bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of deep level defects in m-plane GaN grown by metalorganic chemical vapor deposition
Authors: Henry T. A. , Armstrong A. , Kelchner K. M. , Nakamura S. , DenBaars S. P. , Speck J. S.
Published: February 2012

We report on deep level defect incorporation in n-type m-plane (101¯0) GaN grown by metalorganic chemical vapor deposition (MOCVD) on bulk m-plane GaN substrates. Deep levels were observed at 2.85 eV and 3.31 eV relative to the conduction band minimum. While the energetic distribution of defect states for m-plane GaN was similar to the previous reports of n-type c-plane GaN grown by MOCVD, the deep level densities of the m-plane GaN were significantly lower. The comparatively low defect density in homoepitaxially grown m-plane GaN is attributed to reduced point defect incorporation. In addition to the absence of polarization fields, the low deep level density achieved by homoepitaxial growth on high quality bulk GaN substrates makes m-plane GaN highly attractive for opto-electronic devices.
Plasmonic detector/spectrometer of subterahertz radiation based on two-dimensional electron system with embedded defect
Authors: Muravev V. M. , Kukushkin I. V.
Published: February 2012

We demonstrate that the introduction of a defect in the form of an electron density step into a two-dimensional electron system (2DES) locally rectifies the alternating potential of plasma waves. The rectification mechanism is active at temperatures up to room temperature. We observe photovoltage oscillations in a back-gated 2DES with a density defect, when tuning the density under incident subterahertz radiation. The oscillations originate from the interference of 2D plasma waves excited by subterahertz radiation. The period of oscillations depends on the radiation wavelength. These phenomena can be exploited further to produce detectors/spectrometers for millimeter waves.
Comparison of nuclear magnetic resonance methods for the analysis of organic matter composition from soil density and particle fractions
Authors: Clemente Joyce S. , Gregorich Edward G. , Simpson André J. , Kumar Rajeev , Courtier-Murias Denis , Simpson Myrna J.
Published: February 2012

Environmental contextThe association of specific organic matter (OM) compounds with clay mineral surfaces is believed to protect these compounds from degradation and thus result in long-term protection in soil. The molecular-level composition of soil OM associated with soil fractions was measured and compared using solid-state 13C nuclear magnetic resonance (NMR) and solution-state 1H NMR methods. Combining these methods allowed more detailed characterisation of OM associated with different soil fractions and will improve the understanding of OM dynamics in soil.
AbstractOrganic matter (OM) associated with fine soil fractions is hypothesised to be protected from complete biodegradation by soil microbes. It is therefore important to understand the structure and stage of decomposition of OM associated with various soil fractions. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy has been used extensively to investigate the OM composition of soils and soil fractions. Solution-state 1H NMR spectroscopy has not been used as much but is an emerging tool for analysing soil OM because 1H NMR spectra are often better resolved and provide information that complements the structural information obtained from solid-state 13C NMR experiments. This study compares one-dimensional solution-state 1H NMR and solid-state 13C NMR methods for assessing the degradation and composition of OM in three different soils, and their light and clay-size fractions. The alkyl/O-alkyl degradation parameter was consistent across all NMR methods and showed that OM associated with clay-size fractions were at more advanced stages of degradation as compared to that in light density soil fractions. Solution-state 1H and diffusion edited (DE) 1H NMR results showed the presence of high concentrations of microbial-derived peptidoglycan and peptide side-chains in clay-sized fractions. Lignin was also identified in clay-sized fractions using solid-state 13C and solution-state 1H NMR techniques. The combination of solid-state 13C and solution-state 1H NMR methods provides a more detailed analysis of OM composition and thereby facilitates a better understanding of the fate and preservation of OM in soil.
An engineered innate immune defense protects grapevines from Pierce disease
Authors: Dandekar Abhaya M. , Gouran Hossein , Ibáñez Ana María , Uratsu Sandra L. , Agüero Cecilia B. , McFarland Sarah , Borhani Yasmin , Feldstein Paul A. , Bruening George , Nascimento Rafael , Goulart Luiz R. , Pardington Paige E. , Chaudhary Anu , Norvell Meghan , Civerolo Edwin , Gupta Goutam
Published: February 2012

We postulated that a synergistic combination of two innate immune functions, pathogen surface recognition and lysis, in a protein chimera would lead to a robust class of engineered antimicrobial therapeutics for protection against pathogens. In support of our hypothesis, we have engineered such a chimera to protect against the Gram-negative
Xylella fastidiosa
(Xf), which causes diseases in multiple plants of economic importance. Here we report the design and delivery of this chimera to target the Xf subspecies
fastidiosa
(Xff), which causes Pierce disease in grapevines and poses a great threat to the wine-growing regions of California. One domain of this chimera is an elastase that recognizes and cleaves MopB, a conserved outer membrane protein of Xff. The second domain is a lytic peptide, cecropin B, which targets conserved lipid moieties and creates pores in the Xff outer membrane. A flexible linker joins the recognition and lysis domains, thereby ensuring correct folding of the individual domains and synergistic combination of their functions. The chimera transgene is fused with an amino-terminal signal sequence to facilitate delivery of the chimera to the plant xylem, the site of Xff colonization. We demonstrate that the protein chimera expressed in the xylem is able to directly target Xff, suppress its growth, and significantly decrease the leaf scorching and xylem clogging commonly associated with Pierce disease in grapevines. We believe that similar strategies involving protein chimeras can be developed to protect against many diseases caused by human and plant pathogens.
The distribution of ligand-binding pockets around protein-protein interfaces suggests a general mechanism for pocket formation
Authors: Gao Mu , Skolnick Jeffrey
Published: February 2012

Protein-protein and protein-ligand interactions are ubiquitous in a biological cell. Here, we report a comprehensive study of the distribution of protein-ligand interaction sites, namely ligand-binding pockets, around protein-protein interfaces where protein-protein interactions occur. We inspected a representative set of 1,611 representative protein-protein complexes and identified pockets with a potential for binding small molecule ligands. The majority of these pockets are within a 6 Å distance from protein interfaces. Accordingly, in about half of ligand-bound protein-protein complexes, amino acids from both sides of a protein interface are involved in direct contacts with at least one ligand. Statistically, ligands are closer to a protein-protein interface than a random surface patch of the same solvent accessible surface area. Similar results are obtained in an analysis of the ligand distribution around domain-domain interfaces of 1,416 nonredundant, two-domain protein structures. Furthermore, comparable sized pockets as observed in experimental structures are present in artificially generated protein complexes, suggesting that the prominent appearance of pockets around protein interfaces is mainly a structural consequence of protein packing and thus, is an intrinsic geometric feature of protein structure. Nature may take advantage of such a structural feature by selecting and further optimizing for biological function. We propose that packing nearby protein-protein or domain-domain interfaces is a major route to the formation of ligand-binding pockets.
Autoinhibition of Mint1 adaptor protein regulates amyloid precursor protein binding and processing
Authors: Matos Maria F. , Xu Yibin , Dulubova Irina , Otwinowski Zbyszek , Richardson John M. , Tomchick Diana R. , Rizo Josep , Ho Angela
Published: February 2012

Mint adaptor proteins bind to the amyloid precursor protein (APP) and regulate APP processing associated with Alzheimer’s disease; however, the molecular mechanisms underlying Mint regulation in APP binding and processing remain unclear. Biochemical, biophysical, and cellular experiments now show that the Mint1 phosphotyrosine binding (PTB) domain that binds to APP is intramolecularly inhibited by the adjacent C-terminal linker region. The crystal structure of a C-terminally extended Mint1 PTB fragment reveals that the linker region forms a short α-helix that folds back onto the PTB domain and sterically hinders APP binding. This intramolecular interaction is disrupted by mutation of Tyr633 within the Mint1 autoinhibitory helix leading to enhanced APP binding and β-amyloid production. Our findings suggest that an autoinhibitory mechanism in Mint1 is important for regulating APP processing and may provide novel therapies for Alzheimer’s disease.
A two-dimensional comprehensive hydrodynamic model for femtosecond laser pulse interaction with metals
Authors: Zhao Xin , Shin Yung C
Published: February 2012

Femtosecond laser–metal interaction in air and the resultant early plasma evolution are investigated by a two-dimensional comprehensive hydrodynamic model in this paper. The model comprises a two-temperature model and a hydrodynamic model supplemented with a quotidian equation of state model, considering the relevant multiphysical phenomena during the laser–metal interaction. The experimental measurements for plasma expansion were carried out to validate the simulation results, using a shadowgraph technique and direct fluorescence measurement. The evolution of both the early plasma and plume plasma is investigated by the model. The early plasma is proved to be generated by electron emission and ambient gas ionization and splits into several portions during its expansion due to different mechanisms. The plume plasma comes from the target material ejection. The photoelectric emission is revealed to be the dominant electron emission mechanism at high laser intensities, while thermal emission is more important at low laser intensities. The electron emission process and early stage plasma are critical to ultrashort laser–metal interaction, especially at high laser intensities. Without considering this, the electron temperature can be overestimated by as much as 70%.
Allele-specific expression analysis methods for high-density SNP microarray data
Authors: Liu Ruijie , Maia Ana-Teresa , Russell Roslin , Caldas Carlos , Ponder Bruce A. , Ritchie Matthew E.
Published: February 2012

Motivation: In the past decade, a number of technologies to quantify allele-specific expression (ASE) in a genome-wide manner have become available to researchers. We investigate the application of single-nucleotide polymorphism (SNP) microarrays to this task, exploring data obtained from both cell lines and primary tissue for which both RNA and DNA profiles are available.

Results: We analyze data from two experiments that make use of high-density Illumina Infinium II genotyping arrays to measure ASE. We first preprocess each data set, which involves removal of outlier samples, careful normalization and a two-step filtering procedure to remove SNPs that show no evidence of expression in the samples being analyzed and calls that are clear genotyping errors. We then compare three different tests for detecting ASE, one of which has been previously published and two novel approaches. These tests vary at the level at which they operate (per SNP per individual or per SNP) and in the input data they require. Using SNPs from imprinted genes as true positives for ASE, we observe varying sensitivity for the different testing procedures that improves with increasing sample size. Methods that rely on RNA signal alone were found to perform best across a range of metrics. The top ranked SNPs recovered by all methods appear to be reasonable candidates for ASE.

Availability and implementation: Analysis was carried out in R (http://www.R-project.org/) using existing functions.

Contact:  mritchie@wehi.edu.au.

Supplementary information:  Supplementary data are available at Bioinformatics online.
34th ANNUAL CARRELL-KRUSEN NEUROMUSCULAR SYMPOSIUM, Texas Scottish Rite Hospital for Children, Dallas, Texas, February 23–24, 2012
Authors: Iannaccone Susan T.
Published: February 2012

The Annual Carrell-Krusen Neuromuscular Symposium is a unique conference attended by more than 200 each year at the Texas Scottish Rite Hospital for Children. Its name honors Dr. Brandon Carrell who retired as physician-in-chief at Texas Scottish Rite Hospital in 1978 and Dr. Ed Krusen who organized the first Muscular Dystrophy Association Clinic in Dallas. This Symposium began in 1978 under the leadership of Dr. Jay Cook as a Muscular Dystrophy Clinic Directors' meeting and is now jointly sponsored by the hospital, the Muscular Dystrophy Association, Childrens' Medical Center of Dallas, and the University of Texas Southwestern Medical Center. The Symposium has grown to be the most popular clinical meeting for neuromuscular specialists in the country. During the three day meeting, attendees participate in lively discussions while meeting interesting and challenging patients. Attendees are invited to contribute interesting electrodiagnostic and histopathologic cases to review with the group. The visiting professor, the recipient of the Carrell-Krusen Award, gives the keynote lecture. The list of awardees represents the development of neuromuscular research for the past 30 years. Currently, the Program Director is Dr. Susan T. Iannaccone.
Mind the gap: genetic distance increases with habitat gap size in Florida scrub jays
Authors: Coulon Aurélie , Fitzpatrick John W. , Bowman Reed , Lovette Irby J.
Published: February 2012

Habitat gap size has been negatively linked to movement probability in several species occupying fragmented landscapes. How these effects on movement behaviour in turn affect the genetic structure of fragmented populations at local scales is less well known. We tested, and confirmed, the hypothesis that genetic differentiation among adjacent populations of Florida scrub jays—an endangered bird species with poor dispersal abilities and a high degree of habitat specialization—increases with the width of habitat gaps separating them. This relationship was not an artefact of simple isolation-by-distance, as genetic distance was not correlated with the Euclidean distance between geographical centroids of the adjacent populations. Our results suggest that gap size affects movement behaviour even at remarkably local spatial scales, producing direct consequences on the genetic structure of fragmented populations. This finding shows that conserving genetic continuity for specialist species within fragmented habitat requires maintenance or restoration of preserve networks in which habitat gaps do not exceed a species-specific threshold distance.
Ambient noise increases missed detections in nestling birds
Authors: Leonard Marty L. , Horn Andrew G.
Published: February 2012

Ambient noise can mask acoustic cues, making their detection and discrimination difficult for receivers. This can result in two types of error: missed detections, when receivers fail to respond to the appropriate cues, and false alarms, when they respond to inappropriate cues. Nestling birds are error-prone, sometimes failing to beg when parents arrive with food (committing missed detections) or begging in response to stimuli other than a parent's arrival (committing false alarms). Here, we ask whether the frequency of these errors by nestling tree swallows (
Tachycineta bicolor
) increases in the presence of noise. We found that nestlings exposed to noise had more missed detections than their unexposed counterparts. We also found that false alarms remained low overall and did not differ significantly between noise and quiet treatments. Our results suggest that nestlings living in noisy environments may be less responsive to their parents than nestlings in quieter environments.
Asymptotic solutions for turbulent mass transfer at high Schmidt number
Authors: van Reeuwijk Maarten , Sookhak Lari Kaveh
Published: February 2012

We present closed-form solutions for high Schmidt number mass transfer in a hydrodynamically fully developed turbulent flow. Governing equations for the near- and far-field are developed for a large class of boundary conditions (BCs) for which the mass flux is a function of the concentration at the wall. We show that for this class of BCs, which includes nonlinear wall reactions, the mass transfer coefficient is independent of the BC and the Sherwood correlation is therefore universal. For Dirichlet, Neumann and Robin BCs, the far-field solutions are in good correspondence with the method of separating variables and near-field solutions are in good agreement with numerical simulations. However, in contrast with the far-field solutions, the Sherwood correlation in the near-field depends on the specific BC. As an example of nonlinear BCs, solutions for a second-order wall reaction are derived which are compared with numerical simulations and found to be in excellent agreement.
Twisted and frustrated states of matter
Authors: Goodby John W.
Published: February 2012

The World, and much of Nature that we see within it, experiences an environment of reduced symmetries. For example, living organisms are dependent on asymmetric or dissymmetric structures for their life processes. In the solid state, a large number of space groups are chiral. Conversely, in liquids, the effects of reduced symmetries are smeared out owing to the dynamical fluctuations of the constituent molecules, atoms or ions. Thus, on progressing from the strongly ordered solid to the amorphous liquid state, the effects of reduced symmetries weaken as the molecular or atomic correlations and penetration lengths fall. Between these two states of matter, the fourth state of organized fluids can be markedly affected by chirality, and over substantial length scales, owing to both the fluidity and partial ordering of the molecules. In effect, complex fluids can amplify the effects of chirality at the molecular level. Broken symmetries in self-organizing systems can lead to the formation of novel phases of matter and to the creation of structured liquids, and to the generation of nonlinear properties such as heli-, ferro-, ferri- and antiferro-electricity, and electroclinism, which can be harnessed in a wide range of applications including thermal sensors, imaging devices and information displays, to name but a few.
A case of acquired FXIII deficiency with severe bleeding symptoms
Authors: Hayashi T. , Kadohira Y. , Morishita E. , Asakura H. , Souri M. , Ichinose A.
Published: February 2012

Summary.  Acquired factor XIII (FXIII) deficiency due to an autoantibody against FXIII is a very rare, yet potentially life‐threatening bleeding disorder. As the standard coagulation tests (prothrombin time and activated partial thromboplastin time) are normal, the specialized tests are required to make an accurate diagnosis. Here, we report a case of acquired FXIII deficiency with severe bleeding symptoms. A 75‐year‐old man was referred to our hospital because of severe bleeding tendency after a tooth extraction. Laboratory findings showed that routine coagulation studies were normal, but factor XIII (FXIII) activity was low (3%). The presence of FXIII inhibitor was detected with dot blotting studies. Although the bleeding tendency was very severe, it was successfully controlled by infusion of FXIII concentrates combined with immunosuppressive treatment (oral prednisolone). Fibrin cross‐linking study showed the significant delay of the γ‐chain dimer and α‐chain polymer formation. Western blotting revealed the marked decrease in FXIII‐A level. The mixing study of FXIII activity measured using amine‐incorporation assay showed the incomplete inhibition pattern. There seems to be little agreement as to the treatment strategy of acquired FXIII deficiency. In this patient, the use of FXIII concentrates was very useful in the initial treatment of bleeding symptom. The use of steroids was also effective in increasing FXIII activity without any serious complications.
Dental attendance in preschool children – a prospective study
Authors: LEROY ROOS , BOGAERTS KRIS , HOPPENBROUWERS KAREL , MARTENS LUC C. , DECLERCK DOMINIQUE
Published: February 2012

International Journal of Paediatric Dentistry 2013; 23: 84–93

Background.  At present, our understanding of the use of dental care services is incomplete, certainly where preschool children are concerned.

Objectives.  To investigate what proportion of 3‐ and 5‐year‐olds living in Flanders (Belgium) have already visited the dentist, to describe parents’ experience about their child’s dental visit, and to explore factors that may have an impact on children’s early dental visit.

Design.  Data were collected from 1057 children; validated questionnaires were completed, and children were examined by trained dentist at ages 3 and 5. Logistic regression analyses were performed to explain dental attendance.

Results.  At the age of 3, 62% and by 5 years, 21% had never visited the dentist. The first dental visit was considered a pleasant experience for the majority of children. Multivariable regression analyses revealed that children who were not first born, whose mothers had a higher educational level and whose parents had recently visited the dentist, had significantly higher odds for having visited the dentist at young age.

Conclusions.  Parents of young children need to be informed about and motivated for an early dental visit. Promotion campaigns should focus on firstborn children, children from less educated parents, and parents who do not regularly see a dentist.
Quantitative comparison between full‐spectrum and filter‐based imaging in hyperspectral fluorescence microscopy
Authors: GAO L. , HAGEN N. , TKACZYK T.S.
Published: February 2012

We implement a filterless illumination scheme on a hyperspectral fluorescence microscope to achieve full‐range spectral imaging. The microscope employs polarisation filtering, spatial filtering and spectral unmixing filtering to replace the role of traditional filters. Quantitative comparisons between full‐spectrum and filter‐based microscopy are provided in the context of signal dynamic range and accuracy of measured fluorophores’ emission spectra. To show potential applications, a five‐colour cell immunofluorescence imaging experiment is theoretically simulated. Simulation results indicate that the use of proposed full‐spectrum imaging technique may result in three times improvement in signal dynamic range compared to that can be achieved in the filter‐based imaging.
Morphological Observation of a Horseshoe (fused) Kidney and its Vascular Pattern in a Horse
Authors: Shojaei B. , Kheirandish R. , Azizi S.
Published: February 2012

The present study describes the anatomical and microscopic features of a horseshoe kidney that was found in a 7‐year‐old male horse. The specimen consisted of two kidneys joined at their caudal poles by an isthmus composed of renal parenchyma and situated caudal to the caudal mesenteric artery. Six main renal arteries arose from the aorta and the external iliac arteries and ramified into 21 branches before entering the kidney. A hypoplastic and ectopic left testis, located in the inguinal canal, was observed as an associated anomaly.
Regulation of pancreatic exocrine secretion in goats: differential effects of short‐ and long‐term duodenal phenylalanine treatment
Authors: Yu Z. P. , Xu M. , Yao J. H. , Liu K. , Li F. , Liu Y. , Wang F. , Sun F. F. , Liu N. N.
Published: February 2012

Four yearling goats (31.2 ± 2.5 kg), surgically fitted with common bile duct reentrant and duodenal catheter, were used in two 4 × 4 Latin square design experiments to investigate the effects of duodenal infusion of phenylalanine for different times on pancreatic exocrine secretion (PES). In experiment 1 (the long‐term experiment), goats were duodenally infused with 0, 2, 4 or 8 g/day phenylalanine for 14 day. Pancreatic juice and jugular blood samples were collected over 1‐h intervals for 6 h daily from day 11 to day 14 to encompass a 24‐h day. In experiment 2 (the short‐term experiment), goats were infused with phenylalanine for 10 h continuously at the same infusion rate as experiment 1 after feed deprivation for 24 h repeated every 10 day. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10 h of infusion. The volume and pH of pancreatic juice were measured, and a 5% subsample was composited and frozen until analysis of enzyme activities. Plasma was frozen until analysis of insulin and cholecystokinin (CCK). In experiment 1, pancreatic juice, α‐amylase secretion and plasma CCK concentration responded quadratically (p < 0.05), with the top value observed at the 2 g/day phenylalanine. Trypsin secretion had a quadratic response (p < 0.05), with secretion increasing up to 4 g/day phenylalanine and decreasing thereafter. Phenylalanine linearly decreased pancreatic protein and lipase secretion (p < 0.05). The results of correlation analysis showed significant correlations (p < 0.05) between plasma CCK concentration and secretion of α‐amylase and trypsin. However, the short‐term phenylalanine infusion did not influence (p > 0.05) pancreatic juice, protein, α‐amylase, lipase, trypsin secretion and plasma CCK concentration. These results indicate PES of ruminants is stimulated by phenylalanine and is potentially mediated by CCK in the long‐term duodenal infusion treatment, but is not influenced by phenylalanine in the short‐term duodenal infusion treatment.
Angle closure and angle‐closure glaucoma: what we are doing now and what we will be doing in the future
Authors: Friedman David S , Foster Paul J , Aung Tin , He Mingguang
Published: February 2012

Abstract

Primary angle‐closure glaucoma (PACG) frequently leads to severe vision loss. Prevalence among older Asian populations is high and given global demographics, the number of persons with PACG will increase dramatically in the coming decades. Improvements in imaging of the anterior segment will help us to identify more of those with angle closure, and important clinical trials that are currently underway will provide important evidence to support screening and treatment approaches for PACG. In this manuscript, we intend to review the existing evidences, to introduce some important on‐going studies on PACG and to share the experience and viewpoints of the authors.
Recreational drug use in type 1 diabetes: an invisible accomplice to poor glycaemic control?
Authors: Lee P. , Greenfield J. R. , Gilbert K. , Campbell L. V.
Published: February 2012

Recreational drug use during ‘rave’ parties is increasingly popular, but the impact of recreational drug use in type 1 diabetes (T1D) is not known. We determined the self‐reported pattern and effects of recreational/illicit drug use in Australians with T1D people by inviting people with T1D to participate in an anonymous online/paper survey of drug use, through national radio broadcast and online/hospital advertising. Of the people with T1D who responded to our survey, more than three quarters reported having used recreational/illicit drug, but few people had informed health professionals about drug use. Drug use was associated with worse glycaemic control and higher risk of diabetic ketoacidosis. Medical awareness of common, currently underreported, drug use in young people with T1D is essential. It offers the possibility of helping such patients improve related suboptimal metabolic control.
Fetal developmental change in topographical relationship between the human lateral pterygoid muscle and buccal nerve
Authors: Katori Y. , Yamamoto M. , Asakawa S. , Maki H. , Rodríguez‐Vázquez J. F. , Murakami G. , Abe S.
Published: February 2012

In adults, the lateral pterygoid muscle (LPM) is usually divided into the upper and lower heads, between which the buccal nerve passes. Using sagittal or horizontal sections of 14 fetuses and seven embryos (five specimens at approximately 20–25 weeks; five at 14–16 weeks; four at 8 weeks; seven at 6–7 weeks), we examined the topographical relationship between the LPM and the buccal nerve. In large fetuses later than 15 weeks, the upper head of the LPM was clearly discriminated from the lower head. However, the upper head was much smaller than the lower head in the smaller fetuses. Thus, in the latter, the upper head was better described as an ‘anterior slip’ extending from the lower head or the major muscle mass to the anterior side of the buccal nerve. The postero‐anterior nerve course seemed to be determined by a branch to the temporalis muscle (i.e. the anterior deep temporal nerve). At 8 weeks, the buccal nerve passed through the roof of the small, fan‐like LPM. At 6–7 weeks, the LPM anlage was embedded between the temporobuccal nerve trunk and the inferior alveolar nerve. Therefore, parts of the LPM were likely to ‘leak’ out of slits between the origins of the mandibular nerve branches at 7–8 weeks, and seemed to grow in size during weeks 14–20 and extend anterosuperiorly along the infratemporal surface of the prominently developing greater wing of the sphenoid bone. Consequently, the topographical relationship between the LPM and the buccal nerve appeared to ‘change’ during fetal development due to delayed development of the upper head.
Kv7 (KCNQ) channel openers normalize central 2‐deoxyglucose uptake in a mouse model of mania and increase prefrontal cortical and hippocampal serine‐9 phosphorylation levels of GSK3β
Authors: Kristensen Line V. , Sandager‐Nielsen Karin , Hansen Henrik H.
Published: February 2012

J. Neurochem. (2012) 121, 373–382.

Several metabolic neuroimaging studies have indicated that bipolar patients with mania exhibit alterations in metabolic activity, suggesting that perturbations in corticolimbic function contribute to the functional deficits associated with the disease. Because pharmacological stimulation of Kv7 channel function has shown anti‐manic like efficacy in the D‐amphetamine and chlordiazepoxide (AMPH+CDP) induced hyperactivity mouse model of mania, we addressed whether this effect of Kv7 channels could be associated with changes in cerebral [14C]2‐deoxyglucose (2‐DG) uptake, a surrogate marker of brain metabolic activity. Acute administration of the Kv7 channel modulators, retigabine (pan Kv7.2‐Kv7.5 channel opener) and ICA‐27243 (Kv7.2/Kv7.3 channel‐preferring opener) reduced 2‐DG uptake in several mouse forebrain structures with a brain regional signature similar to the mood stabilizers, lithium and valproate. Combined administration of AMPH+CDP enhanced 2‐DG uptake in the striatum, cortex and thalamus, and both retigabine and ICA‐27243 fully prevented this stimulatory effect of AMPH+CDP. In addition, both Kv7 channel openers dose‐dependently increased phospho‐serine‐9 levels of GSK3β in the prefrontal cortex and hippocampus, a common molecular mechanism shared by anti‐manic drugs. In combination, these data emphasize the potential of Kv7 channel openers in the treatment of bipolar disorder, and suggest that heteromeric Kv7.2/Kv7.3 channels may present a novel anti‐manic therapeutic target.
Holocene aeolian dynamics in the European sand‐belt as indicated by geochronological data
Authors: Tolksdorf Johann Friedrich , Kaiser Knut
Published: February 2012

Aeolian sands are widespread in the European sand‐belt. While there is a consensus about the timing of increased aeolian activity and, in contrast, of surface stabilization during the Lateglacial, knowledge about Holocene aeolian dynamics is still very sparse. It is generally assumed that aeolian processes have been closely connected to human activities since at least the Neolithic period. A compilation of 189 luminescence dates from aeolian sands of Holocene age and 301 14C‐dates from palaeo‐surfaces, comprising palaeosols, buried peats and archaeological features from the whole sand‐belt, is plotted as histograms and kernel density plots and divided into sub‐phases by cluster analysis. This is also done separately for the dates from the areas west and east of the river Elbe. Our results show that aeolian activity did not cease with the end of the Younger Dryas but continued in the whole European sand‐belt until the Mid‐Atlantic (c. 6500 a BP), presenting evidence of vegetation‐free areas at least at the local scale. During the subsequent time period evidence of aeolian sedimentation is sparse, and surface stabilization is indicated by a cluster of palaeo‐surfaces ascribed to the early Subboreal (c. 5000 cal. a BP). The agglomeration of luminescence ages around 4000 years is probably connected with intensified land use during the Late Neolithic. Younger phases of aeolian sedimentation are indicated by clusters of luminescence ages around 1800 years, a group of luminescence ages from the Netherlands and NW Germany around 900 years, and a group of ages around 680 years in Germany. Among the dates from palaeo‐surfaces, clusters were identified around 2700, 1300 and 900 cal. a BP as well as around 690 cal. a BP in the western part and 610 cal. a BP in the eastern part of the sand‐belt. The clusters within the luminescence ages and the 14C‐dates coincide with phases where increased human impact can be deduced from archaeological and historical sources as well as from environmental history.
No direct role for A1/A2 adenosine receptor activation to reflex cutaneous vasodilatation during whole‐body heat stress in humans
Authors: Fieger S. M. , Wong B. J.
Published: February 2012

Aim

The precise mechanisms underlying reflex cutaneous vasodilatation during hyperthermia remain unresolved. The purpose of this study was to investigate a potential contribution of adenosine A1/A2 receptor activation to reflex cutaneous vasodilatation.

Methods

Eight subjects were equipped with four microdialysis fibres on the left forearm, and each fibre was randomly assigned one of four treatments: (1) lactated Ringer's (control); (2) 4 mm of the non‐selective A1/A2 adenosine receptor antagonist theophylline; (3) 10 mm L‐NAME to inhibit nitric oxide (NO) synthase; and (4) combined 4 mm theophylline and 10 mm L‐NAME. Laser‐Doppler flowmetry (LDF) was used as an index of skin blood flow, and blood pressure was measured beat‐by‐beat via photoplethysmography and verified via brachial auscultation. Whole‐body heat stress to raise oral temperature 0.8 °C above baseline was induced via water‐perused suits. Cutaneous vascular conductance (CVC) was calculated as LDF/mean arterial pressure and normalized to maximal (%CVC max) via infusion of 28 mm nitroprusside and local heating to 43 °C.

Results

There was no difference between control (65 ± 5%CVC max) and theophylline (63 ± 5%CVC max) sites. L‐NAME (44 ± 4%CVC max) and theophylline + L‐NAME (32 ± 3%CVC max) sites were significantly attenuated compared to both control and theophylline only sites (P < 0.05), and combined theophylline + L‐NAME sites were significantly reduced compared to L‐NAME only sites (P < 0.05).

Conclusion

These data suggest A1/A2 adenosine receptor activation does not directly contribute to cutaneous active vasodilatation; however, a role for A1/A2 adenosine receptor activation is unmasked when NO synthase is inhibited.
Measurement of Welding Residual Stress in Reactor Components
Authors: DeWald Adrian T. , Hill Michael R.
Published: February 2012

Welding residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to cause significant degradation to the PWSCC resistance of structural materials. The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds due to the complex residual stress distributions that generally result. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on the dissimilar metal weld region of pressurizer relief nozzles removed from the cancelled WNP-3 plant in the United States as part of the NRC/EPRI weld residual stress (WRS) program [1].
Combined CFD and DEM Simulations of Fluid Flow and Heat Transfer in a Pebble Bed Reactor
Authors: Zhao Xiang , Montgomery Trent , Zhang Sijun
Published: February 2012

This paper presents combined computational fluid dynamics (CFD) and discrete element method (DEM) simulations of fluid flow and relevant heat transfer in the pebble bed reactor core. In the pebble bed reactor core, the coolant passes highly complicated flow channels, which are formed by thousands of pebbles in a random way. The random packing structure of pebbles is crucial to CFD simulations results. The realistic packing structure in an entire pebble bed reactor (PBR) is generated by discrete element method (DEM). While in CFD calculations, selection of the turbulence models have great importance in accuracy and capturing the details of the flow features, in our numerical simulations both large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) models are employed to investigate the effects of different turbulence models on gas flow field and relevant heat transfer. The calculations indicate the complex flow structure within the voids between the pebbles.
Finite Element Cracking Analysis of Nuclear Containment Vessels Under External Impacts
Authors: Al-Obaid Y. F.
Published: February 2012

This paper attempts to examine the behavior of nuclear containment vessels under impact loads. Three-dimensional dynamics finite element analysis is proposed. The analysis includes the non-linear behavior of concrete, structural damping and cracking. A combination of solid isoparametric, panel and line elements representing vessel concrete, steel lining, and prestressing tendons or conventional steel, respectively, is suggested. Three-dimensional computer program OBAID is developed which gives time-dependent interactive calculations for stresses, deflections, cracks, reinforcement and suitable wall and dome thicknesses. An existing concrete containment vessels for pressurized water reactor (PWR) is examined under aircraft crash load.
Research Activities to Support SMR Licensing
Authors: Cipiti Ben
Published: February 2012

Small Module Reactors (SMRs) face a number of licensing issues due to the fact that existing regulations were designed for large units. The move toward smaller cores, more reliance on passive safety, and modular construction will require new research to meet existing regulations and possibly regulatory change that would be more appropriate to and cost effective for this technology. The Department of Energy is funding a number of research projects to address SMR licensing issues, including both regulatory framework and design-related issues. Near term priorities include Emergency Planning Zone (EPZ) sizing, operations & staffing, and physical security integration. The recent accident in Japan only heightens the need for thorough analysis of these issues. The purpose of these activities is to provide research support to assist SMR vendors with licensing and to assist the Nuclear Regulatory Commission (NRC) in any data needs that might be required for these unique designs. These research activities will be described with attention to how they will address the SMR licensing needs.
An Experimental Investigation on the Behaviour of Pressure Tube Under Symmetrical and Asymmetrical Heating Conditions in an Indian PHWR
Authors: Yadav Ashwini K. , Kumar Ravi , Gupta Akhilesh , Majumdhar P. , Chatterjee B. , Lele H. G.
Published: February 2012

Thermal behavior of fuel channel under loss of coolant accident (LOCA) is a major concern for nuclear reactor safety. LOCA along with failure of emergency cooling water system (ECC) may leads to mechanical deformations like sagging, ballooning or even release of containment in open atmosphere due to breaching of pressure tube (PT) under certain depressurization and voiding rates. In order to understand the phenomenon an experiment has been carried out using 19 pin fuel element simulator. Main purpose of the experiment was to trace temperature profiles over the pressure tube, calandria tube and clad tubes of Indian Pressurized Heavy Water Reactor (IPHWR) under symmetrical and asymmetrical heat-up conditions. For simulating the fully voided scenario, symmetrical heating of pressure was carried out by injecting 13.2 KW (2% of nominal power) to all the 19 pins and the temperatures of pressure tube, calandria tube and clad tubes were measured. During symmetrical heating the sagging of fuel channel was initiated at 460 °C and the highest temperature attained by PT was 650 °C. The decay heat from clad tubes was dissipated to moderator mainly by radiation and natural convection. The highest temperature of 680 °C was observed over the outer ring of clad tubes of fuel simulator. Again, to simulate partially voided condition, asymmetrical heating of pressure was carried out by supplying 8.0 kW power to upper 8 pins of fuel simulator and temperature profiles were measured. Along the circumference of pressure tube (PT) the highest temperature difference of 320 °C was observed, which highlights the magnitude of thermal stresses and their role in breaching of pressure tube under partially voided conditions. However, the integrity of pressure tube was intact during both symmetrical and asymmetrical heat-up conditions.
Modal Test of Scaled-Down Reactor Internals in SMART Considering the Fluid-Structure Interaction
Authors: Lim Seungho , Ha Kyungrok , Park Kyoung-Su , Park No-Cheol , Park Young-Pil , Jeong Kyeong-Hoon , Park Jin-Seok
Published: February 2012

The System-integrated Modular Advanced ReacTor (SMART) is a small modular integral-type reactor for the seawater desalination and small-scaled power generation under development in Korea. Although the SMART is innovative reactor with a sensible mixture of the proven technology and advanced design features aimed at enhanced safety, there is no valid prototype which can specify the structural dynamic characteristics of reactor internals. Thus, extensive research for the technology verification and standard design approval are in progress. One of them is to perform the dynamic characteristics identification of reactor internals. Especially, it is focused on the added mass effect caused by the fluid-structure interaction because the reactor internals is submerged in the reactor coolant. The extracted dynamic characteristics such as the natural frequencies and the vibratory mode shapes can be used as the basis on further dynamic analysis, for example, seismic analysis and a postulated pipe break analysis.
Seismic Protection of Small Modular Reactors
Authors: Whittaker Andrew , Huang Yin-Nan , Stojadinovic Bozidar
Published: February 2012

The next edition of ASCE Standard 4 will include detailed provisions for the seismic isolation of structures, systems and components in safety-related nuclear structures. The provisions are based on those available in North America for buildings, bridges and other infrastructure but address issues particular to nuclear energy construction and take advantage of recent research funded by federal agencies, including the Nuclear Regulatory Commission and the National Science Foundation. The paper highlights these research products and their incorporation into ASCE Standard 4. Although the focus of the studies and ASCE Standard 4 is analysis of conventional light water reactors of 500+MWe, most of the conclusions are applicable to small modular reactors.
Neutronics Optimization of UN Fuel Pin Assemblies for a Sodium-Cooled, Small Modular Reactor
Authors: Schriener Timothy M. , El-Genk Mohamed S.
Published: February 2012

This paper presents preliminary results of neutronics and thermal-hydraulics design analysis of a sodium cooled, small modular reactor (SMR). The reactor’s nominal thermal power is 150 MWth at sodium inlet and exit temperatures of 630 and 780 K. The reactor core is comprised of three rings of shrouded hexagonal assemblies of 19.8% enriched UN fuel pins and a hexagonal assembly of enriched B4C pins in the central cavity for a coarse reactivity control. The objectives are to provide enough excess reactivity for achieving a refueling cycle > 5 year, maintaining a more even coolant flow in the core assemblies and keeping the peak centerline temperature of UN fuel pins < 1300 K. Fuel assemblies with scalloped shroud walls, 4 rings and 1.942 cm diameter fuel pins with p/d = 1.098 are selected for the reference design of the present SMR. In this design, peak fuel centerline temperature is only 1240 K and the beginning-of-life, cold-clean excess reactivity is $26.67.
Underground Siting of Small Modular Reactors in Bedrock: Rationale, Concepts, and Applications
Authors: Myers Carl W. , Mahar James M.
Published: February 2012

Small modular reactors (SMRs) sited 100 to 300 meters deep in underground chambers constructed in bedrock having favorable geotechnical properties could be both cost effective and provide superior levels of safety and physical security. The bedrock adjacent to and enclosing the reactor chamber would become the functional equivalent of a conventional containment structure, but one with increased margins of safety for design-basis accidents, reduced risks for beyond-design-basis accidents, and a high level of inherent physical protection against external threats. In addition, seismic safety could be enhanced at lower cost because seismic waves are generally attenuated with depth in bedrock. Nominal steel and concrete around the reactor would be required as would sealing of tunnels and other penetrations into the reactor chamber. Nonetheless, the net result in capital cost savings could potentially more than offset the cost of underground excavation. For a hypothetical granitic bedrock site with SMRs at a nominal depth of 100 meters, preliminary excavation cost estimates for single- and four-unit installations constructed by drill-and-blast range from around $90 million to $45 million per reactor, respectively, and for a twelve-unit installation constructed by tunnel boring machine from $25 to $15 million per reactor. Specialized applications for bedrock-sited SMRs include collocation at underground hydropower stations, test and demonstration facility for prototype SMR designs, and deployments in regions at risk of terrorist or military attack.
Metal oxide morphology in argon-assisted glancing angle deposition
Authors: Sorge J. B. , Taschuk M. T. , Wakefield N. G. , Sit J. C. , Brett M. J.
Published: February 2012

Glancing angle deposition (GLAD) is a thin film deposition technique capable of fabricating columnar architectures such as posts, helices, and chevrons with control over nanoscale film features. Argon bombardment during deposition modifies the GLAD process, producing films with new morphologies which have shown promise for sensing and photonic devices. The authors report modification of column tilt angle, film density, and specific surface area for 12 different metal oxide and fluoride film materials deposited using Ar-assisted GLAD. For the vapor flux/ion beam geometry and materials studied here, with increasing argon flux, the column tilt increases, film density increases, and specific surface area decreases. With a better understanding of the nature of property modification and the mechanisms responsible, the Ar-assisted deposition process can be more effectively targeted towards specific applications, including birefringent thin films or photonic crystal square spirals.
Higher Consciousness
Authors: Mashour George A.
Published: February 2012

The psychedelic drug psilocybin uncouples the activity of key brain areas, providing insight into new therapies for psychiatric disorders.