bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of novel hybrid flexure-based microgrippers for precision micro-object manipulation
Authors: Mohd Zubir Mohd Nashrul , Shirinzadeh Bijan , Tian Yanling
Published: June 2009

This paper describes the process of developing a microgripper that is capable of high precision and fidelity manipulation of micro-objects. The design adopts the concept of flexure-based hinges on its joints to provide the rotational motion, thus eliminating the inherent nonlinearities associated with the application of conventional rigid hinges. A combination of two modeling techniques, namely, pseudorigid body model and finite element analysis was utilized to expedite the prototyping procedure, which leads to the establishment of a high performance mechanism. A new hybrid compliant structure integrating cantilever beam and flexural hinge configurations within microgripper mechanism mainframe has been developed. This concept provides a novel approach to harness the advantages within each individual configuration while mutually compensating the limitations inherent between them. A wire electrodischarge machining technique was utilized to fabricate the gripper out of high grade aluminum alloy (Al 7075T6). Experimental studies were conducted on the model to obtain various correlations governing the gripper performance as well as for model verification. The experimental results demonstrate high level of compliance in comparison to the computational results. A high amplification characteristic and maximum achievable stroke of 100 μm can be achieved.
Raman spectra and room-temperature ferromagnetism of hydrogenated Zn0.95Mn0.05O nanopowders
Authors: Wang Zhenhua , Geng Dianyu , Hu Weijin , Zhang Zhidong
Published: June 2009

Two additional vibration modes at 250 and 529 cm−1 were observed in hydrogenated Zn0.98Mn0.05O nanopowders. The number of oxygen vacancies was increased by hydrogenation, which induced the mode at 250 cm−1. The additional vibration mode at 529 cm−1 was due to the increase of the number of subsititutional Mn atoms occupying Zn sites, which resulted that some new lattice defects were introduced or intrinsic host-lattice defects became activated/intensified. The room-temperature ferromagnetism was observed in the hydrogenated Zn0.98Mn0.05O nanopowders prepared at high temperature (T=700 °C), which originated from the lattice defects such as oxygen vacancies and Zn interstitials.
Baroclinic vortex influence on wave drag reduction induced by pulse energy deposition
Authors: Ogino Yousuke , Ohnishi Naofumi , Taguchi Shinichi , Sawada Keisuke
Published: June 2009

We present the results of numerical analysis of wave drag reduction by a single-pulse energy deposition in a supersonic flow field around a sphere. The wave drag for the sphere was reduced as a result of the interaction between a low-density core following the blast wave produced by the energy deposition and the bow shock developed in front of the sphere. We investigated the drag reduction mechanism in terms of the unsteady flow field induced by the interaction. The effects of deposited energy and deposition location on energy reduction were examined by parametric study. From the obtained results, we refined the parameters, utilizing the baroclinic source term that produced vorticity in the vortex equation when the gradients of density and pressure were not parallel. The baroclinic vortex driven by Richtmyer–Meshkov-like instability was strong enough to contribute to the temporary low-entropy shock formation that caused low wave drag for the supersonic object. We determined that the reduced energy had a linear dependence on the radius of the low-density core formed in the blast wave and was proportional to the square of the freestream Mach number. Such dependencies could be predicted with the assumption that the energy was consumed by the baroclinic vortex generation and advected downward without thermalization in an inviscid shock layer.
Initial oxidation of pure and K doped NiTi shape memory alloys
Authors: Tollefsen H. , Raaen S.
Published: June 2009

Initial oxidation of pure and K doped nitinol has been studied by photoelectron spectroscopy. The composition of the TiOx layer that forms on the surface is found to depend on the temperature during oxidation. The oxidation at high temperatures results in enhanced formation of lower oxides, whereas TiO2 predominates for oxidation at lower temperatures, e.g., 70 °C. Submonolayer coverage of K on NiTi enhances the formation of TiO2 on the expense of lower oxides, which is of consequence for formation of a protective oxide layer and biocompatibility. Oxidation in the martensitic phase was found to be independent of temperature for temperatures between −40 and 10 °C, whereas in the austenitic phase the oxide growth is thermally activated.
Upconversion and anomalous power dependence in Ca12Al14O33:Er3+/Yb3+ single phase nanophosphor
Authors: Joshi C. , Kumar K. , Rai S. B.
Published: June 2009

Ca 12 Al 14 O 33  (Ca12Al7) phase nanophosphor material codoped with Er3+/Yb3+ ions has been synthesized through combustion route, and its UV/visible upconversion luminescence excited by infrared of 976 nm radiation has been monitored. Different batches of samples were calcinated in air at different temperatures, and then changes in the upconversion luminescence have been studied. Freshly synthesized sample shows low upconversion efficiency; however the sample calcinated at 1473 K shows a bright upconverted emission. The Yb3+ and Yb2+ ionic states of Yb have been observed in the samples, and the enhancement in upconversion intensities has been attributed to the conversion of Yb2+ and Yb3+. The upconversion emissions from Er3+ ions have been observed at 335, 366, 380, 408, 475, 523, 548, 661, and 848 nm wavelengths and have been assigned to the transitions G49/2→I413/2, G29/2→I415/2, G411/2→I415/2, P23/2→I413/2(H29/2→I415/2), F43/2→I415/2, H211/2→I415/2, S43/2→I415/2, F49/2→I415/2, and I49/2→I415/2, respectively. The bands at 408, 523, 548, and 661 nm are very intense and can be detected even with the eye using suitable filters at pump power of as low as 50 mW. The pump power dependence of the emission intensities for different bands has been investigated and shows a strange behavior.
Diagnostic of laser contrast using target reflectivity
Authors: Pirozhkov A. S. , Choi I. W. , Sung J. H. , Lee S. K. , Yu T. J. , Jeong T. M. , Kim I J. , Hafz N. , Kim C. M. , Pae K. H. , Noh Y.-C. , Ko D.-K. , Lee J. , Robinson A. P. L. , Foster P. , Hawkes S. , Streeter M. , Spindloe C. , McKenna P. , Carroll D. C. , Wahlström C.-G. , Zepf M. , Adams D. , Dromey B. , Markey K. , Kar S. , Li Y. T. , Xu M. H. , Nagatomo H. , Mori M. , Yogo A. , Kiriyama H. , Ogura K. , Sagisaka A. , Orimo S. , Nishiuchi M. , Sugiyama H. , Esirkepov T. Zh. , Okada H. , Kondo S. , Kanazawa S. , Nakai Y. , Akutsu A. , Motomura T. , Tanoue M. , Shimomura T. , Ikegami M. , Daito I. , Kando M. , Kameshima T. , Bolton P. , Bulanov S. V. , Daido H. , Neely D.
Published: June 2009

Using three different laser systems, we demonstrate a convenient and simple plasma based diagnostic of the contrast of high-power short-pulse lasers. The technique is based on measuring the specular reflectivity from a solid target. The reflectivity remains high even at relativistic intensities above 1019 W/cm2 in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops with increasing intensities in the case of systems with insufficient contrast due to beam breakup and increased absorption caused by preplasma.
Microscale structural model of Alzheimer Aβ(1–40) amyloid fibril
Authors: Paparcone Raffaella , Buehler Markus J.
Published: June 2009

Amyloid fibril formation and characterization are crucial due to their association with severe degenerative disorders such as Alzheimer’s, type II diabetes, and Parkinson’s disease. Here we present an atomistic-based multiscale analysis, utilized to predict the structure of Alzheimer Aβ(1–40) fibrils. Our study provides a structural model of amyloid fibers with lengths of hundreds of nanometers at atomistic resolution. We report a systematic analysis of the energies, structural changes and H-bonding for varying fibril lengths, elucidating their size dependent properties. Our model predicts the formation of twisted amyloid microfibers with a periodicity of ≈82 nm, in close agreement with experimental results.
Structure and dynamics of a Gay–Berne liquid crystal confined in cylindrical nanopores
Authors: Ji Qing , Lefort Ronan , Busselez Rémi , Morineau Denis
Published: June 2009

Gay–Berne liquid crystals confined in two cylindrical nanopores with different pore sizes were studied by molecular dynamics simulation. Their structure and dynamics properties were obtained and compared with those of the bulk. Our data show that confinement changes the bulk isotropic-to-nematic transition to a continuous ordering from a paranematic to a nematic phase. Moreover, confinement strongly hinders the smectic translational order. The molecular dynamics is characterized by the translational diffusion coefficients and the first-rank reorientational correlation times. Very different characteristic times and temperature variations in the dynamics are observed in confinement. Spatially resolved quantities illustrate that confinement induces predominant structural and dynamical heterogeneities.
Tethered DNA dynamics in shear flow
Authors: Zhang Yu , Donev Aleksandar , Weisgraber Todd , Alder Berni J. , Graham Michael D. , de Pablo Juan J.
Published: June 2009

We study the cyclic dynamics of a single polymer tethered to a hard wall in shear flow using Brownian dynamics, the lattice Boltzmann method, and a recent stochastic event-driven molecular dynamics algorithm. We focus on the dynamics of the free end (last bead) of the tethered chain and we examine the cross-correlation function and power spectral density of the chain extensions in the flow and gradient directions as a function of chain length N and dimensionless shear rate Wi. Extensive simulation results suggest a classical fluctuation-dissipation stochastic process and question the existence of periodicity of the cyclic dynamics, as previously claimed. We support our numerical findings with a simple analytical calculation for a harmonic dimer in shear flow.
Acoustic detection of microbubble resonance
Authors: Thomas D. H. , Looney P. , Steel R. , Pelekasis N. , McDicken W. N. , Anderson T. , Sboros V.
Published: June 2009

Large numbers of acoustic signals from single lipid-shelled Definity® microbubbles have been measured using a calibrated microacoustic system and a two population response observed. Theoretical results based on the Mooney–Rivlin strain softening shell model have been used to identify these populations as primary resonant and off-primary resonant scatter. An experimentally measured size distribution was used to provide the initial resting radius for the simulations, and the responses agree well with the experimental data. In this way, the primary resonant or off-primary resonant behavior of a microbubble can be studied, with potential benefits to both signal processing techniques and microbubble manufacture.
Production and ion-ion cooling of highly charged ions in electron string ion source
Authors: Donets D. E. , Donets E. D. , Donets E. E. , Salnikov V. V. , Shutov V. B. , Syresin E. M.
Published: June 2009

The scheme of an internal injection of Au atoms into the working space of the “Krion-2” electron string ion source (ESIS) was applied and tested. In this scheme Au atoms are evaporated from the thin tungsten wire surface in vicinity of the source electron string. Ion beams with charge states up to Au51+ were produced. Ion-ion cooling with use of C and O coolant ions was studied. It allowed increasing of the Au51+ ion yield by a factor of 2. Ions of Kr up to charge state 28+ were also produced in the source. Electron strings were first formed with injection electron energy up to 6 keV. Methods to increase the ESIS ion output are discussed.
Hydrogen atoms in Debye plasma environments
Authors: Paul S. , Ho Y. K.
Published: June 2009

Plasma-screening effects are investigated on hydrogen atoms embedded in weakly coupled plasmas. In the present context, bound state wave functions are introduced related to the screening Coulomb potential (Debye model) using the Ritz variation method. The bound energies are derived from an energy equation, which contains one unknown variational parameter. To calculate the parameter numerically, fixed-point iteration scheme is used. The calculated energy eigenvalues for various Debye lengths agree well with the other available theoretical results. The radial wave functions and radial probability distribution functions are presented for different Debye lengths. The outcomes show that the plasma affects the embedded hydrogen atom.
A phase-field approach to no-slip boundary conditions in dissipative particle dynamics and other particle models for fluid flow in geometrically complex confined systems
Authors: Xu Zhijie , Meakin Paul
Published: June 2009

Dissipative particle dynamics (DPD) is an effective mesoscopic particle model with a lower computational cost than molecular dynamics because of the soft potentials that it employs. However, the soft potential is not strong enough to prevent the DPD particles that are used to represent the fluid from penetrating solid boundaries represented by stationary DPD particles. A phase-field variable, ϕ(x,t), is used to indicate the phase at point x and time t, with a smooth transition from −1 (phase 1) to +1 (phase 2) across the interface. We describe an efficient implementation of no-slip boundary conditions in DPD models that combines solid-liquid particle-particle interactions with reflection at a sharp boundary located with subgrid scale accuracy using the phase field. This approach can be used for arbitrarily complex flow geometries and other similar particle models (such as smoothed particle hydrodynamics), and the validity of the model is demonstrated by DPD simulations of flow in confined systems with various geometries.
Fast detection of a protozoan pathogen, Perkinsus marinus, using AlGaN/GaN high electron mobility transistors
Authors: Wang Yu-Lin , Chu B. H. , Chen K. H. , Chang C. Y. , Lele T. P. , Papadi G. , Coleman J. K. , Sheppard B. J. , Dungen C. F. , Pearton S. J. , Johnson J. W. , Rajagopal P. , Roberts J. C. , Piner E. L. , Linthicum K. J. , Ren F.
Published: June 2009

Antibody-functionalized, Au-gated AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect Perkinsus marinus. The antibody was anchored to the gate area through immobilized thioglycolic acid. The AlGaN/GaN HEMT drain-source current showed a rapid response of less than 5 s when the infected solution was added to the antibody-immobilized surface. The sensor can be recycled with a phosphate buffered saline wash. These results clearly demonstrate the promise of field-deployable electronic biological sensors based on AlGaN/GaN HEMTs for Perkinsus marinus detection.
An improved velocity increment model based on Kolmogorov equation of filtered velocity
Authors: Fang L. , Shao L. , Bertoglio J. P. , Cui G. X. , Xu C. X. , Zhang Z. S.
Published: June 2009

The velocity increment (VI) model, which was introduced by Brun et al., is improved by employing the Kolmogorov equation of filtered velocity in this paper. This model has two different formulations: a dynamic formulation and a simplified constant form in high Reynolds number turbulence. A priori tests in isotropic turbulence and wall-bounded turbulence are performed. A posteriori tests of decaying turbulence and channel Poiseuille flow are made to testify the model performance, especially on the energy backscatter. The simple constant coefficient formulation has good performance, and avoids the ensemble average operation, which exists in other subgrid models. This constant improved VI model is particularly proposed in complicated large-eddy simulation projects.
Room-temperature temperature sensitivity and resolution of doped-silicon microcantilevers
Authors: Corbin Elise A. , Park Keunhan , King William P.
Published: June 2009

An atomic force microscope microcantilever having an integrated solid-state resistor can be used as a heater or a resistive thermometer. The temperature sensitivity and resolution of these cantilevers were investigated under steady and periodic operation near 300 K. Overall, the temperature coefficient of resistance of the cantilever is 0.0029 K−1 at 300 K. When the cantilever is placed under periodic heating conditions the temperature resolution is measured as low as 5 mK. This characterization of heated cantilevers enables precise measurement of small temperature changes, and could improve nanoscale thermal measurements.
Ultrafast photodetection in an all-silicon chip enabled by two-photon absorption
Authors: Bravo-Abad J. , Ippen E. P. , Soljačić M.
Published: June 2009

In this letter we theoretically demonstrate that by dramatically enhancing two-photon absorption, all-silicon optical microresonators can act as efficient photodetectors for light at telecom wavelengths. We illustrate this approach with two specific designs based on a ring resonator and a photonic crystal cavity. The proposed scheme is fully compatible with standard silicon complementary metal-oxide-semiconductor processing technology, and thus, could contribute to the development of chip-scale integrated photodetectors based exclusively on silicon.
Low thermal conductivity in Ge2Sb2Te5–SiOx for phase change memory devices
Authors: Lee Tae-Yon , Kim Kijoon H. P. , Suh Dong-Seok , Kim Cheolkyu , Kang Youn-Seon , Cahill David G. , Lee Dongbok , Lee Min-Hyun , Kwon Min-Ho , Kim Ki-Bum , Khang Yoonho
Published: June 2009

Nanometer scale Ge2Sb2Te5 (GST) domains formed by immiscible mixture of GST-SiOx at room temperature and 180 °C show remarkable suppression in electrical and thermal conductivity. Thermal boundary resistance with increased GST-SiOx interface becomes crucial to the reduction in thermal conductivity. These conductivity reductions concurrently result in the reduction in programming current and power consumption in phase change memory devices.
Optical nonlinearities of Se-loaded zeolite (ZSM-5): A molded nanowire system
Authors: Tanaka Keiji , Saitoh Akira
Published: June 2009

Nonlinear optical properties of Se-loaded ZSM-5 single crystals have been studied comparatively with those of glassy Se. Two-photon absorption coefficients and intensity-dependent refractive-index of the Se-zeolite are higher by three orders of magnitude than those of glassy Se. The enhancements can be ascribed to electron confinement in single Se chains.
Human-induced evolution caused by unnatural selection through harvest of wild animals
Authors: Allendorf Fred W. , Hard Jeffrey J.
Published: June 2009

Human harvest of phenotypically desirable animals from wild populations imposes selection that can reduce the frequencies of those desirable phenotypes. Hunting and fishing contrast with agricultural and aquacultural practices in which the most desirable animals are typically bred with the specific goal of increasing the frequency of desirable phenotypes. We consider the potential effects of harvest on the genetics and sustainability of wild populations. We also consider how harvesting could affect the mating system and thereby modify sexual selection in a way that might affect recruitment. Determining whether phenotypic changes in harvested populations are due to evolution, rather than phenotypic plasticity or environmental variation, has been problematic. Nevertheless, it is likely that some undesirable changes observed over time in exploited populations (e.g., reduced body size, earlier sexual maturity, reduced antler size, etc.) are due to selection against desirable phenotypes—a process we call “unnatural” selection. Evolution brought about by human harvest might greatly increase the time required for over-harvested populations to recover once harvest is curtailed because harvesting often creates strong selection differentials, whereas curtailing harvest will often result in less intense selection in the opposing direction. We strongly encourage those responsible for managing harvested wild populations to take into account possible selective effects of harvest management and to implement monitoring programs to detect exploitation-induced selection before it seriously impacts viability.
Genetics and ecological speciation
Authors: Schluter Dolph , Conte Gina L.
Published: June 2009

Species originate frequently by natural selection. A general mechanism by which this occurs is ecological speciation, defined as the evolution of reproductive isolation between populations as a result of ecologically-based divergent natural selection. The alternative mechanism is mutation-order speciation in which populations fix different mutations as they adapt to similar selection pressures. Although numerous cases now indicate the importance of ecological speciation in nature, very little is known about the genetics of the process. Here, we summarize the genetics of premating and postzygotic isolation and the role of standing genetic variation in ecological speciation. We discuss the role of selection from standing genetic variation in threespine stickleback (Gasterosteus aculeatus), a complex of species whose ancestral marine form repeatedly colonized and adapted to freshwater environments. We propose that ecological speciation has occurred multiple times in parallel in this group via a “transporter” process in which selection in freshwater environments repeatedly acts on standing genetic variation that is maintained in marine populations by export of freshwater-adapted alleles from elsewhere in the range. Selection from standing genetic variation is likely to play a large role in ecological speciation, which may partly account for its rapidity.
Pristine extraterrestrial material with unprecedented nitrogen isotopic variation
Authors: Briani Giacomo , Gounelle Matthieu , Marrocchi Yves , Mostefaoui Smail , Leroux Hugues , Quirico Eric , Meibom Anders
Published: June 2009

Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (δ
15
N
AIR
= −310 ± 20‰), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (δ
15
N
AIR
= 4,900 ± 300‰). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies.
Adaptive radiations: From field to genomic studies
Authors: Hodges Scott A. , Derieg Nathan J.
Published: June 2009

Adaptive radiations were central to Darwin's formation of his theory of natural selection, and today they are still the centerpiece for many studies of adaptation and speciation. Here, we review the advantages of adaptive radiations, especially recent ones, for detecting evolutionary trends and the genetic dissection of adaptive traits. We focus onAquilegiaas a primary example of these advantages and highlight progress in understanding the genetic basis of flower color. Phylogenetic analysis ofAquilegiaindicates that flower color transitions proceed by changes in the types of anthocyanin pigments produced or their complete loss. Biochemical, crossing, and gene expression studies have provided a wealth of information about the genetic basis of these transitions inAquilegia. To obtain both enzymatic and regulatory candidate genes for the entire flavonoid pathway, which produces anthocyanins, we used a combination of sequence searches of theAquilegiaGene Index, phylogenetic analyses, and the isolation of novel sequences by using degenerate PCR and RACE. In total we identified 34 genes that are likely involved in the flavonoid pathway. A number of these genes appear to be single copy inAquilegiaand thus variation in their expression may have been key for floral color evolution. Future studies will be able to use these sequences along with next-generation sequencing technologies to follow expression and sequence variation at the population level. The genetic dissection of other adaptive traits inAquilegiashould also be possible soon as genomic resources such as whole-genome sequencing become available.
Mouse model ofOPRM1(A118G) polymorphism has sex-specific effects on drug-mediated behavior
Authors: Mague Stephen D. , Isiegas Carolina , Huang Peng , Liu-Chen Lee-Yuan , Lerman Caryn , Blendy Julie A.
Published: June 2009

A single nucleotide polymorphism (SNP) in the human μ-opioid receptor gene (OPRM1A118G) has been widely studied for its association in a variety of drug addiction and pain sensitivity phenotypes; however, the extent of these adaptations and the mechanisms underlying these associations remain elusive. To clarify the functional mechanisms linking theOPRM1A118G SNP to addiction and analgesia phenotypes, we derived a mouse model possessing the equivalent nucleotide/amino acid substitution in theOprm1gene. Mice harboring this SNP (A112G) demonstrated several phenotypic similarities to humans carrying the A118G SNP, including reduced mRNA expression and morphine-mediated antinociception. We found additional phenotypes associated with this SNP including significant reductions of receptor protein levels, morphine-mediated hyperactivity, and the development of locomotor sensitization in mice harboring the G112 allele. In addition, we found sex-specific reductions in the rewarding properties of morphine and the aversive components of naloxone-precipitated morphine withdrawal. Further cross-species analysis will allow us to investigate mechanisms and adaptations present in humans carrying this SNP.
Motivational states activate distinct hippocampal representations to guide goal-directed behaviors
Authors: Kennedy Pamela J. , Shapiro Matthew L.
Published: June 2009

Adaptive behaviors are guided by motivation and memory. Motivational states specify goals, and memory can inform motivated behavior by providing detailed records of past experiences when goals were obtained. These 2 fundamental processes interact to guide animals to biologically relevant targets, but the neuronal mechanisms that integrate them remain unknown. To investigate these mechanisms, we recorded unit activity from the same population of hippocampal neurons as rats performed identical tasks while either food or water deprived. We compared the influence of motivational state (hunger and thirst), memory demand, and spatial behavior in 2 tasks: hippocampus-dependent contextual memory retrieval and hippocampus-independent random foraging. We found that: (
i
) hippocampal coding was most strongly influenced by motivational state during contextual memory retrieval, when motivational cues were required to select among remembered, goal-directed actions in the same places; (
ii
) the same neuronal populations were relatively unaffected by motivational state during random foraging, when hunger and thirst were incidental to behavior, and signals derived from deprivation states thus informed, but did not determine, hippocampal coding; and (
iii
) “prospective coding” in the contextual retrieval task was not influenced by allocentric spatial trajectory, but rather by the animal's deprivation state and the associated, non-spatial target, suggesting that hippocampal coding includes a wide range of predictive associations. The results show that beyond coding spatiotemporal context, hippocampal representations encode the relationships between internal states, the external environment, and action to provide a mechanism by which motivation and memory are coordinated to guide behavior.
Functional characterization of human variants of the mu-opioid receptor gene
Authors: Ravindranathan Ajay , Joslyn Geoff , Robertson Margaret , Schuckit Marc A. , Whistler Jennifer L. , White Raymond L.
Published: June 2009

Opioids and their receptors have an important role in analgesia and alcohol and substance use disorders (ASUD). We have identified several naturally occurring amino acid changing variants of the human mu-opioid receptor (MOR), and assessed the functional consequences of these previously undescribed variants in stably expressing cell lines. Several of these variants had altered trafficking and signaling properties. We found that an L85I variant showed significant internalization in response to morphine, in contrast to the WT MOR, which did not internalize in response to morphine. Also, when L85I and WT receptor were coexpressed, WT MOR internalized with the L85I MOR, suggesting that, in the heterozygous condition, the L85I phenotype would be dominant. This finding is potentially important, because receptor internalization has been associated with development of tolerance to opiate analgesics. In contrast, an R181C variant abolished both signaling and internalization in response to saturating doses of the hydrolysis-resistant enkephalin [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO). Coexpression of the R181C and WT receptor led to independent trafficking of the 2 receptors. S42T and C192F variants showed a rightward shift in potency of both morphine and DAMGO, whereas the S147C variant displayed a subtle leftward shift in morphine potency. These data suggest that these and other such variants may have clinical relevance to opioid responsiveness to both endogenous ligands and exogenous drugs, and could influence a broad range of phenotypes, including ASUD, pain responses, and the development of tolerance to morphine.
Relationships Between Body Mass Index, Mental Health, and Suicidal Ideation: Population Perspective Using Two Methods
Authors: Goldney Robert D. , Dunn Kirsten I. , Air Tracy M. , Dal Grande Eleanora , Taylor Anne W.
Published: June 2009

Objective: The aim of the present study was to examine the relationship between body mass index (BMI), mental health, and suicidal ideation in a general population.

Method: Two random and representative samples were drawn from the South Australian population. The interview techniques differed, as did the measures of depression and suicidality. One involved 3034 people in face-to-face interviews, and the other involved 30 214 persons providing information via a computer-assisted telephone interviewing (CATI) system. BMI was classified according to World Health Organization criteria. In face-to-face interviews, major depression was defined by the Primary Care Evaluation of Mental Disorders (PRIME-MD) and suicidal ideation by direct enquiry. In the CATI data, psychological distress was assessed on the Kessler 10 instrument and suicidal ideation by four items on the General Health Questionnaire (GHQ). Data analysis controlled for demographic and physical health variables.

Results: In the face-to-face interviews, the combined obese and morbidly obese men were significantly less likely to have major depression or suicidal ideation than those of a healthy weight. For the telephone interview-derived data, the only significant finding was for overweight women to report less psychological distress than those of a healthy weight.

Conclusions: It is no longer tenable to assume that increased BMI is necessarily associated with major depression, psychological distress, or suicidal ideation. Indeed, it appears protective for some people.
Service Use for Mental Health Problems: Findings from the 2007 National Survey of Mental Health and Wellbeing
Authors: Burgess Philip M. , Pirkis Jane E. , Slade Tim N. , Johnston Amy K. , Meadows Graham N. , Gunn Jane M.
Published: June 2009

Objectives: To provide an overview of 12 month rates of service use for mental health problems and mental disorders by the general Australian adult population.

Method: Data came from the 2007 National Survey of Mental Health and Wellbeing (2007 NSMHWB), a nationally representative household survey of 8841 individuals aged between 16 and 85 years.

Results: Overall, 11.9% of the general Australian adult population made use of any services for mental health problems in a 12 month period. Approximately one-third of people (34.9%) meeting criteria for a mental disorder did so. Female subjects with mental disorders were more likely to use services than male subjects (40.7% vs 27.5%). People in the youngest age group made relatively less use of services than older adults. Those with affective disorders were most likely to make use of services (58.6%), followed by those with anxiety (37.8%) and substance use disorders (24.0%), respectively. Mental health hospitalizations were less common than consultations with community-based providers (2.6%), whereas 34.6% consulted a community-based provider – particularly general practitioners (24.7%) and psychologists (13.2%). There was a clear dose-response effect between severity of disorders and rates of community-based service use: 63.5% of those with severe mental disorders used community-based services, compared with 40.2% and 17.7% of those with moderate and mild mental disorders, respectively. There was also a relationship between comorbidity of mental disorders and service use.

Conclusions: Rates of service use for mental health problems among those with mental disorders in Australia are less than optimal. Little international guidance is available regarding appropriate levels of treatment coverage and other comparable countries face similar difficulties. Further work is required to determine what an appropriate rate of service use is, and to set targets to reach that rate. Australia has demonstrated that concerted policy efforts can improve rates of service use. These efforts should be expanded.
2007 National Survey of Mental Health and Wellbeing: Methods and Key Findings
Authors: Slade Tim , Johnston Amy , Oakley Browne Mark A. , Andrews Gavin , Whiteford Harvey
Published: June 2009

Objective: To provide a description of the methods and key findings of the 2007 Australian National Survey of Mental Health and Wellbeing.

Method: A national face-to-face household survey of 8841 (60% response rate) community residents aged between 16 and 85 years was carried out using the World Mental Health Survey Initiative version of the Composite International Diagnostic Interview. Diagnoses were made according to ICD-10. Key findings include the prevalence of mental disorder, sex and age distributions of mental disorders, severity of mental disorders, comorbidity among mental disorders, and the extent of disability and health service use associated with mental disorders.

Results: The prevalence of any lifetime mental disorder was 45.5%. The prevalence of any 12 month mental disorder was 20.0%, with anxiety disorders (14.4%) the most common class of mental disorder followed by affective disorders (6.2%) and substance use disorders (5.1%). Mental disorders, particularly affective disorders, were disabling. One in four people (25.4%) with 12 month mental disorders had more than one class of mental disorder. One-third (34.9%) of people with a mental disorder used health services for mental health problems in the 12 months prior to the interview.

Conclusions: Mental disorders are common in Australia. Many people have more than one class of mental disorder. Mental disorders are associated with substantial disability, yet many people with mental disorders do not seek help for their mental health problems.
Comorbidity in Australia: Findings of the 2007 National Survey of Mental Health and Wellbeing
Authors: Teesson Maree , Slade Tim , Mills Katherine
Published: June 2009

Objective: The aim of the present study was to report the prevalence and patterns of 12 month comorbidity in the 2007 National Survey of Mental Health and Wellbeing (2007 NSMHWB). In this paper the comorbidity between common mental disorders (affective, substance use and anxiety) and between physical and mental disorders is examined.

Method: The 2007 NSMHWB was a nationally representative household survey of 8841 Australian adults (16–85 years) that assessed participants for symptoms of the most prevalent ICD-10 mental disorders.

Results: The common mental disorder classes (affective, anxiety and substance use disorders) often occur together and 25.4% of persons with an anxiety, affective or substance use disorder had at least one other class of mental disorder. A small proportion (3.5%, 95% confidence interval (CI) = 2.3–4.7%) had all three classes of disorder. Mental disorder and physical disorder comorbidity was also common, with 28% (95%CI = 25.1–30.9%) of those with a chronic physical disorder also having a mental disorder. Comorbidity was associated with greater severity and greater health service use.

Conclusions: Comorbidity is widespread and remains a significant challenge for the delivery of effective health-care services and treatment.
Arteriovenous malformations of the uterus
Authors: Cura M. , Martinez N. , Cura A. , Dalsaso T J. , Elmerhi F.
Published: June 2009

Arterial venous malformations (AVM) of the uterus are uncommon entities and should be considered in patients who present with profuse genital bleeding. There are two types of uterine AVM: acquired and congenital. Acquired uterine AVMs are conformed by communications between the uterine arteries and the myometrial veins, and are caused by an iatrogenic event or a pathological condition. Congenital AVMs are the result of abnormal development of primitive vessels that result in connections between pelvic arteries and veins in the uterus without an interconnecting capillary bed. Ultrasonography is a noninvasive diagnostic method able to demonstrate and characterize AVMs of the uterus. AVM in the pelvis may be noted incidentally by computed tomography (CT) of the pelvis, and magnetic resonance imaging (MRI) is frequently used to confirm and further characterize the sonographic findings of uterine AVM. Catheter angiography and embolization are very effective in defining the vascular anatomy and treating uterine vascular abnormalities.
Lucas Pelkmans: Taking it from the top
Authors: Short Ben
Published: June 2009

Pelkmans takes a systems biology approach to endocytosis and viral entry.
Dynamic instability of microtubules requires dynamin 2 and is impaired in a Charcot-Marie-Tooth mutant
Authors: Tanabe Kenji , Takei Kohji
Published: June 2009

Dynamin is a fission protein that participates in endocytic vesicle formation. Although dynamin was originally identified as a microtubule-binding protein, the physiological relevance of this function was unclear. Recently, mutations in the ubiquitously expressed dynamin 2 (dyn2) protein were found in patients with Charcot-Marie-Tooth (CMT) disease, which is an inherited peripheral neuropathy. In this study, we show that one of these mutations, 551Δ3, induces prominent decoration of microtubules with the mutant dyn2. Dyn2 was required for proper dynamic instability of microtubules, and this was impaired in cells expressing the 551Δ3 mutant, which showed a remarkable increase in microtubule acetylation, a marker of stable microtubules. Depletion of endogenous dyn2 with a small interfering RNA also resulted in the accumulation of stable microtubules. Furthermore, the formation of mature Golgi complexes, which depends on microtubule-dependent membrane transport, was impaired in both dyn2 knockdown cells and cells expressing the 551Δ3 mutant. Collectively, our results suggest that dyn2 regulates dynamic instability of microtubules, which is essential for organelle motility, and that this function may be impaired in CMT disease.
De novo transcriptome assembly with ABySS
Authors: Birol Inanç , Jackman Shaun D. , Nielsen Cydney B. , Qian Jenny Q. , Varhol Richard , Stazyk Greg , Morin Ryan D. , Zhao Yongjun , Hirst Martin , Schein Jacqueline E. , Horsman Doug E. , Connors Joseph M. , Gascoyne Randy D. , Marra Marco A. , Jones Steven J. M.
Published: June 2009

Motivation: Whole transcriptome shotgun sequencing data from non-normalized samples offer unique opportunities to study the metabolic states of organisms. One can deduce gene expression levels using sequence coverage as a surrogate, identify coding changes or discover novel isoforms or transcripts. Especially for discovery of novel events, de novo assembly of transcriptomes is desirable.

Results: Transcriptome from tumor tissue of a patient with follicular lymphoma was sequenced with 36 base pair (bp) single- and paired-end reads on the Illumina Genome Analyzer II platform. We assembled ∼194 million reads using ABySS into 66 921 contigs 100 bp or longer, with a maximum contig length of 10 951 bp, representing over 30 million base pairs of unique transcriptome sequence, or roughly 1% of the genome.

Availability and Implementation: Source code and binaries of ABySS are freely available for download at http://www.bcgsc.ca/platform/bioinfo/software/abyss. Assembler tool is implemented in C++. The parallel version uses Open MPI. ABySS-Explorer tool is implemented in Java using the Java universal network/graph framework.

Contact:  ibirol@bcgsc.ca
Proximate mechanisms driving circadian control of neuroendocrine function: Lessons from the young and old
Authors: Williams Wilbur P. , Gibson Erin M. , Wang Connie , Tjho Stephanie , Khattar Neera , Bentley George E. , Tsutsui Kazuyoshi , Kriegsfeld Lance J.
Published: June 2009

Circadian rhythms impact a variety of behavioral and physiological functions contributing to longevity and successful reproduction. In their natural environments, individuals of a species are faced with a multitude of challenges and the coordination of internal processes and behavior with external pressures has been hypothesized to be an important target of natural selection. Several lines of evidence from cyanobacteria, Drosophila, and plants provide strong support for an important role of the circadian clock in survival and reproductive success. Similarly in mammals, disruptions in circadian function markedly impact reproduction and lifespan. The present review discusses research outlining the proximate and ultimate mechanisms responsible for the central and peripheral control of the reproductive axis. Because precise temporal coordination of the endocrine system is particularly crucial for reproduction by females, the present overview focuses on the role of circadian timing in this sex.
A comparative study of optimization methods and conventional methods for sampling design in fishery-independent surveys
Authors: Liu Yong , Chen Yong , Cheng Jiahua
Published: June 2009

Liu, Y., Chen, Y., and Cheng, J. 2009. A comparative study of optimization methods and conventional methods for sampling design in fishery-independent surveys. – ICES Journal of Marine Science, 66: 1873–1882. We have introduced and evaluated a procedure, the constrained spatial simulated annealing method, for developing an optimal sampling design for fishery-independent surveys. We used two criterion functions, minimization of the mean of the shortest distance (MMSD) and uniform distribution of point pairs for variogram estimation (WM), and three arrangements of the two criteria, all WM, all MMSD, and a combination of MMSD (2/3 of samples) and WM (1/3), to construct three optimized sampling designs (denoted as Designs I, II, and III, respectively). These three designs were compared in a simulation study with systematic sampling (Design IV) and stratified random sampling designs (Design V), commonly used in fishery-independent surveys. Three levels of sample size (small, medium, and large) were considered in the simulation study developed using a geostatistical approach. The results showed that for parameter estimation of the spatial covariance function, Design III was better than the other designs at relatively small sample size and Design II performed better than the other designs at relatively large sample size. For estimating fish stock abundance, the performance of the designs considered in this study can be ranked as follows: Design II > Design IV > Design III > Design V > Design I. It is clearly important to evaluate and improve sampling design based on historical survey data. Such a study allows us to identify an optimal sampling design to balance the quality of the data collected and the costs of the sampling programme, leading to the development and optimization of a sustainable and fishery-independent monitoring programme.
Attenuation of Mechanical Hypersensitivity by an Antagonist of the TRPA1 Ion Channel in Diabetic Animals
Authors: Wei Hong , Hämäläinen Minna M. , Saarnilehto Marja , Koivisto Ari , Pertovaara Antti
Published: June 2009

Background

The TRPA1 ion channel modulates excitability of nociceptors, and it may be activated by compounds resulting from oxidative insults. Diabetes mellitus produces oxidative stress and sensory neuropathy. The authors tested the hypothesis that diabetes-induced endogenous compounds acting on the TRPA1 ion channel contribute to development and maintenance of mechanical hypersensitivity.

Methods

Diabetes mellitus was induced by streptozotocin. Mechanical hypersensitivity was assessed by the monofilament and paw pressure tests. Chembridge-5861528 (CHEM; a TRPA1 channel antagonist, a derivative of HC-030031) or vehicle was administered acutely or twice daily for 10 days in diabetic animals. For comparison, effects of CHEM were assessed in a group of healthy control animals.

Results

Acute administration of CHEM attenuated mechanically induced withdrawal responses in diabetic and control groups. The maximal effect (over 50% elevation of the paw pressure threshold) by acute administration of CHEM was obtained in 30 min. The lowest dose producing a significant attenuation was 10 mg/kg in the diabetic group and 30 mg/kg in the healthy controls. Chronic administration of CHEM (30 mg/kg twice daily) for a week in the diabetic group attenuated development of mechanical hypersensitivity.

Conclusions

Reduction of pain-related behavior by a lower dose of the TRPA1 channel antagonist in the diabetic than in the control group suggests that endogenous compounds resulting from diabetes mellitus and acting on the TRPA1 channel contribute to diabetic hypersensitivity. Prolonged antihypersensitivity effect after chronic treatment suggests that daily administration of a TRPA1 channel antagonist may prevent development of diabetic hypersensitivity.
Large eddy simulation for aerodynamics: status and perspectives
Authors: Sagaut Pierre , Deck Sébastien
Published: June 2009

The present paper provides an up-to-date survey of the use of large eddy simulation (LES) and sequels for engineering applications related to aerodynamics. Most recent landmark achievements are presented. Two categories of problem may be distinguished whether the location of separation is triggered by the geometry or not. In the first case, LES can be considered as a mature technique and recent hybrid Reynolds-averaged Navier–Stokes (RANS)–LES methods do not allow for a significant increase in terms of geometrical complexity and/or Reynolds number with respect to classical LES. When attached boundary layers have a significant impact on the global flow dynamics, the use of hybrid RANS–LES remains the principal strategy to reduce computational cost compared to LES. Another striking observation is that the level of validation is most of the time restricted to time-averaged global quantities, a detailed analysis of the flow unsteadiness being missing. Therefore, a clear need for detailed validation in the near future is identified. To this end, new issues, such as uncertainty and error quantification and modelling, will be of major importance. First results dealing with uncertainty modelling in unsteady turbulent flow simulation are presented.