OALib Journal期刊

ISSN: 2333-9721




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匹配條件: “T. Hecht” ,找到相關結果約118138條。
On the stunted Mocambique tilapia Oreochromis mossambicus (Peters, 1852) (PIsces: Cichlidae) of the Matiovila hot spring, Kruger National Park
T Hecht,P Zway
Koedoe : African Protected Area Conservation and Science , 1984, DOI: 10.4102/koedoe.v27i1.548
Abstract: A stunted population of Oreochromis mossambicus occurs in the Matiovila Hot Sulphur Spring in the Kruger National Park. The growth of the fishes can best be described by the Von Bertalanffy equation L, = ^^(l-e0154^028^) mm SL. Breeding occurs throughout the year and the smallest sexually mature female was 35 mm SL. The fish from this locality were morphometrically compared to another stunted population and to a population of 0. mossambicus from a large impoundment. Speculative reasons for and advantages of stunting are presented.
Life history traits of Bathyclarias nyasensis (Siluroidei) in Lake Malawi
E. Kaunda,T. Hecht
African Zoology , 2011,
Abstract: Life history traits, including age, growth, reproduction and diet ofBathyclarias nyasensis from Lake Malawi were studied between December 1996 and November 1998. Owing to reabsorption of pectoral spines with increasing fish size, and the relatively low number of spines that could be aged reliably, only otoliths were used to age fish. The maximum age for B. nyasensis was estimated at 14 years. There was no difference in growth rate between males and females. Age-at-50 % maturity for females and males was estimated at seven and four years, respectively. The age of fish was validated using marginal zone analysis. The results need further validation, however, owing to the high percentage of samples having opaque marginal zones in all months, the failure to explain the occurrence of peak marginal zones in particular months and the high percentage of otoliths that were rejected. The hypothesis of rapid fish growth in the first year and slow growth during subsequent years was supported by results from stomach content analysis. Smaller fish that were found inshore were predominantly piscivorous while larger fish that were found in offshore regions were mostly zooplanktivorous. The utilization of zooplankton in offshore areas suggests that B. nyasensis relies on the pelagic food web in Lake Malawi
Wave functions and their use in spectroscopy and phenomenology
T. DeGrand,M. Hecht
Physics , 1992, DOI: 10.1016/0920-5632(93)90239-3
Abstract: We describe the calculation of Coulomb gauge wave functions for light quark systems, and their use as interpolating fields for excited state spectroscopy.
More about orbitally excited hadrons from lattice QCD
T. A. DeGrand,M. W. Hecht
Physics , 1992, DOI: 10.1103/PhysRevD.46.3937
Abstract: This is a second paper describing the calculation of spectroscopy for orbitally excited states from lattice simulations of Quantum Chromodynamics. New features include higher statistics for P-wave systems and first results for the spectroscopy of D-wave mesons and baryons, for relatively heavy quark masses. We parameterize the Coulomb gauge wave functions for P-wave and D-wave systems and compare them to those of their corresponding S-wave states.
Where Do We Stand on Locating the Self?  [PDF]
Jakub Limanowski, Heiko Hecht
Psychology (PSYCH) , 2011, DOI: 10.4236/psych.2011.24049
Abstract: The subjective location of the Self in the body is a traditionally problematic question, and it can only be addressed from the first-person perspective. However, this does not preclude an empirical approach to the question. In the present study, we examined whether a large sample of participants would be willing and able to determine the perceived location of their Self. The main goal was to assess current beliefs about the nature of the Self and its assumed relation to specific bodily organs. Eighty-seven participants indicated the center of their Self by placing crosshairs on human silhouettes and abstract, non-human silhouettes with varying anatomy. Results show a clearly dominant role of the brain and the heart for Self-location in humans, but only of the brain for Self-location in abstract creatures. Moreover, results reveal that people believe there is one single point inside the human body where their Self is located.
Past, Present and Future: Urgency of Dealing with Climate Change  [PDF]
Alan D. Hecht
Atmospheric and Climate Sciences (ACS) , 2014, DOI: 10.4236/acs.2014.45069

This paper gives an historic perspective on 10 critical phases and actions in advancing an understanding of climate change and taking appropriate domestic and international action. Credit goes to atmospheric scientists for their committed efforts to understand, model and measure the impacts of climate change. Today, greenhouse gases are at a record level and little doubt remains that greenhouse gases (GHG) warm the atmosphere and that human-made climate change is real. Recognizing the urgency of responding to climate change, the 2013 US Climate Action Plan aims to cut carbon emissions and prepare to deal effectively with the economic, social, and environmental impacts of climate change. Many US states, Tribes, and local communities have also begun to take action to reduce GHG emissions and adapt to the impact of climate change, especially on disadvantaged communities. While recognition of the urgency of action on climate change is growing in government and in large parts of the business and financial sector, it has taken over 40 years to get to this point. While an understanding of the reality and impact of climate change has grown, significant efforts to reduce the concentration of greenhouse gases in the atmosphere and stabilize global warming have not occurred. The problem that society faces is not the absence of scientific knowledge, but rather the need to reduce GHG emissions and create resilient and adaptive responses to climate change. This paper concludes that future successes will need more effective collaboration between government, business, and society to address climate change and greater public understanding of the impacts of climate change on human health and economic well-being.

Lack of mutations in the PVRL3 gene in North American caucasians with non-syndromic cleft lip/palate
S?zen, Mehmet A.;Hecht, Jacqueline T.;Spritz, Richard A.;
Genetics and Molecular Biology , 2008, DOI: 10.1590/S1415-47572008000400008
Abstract: cleft lip with or without cleft palate (clp) is one of the most common birth defects. in about 70% of cases, clp occurs as an isolated anomaly, denoted non-syndromic clp (nsclp). genetic linkage and association studies have implicated many loci in susceptibility to nsclp, including some members of the nectin gene family. we performed mutation screening of the pvrl3 gene that encodes nectin-3 in 73 unrelated caucasian nsclp patients and 105 unrelated controls from north america. we detected no sequence variants in the pvrl3 gene in either the nsclp patients or the controls. these data suggest that pvrl3 is not an important susceptibility gene for nsclp in the north american caucasian population.
Mutation and association analysis of the PVR and PVRL2 genes in patients with non-syndromic cleft lip and palate
S?zen, Mehmet A.;Hecht, Jacqueline T.;Spritz, Richard A.;
Genetics and Molecular Biology , 2009, DOI: 10.1590/S1415-47572009000300007
Abstract: orofacial clefts (ofc; mim 119530) are among the most common major birth defects. here, we carried out mutation screening of the pvr and pvrl2 genes, which are both located at an ofc linkage region at 19q13 (ofc3) and are closely related to pvrl1, which has been associated with both syndromic and non-syndromic cleft lip and palate (nsclp). we screened a total of 73 nsclp patients and 105 non-cleft controls from the usa for variants in pvr and pvrl2, including all exons and encompassing all isoforms. we identified four variants in pvr and five in pvrl2. one non-synonymous pvr variant, a67t, was more frequent among nsclp patients than among normal controls, but this difference did not achieve statistical significance.
Turbidity-induced changes in feeding strategies of fish in estuaries
T. Hecht,C.D. Van der Lingen
African Zoology , 2012,
Abstract: ENGLISH ABSTRACT: The aim of this study was to determine the effect of turbidity on the feeding strategies of fish in estuaries. Three species representing different feeding guilds were selected for the investigation. These were Elops machnata (representative piscivore), Pomadasys commefsonnii (a macrobenthivore) and Athefina breviceps (a planktivore). The stomach contents of these fish were examined from a clear and a turbid estuary and some experimental work was carried out on A. brevic8ps to test the hypothesis that turbidity affects feeding behaviour. Turbidity was found to have no effect on size selection of prey, but feeding rate, particularly of visual predators, was reduced at higher turbidity levels. This was caused by a decrease in the reactive distance of the fish. It would appear that in order to optimize the aquisition of food under different turbidity conditions fishes have the ability to change their feeding strategies. Visual predators are more affected by turbidity than are macrobenthic feeders. *********** AFRIKAANSE OPSOMMING: Die doeI van hierdie ondersoek was om die invloed van watertroebelheid op die voedingstrategie van vis in getyriviere te ondersoek. Drie spesies met verskillende voedingsgewoontes is gekies vir die ondersoek, naamlik E/ops machnata (verteenwoordigende visvreter), Pomadasys commefsonnii (makrobentiese vreter) en Athefina bfeviceps (planktonvreter). Die maaginhoud van hierdie vissoorte vanaf 'n helder en 'n baie troebel getyrivier is ondersoek en ontleed. Sekere eksperimentele werk is ook onderneem om die hipotese te toets dat watertroebelheid 'n verandering in die vreetgewoontes van vis teweeg bring. Die resultate het gewys dat troebelheid geen effek het op die grootte van die prooi wat geselekteer word, maar dat voedingskoers verlaag, hoofsaaklik by visuele roofvisse as gevolg van 'n afname in die reaktiewe afstand van die vis. Visuele roofvisse word tot 'n groter mate as makrobentiese vreters deur watertroebelheid geaffekteer.
De caza con el rey(1)
ARQ (Santiago) , 2010, DOI: 10.4067/S0717-69962010000100015
Abstract: the landscape is intervened to return to its natural state, with the objective of being utilized by the kings in hunting season. species of flora and fauna are forcibly introduced in a place to create gardens that we now recognize as parks. the different layers of history are superimposed and configure a particular terrain.

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