14,104 research outputs found
Launching Delta Alliance, final report of phase 2
Delta Alliance is a network that aims to improve the resilience of the worldâs deltas. It provides a foundation and framework for international knowledge sharing and development around delta issues. Phase 2 focussed on three components: developing the Delta Alliance organization, initiating network activities and (development of) research and knowledge sharing projects
The Circadian Clock Gene Period1 Connects the Molecular Clock to Neural Activity in the Suprachiasmatic Nucleus.
The neural activity patterns of suprachiasmatic nucleus (SCN) neurons are dynamically regulated throughout the circadian cycle with highest levels of spontaneous action potentials during the day. These rhythms in electrical activity are critical for the function of the circadian timing system and yet the mechanisms by which the molecular clockwork drives changes in the membrane are not well understood. In this study, we sought to examine how the clock gene Period1 (Per1) regulates the electrical activity in the mouse SCN by transiently and selectively decreasing levels of PER1 through use of an antisense oligodeoxynucleotide. We found that this treatment effectively reduced SCN neural activity. Direct current injection to restore the normal membrane potential partially, but not completely, returned firing rate to normal levels. The antisense treatment also reduced baseline [Ca(2+)]i levels as measured by Fura2 imaging technique. Whole cell patch clamp recording techniques were used to examine which specific potassium currents were altered by the treatment. These recordings revealed that the large conductance [Ca(2+)]i-activated potassium currents were reduced in antisense-treated neurons and that blocking this current mimicked the effects of the anti-sense on SCN firing rate. These results indicate that the circadian clock gene Per1 alters firing rate in SCN neurons and raise the possibility that the large conductance [Ca(2+)]i-activated channel is one of the targets
Consequences of the Factorization Hypothesis in pbar p, pp, gamma p and gamma gamma Collisions
Using an eikonal analysis, we examine the validity of the factorization
theorem for nucleon-nucleon, gamma p and gamma gamma collisions. As an example,
using the additive quark model and meson vector dominance, we directly show
that for all energies and values of the eikonal, that the factorization theorem
sigma_{nn}/sigma_{gamma p} = sigma_{gamma p}/sigma_{gamma gamma} holds. We can
also compute the survival probability of large rapidity gaps in high energy
pbar p and pp collisions. We show that the survival probabilities are identical
(at the same energy) for gamma p and gamma gamma collisions, as well as for
nucleon-nucleon collisions. We further show that neither the factorization
theorem nor the reaction-independence of the survival probabilities depends on
the assumption of an additive quark model, but, more generally, depends on the
opacity of the eikonal being independent of whether the reaction is n-n, gamma
p or gamma gamma.Comment: 8 pages, Revtex, no figures. Expanded discussion, minor correction
A new numerical method for obtaining gluon distribution functions , from the proton structure function
An exact expression for the leading-order (LO) gluon distribution function
from the DGLAP evolution equation for the proton structure
function for deep inelastic scattering has
recently been obtained [M. M. Block, L. Durand and D. W. McKay, Phys. Rev.
D{\bf 79}, 014031, (2009)] for massless quarks, using Laplace transformation
techniques. Here, we develop a fast and accurate numerical inverse Laplace
transformation algorithm, required to invert the Laplace transforms needed to
evaluate , and compare it to the exact solution. We obtain accuracies
of less than 1 part in 1000 over the entire and spectrum. Since no
analytic Laplace inversion is possible for next-to-leading order (NLO) and
higher orders, this numerical algorithm will enable one to obtain accurate NLO
(and NNLO) gluon distributions, using only experimental measurements of
.Comment: 9 pages, 2 figure
Measuring the True Cost of Government Bailout
Government intervention to assist individual businesses and industries during the 2008â2009 economic crisis was extraordinary in variety and scope. Despite official protestations of no more bailoutâ in the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, future government interventions are inevitable, should economic circumstances become sufficiently dire. Moreover, even if Congress eliminates overt bailout-type interventions, indirect forms of public bailout are likely to continue. Understandably, taxpayers have been concerned about the cost. A simple tally of dollars authorized or disbursed is wholly inadequate to accurately assess the costs of various interventions. This Article addresses the challenges of providing reasonable budgetary information with respect to different types of bailout expenditures. In addition to looking at costs for the more obvious bailout programs, the analysis explores the special cost estimation challenges for other more covert actions, such as special tax breaks or relief from burdensome regulation, that serve a bailout function. The Article also takes issue with the fragmentation of intervention efforts among different on-budget and âoff-budgetâ entities and with some of the methodologies used by the government to value assets obtained in its bailout efforts, arguing that decision making about the appropriate allocation of aggregate resources is hampered when some expenditures are âoff-budgetâ altogether and when even âon-budgetâ agencies use different accounting methods. Finally, the Article calls for transparency and budget accounting for public bailouts accomplished more indirectly through the tax system and other regulatory regimes. Adequate and transparent budget accounting for bailout costs requires greater consistency in valuation and accounting methods, and a more unified presentation of aggregate information in the budget with respect to all government bailout-type activities
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