807 research outputs found

    Constitution of the forest road evaluation form for Turkish forestry

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    It is highly important to describe the capabilities of existing forest roads in terms of all the functions assigned to them in line with forestry objectives and to define their conditions of utilization in the future. This study aimed at determining and grading the factors that are required to make an evaluation concerning the forest roads and preparing an evaluation form for them. Twenty-three evaluation factors and indicators that subgroup these factors were defined to evaluate forest roads. The method ofAnalytical Hierarchy Process (AHP) was used to define the significance rates at the step of factor evaluation. Survey method was applied for expert group evaluation. Significance rates of the factors were found through an evaluation of the data obtained. After the significance rates of the factors that were regarded at the outset as significant factors for evaluation of roads were defined, factors having a significance rate of lower than 2% were extracted and calculation was repeated accordingly. After fouriterations, the forest road evaluation form was prepared with 13 factors. Factors in the form and their respective significance rates were defined as vertical slope value, 12.73%; condition of superstructure, 6.89%; condition of art structure and its compliance with the draining system, 5.71%; availability of continuous access, 5.17%; transportation costs, 3.94%; availability of fire protection 12.37%; proneness to develop erosion and any water quality problem 11.45%; the risk of land-slide due to high hillside slope 12.55%; proneness to make pressure on water courses 5.97%; risk to damage or annihilate the wild habitats 5.63%; eligibility for forestry works 2.64% and eligibility for utilization for security 6.45%.The evaluation form was prepared as practical and handy to use

    Science mapping research on educational leadership and management in Turkey : a bibliometric review of international publications

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    Abstract: Over the past two decades, there have been significant efforts to investigate knowledge produc-tion in the field of educational leadership and management (EDLM) in non-Western contexts. Consistent with this effort, the present paper aims to identify the contribution of Turkish scholars to the international EDLM literature. More specifically, the review examined the volume, jour-nals, authors, types of papers, most frequently used keywords, citation impact, and co-citation networks of papers associated with Turkish EDLM scholars. Bibliometric methods were em-ployed to examine 313 papers published by Turkish scholars in internationally recognized jour-nals. The results show that while Turkish EDLM scholars have predominantly published in Tur-key-based journals, there has also been a substantial increase in the number of papers published in international journals in recent years. This literature is largely empirical with topical foci con-centrated on issues surrounding school leadership and organizational behavior. Author co-citation analysis identified three main Schools of Thought in the Turkish literature: Leadership for Learning, Leading Teachers, Administrative Behavior and Effects in Turkey. Several rec-ommendations are made in order to further develop EDLM field in both Turkey and other emerging countries

    Option Value and Dynamic Programming Model Estimates of Social Security Disability Insurance Application Timing

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    This paper develops dynamic structural models - an option value model and a dynamic programming model - of the Social Security Disability Insurance (SSDI) application timing decision. We estimate the time to application from the point at which a health condition first begins to affect the kind or amount of work that a currently employed person can do. We use Health and Retirement Study (HRS) and restricted access Social Security earnings data for estimation. Based on tests of both in-sample and out-of-sample predictive accuracy, our option value model performs better than both our dynamic programming model and our reduced form hazard model

    Dynamic Modeling of the SSDI Application Timing Decision: The Importance of Policy Variables

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    This paper analyzes the importance of policy variables in the context of Social Security Disability Insurance (SSDI) application timing decision. Previously, we explicitly modeled the optimal timing of SSDI application using dynamic structural models. We estimated these models using data from the Health and Retirement Study (HRS). This paper uses option value model estimates to simulate application timing under alternative SSDI policy formulations. We consider changes in three policy variables: benefit levels, acceptance rates, and employer accommodation. Our simulations suggest all these changes would have substantial effects on expected spell lengths until application and on lifetime application rates, and hence on SSDI caseloads

    Option Value and Dynamic Programming Model Estimates of Social Security Disability Insurance Application Timing

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    This paper develops dynamic structural models - an option value model and a dynamic programming model - of the Social Security Disability Insurance (SSDI) application timing decision. We estimate the time to application from the point at which a health condition first begins to affect the kind or amount of work that a currently employed person can do. We use Health and Retirement Study (HRS) and restricted access Social Security earnings data for estimation. Based on tests of both in-sample and out-of-sample predictive accuracy, our option value model performs better than both our dynamic programming model and our reduced form hazard model

    CMS search plans and sensitivity to new physics with dijets

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    CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 inverse picobarns of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions.Comment: 10 pages, 4 figures, accepted for publication in J. Phys. G: Nucl. Part. Phy

    Detection by tissue printing hybridization of Pome fruit viroids in the mediterranean basin

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    Available data on the incidence and biodiversity of pome fruit viroids in the Mediterranean basin are limited. Before starting a research survey to fill this gap, a tissue-printing hydridization (TPH) method to detect Apple scar skin viroid (ASSVd), Pear blister canker viroid (PBCVd) and Apple dimple fruit viroid (ADFVd) has been developed and validated. Afterward, TPH was used in large-scale indexing of pome fruit viroids in Bosnia and Herzegovina, Malta, Lebanon and Turkey. A total of about 1,000 trees was randomly collected and tested. Positive results obtained by TPH were confirmed by at least one additional detection method (RT-PCR and/or Northern-blot hybridization) and viroids were finally identified by sequencing full-length cDNA clones. PBCVd was detected in 13%, 12.4% and 5.4% of the tested pear trees in Bosnia and Herzegovina, Malta and Turkey, respectively, showing a wider diffusion of this viroid than expected. In contrast, ASSVd was never detected and ADFVd was only found in symptomatic trees (cv. Starking Delicious) in Lebanon, confirming a restricted presence of these viroids in the Mediterranean basin. Altogether, these data support the use of TPH as an easy and valuable tool for exploring pome fruit viroid spread. Keywords: Viroid disease, viroid spread, pome fruit trees, detection methods, molecular hybridizatio

    A parametric integer programming algorithm for bilevel mixed integer programs

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    We consider discrete bilevel optimization problems where the follower solves an integer program with a fixed number of variables. Using recent results in parametric integer programming, we present polynomial time algorithms for pure and mixed integer bilevel problems. For the mixed integer case where the leader's variables are continuous, our algorithm also detects whether the infimum cost fails to be attained, a difficulty that has been identified but not directly addressed in the literature. In this case it yields a ``better than fully polynomial time'' approximation scheme with running time polynomial in the logarithm of the relative precision. For the pure integer case where the leader's variables are integer, and hence optimal solutions are guaranteed to exist, we present two algorithms which run in polynomial time when the total number of variables is fixed.Comment: 11 page

    Searching for Lee-Wick Gauge Bosons at the LHC

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    In an extension of the Standard Model(SM) based on the ideas of Lee and Wick, Grinstein, O'Connell and Wise have found an interesting way to remove the usual quadratically divergent contributions to the Higgs mass induced by radiative corrections. Phenomenologically, the model predicts the existence of Terascale, negative-norm copies of the usual SM fields with rather unique properties: ghost-like propagators and negative decay widths, but with otherwise SM-like couplings. The model is both unitary and causal on macroscopic scales. In this paper we examine whether or not such states with these unusual properties can be uniquely identified as such at the LHC. We find that in the extended strong and electroweak gauge boson sector of the model, which is the simplest one to analyze, such an identification can be rather difficult. Observation of heavy gluon-like resonances in the dijet channel offers the best hope for this identification.Comment: 17 pages, 4 figs; discussion adde
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