965 resultados para Survey Programs.
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XVIII IUFRO World Congress, Ljubljana 1986.
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XVIII IUFRO World Congress, Ljubljana 1986.
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XVIII IUFRO World Congress, Ljubljana 1986.
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XVIII IUFRO World Congress, Ljubljana 1986.
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In a max-min LP, the objective is to maximise ω subject to Ax ≤ 1, Cx ≥ ω1, and x ≥ 0 for nonnegative matrices A and C. We present a local algorithm (constant-time distributed algorithm) for approximating max-min LPs. The approximation ratio of our algorithm is the best possible for any local algorithm; there is a matching unconditional lower bound.
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The majority of Internet traffic use Transmission Control Protocol (TCP) as the transport level protocol. It provides a reliable ordered byte stream for the applications. However, applications such as live video streaming place an emphasis on timeliness over reliability. Also a smooth sending rate can be desirable over sharp changes in the sending rate. For these applications TCP is not necessarily suitable. Rate control attempts to address the demands of these applications. An important design feature in all rate control mechanisms is TCP friendliness. We should not negatively impact TCP performance since it is still the dominant protocol. Rate Control mechanisms are classified into two different mechanisms: window-based mechanisms and rate-based mechanisms. Window-based mechanisms increase their sending rate after a successful transfer of a window of packets similar to TCP. They typically decrease their sending rate sharply after a packet loss. Rate-based solutions control their sending rate in some other way. A large subset of rate-based solutions are called equation-based solutions. Equation-based solutions have a control equation which provides an allowed sending rate. Typically these rate-based solutions react slower to both packet losses and increases in available bandwidth making their sending rate smoother than that of window-based solutions. This report contains a survey of rate control mechanisms and a discussion of their relative strengths and weaknesses. A section is dedicated to a discussion on the enhancements in wireless environments. Another topic in the report is bandwidth estimation. Bandwidth estimation is divided into capacity estimation and available bandwidth estimation. We describe techniques that enable the calculation of a fair sending rate that can be used to create novel rate control mechanisms.
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In a max-min LP, the objective is to maximise ω subject to Ax ≤ 1, Cx ≥ ω1, and x ≥ 0. In a min-max LP, the objective is to minimise ρ subject to Ax ≤ ρ1, Cx ≥ 1, and x ≥ 0. The matrices A and C are nonnegative and sparse: each row ai of A has at most ΔI positive elements, and each row ck of C has at most ΔK positive elements. We study the approximability of max-min LPs and min-max LPs in a distributed setting; in particular, we focus on local algorithms (constant-time distributed algorithms). We show that for any ΔI ≥ 2, ΔK ≥ 2, and ε > 0 there exists a local algorithm that achieves the approximation ratio ΔI (1 − 1/ΔK) + ε. We also show that this result is the best possible: no local algorithm can achieve the approximation ratio ΔI (1 − 1/ΔK) for any ΔI ≥ 2 and ΔK ≥ 2.
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"I will soon understand." The House Planning Program as an Enhancer of Pupils´ Thinking Skills and Learning in Home Economics at Comprehensive School The aim of the research was to build a study program for home economics education in order to enhance pupils´ thinking skills. The program was based on the intervention programs or strategies known as Cognitive Acceleration (CA), which are founded on the theories of Jean Piaget, Lev Vygotsky, and Reuven Feuerstein. In addition, Carl Bereiter s theory of knowledge building was integrated to the research. The viewpoint of home economics was based on the multidimensional foundation of home economics science, particularly household technology and house planning. I first analyzed the kind of body of knowledge home economics science and home economics education provides for enhancing thinking skills in home economics. For the study, a CATE (Cognitive Acceleration through Technology Education) program was adapted and modified and a House Planning program was created for home economics classes. The house planning program consisted of five lessons during which pupils learned how to make functional floor plans as well as choose furniture, household appliances and materials for the home. In order to obtain the required data, various classroom experiments were arranged in 2005 with grade 9 pupils at a comprehensive school in Helsinki. All the experiments were videotaped, and five hours of the videotaped material was edited and transcribed for closer examination. The material consisted of all the video-recorded activity of the selected study group. Interaction study and content analysis were used to analyze the data. Following the experiments, a small survey was conducted to solicit pupils´ and teacher´s opinions of the program. The analysis sheds light on the nature of pupils´ interaction and knowledge building in small group activity. Special attention was given to tracking pupils´ interaction during the socalled construction zone activity. The models and qualities of teacher´s aid and support during the lessons were examined as well. The results revealed the versatility of the pupils social interaction and common knowledge building that occurred during the small group activity. The pupils discussions, including their arguments, their sharing of ideas, and the multiple perspectives that emerged reflected home economics knowledge building. The construction zone activity appeared through expressions of cognitive conflict and metacognition. Cognitive conflict was evident in the pupils´ words and involved questioning, doubting and disputing. The metacognitive activity emerged by thinking aloud, choosing the strategies, and negotiating the results. The pupils also coordinated their activity, allocated the responsibility, and systematized their work. The teacher assisted by preparing new themes for the pupils and by participating in the small group work. The teacher´s help during the small group sessions strengthened the pupils activity in the construction zone. The results showed that one can utilize the wide multidisciplinary basis of home economics, which includes scientific knowledge but also the knowledge derived from practical activity and experience. In this study practical activity was undertaken as a planning project the result of which was a plan or a new vision for the house planning situation. The study showed that the House Planning program was able to enhance the pupils´ social interaction and collaboration. The learning environment challenged the pupils in a way that could be a gateway to further developing their thinking skills. The method of analysis created in the study could be a potential tool for examining social interaction, construction zone activity, and knowledge building in other learning environments as well. Key words: home economics, house planning, classroom experiment, thinking skills,cognitive conflict, metacognition, social interaction, knowledge building
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We study the problem of finding a set of constraints of minimum cardinality which when relaxed in an infeasible linear program, make it feasible. We show the problem is NP-hard even when the constraint matrix is totally unimodular and prove polynomial-time solvability when the constraint matrix and the right-hand-side together form a totally unimodular matrix.
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This work is a survey of the average cost control problem for discrete-time Markov processes. The authors have attempted to put together a comprehensive account of the considerable research on this problem over the past three decades. The exposition ranges from finite to Borel state and action spaces and includes a variety of methodologies to find and characterize optimal policies. The authors have included a brief historical perspective of the research efforts in this area and have compiled a substantial yet not exhaustive bibliography. The authors have also identified several important questions that are still open to investigation.
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Due to large scale afforestation programs and forest conservation legislations, India's total forest area seems to have stabilized or even increased. In spite of such efforts, forest fragmentation and degradation continues, with forests being subject to increased pressure due to anthropogenic factors. Such fragmentation and degradation is leading to the forest cover to change from very dense to moderately dense and open forest and 253 km(2) of very dense forest has been converted to moderately dense forest, open forest, scrub and non-forest (during 2005-2007). Similarly, there has been a degradation of 4,120 km(2) of moderately dense forest to open forest, scrub and non-forest resulting in a net loss of 936 km(2) of moderately dense forest. Additionally, 4,335 km(2) of open forest have degraded to scrub and non-forest. Coupled with pressure due to anthropogenic factors, climate change is likely to be an added stress on forests. Forest sector programs and policies are major factors that determine the status of forests and potentially resilience to projected impacts of climate change. An attempt is made to review the forest policies and programs and their implications for the status of forests and for vulnerability of forests to projected climate change. The study concludes that forest conservation and development policies and programs need to be oriented to incorporate climate change impacts, vulnerability and adaptation.
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Intracellular pathogen sensor, NOD2, has been implicated in regulation of wide range of anti-inflammatory responses critical during development of a diverse array of inflammatory diseases; however, underlying molecular details are still imprecisely understood. In this study, we demonstrate that NOD2 programs macrophages to trigger Notch1 signaling. Signaling perturbations or genetic approaches suggest signaling integration through cross-talk between Notch1-PI3K during the NOD2-triggered expression of a multitude of immunological parameters including COX-2/PGE(2) and IL-10. NOD2 stimulation enhanced active recruitment of CSL/RBP-Jk on the COX-2 promoter in vivo. Intriguingly, nitric oxide assumes critical importance in NOD2-mediated activation of Notch1 signaling as iNOS(-/-) macrophages exhibited compromised ability to execute NOD2-triggered Notch1 signaling responses. Correlative evidence demonstrates that this mechanism operates in vivo in brain and splenocytes derived from wild type, but not from iNOS(-/-) mice. Importantly, NOD2-driven activation of the Notch1-PI3K signaling axis contributes to its capacity to impart survival of macrophages against TNF-alpha or IFN-gamma-mediated apoptosis and resolution of inflammation. Current investigation identifies Notch1-PI3K as signaling cohorts involved in the NOD2-triggered expression of a battery of genes associated with anti-inflammatory functions. These findings serve as a paradigm to understand the pathogenesis of NOD2-associated inflammatory diseases and clearly pave a way toward development of novel therapeutics.
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Indian logic has a long history. It somewhat covers the domains of two of the six schools (darsanas) of Indian philosophy, namely, Nyaya and Vaisesika. The generally accepted definition of Indian logic over the ages is the science which ascertains valid knowledge either by means of six senses or by means of the five members of the syllogism. In other words, perception and inference constitute the subject matter of logic. The science of logic evolved in India through three ages: the ancient, the medieval and the modern, spanning almost thirty centuries. Advances in Computer Science, in particular, in Artificial Intelligence have got researchers in these areas interested in the basic problems of language, logic and cognition in the past three decades. In the 1980s, Artificial Intelligence has evolved into knowledge-based and intelligent system design, and the knowledge base and inference engine have become standard subsystems of an intelligent system. One of the important issues in the design of such systems is knowledge acquisition from humans who are experts in a branch of learning (such as medicine or law) and transferring that knowledge to a computing system. The second important issue in such systems is the validation of the knowledge base of the system i.e. ensuring that the knowledge is complete and consistent. It is in this context that comparative study of Indian logic with recent theories of logic, language and knowledge engineering will help the computer scientist understand the deeper implications of the terms and concepts he is currently using and attempting to develop.