1,015 research outputs found
AN ANALYSIS OF THE USE OF GRADES AND HOUSEBRAND LABELS IN THE RETAIL BEEF MARKET
The congruence of beef consumersĂâ purchases with their stated preferences regarding internal fat content are examined. The role of U.S. Department of Agriculture (USDA) grades and housebrand labeling of beef in providing information to consumers is studied in the theoretical framework of search theory. The empirical results indicate that the current system of USDA grades and housebrand labels is not disseminating information regarding internal fat content effectively to consumers. Suggestions are made for providing consumers with better information and education necessary to increase congruence of expressed preferences regarding internal fat content and actual beef purchases.Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,
Star formation in Chamaeleon I and III: a molecular line study of the starless core population
The Chamaeleon clouds are excellent targets for low-mass star formation
studies. Cha I and II are actively forming stars while Cha III shows no sign of
ongoing star formation. We aim to determine the driving factors that have led
to the very different levels of star formation activity in Cha I and III and
examine the dynamical state and possible evolution of the starless cores within
them. Observations were performed in various molecular transitions with APEX
and Mopra. Five cores are gravitationally bound in Cha I and one in Cha III.
The infall signature is seen toward 8-17 cores in Cha I and 2-5 cores in Cha
III, which leads to a range of 13-28% of the cores in Cha I and 10-25% of the
cores in Cha III that are contracting and may become prestellar. Future
dynamical interactions between the cores will not be dynamically significant in
either Cha I or III, but the subregion Cha I North may experience collisions
between cores within ~0.7 Myr. Turbulence dissipation in the cores of both
clouds is seen in the high-density tracers N2H+ 1-0 and HC3N 10-9. Evidence of
depletion in the Cha I core interiors is seen in the abundance distributions of
C17O, C18O, and C34S. Both contraction and static chemical models indicate that
the HC3N to N2H+ abundance ratio is a good evolutionary indicator in the
prestellar phase for both gravitationally bound and unbound cores. In the
framework of these models, we find that the cores in Cha III and the southern
part of Cha I are in a similar evolutionary stage and are less chemically
evolved than the central region of Cha I. The measured HC3N/N2H+ abundance
ratio and the evidence for contraction motions seen towards the Cha III
starless cores suggest that Cha III is younger than Cha I Centre and that some
of its cores may form stars in the future. The cores in Cha I South may on the
other hand be transient structures. (abridged)Comment: Accepted for publication in A&A. The resolution of Figure 2 has been
degraded and the abstract in the metadata has been shortened to fit within
the limits set by arXi
Primates of the Caribbean: using historical-era introduction of monkeys in the Lesser Antilles to understand patterns of island evolution
Across the world, islands were and still are inhabited by unique species, often restricted to their own island and found nowhere else. After their ancestors managed to reach an island from a mainland population and become isolated from this mainland and its ecological restrictions, they often evolved spectacular adaptations. The more extrinsic barriers to gene flow there are and the more distant the populations, the greater the probability of a profound genetic and morphological change. Whereas many other insular mammalian taxa such as proboscideans, rodents and cervids react in readily identifiable trends, primates respond in varied and unpredictable ways. In order to better understand the underlying evolutionary principles behind island speciation, this thesis focuses on the small cercopithecine monkeys taken from western Africa to the Caribbean during the transatlantic slave trade. These Chlorocebus monkeys inhabit Nevis, St Kitts and Barbados but have long been assumed to originate solely from the Senegambia region. This thesis investigates the very early phase associated with island separation, using mitochondrial analysis and 3D geometric morphometric techniques to thoroughly assess whether any changes are present in these populations. An additional assessment is made of the three western African species of Chlorocebus, which is still largely subject to taxonomic discord. The results here show that the existing taxonomic status of African Chlorocebus does not fully describe the whole situation and that changes should be made to resolve this. The molecular results from this thesis show that rather than originating from one Senegambian location, Caribbean Chlorocebus monkeys instead originate from three different African species, across the entire western African coast, meaning their current designation as âAfrican green monkeysâ is inaccurate. Additionally, morphological adaptations within these three insular populations are also already apparent, both across the three island groups and between Caribbean and African Chlorocebus
Finite temperature bosonization
Finite temperature properties of a non-Fermi liquid system is one of the most
challenging probelms in current understanding of strongly correlated electron
systems. The paradigmatic arena for studying non-Fermi liquids is in one
dimension, where the concept of a Luttinger liquid has arisen. The existence of
a critical point at zero temperature in one dimensional systems, and the fact
that experiments are all undertaken at finite temperature, implies a need for
these one dimensional systems to be examined at finite temperature.
Accordingly, we extended the well-known bosonization method of one dimensional
electron systems to finite temperatures. We have used this new bosonization
method to calculate finite temperature asymptotic correlation functions for
linear fermions, the Tomonaga-Luttinger model, and the Hubbard model.Comment: REVTex, 48 page
Parameterizing the interstellar dust temperature
The temperature of interstellar dust particles is of great importance to
astronomers. It plays a crucial role in the thermodynamics of interstellar
clouds, because of the gas-dust collisional coupling. It is also a key
parameter in astrochemical studies that governs the rate at which molecules
form on dust. In 3D (magneto)hydrodynamic simulations often a simple expression
for the dust temperature is adopted, because of computational constraints,
while astrochemical modelers tend to keep the dust temperature constant over a
large range of parameter space. Our aim is to provide an easy-to-use parametric
expression for the dust temperature as a function of visual extinction () and to shed light on the critical dependencies of the dust temperature on
the grain composition. We obtain an expression for the dust temperature by
semi-analytically solving the dust thermal balance for different types of
grains and compare to a collection of recent observational measurements. We
also explore the effect of ices on the dust temperature. Our results show that
a mixed carbonaceous-silicate type dust with a high carbon volume fraction
matches the observations best. We find that ice formation allows the dust to be
warmer by up to 15% at high optical depths ( mag) in the
interstellar medium. Our parametric expression for the dust temperature is
presented as , where is in units of the Draine (1978) UV fieldComment: 16 pages, 17 figures, 4 tables. Accepted for publication in A&A.
Version 2: the omission of factor 0.921 in equation 4 is correcte
The impact of constructive operating lease capitalisation on key accounting ratios
Current UK lease accounting regulation does not require operating leases to be capitalised in the accounts of lessees, although this is likely to change with the publication of FRS 5. This study conducts a prospective analysis of the effects of such a change. The potential magnitude of the impact of lease capitalisation upon individual users' decisions, market valuations, company cash flows, and managers' behaviour can be indicated by the effect on key accounting ratios, which are employed in decision-making and in financial contracts. The capitalised value of operating leases is estimated using a method similar to that suggested by Imhoff, Lipe and Wright (1991), adapted for the UK accounting and tax environment, and developed to incorporate company-specific assumptions. Results for 1994 for a random sample of 300 listed UK companies show that, on average, the unrecorded long-term liability represented 39% of reported long-term debt, while the unrecorded asset represented 6% of total assets. Capitalisation had a significant impact (at the 1% level) on six of the nine selected ratios (profit margin, return on assets, asset turnover, and three measures of gearing). Moreover, the Spearman rank correlation between each ratio before and after capitalisation revealed that the ranking of companies changed markedly for gearing measures in particular. There were significant inter-industry variations, with the services sector experiencing the greatest impact. An analysis of the impact of capitalisation over the five-year period from 1990 to 1994 showed that capitalisation had the greatest impact during the trough of the recession. Results were shown to be robust with respect to key assumptions of the capitalisation method. These findings contribute to the assessment of the economic consequences of a policy change requiring operating lease capitalisation. Significant changes in the magnitude of key accounting ratios and a major shift in company performance rankings suggest that interested parties' decisions and company cash flows are likely to be affected
Detection of the hydroperoxyl radical HO2 toward \rho Oph A: Additional constraints on the water chemical network
Context: Hydrogen peroxide (HOOH) was recently detected toward \rho Oph A.
Subsequent astrochemical modeling that included reactions in the gas phase and
on the surface of dust grains was able to explain the observed abundance, and
highlighted the importance of grain chemistry in the formation of HOOH as an
intermediate product in water formation. This study also predicted that the
hydroperoxyl radical HO2, the precursor of HOOH, should be detectable. Aims: We
aim at detecting the hydroperoxyl radical HO2 in \rho Oph A. Methods: We used
the IRAM 30m and the APEX telescopes to target the brightest HO2 lines at about
130 and 260 GHz. Results: We detect five lines of HO2 (comprising seven
individual molecular transitions). The fractional abundance of HO2 is found to
be about 1e-10, a value similar to the abundance of HOOH. This observational
result is consistent with the prediction of the above mentioned astrochemical
model, and thereby validates our current understanding of the water formation
on dust grains. Conclusions: This detection, anticipated by a sophisticated
gas-grain chemical model, demonstrates that models of grain chemistry have
improved tremendously and that grain surface reactions now form a crucial part
of the overall astrochemical network.Comment: 5 pages, 4 figures, accepted for publication as a Letter to the
Editor in Astronomy and Astrophysic
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