bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparisons among cultivars of wheat, hulless and hulled oats: Dry matter, N and P accumulation and partitioning as affected by N supply
Authors: Zhou Qing‐Ping , Kumar Biswas Dilip , Ma Bao‐Luo
Published: October 2013

A better understanding of the impact of fertilizer nitrogen (N) on biomass and N accumulation, and their partitioning into different plant components is needed to optimize crop yield and quality. A field experiment with spring wheat (Triticum aestivum), hulless (Avena nuda), and hulled (Avena sativa) oats was conducted for 3 years in Ottawa, ON, Canada, to determine the crop responses to N addition (0, 75, and 150 kg N ha–1). Biomass, N, and phosphorus (P) accumulation and partitioning into different plant components were examined during the growth season. Lodging score was determined for all crops when it occurred and again at harvest. During the growth season, both hulless and hulled oats and the wheat cultivar showed almost similar patterns of N and P accumulation with maximum contents at late grain filling or at harvest. Plant N concentration was up to 60 g kg–1 during the seedling stage, decreased gradually with advancing growth stages, and was lowest at harvest. Nitrogen treatments significantly increased plant N and P contents. At heading stage, N treatments enhanced dry matter (24%–45%), N (35%–135%), and P (27%–45%) contents in plant components (i.e., culm, leaf, and head), but also enhanced crop lodging, especially in oats. Both hulled and hulless oats had higher total plant N (5%–35%), N : P ratio, and dry‐matter content in leaf (6%–43%) and head (0%–129%) along with higher P (up to 27%) in culm than the wheat cultivar. The wheat cultivar accumulated greater dry matter and higher N content in kernels than both hulled and hulless oats at harvest. Both hulled and hulless oat cultivars exhibited similar lodging susceptibility to N addition (75 or 150 kg N ha–1), produced lower dry weight and lower kernel N, and hence lower grain yield than the wheat cultivar. The larger vegetative dry‐matter accumulation at heading coupled with higher P content in culms under high‐N‐supply conditions may be related to severe lodging in oat cultivars.
Biochar application to temperate soils: Effects on soil fertility and crop growth under greenhouse conditions
Authors: Kloss Stefanie , Zehetner Franz , Wimmer Bernhard , Buecker Jannis , Rempt Franziska , Soja Gerhard
Published: October 2013

Biochar (BC) application as a soil amendment has aroused much interest and was found to considerably improve soil nutrient status and crop yields on poor, tropical soils. However, information on the effect of BC on temperate soils is still insufficient, with effects expected to differ from tropical soils. We investigated the effects of BC on soil nutrient dynamics, crop yield, and quality in a greenhouse pot experiment. We compared three agricultural soils (Planosol, Cambisol, Chernozem), and BCs of three different feedstocks (wheat straw [WS], mixed woodchips [WC], vineyard pruning [VP]) slowly pyrolyzed at 525°C, of which the latter was also pyrolyzed at 400°C. The BCs were applied at two rates (1% and 3%, which would correspond to 30 and 90 t ha–1 in the field). Three crops, namely mustard (Sinapis alba L.), barley (Hordeum vulgare L.), and red clover (Trifolium pretense L.) were grown successively within one year. The investigated soil properties included pH, electrical conductivity (EC), cation‐exchange capacity (CEC), calcium‐acetate‐lactate (CAL)–extractable P (PCAL) and K (KCAL), C, N, and nitrogen‐supplying potential (NSP). The results show a pH increase in all soils. The CEC increased only on the Planosol. The C : N ratio increased at 3% application rate. Despite improving the soil nutrient status partly, yields of the first crop (mustard) and to a lesser extent of the second crop (barley) were significantly depressed through BC application (by up to 68%); the yield of clover as third crop was not affected. Only the BC from WS maintained yields in the range of the control and even increased barley yield by 6%. The initial yield reduction was accompanied by notable decreases (Cu, Fe, Mn, Zn) and increases (Mo) in micronutrient concentrations of plant tissues while nitrogen concentrations were hardly affected. The results of the pot experiment show that despite additional mineral fertilization, short‐term growth inhibition may occur when applying BC without further treatment to temperate soils.
High temperature wear testing of a Ni‐based superalloy pin on a cast iron disc
Authors: Rynio C. , Hattendorf H. , Klöwer J. , Lüdecke H.‐G. , Eggeler G.
Published: October 2013

A pin‐on‐disc wear test rig is described, which allows to extract reproducible mechanical and microstructural wear data from very small sample volumes at temperatures up to 900°C. The friction and wear behavior of Alloy 80A against a cast iron is evaluated at temperatures from ambient to 800°C. The wear rate of Alloy 80A decreased with increasing temperature. This was attributed to the development of protective tribolayers, which prevented a direct contact between the two sliding partners. Energy Dispersive X‐Ray (EDX) mapping of surface wear products and Transmission Electron Microscopy (TEM) results for the evolution of subsurface microstructures are exemplarily presented for wear experiments performed for 10 min at 300°C (frequency: 20 Hz, load: 20 N, stroke: 1 mm). EDX investigations provide a good insight into material transfers and oxide layer generations during sliding wear. TEM‐micrographs revealed cell structure formation and very small nanograins directly beneath the surface.
Insecticide‐induced hormesis and arthropod pest management
Authors: Guedes Raul Narciso C , Cutler G Christopher
Published: October 2013

Ecological backlashes such as insecticide resistance, resurgence and secondary pest outbreaks are frequent problems associated with insecticide use against arthropod pest species. The last two have been particularly important in sparking interest in the phenomenon of insecticide‐induced hormesis within entomology and acarology. Hormesis describes a biphasic dose–response relationship that is characterized by a reversal of response between low and high doses of a stressor (e.g. insecticides). Although the concept of insecticide‐induced hormesis often does not receive sufficient attention, or has been subject to semantic confusion, it has been reported in many arthropod pest species and natural enemies, and has been linked to pest outbreaks and potential problems with insecticide resistance. The study of hormesis remains largely neglected in entomology and acarology. Here, we examined the concept of insecticide‐induced hormesis in arthropods, its functional basis and potential fitness consequences, and its importance in arthropod pest management and other areas. © 2013 Society of Chemical Industry
TOPAAS: An Alternative Approach to Software Reliability Quantification
Authors: van Manen Sipke , Brandt Ed , van Ekris Jaap , Geurts Wouter
Published: October 2013

In the realm of safety related systems, a growing number of functions are realized by software, ranging from ‘firmware’ to autonomous decision‐taking software.

To support (political) real‐world decision makers, quantitative risk assessment methodology quantifies the reliability of systems. The optimal choice of safety measures with respect to the available budget, for example, the UK (as low as reasonably practicable approach), requires quantification. If a system contains software, some accepted methods on quantification of software reliability exist, but none of them is generally applicable, as we will show.

We propose a model bringing software into the quantitative risk assessment domain by introducing failure of software modules (with their probabilities) as basic events in a fault tree. The method is known as ‘TOPAAS’ (Task‐Oriented Probability of Abnormalities Analysis for Software). TOPAAS is a factor model allowing the quantification of the basic ‘software’ events in fault tree analyses. In this paper, we argue that this is the best approach currently available to industry.

Task‐Oriented Probability of Abnormalities Analysis for Software is a practical model by design and is currently put to field testing in risk assessments of programmable electronic safety‐related systems in tunnels and control systems of movable storm surge barriers in the Netherlands.

The TOPAAS model is constructed to incorporate detailed fields of knowledge and to provide focus toward reliability quantification in the form of a probability measure of mission failure. Our development also provides context for further in‐depth research. Copyright © 2013 John Wiley & Sons, Ltd.
Multidisciplinary Overview of Vaginal Atrophy and Associated Genitourinary Symptoms in Postmenopausal Women
Authors: Goldstein Irwin , Dicks Brian , Kim Noel N. , Hartzell Rose
Published: October 2013

Introduction

Vaginal atrophy, which may affect up to 45% of postmenopausal women, is often associated with one or more urinary symptoms, including urgency, increased frequency, nocturia, dysuria, incontinence, and recurrent urinary tract infection.

Aims

To provide an overview of the current literature regarding cellular and clinical aspects of vaginal atrophy and response to treatment with local vaginal estrogen therapy.

Methods

PubMed searches through February 2012 were conducted using the terms “vaginal atrophy,” “atrophic vaginitis,” and “vulvovaginal atrophy.” Expert opinion was based on review of the relevant scientific and medical literature.

Main Outcome Measure

Genitourinary symptoms and treatment of vaginal atrophy from peer-reviewed published literature.

Results

Typically, a diagnosis of vaginal atrophy is made based on patient-reported symptoms, including genitourinary symptoms, and an examination that reveals signs of the disorder; however, many women are hesitant to report vaginal-related symptoms, primarily because of embarrassment.

Conclusions

Physicians in various disciplines are encouraged to initiate open discussions about vulvovaginal health with postmenopausal women, including recommended treatment options.
State of the Art of Robotic Thymectomy
Authors: Ismail Mahmoud , Swierzy Marc , Rückert Jens C.
Published: October 2013

Background

Thymectomy is a widely accepted treatment for most cases of myasthenia gravis and essential for the treatment of thymoma. The development of a minimally invasive procedure for thymectomy resulted in a variety of approaches for surgery on the thymic gland. The use of thoracoscopy‐based techniques has continued to increase, including the latest advance in this field, robotic thymectomy.

Methods

We review the rapid development and actual use of this approach by examining published reports, worldwide registries, and personal communications and by analyzing our database, which is the largest single‐center experience and contains 317 thymectomies until 12/2012. The technical modifications of robotic thymectomy are also described.

Results

Since 2001, approximately 3,500 robotic thymectomies have been registered worldwide. Meanwhile, the results of approximately 500 thymectomy cases have been published. Robotic thymectomy is performed most frequently through a standardized unilateral three‐trocar approach. All reports describe promising and satisfactory results for myasthenia gravis. For early‐stage thymoma, robotic thymectomy is a technically sound and safe procedure with a very low complication rate and short hospital stay. Oncological outcome without recurrences is promising, but a longer follow‐up is needed.

Conclusion

The unilateral robotic technique can be considered an adequate approach for thymectomy, even with demanding anatomical configurations. Robotic thymectomy has spread worldwide over the last decade because of the promising results in myasthenia gravis and thymoma patients.
Dimeric peptides of the C‐terminal region of CXCL14 function as CXCL12 inhibitors
Authors: Tanegashima Kosuke , Tsuji Kohei , Suzuki Kenji , Shigenaga Akira , Otaka Akira , Hara Takahiko
Published: October 2013

We recently reported that CXCL14 binds to CXCR4 with high affinity and inhibits CXCL12‐mediated chemotaxis. Here we found that the C‐terminal 51–77 amino acid residues of CXCL14 are responsible for CXCR4 binding. A disulfide dimer peptide of CXCL14(51–77) bound to CXCR4 with comparable affinity to full length CXCL14, and exhibited CXCL12 inhibitor activity. CXCR4 was efficiently internalized upon binding of dimeric CXCL14(51–77), thereby being reduced on the cell surface. Substitution of 5 amino acid residues in combination with the use of an oxime linker for dimerization increased the solubility and chemical stability of the dimeric CXCL14(51–77).
New correlation formulae for the straight section of the electrospun jet from a polymer drop
Authors: Sahay R. , Teo C. J. , Chew Y. T.
Published: October 2013

An electrospun polymer jet issued from a Taylor cone follows a straight-line motion before experiencing electrical bending instability resulting in curling and spiralling of the jet in three-dimensional space. Experiments are performed to characterize the fluid dynamics of an electrospun polymer jet. Appropriate image processing is performed to systematically analyse flow regimes of the electrospun jet. These regimes include Taylor cone formation/jet initiation and the straight section of the jet. Dimensional analysis was performed to identify the salient dimensionless parameters, which govern the electrospun jet characteristics. Three new correlation formulae were obtained to characterize the dimensionless jet diameter at the apex of the Taylor cone $(\tilde {d} = 1. 03{\tilde {Q} }^{0. 44} )$, the dimensionless jet diameter at different locations along the jet’s straight section $(\tilde {d} {\tilde {z} }^{1/ 4} = 1. 09{\tilde {Q} }^{1/ 2} )$, as well as the length of the straight section of the jet $({\tilde {Z} }_{in} = 86{\tilde {Q} }^{0. 42} )$. These correlation formulae are valid for the analysed range of dimensionless flow rates $(2. 6{{\times 10}}^{- 4} \lt \tilde {Q} \lt 3. 6{{\times 10}}^{7} )$ and dimensionless electric fields $(7. 4{{\times 10}}^{- 4} \lt \tilde {E} \lt 1. 4{{\times 10}}^{- 1} )$. In addition, the correlation formulae are valid for the analysed range of Deborah numbers De and Reynolds numbers Re based on nozzle radius, $3. 3\times {10}^{- 7} \lt {\mathit{De}}_{{r}_{o} } \lt 3. 8\times {10}^{- 2} $ and $5. 8\times {10}^{- 4} \lt {\mathit{Re}}_{{r}_{o} } \lt 7. 0\times {10}^{- 1} $. The proposed new correlation formulae are instrumental in the design as well as controlled manipulation/optimization of the electrospinning phenomenon.
Estimating population sizes of lions Panthera leo and spotted hyaenas Crocuta crocuta in Uganda's savannah parks, using lure count methods
Authors: Omoya Edward Okot , Mudumba Tutilo , Buckland Stephen T. , Mulondo Paul , Plumptre Andrew J.
Published: October 2013

Despite > 60 years of conservation in Uganda's national parks the populations of lions and spotted hyaenas in these areas have never been estimated using a census method. Estimates for some sites have been extrapolated to other protected areas and educated guesses have been made but there has been nothing more definitive. We used a lure count analysis method of call-up counts to estimate populations of the lion Panthera leo and spotted hyaena Crocuta crocuta in the parks where reasonable numbers of these species exist: Queen Elizabeth Protected Area, Murchison Falls Conservation Area and Kidepo Valley National Park. We estimated a total of 408 lions and 324 hyaenas for these three conservation areas. It is unlikely that other conservation areas in Uganda host > 10 lions or > 40 hyaenas. The Queen Elizabeth Protected Area had the largest populations of lions and hyaenas: 140 and 211, respectively. It is estimated that lion numbers have declined by 30% in this protected area since the late 1990s and there are increasing concerns for the long-term viability of both species in Uganda.
The Embodied Nature of Motor Imagery Processes Highlighted by Short-Term Limb Immobilization
Authors: Meugnot Aurore , Almecija Yves , Toussaint Lucette
Published: October 2013

We investigated the embodied nature of motor imagery processes through a recent use-dependent plasticity approach, a short-term limb immobilization paradigm. A splint placed on the participants’ left-hand during a brief period of 24 h was used for immobilization. The immobilized participants performed two mental rotation tasks (a hand mental rotation task and a number mental rotation task) before (pre-test) and immediately after (post-test) the splint removal. The control group did not undergo the immobilization procedure. The main results showed an immobilization-induced effect on left-hand stimuli, resulting in a lack of task-repetition benefit. By contrast, accuracy was higher and response times were shorter for right-hand stimuli. No immobilization-induced effects appeared for number stimuli. These results revealed that the cognitive representation of hand movements can be modified by a brief period of sensorimotor deprivation, supporting the hypothesis of the embodied nature of motor simulation processes.
Elevated CNS Inflammation in Patients with Preclinical Alzheimer's Disease
Authors: Monson Nancy L , Ireland Sara J , Ligocki Ann J , Chen Ding , Rounds William H , Li Min , Huebinger Ryan M , Munro Cullum C , Greenberg Benjamin M , Stowe Ann M , Zhang Rong
Published: October 2013

Alzheimer's disease (AD) is a progressive, neurodegenerative disease that may involve inflammatory responses in the central nervous system (CNS). Our objective was to determine whether patients with amnestic mild cognitive impairment (aMCI), a preclinical stage of AD, have inflammatory characteristics similar to patients with multiple sclerosis (MS), a known CNS inflammatory disease. The frequency of lymphocytes and levels of pro-inflammatory cytokines in the cerebrospinal fluid of aMCI patients was comparable to MS patients or patients at high risk to develop MS. Thus, brain inflammation occurs early at the preclinical stage of AD and may have an important role in pathology.
Cardiovascular Disease: The Other Face of Diabetes
Authors: Vlasakakis G , Della Pasqua O
Published: October 2013

Despite glycemic control, evidence suggests that mortality and morbidity remain high in diabetes. Regulatory agencies deem, therefore, additional safety trials necessary for the approval of new antidiabetic drugs. Nevertheless, markers of cardiovascular risk, which can be used as response predictors, are not available. In contrast with current efforts on further understanding of glucose–insulin homeostasis, a model‐based approach is required to assess the correlation between hyperglycemia and cardiometabolic phenotypes, enabling prediction of the underlying cardiovascular risk.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e81; doi:10.1038/psp.2013.57; advance online publication 23 October 2013
Isolation and characterization of a novel wheat cysteine-rich receptor-like kinase gene induced by Rhizoctonia cerealis
Authors: Yang Kun , Rong Wei , Qi Lin , Li Jiarui , Wei Xuening , Zhang Zengyan
Published: October 2013

Cysteine-rich receptor kinases (CRKs) belong to the receptor-like kinase family. Little is known about CRK genes in wheat. We isolated a wheat CRK gene TaCRK1 from Rhizoctonia cerealis-resistant wheat CI12633 based on a differentially expressed sequence identified by RNA-Sequencing (RNA-Seq) analysis. TaCRK1 was more highly expressed in CI12633 than in susceptible Wenmai 6. Transcription of TaCRK1 in wheat was induced in CI12633 after R. cerealis infection and exogenous abscisic acid (ABA) treatment. The deduced TaCRK1 protein contained a signal peptide, two DUF26 domains, a transmembrane domain and a serine/threonine protein kinase domain. Transient expression of a green fluorescence protein fused with TaCRK1 in wheat and onion indicated that TaCRK1 may localize to plasma membranes. Characterization of TaCRK1 silencing induced by virus-mediated method in CI12633 showed that the downregulation of TaCRK1 transcript did not obviously impair resistance to R. cerealis. This study paves the way to further CRK research in wheat.
Linear complexity of binary sequences with interleaved structure
Authors: Xiong Hai , Qu Longjiang , Li Chao , Fu Shaojing
Published: October 2013

In this study, the minimal polynomials and the linear complexity of interleaved binary sequences are investigated. Both the linear complexity and the minimal polynomials of low correlation zone sequences constructed by Zhou et al. are completely determined. Besides, an open problem proposed by Li and Tang is discussed. At last, a sufficient condition and a necessary condition are presented about when the linear complexity of the interleaved sequences constructed by Tang et al. attains the maximum.
Identification of non‐linear stochastic spatiotemporal dynamical systems
Authors: Ning Hanwen , Jing Xingjian , Cheng Li
Published: October 2013

A systematic identification method for non‐linear stochastic spatiotemproal (SST) systems described by non‐linear stochastic partial differential equations (SPDEs) is investigated in this study based on pointwise observation data. A theoretical framework for a semi‐finite element model approximating to an infinite‐dimensional system is established, and several fundamental issues are discussed including the approximation error between the underlying infinite‐dimensional dynamics and the model to be identified, and its rationality etc. Based on the proposed theoretical framework, a general identification method with irregular observation data is provided. These results not only provide an effective method for the identification of non‐linear SST systems using measurement data (both offline and online), but also demonstrate a potential solution for the analysis, design and control of non‐linear SST systems from a numerical point of view.
Performance analysis of contention‐based access periods and service periods of 802.11ad hybrid medium access control
Authors: Hemanth C. , Venkatesh T.G.
Published: October 2013

In this study, the authors present an analytical model for the contention‐based access periods (CBAPs) and service periods (SPs) as specified in the medium access control (MAC) layer of IEEE 802.11ad standards. The analytical model for CBAP is based on a two‐dimensional Markov chain which captures the hybrid nature of IEEE 802.11ad MAC. The Markov chain is used to obtain important metrics like MAC throughput and average frame service time. The SPs are modelled as a M/G/1 queueing system with vacations. Using this model, the delay experienced by packets is calculated. The accuracy of the analytical models is established by extensive simulation results. A brief insight into optimal allocation of SP and CBAP is also discussed.
Data‐driven technique for interpreting wind turbine condition monitoring signals
Authors: Yang Wenxian , Little Christian , Tavner Peter J. , Court Richard
Published: October 2013

Increasing deployment of large wind turbines (WT) offshore and in remote areas requires reliable condition monitoring (CM) techniques to guarantee the high availability of these WTs and economic return. To meet this need, much effort has been expended to improve the capability of analysing the WT CM signals. However, a fully satisfactory technique has not been achieved today. One of the major reasons is that the developed techniques still cannot provide accurate interpretation of the WT CM signals, which are usually non‐linear and non‐stationary in nature because of the constantly varying loads and non‐linear operations of the turbines. To deal with this issue, a new data‐driven signal processing technique is developed in this study based on the concepts of intrinsic time‐scale decomposition (ITD) and energy operator separation algorithm (EOSA). The advantages of the proposed technique over the traditional data‐driven techniques have been demonstrated and validated experimentally. It has been shown that in comparison with the Hilbert–Huang transform the combination of ITD and EOSA provided more accurate and explicit presentations of the instantaneous information of the signals tested. Thus, it provides a much improved offline tool for accurately interpreting WT CM signals.
The Effect of a Cyclooxygenase 2 Inhibitor on Early Degenerated Human Nucleus Pulposus Explants
Authors: van Dijk Bart , Potier Esther , Licht Ruud , Creemers Laura , Ito Keita
Published: October 2013

Study Design

Preclinical in vitro culture of human degenerated nucleus pulposus (NP) tissue.

Objective

Cyclooxygenase 2 inhibitors (e.g., celecoxib) inhibit prostaglandin E2 (PGE2) production, and they have been shown to upregulate regeneration of articular cartilage. In this study, we developed an explant culture system for use with human tissue and tested the potential of celecoxib.

Methods

NP explants were cultured with or without 1 μM of celecoxib and were analyzed at days 0 and 7 for biochemical content (water, sulfated glycosaminoglycans, hydroxyproline, and DNA), gene expression (for disk matrix anabolic and catabolic markers), and PGE2 content.

Results

Water and biochemical contents as well as gene expression remained close to native values after 1 week of culture. PGE2 levels were not increased in freshly harvested human NP tissue and thus were not reduced in treated tissues. Although no anabolic effects were observed at the dosage and culture duration used, no detrimental effects were observed and some specimens did respond by lowering PGE2.

Conclusions

Human degenerated NP explants were successfully cultured in a close to in vivo environment for 1 week. Further research, especially dosage-response studies, is needed to understand the role of PGE2 in low back pain and the potential of celecoxib to treat painful disks.
Near-wall turbulence
Authors: Jiménez Javier
Published: October 2013

The current state of knowledge about the structure of wall-bounded turbulent flows is reviewed, with emphasis on the layers near the wall in which shear is dominant, and particularly on the logarithmic layer. It is shown that the shear interacts with scales whose size is larger than about one third of their distance to the wall, but that smaller ones, and in particular the vorticity, decouple from the shear and become roughly isotropic away from the wall. In the buffer and viscous layers, the dominant structures carrying turbulent energy are the streamwise velocity streaks, and the vortices organize both the dissipation and the momentum transfer. Farther from the wall, the velocity remains organized in streaks, although much larger ones than in the buffer layer, but the vortices lose their role regarding the Reynolds stresses. That function is taken over by wall-attached turbulent eddies with sizes and lifetimes proportional to their heights. Two kinds of eddies have been studied in some detail: vortex clusters, and ejections and sweeps. Both can be classified into a detached background, and a geometrically self-similar wall-attached family. The latter is responsible for most of the momentum transfer, and is organized into composite structures that can be used as models for the attached-eddy hierarchy hypothesized by Townsend [“Equilibrium layers and wall turbulence,” J. Fluid Mech. 11, 97–120 (1961)]. The detached component seems to be common to many turbulent flows, and is roughly isotropic. Using a variety of techniques, including direct tracking of the structures, it is shown that an important characteristic of wall-bounded turbulence is temporally intermittent bursting, which is present at all distances from the wall, and in other shear flows. Its properties and time scales are reviewed, and it is shown that bursting is an important part of the production of turbulent energy from the mean shear. It is also shown that a linearized model captures many of its characteristics.
Spanwise velocity component in nonlinear region of Görtler vortices
Authors: Tandiono T. , Winoto S. H. , Shah D. A.
Published: October 2013

The spanwise velocity component of Görtler vortices in a concave surface boundary layer flow was experimentally studied by means of hot-wire anemometer measurements. For this purpose, the wavelength of the Görtler vortices was pre-set to the most amplified wavelength of 12 mm at free-stream velocity of 2.8 m/s, by a series of thin perturbation wires placed near to the concave surface leading edge. The streamwise and spanwise velocity components, respectively, u and w, in the nonlinear region of Görtler vortices were measured using an X-wire probe. The secondary motion induced by the free-stream disturbances in the vortex's head region is observed to be amplified by the appearance of secondary instability. The ∂w/∂y iso-shear contours form alternate positive and negative shear layers across the boundary layer in the upwash region. On the other hand, two pairs of anti-symmetric structures are observed in the ∂w/∂z iso-shear contours near the wall and vortex's head. The $\overline {w^{\prime 2 }}$w′2¯ contours have two intense regions at the stem and head of the vortex structures. The most unstable characteristic frequency of secondary instability is found exactly at the maxima of the contours. The Reynolds shear stress $-\overline {u^{\prime} w ^{\prime}}$−u′w′¯ contour is anti-symmetric in z-direction about the upwash with a pair of two intense regions of positive and negative shears at both the stem and head of the vortices. The $ - \overline {u^{\prime} w^{\prime} } \partial u/\partial z$−u′w′¯∂u/∂z contours reveal that the energy conversion mechanism occurs intensely on the sides of the vortex's stem.
A realizable explicit algebraic Reynolds stress model for compressible turbulent flow with significant mean dilatation
Authors: Grigoriev I. A. , Wallin S. , Brethouwer G. , Johansson A. V.
Published: October 2013

The explicit algebraic Reynolds stress model of Wallin and Johansson [J. Fluid Mech. 403, 89 (2000)] is extended to compressible and variable-density turbulent flows. This is achieved by correctly taking into account the influence of the mean dilatation on the rapid pressure-strain correlation. The resulting model is formally identical to the original model in the limit of constant density. For two-dimensional mean flows the model is analyzed and the physical root of the resulting quartic equation is identified. Using a fixed-point analysis of homogeneously sheared and strained compressible flows, we show that the new model is realizable, unlike the previous model. Application of the model together with a K − ω model to quasi one-dimensional plane nozzle flow, transcending from subsonic to supersonic regime, also demonstrates realizability. Negative “dilatational” production of turbulence kinetic energy competes with positive “incompressible” production, eventually making the total production negative during the spatial evolution of the nozzle flow. Finally, an approach to include the baroclinic effect into the dissipation equation is proposed and an algebraic model for density-velocity correlations is outlined to estimate the corrections associated with density fluctuations. All in all, the new model can become a significant tool for CFD (computational fluid dynamics) of compressible flows.
Electro-entropic excluded volume effects on DNA looping and relaxation in nanochannels
Authors: Chen Yeng-Long
Published: October 2013

We investigate the fluctuation-relaxation dynamics of entropically restricted DNA molecules in square nanochannels ranging from 0.09 to 19.9 times the persistence length. In nanochannels smaller than the persistence length, the chain relaxation time is found to have cubic dependence on the channel size. It is found that the effective polymer width significantly alter the chain conformation and relaxation time in strong confinement. For thinner chains, looped chain configurations are found in channels with height comparable to the persistence length, with very slow relaxation compared to un-looped chains. Larger effective chain widths inhibit the formation of hairpin loops.
Large enhancement of nonlinear terahertz absorption in intrinsic GaAs by plasmonic nano antennas
Authors: Jeong Young-Gyun , Paul Michael J. , Kim Seung-Hyun , Yee Ki-Ju , Kim Dai-Sik , Lee Yun-Shik
Published: October 2013

We demonstrate remarkably strong nonlinear terahertz (THz) effects in an intrinsic GaAs wafer patterned with a nanometer-width slot antenna array. The antenna near-field reaches 20 MV/cm due to the huge field enhancement in the plasmonic nano-structure (field enhancement factor, α ≅ 50). The THz fields are strong enough to generate high density free carriers (Ne > 1017 cm−3) via interband excitations associated with impact ionizations and thus to induce large absorption of the THz radiation (>35%). The nonlinear THz interactions take place in the confined region of nanometer-scale layer adjacent to the antenna.
A perfect metamaterial polarization rotator
Authors: Cong Longqing , Cao Wei , Zhang Xueqian , Tian Zhen , Gu Jianqiang , Singh Ranjan , Han Jiaguang , Zhang Weili
Published: October 2013

Polarization conveys valuable information for electromagnetic signal processing exhibiting tremendous potential in developing application driven photonic devices. Manipulation of polarization state of an electromagnetic wave has drawn a lot of research interests in many different fields, especially in the terahertz regime. Here, we propose a unique approach to efficiently rotate the linear polarization of terahertz wave in a broadband configuration with tri-layer metasurfaces. We experimentally observe a nearly perfect orthogonal polarization conversion with an ultrahigh efficiency, demonstrating a ultrathin terahetz rotator. The Fabry-Perot cavity effect in the tri-layer metasurfaces is attributed to the underlying mechanism of high transmittance and polarization rotation.
Influence of crystal mosaicity on axial channeling effects and lattice site determination of impurities
Authors: De Vries B. , Wahl U. , Ruffenach S. , Briot O. , Vantomme A.
Published: October 2013

Using the electron emission channeling and Rutherford backscattering/channeling techniques, the influence of the mosaicity of a thin film on the axial channeling of charged particles was investigated. It is found that crystal mosaicity leads to a broadening and a degradation of the experimental channeling effects. This phenomenon, which is shown to be of major importance when assessing the lattice site of impurities in a single crystal, can be modeled quantitatively by using the mosaic tilt and twist components derived from X-ray rocking curve scans. As a case study, we illustrate that our approach allows to accurately determine the lattice site of Er in AlN, despite the significant influence of mosaicity on the channeling measurements.
What is a representative brain? Neuroscience meets population science
Authors: Falk Emily B. , Hyde Luke W. , Mitchell Colter , Faul Jessica , Gonzalez Richard , Heitzeg Mary M. , Keating Daniel P. , Langa Kenneth M. , Martz Meghan E. , Maslowsky Julie , Morrison Frederick J. , Noll Douglas C. , Patrick Megan E. , Pfeffer Fabian T. , Reuter-Lorenz Patricia A. , Thomason Moriah E. , Davis-Kean Pamela , Monk Christopher S. , Schulenberg John
Published: October 2013

The last decades of neuroscience research have produced immense progress in the methods available to understand brain structure and function. Social, cognitive, clinical, affective, economic, communication, and developmental neurosciences have begun to map the relationships between neuro-psychological processes and behavioral outcomes, yielding a new understanding of human behavior and promising interventions. However, a limitation of this fast moving research is that most findings are based on small samples of convenience. Furthermore, our understanding of individual differences may be distorted by unrepresentative samples, undermining findings regarding brain–behavior mechanisms. These limitations are issues that social demographers, epidemiologists, and other population scientists have tackled, with solutions that can be applied to neuroscience. By contrast, nearly all social science disciplines, including social demography, sociology, political science, economics, communication science, and psychology, make assumptions about processes that involve the brain, but have incorporated neural measures to differing, and often limited, degrees; many still treat the brain as a black box. In this article, we describe and promote a perspective—population neuroscience—that leverages interdisciplinary expertise to (i) emphasize the importance of sampling to more clearly define the relevant populations and sampling strategies needed when using neuroscience methods to address such questions; and (ii) deepen understanding of mechanisms within population science by providing insight regarding underlying neural mechanisms. Doing so will increase our confidence in the generalizability of the findings. We provide examples to illustrate the population neuroscience approach for specific types of research questions and discuss the potential for theoretical and applied advances from this approach across areas.
Dynamics of dendritic spines in the mouse auditory cortex during memory formation and memory recall
Authors: Moczulska Kaja Ewa , Tinter-Thiede Juliane , Peter Manuel , Ushakova Lyubov , Wernle Tanja , Bathellier Brice , Rumpel Simon
Published: October 2013

Significance

Memories are believed to be stored as long-lasting structural changes in synapses. We tested the hypothesis that formation of a tone-shock association induces changes in the mouse auditory cortex by combining chronic in vivo imaging of dendritic spines with auditory fear conditioning. We find that memory formation is correlated with a transient increase in spine formation that leaves a long-lasting trace in the network. Memory recall does not lead to a recapitulation of structural remodeling as observed during initial memory formation. Our findings provide a potential synaptic mechanism underlying previously reported functional changes in auditory cortex following fear conditioning and challenge models in which memory traces are modified upon memory retrieval.
Learning to Spell from Reading: General Knowledge about Spelling Patterns Influences Memory for Specific Words
Authors: Pacton Sébastien , Borchardt Gaëlle , Treiman Rebecca , Lété Bernard , Fayol Michel
Published: October 2013

Adults often learn to spell words during the course of reading for meaning, without intending to do so. We used an incidental learning task in order to study this process. Spellings that contained double n, r and t which are common doublets in French, were learned more readily by French university students than spellings that contained less common but still legal doublets. When recalling or recognizing the latter, the students sometimes made transposition errors, doubling a consonant that often doubles in French rather than the consonant that was originally doubled (e.g., tiddunar recalled as tidunnar). The results, found in three experiments using different nonwords and different types of instructions, show that people use general knowledge about the graphotactic patterns of their writing system together with word-specific knowledge to reconstruct spellings that they learn from reading. These processes contribute to failures and successes in memory for spellings, as in other domains.
An improved error bound for reduced basis approximation of linear parabolic problems
Authors: Urban Karsten , Patera Anthony
Published: October 2013

We consider a space-time variational formulation for linear parabolic partial differential equations. We introduce an associated Petrov-Galerkin truth finite element discretization with favorable discrete inf-sup constant

β

δ

\beta _{\delta }

, the inverse of which enters into error estimates:

β

δ

\beta _{\delta }

is unity for the heat equation;

β

δ

\beta _{\delta }

decreases only linearly in time for non-coercive (but asymptotically stable) convection operators. The latter in turn permits effective long-time a posteriori error bounds for reduced basis approximations, in sharp contrast to classical (pessimistic) exponentially growing energy estimates. The paper contains a full analysis and various extensions for the formulation introduced briefly by Urban and Patera (2012) as well as numerical results for a model reaction-convection-diffusion equation.
The dependence of stellar age distributions on giant molecular cloud environment
Authors: Dobbs C. L. , Pringle J. E. , Naylor T.
Published: October 2013

In this Letter, we analyse the distributions of stellar ages in giant molecular clouds (GMCs) in spiral arms, interarm spurs and at large galactic radii, where the spiral arms are relatively weak. We use the results of numerical simulations of galaxies, which follow the evolution of GMCs and include star particles where star formation events occur. We find that GMCs in spiral arms tend to have predominantly young (<10 Myr) stars. By contrast, clouds which are the remainders of spiral arm giant molecular asssociations that have been sheared into interarm GMCs contain fewer young (<10 Myr) stars and more ∼20 Myr stars. We also show that clouds which form in the absence of spiral arms, due to local gravitational and thermal instabilities, contain preferentially young stars. We propose that the age distributions of stars in GMCs will be a useful diagnostic to test different cloud evolution scenarios, the origin of spiral arms and the success of numerical models of galactic star formation. We discuss the implications of our results in the context of Galactic and extragalactic molecular clouds.
Context-dependent expression of sperm quality in the fruitfly
Authors: Decanini Daniel Paz , Wong Bob B. M. , Dowling Damian K.
Published: October 2013

In most species, females mate multiply within a reproductive cycle, invoking post-copulatory selection on ejaculatory components. Much research has focused on disentangling the key traits important in deciding the outcomes of sperm competition and investigating patterns of covariance among these traits. Less attention has focused on the degree to which such patterns might be context-dependent. Here, we examine whether the expression of sperm viability—a widely used measure of sperm quality—and patterns of covariance between this trait and male reproductive morphologies, change across distinct age classes and across naturally occurring genotypes, when expressed in both heterozygotic (extreme outbred) and homozygotic (extreme inbred) states in the fruitfly
Drosophila melanogaster
. Older males, and heterozygous males, generally exhibited higher sperm viability. The male age effect seems at least partly explained by a positive association between sperm numbers and viability. First, old males possessed more stored sperm than young males, and second, sperm numbers and viability were also positively associated within each age class. Furthermore, we found a positive association between sperm viability and testis size, but only among heterozygous, old males. These results suggest that sperm quality is a labile trait, with expression levels that are context-dependent and shaped by multiple, potentially interacting, factors.
Sperm storage mediated by cryptic female choice for nuptial gifts
Authors: Albo Maria J. , Bilde Trine , Uhl Gabriele
Published: October 2013

Polyandrous females are expected to discriminate among males through postcopulatory cryptic mate choice. Yet, there is surprisingly little unequivocal evidence for female-mediated cryptic sperm choice. In species in which nuptial gifts facilitate mating, females may gain indirect benefits through preferential storage of sperm from gift-giving males if the gift signals male quality. We tested this hypothesis in the spider
Pisaura mirabilis
by quantifying the number of sperm stored in response to copulation with males with or without a nuptial gift, while experimentally controlling copulation duration. We further assessed the effect of gift presence and copulation duration on egg-hatching success in matings with uninterrupted copulations with gift-giving males. We show that females mated to gift-giving males stored more sperm and experienced 17% higher egg-hatching success, compared with those mated to no-gift males, despite matched copulation durations. Uninterrupted copulations resulted in both increased sperm storage and egg-hatching success. Our study confirms the prediction that the nuptial gift as a male signal is under positive sexual selection by females through cryptic sperm storage. In addition, the gift facilitates longer copulations and increased sperm transfer providing two different types of advantage to gift-giving in males.
Ocean acidification and host–pathogen interactions: blue mussels, Mytilus edulis, encountering Vibrio tubiashii
Authors: Asplund Maria E. , Baden Susanne P. , Russ Sarah , Ellis Robert P. , Gong Ningping , Hernroth Bodil E.
Published: October 2013

Ocean acidification (OA) can shift the ecological balance between interacting organisms. In this study, we have used a model system to illustrate the interaction between a calcifying host organism, the blue mussel Mytilus edulis and a common bivalve bacterial pathogen, Vibrio tubiashii, with organisms being exposed to a level of acidification projected to occur by the end of the 21st century. OA exposures of the mussels were carried out in relative long‐term (4 months) and short‐term (4 days) experiments. We found no effect of OA on the culturability of V. tubiashii, in broth or in seawater. OA inhibited mussel shell growth and impaired crystalline shell structures but did not appear to affect mussel immune parameters (i.e haemocyte counts and phagocytotic capacity). Despite no evident impact on host immunity or growth and virulence of the pathogen, V. tubiashii was clearly more successful in infecting mussels exposed to long‐term OA compared to those maintained under ambient conditions. Moreover, OA exposed V. tubiashii increased their viability when exposed to haemocytes of OA‐treated mussel. Our findings suggest that even though host organisms may have the capacity to cope with periods of OA, these conditions may alter the outcome of host–pathogen interactions, favouring the success of the latter.
Insights on the regulation of the phenylacetate degradation pathway from Escherichia coli
Authors: Fernández Cristina , Díaz Eduardo , García José Luis
Published: October 2013

The paa genes for phenylacetic acid (PA) catabolism encode the best characterized aerobic hybrid route involved in the bacterial degradation of aromatic compounds. Here, we demonstrate that the divergent paaZ and paaA‐K catabolic operons of Escherichia coli are regulated by two genes, paaXY, that form a distinct transcriptional unit driven by the Px promoter. In vivo and in vitro approaches using purified PaaX regulatory protein revealed that this regulator is able to bind and inhibit the activity of Px in a phenylacetyl‐coenzyme A (PA‐CoA) dependent manner. The autoregulation of paaXY is due to the competition between PaaX and RNA polymerase for binding to the regulatory Px promoter. Whereas a similar mechanism of repression mediated by PaaX was shown to occur at the catabolic Pz promoter; the catabolic Pa promoter is inhibited by PaaX by a mechanism that does not involves competition with RNA polymerase. We have shown for the first time that the paaY gene product is essential for an efficient growth in PA. Purified PaaY was shown to be a trimer in solution with a broad thioesterase activity stimulated by some metals. This thioesterase activity will allow the detoxification of some CoA‐intermediates that block the aerobic catabolism of PA, as previously suggested, but also will avoid the accumulation of some CoA derivatives that could behave as antagonists of the inducer effect caused by PA‐CoA on the PaaX repressor for an efficient expression of the paa genes. This regulatory function mediated by PaaY constitutes an additional regulatory checkpoint that makes the circuit that controls the transcription of the paa genes more complex than previously thought, and it could represent a general strategy present in most bacterial paa gene clusters that also harbour the paaY gene.