Behaviour: Of mice and man-eaters
The sexual behaviour of female mice can be altered dramatically by almost literally flicking a switch at the periphery of their brain. Disrupting the function of a sensory organ called the vomeronasal organ (VNO) causes female mice to display strikingly masculine sexual behaviours – such as mounting, pelvic thrust and solicitation.
It is thought that sex differences in mammalian behaviour arise as a result of exposure to hormones in the womb, which shape the development of either male- or female-specific neural circuits. The evidence Catherine Dulac and colleagues present in a study. They observed the behaviour of female mice after genetic or physical lesion of the VNO, and report that the mice display sexual and courtship behaviours that are uniquely male. The authors report that the lesioned female mice also show a reduction in female-specific behaviours such as nesting.
These results suggest that, in mice at least, the neural circuitry underlying masculine behaviour surprisingly still exists in adult females. This implies a new model of sex differences in behaviour, in which male and female circuits co-exist in the brains of both sexes and are switched on or off by sensory input such as the pheromones detected by the VNO.
Author contact:
Catherine Dulac (Harvard University, Cambridge, MA, USA)
Tel: +1 617 495 7893; E-mail: dulac@fas.harvard.edu
Marc Breedlove (Michigan State University, East Lansing, MI, USA) N&V author
Tel: +1 517 355 1749; E-mail: breedsm@msu.edu
Monday, August 06, 2007
Cancer: Gene reduces severity of lung cancer
A gene known to aid suppression of some tumours is shown to reduce the aggression of lung cancers along with the risk of metastasis. This demonstrates that Lkb1 loss, combined with the mutation of another factor, Kras, in a mouse model, causes more aggressive tumours to arise.
LKB1 is a tumour suppressor gene and is often found to be mutated in patients with Peutz–Jeghers syndrome, who have an increased incidence of cancer. Kras mutation and p53 loss lead to lung cancer in a mouse model, but Kwok-Kin Wong and colleagues found that, when combined with Lkb1 mutation, not only were tumours more aggressive but they were more likely to develop into squamous and large-cell carcinomas of the lung. This report also identifies LKB1 mutations in human lung cancers classified as squamous carcinomas.
Thus, LKB1 loss may be a marker for predicting disease development and spread, and the pathways regulated by LKB1 represent possible therapeutic targets.
Author contact:
Kwok-Kin Wong (Dana Farber Cancer Institute, Boston, MA, USA)
Tel: +1 617 632 6084; E-mail: kwong1@partners.org
A gene known to aid suppression of some tumours is shown to reduce the aggression of lung cancers along with the risk of metastasis. This demonstrates that Lkb1 loss, combined with the mutation of another factor, Kras, in a mouse model, causes more aggressive tumours to arise.
LKB1 is a tumour suppressor gene and is often found to be mutated in patients with Peutz–Jeghers syndrome, who have an increased incidence of cancer. Kras mutation and p53 loss lead to lung cancer in a mouse model, but Kwok-Kin Wong and colleagues found that, when combined with Lkb1 mutation, not only were tumours more aggressive but they were more likely to develop into squamous and large-cell carcinomas of the lung. This report also identifies LKB1 mutations in human lung cancers classified as squamous carcinomas.
Thus, LKB1 loss may be a marker for predicting disease development and spread, and the pathways regulated by LKB1 represent possible therapeutic targets.
Author contact:
Kwok-Kin Wong (Dana Farber Cancer Institute, Boston, MA, USA)
Tel: +1 617 632 6084; E-mail: kwong1@partners.org
CHEMICAL BIOLOGY : An unfolding antibiotics story
Scientists have identified the way an unusual antibiotic works. Lactivicin and similar molecules are a class of antibiotics that are unique because they do not contain a beta-lactam ring. This is significant because antibiotic resistance is frequently tied to the beta-lactam rings of the more common antibiotics, like penicillin.
Now a team led by Christopher Schofield and colleagues specifically demonstrate that lactivicin is an effective antibiotic against penicillin-resistant bacteria isolated from human patients. In addition, the authors explain lactivicin’s unique behaviour by providing a crystal structure of the compound bound to its protein target, in which the two rings of the compound have been opened. This discovery will undoubtedly lead to the design of new effective antibiotics that can be applied to resistant bacteria.
Author contact:
Christopher Schofield (Chemistry Research Laboratory, Oxford, UK)
Tel: +44 1865 275 625, Email: christopher.schofield@chem.ox.ac.uk
Scientists have identified the way an unusual antibiotic works. Lactivicin and similar molecules are a class of antibiotics that are unique because they do not contain a beta-lactam ring. This is significant because antibiotic resistance is frequently tied to the beta-lactam rings of the more common antibiotics, like penicillin.
Now a team led by Christopher Schofield and colleagues specifically demonstrate that lactivicin is an effective antibiotic against penicillin-resistant bacteria isolated from human patients. In addition, the authors explain lactivicin’s unique behaviour by providing a crystal structure of the compound bound to its protein target, in which the two rings of the compound have been opened. This discovery will undoubtedly lead to the design of new effective antibiotics that can be applied to resistant bacteria.
Author contact:
Christopher Schofield (Chemistry Research Laboratory, Oxford, UK)
Tel: +44 1865 275 625, Email: christopher.schofield@chem.ox.ac.uk
IMMUNOLOGY : How inflammatory lymphocytes develop
Researchers describe the development of a unique type of white blood cell and how this development is different in humans and mice. These cells are required for healthy gut biology but also, in other areas of the body such as the brain, are associated with dangerous inflammation.
Two groups, one led by Rene Waal de Malefyt and the other by Federica Sallusto, evaluated how human T cells develop into TH-17 cells, which make several inflammatory immune proteins associated with inflammation and with fighting certain microbial infections. Both groups found that the requirements for TH-17 cell development in humans and mice are different, a surprising finding that has great significance because mice are commonly used to study human disease. A third study led by Michael Lohoff evaluated TH-17 cells in mice only, and found that a specific cellular protein called interferon regulatory factor 4 is absolutely required for their development.
These three studies provide considerable insight into how TH-17 inflammatory cells are produced in both mice and humans. Understanding the unique developmental requirements for these inflammatory T cells may help to explain the cause of inflammatory diseases of the brain and gut in humans.
Author contacts:
Rene Waal de Malefyt (Schering-Plough Biopharma, Palo Alto, CA, USA)
Tel: +1 650 496 1164; E-mail: rene.de.waal.malefyt@spcorp.com Author paper [5]
Federica Sallusto (Institute for Research in Biomedicine, Bellinzona, Switzerland)
Tel: +41 91 820 0315; E-mail: federica.sallusto@irb.unisi.ch Author paper [6]
Michael Lohoff (Marburg University, Germany) Author paper [7]
Tel: +49 6421 286 6455; E-mail: lohoff@med.uni-marburg.de
Researchers describe the development of a unique type of white blood cell and how this development is different in humans and mice. These cells are required for healthy gut biology but also, in other areas of the body such as the brain, are associated with dangerous inflammation.
Two groups, one led by Rene Waal de Malefyt and the other by Federica Sallusto, evaluated how human T cells develop into TH-17 cells, which make several inflammatory immune proteins associated with inflammation and with fighting certain microbial infections. Both groups found that the requirements for TH-17 cell development in humans and mice are different, a surprising finding that has great significance because mice are commonly used to study human disease. A third study led by Michael Lohoff evaluated TH-17 cells in mice only, and found that a specific cellular protein called interferon regulatory factor 4 is absolutely required for their development.
These three studies provide considerable insight into how TH-17 inflammatory cells are produced in both mice and humans. Understanding the unique developmental requirements for these inflammatory T cells may help to explain the cause of inflammatory diseases of the brain and gut in humans.
Author contacts:
Rene Waal de Malefyt (Schering-Plough Biopharma, Palo Alto, CA, USA)
Tel: +1 650 496 1164; E-mail: rene.de.waal.malefyt@spcorp.com Author paper [5]
Federica Sallusto (Institute for Research in Biomedicine, Bellinzona, Switzerland)
Tel: +41 91 820 0315; E-mail: federica.sallusto@irb.unisi.ch Author paper [6]
Michael Lohoff (Marburg University, Germany) Author paper [7]
Tel: +49 6421 286 6455; E-mail: lohoff@med.uni-marburg.de
Structural & Molecular Biology - Seeing transcription in living colour
A closer look is taken at gene transcription in living organisms. Transcription by RNA polymerase II, the enzyme that transcribes DNA into messenger RNAs, is at the core of gene expression and is a major focus of biological regulatory mechanisms. Much of what is known about transcription comes from test tube experiments (in vitro) with purified components but little is known about how RNA polymerase works in vivo.
Robert Singer and co-workers have now taken the analysis of the mechanism of gene transcription in higher organisms to a new level by using advanced fluorescence imaging techniques to measure quantitatively the kinetics of gene transcription by RNA polymerase II in living mammalian cells. The ultimate goal of this work is a quantitative model of gene transcription in vivo. They find several novel and unexpected features concerning the nature of the in vivo transcription.
First, they conclude that only a surprisingly small fraction of RNA polymerases that bind to the start of a gene, amounting to about 1%, actually go on to transcribe the gene and produce a messenger RNA. Second, they find that RNA polymerases transcribe more rapidly than previously thought, often pausing for prolonged periods. This study represents a critical milestone on the way to building a quantitative understanding of the mechanism of transcription in single live cells.
Author contact:
Robert Singer (Albert Einstein College of Medicine, New York, NY, USA)
Tel: + 1 718 430 8646; E-mail: rhsinger@aecom.yu.edu
A closer look is taken at gene transcription in living organisms. Transcription by RNA polymerase II, the enzyme that transcribes DNA into messenger RNAs, is at the core of gene expression and is a major focus of biological regulatory mechanisms. Much of what is known about transcription comes from test tube experiments (in vitro) with purified components but little is known about how RNA polymerase works in vivo.
Robert Singer and co-workers have now taken the analysis of the mechanism of gene transcription in higher organisms to a new level by using advanced fluorescence imaging techniques to measure quantitatively the kinetics of gene transcription by RNA polymerase II in living mammalian cells. The ultimate goal of this work is a quantitative model of gene transcription in vivo. They find several novel and unexpected features concerning the nature of the in vivo transcription.
First, they conclude that only a surprisingly small fraction of RNA polymerases that bind to the start of a gene, amounting to about 1%, actually go on to transcribe the gene and produce a messenger RNA. Second, they find that RNA polymerases transcribe more rapidly than previously thought, often pausing for prolonged periods. This study represents a critical milestone on the way to building a quantitative understanding of the mechanism of transcription in single live cells.
Author contact:
Robert Singer (Albert Einstein College of Medicine, New York, NY, USA)
Tel: + 1 718 430 8646; E-mail: rhsinger@aecom.yu.edu
Virus-based screen for ion channel modulators
A virus-based method that screens for chemical or genetically-encoded inhibitors of ion channels. Ion channels are cell membrane-spanning proteins that, when activated, allow the influx of ions. They encompass a large family of over 400 proteins and play key roles in maintaining cellular function. While blocking their activity has proven useful for certain medical applications, these drugs usually elicit severe side effects due to their wide range action and lack of selectivity for the intended cell alone.
Joseph Glorioso and colleagues wanted to find more specific channel modulators and set up a virus-based screen in which the virus level is an indicator for inhibitor efficacy. They reasoned that overexpression of an ion channel in cells via a virus would be detrimental to the cell and consequently impede viral replication; while the presence of an inhibitor of channel function would keep the cells healthy and allow replication. The advance over other screens for channel inhibitors is that the technique can easily be adapted to screen for genetically-encoded inhibitors by coinfection of a second virus that encodes the inhibitor. The inhibitor’s DNA can then be easily retrieved from the viral genome.
This method can easily be scaled up to screen whole DNA libraries that express a wide range of potential channel modulators. These genetically encoded inhibitors will help reveal the biology behind channel regulation and are likely to lead to more specific inhibitors.
Author contact:
Joseph Glorioso (University of Pittsburgh School of Medicine, PA, USA)
Tel: +1 412 648 8105; E-mail: glorioso@pitt.edu
A virus-based method that screens for chemical or genetically-encoded inhibitors of ion channels. Ion channels are cell membrane-spanning proteins that, when activated, allow the influx of ions. They encompass a large family of over 400 proteins and play key roles in maintaining cellular function. While blocking their activity has proven useful for certain medical applications, these drugs usually elicit severe side effects due to their wide range action and lack of selectivity for the intended cell alone.
Joseph Glorioso and colleagues wanted to find more specific channel modulators and set up a virus-based screen in which the virus level is an indicator for inhibitor efficacy. They reasoned that overexpression of an ion channel in cells via a virus would be detrimental to the cell and consequently impede viral replication; while the presence of an inhibitor of channel function would keep the cells healthy and allow replication. The advance over other screens for channel inhibitors is that the technique can easily be adapted to screen for genetically-encoded inhibitors by coinfection of a second virus that encodes the inhibitor. The inhibitor’s DNA can then be easily retrieved from the viral genome.
This method can easily be scaled up to screen whole DNA libraries that express a wide range of potential channel modulators. These genetically encoded inhibitors will help reveal the biology behind channel regulation and are likely to lead to more specific inhibitors.
Author contact:
Joseph Glorioso (University of Pittsburgh School of Medicine, PA, USA)
Tel: +1 412 648 8105; E-mail: glorioso@pitt.edu
Friday, August 03, 2007
Fast and low cost Photographic Method
Researchers in the Philippines have revealed that a fast and low cost photographic method is just as effective as the more expensive videographic method in assessing the condition of coral reef benthic communities. Comparison Between Videographic and Photographic Methods in Assessing Coral Reef Benthic Communities by Patrick C. Cabaitan, Wilfredo Y. Licuanan, and Edgardo D. Gomez
Continuous degradation of coral reefs creates a need for techniques that can assess reef conditions rapidly and efficiently. The Video transect survey is commonly used to monitor benthic communities because it is rapid, provides a permanent historical record of the data, and can help minimize observer bias. But this technology is not readily available to most research institutions because of its high cost.
In this study, a low cost photographic method was used to survey benthic communities in the subtidal flat inside Caniogan Marine Sanctuary, Tondol, Anda, Pangasinan. Results from this method were then compared with those from videographic methods.
For the low cost photographic method, ten regularly spaced shots were directly taken from each 5m transect, totaling to 100 frames. Ten 5m x ~0.25m video transects were also run over each of the twenty selected patch reefs, covering the whole demarcated area. Ten regularly spaced frames were then taken from the videotape in each transect, totaling to 100 frames in each patch reef. In the laboratory, all frames were analyzed using the systematic 5-point method.
Both methods yielded comparable time in field data collection. However, videographic method demanded more time in post-collection computer analysis and it is more costly due to the required additional computer software and hardware. Pairwise T-tests and Analysis of similarities (ANOSIM) revealed that both methods gathered similar results in terms of the diversity (P>0.05) and in terms of percentage composition (P>0.05) of life forms recorded, suggesting that both can be used interchangeably in benthic community surveys.
(Science Diliman)E-mail: rduo.ovcrd@up.edu.ph
Telephone:+63 2 - 927-2309
Fax:+63 2 - 927-2568
Researchers in the Philippines have revealed that a fast and low cost photographic method is just as effective as the more expensive videographic method in assessing the condition of coral reef benthic communities. Comparison Between Videographic and Photographic Methods in Assessing Coral Reef Benthic Communities by Patrick C. Cabaitan, Wilfredo Y. Licuanan, and Edgardo D. Gomez
Continuous degradation of coral reefs creates a need for techniques that can assess reef conditions rapidly and efficiently. The Video transect survey is commonly used to monitor benthic communities because it is rapid, provides a permanent historical record of the data, and can help minimize observer bias. But this technology is not readily available to most research institutions because of its high cost.
In this study, a low cost photographic method was used to survey benthic communities in the subtidal flat inside Caniogan Marine Sanctuary, Tondol, Anda, Pangasinan. Results from this method were then compared with those from videographic methods.
For the low cost photographic method, ten regularly spaced shots were directly taken from each 5m transect, totaling to 100 frames. Ten 5m x ~0.25m video transects were also run over each of the twenty selected patch reefs, covering the whole demarcated area. Ten regularly spaced frames were then taken from the videotape in each transect, totaling to 100 frames in each patch reef. In the laboratory, all frames were analyzed using the systematic 5-point method.
Both methods yielded comparable time in field data collection. However, videographic method demanded more time in post-collection computer analysis and it is more costly due to the required additional computer software and hardware. Pairwise T-tests and Analysis of similarities (ANOSIM) revealed that both methods gathered similar results in terms of the diversity (P>0.05) and in terms of percentage composition (P>0.05) of life forms recorded, suggesting that both can be used interchangeably in benthic community surveys.
(Science Diliman)E-mail: rduo.ovcrd@up.edu.ph
Telephone:+63 2 - 927-2309
Fax:+63 2 - 927-2568
Commencement of Second Life Joint Research
Keio University and Dentsu Announce the Commencement of Second Life Joint Research -- Keio University Second Life Campus to Hold Japan’s First Metaverse-Based University Course --
Keio University (President: Yuichiro Anzai; Head Office: Tokyo) and Dentsu Inc. (President & COO: Tatsuyoshi Takashima; Head Office: Tokyo; Capital: 58,967.1 million yen) announced today that they will conduct joint research covering a number of issues relating to metaverses, and particularly Second Life® (See Note 1), a 3-D virtual community that has gained worldwide popularity. Planned research topics include issues on social systems, distance learning and continuing education, the potential for marketing activities within a metaverse, and the potential for technological development.
As a facility to carry out their joint research, Keio University and Dentsu plan to establish the Keio University Second Life® Campus within Virtual Tokyo (See Note 2), which Dentsu will open in August this year as a virtual city within the Second Life® metaverse. Through demonstration tests conducted in the Keio University Second Life® Campus, the joint research group aims to contribute to finding solutions to a range of issues relating to virtual societies. In addition, the joint research group plans to study the potential for educational content within 3-D virtual communities and consider various aspects about the future of education.
Outline of the Joint Research
Keio University Dentsu and will establish a joint research facility, Keio University Second Life® Campus, within Virtual Tokyo. Virtual land for the campus as well as authority to manage the campus will be provided by Dentsu to Keio University Research Institute at SFC. The research group will utilize this land to conduct their research. The land area allocated for the campus will be 1 SIM, which is the standard land unit in the Second Life® metaverse and is equal to 256 x 256 meters (16 acres).
Within this virtual space, the research group will conduct the following research
(1) Within the Keio University Second Life® Campus, the research group plans to explore new education possibilities by utilizing the experience Keio University has built up in distance teaching methods, for instance, through operating the Keio University SFC Global Campus (See Note 3). Utilizing the educational video content Keio University has accumulated until now, the research group plans to examine the
potential for Second Life® in the education field. This will be the first time for a university in Japan to offer lectures from regular university courses within Second Life®.
(2) The research group will conduct research within the Keio University Second Life® Campus and Virtual Tokyo on the behavior of Second Life® consumers and economic activities such as virtual currencies. Utilizing the Linden Dollar, the virtual currency circulating within Second Life®, the research group will study such areas as the virtual economic mechanism, analysis of consumer behavior, and legal or ethical issues within the metaverse. The research group also plans to collaborate with the makers of Second Life®, Linden Labs, in research on technical aspects of Second Life®.
Research Group Participants
A number of researchers from the Keio Research Institute at SFC, based at the Keio University Shonan Fujisawa Campus, will participate in the research. These researchers include such specialists in Internet, digital media, and other social applications for new technologies as Professor Jun Murai and Professor Masahiko Inakage from the Faculty of Environment and Information Studies; Professor Ikuyo Kaneko from the Graduate School of Media and Governance; and Professor Jiro Kokuryo from the Faculty of Policy Management.
From Dentsu, specialists in marketing and media content will participate in the joint research. Dentsu Group companies will also provide cooperation and support for the construction and operation of the virtual campus.
Note 1: Second Life® 3-D virtual community
Second Life® is a 3-D virtual community, created and operated by U.S.-based company Linden Lab, with a rapidly growing population from 100 countries around the globe. Residents of the Second Life®
metaverse themselves create and build the world that includes homes, vehicles, nightclubs, stores, landscapes, clothing, and games. The Second Life® Grid is a sophisticated development platform created by Linden Lab, a company founded in 1999 by Philip Rosedale, to create a revolutionary new form of shared 3-D experience. The former CTO of RealNetworks, Rosedale pioneered the development of many of today’s streaming media technologies, including RealVideo. In April 2003, noted software pioneer Mitch Kapor, founder of Lotus Development Corporation, was named Chairman. In 2006, Philip Rosedale and Linden Lab received WIRED’s Rave Award for Innovation in Business. Based in San Francisco, Linden Lab employs a senior team bringing together deep expertise in physics, 3-D graphics and networking.
Note 2: Virtual Tokyo
Virtual Tokyo is a comprehensive virtual city being created based on the concept of
"Vitality–Future–Tokyo.” It is a collaboration between Dentsu and Tetsuya Mizuguchi, CCO of Q Entertainment Inc. Virtual Tokyo will condense the images and energy of Tokyo and disseminate to the rest of the world the pop culture created within it. Virtual Tokyo will not be a one-way content source but provide a place for creators (users) to actively participate. By doing so, Dentsu wishes to recreate the
dynamism of Tokyo—an ever-changing city—within Second Life®. Virtual Tokyo will cover 85 hectares, making it one of the largest cities within Second Life®. It will comprise various zones, including a public zone with stadiums and museums, and other zones such as those focusing on education, experiential activities and commerce.
Note 3: Keio University SFC Global Campus (http://gc.sfc.keio.ac.jp/)
The Keio University Shonan Fujisawa Campus (SFC-GC) provides lectures that are shared globally and accessed by learners outside the university. It was opened in 2002 and from the 2002 autumn semester to the 2007 spring semester, 297 courses (each comprising 13 lectures) have been made available for access as approximately 4,000 video material content items. At present, Keio University runs the distance learning program, which allows people who are not Keio University students to utilize SFC-GC to enroll in courses. Furthermore, the content, which is provided free of charge, may be accessed without the need for user registration.
Contact: Rina Tanaka and Aiko Nakajima
Office of Communications and Public Relations
Keio University
Telephone: (813) 5427-1541
E-mail: m-koho@adst.keio.ac.jp
Keio University and Dentsu Announce the Commencement of Second Life Joint Research -- Keio University Second Life Campus to Hold Japan’s First Metaverse-Based University Course --
Keio University (President: Yuichiro Anzai; Head Office: Tokyo) and Dentsu Inc. (President & COO: Tatsuyoshi Takashima; Head Office: Tokyo; Capital: 58,967.1 million yen) announced today that they will conduct joint research covering a number of issues relating to metaverses, and particularly Second Life® (See Note 1), a 3-D virtual community that has gained worldwide popularity. Planned research topics include issues on social systems, distance learning and continuing education, the potential for marketing activities within a metaverse, and the potential for technological development.
As a facility to carry out their joint research, Keio University and Dentsu plan to establish the Keio University Second Life® Campus within Virtual Tokyo (See Note 2), which Dentsu will open in August this year as a virtual city within the Second Life® metaverse. Through demonstration tests conducted in the Keio University Second Life® Campus, the joint research group aims to contribute to finding solutions to a range of issues relating to virtual societies. In addition, the joint research group plans to study the potential for educational content within 3-D virtual communities and consider various aspects about the future of education.
Outline of the Joint Research
Keio University Dentsu and will establish a joint research facility, Keio University Second Life® Campus, within Virtual Tokyo. Virtual land for the campus as well as authority to manage the campus will be provided by Dentsu to Keio University Research Institute at SFC. The research group will utilize this land to conduct their research. The land area allocated for the campus will be 1 SIM, which is the standard land unit in the Second Life® metaverse and is equal to 256 x 256 meters (16 acres).
Within this virtual space, the research group will conduct the following research
(1) Within the Keio University Second Life® Campus, the research group plans to explore new education possibilities by utilizing the experience Keio University has built up in distance teaching methods, for instance, through operating the Keio University SFC Global Campus (See Note 3). Utilizing the educational video content Keio University has accumulated until now, the research group plans to examine the
potential for Second Life® in the education field. This will be the first time for a university in Japan to offer lectures from regular university courses within Second Life®.
(2) The research group will conduct research within the Keio University Second Life® Campus and Virtual Tokyo on the behavior of Second Life® consumers and economic activities such as virtual currencies. Utilizing the Linden Dollar, the virtual currency circulating within Second Life®, the research group will study such areas as the virtual economic mechanism, analysis of consumer behavior, and legal or ethical issues within the metaverse. The research group also plans to collaborate with the makers of Second Life®, Linden Labs, in research on technical aspects of Second Life®.
Research Group Participants
A number of researchers from the Keio Research Institute at SFC, based at the Keio University Shonan Fujisawa Campus, will participate in the research. These researchers include such specialists in Internet, digital media, and other social applications for new technologies as Professor Jun Murai and Professor Masahiko Inakage from the Faculty of Environment and Information Studies; Professor Ikuyo Kaneko from the Graduate School of Media and Governance; and Professor Jiro Kokuryo from the Faculty of Policy Management.
From Dentsu, specialists in marketing and media content will participate in the joint research. Dentsu Group companies will also provide cooperation and support for the construction and operation of the virtual campus.
Note 1: Second Life® 3-D virtual community
Second Life® is a 3-D virtual community, created and operated by U.S.-based company Linden Lab, with a rapidly growing population from 100 countries around the globe. Residents of the Second Life®
metaverse themselves create and build the world that includes homes, vehicles, nightclubs, stores, landscapes, clothing, and games. The Second Life® Grid is a sophisticated development platform created by Linden Lab, a company founded in 1999 by Philip Rosedale, to create a revolutionary new form of shared 3-D experience. The former CTO of RealNetworks, Rosedale pioneered the development of many of today’s streaming media technologies, including RealVideo. In April 2003, noted software pioneer Mitch Kapor, founder of Lotus Development Corporation, was named Chairman. In 2006, Philip Rosedale and Linden Lab received WIRED’s Rave Award for Innovation in Business. Based in San Francisco, Linden Lab employs a senior team bringing together deep expertise in physics, 3-D graphics and networking.
Note 2: Virtual Tokyo
Virtual Tokyo is a comprehensive virtual city being created based on the concept of
"Vitality–Future–Tokyo.” It is a collaboration between Dentsu and Tetsuya Mizuguchi, CCO of Q Entertainment Inc. Virtual Tokyo will condense the images and energy of Tokyo and disseminate to the rest of the world the pop culture created within it. Virtual Tokyo will not be a one-way content source but provide a place for creators (users) to actively participate. By doing so, Dentsu wishes to recreate the
dynamism of Tokyo—an ever-changing city—within Second Life®. Virtual Tokyo will cover 85 hectares, making it one of the largest cities within Second Life®. It will comprise various zones, including a public zone with stadiums and museums, and other zones such as those focusing on education, experiential activities and commerce.
Note 3: Keio University SFC Global Campus (http://gc.sfc.keio.ac.jp/)
The Keio University Shonan Fujisawa Campus (SFC-GC) provides lectures that are shared globally and accessed by learners outside the university. It was opened in 2002 and from the 2002 autumn semester to the 2007 spring semester, 297 courses (each comprising 13 lectures) have been made available for access as approximately 4,000 video material content items. At present, Keio University runs the distance learning program, which allows people who are not Keio University students to utilize SFC-GC to enroll in courses. Furthermore, the content, which is provided free of charge, may be accessed without the need for user registration.
Contact: Rina Tanaka and Aiko Nakajima
Office of Communications and Public Relations
Keio University
Telephone: (813) 5427-1541
E-mail: m-koho@adst.keio.ac.jp
Climate change: Brown haze spells bad news
The haze of air pollution over the Indian Ocean may be causing as much lower atmospheric warming as the recent increase in anthropogenic greenhouse gases.
During 18 missions, Veerabhadran Ramanathan and colleagues simultaneously flew three lightweight unmanned aerial vehicles below, into and above the polluted ‘Brown Clouds’ over the Indian Ocean. Tiny instruments were deployed to measure aerosol concentrations, soot amount and solar fluxes, allowing the team to calculate atmospheric solar heating rates. Using model simulations, they conclude that atmospheric Brown Clouds enhance lower atmospheric solar heating by around 50 per cent.
Atmospheric Brown Clouds consist of a mixture of light-absorbing and light-scattering aerosols and so contribute both to atmospheric solar heating and to surface cooling. The combined effects are thought to have masked up to 50 per cent of the global warming attributed to the recent, rapid rise in greenhouse gases. This study helps to tease out the effects of atmospheric solar heating.
CONTACT
Veerabhadran Ramanathan (University of California San Diego, La Jolla, CA, USA)
Tel: +1 858 337 3114; E-mail: vram@fiji.ucsd.edu or vraman000@hotmail.com
Peter Pilewskie (University of Colorado Boulder, CO, USA) N&V author
Tel: +1 303 492 5724; E-mail: peter.pilewskie@lasp.colorado.edu
The haze of air pollution over the Indian Ocean may be causing as much lower atmospheric warming as the recent increase in anthropogenic greenhouse gases.
During 18 missions, Veerabhadran Ramanathan and colleagues simultaneously flew three lightweight unmanned aerial vehicles below, into and above the polluted ‘Brown Clouds’ over the Indian Ocean. Tiny instruments were deployed to measure aerosol concentrations, soot amount and solar fluxes, allowing the team to calculate atmospheric solar heating rates. Using model simulations, they conclude that atmospheric Brown Clouds enhance lower atmospheric solar heating by around 50 per cent.
Atmospheric Brown Clouds consist of a mixture of light-absorbing and light-scattering aerosols and so contribute both to atmospheric solar heating and to surface cooling. The combined effects are thought to have masked up to 50 per cent of the global warming attributed to the recent, rapid rise in greenhouse gases. This study helps to tease out the effects of atmospheric solar heating.
CONTACT
Veerabhadran Ramanathan (University of California San Diego, La Jolla, CA, USA)
Tel: +1 858 337 3114; E-mail: vram@fiji.ucsd.edu or vraman000@hotmail.com
Peter Pilewskie (University of Colorado Boulder, CO, USA) N&V author
Tel: +1 303 492 5724; E-mail: peter.pilewskie@lasp.colorado.edu
Earthquakes: Love and stress
Non-volcanic tremor and slip along a plate boundary can be triggered by shear stress, rather than fluid movement.The analysis of seismic data has revealed long-duration, low-amplitude tremor, similar to that seen below active volcanoes, but associated with plate tectonic boundaries, rather than volcanoes. Episodes of tremors and slow slip have been observed to last up to months, and can be associated with as much deformation as a magnitude-7 earthquake. Although observations of this type of tremor are increasing, the mechanism behind it remains unclear, with some researchers pointing towards slip along the plate interface, and others the movement of fluids.
Justin Rubinstein and colleagues examined seismic recordings associated with the 2002 Denali earthquake and found clear evidence of bursts of tremor having been triggered within the Cascadia subduction zone near Vancouver Island, Canada. These episodes seem to be triggered when the Love wave (surface seismic wave) displacements were to the southwest — parallel to the direction of plate convergence. They conclude that the tremor and possibly slow-slip events can be induced by shear stress increases along the subduction interface.
CONTACT
Justin Rubinstein (University of Washington, Seattle, WA, USA)
Tel: +1 206 685 7563; E-mail: justin@ess.washington.edu
Non-volcanic tremor and slip along a plate boundary can be triggered by shear stress, rather than fluid movement.The analysis of seismic data has revealed long-duration, low-amplitude tremor, similar to that seen below active volcanoes, but associated with plate tectonic boundaries, rather than volcanoes. Episodes of tremors and slow slip have been observed to last up to months, and can be associated with as much deformation as a magnitude-7 earthquake. Although observations of this type of tremor are increasing, the mechanism behind it remains unclear, with some researchers pointing towards slip along the plate interface, and others the movement of fluids.
Justin Rubinstein and colleagues examined seismic recordings associated with the 2002 Denali earthquake and found clear evidence of bursts of tremor having been triggered within the Cascadia subduction zone near Vancouver Island, Canada. These episodes seem to be triggered when the Love wave (surface seismic wave) displacements were to the southwest — parallel to the direction of plate convergence. They conclude that the tremor and possibly slow-slip events can be induced by shear stress increases along the subduction interface.
CONTACT
Justin Rubinstein (University of Washington, Seattle, WA, USA)
Tel: +1 206 685 7563; E-mail: justin@ess.washington.edu
Neuroscience: Deep brain stimulation in a minimally conscious state
The responses of a single patient in a minimally conscious state have improved with deep brain stimulation.During this intervention, the patient’s arousal level and motor control increased to the point that he was able to chew and swallow food.
‘Minimally conscious state’ refers to a level of consciousness characterized by intermittent evidence of awareness of oneself or the environment, and is distinct from persistent vegetative state or coma. At present there are no reliable means for improving recovery from this extended loss of consciousness, which can occur following traumatic brain injury, although recent evidence suggests some brain activity may be preserved in minimally conscious patients. In the current study, Nicholas Schiff and colleagues implanted electrodes into the brain of a 38-year-old male, six years after he suffered a severe brain injury that resulted in a minimally conscious state. The electrodes were used to stimulate an area known as the thalamus, on both sides of the brain, which has been suggested to have a role in arousal. The authors report that during periods of stimulation, the frequency of communicative behaviours, functional limb control and oral feeding increased.
The authors caution that the extent to which their results might apply to other patients is unknown, and that expectations raised by their findings should be tempered — the specific injury suffered and its effects on responsiveness will not be shared by all patients in a minimally conscious state. The present findings should, however, motivate further research into the mechanisms of recovery, as their replication could have important implications for clinical practice.
CONTACT
Nicholas Schiff (Weill Cornell Medical College, New York, NY, USA)
Joseph Fins (Weill Cornell Medical College, New York, NY, USA)
Ali Rezai (Cleveland Clinic Foundation, OH, USA)
Joseph Giacino (JFK Johnson Rehabilitation Institute / New Jersey Neuroscience Institute, Edison, NJ, USA)
The responses of a single patient in a minimally conscious state have improved with deep brain stimulation.During this intervention, the patient’s arousal level and motor control increased to the point that he was able to chew and swallow food.
‘Minimally conscious state’ refers to a level of consciousness characterized by intermittent evidence of awareness of oneself or the environment, and is distinct from persistent vegetative state or coma. At present there are no reliable means for improving recovery from this extended loss of consciousness, which can occur following traumatic brain injury, although recent evidence suggests some brain activity may be preserved in minimally conscious patients. In the current study, Nicholas Schiff and colleagues implanted electrodes into the brain of a 38-year-old male, six years after he suffered a severe brain injury that resulted in a minimally conscious state. The electrodes were used to stimulate an area known as the thalamus, on both sides of the brain, which has been suggested to have a role in arousal. The authors report that during periods of stimulation, the frequency of communicative behaviours, functional limb control and oral feeding increased.
The authors caution that the extent to which their results might apply to other patients is unknown, and that expectations raised by their findings should be tempered — the specific injury suffered and its effects on responsiveness will not be shared by all patients in a minimally conscious state. The present findings should, however, motivate further research into the mechanisms of recovery, as their replication could have important implications for clinical practice.
CONTACT
Nicholas Schiff (Weill Cornell Medical College, New York, NY, USA)
Joseph Fins (Weill Cornell Medical College, New York, NY, USA)
Ali Rezai (Cleveland Clinic Foundation, OH, USA)
Joseph Giacino (JFK Johnson Rehabilitation Institute / New Jersey Neuroscience Institute, Edison, NJ, USA)
Tunable light sources lose their mirrors
A tunable infrared source that is ‘mirror-free’ and easy to align has been experimentally demonstrated for the first time and could result in a new source of light that is small, inexpensive and convenient to use.
Optical parametric oscillators (OPOs) are useful in the fields of spectroscopy, chemistry and other disciplines because they offer tunable coherent light – narrow-bandwidth light that has radiation with all the waves vibrating in phase – with wavelengths ranging from 2 to 10 micrometres, filling gaps that can’t be served by other sources. Unfortunately, conventional designs are hard to align and miniaturize as, apart from a nonlinear crystal, they also contain a pair of mirrors that need to be very precisely located. Although ‘mirrorless’ designs have been theoretically proposed in the past, an experimental prototype has not been demonstrated to date.
Carlota Canalias and Valdas Pasiskevicius have built a device that is highly compact, easy to align and has the ability to tune wavelengths with high precision in the near- and mid-infrared wavelengths. Their OPO relies solely on subtle modifications to the nonlinear crystal itself, rather than mirrors. The result is a new breed of OPO that consists of just the nonlinear crystal and a pump laser.
Author contact:
Carlota Canalias (Royal Institute of Technology, Stockholm, Sweden)
Tel: +46 855 378 159; E-mail: cc@laserphysics.kth.se
A tunable infrared source that is ‘mirror-free’ and easy to align has been experimentally demonstrated for the first time and could result in a new source of light that is small, inexpensive and convenient to use.
Optical parametric oscillators (OPOs) are useful in the fields of spectroscopy, chemistry and other disciplines because they offer tunable coherent light – narrow-bandwidth light that has radiation with all the waves vibrating in phase – with wavelengths ranging from 2 to 10 micrometres, filling gaps that can’t be served by other sources. Unfortunately, conventional designs are hard to align and miniaturize as, apart from a nonlinear crystal, they also contain a pair of mirrors that need to be very precisely located. Although ‘mirrorless’ designs have been theoretically proposed in the past, an experimental prototype has not been demonstrated to date.
Carlota Canalias and Valdas Pasiskevicius have built a device that is highly compact, easy to align and has the ability to tune wavelengths with high precision in the near- and mid-infrared wavelengths. Their OPO relies solely on subtle modifications to the nonlinear crystal itself, rather than mirrors. The result is a new breed of OPO that consists of just the nonlinear crystal and a pump laser.
Author contact:
Carlota Canalias (Royal Institute of Technology, Stockholm, Sweden)
Tel: +46 855 378 159; E-mail: cc@laserphysics.kth.se
Saturday, July 28, 2007
Filipino Physicists Awarded a US Patent for a New Semiconductor Circuit Imaging Technique
A microscope imaging technique for visualizing and analyzing semiconductor integrated circuits developed by a team of scientists from the University of the Philippines’ National Institute of Physics was awarded a patent by the United States Patent and Trademark Office.
Imagine if our computers, cellular phones and other electronic gadgets cease to work due to failures in the circuits that run them. These failures in the minuscule wires that make up the semiconductor integrated circuits embedded in our electronic products must be detected in order to make sure that our prized gadgets function. To detect such failures, an effective technique for visualizing and analyzing circuits has been developed by a team of scientists from the University of the Philippines’ National Institute of Physics (UP NIP), namely: Dr. Ceasar Saloma, Dr. Vincent Ricardo M. Daria and Ms. Jelda Jane C. Miranda. This microscope imaging technique entitled “Method for Generating High Contrast Images of Semiconductor Sites via One-Photon Optical Beam-induced Current (IP OBIC) Imaging and Confocal Reflectance Microscopy” was awarded a patent by the United States Patent and Trademark Office last June 26, 2007.
Saloma, currently Dean of the College of Science of the University of the Philippines, is recipient of prestigious international awards for outstanding scientific work, among them the Galileo Galilei Award from the International Commission on Optics. Daria, Associate Professor at the UP-NIP is one of its most active researchers, and Miranda, who was part of its Experimental Optics Group now works for Intel Corporation. The US patent gives Saloma and his team an exclusive right to commercialize their invention in the United States without fear of infringement. The patent is effective for 20 years after the filing of application in December 09, 2006. For more details on the invention, you may check out the United States Patents and Trademarks Office website at http://patft.uspto.gov/.
The invention combines two existing imaging techniques called confocal reflectance microscopy and 1P-OBIC. It uses computer software to produce a high-contrast image mapping of the semiconductor and metal sites in an integrated circuit. The technique is a major breakthrough in the semiconductor industry. It is particularly useful in the manufacturing of microprocessors, integrated circuits and memories for computers, cellular phones and other electronic devices. Creating sharp visual images of semiconductor integrated circuits is important for failure analysis since one can track which part of the device would produce electrical current when hit by laser beam. The method facilitates accurate identification of semiconductor and metal sites in an integrated circuit. With this technique, defects in the circuit can be detected, thus ensuring quality control of such devices.
The main claims of the patent include a description of a technique that facilitates discrimination of these two types of materials in an integrated circuit. The claims also include a description of the optical layout for a generic confocal microscope that allows for simultaneous acquisition of reflectance confocal image and single-photon optical beam induced current (OBIC) image. Moreover, the patent includes an algorithm and software control for microscopic image acquisition for both confocal and OBIC image.
Applications of the patent extend to a fully integrated microscope system for failure analysis of integrated circuits by improved visualization and mapping of materials in a semiconductor device. The microscope extends to a system for measuring optical beam induced current of semiconductor materials. Further applications of the patent may include the construction of a general purpose Confocal Reflectance microscope system for viewing microscopic objects.
Just last March 16, 2007, another scientist from the National Institute of Physics in the University of the Philippines, Dr. Henry J. Ramos, was awarded a Taiwan patent for his invention entitled “Titanium Nitride Thin Formation on Metal Substrate by Chemical Vapor Deposition in a Magnetized Sheet Plasma Source.” The invention has a wide range of applications: cutting tools manufacturing, and the production of aerospace components, marine hardware, medical devices, and pharmaceutical equipment among others.
-By Jennalyn S. Baraquio and Agnes A. Paculdar
A microscope imaging technique for visualizing and analyzing semiconductor integrated circuits developed by a team of scientists from the University of the Philippines’ National Institute of Physics was awarded a patent by the United States Patent and Trademark Office.
Imagine if our computers, cellular phones and other electronic gadgets cease to work due to failures in the circuits that run them. These failures in the minuscule wires that make up the semiconductor integrated circuits embedded in our electronic products must be detected in order to make sure that our prized gadgets function. To detect such failures, an effective technique for visualizing and analyzing circuits has been developed by a team of scientists from the University of the Philippines’ National Institute of Physics (UP NIP), namely: Dr. Ceasar Saloma, Dr. Vincent Ricardo M. Daria and Ms. Jelda Jane C. Miranda. This microscope imaging technique entitled “Method for Generating High Contrast Images of Semiconductor Sites via One-Photon Optical Beam-induced Current (IP OBIC) Imaging and Confocal Reflectance Microscopy” was awarded a patent by the United States Patent and Trademark Office last June 26, 2007.
Saloma, currently Dean of the College of Science of the University of the Philippines, is recipient of prestigious international awards for outstanding scientific work, among them the Galileo Galilei Award from the International Commission on Optics. Daria, Associate Professor at the UP-NIP is one of its most active researchers, and Miranda, who was part of its Experimental Optics Group now works for Intel Corporation. The US patent gives Saloma and his team an exclusive right to commercialize their invention in the United States without fear of infringement. The patent is effective for 20 years after the filing of application in December 09, 2006. For more details on the invention, you may check out the United States Patents and Trademarks Office website at http://patft.uspto.gov/.
The invention combines two existing imaging techniques called confocal reflectance microscopy and 1P-OBIC. It uses computer software to produce a high-contrast image mapping of the semiconductor and metal sites in an integrated circuit. The technique is a major breakthrough in the semiconductor industry. It is particularly useful in the manufacturing of microprocessors, integrated circuits and memories for computers, cellular phones and other electronic devices. Creating sharp visual images of semiconductor integrated circuits is important for failure analysis since one can track which part of the device would produce electrical current when hit by laser beam. The method facilitates accurate identification of semiconductor and metal sites in an integrated circuit. With this technique, defects in the circuit can be detected, thus ensuring quality control of such devices.
The main claims of the patent include a description of a technique that facilitates discrimination of these two types of materials in an integrated circuit. The claims also include a description of the optical layout for a generic confocal microscope that allows for simultaneous acquisition of reflectance confocal image and single-photon optical beam induced current (OBIC) image. Moreover, the patent includes an algorithm and software control for microscopic image acquisition for both confocal and OBIC image.
Applications of the patent extend to a fully integrated microscope system for failure analysis of integrated circuits by improved visualization and mapping of materials in a semiconductor device. The microscope extends to a system for measuring optical beam induced current of semiconductor materials. Further applications of the patent may include the construction of a general purpose Confocal Reflectance microscope system for viewing microscopic objects.
Just last March 16, 2007, another scientist from the National Institute of Physics in the University of the Philippines, Dr. Henry J. Ramos, was awarded a Taiwan patent for his invention entitled “Titanium Nitride Thin Formation on Metal Substrate by Chemical Vapor Deposition in a Magnetized Sheet Plasma Source.” The invention has a wide range of applications: cutting tools manufacturing, and the production of aerospace components, marine hardware, medical devices, and pharmaceutical equipment among others.
-By Jennalyn S. Baraquio and Agnes A. Paculdar
Breaking the frustration
The crystal structure of an oxide material is directly coupled to its ‘frustrated’ magnetic structure
Researchers from the RIKEN SPring-8 Center in Harima, the Japan Atomic Energy Agency and the universities of Tokyo and Virginia have discovered how changes to the crystal structure of the oxide material HgCr2O4 correlate to its magnetic state.
HgCr2O4 has an intriguing crystal structure where all relevant atoms are arranged in tetrahedra (Fig. 1 - Click on link below). When the interaction between the magnetic atoms at the corners of these tetrahedra is antiferromagnetic, a magnetic state with a zero net ‘moment’ is expected to occur—that is, there should be as many magnetic arrows pointing upwards as downwards. However, the geometry of the tetrahedra means that no perfectly homogeneous distribution of the moments is possible. This is known as ‘geometrically frustrated magnetism’.
To break the frustration, the system compensates for the uneven distribution of magnetic moments by distorting the crystal lattice (Fig. 1a). However, in response to an increasing external magnetic field, the magnetic moments realign and there is a stepwise reduction in crystal distortion (Fig. 1b). Once all magnetic moments are forced to point in the same direction, a perfectly symmetric crystal structure is assumed (Fig. 1c).
As reported in the journal Nature Physics (1), the research team studied the behavior of this material as they applied a slowly increasing magnetic field. They confirmed that the external magnetic field eventually breaks the zero magnetization of the sample and causes the magnetic spins to align along the external field—evidenced by sudden jumps in the sample magnetization followed by plateaus with constant magnetization.
Unlike other materials, HgCr2O4 is uniquely suited for this type of study, as these changes occur in magnetic fields small enough to be generated in experiments. Therefore, “the observation of magnetization plateaus in this compound over a wide range of magnetic fields is novel and a manifestation of the geometrical frustration,” explains Koichi Katsumata from the RIKEN team.
Importantly, the researchers studied for the first time the simultaneous evolution of the material’s crystal structure and found that as the magnetization jumps between the different plateaus, the crystal structure becomes less distorted (Fig. 1). Katsumata is therefore confident that this study “has unveiled the origin of some of the intriguing properties of geometrically frustrated magnets.” In particular, the results allow the validation and refinement of theoretical models describing the interaction between magnetism and crystal structure not only in this compound, but also in related systems.
Reference
1. Matsuda, M., Ueda, H., Kikkawa, A., Tanaka, Y., Katsumata, K., Narumi, Y., Inami, T., Ueda, Y. & Lee, S.-H. Spin-lattice instability to a fractional magnetization state in the spinel HgCr2O4. Nature Physics 3, 397–400 (2007).
The crystal structure of an oxide material is directly coupled to its ‘frustrated’ magnetic structure
Researchers from the RIKEN SPring-8 Center in Harima, the Japan Atomic Energy Agency and the universities of Tokyo and Virginia have discovered how changes to the crystal structure of the oxide material HgCr2O4 correlate to its magnetic state.
HgCr2O4 has an intriguing crystal structure where all relevant atoms are arranged in tetrahedra (Fig. 1 - Click on link below). When the interaction between the magnetic atoms at the corners of these tetrahedra is antiferromagnetic, a magnetic state with a zero net ‘moment’ is expected to occur—that is, there should be as many magnetic arrows pointing upwards as downwards. However, the geometry of the tetrahedra means that no perfectly homogeneous distribution of the moments is possible. This is known as ‘geometrically frustrated magnetism’.
To break the frustration, the system compensates for the uneven distribution of magnetic moments by distorting the crystal lattice (Fig. 1a). However, in response to an increasing external magnetic field, the magnetic moments realign and there is a stepwise reduction in crystal distortion (Fig. 1b). Once all magnetic moments are forced to point in the same direction, a perfectly symmetric crystal structure is assumed (Fig. 1c).
As reported in the journal Nature Physics (1), the research team studied the behavior of this material as they applied a slowly increasing magnetic field. They confirmed that the external magnetic field eventually breaks the zero magnetization of the sample and causes the magnetic spins to align along the external field—evidenced by sudden jumps in the sample magnetization followed by plateaus with constant magnetization.
Unlike other materials, HgCr2O4 is uniquely suited for this type of study, as these changes occur in magnetic fields small enough to be generated in experiments. Therefore, “the observation of magnetization plateaus in this compound over a wide range of magnetic fields is novel and a manifestation of the geometrical frustration,” explains Koichi Katsumata from the RIKEN team.
Importantly, the researchers studied for the first time the simultaneous evolution of the material’s crystal structure and found that as the magnetization jumps between the different plateaus, the crystal structure becomes less distorted (Fig. 1). Katsumata is therefore confident that this study “has unveiled the origin of some of the intriguing properties of geometrically frustrated magnets.” In particular, the results allow the validation and refinement of theoretical models describing the interaction between magnetism and crystal structure not only in this compound, but also in related systems.
Reference
1. Matsuda, M., Ueda, H., Kikkawa, A., Tanaka, Y., Katsumata, K., Narumi, Y., Inami, T., Ueda, Y. & Lee, S.-H. Spin-lattice instability to a fractional magnetization state in the spinel HgCr2O4. Nature Physics 3, 397–400 (2007).
Take your computer for a spin
RIKEN Large spin Hall effect measured at room temperature
RIKEN scientists have accurately measured a tiny voltage produced by segregating electrons according to their spin (1), a result which could help to usher in a new era of spin-based computing.
Conventional computers process and communicate information by shunting electrons around, but store data in the magnetic properties of tiny segments of a spinning disk drive. Yet that magnetism is also due to electrons—as each charged particle spins, it creates a magnetic moment. Electrons can spin ‘up’ or ‘down’, creating opposing poles like a bar magnet, and the burgeoning technology of spintronics uses these two states to represent bits of binary data. As well as storing information, these states can potentially be used to perform calculations.
The spin Hall effect (SHE) provides an important way to control these spinning electrons. The Hall effect itself (identified in 1879 by Edwin Hall) occurs when a magnetic field forces a current of electrons flowing through a flat plate to veer to one side. This causes charge to accumulate on that side of the plate, setting up a voltage across it. In a similar way, the SHE sends spin-up electrons to one side of the plate and spin-down to the other, setting up a ‘spin current’ (Fig. 1 - Click on link below).
Spin current is an important factor in operating future spintronic devices. Ferromagnets are normally used to differentiate spins, but interference between neighboring magnets makes it tricky to build working spintronic devices that way.
“However, if we use SHE, we can generate the spin current without using a ferromagnet,” says Takashi Kimura of RIKEN’s Frontier Research System, Wako. This could allow much easier integration of semiconductor and spintronic devices in the future.
Kimura and the team leader YoshiChika Otani have now found that the spin Hall conductivity—the potential for electrons to migrate due to the SHE—in a platinum wire is a thousand times greater than in previous experiments with semiconductor materials, making it easier to study and exploit the effect. Their electrical measurement technique is also more precise than the optical detection method usually employed.
It’s significant that the team has detected this effect at room temperature. It means that SHE is not only a physically interesting phenomenon, but also a useful way of manipulating spins in future spintronic devices, says Kimura.
The team is now trying to identify materials that produce even greater SHE conductivities. “We hope that new devices using SHE are proposed in near future,” says Kimura.
Reference
1. Kimura, T., Otani, Y., Sato, T., Takahashi, S. & Maekawa, S. Room-temperature reversible spin Hall effect. Physical Review Letters 98, 156601 (2007).
RIKEN Large spin Hall effect measured at room temperature
RIKEN scientists have accurately measured a tiny voltage produced by segregating electrons according to their spin (1), a result which could help to usher in a new era of spin-based computing.
Conventional computers process and communicate information by shunting electrons around, but store data in the magnetic properties of tiny segments of a spinning disk drive. Yet that magnetism is also due to electrons—as each charged particle spins, it creates a magnetic moment. Electrons can spin ‘up’ or ‘down’, creating opposing poles like a bar magnet, and the burgeoning technology of spintronics uses these two states to represent bits of binary data. As well as storing information, these states can potentially be used to perform calculations.
The spin Hall effect (SHE) provides an important way to control these spinning electrons. The Hall effect itself (identified in 1879 by Edwin Hall) occurs when a magnetic field forces a current of electrons flowing through a flat plate to veer to one side. This causes charge to accumulate on that side of the plate, setting up a voltage across it. In a similar way, the SHE sends spin-up electrons to one side of the plate and spin-down to the other, setting up a ‘spin current’ (Fig. 1 - Click on link below).
Spin current is an important factor in operating future spintronic devices. Ferromagnets are normally used to differentiate spins, but interference between neighboring magnets makes it tricky to build working spintronic devices that way.
“However, if we use SHE, we can generate the spin current without using a ferromagnet,” says Takashi Kimura of RIKEN’s Frontier Research System, Wako. This could allow much easier integration of semiconductor and spintronic devices in the future.
Kimura and the team leader YoshiChika Otani have now found that the spin Hall conductivity—the potential for electrons to migrate due to the SHE—in a platinum wire is a thousand times greater than in previous experiments with semiconductor materials, making it easier to study and exploit the effect. Their electrical measurement technique is also more precise than the optical detection method usually employed.
It’s significant that the team has detected this effect at room temperature. It means that SHE is not only a physically interesting phenomenon, but also a useful way of manipulating spins in future spintronic devices, says Kimura.
The team is now trying to identify materials that produce even greater SHE conductivities. “We hope that new devices using SHE are proposed in near future,” says Kimura.
Reference
1. Kimura, T., Otani, Y., Sato, T., Takahashi, S. & Maekawa, S. Room-temperature reversible spin Hall effect. Physical Review Letters 98, 156601 (2007).
Saturday, July 14, 2007
A concerted effort : proton transfer in a chemical reaction
Chemical reactions are processes in which one substance is transformed into another and involve the motion of atoms and electrons. Because these processes occur on short time-scales that are measured in femtoseconds (millionths of a billionth of a second), it is difficult to study what actually happens during a chemical reaction.
Of particular interest are reactions that involve the transfer of a hydrogen nucleus (a proton) between two molecules—an important process in biological systems. Tahei Tahara from RIKEN’s Discovery Research Institute in Wako has been studying proton transfer reactions for many years and views them as a challenge at the limits of science. “Because hydrogen is the lightest atomic species, it usually moves very quickly and is difficult to catch,” comments Tahara.
A model system in which proton transfer has been extensively studied is 7-azaindole. In solution, this compound exists in two different forms; discrete individual molecules (monomers), and pairs known as dimers. The dimers can be pushed into a higher energy ‘excited’ state by shining ultraviolet light on them, and subsequently undergo a double proton transfer reaction to form a structure known as a tautomer.
When Tahara published his first results on this system ten years ago, he says that, “the work triggered very intense world-wide debate.” The controversy stemmed from whether the two proton-transfer steps occurred sequentially in a step-wise reaction, or simultaneously in a ‘concerted’ process. Tahara has always argued that the concerted process is the correct one, a hypothesis that is further supported by his recent findings published in the Proceedings of the National Academy of Sciences of the USA (1).
By exciting the 7-azaindole dimer with different wavelengths of ultraviolet light and monitoring the fluorescence, Tahara and colleague, Satoshi Takeuchi, show conclusively that no intermediate structure is formed, thereby ruling out the possibility of a step-wise process. Significantly, their experiments demonstrate that a feature of the fluorescence decay that was attributed to a separate proton transfer actually corresponds to the conversion of the dimer from one excited state to another.
Because the 7-azaindole dimer is very similar in structure to the base pairs found in DNA, Tahara expects that this work may help to understand the chemical mechanism of how ultraviolet light affects DNA. In addition, Tahara and co-workers are now intending to observe nuclear motion in real-time using sub-10-femtosecond pulses of light, which he suggests, “may offer new opportunities for using light to control chemical reactions.”
Chemical reactions are processes in which one substance is transformed into another and involve the motion of atoms and electrons. Because these processes occur on short time-scales that are measured in femtoseconds (millionths of a billionth of a second), it is difficult to study what actually happens during a chemical reaction.
Of particular interest are reactions that involve the transfer of a hydrogen nucleus (a proton) between two molecules—an important process in biological systems. Tahei Tahara from RIKEN’s Discovery Research Institute in Wako has been studying proton transfer reactions for many years and views them as a challenge at the limits of science. “Because hydrogen is the lightest atomic species, it usually moves very quickly and is difficult to catch,” comments Tahara.
A model system in which proton transfer has been extensively studied is 7-azaindole. In solution, this compound exists in two different forms; discrete individual molecules (monomers), and pairs known as dimers. The dimers can be pushed into a higher energy ‘excited’ state by shining ultraviolet light on them, and subsequently undergo a double proton transfer reaction to form a structure known as a tautomer.
When Tahara published his first results on this system ten years ago, he says that, “the work triggered very intense world-wide debate.” The controversy stemmed from whether the two proton-transfer steps occurred sequentially in a step-wise reaction, or simultaneously in a ‘concerted’ process. Tahara has always argued that the concerted process is the correct one, a hypothesis that is further supported by his recent findings published in the Proceedings of the National Academy of Sciences of the USA (1).
By exciting the 7-azaindole dimer with different wavelengths of ultraviolet light and monitoring the fluorescence, Tahara and colleague, Satoshi Takeuchi, show conclusively that no intermediate structure is formed, thereby ruling out the possibility of a step-wise process. Significantly, their experiments demonstrate that a feature of the fluorescence decay that was attributed to a separate proton transfer actually corresponds to the conversion of the dimer from one excited state to another.
Because the 7-azaindole dimer is very similar in structure to the base pairs found in DNA, Tahara expects that this work may help to understand the chemical mechanism of how ultraviolet light affects DNA. In addition, Tahara and co-workers are now intending to observe nuclear motion in real-time using sub-10-femtosecond pulses of light, which he suggests, “may offer new opportunities for using light to control chemical reactions.”
Researchers find a gene controlling embryo orientation
Developmental biologists from RIKEN working with Japanese and Canadian colleagues have located an important gene that regulates the establishment of the head-to-tail or anterior-to-posterior (A–P) axis in mice. The future development of the whole embryo is orientated to this point of reference.
The A–P axis appears before the emergence of the three primary germ layers of body tissue during the process known as gastrulation, when the primitive ball of cells called the blastula folds in on itself to form the more complex, layered structure of the gastrula. Before gastrulation, there are only two types of tissue—epiblast from which the animal proper develops and visceral endoderm (VE) that forms all of the support structures such as blood vessels and nutrient cells.
The establishment of the A–P axis involves interplay between the VE cells and the underlying epiblast. In particular, a group of VE cells furthest from where embryonic structure attaches to the uterus migrates to close to where the head will develop in the epiblast. At the same time VE cells near the posterior end of the axis switch on a gene, Wnt, that produces a compound necessary to initiate gastrulation. In contrast, the VE cells at the head end or anterior visceral endoderm (AVE) produce compounds which block Wnt.
Earlier work has shown that the developmental gene known as Otx2 is critical in the generation and function of the AVE. In mutants lacking Otx2 there is no migration of VE cells to form the AVE and a key antagonist to Wnt is not produced. But the factors that regulated Otx2 were unknown.
In a recent paper in the Proceedings of the National Academy of Sciences (1), the researchers from RIKEN’s Center for Developmental Biology in Kobe and their colleagues describe how they used carefully engineered transgenic mice to demonstrate the critical role of the transcription factor Foxa2 in regulating Otx2. In laboratory studies, they also showed that the Foxa2 protein is needed for the production of at least two Wnt antagonists. Through these actions Foxa2 controls the establishment of the A–P axis.
Similar genes and compounds also exist in the pufferfish, fugu (Fig. 1 - Click on link). In fact, the group found, the fugu equivalent of Foxa2 can actually work in mice. According to the researchers, this shows how tightly the whole regulatory system has been conserved in the evolution of higher vertebrates from the bony fishes.
Reference
Developmental biologists from RIKEN working with Japanese and Canadian colleagues have located an important gene that regulates the establishment of the head-to-tail or anterior-to-posterior (A–P) axis in mice. The future development of the whole embryo is orientated to this point of reference.
The A–P axis appears before the emergence of the three primary germ layers of body tissue during the process known as gastrulation, when the primitive ball of cells called the blastula folds in on itself to form the more complex, layered structure of the gastrula. Before gastrulation, there are only two types of tissue—epiblast from which the animal proper develops and visceral endoderm (VE) that forms all of the support structures such as blood vessels and nutrient cells.
The establishment of the A–P axis involves interplay between the VE cells and the underlying epiblast. In particular, a group of VE cells furthest from where embryonic structure attaches to the uterus migrates to close to where the head will develop in the epiblast. At the same time VE cells near the posterior end of the axis switch on a gene, Wnt, that produces a compound necessary to initiate gastrulation. In contrast, the VE cells at the head end or anterior visceral endoderm (AVE) produce compounds which block Wnt.
Earlier work has shown that the developmental gene known as Otx2 is critical in the generation and function of the AVE. In mutants lacking Otx2 there is no migration of VE cells to form the AVE and a key antagonist to Wnt is not produced. But the factors that regulated Otx2 were unknown.
In a recent paper in the Proceedings of the National Academy of Sciences (1), the researchers from RIKEN’s Center for Developmental Biology in Kobe and their colleagues describe how they used carefully engineered transgenic mice to demonstrate the critical role of the transcription factor Foxa2 in regulating Otx2. In laboratory studies, they also showed that the Foxa2 protein is needed for the production of at least two Wnt antagonists. Through these actions Foxa2 controls the establishment of the A–P axis.
Similar genes and compounds also exist in the pufferfish, fugu (Fig. 1 - Click on link). In fact, the group found, the fugu equivalent of Foxa2 can actually work in mice. According to the researchers, this shows how tightly the whole regulatory system has been conserved in the evolution of higher vertebrates from the bony fishes.
Reference
Playing tag highlights genetic disorder
A team of Japanese scientists led by Akimitsu Okamoto from the RIKEN Frontier Research System, Wako, has developed a new method for tagging a particular DNA base responsible for causing cancer.
Cytosine, a common DNA base, is reacted to add a methyl group to form methylcytosine during many biological processes. This process, known as methylation, is important for gene regulation, and DNA and protein stability. Further, excessive methylation of cytosine has been shown to result in cancer. The development of simple techniques to detect methylcytosine is therefore of great interest to scientists.
Although conventional methods have many advantages, they also have problems. Current methods cannot differentiate between cytosine and methylcytosine; they also destroy the DNA sample and are time-consuming. The latest technique by Okamoto and co-workers is selective for methylcytosine, fast and allows easy detection1.
The technique takes advantage of the easy oxidation of methylcytosine and uses three, specially designed, components to enable detection. When the reaction takes place, the methylcytosine forms a stable complex with an oxidant, potassium osmate, and a rate-enhancing ligand. The ligand, a bipyridine derivative, can then react further to bond with a variety of fluorescent or electrochemical tags allowing routine detection of the complex (Fig. 1 - Click on link below).
This conceptually new approach to methylcytosine detection takes just six hours to complete. Importantly, the key complex only forms between the methylcytosine and the ligand. This leaves the cytosine in the sample untouched and allows a clear distinction to be made. In addition, methylcytosines in single-stranded DNA efficiently formed the complex, whereas complexation of methylcytosines in a DNA duplex was suppressed. This result implies that the technique could also provide sequence-specific results giving detailed and accurate information of the methylated sites.
Okamoto explains that there is still more work to be done. Unfortunately, the information gained from the sequence-specific studies is limited as a consequence of the competing reaction with thymine, another DNA base. Also, the signal intensities and sensitivities are a little too weak to be useful on small sample sizes at this time.
Okamoto and his team are now striving to improve their technique so it can be used routinely in clinics with standard fluorescence or electronic signal analyzers. This technique is based on easy-to-use chemistry and Okamoto says, “Because the total process finishes in a few hours, this technique may make it possible to design machines that automate a series of processes from purification of samples to analysis.”
Reference
A team of Japanese scientists led by Akimitsu Okamoto from the RIKEN Frontier Research System, Wako, has developed a new method for tagging a particular DNA base responsible for causing cancer.
Cytosine, a common DNA base, is reacted to add a methyl group to form methylcytosine during many biological processes. This process, known as methylation, is important for gene regulation, and DNA and protein stability. Further, excessive methylation of cytosine has been shown to result in cancer. The development of simple techniques to detect methylcytosine is therefore of great interest to scientists.
Although conventional methods have many advantages, they also have problems. Current methods cannot differentiate between cytosine and methylcytosine; they also destroy the DNA sample and are time-consuming. The latest technique by Okamoto and co-workers is selective for methylcytosine, fast and allows easy detection1.
The technique takes advantage of the easy oxidation of methylcytosine and uses three, specially designed, components to enable detection. When the reaction takes place, the methylcytosine forms a stable complex with an oxidant, potassium osmate, and a rate-enhancing ligand. The ligand, a bipyridine derivative, can then react further to bond with a variety of fluorescent or electrochemical tags allowing routine detection of the complex (Fig. 1 - Click on link below).
This conceptually new approach to methylcytosine detection takes just six hours to complete. Importantly, the key complex only forms between the methylcytosine and the ligand. This leaves the cytosine in the sample untouched and allows a clear distinction to be made. In addition, methylcytosines in single-stranded DNA efficiently formed the complex, whereas complexation of methylcytosines in a DNA duplex was suppressed. This result implies that the technique could also provide sequence-specific results giving detailed and accurate information of the methylated sites.
Okamoto explains that there is still more work to be done. Unfortunately, the information gained from the sequence-specific studies is limited as a consequence of the competing reaction with thymine, another DNA base. Also, the signal intensities and sensitivities are a little too weak to be useful on small sample sizes at this time.
Okamoto and his team are now striving to improve their technique so it can be used routinely in clinics with standard fluorescence or electronic signal analyzers. This technique is based on easy-to-use chemistry and Okamoto says, “Because the total process finishes in a few hours, this technique may make it possible to design machines that automate a series of processes from purification of samples to analysis.”
Reference
Thursday, July 12, 2007
IMMUNOLOGY:Arresting autoimmunity
Working with a mouse version of multiple sclerosis, Gang Pei and colleagues study a protein called beta-arrestin 1, a factor known to regulate gene expression in all cells. Pei’s team reports that beta-arrestin 1 helps promote survival of T lymphocytes, which increases the duration of inflammation. In the absence of beta-arrestin 1 a critical factor required for T lymphocyte survival is not produced. Consistently, T lymphocytes lacking beta-arrestin 1 survive less well and cause much less brain inflammation in a mouse model of multiple sclerosis.
Demonstrating a role for beta-arrestin 1 in prolonging survival of aggressive T lymphocytes associated with autoimmune disease provides a possible target for reducing such diseases. Whether blocking the function of beta-arrestin 1 will help multiple sclerosis patients, however, remains a question for future investigation.
Author contact:
Gang Pei (Shanghai Institutes for Biological Sciences, China)
Tel: +86 21 5492 1371; E-mail: gpei@sibs.ac.cn
Working with a mouse version of multiple sclerosis, Gang Pei and colleagues study a protein called beta-arrestin 1, a factor known to regulate gene expression in all cells. Pei’s team reports that beta-arrestin 1 helps promote survival of T lymphocytes, which increases the duration of inflammation. In the absence of beta-arrestin 1 a critical factor required for T lymphocyte survival is not produced. Consistently, T lymphocytes lacking beta-arrestin 1 survive less well and cause much less brain inflammation in a mouse model of multiple sclerosis.
Demonstrating a role for beta-arrestin 1 in prolonging survival of aggressive T lymphocytes associated with autoimmune disease provides a possible target for reducing such diseases. Whether blocking the function of beta-arrestin 1 will help multiple sclerosis patients, however, remains a question for future investigation.
Author contact:
Gang Pei (Shanghai Institutes for Biological Sciences, China)
Tel: +86 21 5492 1371; E-mail: gpei@sibs.ac.cn
Growth factor reinforces cocaine addiction
Release of a growth factor in the nucleus accumbens – a brain area mediating reward – is necessary for the development and relapse of cocaine addiction.
Addictive drugs are thought to ‘hijack’ reward systems in the brain, causing neurons to be persistently more responsive to drug-associated cues and stressors. David Self and colleagues report that four hours after cocaine self-administration, rats show an increase in brain-derived neurotrophic factor (BDNF) in the nucleus accumbens. Preventing this increase in BDNF reduced cocaine self-administration and the propensity to relapse, whereas giving the rats daily BDNF injections after cocaine self-administration increased cocaine-seeking behaviour and relapse.
Moreover, using mice that were genetically engineered to lack BDNF only in the nucleus accumbens in adulthood, they showed that BDNF release in the nucleus accumbens did not affect the initial rewarding effects of cocaine, but did dramatically alter the development of addiction. If similar mechanisms mediate addiction in humans, these results could suggest possible approaches to addiction treatment.
Author contact:
David Self (University of Texas Southwestern Medical Center, Dallas, TX, USA)
Tel: +1 214 648 1237; E-mail: david.self@utsouthwestern.edu
Release of a growth factor in the nucleus accumbens – a brain area mediating reward – is necessary for the development and relapse of cocaine addiction.
Addictive drugs are thought to ‘hijack’ reward systems in the brain, causing neurons to be persistently more responsive to drug-associated cues and stressors. David Self and colleagues report that four hours after cocaine self-administration, rats show an increase in brain-derived neurotrophic factor (BDNF) in the nucleus accumbens. Preventing this increase in BDNF reduced cocaine self-administration and the propensity to relapse, whereas giving the rats daily BDNF injections after cocaine self-administration increased cocaine-seeking behaviour and relapse.
Moreover, using mice that were genetically engineered to lack BDNF only in the nucleus accumbens in adulthood, they showed that BDNF release in the nucleus accumbens did not affect the initial rewarding effects of cocaine, but did dramatically alter the development of addiction. If similar mechanisms mediate addiction in humans, these results could suggest possible approaches to addiction treatment.
Author contact:
David Self (University of Texas Southwestern Medical Center, Dallas, TX, USA)
Tel: +1 214 648 1237; E-mail: david.self@utsouthwestern.edu
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