bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Zr22+, Cd22+, Hf22+, W22+, and Pt22+ in the gas phase
Authors: Franzreb Klaus , Diez Reinaldo Pis , Alonso Julio A.
Published: April 2009

Five homonuclear diatomic dications Zr22+, Cd22+, Hf22+, W22+, and Pt22+ have been observed in the gas phase by mass spectrometry. These exotic doubly positively charged molecules were produced indirectly in the ion extraction region of a secondary ion mass spectrometer during sputtering of zirconium, cadmium, hafnium, tungsten, and platinum metal foils, respectively, by energetic high-current Ar+ ion surface bombardment. They were detected in positive ion mass spectra at half-integer m∕z values for ion flight times of the order of ∼10−5s. To our knowledge, these species had not been observed before. This experimental work confirms two theoretical investigations that had predicted that W22+ and Cd22+ are long-lived metastable species in the gas phase, but contradicts two theoretical studies that had suggested that Pt22+ should be unstable with respect to fragmentation. Therefore an advanced theoretical investigation of the ground state of Pt22+ was also performed. Our calculation shows that the ground state of Pt22+ is metastable with an internuclear equilibrium distance of 2.36Å, a dissociation energy (with respect to the top of the barrier) of 2.32eV, and an ionization potential of Pt2+ of about 15.8eV. The latter theoretical result strongly suggests that Pt22+ dication formation in our experiment may have taken place via the resonant electron transfer process Pt2++Ar+→Pt22++Ar.
Molecular origin of the negative heat capacity of hydrophilic hydration
Authors: Kinoshita Masahiro , Yoshidome Takashi
Published: April 2009

The hydrophobic and hydrophilic hydrations are analyzed with the emphasis on the sign of the heat capacity of hydration (HCH). The angle-dependent integral equation theory combined with a multipolar water model is employed in the analysis. The hydration entropy (HE) is decomposed into the translational and orientational parts. It is found that the orientational part governs the temperature dependence of the HE. The orientational part is further decomposed into the solute-water pair correlation component (component 1) and the water reorganization component (component 2). For hydrophilic solutes, components 1 and 2 are negative and positive, respectively. As the temperature becomes higher, component 1 increases while component 2 decreases: They make positive and negative contributions to the HCH, respectively. The strong solute-water electrostatic attractive interactions induce the distortion of water structure near the solute and the break of hydrogen bonds. As the temperature increases, the effect of the attractive interactions becomes smaller and the distortion of water structure is reduced (i.e., more hydrogen bonds are recovered with increasing temperature). The latter effect dominates, leading to negative HCH. During the heat addition the formation of hydrogen bonds, which accompanies heat generation, occurs near the solute. Consequently, the addition of the same amount of heat leads to a larger increase in the thermal energy (or equivalently, in the temperature) than in the case of pure water. The hydrophobic hydration, which is opposite to the hydrophilic hydration in many respects, is also discussed in detail.
Effect of the position of a circular cylinder in a square enclosure on natural convection at Rayleigh number of 107
Authors: Yoon Hyun Sik , Ha Man Yeong , Kim Byung Soo , Yu Dong Hun
Published: April 2009

Numerical calculations are carried out for the natural convection induced by temperature difference between a cold outer square cylinder and a hot inner circular cylinder for Rayleigh number of Ra=107. This study investigates the effect of the inner cylinder location on the heat transfer and fluid flow. The location of inner circular cylinder (δ) is changed vertically along the centerline of square enclosure. The natural convection bifurcates from unsteady to steady state according to δ. Two critical positions of δC,L and δC,U as a lower bound and an upper bound are δC,L=0.05 and δC,U=0.18, respectively. Within the defined bounds, the thermal and flow fields are steady state. In the unsteady region, the natural convection shows a single frequency and multiple frequency periodic patterns alternately according to δ. When the inner cylinder locates at δ≥δC,U, the space between the upper surface of inner cylinder and the top surface of the enclosure forms a relatively shallow layer where the natural convection characterized as the pure Rayleigh–Benard convection forms alternately the upwelling and downwelling plums. As a result a series of cells known as Benard cells is derived. The changes in heat transfer quantities have also been presented.
Development of wearable optical topography system for mapping the prefrontal cortex activation
Authors: Atsumori Hirokazu , Kiguchi Masashi , Obata Akiko , Sato Hiroki , Katura Takusige , Funane Tsukasa , Maki Atsushi
Published: April 2009

Optical topography (OT) based on near infrared spectroscopy is effective for measuring changes in the concentrations of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) in the brain. It can be used to investigate brain functions of subjects of all ages because it is noninvasive and less constraining for subjects. Conventional OT systems use optical fibers to irradiate the scalp and detect light transmitted through the tissue in the human head, but optical fibers limit the subject’s head position, so some small systems have been developed without using optical fibers. These systems, however, have a small number of measurement channels. We developed a prototype of a small, light, and wearable OT system that covers the entire forehead. We measured changes in the concentrations of oxy-Hb and deoxy-Hb in the prefrontal cortex while a subject performed a word fluency task. The results show typical changes in oxy-Hb and deoxy-Hb during the task and suggest that the prototype of our system can be used to investigate functions in the prefrontal cortex.
Effects of anisotropic material property on the spring constant and the resonant frequency of atomic force microscope cantilever
Authors: Yeh Meng-Kao , Tai Nyan-Hwa , Chen Bo-Yi
Published: April 2009

Atomic force microscope (AFM) is a powerful tool for force measurement in nanoscale. Many methods have been developed to obtain the precise cantilever’s spring constant for improving the accuracy of force measurement. AFM cantilevers are usually made by single crystal silicon of which the anisotropic material property seriously affects the spring constant of cantilevers and has not considered before. In this paper, the density function theory was used to calculate the anisotropic stiffness matrix of crystal silicon, which was used in the finite element analysis to calculate lateral, axial, bending spring constants, and resonant frequencies of rectangular AFM cantilevers. These results were compared with those derived from other theoretical methods and with those provided by the manufacturers. The results showed that the anisotropic material property significantly affected the spring constants and the resonant frequencies of the AFM cantilever. The assumption of equivalent isotropic property of the rectangular AFM cantilever would cause an error up to 29.72%. Furthermore, two equations were proposed to obtain the spring constants and the resonant frequencies of crystal silicon AFM cantilever with the axis located at different cantilever-crystal angles.
The temperature dependence of free volume in phenyl salicylate and its relation to structural dynamics: A positron annihilation lifetime and pressure-volume-temperature study
Authors: Dlubek G. , Shaikh M. Q. , Raetzke K. , Faupel F. , Pionteck J. , Paluch M.
Published: April 2009

Positron annihilation lifetime spectroscopy (PALS) and pressure-volume-temperature (PVT) experiments were performed to characterize the temperature dependent microstructure of the hole free volume in the low molecular weight glass-former phenyl salicylate (salol). The PALS spectra were analyzed with the new routine LT9.0 and the volume distribution of subnanometer size holes characterized by its mean ⟨vh⟩ and standard deviation σh was calculated. Crystallization of the amorphous sample was observed in the temperature range above 250 K, which leads to a vanishing of the positronium formation. The positronium signal recovered after melting at 303 K. A combination of PALS with PVT data enabled us to calculate the specific density Nh′, the specific volume Vf, and the fraction of holes fh in the amorphous state. From comparison with dielectric measurements in the temperature range above TB=265 K, it was found that the primary structural relaxation slows down with temperature, faster than the shrinkage of the hole free volume Vf would predict, on the basis of the Cohen–Turnbull (CT) free volume theory. CT plots can be linearized by replacing Vf of the CT theory by (Vf-ΔV), where ΔV is a volume correction term. This was interpreted as indication that the lower wing of the hole size distribution contains holes too small to show a liquidlike behavior in their surroundings. Peculiarities of the relaxation behavior below TB=265 K and the possible validity of the Cohen–Grest free volume model are discussed.
Calculating electron paramagnetic resonance g-matrices for triplet state molecules from multireference spin-orbit configuration interaction wave functions
Authors: Tatchen Jörg , Kleinschmidt Martin , Marian Christel M.
Published: April 2009

We present a way to calculate electron paramagnetic resonance (EPR) g-matrices from variationally optimized spin-orbit coupled wave functions. Our method constructs a triangular g-matrix from the matrix representation of the total electron magnetic moment in the basis of the spin-orbit coupled wave functions by means of a projection technique. Principal g-values are obtained in the standard fashion by forming from the triangular matrix g͇ the tensor G͇=g͇g͇t and diagonalizing it. In principle, the scheme allows to calculate the spin-orbit orbital Zeeman cross term which usually gives the dominating contribution to the EPR g-shifts for any multiplicity. We have implemented this approach into a multireference spin-orbit configuration interaction (MRSOCI) program [M. Kleinschmidt et al., J. Chem. Phys. 124, 124101 (2006)]. Test applications are carried out for various triplet state sytems. The g-shifts of several of main group diatomics with X Σ3(g)− ground state are investigated at the level of ab initio MRSOCI. We obtain perpendicular g-shifts which underestimate experimental Δg⊥ values from literature by ∼13% on the average. For a set of organic triplet state molecules we employ the combined density functional theory/multireference configuration interaction (DFT/MRCI) technique [S. Grimme and M. Waletzke, J. Chem. Phys. 111, 5645 (1999)] to reduce the computational costs of the spin-free correlation problem. This approach yields principal g-values that match experiment well in many cases. Due to the small absolute g-shifts, a rigorous comparison will require the inclusion of first-order contributions such as the relativistic mass correction and gauge correction terms which have not been included here. For the triplet state dication trans-(CNSSS)22+ the principal g-shifts Δga=−0.3 ppt, Δgb=17.5 ppt, and Δgc=26.6 ppt are significantly larger and compare rather well to the experimental values Δg1=−0.1±0.2 ppt, Δg2=14.8±0.2 ppt, and Δg3=24.8±0.1 ppt [A. Berces et al., Magn. Reson. Chem. 37, 353 (1999)]. In comparison to conventional truncated sum-over state techniques based on Rayleigh–Schrödinger perturbation theory, our new variational approach shows, in practice, robust and advantageous convergence characteristics with respect to the size of the many-particle basis set. We demonstrate that the DFT/MRSOCI technology is a very feasible means to compute reliable g-shifts for large organic triplet systems at low computational cost.
Giant enhancement of top emission from ZnO thin film by nanopatterned Pt
Authors: Liu K. W. , Tang Y. D. , Cong C. X. , Sum T. C. , Huan A. C. H. , Shen Z. X. , Wang Li , Jiang F. Y. , Sun X. W. , Sun H. D.
Published: April 2009

The authors report the enhancement of the bandgap emission from ZnO thin films by surface modification and surface plasmon cross-coupling. 12-fold and twofold enhancements of bandgap emission from the metal side of ZnO film were observed by sputtering Pt nanopattern and Pt film onto ZnO film, respectively. Time-resolved photoluminescence indicates that the decay time is slowed down by Pt capping, contrary to common observations. The “abnormal” phenomena are interpreted by considering both the surface modification and surface plasmon coupling.
On the structure of hot absorption spectra of polyatomic molecules: Solvent effect on the transition energy gap
Authors: Tranca D. C. , Neufeld A. A.
Published: April 2009

Hot absorption spectra of polyatomic molecules may exhibit a characteristic shoulder. Its origin and connection to the 0-0 transition energy gap has been established on the basis of a recently developed quantum-classical approach. We demonstrate that an accurate estimate of the transition energy can be obtained directly from experimental data. The method can be used to study the solvent influence on the energetics of electronic transitions.
Use of ruthenium dyes for subnanosecond detector fidelity testing in real time transient absorption
Authors: Byrdin Martin , Thiagarajan Viruthachalam , Villette Sandrine , Espagne Agathe , Brettel Klaus
Published: April 2009

Transient absorption spectroscopy is a powerful tool for the study of photoreactions on time scales from femtoseconds to seconds. Typically, reactions slower than ∼1 ns are recorded by the “classical” technique; the reaction is triggered by an excitation flash, and absorption changes accompanying the reaction are recorded in real time using a continuous monitoring light beam and a detection system with sufficiently fast response. The pico- and femtosecond region can be accessed by the more recent “pump-probe” technique, which circumvents the difficulties of real time detection on a subnanosecond time scale. This is paid for by accumulation of an excessively large number of shots to sample the reaction kinetics. Hence, it is of interest to extend the classical real time technique as far as possible to the subnanosecond range. In order to identify and minimize detection artifacts common on a subnanosecond scale, like overshoot, ringing, and signal reflections, rigorous testing is required of how the detection system responds to fast changes of the monitoring light intensity. Here, we introduce a novel method to create standard signals for detector fidelity testing on a time scale from a few picoseconds to tens of nanoseconds. The signals result from polarized measurements of absorption changes upon excitation of ruthenium complexes {[Ru(bpy)3]2+ and a less symmetric derivative} by a short laser flash. Two types of signals can be created depending on the polarization of the monitoring light with respect to that of the excitation flash: a fast steplike bleaching at magic angle and a monoexponentially decaying bleaching for parallel polarizations. The lifetime of the decay can be easily varied via temperature and viscosity of the solvent. The method is applied to test the performance of a newly developed real time transient absorption setup with 300 ps time resolution and high sensitivity.
Single gold nanostars enhance Raman scattering
Authors: Hrelescu Calin , Sau Tapan K. , Rogach Andrey L. , Jäckel Frank , Feldmann Jochen
Published: April 2009

Raman scattering from single gold nanostars coated with self-assembled monolayers of 4-mercaptobenzoic acid is observed. The Raman signal can be detected without the need of forming particle aggregates or resonant electronic excitation of the analyte. A total Raman enhancement factor of 107 for individual nanostars is estimated. These features make gold nanostars promising for Raman imaging in cells or cellular membranes.
Magnetoresistance in high-density two-dimensional electron gas confined in InAlAs/InGaAs quantum well
Authors: Gao K. H. , Zhou W. Z. , Zhou Y. M. , Yu G. , Lin T. , Guo S. L. , Chu J. H. , Dai N. , Gu Y. , Zhang Y. G. , Austing D. G.
Published: April 2009

We study the magnetoresistance of a high-density two-dimensional electron gas confined in an InAlAs/InGaAs quantum well and observe a parabolic negative magnetoresistivity at moderate field. This negative magnetoresistivity is induced by electron-electron interactions. The interaction correction to the Drude conductance is extracted from the negative magnetoresistivity. However, due to inhomogeneity in the electron density, there is a contribution of positive magnetoresistivity, which induces the larger extracted correction than anticipated.
Domain structures in continuously graded ferroelectric films
Authors: Roytburd A. L. , Roytburd V. , Slutsker J.
Published: April 2009

Thermodynamic analysis of a graded ferroelectric epitaxial film demonstrates that in the equilibrium state the films subdivide into an alternation of polydomain bands consisting of wedge- or lens-shape domains and single-domain bands. Polarization under an external electrical field proceeds through an interband boundary movement due to the growth/shrinkage of the wedge domains. The domain structure and its evolution are determined by the distribution of the spontaneous polarization and dielectric constant. Through film grading, it is possible to design a controlled domain structure with desirable tunability. Graded films exhibit a sharp increase of the dielectric constant as electrical field approaches zero.
Dissipation-factor-based criterion for the validity of carrier-type identification by capacitance-voltage measurements
Authors: Bierwagen O. , Nagata T. , Ive T. , Van de Walle C. G. , Speck J. S.
Published: April 2009

High series resistance and parasitic parallel conductance—typical problems in electronic materials at early stages of development—can lead to serious artifacts in capacitance-voltage measurements. Depending on the assumed equivalent circuit model, these artifacts can even lead to an incorrect carrier type identification. Based on an analytical model we show that a dissipation factor of less than unity indicates that the correct carrier type is obtained in the series circuit model. In the context of Schottky diodes, we also show how the characteristics of the measured conductance-voltage curves from the parallel circuit model can be used to infer the carrier type. We demonstrate these effects with the example of an n-type ZnO sample for which the measured capacitance-voltage dependence seemingly shows the presence of p-type conductivity.
Film bulk acoustic-wave resonator based ultraviolet sensor
Authors: Qiu X. , Zhu J. , Oiler J. , Yu C. , Wang Z. , Yu H.
Published: April 2009

This letter described ultraviolet (UV) radiation sensing with ZnO based film bulk acoustic-wave resonator (FBAR). The resonant frequency upshifted when there was UV illumination on the FBAR. For 365 nm UV light, the frequency upshift was 9.8 kHz with an intensity of 600 μW/cm2, and the detection limit of the sensor was 6.5 nW. The frequency increase in the FBAR UV sensor was proposed to be due to the density decrease in ZnO film upon UV illumination. When UV was incident on the ZnO film, it can cause oxygen desorption from the ZnO surface, resulting in density decrease in the film. This study has proven the feasibility of detection of low intensity UV using ZnO film based FBAR.
High-energy physics
Authors: Malamud Ernest , Nezrick Frank
Published: April 2009

As the US and the USSR have moved toward a closer relationship over the past twenty years, one very successful area of mutual cooperation has been the field of high-energy physics. Both the US and USSR have at least five accelerators operating at center-of-mass energies greater than 3.0 GeV. During the past two decades the US and USSR have alternately had the higher energy accelerator. The number of active high-energy physicists, including theorists, machine builders and experimentalists is roughly comparable for both countries. This similarity between the facilities available and the number of specialists in the field for both sides formed a promising foundation on which a joint program could be built.
Effects of age and equine follicle-stimulating hormone (eFSH) on collection and viability of equine oocytes assessed by morphology and developmental competency after intracytoplasmic sperm injection (ICSI)
Authors: Altermatt J. L. , Suh T. K. , Stokes J. E. , Carnevale E. M.
Published: April 2009

Young (4 to 9 yr) and old (≥20 yr) mares were treated with equine follicle-stimulating hormone (eFSH), and oocytes were collected for intracytoplasmic sperm injections (ICSI). Objectives were to compare: (1) number, morphology and developmental potential of oocytes collected from young v. old mares from cycles with or without exogenous eFSH and (2) oocyte morphology parameters with developmental competence. Oocytes were collected from preovulatory follicles 20 to 24 h after administration of recombinant equine LH and imaged before ICSI for morphological measurements. After ICSI, embryo development was assessed, and late morulae or blastocysts were transferred into recipients’ uteri. Cycles with eFSH treatment resulted in more follicles (1.8 v. 1.2) and more recovered oocytes (1.1 v. 0.8) than those without eFSH. Age and eFSH treatment did not effect cleavage, blastocyst and pregnancy rates. Treatment with eFSH had no effect on oocyte morphology, but age-associated changes were observed. In old mares, zona pellucidae (ZP) were thinner than in young mares, and perivitelline space and inner ZP volume (central cavity within the ZP) were larger and associated with oocytes that failed to develop. These results suggest that administration of eFSH can increase the number of oocytes collected per cycle. Oocyte morphology differed with age and was associated with developmental competence.
The “Bosnian war on terrorism”
Authors: Erjavec Karmen
Published: April 2009

This paper explores the changes in the media discourse on granting and revoking Bosnian citizenship of foreigners in the most read Bosnian, Croatian, and Serbian quality daily newspapers from the end of the Bosnian war in 1995 until the Commission for the Revision of Decisions on Naturalization of Foreign Citizens finished its work in 2007. Critical discourse analysis of news articles shows that all newspapers recontextualised the discourse on granting and revoking citizenship from a nationalistic war discourse to a “war on terrorism” discourse, joining the anti-terrorism global discursive community. Serbian and Croatian newspapers have not only colonised the “war on terrorism” vocabulary and discourse of difference but they have also appropriated a specific local discourse to the more global “war on terrorism” discourse and have represented military actions against the Muslims in the Bosnian war “as our war on terrorism”. A Bosnian daily newspaper similarly represented the Commission’s activities as the “Bosnian war on terrorism”.
A cross cultural apology episode of a diplomatic repair
Authors: Mok Jeffrey , Tokunaga Mitsuhiro
Published: April 2009

Against the political backdrop of what was arguably the lowest point in the China-Japan relationship in modern times, China had called for Japan to take “concrete actions to face up with … its history of invasion”. In response, Japan’s then Prime Minister, Junichiro Koizumi, issued a public apology at the Asian-African Summit on 22nd April 2005. His choice of words, “deep remorse” and “heartfelt apology”, did little to assuage the Chinese. What did these words really mean in the context of speech acts of apology? Was the apology considered to be an apology? How does this episode of apology fall into the current discussion of apology strategies? Was there lexical avoidance? Was there any discourse difference compared to previous apologies? This paper will attempt to answer these questions.
Post-colonial identity in Greenland?
Authors: Gad Ulrik Pram
Published: April 2009

In the gradual unravelling of Greenland’s colonial relationship to Denmark, an essentialist conceptualization of Greenlandic identity has played a significant role. However, both our scholarly understanding of post-colonial Greenlandic identity and the process towards independence for Greenland could be furthered by bringing politics back in. Based on a discourse analysis of the Greenlandic debate on language, this paper makes three claims: First, the identity projects promoted in Greenland are based on an essentialist conception of identity. Secondly, Greenlandic identity discourse combines elements of traditional Inuit culture and elements of colonial modernity. Thirdly, monolingual Greenlanders are those with the most to gain from abandoning the dichotomy of essentialist identities. Strategically, the paper suggests a post-post-colonial Greenlandic identity as a means of avoiding the exclusion of valuable human resources. One step towards relieving the relation to the Danish Other of identificatory weight could be a gradual shift to English as second language.
Templated growth of textured and luminescent CaS : Eu thin films by a low-temperature solvothermal process
Authors: Smet P F , Poelman D
Published: April 2009

The direct growth of luminescent sulfide thin films onto templated substrates was realized with a solvothermal synthesis method. The as-grown layers of SrS : Eu and CaS : Eu emit a bright and homogeneous photoluminescence, peaking at 610 nm and 650 nm, respectively. X-ray diffraction measurements showed that the layers grown at a temperature of only 200 °C are strongly crystalline, with (2 0 0) out-of-plane orientation. Using silicon substrates, almost epitaxial growth could be obtained. Electron microscopy was used to study the growth, morphology and texture of the thin films. The main advantages of this innovative approach for the production of sulfide layers are the low-temperature process and scalability.
Explaining and inducing savant skills: privileged access to lower level, less-processed information
Authors: Snyder Allan
Published: April 2009

I argue that savant skills are latent in us all. My hypothesis is that savants have privileged access to lower level, less-processed information, before it is packaged into holistic concepts and meaningful labels. Owing to a failure in top-down inhibition, they can tap into information that exists in all of our brains, but is normally beyond conscious awareness. This suggests why savant skills might arise spontaneously in otherwise normal people, and why such skills might be artificially induced by low-frequency repetitive transcranial magnetic stimulation. It also suggests why autistic savants are atypically literal with a tendency to concentrate more on the parts than on the whole and why this offers advantages for particular classes of problem solving, such as those that necessitate breaking cognitive mindsets. A strategy of building from the parts to the whole could form the basis for the so-called autistic genius. Unlike the healthy mind, which has inbuilt expectations of the world (internal order), the autistic mind must simplify the world by adopting strict routines (external order).
Stereotypes of autism
Authors: Draaisma Douwe
Published: April 2009

In their landmark papers, both Kanner and Asperger employed a series of case histories to shape clinical insight into autistic disorders. This way of introducing, assessing and representing disorders has disappeared from today's psychiatric practice, yet it offers a convincing model of the way stereotypes may build up as a result of representations of autism. Considering that much of what society at large learns on disorders on the autism spectrum is produced by representations of autism in novels, TV-series, movies or autobiographies, it will be of vital importance to scrutinize these representations and to check whether or not they are, in fact, misrepresenting autism. In quite a few cases, media representations of talent and special abilities can be said to have contributed to a harmful divergence between the general image of autism and the clinical reality of the autistic condition.
Savant skills in autism: psychometric approaches and parental reports
Authors: Howlin Patricia , Goode Susan , Hutton Jane , Rutter Michael
Published: April 2009

Most investigations of savant skills in autism are based on individual case reports. The present study investigated rates and types of savant skills in 137 individuals with autism (mean age 24 years). Intellectual ability ranged from severe intellectual impairment to superior functioning. Savant skills were judged from parental reports and specified as ‘an outstanding skill/knowledge clearly above participant's general level of ability
and
above the population norm’. A comparable definition of exceptional cognitive skills was applied to Wechsler test scores—requiring a subtest score at least 1 standard deviation above general population norms and 2 standard deviations above the participant's own mean subtest score. Thirty-nine participants (28.5%) met criteria for either a savant skill or an exceptional cognitive skill: 15 for an outstanding cognitive skill (most commonly block design); 16 for a savant skill based on parental report (mostly mathematical/calculating abilities); 8 met criteria for both a cognitive and parental rated savant skill. One-third of males showed some form of outstanding ability compared with 19 per cent of females. No individual with a non-verbal IQ below 50 met criteria for a savant skill and, contrary to some earlier hypotheses, there was no indication that individuals with higher rates of stereotyped behaviours/interests were more likely to demonstrate savant skills.
Radial cytoarchitecture and patterns of cortical connectivity in autism
Authors: Casanova Manuel , Trippe Juan
Published: April 2009

To explain the pattern of preserved and superior abilities found in autism spectrum disorders, a hypothesis has emerged, which assumes that there is a developmental bias towards the formation of short-range connections. This would result in excessive activity and overconnectivity within susceptible local networks. These networks might become partially isolated and acquire novel functional properties. In turn, this would affect the formation of long-range circuits and systems governing top-down control and integration. Despite many tantalizing clues, mechanisms relating pathogenesis and altered cell function to the ‘disconnection’ of integrative and focal activity remain obscure. However, recent
post-mortem
studies of brains of individuals with autism have shown characteristic differences in the morphometry of radial cell minicolumns, which add credence to the connectivity hypothesis.
What aspects of autism predispose to talent?
Authors: Happé Francesca , Vital Pedro
Published: April 2009

In this paper, we explore the question, why are striking special skills so much more common in autism spectrum conditions (ASC) than in other groups? Current cognitive accounts of ASC are briefly reviewed in relation to special skills. Difficulties in ‘theory of mind’ may contribute to originality in ASC, since individuals who do not automatically ‘read other minds’ may be better able to think outside prevailing fashions and popular theories. However, originality alone does not confer talent. Executive dysfunction has been suggested as the ‘releasing’ mechanism for special skills in ASC, but other groups with executive difficulties do not show raised incidence of talents. Detail-focused processing bias (‘weak coherence’, ‘enhanced perceptual functioning’) appears to be the most promising predisposing characteristic, or ‘starting engine’, for talent development. In support of this notion, we summarize data from a population-based twin study in which parents reported on their 8-year-olds' talents and their ASC-like traits. Across the whole sample, ASC-like traits, and specifically ‘restricted and repetitive behaviours and interests’ related to detail focus, were more pronounced in children reported to have talents outstripping older children. We suggest that detail-focused cognitive style predisposes to talent in savant domains in, and beyond, autism spectrum disorders.
Perception and apperception in autism: rejecting the inverse assumption
Authors: Plaisted Grant Kate , Davis Greg
Published: April 2009

In addition to those with savant skills, many individuals with autism spectrum conditions (ASCs) show superior perceptual and attentional skills relative to the general population. These superior skills and savant abilities raise important theoretical questions, including whether they develop as compensations for other underdeveloped cognitive mechanisms, and whether one skill is inversely related to another weakness via a common underlying neurocognitive mechanism. We discuss studies of perception and visual processing that show that this inverse hypothesis rarely holds true. Instead, they suggest that enhanced performance is not always accompanied by a complementary deficit and that there are undeniable difficulties in some aspects of perception that are not related to compensating strengths. Our discussion emphasizes the qualitative differences in perceptual processing revealed in these studies between individuals with and without ASCs. We argue that this research is important not only in furthering our understanding of the nature of the qualitative differences in perceptual processing in ASCs, but can also be used to highlight to society at large the exceptional skills and talent that individuals with ASCs are able to contribute in domains such as engineering, computing and mathematics that are highly valued in industry.
Prospero-related homeobox protein (Prox1) inhibits hepatitis B virus replication through repressing multiple cis regulatory elements
Authors: Qin Jun , Zhai Jianwei , Hong Ran , Shan Shifang , Kong Yuying , Wen Yumei , Wang Yuan , Liu Jing , Xie Youhua
Published: April 2009

Hepatitis B virus (HBV) gene transcription is controlled by viral promoters and enhancers, the activities of which are regulated by a number of cellular factors as well as virally encoded proteins. Negative regulation of HBV cis-element activities by cellular factors has been reported less widely than their activation. In this study, we report that nuclear factor Prospero-related homeobox protein (Prox1) represses HBV antigen expression and genome replication in cultured hepatocytes. By using reporter-gene analysis, three of the four HBV promoters, namely the enhancer II/core promoter (ENII/Cp), preS1 promoter (Sp1) and enhancer I/X promoter, were identified as targets for Prox1-mediated repression. Mechanistic analysis then revealed that, for ENII/Cp, Prox1 serves as a corepressor of liver receptor homologue 1 (LRH-1) and downregulates LRH-1-mediated activation of ENII/Cp, whereas for Sp1, Prox1 partially represses Sp1 activity by interacting directly with hepatocyte nuclear factor 1. Identification of Prox1 as an HBV repressor will help in the understanding of detailed interactions between viral cis elements and host cellular factors and may also form the basis for new anti-HBV intervention therapeutics.
Binding of CCCTC-binding factor in vivo to the region located between Rep* and the C promoter of Epstein–Barr virus is unaffected by CpG methylation and does not correlate with Cp activity
Authors: Salamon Daniel , Banati Ferenc , Koroknai Anita , Ravasz Mate , Szenthe Kalman , Bathori Zoltan , Bakos Agnes , Niller Hans Helmut , Wolf Hans , Minarovits Janos
Published: April 2009

In this study, the binding of the insulator protein CCCTC-binding factor (CTCF) to the region located between Rep* and the C promoter (Cp) of Epstein–Barr virus (EBV) was analysed using chromatin immunoprecipitation and in vivo footprinting. CTCF binding was found to be independent of Cp usage in cell lines corresponding to the major EBV latency types. Bisulfite sequencing and an electrophoretic mobility-shift assay (using methylated and unmethylated probes) revealed that CTCF binding was insufficient to induce local CpG demethylation in certain cell lines and was unaffected by CpG methylation in the region between Rep* and Cp. In addition, CTCF binding to the latency promoter, Qp, did not correlate with Qp activity.
Differential regulation of antiviral and proinflammatory cytokines and suppression of Fas-mediated apoptosis by NS1 of H9N2 avian influenza virus in chicken macrophages
Authors: Xing Zheng , Cardona Carol J. , Adams Sean , Yang Zengqi , Li Jinling , Perez Daniel , Woolcock Peter R.
Published: April 2009

The NS1 protein is known to suppress immune responses in influenza virus-infected hosts. However, the role of NS1 in apoptosis in infected cells is disputed. In this study, through the use of a mutant A/pheasant/California/2373/1998 (H9N2) avian influenza virus (AIV) with a truncated NS1, we have demonstrated that a functional NS1 protein suppresses the induction of interferons in chicken macrophages. However, NS1 appeared to be irrelevant to the regulation of cytokines interleukin (IL)-1βand IL-6, indicating that distinct mechanisms may be employed in the regulation of antiviral and proinflammatory cytokines in chicken immune cells. Our study also showed that this H9N2 AIV induced apoptosis extrinsically through the Fas/Fas ligand (FasL)-mediated pathway. We found that NS1 suppressed the apoptotic process through suppression of the induction of FasL, but not tumour necrosis factor-αor TNF-related apoptosis-inducing ligand. Furthermore, our data indicated that the disruption of a potential binding site for the p85βsubunit of phosphoinositide 3-kinase in the carboxyl terminus of NS1, while having no effect on the regulation of IFN induction, may contribute to the suppression of Fas/FasL-mediated apoptosis. Therefore, suppression of Fas/FasL-mediated apoptosis by NS1 is one of the critical mechanisms necessary to increase infectivity in AIV-infected chicken macrophages.
Tyrosine 78 of premembrane protein is essential for assembly of West Nile virus
Authors: Tan Terence T. T. , Bhuvanakantham Raghavan , Li Jun , Howe Josephine , Ng Mah-Lee
Published: April 2009

Flavivirus premembrane (prM) protein plays an important role in conformational folding of the envelope (E) protein and protects it against premature fusion in acidic vesicles of the Golgi network. Currently, molecular determinants on the prM protein ectodomain which mediate critical steps during the flavivirus assembly process are poorly characterized. In this study, bioinformatics analysis and alanine scanning mutagenesis showed that the amino acid triplet valine 76, tyrosine 78 and glycine 79 is absolutely conserved among flavivirus prM ectodomains. Triple mutations engineered at these residues in prM ectodomain of West Nile virus (WNV) completely abrogated virus infectivity. Site-directed mutagenesis of prM protein revealed that tyrosine 78 of the amino acid triplet was required for virus infectivity and secretion. The mutation did not affect folding, post-translational modifications and trafficking of the prM and E proteins. Ultrastructural studies using transmission electron microscopy confirmed that virus particle formation was blocked by tyrosine 78 mutation. Specificity of assembly defect conferred by tyrosine 78 mutation was demonstrated by positive and negative trans complementation studies. Collectively, these results defined tyrosine 78 as a novel critical determinant present on prM protein ectodomain that is required for flavivirus assembly. Molecular dissection of prM protein function provides the crucial knowledge much needed in the elucidation of flavivirus particle formation.
A role for autophagolysosomes in dengue virus 3 production in HepG2 cells
Authors: Khakpoor Atefeh , Panyasrivanit Mingkwan , Wikan Nitwara , Smith Duncan R.
Published: April 2009

We have recently proposed that amphisomes act as a site for translation and replication of dengue virus (DENV)-2 and that DENV-2 entry and replication are linked through an ongoing association with membranes of an endosomal–autophagosomal lineage. In this report, we present the results of an investigation into the interaction between DENV-3 and the autophagy machinery. Critically, treatment with the lysosomal fusion inhibitor l-asparagine differentiated the interaction of DENV-3 from that of DENV-2. Inhibition of fusion of autophagosomes and amphisomes with lysosomes resulted in decreased DENV-3 production, implying a role for the autophagolysosome in the DENV-3 life cycle. Evidence based upon the co-localization of LC3 and cathepsin D with double stranded RNA and NS1 protein, as assessed by confocal microscopy, support a model in which DENV-3 interacts with both amphisomes and autophagolysosomes. These results demonstrate that the interactions between DENV and the host cell autophagy machinery are complex and may be determined in part by virus-encoded factors.
Rev regulates translation of human immunodeficiency virus type 1 RNAs
Authors: Groom Harriet C. T. , Anderson Emma C. , Dangerfield John A. , Lever Andrew M. L.
Published: April 2009

Full-length human immunodeficiency virus type 1 (HIV-1) RNA acts as both mRNA, encoding Gag and Gag–Pol polyproteins, and genomic RNA. Translation of this RNA must be tightly controlled to allow sufficient protein synthesis prior to a switch to particle production. The viral protein Rev stimulates nuclear export of unspliced HIV-1 RNAs containing the Rev response element, but may also stimulate translation of these RNAs. We previously identified an additional Rev binding site in the 5′ untranslated region of the HIV-1 RNA. We show that Rev inhibits translation non-specifically at high concentrations and stimulates translation of HIV-1 RNAs at intermediate concentrations in vitro. Stimulation is dependent on the presence of the Rev binding site within the 5′ untranslated region and not on the Rev response element. In COS-1 cells, translation from an HIV-1 reporter is specifically increased by coexpression of Rev.
Identification and functional characterization of a spliced rhesus rhadinovirus gene with homology to the K15 gene of Kaposi's sarcoma-associated herpesvirus
Authors: Wang Linding , Pietrek Marcel , Brinkmann Melanie M. , Hävemeier Anika , Fischer Irina , Hillenbrand Bernd , Dittrich-Breiholz Oliver , Kracht Michael , Chanas Simon , Blackbourn David J. , Schulz Thomas F.
Published: April 2009

Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus related to the human Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8). This study identified an alternatively spliced gene at the right side of the RRV genome (strain 17577) between open reading frame 75 and the terminal repeat region. Of its eight exons, the first seven encoded up to 12 transmembrane domains, whilst the eighth exon encoded a predicted C-terminal cytoplasmic domain. Structurally and positionally, this RRV gene therefore resembles the K15 gene of KSHV; it was provisionally named RK15 to avoid confusion with other RRV17577 genes. In ectopic expression studies, the 55 kDa RK15 protein isoform activated the JNK and NF-κB pathways, like the 45 kDa KSHV K15-encoded protein isoform. In contrast to K15, which activates angiogenic and inflammatory cytokines such as interleukin (IL)-8, IL-6 and CCL20, the range of cellular transcripts activated by the RRV K15 homologue was much more restricted, but included IL-6, IL-8 and FGF21. These data suggest functional differences between terminal membrane proteins at the right end of the genomes of Old World primate gamma-2 herpesviruses.
Ovine PRNP untranslated region and promoter haplotype diversity
Authors: Saunders Ginny C. , Cawthraw Saira , Mountjoy Susan J. , Tout Anna C. , Sayers Anthony R. , Hope Jim , Windl Otto
Published: April 2009

The diversity and possible contribution of non-coding regions of the prion protein (PrP) gene (PRNP) to transmissible spongiform encephalopathy susceptibility and PrP regulation are not fully known. This study defined ten ovine PRNP promoters and five untranslated region (UTR) haplotypes found in atypical and classical scrapie cases and healthy control sheep. A greater diversity of promoter and UTR haplotypes was observed in conjunction with the ARQ PrP allele (seven promoter and four UTR haplotypes), while it was observed that the other alleles were linked with a limited number of haplotypes, such as ARR, found to be linked to only two promoter and one UTR haplotypes. In silico analysis identified potential transcription factor binding sites that differed in the promoter haplotype variants. Furthermore, a 5′ UTR internal ribosome entry site motif was identified in exon 2 and highlights a possible role for this exon in regulating PrP expression at the translational level.
Profile of physical status and gene variation of human papillomavirus 58 genome in cervical cancer
Authors: Wu En-qi , Zha Xiao , Yu Xiang-hui , Zhang Guo-nan , Wu Yong-ge , Fan Ying , Ren Yuan , Kong Ling-Qian , Kong Wei
Published: April 2009

Epidemiological studies have shown that human papillomavirus 58 (HPV 58) is found at a relatively high frequency in east Asia and some regions of Central and South America. To investigate the physical status of HPV 58 and analyse sequence variations of HPV 58 in cervical cancer patients, the HPV 58 genome in 37 HPV 58-positive cervical cancer specimens collected from China were investigated by a mapping analysis based on nested PCR and nucleotide sequencing. A pure integrated genome was found in 78.4 % (29/37) of specimens, which is much higher than that found in previous studies. Multiple disruptions were first found among the integrated HPV 58 genomes in 51.7 % (15/29) of specimens. Among the 7824 bp of the HPV 58 genome, 119 (1.52 %) nucleotide positions were found to be variable, and 45 of them lead to amino acid changes. Phylogenetic analyses, based on partial L1 sequences of 14 variants isolated in previous studies and this study, show that two main groups were observed in HPV 58 variants, the prototype or prototype-like group and the non-prototype-like group.
Hepatitis C virus cell entry: role of lipoproteins and cellular receptors
Authors: Burlone Michela E. , Budkowska Agata
Published: April 2009

Hepatitis C virus (HCV), a major cause of chronic liver disease, is a single-stranded positive sense virus of the familyFlaviviridae. HCV cell entry is a multi-step process, involving several viral and cellular factors that trigger virus uptake into the hepatocyte. Tetraspanin CD81, human scavenger receptor SR-BI, and tight junction molecules Claudin-1 and occludin are the main receptors that mediate HCV entry. In addition, the virus may use glycosaminoglycans and/or low density receptors on host cells as initial attachment factors. A unique feature of HCV is the dependence of virus replication and assembly on host cell lipid metabolism. Most notably, during HCV assembly and release from the infected cells, virus particles associate with lipids and very-low-density lipoproteins. Thus, infectious virus circulates in patient sera in the form of triglyceride-rich particles. Consequently, lipoproteins and lipoprotein receptors play an essential role in virus uptake and the initiation of infection. This review summarizes the current knowledge about HCV receptors, mechanisms of HCV cell entry and the role of lipoproteins in this process.