bluuebunny/crossref_metadata_2025 huggingface dataset:
Inducible Cyclooxygenase Released Prostaglandin E2 Modulates the Severity of Infection Caused by Streptococcus
pyogenes
Authors: Goldmann Oliver , Hertzén Erika , Hecht Alexander , Schmidt Heike , Lehne Sabine , Norrby-Teglund Anna , Medina Eva
Published: July 2010

Streptococcus pyogenes is a significant human pathogen that can cause life-threatening invasive infections. Understanding the mechanism of disease is crucial to the development of more effective therapies. In this report, we explored the role of PGE2, an arachidonic acid metabolite, and its rate-limiting enzyme cyclooxygenase 2 (COX-2) in the pathogenesis of severe S. pyogenes infections. We found that the COX-2 expression levels in tissue biopsies from S. pyogenes-infected patients, as well as in tissue of experimentally infected mice, strongly correlated with the severity of infection. This harmful effect was attributed to PGE2-mediated suppression of the bactericidial activity of macrophages through interaction with the G2-coupled E prostanoid receptor. The suppressive effect of PGE2 was associated with enhanced intracellular cAMP production and was mimicked by the cAMP-elevating agent, forskolin. Activation of protein kinase A (PKA) was the downstream effector mechanisms of cAMP because treatment with PKI14–22, a highly specific inhibitor of PKA, prevented the PGE2-mediated inhibition of S. pyogenes killing in macrophages. The inhibitory effect exerted by PKA in the generation of antimicrobial oxygen radical species seems to be the ultimate effector mechanism responsible for the PGE2-mediated downregulation of the macrophage bactericidal activity. Importantly, either genetic ablation of COX-2, pharmacological inhibition of COX-2 or treatment with the G2-coupled E prostanoid antagonist, AH6809, significantly improved the disease outcome in S. pyogenes infected mice. Therefore, the results of this study open up new perspectives on potential molecular pathways that are prone to pharmacological manipulation during severe streptococcal infections.
Characterization of Cytokine-Induced Myeloid-Derived Suppressor Cells from Normal Human Peripheral Blood Mononuclear Cells
Authors: Lechner Melissa G. , Liebertz Daniel J. , Epstein Alan L.
Published: July 2010

Tumor immune tolerance can derive from the recruitment of suppressor cell populations, including myeloid-derived suppressor cells (MDSCs). In cancer patients, increased MDSCs correlate with more aggressive disease and a poor prognosis. Expression of 15 immune factors (TGFβ, IL-1β, IL-4, IL-6, IL-10, GM-CSF, M-CSF, IDO, fms-related tyrosine kinase 3 ligand, c-kit ligand, inducible NO synthase, arginase-1, TNF-α, cyclo-oxygenase 2, vascular endothelial growth factor [VEGF]) by MDSC-inducing human solid tumor cell lines was evaluated by RT-PCR. Based upon these data, cytokine mixtures were then tested for their ability to generate suppressive CD33+ cells from healthy donor PBMCs in vitro by measuring their ability to inhibit the proliferation of, and IFN-γ production by, fresh autologous human T cells after CD3/CD28 stimulation. Induced MDSCs were characterized with respect to their morphology, surface phenotype, and gene expression profile. MDSC-inducing cancer cell lines demonstrated multiple pathways for MDSC generation, including overexpression of IL-6, IL-1β, cyclo-oxygenase 2, M-CSF, and IDO. CD33+ cells with potent suppressive capacity were best generated in vitro by GM-CSF and IL-6, and secondarily by GM-CSF + IL-1β, PGE2, TNF-α, or VEGF. Characterization studies of cytokine-induced suppressive cells revealed CD33+CD11b+CD66b+HLA-DRlowIL-13Rα2int large mononuclear cells with abundant basophilic cytoplasm. Expression of inducible NO synthase, TGFβ, NADPH oxidase, VEGF, and/or arginase-1 was also upregulated, and Transwell studies showed suppression of autologous T cells to be contact dependent. Suppressive CD33+ cells generated from PBMCs by GM-CSF and IL-6 were consistent with human MDSCs. This study suggests that these cytokines are potential therapeutic targets for the inhibition of MDSC induction in cancer patients.
Cutting Edge: Merocytic Dendritic Cells Break T Cell Tolerance to β Cell Antigens in Nonobese Diabetic Mouse Diabetes
Authors: Katz Jonathan D. , Ondr Jennifer K. , Opoka Robert J. , Garcia Zacharias , Janssen Edith M.
Published: July 2010

In type 1 diabetes, the breach of central and peripheral tolerance results in autoreactive T cells that destroy insulin-producing, pancreatic β cells. In this study, we identify a critical subpopulation of dendritic cells responsible for mediating both the cross-presentation of islet Ags to CD8+ T cells and the direct presentation of β cell Ags to CD4+ T cells. These cells, termed merocytic dendritic cells (mcDCs), are more numerous in the NOD mouse and, when Ag-loaded, rescue CD8+ T cells from peripheral anergy and deletion while stimulating islet-reactive CD4+ T cells. When purified from the pancreatic lymph nodes of overtly diabetic NOD mice, mcDCs break peripheral T cell tolerance to β cells in vivo and induce rapid onset type 1 diabetes in the young NOD mouse. Thus, the mcDC subset appears to represent the long-sought APC responsible for breaking peripheral tolerance to β cell Ags in vivo.
The IFN-γ–Dependent Suppressor of Cytokine Signaling 1 Promoter Activity Is Positively Regulated by IFN Regulatory Factor-1 and Sp1 but Repressed by Growth Factor Independence-1b and Krüppel-Like Factor-4, and It Is Dysregulated in Psoriatic Keratinocytes
Authors: Madonna Stefania , Scarponi Claudia , Sestito Rosanna , Pallotta Sabatino , Cavani Andrea , Albanesi Cristina
Published: July 2010

Epidermal keratinocytes can counteract the detrimental effects of IFN-γ by inducing the expression of suppressor of cytokine signaling (SOCS)1, which plays an important anti-inflammatory and self-protective role. To date, limited information exists on its expression and regulation in human diseased keratinocytes. In this study, we compared the expression levels of SOCS1 in keratinocytes isolated from skin affected by psoriasis with cells obtained from healthy donors, unveiling that keratinocytes are more prone than healthy cells to upregulate SOCS1 mRNA expression in response to IFN-γ. We explored the regulatory mechanisms involved in socs1 gene transcription, and found that Sp1 and IFN regulatory factor-1 transcription factors are, respectively, responsible for the basal and IFN-γ–induced activity of human socs1 promoter. In parallel, we demonstrated that socs1 promoter is negatively regulated by two transcriptional repressors, namely, growth factor independence-1b and Krüppel-like factor 4, which tightly control SOCS1 transcription on IFN-γ stimulation. Interestingly, although the expression of Sp1 and IFN regulatory factor-1 activators of socs1 promoter is unaltered, growth factor independence-1b and Krüppel-like factor 4 are significantly reduced in psoriatic compared with healthy keratinocytes. This reduction and the consequent unbalanced binding of transcriptional activators and repressors to socs1 promoter after IFN-γ stimulation might be responsible for the enhanced expression of SOCS1 in psoriatic cells. We suggest that SOCS1 exaggerated upregulation in psoriatic keratinocytes could represent a mechanism through which these cells attempt to protect themselves from IFN-γ effects. However, the SOCS1 increased levels in psoriatic keratinocytes are not sufficient to completely inhibit the expression of proinflammatory genes.
Neuronal Models for Studying Tau Pathology
Authors: Koechling Thorsten , Lim Filip , Hernandez Felix , Avila Jesus
Published: July 2010

Alzheimer's disease (AD) is the most frequent neurodegenerative disorder leading to dementia in the aged human population. It is characterized by the presence of two main pathological hallmarks in the brain: senile plaques containing -amyloid peptide and neurofibrillary tangles (NFTs), consisting of fibrillar polymers of abnormally phosphorylated tau protein. Both of these histological characteristics of the disease have been simulated in genetically modified animals, which today include numerous mouse, fish, worm, and fly models of AD. The objective of this review is to present some of the main animal models that exist for reproducing symptoms of the disorder and their advantages and shortcomings as suitable models of the pathological processes. Moreover, we will discuss the results and conclusions which have been drawn from the use of these models so far and their contribution to the development of therapeutic applications for AD.
Current Versus Ultimate Life Expectancies: Perceptions and Implications
Authors: Suyderhoud Jack P. , Pollock Richard L.
Published: July 2010

No abstract available.
Lucrum Cessans, Damnum Emergens and the Market Place
Authors: Jorge Antonio , Salazar-Carrillo Jorge
Published: July 2010

No abstract available.
Estimating Personal Expenditure Deductions in Multi-Income Families in Cases of Wrongful Death
Authors: Harju Melvin W. , Adams Clarence H.
Published: July 2010

No abstract available.
A 1990 Survey Study of Forensic Economists
Authors: Brookshire Michael , Slesnick Frank
Published: July 2010

No abstract available.
Job Search and College Enrollment Durations for Calculating Economic Losses from Personal Injuries
Authors: Burns Malcolm R. , Faurot David J.
Published: July 2010

No abstract available.
Female Work Experience: Voluntary Versus Involuntary Labor Force Activity
Authors: Corcione Frank P. , Thornton Robert J.
Published: July 2010

No abstract available.
The Role of the Husband/Father in Household Output
Authors: Paul Harvey
Published: July 2010

No abstract available.
Inflation in the Computation of the Present Value of Lost Earnings1
Authors: PonArul Richard
Published: July 2010

No abstract available.
The Economic Expert in Wrongful Death/Personal Injury Cases: Workable Competition or Monopoly Power?
Authors: Fox Pauline
Published: July 2010

No abstract available.
The Expert Witness: Knowledge and Communication (The Deadly or Dynamic Duo)
Authors: Stufflebean Debra Guiou
Published: July 2010

No abstract available.
More on Alternative Measures of Earnings Growth
Authors: Bell Edward B. , Taub Allan J.
Published: July 2010

No abstract available.
Literature Relevant to the Valuation of Household Services
Authors: Hicks Whitney W. , Ireland Thomas R. , Johnson Walter D. , Metzen Edward J. , Ward John O.
Published: July 2010

No abstract available.
The Effect of Taxes and Inflation on the Real Interest Rate
Authors: Schwartz Eli , Thornton Robert
Published: July 2010

No abstract available.
Evaluating Lost Vacation Benefits: A Note on the Opportunity Cost Approach
Authors: Dulaney Ronald A.
Published: July 2010

No abstract available.
An Employer's Loss of Employee's Profit Capacity: A Membership Surplus Approach
Authors: Hajiran Homayoun
Published: July 2010

No abstract available.
Accounting for Taxes in the Determination of the Reduction for Personal Consumption
Authors: Jennings William , Mercurio Penelope
Published: July 2010

No abstract available.
The Determination of Court-Awarded Legal Fees
Authors: McInish Thomas H.
Published: July 2010

No abstract available.
On the Relative Stability and Predictability of the Interest Rate and Earnings Growth Rate
Authors: Lewis W. Cris
Published: July 2010

No abstract available.
Selecting the Time Period Over Which the Net Discount Rate is Determined for Economic Loss Analysis
Authors: Haydon Randall B. , Webb Samuel C.
Published: July 2010

No abstract available.
Loss of Future Income in the Case of Personal Injury of a Child: Parental Influence on a Child's Future Earnings
Authors: Spizman Lawrence M. , Kane John
Published: July 2010

No abstract available.
Economic Value of Restricted Fringe Benefits: A Comment
Authors: Romans J. Thomas , Floss Frederick G.
Published: July 2010

No abstract available.
Economic Value of Restricted Fringe Benefits: A Reply
Authors: Rosenman Robert
Published: July 2010

No abstract available.
Discount Rates for Lost Profits
Authors: Bodington Jeffrey C.
Published: July 2010

No abstract available.
Loss of Enjoyment, Rehabilitation and Hedonic Damages: A Comment
Authors: Metcalf Robert
Published: July 2010

No abstract available.
Four Guidelines for Selecting a Discount Rate
Authors: Romans J. Thomas , Floss Frederick G.
Published: July 2010

No abstract available.
Estimated impact of black carbon deposition during pre-monsoon season from Nepal Climate Observatory – Pyramid data and snow albedo changes over Himalayan glaciers
Authors: Yasunari T. J. , Bonasoni P. , Laj P. , Fujita K. , Vuillermoz E. , Marinoni A. , Cristofanelli P. , Duchi R. , Tartari G. , Lau K.-M.
Published: July 2010

Abstract. The possible minimal range of reduction in snow surface albedo due to dry deposition of black carbon (BC) in the pre-monsoon period (March–May) was estimated as a lower bound together with the estimation of its accuracy, based on atmospheric observations at the Nepal Climate Observatory – Pyramid (NCO-P) sited at 5079 m a.s.l. in the Himalayan region. A total BC deposition rate was estimated as 2.89 μg m−2 day−1 providing a total deposition of 266 μg m−2 for March–May at the site, based on a calculation with a minimal deposition velocity of 1.0×10−4 m s−1 with atmospheric data of equivalent BC concentration. Main BC size at NCO-P site was determined as 103.1–669.8 nm by correlation analyses between equivalent BC concentration and particulate size distributions in the atmosphere. The BC deposition from the size distribution data was also estimated. It was found that 8.7% of the estimated dry deposition corresponds to the estimated BC deposition from equivalent BC concentration data. If all the BC is deposited uniformly on the top 2-cm pure snow, the corresponding BC concentration is 26.0–68.2 μg kg−1, assuming snow density variations of 195–512 kg m−3 of Yala Glacier close to NCO-P site. Such a concentration of BC in snow could result in 2.0–5.2% albedo reductions. By assuming these albedo reductions continue throughout the year, and then applying simple numerical experiments with a glacier mass balance model, we estimated reductions would lead to runoff increases of 70–204 mm of water. This runoff is the equivalent of 11.6–33.9% of the annual discharge of a typical Tibetan glacier. Our estimates of BC concentration in snow surface for pre-monsoon season is comparable to those at similar altitudes in the Himalayan region, where glaciers and perpetual snow regions begin, in the vicinity of NCO-P. Our estimates from only BC are likely to represent a lower bound for snow albedo reductions, because we used a fixed slower deposition velocity. In addition, we excluded the effects of atmospheric wind and turbulence, snow aging, dust deposition, and snow albedo feedbacks. This preliminary study represents the first investigation of BC deposition and related albedo on snow, using atmospheric aerosol data observed at the southern slope in the Himalayas.
Total column CO2 measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles
Authors: Deutscher N. M. , Griffith D. W. T. , Bryant G. W. , Wennberg P. O. , Toon G. C. , Washenfelder R. A. , Keppel-Aleks G. , Wunch D. , Yavin Y. , Allen N. T. , Blavier J.-F. , Jiménez R. , Daube B. C. , Bright A. V. , Matross D. M. , Wofsy S. C. , Park S.
Published: July 2010

Abstract. An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO2 and O2 and other gases. Measured CO2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January–February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clear-sky low airmass relative precision of 0.1% is demonstrated in the CO2 and O2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS XCO2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.
Comment on ''Effects of long-term high CO2 exposure on two species of coccolithophore'' by Müller et al. (2010)
Authors: Collins S.
Published: July 2010

Abstract. Populations can respond to environmental change over tens or hundreds of generations by shifts in phenotype that can be the result of a sustained physiological response, evolutionary (genetic) change, shifts in community composition, or some combination of these factors. Microbes evolve on human timescales, and evolution may contribute to marine phytoplankton responses to global change over the coming decades. However, it is still unknown whether evolutionary responses are likely to contribute significantly to phenotypic change in marine microbial communities under high pCO2 regimes or other aspects of global change. Recent work by Müller et al. (2010) highlights that long-term responses of marine microbes to global change must be empirically measured and the underlying cause of changes in phenotype explained. Here, I briefly discuss how tools from experimental microbial evolution may be used to detect and measure evolutionary responses in marine phytoplankton grown in high CO2 environments and other environments of interest. I outline why the particular biology of marine microbes makes conventional experimental evolution challenging right now and make a case that marine microbes are good candidates for the development of new model systems in experimental evolution. I suggest that "black box" frameworks that focus on partitioning phenotypic change, such as the Price equation, may be useful in cases where direct measurements of evolutionary responses alone are difficult, and that such approaches could be used to test hypotheses about the underlying causes of phenotypic shifts in marine microbe communities responding to global change.
Impact of climate and land use/cover changes on the carbon cycle in China (1981–2000): a system-based assessment
Authors: Gao Z. , Gao W. , Chang N.-B.
Published: July 2010

Abstract. In China, cumulative changes in climate and land use/land cover (LULC) from 1981 to 2000 had collectively affected the net productivity in the terrestrial ecosystem and thus the net carbon flux, both of which are intimately linked with the global carbon cycle. This paper represents the first national effort of its kind to systematically investigate the impact of changes of LULC on carbon cycle with high-resolution dynamic LULC data at the decadal scale (1990s and 2000s). The CEVSA was applied and driven by high resolution LULC data retrieved from remote sensing and climate data collected from two ground-based meteorological stations. In particular, it allowed us to simulate carbon fluxes (net primary productivity (NPP), vegetation carbon (VEGC) storage, soil carbon (SOC) storage, heterotrophic respiration (HR), and net ecosystem productivity (NEP)) and carbon storage from 1981 to 2000. Simulations generally agree with output from other models and results from bookkeeping approach. Based on these simulations, temporal and spatial variations in carbon storage and fluxes in China may be confirmed and we are able to relate these variations to climate variability during this period for detailed analyses to show influences of the LULC and environmental controls on NPP, NEP, HR, SOC, and VEGC. Overall, the increases in NPP were greater than HR in most of the time due to the effect of global warming with more precipitation in China from 1981 to 2000. With this trend, the NEP remained positive during that period, resulting in the net increase of total amount of carbon being stored by about 0.296 Pg C within the 20-years time frame. Because the climate effect was much greater than that of changes of LULC, the total carbon storage in China actually increased by about 0.17 Pg C within the 20 years. Such findings will contribute to the generation of control policies of carbon emissions under global climate change.
Influence of seasonal monsoons on net primary production and CO2 in subtropical Hong Kong coastal waters
Authors: Yuan X. C. , Yin K. D. , Cai W.-J. , Ho A. Y. T. , Xu J. , Harrison P. J.
Published: July 2010

Abstract. Data from seven cruises in three different environments including the Pearl River estuary, sewage discharge outfall and eastern coastal/shelf waters, were used to examine the seasonal variations in net primary production (NPP) and the biologically active gases O2 and CO2. In the winter dry season, when monsoon-induced downwelling was dominant, NPP was low (−60±50 mmol C m−2 d−1) in all three regions. The negative NPP corresponded to low O2 influxes (−100±50 mmol O2 m−2 d−1) and CO2 effluxes (24±10 mmol C m−2 d−1). In the summer wet season, when upwelling brought the bottom oceanic waters to the nearshore due to the southwest monsoonal wind, there was a 2 to 15-fold increase in integrated primary production (IPP) compared to winter. The increase in IPP was likely due to the favorable conditions such as stratification and the nutrient inputs from upwelled waters and the Pearl River estuary. NPP reached up to 240±100 mmol C m−2 d−1 in the wet season. However, accompanying the high positive NPP, we observed an influx of O2 (−100±60 mmol O2 m−2 d−1) and efflux of CO2 (25±15 mmol C m−2 d−1). The high positive NPP corresponding to a CO2 source and O2 sink could be explained by the influence of the southwest monsoon-induced upwelling, as the upwelling brought cold, low DO (160±30 μM) and high DIC (1960±100 μatm) water to the surface in the wet season. Hence, the subtropical Hong Kong coastal waters are generally a CO2 source due to the monsoonal influence in both the dry and wet seasons.
Assessing microstructures of pyrrhotites in basalts by multifractal analysis
Authors: Xie S. , Cheng Q. , Zhang S. , Huang K.
Published: July 2010

Abstract. Understanding and describing spatial arrangements of mineral particles and determining the mineral distribution structure are important to model the rock-forming process. Geometric properties of individual mineral particles can be estimated from thin sections, and different models have been proposed to quantify the spatial complexity of mineral arrangement. The Gejiu tin-polymetallic ore-forming district, located in Yunnan province, southwestern China, is chosen as the study area. The aim of this paper is to apply fractal and multifractal analysis to quantify distribution patterns of pyrrhotite particles from twenty-eight binary images obtained from seven basalt segments and then to discern the possible petrological formation environments of the basalts based on concentrations of trace elements. The areas and perimeters of pyrrhotite particles were measured for each image. Perimeter-area fractal analysis shows that the perimeter and area of pyrrhotite particles follow a power-law relationship, which implies the scale-invariance of the shapes of the pyrrhotites. Furthermore, the spatial variation of the pyrrhotite particles in space was characterized by multifractal analysis using the method of moments. The results show that the average values of the area-perimeter exponent (DAP), the width of the multifractal spectra (Δ(D(0)−D(2)) and Δ(D(qmin)−D(qmax))) and the multifractality index (τ"(1)) for the pyrrhotite particles reach their minimum in the second basalt segment, which implies that the spatial arrangement of pyrrhotite particles in Segment 2 is less heterogeneous. Geochemical trace element analysis results distinguish the second basalt segment sample from other basalt samples. In this aspect, the fractal and multifractal analysis may provide new insights into the quantitative assessment of mineral microstructures which may be closely associated with the petrogenesis as shown by the bulk-rock geochemical analysis.
Determination of acrylamide in food by gas and liquid chromatography-mass spectrometry
Authors: Vlčáková Miriam , Vieriková Michaela
Published: July 2010

Acrylamide in food was determined by gas chromatography - mass spectrometry (GC-MS) after bromination of acrylamide and underivatized acrylamide was quantified by ultra performance liquid chromatography -mass spectrometry (UPLC-MS). Two different sample preparation methods were used and optimised. The GC-MS method was used for various food matrices like breads, potato crisps, potato crackers, french fries. The UPLC-MS method was used for analysis of coffee. The limit of detection and limit of quantification for acrylamide were 7 µg.kg-1 and 20 µg.kg-1 by GC-MS, 9 µg.kg-1  and 30 µg.kg-1 by UPLC-MS. For both methods the reproducibility, given as relative standard deviation was < 5% , and the recovery was close to 100 %.
Functional renormalization group approach to the BCS‐BEC crossover
Authors: Diehl S. , Floerchinger S. , Gies H. , Pawlowkski J.M. , Wetterich C.
Published: July 2010

The phase transition to superfluidity and the BCS‐BEC crossover for an ultracold gas of fermionic atoms is discussed within a functional renormalization group approach. Non‐perturbative flow equations, based on an exact renormalization group equation, describe the scale dependence of the flowing or average action. They interpolate continuously from the microphysics at atomic or molecular distance scales to the macroscopic physics at much larger length scales, as given by the interparticle distance, the correlation length, or the size of the experimental probe. We discuss the phase diagram as a function of the scattering length and the temperature and compute the gap, the correlation length and the scattering length for molecules. Close to the critical temperature, we find the expected universal behavior. Our approach allows for a description of the few‐body physics (scattering and molecular binding) and the many‐body physics within the same formalism.
Information sources and perceived success in corporate finance
Authors: Huvila Isto
Published: July 2010

The work of corporate finance professionals is information‐intensive, despite the fact that the practices and motivations of their information preferences have been researched very little. The present study investigates perceived success and how it is related to corporate finance professionals' information source use behavior based on a Web survey of 92 Finnish corporate finance professionals. The principal finding of the statistical analysis of the data is that perceptions of work success and specific types of information sources contributing to the success are related. The correlations are complex, and very different types of information sources contribute to individual types of success, and vice versa. The findings indicate that information sources function as measures of success and serve an instrumental purpose. Besides functional relations, the correlation of the variables suggests more comprehensive success and information source use related dependencies and preferences. The findings imply that by studying existing perceptions of success, it is possible to make inferences about preferred information sources. The study also suggests that both personal and organizational perceptions of success should be taken into account when planning information services and information literacy education for corporate finance professionals to increase their effectiveness and relevance for the professionals.
Social network site changes over time: The case of MySpace
Authors: Wilkinson David , Thelwall Mike
Published: July 2010

The uptake of social network sites (SNSs) has been highly trend‐driven, with Friendster, MySpace, and Facebook being successively the most popular. Given that teens are often early adopters of communication technologies, it seems reasonable to assume that the typical user of any particular SNS would change over time, probably becoming older and covering different segments of the population. This article analyzes changes in MySpace self‐reported member demographics and behavior from 2007 to 2010 using four large samples of members and focusing on the United States. The results indicate that despite its take‐up rate declining, with only about 1 in 10 members being active a year after joining, the dominant (modal) age for active U.S. members remains midadolescence, but has shifted by about 2 years from 15 to 17, and the U.S. dominance of MySpace is shrinking. There also has been a dramatic increase in the median number of Friends for new U.S. members, from 12 to 96—probably due to MySpace's automated Friend Finder. Some factors show little change, however, including the female majority, the 5% minority gay membership, and the approximately 50% private profiles. In addition, there has been an increase in the proportion of Latino/Hispanic U.S. members, suggesting a shifting ethnic profile. Overall, MySpace has surprisingly stable membership demographics and is apparently maintaining its primary youth appeal, perhaps because of its music orientation.
A group sequential type design for three‐arm non‐inferiority trials with binary endpoints
Authors: Li Gang , Gao Shan
Published: July 2010

The three‐arm design with a test treatment, an active control and a placebo group is the gold standard design for non‐inferiority trials if it is ethically justifiable to expose patients to placebo. In this paper, we first use the closed testing principle to establish the hierarchical testing procedure for the multiple comparisons involved in the three‐arm design. For the effect preservation test we derive the explicit formula for the optimal allocation ratios. We propose a group sequential type design, which naturally accommodates the hierarchical testing procedure. Under this proposed design, Monte Carlo simulations are conducted to evaluate the performance of the sequential effect preservation test when the variance of the test statistic is estimated based on the restricted maximum likelihood estimators of the response rates under the null hypothesis. When there are uncertainties for the placebo response rate, the proposed design demonstrates better operating characteristics than the fixed sample design.
Peroxynitrite—An ugly biofactor?
Authors: Ascenzi Paolo , di Masi Alessandra , Sciorati Clara , Clementi Emilio
Published: July 2010

Cellular damage occurring under oxidative conditions has been ascribed mainly to the formation of peroxynitrite (ONOOH/ONOO−) that originates from the reaction of NO•with O2•−. The detrimental effects of peroxynitrite are exacerbated by the reaction with CO2that leads to ONOOC(O)O−, which further decays to the strong oxidant radicals NO2•and CO3•−. The reaction with CO2, however, may redirect peroxynitrite specificity. An excessive formation of peroxynitrite represents an important mechanism contributing to the DNA damage, the inactivation of metabolic enzymes, ionic pumps, and structural proteins, and the disruption of cell membranes. Because of its ability to oxidize biomolecules, peroxynitrite is implicated in an increasing list of diseases, including neurodegenerative and cardiovascular disorders, inflammation, pain, autoimmunity, cancer, and aging. However, peroxynitrite displays also protective activities: (i) at high concentrations, it shows anti‐viral, anti‐microbial, and anti‐parasitic actions; and (ii) at low concentrations, it stimulates protective mechanisms in the cardiovascular, nervous, and respiratory systems. The detrimental effects of peroxynitrite and related reactive species are impaired by (pseudo‐) enzymatic systems, mainly represented by heme‐proteins (e.g., hemoglobin and myoglobin). Here, we report biochemical aspects of peroxynitrite actions being at the root of its biomedical effects.
Hepatic ischaemia–reperfusion injury from bench to bedside
Authors: Bahde R , Spiegel H-U
Published: July 2010

Background

Vascular occlusion to prevent haemorrhage during liver resection causes ischaemia–reperfusion (IR) injury. Insights into the mechanisms of IR injury gathered from experimental models have contributed to the development of therapeutic approaches, some of which have already been tested in randomized clinical trials.

Methods

The review was based on a PubMed search using the terms ‘ischemia AND hepatectomy’, ‘ischemia AND liver’, ‘hepatectomy AND drug treatment’, ‘liver AND intermittent clamping’ and ‘liver AND ischemic preconditioning’; only randomized controlled trials (RCTs) were included.

Results

Twelve RCTs reported on ischaemic preconditioning and intermittent clamping. Both strategies seem to confer protection and allow extension of ischaemia time. Fourteen RCTs evaluating pharmacological interventions, including antioxidants, anti-inflammatory drugs, vasodilators, pharmacological preconditioning and glucose infusion, were identified.

Conclusion

Several strategies to prevent hepatic IR have been developed, but few have been incorporated into clinical practice. Although some pharmacological strategies showed promising results with improved clinical outcome there is not sufficient evidence to recommend them.
On estimating model complexity and prediction errors in multivariate calibration: generalized resampling by random sample weighting (RSW)
Authors: Xu L. , Xu Q.‐S. , Yang M. , Zhang H.‐Z. , Cai C.‐B. , Jiang J.‐H. , Wu H.‐L. , Yu R.‐Q.
Published: July 2010

The present paper focuses on determining the number of PLS components by using resampling methods such as cross validation (CV), Monte Carlo cross validation (MCCV), bootstrapping (BS), etc. To resample the training data, random non‐negative weights are assigned to the original training samples and a sample‐weighted PLS model is developed without increasing the computational burden much. Random weighting is a generalization of the traditional resampling methods and is expected to have a lower risk of getting an insufficient training set. For prediction, only the training samples with random weights less than a threshold value are selected to ensure that the prediction samples have less influence on training. For complicated data, because the optimal number of PLS components is often not unique or readily distinguished and there might exist an optimal region of model complexity, the distribution of prediction errors can be more useful than a single value of root mean squared error of prediction (RMSEP). Therefore, the distribution of prediction errors are estimated by repeated random sample weighting and used to determine model complexity. RSW is compared with its traditional counterparts like CV, MCCV, BS and a recently proposed randomization test method to demonstrate its usefulness. Copyright © 2010 John Wiley & Sons, Ltd.
The Trigonal Prism in Coordination Chemistry
Authors: Cremades Eduard , Echeverría Jorge , Alvarez Santiago
Published: July 2010

Herein we analyze the accessibility of the trigonal‐prismatic geometry to metal complexes with different electron configurations, as well as the ability of several hexadentate ligands to favor that coordination polyhedron. Our study combines i) a structural database analysis of the occurrence of the prismatic geometry throughout the transition‐metal series, ii) a qualitative molecular orbital analysis of the distortions expected for a trigonal‐prismatic geometry, and iii) a computational study of complexes of several transition‐metal ions with different hexadentate ligands. Also the tendency of specific electron configurations to present a cis bond‐stretch Jahn–Teller distortion is analyzed.
Sequence, Stoichiometry, and Dimensionality Control in Porphyrin/Bis‐calix[4]arene Self‐Assemblies in Aqueous Solution
Authors: D'Urso Alessandro , Cristaldi Domenico Andrea , Fragalà Maria Elena , Gattuso Giuseppe , Pappalardo Andrea , Villari Valentina , Micali Norberto , Pappalardo Sebastiano , Parisi Melchiorre F. , Purrello Roberto
Published: July 2010

The use of a water‐soluble octacationic bis‐calix[4]arene with divergent cavities (BC4) as a templating agent for the assembly of a tetraanionic porphyrin (CuTPPS) has allowed the noncovalent synthesis of 2D or 3D multiporphyrin assemblies. Self‐assembly of CuTPPS and BC4 molecules proceeded under hierarchical control in a stepwise fashion to yield discrete and isolable supramolecular nanostructures containing up to 33 molecular elements (i.e., the CuTPPS/BC4 17:16 assembly, obtained in less than three hours). The formation of these species could be conveniently monitored by means of UV/Vis spectroscopy by following the absorbance of the Soret band at 412 nm. In particular, the attainment of the pivotal CuTPPS/BC4 5:4 species with a cruciform structure, as the key fork‐point intermediate for the subsequent formation of the higher 2D and 3D assemblies, has been demonstrated by light‐scattering studies and by an unequivocal synthesis of mixed‐porphyrin/calixarene 5:4 species involving the use of two different types of metallated porphyrins, namely CuTPPS and MnTPPS. The remarkable stability of these assemblies permits a stepwise synthesis that makes it possible to choose the desired porphyrin sequence.
Lithiated Fluorinated Styrene Oxides: Configurational Stability, Synthetic Applications, and Mechanistic Insight
Authors: Capriati Vito , Florio Saverio , Perna Filippo Maria , Salomone Antonio
Published: July 2010

The configurational stability of some lithiated fluorinated styrene oxides has been investigated. Chemical studies have shown that in ethereal solvents α‐lithiated ortho‐, meta‐, and para‐fluorostyrene oxides (2‐Li, α‐5‐Li, and α‐6‐Li) are all configurationally stable in the reaction time scale, whereas α‐lithiated ortho‐, meta‐, and para‐trifluoromethylstyrene oxides (9‐Li, 13‐Li, and 14‐Li) are configurationally unstable. Optically active oxiranyllithiums 2‐Li and 9‐Li, could be stereospecifically generated and quenched with electrophiles. The corresponding derivatives were then successfully subjected to regiospecific ring‐opening reactions with amines to give fluorinated β‐amino alcohols with a stereodefined quaternary carbinol center, which are useful synthons in medicinal chemistry. The barriers of inversion have been calculated (Eyring equation) for oxiranyllithiums 9‐Li, 13‐Li, and 14‐Li by determining the enantiomeric ratios after electrophilic quenching on aging the enantioenriched organolithium for different times in THF; in the case of 9‐Li, activation parameters have also been determined. Mechanisms that may be responsible of the racemization oxiranyllithiums 9‐Li, 13‐Li, and 14‐Li undergo once generated are also discussed.
Alkylative Carbocyclization of ω‐Iodoalkynyl Tosylates with Alkynyllithium Compounds Through a Carbenoid‐Chain Process Leading to (1‐Iodoprop‐2‐ynylidene)tetrahydrofurans and ‐cyclopropanes
Authors: Harada Toshiro , Imaoka Daisuke , Kitano Chie , Kusukawa Takahiro
Published: July 2010

Alkylative carbocyclization reactions of ω‐iodoalkynyl tosylates with alkynyllithium compounds to give products with incorporated iodine atoms are described. Slow addition of 2‐(3‐iodoprop‐2‐ynyloxy)ethyl tosylates to 1‐alkynyllithium compounds in tetrahydrofuran at 40 °C followed by additional stirring at this temperature gives (Z)‐3‐(1‐iodoprop‐2‐ynylidene)tetrahydrofurans stereoselectively in good to moderate yields. Under similar conditions at 0 °C, 4‐iodobut‐1‐ynyl tosylates react with 1‐alkynyllithium compounds to give (1‐iodoprop‐2‐ynylidene)cyclopropanes. The carbocyclization reactions are proposed to proceed through a new carbenoid‐chain process involving the exo cyclization of a lithium acetylide intermediate and the vinylic substitution of the resulting TsO,Li‐cycloalkylidenecarbenoids (Ts=tosyl) by 1‐alkynyllithium compounds.
Dioxygenase‐Like Reactivity of an Isolable Superoxo–Nickel(II) Complex
Authors: Company Anna , Yao Shenglai , Ray Kallol , Driess Matthias
Published: July 2010

Although O2 activation by metals such as iron and copper has been a matter of intensive research in the last decades, this type of chemistry for nickel systems is still in its infancy. Moreover, studies regarding the oxidizing ability of the resulting “Nin–O2” species towards exogenous substrates are scarce. In this work, we report on the reactivity of an isolable and thermally stable mononuclear superoxo–nickel compound [NiII(β‐diketiminato)(O2)] (1) towards different types of organic substrates. In addition, we have been able to prove that the β‐diketiminato ligand can undergo partial intramolecular oxidation due to close proximity between the isopropyl groups of the β‐diketiminato‐aryl and the superoxo subunits. Compound 1 performs hydrogen‐atom abstraction from O‐H and N‐H groups and most importantly it shows an unprecedented dioxygenase‐like reactivity in the oxidation of 2,4,6‐tri‐tert‐butylphenol. The latter reaction most likely occurs through the mediation of a putative [NiIII‐oxo] intermediate, affording an unprecedented oxidation product of the phenol that incorporates two oxygen atoms from a single O2 subunit. Results presented herein provide evidence of the striking oxidizing ability of dioxygen–nickel species and further support the viability to use such systems as oxidation catalysts analogous to its heavy metal congener, palladium.
Systems Chemistry Approach in Organic Photovoltaics
Authors: Würthner Frank , Meerholz Klaus
Published: July 2010

The common approach in organic materials science is dominated by the perception that the properties of the bulk materials are virtually determined by the properties of the molecular building blocks. In this Concept Article, we advocate for taking into account supramolecular organization principles for all kinds of organic solid‐state materials, irrespective of them being crystalline, liquid crystalline, or amorphous, and discuss a showcase example, that is, the utilization of merocyanine dyes as p‐type organic semiconductors in bulk heterojunction (BHJ) solar cells. Despite their extraordinarily large dipole moments, which are considered to be detrimental for efficient charge carrier transport, BHJ organic photovoltaic materials of these dyes with fullerenes have reached remarkable power conversion efficiencies of meanwhile nearly 5 %. These at the first glance contradictory properties are, however, well‐understandable on the systems chemistry level.
Semistate models of electrical circuits including memristors
Authors: Riaza Ricardo , Tischendorf Caren
Published: July 2010

In this paper we present several semistate or differential‐algebraic models arising in nodal analysis of nonlinear circuits including memristors. The goal is to characterize the tractability index of these models under strict passivity assumptions, a key issue for the numerical simulation of circuit dynamics. We show that the main model, which combines memristors' fluxes and charges, is index two. From a technical point of view, this result is based on the use of a projector along the image of the leading matrix, in contrast to previous index analyses. For charge‐controlled memristors, the elimination of fluxes yields an index one system in topologically nondegenerate circuits, and an index two model otherwise. Analogous results are also proved to hold for flux‐controlled memristors. Our framework accommodates coupling effects among resistors, memristors, capacitors and inductors. Copyright © 2010 John Wiley & Sons, Ltd.
A scalable and efficient key escrow model for lawful interception of IDBC‐based secure communication
Authors: Han Kyusuk , Yeun Chan Yeob , Shon Taeshik , Park Jonghyuk , Kim Kwangjo
Published: July 2010

Key escrowing is one of the core technologies for the lawful interception (LI) of secure communications in the wired and wireless networks. Although many previous studies on the key escrowing have been done before, they are insufficient to be deployed in practical networks due to conflicts with the LI requirements. Moreover, there is lack of consideration on the LI of ID‐based cryptosystem (IDBC)‐based secure communication because the interest of the LI was moved to the industries and IDBC has the inherent key escrowing property. However, the inherent property of IDBC cannot prevent ‘illegal’ eavesdropping of all the communications in the networks from the law enforcement agency with the ‘legally’ obtained key. Thus, we propose a new key escrow model that satisfies the requirements of LI and overcomes the potential threats of IDBC. Our contributions enable the scalable and efficient key escrowing for the LI of secure one‐way and two‐pass communication in the mobile networks. Copyright © 2010 John Wiley & Sons, Ltd.
Distributed BLAST with relay selection for multi‐antenna AF relaying
Authors: Bahrami Hamid Reza , Le‐Ngoc Tho
Published: July 2010

By examining the diversity–multiplexing tradeoff (DMT) of an amplify‐and‐forward (AF) multi‐antenna multi‐relay network, a procedure to select the optimal number of relays and relay candidates is established. Subsequently, a distributed BLAST transmission scheme in conjunction with successive nulling and cancellation at destination is proposed to achieve the optimal DMT. Illustrative results indicate that the proposed method can significantly enhance the outage probability performance, and for a selected number of relays in use, the performance enhancement can be further improved by increasing the number of available relays in the AF network. Copyright © 2010 John Wiley & Sons, Ltd.
The global challenge of type 2 diabetes and the strategies for response in ethnic minority groups
Authors: Lirussi Flavio
Published: July 2010

Ethnic minorities living in high‐income countries usually exhibit a greater risk of developing diabetes along with higher morbidity and mortality rates. We evaluated the effectiveness of interventions to improve glycaemic control in ethnic minority groups. Results of major controlled trials, systematic reviews and meta‐analyses were included in the review. Only 1/47 studies addressing diet and exercise interventions reported details on the ethnicity of the studied population. Self‐management education was successful if associated with increased self‐efficacy; delivered over a longer period; of high intensity; culturally tailored; and when using community educators. Strategies adopted in community‐gathering places, family‐based, multifaceted, and those tackling the social context were likely to be more effective. A positive relationship was found between social support and self‐management behaviour as well as quality of life, but there is little evidence about the impact of organizational changes within health‐care services on diabetes control. More research is needed to strengthen the evidence on effective strategies for response to diabetes in ethnic minorities. Also, there is a need to take into account diabetes beliefs and communication difficulties, as well as potential protective factors. Globally, many health‐care systems are inadequately equipped to improve diabetes prevention and disease outcomes in these communities. Copyright © 2010 John Wiley & Sons, Ltd.