bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of a neutral pectin lyase produced by Oidiodendron echinulatum MTCC 1356 in solid state fermentation
Authors: Yadav Sangeeta , Dubey Amit Kumar , Anand Gautam , Yadav Dinesh
Published: February 2012

A neutral pectin lyase produced by a new fungal strain Oidiodendron echinulatum MTCC 1356 under solid state fermentation using wheat bran as agro waste has been studied. The enzyme was purified by ammonium sulphate precipitation (30–60%), DEAE anion exchange and Sephadex G‐100 column chromatographies. The SDS‐PAGE and native PAGE revealed two bands of sizes 42 and 47 kDa. The enzyme was purified 37 fold with specific activity of 4.5 U/mg and 2.25% yield. The Km and Vmax values determined using citrus pectin were 1.2 mg/ml and 0.36 IU/min respectively. The pH and temperature optima were pH 7.0 and 50 °C, respectively. The pH stability was around 5.0 for 24 h at 20 °C. The purified enzyme retained maximum activity for 30 min upto 50 °C. The activation energy for thermal denaturation of the purified enzyme was found to be 60.0 kJ/Mol. The effects of various metal ions and protein inhibitors on enzyme activity have revealed total inhibition of the enzyme activity in the presence of Ag+and Cu+and KMnO4 at 1 mM. The neutral pectin lyase showed retting of Crotalaria juncea fibre in the presence of EDTA. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Concomitant evolution of wear and squeaking in dual‐severity, lubricated wear testing of ceramic‐on‐ceramic hip prostheses
Authors: Sanders Anthony , Tibbitts Ira , Brannon Rebecca
Published: February 2012

Ceramic‐on‐ceramic (CoC) hip bearings were tested in short‐term wear tests with a systematically varied contact force. Continuous vibration and intermittent surface roughness measurements were obtained to elucidate potential causes of in vivo hip joint squeaking. The three‐phase test comprised alternating cycles of edge loading (EL) and concentric articulation (CA), always using ample serum lubricant. A 50,000‐cycle wear trial in which the contact force during CA was distant from the head's wear patch yielded no squeaking and practically no liner roughening. In 10‐cycle trials of an edge‐worn head coupled with a pristine liner, the contact force was varied in magnitude and point of application; immediate, recurrent squeaking occurred only when the contact force exceeded a critical threshold value and was centered upon the head's wear patch. In a 27,000‐cycle wear trial with the contact force applied near the margin of the head's wear patch, recurrent squeaking emerged progressively as the liner's inner surface was roughened via its articulation with the worn portion of the head. The results reveal key conditions that yield recurrent squeaking in vitro in various scenarios without resorting to implausible dry conditions. A fundamental theory explains that hip squeaking is induced by myriad stress waves emanating from asperity collisions; yet, the root cause is edge loading. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1377–1383, 2012
Early adult sexual assault and disordered eating: The mediating role of posttraumatic stress symptoms
Authors: Dubosc Auberi , Capitaine Maud , Franko Debra L. , Bui Eric , Brunet Alain , Chabrol Henri , F. Rodgers Rachel
Published: February 2012

Although adult sexual assault has been suggested to be a risk factor for disordered eating, little is known about the pathways leading to this disorder. This study aimed to examine the mediating effect of depressive symptoms and symptoms of posttraumatic stress disorder (PTSD), in the relationship between sexual assault and disordered eating among female students. A sample of 296 French female students completed a questionnaire assessing experiences of sexual assault from age 15, PTSD symptoms, depressive symptoms, and disordered eating. Results revealed that PTSD symptoms fully mediated the effect of early adult sexual assault on disordered eating (B = 1.10, SE = 1.64), and depressive symptoms were a partial mediator of this relationship (B = 2.64, SE = 1.28). When examining both mediators simultaneously the relationship was fully mediated and neither variable emerged as a significantly stronger mediator. Our findings highlight the complex relationship between PTSD symptoms, depressive symptoms, and disordered eating following sexual assault. Further investigation into the temporal relationships between these variables would contribute to inform prevention interventions for disordered eating.
The mediating role of trauma‐related symptoms in the relationship between sexual victimization and physical health symptomatology in undergraduate women
Authors: Tansill Erin C. , Edwards Katie M. , Kearns Megan C. , Gidycz Christine A. , Calhoun Karen S.
Published: February 2012

Previous research suggests that posttraumatic stress symptomatology is a partial mediator of the relationship between sexual assault history in adolescence/adulthood and physical health symptomatology (e.g., Eadie, Runtz, & Spencer‐Rodgers, 2008). The current study assessed a broader, more inclusive potential mediator, trauma‐related symptoms in the relationship between sexual victimization history (including both childhood and adolescent/adulthood sexual victimizations) and physical health symptomatology in a college sample. Participants were 970 young women (M = 18.69, SD = 1.01), who identified mostly as Caucasian (86.7%), from 2 universities who completed a survey packet. Path analysis results provide evidence for trauma‐related symptoms as a mediator in the relationship between adolescent/adulthood sexual assault and physical health symptomatology, χ2 (1, N = 970) = 1.55, p = .21; comparative fit index = 1.00; Tucker‐Lewis index = 0.99; root mean square error of approximation = .02, 90% confidence interval [.00, .09], Bollen‐Stine bootstrap statistic, p = .29. Childhood sexual abuse was not related to physical health symptomatology, but did predict trauma‐related symptoms. Implications of these findings suggest that college health services would benefit from targeted integration of psychiatric and medical services for sexual assault survivors given the overlap of psychological and physical symptoms.
The C‐tail anchored TssL subunit, an essential protein of the enteroaggregative Escherichia coli Sci‐1 Type VI secretion system, is inserted by YidC
Authors: Aschtgen Marie‐Stéphanie , Zoued Abdelrahim , Lloubès Roland , Journet Laure , Cascales Eric
Published: February 2012

Type VI secretion systems (T6SS) are macromolecular complexes present in Gram‐negative bacteria. T6SS are structurally similar to the bacteriophage cell‐puncturing device and have been shown to mediate bacteria–host or bacteria–bacteria interactions. T6SS assemble from 13 to 20 proteins. In enteroaggregative Escherichia coli (EAEC), one of the subassemblies is composed of four proteins that form a trans‐envelope complex: the TssJ outer membrane lipoprotein, the peptidoglycan‐anchored inner membrane TagL protein, and two putative inner membrane proteins, TssL and TssM. In this study, we characterized the TssL protein of the EAEC Sci‐1 T6SS in terms of localization, topology, and function. TssL is a critical component of the T6SS, anchored to the inner membrane through a single transmembrane segment located at the extreme C‐terminus of the protein. We further show that this transmembrane segment is essential for the function of the protein and its proper insertion in the inner membrane is dependent upon YidC and modulated by the Hsp70 homologue DnaK.
Mathematical analysis of a model of chemotaxis arising from morphogenesis
Authors: Stinner Christian , Tello J. Ignacio , Winkler Michael
Published: February 2012

We consider non‐negative solution couples (u,v) of
urn:x-wiley:01704214:media:mma1573:mma1573-math-0001 with positive parameters χ and λ, where the spatial domain is the interval (0,1). This system appears as a limit case of a model for morphogenesis proposed by Bollenbach et al. (Phys. Rev. E. 75, 2007). Under suitable boundary conditions, modeling the presence of a morphogen source at x = 0, we prove the existence of a global and bounded weak solution using an approximation by problems where diffusion is introduced in the ordinary differential equation. Moreover, we prove the convergence of the solution to the unique steady state provided that χ is small and λ is large enough.

Numerical simulations both illustrate these results and give rise to further conjectures on the solution behavior that go beyond the rigorously proved statements. Copyright © 2012 John Wiley & Sons, Ltd.
Mechanical property tuning of semicrystalline network polymers by controlling rates of crystallization and crosslinking
Authors: Oya Nobuhiro , Saitoh Shunsuke , Furuhashi Yukiko , Yoshie Naoko
Published: February 2012

Semicrystalline network polymers were obtained by the Diels–Alder (DA) reaction of furyl‐telechelic poly(ε‐caprolactone) and tris(2‐maleimide ethyl)amine. Controlling the rates of crystallization and crosslinking reaction gave materials with various properties. Curing at a temperature much below Tm of poly(ε‐caprolactone), at which crystallization proceeded first followed by DA reaction, gave a hard and stiff material, whereas curing above Tm gave a soft and stretchable one. When crystallization and crosslinking were promoted simultaneously, tough and ductile materials were obtained. Structural analysis of the network polymers showed that the variation in the properties was derived from the difference in the crystallinity, crystallite size, and network structure. Therefore, materials with various mechanical properties, from soft to hard, could be obtained by simple thermal treatment. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Novel thermo‐responsive self‐assembly micelles from a double brush‐shaped PNIPAM‐g‐(PA‐b‐PEG‐b‐PA)‐g‐PNIPAM block copolymer with PNIPAM polymers as side chains
Authors: Luo Yan‐Ling , Yu Wei , Xu Feng , Zhang Li‐Li
Published: February 2012

A novel double brush‐shaped copolymer with amphiphilic polyacrylate‐b‐poly(ethylene glycol)‐b‐poly acrylate copolymer (PA‐b‐PEG‐b‐PA) as a backbone and thermosensitive poly(N‐isopropylacrylamide) (PNIPAM) long side chains at both ends of the PEG was synthesized via an atom transfer radical polymerization (ATRP) route, and the structure was confirmed by FTIR, 1H NMR, and SEC. The thermosensitive self‐assembly behavior was examined via UV‐vis, TEM, DLS, and surface tension measurements, etc. The self‐assembled micelles, with low critical solution temperatures (LCST) of 34–38 °C, form irregular fusiform and/or spherical morphologies with single, double, and petaling cores in aqueous solution at room temperature, while above the LCST the micelles took on more regular and smooth spherical shapes with diameter ranges from 45 to 100 nm. The micelle exhibits high stabilities even in simulated physiological media, with low critical micellization concentration (CMC) up to 5.50, 4.89, and 5.05 mg L−1 in aqueous solution, pH 1.4 and 7.4 PBS solutions, respectively. The TEM and DLS determination reveled that the copolymer micelle had broad size distribution below its LCST while it produces narrow and homogeneous size above the LCST. The cytotoxicity was investigated by MTT assays to elucidate the application potential of the as‐prepared block polymer brushes as drug controlled release vehicles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Copolymerization of ethylene with acrylonitrile promoted by novel nonmetallocene catalysts with phenoxy‐imine ligands
Authors: Zhang Xinli , Liu Zhi , Yi Jianjun , Li Fengjiao , Huang Haibing , Liu Wei , Zhen Hongpeng , Huang Qigu , Gao Kejing , Yang Wantai
Published: February 2012

A series of novel nonmetallocene catalysts with phenoxy‐imine ligands was synthesized by the treatment of phthaldialdehyde, substituted phenol with TiCl4, ZrCl4, and YCl3 in THF. The structures and properties of the catalysts were characterized by 1H NMR and elemental analysis. These catalysts were used for copolymerization of ethylene with acrylonitrile after activated by methylaluminoxane (MAO). The effects of copolymerization temperature, Al/M (M = Ti, Zr, and Y) ratio in mole, concentrations of catalyst and comonomer on the polymerization behaviors were investigated in detail. These results revealed that these catalysts were favorable for copolymerization of ethylene with acrylonitrile. Cat.3 was the most favorable one for the copolymerization of ethylene with acrylonitrile, and the catalytic activity was up to 2.19 × 104 g PE/mol.Ti.h under the conditions: polymerization temperature of 50 °C, Al/Ti molar ratio of 300, catalyst concentration of 1.0 × 10–4 mol/L, and toluene as solvent. The resultant polymer was characterized by FTIR, cross‐polarization magic angle spinning, 13C NMR, WAXD, GPC, and DSC. The results confirmed that the obtained copolymer featured high‐weight–average molecular weight, narrow molecular weight distribution about 1.61–1.95, and high‐acrylonitrile incorporation up to 2.29 mol %. Melting temperature of the copolymer depended on the content of acrylonitrile incorporation within the copolymer chain. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Block and random copolymerization of ε‐caprolactone, L‐, and rac‐lactide using titanium complex derived from aminodiol ligand
Authors: Dakshinamoorthy Deivasagayam , Peruch Frédéric
Published: February 2012

A series of di‐ and triblock copolymers [poly(L‐lactide‐b‐ε‐caprolactone), poly(D,L‐lactide‐b‐ε‐caprolactone), poly(ε‐caprolactone‐b‐L‐lactide), and poly(ε‐caprolactone‐b‐L‐lactide‐b‐ε‐caprolactone)] have been synthesized successfully by sequential ring‐opening polymerization of ε‐caprolactone (ε‐CL) and lactide (LA) either by initiating PCL block growth with living PLA chain end or vice versa using titanium complexes supported by aminodiol ligands as initiators. Poly(trimethylene carbonate‐b‐ε‐caprolactone) was also prepared. A series of random copolymers with different comonomer composition were also synthesized in solution and bulk of ε‐CL and D,L‐lactide. The chemical composition and microstructure of the copolymers suggest a random distribution with short average sequence length of both the LA and ε‐CL. Transesterification reactions played a key role in the redistribution of monomer sequence and the chain microstructures. Differential scanning calorimetry analysis of the copolymer also evidenced the random structure of the copolymer with a unique Tg. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Metal/organic barrier formation for a C60/Au interface: From the molecular to the monolayer limit
Authors: Abad Enrique , Ortega José , Flores Fernando
Published: February 2012

The C60/Au(111) metal/organic (MO) interface barrier formation is analyzed from the single molecule limit to the full monolayer case by means of density functional theory (DFT) calculations taking into account charging energy effects to properly describe the electronic structure of the interface and van der Waals (vdW) interactions to obtain the molecule‐surface adsorption distance. In our calculations we obtain the density of states (DOS) projected on the C60‐molecule, the energy position of its charge neutrality level (CNL), its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, as well as the interface Fermi level. From these calculations we also obtain the charge transfer, the induced potential on the molecule and the interface screening parameter, S. We find a significant evolution from the single molecule to the full monolayer, with the energy barrier for electrons decreasing with the molecule deposition: this reflects an increasing interface screening effect for larger molecule coverages. We also analyze the relationship between S and the molecule charging energy, U, and deduce an effective interaction between electrons in different C60 molecules.
Whispering gallery modes in deformed hexagonal resonators
Authors: Grundmann Marius , Dietrich Christof P.
Published: February 2012

Optical resonances in polygonal resonators are due to whispering gallery modes (WGM). We investigate WGM in regular and deformed hexagonal ZnO microwire resonators. Four types of geometries are investigated: regular hexagonal and dodecagonal cross sections, hexagonal cross section elongated for one pair of facets and hexagonal cross section deformed by bending (uniaxial stress). Experimental data on mode energies and angular dispersion are correlated with model calculations and Poincaré surfaces of section. Hexagonal (ϕ = 60°), square (ϕ = 45°), triangular (ϕ = 30°), and Fabry–Pérot modes (ϕ = 0°) are observed in the various investigated geometries, ϕ being the angle of incidence at the facets with respect to the normal direction.

magnified image

Hexagonal WGMs (green, 6‐WGM), triangular (red, 3‐WGM), and double‐triangular (blue, D3‐WGM) rays in regular hexagons, elongated hexagons and hexagons deformed by bending. Triangular WGMs are stable modes in all three resonators. Hexagonal modes are not stable in the bent hexagon.
Controlling quantum dot emission by integration of semiconductor nanomembranes onto piezoelectric actuators
Authors: Rastelli A. , Ding F. , Plumhof J. D. , Kumar S. , Trotta R. , Deneke Ch. , Malachias A. , Atkinson P. , Zallo E. , Zander T. , Herklotz A. , Singh R. , Křápek V. , Schröter J. R. , Kiravittaya S. , Benyoucef M. , Hafenbrak R. , Jöns K. D. , Thurmer D. J. , Grimm D. , Bester G. , Dörr K. , Michler P. , Schmidt O. G.
Published: February 2012

This paper reviews the recent advances obtained by integrating semiconductor epitaxial films with embedded self‐assembled quantum dots (QDs) on top of single‐crystal piezoelectric substrates made of lead magnesium niobate–lead titanate (PMN‐PT). This combination allows us to study in detail the effects produced by variable strains (up to about ± 0.2%) on the excitonic emission of single QDs and to add a powerful “tuning knob” to QDs. Biaxial stress can be used to reversibly shift the emission wavelength of QDs in a spectral range wider than 10 meV and to modify the relative binding energies of excitonic species. Anisotropic stress has instead a strong influence on the fine structure splitting of neutral excitons. Finally, we present experimental results on the effect of biaxial strain on the optical modes of microring optical resonators and show a simple approach enabling the compensation of piezo‐creep via a closed‐loop system.

magnified image

Schematic illustration of a QD membrane integrated on top of a PMN‐PT substrate. Stress provided by the piezoelectric substrate allows broad range tuning of the emission properties of the overlying dots.
Effect of dependent errors in the assessment of diagnostic or screening test accuracy when the reference standard is imperfect
Authors: Walter S.D. , Macaskill P. , Lord Sarah J. , Irwig L.
Published: February 2012

When no gold standard is available to evaluate a diagnostic or screening test, as is often the case, an imperfect reference standard test must be used instead. Furthermore, the errors of the test and its reference standard may not be independent. Some authors have opined that positively dependent errors will lead to overestimation of test performance. Although positive dependence does increase agreement between the test and the reference standard, it is not clear if test accuracy will necessarily be overestimated in this situation, and the case of negatively associated test errors is even less clear. To examine this issue in more detail, we derive the apparent sensitivity, specificity, and overall accuracy of a test relative to an imperfect reference standard and the bias in these parameters. We demonstrate that either positive or negative bias can occur if the reference standard is imperfect. The type and magnitude of bias depend on several components: the disease prevalence, the true test sensitivity and specificity, the covariance between the false‐negative test errors among the true disease cases, and the covariance between the false‐positive test errors among the true noncases. If, for example, sensitivity and specificity are 0.8 for both the test and reference standard and the errors have a moderate positive dependence, test sensitivity is then underestimated at low prevalence but overestimated at high prevalence, while the opposite occurs for specificity. We illustrate these ideas through general numerical calculations and an empirical example of screening for breast cancer with magnetic resonance imaging and mammography. Copyright © 2012 John Wiley & Sons, Ltd.
L1penalized continuation ratio models for ordinal response prediction using high‐dimensional datasets
Authors: Archer K. J. , Williams A. A. A.
Published: February 2012

Health status and outcomes are frequently measured on an ordinal scale. For high‐throughput genomic datasets, the common approach to analyzing ordinal response data has been to break the problem into one or more dichotomous response analyses. This dichotomous response approach does not make use of all available data and therefore leads to loss of power and increases the number of type I errors. Herein we describe an innovative frequentist approach that combines two statistical techniques, L1penalization and continuation ratio models, for modeling an ordinal response using gene expression microarray data. We conducted a simulation study to assess the performance of two computational approaches and two model selection criteria for fitting frequentist L1penalized continuation ratio models. Moreover, we empirically compared the approaches using three application datasets, each of which seeks to classify an ordinal class using microarray gene expression data as the predictor variables. We conclude that the L1penalized constrained continuation ratio model is a useful approach for modeling an ordinal response for datasets where the number of covariates (p) exceeds the sample size (n) and the decision of whether to use Akaike Information Criterion (AIC) or Bayesian Information Criterion (BIC) for selecting the final model should depend upon the similarities between the pathologies underlying the disease states to be classified. Copyright © 2012 John Wiley & Sons, Ltd.
Modeling transmission of multitype infectious agents: application to carriage of Streptococcus pneumoniae
Authors: Erästö Panu , Hoti Fabian , Auranen Kari
Published: February 2012

We describe a novel Bayesian approach to estimate acquisition and clearance rates for many competing subtypes of a pathogen in a susceptible–infected–susceptible model. The inference relies on repeated measurements of the current status of being a non‐carrier (susceptible) or a carrier (infected) of one of the nq > 1 subtypes. We typically collect the measurements with sampling intervals that may not catch the true speed of the underlying dynamics. We tackle the problem of incompletely observed data with Bayesian data augmentation, which integrates over possible carriage histories, allowing the data to contain intermittently missing values, complete dropouts of study subjects, or inclusion of new study subjects during the follow‐up. We investigate the performance of the described method through simulations by using two different mixing groups (family and daycare) and different sampling intervals. For comparison, we describe crude maximum likelihood‐based estimates derived directly from the observations. We apply the estimation algorithm to data about transmission of Streptococcus pneumonia in Bangladeshi families. The computationally intensive Bayesian approach is a valid method to account for incomplete observations, and we found that it performs generally better than the simple crude method, in particular with large amount of missing data. Copyright © 2012 John Wiley & Sons, Ltd.
Social networking relationships, firm‐specific managerial experience and firm performance in a transition economy: A comparative analysis of family owned and nonfamily firms
Authors: Acquaah Moses
Published: February 2012

The effect of social networking relationships, firm‐specific managerial experience, and their interactions on performance between family owned and nonfamily firms are studied. Using data from 106 organizations in Ghana, the findings show that family owned firms benefit more from networking relationships with bureaucratic officials than do nonfamily firms. However, nonfamily firms benefit more from networking relationships with community leaders and firm‐specific managerial experience than do family owned firms. Networking relationships with politicians impede performance for nonfamily firms. Nonfamily firms are better able than family owned firms to use their firm‐specific managerial experience to manage the resources and capabilities obtained from networking relationships with community leaders to create value. Moreover, firm‐specific managerial experience attenuates the detrimental effects of networking with politicians for both types of firms. Copyright © 2012 John Wiley & Sons, Ltd.
Facile Synthesis of Au‐Nanoparticle/Polyoxometalate/Graphene Tricomponent Nanohybrids: An Enzyme‐Free Electrochemical Biosensor for Hydrogen Peroxide
Authors: Liu Rongji , Li Shiwen , Yu Xuelian , Zhang Guangjin , Zhang Suojiang , Yao Jiannian , Keita Bineta , Nadjo Louis , Zhi Linjie
Published: February 2012

A green, facile, one‐pot synthesis of well‐defined Au NPs@POM–GNSs tricomponent nanohybrids is reported (POM stands for polyoxometalate and GNSs for graphene nanosheets). The synthesis is convenient, rapid and environmentally friendly. The POMs serve as both reducing, encapsulating molecules, and bridging molecules; this avoids the introduction of other organic toxic molecules. Characterization using transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and Raman spectroscopy analysis is performed, and the structure of the prepared nanohybrids of Au NPs@POM–GNSs is verified. Most importantly, the amperometric measurements show the Au NPs@POM–GNSs nanohybrids have high catalytic activity with good sensitivity, good long‐term stability, wide linear range, low detection limit, and fast response towards H2O2 detection for application as an enzyme‐free biosensor. Transformation of the POMs during H2O2 detection does not affect the catalytic activities of the nanohybrids. Thus, the synergistic effect of Au NPs and GNSs in the nanohybrids leads to the enhanced catalytic property.
Highly Efficient and Ultra‐small Volume Separation by Pressure‐Driven Liquid Chromatography in Extended Nanochannels
Authors: Ishibashi Ryo , Mawatari Kazuma , Kitamori Takehiko
Published: February 2012

The rapidly developing interest in nanofluidic analysis, which is used to examine liquids ranging in amounts from the attoliter to the femtoliter scale, correlates with the recent interest in decreased sample amounts, such as in the field of single‐cell analysis. For general nanofluidic analysis, the fact that a pressure‐driven flow does not limit the choice of solvents (aqueous or organic) is important. This study shows the first pressure‐driven liquid chromatography technique that enables separation of atto‐ to femtoliter sample volumes, with a high separation efficiency within a few seconds. The apparent diffusion coefficient measurement of the unretentive sample suggests that there is no increase in the viscosity of toluene in the extended nanospace, unlike in aqueous solvents. Evaluation of the normal phase separation, therefore, should involve only the examination of the effect of the small size of the extended nanospace. Compared to a conventionally packed high‐performance liquid chromatography column, the separation here results in a faster separation (4 s) by 2 orders of magnitude, a smaller injection volume (100 fL) by 9 orders, and a higher separation efficiency (440 000 plates/m) by 1 order. Moreover, the separation behavior agrees with the theory showing that this high efficiency was due to the small and controlled size of the separation channel, where the diffusion through the channel depth direction is fast enough to be neglected. Our chip‐based platform should allow direct and real‐time analysis or screening of ultralow volume of sample.
Glossing and Second Language Vocabulary Learning
Authors: Ko Myong Hee
Published: February 2012

This study aims to investigate the effect of different types of glosses as well as no‐gloss and glossed texts on L2 vocabulary learning. A total of 90 university students in Korea participated in this study. They were randomly divided into groups according to three different conditions: no gloss, L1 gloss, and L2 gloss. Students were first asked to read materials for a reading comprehension test. Immediately after, participants took an unexpected multiple‐choice (MC) vocabulary test, which they took once again unannounced four weeks later. All participants also completed a student opinion questionnaire reporting on their reactions to the reading text. Results indicated that, on the immediate vocabulary test, there was a significant difference between no‐gloss and glossed conditions. However, participants showed no significant differences between texts with L1 glosses and L2 glosses. Findings were similar on the delayed vocabulary test given four weeks later. There were significant time effects on L1 and L2 gloss conditions over time but not on the no‐gloss condition. The survey results revealed participants preferred glosses in their L2 reading materials, and they favored L2 glosses over L1 glosses.
Head in the clouds or feet on the ground? CEO perspectives and the international business research agenda
Authors: Pendergast William , Geringer J. Michael
Published: February 2012

In response to recent articles examining the current state and future direction of international business (IB) research, this article directly surveys CEOs of the largest Fortune 500 companies to solicit their views about university‐based IB research and to identify the most significant IB problems their firms encounter. Results suggest a consistently low appreciation by CEOs for university‐based IB research over an extended period of time. Data also suggest a window of opportunity to capture a constituency among those companies that anticipate a significant increase in their international activity. To capture a practitioner constituency, however, research should focus on key problem areas that have been identified in this article, and the findings should be presented in accessible forms and venues. © 2012 Wiley Periodicals, Inc.
International business research and the new role of universities (there is sunshine above the clouds)
Authors: Czinkota Michael R. , Pinkwart Andreas
Published: February 2012

Pendergast and Geringer juxtapose the need for more theory with the requirement for immediate and direct benefits of international business education. Concurrently, they address the linkage between business and academia and demonstrate, with the help of data, the changes that have occurred since an earlier study of these topics by Ricks and Czinkota (1979). We analyze the reasons for changes during this time period and offer a broad perspective on what universities should do in order to remain leading institutions in this century. © 2012 Wiley Periodicals, Inc.
19F magnetic resonance imaging of endogenous macrophages in inflammation
Authors: Temme Sebastian , Bönner Florian , Schrader Jürgen , Flögel Ulrich
Published: February 2012

In this article, we review the use of 19F MRI (magnetic resonance imaging) for in vivo tracking of monocytes and macrophages in the course of tissue inflammation. Emulsified perfluorocarbons (PFCs) are preferentially phagocytized by monocytes/macrophages and are readily detected by 19F MRI. Because of the lack of any 19F background in the body, observed signals are robust and exhibit an excellent degree of specificity. As a consequence of progressive infiltration of the labeled immunocompetent cells into inflamed areas, foci of inflammation can be localized as hot spots by simultaneous acquisition of morphologically matched proton (1H) and fluorine (19F) MRI. The identification of inflammation by 19F MRI—at a time when the inflammatory cascade is initiated—opens the possibility for an early detection and more timely therapeutic intervention. Since signal intensity in the 19F images reflects the severity of inflammation, this approach is also suitable to monitor the efficacy of pharmaceutical treatment. Because PFCs are biochemically inert and the fluorine nucleus exhibits high magnetic resonance (MR) sensitivity, 19F MRI may be applicable for clinical inflammation imaging. WIREs Nanomed Nanobiotechnol 2012, 4:329–343. doi: 10.1002/wnan.1163

This article is categorized under:

Diagnostic Tools > In Vivo Nanodiagnostics and Imaging
Comparison of aerial surveys and pellet‐based distance sampling methods for estimating deer density
Authors: Urbanek Rachael E. , Nielsen Clayton K. , Preuss Timothy S. , Glowacki Gary A.
Published: February 2012

Wildlife biologists require density estimates for white‐tailed deer (Odocoileus virginianus) to facilitate management. Aerial surveys are often used to obtain density estimates, but are subject to problems necessitating the consideration of novel techniques. During winters 2008 and 2009, we estimated deer density on 6 forest preserves near Chicago, Illinois, USA, using aerial surveys and pellet‐based distance sampling (PBDS) methods to provide a comparison of these 2 density‐estimation techniques. Density estimates from aerial surveys were obtained by dividing both the raw count of deer observed on each preserve (unadjusted aerial density) and the raw count divided by 0.75 (i.e., assuming a 75% detection rate; adjusted aerial density) by the area of the preserve. We calculated deer densities from PBDS methods using Program DISTANCE 5.0 (PBDS density) and used paired t‐tests to compare density estimates between PBDS and aerial survey techniques. Unadjusted aerial density (10–29 deer/km2) and adjusted aerial density (13–39 deer/km2) estimates did not differ (t11 = −1.99–0.44, P = 0.071–0.666) from PBDS density estimates (12–36 deer/km2). We also compared costs and found PBDS (US$85/survey) was 88% cheaper than aerial surveys (US$722/survey). Problems with bias and precision exist with both methods, and managers should give them serious consideration when choosing which method to use to estimate deer densities. Given accurate pellet decay and deposition rates and a large sample size of pellet groups, PBDS may be advantageous due to less bias in density estimates, no dependence on continuous snow cover, cheaper survey costs, and no need for elaborate equipment or for professional biologists to conduct surveys. However, future research needs to address how to reduce coefficient of variations and confidence intervals for PBDS so that differences among years can be better differentiated. © 2012 The Wildlife Society.
On invariant structures of black hole charges
Authors: Ferrara Sergio , Marrani Alessio , Yeranyan Armen
Published: February 2012

Abstract

We study “minimal degree” complete bases of duality- and “horizontal”- invariant homogeneous polynomials in the flux representation of two-centered black hole solutions in two classes of D = 4 Einstein supergravity models with symmetric vector multiplets’ scalar manifolds. Both classes exhibit an SL(2,

$ \mathbb{R} $
) “horizontal” symmetry which mixes the two centers. The first class encompasses
$ \mathcal{N} = {2} $
and
$ \mathcal{N} = {4} $
matter-coupled theories, with semisimple U-duality given by SL(2,

$ \mathbb{R} $
) × SO(m,n); the analysis is carried out in the so-called Calabi-Vesentini symplectic frame (exhibiting maximal manifest covariance) and until order six in the fluxes included. The second class, exhibiting a non-trivial “horizontal” stabilizer SO(2), includes
$ \mathcal{N} = {2} $

minimally coupled and
$ \mathcal{N} = 3 $
matter coupled theories, with U-duality given by the pseudounitary group U(r,s) (related to complex flux representations). Finally, we comment on the formulation of special Kähler geometry in terms of “generalized” groups of type E
7.
Post‐dispersal seed removal in four Mediterranean oaks: species and microhabitat selection differ depending on large herbivore activity
Authors: González‐Rodríguez Victoria , Villar Rafael
Published: February 2012

Quercus forest regeneration is limited by different factors, post‐dispersal predation being one of the most critical stages. We analysed seed removal of four coexisting Quercus species (Q. ilex, Q. suber, Q. faginea and Q. pyrenaica) in a Mediterranean forest located in Southern Spain. Marked and weighed acorns from each of the species were placed in experimental units with or without exclusion of large herbivores and in two microhabitat types (Q. ilex shade or open). Acorn removal was monitored for 120 days in order to test the effect of exclusion of large herbivore and microhabitat type on seed removal rates and species selection. Interestingly, the results of microhabitat and species selection differed depending on the presence of large herbivores. Removal was faster in sites without exclusion, where most seeds (≈85%) disappeared during the first 9 days. In these sites, no differences in seed removal were found between different microhabitats, but seeds of two species, those with higher seed mass (Q. suber and Q. pyrenaica) were most preferred. However, under exclusion of large herbivores, seed removal was affected by the microhabitat, this being greater in Q. ilex shaded microhabitats, which showed a higher structural diversity. Also, species selection was completely different under exclusion of large herbivores, and seeds of Q. ilex and Q. faginea were removed faster. These results highlight the importance of large herbivore activity on seed removal and its effect on microhabitat and species selection. Therefore, specific selection by seed consumers may modify seedling recruitment and may have an important influence on the relative abundance of coexisting Quercus species.
Fears for the future among Finnish adolescents in 1983–2007: From global concerns to ill health and loneliness
Authors: Lindfors Pirjo , Solantaus Tytti , Rimpelä Arja
Published: February 2012

We examined how Finnish adolescents’ fears for their future changed over a quarter of a century and how these changes reflect transformations of the adolescents’ key contexts from the late‐modernist perspective. Nationally representative samples of 12‐, 14‐, 16‐, and 18‐year‐olds in 1983, 1997, and 2007 were surveyed using mailed questionnaires regarding health behaviours (N = 17,750). Over 1900 fears to open‐ended questions were reported. Inductive content analysis was used to construct 19 fear categories. The percentage of adolescents reporting fears in each study year is presented for the entire study population and by age and sex with tests for statistical significance. Fears concerning global and societal issues declined from 1983 to 2007. The emphasis on future work remained stable, but uneasiness about making wrong decisions has increased. Fears regarding health, death, loneliness, and relationships gained importance. Our findings indicate that the perceptions of risks have become more individualized, thus providing strong support for the late‐modernist theory.
Anaerobic Power and Muscle Strength in Human Immunodeficiency Virus–Positive Preadolescents
Authors: Ramos Edwardo , Guttierrez‐Teissoonniere Suzanne , Conde Jose G. , Baez‐Cordova Jose A. , Guzman‐Villar Brenda , Lopategui‐Corsino Edgar , Frontera Walter R.
Published: February 2012

Objective

To determine the anaerobic power and muscle strength of preadolescents with human immunodeficiency virus (HIV).

Design

Cross‐sectional design.

Setting

Human performance laboratory at the University District Hospital at the Puerto Rico Medical Center.

Participants

Fifteen preadolescents (8 girls and 7 boys) with a classification of HIV A and B attending an investigational treatment program at the University Pediatric Hospital. Fifteen seronegative control subjects matched by age and gender also were included.

Main Outcome Measures

The power of the lower extremities was measured with use of the Wingate Anaerobic Power Test on a MONARK cycle ergometer (mean power in watts). Local muscle strength of the dominant knee extensors (peak torque/body weight × 100) was tested with an isokinetic dynamometer set at 60 deg/s. Statistical analysis was performed with the Wilcoxon signed‐rank test, and statistical significance was accepted at an α level of <.05.

Results

No significant differences between the control group and study group were detected on muscle strength testing. The study group presented a lower anaerobic power (mean power) compared with control subjects (P = .04).

Conclusions

This exploratory study suggests that HIV‐infected preadolescents present lower anaerobic power compared with uninfected control subjects. Our findings of impaired anaerobic capacity can have clinical implications in this population because most of the activities of daily living, such as play, leisure, and sport activities, are short term and high intensity (anaerobic) in nature.
Power relations and risk allocation in the governance of public private partnerships: A case study from China
Authors: Chen Cheng , Hubbard Michael
Published: February 2012

This article examines the power relations between the government, the private sector and citizens/users, which underlie the risk allocation process in public private partnerships (PPPs) for infrastructure. It argues that the institutional environment and resource dependency determine power relations, and hence risk allocation. The approach is applied to analyse risk allocation in a PPP toll road in Zhejiang province, China. The analysis reveals the dynamic of power relations among the parties. The findings show how the party with more power (in this case, the local government) was able to shift costs to the weaker parties (in this case, the users and the private sector). The implication of the study is that more effective courts and greater accountability of government to citizens are required to enhance the governance of such PPPs in China.
ON THE EXPONENTIAL DIOPHANTINE EQUATIONx2+p2m=2yn
Authors: ZHU HUILIN , LE MAOHUA , TOGBÉ ALAIN
Published: February 2012

Letpbe an odd prime. In this paper, we consider the equationand we describe all its solutions. Moreover, we prove that this equation has no solution (x,y,m,n) whenn>3 is an odd prime andyis not the sum of two consecutive squares. This extends the work of Tengely [On the diophantine equationx2+q2m=2yp,Acta Arith.127(1) (2007), 71–86].
STTEP by STEPP in the spirit ofUmuntu ungumuntu ngabantu
Authors: van Niekerk Caroline , Typpo Maria
Published: February 2012

In a recent article, ‘Sttepping in the right direction? Western classical music in an orchestral programme for disadvantaged African youth’, ‘sttepping’ was noted as no spelling error. The same applies here; reference is to STTEP Music School, an outreach project at the University of Pretoria. STTEP teaches the playing of orchestral instruments, plus background areas like music theory, to disadvantaged learners. Ethnographic and case study research of STTEP, its teachers, pupils and administrators, over the period 2005–2009 was conducted within a sociological meta-theoretical framework. From the hybrid data obtained, conclusions have been drawn, including on observed effects of the African philosophyUbuntu.
Turning (Into) “The Great Regulating Wheel”: The Conversion of the Bank of the United States, 1791–1811
Authors: Lomazoff Eric
Published: February 2012

Two volumes have recently challenged the assumption that institutional change either (1) takes the form of gradual adaptation in the service of continuity, or (2) entails the abrupt breakdown of existing arrangements. This scholarship has demonstrated that change can also be simultaneously gradual and transformative. Conversion represents one type of such change; it involves the use of institutional resources for new purposes. I chronicle the conversion of the Bank of the United States (1791–1811) from a fiscal auxiliary of the federal government to an institution with both fiscal and monetary capacities. More generally, I ask whether this change squares with existing understandings of how conversion unfolds. Conversion is thought to occur when (1) new actors assume control, or (2) new challenges prompt the redeployment of resources. I ask whether the Bank's conversion resulted from (3) efforts by institutional elites to invent a rationale for deployment. I find that the change in question resulted from genuine concerns about the supply of bank credit in the Early Republic. With the details of this historical transformation in mind, I briefly digress in order to address repeated claims that the Bank of the United States was or became a “central bank” during this period.
Zooplankton respiration and the export of carbon at depth in the Amundsen Gulf (Arctic Ocean)
Authors: Darnis Gérald , Fortier Louis
Published: February 2012

In arctic seas, lipids accumulated by zooplankton migrants in the surface layer in spring‐summer are respired at depth during the winter. The resulting active downward transport of carbon by the 200–1000 and >1000 μm mesozooplankton fractions was quantified based on 41 biomass and respiration profiles from October 2007 to July 2008 in the Amundsen Gulf (Canadian Arctic Ocean). The small fraction, dominated by CII‐CIII Calanus glacialis, represented on average 12% of the overall zooplankton biomass and contributed little to the active transport of carbon by respiration. From April to July, total zooplankton ingested 17–28% of the estimated gross primary production (GPP) in the surface 100 m, and 36–59% of GPP over the entire water column. The large fraction, comprised mainly of CIV, CV and adults Calanus hyperboreus and C. glacialis that accumulate large lipid reserves, was responsible for 89% of grazing. The downward migration of large zooplankton in late summer coincided with a sharp decline in specific respiration rates signaling the start of diapause and the endogenous fuelling of metabolism. From October to April, Calanus migration‐respiration actively transported 3.1 g C m−2 beyond 100 m, a flux that represented 85 to 132% of the gravitational POC fluxes at 100 m from October to July. Our results stress the importance of including active transport by large zooplankton migrants in carbon budgets of the Arctic Ocean.
Most Mars minerals in a nutshell: Various alteration phases formed in a single environment in Noctis Labyrinthus
Authors: Thollot Patrick , Mangold Nicolas , Ansan Véronique , Le Mouélic Stéphane , Milliken Ralph E. , Bishop Janice L. , Weitz Catherine M. , Roach Leah H. , Mustard John F. , Murchie Scott L.
Published: February 2012

A closed depression in the Noctis Labyrinthus region of Mars (at 10.4°S, 98.6°W), believed to have formed in the Late Hesperian, holds an inner pit partially filled with several hundred meters of stratified material. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) visible‐near infrared reflectance data reveal signatures of numerous hydrated minerals including halloysite/kaolinite, Fe‐smectite, Si‐OH bearing phases and Fe‐sulfates (polyhydrated, monohydrated, and hydroxylated types, including jarosite). We use CRISM data, high resolution imagery (HiRISE) and HRSC (High Resolution Stereo Camera) derived elevation to analyze the morphology, composition and stratigraphy of these materials. We propose an alteration sequence including formation of acid sulfate solutions from groundwater and magmatic sulfur, which then locally altered the basaltic bedrock and layered sediments mainly deposited from volcanic tephra, forming Fe‐smectite and Fe‐sulfates. The mineral variability can mostly be explained by local variations in the pH of the altering fluids, with original acidity being buffered by dissolution of primary minerals; and by variable fluid input and evaporation and/or freezing rates (resulting in various water/rock ratios). This site shows local formation of almost all classes of minerals identified thus far on Mars without invoking global conditions. Processes related to local volcanic activity and associated hydrothermalism were able to produce, during an era in which the climate is believed to have been cold, a large variety of hydrated minerals. This study highlights the importance of the geological setting of hydrated minerals in the understanding of Mars geologic and climatic evolution.