bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical behavior of nonintersecting Brownian motions at a tacnode
Authors: Delvaux Steven , Kuijlaars Arno B. J. , Zhang Lun
Published: May 2011

We study a model of n one‐dimensional, nonintersecting Brownian motions with two prescribed starting points at time t = 0 and two prescribed ending points at time t = 1 in a critical regime where the paths fill two tangent ellipses in the time‐space plane as n → ∞. The limiting mean density for the positions of the Brownian paths at the time of tangency consists of two touching semicircles, possibly of different sizes. We show that in an appropriate double scaling limit, there is a new family of limiting determinantal point processes with integrable correlation kernels that are expressed in terms of a new Riemann‐Hilbert problem of size 4 × 4. We prove solvability of the Riemann‐Hilbert problem and establish a remarkable connection with the Hastings‐McLeod solution of the Painlevé II equation. We show that this Painlevé II transcendent also appears in the critical limits of the recurrence coefficients of the multiple Hermite polynomials that are associated with the nonintersecting Brownian motions. Universality suggests that the new limiting kernels apply to more general situations whenever a limiting mean density vanishes according to two touching square roots, which represents a new universality class. © 2011 Wiley Periodicals, Inc
Towards automated HPC scheduler configuration tuning
Authors: Krishnamurthy Diwakar , Alemzadeh Mehrnoush , Moussavi Mahmood
Published: May 2011

High performance computing (HPC) systems allow researchers and businesses to harness large amounts of computing power needed for solving complex problems. In such systems a job scheduler prioritizes the execution of jobs belonging to users of the system in a manner that allows the system to satisfy performance objectives for various groups of users while simultaneously making efficient use of available resources. Typically, system administrators have the responsibility of manually configuring or tuning the job scheduler such that the performance objectives of user groups as well as system‐level performance objectives are met. Modern job schedulers used in production systems are quite complex. Through detailed trace‐driven simulations, we show that manually tuning the configuration of production schedulers in an environment characterized by multiple performance objectives is very challenging and may not be feasible. To alleviate this problem, this paper describes a toolset that can help a system administrator to automatically configure a scheduler such that the performance objectives for various classes of users in the system as well as other system‐level performance objectives can be satisfied. A unique aspect of this work that differentiates it from the existing work on scheduler tuning is that it has been implemented to work with a widely used production scheduler. Furthermore, in contrast to the existing work it considers the challenging real‐world problem of delivering different levels of performance to different classes of users. System administrators can exploit the toolset to react quickly to changes in performance objectives and workload conditions. Case studies using synthetic and real HPC workloads demonstrate the effectiveness of the technique. Copyright © 2011 John Wiley & Sons, Ltd.
DHTrust: a robust and distributed reputation system for trusted peer‐to‐peer networks
Authors: Xue Weilian , Liu Yaqiong , Li Keqiu , Chi Zhongxian , Min Geyong , Qu Wenyu
Published: May 2011

The anonymity and dynamic character of a Peer‐to‐Peer (P2P) network makes it an ideal medium for selfish and vicious action. In order to solve this problem, P2P reputation systems are proposed to evaluate the trustworthiness of peers and to prevent the selfish, dishonest, and malicious peers' behaviors, which collects local reputation scores and aggregates them into the global reputation. In this paper we propose a DHT (Distributed Hash Table) trust overlay network (DHTON) to model the network structure and the storage of reputation information. We also design a robust and distributing reputation system, DHTrust, which takes full advantage of the DHT to distribute local reputation to trade‐off the damage of fake reputation information by genuine reputation information. By using the trust evaluation towards two reputation scores, we can also distinguish and evaluate the fundamental behaviors of peers in the P2P network, i.e. providing service and issuing reputation scores. To adapt to the dynamic P2P networks, we take dynamic node mechanism into account. Our scheme can assure convergence effectiveness and robustness, when nodes enter or leave the system. We conduct extensive simulations to evaluate the performance of DHTrust. The results show that our system makes significant improvement in convergence speed and aggregation accuracy. Moreover, it is robust to malicious peers. Copyright © 2011 John Wiley & Sons, Ltd.
Asynchronous event handling and Safety Critical Java
Authors: Wellings Andy , Kim MinSeong
Published: May 2011

Over the last few years, the Java Community Process (under the auspices of Java Specification Request 302) has been developing a subset of Java augmented by the Real‐Time Specification for Java (RTSJ) for use in safety critical systems. The concurrency model supported by Safety Critical Java (SCJ) relies almost exclusively on an event‐based model rather than on a thread‐based model. This paper reviews the advantages and disadvantages of the two models and gives the pragmatic reasons that SCJ has adopted the former model. It describes the SCJ approach and gives a simple example of how it can be used, illustrating the difference in style between the RTSJ and SCJ code. The paper then considers the compatibility of the SCJ model with the RTSJ. It argues that by basing the SCJ classes on the RTSJ's BoundAsyncEvent class, some inconsistencies exist between the SCJ and the RTSJ models. Furthermore, some of the optimizations that are possible when mapping handlers to server threads are inhibited, even though the programming restrictions necessary for these optimizations are imposed by the SCJ specification. A revised model is presented that has a slightly more complicated API but is more consistent with the RTSJ and allows the optimizations. However, there is a resulting increase in the necessary run‐time support, particularly for multiprocessor implementations. Copyright © 2011 John Wiley & Sons, Ltd.
Scalability and locality of extrapolation methods on large parallel systems
Authors: Korch Matthias , Rauber Thomas , Scholtes Carsten
Published: May 2011

Time‐dependent processes can often be modeled by systems of ordinary differential equations (ODEs). Solving such a system for a detailed model can be highly computationally intensive. We investigate explicit extrapolation methods for solving such systems efficiently on current highly parallel supercomputer systems with shared‐or distributed‐memory architecture. We analyze and compare the scalability of several parallelization variants, some of them using multiple levels of parallelization. For a large class of ODE systems, data access costs are reduced considerably by exploiting the special structure of the ODE system. Furthermore, by employing a pipeline‐like loop structure, the locality of memory references is increased for such systems resulting in a better utilization of the cache hierarchy. Runtime experiments show that the optimized implementations can deliver a high scalability. Copyright © 2011 John Wiley & Sons, Ltd.
Self‐adaptive clock frequency recovery based on buffer control
Authors: Lu Yueming , Ji Yuefeng
Published: May 2011

With high‐speed packet networks and packet transport networks (PTNs) beginning to support transmissions of high‐speed time division multiplex and multiplexer (TDM) and 3G services, the clock recovery in packet networks becomes significant and challengeable. This paper proposes a self‐adaptive clock frequency recovery based on buffer control to support the clock recovery in packet networks. It includes an estimation part and an amend part, estimates clock frequencies using the dynamic moving average algorithm, amends clock frequencies according to feedbacks, and balances stability, convergence, and system faults. Simulations show that the method has the ability of self‐adaption, avoids the buffer overflow and underflow, and achieves better accuracy, less packet delay, as well as better convergence ability. Copyright © 2011 John Wiley & Sons, Ltd.
Clustering‐based power‐controlled routing for mobile wireless sensor networks
Authors: Khan Atta ur Rehman , Madani Sajjad A. , Hayat Khizar , Khan Samee Ullah
Published: May 2011

This paper presents two new routing protocols for mobile sensor networks, viz. power‐controlled routing (PCR) and its enhanced version, i.e. Enhanced Power‐Controlled Routing (EPCR). In both the protocols, fixed transmission power is employed in the clustering phase but when ordinary nodes are about to send their data to their respective cluster‐heads, they change their transmission power according to their distance from their cluster‐head. While in PCR, the nodes are associated with the cluster‐head on the basis of weight, in EPCR it is done on the basis of distance. In addition to the protocols, we are suggesting a packet loss recovery mechanism for the PCR and EPCR. Both protocols work well for both mobile and static networks and are designed to achieve high network lifetime, high packet delivery ratio, and high network throughput. These protocols are extensively simulated using mass mobility model, with different speeds and different number of nodes to evaluate their performance. Simulation results show that both PCR and EPCR are successful in achieving their objectives by using variable transmission powers and smart clustering. Copyright © 2011 John Wiley & Sons, Ltd.
Myocyte proliferation in the developing heart
Authors: Sedmera David , Thompson Robert P.
Published: May 2011

Regulation of organ growth is critical during embryogenesis. At the cellular level, mechanisms controlling the size of individual embryonic organs include cell proliferation, differentiation, migration, and attrition through cell death. All these mechanisms play a role in cardiac morphogenesis, but experimental studies have shown that the major determinant of cardiac size during prenatal development is myocyte proliferation. As this proliferative capacity becomes severely restricted after birth, the number of cell divisions that occur during embryogenesis limits the growth potential of the postnatal heart. We summarize here current knowledge concerning regional control of myocyte proliferation as related to cardiac morphogenesis and dysmorphogenesis. There are significant spatial and temporal differences in rates of cell division, peaking during the preseptation period and then gradually decreasing toward birth. Analysis of regional rates of proliferation helps to explain the mechanics of ventricular septation, chamber morphogenesis, and the development of the cardiac conduction system. Proliferation rates are influenced by hemodynamic loading, and transduced by autocrine and paracrine signaling by means of growth factors. Understanding the biological response of the developing heart to such factors and physical forces will further our progress in engineering artificial myocardial tissues for heart repair and designing optimal treatment strategies for congenital heart disease. Developmental Dynamics 240:1322–1334, 2011. © 2011 Wiley‐Liss, Inc.
Epigenetics in C. elegans: Facts and challenges
Authors: Wenzel Dirk , Palladino Francesca , Jedrusik‐Bode Monika
Published: May 2011

Epigenetics is defined as the study of heritable changes in gene expression that are not accompanied by changes in the DNA sequence. Epigenetic mechanisms include histone post‐translational modifications, histone variant incorporation, non‐coding RNAs, and nucleosome remodeling and exchange. In addition, the functional compartmentalization of the nucleus also contributes to epigenetic regulation of gene expression. Studies on the molecular mechanisms underlying epigenetic phenomena and their biological function have relied on various model systems, including yeast, plants, flies, and cultured mammalian cells. Here we will expose the reader to the current understanding of epigenetic regulation in the roundworm C. elegans. We will review recent models of nuclear organization and its impact on gene expression, the biological role of enzymes modifying core histones, and the function of chromatin‐associated factors, with special emphasis on Polycomb (PcG) and Trithorax (Trx‐G) group proteins. We will discuss how the C. elegans model has provided novel insight into mechanisms of epigenetic regulation as well as suggest directions for future research. genesis 49:647–661, 2011. © 2011 Wiley‐Liss, Inc
Combination of lentivector immunization and low‐dose chemotherapy or PD‐1/PD‐L1 blocking primes self‐reactive T cells and induces anti‐tumor immunity
Authors: Sierro Sophie R. , Donda Alena , Perret Rachel , Guillaume Philippe , Yagita Hideo , Levy Frédéric , Romero Pedro
Published: May 2011

In the last two decades, anti‐cancer vaccines have yielded disappointing clinical results despite the fact that high numbers of self/tumor‐specific T cells can be elicited in immunized patients. Understanding the reasons behind this lack of efficacy is critical in order to design better treatment regimes. Recombinant lentivectors (rLVs) have been successfully used to induce antigen‐specific T cells to foreign or mutated tumor antigens. Here, we show that rLV expressing a murine nonmutated self/tumor antigen efficiently primes large numbers of self/tumor‐specific CD8+ T cells. In spite of the large number of tumor‐specific T cells, however, no anti‐tumor activity could be measured in a therapeutic setting, in mice vaccinated with rLV. Accumulating evidence shows that, in the presence of malignancies, inhibition of T‐cell activity may predominate overstimulation. Analysis of tumor‐infiltrating lymphocytes revealed that specific anti‐tumor CD8+ T cells fail to produce cytokines and express high levels of inhibitory receptors such as programmed death (PD)‐1. Association of active immunization with chemotherapy or antibodies that block inhibitory pathways often leads to better anti‐tumor effects. We show here that combining rLV vaccination with either cyclophosphamide or PD‐1 and PD‐L1 blocking antibodies enhances rLV vaccination efficacy and improves anti‐tumor immunity.
Intramolecular Butenolide Allene Photocycloadditions and Ensuing Retro‐Ene Reactions of Some Photoadducts
Authors: Lutteke Ginger , Kleinnijenhuis Roel A. , Jacobs Ivo , Wrigstedt Pauli J. , Correia Ana C. A. , Nieuwenhuizen Rowan , Buu Hue B. T. , Goubitz Kees , Peschar René , van Maarseveen Jan H. , Hiemstra Henk
Published: May 2011

This report describes intramolecular [2+2] photocycloadditions of several butenolides with an allenylmethyl substituent at the 5‐position. These photosubstrates were prepared from 2‐(silyloxy)furans through silver‐mediated reactions with allenylmethyl bromides. Two cases were studied where the lactone was replaced by an N‐Boc‐lactam. Irradiations of the photosubstrates were carried out with 300 nm UV‐light in acetonitrile/acetone mixtures. Crossed cycloadducts were produced in good yields via cycloaddition of the heterocyclic double bond with the allene internal double bond. The products were γ‐lactones (γ‐lactams) containing the strained 5‐methylenebicyclo[2.1.1]hexane skeleton. In some cases the products were unstable due to remarkably facile retro‐ene reactions (1,5‐hydrogen shifts) leading to unique α,β‐unsaturated γ‐lactone derivatives. These reactions occurred only with well‐oriented C–H bonds so that strain‐releasing four‐membered ring opening could take place. This retro‐ene reaction was studied in detail for more highly substituted derivatives in order to establish its relevance in connection with the instability of the natural terpenoid solanoeclepin A, the hatching agent of potato cyst nematodes. To this end, the methylenecyclobutane moiety in one of the cycloadducts was converted into a bicyclo[2.1.1]hexan‐5‐one (cyclobutanone) substructure.
Copper‐Catalyzed Aerobic Oxidative Cyclization of Hydrazones to Pyrazolidinones
Authors: Dos Santos Aurélie , El Kaïm Laurent , Grimaud Laurence , Ronsseray Caroline
Published: May 2011

N‐Aryl hydrazones participate, under copper catalysis, in a [3+2] cycloaddition/aerobic oxidation cascade reaction to form pyrazolidinones. The starting hydrazones were prepared by three‐component coupling of allylic amines, acyl chlorides, and aryl diazonium salts.
Theoretical Investigation of Electrochemical Signal from Nanoscale Systems
Authors: Liang Shuai , Dong Xiandui
Published: May 2011

In this paper, we report a theoretical study exploring the stochastic signal from electrochemical detection toward the nanometer scale systems. By using a discrete simulation as well as a statistical theory, this work investigates the distribution of the capturing times for redox molecules that released at a given distance from an electrode. We find that the capturing times tend to distribute over a wider range with a larger distance between the molecule’s source and the electrode, and thus the corresponding electrochemical signal would be somewhat less repeatable.
Pathways of Electrochemical Oxidation of Indolic Compounds
Authors: Enache Teodor Adrian , Oliveira‐Brett Ana Maria
Published: May 2011

The electrochemical behaviour of indole and a group of indole‐containing compounds with a substituent at the C3 position, indol‐3‐acetamide (IAM), tryptamine, gramine, indole acetic acid (IAA), indole propionic acid (IPA), indole butyric acid (IBA) and tryptophan, was investigated at a glassy carbon electrode, in order to determine their oxidation pathways. Indole undergoes one irreversible pH dependent oxidation, whereas the oxidation process of indole derivatives was more complex, a two step, the oxidation at C2 position on the pyrrole ring followed by the hydroxylation at the C7 position of the benzene moiety of indoles, irreversible pH dependent oxidation.
Characterization of Iron Sulfide Species in Model Solutions by Cyclic Voltammetry. Revisiting an Old Problem
Authors: Bura‐Nakić E. , Krznarić D. , Helz G. R. , Ciglenečki I.
Published: May 2011

A long‐standing problem associated with voltammetric determination of iron and sulfide in reduced natural waters has been the nature of the presumed analyte responsible for a reduction peak at −1.1 V vs. Ag/AgCl. Cyclic voltammetry at the Hg electrode is used here to study solutions with different Fe(II) to sulfide ratios in chloride and acetate electrolytes (pH 6–7). The results indicate that the −1.1 V peak can be assigned to reduction of Fe2+ or its labile complexes on FeS layers that partially cover the Hg electrode. Hg electrodes covered with FeS act like FeS solid electrodes over a very wide potential range (−0.35 to −1.9 V). Two mechanisms for forming FeS layers on Hg are described. Over the broadest deposition potential range, the dominant mechanism involves attachment at the Hg surface of FeS nanoparticles, which are generated quickly in initially supersaturated mixtures of Fe(II) and S(–II). In a narrow deposition potential range, roughly −0.56 to −0.70, FeS layers are produced additionally by replacement of preformed HgS. Because Fe2+ is reduced at −1.1 V on FeS layers and at −1.4 V on bare Hg, it may be underdetermined when only the −1.4 V peak is measured.
Development of a Carbon Paste Electrode for Lactate Detection Based on Meldola’s Blue Adsorbed on Silica Gel Modified with Niobium Oxide and Lactate Oxidase
Authors: Pereira Arnaldo C. , Kisner Alexandre , Tarley César R. T. , Kubota Lauro T.
Published: May 2011

A reagentless amperometric biosensor sensitive to lactate was developed. The sensor employs a carbon paste electrode modified with lactate oxidase (LOx) and Meldola’s Blue (MB) adsorbed on silica gel coated with niobium oxide. The dependence on the biosensor response was investigated in terms of pH, supporting electrolyte, ionic strength, lactate oxidase (LOx) amounts and applied potential. The biosensor showed an excellent operational stability (96 % of the activity was maintained after 150 determinations) and storage stability (allowing measurements for more than 1.5 months, when stored in a refrigerator). The proposed biosensor also presented good sensitivity allowing lactate quantification at levels down to 6.5×10−7 mol L−1. Moreover, the biosensor showed a good linear response range (from 0.1 to 5.0 mmol L−1 for lactate). Lactate analysis in biological samples such as blood was also performed. The precision of the data obtained by the proposed biosensor showed reliable results for real complex matrices.
Cationic poly(amidoamine) dendrimers as additives for capillary electroseparation and detection of proteins
Authors: Liu Qingchun , Tian Jing , Zhang Chenling , Yang Huan , Liu Yang , Qin Weidong , Liu Zhengping
Published: May 2011

We examine the influence of cationic poly(amidoamine) (PAMAM) dendrimers on capillary electroseparation–UV analysis of proteins. PAMAMs adsorbing to the capillary surface suppressed the wall‐adsorption of proteins; meanwhile, PAMAMs added to the buffer exhibited selectivity toward proteins. Presence of 3×10−4 g/mL PAMAM generation one (G 1.0) in 30 mM phosphate, at pH 2.6, rendered significant enhancement in separation efficiency; the merged peaks of myoglobin and trypsin inhibitor were separated. Moreover, the protein–dendrimer interactions changed the inherent UV absorbance profiles of proteins. UV–Vis study showed that the absorbance of cytochrome C and transferrin increased at the detection wavelength of 214 nm; their detection sensitivity enhanced by 2.44 and 2.01‐folds, respectively, with addition of 5×10−4 g/mL PAMAM G 1.0.
CEC separation of ofloxacin enantiomers using imprinted microparticles prepared in molecular crowding conditions
Authors: Shi Xiao‐Xu , Xu Liang , Duan Hong‐Quan , Huang Yan‐Ping , Liu Zhao‐Sheng
Published: May 2011

Molecular crowding is a new concept to obtain molecularly imprinted polymers (MIPs) with greater capacity and selectivity, which could shift the equilibrium of a print molecule reacting with functional monomers in the direction of complex formation side. In this work, molecular crowding agent was first applied to the preparation of MIPs microparticles by precipitation polymerization. A new system of molecular crowding surrounding was developed, composed of polystyrene and tetrahydrofuran, in the presence of the template (S)‐ofloxacin. Partial filling capillary electrochromatography (CEC) was utilized to evaluate imprinting effect of the resulting microparticles by chiral separations of ofloxacin. Some important parameters in the preparation, i.e. template to monomer ratio, influence of cross‐linking monomers and functional monomer composition on the CEC separation of MIP microparticles were investigated. Baseline separation of ofloxacin (Rs=1.53) was obtained under optimized conditions and the highest theory plate of the later eluent (S)‐ofloxacin was 5400. The textural and morphological parameters for imprinted particles, such as Brunauer–Emmett–Teller surface areas, pore volumes and pore size distributions have also been determined. Compared to the MIP microparticle prepared by conventional precipitation polymerization, the (S)‐ofloxacin‐imprinted particles formed under molecular crowding conditions showed higher selectivity (α=1.09) and separation efficiency (<25 min) in the CEC mode.
Peptide fractionation by acid pH SDS‐free electrophoresis
Authors: Ramos Yassel , Garcia Yairet , Pérez‐Riverol Yasset , Leyva Alejandro , Padrón Gabriel , Sánchez Aniel , Castellanos‐Serra Lila , González Luis J. , Besada Vladimir
Published: May 2011

SDS‐free polyacrylamide gel electrophoresis is an effective alternative approach to peptide fractionation. Here we describe a discontinuous buffer system at acid pH that improves the separation of acidic peptides from tryptic digestion. MOPS and chloride act as trailing and leading ions, respectively, in this system, while histidine operates as counterion and buffers all solutions. In these electrophoretic conditions, peptides with pI below 5.5 migrate with low overall electrophoretic mobilities but high differences from one another, which allows for their efficient resolution. In silico analysis of several proteomes shows that the acid pH system allows a peptide simplification of 2.5‐fold with respect to the total peptide mixture, and still a proteome coverage of about 95% is achievable. A straightforward method with a protocol including proteomic studies was achieved for SDS‐PAGE of proteins, enzyme treatment and further peptide fractionation by SDS‐free acid PAGE.
Electro‐osmotic flow in polygonal ducts
Authors: Wang Chang‐Yi , Chang Chien‐Cheng
Published: May 2011

The paper presents semi‐analytical solutions to electro‐osmotic (EO) flow through polygonal ducts under the Debye–Hückel approximation. Analytical series solutions assisted with numerical collocations are found to yield very fast convergence. The solutions have practical applications as the pores of EO membranes are mostly hexagonal, stacked densely in a beehive‐like matrix. In addition, we develop simple asymptotic approximations that would be applicable to all EO tube flows of small as well as large dimensionless electrokinetic width. This facilitates investigation of analytical structures of general EO flows in all shapes of tubes, including the present geometries. In particular, for thick electrical double layers, the flow rate of EO is related to the corresponding viscous Poiseuille flow rate, while for thin electrical double layers, the flow rate is shown to be characterized by the cross‐sectional area and the perimeter length of the tubes.
A Horvitz–Thompson‐type estimator of species richness
Authors: Magnussen Steen
Published: May 2011

A Horvitz–Thompson‐type estimator of species richness for plot (cluster) sampling is constructed by considering species sampling as sampling with an unequal probability. Inclusion probabilities are estimated from sample‐based estimates of relative species incidence. Bias is addressed by adding, to each observed species, the expected number of unseen species with the same relative incidence. A Hansen–Hurwitz estimator of variance is adopted and augmented by the anticipated variance from sample‐based inclusion probabilities and the number of observed species. In Monte Carlo simulation of simple random plot (cluster) sampling from 11 large finite populations of forest trees and three sample sizes, the proposed estimator achieved the best overall ranking in terms of relative root mean square error efficiency when compared to 12 alternative estimators. The proposed estimator ranked third in terms of bias. The augmented Hansen–Hurwitz estimator of variance was liberal (median −13%). No richness estimator was uniformly best across populations and sample sizes. Across all settings, the performance of the best four estimators was similar, both in terms of bias and relative root mean square error efficiency. Copyright © 2011 John Wiley & Sons, Ltd.
Synergistic use of several receptor models (CMB, APCS and PMF) to interpret air quality data
Authors: Andriani E. , Caselli M. , de Gennaro G. , Giove A. , Tortorella C.
Published: May 2011

PM10 samples were collected in Civitavecchia (Rome, Italy) during a monitoring campaign performed between August and September 2008; elemental, ionic and organic characterisation of the samples was carried out. Three receptor models (Chemical Mass Balance, Absolute Principal Component Scores and Positive Matrix Factorisation) were applied to identify PM10 sources and their contributions. The results obtained by the models were compared in order to perform a robust characterisation of the sources.

Seven emission sources were considered relevant for the area under investigation and their profiles were used to run CMB. Source percentage contributions to the total particulate matter samples were evaluated: the greater contribution was obtained for Traffic (39%), the lower for Marine Aerosol (3%).

Five factors were selected to perform the multivariate receptor models (APCS and PMF) after the application of explorative Principal Component Analysis to the dataset. Furthermore, attention was focused on the characterisation of source profiles and contributions obtained by PMF because it best reconstructed the PM mass of the samples.

The percentage contributions of the five sources to the total PM samples were estimated: the greater contribution was obtained for resuspended matter (22%), the lower for combustions (17%).

The results of the source apportionment studies can be used by air quality managers to develop appropriate control strategy. However, the differences in sources profiles and weights obtained by the models were related to their specific approaches: further investigations are suggested in order to develop sources profiles more reliable for the area under investigation. Copyright © 2011 John Wiley & Sons, Ltd.
Near‐surface temperatures and heat balance of bare outcrops exposed to solar radiation
Authors: Gunzburger Yann , Merrien‐Soukatchoff Véronique
Published: May 2011

Subsurface temperatures in rocks naturally fluctuate under the influence of local meteorological conditions. These fluctuations play a role in mechanical weathering, thus creating the environmental conditions conducive to natural hazards such as rockfalls and providing important sediment source terms for landscape evolution. However, the physics that control heat penetration into rocks are not fully understood, which makes the underground thermal state difficult to interpret when temperature measurements are available and even more difficult to estimate for unmonitored sites. This is an important lacuna given possible impacts of future climate change on mechanical weathering processes.

The natural daily variations of subsurface temperatures were investigated on a bare gneiss outcrop exposed to solar radiation, where temperatures at various depths (up to 50 cm), as well as the solar radiation reaching a pyranometer, were monitored hourly for several months. This detailed times series of thermal data was used to gain insight into the heat balance at the inclined free surface of the rock mass.

Attention was focused on two major contributors to the heat balance; the heat flux entering the rock mass through conduction and the incoming shortwave (solar) radiation. A Fourier decomposition of the temperature measurements provided an estimate of the in situ thermal conductivity of the rock and was used to calculate the conductive term. The shortwave radiation term was determined on the basis of the pyranometer measurements adjusted to account for the angle of incidence of the sun.

It is shown that, throughout clear‐sky periods, heat exchanges at the surface are mainly controlled by direct solar radiation during the day, and by a roughly constant outgoing heat flux during the night. Subsurface temperatures can be reliably estimated with a semi‐infinite medium model whose boundary condition is derived from an analytical insolation model that takes atmospheric attenuation into account. Copyright © 2011 John Wiley & Sons, Ltd.
1D‐Modelling and Experimental Study of the PEFC Dynamic Behaviour at Load Increase
Authors: Zaglio M. , Wokaun A. , Mantzaras J. , Büchi F. N.
Published: May 2011

The complex dynamic response of a 1‐dimensional polymer electrolyte fuel cell to load changes is numerically and experimentally investigated, in order to understand the transient transport processes in the different domains of the cell through the membrane‐electrode assembly. The analysis focuses on the comparison of cell response to step load changes, at different levels of reactants humidification. To render the model capable of capturing the cell behaviour at different operating conditions, a multiparameter optimisation procedure is performed to determine the most sensitive transport parameters. The optimisation procedure converges towards a well‐defined solution and the resulting parameters are compared to those available in the literature. Model results indicate that the time required to reach the new steady‐state after a load increase is controlled by the water transport in the membrane. The influence of the water diffusion coefficient at the different operating conditions is further investigated numerically.
Person‐centred care and job satisfaction of caregivers in nursing homes: a systematic review of the impact of different forms of person‐centred care on various dimensions of job satisfaction
Authors: van den Pol‐Grevelink A. , Jukema J.S. , Smits C.H.M.
Published: May 2011

Objective

The positive effects of person‐centred care on older clients have been demonstrated. However, relatively little is known about the effect that giving person‐centred care has on caregivers. This literature review examines the job satisfaction of caregivers who deliver person‐centred care in nursing homes.

Design

The research questions are: Do the various forms of person‐centred care affect job satisfaction differently? Which particular dimensions of job satisfaction have been evaluated in studies on person‐centred care, and does their sensitivity to person‐centred care differ? Using the search engines Pubmed, Cinahl, Psychinfo and Embase up to August 2010, 46 efficacy studies were found, seven of which satisfied our criteria.

Results

Emotion‐oriented care, snoezelen, and small‐scale care most often show positive effects on job satisfaction. Person‐centred care has been shown to have positive effects on general job satisfaction, job demands at psychogeriatric wards, emotional exhaustion and personal accomplishment.

Conclusions

Taking into account the fair‐to‐moderate quality of the studies included, it is concluded that there are limited indications that person‐centred care has a positive effect on a number of dimensions of caregivers' job satisfaction. Further study is required to expand and to support these tentative conclusions. Copyright © 2011 John Wiley & Sons, Ltd.
Humanized tumor mice—A new model to study and manipulate the immune response in advanced cancer therapy
Authors: Wege Anja K. , Ernst Wolfgang , Eckl Judith , Frankenberger Bernhard , Vollmann‐Zwerenz Arabel , Männel Daniela N. , Ortmann Olaf , Kroemer Alexander , Brockhoff Gero
Published: May 2011

The immunological impact on antibody‐based anticancer therapies remains incompletely understood due to the lack of appropriate animal models for in vivo analysis. Here, we present a novel humanized tumor mouse (HTM) model, generated by concurrent transplantation of human hematopoietic stem cells (HSCs) and human breast cancer cells in neonatal NOD‐scid IL2Rγnull mice. Five weeks after intrahepatic transplantation, a functional human immune system was developed in all organs, and, in addition, tumor cells were detectable in lung and bone marrow (early dissemination). After 3 months posttransplant, tumor‐cell effusions and macroscopic tumors associated with liver or spleen were found. Furthermore, disseminated cells in different lymphoid and nonlymphoid organs were measurable. Tumor growth was accompanied by specific T‐cell maturation and tumor cell‐specific T‐cell activation. In addition, Natural–Killer cell accumulation and activation were observed in HTM, which was further enhanced upon IL‐15 treatment facilitating the possibility of immune cell modulation in, e.g., antibody‐dependent cellular cytotoxicity‐based immunotherapeutic approaches. This novel mouse model makes it possible to combine transfer of MHC mismatched tumor cells together with human HSCs resulting in a solid coexistence and interaction without evidence for rejection. Overall, humanized tumor mice represent a powerful in vivo model that for the first time permits the investigation of human immune system‐related target cancer therapy and resistance.
Ultrastable Host–Guest Complexes and Their Applications
Authors: Ko Young Ho , Hwang Ilha , Lee Don‐Wook , Kim Kimoon
Published: May 2011

This review describes monovalent synthetic receptor–ligand (or host–guest) pairs with extremely high binding affinity, comparable to that of the biotin–avidin pair, and their applications. Cucurbit[7]uril (CB[7]), a member of the host family cucurbit[n]uril (CB[n], n=5–8, 10), forms ultrastable host–guest complexes with ferrocene‐, adamantane‐ or bicyclo[2.2.2]octane‐based molecules having ammonium groups properly positioned to interact with the carbonyl oxygens at the portals of CB[7]. The extremely high affinity is achieved by a large enthalpic gain arising from the near perfect size/shape complementarity between the rigid CB cavity and the rigid core of the guest molecules, with the critical assistance of the positive entropy change due to the extensive dehydration of the host and guest. The high stability of the complexes allowed us and others to explore several biological applications such as immobilization of biomolecules on a solid surface, protein isolation, triggering intracellular events, and regulating enzymatic activities. These complexes with their exceptional affinity, chemical robustness, simple preparation, biocompatibility, and easy handling may replace the biotin–(strept)avidin system in diverse areas of research, including affinity chromatography, high throughput biochemical assays, imaging, and sensor technologies.
Deep Inside Cucurbiturils: Physical Properties and Volumes of their Inner Cavity Determine the Hydrophobic Driving Force for Host–Guest Complexation
Authors: Nau Werner M. , Florea Mara , Assaf Khaleel I.
Published: May 2011

Cucurbit[n]urils (CBn) bind guest molecules through a combination of electrostatic interactions with the carbonyl rims and hydrophobic interactions with the inner cavity. Investigations with solvatochromic probes in CB7 reveal that the polarity of the cavity resembles that of alcohols (e.g., n‐octanol), while its polarizability (P=0.12) and apparent refractive index (nD=1.10±0.12) are extremely low, close to the gas phase. The calculated molecular quadrupole moments of CBs are extremely large (Θzz=−120 to −340 Buckingham). A survey of reported binding constants of neutral guests and hydrophobic residues that form 1 : 1 inclusion complexes with CB6, reveals a preferential inclusion of C3–C5 residues in its cavity. The largest guests which show non‐negligible binding contain 7 heavy atoms (excluding hydrogen). For CB7, the strongest binding is observed for guests with adamantyl (10 heavy atoms) and ferrocenyl groups (11 heavy atoms), while the largest guests known to be complexed are carborane and the adduct of two pyridine derivatives (12 heavy atoms). The evaluation of different volumes shows that the most meaningful cavity, namely that responsible for binding of hydrophobic residues, is confined by the planes through the oxygen carbonyls. The volume of this inner cavity follows the formula V/Å3=68+62(n−5)+12.5(n−5)2, affording representative cavity volumes of 68 Å3 for CB5, 142 Å3 for CB6, 242 Å3 for CB7, and 367 Å3 for CB8. The volume of the 2 bond dipole regions is comparably smaller, amounting, for example, to 2×35 Å3 for CB6. The analysis of packing coefficients for representative sets of known guests with clearly defined hydrophobic binding motifs reveals average values of 47 % for CB5, 58 % for CB6, 52 % for CB7, and 53 % for CB8, which are well in line with the preferred packing (“55 % solution”, see S. Mecozzi, J. Rebek, Chem. Eur. J. 1998, 4, 1016–1022) in related supramolecular host–guest assemblies. The driving force for binding of hydrophobic guests and residues by CBs is interpreted in terms of the unimportance of dispersion interactions (owing to the low polarizability of their cavity) and the dominance of classical and nonclassical hydrophobic effects related to the removal of very‐high‐energy water molecules (2 for CB5, 4 for CB6, 8 for CB7, and 12 for CB8) from the cavity.
Improved adhesion of human cultured periosteal sheets to a porous poly(L‐lactic acid) membrane scaffold without the aid of exogenous adhesion biomolecules
Authors: Kawase Tomoyuki , Tanaka Takaaki , Nishimoto Takayuki , Okuda Kazuhiro , Nagata Masaki , Burns Douglas M. , Yoshie Hiromasa
Published: May 2011

Human cultured periosteal sheets, which are developed from small excised periosteum tissue segments (PTSs) in culture dishes by simple expansion culture, have been applied as a promising autologous osteogenic grafting material for periodontal regenerative therapy. However, the weak initial adhesion of PTSs to dish surfaces often hampers cellular outgrowth and limits the number of preparations. To correct this weakness and still avoid the use of animal‐derived adhesion biomolecules, we have developed a novel, biodegradable, porous poly(L‐lactic acid) (pPLLA) membrane. Freshly excised PTSs bound well to the highly porous pPLLA membrane, possibly due to the presence of semihemispheric 20–30 μm diameter openings on the upper surface. Global gene expression analysis demonstrated that periosteal sheets cultured on pPLLA membranes upregulated expression of many adhesion molecules. Osteogenic induction stimulated the production of proteoglycans by these cells and concomitantly enhanced their expansion and penetration into the deep pore regions of the membrane in parallel with the progression of in vitro mineralization. These findings suggest that our pPLLA membranes not only facilitate initial adhesion, primarily mediated by adsorbed proteins, but also enhance biological adhesion by inducing endogenous adhesion molecules in periosteal sheet cultures. Therefore, the efficacy of periosteal sheets in therapy should be greatly enhanced by using this new pPLLA membrane. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Preparation and characterization of antibacterial P2O5–CaO–Na2O–Ag2O glasses
Authors: Ahmed A. A. , Ali A. A. , Mahmoud Doaa A. R. , El‐Fiqi A. M.
Published: May 2011

60P2O5–20CaO–(20 – x) Na2O–xAg2O and 60P2O5–30CaO–(10 – x) Na2O–xAg2O glasses, x = 0, 0.5,1, and 2 mol % were prepared using normal glass melting technique. The antibacterial activity of pressed disks of powdered glass (undoped and silver‐doped glass) was investigated against S.aureus, P.aeruginosa, and E.coli micro‐organisms using agar disk‐diffusion assays at 37°C for 24 h. The antibacterial activity was deduced from the inhibition zone diameter (IZD), zone of no bacterial growth, measured under the stated experimental conditions. The antibacterial activity increases with the increase in IZD and vice versa. Dissolution of glass in water at 37°C, pH changes of water during glass dissolution, and concentrations of silver ions released from silver‐doped glasses into water during their dissolution were determined. An increase in the concentration of silver ions released from silver‐doped glasses into water was observed with increasing time of glass dissolution and with increasing Ag2O content. The tested silver‐free and silver‐doped glasses demonstrated different antibacterial activity against the tested micro‐organisms. For silver‐free glasses, an increase in IZD was observed with the increase in the glass dissolution rate and with the decrease in pH of water. Also, the IZD showed an increase with increasing Ag2O content of silver‐doped glasses. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Circulating osteogenic cells: Implications for injury, repair, and regeneration
Authors: Pignolo Robert J , Kassem Moustapha
Published: May 2011

The aim of this review is to provide a critical reading of recent literature pertaining to the presence of circulating, fluid-phase osteoblastic cells and their possible contribution to bone formation. We have termed this group of cells collectively as circulating osteogenic precursor (COP) cells. We present evidence for their existence, methods used for their isolation and identification, possible physiological and pathophysiological roles, cellular origins, and possible mechanisms for their migration to target tissues. © 2011 American Society for Bone and Mineral Research
Caspase‐2 deficiency protects mice from diabetes‐induced marrow adiposity
Authors: Coe Lindsay M. , Lippner Dennean , Perez Gloria I. , McCabe Laura R.
Published: May 2011

Type I (T1) diabetes is an autoimmune and metabolic disease associated with bone loss. Bone formation and density are decreased in T1‐diabetic mice. Correspondingly, the number of TUNEL positive, dying osteoblasts increases in bones of T1‐diabetic mice. Moreover, two known mediators of osteoblast death, TNFα and ROS, are increased in T1‐diabetic bone. TNFα and oxidative stress are known to activate caspase‐2, a factor involved in the extrinsic apoptotic pathway. Therefore, we investigated the requirement of caspase‐2 for diabetes‐induced osteoblast death and bone loss. Diabetes was induced in 16‐week old C57BL/6 caspase‐2 deficient mice and their wild type littermates and markers of osteoblast death, bone formation and resorption, and marrow adiposity were examined. Despite its involvement in extrinsic cell death, deficiency of caspase‐2 did not prevent or reduce diabetes‐induced osteoblast death as evidenced by a twofold increase in TUNEL positive osteoblasts in both mouse genotypes. Similarly, deficiency of caspase‐2 did not prevent T1‐diabetes induced bone loss in trabecular bone (BV/TV decreased by 30 and 50%, respectively) and cortical bone (decreased cortical thickness and area with increased marrow area). Interestingly, at this age, differences in bone parameters were not seen between genotypes. However, caspase‐2 deficiency attenuated diabetes‐induced bone marrow adiposity and adipocyte gene expression. Taken together, our data suggest that caspase‐2 deficiency may play a role in promoting marrow adiposity under stress or disease conditions, but it is not required for T1‐diabetes induced bone loss. J. Cell. Biochem. 112: 2403–2411, 2011. © 2011 Wiley‐Liss, Inc.
Apoptotic osteocytes regulate osteoclast precursor recruitment and differentiation in vitro
Authors: Al‐Dujaili Saja A. , Lau Esther , Al‐Dujaili Hashem , Tsang Kyle , Guenther Axel , You Lidan
Published: May 2011

Fatigue loading causes a spatial distribution of osteocyte apoptosis co‐localized with bone resorption spaces peaking around microdamage sites. Since osteocytes have been shown to regulate osteoclast formation and activity, we hypothesize that osteocyte apoptosis regulates osteoclastogenesis. In this study, we used serum‐starvation to mimic reduced nutrient transport in microdamaged bone and induce apoptosis in MLO‐Y4 osteocyte‐like cells; conditioned medium was used to apply soluble factors released by apoptotic osteocytes (aOCY) to healthy non‐apoptotic MLO‐Y4 cells. Osteoclast precursor (RAW264.7 monocyte) migration and differentiation were assessed in the presence of conditioned media (CM) from: (A) aOCY, (B) osteocytes treated with apoptosis conditioned medium (i.e., healthy osteocytes in the presence of apoptosis cues; apoptosis CM‐treated osteocytes (atOCY)), and (C) osteocytes treated with non‐apoptosis conditioned medium (i.e., healthy osteocytes in the absence of apoptosis cues; non‐apoptosis CM‐treated osteocytes (natOCY)). Receptor activator for nuclear factor‐κB ligand (RANKL), macrophage colony stimulating factor (M‐CSF), vascular endothelial growth factor (VEGF) and osteoprotegerin (OPG) mRNA, and protein expression were measured. Our findings indicate that soluble factors released by aOCY and atOCY promoted osteoclast precursor migration (up to 64% and 24% increase, respectively) and osteoclast formation (up to 450% and 265% increase, respectively). Osteoclast size increased up to 233% in the presence of aOCY and atOCY CM. Recruitment, formation and size were unaltered by natOCY. RANKL mRNA and protein expression were upregulated only in aOCY, while M‐CSF and VEGF increased in atOCY. Addition of RANKL‐blocking antibody abolished aOCY‐induced osteoclast precursor migration and osteoclast formation. VEGF and M‐CSF blocking antibodies abolished atOCY‐induced osteoclastogenesis. These findings suggest that aOCY directly and indirectly (through atOCY) initiate targeted bone resorption by regulating osteoclast precursor recruitment and differentiation. J. Cell. Biochem. 112: 2412–2423, 2011. © 2011 Wiley‐Liss, Inc.