250 research outputs found

    Volumen de madera muerta en rodales gestionados de Haya Oriental (Fagus orientalis Lipsky) en Turquía

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    As a result of " clean management " systems in forests, many species are lost or reduced to the point of being endangered. This is a broad term which refers to the pursuit of a tidy, system of intensively productive forest in which dead and dying wood, standing and fallen, is rigorously removed or cleansed from the system. This is because foresters believed that such wood harboured diseases and pests. The consequence of such policies applied over decades or in some cases centuries has been a massive depletion of the resource and serious declines of removal of biodiversity. This study assesses the amount of coarse dead wood in oriental beech forests in Turkey. The total volume of dead wood was revealed as 22.87 +/- 4.34 cubic m/ha; made up of 3.37 +/- 1.41 cubic m/ha (15%) as snag1 (standing dead wood with dried tips and intact top), 9.87 +/- 2.2 cubic m/ha (43%) as snag2 (standing dead wood with bark loosened and broken top), 4.13 +/- 1.9 cubic m/ha (18%) as log1 (newly fallen dead wood), and 5.51 +/- 1.99 cubic m/ha (24%) as log2 (rotted fallen dead wood). From this research the managed oriental beech stands in Turkey can be described as relatively dead wood-rich. The proportion of the total dead wood volume (%) of oriental beech stands investigated 4.81 +/- 4.72 percent of the total living wood volume. There were significant differences (F sub(14;65)= 4.109***, and SNK -Student-Newman-Keuls- = 3.99) in dead wood volume between the main study areas (min.: 4.46 cubic m/ha; max.: 46.11 cubic m/ha). This was due to the topography and particularly the steep slopes, and the road network infrastructure which influences the situation through local timber production. It is hoped that this study of oriental beech forests, may guide managers in considering dead wood and processes of decomposition in managing forests in Turkey, Southeastern Europe, the Northern Caucasus, Northern Iran and Syria.Muchas especies forestales se pierden o ven reducida su distribución hasta el punto de estar amenazadas, como resultado de sistemas de "gestión limpia" de los sistemas forestales. Este es un término amplio que se refiere a conseguir un sistema de bosques productivos de forma intensiva en los que la madera muerta, tanto en pie como caída, se extrae del sistema. Esto es debido a que los forestales creen que esta madera alberga a plagas y enfermedades. La consecuencia de estas políticas, aplicadas durante décadas o siglos, ha sido una disminución de los recursos y la perdida de biodiversidad. Este estudio evalúa la cantidad de madera muerta en bosques de haya oriental en Turquía. El volumen total extraído fue de 22,87 +/- 4,34 m cúbicos/ha; siendo de 3,37 +/- 1,41 m cúbicos/ha (15%) la madera muerta en pie de árboles puntisecos, 9,87 +/- 2,2 m cúbicos/ha (43%) de madera muerta en pie con corteza desprendida y parte superior rota, 4,13 +/- 1,9 m cúbicos/ha (18%) de madera muerta caída reciente, y 5,51 +/- 1,99 m cúbicos/ha (24%) de madera caída podrida. A partir de esta investigación, la gestión de los rodales de haya oriental en Turquía puede describirse como relativamente rico en madera muerta. La proporción del volumen total de madera muerta (%) de los rodales de haya oriental representan el 4,81 +/- 4,72% del volumen total de madera viva. Existen diferencias significativas (F sub(14;65)= 4,109***, y SNK -Student-Newman-Keuls- = 3,99) en el volumen de madera muerta entre las áreas principales de estudio (min.: 4,46 m cúbicos/ha; max.: 46,11 m cúbicos/ha). Esto se debe a la topografía y particularmente a las pendientes pronunciadas, y la red de caminos que influyen la situación de la producción local de madera. Se espera que este estudio sobre los bosques de haya oriental puedan servir de guía a los gestores para considerar la madera muerta y su proceso de descomposición en la gestión de los bosques de Turquía

    A General Backwards Calculus of Variations via Duality

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    We prove Euler-Lagrange and natural boundary necessary optimality conditions for problems of the calculus of variations which are given by a composition of nabla integrals on an arbitrary time scale. As an application, we get optimality conditions for the product and the quotient of nabla variational functionals.Comment: Submitted to Optimization Letters 03-June-2010; revised 01-July-2010; accepted for publication 08-July-201

    La cantidad de madera muerta y sus tasas de descomposición asociadas en reservas forestales y bosques manejados en el noroeste de Turquía

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    This study describes the state of coarse dead wood (CDW) in the Forest Reserve and the Managed Forest zones of northern conifer-broadleaved mixed forest. The results showed mean total CDW volumes in the ranges 30,05±11,06 m3/ha in the Forest Reserve (6,33±2,98% of the LW volume), and 9,31±2,84 m3/ha in the Managed Forest (1,96±0,84% of the LW volume). The total CDW volume was 3,22 times higher in the Forest Reserve than in the Managed Forest. The CDWlog1 and CDWsnag1 were the most abundant CDW decay classes, whilst CDWlog2 and CDWsnag2 were the lowest. Comparisons of ratios between the Managed Forest and the Forest Reserve with abundant decay classes CDWlog1 and CDWsnag1 indicated large differences. The CDWlog1 volume was 4,09 times higher, and the CDWsnag1 volume was 3,68 times greater in the Forest Reserve than in the Managed Forest. The ratio of different CWD classes in the Managed Forest to CWD classes in the Reserve Forest confirms the pattern. In both Managed and Reserve Forest zones there is balance between total CDWlogs and total CDWsnags, but the differences between total CDWlogs and total CDWsnags was not statistically significant. The total CDW volume was significantly dependent on the forest management system. The system influenced amount and diversity of CDW. In commercially managed forest the abundance and structure of CDW retained is a compromise between the needs of timber production and nature conservation.Este estudio describe el estado de la madera muerta en la zona de reserva forestal y zonas de bosques manejados de coníferas del norte de bosques mixtos de frondosas. Los resultados mostraron que la media total de los volúmenes de madera muerta es igual a 30,05 ± 11,06 m3 / ha en la Reserva Forestal (6,33 ± 2,98% del volumen de madera en pie), y 9,31 ± 2,84 m3 / ha en los bosques manejados (1,96 ± 0,84% del volumen de LW). El volumen total de madera muerta fue de 3,22 veces mayor en la Reserva Forestal de que en el bosque administrado. Las clases de decaimiento de madera muerta más abundantes eran CDWlog1 y CDWsnag1, mientras que CDWlog2 y CDWsnag2 fueron los menos abundantes. Las comparaciones de las proporciones entre el bosque manejado y la Reserva Forestal con las clases de decaimiento más abundantes (CDWlog1 y CDWsnag1) indican grandes diferencias ente las dos zonas. El volumen CDWlog1 fue 4,09 veces mayor, y el volumen CDWsnag1 fue 3,68 veces mayor en la Reserva Forestal de que en el bosque manejado. La relación de las diferentes clases de decaimiento entre los bosques manejados y la Reserva Forestal confirma el patrón. En ambos casos, bosque manejado y zonas de reserva forestal, existe un equilibrio entre CDWlogs total y CDWsnags total, pero las diferencias entre CDWlogs total y CDWsnags total no fue estadísticamente significativa. El volumen total de madera muerta depende significativamente del sistema de gestión forestal. El sistema de manejo influye sobre la cantidad y diversidad de madera muerta. En una gestión comercial de los bosques, la abundancia y estructura de madera muerta presente es un compromiso entre las necesidades de la producción de madera y la conservación de la naturaleza

    Improved Bounds on Quantum Learning Algorithms

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    In this article we give several new results on the complexity of algorithms that learn Boolean functions from quantum queries and quantum examples. Hunziker et al. conjectured that for any class C of Boolean functions, the number of quantum black-box queries which are required to exactly identify an unknown function from C is O(logCγ^C)O(\frac{\log |C|}{\sqrt{{\hat{\gamma}}^{C}}}), where γ^C\hat{\gamma}^{C} is a combinatorial parameter of the class C. We essentially resolve this conjecture in the affirmative by giving a quantum algorithm that, for any class C, identifies any unknown function from C using O(logCloglogCγ^C)O(\frac{\log |C| \log \log |C|}{\sqrt{{\hat{\gamma}}^{C}}}) quantum black-box queries. We consider a range of natural problems intermediate between the exact learning problem (in which the learner must obtain all bits of information about the black-box function) and the usual problem of computing a predicate (in which the learner must obtain only one bit of information about the black-box function). We give positive and negative results on when the quantum and classical query complexities of these intermediate problems are polynomially related to each other. Finally, we improve the known lower bounds on the number of quantum examples (as opposed to quantum black-box queries) required for (ϵ,δ)(\epsilon,\delta)-PAC learning any concept class of Vapnik-Chervonenkis dimension d over the domain {0,1}n\{0,1\}^n from Ω(dn)\Omega(\frac{d}{n}) to Ω(1ϵlog1δ+d+dϵ)\Omega(\frac{1}{\epsilon}\log \frac{1}{\delta}+d+\frac{\sqrt{d}}{\epsilon}). This new lower bound comes closer to matching known upper bounds for classical PAC learning.Comment: Minor corrections. 18 pages. To appear in Quantum Information Processing. Requires: algorithm.sty, algorithmic.sty to buil

    Direct and Inverse Variational Problems on Time Scales: A Survey

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    We deal with direct and inverse problems of the calculus of variations on arbitrary time scales. Firstly, using the Euler-Lagrange equation and the strengthened Legendre condition, we give a general form for a variational functional to attain a local minimum at a given point of the vector space. Furthermore, we provide a necessary condition for a dynamic integro-differential equation to be an Euler-Lagrange equation (Helmholtz's problem of the calculus of variations on time scales). New and interesting results for the discrete and quantum settings are obtained as particular cases. Finally, we consider very general problems of the calculus of variations given by the composition of a certain scalar function with delta and nabla integrals of a vector valued field.Comment: This is a preprint of a paper whose final and definite form will be published in the Springer Volume 'Modeling, Dynamics, Optimization and Bioeconomics II', Edited by A. A. Pinto and D. Zilberman (Eds.), Springer Proceedings in Mathematics & Statistics. Submitted 03/Sept/2014; Accepted, after a revision, 19/Jan/201

    Towards the Formalization of Fractional Calculus in Higher-Order Logic

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    Fractional calculus is a generalization of classical theories of integration and differentiation to arbitrary order (i.e., real or complex numbers). In the last two decades, this new mathematical modeling approach has been widely used to analyze a wide class of physical systems in various fields of science and engineering. In this paper, we describe an ongoing project which aims at formalizing the basic theories of fractional calculus in the HOL Light theorem prover. Mainly, we present the motivation and application of such formalization efforts, a roadmap to achieve our goals, current status of the project and future milestones.Comment: 9 page

    Mitochondrial quality control in health and cardiovascular diseases

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    Cardiovascular diseases (CVDs) are one of the primary causes of mortality worldwide. An optimal mitochondrial function is central to supplying tissues with high energy demand, such as the cardiovascular system. In addition to producing ATP as a power source, mitochondria are also heavily involved in adaptation to environmental stress and fine-tuning tissue functions. Mitochondrial quality control (MQC) through fission, fusion, mitophagy, and biogenesis ensures the clearance of dysfunctional mitochondria and preserves mitochondrial homeostasis in cardiovascular tissues. Furthermore, mitochondria generate reactive oxygen species (ROS), which trigger the production of pro-inflammatory cytokines and regulate cell survival. Mitochondrial dysfunction has been implicated in multiple CVDs, including ischemia-reperfusion (I/R), atherosclerosis, heart failure, cardiac hypertrophy, hypertension, diabetic and genetic cardiomyopathies, and Kawasaki Disease (KD). Thus, MQC is pivotal in promoting cardiovascular health. Here, we outline the mechanisms of MQC and discuss the current literature on mitochondrial adaptation in CVDs

    Euler-Lagrange equations for composition functionals in calculus of variations on time scales

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    In this paper we consider the problem of the calculus of variations for a functional which is the composition of a certain scalar function HH with the delta integral of a vector valued field ff, i.e., of the form H(abf(t,xσ(t),xΔ(t))Δt)H(\int_{a}^{b}f(t,x^{\sigma}(t),x^{\Delta}(t))\Delta t). Euler-Lagrange equations, natural boundary conditions for such problems as well as a necessary optimality condition for isoperimetric problems, on a general time scale, are given. A number of corollaries are obtained, and several examples illustrating the new results are discussed in detail.Comment: Submitted 10-May-2009 to Discrete and Continuous Dynamical Systems (DCDS-B); revised 10-March-2010; accepted 04-July-201

    2022 Midterm Election Voter Turnout in the Mountain West

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    This fact sheet presents voter turnout rates in the Mountain West (Arizona, Colorado, New Mexico, Nevada, and Utah) for the 2022 midterm election. The data are retrieved from the 2023 Brookings Institution report “New Voter Turnout Data from 2022 shows some surprises, including lower turnout for youth, women, and Black Americans in some states” by William H. Frey

    Environmental and Socio-Economic Stress in the Mountain West

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    This fact sheet examines data on environmental and socio-economic risk metrics including which metrics pose the most risk for Nevada counties.The data are retrieved from “System for the Triage of Risks from Environmental and Socio-Economic Stressors” created by the Massachusetts Institute of Technology (MIT) joint program on the science and policy of global change
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