251 research outputs found
A Bit-String Model for Biological Aging
We present a simple model for biological aging. We studied it through
computer simulations and we have found this model to reflect some features of
real populations.Comment: LaTeX file, 4 PS figures include
Impact of Corporate Governance Practices on Firm Capital Structure and Profitability: A Study of Selected Hotels and Restaurant Companies in Sri Lanka.
Corporate governance issues have been a growing area of management research especially among large and listed firms. Good corporate governance practices are regarded as important in reducing risk for investors, attracting investment capital and improving the performance of companies. Companies need financial resources and better earnings to promote their objectives. Therefore, factorsmay affect the capital structure and profitability of companies should be considered carefully. The purpose of the present study is to investigate whether there is any relationship among some specific characters of corporate governance, capital structure and profitability of listedHotels &Restaurant companies in Colombo Stock Exchange (CSE). To do so, 18 companies were selected from those which were listed inCSE during the 2007-2012. The âBoard Composition(BC)â, âBoard Size (BS)â and âCEOduality (CEOD)â were considered as independent variables, whereas,â Debt Ratio(DR)â,âDebt-to-Equity Ratio(DER)â,âReturns on Equity(ROE)â,and âReturn on Assets(ROA)â as dependent variable. The results indicate a positive relationship between âBS; BC; CEOD; ROE; ROA and DERwhereas negative relationship between BS; BID and DR.in addition CEOD have a positive relationship with DR.In addition, none of the variables have a significant relationship with capital structure and profitability. Key words: Corporate Governance; Capital Structure and Profitability
The influence of the cluster environment on the large-scale radio continuum emission of 8 Virgo cluster spirals
The influence of the environment on the polarized and total power radio
continuum emission of cluster spiral galaxies is investigated. We present deep
scaled array VLA 20 and 6 cm observations including polarization of 8 Virgo
spiral galaxies. These data are combined with existing optical, HI, and Halpha
data. Ram pressure compression leads to sharp edges of the total power
distribution at one side of the galactic disk. These edges coincide with HI
edges. In edge-on galaxies the extraplanar radio emission can extend further
than the HI emission. In the same galaxies asymmetric gradients in the degree
of polarization give additional information on the ram pressure wind direction.
The local total power emission is not sensitive to the effects of ram pressure.
The radio continuum spectrum might flatten in the compressed region only for
very strong ram pressure. This implies that neither the local star formation
rate nor the turbulent small-scale magnetic field are significantly affected by
ram pressure. Ram pressure compression occurs mainly on large scales (>=1 kpc)
and is primarily detectable in polarized radio continuum emission.Comment: 16 pages, 10 figures, accepted for publication in A&
Matching Watershed and Otolith Chemistry to Establish Natal Origin of an Endangered Desert Lake Sucker
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Toward an internally consistent astronomical distance scale
Accurate astronomical distance determination is crucial for all fields in
astrophysics, from Galactic to cosmological scales. Despite, or perhaps because
of, significant efforts to determine accurate distances, using a wide range of
methods, tracers, and techniques, an internally consistent astronomical
distance framework has not yet been established. We review current efforts to
homogenize the Local Group's distance framework, with particular emphasis on
the potential of RR Lyrae stars as distance indicators, and attempt to extend
this in an internally consistent manner to cosmological distances. Calibration
based on Type Ia supernovae and distance determinations based on gravitational
lensing represent particularly promising approaches. We provide a positive
outlook to improvements to the status quo expected from future surveys,
missions, and facilities. Astronomical distance determination has clearly
reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press
(chapter 8 of a special collection resulting from the May 2016 ISSI-BJ
workshop on Astronomical Distance Determination in the Space Age
Predicting global invasion risks: a management tool to prevent future introductions
Predicting regions at risk from introductions of non-native species and the subsequent invasions is a fundamental aspect of horizon scanning activities that enable the development of more effective preventative actions and planning of management measures. The Asian cyprinid fish topmouth gudgeon Pseudorasbora parva has proved highly invasive across Europe since its introduction in the 1960s. In addition to direct negative impacts on native fish populations, P. parva has potential for further damage through transmission of an emergent infectious disease, known to cause mortality in other species. To quantify its invasion risk, in regions where it has yet to be introduced, we trained 900 ecological niche models and constructed an Ensemble Model predicting suitability, then integrated a proxy for introduction likelihood. This revealed high potential for P. parva to invade regions well beyond its current invasive range. These included areas in all modelled continents, with several hotspots of climatic suitability and risk of introduction. We believe that these methods are easily adapted for a variety of other invasive species and that such risk maps could be used by policy-makers and managers in hotspots to formulate increased surveillance and early-warning systems that aim to prevent introductions and subsequent invasions
Benthic community structure and ecosystem functions in above- and below-waterfall pools in Borneo
Waterfalls are geomorphic features that often partition streams into discrete zones. Our study examined aquatic communities, litter decomposition and periphyton growth rates for above- and below-waterfall pools in Ulu Temburong National Park, Brunei. We observed higher fish densities in below-waterfall pools (0.24 fish mâ2 vs. 0.02 fish mâ2 in above-waterfall pools) and higher shrimp abundance in above-waterfall pools (eight shrimp/pool vs. less than one shrimp/pool in below-waterfall pools). However, macroinvertebrate densities (excluding shrimp) were similar among both pool types. Ambient periphyton was higher in below-waterfall pools in 2013 (4.3 vs. 2.8 g mâ2 in above-waterfall pools) and 2014 (4.8 vs. 3.4 g mâ2 in above-waterfall pools), while periphyton growth rates varied from 0.05 to 0.26 g mâ2 daysâ1 and were significantly higher in below-waterfall pools in 2014. Leaf litter decomposition rates (0.001 to 0.024 daysâ1) did not differ between pool types, suggesting that neither shrimp nor fish densities had consistent impacts on this ecosystem function. Regardless, this research demonstrates the varied effects of biotic and abiotic factors on community structure and ecosystem function. Our results have highlighted the importance of discontinuities, such as waterfalls, in tropical streams.</p
Effect of tube diameter and capillary number on platelet margination and near-wall dynamics
The effect of tube diameter and capillary number on platelet
margination in blood flow at tube haematocrit is investigated.
The system is modelled as three-dimensional suspension of deformable red blood
cells and nearly rigid platelets using a combination of the lattice-Boltzmann,
immersed boundary and finite element methods. Results show that margination is
facilitated by a non-diffusive radial platelet transport. This effect is
important near the edge of the cell-free layer, but it is only observed for , when red blood cells are tank-treading rather than tumbling. It is also
shown that platelet trapping in the cell-free layer is reversible for . Only for the smallest investigated tube ()
margination is essentially independent of . Once platelets have reached the
cell-free layer, they tend to slide rather than tumble. The tumbling rate is
essentially independent of but increases with . Tumbling is suppressed
by the strong confinement due to the relatively small cell-free layer thickness
at tube haematocrit.Comment: 16 pages, 10 figure
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