bluuebunny/crossref_metadata_2025 huggingface dataset:
Threatened predator on the equator: multi-point abundance estimates of the tiger Panthera tigris in central Sumatra
Authors: Sunarto  , Kelly Marcella J. , Klenzendorf Sybille , Vaughan Michael R. , Zulfahmi  , Hutajulu M.B. , Parakkasi Karmila
Published: April 2013

Information on spatial and temporal variation in abundance is crucial for effective management of wildlife. Yet abundance estimates for the Critically Endangered Sumatran tiger Panthera tigris sumatrae are lacking from Riau, the province historically believed to hold the largest percentage of this subspecies. Recently, this area has had one of the highest global rates of deforestation. Using camera traps we investigated tiger abundance across peatland, flat lowland, and hilly lowland forest types in the province, and over time, in the newly established Tesso Nilo National Park, central Sumatra. We estimated densities using spatially explicit capture–recapture, calculated with DENSITY, and traditional capture–recapture models, calculated with CAPTURE. With spatially explicit capture–recapture the lowest tiger density (0.34 ± SE 0.24 per 100 km2) was estimated in the hilly lowland forest of Rimbang Baling and the highest (0.87 ± SE 0.33 per 100 km2) in the flat lowland forest of the Park. Repeated surveys in the Park documented densities of 0.63 ± SE 0.28 in 2005 to 0.87 ± SE 0.33 per 100 km2 in 2008. Compared to traditional capture–recapture the spatially explicit capture–recapture approach resulted in estimates 50% lower. Estimates of tiger density from this study were lower than most previous estimates in other parts of Sumatra. High levels of human activity in the area appear to limit tigers. The results of this study, which covered areas and habitat types not previously surveyed, are important for overall population estimates across the island, provide insight into the response of carnivores to habitat loss, and are relevant to the interventions needed to save the tiger.
Fishermen's perceptions of interactions between seabirds and artisanal fisheries in the Chonos archipelago, Chilean Patagonia
Authors: Suazo Cristián G. , Schlatter Roberto P. , Arriagada Aldo M. , Cabezas Luis A. , Ojeda Jaime
Published: April 2013

Interactions between seabirds and commercial fishing activities have been well documented but little information is available regarding the impacts of more traditional fishing practices on seabird populations. We interviewed fishermen, administered questionnaires, and made field-based observations to determine the extent to which artisanal fisheries interact with and affect seabirds in the fjords and channels of the Chonos archipelago in southern Chile. Our surveys indicated a positive perception of seabirds as useful indicators of marine productivity and in their role scavenging fish waste and discards associated with fishing operations. However, the surveys also revealed that fishermen routinely establish seasonal camps for collecting seabird eggs and adults for food or bait and introduce feral predators to seabird breeding colonies on islands. Understanding the traditional practices of fishermen is critical for the future of community-based conservation of the region's marine resources and biodiversity.
Conservation status of the narrow endemic gypsophile Ononis tridentata subsp. crassifolia in southern Spain: effects of habitat disturbance
Authors: Ballesteros Miguel , Foronda Ana , Cañadas Eva María , Peñas Julio , Lorite Juan
Published: April 2013

Ononis tridentata L. subsp. crassifolia (Leguminosae) is a narrow endemic plant restricted to gypsum outcrops in south-east Spain. Its habitat and populations are currently threatened by anthropogenic disturbance. Because of the paucity of information concerning its distribution, abundance and response to disturbance, we assessed its status and evaluated the impacts of quarrying, ploughing, grazing and afforestation. Distribution and population size were estimated by field surveys, censuses and mapping. We measured cover, plant volume, fruit and seed production, seed predation and seedling recruitment to asses any effects of disturbance. The species’ area of occupancy is 1.6 km2 and its extent of occurrence 337 km2, in 29 habitat patches and 16 populations between 705 and 1,125 m altitude, and its population size was estimated to be 531,605. Quarrying, ploughing, overgrazing and afforestation negatively affected the species, in this order. We recommend this subspecies be categorized as Vulnerable on the IUCN Red List. A species recovery plan is required, and the ecological restoration of altered areas would mitigate negative effects on the species and improve the overall conservation of gypsum habitats.
Change in cannabis use, clinical symptoms and social functioning among patients with first-episode psychosis: a 5-year follow-up study of patients in the OPUS trial
Authors: Clausen L. , Hjorthøj C. R. , Thorup A. , Jeppesen P. , Petersen L. , Bertelsen M. , Nordentoft M.
Published: April 2013

Background

Several studies indicate that cannabis use among patients with psychotic disorders is associated with worse outcome, but only a few studies have controlled for baseline condition and medication.

Method

At 5-year follow-up, interviews were carried out with 314 first-episode psychosis patients included in the OPUS trial. The patients included were in the age range of 18 to 45 years old and 59% were male. Cannabis use was extracted from the Schedule for Clinical Assessment in Neuropsychiatry. At follow-up, the patients were divided into different groups according to the variable cannabis use: abstainers, stoppers, starters and continuers. Psychotic, negative and disorganized dimensions (ranging from zero to five) were calculated for each of the four groups based on the Schedule for the Assessment of Positive and Negative Symptoms in Schizophrenia.

Results

Cannabis users were younger (24.6 years v. 27.4 years, p < 0.001) and had a lower level of education. At the 5-year follow-up, users of cannabis had higher scores on the psychotic dimension [difference 0.97, 95% confidence interval (CI) 0.41–1.53, p = 0.001] and lower levels of the Global Assessment of Functioning (difference 8.26, 95% CI 2.13–14.39, p = 0.01). Those who stopped using cannabis between entry and 5-year follow-up had a significantly lower level of psychotic symptoms at 5-year follow-up even after controlling for baseline level of psychotic symptoms and for insufficient antipsychotic medication (adjusted difference in psychotic dimension –1.04, 95% CI –1.77 to –0.31, p = 0.006).

Conclusions

Continuous cannabis use was associated with higher levels of psychotic symptoms after 5 years, and this association was only partly explained by insufficient antipsychotic medication.
Lifetime prevalence and co-morbidity of externalizing disorders and depression in prospective assessment
Authors: Hamdi N. R. , Iacono W. G.
Published: April 2013

Background

Epidemiological research is believed to underestimate the lifetime prevalence of mental illness due to recall failure and a lack of rapport between researchers and participants.

Method

In this prospective study, we examined lifetime prevalence and co-morbidity rates of substance use disorders, antisocial personality disorder (ASPD) and major depressive disorder (MDD) in a representative, statewide Minnesota sample (n = 1252) assessed four times between the ages of 17 and 29 years with very low attrition.

Results

Lifetime prevalence rates of all disorders more than doubled between the ages of 17 and 29 years in both men and women, and our prospective rates at the age of 29 years were consistently higher than rates from leading epidemiological surveys. Although there was some variation, the general trend was for lifetime co-morbidity to increase between the ages of 17 and 29 years, and this trend was significant for MDD–alcohol dependence, MDD–nicotine dependence, and ASPD–nicotine dependence.

Conclusions

Overall, our results show that emerging adulthood is a high-risk period for the development of mental illness, with increases in the lifetime prevalence and co-morbidity of mental disorders during this time. More than a quarter of individuals had met criteria for MDD and over a fifth had experienced alcohol dependence by the age of 29 years, indicating that mental illness is more common than is estimated in cross-sectional mental health surveys. These findings have important implications for the measurement of economic burden, resource allocation toward mental health services and research, advocacy organizations for the mentally ill, and etiological theories of mental disorders.
Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy
Authors: Blanton Thomas N. , Majumdar Debasis
Published: April 2013

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.
Antimicrobial resistance patterns and genotypes ofSalmonella entericaserovar Hadar strains associated with human infections in Switzerland, 2005–2010
Authors: CERNELA N. , NÜESCH-INDERBINEN M. , HÄCHLER H. , STEPHAN R.
Published: April 2013

SalmonellaHadar ranks in the top ten serovars reported from humans in Switzerland. In this study, all 64S.Hadar strains isolated from different patients from 2005 to 2010 in Switzerland were characterized by (i) assessing phenotypic antimicrobial resistance profiles using the disk diffusion method and (ii) by genotyping using pulsed-field gel electrophoresis (PFGE) in order to evaluate the relationship of the strains. The annual incidences varied between 0·32/100 000 in 2005 (highest incidence) and 0·065/100 000 in 2007 (lowest incidence). In total 71·8% of the isolates were resistant to nalidixic acid. Although 40·6% of the strains were resistant to theβ-lactam antibiotic ampicillin, they remained susceptible to the third-generation cephalosporin cefotaxime. Genotyping revealed a primary cluster consisting of 42 strains, sharing a similarity of >92%, with a subcluster of 18 strains with indistinguishable patterns. Resistance profiles allowed further differentiation within this subcluster providing a link of two strains to an outbreak in Spain.
Marginal marine depositional setting and correlation of the Devonian Sperm Bluff Formation (Taylor Group), southern Victoria Land, Antarctica
Authors: Savage Jeni E. , Bradshaw Margaret A. , Bassett Kari N.
Published: April 2013

Analysis of conglomerates and sandstones of the Sperm Bluff Formation at the base of the Taylor Group (Devonian) between the Mackay Glacier and Bull Pass provides new insights into the nature of initial coarse-grained deposition on basement along the northern side of the McMurdo sedimentary basin. Six lithofacies are recognized in the Sperm Bluff Formation: conglomerate lithofacies, pebbly sandstone lithofacies, cross-bedded sandstone lithofacies, low-angle cross-stratified sandstone lithofacies, bioturbated sandstone lithofacies and interbedded siltstone/sandstone lithofacies. Sedimentary environments ranged from wave-dominated delta, estuary or lagoon to shoreface and inner shelf. The assemblage is thought to reflect changes in sea level. Rhyolite is the most abundant clast type in the coarse lithofacies, but is unknown in outcrop in southern Victoria Land. The rhyolites correlate in age and geochemistry with Cambrian granites in the basement. Coarse beds also contain numerous quartzite clasts, probably derived from the late Precambrian Skelton Group. Palaeocurrents on Mount Suess indicate a strong unimodal flow to the west, but other sites show polymodal palaeoflow. The Sperm Bluff Formation is correlated with Terra Cotta Siltstone, New Mountain Sandstone and Altar Mountain formations based on the lithology of sandstones and their ichnology. A northward onlap during the Early Devonian is indicated.
Proteomic analysis of the enhancement of seed vigour in osmoprimed alfalfa seeds germinated under salinity stress
Authors: Yacoubi Rafika , Job Claudette , Belghazi Maya , Chaibi Wided , Job Dominique
Published: April 2013

Alfalfa (Medicago sativaL.) yield is severely compromised by soil salinity, especially at the level of seedling establishment. This question was addressed by proteomics to decipher whether specific changes in protein accumulation correlate with germination performance of alfalfa seeds submitted to a salinity stress as obtained by imbibing seeds in the presence of NaCl. This study used alfalfa seeds submitted to an osmopriming invigoration treatment that proved very efficient in counteracting the negative effect of salinity stress on germination performance. Comparative proteomic analyses disclosed 94 proteins commonly characterizing the response of both the untreated control and osmoprimed seeds to the experimental salinity stress. Remarkably, many of them, representing 84 proteins, showed contrasting accumulation patterns when comparing the untreated control and osmoprimed seeds submitted to the same salt stress. Thus numerous changes observed in the proteome of the untreated control seeds imbibed in the presence of salt, and presumably accounting for the loss in seed vigour associated with salinity stress, can be substantially reversed in osmoprimed seeds undergoing this stress. These data therefore provide a biochemical understanding of the increase in seed vigour generally observed with primed seeds.
N-acetyl-cysteine prevents toxic oxidative effects induced by IFN-α in human neurons
Authors: Alboni Silvia , Gibellini Lara , Montanari Claudia , Benatti Cristina , Benatti Stefania , Tascedda Fabio , Brunello Nicoletta , Cossarizza Andrea , Pariante Carmine M.
Published: April 2013

Currently IFN-α is widely used for effective treatment of viral infections and several malignancies. However, IFN-α can cause neuropsychiatric disturbances and mental impairments, including fatigue, insomnia, depression, irritability and cognitive deficits. Molecular and cellular mechanisms leading to such side-effects are still poorly understood. Neurons seem to be an important target in mediating cellular effects induced by exposure to this cytokine, but so far little is known about IFN-α-induced effects on these cells. We have investigated the ability of IFN-α (2–100 ng/ml) to induce damage and toxicity to the human neuroblastoma SH-SY5Y cell line, commonly used for studying such phenomena, and the mechanisms underlying these effects. After 24 h treatment, IFN-α increased mitochondrial activity, whereas cell density was reduced in a dose- and time-dependent manner. This effect did not depend on reduced cell proliferation, but rather the activation of apoptosis, as revealed by an increased Bax:Bcl-2 mRNA ratio after 72-h IFN-α exposure. At this time-point, IFN-α also reduced the expression of the brain-derived neurotrophic factor gene, and induced an increase in reactive oxygen species (ROS). A co-treatment with N-acetyl-cysteine (NAC; 5 mm), a potent antioxidant and mitochondrial modulator, was able to counteract all of these IFN-α-induced effects. These findings demonstrated that IFN-α induces neurotoxicity and apoptosis that is, in part, very likely due to mitochondrial damages and production of ROS. We suggest that NAC, already tested for the treatment of psychiatric disorders, may be useful to prevent IFN-α-induced central side-effects in a safe and effective way.
Sex-specific associations of maternal prenatal testosterone levels with birth weight and weight gain in infancy
Authors: Voegtline K. M. , Costigan K. A. , Kivlighan K. T. , Henderson J. L. , DiPietro J. A.
Published: April 2013

Associations between maternal salivary testosterone at 36 weeks’ gestation with birth weight and infant weight gain through 6 months of age were examined in a group of 49 healthy, pregnant women and their offspring. The diurnal decline of maternal testosterone was conserved in late pregnancy, and levels showed significant day-to-day stability. Elevated maternal morning testosterone level was associated with lower birth weight Z-scores adjusted for gestational age and sex, and greater infant weight gain between birth and 6 months. Although maternal testosterone levels did not differ by fetal sex, relations were sex-specific such that maternal testosterone had a significant impact on weight for male infants; among female infants associations were nonsignificant. Results highlight the opposing influence of maternal androgens during pregnancy on decreased growth in utero and accelerated postnatal weight gain.
Long-Range Temporal Correlations in Resting EEG
Authors: Bornas Xavier , Noguera Miquel , Balle Maria , Morillas-Romero Alfonso , Aguayo-Siquier Blanca , Tortella-Feliu Miquel , Llabrés Jordi
Published: April 2013

Several studies have reported differences in long-range temporal correlations of EEG oscillations between depressed and nondepressed individuals. The question remains unsolved whether these differences are also linked to negative emotion regulation strategies that configure a depressive style. In this study we applied detrended fluctuation analysis to the amplitude envelope of broad band and narrow band (theta and alpha) spontaneous EEG oscillations of a sample (N = 56) of young nondepressed adults to whom several emotion regulation and depression questionnaires were administered. Linear positive correlations between the scaling exponents of both broad band and theta band oscillations and negative emotion regulation strategies and depression scores were found. These results suggest that previously found differences between depressed and nondepressed individuals may exist before depression manifests, as differences could be linked to a negative emotion regulation style that in some cases could lead to the development of a depressive disorder.
Indirect and suboptimal control of gene expression is widespread in bacteria
Authors: Price Morgan N , Deutschbauer Adam M , Skerker Jeffrey M , Wetmore Kelly M , Ruths Troy , Mar Jordan S , Kuehl Jennifer V , Shao Wenjun , Arkin Adam P
Published: April 2013

Gene regulation in bacteria is usually described as an adaptive response to an environmental change so that genes are expressed when they are required. We instead propose that most genes are under indirect control: their expression responds to signal(s) that are not directly related to the genes’ function. Indirect control should perform poorly in artificial conditions, and we show that gene regulation is often maladaptive in the laboratory. In Shewanella oneidensis MR‐1, 24% of genes are detrimental to fitness in some conditions, and detrimental genes tend to be highly expressed instead of being repressed when not needed. In diverse bacteria, there is little correlation between when genes are important for optimal growth or fitness and when those genes are upregulated. Two common types of indirect control are constitutive expression and regulation by growth rate; these occur for genes with diverse functions and often seem to be suboptimal. Because genes that have closely related functions can have dissimilar expression patterns, regulation may be suboptimal in the wild as well as in the laboratory.
Xentry, a new class of cell-penetrating peptide uniquely equipped for delivery of drugs
Authors: Montrose Kristopher , Yang Yi , Sun Xueying , Wiles Siouxsie , Krissansen Geoffrey W.
Published: April 2013

Here we describe an entirely new class of cell-penetrating peptide (CPP) represented by the short peptide Xentry (LCLRPVG) derived from an N-terminal region of the X-protein of the hepatitis B virus. Xentry permeates adherent cells using syndecan-4 as a portal for entry and is uniquely restricted from entering syndecan-deficient, non-adherent cells, such as resting blood cells. Intravenous injection of Xentry alone or conjugated to β-galactosidase led to its delivery to most tissues in mice, except circulating blood cells. There was a predilection for uptake by epithelia. Anti-B-raf antibodies and siRNAs linked to Xentry were capable of killing B-raf-dependent melanoma cells. Xentry represents a new class of CPP with properties that are potentially advantageous for life science and therapeutic applications.
Aggregation of amyloids in a cellular context: modelling and experiment
Authors: Friedman Ran
Published: April 2013

Amyloid-related diseases are a group of illnesses in which an abnormal accumulation of proteins into fibrillar structures is evident. Results from a wide range of studies, ranging from identification of amyloid-β dimers in the brain to biophysical characterization of the interactions between amyloidogenic peptides and lipid membranes during fibril growth shed light on the initial events which take place during amyloid aggregation. Accounts of fibril disaggregation and formation of globular aggregates due to interactions with lipids or fatty acids further demonstrate the complexity of the aggregation process and the difficulty to treat amyloid-related diseases. There is an inherent difficulty in generalizing from studies of aggregation in vitro, but the involvement of too many cellular components limits the ability to follow amyloid aggregation in a cellular (or extracellular) context. Fortunately, the development of experimental methods to generate stable globular aggregates suggests new means of studying the molecular events associated with amyloid aggregation. Furthermore, simulation studies enable deeper understanding of the experimental results and provide useful predictions that can be tested in the laboratory. Computer simulations can nowadays provide molecular or even atomistic details that are experimentally not available or very difficult to obtain. In the present review, recent developments on modelling and experiments of amyloid aggregation are reviewed, and an integrative account on how isolated interactions (as observed in vitro and in silico) combine during the course of amyloid-related diseases is presented. Finally, it is argued that an integrative approach is necessary to get a better understanding of the protein aggregation process.
A critical role for citrate metabolism in LPS signalling
Authors: O'Neill Luke A. J.
Published: April 2013

Macrophage activation is a key event in the inflammatory process, since these cells produce a range of pro-inflammatory molecules, including ROS (reactive oxygen species), prostaglandins, cytokines and nitric oxide. These factors promote inflammation by causing vasodilation and recruitment of neutrophils, monocytes and lymphocytes, which ultimately clear infection and repair damaged tissue. One of the most potent macrophage activators is the Gram-negative-derived bacterial cell wall component LPS (lipopolysaccharide). LPS is sensed by TLR4 (Toll-like receptor 4) and triggers highly complex signalling pathways that culminate in activation of transcription factors such as NF-κB (nuclear factor κB), which in turn increases transcription of genes encoding proteins such as COX2 (cyclo-oxygenase 2, a key enzyme in prostaglandin biosynthesis), nitric oxide synthase and cytokines such as TNF (tumour necrosis factor). Recently, a role for metabolic pathways in the regulation of LPS signalling has become a focus of research in inflammation. A notable example is LPS promoting the so-called Warburg effect – aerobic glycolysis. This allows for an up-regulation in ATP production, and also for the production of biosynthetic intermediates to meet the demands of the activated macrophages. In this issue of the Biochemical Journal, Infantino et al. add a new finding to the role of metabolism in LPS action. They demonstrate a requirement for the mitochondrial citrate carrier in the induction of ROS, nitric oxide and prostaglandins by LPS. The knockdown of the carrier with siRNA (small interfering RNA), or the use of an inhibitor BTA (benzene-1,2,3-tricarboxylate), abolishes these responses. Although no mechanism is provided, the authors speculate that acetyl-CoA is synthesized from citrate in the cytosol. The acetyl-CoA generated could be required for phospholipid biosynthesis, the phospholipids being the source of arachidonic acid for prostaglandin production. Another product of citrate metabolism, oxaloacetate, will indirectly generate nitric oxide and ROS. This finding places citrate, transported from the mitochondria, as a key player in LPS signalling, at least for ROS, nitric oxide and prostaglandin production. This somewhat unexpected role for citrate in LPS action adds to a growing literature on the role for metabolism in the regulation of signalling in inflammation.
SUMOylation is a regulator of the translocation of Jak2 between nucleus and cytosol
Authors: Sedek Magdalena , Strous Ger J.
Published: April 2013

Jak2 (Janus kinase 2) initiates the signal transduction of many cytokine receptors. We discovered that Jak2 is SUMOylated on multiple lysine residues by SUMO2/3 (small ubiquitin-related modifier 2/3) chains. Analysis of Jak2 mutants revealed that Jak2 SUMOylation depends on the presence of an active catalytic site. We used the GH (growth hormone) receptor to study the physiological relevance of Jak2 SUMOylation. Both GH stimulation and several other environmental stressors increased Jak2 SUMOylation. Cell fractionation showed that SUMOylated Jak2 is mainly present in the nucleus. The constitutively active V617F Jak2 mutant, implicated in myeloproliferative diseases, was highly SUMOylated in the absence of stimuli. These data provide evidence that Jak2 SUMOylation controls Jak2 shuttling between cytoplasm and nucleus.
Mutations in Tyr808 reveal a potential auto-inhibitory mechanism of guanylate cyclase-B regulation
Authors: Katafuchi Takeshi
Published: April 2013

In this study, Tyr808 in GC-B (guanylate cyclase-B), a receptor of the CNP (C-type natriuretic peptide), has been shown to be a critical regulator of GC-B activity. In searching for phosphorylation sites that could account for suppression of GC-B activity by S1P (sphingosine-1-phosphate), mutations were introduced into several candidate serine/threonine and tyrosine residues. Although no novel phosphorylation sites that influenced the suppression of GC-B were identified, experiments revealed that mutations in Tyr808 markedly enhanced GC-B activity. CNP-stimulated activities of the Y808F and Y808A mutants were greater than 30-fold and 70-fold higher, respectively, than that of WT (wild-type) GC-B. The Y808E and Y808S mutants were constitutively active, expressing 270-fold higher activity without CNP stimulation than WT GC-B. Those mutations also influenced the sensitivity of GC-B to a variety of inhibitors, including S1P, Na3VO4 and PMA. Y808A, Y808E and Y808S mutations markedly weakened S1P- and Na3VO4-dependent suppression of GC-B activity, whereas Y808E and Y808S mutations rather elevated cGMP production. Tyr808 is conserved in all membrane-bound GCs and located in the niche domain showing sequence similarity to a partial fragment of the HNOBA (haem nitric oxide binding associated) domain, which is found in soluble GC and in bacterial haem-binding kinases. This finding provides new insight into the activation mechanism of GCs.
Effect of dielectric/organic interface properties on charge transport in organic thin film transistors
Authors: Rahimi Ronak , Kuchibhatla S. , Korakakis D.
Published: April 2013

Charge carrier transport within the organic thin films as well as charge carrier injection between organic layers and organic/inorganic materials such as metal or dielectric layers are crucial factors in determining the efficiency of organic electronic devices. These parameters rely largely on the molecular structure, morphology, and ordering of the organic thin films. Therefore, a profound understanding of the structure of organic materials as well as the properties of the interfacial layers is crucial to enhance the performance of the device. To achieve this fact, structure and morphology of PTCDI-C8 and pentacene thin films on Lithium Fluoride (LiF) have been studied using X-ray reflectivity technique. These films have been integrated into organic thin film transistors (OTFTs) to investigate their transport properties. The structural characterization revealed that the PTCDI-C8 films form an ordered structure on the LiF dielectric layer. Devices with LiF/PTCDI-C8 bilayer exhibit about one order of magnitude higher output current (Ids) at a constant drain-source voltage (Vds) compared to the devices with LiF/pentacene bilayer. The observed differences in the electrical characteristics of these devices can be attributed to the effects of the dielectric/organic interface and the molecular structure of the organic layers. The results of this study present the importance of the dielectric/organic interfaces in the performance of OTFTs.
Why there is no Efimov effect for four bosons and related results on the finiteness of the discrete spectrum
Authors: Gridnev Dmitry K.
Published: April 2013

We consider a system of N pairwise interacting particles described by the Hamiltonian H, where σess(H) = [0, ∞) and none of the particle pairs has a zero energy resonance. The pair potentials are allowed to take both signs and obey certain restrictions regarding the fall off. It is proved that if N ⩾ 4 and none of the Hamiltonians corresponding to the subsystems containing N − 2 or less particles has an eigenvalue equal to zero then H has a finite number of negative energy bound states. This result provides a positive proof to a long-standing conjecture of Amado and Greenwood stating that four bosons with an empty negative continuous spectrum have at most a finite number of negative energy bound states. Additionally, we give a short proof to the theorem of Vugal'ter and Zhislin on the finiteness of the discrete spectrum and pose a conjecture regarding the existence of the “true” four-body Efimov effect.
Weak ferromagnetic behavior of BiFeO3 at low temperature
Authors: Han Seungkyu , Sung Kim Chul
Published: April 2013

Polycrystalline BiFeO3, having a spherical shape with a diameter of about 78 μm, has been synthesized by low-temperature hydrothermal method. The observed Raman and x-ray photo electron spectroscopy (XPS) spectra of the sample show the spectra of typical single-phased BiFeO3, and the x-ray diffractometry (XRD) measurement further confirmed that the synthesized sample is single phase. The value of isomer shift from Mössbauer analysis indicates the Fe3+ ionic state without Fe2+ ionic state as observed from XPS measurement. The experimentally measured M-H curves show antiferromagnetic behavior at 295 K and weak ferromagnetic behavior at 4.2 K. The appearance of two different magnetic behaviors is due to the fact that the antiferromagnetic coupling becomes weak because of the presence of two distorted octahedral sites. Since the effect of the lattice distortion strongly depends on the thermal agitation effect, the weak ferromagnetic behavior can be observed only at 4.2 K. The detailed Mössbauer spectra analysis result confirms the existence of two distortion octahedral sites, which is in an agreement with XRD results.
Ultrafast ultrasonic imaging coupled to rheometry: Principle and illustration
Authors: Gallot Thomas , Perge Christophe , Grenard Vincent , Fardin Marc-Antoine , Taberlet Nicolas , Manneville Sébastien
Published: April 2013

We describe a technique coupling standard rheology and ultrasonic imaging with promising applications to characterization of soft materials under shear. Plane wave imaging using an ultrafast scanner allows to follow the local dynamics of fluids sheared between two concentric cylinders with frame rates as high as 10 000 images per second, while simultaneously monitoring the shear rate, shear stress, and viscosity as a function of time. The capacities of this “rheo-ultrasound” instrument are illustrated on two examples: (i) the classical case of the Taylor-Couette instability in a simple viscous fluid and (ii) the unstable shear-banded flow of a non-Newtonian wormlike micellar solution.
Comment on “Elasticity of flexible and semiflexible polymers with extensible bonds in the Gibbs and Helmholtz ensembles” [J. Chem. Phys. 136, 154906 (2012)]
Authors: Neumann Richard M.
Published: April 2013

In this Comment, we point out that (i) Manca et al. err in their finding that the force law obtained for a single polymer chain in the thermodynamic limit using the Helmholtz ensemble is identical to that obtained using the Gibbs ensemble in all force regimes, and (ii) the perpetuation of this misunderstanding can have serious consequences when interpreting the results of polymer-stretching experiments in the weak-force region.
Response to “Comment on ‘Elasticity of flexible and semiflexible polymers with extensible bonds in the Gibbs and Helmholtz ensembles”’ [J. Chem. Phys. 138, 157101 (2013)]
Authors: Manca Fabio , Giordano Stefano , Palla Pier Luca , Cleri Fabrizio , Colombo Luciano
Published: April 2013

Two different statistical ensembles can be considered for extending a single polymer chain: the Gibbs (or isotensional) ensemble characterized by a deterministic force applied to the free end of the chain (the other being fixed in a given reference frame), and the Helmholtz (or isometric) ensemble obtained with both the ends of the polymers tethered at two different points of the space. When the thermodynamic limit is satisfied (the number of monomers approaches infinity) these ensembles are equivalent from the thermodynamic point of view: it means that the constitutive equations (vector force-extension relations) assume the same mathematical form in both isotensional and isometric conditions. Equivalently, the Helmholtz and Gibbs free energies are linked by a Legendre transform. We explain that this general result is coherent with some “forms of inequivalence” observed by defining different average values of force and position vectors. However, this fact does not indicate thermodynamic inequivalence as largely discussed in the present Response.
Glass-forming ability of Al-Co alloy under rapid annealing
Authors: Liu Chengyan , Wang Fei , Rao Fengfei , Hou Yasen , Wang Songyou , Sun Qiang , Jia Yu
Published: April 2013

By using molecular dynamics method, transition of Al-Co alloy from liquid to amorphous structure has been investigated theoretically. The structure parameters, pair distribution functions (PDF), bond-angle distribution functions, and Voronoi polyhedra analysis are adopted as indicators of the evolution of clusters in Al-Co alloy during the rapid cooling processes. We found that below transition temperature, the second peak of PDF curves splits into two pronounced subpeaks, while at all temperature the PDF curves gradually converge to unity at large distance. This indicates that the amorphous alloy exhibits local ordering structure and has no long-range ordering. Besides, the bond-angle distribution function predicts that the degrees in the vicinity of 63.4 and 113.4 are dominated in the system during the processes of rapid annealing, which represent that the icosahedral structures are dominant. Together with the cluster structures observed in simulation, Voronoi polyhedra analysis shows that the most popular polyhedron is full icosahedron with the Voronoi index 〈0, 0, 12, 0〉, which is always predominant in bulk metallic glass (MG) formers with excellent glass forming ability. Our studies indicated that doping of cobalt atoms in the Al-based alloy should have a better capacity of forming MG.
Acoustic nonlinearity and cumulative plastic shear strain in cyclically loaded metals
Authors: Cantrell John H. , Yost William T.
Published: April 2013

Cyclic loading leads to microstructural changes in metals that result in substantial increases in the material nonlinearity. Two quite distinct approaches for quantifying the nonlinearity via a material nonlinearity parameter assessed directly from acoustic harmonic generation measurements have emerged—the Cantrell model and the model of Kim et al. The Cantrell model quantifies the nonlinearity in terms of lattice anharmonicity, dislocation plasticity, and crack growth as independent sources of nonlinearity arising from the accumulated plastic shear strain. The approach of Kim et al. links the cumulative plastic shear strain directly to a change in the third-order elastic constants of the material. We show that although the model of Kim et al. has the advantage of expediency, the Cantrell model reflects much more accurately the dependence of the nonlinearity parameter on the state of fatigue.
Acoustic wave localization in one-dimensional Fibonacci phononic structures with mirror symmetry
Authors: Hladky-Hennion A. C. , Vasseur J. O. , Degraeve S. , Granger C. , de Billy M.
Published: April 2013

This paper reports on numerical and experimental results of acoustic transmission spectra of bead chains with symmetric and asymmetric Fibonacci-like structures. As a matter of comparison, perfect periodic acoustic waveguide structures are also examined. This study shows that Fibonacci structures with mirror symmetry can exhibit localized modes with higher amplitude, due to resonant transmission induced by the presence of dimers inside the 1D structure. A good agreement is observed between the theoretical predictions and the experimental power spectra.
Highly efficient bulk heterojunction photovoltaic cell based on tris[4-(5-phenylthiophen-2-yl)phenyl]amine and C70 combined with optimized electron transport layer
Authors: Zheng Yan-qiong , Potscavage William J. , Komino Takeshi , Adachi Chihaya
Published: April 2013

Efficient bulk heterojunction (BHJ) photovoltaic cells (PVs) based on 5 wt. % donors and C70 were fabricated. Tris[4-(5-phenylthiophen-2-yl)phenyl]-amine (TPTPA)-based BHJ PVs show higher power conversion efficiency (ηPCE) than aluminum phthalocyanine chloride-based BHJ PVs. Although the absorption of AlPcCl is complementary to that of C70, TPTPA's high hole mobility and symmetrical molecular structure are likely to be crucial contributing factors to the higher ηPCE. Phase separation occurs in the 5%-TPTPA blend. The device was optimized via replacement of the bathocuproine buffer by a combination of 3,4,9,10-perylenetetracarboxylic bis-benzimidazole and bathocuproine. ηPCE of 5.96% is achieved because of the decreased series resistance.
Early quality assessment lessens pheromone specificity in a moth
Authors: Kárpáti Zsolt , Tasin Marco , Cardé Ring T. , Dekker Teun
Published: April 2013

Pheromone orientation in moths is an exemplar of olfactory acuity. To avoid heterospecific mating, males respond to female-produced blends with high specificity and temporal resolution. A finely tuned sensory to projection neuron network secures specificity, and this network is thought to assess pheromone quality continually during orientation. We tested whether male moths do indeed evaluate each pheromone encounter and surprisingly found that male European corn borer moths instead generalize across successive encounters. Although initially highly ratio specific, once “locked on” to the pheromone plume the acceptable ratio can vary widely, and even unattractive blends can become attractive. We further found that this “mental shortcut” may be a consequence of the fact that sensory neurons exposed to frequent encounters do not reliably encode blend ratios. Neurons tuned to either of the two pheromone components adapt differentially in plumes containing the preferred blend ratio (97:3) and cause the olfactory sensory signal to “evolve,” even in narrowly tuned pheromonal circuits. However, apparently the brain interprets these shifting signals as invariant “gestalts.” Generalization in pheromone perception may mitigate stabilizing selection and allow introgression between sympatric strains, such as in the European corn borer, that otherwise appear isolated by pheromonal differences. Generalization may also be important in responses to general odorants, as circuits underlying these display vast sensitivity differences, complex interactions, and temporal intricacies.
High-performance hollow sulfur nanostructured battery cathode through a scalable, room temperature, one-step, bottom-up approach
Authors: Li Weiyang , Zheng Guangyuan , Yang Yuan , Seh Zhi Wei , Liu Nian , Cui Yi
Published: April 2013

Sulfur is an exciting cathode material with high specific capacity of 1,673 mAh/g, more than five times the theoretical limits of its transition metal oxides counterpart. However, successful applications of sulfur cathode have been impeded by rapid capacity fading caused by multiple mechanisms, including large volume expansion during lithiation, dissolution of intermediate polysulfides, and low ionic/electronic conductivity. Tackling the sulfur cathode problems requires a multifaceted approach, which can simultaneously address the challenges mentioned above. Herein, we present a scalable, room temperature, one-step, bottom-up approach to fabricate monodisperse polymer (polyvinylpyrrolidone)-encapsulated hollow sulfur nanospheres for sulfur cathode, allowing unprecedented control over electrode design from nanoscale to macroscale. We demonstrate high specific discharge capacities at different current rates (1,179, 1,018, and 990 mAh/g at C/10, C/5, and C/2, respectively) and excellent capacity retention of 77.6% (at C/5) and 73.4% (at C/2) after 300 and 500 cycles, respectively. Over a long-term cycling of 1,000 cycles at C/2, a capacity decay as low as 0.046% per cycle and an average coulombic efficiency of 98.5% was achieved. In addition, a simple modification on the sulfur nanosphere surface with a layer of conducting polymer, poly(3,4-ethylenedioxythiophene), allows the sulfur cathode to achieve excellent high-rate capability, showing a high reversible capacity of 849 and 610 mAh/g at 2C and 4C, respectively.
Critical role for miR-181a/b-1 in agonist selection of invariant natural killer T cells
Authors: Ziętara Natalia , Łyszkiewicz Marcin , Witzlau Katrin , Naumann Ronald , Hurwitz Robert , Langemeier Jörg , Bohne Jens , Sandrock Inga , Ballmaier Matthias , Weiss Siegfried , Prinz Immo , Krueger Andreas
Published: April 2013

T-cell receptor (TCR) signal strength determines selection and lineage fate at the CD4+CD8+double-positive stage of intrathymic T-cell development. Members of the miR-181 family constitute the most abundantly expressed microRNA at this stage of T-cell development. Here we show that deletion of miR-181a/b-1 reduced the responsiveness of double-positive thymocytes to TCR signals and virtually abrogated early invariant natural killer T (iNKT) cell development, resulting in a dramatic reduction in iNKT cell numbers in thymus as well as in the periphery. Increased concentrations of agonist ligand rescued iNKT cell development in miR-181a/b-1−/−mice. Our results define a critical role of miR-181a/b-1 in early iNKT cell development and show that miR-181a/b-1 sets a TCR signaling threshold for agonist selection.
In vitro activity of the nisin dehydratase NisB
Authors: Garg Neha , Salazar-Ocampo Luis M. A. , van der Donk Wilfred A.
Published: April 2013

The biosynthesis of several classes of ribosomally synthesized and posttranslationally modified peptides involves dehydration of serine and threonine residues. For class I lantibiotics, thiopeptides, and goadsporin, this dehydration is catalyzed by lanthionine biosynthetic enzyme B (LanB) or LanB-like proteins. Although LanB proteins have been studied since 1992, in vitro reconstitution of their dehydration activity has been elusive. We show here the in vitro activity of the dehydratase involved in the biosynthesis of the food preservative nisin (NisB). In vitro, NisB dehydrated its substrate peptide NisA eight times in the presence of glutamate, ATP, Mg
2+
, and the ribosomal/membrane fraction of bacterial cell extract. Mutation of 23 highly conserved residues of NisB identified a number of amino acids that are essential for dehydration activity. In addition, these mutagenesis studies identified three mutants, R786A, R826A, and H961A, that result in multiple glutamylations of the NisA substrate. Glutamylation was observed during both
Escherichia coli
coexpression of NisA with these mutants and in vitro assays. Treatment of the glutamylated substrate with WT NisB results in dehydrated NisA, suggesting that the glutamylated peptide is an intermediate in dehydration. Collectively, these studies suggest that dehydration involves glutamylation of the side chains of Ser and Thr followed by elimination. The latter step has precedent in the virginiamycin resistance protein virginiamycin B lyase. These studies will facilitate investigation of other LanB proteins involved in the biosynthesis of lantibiotics, thiopeptides, and goadsporin.
Domain cooperativity in the β1asubunit is essential for dihydropyridine receptor voltage sensing in skeletal muscle
Authors: Dayal Anamika , Bhat Vinayakumar , Franzini-Armstrong Clara , Grabner Manfred
Published: April 2013

The dihydropyridine receptor (DHPR) β1asubunit is crucial for enhancement of DHPR triad expression, assembly of DHPRs in tetrads, and elicitation of DHPRα1Scharge movement—the three prerequisites of skeletal muscle excitation–contraction coupling. Despite the ability to fully target α1Sinto triadic junctions and tetradic arrays, the neuronal isoform β3was unable to restore considerable charge movement (measure of α1Svoltage sensing) upon expression in β1-null zebrafishrelaxedmyotubes, unlike the other three vertebrate β-isoforms (β1a, β2a, and β4). Thus, we used β3for chimerization with β1ato investigate whether any of the five distinct molecular regions of β1ais dominantly involved in inducing the voltage-sensing function of α1S. Surprisingly, systematic domain swapping between β1aand β3revealed a pivotal role of the src homology 3 (SH3) domain and C terminus of β1ain charge movement restoration. More interestingly, β1aSH3 domain and C terminus, when simultaneously engineered into β3sequence background, were able to fully restore charge movement together with proper intracellular Ca2+release, suggesting cooperativity of these two domains in induction of the α1Svoltage-sensing function in skeletal muscle excitation–contraction coupling. Furthermore, substitution of a proline by alanine in the putative SH3-binding polyproline motif in the proximal C terminus of β1a(also of β2aand β4) fully obstructed α1Scharge movement. Consequently, we postulate a model according to which β subunits, probably via the SH3–C-terminal polyproline interaction, adapt a discrete conformation required to modify the α1Sconformation apt for voltage sensing in skeletal muscle.
Structural basis for encapsidation of genomic RNA by La Crosse Orthobunyavirus nucleoprotein
Authors: Reguera Juan , Malet Hélène , Weber Friedemann , Cusack Stephen
Published: April 2013

The nucleoprotein (NP) of segmented negative-strand RNA viruses such as Orthomyxo-, Arena-, and Bunyaviruses coats the genomic viral RNA and together with the polymerase forms ribonucleoprotein particles (RNPs), which are both the template for replication and transcription and are packaged into new virions. Here we describe the crystal structure of La Crosse Orthobunyavirus NP both RNA free and a tetrameric form with single-stranded RNA bound. La Crosse Orthobunyavirus NP is a largely helical protein with a fold distinct from other bunyavirus genera NPs. It binds 11 RNA nucleotides in the positively charged groove between its two lobes, and hinged
N
- and C-terminal arms mediate oligomerization, allowing variable protein–protein interface geometry. Oligomerization and RNA binding are mediated by residues conserved in the Orthobunyavirus genus. In the twofold symmetric tetramer, 44 nucleotides bind in a closed ring with sharp bends at the NP–NP interfaces. The RNA is largely inaccessible within a continuous internal groove. Electron microscopy of RNPs released from virions shows them capable of forming a hierarchy of more or less compact irregular helical structures. We discuss how the planar, tetrameric NP–RNA structure might relate to a polar filament that upon supercoiling could be packaged into virions. This work gives insight into the RNA encapsidation and protection function of bunyavirus NP, but also highlights the need for dynamic rearrangements of the RNP to give the polymerase access to the template RNA.