bluuebunny/crossref_metadata_2025 huggingface dataset:
A unified heteronuclear decoupling strategy for magic-angle-spinning solid-state NMR spectroscopy
Authors: Equbal Asif , Bjerring Morten , Madhu P. K. , Nielsen Niels Chr.
Published: May 2015

A unified strategy of two-pulse based heteronuclear decoupling for solid-state magic-angle spinning nuclear magnetic resonance is presented. The analysis presented here shows that different decoupling sequences like two-pulse phase-modulation (TPPM), X-inverse-X (XiX), and finite pulse refocused continuous wave (rCWA) are basically specific solutions of a more generalized decoupling scheme which incorporates the concept of time-modulation along with phase-modulation. A plethora of other good decoupling conditions apart from the standard, TPPM, XiX, and rCWA decoupling conditions are available from the unified decoupling approach. The importance of combined time- and phase-modulation in order to achieve the best decoupling conditions is delineated. The consequences of different indirect dipolar interactions arising from cross terms comprising of heteronuclear and homonuclear dipolar coupling terms and also those between heteronuclear dipolar coupling and chemical-shift anisotropy terms are presented in order to unfold the effects of anisotropic interactions under different decoupling conditions. Extensive numerical simulation results are corroborated with experiments on standard amino acids.
The effect of intersystem crossings in N(2D) + H2 collisions
Authors: Galvão B. R. L. , Poveda L. A.
Published: May 2015

The transitions between quartet and doublet states of the NH2 molecule are studied for the first time, allowing the evaluation of the N(4S) + H2 reactive channel. High level ab initio calculations of the spin-orbit coupling are performed over the whole configurational space of the NH2 molecule and fitted to a proposed analytic form. Quasiclassical trajectories coupled with the surface hopping method are employed to calculate reaction cross section and rate constants. The reaction is largely affected by the initial rovibrational states of H2, while the formation of long-lived complexes enhances the reaction probability.
Electron transport in unipolar InGaN/GaN multiple quantum well structures grown by NH3 molecular beam epitaxy
Authors: Browne David A. , Mazumder Baishakhi , Wu Yuh-Renn , Speck James S.
Published: May 2015

Unipolar-light emitting diode like structures were grown by NH3 molecular beam epitaxy on c plane (0001) GaN on sapphire templates. Studies were performed to experimentally examine the effect of random alloy fluctuations on electron transport through quantum well active regions. These unipolar structures served as a test vehicle to test our 2D model of the effect of compositional fluctuations on polarization-induced barriers. Variables that were systematically studied included varying quantum well number from 0 to 5, well thickness of 1.5 nm, 3 nm, and 4.5 nm, and well compositions of In0.14Ga0.86N and In0.19Ga0.81N. Diode-like current voltage behavior was clearly observed due to the polarization-induced conduction band barrier in the quantum well region. Increasing quantum well width and number were shown to have a significant impact on increasing the turn-on voltage of each device. Temperature dependent IV measurements clearly revealed the dominant effect of thermionic behavior for temperatures from room temperature and above. Atom probe tomography was used to directly analyze parameters of the alloy fluctuations in the quantum wells including amplitude and length scale of compositional variation. A drift diffusion Schrödinger Poisson method accounting for two dimensional indium fluctuations (both in the growth direction and within the wells) was used to correctly model the turn-on voltages of the devices as compared to traditional 1D simulation models.
On a theory of stability for nonlinear stochastic chemical reaction networks
Authors: Smadbeck Patrick , Kaznessis Yiannis N.
Published: May 2015

We present elements of a stability theory for small, stochastic, nonlinear chemical reaction networks. Steady state probability distributions are computed with zero-information (ZI) closure, a closure algorithm that solves chemical master equations of small arbitrary nonlinear reactions. Stochastic models can be linearized around the steady state with ZI-closure, and the eigenvalues of the Jacobian matrix can be readily computed. Eigenvalues govern the relaxation of fluctuation autocorrelation functions at steady state. Autocorrelation functions reveal the time scales of phenomena underlying the dynamics of nonlinear reaction networks. In accord with the fluctuation-dissipation theorem, these functions are found to be congruent to response functions to small perturbations. Significant differences are observed in the stability of nonlinear reacting systems between deterministic and stochastic modeling formalisms.
Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy
Authors: Hafiz Moustafa Abdel , Maurice Vincent , Chutani Ravinder , Passilly Nicolas , Gorecki Christophe , Guérandel Stéphane , de Clercq Emeric , Boudot Rodolphe
Published: May 2015

We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 ± 0.03) eV, leading to a clock frequency shift rate of 2.7 × 10−9/K in fractional unit. A hyperfine population lifetime, T1, and a microwave coherence lifetime, T2, of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed.
Sound velocity of tantalum under shock compression in the 18–142 GPa range
Authors: Xi Feng , Jin Ke , Cai Lingcang , Geng Huayun , Tan Ye , Li Jun
Published: May 2015

Dynamic compression experiments of tantalum (Ta) within a shock pressure range from 18–142 GPa were conducted driven by explosive, a two-stage light gas gun, and a powder gun, respectively. The time-resolved Ta/LiF (lithium fluoride) interface velocity profiles were recorded with a displacement interferometer system for any reflector. Sound velocities of Ta were obtained from the peak state time duration measurements with the step-sample technique and the direct-reverse impact technique. The uncertainty of measured sound velocities were analyzed carefully, which suggests that the symmetrical impact method with step-samples is more accurate for sound velocity measurement, and the most important parameter in this type experiment is the accurate sample/window particle velocity profile, especially the accurate peak state time duration. From these carefully analyzed sound velocity data, no evidence of a phase transition was found up to the shock melting pressure of Ta.
An electron energy-loss study of picene and chrysene based charge transfer salts
Authors: Müller Eric , Mahns Benjamin , Büchner Bernd , Knupfer Martin
Published: May 2015

The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F4TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.
Electrochemical removal of hydrogen atoms in Mg-doped GaN epitaxial layers
Authors: Lee June Key , Hyeon Gil Yong , Tawfik Wael Z. , Choi Hee Seok , Ryu Sang-Wan , Jeong Tak , Jung Eunjin , Kim Hyunsoo
Published: May 2015

Hydrogen atoms inside of an Mg-doped GaN epitaxial layer were effectively removed by the electrochemical potentiostatic activation (EPA) method. The role of hydrogen was investigated in terms of the device performance of light-emitting diodes (LEDs). The effect of the main process parameters for EPA such as solution type, voltage, and time was studied and optimized for application to LED fabrication. In optimized conditions, the light output of 385-nm LEDs was improved by about 26% at 30 mA, which was caused by the reduction of the hydrogen concentration by ∼35%. Further removal of hydrogen seems to be involved in the breaking of Ga-H bonds that passivate the nitrogen vacancies. An EPA process with high voltage breaks not only Mg-H bonds that generate hole carriers but also Ga-H bonds that generate electron carriers, thus causing compensation that impedes the practical increase of hole concentration, regardless of the drastic removal of hydrogen atoms. A decrease in hydrogen concentration affects the current-voltage characteristics, reducing the reverse current by about one order and altering the forward current behavior in the low voltage region.
Dynamic memory of a single voltage-gated potassium ion channel: A stochastic nonequilibrium thermodynamic analysis
Authors: Banerjee Kinshuk
Published: May 2015

In this work, we have studied the stochastic response of a single voltage-gated potassium ion channel to a periodic external voltage that keeps the system out-of-equilibrium. The system exhibits memory, resulting from time-dependent driving, that is reflected in terms of dynamic hysteresis in the current-voltage characteristics. The hysteresis loop area has a maximum at some intermediate voltage frequency and disappears in the limits of low and high frequencies. However, the (average) dissipation at long-time limit increases and finally goes to saturation with rising frequency. This raises the question: how diminishing hysteresis can be associated with growing dissipation? To answer this, we have studied the nonequilibrium thermodynamics of the system and analyzed different thermodynamic functions which also exhibit hysteresis. Interestingly, by applying a temporal symmetry analysis in the high-frequency limit, we have analytically shown that hysteresis in some of the periodic responses of the system does not vanish. On the contrary, the rates of free energy and internal energy change of the system as well as the rate of dissipative work done on the system show growing hysteresis with frequency. Hence, although the current-voltage hysteresis disappears in the high-frequency limit, the memory of the ion channel is manifested through its specific nonequilibrium thermodynamic responses.
Consumption of crops by feral pigs (Sus scrofa) in a fragmented agricultural landscape
Authors: Gentle Matthew , Speed James , Marshall Darren
Published: May 2015

Feral pigs (Sus scrofa) consume and damage crops and impact the environment through predation, competition and habitat disturbance, although supporting dietary data are lacking in agricultural landscapes. This study was undertaken to determine the relative importance of food items in the diet of feral pigs in a fragmented agricultural landscape, particularly to assist in predicting the breadth of likely impacts. Diet composition was assessed from the stomach contents of 196 feral pigs from agricultural properties in southern Queensland. Feral pigs were herbivorous, with plant matter comprising >99% of biomass consumed. Crops were consumed more frequently than non-crop species, and comprised >60% of dietary biomass, indicating a clear potential for direct economic losses. Consumption of pasture and forage species also suggests potential competition for pasture with domestic stock. There is little evidence of direct predation on native fauna, but feral pig feeding activities may impact environmental values. Seasonal differences in consumption of crop, pasture or animal food groups probably reflect the changing availability of food items. We recommend that future dietary studies examine food availability to determine any dietary preferences to assist in determining the foods most susceptible to damage. The outcomes of this study are important for developing techniques for monitoring the impacts of feral pigs, essential for developing management options to reduce feral pig damage on agricultural lands.
Public justification versus public deliberation: the case for divorce
Authors: Vallier Kevin
Published: May 2015

I drive a wedge between public deliberation and public justification, concepts tightly associated in public reason liberalism. Properly understood, the ideal of public justification imposes no restraint on citizen deliberation but requires that those who have a substantial impact on the use of coercive power, political officials, advance proposals each person has sufficient reason to accept. I formulate this idea as the Principle of Convergent Restraint and apply it to legislators to illustrate the general reorientation I propose for the public reason project.
Latent semantic analysis cosines as a cognitive similarity measure: Evidence from priming studies
Authors: Günther Fritz , Dudschig Carolin , Kaup Barbara
Published: May 2015

In distributional semantics models (DSMs) such as latent semantic analysis (LSA), words are represented as vectors in a high-dimensional vector space. This allows for computing word similarities as the cosine of the angle between two such vectors. In two experiments, we investigated whether LSA cosine similarities predict priming effects, in that higher cosine similarities are associated with shorter reaction times (RTs). Critically, we applied a pseudo-random procedure in generating the item material to ensure that we directly manipulated LSA cosines as an independent variable. We employed two lexical priming experiments with lexical decision tasks (LDTs). In Experiment 1 we presented participants with 200 different prime words, each paired with one unique target. We found a significant effect of cosine similarities on RTs. The same was true for Experiment 2, where we reversed the prime-target order (primes of Experiment 1 were targets in Experiment 2, and vice versa). The results of these experiments confirm that LSA cosine similarities can predict priming effects, supporting the view that they are psychologically relevant. The present study thereby provides evidence for qualifying LSA cosine similarities not only as a linguistic measure, but also as a cognitive similarity measure. However, it is also shown that other DSMs can outperform LSA as a predictor of priming effects.
Boundaries and polyhedral Banach spaces
Authors: Fonf V. , Smith R. , Troyanski S.
Published: May 2015

We show that if

X
X

and

Y
Y

are Banach spaces, where

Y
Y

is separable and polyhedral, and if

T
:
X
→
Y

T:X\to Y

is a bounded linear operator such that

T
∗

(

Y
∗

)

T^*(Y^*)

contains a boundary

B
B

of

X
X

, then

X
X

is separable and isomorphic to a polyhedral space. Some corollaries of this result are presented.
A concise review of lobster utilization by worldwide human populations from prehistory to the modern era
Authors: Spanier Ehud , Lavalli Kari L. , Goldstein Jason S. , Groeneveld Johan C. , Jordaan Gareth L. , Jones Clive M. , Phillips Bruce F. , Bianchini Marco L. , Kibler Rebecca D. , Díaz David , Mallol Sandra , Goñi Raquel , van Der Meeren Gro I. , Agnalt Ann-Lisbeth , Behringer Donald C. , Keegan William F. , Jeffs Andrew
Published: May 2015

Lobsters are important resources throughout the world's oceans, providing food security, employment, and a trading commodity. Whereas marine biologists generally focus on modern impacts of fisheries, here we explore the deep history of lobster exploitation by prehistorical humans and ancient civilizations, through the first half of the 20th century. Evidence of lobster use comprises midden remains, artwork, artefacts, writings about lobsters, and written sources describing the fishing practices of indigenous peoples. Evidence from archaeological dig sites is potentially biased because lobster shells are relatively thin and easily degraded in most midden soils; in some cases, they may have been used as fertilizer for crops instead of being dumped in middens. Lobsters were a valuable food and economic resource for early coastal peoples, and ancient Greek and Roman Mediterranean civilizations amassed considerable knowledge of their biology and fisheries. Before European contact, lobsters were utilized by indigenous societies in the Americas, southern Africa, Australia, and New Zealand at seemingly sustainable levels, even while other fish and molluscan species may have been overfished. All written records suggest that coastal lobster populations were dense, even in the presence of abundant and large groundfish predators, and that lobsters were much larger than at present. Lobsters gained a reputation as “food for the poor” in 17th and 18th century Europe and parts of North America, but became a fashionable seafood commodity during the mid-19th century. High demand led to intensified fishing effort with improved fishing gear and boats, and advances in preservation and long-distance transport. By the early 20th century, coastal stocks were overfished in many places and average lobster size was significantly reduced. With overfishing came attempts to regulate fisheries, which have varied over time and have met with limited success.
Parallel evolutionary pathways to antibiotic resistance selected by biocide exposure
Authors: Webber Mark A. , Whitehead Rebekah N. , Mount Manuella , Loman Nick J. , Pallen Mark J. , Piddock Laura J. V.
Published: May 2015

Objectives

Biocides are widely used to prevent infection. We aimed to determine whether exposure of Salmonella to various biocides could act as a driver of antibiotic resistance.

Methods

Salmonella enterica serovar Typhimurium was exposed to four biocides with differing modes of action. Antibiotic-resistant mutants were selected during exposure to all biocides and characterized phenotypically and genotypically to identify mechanisms of resistance.

Results

All biocides tested selected MDR mutants with decreased antibiotic susceptibility; these occurred randomly throughout the experiments. Mutations that resulted in de-repression of the multidrug efflux pump AcrAB-TolC were seen in MDR mutants. A novel mutation in rpoA was also selected and contributed to the MDR phenotype. Other mutants were highly resistant to both quinolone antibiotics and the biocide triclosan.

Conclusions

This study shows that exposure of bacteria to biocides can select for antibiotic-resistant mutants and this is mediated by clinically relevant mechanisms of resistance prevalent in human pathogens.
Critical Changes in Cortical Neuronal Interactions in Anesthetized and Awake Rats
Authors: Hudetz Anthony G. , Vizuete Jeannette A. , Pillay Siveshigan , Ropella Kristina M.
Published: May 2015

AbstractAbstract

Neuronal interactions increase during stepwise emergence from desflurane anesthesia and were enhanced by visual stimulation to the greatest extent during the return of righting reflex. Critical changes in neuronal interaction correlate with depth of anesthesia and an experimental index of the return of consciousness.

Background:

Neuronal interactions are fundamental for information processing, cognition, and consciousness. Anesthetics reduce spontaneous cortical activity; however, neuronal reactivity to sensory stimuli is often preserved or augmented. How sensory stimulus–related neuronal interactions change under anesthesia has not been elucidated. In this study, the authors investigated the visual stimulus–related cortical neuronal interactions during stepwise emergence from desflurane anesthesia.

Methods:

Parallel spike trains were recorded with 64-contact extracellular microelectrode arrays from the primary visual cortex of chronically instrumented, unrestrained rats (N = 6) at 8, 6, 4, and 2% desflurane anesthesia and wakefulness. Light flashes were delivered to the retina by transcranial illumination at 5- to 15-s randomized intervals. Information theoretical indices, integration and interaction complexity, were calculated from the probability distribution of coincident spike patterns and used to quantify neuronal interactions before and after flash stimulation.

Results:

Integration and complexity showed significant negative associations with desflurane concentration (N = 60). Flash stimulation increased integration and complexity at all anesthetic levels (N = 60); the effect on complexity was reduced in wakefulness. During stepwise withdrawal of desflurane, the largest increase in integration (74%) and poststimulus complexity (35%) occurred before reaching 4% desflurane concentration—a level associated with the recovery of consciousness according to the rats’ righting reflex.

Conclusions:

Neuronal interactions in the cerebral cortex are augmented during emergence from anesthesia. Visual flash stimuli enhance neuronal interactions in both wakefulness and anesthesia; the increase in interaction complexity is attenuated as poststimulus complexity reaches plateau. The critical changes in cortical neuronal interactions occur during transition to consciousness.
Assisted Ventilation in Patients with Acute Respiratory Distress Syndrome
Authors: Doorduin Jonne , Sinderby Christer A. , Beck Jennifer , van der Hoeven Johannes G. , Heunks Leo M. A.
Published: May 2015

AbstractAbstract

Twelve patients with mild-to-moderate acute respiratory distress syndrome were ventilated in a randomized order with three ventilation modes: pressure control ventilation, pressure support ventilation, and neurally adjusted ventilatory assist. Lung-protective ventilation was maintained to a similar degree in all study arms; the results are hypothesis generating for using assisted ventilation in patients with acute respiratory distress syndrome after the first 48 h of therapy, which might include paralysis.

Supplemental Digital Content is available in the text.

Background:

In patients with acute respiratory distress syndrome (ARDS), the use of assisted mechanical ventilation is a subject of debate. Assisted ventilation has benefits over controlled ventilation, such as preserved diaphragm function and improved oxygenation. Therefore, higher level of “patient control” of ventilator assist may be preferable in ARDS. However, assisted modes may also increase the risk of high tidal volumes and lung-distending pressures. The current study aims to quantify how differences in freedom to control the ventilator affect lung-protective ventilation, breathing pattern variability, and patient–ventilator interaction.

Methods:

Twelve patients with ARDS were ventilated in a randomized order with assist pressure control ventilation (PCV), pressure support ventilation (PSV), and neurally adjusted ventilatory assist (NAVA). Transpulmonary pressure, tidal volume, diaphragm electrical activity, and patient–ventilator interaction were measured. Respiratory variability was assessed using the coefficient of variation of tidal volume.

Results:

During inspiration, transpulmonary pressure was slightly lower with NAVA (10.3 ± 0.7, 11.2 ± 0.7, and 9.4 ± 0.7 cm H2O for PCV, PSV, and NAVA, respectively; P < 0.01). Tidal volume was similar between modes (6.6 [5.7 to 7.0], 6.4 [5.8 to 7.0], and 6.0 [5.6 to 7.3] ml/kg for PCV, PSV, and NAVA, respectively), but respiratory variability was higher with NAVA (8.0 [6.4 to 10.0], 7.1 [5.9 to 9.0], and 17.0 [12.0 to 36.1] % for PCV, PSV, and NAVA, respectively; P < 0.001). Patient–ventilator interaction improved with NAVA (6 [5 to 8] % error) compared with PCV (29 [14 to 52] % error) and PSV (12 [9 to 27] % error); P < 0.0001.

Conclusion:

In patients with mild-to-moderate ARDS, increasing freedom to control the ventilator maintains lung-protective ventilation in terms of tidal volume and lung-distending pressure, but it improves patient–ventilator interaction and preserves respiratory variability.
Efficacy of 2 Regional Pain Control Techniques in Pediatric Foot Surgery
Authors: Lloyd Chandra H. , Srinath Arjun K. , Muchow Ryan D. , Iwinski Henry J. , Talwalkar Vishwas R. , Walker Janet L. , Montgomery Christopher , Milbrandt Todd
Published: May 2015

Background:

Peripheral nerve blocks (PNBs) have the potential to reduce postoperative pain. The use of ultrasound (US) to guide PNBs may be more beneficial than nerve stimulation (NS); however, very few studies have studied this technique in children. The objective of this study was to compare postoperative pain control in pediatric patients who had general anesthesia (GA) alone compared with those who had PNB performed by NS, or PNB with both NS and US guidance. Our hypothesis was that compared with NS, the US-guided PNB would result in reduced postoperative pain and opioid use, and that both PNB conditions would have improved outcomes compared with GA.

Methods:

A retrospective chart review of foot and ankle surgery included 103 patients who were stratified into 3 groups: GA, PNB with NS, and PNB with NS and US. Pain levels were measured with visual pain scales at 2, 4, 6, 8, 12, and 24 hours postoperatively. Days of hospitalization, morphine and oxycodone use by weight, and time to first PRN opioid use were also recorded. A repeated measure analysis of variance was used to compare the groups, and the proportion of patients who reported a visual analog scale score of 0 was calculated for each time point.

Results:

There were no significant differences in pain levels between groups for the first 12 hours, but the US group had higher pain levels at 24 hours. Both US and NS groups had a longer time to PRN opioid use and used significantly less morphine compared with GA. The US group had a significantly greater proportion of pain-free patients than the other 2 groups for the first 6 hours.

Conclusions:

The use of US guidance is beneficial in postoperative pain control. Both US-guided and NS-guided PNB are preferable to GA alone for lower extremity orthopaedic surgery in the pediatric population.

Level of Evidence:

III, retrospective comparative study.
Radiographic Assessment of Shoulder Position in 619 Idiopathic Scoliosis Patients: Can T1 Tilt Be Used as an Intraoperative Proxy to Determine Postoperative Shoulder Balance?
Authors: Luhmann Scott J. , Sucato Dan J. , Johnston Charles E. , Richards B. Stephens , Karol Lori A.
Published: May 2015

Background:

The purpose of this study is to assess radiographic shoulder measures from the preoperative to the postoperative time period, specifically to determine whether T1 tilt could be used as an intraoperative proxy for shoulder balance determination. This study focused on radiographic shoulder measures of 619 adolescent idiopathic scoliosis patients who underwent spinal deformity surgery.

Methods:

A prospective, multicenter database of adolescent idiopathic scoliosis was queried to identify all patients who had undergone spinal deformity surgery with >2 years of follow-up postoperatively. Radiographic analysis focused on measures of shoulder balance: T1 tilt, clavicle angle, and radiographic shoulder height.

Results:

A total of 619 patients were included in this analysis. Mean age at surgery was 14.8 years with 83% female. Mean preoperative curve size was 58.0 degrees. Mean T1 tilt preoperatively was −0.10 degrees and postoperatively 2.42 degrees. Mean clavicle angle preoperatively was −1.39 degrees and postoperatively 0.79 degrees. Mean radiographic shoulder height preoperatively was −7.04 mm and postoperatively 1.63 mm. All 3 radiographic parameters demonstrated reasonable correlation preoperatively and postoperatively to each other. To assess the viability of T1 tilt as an intraoperative proxy for shoulder balance, standardized ratios between the variables were created. Analysis of these ratios demonstrated little or no relationship preoperatively to postoperatively, hence the relationship of T1 tilt to radiographic shoulder height does not remain constant.

Conclusions:

Analysis of the relationship of T1 tilt to radiographic shoulder height from preoperative to postoperative did not demonstrate consistency. Lenke 3 and 6 curve patterns demonstrated preoperative to postoperative correlation, both with nonstructural proximal thoracic curves; however, for the remaining curve patterns T1 tilt cannot be used as an intraoperative proxy for shoulder balance.

Level of Evidence:

Level IV.
Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management
Authors: Hegg Jens C. , Giarrizzo Tommaso , Kennedy Brian P.
Published: May 2015

Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world’s largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some of the longest freshwater fish migrations in the world, travelling from the Amazon River estuary to the Andes foothills. These species are important apex predators in the main stem rivers of the Amazon Basin and make up the regions largest fishery. They are also the only species to utilize the entire Amazon Basin to complete their life cycle. Studies indicate both that the fisheries may be declining due to overfishing, and that the proposed and completed dams in their upstream range threaten spawning migrations. Despite this, surprisingly little is known about the details of these species’ migrations, or their life history. Otolith microchemistry has been an effective method for quantifying and reconstructing fish migrations worldwide across multiple spatial scales and may provide a powerful tool to understand the movements of Amazonian migratory catfish. Our objective was to describe the migratory behaviors of the three most populous and commercially important migratory catfish species, Dourada (Brachyplatystoma rousseauxii), Piramutaba (Brachyplatystoma vaillantii), and Piraíba (Brachyplatystoma filamentosum). We collected fish from the mouth of the Amazon River and the Central Amazon and used strontium isotope signatures (87Sr/86Sr) recorded in their otoliths to determine the location of early rearing and subsequent. Fish location was determined through discriminant function classification, using water chemistry data from the literature as a training set. Where water chemistry data was unavailable, we successfully in predicted87Sr/86Sr isotope values using a regression-based approach that related the geology of the upstream watershed to the Sr isotope ratio. Our results provide the first reported otolith microchemical reconstruction ofBrachyplatystomamigratory movements in the Amazon Basin. Our results indicate that juveniles exhibit diverse rearing strategies, rearing in both upstream and estuary environments. This contrasts with the prevailing understanding that juveniles rear in the estuary before migrating upstream; however it is supported by some fisheries data that has indicated the presence of alternate spawning and rearing life-histories. The presence of alternate juvenile rearing strategies may have important implications for conservation and management of the fisheries in the region.
Rail-RNA: Scalable analysis of RNA-seq splicing and coverage
Authors: Nellore Abhinav , Collado-Torres Leonardo , Jaffe Andrew E , Alquicira-Hernández José , Pritt Jacob , Morton James , Leek Jeffrey T , Langmead Ben
Published: May 2015

RNA sequencing (RNA-seq) experiments now span hundreds to thousands of samples. Current spliced alignment software is designed to analyze each sample separately. Consequently, no information is gained from analyzing multiple samples together, and it is difficult to reproduce the exact analysis without access to original computing resources. We describe Rail-RNA, a cloud-enabled spliced aligner that analyzes many samples at once. Rail-RNA eliminates redundant work across samples, making it more efficient as samples are added. For many samples, Rail-RNA is more accurate than annotation-assisted aligners. We use Rail-RNA to align 667 RNA-seq samples from the GEUVADIS project on Amazon Web Services in under 16 hours for US$0.91 per sample. Rail-RNA produces alignments and base-resolution bigWig coverage files, ready for use with downstream packages for reproducible statistical analysis. We identify expressed regions in the GEUVADIS samples and show that both annotated and unannotated (novel) expressed regions exhibit consistent patterns of variation across populations and with respect to known confounders. Rail-RNA is open-source software available at http://rail.bio.
Bayesian Inference of Divergence Times and Feeding Evolution in Grey Mullets (Mugilidae)
Authors: Santini Francesco , May Michael R. , Carnevale Giorgio , Moore Brian R.
Published: May 2015

Grey mullets (Mugilidae, Ovalentariae) are coastal fishes found in near-shore environments of tropical, subtropical, and temperate regions within marine, brackish, and freshwater habitats throughout the world. This group is noteworthy both for the highly conserved morphology of its members—which complicates species identification and delimitation—and also for the uncommon herbivorous or detritivorous diet of most mullets. In this study, we first attempt to identify the number of mullet species, and then—for the resulting species—estimate a densely sampled time-calibrated phylogeny using three mitochondrial gene regions and three fossil calibrations. Our results identify two major subgroups of mullets that diverged in the Paleocene/Early Eocene, followed by an Eocene/Oligocene radiation across both tropical and subtropical habitats. We use this phylogeny to explore the evolution of feeding preference in mullets, which indicates multiple independent origins of both herbivorous and detritivorous diets within this group. We also explore correlations between feeding preference and other variables, including body size, habitat (marine, brackish, or freshwater), and geographic distribution (tropical, subtropical, or temperate). Our analyses reveal: (1) a positive correlation between trophic index and habitat (with herbivorous and/or detritivorous species predominantly occurring in marine habitats); (2) a negative correlation between trophic index and geographic distribution (with herbivorous species occurring predominantly in subtropical and temperate regions), and; (3) a negative correlation between body size and geographic distribution (with larger species occurring predominantly in subtropical and temperate regions).
Supramolecular organic frameworks of a Schiff base showing selective guest adsorption
Authors: Kong Jianfei , Du Jialei , Wang Jiren , Chen Zuofeng
Published: May 2015

A relatively simple molecule, N,N′-bis(3-methoxy-4-hydroxybenzylidene)-1,4-phenylenediamine, was synthesized and found to be a suitable building block to form different types of crystalline framework via hydrogen bonding. The porous frameworks show potential selectivity for uptake of small guest molecules.
A new simulation approach of genetic programming in modelling of soil water retention property of unsaturated soil
Authors: Garg Ankit , Garg Akhil , Zhou Wan-Huan , Tai Kang , Deo M C
Published: May 2015

Purpose

– For measuring the effect of crop root content on soil water retention curves (SWRC), a simulation approach (multi-gene genetic programming (MGGP)), which develops the model structure and its coefficients automatically can be applied. However, it does not perform well due to two vital issues related to its generalization: inappropriate formulation procedure of the multi-gene model and the difficulty in model selection. The purpose of this paper is to propose a heuristic-based-MGGP (N-MGGP) to formulate the functional relationship between the water content and two input parameters (soil suction and volumetric crop root content).

Design/methodology/approach

– A new simulation approach (heuristic-based-MGGP (N-MGGP)), was proposed to formulate the functional relationship between the water content and two input parameters (soil suction and volumetric crop root content). The proposed approach makes use of a statistical approach of stepwise regression and classification methods (Bayes naïve and artificial neural network (ANN)) to tackle the two issues. Simulated data obtained from the models was evaluated against the experimental data.

Findings

– The performance of proposed approach was found to better than that of standardized MGGP. Sensitivity and parametric analysis conducted validates the robustness of model by unveiling dominant input parameters and hidden non-linear relationships.

Originality/value

– To the best of authors’ knowledge, an empirical model is developed that measures the effect of crop root content on the SWRCs. The authors also proposed a new genetic programming approach in simulating the crop root content dependent SWRCs.
An adaptive SVR-HDMR model for approximating high dimensional problems
Authors: Huang Zhiyuan , Qiu Haobo , Zhao Ming , Cai Xiwen , Gao Liang
Published: May 2015

Purpose

– Popular regression methodologies are inapplicable to obtain accurate metamodels for high dimensional practical problems since the computational time increases exponentially as the number of dimensions rises. The purpose of this paper is to use support vector regression with high dimensional model representation (SVR-HDMR) model to obtain accurate metamodels for high dimensional problems with a few sampling points.

Design/methodology/approach

– High-dimensional model representation (HDMR) is a general set of quantitative model assessment and analysis tools for improving the efficiency of deducing high dimensional input-output system behavior. Support vector regression (SVR) method can approximate the underlying functions with a small subset of sample points. Dividing Rectangles (DIRECT) algorithm is a deterministic sampling method.

Findings

– This paper proposes a new form of HDMR by integrating the SVR, termed as SVR-HDMR. And an intelligent sampling strategy, namely, DIRECT method, is adopted to improve the efficiency of SVR-HDMR.

Originality/value

– Compared to other metamodeling techniques, the accuracy and efficiency of SVR-HDMR were significantly improved. The SVR-HDMR helped engineers understand the essence of underlying problems visually.
Solution of problems in dynamic elasticity via a mixed least squares method
Authors: Tchonkova Maria
Published: May 2015

Purpose

– The purpose of this paper is to present an original mixed least squares method for solving problems in dynamic elasticity.

Design/methodology/approach

– The proposed approach involves two different types of unknowns: velocities and stresses. The approximate solution to the dynamic elasticity equations is obtained via a minimization of a least squares functional, consisting of two terms: a term, which includes the squared residual of a weak form of the time rate of the constitutive relationships, expressed in terms of velocities and stresses, and a term, which depends on the squared residual of the equations of motion. At each time step the functional is minimized with respect to the velocities and stresses, which for the purpose of this study, are approximated by equal order piece-wise linear polynomial functions. The time discretization is based upon the backward Euler scheme. The displacements are computed from the obtained velocities in terms of a finite difference interpolation. The proposed theoretical formulation is given the general three-dimensional case and is tested numerically on the solution of one-dimensional wave equations.

Findings

– To test the performance of the method, it has been implemented in an original computer code, using object-oriented logic and written from scratch. Two one-dimensional problems from the mathematical physics, with well-known exact analytical solutions, have been solved. The numerical examples include a forced vibrating spring, fixed at its both ends and a rod, vibrating under its own weight, when one of its ends is fixed and the other is traction-free. The performed convergence study suggests that the method is convergent for both: velocities and stresses. The obtained results show excellent agreement between the exact and analytical solutions for displacement modes, velocities and stresses. It is observed that this method appears to be stable for the different mesh sizes and time step values.

Originality/value

– The mixed least squares formulation, described in this paper, serves as a basis for interesting future developments and applications to two and three-dimensional problems in dynamic elasticity.
Soret and Dufour effects in three-dimensional flow over an exponentially stretching surface with porous medium, chemical reaction and heat source/sink
Authors: Hayat Tasawar , Muhammad Taseer , Shehzad Sabir Ali , Alsaedi A.
Published: May 2015

Purpose

– The purpose of this paper is to study the Soret and Dufour effects in three-dimensional flow induced by an exponential stretching surface in a porous medium.

Design/methodology/approach

– Series solutions are developed.

Findings

– The authors observed that the temperature profile and thermal boundary layer thickness are enhanced when the authors increase the values of Dufour number. It is also examined that the concentration field and its associated boundary layer thickness are higher for the larger values of Soret number.

Originality/value

– Such investigation is not available in the literature.
Effects of width-to-depth ratio on heat transfer coefficient for gap
Authors: Huang Haiming , Huang Guo
Published: May 2015

Purpose

– The purpose of this paper is to perform the stimulation in order to examine the effects on the heat transfer coefficient and the flowfield properties at the vicinity of the gap due to variations in the width-to-depth ratio.

Design/methodology/approach

– The governing equations were discreted by using the finite volume method, and based on pressure-velocity coupled algorithm, the heat transfer coefficients outside and inside the gaps, defined by the width-to-depth ratio of 1, 2/3, 1/2, 1/3 and 1/4, were obtained by the Fluent software.

Findings

– The number of vortex inside the gap depends on the width-to-depth ratio, and the maximum value of the heat transfer coefficient emerges on the downstream surface.

Originality/value

– The study gives a feasible method to simulate the flowfield and the heat transfer inside the gap, which will help the design of the thermal protection system for reentry vehicles.
Numerical study of a thin film flow of fourth grade fluid
Authors: Rasheed Amer , Nawaz Rab , Khan Sohail Ahmed , Hanif Hanifa , Wahab Abdul
Published: May 2015

Purpose

– The purpose of this paper is to study the thin film flow of a fourth grade fluid subject to slip conditions in order to understand its velocity profile.

Design/methodology/approach

– An exact expression for flow velocity is derived in terms of hyperbolic sine functions. The practical usage of the exact flow velocity is restrictive as it involves very complicated integrals. Therefore, an approximate solution is also derived using a Galerkin finite element method and numerical error analysis is performed.

Findings

– The behavior of fluid velocity with respect to various flow parameters is discussed. The results are not restrictive to small values of flow parameters unlike those obtained earlier using homotopy analysis method and homotopy perturbation method.

Originality/value

– An approximate solution based on finite element technique is derived.
Towards broadband targets on the EU Digital Agenda 2020: discussion on the demand side of broadband policy
Authors: Kongaut Chatchai , Bohlin Erik
Published: May 2015

Purpose

– The purpose of this paper is to propose a guideline for the European Union (EU) to support high-speed broadband development based on economic frameworks and successful countries, Korea and Sweden. In the past decade, both policymakers and academic scholars have so far emphasised broadband policy mostly on the supply side. Increasing broadband adoption, nevertheless, is important for the EU to meet its Digital Agenda. Therefore, demand-side policy is also needed to stimulate high-speed broadband adoption in the EU.

Design/methodology/approach

– This paper applies frameworks of network externalities and the information and communications technology ecosystem to provide a better understanding of the relationship between supply- and demand-side policies. In addition, Korea and Sweden, which are two successful countries in high-speed broadband development particularly their demand-side policy, are chosen as a comparative case study.

Findings

– Both supply and demand sides are important to broadband policy to achieve the EU Digital Agenda 2020. It is also important for the policymakers to consider that demand-side policy should complement the implementation of supply-side policy, not substitute it. The demand side can be a great driver, especially with the development of content and applications for high-speed broadband.

Originality/value

– This paper fills the research gap on broadband policy on the demand side which is currently limited in comparison to the supply-side studies.
Acceptance of mobile money by poor citizens of India: integrating trust into the technology acceptance model
Authors: Chauhan Sumedha
Published: May 2015

Purpose

– The purpose of this paper is to understand the acceptance of mobile-money (m-money) among target populations, i.e. below-poverty-line citizens in India, using the technology acceptance model (TAM). The m-money service is a major initiative that can enable the provision of low-cost and speedy money transfer through mobile phones, especially in developing countries such as India. For a large section of the population in India, m-money can act as a way to achieve financial inclusion. However, for m-money to succeed, users should accept the initiative wholeheartedly.

Design/methodology/approach

– The survey data were collected from 225 actual and prospective m-money users and analysed using partial least square technique.

Findings

– The findings imply that the trust and the core constructs of TAM such as perceived usefulness, trust and attitude towards usage contribute in influencing the intention to accept m-money. Perceived ease of use neither impacts perceived usefulness nor attitude towards usage.

Practical implications

– This research also provides possible explanations for the significant relationships between the constructs and discusses how this information can be used to enhance the acceptance of m-money among poor Indians.

Originality/value

– This research is original and is based on primary data collection and its interpretation. It provides thorough empirical insights on the acceptance of m-money among poor Indian citizens which is currently a weakly addressed and empirically less explored area of research.