bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy and density analyses of the H2 molecule from the united atom to dissociation: The ∑1g+ states
Authors: Corongiu Giorgina , Clementi Enrico
Published: July 2009

The first 15 ∑1g+ states of the H2 molecule are computed with full configuration interaction (CI) both from Hartree–Fock molecular orbitals and Heitler–London atomic orbitals; the computations are correlated with a comprehensive analysis. The basis sets utilized are extended and optimized Slater-type functions [Slater-type orbital (STO)] and spherical Gaussian functions [Gaussian-type orbital (GTO)]. The full CI computations cover the internuclear distances from 0.01 to 10 000 bohr. The available accurate data by Wolniewicz and co-workers for the first five excited states verify the quality of our computations. We focus on the characterization of the orbitals in the wave functions, on the electronic density evolution from the united atom to dissociation, on quantitative decomposition of the total energy into covalent and ionic components, and on detailed analyses of energy contributions to the total state energy from selected STO and GTO subsets. These analyses lead to study (with full CI) the H− negative ion with a proton and the H+H− ion pair systems. The ground and excited states for the He and H atoms and for the H− ion are computed to discuss the united atom and the dissociation products H(1s)+H(nl) of the n state manifolds. With the exception of n=1, each manifold has one state, specifically the EF, H, 7, and 11, whose second minimum has strong ionic character; state 11 dissociates as H+H−.
Water adsorption onto Y and V sites at the surface of the YVO4 photocatalyst and related electronic properties
Authors: Oshikiri Mitsutake , Boero Mauro , Matsushita Akiyuki , Ye Jinhua
Published: July 2009

The dynamics of water molecules and the adsorption properties at the V and Y sites on the surface of the photocatalyst YVO4 have been investigated by first principles molecular dynamics. This system has shown an excellent performance in the production of both hydrogen and oxygen in the ultraviolet region. Yet, its catalytic properties, related to the electronic structure, are poorly understood. Here we show that imperfectly oxygen coordinated V sites (i.e., not fourfold oxygen coordinated vanadium but threefold oxygen coordinated vanadium) exposed on the catalyst surface play a central role in the dissociation of water molecules. By simulating the H2O adsorption process and by performing an analysis of the electronic structure of the unoccupied orbitals corresponding to the lowest unoccupied energy level of the system, we can infer that the dissociation of water at these imperfectly oxygen coordinated V sites can promote the proton reduction and is expected to trigger the H2 generation.
Do fluorescence and transient absorption probe the same intramolecular charge transfer state of 4-(dimethylamino)benzonitrile?
Authors: Gustavsson Thomas , Coto Pedro B. , Serrano-Andrés Luis , Fujiwara Takashige , Lim Edward C.
Published: July 2009

We present here the results of time-resolved absorption and emission experiments for 4-(dimethylamino)benzonitrile in solution, which suggest that the fluorescent intramolecular charge transfer (ICT) state may differ from the twisted ICT (TICT) state observed in transient absorption.
Invited Article: High resolution digital camera for infrared reflectography
Authors: Falco Charles M.
Published: July 2009

This paper describes the characteristics of a high resolution infrared (IR) imaging system operating over the wavelength range of 830–1100 nm, based on a modified 8 Mpixels commercial digital camera, with which nonspecialists can obtain IR reflectograms of works of art in situ in a museum environment. The relevant imaging properties of sensitivity, resolution, noise, and contrast are characterized and the capabilities of this system are illustrated with an example that has revealed important new information about the working practices of a 16th century artist.
Large amplitude ion-acoustic solitary waves and double layers in multicomponent plasma with positrons
Authors: Sabry R.
Published: July 2009

A finite amplitude theory for ion-acoustic solitary waves and double layers in multicomponent plasma consisting of hot positrons, cold ions, and electrons with two-electron temperature distributions is presented. Conditions are obtained under which large amplitude stationary ion-acoustic solitary waves and double layers can exist. For the physical parameters of interest, the ion-acoustic solitary wave (double layers) profiles and the relationship between the maximum soliton (double layers) amplitude and the Mach number are found. Also, we have presented the region of existence of the large amplitude ion-acoustic waves by analyzing the structure of the pseudopotential. For the selected range of parameters, it is found that only positive solitary waves and double layers can exist. An analysis for the small amplitude limit through the Sagdeev pseudopotential analysis and the reductive perturbation theory shows the existence of positive and negative ion-acoustic solitary waves and double layers. The effects of positron concentration and temperature ratio on the characteristics of the solitary ion-acoustic waves and double layers (namely, the amplitude and width) are discussed in detail. The relevance of this investigation to space and laboratory plasmas is pointed out.
The mechanism of sound generation in the interaction between a shock wave and two counter-rotating vortices
Authors: Zhang Shuhai , Jiang Shufen , Zhang Yong-Tao , Shu Chi-Wang
Published: July 2009

The interaction between a shock wave and two counter-rotating vortices is simulated systematically through solving the two-dimensional, unsteady, compressible Navier–Stokes equations using a fifth order weighted essentially nonoscillatory finite difference scheme. The main purpose of this study is to reveal the mechanism of sound generation in the interaction between a shock wave and two counter-rotating vortices. It is found that there are two regimes of sound generation in this interaction. The first regime corresponds to the shock interaction with two isolated vortices, in which the sound wave generated by the interaction between the shock wave and two counter-rotating vortices equals to the linear combination of the sound waves generated by the interactions between the same shock wave and each vortex. The second regime corresponds to the shock interaction with a coupled vortex pair, in which the sound wave comes from two processes. One is the vortex coupling, and the second is the interaction between the shock wave and the coupled vortex pair.
Broadband electromagnetic-wave absorption by FeCo/C nanocapsules
Authors: Han Z. , Li D. , Wang H. , Liu X. G. , Li J. , Geng D. Y. , Zhang Z. D.
Published: July 2009

Electromagnetic-wave absorption by FeCo/C nanocapsules has been investigated. In contrast to earlier reported materials, including other nanocapsules, the absorption amplitude of FeCo/C nanocapsules is found not to decrease with increasing absorption-layer thickness. A reflection loss (RL) exceeding −20 dB can be obtained for all frequencies within the 2–18 GHz range by choosing an appropriate layer thickness between 1.6 and 8.5 mm. The broadest bandwidth (RL values exceeding −10 dB) from 10 to 18 GHz, covering half of the X-band and the whole Ku-band, is obtained for a 2 mm layer.
Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow
Authors: Turkyilmazoglu M.
Published: July 2009

This paper is devoted to the investigation of three primary linear instability mechanisms due to the resonating disturbance waves present in the three-dimensional incompressible viscous/inviscid rotating disk boundary layer flow, extending our earlier still outer fluid work [M. Turkyilmazoglu, “Resonance instabilities on the boundary layer flow over a rotating-disk under the influence of a uniform magnetic field,” J. Eng. Math. 59, 337 (2007)] to a uniform nonzero radial flow. A spatiotemporal linear stability analysis is conducted to search for the influences of physical parameters on the possible important mechanisms of resonances leading to, respectively, the absolute instability, the direct spatial instability, and the direct temporal instability. The radial flow is shown to act in the way of stabilizing all the possible mechanisms considered, more pronouncedly as the magnetic field gets strengthened. The onset of absolute instability and convective temporal instability is found to be more sensitive to the variations in the radial flow than is the onset of convective direct spatial instability. Although a considerable delay of the onset of absolute instability as well as temporal instability can be achieved by increasing the magnitude of the radial flow, the direct spatial resonance instability mechanism persists to occur for low Reynolds numbers, while the flow is still in the laminar regime, which is expected to trigger nonlinearity just prior to transition to turbulence.
Elliptical instability of a rapidly rotating, strongly stratified fluid
Authors: Aspden J. M. , Vanneste J.
Published: July 2009

The elliptical instability of a rotating stratified fluid is examined in the regime of a small Rossby number and order-one Burger number corresponding to rapid rotation and strong stratification. The Floquet problem describing the linear growth of disturbances to an unbounded, uniform-vorticity elliptical flow is solved using exponential asymptotics. The results demonstrate that the flow is unstable for arbitrarily strong rotation and stratification; in particular, both cyclonic and anticyclonic flows are unstable. The instability is weak, however, with growth rates that are exponentially small in the Rossby number. The analytic expression obtained for the growth rate elucidates its dependence on the Burger number and on the eccentricity of the elliptical flow. It explains, in particular, the weakness of the instability of cyclonic flows, with growth rates that are only a small fraction of those obtained for the corresponding anticyclonic flows. The asymptotic results are confirmed by numerical solutions of the Floquet problem.
On the surface roughness development of hydrogenated amorphous silicon deposited at low growth rates
Authors: Wank M. A. , van Swaaij R. A. C. M. M. , van de Sanden M. C. M.
Published: July 2009

The surface roughness evolution of hydrogenated amorphous silicon (a-Si:H) films has been studied using in situ spectroscopic ellipsometry for a temperature range of 150–400 °C. The effect of external rf substrate biasing on the coalescence phase is discussed and a removal/densification of a hydrogen-rich layer is suggested to explain the observed roughness development in this phase. After coalescence we observe two distinct phases in the roughness evolution and highlight trends which are incompatible with the idea of dominant surface diffusion. Alternative, nonlocal mechanisms such as the re-emission effect are discussed, which can partly explain the observed incompatibilities.
GABA
A
receptor membrane trafficking regulates spine maturity
Authors: Jacob Tija C. , Wan Qin , Vithlani Mansi , Saliba Richard S. , Succol Francesca , Pangalos Menelas N. , Moss Stephen J.
Published: July 2009

GABA
A
receptors (GABA
A
Rs), the principal sites of synaptic inhibition in the brain, are dynamic entities on the neuronal cell surface, but the role their membrane trafficking plays in shaping neuronal activity remains obscure. Here, we examined this by using mutant receptor β3 subunits (β3S408/9A), which have reduced binding to the clathrin adaptor protein-2, a critical regulator of GABA
A
R endocytosis. Neurons expressing β3S408/9A subunits exhibited increases in the number and size of inhibitory synapses, together with enhanced inhibitory synaptic transmission due to reduced GABA
A
R endocytosis. Furthermore, neurons expressing β3S408/9A subunits had deficits in the number of mature spines and reduced accumulation of postsynaptic density protein-95 at excitatory synapses. This deficit in spine maturity was reversed by pharmacological blockade of GABA
A
Rs. Therefore, regulating the efficacy of synaptic inhibition by modulating GABA
A
R membrane trafficking may play a critical role in regulating spine maturity with significant implications for synaptic plasticity together with behavior.
Sequence-independent and reversible photocontrol of transcription/expression systems using a photosensitive nucleic acid binder
Authors: Estévez-Torres André , Crozatier Cécile , Diguet Antoine , Hara Tomoaki , Saito Hirohide , Yoshikawa Kenichi , Baigl Damien
Published: July 2009

To understand non-trivial biological functions, it is crucial to develop minimal synthetic models that capture their basic features. Here, we demonstrate a sequence-independent, reversible control of transcription and gene expression using a photosensitive nucleic acid binder (pNAB). By introducing a pNAB whose affinity for nucleic acids is tuned by light, in vitro RNA production, EGFP translation, and GFP expression (a set of reactions including both transcription and translation) were successfully inhibited in the dark and recovered after a short illumination at 365 nm. Our results indicate that the accessibility of the protein machinery to one or several nucleic acid binding sites can be efficiently regulated by changing the conformational/condensation state of the nucleic acid (DNA conformation or mRNA aggregation), thus regulating gene activity in an efficient, reversible, and sequence-independent manner. The possibility offered by our approach to use light to trigger various gene expression systems in a system-independent way opens interesting perspectives to study gene expression dynamics as well as to develop photocontrolled biotechnological procedures.
WebArrayDB: cross-platform microarray data analysis and public data repository
Authors: Xia Xiao-Qin , McClelland Michael , Porwollik Steffen , Song Wenzhi , Cong Xianling , Wang Yipeng
Published: July 2009

Motivation: Cross-platform microarray analysis is an increasingly important research tool, but researchers still lack open source tools for storing, integrating and analyzing large amounts of microarray data obtained from different array platforms.

Results: An open source integrated microarray database and analysis suite, WebArrayDB (http://www.webarraydb.org), has been developed that features convenient uploading of data for storage in a MIAME (Minimal Information about a Microarray Experiment) compliant fashion, and allows data to be mined with a large variety of R-based tools, including data analysis across multiple platforms. Different methods for probe alignment, normalization and statistical analysis are included to account for systematic bias. Student's t-test, moderated t-tests, non-parametric tests and analysis of variance or covariance (ANOVA/ANCOVA) are among the choices of algorithms for differential analysis of data. Users also have the flexibility to define new factors and create new analysis models to fit complex experimental designs. All data can be queried or browsed through a web browser. The computations can be performed in parallel on symmetric multiprocessing (SMP) systems or Linux clusters.

Availability: The software package is available for the use on a public web server (http://www.webarraydb.org) or can be downloaded.

Contact:  xqxia70@gmail.com; mcclelland.michael@gmail.com; yipengw@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
Paused Pol II captures enhancer activity and acts as a potent insulator
Authors: Core Leighton J. , Lis John T.
Published: July 2009

Enhancers act over many kilobase pairs to activate target promoters, but their activity is constrained by insulator elements that prevent indiscriminate activation of nearby genes. In the July 1, 2009, issue of Genes & Development, Chopra and colleagues (pp. 1505–1509) report that promoters containing a stalled Pol II are activated by enhancers, but these promoters also serve as insulators that block enhancers from reaching more distal genes. This new class of insulators provide critical clues to regulatory mechanisms.
SMN-assisted assembly of snRNP-specific Sm cores in trypanosomes
Authors: Palfi Zsofia , Jaé Nicolas , Preußer Christian , Kaminska Katarzyna H. , Bujnicki Janusz M. , Lee Ju Huck , Günzl Arthur , Kambach Christian , Urlaub Henning , Bindereif Albrecht
Published: July 2009

Spliceosomal small nuclear ribonucleoproteins (snRNPs) in trypanosomes contain either the canonical heptameric Sm ring (U1, U5, spliced leader snRNPs), or variant Sm cores with snRNA-specific Sm subunits (U2, U4 snRNPs). Searching for specificity factors, we identified SMN and Gemin2 proteins that are highly divergent from known orthologs. SMN is splicing-essential in trypanosomes and nuclear-localized, suggesting that Sm core assembly in trypanosomes is nuclear. We demonstrate in vitro that SMN is sufficient to confer specificity of canonical Sm core assembly and to discriminate against binding to nonspecific RNA and to U2 and U4 snRNAs. SMN interacts transiently with the SmD3B subcomplex, contacting specifically SmB. SMN remains associated throughout the assembly of the Sm heteroheptamer and dissociates only when a functional Sm site is incorporated. These data establish a novel role of SMN, mediating snRNP specificity in Sm core assembly, and yield new biochemical insight into the mechanism of SMN activity.
The ClinSeq Project: Piloting large-scale genome sequencing for research in genomic medicine
Authors: Biesecker Leslie G. , Mullikin James C. , Facio Flavia M. , Turner Clesson , Cherukuri Praveen F. , Blakesley Robert W. , Bouffard Gerard G. , Chines Peter S. , Cruz Pedro , Hansen Nancy F. , Teer Jamie K. , Maskeri Baishali , Young Alice C. ,   NISC Comparative Sequencing Program, Manolio Teri A. , Wilson Alexander F. , Finkel Toren , Hwang Paul , Arai Andrew , Remaley Alan T. , Sachdev Vandana , Shamburek Robert , Cannon Richard O. , Green Eric D.
Published: July 2009

ClinSeq is a pilot project to investigate the use of whole-genome sequencing as a tool for clinical research. By piloting the acquisition of large amounts of DNA sequence data from individual human subjects, we are fostering the development of hypothesis-generating approaches for performing research in genomic medicine, including the exploration of issues related to the genetic architecture of disease, implementation of genomic technology, informed consent, disclosure of genetic information, and archiving, analyzing, and displaying sequence data. In the initial phase of ClinSeq, we are enrolling roughly 1000 participants; the evaluation of each includes obtaining a detailed family and medical history, as well as a clinical evaluation. The participants are being consented broadly for research on many traits and for whole-genome sequencing. Initially, Sanger-based sequencing of 300–400 genes thought to be relevant to atherosclerosis is being performed, with the resulting data analyzed for rare, high-penetrance variants associated with specific clinical traits. The participants are also being consented to allow the contact of family members for additional studies of sequence variants to explore their potential association with specific phenotypes. Here, we present the general considerations in designing ClinSeq, preliminary results based on the generation of an initial 826 Mb of sequence data, the findings for several genes that serve as positive controls for the project, and our views about the potential implications of ClinSeq. The early experiences with ClinSeq illustrate how large-scale medical sequencing can be a practical, productive, and critical component of research in genomic medicine.
Instrumenting the health care enterprise for discovery research in the genomic era
Authors: Murphy Shawn , Churchill Susanne , Bry Lynn , Chueh Henry , Weiss Scott , Lazarus Ross , Zeng Qing , Dubey Anil , Gainer Vivian , Mendis Michael , Glaser John , Kohane Isaac
Published: July 2009

Tens of thousands of subjects may be required to obtain reliable evidence relating disease characteristics to the weak effects typically reported from common genetic variants. The costs of assembling, phenotyping, and studying these large populations are substantial, recently estimated at three billion dollars for 500,000 individuals. They are also decade-long efforts. We hypothesized that automation and analytic tools can repurpose the informational byproducts of routine clinical care, bringing sample acquisition and phenotyping to the same high-throughput pace and commodity price-point as is currently true of genome-wide genotyping. Described here is a demonstration of the capability to acquire samples and data from densely phenotyped and genotyped individuals in the tens of thousands for common diseases (e.g., in a 1-yr period:N= 15,798 for rheumatoid arthritis;N= 42,238 for asthma;N= 34,535 for major depressive disorder) in one academic health center at an order of magnitude lower cost. Even for rare diseases caused by rare, highly penetrant mutations such as Huntington disease (N= 102) and autism (N= 756), these capabilities are also of interest.
Comparative Analysis between Homoeologous Genome Segments ofBrassica napusand Its Progenitor Species Reveals Extensive Sequence-Level Divergence
Authors: Cheung Foo , Trick Martin , Drou Nizar , Lim Yong Pyo , Park Jee-Young , Kwon Soo-Jin , Kim Jin-A , Scott Rod , Pires J. Chris , Paterson Andrew H. , Town Chris , Bancroft Ian
Published: July 2009

Homoeologous regions of Brassica genomes were analyzed at the sequence level. These represent segments of the Brassica A genome as found in Brassica rapa and Brassica napus and the corresponding segments of the Brassica C genome as found in Brassica oleracea and B. napus. Analysis of synonymous base substitution rates within modeled genes revealed a relatively broad range of times (0.12 to 1.37 million years ago) since the divergence of orthologous genome segments as represented in B. napus and the diploid species. Similar, and consistent, ranges were also identified for single nucleotide polymorphism and insertion-deletion variation. Genes conserved across the Brassica genomes and the homoeologous segments of the genome of Arabidopsis thaliana showed almost perfect collinearity. Numerous examples of apparent transduplication of gene fragments, as previously reported in B. oleracea, were observed in B. rapa and B. napus, indicating that this phenomenon is widespread in Brassica species. In the majority of the regions studied, the C genome segments were expanded in size relative to their A genome counterparts. The considerable variation that we observed, even between the different versions of the same Brassica genome, for gene fragments and annotated putative genes suggest that the concept of the pan-genome might be particularly appropriate when considering Brassica genomes.
Analysis of focused-beam powder X-ray diffraction resolution using doubly curved crystal optics
Authors: Bingölbali A. , MacDonald C. A.
Published: July 2009

In this work, focusing doubly curved crystal X-ray optics were used in powder diffraction to produce an intense spot for use with small powder or polycrystalline samples. Measurements of several standard small inorganic samples were made using a low-power microfocus source. Diffracted peak width, resolution and intensity were analyzed. The measured resolution, defined as the uncertainty in the peak center, was much smaller than the peak width, which was broadened owing to the use of a focused beam. Resolution was limited by the pixel size of the area detector. Resolution and intensity measurements were in good agreement with those obtained from simple geometric analysis and from a Monte Carlo model used to simulate the diffraction ring shape and width.
High-resolution X-ray microdiffraction analysis of NaOH-treated dentin
Authors: Wei Wei , Jing Mao , Zhou Peng , Jianzhong Xiao , Yan Liu , Shiqiang Gong , Dan Wang , Bin Zhou
Published: July 2009

Various kinds of basic chemicals interact with dentin directly in different clinical conditions. However, owing to the lack of appropriate models and technology, it is still not known how the mineral components of dentin react to these chemicals. The technology of high-resolution X-ray microdiffraction, in combination with scanning electron microscopy, has been applied to study the microstructure and minor crystallographic changes in a longitudinal dentin section before and after chemical treatment. Phase analysis was performed; the crystal sizes at two dentin sections were calculated from the reflections (002) and (211), and the crystal orientations of reflections (222), (213) and (002) were compared before and after treatment. The results show an inhomogeneity of the microstructure in dentin between the coronal and the root regions and that they react differently to basic treatment. In particular, NaOH treatment causes a change in crystal sizes and disorder.
Automatic multiple-zone rigid-body refinement with a large convergence radius
Authors: Afonine Pavel V. , Grosse-Kunstleve Ralf W. , Urzhumtsev Alexandre , Adams Paul D.
Published: July 2009

Rigid-body refinement is the constrained coordinate refinement of one or more groups of atoms that each move (rotate and translate) as a single body. The goal of this work was to establish an automatic procedure for rigid-body refinement which implements a practical compromise between runtime requirements and convergence radius. This has been achieved by analysis of a large number of trial refinements for 12 classes of random rigid-body displacements (that differ in magnitude of introduced errors), using both least-squares and maximum-likelihood target functions. The results of these tests led to a multiple-zone protocol. The final parameterization of this protocol was optimized empirically on the basis of a second large set of test refinements. This multiple-zone protocol is implemented as part of thephenix.refineprogram.
Diffraction anomalous fine structure study of iron/iron oxide nanoparticles
Authors: Meneghini Carlo , Boscherini Federico , Pasquini Luca , Renevier Hubert
Published: July 2009

Diffraction anomalous fine structure is a recently developed technique which can provide a measurement of the local structure of a given element in a particular phase or crystallographic site. Most previous investigations have applied the technique to bulk solids, thin films, and nano-dots or wires on crystalline substrates. In this paper, the technique is applied to highly disordered nanometre-sized Fe/Fe oxide core–shell nanocrystalline powders, the diffraction patterns of which exhibit weak and greatly broadened diffraction peaks. Focusing on the oxide shell diffraction peaks, a qualitative analysis of the near-edge spectral region and a quantitative analysis of the extended energy region are provided; in particular, good quality fittings of the extended range spectra are obtained. The local structure is selectively probed around the tetrahedral and octahedral sites of the oxide shell, finding the presence of a high degree of structural disorder. This study demonstrates that diffraction anomalous fine structure can now be fruitfully applied to nanocrystalline powders.
Is Privacy at Risk when Commercial Websites Target Primary School Children? A Case Study in Korea
Authors: Kim Sora , Yi Soon‐Hyung
Published: July 2009

This study discusses privacy risk factors when commercial web sites target primary school children in Korea. Specifically, the authors examined types of personal information required for membership subscriptions and whether privacy policies at commercial sites for children abide by privacy guidelines. A total of 159 commercial sites targeting children were selected for content analysis. The findings showed that most sites provided a mailing service for children. Critical problems in parental consent procedures also were found. Privacy policies at sites frequently omitted important principles, such as the specific purpose for the information being collected or protection of personal information. The study concluded with general suggestions to protect child privacy for online marketers targeting children and for parents.
Cloud forest dynamics in the Mexican neotropics during the last 1300 years
Authors: FIGUEROA‐RANGEL BLANCA L. , WILLIS KATHY J. , OLVERA‐VARGAS MIGUEL
Published: July 2009

Key questions for understanding the resilience and variability of Mexican Neotropical cloud forest assemblages in current and future climate change include: How have human disturbances and climate change affected the dynamics of the cloud forest assemblage? What are the predominant processes responsible for its present day composition and distribution? Are the current conservation strategies for the cloud forest in accordance with preserving its natural variability through time? In this study, the temporal dynamics of the cloud forest in west‐central Mexico over the last ∼1300 years were reconstructed using palaeoecological techniques. These included analyses of fossil pollen, microfossil charcoal, and sediment geochemistry. Results indicated that a cloud forest assemblage has been the predominant vegetation type in this region over the last ∼1300 years. During this time, however, there have been changes in the vegetation with an apparent expansion of cloud forest from ∼832 to 620 cal years bp and a decline from 1200 to 832 cal years bp. Climate change (intervals of aridity) and human disturbances through anthropogenic burning appear to have been the main factors influencing the dynamics of this cloud forest. The spatial heterogeneity reported for high‐altitude forests in this region, in concert with high beta diversity, appears to be a manifestation of the high temporal variability in species composition for these forests. Greater turnover in cloud forest taxa occurred during intervals of increased humidity and is probably representative of a higher temporal competition for resources among the cloud forest taxa. The present results support the current protection scheme for cloud forests in west‐central Mexico where areas are kept in exclusion zones to avoid timber extraction, grazing, and agriculture; this will maintain diversity within these forests, even if there are only a few individuals per species, and enable the forests to retain some resilience to current and future climate change.
Neuronal and glial localization of the cannabinoid‐1 receptor in the superficial spinal dorsal horn of the rodent spinal cord
Authors: Hegyi Zoltán , Kis Gréta , Holló Krisztina , Ledent Catherine , Antal Miklós
Published: July 2009

A long line of experimental evidence indicates that endogenous cannabinoid mechanisms play important roles in nociceptive information processing in various areas of the nervous system including the spinal cord. Although it is extensively documented that the cannabinoid‐1 receptor (CB1‐R) is strongly expressed in the superficial spinal dorsal horn, its cellular distribution is poorly defined, hampering our interpretation of the effect of cannabinoids on pain processing spinal neural circuits. Thus, we investigated the cellular distribution of CB1‐Rs in laminae I and II of the rodent spinal dorsal horn with immunocytochemical methods. Axonal varicosities revealed a strong immunoreactivity for CB1‐R, but no CB1‐R expression was observed on dendrites and perikarya of neurons. Investigating the co‐localization of CB1‐R with markers of peptidergic and non‐peptidergic primary afferents, and axon terminals of putative glutamatergic and GABAergic spinal neurons we found that nearly half of the peptidergic (immunoreactive for calcitonin gene‐related peptide) and more than 20% of the non‐peptidergic (binding isolectin B4) nociceptive primary afferents, more than one‐third and approximately 20% of the axon terminals of putative glutamatergic (immunoreactive for vesicular glutamate transporter 2) and GABAergic (immunoreactive for glutamic acid decarboxylase; GAD65 and/or GAD67) spinal interneurons, respectively, were positively stained for CB1‐R. In addition to axon terminals, almost half of the astrocytic (immunoreactive for glial fibrillary acidic protein) and nearly 80% of microglial (immunoreactive for CD11b) profiles were also immunolabeled for CB1‐R. The findings suggest that the activity‐dependent release of endogenous cannabinoids activates a complex signaling mechanism in pain processing spinal neural circuits into which both neurons and glial cells may contribute.
On how the motor cortices resolve an inter‐hemispheric response conflict: an event‐related EEG potential‐guided TMS study of the flankers task
Authors: Verleger Rolf , Kuniecki Michał , Möller Friderike , Fritzmannova Michaela , Siebner Hartwig R.
Published: July 2009

An important aspect of human motor control is the ability to resolve conflicting response tendencies. Here we used single‐pulse transcranial magnetic stimulation (TMS) to track the time course of excitability changes in the primary motor hand areas (M1HAND) while the motor system resolved response conflicts. Healthy volunteers had to respond fast with their right and left index fingers to right‐ and left‐pointing arrows. These central target stimuli were preceded by flanking arrows, inducing premature response tendencies which competed with correct response activation. The time point of maximum premature activation was individually measured as peak latency of the lateralized readiness potential (LRP) in the EEG. In the subsequent TMS experiment, single pulses were applied to left or right M1HAND during the same flanker task. The amplitude of the motor evoked potentials in the contralateral first dorsal interosseus muscle was taken as an index of corticospinal excitability. Guided by the previous LRP measurement, magnetic stimuli were applied 0–90 ms after the individual LRP peak, to cover the epoch of conflict resolution. When flankers were incompatible with the target, excitability of the prematurely activated M1HAND gradually decreased during this 90 ms period. This decrease was paralleled by a mirror‐symmetrical increase in excitability in the other M1HAND. These results show that the inappropriate response tendency is cancelled in one M1HAND simultaneously with activation of the correct response in the other. This integrated implementation of response activation and cancellation at the level of the M1HAND presumably represents a downstream effect orchestrated by premotor brain regions.
Neural correlates of evaluative compared with passive tasting
Authors: Bender Genevieve , Veldhuizen Maria G. , Meltzer Jed A. , Gitelman Darren R. , Small Dana M.
Published: July 2009

We used functional magnetic resonance imaging to test the hypothesis that the nature of the neural response to taste varies as a function of the task the subject is asked to perform. Subjects received sweet, sour, salty and tasteless solutions passively and while evaluating stimulus presence, pleasantness and identity. Within the insula and overlying operculum the location of maximal response to taste vs. tasteless varied as a function of task; however, the primary taste cortex (anterior dorsal insula/frontal operculum – AIFO), as well as a more ventral region of anterior insula, responded to taste vs. tasteless irrespective of task. Although the response here did not depend upon task, preferential connectivity between AIFO and the amygdala (bilaterally) was observed when subjects tasted passively compared with when they performed a task. This suggests that information transfer between AIFO and the amygdala is maximal during implicit processing of taste. In contrast, a region of the left lateral orbitofrontal cortex (OFC) responded preferentially to taste and to tasteless when subjects evaluated pleasantness, and was preferentially connected to earlier gustatory relays (caudomedial OFC and AIFO) when a taste was present. This suggests that processing in the lateral OFC organizes the retrieval of gustatory information from earlier relays in the service of computing perceived pleasantness. These findings show that neural encoding of taste varies as a function of task beyond that of the initial cortical representation.
Dopamine D1‐like receptor antagonism in amygdala impairs the acquisition of glucose‐conditioned flavor preference in rats
Authors: Touzani Khalid , Bodnar Richard J. , Sclafani Anthony
Published: July 2009

This study examined the role of dopamine within the amygdala (AMY) in flavor preference learning induced by post‐oral glucose. In Experiment 1, rats were trained with a flavor [conditioned stimulus (CS+)] paired with intragastric (IG) infusions of 8% glucose and a different flavor (CS−) paired with IG water infusions. The CS+ preference was evaluated in two‐bottle tests following bilateral injection of the dopamine D1‐like receptor antagonist, SCH23390 (SCH), into the AMY at total doses of 0, 12, 24 and 48 nmol. SCH produced dose‐dependent reductions in CS+ intake but did not block the CS+ preference except at the two highest doses, which also greatly suppressed the CS intakes. In Experiment 2, new rats were injected daily in the AMY with either saline or SCH (12 nmol), prior to training sessions with CS+/IG glucose and CS−/IG water. In the two‐bottle tests, SCH rats, unlike the control rats, failed to prefer the CS+ (55 vs. 81%). In Experiments 3 and 4, new rats were trained as in Experiment 2, except that brain injections were in the basolateral and central nuclei of the AMY, respectively. SCH rats learned to prefer the CS+ to the CS−, although their preference was weaker than that displayed by the control rats (Experiment 3: 59 vs. 80%; Experiment 4: 73 vs. 88%). These results show an essential role for D1‐like receptor activation in the AMY in the acquisition of flavor preference learning induced by the post‐oral reinforcing properties of glucose. A distributed network mediating flavor–nutrient incentive learning is discussed.
The chimpanzee brain shows human‐like perisylvian asymmetries in white matter
Authors: Cantalupo Claudio , Oliver Joanne , Smith Jarrod , Nir Talia , Taglialatela Jared P. , Hopkins William D.
Published: July 2009

Modern neuroimaging technologies allow scientists to uncover interspecies differences and similarities in hemispheric asymmetries that may shed light on the origin of brain asymmetry and its functional correlates. We analyzed asymmetries in ratios of white to grey matter in the lateral aspect of the lobes of the brains of chimpanzees. We found marked leftward asymmetries for all lobar regions. This asymmetry was particularly pronounced in the frontal region and was found to be related to handedness for communicative manual gestures as well as for tool use. These results point to a continuity in asymmetry patterns between the human and chimpanzee brain, and support the notion that the anatomical substrates for lateralization of communicative functions and complex manipulative activities may have been present in the common hominid ancestor.
Social Perception in Infancy: A Near Infrared Spectroscopy Study
Authors: Lloyd‐Fox Sarah , Blasi Anna , Volein Agnes , Everdell Nick , Elwell Claire E. , Johnson Mark H.
Published: July 2009

The capacity to engage and communicate in a social world is one of the defining characteristics of the human species. While the network of regions that compose the social brain have been the subject of extensive research in adults, there are limited techniques available for monitoring young infants. This study used near infrared spectroscopy to investigate functional activation in the social brain network of 36 five‐month‐old infants. We measured the hemodynamic responses to visually presented stimuli in the temporal lobes. A significant increase in oxyhemoglobin was localized to 2 posterior temporal sites bilaterally, indicating that these areas are involved in the social brain network in young infants.
Probing the Neural Correlates of Anticipated Peer Evaluation in Adolescence
Authors: Guyer Amanda E. , McClure‐Tone Erin B. , Shiffrin Nina D. , Pine Daniel S. , Nelson Eric E.
Published: July 2009

Neural correlates of social‐cognition were assessed in 9‐ to‐ 17‐year‐olds (N = 34) using functional magnetic resonance imaging. Participants appraised how unfamiliar peers they had previously identified as being of high or low interest would evaluate them for an anticipated online chat session. Differential age‐ and sex‐related activation patterns emerged in several regions previously implicated in affective processing. These included the ventral striatum, hippocampus, hypothalamus, and insula. In general, activation patterns shifted with age in older relative to younger females but showed no association with age in males. Relating these neural response patterns to changes in adolescent social‐cognition enriches theories of adolescent social development through enhanced neurobiological understanding of social behavior.
The Effects of Early Experience on Face Recognition: An Event‐Related Potential Study of Institutionalized Children in Romania
Authors: Moulson Margaret C. , Westerlund Alissa , Fox Nathan A. , Zeanah Charles H. , Nelson Charles A.
Published: July 2009

Data are reported from 3 groups of children residing in Bucharest, Romania. Face recognition in currently institutionalized, previously institutionalized, and never‐institutionalized children was assessed at 3 time points: preintervention (n = 121), 30 months of age (n = 99), and 42 months of age (n = 77). Children watched photographs of caregiver and stranger faces while event‐related potentials were recorded. Results demonstrate that institutionalized children show pervasive cortical hypoarousal in response to faces and that foster care is somewhat effective in remediating this deficit by 42 months of age. All 3 groups of children distinguished between the familiar and unfamiliar faces. These results have the potential to inform an understanding of the role of early experience in the development of the neural systems that subserve face recognition.
Interindividual Differences in Neonatal Imitation and the Development of Action Chains in Rhesus Macaques
Authors: Ferrari Pier Francesco , Paukner Annika , Ruggiero Angela , Darcey Lisa , Unbehagen Sarah , Suomi Stephen J.
Published: July 2009

The capacity to imitate facial gestures is highly variable in rhesus macaques and this variability may be related to differences in specific neurobehavioral patterns of development. This study evaluated the differential neonatal imitative response of 41 macaques in relation to the development of sensory, motor, and cognitive skills throughout the 1st month of life. The results show that infants who imitate facial gestures display more developed skills in goal‐directed movements (reaching–grasping and fine hand motor control) than nonimitators. These differences might reflect, at least in part, the differential maturation of motor chains in the parietal and motor cortices, which partly overlap with those of the mirror neuron system. Thus, neonatal imitation appears to be a predictor of future neurobehavioral development.
Biological Motion Displays Elicit Social Behavior in 12‐Month‐Olds
Authors: Yoon Jennifer M. D. , Johnson Susan C.
Published: July 2009

To test the hypothesis that biological motion perception is developmentally integrated with important social cognitive abilities, 12‐month‐olds (N = 36) were shown a display of a human point‐light figure turning to observe a target. Infants spontaneously and reliably followed the figure’s “gaze” despite the absence of familiar and socially informative features such as a face or eyes. This suggests that biological motion displays are sufficient to convey rich psychological information such as attentional orientation and is the first evidence to show that biological motion perception and social cognitive abilities are functionally integrated early in the course of typical development. The question of whether common neural substrates for biological motion perception and analysis of gaze direction underlies the functional integration seen behaviorally is discussed.
Electroencephalogram and Heart Rate Regulation to Familiar and Unfamiliar People in Children With Autism Spectrum Disorders
Authors: Van Hecke Amy Vaughan , Lebow Jocelyn , Bal Elgiz , Lamb Damon , Harden Emily , Kramer Alexis , Denver John , Bazhenova Olga , Porges Stephen W.
Published: July 2009

Few studies have examined whether familiarity of partner affects social responses in children with autism. This study investigated heart rate regulation (respiratory sinus arrhythmia [RSA]: The myelinated vagus nerve’s regulation of heart rate) and temporal–parietal electroencephalogram (EEG) activity while nineteen 8‐ to 12‐year‐old children with autism and 14 controls viewed videos of a familiar and an unfamiliar person reading a story. Children with autism had lower overall RSA levels and exhibited decreased RSA to the unfamiliar person, versus control children. Both groups decreased temporal–parietal EEG activity to the unfamiliar person. Higher RSA was related to higher social skill ratings and fewer problem behaviors. Thus, the social difficulties of children with autism may be characterized by specific mobilization to unfamiliar people.
Does Gaze Direction Modulate Facial Expression Processing in Children With Autism Spectrum Disorder?
Authors: Akechi Hironori , Senju Atsushi , Kikuchi Yukiko , Tojo Yoshikuni , Osanai Hiroo , Hasegawa Toshikazu
Published: July 2009

Two experiments investigated whether children with autism spectrum disorder (ASD) integrate relevant communicative signals, such as gaze direction, when decoding a facial expression. In Experiment 1, typically developing children (9–14 years old; n = 14) were faster at detecting a facial expression accompanying a gaze direction with a congruent motivational tendency (i.e., an avoidant facial expression with averted eye gaze) than those with an incongruent motivational tendency. Children with ASD (9–14 years old; n = 14) were not affected by the gaze direction of facial stimuli. This finding was replicated in Experiment 2, which presented only the eye region of the face to typically developing children (n = 10) and children with ASD (n = 10). These results demonstrated that children with ASD do not encode and/or integrate multiple communicative signals based on their affective or motivational tendency.
Neural Correlates of Belief‐ and Desire‐Reasoning
Authors: Liu David , Meltzoff Andrew N. , Wellman Henry M.
Published: July 2009

Theory of mind requires an understanding of both desires and beliefs. Moreover, children understand desires before beliefs. Little is known about the mechanisms underlying this developmental lag. Additionally, previous neuroimaging and neurophysiological studies have neglected the direct comparison of these developmentally critical mental‐state concepts. Event‐related brain potentials were recorded as participants (N = 24; mean age = 22 years) reasoned about diverse‐desires, diverse‐beliefs, and parallel physical situations. A mid‐frontal late slow wave (LSW) was associated with desire and belief judgments. A right‐posterior LSW was only associated with belief judgments. These findings demonstrate neural overlap and critical differences in reasoning explicitly about desires and beliefs, and they suggest children recruit additional neural processes for belief judgments beyond a common, more general, mentalizing neural system.
Brain Regions for Perceiving and Reasoning About Other People in School‐Aged Children
Authors: Saxe Rebecca R. , Whitfield‐Gabrieli Susan , Scholz Jonathan , Pelphrey Kevin A.
Published: July 2009

Neuroimaging studies with adults have identified cortical regions recruited when people think about other people’s thoughts (theory of mind): temporo‐parietal junction, posterior cingulate, and medial prefrontal cortex. These same regions were recruited in 13 children aged 6–11 years when they listened to sections of a story describing a character’s thoughts compared to sections of the same story that described the physical context. A distinct region in the posterior superior temporal sulcus was implicated in the perception of biological motion. Change in response selectivity with age was observed in just one region. The right temporo–parietal junction was recruited equally for mental and physical facts about people in younger children, but only for mental facts in older children.