bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanocrystalline silicon in biological studies
Authors: Fucikova Anna , Valenta Jan , Pelant Ivan , Kusova Katerina , Brezina Vitezslav
Published: February 2011

Porous silicon and similar materials, like micro‐ and nanocrystalline silicon, are nowadays studied not only in physical research (e.g. optical gain studies, electro‐optical devices, solar energy conversion), but they are very promising also in biological research as fluorescent labels, biological sensors, drug delivery systems or scaffold for various tissues. We are giving an overview of various approaches of preparation of micro‐ and nanocrystalline silicon and current studies of applications with main focus on biology and medicine. In contrast to other nanomaterials used in biological studies (e.g. carbon nanotubes, fullerenes, cadmium containing quantum dots) silicon based nanomaterials show very good biocompatibility and low cytotoxicity. Therefore, these materials have potential to become powerful tools for in vivo investigation of life processes on subcellular and molecular level. Our group concentrates on developing of gentle florescent label based on porous silicon for single molecule detection in the cell. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transition from excitonic to plasma emission from localized electron‐hole pair states in GaAs‐AlGaAs quantum wells
Authors: Manzke G. , Richter F. , Semkat D. , Burau G. K. G. , Kieseling F. , Stolz H.
Published: February 2011

We present a theoretical analysis of the emission of localized excitons in GaAs‐AlGaAs quantum wells, which shows a strong nonlinear behavior with increasing excitation. Considering the influence of dynamical screening both on the one‐particle properties of carriers and on the whole spectrum of electron‐hole pair states, we are able to explain the nonlinearity as a transition of the emission from excitonic to electron‐hole pair states in the continuum (electron‐hole plasma). Moreover, our theoretical approach based on the quasi‐particle approximation for the carriers states and quantum kinetic effects in the screening describes the observed changes of the shift of the exciton energy from higher to lower energies at a temperature of T = 10 K (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oscillatory excitation energy dependence of injection currents in GaAs/AlGaAs quantum wells
Authors: Thanh Duc Huynh , Förstner Jens , Meier Torsten , Priyadarshi Shekhar , Racu Ana Maria , Pierz Klaus , Siegner Uwe , Bieler Mark
Published: February 2011

The injection of photocurrents by femtosecond laser pulses in (110)‐oriented GaAs/AlGaAs quantum wells is investigated theoretically and experimentally. The roomtemperature measurements show an oscillatory dependence of the injection current amplitude and direction on the excitation photon energy.

Microscopic calculations using the semiconductor Bloch equations that are set up on the basis of k·p band structure calculations provide a detailed understanding of the experimental findings (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase separation of multicomponent excitonic Bose–Einstein condensates
Authors: Sobkowiak S. , Semkat D. , Stolz H. , Koch Th. , Fehske H.
Published: February 2011

For the observation of Bose–Einstein condensation, excitons in cuprous oxide are regarded as promising candidates due to their large binding energy and long lifetime. High particle densities may be achieved by entrapment in a stress induced potential. We consider a multicomponent gas of interacting para‐ and orthoexcitons in cuprous oxide confined in a three‐dimensional potential trap. Based on the Hartree–Fock–Bogoliubov theory, we calculate density profiles as well as decay luminescence spectra which exhibit signatures of the separation of the Bose‐condensed phases (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Second‐order polaron resonances in self‐assembled quantum dots
Authors: Kaczmarkiewicz Piotr , Machnikowski Paweł
Published: February 2011

We theoretically study the optical properties of an InAs/GaAs quantum dot (QD) near the area of the second‐order resonance between an electron confined in the QD and two longitudinal optical phonons. We present the absorption spectra of an inhomogeneously broadened QD ensemble and show that the minimal model needed for an accurate description of such a system needs to account for 3‐phonon states.

We study also the influence of the QD height to width ratio on the optical properties of the polaron system. The dependence of the width of the resonance and the position of the second‐orderresonant feature on the height to width ratio is presented (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InAs quantum dot site‐selective growth on GaAs substrates
Authors: Hendrickson Joshua , Helfrich Mathieu , Gehl Michael , Hu Dongzhi , Schaadt Daniel , Linden Stefan , Wegener Martin , Richards Benjamin , Gibbs Hyatt , Khitrova Galina
Published: February 2011

Photoluminescence (PL) spectra and AFM measurements of InAs quantum dots grown in a site‐selective manner on pre‐patterned GaAs substrates are presented. A number of processing steps are described including a Ga‐assisted deoxidation step to remove native oxides from the sample surface. Furthermore, post growth annealing is shown to be a promising technique for improving the quantum dot density and likelihood of single site‐selective nucleation. Morphological transitions are shown to occur during the annealing process with two initial quantum dots in a given nucleation site transforming into one slightly larger quantum dot. Density measurements performed by AFM combined with PL spectroscopic measurements show that we have achieved optically active, site‐selective dot growth, and additionally allow us to calculate that our site‐selective dots are on average 30% as efficient as unpatterned dots. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design for volume optimization of packaging for durable goods
Authors: Wever R.
Published: February 2011

In the literature, there are several authors arguing for the optimization of the packaging volume as an important factor in distribution efficiency. Within the context of packaging of durable goods, these authors present significant economic savings, usually illustrated by qualitative examples of redesigns. So far, these papers are limited to: (a) the economic aspect of volume (b) packaging for which the main functionality is distribution‐related, and (c) mostly qualitative empirical data. This current paper aims to contribute to this literature by: (a) arguing that volume is also a significant factor from an environmental perspective (b) including packaging for which the main functionality is marketing‐related, and (c) presenting quantitative data of over 1000 packed durable goods, covering consumer electronics, domestic appliances, toys, power tools and furniture. Several strategies for volume optimization are discussed in relation to different packaging functionalities. Copyright © 2011 John Wiley & Sons, Ltd.
High‐resolution simulation over central Europe: assimilation experiments during COPS IOP 9c
Authors: Schwitalla Thomas , Bauer Hans‐Stefan , Wulfmeyer Volker , Aoshima Fumiko
Published: February 2011

The impact of assimilating conventional and Global Positioning System (GPS) Zenith Total Delay (ZTD) data over France into the Weather Research and Forecasting (WRF) model is investigated during COPS IOP 9c. A convection‐permitting horizontal resolution of 3.6 km covering the whole of central Europe was chosen. Four different simulations were conducted to show the influence of assimilating different observation types on the forecast. Additionally, a comparison with the models COSMO‐DE and COSMO‐EU from the German Meteorological Service (DWD) was performed.

The results show a clear positive impact of assimilating data into a convection‐permitting configuration of the WRF model over Europe. The additional assimilation of GPS‐ZTD data shows a further improvement of integrated water vapour (IWV) correlation, but the influence on prediction of precipitation was not necessarily clear. A comparison with radiosonde data shows a positive impact on the humidity structure after 12 hours, while an overestimation of precipitation still remains.

A further comparison with the operational high‐resolution models of DWD during this COPS IOP reveals a strong dependence on the initial boundary‐layer wind field especially as the near‐surface wind field is better represented in the ECMWF analysis than in the COSMO analysis.

As this is, to our knowledge, the first study applying a convection‐permitting configuration of WRF over Europe, it can be used as a guidance for further studies. Copyright © 2011 Royal Meteorological Society
DFT calculations of amine‐imine tautomerism in some pyrimidine derivatives and their 1:1 and 1:2 complexes with water
Authors: Hasanein Ahmed A. , Senior Samir A.
Published: February 2011

Amine‐Imine tautomerization in 2‐amino‐pyrimidine (I), 2‐amino‐4,6‐dichloropyrimidine (II), 2‐amino‐4,6‐dimethylpyrimidine (III), and 2‐amino‐4,6‐dimethoxypyrimidine (IV) and their 1:1 and 1:2 H‐bonded complexes with water have been studied using the B3LYP/6‐31++G** method. Optimum molecular geometries, electronic properties, and energetics of these systems have been discussed. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Properties of polypropylene/(natural rubber)/organomontmorillonite nanocomposites prepared by melt blending
Authors: Bendjaouahdou C. , Bensaad S.
Published: February 2011

The aim of this work was to study the effects of an organomontmorillonite or organoclay (OMMT) on the properties of a thermoplastic elastomer blend prepared by melt blending and based on polypropylene (PP) and natural rubber (NR). The results obtained showed a slight improvement of the blend mechanical (strength, modulus, and elongation), thermal, and solvent resistance properties when the amount of the organoclay was 3 phr. Results obtained by XRD analysis showed that at 3 phr of organoclay loading there was a shift toward low angles of the organoclay (001) plane diffraction peak and a disappearance of the PP β–phase peak. This shift signifies an intercalation of the polypropylene/(natural rubber) chains between organoclay platelets. An SEM study revealed that at the 3 phr organoclay concentration the blend became tougher, and the organoclay was located both at the PP/NR interface and inside the NR dispersed phase. A DSC study showed a decrease of the melting temperature of the PP phase at the 3 phr organoclay loading. A rheological study revealed that the addition of organoclay had not increased the melt viscosity of the PP/NR blend, and the stiffness was related to the maximum torque increase as a function of the organoclay loading. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers
Dietary Cocoa Butter or Refined Olive Oil Does Not Alter Postprandial hsCRP and IL‐6 Concentrations in Healthy Women
Authors: Tholstrup Tine , Teng Kim‐Tiu , Raff Marianne
Published: February 2011

Contrary to other long chain saturated fatty acids (SFA), fats high in stearic acid do not raise plasma cholesterol concentrations, however, a slight elevation in inflammatory markers, plasma fibrinogen and interleukin‐6 (IL‐6), has been observed in the fasting state. The effect of stearic acid on inflammation in the postprandial state has not yet been reported. We conducted a single blind crossover, randomized, postprandial study to compare the effects of a fat load of cocoa butter high in stearic acid and olive oil in ten healthy women. The test meals contained 1 g of fat per kg body weight (mean 62 g). Blood samples were collected at 0 (fasting), 4 and 6 h. Both diets resulted in a significant increase in serum triacylglycerol (TAG) concentration over time (P = 0.003) and a decrease in serum IL‐6 concentration after 4 h followed by an increase to post absorptive values after 6 h (P < 0.001); whereas serum high sensitivity C‐reactive protein (hsCRP) concentration was not affected. There was no difference between diets in effects on serum TAG, hsCRP and IL‐6 concentrations and no association between postprandial lipemia and inflammatory markers. High intake of dietary fats increase postprandial serum TAG, however, may not affect inflammatory markers postprandially. Thus, fat rich in stearic acid does not seem to increase postprandial inflammation.
Improvement of Canola Oil Frying Stability by Bene Kernel Oil's Unsaponifiable Matter
Authors: Sharayei Parvin , Farhoosh Reza , Poorazrang Hashem , Khodaparast Mohammad Hossein Haddad
Published: February 2011

The anti‐rancidity effect of the unsaponifiable matter fraction of bene kernel (UFB) oil on canola oil (CAO) during frying was compared to that of tert‐butyl hydroquinone (TBHQ). The UFB was separated into hydrocarbons (12.9%), carotenes (9.6%), tocopherols and tocotrienols (65.8%, mainly γ‐tocopherol), linear and triterpenic alcohols (3.8%), methyl sterols (2.8%), sterols (3.0%, mainly β‐sitosterol, stigmasterol, Δ5‐avenasterol, and Δ7‐avenasterol, respectively), and triterpenic dialcohols (2.2%). The results obtained from the measurements of the total polar compounds, the conjugated diene value, the carbonyl value, and total tocopherols showed that the stability of CAO improves similarly in the presence of UFB or TBHQ, and even more in the presence of UFB in some cases (especially inhibition of oxidized triglyceride monomers and triglyceride dimers). The analysis of polar components showed that the antioxidative additives were more effective to resist the formation of thermo‐oxidative than hydrolytic products during the frying of CAO.
Global well-posedness for an advection–diffusion equation arising in magneto-geostrophic dynamics
Authors: Friedlander Susan , Vicol Vlad
Published: February 2011

We use De Giorgi techniques to prove Hölder continuity of weak solutions to a class of drift-diffusion equations, with

L^{2}

initial data and divergence free drift velocity that lies in

L_{t}^{\infty }\mathrm{BMO}_{x}^{−1}

. We apply this result to prove global regularity for a family of active scalar equations which includes the advection–diffusion equation that has been proposed by Moffatt in the context of magnetostrophic turbulence in the Earthʼs fluid core.

Nous utilisons des techniques de De Giorgi pour démontrer la continuité Hölder de solutions faibles pour une classe dʼéquations de dérive-diffusion, avec données initiales

L^{2}

et champ de vitesse incompressible appartenant à

L_{t}^{\infty }\mathrm{BMO}_{x}^{−1}

. Nous appliquons ce résultat pour démontrer la régularité globale pour une famille dʼéquations du scalaire actif qui comprend lʼéquation dʼadvection–diffusion qui a été proposée par Moffatt dans le contexte de la turbulence magnétostrophique dans le noyau fluide de la Terre.
Violence and phases of illness: Differential risk and predictors
Authors: Hodgins S. , Riaz M.
Published: February 2011

This study tested the hypothesis that among patients with schizophrenia the risk and correlates of aggressive behavior differ depending on the level of positive symptoms. Two hundred and fifty-one adults with schizophrenia who were living in the community were assessed by psychiatrists using validated instruments. Patients and collaterals reported aggressive behavior. In a final multivariate model, aggressive behavior was significantly and positively associated with childhood conduct disorder, current use of illicit drugs, positive, threat-control-override (TCO), and depression symptoms. While 16% of the patients with two or fewer positive symptoms engaged in aggressive behavior in the previous six months, this was true of 28.4% of those with three or more positive symptoms (X2(n= 251,1) = 5.48,P= 0.019). Among patients with high positive symptoms, even univariate analyses failed to detect any factors associated with aggressive behavior other than medication non-compliance, typical antipsychotic medication, and clozapine. By contrast, among patients with few positive symptoms, aggressive behavior was associated with TCO and depression symptoms, young age, male sex, the number of childhood conduct disorder symptoms, prior aggressive behavior, and current illicit drug use. In phases of illness characterized by different levels of positive symptoms, the risk of aggressive behavior and the associated factors differ.
Competing on Good Politicians
Authors: GALASSO VINCENZO , NANNICINI TOMMASO
Published: February 2011

Is electoral competition good for political selection? To address this issue, we introduce a theoretical model where ideological parties select and allocate high-valence (experts) and low-valence (party loyalists) candidates into electoral districts. Voters care about a national policy (e.g., party ideology) and the valence of their district's candidates. High-valence candidates are more costly for the parties to recruit. We show that parties compete by selecting and allocating good politicians to the most contestable districts. Empirical evidence on Italian members of parliament confirms this prediction: politicians with higher ex ante quality, measured by years of schooling, previous market income, and local government experience, are more likely to run in contestable districts. Indeed, despite being different on average, politicians belonging to opposite political coalitions converge to high-quality levels in close electoral races. Furthermore, politicians elected in contestable districts have fewer absences in parliament, due to a selection effect more than to reelection incentives.
The Political Economy of Imperialism, Decolonization and Development
Authors: Gartzke Erik , Rohner Dominic
Published: February 2011

Nations have historically sought power and prosperity through control of physical space. In recent decades, however, this has largely ceased. Most states that could do so appear relucant, while the weak cannot expand. This article presents a theory of imperialism and decolonization that explains both historic cycles of expansion and decline and the collective demise of the urge to colonize. Technological shocks enable expansion, while rising labour costs and the dynamics of military technology gradually dilute imperial advantage. Simultaneously, economic development leads to a secular decline in payoffs for appropriating land, minerals and capital. Once conquest no longer pays great powers, the systemic imperative to integrate production vertically also becomes archaic.
Government Intentions and Citizen Preferences in Dynamic Perspective
Authors: Warwick Paul V.
Published: February 2011

The relationship between median citizen opinion on the left–right dimension, as measured in the Eurobarometer and European Electoral Studies series of surveys, and the left–right positions of governments in West European democracies is explored to gain a fuller understanding of how and to what extent median opinion may influence what governments subsequently set out to do. The analysis allows for the possibility that measurement may not be equivalent across countries and surveys, that the data may contain significant dynamic effects, and that different countries may exhibit different relationships between the two variables. The analyses show that changes in the citizen median generally produce larger changes in government position, the size depending mainly on the proportionality of the electoral system.
A taxonomic study of Melanelixia fuliginosa in Europe
Authors: ARUP Ulf , BERLIN Emma SANDLER
Published: February 2011

For a long time it has been discussed as to whether Melanelixia fuliginosa comprises one or two species: one darker, mainly saxicolous, and one lighter, mainly corticolous. To settle the question, a morphometric and a molecular analysis were carried out and analyzed using a principal component analysis (PCA). The morphometric analysis indicates a differentiation in several characters between material previously recognized as subspecies fuliginosa and glabratula, but also a considerable overlap in some of them. The molecular analysis of the nrITS DNA gene reveals a clear division of the taxa. Specimens belonging to Melanelia fuliginosa fall out in two different clades, which have good bootstrap support, corresponding to the subspecies fuliginosa and glabratula. Accordingly, we propose that the subspecies should be acknowledged as separate species, Melanelixia fuliginosa (Fr. ex Duby) O. Blanco et al. and Melanelixia glabratula (Lamy) Sandler & Arup.
Taxonomy and phylogeny of theCaloplaca cerinagroup in Europe
Authors: ŠOUN Jaroslav , VONDRÁK Jan , SØCHTING Ulrik , HROUZEK Pavel , KHODOSOVTSEV Alexander , ARUP Ulf
Published: February 2011

Using ITS nrDNA sequence data, theCaloplaca cerinagroup (Teloschistaceae) is defined here as a monophyletic, but internally richly branched lineage. The group is also characterized by a combination of morphological and anatomical characters. Its internal lineages are supported by phenotypic characters in addition to ecology and distribution. Within the largeC. cerinagroup, we have found at least 20 phylospecies in the temperate zone of the Northern Hemisphere. Two species complexes do not produce any vegetative diaspores: the polyphyletic, corticolousCaloplaca cerinas. lat. (six separated cryptic or semi-cryptic species) and the monophyleticC. stillicidiorums. lat. that grows mainly on plant debris, small shrubs and bryophytes and consists of at least four internal lineages. All lineages producing vegetative diaspores (soredia, blastidia, isidia or lobules) are phenotypically characteristic and represent fairly easily distinguishable species:C. chlorina,C. isidiigera,C. monacensis,C. subalpina,C. thracopontica,C. turkuensisandC. ulmorum. Only the North American sorediateC. pinicolapossibly represents an aggregate of species.Caloplaca sterilisis described as a new species. A key to the phenotypically distinguishable species is provided.

Lectotypes are designated forC. albolutea,Caloplaca cerinaf.coronulataand forC. monacensis. The AustralianC. hannesherteliibelongs to this group, but this and other possible species from the Southern Hemisphere are not treated here in detail. Some species traditionally placed in theC. cerinagroup due to their similar morphology are excluded here on the basis of our phenotype examinations and molecular data.Caloplaca albolutea,C. mydalaeaandC. virescensare uncertain taxa and their identities still remain unclear.
Pilophorus fruticosus (Cladoniaceae), a new species from south-western China
Authors: WANG Xin Yu , JOSHI Yogesh , OH Soon Ok , HUR Jae-Seoun , WANG Li Song
Published: February 2011

Pilophorus fruticosus Li S. Wang & Xin Y. Wang is described from south-west China. It is characterized by the presence of densely dichotomously branched, partly decorticated pseudopodetia, and by having single, spherical apothecia on the apices of the pseudopodetia. The species grows on siliceous rocks in alpine regions of the Yunnan Province. A detailed description and illustrations are provided. The new taxon is compared with other Pilophorus species.
Description ofSantelmoa elviraesp. nov. (Teleostei: Zoarcidae) from the Southern Ocean
Authors: Matallanas Jesús
Published: February 2011

Santelmoais diagnosed by the following characters: anterior portion of frontals fused; scapular foramen open; anterior ceratohyal–posterior ceratohyal (=epihyal) articulation interdigitating; cranium narrowed; supratemporal commissure and occipital pores absent; intercalar reaching the prootic; ascending rami of the parasphenoid wing high; palatal arch well developed; posterior hyomandibular ramus short; post-temporal ventral ramus well developed; six branchiostegal rays; vertebrae asymmetrical; pelvic fin rays ensheathed; scales, lateral line, pyloric caeca, palatine and vomerine teeth present. A new species ofSantelmoa, Santelmoa elviraesp. nov., is described on the basis of four specimens collected from the Bellingshausen Sea, Southern Ocean, at a depth of 1837 m. The new species can be distinguished fromSantelmoa carmenae, the type species of the genus and the sole knownSantelmoaspecies, by the following characters: mouth inferior; vertical folds on posterior end of the upper lip and on the lower lip lobe; oral valve nearly reaching the anterior edge of vomer; two posterior nasal pores; lateral line double with ventral and medio-lateral branches; single row of palatine teeth; dorsal fin rays 108–111; anal fin rays 93–94; pectoral fin rays 18–19 and vertebrae asymmetrical, 26–27 + 90–93 = 116–119.
Antifouling activity of marine sessile organisms from China against barnacle settlement
Authors: Feng Danqing , Ke Caihuan , Lu Changyi , Li Shaojing
Published: February 2011

The antifouling activity of a series of hexane, ethyl acetate, ethanol and aqueous extracts from 11 species of marine sessile organisms collected from the south-east coast of China was investigated. Settlement inhibition of cyprid larvae of the barnacleBalanus albicostatuswas used to evaluate their antifouling efficacy. Screening of the 44 extracts showed antifouling activity in 90.9% of the hexane extracts followed by 90.9% of the ethyl acetate, 72.7% of the ethanol and 36.4% of the aqueous extracts. The hexane extracts ofTubularia mesembryanthemum, Notarcus leachii cirrosusandStyela canopus, the ethyl acetate extracts ofBugula neritinaandN. leachii cirrosus,and the ethanol extracts of B. neritinaandAnthopleura sp.were the most active in inhibiting the settlement ofB. albicostatus, with EC50values all below 50 μg/ml. At least one of the four extracts of each tested species exhibited antifouling activity, suggesting that all 11 marine sessile organisms contained antifouling substances and they may have evolved chemical defences against biofouling on their surfaces.
Biomass allocation and phosphorus economics of rain-forest seedlings: effects of fertilization and radiation on soil specialists and soil generalists
Authors: Gleason Sean M. , Read Jennifer , Ares Adrian
Published: February 2011

Concurrent nutrient and radiation limitation in forests may engender trade-offs between P-use and radiation-use efficiency in tree species. To quantify these trade-offs, structural and physiological traits were examined among five rain-forest species subjected to four levels of fertilization and two levels of radiation in a glasshouse experiment. Schist specialists,Cryptocarya lividulaandCeratopetalum virchowii, occur only on P-poor schist soils, whereas soil generalists,Cryptocarya mackinnoniana,Franciscodendron laurifoliumandMyristica insipida, occur on both P-poor schist and P-rich basalt soils. Wild seedlings less than 20 cm tall and 1 y old were collected from field sites, treated with fungicide, sorted into treatments (48 plants per species), and grown for 11 mo. We hypothesized that soil specialists would possess mainly non-plastic traits conferring high P-use efficiency, whereas soil generalists would possess markedly plastic traits conferring high radiation capture and use, enabling them to outcompete specialists on P-rich soils. Only generalistC. mackinnonianaand specialistC. virchowiisupported these hypotheses.Cryptocarya mackinnonianahad more plastic root mass fraction, leaf area ratio, P uptake, and higher C assimilation thanC. virchowii, which resulted in greater relative growth rates in high P treatments, but lower P-use efficiency in low P treatments. In contrast, specialistC. lividulademonstrated similar trait plasticity asC. mackinnoniana, suggesting that plasticity in these traits may be poor indicators of fitness on P-poor soils.
Regional-scale heterogeneity in primate community structure at multiple undisturbed forest sites across south-eastern Peru
Authors: Palminteri Suzanne , Powell George V. N. , Peres Carlos A.
Published: February 2011

The forests of western Amazonia support high site-level biological diversity, yet regional community heterogeneity is poorly understood. Using data from line transect surveys at 37 forest sites in south-eastern Peru, we assessed whether local primate assemblages are heterogeneous at the scale of a major watershed. We examined patterns of richness, abundance and community structure as a function of forest type, hunting pressure, land-management regime and geographic location. The primate assemblage composition and structure varied spatially across this relatively small region of Amazonia (≈ 85 000 km2), resulting from large-scale species patchiness rather than species turnover. Primate species richness varied among sites by a factor of two, community similarity by a factor of four and aggregate biomass by a factor of 45. Several environmental variables exhibited influence on community heterogeneity, though none as much as geographic location. Unflooded forest sites had higher species richness than floodplain forests, although neither numerical primate abundance nor aggregate biomass varied with forest type. Non-hunted sites safeguarded higher abundance and biomass, particularly of large-bodied species, than hunted sites. Spatial differences among species assemblages of a relatively generalist taxon like primates in this largely undisturbed forest region imply that community heterogeneity may be even greater in more species-rich taxa, as well as in regions of greater forest habitat diversity.
Predictable timing of oestrus in the tropical bat Saccopteryx bilineata living in a Costa Rican rain forest
Authors: Greiner Sabine , Schwarzenberger Franz , Voigt Christian C.
Published: February 2011

Many tropical mammals reproduce seasonally, although the circum-equatorial climate is more stable and less seasonal than that of temperate zones. The mechanisms underlying seasonal reproduction in the tropics remain enigmatic. Female reproduction and its relation to environmental factors were investigated in the Neotropical bat species Saccopteryx bilineata. Colonies consist of year-round stable groups of several females that are defended each by an adult male. Females give birth to a single offspring each year and it is suggested that mating is restricted to November and December. In this study, it was asked whether females of a Costa Rican colony come into oestrus around the same time each year and whether oestrus times are synchronized. Oestrogen and progesterone metabolites were monitored from faeces between October and January in four years. Oestrus was identified in 32 females. In addition, climatic factors such as rainfall and temperature were monitored at the study site. Results indicate that (1) females exhibit monoestry, (2) oestrus dates cluster around the first half of December, (3) reproduction is strongly seasonal and highly predictable and (4) oestrus times are possibly influenced by long-term cues like photoperiod and short-term cues like sudden changes in rainfall and temperature.
Longitudinal and spatial distribution of GP60 subtypes in human cryptosporidiosis cases in Ireland
Authors: ZINTL A. , EZZATY-MIRASHEMI M. , CHALMERS R. M. , ELWIN K. , MULCAHY G. , LUCY F. E. , DE WAAL T.
Published: February 2011

Within Europe, Ireland has one of the highest reported infection rates with the diarrhoeal protozoan pathogen Cryptosporidium. In this study 249 Cryptosporidium parvum isolates collected from Irish patients between 2000 and 2009 were subtyped by sequence analysis of the GP60 locus. A subsample of 127 isolates was also typed at the MS1 and ML1 loci. GP60 subtype IIaA18G3R1 was the predominant subtype in every year and every season throughout the country. Over the 10-year period there was no evidence that host immunity to the predominant subtype caused a shift in its prevalence. Length frequency distributions of the GP60 TCA/TCG repeats compiled from published data, showed distinct patterns for countries with predominantly zoonotic or anthroponotic transmission cycles, respectively. Although considered to be mostly affected by zoonotic cryptosporidiosis, the GP60 fragment length of Irish C. parvum isolates mirrored that of countries with predominantly human-to-human transmission, indicating more complex routes of infection between livestock and humans. Due to their homogeneity, ML1 and MS1 were not considered useful loci for subtyping C. parvum strains in Ireland.
Shigellosis outbreak linked to canteen-food consumption in a public institution: a matched case-control study
Authors: GUTIÉRREZ GARITANO I. , NARANJO M. , FORIER A. , HENDRIKS R. , DE SCHRIJVER K. , BERTRAND S. , DIERICK K. , ROBESYN E. , QUOILIN S.
Published: February 2011

On 13 November 2009, the authorities of Flemish Brabant, Belgium, received an alert concerning a potential outbreak ofShigella sonneiat a public institution. A study was conducted to assess the extent, discover the source and to implement further measures. We performed a matched case-control study to test an association between shigellosis and canteen-food consumption. Water samples and food handlers' faecal samples were tested. The reference laboratory characterized the retrospectively collectedShigellaspecimens. We found 52 cases distributed over space (25/35 departments) and time (2 months). We found a matched odds ratio of 3·84 (95% confidence interval 1·02–14·44) for canteen-food consumption. A food handler had travelled to Morocco shortly before detection of the first laboratory-confirmed case. Water samples and food handlers' faecal samples tested negative forShigella. Confirmed cases presented PFGE profiles, highly similar to archived isolates from Morocco. Foodborne transmission associated with the canteen was strongly suspected.
An overview of the epidemic of highly pathogenic H5N1 avian influenza virus in Egypt: epidemiology and control challenges
Authors: ABDELWHAB E. M. , HAFEZ H. M.
Published: February 2011

Emergence of the highly pathogenic avian influenza (HPAI) H5N1 virus in Egypt in mid-February 2006 caused significant losses for the poultry industry and constituted a potential threat to public health. Since late 2007, there has been increasing evidence that stable lineages of H5N1 viruses are being established in chickens and humans in Egypt. The virus has been detected in wild, feral and zoo birds and recently was found in donkeys and pigs. Most of the outbreaks in poultry and humans occurred in the highly populated Nile delta. The temporal pattern of the virus has changed since 2009 with outbreaks now occurring in the warmer months of the year. Challenges to control of endemic disease in Egypt are discussed. For the foreseeable future, unless a global collaboration exists, HPAI H5N1 virus in Egypt will continue to compromise the poultry industry, endanger public health and pose a serious pandemic threat.
Emplacement of magma at shallow depth: insights from field relationships at Allan Hills, south Victoria Land, East Antarctica
Authors: Airoldi Giulia , Muirhead James D. , White James D.L. , Rowland Julie
Published: February 2011

Allan Hills nunatak, south Victoria Land, Antarctica, exposes an exceptional example of a shallow depth (< 500 m) intrusive complex formed during the evolution of the Ferrar large igneous province (LIP). Dyke distribution, geometries and relationships allow reconstruction of its history and mechanics of intrusion. Sills interconnect across host sedimentary layers, and a swarm of parallel inclined dolerite sheets is intersected by a radiating dyke-array associated with remnants of a phreatomagmatic vent, where the dolerite is locally quenched and mixed to form peperite. Intrusion geometries, and lack of dominant rift-related structures in the country rock indicate that magma overpressure, local stresses between mutually interacting dykes and vertical variations of host rock mechanical properties controlled the intrusive process throughout the thick and otherwise undeformed pile of sedimentary rocks (Victoria Group). Dolerite sills connected to one another by inclined sheets are inferred to record the preferred mode of propagation for magma-carrying cracks that represent the shallow portions of the Ferrar LIP plumbing system.
Corrections for interferences and extraction conditions make a difference: use of the TBARS assay for lipid peroxidation of orthodoxSpartina pectinataand recalcitrantSpartina alternifloraseeds during desiccation
Authors: Chappell James H. , Cohn Marc Alan
Published: February 2011

Lipid peroxidation and membrane damage are often proposed as causes of recalcitrant seed death, and the thiobarbituric acid reactive substances (TBARS) assay is commonly used to measure lipid peroxidation. However, several artefacts can cause an overestimation of TBARS values, and these have not been routinely addressed in experiments with recalcitrant seeds. In the present report, TBARS was assayed as recalcitrantSpartina alternifloraand orthodoxS. pectinataseeds were dried rapidly. Using the traditional Heath and Packer (1968) protocol with tissue extraction at 4°C,S. alterniflorahad higher overall TBARS values thanS. pectinata, and TBARS products increased when recalcitrantS. alternifloraand orthodoxS. pectinataseeds were dried. However, when corrections for interfering substances, such as sugars and anthocyanins, were made, the TBARS values between the two species were almost identical. When seeds were freeze-clamped in liquid nitrogen prior to extraction, TBARS did not increase during desiccation for either species. These findings may indicate that lipid peroxidation is not the cause of desiccation-induced death inS. alterniflora. Therefore, freeze-clamping during tissue extraction and corrections for TBARS interfering substances must be applied to avoid overestimation of lipid peroxidation values.
Bayesian conditioning of a rainfall‐runoff model for predicting flows in ungauged catchments and under land use changes
Authors: Bulygina Nataliya , McIntyre Neil , Wheater Howard
Published: February 2011

A novel method is presented for conditioning rainfall‐runoff models for ungauged catchment and land use impact applications. The method conditions the model on information from multiple regionalized response indices using a formal Bayesian approach. Two indices that hold information about soil type and land use effects are the base flow index from the Hydrology of Soil Type (HOST) classification and curve number from the U.S. Department of Agriculture's Soil Conservation Service soil and land use classification. These indices are used to constrain a five‐parameter probability distributed moisture model for subcatchments of the Wye (grazed grassland) and Severn (mainly afforested) catchments in the United Kingdom. The base flow index and curve number constrain only two of the five model parameters, indicating that ideally, other sources of information would be sought. Nevertheless, the procedure significantly reduces the prior uncertainty in runoff prediction and gives predictions close to those of the calibrated models. For the case study, the introduction of the curve number in addition to the base flow index has only a small effect on model performance and uncertainty; however, it allows a distinction between the effects of soil type and land management for the purpose of scenario analysis. The principal assumptions used in the method are the applicability of the curve number classification system and its mapping to UK soil types and the likelihood function used for Bayesian conditioning.
Genomes, race and health
Authors: Wolinsky Howard
Published: February 2011

Considering a patient's ethnic background can make some diagnoses easier. Yet, ‘racial profiling’ is a highly controversial concept and might soon be replaced by the advent of individualized medicine.
Hierarchy of folding and unfolding events of protein G, CI2, and ACBP from explicit-solvent simulations
Authors: Camilloni Carlo , Broglia Ricardo A. , Tiana Guido
Published: February 2011

The study of the mechanism which is at the basis of the phenomenon of protein folding requires the knowledge of multiple folding trajectories under biological conditions. Using a biasing molecular-dynamics algorithm based on the physics of the ratchet-and-pawl system, we carry out all-atom, explicit solvent simulations of the sequence of folding events which proteins G, CI2, and ACBP undergo in evolving from the denatured to the folded state. Starting from highly disordered conformations, the algorithm allows the proteins to reach, at the price of a modest computational effort, nativelike conformations, within a root mean square deviation (RMSD) of approximately 1 Å. A scheme is developed to extract, from the myriad of events, information concerning the sequence of native contact formation and of their eventual correlation. Such an analysis indicates that all the studied proteins fold hierarchically, through pathways which, although not deterministic, are well-defined with respect to the order of contact formation. The algorithm also allows one to study unfolding, a process which looks, to a large extent, like the reverse of the major folding pathway. This is also true in situations in which many pathways contribute to the folding process, like in the case of protein G.
Influence of a high vacuum on the precise positioning using an ultrasonic linear motor
Authors: Kim Wan-Soo , Lee Dong-Jin , Lee Sun-Kyu
Published: February 2011

This paper presents an investigation of the ultrasonic linear motor stage for use in a high vacuum environment. The slider table is driven by the hybrid bolt-clamped Langevin-type ultrasonic linear motor, which is excited with its different modes of natural frequencies in both lateral and longitudinal directions. In general, the friction behavior in a vacuum environment becomes different from that in an environment of atmospheric pressure and this difference significantly affects the performance of the ultrasonic linear motor. In this paper, to consistently provide stable and high power of output in a high vacuum, frequency matching was conducted. Moreover, to achieve the fine control performance in the vacuum environment, a modified nominal characteristic trajectory following control method was adopted. Finally, the stage was operated under high vacuum condition, and the operating performances were investigated compared with that of a conventional PI compensator. As a result, robustness of positioning was accomplished in a high vacuum condition with nanometer-level accuracy.
Kinetics of electron attachment to SF3CN, SF3C6F5, and SF3 and mutual neutralization of Ar+ with CN− and C6F5−
Authors: Shuman Nicholas S. , Miller Thomas M. , Viggiano A. A. , Luzik Eddie D. , Hazari Nilay
Published: February 2011

The additions of two sulfur fluoride derivatives (SF3C6F5 and SF3CN) to a flowing afterglow were studied by variable electron and neutral density mass spectrometry. Data collection and analysis were complicated by the high reactivity of the neutral species. Both species readily dissociatively attach thermal electrons at 300 K to yield SF3 + X− (X = C6F5, CN). Attachment to SF3C6F5 also results in SF3− + C6F5 as a minor product channel. The determined electron attachment rate constants were \documentclass[12pt]{minimal}\begin{document}$1^{+1}_{-0.6}$\end{document}1−0.6+1 × 10−7 cm3 s−1 for SF3C6F5, a lower limit of 1 × 10−8 cm3 s−1 for SF3CN, and 4 ± 3 × 10−9 cm3 s−1 for SF3. Mutual neutralization rate constants of C6F5− and CN− with Ar+ at 300 K were determined to be \documentclass[12pt]{minimal}\begin{document}$5.5^{+1.0}_{-1.6}$\end{document}5.5−1.6+1.0 × 10−8 and 3.0 ± 1 × 10−8 cm3 s−1, respectively.
Jupp and Kent's cubics in Lie groups
Authors: Pauley Michael
Published: February 2011

We study a generalization of the cubic polynomial to Riemannian manifolds and other affine connection spaces, modifying the differential equation \documentclass[12pt]{minimal}\begin{document}$x^{(4)} = 0$\end{document}x(4)=0 by replacing higher derivatives with covariant derivatives. In matrix groups, with two particular choices of a left-invariant connection, we can convert the equation into a system of first order linear differential equations. We give asymptotics in a generic case in GL(n) and in the n-sphere.
Charge and spin transport in graphene-based heterostructure
Authors: Zeng Minggang , Shen Lei , Yang Ming , Zhang Chun , Feng Yuanping
Published: February 2011

We investigate electron transport properties of a heterostructure based on zigzag graphene nanoribbon (ZGNR) by first-principles calculations. This heterostructure consists of hydrogen-terminated ZGNR (ZGNR-H) and oxygen-terminated ZGNR (ZGNR-O). We find that both charge and spin transport can be well controlled with the ZGNR-H/ZGNR-O heterostructure. A large charge transmission gap appears near the Fermi energy, and rectification behavior is observed. Moreover, the ZGNR-H/ZGNR-O heterostructure can act as a perfect bipolar spin filter or magnetoresistance device. Our results show that the ZGNR-H/ZGNR-O heterostructure hold promise for combining magnetoelectronics and conventional charge-based electronics.
Tailoring band gap in GaN sheet by chemical modification and electric field: Ab initio calculations
Authors: Chen Qian , Hu Hong , Chen Xiaojie , Wang Jinlan
Published: February 2011

Ab initio calculations show that the GaN monolayer (GaN-ML) in (0001) face is a planar semiconductor with an indirect band gap of 1.95 eV. The gap converts into a direct one and is enlarged by 0.81 eV when the GaN-ML is modified by H and F atoms. Furthermore, the gap can be efficiently manipulated in a range of 1.8 to 3.5 eV by applying an external electric field. Moreover, because of the spontaneous polarization, the gap is remarkably broadened by a positive electric field while it is rapidly decreased under a negative field. The chemical modification also significantly improves the stability of GaN-ML.
Ligament and joint sizes govern softening in nanoporous aluminum
Authors: To A. C. , Tao J. , Kirca M. , Schalk L.
Published: February 2011

The present computational study demonstrates that softening of an open cell nanoporous aluminum structure subjected to tensile loading can be significantly reduced when the size of ligaments and the joints that connect them in the structure is designed to be sufficiently small. It is found using molecular dynamics simulations that the softening becomes slightly slower with increasing porosity for the structures with porosity less than or equal to 72%, and stress localization is observed during softening. In contrast, for structures with more than 75% porosity, softening is much slower, and stress delocalization occurs during softening. It is argued that at relatively high porosity, softening is governed by both the ligament size and the joint size because their compliance becomes high enough to allow the overloading stress due to ligament rupture to be redistributed more effectively throughout the structure.
Facilitating science in developing countries
Authors: Feder Toni
Published: February 2011

Smart people are everywhere, but they need resources to realize their talents.
What Did the Early American Presidents Really Look Like? Gilbert Stuart Portraits as a “Rosetta Stone” to the Pre-Photography Era
Authors: Ehinger Krista A , Altschuler Eric L
Published: February 2011

The American painter Gilbert Stuart (1755–1828) painted many prominent individuals, including the first six presidents of the United States, and several of his later subjects were also photographed. We compared these photographs to Stuart's portraits of the same individuals and characterized the differences between Stuart's representations and his subjects' actual appearances. This allows us to create more photographic likenesses of other Stuart subjects, including individuals who lived before the invention of photography.