Unfavorable

Distribution by Scientific Domains
Distribution within Medical Sciences

Terms modified by Unfavorable

  • unfavorable condition
  • unfavorable effects
  • unfavorable interaction
  • unfavorable outcome
  • unfavorable prognosis
  • unfavorable prognostic factor

  • Selected Abstracts


    The Characteristics and Features of SMEs: Favorable or Unfavorable to Logistics Integration?

    JOURNAL OF SMALL BUSINESS MANAGEMENT, Issue 3 2004
    René Gélinas
    For small and medium-sized enterprises (SMEs), logistics integration is one of the most significant challenges of modern management. Growing numbers of SMEs are under pressure from large manufacturing enterprises (LMEs) to change their traditional management styles, both operationally and organizationally, replacing them with integrated systems that help increase the speed and fluidity of physical and information flows, help synchronize demand with supply, and help manage transactions more accurately. The recent literature discusses integrated logistics chain management quite extensively, but most studies address the issue from the standpoint of large firms. Given the importance of SMEs in the economies of industrialized countries, and given, too, that a constantly growing number of such firms will have to replace their management methods by logistically integrated practices, the authors of this study believe that it is important to examine the characteristics and features of SMEs in order to identify those favorable and unfavorable to logistics integration. [source]


    MANAGEMENT OF THE BILE DUCT STONE: CURRENT SITUATION IN JAPAN

    DIGESTIVE ENDOSCOPY, Issue 2010
    Ichiro Yasuda
    Endoscopic treatment is now recognized as the standard treatment for common bile duct stones worldwide. Endoscopic treatment routinely involves endoscopic sphincterotomy in most countries including Japan and endoscopic papillary balloon dilation is also a widely used alternative to endoscopic sphincterotomy in Japan. Surgery in any form, including laparoscopic surgery, is mainly performed when endoscopic treatments are unsuccessful or unfavorable. Other therapeutic modalities considered under certain circumstances include lithotripsy under the guidance of percutaneous transhepatic cholangioscopy, peroral cholangioscopy, or enteroscopy; electrohydraulic lithotripsy or laser lithotripsy; and extracorporeal shock-wave lithotripsy. [source]


    Effects of vegetation on channel morphodynamics: results and insights from laboratory experiments

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2010
    Michal Tal
    Abstract A series of laboratory experiments demonstrates that riparian vegetation can cause a braided channel to self-organize to, and maintain, a dynamic, single-thread channel. The initial condition for the experiments was steady-state braiding in non-cohesive sand under uniform discharge. From here, an experiment consisted of repeated cycles alternating a short duration high flow with a long duration low flow, and uniform dispersal of alfalfa seeds over the bed at the end of each high flow. Plants established on freshly deposited bars and areas of braidplain that were unoccupied during low flow. The presence of the plants had the effect of progressively focusing the high flow so that a single dominant channel developed. The single-thread channel self-adjusted to carry the high flow. Vegetation also slowed the rate of bank erosion. Matching of deposition along the point bar with erosion along the outer bend enabled the channel to develop sinuosity and migrate laterally while suppressing channel splitting and the creation of new channel width. The experimental channels spontaneously reproduced many of the mechanisms by which natural meandering channels migrate and maintain a single dominant channel, in particular bend growth and channel cutoff. In contrast with the braided system, where channel switching is a nearly continuous process, vegetation maintained a coherent channel until wholesale diversion of flow via cutoff and/or avulsion occurred, by which point the previous channel tended to be highly unfavorable for flow. Thus vegetation discouraged the coexistence of multiple channels. Varying discharge was key to allowing expression of feedbacks between the plants and the flow and promoting the transition from braiding to a single-thread channel that was then dynamically maintained. Copyright © 2010 John Wiley & Sons, Ltd. [source]


    Somatodendritic autoreceptor regulation of serotonergic neurons: dependence on l -tryptophan and tryptophan hydroxylase-activating kinases

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2005
    Rong-Jian Liu
    Abstract The somatodendritic 5-HT1A autoreceptor has been considered a major determinant of the output of the serotonin (5-HT) neuronal system. However, recent studies in brain slices from the dorsal raphe nucleus have questioned the relevance of 5-HT autoinhibition under physiological conditions. In the present study, we found that the difficulty in demonstrating 5-HT tonic autoinhibition in slice results from in vitro conditions that are unfavorable for sustaining 5-HT synthesis. Robust, tonic 5-HT1A autoinhibition can be restored by reinstating in vivo 5-HT synthesizing conditions with the initial 5-HT precursor l -tryptophan and the tryptophan hydroxylase co-factor tetrahydrobiopterin (BH4). The presence of tonic autoinhibition under these conditions was revealed by the disinhibitory effect of a low concentration of the 5-HT1A antagonist WAY 100635. Neurons showing an autoinhibitory response to l -tryptophan were confirmed immunohistochemically to be serotonergic. Once conditions for tonic autoinhibition had been established in raphe slice, we were able to show that 5-HT autoinhibition is critically regulated by the tryptophan hydroxylase-activating kinases calcium/calmodulin protein kinase II (CaMKII) and protein kinase A (PKA). In addition, at physiological concentrations of l -tryptophan, there was an augmentation of 5-HT1A receptor-mediated autoinhibition when the firing of 5-HT cells activated with increasing concentrations of the ,1 adrenoceptor agonist phenylephrine. Increased calcium influx at higher firing rates, by activating tryptophan hydroxylase via CaMKII and PKA, can work together with tryptophan to enhance negative feedback control of the output of the serotonergic system. [source]


    Responses to hedonically conflicting social comparisons: comparing happy and unhappy people

    EUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2001
    Sonja Lyubomirsky
    Two laboratory studies explored how self-rated unhappy and happy students balance hedonically conflicting social comparison information, and tested whether unhappy students would be relatively more sensitive to hedonically consistent unfavorable information. In both studies, students working in teams of four competed against one other team on a novel verbal task. First, unhappy participants showed relatively greater sensitivity to undiluted unfavorable feedback,about group standing (e.g. your team ,lost'; Study 1) and about group and individual standing (e.g. your team lost and you were placed last; Study 2). Second, unhappy students were more reactive than happy students to individual social comparison information in the context of relative group feedback. In Study 1, the moods and self-assessments of unhappy individuals (but not happy ones) after news of team defeat appeared to be buffered by the additional news of personal triumph. In Study 2, unhappy students showed relatively larger decreases in mood and ability assessments after unfavorable than after favorable individual feedback (i.e. ranking last versus first), regardless of whether they additionally learned that their teams had won or lost. The role of students' attributions and perceptions of their personal contribution was also explored. Implications of these findings for the links among social comparison, cognitive processes, and hedonic consequences are discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    DENSITY DEPENDENCE AND COOPERATION: THEORY AND A TEST WITH BACTERIA

    EVOLUTION, Issue 9 2009
    Adin Ross-Gillespie
    Although cooperative systems can persist in nature despite the potential for exploitation by noncooperators, it is often observed that small changes in population demography can tip the balance of selective forces for or against cooperation. Here we consider the role of population density in the context of microbial cooperation. First, we account for conflicting results from recent studies by demonstrating theoretically that: (1) for public goods cooperation, higher densities are relatively unfavorable for cooperation; (2) in contrast, for self-restraint,type cooperation, higher densities can be either favorable or unfavorable for cooperation, depending on the details of the system. We then test our predictions concerning public goods cooperation using strains of the pathogenic bacterium Pseudomonas aeruginosa that produce variable levels of a public good,iron-scavenging siderophore molecules. As predicted, we found that the relative fitness of cheats (under-producers) was greatest at higher population densities. Furthermore, as assumed by theory, we show that this occurs because cheats are better able to exploit the cooperative siderophore production of other cells when they are physically closer to them. [source]


    Effect of the disease-causing mutations identified in human ribonuclease (RNase) H2 on the activities and stabilities of yeast RNase H2 and archaeal RNase HII

    FEBS JOURNAL, Issue 19 2008
    Muhammad S. Rohman
    Eukaryotic ribonuclease (RNase) H2 consists of one catalytic and two accessory subunits. Several single mutations in any one of these subunits of human RNase H2 cause Aicardi,Goutières syndrome. To examine whether these mutations affect the complex stability and activity of RNase H2, three mutant proteins of His-tagged Saccharomyces cerevisiae RNase H2 (Sc-RNase H2*) were constructed. Sc-G42S*, Sc-L52R*, and Sc-K46W* contain single mutations in Sc-Rnh2Ap*, Sc-Rnh2Bp*, and Sc-Rnh2Cp*, respectively. The genes encoding the three subunits were coexpressed in Escherichia coli, and Sc-RNase H2* and its derivatives were purified in a heterotrimeric form. All of these mutant proteins exhibited enzymatic activity. However, only the enzymatic activity of Sc-G42S* was greatly reduced compared to that of the wild-type protein. Gly42 is conserved as Gly10 in Thermococcus kodakareansis RNase HII. To analyze the role of this residue, four mutant proteins, Tk-G10S, Tk-G10A, Tk-G10L, and Tk-G10P, were constructed. All mutant proteins were less stable than the wild-type protein by 2.9,7.6 °C in Tm. A comparison of their enzymatic activities, substrate binding affinities, and CD spectra suggests that the introduction of a bulky side chain into this position induces a local conformational change, which is unfavorable for both activity and substrate binding. These results indicate that Gly10 is required to make the protein fully active and stable. [source]


    Environmental effects on recruitment and productivity of Japanese sardine Sardinops melanostictus and chub mackerel Scomber japonicus with recommendations for management

    FISHERIES OCEANOGRAPHY, Issue 4 2005
    AKIHIKO YATSU
    Abstract We compared a wide range of environmental data with measures of recruitment and stock production for Japanese sardine Sardinops melanostictus and chub mackerel Scomber japonicus to examine factors potentially responsible for fishery regimes (periods of high or low recruitment and productivity). Environmental factors fall into two groups based on principal component analyses. The first principal component group was determined by the Pacific Decadal Oscillation Index and was dominated by variables associated with the Southern Oscillation Index and Kuroshio Sverdrup transport. The second was led by the Arctic Oscillation and dominated by variables associated with Kuroshio geostrophic transport. Instantaneous surplus production rates (ISPR) and log recruitment residuals (LNRR) changed within several years of environmental regime shifts and then stabilized due, we hypothesize, to rapid changes in carrying capacity and relaxation of density dependent effects. Like ISPR, LNRR appears more useful than fluctuation in commercial catch data for identifying the onset of fishery regime shifts. The extended Ricker models indicate spawning stock biomass and sea surface temperatures (SST) affect recruitment of sardine while spawning stock biomass, SST and sardine biomass affect recruitment of chub mackerel. Environmental conditions were favorable for sardine during 1969,87 and unfavorable during 1951,67 and after 1988. There were apparent shifts from favorable to unfavorable conditions for chub mackerel during 1976,77 and 1985,88, and from unfavorable to favorable during 1969,70 and 1988,92. Environmental effects on recruitment and surplus production are important but fishing effects are also influential. For example, chub mackerel may have shifted into a new favorable fishery regime in 1992 if fishing mortality had been lower. We suggest that managers consider to shift fishing effort in response to the changing stock productivity, and protect strong year classes by which we may detect new favorable regimes. [source]


    On the Design of High-Efficiency Thermoelectric Clathrates through a Systematic Cross-Substitution of Framework Elements

    ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010
    Xun Shi
    Abstract Type I clathrates have recently been identified as prospective thermoelectric materials for power generation purposes due to their very low lattice thermal conductivity values. The maximum thermoelectric figure of merit of almost all type I clathrates is, however, less than 1 and occurs at, or above, 1000,K, making them unfavorable especially for intermediate temperature applications. In this report, the Zintl,Klemm rule is demonstrated to be valid for Ni, Cu, and Zn transition metal substitution in the framework of type I clathrates and offers many degrees of freedom for material modification, design, and optimization. The cross-substitution of framework elements introduces ionized impurities and lattice defects into these materials, which optimize the scattering of charge carriers by the substitution-induced ionized impurities and the scattering of heat-carrying lattice phonons by point defects, respectively, leading to an enhanced power factor, reduced lattice thermal conductivity, and therefore improved thermoelectric figure of merit. Most importantly, the bandgap of these materials can be tuned between 0.1 and 0.5,eV by adjusting the cross-substitution ratio of framework elements, making it possible to design clathrates with excellent thermoelectric properties between 500 and 1000,K. [source]


    THE ODYSSEY OF JAPANESE COLONISTS IN THE DOMINICAN REPUBLIC,

    GEOGRAPHICAL REVIEW, Issue 3 2000
    OSCAR H. HORST
    ABSTRACT. In an agreement formalized with the Japanese government in 1956, Generalissimo Rafael Leónidas Trujillo Molina of the Dominican Republic extended an offer of refuge for Japanese immigrants seeking to improve their fortunes in the late 1950s by taking up residence in Trujillo's vaunted "Paradise of the Caribbean." The provision of sites ultimately unfavorable for colonization, lack of infrastructure, failure of the Japanese government to address the complaints of the colonists, and political instability within the Dominican Republic led to the abandonment of five of the eight colonies. By 1962 only 276 of the 1,319 original colonists remained; the rest had either returned to Japan or sought refuge in South America. Although the fortunes of these Japanese families fell far short of their expectations, Trujillo could hardly have envisioned the contributions to Dominican society to be made by their descendants. The experiences of this relatively small number of migrants reflect the difficulties encountered when racial and geopolitical concerns take precedence over judicious plans for colonization. [source]


    Twelve-year course and outcome predictors of anorexia nervosa

    INTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 2 2006
    Dipl-Psych, Manfred M. Fichter MD
    Abstract Objective The current study presents the long-term course of anorexia nervosa (AN) over 12 years in a large sample of 103 patients diagnosed according to criteria in the 4th ed. of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Method Assessments were made at the beginning of therapy, at the end of therapy, at the 2-year follow-up, at the 6-year follow-up, and at the 12-year follow-up. Self-rating and an expert-rating interview data were obtained. Results The participation rate at the 12-year follow-up was 88% of those alive. There was substantial improvement during therapy, a moderate (in many instances nonsignificant) decline during the first 2 years posttreatment, and further improvement from 3 to 12 years posttreatment. Based on a global 12-year outcome score, 27.5% had a good outcome, 25.3% an intermediate outcome, 39.6% had a poor outcome, and 7 (7.7%) were deceased. At the 12-year follow-up 19.0% had AN, 9.5% had bulimia nervosa-purging type (BN-P), 19.0% were classified as eating disorder not otherwise specified (EDNOS). A total of 52.4% showed no major DSM-IV eating disorder and 0% had binge eating disorder (BED). Systematic,strictly empirically based,model building resulted in a parsimonious model including four predictors of unfavorable 12-year outcome explaining 45% of the variance, that is, sexual problems, impulsivity, long duration of inpatient treatment, and long duration of an eating disorder. Conclusion Mortality was high and symptomatic recovery protracted. Impulsivity, symptom severity, and chronicity were the important factors for predicting the 12-year outcome. © 2005 by Wiley Periodicals, Inc. [source]


    Impact of anatomical pielocaliceal topography in the treatment of renal lower calyces stones with extracorporeal shock wave lithotripsy

    INTERNATIONAL JOURNAL OF UROLOGY, Issue 6 2005
    LORENZO RUGGERA
    Abstract Aim:, There is wide consensus that the lowest success rate of extracorporeal shock wave lithotripsy (ESWL) is in the complete clearance of renal stones located in the lower calyces. We assess the effectiveness of extracorporeal shock wave lithotripsy monotherapy for lower pole renal calculi to determine the relationship between the spatial anatomy of lower pole and the outcome of ESWL. Methods:, We evaluated 107 patients who were treated for solitary lower pole renal stones less than 20 mm in diameter with ESWL. The spatial anatomy of the lower pole, as defined by the lower infundibulopelvic angle, infundibular length and infundibular width, was measured by preoperative intravenous pyelography, while the stone location and size were determined by using abdominal plain X-ray. All patients were followed up at 1 and 3 months with abdominal plain X-ray and ultrasonography. Results:, Only 62 patients (58%) became stone free, while 45 (42%) retained residual fragments. A small lower infundibulopelvic angle, a long infundibular length and a tight infundibular width are unfavorable for stone clearance after ESWL. Conclusions:, ESWL is the treatment of choice for most renal and ureteral stones. However, stone clearance from the lower pole following ESWL is poor and significantly affected by the inferior pole collecting system anatomy. Therefore, we believe it is important to evaluate these anatomical factors when deciding on the best treatment for lower pole renal calculi. [source]


    Procedural fairness in ultimatum bargaining: Effects of interactional fairness and formal procedure on respondents' reactions to unequal offers1

    JAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2003
    Mitsuteru Fukuno
    Abstract: Ninety-nine Japanese students received one of three offers in an ultimatum bargaining scenario: unfavorable and unequal; equal; or favorable but unequal. These offers were determined by either the other participant or by a computerized lottery. We also manipulated the arbitrariness of the role assignment procedure. Participants perceived the intentional small offer as more unfair in the interactional sense than the unintentional small offer, while they perceived the same offers as unfair in the distributive sense, regardless of intentionality. The intentional small offer was more likely to be rejected than the unintentional small offer. Participants perceived the arbitrary procedure of the role assignment as highly unfair, whereas the difference of arbitrariness in role assignment procedures had no significant impact on their reactions to the offer. Acceptance of the offer was strongly determined by interactional fairness, as well as by distributive fairness, and these types of fairness were influenced by different situational characteristics, such as intentionality, the size of the offer, and the equality of the offer. [source]


    Assessment and Interpretation of Comorbidity Burden in Older Adults with Cancer

    JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2009
    Siran M. Koroukian PhD
    OBJECTIVES: To evaluate the associations between comorbidities, functional limitations, geriatric syndromes, treatment patterns, and outcomes in a population-based cohort of older patients diagnosed with colorectal cancer and receiving home health care. DESIGN: Retrospective study. SETTING: Data from the Ohio Cancer Incidence Surveillance System, Medicare claims and enrollment files, and the home health care Outcome and Assessment Information Set. PARTICIPANTS: Ohio residents diagnosed with incident colorectal cancer in 1999 to 2001 and receiving home health care in the 30 days before or after cancer diagnosis (N=957). MEASUREMENTS: Outcome measures included receipt of cancer treatment and survival through 2005. RESULTS: Not having surgery was associated negatively with comorbidities but positively with functional limitations and geriatric syndromes. Receipt of chemotherapy was negatively associated with comorbidities and functional limitations. The presence of two or more geriatric syndromes was significantly associated with unfavorable survival outcomes when analyzing overall survival and disease-specific survival (DSS). Having limitations in two or more activities of daily living was associated with unfavorable overall survival but not with DSS. Comorbity was associated with favorable DSS at borderline level of statistical significance but not with overall survival. CONCLUSION: The findings highlight the importance of incorporating functional limitations and geriatric syndrome data in geriatric oncology outcomes studies. [source]


    Thermal stability and ablation properties of silicone rubber composites

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008
    Eung Soo Kim
    Abstract Effects of incorporation of clay and carbon fiber (CF) into a high temperature vulcanized (HTV) silicone rubber, i.e., poly(dimethylsiloxane) (PDMS) containing vinyl groups, on its thermal stability and ablation properties were explored through thermogravimetric analyses (TGA) and oxy-acetylene torch tests. Natural clay, sodium montmorillonite (MMT), was modified with a silane compound bearing tetra sulfide (TS) groups to prepare MMTS4: the TS groups may react with the vinyl groups of HTV and enhance the interfacial interaction between the clay and HTV. MMTS4 layers were better dispersed than MMT layers in the respective composites with exfoliated/intercalated coexisting morphology. According to TGA results and to the insulation index, the HTV/MMTS4 composite was more thermally stable than HTV/MMT. However, addition of CF to the composites lowered their thermal stability, because of the high thermal conductivity of CF. The time elapsed for the composite specimen, loaded with a constant weight, to break off after the oxy-acetylene flame bursts onto the surface of the specimen was employed as an index for an integrated assessment of the ablation properties, simultaneously taking into consideration the mechanical strength of the char and the rate of decomposition. The elapsed time increased in the order of: HTV < HTV/CF , HTV/MMTS4 < HTV/CF/MMTS4 , HTV/MMT < HTV/CF/MMT. This order was different from the increasing order of the thermal stability determined by TGA results and the insulation index. The decreased degree of crosslinking of the composites with MMTS4 compared with that of the composite with MMT may be unfavorable for the formation of a mechanically strong char and could lead to early rupture of the HTV/MMTS4 specimen. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


    Double-prodrugs of L -cysteine: Differential protection against acetaminophen-induced hepatotoxicity in mice

    JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2002
    Daune L. Crankshaw
    Abstract A series of double-prodrugs of L -cysteine, designed to release L -cysteine in vivo and stimulate the biosynthesis of glutathione (GSH), were synthesized. To evaluate the hepatoprotective effectiveness of these double-prodrugs, male Swiss-Webster mice were administered acetaminophen (ACP) (2.45 mmol/kg (360 mg/kg), intraperitoneally (i.p.)). Prodrug (2.50 mmol/kg, i.p. or 1.25 mmol/kg, i.p., depending on the protocol) was administered 1 h before ACP as a priming dose. A supplementary dose of prodrug (2.5 mmol/kg, i.p. or 1.25 mmol/kg, i.p. depending on the protocol) was administered 0.5 h after ACP. The plasma alanine amino transferase (ALT) values, 24 h after ACP administration were transformed to logs and the 95% and 99% confidence intervals of the log values were plotted and compared for each group. Hepatoprotection was assessed by the degree of attenuation of plasma ALT levels. With these multiple dose schedules, the use of 2% carboxymethylcellulose as vehicle for the prodrugs was found to be detrimental; therefore, the prodrugs were dissolved in dilute aqueous base and the pH adjusted for administration. When a priming dose was given 1 h before ACP followed by a supplementary dose 0.5 h after ACP, only N,S -bis-acetyl- L -cysteine, where both the sulfhydryl and amino groups of L -cysteine were functionalized with the acetyl group, was found to be effective in protecting mice against the hepatotoxic effects of ACP. This suggests that these acetyl groups were rapidly hydrolyzed in vivo to liberate L -cysteine. In contrast, N -acetylation of 2(R,S)-methylthiazolidine-4(R)-carboxylic acid (MTCA) and its 2- n -propyl analog (PTCA), or N -acetylation of 2-oxothiazolidine-4-carboxylic acid (OTCA), reduced the hepatoprotective effects relative to the parent MTCA, PTCA, and OTCA, indicating that the release of L -cysteine in vivo from these N -acetylated thiazolidine prodrugs was metabolically unfavorable. The carbethoxy group, whether functionalized on the sulfhydryl or on the amino group of L -cysteine, or on the secondary amino group of MTCA, appears to be a poor "pro-moiety," since these carbethoxylated double-prodrugs of L -cysteine did not protect mice from ACP-induced hepatotoxicity. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:235,244, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10044 [source]


    Molecular dynamics simulations of the detoxification of paraoxon catalyzed by phosphotriesterase

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2009
    Xin Zhang
    Abstract Combined QM(PM3)/MM molecular dynamics simulations together with QM(DFT)/MM optimizations for key configurations have been performed to elucidate the enzymatic catalysis mechanism on the detoxification of paraoxon by phosphotriesterase (PTE). In the simulations, the PM3 parameters for the phosphorous atom were reoptimized. The equilibrated configuration of the enzyme/substrate complex showed that paraoxon can strongly bind to the more solvent-exposed metal ion Zn,, but the free energy profile along the binding path demonstrated that the binding is thermodynamically unfavorable. This explains why the crystal structures of PTE with substrate analogues often exhibit long distances between the phosphoral oxygen and Zn,. The subsequent SN2 reaction plays the key role in the whole process, but controversies exist over the identity of the nucleophilic species, which could be either a hydroxide ion terminally coordinated to Zn, or the ,-hydroxo bridge between the ,- and ,-metals. Our simulations supported the latter and showed that the rate-limiting step is the distortion of the bound paraoxon to approach the bridging hydroxide. After this preparation step, the bridging hydroxide ion attacks the phosphorous center and replaces the diethyl phosphate with a low barrier. Thus, a plausible way to engineer PTE with enhanced catalytic activity is to stabilize the deformed paraoxon. Conformational analyses indicate that Trp131 is the closest residue to the phosphoryl oxygen, and mutations to Arg or Gln or even Lys, which can shorten the hydrogen bond distance with the phosphoryl oxygen, could potentially lead to a mutant with enhanced activity for the detoxification of organophosphates. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source]


    Stability of carbon-centered radicals: Effect of functional groups on the energetics of addition of molecular oxygen

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2009
    James S. Wright
    Abstract In this paper we examine a series of hydrocarbons with structural features which cause a weakening of the CH bond. We use theoretical calculations to explore whether the carbon-centered radicals R, which are created after breaking the bond can be stabilized enough so that they resist the addition of molecular oxygen, i.e. where the reaction R, + O2 , ROO, becomes energetically unfavorable. Calculations using a B3LYP-based method provide accurate bond dissociation enthalpies (BDEs) for RH and ROO, bonds, as well as Gibbs free energy changes for the addition reaction. The data show strong correlations between ROO, and RH BDEs for a wide variety of structures. They also show an equally strong correlation between the ROO, BDE and the unpaired spin density at the site of addition. Using these data we examine the major functional group categories proposed in several experimental studies, and assess their relative importance. Finally, we combine effects to try to optimize resistance to the addition of molecular oxygen, an important factor in designing carbon-based antioxidants. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009 [source]


    A comprehensive theoretical study on the hydrolysis of carbonyl sulfide in the neutral water

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2008
    Chao Deng
    Abstract The detailed hydration mechanism of carbonyl sulfide (COS) in the presence of up to five water molecules has been investigated at the level of HF and MP2 with the basis set of 6-311++G(d, p). The nucleophilic addition of water molecule occurs in a concerted way across the CS bond of COS rather than across the CO bond. This preferential reaction mechanism could be rationalized in terms of Fukui functions for the both nucleophilic and electrophilic attacks. The activation barriers, ,H, for the rate-determining steps of one up to five-water hydrolyses of COS across the CS bond are 199.4, 144.4, 123.0, 115.5, and 107.9 kJ/mol in the gas phase, respectively. The most favorable hydrolysis path of COS involves a sort of eight-membered ring transition structure and other two water molecules near to the nonreactive oxygen atom but not involved in the proton transfer, suggesting that the hydrolysis of COS can be significantly mediated by the water molecule(s) and the cooperative effects of the water molecule(s) in the nonreactive region. The catalytic effect of water molecule(s) due to the alleviation of ring strain in the proton transfer process may result from the synergistic effects of rehybridization and charge reorganization from the precoordination complex to the rate-determining transition state structure induced by water molecule. The studies on the effect of temperature on the hydrolysis of COS show that the higher temperature is unfavorable for the hydrolysis of COS. PCM solvation models almost do not modify the calculated energy barriers in a significant way. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source]


    Coarse-graining of protein structures for the normal mode studies

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2007
    Kilho Eom
    Abstract The coarse-grained structural model such as Gaussian network has played a vital role in the normal mode studies for understanding protein dynamics related to biological functions. However, for the large proteins, the Gaussian network model is computationally unfavorable for diagonalization of Hessian (stiffness) matrix for the normal mode studies. In this article, we provide the coarse-graining method, referred to as "dynamic model condensation," which enables the further coarse-graining of protein structures consisting of small number of residues. It is shown that the coarser-grained structures reconstructed by dynamic model condensation exhibit the dynamic characteristics, such as low-frequency normal modes, qualitatively comparable to original structures. This sheds light on that dynamic model condensation and may enable one to study the large protein dynamics for gaining insight into biological functions of proteins. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source]


    The Role of Debt Purchases in Takeovers: A Tale of Two Retailers

    JOURNAL OF ECONOMICS & MANAGEMENT STRATEGY, Issue 3 2006
    Thomas H. Noe
    In this paper, we examine acquisitions of two financially distressed retailers,Federated's takeover of Macy's, and Zell Chilmark's takeover of Carter Hawley Hale. In both cases the raider purchased some of the target's outstanding debt to launch its takeover attempt. These debt purchases appear to have been facilitated by two salient factors,the raider's expertise in dealing with distressed firm restructuring and the ability of the raider to acquire a large blockholding of debt. Our analysis indicates that, when these factors are present, it is optimal for a raider to initiate a takeover of a distressed firm through purchasing a block of the firm's debt. Target bondholder reaction will be favorable whereas shareholder reaction may be either favorable or unfavorable. [source]


    Baseline Computed Tomography Changes and Clinical Outcome After Thrombolysis With Recombinant Tissue Plasminogen Activator in Acute Ischemic Stroke

    JOURNAL OF NEUROIMAGING, Issue 2 2001
    Jorge E. Mendizabal MD
    ABSTRACT Objective. Intravenous recombinant tissue plasminogen activator (rt-PA) is the only therapy of proven value for patients with acute ischemic stroke (AIS). Controversy exists with regard to the prognostic significance of early computed tomography (CT) changes in patients receiving rt-PA for AIS. The authors retrospectively reviewed all cases of AIS who received intravenous rt-PA for AIS in University of South Alabama hospitals between January 1996 and May 1999. A neuroradiologist, blinded to clinical outcomes, reviewed all baseline CT scans for the presence of the following signs: hyperdense middle cerebral artery (HMCA), loss of gray-white differentiation (LGWD), insular ribbon sign (IRS), parenchymal hypodensity (PH), and sulcal effacement (SE). Modified Rankin Scale (mRS) score was recorded 90 days after thrombolysis, and clinical outcome was dichotomized as favorable (0,1) or unfavorable (2,6). The authors performed both univariate and multivariate analyses to investigate the relationship between early CT signs, baseline clinical variables, and functional outcome as measured by the 90-day mRS scores. Any one early CT finding was detected in 23 (64%) patients. The frequency of specific findings were as follows: SE in 13 patients (36%), LGWD in 12 patients (33%), PH in 9 patients (25%), HMCA in 4 patients (11%), and IRS in 3 patients (8%) patients. There was no statistically significant association between the occurrence of these imaging findings and subsequent functional outcome after thrombolysis. The data suggest that the presence of subtle acute CT changes in AIS patients is not predictive of clinical outcome following administration of rt-PA as per National Institute of Neurological Disorders and Stroke protocol. [source]


    Collagen-like triple helix formation of synthetic (Pro-Pro-Gly)10 analogues: (4(S)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10, (4(R)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10 and (4(S)-fluoroprolyl-4(R)-fluoroprolyl-Gly)10

    JOURNAL OF PEPTIDE SCIENCE, Issue 10 2005
    Masamitsu Doi
    Abstract For the rational design of a stable collagen triple helix according to the conventional rule that the pyrrolidine puckerings of Pro, 4-hydroxyproline (Hyp) and 4-fluoroproline (fPro) should be down at the X-position and up at the Y-position in the X-Y-Gly repeated sequence for enhancing the triple helix propensities of collagen model peptides, a series of peptides were prepared in which X- and Y-positions were altogether occupied by HypR, HypS, fProR or fProS. Contrary to our presumption that inducing the X-Y residues to adopt a down-up conformation would result in an increase in the thermal stability of peptides, the triple helices of (HypS -HypR -Gly)10 and (fProS -fProR -Gly)10 were less stable than those of (Pro-HypR -Gly)10 and (Pro-fProR -Gly)10, respectively. As reported by Bächinger's and Zagari's groups, (HypR -HypR -Gly)10 which could have an up-up conformation unfavorable for the triple helix, formed a triple helix that has a high thermal stability close to that of (Pro-HypR -Gly)10. These results clearly show that the empirical rule based on the conformational preference of pyrrolidine ring at each of X and Y residues should not be regarded as still valid, at least for predicting the stability of collagen models in which both X and Y residues have electronegative groups at the 4-position. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source]


    HOST PARASITE INTERACTIONS BETWEEN FRESHWATER PHYTOPLANKTON AND CHYTRID FUNGI (CHYTRIDIOMYCOTA),

    JOURNAL OF PHYCOLOGY, Issue 3 2004
    Bas W. Ibelings
    Some chytrids are host-specific parasiticfungithat may have a considerable impact on phytoplankton dynamics. The phylum Chytridiomycota contains one class, the Chytridiomycetes, and is composed of five different orders. Molecular studies now firmly place the Chytridiomycota within the fungal kingdom. Chytrids are characterized by having zoospores, a motile stage in their life cycle. Zoospores are attracted to the host cell by specific signals. No single physical,chemical factor has been found that fully explains the dynamics of chytrid epidemics in the field. Fungal periodicity was primarily related to host cell density. The absence of aggregated distributions of chytrids on their hosts suggested that their hosts did not vary in their susceptibility to infection. A parasite can only become epidemic when it grows faster than the host. Therefore, it has been suggested that epidemics in phytoplankton populations arise when growth conditions for the host are unfavorable. No support for such a generalization was found, however. Growth of the parasitic fungus Rhizophydium planktonicum Canter emend, parasitic on the diatom Asterionella formosa Hassal, was reduced under stringent nutrient limitation,because production and infectivity of zoospores were affected negatively. A moderate phosphorous or light limitation favored epidemic development, however. Chytrid infections have been shown to affect competition between their algal hosts and in this way altered phytoplankton succession. There is potential for coevolution between Asterionella and the chytrid Zygorhizidium planktonicum Canter based on clear reciprocal fitness costs, absence of overall infective parasite strains, and possibly a genetic basis for host susceptibility and parasite infectivity. [source]


    Insurance, Bond Covenants, and Under- or Over-investment With Risky Asset Reconstitution

    JOURNAL OF RISK AND INSURANCE, Issue 1 2007
    Arthur HauArticle first published online: 8 MAR 200
    Traditional theory predicts that the shareholders of a limited liability company financed partly by bonds may underinvest by not replacing damaged company assets. It also precludes the possibility of overinvestment. By relaxing the restrictive assumption maintained under traditional theory, namely, that the effects of reconstituting damaged assets are nonstochastic, this article shows that both over and underinvestment are possible. It is shown that these moral hazard problems can be mitigated by incorporating appropriate insurance requirements into bond covenants. Moreover, it is shown that the insurance requirements for alleviating underinvestment and overinvestment are quite different. Particularly, for underinvestment, the required insurance only needs to make the bonds riskless in the best asset reconstitution states of the loss states in which the company value falls short of the promised bond repayment; however, for overinvestment, the required insurance should make the bonds totally riskless. The difference in insurance requirements is especially important when insurance is actuarially unfavorable such that more-than-required insurance is always undesirable. [source]


    The Characteristics and Features of SMEs: Favorable or Unfavorable to Logistics Integration?

    JOURNAL OF SMALL BUSINESS MANAGEMENT, Issue 3 2004
    René Gélinas
    For small and medium-sized enterprises (SMEs), logistics integration is one of the most significant challenges of modern management. Growing numbers of SMEs are under pressure from large manufacturing enterprises (LMEs) to change their traditional management styles, both operationally and organizationally, replacing them with integrated systems that help increase the speed and fluidity of physical and information flows, help synchronize demand with supply, and help manage transactions more accurately. The recent literature discusses integrated logistics chain management quite extensively, but most studies address the issue from the standpoint of large firms. Given the importance of SMEs in the economies of industrialized countries, and given, too, that a constantly growing number of such firms will have to replace their management methods by logistically integrated practices, the authors of this study believe that it is important to examine the characteristics and features of SMEs in order to identify those favorable and unfavorable to logistics integration. [source]


    A Social Proximity Explanation of the Reluctance to Assimilate

    KYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 1 2007
    C. Simon Fan
    SUMMARY The pursuit of migration is an extreme example of the severing of ties with, or a distancing from, one's friends and home. The ,failure' of migrants to assimilate cannot plausibly be attributed merely to an urge to stay close to their friends, or they might not have migrated to begin with. Non-assimilation arises from a fear of enhanced relative deprivation if they reduce their distance from the natives as a reference group. Fundamentally, migration is a change of those with whom people associate. But it would be wrong to infer that a change of associates crowds out a change of behavior, given the associates. Through their actions, migrants can elect to associate more with some groups, less with others. However, when actions to keep in check the weight accorded to the rich natives as a reference group are not viable, the very choice of migration destination could be affected in an unexpected way: a country that is not so rich could be preferable to a country that is rich; migrants will protect themselves from an unfavorable comparison by not migrating to where the comparison, when unavoidable, would be highly unfavorable. Relatedly, the variance in the assimilation effort of migrants across host countries could arise from the variance in the income distance with the natives: the richer the natives, the weaker the effort to assimilate, other things held the same. [source]


    Ordering in Stretched Bernoullian Copolymers

    MACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2003
    Arkady D. Litmanovich
    Abstract A new approach is suggested to estimate the theoretical maximum capability to order for stretched Bernoullian copolymers AB, provided interchain AB contacts are unfavorable. A simple Monte Carlo procedure simulating the ordering of such copolymers via rotation of ring-shaped chains reveals the capability to order even for quite long copolymer chains. The analytical probabilistic consideration is elaborated, which enables one to interpret the ordering via rotation in terms of a sliding of periodic Bernoullian chains. Using both the probabilistic analysis and Monte Carlo simulations it is shown that estimations of a capability to order given by the rotation procedure are also good for a sliding of true Bernoullian copolymers. Therefore, the simple Monte Carlo procedure seems suitable for estimating ordering in other classes of copolymers for which an analytical approach is more complicated. Such estimations might be useful for a consideration of various properties of irregular copolymers connected with their tendency to order. Ordering by rotation of rings. As an example, an ordering for M,=,10,000 chains of length N,=,20 and composition p,=,0.50 (p is the mole fraction of A units) is shown. See text. [source]


    Prognostic implications of ezrin expression in human hepatocellular carcinoma

    MOLECULAR CARCINOGENESIS, Issue 9 2010
    Yun Kyung Kang
    Abstract Ezrin is known to regulate cellular survival, adhesion, migration, and invasion and has been identified as one of the key components of tumor progression and metastasis. The authors investigated ezrin expression in human hepatocellular carcinoma (HCC) and sought to determine its relation with clinicopathologic parameters, patients' outcome, and interacting molecular markers. Ezrin expression was assessed by immunohistochemical staining in 100 surgically resected HCCs using the tissue microarray method. A total of 28 HCCs showed high ezrin immunoreactivity, mainly in cytoplasm. Ezrin expression exhibited a positive correlation with c-Met expression (P,=,0.001), but showed no correlation with the expression of CD44s or E-cadherin. HCCs expressing high level of ezrin were significantly associated with advanced TNM stage, poor Edmondson's histological grade, macroscopic portal vein invasion, tumor recurrence, and extrahepatic recurrence (P,<,0.05). Univariate analysis showed that HCCs with high ezrin immunoreactivity were strongly associated with unfavorable overall and disease-free survivals than HCCs with low or negative for ezrin immunoreactivity (P,=,0.0001 and 0.0011, respectively). Furthermore, multivariate analysis demonstrated that a high level of ezrin expression was independently associated with poor overall survival (hazard ratio, 1.905; P,=,0.011). The results suggest that ezrin expression could be a potential predictive marker of progression, metastasis, and prognosis in HCC. © 2010 Wiley-Liss, Inc. [source]


    Ethics in Twain's Connecticut Yankee1

    ORBIS LITERARUM, Issue 2 2006
    Bong Eun Kim
    Despite his frequent utterances in favor of Native Americans, Twain has been interpreted as generally unfavorable to them. However, Emmanuel Levinas's concept of the ,ethical encounter with the absolute other' in ,Is ontology fundamental?' illuminates Twain's affirmative ethics towards Native Americans in his novel A Connecticut Yankee in King Arthur's Court (1889). The comparison of Twain's novel with the Native Alaskan Harold Napoleon's Yuuyaraq: The Way of the Human Being (1996), an autobiographical report on the extermination of Alaskan aboriginals and their culture, demonstrates that Twain's British Arthurian fantasy embodies his postcolonial indictment for the massacre of Native Americans. The Chippewa/Ojibway Anishinaabe critic Gerald Vizenor's new code ,postindian' in Manifest Manners: Narratives on Postindian Survivance (1994) exposes the latent postindian aspect of Twain's discourse. Levinas's ethics and the late twentieth-century Native American texts disclose the ethical prevision implied in Twain's time travelogue. Deconstructing the typological Canaan myth, Twain implies that Native Americans should have been encountered in terms of the absolute other and thus problematizes his forefathers' colonial zeal to exterminate Native Americans and assimilate Native American survivors. [source]