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Hoc
Kinds of Hoc Terms modified by Hoc Selected AbstractsAdsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Peng Wang Abstract The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton® X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (Kow) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment. [source] Hydrogen Bonding of Fluorinated Saccharides in Solution: F Acting as H-Bond Acceptor in a Bifurcated H-Bond of 4-Fluorinated Levoglucosans,HELVETICA CHIMICA ACTA, Issue 10 2007Bruno Bernet Abstract 4-Fluorinated levoglucosans were synthesised to test if OH,,,F H-bonds are feasible even when the O,,,F distance is increased. The fluorinated 1,6-anhydro- , - D -glucopyranoses were synthesised from 1,6,:,3,4-dianhydro- , - D -galactopyranose (8). Treatment of 8 with KHF2 and KF gave 43% of 4-deoxy-4-fluorolevoglucosan (9), which was transformed into the 3- O -protected derivatives 13 by silylation and 15 by silylation, acetylation, and desilylation. 4-Deoxy-4-methyllevoglucosan (19) and 4-deoxylevoglucosan (21) were prepared as reference compounds that can only form a bivalent H-bond from HOC(2) to OC(5). They were synthesised from the iPr3Si-protected derivative of 8. Intramolecular bifurcated H-bonds from HOC(2) to FC(4) and OC(5) of the 4-fluorinated levoglucosans in CDCl3 solution are evidenced by the 1H-NMR scalar couplings h1J(F,OH) and 3J(H,OH). The OH,,,F H-bond over an O,,,F distance of ca. 3.0,Ĺ is thus formed in apolar solvents, at least when favoured by the simultaneous formation of an OH,,,O H-bond. [source] Oligonucleotide Analogues with Integrated Bases and Backbone.HELVETICA CHIMICA ACTA, Issue 12 2006Abstract The self-complementary UA and AU dinucleotide analogues 41,45, 47, 48, and 51,60 were prepared by Sonogashira coupling of 6-iodouridines with C(5,) -ethynylated adenosines and of 8-iodoadenosines with C(5,) -ethynylated uridines. The dinucleotide analogues associate in CDCl3 solution. The C(6/I) -unsubstituted AU dimers 51 and 54 prefer an anti -oriented uracilyl group and form stretched linear duplexes. The UA propargyl alcohols 41 and 43,45 possess a persistent intramolecular O(5,/I)H,,,N(3/I) H-bond and, thus, a syn -oriented adeninyl and a gt - or tg -oriented ethynyl moiety; they form corrugated linear duplexes. All other dimers form cyclic duplexes characterized by syn -oriented nucleobases. The preferred orientation of the ethynyl moiety (the C(4,),C(5,) torsion angle) defines a conformation between gg and one where the ethynyl group eclipses O(4,/I). The UA dimers 42, 47, and 48 form Watson,Crick H-bonds, the AU dimers 56 and 58,60 H-bonds of the Watson,Crick -type, the AU dimers 53 and 55 reverse- Hoogsteen, and 57Hoogsteen H-bonds. The pairing mode depends on the substituent of C(5,/I) (H, OSiiPr3; OH) and on the H-bonds of HOC(5,/I) in the AU dimers. Association constants were derived from the concentration-dependent chemical shift for HN(3) of the uracilyl moiety; they vary from 45,104,M,1 for linear duplexes to 197,2307,M,1 for cyclic duplexes. The thermodynamic parameters were determined by van't Hoff analysis of the temperature-dependence of the (concentration-dependent) chemical shift for HN(3) of the uracilyl moiety. Neglecting stacking energies, one finds an average energy of 3.5,4.0,kcal/mol per intermolecular H-bond. Base stacking is evidenced by the temperature-dependent CD spectra. The crystal structure of 54 shows two antiparallel chains of dimers connected by Watson-Crick H-bonds. The chains are bridged by a strong H-bond between the propargylic OH and OC(4) and by weak reverse A,,,A Hoogsteen H-bonds. [source] A hybrid Padé ADI scheme of higher-order for convection,diffusion problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2010Samir KaraaArticle first published online: 8 SEP 200 Abstract A high-order Padé alternating direction implicit (ADI) scheme is proposed for solving unsteady convection,diffusion problems. The scheme employs standard high-order Padé approximations for spatial first and second derivatives in the convection-diffusion equation. Linear multistep (LM) methods combined with the approximate factorization introduced by Beam and Warming (J. Comput. Phys. 1976; 22: 87,110) are applied for the time integration. The approximate factorization imposes a second-order temporal accuracy limitation on the ADI scheme independent of the accuracy of the LM method chosen for the time integration. To achieve a higher-order temporal accuracy, we introduce a correction term that reduces the splitting error. The resulting scheme is carried out by repeatedly solving a series of pentadiagonal linear systems producing a computationally cost effective solver. The effects of the approximate factorization and the correction term on the stability of the scheme are examined. A modified wave number analysis is performed to examine the dispersive and dissipative properties of the scheme. In contrast to the HOC-based schemes in which the phase and amplitude characteristics of a solution are altered by the variation of cell Reynolds number, the present scheme retains the characteristics of the modified wave numbers for spatial derivatives regardless of the magnitude of cell Reynolds number. The superiority of the proposed scheme compared with other high-order ADI schemes for solving unsteady convection-diffusion problems is discussed. A comparison of different time discretizations based on LM methods is given. Copyright © 2009 John Wiley & Sons, Ltd. [source] A class of higher order compact schemes for the unsteady two-dimensional convection,diffusion equation with variable convection coefficientsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2002Jiten C. Kalita Abstract A class of higher order compact (HOC) schemes has been developed with weighted time discretization for the two-dimensional unsteady convection,diffusion equation with variable convection coefficients. The schemes are second or lower order accurate in time depending on the choice of the weighted average parameter , and fourth order accurate in space. For 0.5,,,1, the schemes are unconditionally stable. Unlike usual HOC schemes, these schemes are capable of using a grid aspect ratio other than unity. They efficiently capture both transient and steady solutions of linear and nonlinear convection,diffusion equations with Dirichlet as well as Neumann boundary condition. They are applied to one linear convection,diffusion problem and three flows of varying complexities governed by the two-dimensional incompressible Navier,Stokes equations. Results obtained are in excellent agreement with analytical and established numerical results. Overall the schemes are found to be robust, efficient and accurate. Copyright © 2002 John Wiley & Sons, Ltd. [source] Sorption of HOC in soils with carbonaceous contamination: Influence of organic-matter compositionJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2005Kerstin Abelmann Abstract Detailed information about structure and composition of organic sorbents is required to understand their impact on sorption capacity and sorption kinetic of organic pollutants. Therefore, the chemical composition of organic material from 18 geosorbents was investigated by solid-state 13C nuclear-magnetic-resonance (NMR) spectroscopy. Structural parameters such as aromaticity, polarity, and alkyl-C content were related to the Freundlich sorption exponent (1/n) and the sorption coefficient . The geosorbents included three natural and four combusted coals (carbonaceous material), three Histosols, five mineral soils from Germany containing inputs of technogenic carbonaceous material, derived from industrial activities, and four non-contaminated mineral soils from Germany. Equilibrium sorption was measured for five hydrophobic organic compounds and analyzed with the solubility-normalized Freundlich sorption isotherm. With increasing maturation degree, the proportion of polar constituents decreases from the natural soils to the coals. In contrast to the non-polluted mineral soils, the soils with technogenic input are characterized by high aromaticity and low polarity. A positive correlation between sorption coefficient and aromaticity was found. The Freundlich exponent (1/n) is negatively correlated with the aromaticity, denoting an increase of adsorption processes with increasing aromaticity. Likewise, the contribution of partitioning decreases. This sorption mechanism predominates only if the organic matter in the samples contains a high proportion of polar compounds. Sorption von HOC in Böden mit kohleartiger Kontamination: Einfluss der Zusammensetzung des organischen Materials Um den Einfluss von organischen Sorbenten auf die Sorptionskapazität und die Kinetik organischer Schadstoffe zu verstehen, müssen detaillierte Informationen über deren Struktur und Zusammensetzung vorliegen. Aus diesem Grund wurde das organische Material von 18 Geosorbenten mittels der Festkörper- 13C-NMR-Spektroskopie untersucht. Strukturelle Parameter wie zum Beispiel die Aromatizität, die Polarität und der Alkyl-C-Gehalt wurden mit dem Freundlich-Exponenten 1/n und dem Sorptionskoeffizienten korreliert. Die Geosorbenten bestehen aus drei natürlichen und vier thermisch behandelten Kohlen, drei Histosolen und fünf deutschen Mineralböden, die technogenes kohlehaltiges Material aus industriellen Aktivitäten enthalten, sowie vier nicht kontaminierten deutschen Böden. Die Gleichgewichtssorption wurde für fünf hydrophobe, organische Verbindungen gemessen und mit Hilfe der löslichkeitsnormalisierten Freundlich-Isotherme analysiert. Der Anteil der polaren Komponenten nimmt von den natürlichen Böden zu den Kohlen mit zunehmendem Inkohlungsstadium ab. Im Gegensatz zu den nicht kontaminierten Mineralböden weisen die Böden mit technogenen Bestandteilen eine hohe Aromatizität und eine geringe Polarität auf. Zwischen dem und der Aromatizität ergab sich ein positiver Zusammenhang. Der Freundlich Exponent (1/n) korreliert negativ mit der Aromatizität. Dies weist auf eine Zunahme der Adsorptionsprozesse mit Erhöhung der Aromatizität hin. Der Beitrag der Partitionierung sinkt ebenfalls. Dieser Sorptionsmechanismus dominiert nur in den Proben, in denen das organische Material einen hohen Anteil polarer Bestandteile besitzt. [source] An efficient HOC scheme for transient convection-diffusion-reaction equations with discontinuous coefficients and singular source termsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2007Rajendra K Ray In this paper, we propose a new methodology for numerically solving one-dimensional (1D) transient convection-diffusion-reaction equations with discontinuous coefficients and singular source terms on nonuniform space grids. This Higher Order Compact (HOC) formulation is at least third order accurate at regular grid points and exactly third order accurate at points just next to the discontinuity. We conduct numerous numerical studies on a number of problems and compare our results with those obtained with immersed interface and other well-known methods. In all cases our formulation is found to produce better results on relatively coarser grids. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and Characterization of Tris(,-ketoiminato)ruthenium(III) Complexes: Potential Precursors for CVD of Ru and RuO2 Thin Films,CHEMICAL VAPOR DEPOSITION, Issue 3 2004T.-Y. Chou Abstract The synthesis and characterization of RuIII metal complexes [Ru(keim1)3] (1) and [Ru(keim2)3] (2) are reported, where (keim)H is an abbreviation for the fluorinated ketoimine ligands with formula HOC(CF3)=CHCR=NMe; (keim1)H with R,=,Me and (keim2)H with R,=,CF3. These newly synthesized complexes were characterized by spectroscopic methods, while the second complex, 2, was further examined by single-crystal X-ray diffraction (XRD), revealing an octahedral coordination for the Ru cation, with three ketoiminate arranged in a mer -configuration, a consequence of the enhanced steric interaction between ligands. Moreover, both Ru metal complexes show good volatility and thermal stability. CVD experiments were conducted using these complexes at temperatures of 325,450,°C. The Ru metal and RuO2 thin films on silicon wafers were successfully obtained using either a mixture of 2,% O2 in argon or pure O2 as the carrier gas, respectively. Our result shows that a 2,% O2 concentration induces the formation of Ru metal, while that only complex 1 gives formation of a columnar RuO2 phase upon switching to pure O2 as the CVD carrier gas. Scanning electron microscopy (SEM) images were taken to reveal surface morphologies, while X-ray photoelectron spectroscopy (XPS) and XRD were utilized to access their atomic composition as well as the intrinsic packing of the as-deposited thin film materials. [source] ChemInform Abstract: New or Improved Syntheses of the Polyfluoroalcohols HOC(cyclo-C6H11)2(CF3), HO(cyclo-C6H11)(CF3)2, and HOC(Ar)(CF3)2 (Ar = 4-C6H4(tBu), 2,4,6-C6H2(CF3)3, 4-Si(iPr)3 -2,6-C6H2 (CF3)2, 3,5-C6H3(CH3)2), and 2-C6H4(C(OH)(CF3)2).CHEMINFORM, Issue 16 2002Thomas J. Barbarich Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A reference model for grid architectures and its validationCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 11 2010Wil van der Aalst Abstract Computing and data-intensive applications in physics, medicine, biology, graphics, and business intelligence require large and distributed infrastructures to address the challenges of the present and the future. For example, process mining applications are faced with terrabytes of event data and computationally expensive algorithms. Computer grids are increasingly being used to deal with such challenges. However, grid computing is often approached in an ad hoc and engineering-like manner. Despite the availability of many software packages for grid applications, a good conceptual model of the grid is missing. This paper provides a formal description of the grid in terms of a colored Petri net (CPN). This CPN can be seen as a reference model for grids as it clarifies the basic concepts at the conceptual level. Moreover, the CPN allows for various kinds of analyses ranging from verification to performance analysis. We validate our model based on real-life experiments using a testbed grid architecture available in our group and we show how the model can be used for the estimation of throughput times for scientific workflows. Copyright © 2009 John Wiley & Sons, Ltd. [source] A set-oriented method definition language for object databases and its semanticsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 14 2003Elisa Bertino Abstract In this paper we propose a set-oriented rule-based method definition language for object-oriented databases. Most existing object-oriented database systems exploit a general-purpose imperative object-oriented programming language as the method definition language. Because methods are written in a general-purpose imperative language, it is difficult to analyze their properties and to optimize them. Optimization is important when dealing with a large amount of objects as in databases. We therefore believe that the use of an ad hoc, set-oriented language can offer some advantages, at least at the specification level. In particular, such a language can offer an appropriate framework to reason about method properties. In this paper, besides defining a set-oriented rule-based language for method definition, we formally define its semantics, addressing the problems of inconsistency and non-determinism in set-oriented updates. Moreover, we characterize some relevant properties of methods, such as conflicts among method specifications in sibling classes and behavioral refinement in subclasses. Copyright © 2003 John Wiley & Sons, Ltd. [source] Sensitivity Analyses of Spatial Population Viability Analysis Models for Species at Risk and Habitat Conservation PlanningCONSERVATION BIOLOGY, Issue 1 2009ILONA R. NAUJOKAITIS-LEWIS análisis de sensibilidad; análisis de viabilidad poblacional; incertidumbre; metapoblación; planificación de la conservación Abstract:,Population viability analysis (PVA) is an effective framework for modeling species- and habitat-recovery efforts, but uncertainty in parameter estimates and model structure can lead to unreliable predictions. Integrating complex and often uncertain information into spatial PVA models requires that comprehensive sensitivity analyses be applied to explore the influence of spatial and nonspatial parameters on model predictions. We reviewed 87 analyses of spatial demographic PVA models of plants and animals to identify common approaches to sensitivity analysis in recent publications. In contrast to best practices recommended in the broader modeling community, sensitivity analyses of spatial PVAs were typically ad hoc, inconsistent, and difficult to compare. Most studies applied local approaches to sensitivity analyses, but few varied multiple parameters simultaneously. A lack of standards for sensitivity analysis and reporting in spatial PVAs has the potential to compromise the ability to learn collectively from PVA results, accurately interpret results in cases where model relationships include nonlinearities and interactions, prioritize monitoring and management actions, and ensure conservation-planning decisions are robust to uncertainties in spatial and nonspatial parameters. Our review underscores the need to develop tools for global sensitivity analysis and apply these to spatial PVA. Resumen:,El análisis de viabilidad poblacional (AVP) es un marco de referencia efectivo para los esfuerzos de recuperación de especie y de hábitat, pero la incertidumbre en las estimaciones de parámetros y la estructura del modelo pueden llevar a predicciones no confiables. La integración de información compleja y a menudo incierta a los modelos de AVP espaciales requiere la aplicación de análisis de sensibilidad para explorar la influencia de parámetros espaciales y no espaciales sobre las predicciones de los modelos. Revisamos 87 análisis de modelos de AVP demográficos espaciales de plantas y animales para identificar métodos comunes de análisis de sensibilidad en publicaciones recientes. En contraste con las mejores prácticas recomendadas por la comunidad de modeladores, los análisis de los sensibilidad de AVP típicamente fueron ad hoc, inconsistentes y difíciles de comparar. La mayoría de los estudios aplicaron métodos locales a los análisis de sensibilidad, pero pocos variaron parámetros múltiples simultáneamente. La falta de estándares para los análisis de sensibilidad y descripción en los AVP espaciales tiene el potencial de comprometer la habilidad de aprender colectivamente de los resultados de AVP, de interpretar con precisión los resultados en casos en que las relaciones de los modelos sean no lineales e incluyan interacciones, para priorizar las acciones de monitoreo y manejo y para asegurar que la planificación de las decisiones de conservación sean robustas ante la incertidumbre en los parámetros espaciales y no espaciales. Nuestra revisión subraya la necesidad de desarrollar herramientas para análisis de sensibilidad globales y aplicarlos a AVP espaciales. [source] Salvage Logging, Ecosystem Processes, and Biodiversity ConservationCONSERVATION BIOLOGY, Issue 4 2006D.B. LINDENMAYER conservación de la biodiversidad; gestión forestal; procesos ecosistémicos Abstract:,We summarize the documented and potential impacts of salvage logging,a form of logging that removes trees and other biological material from sites after natural disturbance. Such operations may reduce or eliminate biological legacies, modify rare postdisturbance habitats, influence populations, alter community composition, impair natural vegetation recovery, facilitate the colonization of invasive species, alter soil properties and nutrient levels, increase erosion, modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity. These impacts can be assigned to three broad and interrelated effects: (1) altered stand structural complexity; (2) altered ecosystem processes and functions; and (3) altered populations of species and community composition. Some impacts may be different from or additional to the effects of traditional logging that is not preceded by a large natural disturbance because the conditions before, during, and after salvage logging may differ from those that characterize traditional timber harvesting. The potential impacts of salvage logging often have been overlooked, partly because the processes of ecosystem recovery after natural disturbance are still poorly understood and partly because potential cumulative effects of natural and human disturbance have not been well documented. Ecologically informed policies regarding salvage logging are needed prior to major natural disturbances so that when they occur ad hoc and crisis-mode decision making can be avoided. These policies should lead to salvage-exemption zones and limits on the amounts of disturbance-derived biological legacies (e.g., burned trees, logs) that are removed where salvage logging takes place. Finally, we believe new terminology is needed. The word salvage implies that something is being saved or recovered, whereas from an ecological perspective this is rarely the case. Resumen:,Resumimos los impactos documentados y potenciales de la cosecha de salvamento , una forma de cosecha de madera que remueve árboles y otros materiales biológicos después de una perturbación natural. Tales operaciones pueden reducir o eliminar legados biológicos, modificar hábitats post perturbación, influir en poblaciones, alterar la composición de comunidades, impedir la recuperación de la vegetación natural, facilitar la colonización de especies invasoras, alterar las propiedades del suelo y de niveles de nutrientes, incrementar la erosión, modificar regímenes hidrológicos y ecosistemas acuáticos, y alterar patrones de heterogeneidad del paisaje. Estos impactos se pueden asignar a tres efectos amplios e interrelacionados: (1) alteración de la complejidad estructural del bosque; (2) alteración de procesos y funciones ecológicas; y (3) alteración de poblaciones de especies y de la composición de la comunidad. Algunos impactos pueden ser diferentes a o adicionales a los efectos de la cosecha de madera tradicional que no es precedida de una perturbación natural severa porque las condiciones antes, durante y después de la cosecha de salvamento pueden diferir de las que caracterizan a la cosecha de madera tradicional. Los impactos potenciales de la cosecha de salvamento a menudo han sido pasados por alto, en parte porque los procesos de recuperación del ecosistema después de una perturbación natural son poco conocidos y en parte porque los efectos acumulativos potenciales de perturbaciones naturales y humanas no han sido bien documentados. Se requieren políticas ecológicamente informadas para la cosecha de salvamento para que cuando ocurran las perturbaciones naturales se evite la toma de decisiones en situaciones de crisis. Estas políticas deberán establecer zonas exentas de salvamento y límites a las cantidades de legados biológicos derivados de la perturbación (e. g., árboles quemados, troncos) que son removidos donde se lleva a cabo la cosecha de salvamento. Finalmente, creemos que se requiere una nueva terminología. La palabra salvamento implica que algo esta siendo salvado o recuperado, y este raramente es el caso desde una perspectiva ecológica. [source] Ad Hoc Reviewers 2009 / Réviseurs ad hoc 2009CONTEMPORARY ACCOUNTING RESEARCH, Issue 1 2010Article first published online: 13 MAY 2010 First page of article [source] Indicators of pretreatment suicidal ideation in adults with major depressive disorderACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2010D. W. Morris Morris DW, Trivedi MH, Husain MM, Fava M, Budhwar N, Wisniewski SR, Miyahara S, Gollan JK, Davis LL, Daly EJ, Rush AJ. Indicators of pretreatment suicidal ideation in adults with major depressive disorder. Objective:, In order to evaluate the presence of treatment emergent suicidal ideation (SI), it becomes necessary to identify those patients with SI at the onset of treatment. The purpose of this report is to identify sociodemographic and clinical features that are associated with SI in major depressive disorder (MDD) patients prior to treatment with a selective serotonin reuptake inhibitor. Method:, This multisite study enrolled 265 out-patients with non-psychotic MDD. Sociodemographic and clinical features of participants with and without SI were compared post hoc. Results:, Social phobia, bulimia nervosa, number of past depressive episodes, and race were independently associated with SI by one or more SI measure. Conclusion:, Concurrent social phobia and bulimia nervosa may be potential risk factors for SI in patients with non-psychotic MDD. Additionally, patients with more than one past depressive episode may also be at increased risk of SI. [source] Typological thinking and the conservation of subspecies: the case of the San Clemente Island loggerhead shrikeDIVERSITY AND DISTRIBUTIONS, Issue 4 2000Michael A. Patten Abstract. ,Hybridization with closely related taxa poses a significant threat to endangered subspecies (e.g. outbreeding depression, inbreeding) and confounds efforts to manage and conserve these taxa through a loss of taxonomic identity, in part because of the practical necessity of defining subspecies in a typological manner. We examined nine morphological characters in 167 post-juvenile museum specimens to determine if loggerhead shrikes Lanius ludovicianus Linnaeus 1766 on San Clemente Island (off the coast of California) remain diagnosable as L. l. mearnsi Ridgway (1903); an island endemic listed as endangered by the United States Fish and Wildlife Service. Four recent shrike specimens from the island were compared to historical specimens using a bivariate scatter plot and a discriminant function (the latter was used to classify recent specimens post hoc). The few recent specimens were not diagnosable as L. l. mearnsi, but instead appear to be intergrades between L. l. mearnsi and L. l. anthonyi Mearns 1898 (the subspecies endemic to Santa Cruz, Santa Catalina, Santa Rosa and Anacapa islands), and are perhaps closer to pure anthonyi. Our data and the species' natural history and distribution suggest that shrikes currently on San Clemente Island are the result of genetic ,swamping' of mearnsi by anthonyi. Under a necessarily typological definition of a subspecies, it is evident that mearnsi is probably no longer diagnosable. However, we conclude that protection of the entire Channel Islands population of the loggerhead shrike would be the best management strategy, as the species has declined drastically throughout the islands. [source] Does conservation planning matter in a dynamic and uncertain world?ECOLOGY LETTERS, Issue 8 2004Eli Meir Abstract Loss of biodiversity is one of the world's overriding environmental challenges. Reducing those losses by creating reserve networks is a cornerstone of global conservation and resource management. Historically, assembly of reserve networks has been ad hoc, but recently the focus has shifted to identifying optimal reserve networks. We show that while comprehensive reserve network design is best when the entire network can be implemented immediately, when conservation investments must be staged over years, such solutions actually may be sub-optimal in the context of biodiversity loss and uncertainty. Simple decision rules, such as protecting the available site with the highest irreplaceability or with the highest species richness, may be more effective when implementation occurs over many years. [source] Capillary electrophoresis using copolymers of different composition as physical coatings: A comparative studyELECTROPHORESIS, Issue 5-6 2006Guillaume L. Erny Abstract In this work, a comparative study on the use of different polymers as physically adsorbed coatings for CE is presented. It is demonstrated that the use of ad hoc synthesized polymers as coatings allows tailoring the EOF in CE increasing the flexibility of this analytical technique. Namely, different polymers were synthesized at our laboratory using different percentages of ethylpyrrolidine methacrylate (EpyM) and N,N -dimethylacrylamide (DMA). Thus, by modifying the percentage of EpyM and DMA monomers it is possible to manipulate the positive charge of the copolymer, varying the global electrical charge on the capillary wall and with that the EOF. These coated capillaries are obtained by simply flushing a given EpyM,DMA aqueous solution into bare silica capillaries. It is shown that by using these coated capillaries at adequate pHs, faster or more resolved CE separations can be achieved depending on the requirements of each analysis. Moreover, it is demonstrated that these coated capillaries reduce the electrostatic adsorption of basic proteins onto the capillary wall. Furthermore, EpyM,DMA coatings allow the reproducible chiral separation of enantiomers through the partial filling technique (PFT). The EpyM,DMA coated capillaries are demonstrated to provide reproducible EOF values independently of the pH and polymer composition with%RSD values lower than 2% for the same day. It is also demonstrated that the coating procedure is reproducible between capillaries. The compatibility of this coating protocol with CE in microchips is discussed. [source] "What exactly are you inferring?"ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2008A closer look at hypothesis testing Abstract This critical review describes the confused application of significance tests in environmental toxicology and chemistry that often produces incorrect inferences and indefensible regulatory decisions. Following a brief review of statistical testing theory, nine recommendations are put forward. The first is that confidence intervals be used instead of hypothesis tests whenever possible. The remaining recommendations are relevant if hypothesis tests are used. They are as follows: Define and justify Type I and II error rates a priori; set and justify an effect size a priori; do not confuse p(E | H0) and p(H0 | E); design tests permitting Positive Predictive Value estimation; publish negative results; estimate a priori, not post hoc, power; as warranted by study goals, favor null hypotheses that are not conventional nil hypotheses; and avoid definitive inferences from isolated tests. [source] A methodology for inferring the causes of observed impairments in aquatic ecosystems,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2002Glenn W. Suter II Abstract Biological surveys have become a common technique for determining whether aquatic communities have been injured. However, their results are not useful for identifying management options until the causes of apparent injuries have been identified. Techniques for determining causation have been largely informal and ad hoc. This paper presents a logical system for causal inference. It begins by analyzing the available information to generate causal evidence; available information may include spatial or temporal associations of potential cause and effect, field or laboratory experimental results, and diagnostic evidence from the affected organisms. It then uses a series of three alternative methods to infer the cause: Elimination of causes, diagnostic protocols, and analysis of the strength of evidence. If the cause cannot be identified with sufficient confidence, the reality of the effects is examined, and if the effects are determined to be real, more information is obtained to reiterate the process. [source] Classification Analysis of World Economic RegionsGEOGRAPHICAL ANALYSIS, Issue 4 2001Raymond J. Dezzani Economic classifications of countries are of continuing utility for comparative and analytic purposes. However, traditional methods of arriving at classifications are often ad hoc, subjective, and imprecise, not permitting the assignments to be used for closer analysis. Discriminant analysis is used in this paper to isolate a time-specific set of economic factors delimiting economic state categories that correspond to core-periphery states. The core-periphery framework is shown to be a special case of a hierarchical market scheme. The purposes of this work are (1) to create a theoretically grounded, empirically derived classification over several time periods to permit dynamic comparisons to be made and provide an explanation of change in the global economy, and (2) to provide feedback information from the classification to supply the necessary rigor and quantitative insight to the world-systems theoretical framework. Results of the analysis suggest that different economic variables provide varying levels of explanation at different times. In particular, variables representing factor endowment provide a greater measure of explanation early in the sequence (for example, 1960) while trade and investment measures are of greater importance in the latter part of the study sequence (for example, 1990). OPEC countries significantly bifurcate the world-economy classification in 1970 and exhibit separate class characteristics. Even within the short time period, a number of countries are shown to transit among the classes. The model is also able to capture the dependence structure implicit in the world-systems framework. [source] Epoetin alfa corrects anemia and improves quality of life in patients with hematologic malignancies receiving non-platinum chemotherapyHEMATOLOGICAL ONCOLOGY, Issue 4 2003Timothy J. Littlewood Abstract Anemia, a commonly occurring morbidity in patients with cancer, often leads to diminished quality of life (QOL). Numerous clinical trials have shown that epoetin alfa treatment improves hematologic and QOL variables in cancer patients. The clinical trial analysis reported here was performed to assess response to epoetin alfa in patients with hematologic malignancies. Cancer patients with anemia undergoing non-platinum-based chemotherapy who were enrolled in a multinational, randomized (2:1), double-blind, placebo-controlled trial were prospectively stratified by tumor type (hematologic, solid). Efficacy endpoints included proportion of patients transfused after day 28; change in hemoglobin (Hb) level from baseline to last assessment; proportion of treatment responders (increase in Hb ,2,g/dl unrelated to transfusion) and correctors (patients whose Hb levels reached ,12,g/dl during the study); and QOL. The protocol was amended before unblinding to prospectively collect and assess survival data 12 months after the last patient completed the study, and survival for the full study cohort was estimated using Kaplan,Meier techniques. Efficacy analyses of hematologic and QOL variables, as well as Kaplan,Meier estimates of survival, were performed post hoc for the hematologic tumor stratum. Among patients with hematologic malignancies, the mean increase in Hb levels was greater with epoetin alfa than with placebo treatment (2.2 vs. 0.3,g/dl). Transfusion requirements were lower in patients who received epoetin alfa versus placebo (25.2 vs. 43.1%), and the proportion of responders and correctors was higher with epoetin alfa than with placebo (75.2 vs. 16.7% and 72.6 vs. 14.8%, respectively). Patients who received epoetin alfa had improved QOL while patients who received placebo had decreased QOL. These results are similar to those seen in the full study cohort, where differences between epoetin alfa and placebo were significant (P<0.05) for all five primary cancer- and anemia-specific QOL domains evaluated. Although the study was not powered for survival, Kaplan,Meier estimates showed a trend in overall survival favoring epoetin alfa in both the full study cohort and the hematologic subgroup. Epoetin alfa treatment was well tolerated. Epoetin alfa therapy increased Hb levels, reduced transfusion requirements, and improved QOL in patients with anemia undergoing non-platinum chemotherapy for hematologic malignancies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Extending Gregory VII's ,Friendship Network': Social Contacts in Late Eleventh-Century FranceHISTORY, Issue 312 2008KRISTON R. RENNIE In the last quarter of the eleventh century, the Roman Church had a capable ruler and defender in Pope Gregory VII (1073,85). Despite his otherwise charismatic authority, however, Gregory's ability to extend his influence beyond the papacy's more immediate control of Rome and the Campagna was limited. Filling this administrative and legal gap was the emerging office of legation, developing ad hoc under Gregory VII in matters of reform and law. Papal legates such as the French representative, Bishop Hugh of Die (later archbishop of Lyons), became crucial figures in the machinery of papal government. They assumed a vital role in the transmission of reforming legislation north of the Alps while effectively widening Gregory VII's ,friendship network' to encompass influential members of the local and regional clerical and lay elite. With the assistance of this ecclesiastical office, moreover, the papacy significantly enhanced its opportunity for social contacts, thereby strengthening its hold on the more distant provinces of Western Christendom. By focusing on existing and growing social networks in late eleventh-century France, this article examines Hugh of Die's role as an instrument of church reform, and assesses this legate's impact on the larger papal reform initiative in France. [source] Prevalence of storage and voiding symptoms among men aged 40 years and older in a US population-based study: results from the Male Attitudes Regarding Sexual Health studyINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 8 2007D. B. Glasser Summary Aims:, Lower urinary tract symptoms (LUTS) are categorised as storage (urgency, frequency, nocturia and incontinence), voiding (sensation of incomplete emptying, hesitancy, weak stream and straining) or mixed symptoms. Methods:, In this US population-based study, we investigated the prevalence of male LUTS and the relative frequency of the LUTS subtypes, and we evaluated associations between LUTS and age, race/ethnicity and erectile dysfunction (ED). The Male Attitudes Regarding Sexual Health study included a nationally representative sample of non-Hispanic black, non-Hispanic white and Hispanic men aged , 40 years. Participants completed a questionnaire including items on ED and the International Prostate Symptom Score (IPSS). The prevalence and subtypes of LUTS were investigated post hoc by age, race/ethnicity and the presence of ED. Results:, The overall prevalence rates of storage (13%) and mixed (9%) symptoms were higher than that of voiding symptoms (6%). The prevalence of storage symptoms was similar across age groups, whereas voiding and mixed symptoms increased with age. Among men with IPSS , 8, the rates of storage (29%) and mixed (38%) symptoms were also higher than voiding symptoms (23%). Distributions of the LUTS subtypes were comparable among black, white and Hispanic respondents with IPSS , 8. The overall prevalence rate of ED (40%) increased with age among those with IPSS , 8. Isolated storage symptoms were more than twice as common as isolated voiding symptoms among US men , 40 years of age. Conclusion:, Careful attention to individual symptoms may help distinguish storage LUTS from voiding LUTS, a distinction that has important implications for treatment. [source] Virtual base stations for wireless mobile ad hoc communications: an infrastructure for the infrastructure-lessINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2001Hossam Hassanein Abstract In this paper, we propose a new protocol for wireless mobile ad hoc networks, which establishes a dynamic wireless mobile infrastructure. The proposed protocol, namely, the virtual base stations (VBS) protocol, mimics and maintains the operation of the conventional fixed infrastructure in cellular networks. In the VBS protocol, a mobile node is elected from a set of nominees to act as a temporary base station within its zone. We provide proofs for the correctness of the VBS protocol, and show lower and upper bounds for its global convergence time. Likewise, we study the characteristics and performance of VBS by means of simulation. It is shown that VBS scales well to large networks of mobile stations, and that it outperforms other infrastructure-formation protocols in terms of stability. The VBS protocol would facilitate the development of a comprehensive and promising framework for quality of service (QoS) management in wireless mobile ad hoc networks once the proper integration of the MAC protocol with the routing and call admission control mechanisms is established. The VBS architecture lays the groundwork for assigning bandwidth, and/or implementing priorities, and hence for QoS-based routing by conveying the quality of a path prior to call setup. Copyright © 2001 John Wiley & Sons, Ltd. [source] Dating currency crises with ad hoc and extreme value-based thresholds: East Asia 1970,2002 [Dating currency crises]INTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 4 2007Lestano Abstract Generally a currency crisis is defined to occur if an index of currency pressure exceeds a threshold. This paper compares currency crisis dating methods. For two definitions of currency pressure we contrast ad hoc and extreme value-based thresholds. We illustrate the methods with data of six East Asian countries for the January 1970,December 2002 period, and evaluate the methods on the basis of the IMF chronology of the Asia crisis in 1997,1999. Copyright © 2007 John Wiley & Sons, Ltd. [source] Hematological parameters and anaerobic threshold in Brazilian soccer players throughout a training programINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2008A. S. R. SILVA Summary We assessed the responses of hematological parameters and their relationship to the anaerobic threshold of Brazilian soccer players during a training program. Twelve athletes were evaluated at the beginning (week 0, T1), in the middle (week 6, T2), and at the end (week 12, T3) of the soccer training program. On the first day at 7:30 am, before collecting the blood sample at rest for the determination of the hematological parameters, the athletes were conducted to the anthropometric evaluation. On the second day at 8:30 am, the athletes had their anaerobic threshold measured. Analysis of variance with Newman,Keuls'post hoc was used for statistical comparisons between the parameters measured during the soccer training program. Correlations between the parameters analyzed were determined using the Pearson's correlation coefficient. Erythrocytes concentration, hemoglobin, and hematocrit were significantly increased from T1 to T2. The specific soccer training program led to a rise in erythrocytes, hemoglobin, and hematocrit from T1 to T2. We assumed that these results occurred due to the plasma volume reduction and may be explained by the soccer training program characteristics. Furthermore, we did not observe any correlation between the anaerobic threshold and the hematological parameters. [source] The marketing and public relations practices of Australian performing arts presentersINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 2 2002Heath McDonald Although arts organisations are often said to be underdeveloped in marketing and management areas, it is unclear whether this is actually an intentional response to the atypical environment in which they exist, or simply a result of limited skills and resources. This paper looks at performing arts presenters (PAPs) in two Australian States, profiling what they do in the way of marketing, how sophisticated they are at it and the reasons they behave the way they do. In-depth interviews with marketing managers indicated that PAPs are confused about the role of marketing, relying instead mainly on public relations. While it was widely acknowledged that marketing would be beneficial, the marketing that is executed is generally ad hoc and basic. This lack of marketing action is due primarily to a paucity of skills and resources and a historical preference for public relations, not as a considered response to the arts environment. Copyright © 2002 Henry Stewart Publications [source] Molecular dynamics of phase transitions in clusters of alkali halidesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2001Pedro C. R. Rodrigues Abstract Molecular dynamics simulations of unconstrained alkali halide clusters with 8, 64, 216, 512, 1000, 1728, 2744, 4096, 5832, and 8000 ions have been carried out using the Born,Mayer,Huggins potential. All the clusters exhibit first-order melting and freezing transitions. The melting temperature increases with the number of ions and approaches the melting temperature of the bulk. Clusters with a number of ions less than approximately 1000 present hysteresis cycles and practically do not have phase coexistence. Clusters with a number of ions over 1000 present phase coexistence during a significant part of the transition region and hysteresis is progressively eliminated as the clusters size increases. It is suggested that hysteresis is an intrinsic characteristic of small clusters. In the transition regions the calculations have been performed by fixing the total energy of the clusters. It is shown that such a technique provides a better way of analyzing the transition mechanism than the usual procedure of fixing the temperature by ad hoc rescaling the velocities or by using canonical molecular dynamics or Monte Carlo. A detailed analysis of the melting transition is presented. The effects of interfaces and impurities are discussed. A method based on the velocity autocorrelation functions is proposed, in order to determine the molar fraction of the ions present in the solid and liquid phases as well as to produce colored snapshots of the phases in coexistence. The overall agreement of the estimated melting points and enthalpies of melting with the experiment is fairly good. The estimated melting point and enthalpy of melting for KCl in particular are in excellent agreement with the experimental values. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 169,180, 2001 [source] The impact of the global financial crisis on social protection in developing countriesINTERNATIONAL SOCIAL SECURITY REVIEW, Issue 2 2010Anna McCord Abstract The global financial crisis has had a devastating effect on poverty levels in developing countries, and the social protection response to date, in the form of social assistance, has been limited, constrained by the weak systems and low coverage of pre-existing provision. Developing countries have struggled to honour pre-crisis social protection policy commitments due to declining revenues, and in this context the potential for expanding coverage to assist those further impoverished and the "new poor" are remote. Despite the expansionary fiscal stance adopted by many developing countries, the focus of policy responses to the crisis has been on protecting and stimulating growth. The focus has not been on social protection provision to assist the poor directly. Where social protection interventions have been made they have, in many cases, been limited to ad hoc and often regressive interventions such as generalized food or fuel subsidies, rather than more systemic and pro-poor interventions. However, there may be some scope for optimism, as the crisis has stimulated a number of initiatives to promote donor coordination and programming coherence, which may result in improvements in the efficiency and impact of future social protection programming. [source] | |||||||||||||||||||||||||||||||||||||||||||