bluuebunny/crossref_metadata_2025 huggingface dataset:
QM/MM investigation of the concentration effects on the second-order nonlinear optical responses of solutions
Authors: Hidalgo Cardenuto Marcelo , Champagne Benoît
Published: December 2014

A multiscale approach combining quantum mechanics (QM) and molecular mechanics methods has been employed to investigate the effects of solute-solute interactions and therefore of concentration on the first hyperpolarizability of solutions of nitrobenzene in benzene. First, spatial distributions of solute and solvent molecules are generated using Monte Carlo simulations where the intermolecular interactions are described using the Lennard-Jones potentials and Coulomb terms. Then, a reduced number of statistically-uncorrelated configurations are sampled and submitted to time-dependent Hartree-Fock calculations of the first hyperpolarizability. When only one molecule is described quantum-mechanically and is embedded in the electrostatic polarization field of the solution described by point charges, βHRS and β// as well as the depolarization ratio increase in parallel with the concentration in nitrobenzene. This effect is attributed to the increase of the polarization field associated with the presence of polar nitrobenzene molecules in the surrounding. Then, the first solvation shell is considered explicitly in the QM calculation to address solute-solute interactions effects. When the number of nitrobenzenes in the first solvation shell increases, βHRS and β// normalized to the number of nitrobenzene molecules decrease and this decrease attains roughly 50% when there are 3 nitrobenzene molecules in the first solvation shell. These drastic reductions of the first hyperpolarizability result from (partial) centro-symmetric arrangements between the nitrobenzene molecules, as supported by the relationship between β and the angle between the nitrobenzene charge transfer axes. Moreover, these β decreases originate mostly from the reduction of the dipolar β component, whereas the octupolar one is rather constant as a function of the nitrobenzene concentration.
Equilibrium properties of charged microgels: A Poisson-Boltzmann-Flory approach
Authors: Colla Thiago , Likos Christos N. , Levin Yan
Published: December 2014

The equilibrium properties of ionic microgels are investigated using a combination of the Poisson-Boltzmann and Flory theories. Swelling behavior, density profiles, and effective charges are all calculated in a self-consistent way. Special attention is given to the effects of salinity on these quantities. In accordance with the traditional ideal Donnan equilibrium theory, it is found that the equilibrium microgel size is strongly influenced by the amount of added salt. Increasing the salt concentration leads to a considerable reduction of the microgel volume, which therefore releases its internal material – solvent molecules and dissociated ions – into the solution. Finally, the question of charge renormalization of ionic microgels in the context of the cell model is briefly addressed.
Negative infrared photocurrent response in layered WS2/reduced graphene oxide hybrids
Authors: Ratha Satyajit , Simbeck Adam J. , Late Dattatray J. , Nayak Saroj K. , Rout Chandra Sekhar
Published: December 2014

We report high performance IR photocurrent response of two-dimensional hybrid materials consisting of layered WS2 nanosheets and reduced graphene oxide (RGO). Comparative photocurrent response studies of WS2 nanosheets, RGO, and WS2/RGO hybrids were carried out by performing current-voltage (I-V) and time-dependent current measurements with a laser excitation source having a wavelength of 808 nm. The experimental investigations indicate that WS2/RGO hybrids show negative photocurrent response, whereas WS2 and RGO show positive photocurrent response. The negative photocurrent response of the WS2/RGO hybrids is explained using a band alignment diagram and attributed to a charge transfer mechanism between WS2 and RGO. This analysis is further corroborated by first-principles density functional calculations. The fabricated device based on WS2/RGO hybrids shows a photosensitivity Rλ of about 6 AW−1 and a quantum efficiency η of ∼924%, which demonstrates high sensitivity of the hybrid material towards IR detection. WS2/RGO hybrids are therefore promising candidates for potential applications in optoelectronic circuits and low cost, high performance, and reliable photodetectors.
Miscible heavy-light displacement flows in an inclined two-dimensional channel: A numerical approach
Authors: Alba K. , Taghavi S. M. , Frigaard I. A.
Published: December 2014

We numerically study the displacement flow of two iso-viscous Newtonian fluids in an inclined two-dimensional channel, formed by two parallel plates. The results are complementary to our previous studies on displacement flows in pipes and channels. The heavier displacing fluid moves the lighter displaced fluid in the downward direction. Three dimensionless groups largely describe these flows: the densimetric Froude number (Fr), the Reynolds number (Re), and the duct inclination (β). As a first order approximation, we are able to classify different flow regimes phenomenologically in a two-dimensional (Fr; Recosβ/Fr)-plane and provide leading order expressions for the transitions between different regimes. The stabilizing and/or de-stabilizing effects of the imposed mean flow on buoyant exchange flows (zero imposed velocity) are described for a broad range of dimensionless parameters.
Structural perturbations of epitaxial α-(Fe1−xVx)2O3 thin films driven by excess oxygen near the surface
Authors: Chamberlin S. E. , Kaspar T. C. , Bowden M. E. , Shutthanandan V. , Kabius B. , Heald S. , Keavney D. J. , Chambers S. A.
Published: December 2014

We examine the structure and composition of phase-pure epitaxial α-(Fe1−xVx)2O3 thin films deposited on α-Al2O3(0001) substrates by oxygen-plasma-assisted molecular beam epitaxy for 0 ≤ x ≤ ∼0.5. The films crystallize in the corundum lattice, with vanadium substituting for iron throughout. Vanadium cations exhibit the expected 3+ charge state in the bulk, but exhibit higher valences nearer to the surface, most likely because of excess oxygen in interstitial sites near the surface. The extent of vanadium oxidation beyond the 3+ state is inversely proportional to x. The gradation of vanadium valence with depth has an impact on local bonding geometries, and could be highly significant in this material's efficiency as a photocatalyst.
Diversity and time delays induce resonance in a modular neuronal network
Authors: Jia Y. B. , Yang X. L. , Kurths J.
Published: December 2014

This paper focuses on the resonance dynamics of a modular neuronal network consisting of several small-world subnetworks. The considered network is composed of delay-coupled FitzHugh-Nagumo (FHN) neurons, whose characteristic parameters present diversity in the form of quenched noise. Our numerical results indicate that when such a network is subjected to an external subthreshold periodic signal, its collective response is optimized for an intermediate level of diversity, namely, a resonant behavior can be induced by an appropriate level of diversity. How the probabilities of intramodule and intermodule connections, as well as the number of subnetworks influence the diversity-induced resonance are also discussed. Further, conclusive evidences demonstrate the nontrivial role of time-delayed coupling on the diversity-induced resonance properties. Especially, multiple resonance is obviously detected when time delays are located at integer multiples of the oscillation period of the signal. Moreover, the phenomenon of fine-tuned delays in inducing multiple resonance remains when diversity is within an intermediate range. Our findings have implications that neural systems may profit from their generic diversity and delayed coupling to optimize the response to external stimulus.
Low temperature p-type doping of (Al)GaN layers using ammonia molecular beam epitaxy for InGaN laser diodes
Authors: Malinverni M. , Lamy J.-M. , Martin D. , Feltin E. , Dorsaz J. , Castiglia A. , Rossetti M. , Duelk M. , Vélez C. , Grandjean N.
Published: December 2014

We demonstrate state-of-the-art p-type (Al)GaN layers deposited at low temperature (740 °C) by ammonia molecular beam epitaxy (NH3-MBE) to be used as top cladding of laser diodes (LDs) with the aim of further reducing the thermal budget on the InGaN quantum well active region. Typical p-type GaN resistivities and contact resistances are 0.4 Ω cm and 5 × 10−4 Ω cm2, respectively. As a test bed, we fabricated a hybrid laser structure emitting at 400 nm combining n-type AlGaN cladding and InGaN active region grown by metal-organic vapor phase epitaxy, with the p-doped waveguide and cladding layers grown by NH3-MBE. Single-mode ridge-waveguide LD exhibits a threshold voltage as low as 4.3 V for an 800 × 2 μm2 ridge dimension and a threshold current density of ∼5 kA cm−2 in continuous wave operation. The series resistance of the device is 6 Ω and the resistivity is 1.5 Ω cm, confirming thereby the excellent electrical properties of p-type Al0.06Ga0.94N:Mg despite the low growth temperature.
Large entropy change associated with the elastocaloric effect in polycrystalline Ni-Mn-Sb-Co magnetic shape memory alloys
Authors: Millán-Solsona Rubén , Stern-Taulats Enric , Vives Eduard , Planes Antoni , Sharma Jyoti , Nayak Ajaya K. , Suresh K. G. , Mañosa Lluís
Published: December 2014

We report on compressive strain measurements in polycrystalline magnetic shape memory alloys aimed at determining the entropy change associated with their elastocaloric effect. It is shown that for a maximum applied stress of 100 MPa, the stress-induced entropy change amounts to ΔS=21 J/kg K. This value compares well to the values reported for nonmagnetic shape memory alloys, and it is of the same order as those reported for the best giant magnetocaloric materials at moderate magnetic fields.
Nitrogen transport from sea to land by a threatened and declining population of Australian sea lions (Neophoca cinerea) on Kangaroo Island, South Australia
Authors: Lavery Trish J. , Roudnew Ben , Mitchell James G.
Published: December 2014

Australian sea lions consume prey in highly productive foraging grounds and defaecate nutrients on land. The resident population of 1100 Australian sea lions contributes 3800 (±80) kg N year–1 into Seal Bay Conservation Park, Kangaroo Island, South Australia. If this population were to decline in abundance the nitrogen availability and coastal productivity of Kangaroo Island may be reduced.
Analysis of the Enol–Keto Tautomers of Indole-3-pyruvic Acid
Authors: Tivendale Nathan D. , Davies Noel W. , Horne James , Ross John J. , Smith Jason A.
Published: December 2014

Indole-3-pyruvic acid (IPyA) is an important naturally occurring biosynthetic intermediate whose quantitation by standard analytic techniques can be complicated as it can exist as either the keto or enol tautomer. Here, we present a detailed analysis of the tautomerism of IPyA and provide further evidence that the two tautomers of IPyA may be readily separated by ultra high-performance liquid chromatography and that the relative proportions of each form may be controlled using temperature and pH.
Synchrotron X-ray absorption spectroscopy analysis of arsenic chemical speciation in human nail clippings
Authors: Ponomarenko Olena , Gherase Mihai R. , LeBlanc Mark S. , Kim Chang-Yong , Desouza Elstan D. , Farquharson Michael J. , McNeill Fiona E. , Nehzati Susan , Pickering Ingrid J. , George Graham N. , Fleming David E. B.
Published: December 2014

Environmental context Chronic ingestion of arsenic leads to its accumulation in keratinous tissues, which can represent a risk factor for developing cancer. We use synchrotron X-ray absorption spectroscopy to investigate chemical bonding of arsenic in the keratins from nail clippings of volunteers from areas in Atlantic Canada with low-to-moderate arsenic contamination of drinking water. The study helps our understanding of arsenic metabolism and its role in cancer development. Abstract Drinking water aquifers in many areas of the world have naturally elevated levels of inorganic arsenic exceeding the World Health Organization limit. Arsenic concentrations in human nail clippings are commonly used as a biomarker of exposure to this toxic element. However, the chemical form of arsenic accumulated in nail tissues is not well determined. We employed synchrotron microprobe and bulk X-ray absorption spectroscopy techniques to analyse the concentration and chemical speciation of arsenic in the finger- and toenail clippings of volunteers living in the vicinity of Sackville, New Brunswick, Canada. This area is known to have low-to-moderately elevated levels of arsenic in ground water. Arsenic species in clippings were represented by three main groups, distinguished by the As-K near-edge X-ray absorption fine structure spectra: (1) AsIII type, which can be fitted as a mixture of As bound to thiols, and also to oxygen or methyl groups, with a small contribution from AsV species, (2) AsV type, best represented by fitting arsenate in aqueous solution and (3) The AsIII+AsV mixture type. The high proportion (%) of sulfur-bound arsenic species most likely corresponds to binding between arsenic (in its trivalent and, to a lesser extent, pentavalent forms) and cysteine residues in the sulfur-rich fraction of keratin and keratin-associated proteins. Further work is needed to explore whether these chemical species could be used as toxicity biomarkers of human exposure to elevated levels of As in drinking water.
Effect of multivalent cations, temperature and aging on soil organic matter interfacial properties
Authors: Diehl Dörte , Schneckenburger Tatjana , Krüger Jaane , Goebel Marc-Oliver , Woche Susanne K. , Schwarz Jette , Shchegolikhina Anastasia , Lang Friederike , Marschner Bernd , Thiele-Bruhn Sören , Bachmann Jörg , Schaumann Gabriele E.
Published: December 2014

Environmental context
The supramolecular structure and resulting physicochemical properties of soil organic matter (SOM) significantly control storage and buffer functions of soils, e.g. for nutrients, organic molecules and water. Multivalent cations, able to form complexes, are suggested to form inter- and intramolecular cross-links in SOM. At present, specific effects of the valence and type of cation on SOM properties are incompletely understood. We investigated changes in SOM interfacial properties, its ability to release mobile colloids in aqueous solutions and its sorption affinity towards organic chemicals in dependence on cation–SOM interactions, temperature and aging time.

Abstract
The present study aims to improve our understanding on the effect of multivalent cations, temperature treatment and isothermal aging time on interfacial soil organic matter (SOM) properties as major factors that modify its supramolecular structures. A sandy topsoil (LW) and a peat soil (SP) were enriched with Na, Ca or Al, or desalinated in a batch experiment, treated at 25, 40, 60 and 105°C and aged at constant temperature and humidity (20°C, 31% relative humidity). After aging for different periods, contact angles (CAs), sorption properties towards xenobiotics and properties of water dispersible colloids were determined. With increasing valence of the dominant cations fewer and larger colloids were observed, probably attributable to cation cross-links or enhanced aggregation caused by reduced surface charge. Al-enrichment of LW resulted in more abundant or more accessible sorption sites for hydrophobic xenobiotics. But in contrast to expectations, hydrophilic sorption as well as wettability was not significantly affected by the type of adsorbed cation. Increasing the temperature had a major effect on surface properties resulting in rising surface hydrophobisation with increasing solid–water CAs, decreasing surface O/C ratio and decreasing sorption of hydrophilic substances; whereas systematic temperature effects on water dispersible colloids and on hydrophobic sorption were not detected. Aging was found to increase the initial CA of the 25°C treatment and to increase the sorption of phenanthrene to LW for all treatment temperatures. We conclude that aging of SOM is a process that changes surface properties and approaches a new equilibrium state after a disturbance. The aging process may be significantly accelerated for samples treated at elevated temperatures.
Fostering teachers' design expertise in teacher design teams: conducive design and support activities
Authors: Huizinga Tjark , Handelzalts Adam , Nieveen Nienke , Voogt Joke
Published: December 2014

Supporting Teacher Design Teams (TDTs) during local curriculum development efforts is essential. To be able to provide high‐quality support, insights are needed about how TDTs carry out design activities and how support is valued by the members of TDTs and how it affects their design expertise. In this study, the design and support processes of two TDTs assisted by an external facilitator were investigated using a case study approach. The results revealed that support offered to TDTs depended on the contextual boundaries and the focus of the design process. The focus, coherence and form of support affected the opportunities for developing teachers’ design expertise. In both cases, teachers’ curriculum design expertise had grown, whereas their pedagogical content knowledge and subject matter knowledge were hardly developed. Findings show that the most conducive support activities and materials were those that could directly be applied in the design process.
Development and Evaluation of an Acoustic Device to Estimate Size Distribution of Channel Catfish in Commercial Ponds
Authors: Goodwiller Bradley T , Beecham Rachel V , Heffington J D , Chambers James P
Published: December 2014

As one step in the continued effort to utilize acoustic methods and techniques to the betterment of catfish aquaculture, an acoustic “catfish sizer” was designed to determine the size distribution of Channel Catfish Ictalurus punctatus in commercial ponds. The catfish sizer employed a custom-built 460 kHz piezoelectric transducer with a 20° beam angle. The sizer was built at the National Center for Physical Acoustics and tested in commercial catfish ponds in Mississippi and Arkansas in June and October. To test the system, fish were collected in seven different ponds using a cut seine. They were weighed and then sent through a pipe into the open pond. The transducer was mounted underwater at the end of the pipe. As the individual fish exited the pipe, they passed through the acoustic field created by the transducer and the echo detected by the transducer was recorded. In three of the seven ponds, calibration tests were run. For these calibration tests, the same process was used with the added step that a jet of bubbles was introduced in front of the transducer after every fifth fish. Analysis of the measured fish weights and acoustic data were used to produce a Gaussian prediction model. This model was applied to the data from the blind tests to predict the average weight and the SD of fish in each pond. The device and methodology worked well, with significant differences between the measured and calculated weights found in only one of the seven ponds tested.
Evaluation of the variations in secondary metabolite concentrations of leymus chinensis seedlings
Authors: Dai Xin , Zhang Yan-Qi , Jiang Lian-Yu , Yuan Fei , Wang Ai-Qin , Wei Wan-Hong , Yang Sheng-Mei
Published: December 2014

Limited information is available about how mammalian browsing activity influences the dynamic defense mechanisms of plants. Here, we aimed to clarify the response mechanism of a herbaceous plant (Chinese lyme grass,Leymus chinensis) to browsing by a mammalian herbivore (Brandt's vole,Lasiopodomy brandtii). We used high-performance liquid chromatography and spectrophotometry to investigate changes in the concentrations of 6-MBOA, total phenol and condensed tannin in Chinese lyme grass seedlings with respect to its ontogeny and different types of damage treatments. 6-MBOA concentrations were higher on day 7 and day 8 than on days 12 and 17 after seedling germination. The concentrations of total phenol and condensed tannin were higher on day 12 than on days 7 and 8 after seedling germination. Compared to the control, higher 6-MBOA concentrations were obtained in the salivation, gnawing and artificial cutting treatment groups. The response of 6-MBOA was delayed in the artificial cutting group compared to the salivation and gnawing groups. In contrast, the concentrations of total phenol and condensed tannin were higher in the artificial cutting and control groups compared to the salivation and gnawing groups. 6-MBOA concentration was negatively correlated with total phenol concentration. The results indicated that 6-MBOA concentration decreased with seedling ontogeny, and that it could be induced by Brandt's vole saliva. In conclusion, our study verified the hypothesis that the browsing by Brandt's vole induces the dynamic defenses ofL. chinensis.
Associations between showering behaviours following physical education, physical activity and fitness in English schoolchildren
Authors: Sandercock Gavin R. H. , Ogunleye Ayodele , Voss Christine
Published: December 2014

We aimed to describe the frequency of showering after physical education (PE) in English high‐school pupils. We examined differences in physical activity (PA) and cardiorespiratory fitness according to showering behaviours and examined predictors of showering. We measured PA and cardiorespiratory fitness of n = 3921 pupils (11–16 years, 53.5% males) from eight high schools. Pupils self‐reported showering behaviour and parental PA levels. We calculated deprivation and distance travelled to school from their home postcode. Overall, 53% of boys and 68% of girls said they never shower after PE. Pupils who did not shower after PE were less physically active and engaged in fewer team sports. Girls who did not shower also had lower cardiorespiratory fitness than those who did. Showering behaviour varied greatly by school, so we adjusted for clustering at the school level. Pupils were more likely to shower if they were active with their parents [odds ratio (OR) = 1.72; 95% CI: 1.43, 2.07] and less likely to shower if they were from deprived areas (OR = 0.68; 95% CI: 0.52, 0.88). Showering after PE is relatively rare in English schoolchildren, particularly girls. While we cannot infer causality regarding the relationships found here, the low rates of showering and the lower PA and cardiorespiratory fitness (in girls) observed in schoolchildren who do not shower suggest research is needed to determine whether showering is a barrier to being physically active during PE.
Not all players are equally motivated: The role of narcissism
Authors: Roberts Ross , Woodman Tim , Lofthouse Sian , Williams Lucy
Published: December 2014

Research on motivational climates consistently demonstrates that mastery‐focused climates are associated with positive outcomes and ego‐involving performance climates lead to maladaptive outcomes. However, the role of personality within such a framework has been largely ignored. To redress this imbalance, we examined the potential role of narcissism in moderating the effects of different motivational climates on leader‐inspired extra effort in training. Training is where rugby players spend most of their rugby time and we were keen to examine the combination of personality and climate that might maximise the yield of such training environments. Female rugby players (n = 126) from 15 clubs completed measures of narcissism, motivational climate and effort. Moderated regression analyses revealed that narcissism moderated the relationship between motivational climate and effort. Increases in either performance or mastery climates were associated with increases in effort for narcissists; no such relationship was revealed for low narcissists. The findings demonstrate the importance of considering personality within rugby training environments, as it is clear that not every player will respond the same way to specific training conditions. Coaches who understand this and are able to tailor individualised motivational climates will likely gain the greatest benefits from their different players.
DETECTION OF STARS WITHIN ∼0.8 in OF Kepler
OBJECTS OF INTEREST
Authors: Kolbl Rea , Marcy Geoffrey W. , Isaacson Howard , Howard Andrew W.
Published: December 2014

We present an algorithm to search for the faint spectrum of a second star mixed
with the spectrum of a brighter star in high resolution spectra. We model
optical stellar spectra as the sum of two input spectra drawn from a vast
library of stars throughout the H-R diagram. From typical spectra having a
resolution of R = 60,000, we are able to detect companions as faint as 1%
relative to the primary star in approximately the V and R bandpasses of
photometry. We are also able to find evidence for triple and quadruple systems,
given that any additional companions are sufficiently bright. The precise
threshold percentage depends on the signal-to-noise of the spectrum and the
properties of the two stars. For cases of non-detection, we place a limit on the
brightness of any potential companions. This algorithm is useful for detecting
faint orbiting companions and background stars that are angularly close to a
foreground target star. The size of the entrance slit to the spectrometer, 0.87
× 3 arcsec (typically), sets the angular domain within which the second
star can be detected. We analyzed Keck-HIRES spectra of 1160 California
Kepler Survey objects of interest (KOI) searching for the
secondary spectra, with the two goals of alerting the community to two possible
host stars of the transiting planet and to dilution of the light curve. We
report 63 California KOI showing spectroscopic evidence of a secondary star.
Spatially heterogeneous impact of climate change on small mammals of montane California
Authors: Rowe Kevin C. , Rowe Karen M. C. , Tingley Morgan W. , Koo Michelle S. , Patton James L. , Conroy Chris J. , Perrine John D. , Beissinger Steven R. , Moritz Craig
Published: December 2014

Resurveys of historical collecting localities have revealed range shifts, primarily leading edge expansions, which have been attributed to global warming. However, there have been few spatially replicated community-scale resurveys testing whether species' responses are spatially consistent. Here we repeated early twentieth century surveys of small mammals along elevational gradients in northern, central and southern regions of montane California. Of the 34 species we analysed, 25 shifted their ranges upslope or downslope in at least one region. However, two-thirds of ranges in the three regions remained stable at one or both elevational limits and none of the 22 species found in all three regions shifted both their upper and lower limits in the same direction in all regions. When shifts occurred, high-elevation species typically contracted their lower limits upslope, whereas low-elevation species had heterogeneous responses. For high-elevation species, site-specific change in temperature better predicted the direction of shifts than change in precipitation, whereas the direction of shifts by low-elevation species was unpredictable by temperature or precipitation. While our results support previous findings of primarily upslope shifts in montane species, they also highlight the degree to which the responses of individual species vary across geographically replicated landscapes.
Background level of risk and the survival of predator-naive prey: can neophobia compensate for predator naivety in juvenile coral reef fishes?
Authors: Ferrari Maud C. O. , McCormick Mark I. , Meekan Mark G. , Chivers Douglas P.
Published: December 2014

Neophobia—the generalized fear response to novel stimuli—provides the first potential strategy that predator-naive prey may use to survive initial predator encounters. This phenotype appears to be highly plastic and present in individuals experiencing high-risk environments, but rarer in those experiencing low-risk environments. Despite the appeal of this strategy as a ‘solution’ for prey naivety, we lack evidence that this strategy provides any fitness benefit to prey. Here, we compare the relative effect of environmental risk (high versus low) and predator-recognition training (predator-naive versus predator-experienced individuals) on the survival of juvenile fish in the wild. We found that juveniles raised in high-risk conditions survived better than those raised in low-risk conditions, providing the first empirical evidence that environmental risk, in the absence of any predator-specific information, affects the way naive prey survive in a novel environment. Both risk level and experience affected survival; however, the two factors did not interact, indicating that the information provided by both factors did not interfere or enhance each other. From a mechanistic viewpoint, this indicates that the combination of the two factors may increase the intensity, and hence efficacy, of prey evasion strategies, or that both factors provide qualitatively separate benefits that would result in an additive survival success.
Maternal and genetic factors determine early life telomere length
Authors: Asghar Muhammad , Bensch Staffan , Tarka Maja , Hansson Bengt , Hasselquist Dennis
Published: December 2014

In a broad range of species—including humans—it has been demonstrated that telomere length declines throughout life and that it may be involved in cell and organismal senescence. This potential link to ageing and thus to fitness has triggered recent interest in understanding how variation in telomere length is inherited and maintained. However, previous studies suffer from two main drawbacks that limit the possibility of understanding the relative importance of genetic, parental and environmental influences on telomere length variation. These studies have been based on (i) telomere lengths measured at different time points in different individuals, despite the fact that telomere length changes over life, and (ii) parent–offspring regression techniques, which do not enable differentiation between genetic and parental components of inheritance. To overcome these drawbacks, in our study of a songbird, the great reed warbler, we have analysed telomere length measured early in life in both parents and offspring and applied statistical models (so-called ‘animal models') that are based on long-term pedigree data. Our results showed a significant heritability of telomere length on the maternal but not on the paternal side, and that the mother's age was positively correlated with their offspring's telomere length. Furthermore, the pedigree-based analyses revealed a significant heritability and an equally large maternal effect. Our study demonstrates strong maternal influence on telomere length and future studies now need to elucidate possible underlying factors, including which types of maternal effects are involved.
The scaffold protein WRAP53β orchestrates the ubiquitin response critical for DNA double-strand break repair
Authors: Henriksson Sofia , Rassoolzadeh Hanif , Hedström Elisabeth , Coucoravas Christos , Julner Alexander , Goldstein Michael , Imreh Gabriela , Zhivotovsky Boris , Kastan Michael B. , Helleday Thomas , Farnebo Marianne
Published: December 2014

The WD40 domain-containing protein WRAP53β (WD40 encoding RNA antisense to p53; also referred to as WDR79/TCAB1) controls trafficking of splicing factors and the telomerase enzyme to Cajal bodies, and its functional loss has been linked to carcinogenesis, premature aging, and neurodegeneration. Here, we identify WRAP53β as an essential regulator of DNA double-strand break (DSB) repair. WRAP53β rapidly localizes to DSBs in an ATM-, H2AX-, and MDC1-dependent manner. We show that WRAP53β targets the E3 ligase RNF8 to DNA lesions by facilitating the interaction between RNF8 and its upstream partner, MDC1, in response to DNA damage. Simultaneous binding of MDC1 and RNF8 to the highly conserved WD40 scaffold domain of WRAP53β facilitates their interaction and accumulation of RNF8 at DSBs. In this manner, WRAP53β controls proper ubiquitylation at DNA damage sites and the downstream assembly of 53BP1, BRCA1, and RAD51. Furthermore, we reveal that knockdown of WRAP53β impairs DSB repair by both homologous recombination (HR) and nonhomologous end-joining (NHEJ), causes accumulation of spontaneous DNA breaks, and delays recovery from radiation-induced cell cycle arrest. Our findings establish WRAP53β as a novel regulator of DSB repair by providing a scaffold for DNA repair factors.
A Sox2 distal enhancer cluster regulates embryonic stem cell differentiation potential
Authors: Zhou Harry Y. , Katsman Yulia , Dhaliwal Navroop K. , Davidson Scott , Macpherson Neil N. , Sakthidevi Moorthy , Collura Felicia , Mitchell Jennifer A.
Published: December 2014

The Sox2 transcription factor must be robustly transcribed in embryonic stem (ES) cells to maintain pluripotency. Two gene-proximal enhancers, Sox2 regulatory region 1 (SRR1) and SRR2, display activity in reporter assays, but deleting SRR1 has no effect on pluripotency. We identified and functionally validated the sequences required for Sox2 transcription based on a computational model that predicted transcriptional enhancer elements within 130 kb of Sox2. Our reporter assays revealed three novel enhancers—SRR18, SRR107, and SRR111—that, through the formation of chromatin loops, form a chromatin complex with the Sox2 promoter in ES cells. Using the CRISPR/Cas9 system and F1 ES cells (Mus musculus129 × Mus castaneus), we generated heterozygous deletions of each enhancer region, revealing that only the distal cluster containing SRR107 and SRR111, located >100 kb downstream from Sox2, is required for cis-regulation of Sox2 in ES cells. Furthermore, homozygous deletion of this distal Sox2 control region (SCR) caused significant reduction in Sox2 mRNA and protein levels, loss of ES cell colony morphology, genome-wide changes in gene expression, and impaired neuroectodermal formation upon spontaneous differentiation to embryoid bodies. Together, these data identify a distal control region essential for Sox2 transcription in ES cells.
Histone acetyltransferase Enok regulates oocyte polarization by promoting expression of the actin nucleation factor spire
Authors: Huang Fu , Paulson Ariel , Dutta Arnob , Venkatesh Swaminathan , Smolle Michaela , Abmayr Susan M. , Workman Jerry L.
Published: December 2014

KAT6 histone acetyltransferases (HATs) are highly conserved in eukaryotes and have been shown to play important roles in transcriptional regulation. Here, we demonstrate that the Drosophila KAT6 Enok acetylates histone H3 Lys 23 (H3K23) in vitro and in vivo. Mutants lacking functional Enok exhibited defects in the localization of Oskar (Osk) to the posterior end of the oocyte, resulting in loss of germline formation and abdominal segments in the embryo. RNA sequencing (RNA-seq) analysis revealed that spire (spir) and maelstrom (mael), both required for the posterior localization of Osk in the oocyte, were down-regulated in enok mutants. Chromatin immunoprecipitation showed that Enok is localized to and acetylates H3K23 at the spir and mael genes. Furthermore, Gal4-driven expression of spir in the germline can largely rescue the defective Osk localization in enok mutant ovaries. Our results suggest that the Enok-mediated H3K23 acetylation (H3K23Ac) promotes the expression of spir, providing a specific mechanism linking oocyte polarization to histone modification.
β-Pix directs collective migration of anterior visceral endoderm cells in the early mouse embryo
Authors: Omelchenko Tatiana , Rabadan M. Angeles , Hernández-Martínez Rocío , Grego-Bessa Joaquim , Anderson Kathryn V. , Hall Alan
Published: December 2014

Collective epithelial migration is important throughout embryonic development. The underlying mechanisms are poorly understood but likely involve spatially localized activation of Rho GTPases. We previously reported that Rac1 is essential for generating the protrusive activity that drives the collective migration of anterior visceral endoderm (AVE) cells in the early mouse embryo. To identify potential regulators of Rac1, we first performed an RNAi screen of Rho family exchange factors (guanine nucleotide exchange factor [GEF]) in an in vitro collective epithelial migration assay and identified β-Pix. Genetic deletion ofβ-Pixin mice disrupts collective AVE migration, while high-resolution live imaging revealed that this is associated with randomly directed protrusive activity. We conclude that β-Pix controls the spatial localization of Rac1 activity to drive collective AVE migration at a critical stage in mouse development.
PTIP associates with Artemis to dictate DNA repair pathway choice
Authors: Wang Jiadong , Aroumougame Asaithamby , Lobrich Markus , Li Yujing , Chen David , Chen Junjie , Gong Zihua
Published: December 2014

PARP inhibitors (PARPis) are being used in patients withBRCA1/2mutations. However, doubly deficient BRCA1−/−53BP1−/−cells or tumors become resistant to PARPis. Since 53BP1 or its known downstream effectors, PTIP and RIF1 (RAP1-interacting factor 1 homolog), lack enzymatic activities directly implicated in DNA repair, we decided to further explore the 53BP1-dependent pathway. In this study, we uncovered a nuclease, Artemis, as a PTIP-binding protein. Loss of Artemis restores PARPi resistance in BRCA1-deficient cells. Collectively, our data demonstrate that Artemis is the major downstream effector of the 53BP1 pathway, which prevents end resection and promotes nonhomologous end-joining and therefore directly competes with the homologous recombination repair pathway.
Bayesian inversion of time‐lapse seismic data for the estimation of static reservoir properties and dynamic property changes
Authors: Grana Dario , Mukerji Tapan
Published: December 2014

Seismic conditioning of static reservoir model properties such as porosity and lithology has traditionally been faced as a solution of an inverse problem. Dynamic reservoir model properties have been constrained by time‐lapse seismic data. Here, we propose a methodology to jointly estimate rock properties (such as porosity) and dynamic property changes (such as pressure and saturation changes) from time‐lapse seismic data. The methodology is based on a full Bayesian approach to seismic inversion and can be divided into two steps. First we estimate the conditional probability of elastic properties and their relative changes; then we estimate the posterior probability of rock properties and dynamic property changes. We apply the proposed methodology to a synthetic reservoir study where we have created a synthetic seismic survey for a real dynamic reservoir model including pre‐production and production scenarios. The final result is a set of point‐wise probability distributions that allow us to predict the most probable reservoir models at each time step and to evaluate the associated uncertainty. Finally we also show an application to real field data from the Norwegian Sea, where we estimate changes in gas saturation and pressure from time‐lapse seismic amplitude differences. The inverted results show the hydrocarbon displacement at the times of two repeated seismic surveys.
The spread of injectate during saphenous nerve block at the adductor canal: a cadaver study
Authors: ANDERSEN H. L. , ANDERSEN S. L. , TRANUM‐JENSEN J.
Published: December 2014

Background

The spread of injectate during a saphenous nerve block at the adductor canal has not been clearly described.

Methods

We examined the spread of 15 ml dyed injectate during ultrasound‐guided saphenous nerve blocks at the adductor canal in 15 unembalmed cadavers' lower limbs followed by comparative dissections of the same limbs.

Results

The spread of the injectates was determined by the fascial limits and the muscles surrounding the adductor canal. The anteromedial limit of the adductor canal (the roof) was found to be a continuous fascia, with a thin proximal part and a thicker distal part (the vastoadductor membrane) covering the canal from the apex of the femoral triangle to the adductor hiatus. The fascial limits of the adductor canal formed a conduit around the femoral neurovascular bundle. The dyed aqueous injectate spread throughout the entire adductor canal to the femoral triangle and reached 1–2 cm into the popliteal fossa. Injections superficial to the adductor canal spread over the femoral artery within the subsartorial fat compartment resembling the injections within the canal but with ultrasonographic distinct features. These injections spread only half the length of the adductor canal. The only nerve observed within the adductor canal was the saphenous nerve.

Conclusions

Injection of 15 ml dye was sufficient to spread throughout the adductor canal and beyond both proximally and distally. Distinct ultrasonographic features could be identified separating a subsartorial injection from an injection within the adductor canal with consequent differences in the spread.
Images of psychiatry and psychiatrists
Authors: Stuart H. , Sartorius N. , Liinamaa T. ,   the Images Study Group
Published: December 2014

Objective

This study surveyed medical teaching faculty to determine their attitudes toward psychiatry and psychiatrists.

Method

We conducted a multisite survey of a probability sample of 1057 teaching medical faculty members from 15 academic teaching centers in the United Kingdom, Europe, and Asia stratified by early, middle, and late career stage. The average response rate across countries was 65%.

Results

The outstanding findings were that 90% of respondents considered that psychiatrists were not good role models for medical students, 84% thought psychiatric patients were unsuitable to be treated outside of specialized facilities, and 73% thought psychiatric patients were emotionally draining. We noted statistically significant differences by country, gender, career stage, and specialty.

Conclusion

These results highlight why recruitment into psychiatry is problematic in many countries and suggest that greater attention should be given to improving the perception of psychiatrists as good role models and the efficacy of psychiatric treatments.
A longitudinal study of the association of adolescent polydrug use, alcohol use and high school non‐completion
Authors: Kelly Adrian B. , Evans‐Whipp Tracy J. , Smith Rachel , Chan Gary C. K. , Toumbourou John W. , Patton George C. , Hemphill Sheryl A. , Hall Wayne D. , Catalano Richard F.
Published: December 2014

Aims

Failure to complete high school predicts substantial economic and social disadvantage in adult life. The aim of this study was to determine the longitudinal association of mid‐adolescent polydrug use and high school non‐completion, relative to other drug use profiles.

Design

A longitudinal analysis of the relationship between polydrug use in three cohorts at grade 9 (age 14–15 years) and school non‐completion (reported post‐high school).

Setting

A State‐representative sample of students across Victoria, Australia.

Participants

A total of 2287 secondary school students from 152 high schools. The retention rate was 85%.

Measurements

The primary outcome was non‐completion of grade 12 (assessed at age 19–23 years). At grade 9, predictors included 30‐day use of eight drugs, school commitment, academic failure and peer drug use. Other controls included socio‐economic status, family relationship quality, depressive symptoms, gender, age and cohort.

Findings

Three distinct classes of drug use were identified—no drug use (31.7%), mainly alcohol use (61.8%) and polydrug use (6.5%). Polydrug users were characterized by high rates of alcohol, tobacco and cannabis use. In the full model, mainly alcohol users and polydrug users were less likely to complete school than non‐drug users [odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.17–2.03) and OR = 2.51, 95% CI = 1.45–4.33), respectively, P < 0.001]. These effects were independent of school commitment, academic failure, peer drug use and other controls.

Conclusions

Mid‐adolescent polydrug use in Australia predicts subsequent school non‐completion after accounting for a range of potential confounding factors. Adolescents who mainly consume alcohol are also at elevated risk of school non‐completion.
In situ Measurements of Oxygen Dynamics in Unsaturated Archaeological Deposits
Authors: Matthiesen H. , Hollesen J. , Dunlop R. , Seither A. , de Beer J.
Published: December 2014

Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more than a year. It is shown that there is a significant spatial and temporal variation in the oxygen concentration, which is correlated to measured soil characteristics, precipitation, soil water content and degradation of organic material. In these deposits oxygen typically occurs when the air content of the soil exceeds 10–15% vol, while oxygen dissolved in infiltrating rainwater is of less importance for the supply of oxygen in the unsaturated zone.
Exponentially decreasing tooth growth rate in horse teeth: implications for isotopic analyses
Authors: Bendrey R. , Vella D. , Zazzo A. , Balasse M. , Lepetz S.
Published: December 2014

A range of archaeological and palaeoclimatic studies use isotopic analyses of ungulate hypsodont tooth enamel. Such studies commonly assume a constant growth rate, though this has not been fully tested. Here, we use stable isotope analyses of sequential enamel samples to study horse tooth growth. We fit the data using models corresponding to constant and exponentially decreasing rates of growth, and compare the results to metrical data showing the geometry and timing of apposition. The results indicate enamel apposition and maturation advances at an exponentially decreasing rate. An understanding of this variable growth rate is crucial for interpreting isotopic data from equid teeth.
Distribution of radioactive cesium and stable cesium in cattle kept on a highly contaminated area of Fukushima nuclear accident
Authors: Sato Itaru , Okada Keiji , Sasaki Jun , Chida Hiroyuki , Satoh Hiroshi , Miura Kiyoshi , Kikuchi Kaoru , Otani Kumiko , Sato Shusuke
Published: December 2014

Radioactivity inspection of slaughtered cattle is generally conducted using a portion of the neck muscle; however, there is limited information about the distribution of radioactive cesium in cattle. In this study, therefore, we measured not only radioactive cesium but also stable cesium in various tissues of 19 cattle that had been kept in the area highly contaminated by the Fukushima nuclear accident. Skeletal muscles showed approximately 1.5‐3.0 times higher concentration of radioactive cesium than internal organs. Radioactive cesium concentration in the tenderloin and top round was about 1.2 times as high as that in the neck muscle. The kidney showed the highest concentration of radioactive cesium among internal organs, whereas the liver was lowest. Radioactive cesium concentration in the blood was about 8% of that in the neck muscle. Characteristics of stable cesium distribution were almost the same as those of radioactive cesium. Correlation coefficient between radioactive cesium and stable cesium in tissues of individual cattle was 0.981 ± 0.012. When a suspicious level near 100 Bq/kg is detected in the neck of slaughtered cattle, re‐inspection should be conducted using a different region of muscle, for example top round, to prevent marketing of beef that violates the Food Sanitation Act.