bluuebunny/crossref_metadata_2025 huggingface dataset:
A Structure-Guided Mutational Analysis of Simian Virus 40 Large T Antigen: Identification of Surface Residues Required for Viral Replication and Transformation
Authors: Ahuja Deepika , Rathi Abhilasha V. , Greer Amy E. , Chen Xiaojiang S. , Pipas James M.
Published: June 2009

Simian virus 40 large T antigen (TAg) transforms cells in culture and induces tumors in rodents. Genetic studies suggest that TAg interaction with the chaperone hsp70 and tumor suppressors pRb and p53 may not be sufficient to elicit complete transformation of cells. In order to identify additional cellular factors important for transformation, we designed mutations on the solvent-exposed surface of TAg. We hypothesized that surface residues would interact directly with cellular targets and that the mutation of these residues might disrupt this interaction without perturbing TAg's global structure. Using structural data, we identified 61 amino acids on the surface of TAg. Each surface amino acid was changed to an alanine. Furthermore, five patches containing clusters of charged amino acids on the surface of TAg were identified. Within these patches, we selectively mutated three to four charged amino acids and thus generated five mutants (patch mutants 1 to 5). We observed that while patch mutants 3 and 4 induced foci in REF52 cells, patch mutants 1 and 2 were deficient in focus formation. We determined that the patch 1 mutant is defective in p53 binding, thus explaining its defect in transformation. The patch 2 mutant can interact with the Rb family members and p53 like wild-type TAg but is unable to transform cells, suggesting that it is defective for action on an unknown cellular target essential for transformation. Our results suggest that the histone acetyltransferase CBP/p300 is one of the potential targets affected by the mutations in patch 2.
Bluetongue Virus Targets Conventional Dendritic Cells in Skin Lymph
Authors: Hemati Behzad , Contreras Vanessa , Urien Céline , Bonneau Michel , Takamatsu Haru-Hisa , Mertens Peter P. C. , Bréard Emmanuel , Sailleau Corinne , Zientara Stéphan , Schwartz-Cornil Isabelle
Published: June 2009

Bluetongue virus (BTV) is the etiological agent of bluetongue, a hemorrhagic disease of ruminants (particularly sheep), which causes important economic losses around the world. BTV is transmitted primarily via the bites of infected midges, which inject the virus into the ruminant's skin during blood feeding. The virus initially replicates in the draining lymph node and then disseminates to secondary organs where it induces edema, hemorrhages, and necrosis. In this study, we show that ovine conventional dendritic cells (cDCs) are the primary targets of BTV that contribute to the primary dissemination of BTV from the skin to draining lymph nodes. Lymph cDCs support BTV RNA and protein synthesis, as well as the production of infectious virus belonging to several different BTV serotypes, regardless of their level of attenuation. Afferent lymph cell subsets, other than cDCs, showed only marginal levels of BTV protein expression. BTV infection provoked a massive recruitment of cDCs to the sheep skin and afferent lymph, providing cellular targets for infection. Although BTV productively infects cDCs, no negative impact on their physiology was detected. Indeed, BTV infection and protein expression in cDCs enhanced their survival rate. Several serotypes of BTV stimulated the surface expression of the CD80 and CD86 costimulatory molecules on cDCs as well as the mRNA synthesis of cytokines involved in inflammation and immunity, i.e., interleukin-12 (IL-12), IL-1β, and IL-6. BTV-infected cDCs stimulated antigen-specific CD4 and CD8 proliferation as well as gamma interferon production. BTV initially targets cDCs while preserving their functional properties, reflecting the optimal adaptation of the virus to its host cells for its first spread.
Impact of Quaternary Organization on the Antigenic Structure of the Tick-Borne Encephalitis Virus Envelope Glycoprotein E
Authors: Kiermayr Stefan , Stiasny Karin , Heinz Franz X.
Published: June 2009

The envelope protein E of flaviviruses mediates both receptor-binding and membrane fusion. At the virion surface, 180 copies of E are tightly packed and organized in a herringbone-like icosahedral structure, whereas in noninfectious subviral particles, 60 copies are arranged in a T=1 icosahedral symmetry. In both cases, the basic building block is an E dimer which exposes the binding sites for neutralizing antibodies at its surface. It was the objective of our study to assess the dependence of the antigenic structure of E on its quaternary arrangement, i.e., as part of virions, recombinant subviral particles, or soluble dimers. For this purpose, we used a panel of 11 E protein-specific neutralizing monoclonal antibodies, mapped to distinct epitopes in each of the three E protein domains, and studied their reactivity with the different soluble and particulate forms of tick-borne encephalitis virus E protein under nondenaturing immunoassay conditions. Significant differences in the reactivities with these forms were observed that could be related to (i) limited access of certain epitopes at the virion surface; (ii) limited occupancy of epitopes in virions due to steric hindrance between antibodies; (iii) differences in the avidity to soluble forms compared to the virion, presumably related to the flexibility of E at its domain junctions; and (iv) modulations of the external E protein surface through interactions with its stem-anchor structure. We have thus identified several important factors that influence the antigenicity of the flavivirus E protein and have an impact on the interaction with neutralizing antibodies.
Brd4 Regulation of Papillomavirus Protein E2 Stability
Authors: Zheng Gang , Schweiger Michal-Ruth , Martinez-Noel Gustavo , Zheng Leon , Smith Jennifer A. , Harper J. Wade , Howley Peter M.
Published: June 2009

The papillomavirus (PV) E2 protein is an important regulator of the viral life cycle. It has diverse roles in viral transcription, DNA replication, and genome maintenance. Our laboratory has previously identified the cellular bromodomain protein Brd4 as a key interacting partner of E2. Brd4 mediates the transcriptional activation function of E2 and plays an important role in viral genome maintenance in dividing cells. E2 interacts with the C-terminal domain (CTD) of Brd4, and the CTD functions in a dominant-negative manner through binding E2 and interfering with E2's interaction with the full-length Brd4 protein. Previous studies have shown that PV E2 proteins are short lived; however, the mechanisms regulating their stability and degradation have not yet been well established. In this study, we explored the role of Brd4 in the regulation of bovine PV 1 (BPV1) and human PV 16 (HPV16) E2 stability. Expression of the Brd4 CTD dramatically increases E2 levels. Both BPV1 E2 and HPV16 E2 are regulated by ubiquitylation, and Brd4 CTD expression blocks this ubiquitylation, thus stabilizing the E2 protein. Furthermore, we have identified the cullin-based E3 ligases and specifically cullin-3 as potential components of the ubiquitylation machinery that targets both BPV1 and HPV16 E2 for ubiquitylation. Expression of the Brd4 CTD blocks the interaction between E2 and the cullin-3 complex. In addition to Brd4's role in mediating E2 transcription and genome tethering activities, these data suggest a potential role for Brd4 in regulating E2 stability and protein levels within PV-infected cells.
gp340 Promotes Transcytosis of Human Immunodeficiency Virus Type 1 in Genital Tract-Derived Cell Lines and Primary Endocervical Tissue
Authors: Stoddard Earl , Ni Houping , Cannon Georgetta , Zhou Chunhui , Kallenbach Neville , Malamud Daniel , Weissman Drew
Published: June 2009

The human scavenger receptor gp340 has been identified as a binding protein for the human immunodeficiency virus type 1 (HIV-1) envelope that is expressed on the cell surface of female genital tract epithelial cells. This interaction allows such epithelial cells to efficiently transmit infective virus to susceptible targets and maintain viral infectivity for several days. Within the context of vaginal transmission, HIV must first traverse a normally protective mucosa containing a cell barrier to reach the underlying T cells and dendritic cells, which propagate and spread the infection. The mechanism by which HIV-1 can bypass an otherwise healthy cellular barrier remains an important area of study. Here, we demonstrate that genital tract-derived cell lines and primary human endocervical tissue can support direct transcytosis of cell-free virus from the apical to basolateral surfaces. Further, this transport of virus can be blocked through the addition of antibodies or peptides that directly block the interaction of gp340 with the HIV-1 envelope, if added prior to viral pulsing on the apical side of the cell or tissue barrier. Our data support a role for the previously described heparan sulfate moieties in mediating this transcytosis but add gp340 as an important facilitator of HIV-1 transcytosis across genital tract tissue. This study demonstrates that HIV-1 actively traverses the protective barriers of the human genital tract and presents a second mechanism whereby gp340 can promote heterosexual transmission.
Computational Analysis of Human Adenovirus Type 22 Provides Evidence for Recombination among Species D Human Adenoviruses in the Penton Base Gene
Authors: Robinson Christopher M. , Rajaiya Jaya , Walsh Michael P. , Seto Donald , Dyer David W. , Jones Morris S. , Chodosh James
Published: June 2009

Recombination in human adenoviruses (HAdV) may confer virulence upon an otherwise nonvirulent strain. The genome sequence of species D HAdV type 22 (HAdV-D22) revealed evidence for recombination with HAdV-D19 and HAdV-D37 within the capsid penton base gene. Bootscan analysis demonstrated that recombination sites within the penton base gene frame the coding sequences for the two external hypervariable loops in the protein. A similar pattern of recombination was evident within other HAdV-D types but not other HAdV species. Further study of recombination among HAdVs is needed to better predict possible recombination events among wild-type viruses and adenoviral gene therapy vectors.
Characterization of the H5N1 Highly Pathogenic Avian Influenza Virus Derived from Wild Pikas in China
Authors: Zhou Jiyong , Sun Wenbo , Wang Junhua , Guo Junqing , Yin Wei , Wu Nanping , Li Lanjuan , Yan Yan , Liao Ming , Huang Yu , Luo Kaijian , Jiang Xuetao , Chen Hualan
Published: June 2009

The highly pathogenic H5N1 avian influenza virus emerged from China in 1996 and has spread across Eurasia and Africa, with a continuous stream of new cases of human infection appearing since the first large-scale outbreak among migratory birds at Qinghai Lake. The role of wild birds, which are the natural reservoirs for the virus, in the epidemiology of the H5N1 virus has raised great public health concern, but their role in the spread of the virus within the natural ecosystem of free-ranging terrestrial wild mammals remains unclear. In this study, we investigated H5N1 virus infection in wild pikas in an attempt to trace the circulation of the virus. Seroepidemiological surveys confirmed a natural H5N1 virus infection of wild pikas in their native environment. The hemagglutination gene of the H5N1 virus isolated from pikas reveals two distinct evolutionary clades, a mixed/Vietnam H5N1 virus sublineage (MV-like pika virus) and a wild bird Qinghai (QH)-like H5N1 virus sublineage (QH-like pika virus). The amino acid residue (glutamic acid) at position 627 encoded by the PB2 gene of the MV-like pika virus was different from that of the QH-like pika virus; the residue of the MV-like pika virus was the same as that of the goose H5N1 virus (A/GS/Guangdong [GD]/1/96). Further, we discovered that in contrast to the MV-like pika virus, which is nonpathogenic to mice, the QH-like pika virus is highly pathogenic. To mimic the virus infection of pikas, we intranasally inoculated rabbits, a species closely related to pikas, with the H5N1 virus of pika origin. Our findings first demonstrate that wild pikas are mammalian hosts exposed to H5N1 subtype avian influenza viruses in the natural ecosystem and also imply a potential transmission of highly pathogenic avian influenza virus from wild mammals into domestic mammalian hosts and humans.
Arginine Methylation of the ICP27 RGG Box Regulates the Functional Interactions of ICP27 with SRPK1 and Aly/REF during Herpes Simplex Virus 1 Infection
Authors: Souki Stuart K. , Sandri-Goldin Rozanne M.
Published: June 2009

The herpes simplex virus 1 protein ICP27 is methylated on arginine residues within an RGG box, and arginine methylation regulates ICP27 export to the cytoplasm. Arginine methylation can regulate protein-protein interactions; therefore, we examined the effect of hypomethylation on ICP27's interactions with cellular proteins SRPK1 and Aly/REF, which bind to ICP27 through the RGG box region. During infections with viral mutants containing lysine substitutions or the methylation inhibitor adenosine dialdehyde, the interaction of ICP27 with SRPK1 and Aly/REF was decreased, as determined by coimmunoprecipitation and colocalization studies, indicating that ICP27 RGG box methylation regulates interaction with these proteins.
T-Cell Tolerance for Variability in an HLA Class I-Presented Influenza A Virus Epitope
Authors: Wahl Angela , McCoy William , Schafer Fredda , Bardet Wilfried , Buchli Rico , Fremont Daved H. , Hildebrand William H.
Published: June 2009

To escape immune recognition, viruses acquire amino acid substitutions in class I human leukocyte antigen (HLA)-presented cytotoxic T-lymphocyte (CTL) epitopes. Such viral escape mutations may (i) prevent peptide processing, (ii) diminish class I HLA binding, or (iii) alter T-cell recognition. Because residues 418 to 426 of the hypervariable influenza A virus nucleoprotein (NP418-426) epitope are consistently bound by class I HLA and presented to CTL, we assessed the impact that intraepitope sequence variability has upon T-cell recognition. CTL elicited by intranasal influenza virus infection were tested for their cross-recognition of 20 natural NP418-426epitope variants. Six of the variant epitopes, of both H1N1 and H3N2 origin, were cross-recognized by CTL while the remaining NP418-426epitope variants escaped targeting. A pattern emerged whereby variability at position 5 (P5) within the epitope reduced T-cell recognition, changes at P4 or P6 enabled CTL escape, and a mutation at P8 enhanced T-cell recognition. These data demonstrate that substitutions at P4 and/or P6 facilitate influenza virus escape from T-cell recognition and provide a model for the number, nature, and location of viral mutations that influence T-cell cross-recognition.
The Efficacy of Antigen Processing Is Critical for Protection against Cytomegalovirus Disease in the Presence of Viral Immune Evasion Proteins
Authors: Holtappels Rafaela , Thomas Doris , Reddehase Matthias J.
Published: June 2009

Cytomegaloviruses (CMVs) code for immunoevasins, glycoproteins that are specifically dedicated to interfere with the presentation of antigenic peptides to CD8 T cells. Nonetheless, the biological outcome is not an immune evasion of the virus, since CD8 T cells can control CMV infection even when immunoevasins are expressed. Here, we compare the processing of a protective and a nonprotective epitope derived from the same viral protein, the antiapoptotic protein M45 in the murine model. The data provide evidence to conclude that protection against CMVs critically depends on antigenic peptides generated in an amount sufficient to exhaust the inhibitory capacity of immunoevasins.
Palmitoylation of the Influenza A Virus M2 Protein Is Not Required for Virus Replication In Vitro but Contributes to Virus Virulence
Authors: Grantham Michael L. , Wu Wai-Hong , Lalime Erin N. , Lorenzo Maria E. , Klein Sabra L. , Pekosz Andrew
Published: June 2009

The influenza A virus M2 protein has important roles during virus entry and in the assembly of infectious virus particles. The cytoplasmic tail of the protein can be palmitoylated at a cysteine residue, but this residue is not conserved in a number of human influenza A virus isolates. Recombinant viruses encoding M2 proteins with a serine substituted for the cysteine at position 50 were generated in the A/WSN/33 (H1N1) and A/Udorn/72 (H3N2) genetic backgrounds. The recombinant viruses were not attenuated for replication in MDCK cells, Calu-3 cells, or in primary differentiated murine trachea epithelial cell cultures, indicating there was no significant contribution of M2 palmitoylation to virus replication in vitro. The A/WSN/33 M2C50S virus displayed a slightly reduced virulence after infection of mice, suggesting that there may be novel functions for M2 palmitoylation during in vivo infection.
Matrix Metalloprotease Inhibitors Restore Impaired NK Cell-Mediated Antibody-Dependent Cellular Cytotoxicity in Human Immunodeficiency Virus Type 1 Infection
Authors: Liu Qingquan , Sun Yongtao , Rihn Suzannah , Nolting Anne , Tsoukas Peter Nicholas , Jost Stephanie , Cohen Kristen , Walker Bruce , Alter Galit
Published: June 2009

Increasing evidence suggests that NK cells not only are critical in the initial host defense against pathogens but also may contribute to continued protection from human immunodeficiency virus type 1 (HIV-1) disease progression. NK cell cytolysis can be induced directly through diverse receptor families or can be induced indirectly through Fc receptors by antibodies mediating antibody-dependent cellular cytotoxicity (ADCC). ADCC has been implicated in both protection from simian immunodeficiency virus infection and slower progression of HIV-1 disease. ADCC activity declines with advancing infection, and yet the underlying mechanism for this dysfunction has not been defined, nor has it been determined whether the activity can be reconstituted. Here we demonstrate that NK cell-mediated ADCC is severely compromised in chronic HIV infection. The potency of ADCC function was directly correlated with baseline FcγRIIIa receptor (CD16) expression on NK cells. CD16 expression was negatively influenced by elevated expression of a group of enzymes, the matrix metalloproteinases (MMPs), normally involved in tissue/receptor remodeling. Inhibition of MMPs resulted in increased CD16 expression and augmented ADCC activity in response to antibody-coated target cells. These data suggest that MMP inhibitors may improve NK cell-mediated ADCC, which may provide subjects with an opportunity to harness the cytolytic power of NK cells through naturally occurring nonneutralizing HIV-specific antibodies.
The role of emotions on pacing strategies and performance in middle and long duration sport events
Authors: Baron B , Moullan F , Deruelle F , Noakes T D
Published: June 2009

Thepacing strategy may be defined as the process in which the total energy expenditure during exercise is regulated on a moment-to-moment basis in order to ensure that the exercise bout can be completed in a minimum time and without a catastrophic biological failure. Experienced athletes develop a stable template of the power outputs they are able to sustain for different durations of exercise, but it is not known how they originally develop this template or how that template changes with training and experience. While it is understood that the athlete's physiological state makes an important contribution to this process, there has been much less interest in the contribution that the athlete's emotional status makes.

The aim of this review is to evaluate the literature of physiological, neurophysiological and perceptual responses during exercise in order to propose a complex model interpretation of this process which may be a critical factor determining success in middle- and long-duration sporting competitions.

We describe unconscious/physiological and conscious/emotional mechanisms of control, the focus of which are to ensure that exercise terminates before catastrophic failure occurs in any bodily system.

We suggest that training sessions teach the athlete to select optimal pacing strategies by associating a level of emotion with the ability to maintain that pace for exercise of different durations. That pacing strategy is then adopted in future events.

Finally, we propose novel perspectives to maximise performance and to avoid overtraining by paying attention also to the emotional state in training process.
Injury incidence and injury patterns in professional football: the UEFA injury study
Authors: Ekstrand J , Hägglund M , Waldén M
Published: June 2009

Objective

To study the injury characteristics in professional football and to follow the variation of injury incidence during a match, during a season and over consecutive seasons.

Design

Prospective cohort study where teams were followed for seven consecutive seasons. Team medical staff recorded individual player exposure and time-loss injuries from 2001 to 2008.

Setting

European professional men's football.

Participants

The first team squads of 23 teams selected by the Union of European Football Associations as belonging to the 50 best European teams.

Main outcome measurement

Injury incidence.

Results

4483 injuries occurred during 566 000 h of exposure, giving an injury incidence of 8.0 injuries/1000 h. The injury incidence during matches was higher than in training (27.5 vs 4.1, p<0.0001). A player sustained on average 2.0 injuries per season, and a team with typically 25 players can thus expect about 50 injuries each season. The single most common injury subtype was thigh strain, representing 17% of all injuries. Re-injuries constituted 12% of all injuries, and they caused longer absences than non re-injuries (24 vs 18 days, p<0.0001). The incidence of match injuries showed an increasing injury tendency over time in both the first and second halves (p<0.0001). Traumatic injuries and hamstring strains were more frequent during the competitive season, while overuse injuries were common during the preseason. Training and match injury incidences were stable over the period with no significant differences between seasons.

Conclusions

The training and match injury incidences were stable over seven seasons. The risk of injury increased with time in each half of matches.
Five-year prospective comparison study of topical glyceryl trinitrate treatment of chronic lateral epicondylosis at the elbow
Authors: McCallum Sebastian DA , Paoloni Justin A , Murrell George AC
Published: June 2009

Background

Topical glyceryl trinitrate (GTN) treatment has previously demonstrated short-term efficacy in the treatment of lateral epicondylosis. No long-term follow-up has been performed.

Hypothesis

Benefits from topical GTN persist 5 years after the cessation of therapy.

Study design

A prospective comparative study.

Methods

A follow-up study of 58 patients treated with 6 months of topical GTN or placebo, combined with a tendon rehabilitation programme, was performed 5 years after discontinuation of therapy. Assessment included patient-rated pain scores, clinically assessed lateral epicondylar and proximal common extensor tendon tenderness, hand-held dynamometer measurement of resisted third finger metacarpophalangeal extension with a fully extended elbow (Maudsley's test) and wrist extensor tendon mean peak force using a modified chair pick-up test (the Orthopaedic Research Institute—tennis elbow testing system).

Results

Patients in both the GTN group and those in the placebo group had significant improvements in symptoms, clinical signs and provocative functional tests compared with baseline week 0 measures. GTN did not offer any additional clinical benefit over a standard tendon rehabilitation programme at 5 years.

Conclusion

While GTN appears to offer short-term benefits up to 6 months in the treatment of lateral epicondylosis, at 5 years there does not appear to be significant clinical benefits when compared with patients undertaking a standard tendon rehabilitation programme alone. This is in contrast to findings of continued benefits at long-term follow-up described in the literature for patients with Achilles tendinopathy treated with GTN.
Cancer incidence and mortality in a historical cohort of Australian pest control workers
Authors: MacFarlane E , Benke G , Del Monaco A , Sim M R
Published: June 2009

Objectives:

To determine the rates of mortality and incident cancer in a historical cohort of pest control operators.

Methods:

A retrospective cohort was assembled from former state government occupational health surveillance programmes. This cohort was linked to the Australian national registries of cancer and mortality and the results were compared with the general Australian population rates.

Results:

125 deaths and 89 incident cancers were found during the periods of observation (mortality 1983–2004 and cancer 1983–2002). Overall cancer incidence and mortality rates were not found to be significantly different from the general population. Among the specific causes of death, suicide (standardised mortality ratio; SMR 1.78; 95% CI 1.12 to 2.83) and unintentional falls (SMR 4.57; 95% CI 1.72 to 12.19) were significantly in excess, although the latter was based on only 4 deaths. Melanoma was the only specific incident cancer found significantly in excess (standardised incidence ratio 1.56; 95% CI 1.03 to 2.37).

Conclusions:

Pest control workers have overall mortality and cancer rates similar to the general population. Excess rates of incident melanoma and intentional self-poisoning mortality are of concern and warrant further investigation. Follow-up of this cohort as its members age, will provide more insight into these possible associations.
ON UNFOLDING LATTICE POLYGONS/TREES AND DIAMETER-4 TREES
Authors: POON SHEUNG-HUNG
Published: June 2009

We consider the problems of straightening polygonal trees and convexifying polygons by continuous motions such that rigid edges can rotate around vertex joints and no edge crossings are allowed. A tree can be straightened if all its edges can be aligned along a common straight line such that each edge points "away" from a designated leaf node. A polygon can be convexified if it can be reconfigured to a convex polygon. A lattice tree (resp. polygon) is a tree (resp. polygon) containing only edges from a square or cubic lattice. We first show that a 2D lattice chain or a 3D lattice tree can be straightened efficiently in O(n) moves and time, where n is the number of tree edges. We then show that a 2D lattice tree can be straightened efficiently in O(n2) moves and time. Furthermore, we prove that a 2D lattice polygon or a 3D lattice polygon with simple shadow can be convexified efficiently in O(n) moves and in O(n log n) time. Finally, we show that two special classes of diameter-4 trees in two dimensions can always be straightened.
DYNAMICAL CLUSTERING AS A GENERATOR OF COMPLEX SYSTEM DYNAMICS
Authors: ZHAO ZHENYUAN , KIROU ANDY , RUSZCZYCKI BŁAŻEJ , JOHNSON NEIL F.
Published: June 2009

The challenge to understand the dynamics of Complex Systems is attracting attention from a wide range of disciplines across the natural, biological and social sciences. Recent turmoil in the financial markets has brought this challenge into the public domain, with speculation rife as to the root cause of the observed fluctuations. At their heart, all Complex Systems share the common property of featuring many interacting objects from which the observed macroscopic dynamics emerge. Exactly how this happens cannot yet be specified in a generic way — however, an important milestone in this endeavor is to develop a quantitative understanding of any internal clustering dynamics within the population. Coalescence-fragmentation processes have been studied widely in conventional chemistry and physics — however, collective behavior in social systems is not limited by nearest-neighbor interactions, nor are the details of social coalescence or fragmentation processes necessarily the same as in physical and biological systems. Here we discuss the general phenomenon of coalescence and fragmentation problems with a focus on social systems in which a typical fragmentation process corresponds to an entire group breaking up, as opposed to the typical binary splitting studied in physical and biological systems. Having discussed situations under which power-laws for the group distribution size emerge from such internal clustering dynamics, we move on to look at the specific application to financial markets. We propose a new model for financial market dynamics based on the combination of internal clustering (i.e. herding) dynamics with human decision-making. The resulting fluctuation in price movements is closer to what is observed empirically, leading us to speculate that the combination of dynamical clustering and decision-making are key for developing quantitative models of social dynamical phenomena.
MINIVERSAL DEFORMATIONS OF DIALGEBRAS
Authors: FIALOWSKI ALICE , MAJUMDAR ANITA
Published: June 2009

We develop the theory of versal deformations of dialgebras and describe a method for constructing a miniversal deformation of a dialgebra.
GLOBAL CONTROLLABILITY OF A NONLINEAR KORTEWEG–DE VRIES EQUATION
Authors: CHAPOULY MARIANNE
Published: June 2009

We are interested in both the global exact controllability to the trajectories and in the global exact controllability of a nonlinear Korteweg–de Vries equation in a bounded interval. The local exact controllability to the trajectories by means of one boundary control, namely the boundary value at the left endpoint, has already been proved independently by Rosier, and Glass and Guerrero. We first introduce here two more controls: the boundary value at the right endpoint and the right member of the equation, assumed to be x-independent. Then, we prove that, thanks to these three controls, one has the global exact controllability to the trajectories, for any positive time T. Finally, we introduce a fourth control on the first derivative at the right endpoint, and we get the global exact controllability, for any positive time T.
Palaeozoic Lachlan orogen, Australia; accretion and construction of continental crust in a marginal ocean setting: isotopic evidence from Cambrian metavolcanic rocks
Authors: Foster David A. , Gray David R. , Spaggiari Catherine , Kamenov George , Bierlein Frank P.
Published: June 2009

The Lachlan orogen developed as a classic accretionary orogen in an oceanic setting between the palaeo-Pacific subduction zone and the Australian craton. Direct evidence for the composition and age of the lower crust and the basement to the thick Palaeozoic turbidite fan of the Lachlan orogen is limited. Exposures of Cambrian metavolcanic rocks and geophysical data suggest that most of the basement is the mafic oceanic crust along with possible small fragments of older continental crust. The trace element compositions of Cambrian metavolcanic rocks in the western and central Lachlan orogen are similar to those of volcanic rocks formed in modern back-arc and forearc settings. Pb, Nd and Sr isotopic data from these Cambrian rocks suggest a supra-subduction zone setting with little or no influence of continental crust other than subducted sediment.
Evolution from an oblique subduction back-arc mobile belt to a highly oblique collisional margin: the Cenozoic tectonic development of Thailand and eastern Myanmar
Authors: Morley C. K.
Published: June 2009

Previous tectonic models (escape tectonics, topographic ooze) for SE Asia have considered that Himalayan–Tibetan processes were dominant and imposed on cool, rigid SE Asian crust. However, present-day geothermal gradients, metamorphic mineral assemblages, structural style and igneous intrusions all point to east Myanmar and Thailand having hot, ductile crust during Cenozoic–Recent times. North to NE subduction beneath SE Asia during the Mesozoic–Cenozoic resulted in development of hot, thickened crust in the Thailand–Myanmar region in a back-arc mobile belt setting. This setting changed during the Eocene–Recent to highly oblique collision as India coupled with the west Burma block. The characteristics of the orogenic belt include: (1) a hot and weak former back-arc area about 200–300 km wide (Shan Plateau) heavily intruded by I-type and S-type granites during the Mesozoic and Palaeogene; (2) high modern geothermal gradients (3–7 °C per 100 m) and heat fl ow (70–100 mW m
−2
; (3) widespread Eocene–Pliocene basaltic volcanism; (4) Late Cretaceous–earliest Cenozoic and Eocene–Oligocene high-temperature–low-pressure metamorphism; (5)
c
. 47–29 Ma peak metamorphism in the Mogok metamorphic belt followed by
c
. 30–23 Ma magmatism and exhumation of the belt between the Late Oligocene and early Miocene; (6) a broad zone of Eocene–Oligocene sinistral transpression in the Shan Plateau, later reactivated by Oligocene–Recent dextral transtension; (7) diachronous extensional collapse during the Cenozoic, involving both high-angle normal fault and low-angle normal fault (LANF) bounded basins; (8) progressive collapse of thickened, ductile crust from south (Eocene) to north (Late Oligocene) in the wake of India moving northwards; and (9) the present-day influence on the stress system by both the Himalayan orogenic belt and the Sumatra–Andaman subduction zone.
Arc-continent collisions, sediment recycling and the maintenance of the continental crust
Authors: Clift Peter D. , Schouten Hans , Vannucchi Paola
Published: June 2009

Subduction zones are both the source of most new continental crust and the locations where crustal material is returned to the upper mantle. Globally the total amount of continental crust and sediment subducted below forearcs currently lies close to 3.0 Armstrong Units (1 AU=1 km
3
a
−1
), of which 1.65 AU comprises subducted sediments and 1.33 AU tectonically eroded forearc crust, compared with an average of
c
. 0.4 AU lost during subduction of passive margins during Cenozoic continental collision. Margins may retreat in a wholesale, steady-state mode, or in a slower way involving the trenchward erosion of the forearc coupled with landward underplating, such as seen in the central and northern Andean margins. Tephra records of magmatism evolution from Central America indicate pulses of recycling through the roots of the arc. While this arc is in a state of long-term mass loss this is achieved in a discontinuous fashion via periods of slow tectonic erosion and even sediment accretion interrupted by catastrophic erosion events, probably caused by seamount subduction. Crustal losses into subduction zones must be balanced by arc magmatism and we estimate global average melt production rates to be 96 and 64 km
3
Ma
−1
km
−1
in oceanic and continental arc, respectively. Critical to maintaining the volume of the continental crust is the accretion of oceanic arcs to continental passive margins. Mass balancing across the Taiwan collision zones suggests that almost 90% of the colliding Luzon Arc crust is accreted to the margin of Asia in that region. Rates of exhumation and sediment recycling indicate that the complete accretion process spans only 6–8 Ma. Subduction of sediment in both erosive and inefficient accretionary margins provides a mechanism for returning continental crust to the upper mantle. Sea level governs rates of continental erosion and thus sediment delivery to trenches, which in turn controls crustal thicknesses over 10
7
–10
9
years. Tectonically thickened crust is reduced to normal values (35–38 km) over time scales of 100–200 Ma.
Eoarchaean crustal growth in West Greenland (Itsaq Gneiss Complex) and in northeastern China (Anshan area): review and synthesis
Authors: Nutman Allen P. , Bennett Vickie C. , Friend Clark R. L. , Jenner Frances , Wan Yusheng , Liu Dunyi
Published: June 2009

Eoarchaean crust in West Greenland (the Itsaq Gneiss Complex, 3870–3600 Ma) is >80% by volume orthogneisses derived from plutonic tonalite–trondhjemite–granodiorite (TTG) suites, <10% amphibolites derived from basalts and gabbros, <10% crustally derived granite, <1% metasedimentary rocks and ≪1% tectonic slices of upper mantle peridotite. Amphibolites at >3850,
c.
3810 and
c.
3710 Ma have some compositional similarities to modern island arc basalts (IAB), suggesting their origin by hydrous fluxing of a suprasubduction-zone upper mantle wedge. Most of the Eoarchaean tonalites match in composition high-silica, low-magnesian adakites, whose petrogenesis is dominated by partial melting of garnetiferous mafic rocks at high pressure. However, associated with the tonalites are volumetrically minor more magnesian quartz diorites, whose genesis probably involved melting of depleted mantle to which some slab-derived component had been added. This assemblage is evocative of suites of magmas produced at Phanerozoic convergent plate boundaries in the case where subducted crust is young and hot. Thus, Eoarchaean ‘subduction’ first gave rise to short-lived episodes of mantle wedge melting by hydrous fluxing, yielding IAB-like basalts±boninites. In the hotter Eoarchaean Earth, flux-dominated destructive plate boundary magma generation quickly switched to slab melting of (‘subducted’) oceanic crust. This latter process produced the voluminous tonalites that were intruded into the slightly older sequences consisting of tectonically imbricated assemblages of IAB-like pillow lavas+sedimentary rocks, gabbros and upper mantle peridotite slivers. Zircon dating shows that Eoarchaean TTG production in the Itsaq Gneiss Complex was episodic (3870, 3850–3840, 3820–3810, 3795, 3760–3740, 3710–3695 and 3660 Ma). In each case, emplacement of small volumes of magma was probably followed by 10–40 Ma quiescence, which allowed the associated thermal pulse to dissipate. This explains why Greenland Eoarchaean crustal growth did not have granulite-facies metamorphism directly associated with it. Instead, 3660–3600 Ma granulite-facies metamorphism(s) in the Itsaq Gneiss Complex were consequential to collisional orogeny and underplating, upon termination of crustal growth. Similar Eoarchaean crustal history is recorded in the Anshan area of China, where a few well-preserved rocks as old as 3800 Ma have been found including high-MgO quartz diorites. For 3800 Ma rocks, this is a rare, if not unique, situation outside of the Itsaq Gneiss Complex. The presence of volumetrically minor 3800 Ma mantle-derived high-MgO quartz diorites in both the Itsaq Gneiss Complex and the Anshan area indicates either that Eoarchaean ‘subduction’ zones were overlain by a narrow mantle wedge or that the shallow subduction trapped slivers of upper mantle between the conserved and consumed plates.
Archaean crustal growth processes in southern West Greenland and the southern Superior Province: geodynamic and magmatic constraints
Authors: Polat Ali , Kerrich Rob , Windley Brian
Published: June 2009

Eo- to Mesoarchaean greenstone belts (e.g. 3800–3700 Ma Isua,c. 3075 Ma Ivisaartoq, 3071 Ma Qussuk) occur within orthogneisses of the southern West Greenland Craton. Greenstone belts are composed mainly of metavolcanic rocks with minor ultramafic and sedimentary schists. Compositionally, volcanic rocks are dominantly tholeiitic basalts, boninites, and picrites, with minor intermediate to felsic volcanic rocks. These greenstone belts appear to have formed in convergent margin geodynamic settings. Detailed field observations, contrasting ages, and metamorphic and structural histories suggest that this craton was assembled in several accretionary tectonothermal events, involving accretion of arcs, back-arcs, forearcs, and continental fragments by horizontal tectonics. The Superior Province of Canada was also built by the amalgamation of oceanic and continental fragments ranging in age from 3700 to 2650 Ma, during five discrete tectonothermal events over 40 Ma between 2720 and 2680 Ma. The Neoarchaean (2750–2670 Ma) Wawa greenstone belts are composed of tectonically juxtaposed fragments of oceanic plateaux, oceanic island arcs, back-arcs, and siliciclastic trench turbidites. Following juxtaposition, these diverse lithologies were collectively intruded by syn- to post-kinematic granitoids with subduction zone geochemical signatures. Oceanic island arc lavas are easily distinguished from oceanic plateau counterparts because they possess positively fractionated rare earth element (La/Smcn> 1 and Gd/Ybcn> 1) and high field strength element depleted (Nb/Thpm< 1; Nb/Lapm< 1) patterns. In addition, the island arc association includes pyroclastic rocks that are rare to absent in the oceanic plateau volcanic association. Structural studies indicate that the Wawa greenstone belts underwent a complex history of deformation including thrusting, strike-slip faulting, and asymmetric folding. These belts constitute part of ac. 1000 km scale subduction–accretion complex that formed along an intra-oceanic convergent plate margin during trenchward migration of the magmatic arc axis. Several first-order geological observations on Archaean greenstone belts of SW Greenland and the Superior Province suggest that Phanerozoic-style plate-tectonic models can provide an elegant explanation for their structural, lithological, metamorphic and geochemical characteristics.
Palaeoproterozoic accretionary processes in Fennoscandia
Authors: Lahtinen Raimo , Korja Annakaisa , Nironen Mikko , Heikkinen Pekka
Published: June 2009

Accretionary processes contributed to major continental growth in Fennoscandia during the Palaeoproterozoic, mainly from 2.1 to 1.8 Ga. The composite Svecofennian orogen covers
c
. 1×10
6
km
2
and comprises the Lapland–Savo, Fennia, Svecobaltic and Nordic orogens. It is a collage of 2.1–2.0 Ga microcontinents and 2.02–1.82 Ga island arcs attached to the Archaean Karelian craton between 1.92 and 1.79 Ga. Andean-type vertical magmatic additions, especially at
c
. 1.89 and
c
. 1.8 Ga, were also important in the continental growth. The Palaeoproterozoic crust is the end product of accretionary growth, continental collision and orogenic collapse. Preserved accretional sections are found in areas where docking of rigid blocks has prevented further shortening. The Pirkanmaa belt represents a composite accretionary prism, and other preserved palaeosubduction zones are identified in the Gulf of Bothnia and the Baltic Sea areas. In the southern segment of the Lapland–Savo orogen collision between the Archaean continent (lower plate) and the Palaeoproterozoic arc–microcontinent assembly (upper plate) produced a special type of lateral crustal growth: the Archaean continental edge decoupled from its mantle during initial collision and overrode the arc and its mantle during continued collision.
The Neurobiology of Individual Differences in Complex Behavioral Traits
Authors: Hariri Ahmad R.
Published: June 2009

Neuroimaging, especially BOLD fMRI, has begun to identify how variability in brain function contributes to individual differences in complex behavioral traits. In parallel, pharmacological fMRI and multimodal PET/fMRI are identifying how variability in molecular signaling pathways influences individual differences in brain function. Against this background, functional genetic polymorphisms are being utilized to understand the origins of variability in signaling pathways as well as to model efficiently how such emergent variability impacts behaviorally relevant brain function. This article provides an overview of a research strategy seeking to integrate these complementary technologies and utilizes existing empirical data to illustrate its effectiveness in illuminating the neurobiology of individual differences in complex behavioral traits. The article also discusses how such efforts can contribute to the identification of predictive markers that interact with environmental factors to precipitate disease and to develop more effective and individually tailored treatment regimes.
Synaptic Mechanisms for Plasticity in Neocortex
Authors: Feldman Daniel E.
Published: June 2009

Sensory experience and learning alter sensory representations in cerebral cortex. The synaptic mechanisms underlying sensory cortical plasticity have long been sought. Recent work indicates that long-term cortical plasticity is a complex, multicomponent process involving multiple synaptic and cellular mechanisms. Sensory use, disuse, and training drive long-term potentiation and depression (LTP and LTD), homeostatic synaptic plasticity and plasticity of intrinsic excitability, and structural changes including formation, removal, and morphological remodeling of cortical synapses and dendritic spines. Both excitatory and inhibitory circuits are strongly regulated by experience. This review summarizes these findings and proposes that these mechanisms map onto specific functional components of plasticity, which occur in common across the primary somatosensory, visual, and auditory cortices.
The Neuropsychopharmacology of Fronto-Executive Function: Monoaminergic Modulation
Authors: Robbins T.W. , Arnsten A.F.T.
Published: June 2009

We review the modulatory effects of the catecholamine neurotransmitters noradrenaline and dopamine on prefrontal cortical function. The effects of pharmacologic manipulations of these systems, sometimes in comparison with the indoleamine serotonin (5-HT), on performance on a variety of tasks that tap working memory, attentional-set formation and shifting, reversal learning, and response inhibition are compared in rodents, nonhuman primates, and humans using, in a behavioral context, several techniques ranging from microiontophoresis and single-cell electrophysiological recording to pharmacologic functional magnetic resonance imaging. Dissociable effects of drugs and neurotoxins affecting these monoamine systems suggest new ways of conceptualizing state-dependent fronto-executive functions, with implications for understanding the molecular genetic basis of mental illness and its treatment.
Advances in Light Microscopy for Neuroscience
Authors: Wilt Brian A. , Burns Laurie D. , Wei Ho Eric Tatt , Ghosh Kunal K. , Mukamel Eran A. , Schnitzer Mark J.
Published: June 2009

Since the work of Golgi and Cajal, light microscopy has remained a key tool for neuroscientists to observe cellular properties. Ongoing advances have enabled new experimental capabilities using light to inspect the nervous system across multiple spatial scales, including ultrastructural scales finer than the optical diffraction limit. Other progress permits functional imaging at faster speeds, at greater depths in brain tissue, and over larger tissue volumes than previously possible. Portable, miniaturized fluorescence microscopes now allow brain imaging in freely behaving mice. Complementary progress on animal preparations has enabled imaging in head-restrained behaving animals, as well as time-lapse microscopy studies in the brains of live subjects. Mouse genetic approaches permit mosaic and inducible fluorescence-labeling strategies, whereas intrinsic contrast mechanisms allow in vivo imaging of animals and humans without use of exogenous markers. This review surveys such advances and highlights emerging capabilities of particular interest to neuroscientists.
The Glial Nature of Embryonic and Adult Neural Stem Cells
Authors: Kriegstein Arnold , Alvarez-Buylla Arturo
Published: June 2009

Glial cells were long considered end products of neural differentiation, specialized supportive cells with an origin very different from that of neurons. New studies have shown that some glial cells—radial glia (RG) in development and specific subpopulations of astrocytes in adult mammals—function as primary progenitors or neural stem cells (NSCs). This is a fundamental departure from classical views separating neuronal and glial lineages early in development. Direct visualization of the behavior of NSCs and lineage-tracing studies reveal how neuronal lineages emerge. In development and in the adult brain, many neurons and glial cells are not the direct progeny of NSCs, but instead originate from transit amplifying, or intermediate, progenitor cells (IPCs). Within NSCs and IPCs, genetic programs unfold for generating the extraordinary diversity of cell types in the central nervous system. The timing in development and location of NSCs, a property tightly linked to their neuroepithelial origin, appear to be the key determinants of the types of neurons generated. Identification of NSCs and IPCs is critical to understand brain development and adult neurogenesis and to develop new strategies for brain repair.