Ad Hoc (ad + hoc)

Distribution by Scientific Domains

Terms modified by Ad Hoc

  • ad hoc basis
  • ad hoc methods
  • ad hoc network
  • ad hoc questionnaire
  • ad hoc way

  • Selected Abstracts

    A reference model for grid architectures and its validation

    Wil 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 semantics

    Elisa 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 Planning

    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 Conservation

    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 2009

    Article first published online: 13 MAY 2010
    First page of article [source]

    Does conservation planning matter in a dynamic and uncertain world?

    ECOLOGY LETTERS, Issue 8 2004
    Eli 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 study

    ELECTROPHORESIS, Issue 5-6 2006
    Guillaume 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]

    A methodology for inferring the causes of observed impairments in aquatic ecosystems,

    Glenn 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 Regions

    Raymond 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]

    Extending Gregory VII's ,Friendship Network': Social Contacts in Late Eleventh-Century France

    HISTORY, Issue 312 2008
    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]

    Virtual base stations for wireless mobile ad hoc communications: an infrastructure for the infrastructure-less

    Hossam 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]

    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]

    The marketing and public relations practices of Australian performing arts presenters

    Heath 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 halides

    Pedro 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 countries

    Anna 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]

    Old age protection in India: Problems and prognosis

    Ranadev Goswami
    This paper reviews the current state of the Indian pension system. The Indian experience could potentially influence policy decisions in other developing countries, especially those with similar reliance on the national provident fund system. Institutional features of various retirement benefit schemes are highlighted and their deficiencies are discussed. It is argued that low coverage level, underperformance of provident fund schemes due to investment restrictions, and financial difficulties in administering unfunded public pension programmes have rendered the current system ineffective and unsustainable. The failed experiments with ad hoc reform initiatives in the recent past further emphasize the need for a structural and lasting change. The paper concludes with some policy directions for reforming the Indian pension system. [source]

    Using the extended quarter degree grid cell system to unify mapping and sharing of biodiversity data

    R. Larsen
    Abstract Information on the distribution of animal populations is essential for conservation planning and management. Unfortunately, shared coordinate-level data may have the potential to compromise sensitive species and generalized data are often shared instead to facilitate knowledge discovery and communication regarding species distributions. Sharing of generalized data is, unfortunately, often ad hoc and lacks scalable conventions that permit consistent sharing at larger scales and varying resolutions. One common convention in African applications is the Quarter Degree Grid Cells (QDGC) system. However, the current standard does not support unique references across the Equator and Prime Meridian. We present a method for extending QDGC nomenclature to support unique references at a continental scale for Africa. The extended QDGC provides an instrument for sharing generalized biodiversity data where laws, regulations or other formal considerations prevent or prohibit distribution of coordinate-level information. We recommend how the extended QDGC may be used as a standard, scalable solution for exchange of biodiversity information through development of tools for the conversion and presentation of multi-scale data at a variety of resolutions. In doing so, the extended QDGC represents an important alternative to existing approaches for generalized mapping and can help planners and researchers address conservation issues more efficiently. Résumé L'information sur la distribution des populations animales est essentielle pour la planification de la conservation et la gestion. Malheureusement, les données partagées au niveau des coordonnées risquent de compromettre les espèces sensibles, et les données généralisées sont souvent partagées pour faciliter la découverte et la communication des connaissances concernant la distribution des espèces. Le partage de données généralisées est, malheureusement, souvent opportuniste et manque de conventions mesurables qui permettraient le partage cohérent sur une plus grande échelle et à des résolutions variées. Une convention commune pour des applications africaines est le système de Quarter Degree Grid Cells (QDGC). Cependant, la norme actuelle ne supporte pas l'emploi des références uniques à travers l'Equateur et le premier méridien. Nous présentons une méthode pour étendre la nomenclature QDGC pour soutenir l'adoption de références uniques à l'échelle du continent, en Afrique. Le QDGC étendu fournit un instrument pour partager les données généralisées sur la biodiversité là où les lois, les réglementations et les autres considérations formelles empêchent ou interdisent la distribution de l'information au niveau coordonné. Nous disons dans quelle mesure le QDGC étendu peut être utilisé comme norme, une solution mesurable pour l'échange d'informations sur la biodiversité grâce au développement d'instruments pour la conversion et la présentation de données àéchelle multiple à des résolutions diverses. Ce faisant, le QDGC étendu représente une alternative importante aux approches existantes pour la cartographie généralisée et il peut aider les planificateurs et les chercheurs à traiter les problèmes de conservation plus efficacement. [source]

    Supporting scientific discovery learning in a simulation environment

    D.J. Reid
    Abstract Until recent times, most studies on supporting simulation-based scientific discovery learning adopted the ad hoc strategies-oriented approach. This paper makes a systematic analysis of the internal conditions of scientific discovery learning to propose a triple scheme for learning support design that includes interpretative support (IS), experimental support (ES), and reflective support (RS). The experiment was conducted with 78 students (aged from 12 to 13 years) to examine the effects of the IS and ES using a 2x2 between-subjects design. The main results were: significant effects were observed for IS on the post-test of intuitive understanding, flexible application and knowledge integration; no main effect was demonstrated for ES, and there was a marginally significant interactive effect for ES and IS on the intuitive understanding test. A process analysis showed that the successful learners had designed more well-controlled experiments than the failing ones. Learning support in a simulation environment should be directed toward the three perspectives to invite meaningful, systematic and reflective discovery learning. [source]

    Higher Education Classroom Fail to Meet Needs of Faculty and Students

    Lennie Scott-Webber Ph.D.
    OBJECTIVES: The objectives of this study were (1) to determine differences between faculty and student opinions about university classrooms when the User's Environmental Interaction Framework (UEIF) model's quadrants were considered together, (2) to determine the positive, negative, and different effects between these populations within each UEIF quadrant, and (3) to determine faculty and student use. RESEARCH DESIGN: The User's Environmental Framework (UEIF) guided the research at a large university. This framework has four quadrants: environmental/value dimensions, and behavioral/internal responses, prox-emics concepts, and interactional influences. The study had two parts: (1) a 48-question questionnaire, and (2) behavioral observations surveying both faculty and students (120 subjects) who used 15 general purpose classrooms. ANALYSIS: Stepwise Discriminant Analysis determined which subset of questions best separates student from faculty responses. Canonical Discriminant Analysis further explained relationships. KEY FINDINGS: Return rate was 67% and four observations of each classroom were conducted. Faculty and students agreed on the majority of the items. Subjects felt lighting, air quality, maintenance, equipment, and general comfort were adequate. There was a lack of commitment to the classrooms and subjects had little desire to stay in these rooms. Faculty and students disagreed on 10 questions. Faculty felt the classrooms did not convey a positive experience relating to noise control, seating flexibility, and lacked provision for social interaction. Students found signage inadequate and felt classrooms were uninspiring, nonanticipatory, and lacking symbolic meaning. Behavioral observations supported these concerns. CONCLUSION: Results indicate that general purpose classrooms on this campus do not meet all needs of faculty or students. Problem areas can be addressed through thoughtful knowledge-based interior design solutions. "I have to use a lecture format because I can't change the seating around to include group discussion." "I have to send students out into the hallway if I want to utilize a team approach in my teaching, because the seating is fixed." "I have to move the furniture at the front of the room out of my way as it looks like a used furniture store." "Technology is not integrated, nor easily accessible. It is provided ad hoc, and looks it." [source]

    Estimating the New Keynesian Phillips Curve: A Vertical Production Chain Approach

    New Keynesian Phillips Curve; generalized method of moments; vertical production chain; inflation It has become customary to estimate the New Keynesian Phillips Curve (NKPC) with generalized method of moments using a large instrument set that includes lags of variables that are ad hoc to the firm's price-decision problem. Researchers have also conventionally used real unit labor cost (RULC) as the proxy for real marginal cost even though it is difficult to support its significance. This paper introduces a new proxy for the real marginal cost term as well as a new instrument set, both of which are based on the micro foundations of the vertical chain of production. I find that the new proxy, based on input prices as opposed to wages, provides a more robust and significant fit to the model. Instruments that are based on the vertical chain of production appear to be both more valid and relevant toward the model. [source]

    Challenging gender stereotypes in the counselling of adult survivors of childhood sexual abuse

    P. E. SIMPSON ba ma rmn
    When working with adult survivors of childhood sexual abuse, the pairing of client with practitioner has implications for both parties. Many therapeutic pairings are ad hoc or based on stereotypical assumptions made by referrers or practitioners themselves. This paper reports on a small-scale study of practitioners working in the mental health directorate of an NHS Trust in Wales. One aim of the study was to explore practitioners' views on appropriate therapeutic pairings. Fifty-three respondents completed a postal questionnaire and six face-to-face interviews were also conducted. Key themes emerged from the study. These were social and cultural stereotyping, gender specific issues, the therapeutic relationship, service and professional issues and special opinions and unique angles. The terms ,therapist' and ,practitioner' will be used interchangeably in this paper. [source]

    An automated approach for abstracting execution logs to execution events

    Zhen Ming Jiang
    Abstract Execution logs are generated by output statements that developers insert into the source code. Execution logs are widely available and are helpful in monitoring, remote issue resolution, and system understanding of complex enterprise applications. There are many proposals for standardized log formats such as the W3C and SNMP formats. However, most applications use ad hoc non-standardized logging formats. Automated analysis of such logs is complex due to the loosely defined structure and a large non-fixed vocabulary of words. The large volume of logs, produced by enterprise applications, limits the usefulness of manual analysis techniques. Automated techniques are needed to uncover the structure of execution logs. Using the uncovered structure, sophisticated analysis of logs can be performed. In this paper, we propose a log abstraction technique that recognizes the internal structure of each log line. Using the recovered structure, log lines can be easily summarized and categorized to help comprehend and investigate the complex behavior of large software applications. Our proposed approach handles free-form log lines with minimal requirements on the format of a log line. Through a case study using log files from four enterprise applications, we demonstrate that our approach abstracts log files of different complexities with high precision and recall. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Which Economic Freedoms Contribute to Growth?

    A Comment
    Most studies on the relationship between economic freedom and growth employ a measure of economic freedom based on an (ad hoc) aggregation of various underlying components. We argue that the alternative aggregation procedure as recently suggested by Heckelman and Stroup (2000) , in which aggregation is directly based upon the relevance of each component for growth, as determined by multivariate regression analysis , is seriously flawed. We present an alternative index based on latent variable estimation techniques. Using standard robustness analyses we find that this index of economic freedom is not robustly related to economic growth. [source]

    Giving Birth to Gonolia: "Culture" and Sexually Transmitted Disease among the Huli of Papua New Guinea

    Holly Wardlow
    The "culture concept" has been challenged on a number of fronts, both by medical anthropologists researching AIDS and in the discipline of cultural anthropology more generally. Medical anthropologists have argued against the "etiologization" of culture, and cultural anthropologists have taken issue with the tendency to treat beliefs and practices as static and seamlessly shared. Using the narrative of one Huli woman's shifting explanation of a diagnosis of syphilis, this article argues that, rather than avoid the notion of culture, we should strive for representations that demonstrate how individuals use discourses in expedient, ad hoc, and yet deeply felt ways. This article also argues for the importance of a sociology of knowledge approach to understanding local notions of etiology. The woman's understanding of her situation was strongly influenced by her entry into a new "community" of women who had similarly been diagnosed with a sexually transmitted disease. [Papua New Guinea, sexually transmitted disease, gender, etiology] [source]

    Statistical hypothesis testing in intraspecific phylogeography: nested clade phylogeographical analysis vs. approximate Bayesian computation

    MOLECULAR ECOLOGY, Issue 2 2009
    Abstract Nested clade phylogeographical analysis (NCPA) and approximate Bayesian computation (ABC) have been used to test phylogeographical hypotheses. Multilocus NCPA tests null hypotheses, whereas ABC discriminates among a finite set of alternatives. The interpretive criteria of NCPA are explicit and allow complex models to be built from simple components. The interpretive criteria of ABC are ad hoc and require the specification of a complete phylogeographical model. The conclusions from ABC are often influenced by implicit assumptions arising from the many parameters needed to specify a complex model. These complex models confound many assumptions so that biological interpretations are difficult. Sampling error is accounted for in NCPA, but ABC ignores important sources of sampling error that creates pseudo-statistical power. NCPA generates the full sampling distribution of its statistics, but ABC only yields local probabilities, which in turn make it impossible to distinguish between a good fitting model, a non-informative model, and an over-determined model. Both NCPA and ABC use approximations, but convergences of the approximations used in NCPA are well defined whereas those in ABC are not. NCPA can analyse a large number of locations, but ABC cannot. Finally, the dimensionality of tested hypothesis is known in NCPA, but not for ABC. As a consequence, the ,probabilities' generated by ABC are not true probabilities and are statistically non-interpretable. Accordingly, ABC should not be used for hypothesis testing, but simulation approaches are valuable when used in conjunction with NCPA or other methods that do not rely on highly parameterized models. [source]

    Simulations of the heating of the Galactic stellar disc

    Jyrki Hänninen
    ABSTRACT The velocity dispersion of nearby stars in the Galactic disc is well known to increase substantially with age; this is the so-called age,velocity relation, and is interpreted as a ,heating' of the disc as a function of time. We have studied the heating of the Galactic stellar disc caused by giant molecular clouds and halo black holes, via simulations of the orbits of tracer stars embedded in a patch of the local Galactic disc. We examine a range of masses and number densities of the giant molecular cloud and halo black hole perturbers. The heating of the stellar disc in the simulations is fitted with a simple power law of the form ,,t,, where , is the velocity dispersion of the tracer stars as a function of time, t. We also fit this form to the best determinations of the increase in the velocity dispersion as a function of time as derived from stars in the solar neighbourhood for which ages can be reliably assigned. Observationally, , is found to lie in the range 0.3,0.6, i.e. it remains poorly constrained and its determination is probably still dominated by systematic errors. Better constrained observationally is the ratio of the velocity dispersions of the stars in the vertical z and horizontal x directions (i.e. towards the Galactic Centre), ,z/,x= 0.5 ± 0.1. For the heating of the stellar disc caused by giant molecular clouds (GMCs) we derive a heating ,,t0.21, which differs somewhat from early (analytic) studies in which ,,t1/4. This confirms the well-known results that there are insufficient GMCs to heat the Galactic disc appropriately. A range of dark halo black hole scenarios are verified to heat the stellar disc as ,,t1/2 (as expected from analytical studies), and give ,z/,x in the range 0.5,0.6, which is consistent with observations. Black holes with a mass of 107 M, are our favoured disc heaters, although they are only marginally consistent with observations. Simulations featuring a combination of giant molecular clouds and halo black holes can explain the observed heating of the stellar disc, but since other perturbing mechanisms, such as spiral arms, are yet to be included, we regard this solution as being ad hoc. [source]

    Bicriteria product design optimization: An efficient solution procedure using AND/OR trees

    S. Raghavan
    Competitive imperatives are causing manufacturing firms to consider multiple criteria when designing products. However, current methods to deal with multiple criteria in product design are ad hoc in nature. In this paper we present a systematic procedure to efficiently solve bicriteria product design optimization problems. We first present a modeling framework, the AND/OR tree, which permits a simplified representation of product design optimization problems. We then show how product design optimization problems on AND/OR trees can be framed as network design problems on a special graph,a directed series-parallel graph. We develop an enumerative solution algorithm for the bicriteria problem that requires as a subroutine the solution of the parametric shortest path problem. Although this parametric problem is hard on general graphs, we show that it is polynomially solvable on the series-parallel graph. As a result we develop an efficient solution algorithm for the product design optimization problem that does not require the use of complex and expensive linear/integer programming solvers. As a byproduct of the solution algorithm, sensitivity analysis for product design optimization is also efficiently performed under this framework. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 574,592, 2002; Published online in Wiley InterScience ( DOI 10.1002/nav.10031 [source]

    Multiterminal resilience for series-parallel networks

    Toni R. Farley
    Abstract Network resilience measures the average two-terminal reliability (connectedness) of a network. Multiterminal resilience extends this measure to any k vertices; it is the average k -terminal reliability of a network. This generalizes two well-studied network connectedness measures. Calculating multiterminal resilience on general networks encompasses all-terminal reliability and thus is NP-hard. Multiterminal resilience is examined on undirected series-parallel networks, and an efficient (polynomial time) algorithm is developed for calculating the resilience for every k. Applications in mobile ad hoc and sensor networks are outlined. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(2), 164,172 2007 [source]

    The treatment of oesophageal varices using a Sengstaken,Blakemore tube: considerations for nursing practice

    Teresa Christensen
    SUMMARY , The Sengstaken,Blakemore tube is slowly becoming the least preferred method for the treatment of oesophageal varices, possibly due to the potential complications that are inherent in its placement , Nursing practice pertaining to the care of this patient group appears ad hoc and reliant on local knowledge and experience, as opposed to recognized evidence of best practice [source]

    African countries propose a regional oral health strategy: The Dakar Report from 1998

    ORAL DISEASES, Issue 3 2004
    NG Myburgh
    It is clear that the African region faces a number of serious oral diseases, either because of their high prevalence or because of the severe tissue damage or death that can occur. Previous approaches to oral health in Africa have failed to recognise the epidemiological priorities of the region or to identify reliable and appropriate strategies to assess them. Efforts have consisted of an unplanned, ad hoc and spasmodic evolution of curative oral health services. This document focuses on the most severe oral problems that people have to live with like noma, oral cancer and the oral consequences of HIV/AIDS infection. It proposes a strategy for assisting member states and partners to identify priorities and interventions at various levels of the health system, particularly at the district level. The strategy aims at strengthening the capacity of countries to improve community oral health by effectively using proven interventions to address specific oral health needs. The strategy identifies five main ,programmatic areas', including (i) the development of national oral health strategies and implementation plans, (ii) integration of oral health in other programmes, (iii) delivery of effective and safe oral health services, (iv) regional approach to education and training for oral health, and (v) development of effective oral health management information systems. Many of the programmatic areas share similar characteristics described as a ,strategic orientation'. These strategic orientations give effect to the concepts of advocacy, equity, quality, partnership, operational research, communication and capacity building. The WHO Regional Committee for Africa (RC) is invited to review the proposed oral health strategy for the African region for the period 1999,2008 and provide an orientation for the improvement of oral health in member states in the region. [source]