Positive Values (positive + value)

Distribution by Scientific Domains


Selected Abstracts


The Decision of the Supply Chain Executive to Support or Impede Supply Chain Integration: A Multidisciplinary Behavioral Agency Perspective,

DECISION SCIENCES, Issue 4 2009
Verónica H. Villena
ABSTRACT Applying the behavioral agency model developed by Wiseman and Gomez-Mejia (1998), this article analyzes human resource factors that induce supply chain executives (SCEs) to make decisions that foster or hinder supply chain integration. We examine two internal sources (compensation and employment risk) and one external source (environmental volatility) of risk bearing that can make SCEs more reluctant to make the decision to promote supply chain integration. We argue and empirically confirm the notion that an employment and compensation system that increases SCE risk bearing reduces the SCE's willingness to make risky decisions and thus discourages supply chain integration. We also reveal that this negative relationship becomes stronger under conditions of high environmental volatility. In addressing the "so what?" question, we found empirical support for the hypothesis that supply chain integration positively influences operational performance. Even though this decision has a positive value for the firm, we showed that SCEs discourage supply chain integration when they face higher risk bearing. Hypotheses are tested using a combination of primary survey data and archival measures in a sample of 133 Spanish firms. [source]


Decision Theory Applied to an Instrumental Variables Model

ECONOMETRICA, Issue 3 2007
Gary Chamberlain
This paper applies some general concepts in decision theory to a simple instrumental variables model. There are two endogenous variables linked by a single structural equation; k of the exogenous variables are excluded from this structural equation and provide the instrumental variables (IV). The reduced-form distribution of the endogenous variables conditional on the exogenous variables corresponds to independent draws from a bivariate normal distribution with linear regression functions and a known covariance matrix. A canonical form of the model has parameter vector (,, ,, ,), where ,is the parameter of interest and is normalized to be a point on the unit circle. The reduced-form coefficients on the instrumental variables are split into a scalar parameter ,and a parameter vector ,, which is normalized to be a point on the (k,1)-dimensional unit sphere; ,measures the strength of the association between the endogenous variables and the instrumental variables, and ,is a measure of direction. A prior distribution is introduced for the IV model. The parameters ,, ,, and ,are treated as independent random variables. The distribution for ,is uniform on the unit circle; the distribution for ,is uniform on the unit sphere with dimension k-1. These choices arise from the solution of a minimax problem. The prior for ,is left general. It turns out that given any positive value for ,, the Bayes estimator of ,does not depend on ,; it equals the maximum-likelihood estimator. This Bayes estimator has constant risk; because it minimizes average risk with respect to a proper prior, it is minimax. The same general concepts are applied to obtain confidence intervals. The prior distribution is used in two ways. The first way is to integrate out the nuisance parameter ,in the IV model. This gives an integrated likelihood function with two scalar parameters, ,and ,. Inverting a likelihood ratio test, based on the integrated likelihood function, provides a confidence interval for ,. This lacks finite sample optimality, but invariance arguments show that the risk function depends only on ,and not on ,or ,. The second approach to confidence sets aims for finite sample optimality by setting up a loss function that trades off coverage against the length of the interval. The automatic uniform priors are used for ,and ,, but a prior is also needed for the scalar ,, and no guidance is offered on this choice. The Bayes rule is a highest posterior density set. Invariance arguments show that the risk function depends only on ,and not on ,or ,. The optimality result combines average risk and maximum risk. The confidence set minimizes the average,with respect to the prior distribution for ,,of the maximum risk, where the maximization is with respect to ,and ,. [source]


Seismic anisotropy of shales

GEOPHYSICAL PROSPECTING, Issue 5 2005
C.M. Sayers
ABSTRACT Shales are a major component of sedimentary basins, and they play a decisive role in fluid flow and seismic-wave propagation because of their low permeability and anisotropic microstructure. Shale anisotropy needs to be quantified to obtain reliable information on reservoir fluid, lithology and pore pressure from seismic data, and to understand time-to-depth conversion errors and non-hyperbolic moveout. A single anisotropy parameter, Thomsen's , parameter, is sufficient to explain the difference between the small-offset normal-moveout velocity and vertical velocity, and to interpret the small-offset AVO response. The sign of this parameter is poorly understood, with both positive and negative values having been reported in the literature. , is sensitive to the compliance of the contact regions between clay particles and to the degree of disorder in the orientation of clay particles. If the ratio of the normal to shear compliance of the contact regions exceeds a critical value, the presence of these regions acts to increase ,, and a change in the sign of ,, from the negative values characteristic of clay minerals to the positive values commonly reported for shales, may occur. Misalignment of the clay particles can also lead to a positive value of ,. For transverse isotropy, the elastic anisotropy parameters can be written in terms of the coefficients W200 and W400 in an expansion of the clay-particle orientation distribution function in generalized Legendre functions. For a given value of W200, decreasing W400 leads to an increase in ,, while for fixed W400, , increases with increasing W200. Perfect alignment of clay particles with normals along the symmetry axis corresponds to the maximum values of W200 and W400, given by and . A comparison of the predictions of the theory with laboratory measurements shows that most shales lie in a region of the (W200, W400)-plane defined by W400/W200,Wmax400/Wmax200. [source]


Scintigraphic evaluation of intrapulmonary shunt in normoxemic cirrhotic patients and effects of terlipressin

HEPATOLOGY RESEARCH, Issue 10 2010
George Kalambokis
Aim:, The magnitude of intrapulmonary shunt (IPS) in cirrhotic patients without hypoxemia remains undefined. We evaluated the severity and clinical correlations of IPS in normoxemic cirrhotics, and possible IPS alterations after terlipressin treatment. Methods:, Fifteen patients with alcoholic cirrhosis without hypoxemia were studied at baseline and after the administration of 2 mg of terlipressin. The IPS fraction was evaluated by lung perfusion scan after the i.v. injection of technetium-99m -labeled macroaggregated albumin (99mTc-MAA) and calculation of brain uptake (positive value ,6%). Cardiac output (CO), pulmonary artery systolic pressure (PASP) and pulmonary vascular resistance (PVR) were evaluated by Doppler echocardiography. Mean arterial pressure (MAP) was measured and the ratio MAP/CO was calculated as an index of systemic vascular resistance (SVR). Portal vein velocity (PVV) and portal venous flow (PVF) were also assessed by Doppler ultrasonography. Results:, Three patients (20%) had an IPS fraction of more than 6%. A significant inverse correlation with platelet count (P = 0.001) and a direct correlation with Child,Pugh score (P = 0.06), PVV (P = 0.07) and PVF (P = 0.07) were noted. IPS fractions decreased significantly after terlipressin administration (P = 0.00001); the IPS fraction fell below 6% in all three patients with positive baseline values. Terlipressin treatment induced a significant decrease in CO (P = 0.003) and significant increases in MAP (P = 0.0003), SVR (P = 0.0003), SPAP (P = 0.001) and PVR (P = 0.01). Conclusion:, IPS fractions detected by 99mTc-MAA lung scan were inversely correlated with platelet count and directly with liver disease severity, and found abnormal in 20% of normoxemic cirrhotic patients. Terlipressin reduced significantly the magnitude of the shunt. [source]


OPTIMAL MONETARY POLICY: WHAT WE KNOW AND WHAT WE DON'T KNOW*

INTERNATIONAL ECONOMIC REVIEW, Issue 2 2005
Narayana R. KocherlakotaArticle first published online: 5 MAY 200
In this article, I examine the current state of knowledge about optimal monetary policy. I distinguish between two literatures, basic and applied. The basic literature is explicit about the frictions that generate a positive value for money and make it socially beneficial. The applied literature is not. I describe the recent lessons about monetary policy that we have learned from each literature and discuss how the two distinct approaches may be usefully combined. [source]


An optimally convergent discontinuous Galerkin-based extended finite element method for fracture mechanics

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2010
Yongxing Shen
Abstract The extended finite element method (XFEM) enables the representation of cracks in arbitrary locations of a mesh. We introduce here a variant of the XFEM rendering an optimally convergent scheme. Its distinguishing features are as follows: (a) the introduction of singular asymptotic crack tip fields with support on only a small region around the crack tip (the enrichment region), (b) only one and two enrichment functions are added for anti-plane shear and planar problems, respectively and (c) the relaxation of the continuity between the enrichment region and the rest of the domain, and the adoption of a discontinuous Galerkin (DG) method therein. The method is provably stable for any positive value of a stabilization parameter, and by weakly enforcing the continuity between the two regions it eliminates ,blending elements' partly responsible for the suboptimal convergence of some early XFEMs. Moreover, the particular choice of enrichment functions results in a surprisingly sparse stiffness matrix that remains reasonably conditioned as the mesh is refined. More importantly, the stress intensity factors can be extracted with a satisfactory accuracy as primary unknowns. Quadrature strategies required for the optimal convergence are also discussed. Finally, the DG method was modified to retain stability based on an inf-sup condition. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Editors' Introduction: Birds and Agriculture

JOURNAL OF APPLIED ECOLOGY, Issue 5 2000
S.J. Ormerod
1.,Around 10% of recent papers in the Journal of Applied Ecology have examined interactions between birds and agriculture. This statistic reveals the important role now played by ecologists in assessing the effects of agricultural development worldwide. It also reflects the position of birds as both indicators and targets of agricultural change: their patterns of behaviour, distribution, seasonal phenology and demography track closely onto the spatial and temporal scales of agricultural intensification. 2.,Papers in this Special Profile illustrate how research in this sphere has shifted towards assessing the processes by which birds are affected ecologically by agricultural change. The works examine spatial patterns in extinction; assess long-term trends in bird abundance and agricultural practice; reveal how foraging and breeding performance in farmland birds varies between habitats; and evaluate the role of large-scale modelling in examining hypotheses about the influences of land management on birds. The final paper shows that birds can have intrinsically positive value in agricultural systems. 3.,All the papers propose management prescriptions for agricultural areas that blend the microscopic , for example, how to modify local land structure to benefit birds , and the macroscopic , for example, by suggested inputs into land-use policy. Perhaps most pertinent is the key conclusion that agricultural change is multivariate, so that straightforward univariate effects on birds are unlikely. Restoration of impacted populations might therefore require holistic strategies that encourage appropriately scaled agricultural extensification. Success would be most likely if farmers, conservationists and other key players were engaged collaboratively in the process. 4.,Current ideas about restoring farmland bird populations share a common assumption: if agricultural practice has reduced populations hitherto, then agricultural practice can restore the losses. We suggest that this assumption carries a range of predictions that now require testing through sustainable farm management , a situation ideally suited to ,BACI' style experiments. 5.,We reiterate the need to expand work on other groups of organisms affected negatively or positively by agricultural management to allow a broader perspective of impacts or benefits. [source]


Does service failure influence customer loyalty?

JOURNAL OF CONSUMER BEHAVIOUR, Issue 3 2002
Francis Buttle
Abstract There is a general consensus that customer loyalty to service providers is not solely dependent upon their level of satisfaction or dissatisfaction. However, the identified antecedents of loyalty remain, at best, highly speculative. The aim of this extensive literature review is to give some understanding of the nature of customer loyalty and the antecedent effects of service dissatisfaction. The research reviewed suggests that customer loyalty is an attitudinal state, reflecting value, trust and commitment within supplier,customer relationships. Satisfaction is one of several antecedents of loyalty. A key influence on loyalty is the offer of unique value-delivering advantages not provided by competitors. Thus firms need to develop positive value-based exit barriers to achieve loyalty. When service failures occur, the recovery process is likely to have a greater impact on loyalty than the original service failure. The key to successful recoveries was found to be the customer's perception of ,fairness'. Recovery programmes must get it right first time. Customers who remain dissatisfied after a complaint has been handled are more dissatisfied than if no recovery attempt had been made. Dissatisfaction and customer satiation are major causes of a customer's exit. The solution to customer satiation is dynamic value creation. Collection and monitoring of customer data is needed for success and two-way communication is vital. Copyright © 2002 Henry Stewart Publications. [source]


Thermodynamically Stable SiwCxNyOz Polymer-Like, Amorphous Ceramics Made from Organic Precursors

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008
Riham M. Morcos
This communication reports new results on the enthalpy of formation of pseudo-amorphous ceramic compounds constituted from silicon, carbon, oxygen, and nitrogen (SiCNO), made from the polymer route. Again, like the SiCO materials, although with one exception, the enthalpy of formation from crystalline components (SiO2 cristobalite, ,-Si3N4, SiC, and excess C) is negative. Some of the alloyed oxygen,nitrogen compositions yield enthalpies that are much more negative (,100 kJ/g·atom) in comparison with compositions that contain mainly oxygen or nitrogen (,20 kJ/g·atom). The exception, having a N/O ratio near 2, has a positive value for the enthalpy. This may reflect the presence of nanoclusters of stoichiometric Si2N2O instead of the pseudo-amorphous nanodomain structure seen for the other samples. [source]


Resolving an apparent discrepancy between theory and experiment: spin,spin coupling constants for FCCF

MAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2008
Janet E. Del Bene
Abstract Ab initio equation of motion coupled cluster singles and doubles (EOM,CCSD) and second-order polarization propagator approximation (SOPPA) calculations have been performed to evaluate spin,spin coupling constants for FCCF (difluoroethyne). The computed EOM-CCSD value of 3J(FF) obtained at the experimental geometry of this molecule supports the previously reported experimental value of 2.1 Hz, thereby resolving an apparent discrepancy between theory and experiment. This coupling constant exhibits a strong dependence on the CC and CF distances, and its small positive value results from a sensitive balance of paramagnetic spin-orbit (PSO) and spin-dipole (SD) terms. The three other unique FCCF coupling constants 1J(CC), 1J(CF), and 2J(CF) have also been reported and compared with experimental data. While 1J(CF) is in agreement with experiment, the computed value of 2J(CF) is larger than our estimate of the experimental coupling constant. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Effect of cooling field strength and ferromagnetic shell shape on exchange bias in nanoparticles with inverted ferromagnetic,antiferromagnetic core-shell morphology

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2010
Yong Hu
Abstract The dependence of exchange bias (EB) effects on cooling field strength and particle shape in nanoparticles with antiferromagnetic (AFM) interfacial coupling and inverted AFM core with a fixed radius and ferromagnetic (FM) shell with various thicknesses are investigated by using a modified Monte Carlo Metropolis method. It is found that with the increase of cooling field, field-cooled exchange bias field (HE) fluctuates in the range of negative values initially, and then has an abrupt jump from the negative value to the positive value, finally levels off. However, HE decreases as the FM shell shape varies from No. 1 to No. 13 regardless of the strength of cooling field. Coercivity is affected by cooling fields and shapes indicating distinct behaviors. Because the AFM core is almost unaffected by shape and frozen completely during measuring hysteresis loops, the effect of ferromagnets on EB, negligible in most of other systems, is ambiguously manifested in such an unconventionally structural system. Moreover, the phenomena are interpreted well by presenting the snapshots of microscopic spin energy distributions, which make us observe directly and vividly the movement of domains and the competition of energies. This work will shed new light into the microscopic origin of peculiar magnetic properties of nanoparticles with special structures. [source]


Magneto-optical spectroscopy of (Zn,Co)O epilayers

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2006
W. Pacuski
Abstract We present a magneto-optical study of (Zn,Co)O layers grown by molecular beam epitaxy. We observed sharp lines related to 4A2,2E intra-ionic Co2+ transitions, and to the A , B and C excitons. Intra-ionic transitions observed by absorption and photoluminescence were used to determine the values of the parameters describing the isolated Co ions, such as the easy-plane magnetic anisotropy and the g -factor of the S = 3/2 Cobalt spin. Excitonic transitions observed in reflectivity were used to determine the giant Zeeman splitting and to estimate the effective coupling ,N0(, , , ),A ,B = 0.4 eV between excitons and Cobalt spins. Due to the electron,hole exchange within the exciton, this effective spin,exciton coupling is much weaker than the exchange integrals for free carriers, estimated to be N0|, , , | , 0.8 eV, with a positive value of (, , , ) if the normal ordering of the valence band of ZnO is assumed. The Zeeman splitting of diluted samples and the magnetic circular dichroism (for a higher Co content) are proportional to the magnetization of the paramagnetic, isolated Cobalt ions. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Solution NMR evidence for a cis Tyr-Ala peptide group in the structure of [Pro93Ala] bovine pancreatic ribonuclease A

PROTEIN SCIENCE, Issue 2 2000
Ying Xiong
Abstract Proline peptide group isomerization can result in kinetic barriers in protein folding. In particular, the cis proline peptide conformation at Tyr92-Pro93 of bovine pancreatic ribonuclease A (RNase A) has been proposed to be crucial for chain folding initiation. Mutation of this proline-93 to alanine results in an RNase A molecule, P93A, that exhibits unfolding/refolding kinetics consistent with a cis Tyr92-Ala93 peptide group conformation in the folded structure (Dodge RW, Scheraga HA, 1996, Biochemistry 35:1548,1559). Here, we describe the analysis of backbone proton resonance assignments for P93 A together with nuclear Overhauser effect data that provide spectroscopic evidence for a type VI ,-bend conformation with a cis Tyr92-Ala93 peptide group in the folded structure. This is in contrast to the reported X-ray crystal structure of [Pro93Gly]-RNase A (Schultz LW, Hargraves SR, Klink TA, Raines RT, 1998, Protein Sci 7:1620,1625), in which Tyr92-Gly93 forms a type-II ,-bend with a trans peptide group conformation. While a glycine residue at position 93 accommodates a type-II bend (with a positive value of ø93), RNase A molecules with either proline or alanine residues at this position appear to require a cis peptide group with a type-VI ,-bend for proper folding. These results support the view that a cis Pro93 conformation is crucial for proper folding of wild-type RNase A. [source]


COMPETITIVE ISSUES IN THE TAIWANESE BANKING INDUSTRY: MERGERS AND UNIVERSAL BANKS

THE DEVELOPING ECONOMIES, Issue 3 2003
Peiyi YU
This paper investigates scale economies and scope economies in the Taiwanese banking system, looking beyond the market-power (MP) and efficient-structure (ES) hypotheses. Given the existence of overall economies of scale and the positive value of expansion path sub-additivity, we conclude that there might be large increases in profits following mergers. Moreover, since the profit-structure relationship after financial reform is determined by the relative-market-power hypothesis, this consolidation trend will not necessarily decrease the social benefit for Taiwanese consumers. With regard to scope economies and product-specific economies of scale, we are unable to recommend whether Taiwanese banks should develop as specialized banks or diversified banks in the future. Finally, we find that risk indicators play an important role in explaining the observed variation in bank profitability, and present evidence that default risk and leverage risk have negative effects on the profits of banking, although the effect of portfolio risk is uncertain. [source]


Role of Laryngeal Movement and Effect of Aging on Swallowing Pressure in the Pharynx and Upper Esophageal Sphincter,

THE LARYNGOSCOPE, Issue 3 2000
Masato Yokoyama MD
Abstract Objectives Describe contribution of laryngeal movement to pressure changes at the upper esophageal sphincter (UES) and the effect of aging on the swallowing function. Study Design Manofluorography on 56 nondysphagic adults divided into three age groups: the 21- to 31-year-old group (n = 32), the 61- to 74-year-old group (n = 12) and the 75- to 89-year-old group (n = 12). Analyses of the bolus transit time, the amplitudes and durations of pharyngeal pressures, the timing of a pressure fall at the UES and the laryngeal movements. Methods Intraluminal strain-gauge sensors recorded pressure changes in the oropharynx, hypopharynx and the UES. Motion pictures of the videotapes were fed into a personal computer, and movements of the hyoid bone were measured in both the horizontal and vertical directions as an indication of laryngeal movement. Results In 26- and 70-year-old men with calcification of the thyroid cartilage, it was determined that the larynx and hyoid bone moved in consonance until the end of the rapid hyoid movements in both the superior and anterior directions. In the 21- to 31-year-old group, the magnitude of the pressure fall at the UES was maximal before or almost at the same time as the bolus arrival, in preparation for smooth passage of the bolus from the pharynx to the esophagus. The rapid superior movements of the hyoid bone started significantly early as compared with its anterior movements (P = .0001). The rapid anterior movements of the hyoid bone started simultaneously with the pressure fall at the UES. In the elderly, all segmental transit times were significantly increased. The timing of the pressure fall at the UES was significantly delayed and the UES pressure reached its minimum value after arrival of the bolus at the UES. The minimum pressure at the UES increased to a significantly positive value. The rapid anterior movements of the hyoid were significantly delayed, suggesting that this delay causes the delay in the pressure fall at the UES. Conclusions The rapid superior and anterior movements of the hyoid bone are considered to start at the same time as those of the larynx. In the young group, it is suggested that superior laryngeal movement protects the lower airway prior to the anterior laryngeal movement, causing the pressure fall at the UES to enable the passage of a bolus into the UES. In the elderly, smooth passage of the bolus from the pharynx to the esophagus is hindered and the system that prevents aspiration is rendered inefficient by changes in the swallowing pressures and laryngeal movements with aging. [source]


Using a complex non-TDN based model (the DVE/OEB system) to predict microbial protein synthesis, endogenous protein, degradation balance, and total truly absorbed protein supply of different varieties of cereal oats for ruminants

ANIMAL SCIENCE JOURNAL, Issue 3 2009
Peiqiang YU
ABSTRACT Recently a new super-genotype of oat has been developed in the Crop Development Center called CDC SO-I (,SuperOat': low lignin and high fat). In a previous study, we evaluated total metabolizable protein using a TDN-based model-NRC-2001 which is popular in North America. However, the TDN-based NRC model is not accepted universally. The objectives of this study were to use a complex non-TDN based model, the DVE/OEB system, to evaluate potential nutrient supply to ruminants from the SuperOat in comparison with two normal varieties of oats (CDC Dancer and Derby) in western Canada. The quantitative predictions were made in terms of: (i) truly absorbed rumen synthesized microbial proteins in the small intestine; (ii) truly absorbed rumen undegraded feed protein in the small intestine; (iii) endogenous protein in the digestive tract; (iv) total truly absorbed protein in the small intestine; and (v) protein degraded balance. Results showed that using the DVE/OEB system to predict the potential nutrient supply, it was found that the SuperOat had similar truly absorbed rumen synthesized microbial protein levels (61, 63, 59 g/kg DM, P > 0.05, for SuperOat, CDC Dancer and Derby, respectively), higher truly absorbed rumen undegraded feed protein than CDC Dancer (22 vs. 17 g/kg DM P < 0.05, for SuperOat, CDC Dancer, respectively), but similar to Derby (22 vs. 21 g/kg DM; P > 0.05), and similar endogenous protein (16, 16, 18 g/kg DM; P > 0.05). Total truly absorbed protein in the small intestine is only numerically higher in the SuperOat (67 vs. 65, 62 g/kg DM, P > 0.05, for CDC Dancer and Derby, respectively). However, the protein degraded balance was significantly different (P < 0.05) with a positive value for the SuperOat (7.0 g/kg DM) and negative values for two normal varieties (,1.5, ,6.8 g/kg DM for CDC Dancer and Derby, respectively). In conclusion, the model predicted significantly different protein degradation balance. The SuperOat had positive degradation balance but other two normal varieties had negative protein degraded balance However, the SuperOat had similar total absorbed protein value to the two normal varieties of oats. [source]


A Comparison of the Variability Spectra of Two Genomic Loci in a European Group of Individuals Reveals Fundamental Differences Pointing to Selection or a Population Bottleneck

ANNALS OF HUMAN GENETICS, Issue 3 2007
C. Schmegner
Summary Knowledge about the variability spectra of neutrally evolving sequences in a population is a prerequisite for the identification of genes, which may have been under positive selection during recent human evolution. Here, we report the results of a re-sequencing project of a presumably neutrally evolving chromosome 22 locus with a severely reduced recombination frequency in a group of 24 individuals of German origin. The comparison of these data with the results of a similar analysis of a chromosome 17 locus revealed striking differences, although the same group of individuals was used. For the chromosome 17 locus two well-separated groups of sequences, a positive value of Tajima's D and a TMRCA of 700 000 years were observed. In contrast, the sequences from the chromosome 22 locus were found to be relatively homogeneous, with no deep splits between subgroups; the obtained value for Tajima's D was negative and the TMRCA was only 260 000 years. These discrepancies may be explained by selection or demographic processes. Regarding demography, the most plausible explanation is the assumption of a severe bottleneck in the history of the European population: in the case of the chromosome 17 locus two ancient lineages passed this bottleneck; for the chromosome 22 locus it was only one ancient lineage. [source]


Energy absorption capacity; a new concept for stability analysis of nonlinear dynamic systems,

ASIAN JOURNAL OF CONTROL, Issue 1 2009
Ali Akbar Jamshidifar
Abstract Stability is the main concern considered for every system. Generally the well-known Lyapunov and input-output stability methods are utilized for the stability analysis of nonlinear systems. These methods face serious difficulties as the size and complexity of the systems increases. In this paper a new approach is presented to overcome this problem by introducing a new concept "Energy Absorption Capacity" (EAC) for every component. The EAC of the system can be derived from its component EACs considering their interaction. It is shown that the stability of every individual component is assured if its EAC has a positive value. The proposed approach is less conservative compared to a Lyapunov-based approach. This is due to its reliance on EAC as the extreme value of energy function rather than the function itself. Some examples are given to support the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]


Exploratory study examining barriers to participation in colorectal cancer screening

AUSTRALIAN JOURNAL OF RURAL HEALTH, Issue 1 2010
Johanna S. Paddison
Abstract Objective:,To examine the Stage of Change distribution for bowel cancer screening in a regional Australian community and the factors associated with varying positions on the continuum of change. Design:,Survey of a convenience sample. Setting:,Community sample. Participants:,A total of 59 (31 male, mean age = 59) service club members from a South Australian regional community. Main outcome measure:,Self-reported Stage of Change for bowel cancer screening behaviour. Results:,Attributing greater embarrassment and discomfort to bowel cancer screening was associated with earlier positions on the Stages of Change. Perceiving that bowel cancer screening might have positive value for personal health was associated with more advanced positions on the continuum of change. Those who perceived breast and prostate screening procedures to be embarrassing or to cause discomfort were significantly less likely to be participating in bowel cancer screening. No significant relationships were found between bowel cancer screening Stage of Change and worry about vulnerability; personal, family or wider social network case reports of bowel cancer; and the population-level value attributed to the cancer screening procedures. Conclusion:,Bowel cancer screening participation rates are currently lower than those associated with breast and prostate screening. Reducing perceptions of embarrassment and discomfort, increasing awareness of potential health benefits and maximising participation in other screening procedures might increase participation in bowel cancer screening. [source]


Into Cerberus' Lair: Bringing the Idea of Security to Light1

BRITISH JOURNAL OF POLITICS & INTERNATIONAL RELATIONS, Issue 4 2005
Graham M. Smith
Using the motif of Cerberus, the three-headed monster watchdog of Hades, this article attempts to bring ,security' to light. Specifically, it addresses two related questions. The primary question is: What does ,security' mean?. Here it is argued that ,security' is related to ,order' and is a reflection not of a positive value in and of itself, but the relative success of any given order to realise its core values in relation to other orders. Therefore, ,security' is found to be like Cerberus insofar as it exists not as an independent value or being, but only in relation between two orders. Having located ,security' within this conceptual framework, the article then addresses its second question: What are the effects of security?. The motif of Cerberus suggests that security ,bites' in three ways: first, that specific measures of security control the members of an order; second, that the identification of security threats reinforce certain persons and structures of the order as being the definers of the order; and finally, that the implementation of certain security measures can change and transform the order itself. In this way the analysis offered here brings ,security' to light not only as an inherently political term connected to political values, but to provide foundations for critiquing the rhetorical use of ,security' in contemporary political discourse and thought. [source]


Estimating Observation Unit Profitability with Options Modeling

ACADEMIC EMERGENCY MEDICINE, Issue 5 2008
Christopher W. Baugh MD
Abstract Background:, Over the past two decades, the use of observation units to treat such common conditions as chest pain, asthma, and others has greatly increased. These units allow patients to be directed out of emergency department (ED) acute care beds while potentially avoiding inpatient admission. Many studies have demonstrated the clinical effectiveness of care delivered in such a setting compared to the ED or inpatient ward. However, there are limited data published about observation unit finance. Methods:, Using the economic principles of stock options, opportunity costs, and net present value (NPV), a model that captures the value generated by admitting a patient to an observation unit was derived. In addition, an appendix is included showing how this model can be used to calculate the dollar value of an observation unit admission. Results:, A model is presented that captures more complexity of observation finance than the simple difference between payments and costs. The calculated estimate in the Appendix suggests that the average value of a single observation unit admission was about $2,908, which is about 40% higher than expected. Conclusion:, Subtraction of costs from payments may significantly underestimate the financial value of an observation unit admission. However, the positive value generated by an observation unit bed must be considered in the context of other projects available to hospital administrators. [source]


Young people's views of children's rights and advocacy services: a case for ,caring' advocacy?

CHILD ABUSE REVIEW, Issue 3 2007
Vivienne Barnes
Abstract This paper looks at some preliminary findings from research with young people in foster and residential care in the UK who have received advocacy services from a range of local authority and voluntary agencies. The study also includes the views of professionals, from both children's rights and social services. The initial findings highlight the importance to young people of their relationship with rights professionals. They speak about the value to them of care and respect, aspects not always seen as fundamental to rights work. Caring, in its various guises is seen by young people as a vital component of their relationship with children's rights workers. They also see this as important within advocacy work itself since caring about the outcome is often key. A pure individual rights focus with an emphasis on challenge and ,being heard' may not take account of the complexity of their situation and may pose difficult dilemmas for young people, especially in dealings with their carers. This ,caring' advocacy is not the paternalistic approach of a professional who ,knows what's best for you' but is a model based on a strong awareness of ways that young people are excluded and oppressed. It is also about placing a positive value on their contribution as citizens and links to a view of society that gives importance to an ethic of inter-relationship and care as well as an ethic of individual rights. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Climate-driven decrease in erosion in extant Mediterranean badlands

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2010
Michèle L. Clarke
Abstract Badland areas provide some of the highest erosion rates globally. Most studies of erosion have insufficient lengths of record to interrogate the impacts of decadal-scale changes in precipitation on rates of badland erosion in regions such as the Mediterranean, which are known to be sensitive to land degradation and desertification. Erosion measurements, derived from field monitoring using erosion pins, in southern Italy during the period 1974,2004 are used to explore the impacts of changing precipitation patterns on badland erosion. Erosion on badland inter-rill areas is strongly correlated with cumulative rainfall over each monitoring period. Annual precipitation has a substantial dynamic range, but both annual and winter (December, January, February) rainfall amounts in southern Italy show a steady decrease over the period 1970,2000. The persistence of positive values of the winter North Atlantic Oscillation index in the period 1980,2000 is correlated with a reduction in the winter rainfall amounts. Future climate scenarios show a reduction in annual rainfall across the western and central Mediterranean which is likely to result in a further reduction in erosion rates in existing badlands. Copyright © 2010 John Wiley & Sons, Ltd. [source]


The efficacy of dantrolene sodium in controlling exertional rhabdomyolysis in the Thoroughbred racehorse

EQUINE VETERINARY JOURNAL, Issue 7 2003
J. G. T. Edwards
Summary Reasons for performing study: Dantrolene sodium (Dantrium) has been used extensively for the treatment of myopathies in man and anecdotal evidence suggests it is of clinical benefit in the control of exercise-induced rhabdomyolysis (ER) in racehorses, although data to support this are currently lacking. Objectives: To investigate the efficacy of oral dantrolene sodium in controlling ER in a randomised, double-blind, placebo-controlled crossover trial involving 77 Thoroughbred racehorses in Newmarket, UK. Methods: Horses were treated on 2 occasions 1 week apart, with treatment days coinciding with a return to exercise following 2 days box rest on each occasion. For the first treatment, each horse was randomly selected to receive either 800 mg dantrolene sodium or a colour- matched placebo administered orally 1 h before exercise. This was followed by crossover to the other treatment on the second occasion, with each horse thereby acting as its own control. Degree of ER was assessed using rising serum creatine kinase (CK) levels, by subtracting pre-exercise blood CK levels from those measured in 6 h post exercise blood samples. For each horse, the difference in change between pre- and post exercise CK values between placebo and dantrolene treatments was calculated, with positive values indicating a greater rise with placebo than with dantrolene sodium treatment. Results: The overall mean difference for all horses was +104.8 iu/l and the null hypothesis, that there was no true difference in non-normally distributed post exercise rises in CK values between placebo and dantrolene treatments, was rejected (P = 0.0013) using the nonparametric Wilcoxon signed rank test. Additionally, no horses given dantrolene sodium showed clinical signs of ER, whereas 3 horses given the placebo developed ER following exercise. The incidence of ER in the study was 4% (3/77). Conclusions: The results confirmed that oral administration of dantrolene sodium, 1 h before exercise, had a statistically significant effect on reducing the difference between pre - and post exercise plasma CK levels compared with a placebo in the same animals, and preventing clinical ER in susceptible individuals. Potential relevance: This study suggested that dantrolene sodium is of use in controlling ER in the Thoroughbred racehorse. Further investigation into pre- and post exercise myoplasmic calcium levels and the repeat of the study late in the season when horses receive a much higher energy ration and more strenuous exercise would appear to be warranted. [source]


Activation Parameters for the Epoxidation of Substituted cis/trans Pairs of 1,2-Dialkylalkenes by Dimethyldioxirane

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2006
Brian S. Crow
Abstract The first activation parameter data for the reaction of dimethyldioxirane (1) with five cis/trans pairs of alkenes are reported. The epoxidation of cis -1,2-dialkylalkenes (2cis: R1 = Me, R2 = iPr; 3cis: R1 = Me, R2 = tBu; 4cis: R1 = R2 = Et; 5cis: R1 = Et, R2 = iPr; 6cis: R1 = Et, R2 = tBu) and trans -1,2-dialkylalkenes (2trans: R1 = Me, R2 = iPr; 3trans: R1 = Me, R2 = tBu; 4trans: R1 = R2 = Et; 5trans: R1 = Et, R2 = iPr; 6trans: R1 = Et, R2 = tBu) by 1 produced the corresponding epoxides, quantitatively and stereospecifically, as the sole observable products. Activation parameters of the epoxidation of the five pairs of alkenes, 2cis,6cis and 2trans,6trans, by 1 were determined using the Arrhenius method. Enhanced selectivity for cis - vs. trans -alkene epoxidation was observed at lower temperatures. In general, the ,G, terms were larger and showed more variability for the reaction of 1 with trans -alkenes as compared to those for the corresponding cis isomers. The ,H, terms mirrored trends observed in ,G, because ,S, terms for all ten of the compounds were roughly identical. The ,,G, values, a comparison of the trans to the cis isomer data, yielded positive values of 1.2 to 1.8 kcal/mol for the five sets of data and appeared to be dependent on relative steric interactions. The experimental activation parameter data, consistent with predictions from ab initio calculations based on a spiro transition-state model, showed that the lower reactivity of trans -alkenes is due to enthalpy factors. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Biophysical characterization of the interaction of Limulus polyphemus endotoxin neutralizing protein with lipopolysaccharide

FEBS JOURNAL, Issue 10 2004
Jörg Andrä
Endotoxin-neutralizing protein (ENP) of the horseshoe crab is one of the most potent neutralizers of endotoxins [bacterial lipopolysaccharide (LPS)]. Here, we report on the interaction of LPS with recombinant ENP using a variety of physical and biological techniques. In biological assays (Limulus amebocyte lysate and tumour necrosis factor-, induction in human mononuclear cells), ENP causes a strong reduction of the immunostimulatory ability of LPS in a dose-dependent manner. Concomitantly, the accessible negative surface charges of LPS and lipid A (zeta potential) are neutralized and even converted into positive values. The gel to liquid crystalline phase transitions of LPS and lipid A shift to higher temperatures indicative of a rigidification of the acyl chains, however, the only slight enhancement of the transition enthalpy indicates that the hydrophobic moiety is not strongly disturbed. The aggregate structure of lipid A is converted from a cubic into a multilamellar phase upon ENP binding, whereas the secondary structure of ENP does not change due to the interaction with LPS. ENP contains a hydrophobic binding site to which the dye 1-anilino-8-sulfonic acid binds at a Kd of 19 µm, which is displaced by LPS. Because lipopolysaccharide-binding protein (LBP) is not able to bind to LPS when ENP and LPS are preincubated, tight binding of ENP to LPS can be deduced with a Kd in the low nonomolar range. Importantly, ENP is able to incorporate by itself into target phospholipid liposomes, and is also able to mediate the intercalation of LPS into the liposomes thus acting as a transport protein in a manner similar to LBP. Thus, LPS,ENP complexes might enter target membranes of immunocompetent cells, but are not able to activate due to the ability of ENP to change LPS aggregates from an active into an inactive form. [source]


Seismic anisotropy of shales

GEOPHYSICAL PROSPECTING, Issue 5 2005
C.M. Sayers
ABSTRACT Shales are a major component of sedimentary basins, and they play a decisive role in fluid flow and seismic-wave propagation because of their low permeability and anisotropic microstructure. Shale anisotropy needs to be quantified to obtain reliable information on reservoir fluid, lithology and pore pressure from seismic data, and to understand time-to-depth conversion errors and non-hyperbolic moveout. A single anisotropy parameter, Thomsen's , parameter, is sufficient to explain the difference between the small-offset normal-moveout velocity and vertical velocity, and to interpret the small-offset AVO response. The sign of this parameter is poorly understood, with both positive and negative values having been reported in the literature. , is sensitive to the compliance of the contact regions between clay particles and to the degree of disorder in the orientation of clay particles. If the ratio of the normal to shear compliance of the contact regions exceeds a critical value, the presence of these regions acts to increase ,, and a change in the sign of ,, from the negative values characteristic of clay minerals to the positive values commonly reported for shales, may occur. Misalignment of the clay particles can also lead to a positive value of ,. For transverse isotropy, the elastic anisotropy parameters can be written in terms of the coefficients W200 and W400 in an expansion of the clay-particle orientation distribution function in generalized Legendre functions. For a given value of W200, decreasing W400 leads to an increase in ,, while for fixed W400, , increases with increasing W200. Perfect alignment of clay particles with normals along the symmetry axis corresponds to the maximum values of W200 and W400, given by and . A comparison of the predictions of the theory with laboratory measurements shows that most shales lie in a region of the (W200, W400)-plane defined by W400/W200,Wmax400/Wmax200. [source]


A conservative 2D model of inundation flow with solute transport over dry bed

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2006
J. Murillo
Abstract In this paper, a transient 2D coupled vertically averaged flow/transport model is presented. The model deals with all kind of bed geometries and guarantees global conservation and positive values of both water level and solute concentration in the transient solution. The model is based on an upwind finite volume method, using Roe's approximate Riemann solver. A specific modification of the Riemann solver is proposed to overcome the generation of negative values of depth and concentration, that can appear as a consequence of existing wetting/drying and solute advance fronts over variable bed levels, or by the generation of new ones when dry areas appear. The numerical stability constraints of the explicit model are stated incorporating the influence of the flow velocity, the bed variations and the possible appearance of dry cells. Faced to the important restriction that this new stability condition can impose on the time step size, a different strategy to allow stability using a maximum time step, and in consequence a minimum computational cost is presented. Copyright © 2006 John Wiley & Sons, Ltd. [source]


The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statistics

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2009
D. Maraun
Abstract The annual cycle of extreme 1-day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges. A generalized extreme-value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year. We average the shape parameter of neighbouring rain gauges to decrease parameter uncertainties, and also interpolate values of all model parameters to give complete coverage of the UK. The model reveals distinct spatial patterns for the estimated parameters. The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks in late summer), and low in the Midlands. The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia. The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK. The shape parameter shows a gradient from positive values in the east to negative values in some areas of the west. We also estimate 10-year and 100-year return levels at each rain gauge, and interpolated across the UK. Copyright © 2008 Royal Meteorological Society [source]


Variability of total and solid precipitation in the Canadian Arctic from 1950 to 1995

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2002
Rajmund Przybylak
Abstract Trends in solid and total precipitation, as well as in the ratio of solid to total precipitation (hereinafter S/T ratio), in the Canadian Arctic in recent decades have been investigated. In addition, the influence of air temperature and circulation factors (atmospheric and oceanic) on the above-mentioned precipitation characteristics have been examined. Recently updated and adjusted data by the Canadian Climate Centre from 16 stations located in the Canadian Arctic and two stations from the sub-Arctic were used for the investigation. The southern boundary of the study area was taken after Atlas Arktiki (Tresjinkov, A. 1985. Glavnoye Upravlenye Geodeziy i Kartografiy: Moscow; 204 pp). The majority of the data cover the period from 1950 to 1995. A statistically significant increase in all kinds of areally averaged seasonal and annual precipitation for the Canadian Arctic over the period 1950,95 has been found. On the other hand, the S/T ratio did not change significantly, except for summer values, and its behaviour was also in accord with small variations noted in air temperature. An increase in air temperature in the Canadian Arctic most often led to a rise in all kinds of annual precipitation sums, but only when the warmest and coldest years were chosen based on individual stations. The pattern of the relationship is significantly more complicated, and can even be opposite to that presented above, when the sets of the warmest and coldest years are chosen based on the areally averaged annual temperature for the Canadian Arctic. Significantly more stable results of changes were found for the S/T ratio, which in warmer periods was usually lower. However, more detailed and reliable investigations of temperature,precipitation relationships conducted for individual stations showed that though the S/T ratio in warmer periods may well be lower, this only applies to the southern (warmer) part of the Canadian Arctic (<70 °N). During periods with high positive values of the North Atlantic Oscillation Index (NAOI), a decrease in precipitation is observed in the south-eastern part of the Canadian Arctic, i.e. in the area where strong cooling was also observed. During El Niño events most of the Canadian Arctic had both greater precipitation and a higher S/T ratio than during La Niña events. The most unequivocal results of precipitation and S/T ratio changes were found for changes in the Arctic Ocean circulation regimes. In almost the whole study area, a lower precipitation and S/T ratio were noted during the anticyclonic circulation regime in the Arctic Ocean. Copyright © 2002 Royal Meteorological Society [source]