906 resultados para fisher


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A bemutatásra kerülő kutatás célja az volt, hogy egy, a Vezetéstudomány hasábjain is megjelent ellátásiláncmenedzsment elmélet (Vezetéstudomány, 34. évf., 7–8. szám, p. 24–34.) empirikus tesztelését mutassa be. Az elmélet Fisher (1997) nevéhez fűződik, és egy racionális magyarázatot kínál arra, hogy a vállalatok által működtetett ellátási láncok miért különböznek egymástól. Véleménye szerint az ellátási lánc típusa attól függ, a lánc milyen típusú terméket visz piacra: funkcionális, mindennapi terméket vagy innovatív jellegűt. Az elméletet, bár nagyon híres az ellátásilánc-szakirodalomban, eddig nem sikerült igazolni. Jelen kutatás célja az volt, hogy tegyen egy újabb kísérletet a verifikálásra magyar vállalati minta statisztikai elemzése révén, valamint feltárja annak okait, ha ez az illeszkedés a termék típusa és az ellátási lánc típusa között nem jön létre. Ez utóbbival még egyetlen korábbi kutatás sem foglalkozott.

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General note: Title and date provided by Bettye Lane.

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One of the simplest models of adaptation to a new environment is Fisher's Geometric Model (FGM), in which populations move on a multidimensional landscape defined by the traits under selection. The predictions of this model have been found to be consistent with current observations of patterns of fitness increase in experimentally evolved populations. Recent studies investigated the dynamics of allele frequency change along adaptation of microbes to simple laboratory conditions and unveiled a dramatic pattern of competition between cohorts of mutations, i.e., multiple mutations simultaneously segregating and ultimately reaching fixation. Here, using simulations, we study the dynamics of phenotypic and genetic change as asexual populations under clonal interference climb a Fisherian landscape, and ask about the conditions under which FGM can display the simultaneous increase and fixation of multiple mutations-mutation cohorts-along the adaptive walk. We find that FGM under clonal interference, and with varying levels of pleiotropy, can reproduce the experimentally observed competition between different cohorts of mutations, some of which have a high probability of fixation along the adaptive walk. Overall, our results show that the surprising dynamics of mutation cohorts recently observed during experimental adaptation of microbial populations can be expected under one of the oldest and simplest theoretical models of adaptation-FGM.

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Fisheries activities are the main source of livelihood for the communities that live at Lake Edward fish landing sites. The landing sites include: Kazinga, Katwe, Kayanja, Kishenyi Rwenshama and Katunguru and are located within Queen Elizabeth Conservation Area (QECA). In spite of being the main source of livelihood, 74% of the respondents in a 2013 survey reported that catches for the main targeted fish species namely: Bagrus docmak (Semutundu), Oreochromis niloticus (Tilapia) and Protopterus aethiopicus (Mamba) were declining due to overfishing and catching of immature fish by the rapidly increasing population. Lake Edward Frame surveys had shown that the number of fishing crafts increased from 302 in 2008 to 330 in 2011, while the number of fishers increased from 355 to 600 during the same period. Between 2008 and 2010, catch per boat, for Bagrus docmak (Semutundu) declined from 5.25 kg to 4.04 kg and for Protopterus aethiopicus (Mamba) from 2.63 kg to 1.03kg. It has been suggested that reducing pressure on the lake should be handled using different approaches, one of which is introduction of programs for enhancing livelihood options which do not conflict with conservation of Queen Elizabeth Conservation Area (QECA). The main goal of this study was therefore to identify, prioritize and pilot livelihood options at selected landing sites of Lakes Edward and George.

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This research project sought to find out the socio-economic status of the small-scale fishers of the blue swimming crab (Portunuspelagicus) in Samar, considering the diminishing volume of catch of the species in the recent years. Using a blend of quantitative and qualitative methods, the study employed an interview schedule, focus group discussion (FGD) and observation in collecting data not only from the fishers but also from other sectors directly involved in the blue swimming crab industry.

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We measured the distribution in absolute magnitude - circular velocity space for a well-defined sample of 199 rotating galaxies of the Calar Alto Legacy Integral Field Area Survey (CALIFA) using their stellar kinematics. Our aim in this analysis is to avoid subjective selection criteria and to take volume and large-scale structure factors into account. Using stellar velocity fields instead of gas emission line kinematics allows including rapidly rotating early-type galaxies. Our initial sample contains 277 galaxies with available stellar velocity fields and growth curve r-band photometry. After rejecting 51 velocity fields that could not be modelled because of the low number of bins, foreground contamination, or significant interaction, we performed Markov chain Monte Carlo modelling of the velocity fields, from which we obtained the rotation curve and kinematic parameters and their realistic uncertainties. We performed an extinction correction and calculated the circular velocity v_circ accounting for the pressure support of a given galaxy. The resulting galaxy distribution on the M-r - v(circ) plane was then modelled as a mixture of two distinct populations, allowing robust and reproducible rejection of outliers, a significant fraction of which are slow rotators. The selection effects are understood well enough that we were able to correct for the incompleteness of the sample. The 199 galaxies were weighted by volume and large-scale structure factors, which enabled us to fit a volume-corrected Tully-Fisher relation (TFR). More importantly, we also provide the volume-corrected distribution of galaxies in the M_r - v_circ plane, which can be compared with cosmological simulations. The joint distribution of the luminosity and circular velocity space densities, representative over the range of -20 > M_r > -22 mag, can place more stringent constraints on the galaxy formation and evolution scenarios than linear TFR fit parameters or the luminosity function alone.