665 research outputs found
Diversity of deep-sea fishes of the Easter Island Ecoregion
The Easter Island Ecoregion is in the center of the South Pacific gyre and experiences ultra-oligotrophic conditions that could make it highly susceptible to global change and anthropogenic activities, so it is imperative that these regions are characterized and studied so that conservation and sustainable management strategies can be developed. From the few studies from the region, we know that the coastal areas are relatively depauperate and have relatively high rates of endemism. Here, we present a brief report from the first video observations from this region of the deep-dwelling fishes from ROV exploration of benthic communities from 157 to 281 m and baited drop-camera videos from 150 to 1850 m. We observed a total of 55 fish species from the ROV and Drop-Cam surveys; nine could not be assigned family level or lower, 26 were observed in the ROV surveys, 29 were observed in the Drop-Cam surveys, nine were observed with both survey methods, at least six species are potentially new to science, and nine species were observed at deeper depths than previously reported. These new reports may be indicative of the unique oceanographic conditions in the area and the relative isolation of the communities that have provided opportunity for the evolution of new species and favorable conditions for range expansion. In contrast, these new reports may be indicative of the severe undersampling in the south Pacific at mesopelagic depths. The prevalence of potentially new species suggests that the region likely harbors a wealth of undiscovered biodiversity
Male frequent attenders of general practice and their help seeking preferences
Background: Low rates of health service usage by men are commonly linked to masculine values and traditional male gender roles. However, not all men conform to these stereotypical notions of masculinity, with some men choosing to attend health services on a frequent basis, for a variety of different reasons. This study draws upon the accounts of male frequent attenders of the General Practitioner's (GP) surgery, examining their help-seeking preferences and their reasons for choosing services within general practice over other sources of support. Methods: The study extends thematic analysis of interview data from the Self Care in Primary Care study (SCinPC), a large scale multi-method evaluation study of a self care programme delivered to frequent attenders of general practice. Data were collected from 34 semi-structured interviews conducted with men prior to their exposure to the intervention. Results: The ages of interviewed men ranged from 16 to 72 years, and 91% of the sample (n= 31) stated that they had a current health condition. The thematic analysis exposed diverse perspectives within male help-seeking preferences and the decision-making behind men's choice of services. The study also draws attention to the large variation in men's knowledge of available health services, particularly alternatives to general practice. Furthermore, the data revealed some men's lack of confidence in existing alternatives to general practice. Conclusions: The study highlights the complex nature of male help-seeking preferences, and provides evidence that there should be no 'one size fits all' approach to male service provision. It also provides impetus for conducting further studies into this under researched area of interest. © 2011 WPMH GmbH
Electron correlation resonances in the transport through a single quantum level
Correlation effects in the transport properties of a single quantum level
coupled to electron reservoirs are discussed theoretically using a
non-equilibrium Green functions approach. Our method is based on the
introduction of a second-order self-energy associated with the Coulomb
interaction that consistently eliminates the pathologies found in previous
perturbative calculations. We present results for the current-voltage
characteristic illustrating the different correlation effects that may be found
in this system, including the Kondo anomaly and Coulomb blockade. We finally
discuss the experimental conditions for the simultaneous observation of these
effects in an ultrasmall quantum dot.Comment: 4 pages (two columns), 3 figures under reques
SUSY Higgs at the LHC: Effects of light charginos and neutralinos
In view of the latest LEP data we consider the effects of charginos and
neutralinos on the two-photon and bbbar signatures of the Higgs at the LHC.
Assuming the usual GUT inspired relation between M_1 and M_2 we show that there
are only small regions with moderate tanbeta and large stop mixings that may be
dangerous. Pathological models not excluded by LEP which have degeneracy
between the sneutrino and the chargino are however a real danger because of
large branching fraction of the Higgs into invisibles. We have also studied
models where the gaugino masses are not unified at the GUT scale. We take
M_1=M_2/10 as an example where large reductions in the signal at the LHC can
occur. However we argue that such models with a very light neutralino LSP may
give a too large relic density unless the sleptons are light. We then combine
this cosmological constraint with neutralino production with light sfermions to
further reduce the parameter space that precludes observability of the Higgs at
the LHC. We still find regions of parameter space where the drops in the usual
Higgs signals at the LHC can be drastic. Nonetheless, in such scenarios where
Higgs may escape detection we show that one should be able to produce all
charginos and neutralinos. Although the heavier of these could cascade into the
Higgs, the rates are not too high and the Higgs may not always be recovered
this way.Comment: 37 pages, 17 figures, Latex file, Paper with high resolution figures
can be found at http://wwwlapp.in2p3.fr/web/lapp/preplapp/psth/LAPTH774.ps.g
The MSSM invisible Higgs in the light of dark matter and g-2
Giving up the assumption of the gaugino mass unification at the GUT scale,
the latest LEP and Tevatron data still allow the lightest supersymmetric Higgs
to have a large branching fraction into invisible neutralinos. Such a Higgs may
be difficult to discover at the LHC and is practically unreachable at the
Tevatron. We argue that, for some of these models to be compatible with the
relic density, light sleptons with masses not far above the current limits are
needed. There are however models that allow for larger sleptons masses without
being in conflict with the relic density constraint. This is possible because
these neutralinos can annihilate efficiently through a Z-pole. We also find
that many of these models can nicely account, at the 2\sigma level, for the
discrepancy in the latest g-2 measurement. However, requiring consistency with
the g-2 at the 1\sigma level, excludes models that lead to the largest Higgs
branching fraction into LSP's. In all cases one expects that even though the
Higgs might escape detection, one would have a rich SUSY phenomenology even at
the Tevatron, through the production of charginos and neutralinos.Comment: 16 pages and 5 figures. New references added, text and figures
unchange
A Cosmology of the Brane World
We develop a possible cosmology for a Universe with n additional spatial
dimensions of variable scale, and an associated scalar field, the radion, which
is distinct from the field responsible for inflation, the inflaton. Based on a
particular ansatz for the effective potential for the inflaton and radion
(which may emerge in string theory), we show that the early expansion of the
Universe may proceed in three stages. First, the radion becomes trapped at a
value much smaller than the size of the extra dimensions today. Second, the
Universe expands exponentially, but with a Planck mass smaller than its present
value. Because the Planck mass during inflation is small, density fluctuations
in agreement with observations can arise naturally. Third, when inflation ends,
the Universe reheats, and the radion becomes free to expand once more. During
the third phase the Universe is ``radiation-dominated'' and tends toward a
fixed-point evolutionary model in which the radion grows but the temperature
remains unchanged. Ultimately, the radion becomes trapped once again at its
present value, and a short period of exponential expansion, which we identify
with the electroweak phase transition, ensues. Once this epoch is over, the
Universe reheats to a temperature of order the electroweak scale, and the
mature Universe evolves as in standard cosmological models. We show that the
present day energy density in radions can be smaller than the closure density
if the second inflationary epoch lasts about 8 e-foldings or more; the
present-day radion mass turns out to be small (less than or of the order of an
eV, depending on parameters). We argue that although our model envisages
considerable time evolution in the Planck mass, substantial spatial
fluctuations in Newton's constant are not produced.Comment: 38 pages, 2 figures, submitted to Phys Rev D. Typos corrected,
references adde
Reduction in the risk of human breast cancer by selective cyclooxygenase-2 (COX-2) inhibitors
BACKGROUND: Epidemiologic and laboratory investigations suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) have chemopreventive effects against breast cancer due to their activity against cyclooxygenase-2 (COX-2), the rate-limiting enzyme of the prostaglandin cascade. METHODS: We conducted a case control study of breast cancer designed to compare effects of selective and non-selective COX-2 inhibitors. A total of 323 incident breast cancer patients were ascertained from the James Cancer Hospital, Columbus, Ohio, during 2003–2004 and compared with 649 cancer free controls matched to the cases at a 2:1 ratio on age, race, and county of residence. Data on the past and current use of prescription and over the counter medications and breast cancer risk factors were ascertained using a standardized risk factor questionnaire. Effects of COX-2 inhibiting agents were quantified by calculating odds ratios (OR) and 95% confidence intervals. RESULTS: Results showed significant risk reductions for selective COX-2 inhibitors as a group (OR = 0.29, 95% CI = 0.14–0.59), regular aspirin (OR = 0.49, 95% CI = 0.26–0.94), and ibuprofen or naproxen (0.36, 95% CI = 0.18–0.72). Acetaminophen, a compound with negligible COX-2 activity and low dose aspirin (81 mg) produced no significant change in the risk of breast cancer. CONCLUSION: Selective COX-2 inhibitors (celecoxib and rofecoxib) were only recently approved for use in 1999, and rofecoxib (Vioxx) was withdrawn from the marketplace in 2004. Nevertheless, even in the short window of exposure to these compounds, the selective COX-2 inhibitors produced a significant (71%) reduction in the risk of breast cancer, underscoring their strong potential for breast cancer chemoprevention
International Coercion, Emulation and Policy Diffusion: Market-Oriented Infrastructure Reforms, 1977-1999
Why do some countries adopt market-oriented reforms such as deregulation, privatization and liberalization of competition in their infrastructure industries while others do not? Why did the pace of adoption accelerate in the 1990s? Building on neo-institutional theory in sociology, we argue that the domestic adoption of market-oriented reforms is strongly influenced by international pressures of coercion and emulation. We find robust support for these arguments with an event-history analysis of the determinants of reform in the telecommunications and electricity sectors of as many as 205 countries and territories between 1977 and 1999. Our results also suggest that the coercive effect of multilateral lending from the IMF, the World Bank or Regional Development Banks is increasing over time, a finding that is consistent with anecdotal evidence that multilateral organizations have broadened the scope of the “conditionality” terms specifying market-oriented reforms imposed on borrowing countries. We discuss the possibility that, by pressuring countries into policy reform, cross-national coercion and emulation may not produce ideal outcomes.http://deepblue.lib.umich.edu/bitstream/2027.42/40099/3/wp713.pd
Microwave background anisotropies in quasiopen inflation
Quasiopenness seems to be generic to multi-field models of single-bubble open
inflation. Instead of producing infinite open universes, these models actually
produce an ensemble of very large but finite inflating islands. In this paper
we study the possible constraints from CMB anisotropies on existing models of
open inflation. The effect of supercurvature anisotropies combined with the
quasiopenness of the inflating regions make some models incompatible with
observations, and severely reduces the parameter space of others. Supernatural
open inflation and the uncoupled two-field model seem to be ruled out due to
these constraints for values of . Others, such as the
open hybrid inflation model with suitable parameters for the slow roll
potential can be made compatible with observations.Comment: 19 pages, ReVTeX, 10 figures inserted with eps
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