585 research outputs found
Time Evolution of Unstable Particle Decay Seen with Finite Resolution
Time evolution of the decay process of unstable particles is investigated in
field theory models. We first formulate how to renormalize the non-decay
amplitude beyond perturbation theory and then discuss short-time behavior of
very long-lived particles. Two different formalisms, one that does and one that
does not, assume existence of the asymptotic field of unstable particles are
considered. The non-decay amplitude is then calculated by introducing a finite
time resolution of measurement, which makes it possible to discuss both
renormalizable and non-renormalizable decay interaction including the nucleon
decay. In ordinary circumstances the onset of the exponential decay law starts
at times as early as at roughly the resolution time, but with an enhanced
amplitude which may be measurable. It is confirmed that the short-time formula
of the exponential decay law may be used to set limits on the
nucleon decay rate in underground experiments. On the other hand, an
exceptional example of S-wave decay of very small Q-value is found, which does
not have the exponential period at all.Comment: 26 pages, LATEX file with 8 PS figure
Truthmakers and modality
This paper attempts to locate, within an actualist ontology, truthmakers for modal truths: truths of the form or . In section 1 I motivate the demand for substantial truthmakers for modal truths. In section 2 I criticise Armstrong’s account of truthmakers for modal truths. In section 3 I examine essentialism and defend an account of what makes essentialist attributions true, but I argue that this does not solve the problem of modal truth in general. In section 4 I discuss, and dismiss, a theistic account of the source of modal truth proposed by Alexander Pruss. In section 5 I offer a means of (dis)solving the problem
Andes Basin Focal Project
The CPWF Basin Focal Project for the Andes system of basins worked with a range of local
stakeholders to develop a better understanding of the mechanisms for improving the
productivity of water in the Andes. We considered productivity in broad terms as the
productivity of energy (HEP), food and fiber (agriculture) and livelihoods (industry, transport
and benefit sharing such as Payments for Environmental Services schemes (PES)).
In addition to the compiled data bases and analyses on poverty and institutions, one of the
key deliverables of the project was the development and deployment of the AguAAndes
policy support system (PSS). This integrates analyses of water availability and productivity
within the local environmental and policy context. It is a web-based policy support system
combining an extensive spatial database with process-based models for hydrology, crop
production and socio-economic processes. It is intended to allow analysts and decision
makers to test the potential onsite and offsite impacts of land and water management
decisions in terms of their ability to sustain environmental services and human wellbeing.
Interventions and recommendations for future actions on water and food in the region are
presented
The hyperon-nucleon interaction: conventional versus effective field theory approach
Hyperon-nucleon interactions are presented that are derived either in the
conventional meson-exchange picture or within leading order chiral effective
field theory. The chiral potential consists of one-pseudoscalar-meson exchanges
and non-derivative four-baryon contact terms. With regard to meson-exchange
hyperon-nucleon models we focus on the new potential of the Juelich group,
whose most salient feature is that the contributions in the scalar--isoscalar
(\sigma) and vector--isovector (\rho) exchange channels are constrained by a
microscopic model of correlated \pi\pi and KKbar exchange.Comment: 28 pages, 8 figures, submitted to Lecture Notes in Physic
Spontaneous Creation of Inflationary Universes and the Cosmic Landscape
We study some gravitational instanton solutions that offer a natural
realization of the spontaneous creation of inflationary universes in the brane
world context in string theory. Decoherence due to couplings of higher
(perturbative) modes of the metric as well as matter fields modifies the
Hartle-Hawking wavefunction for de Sitter space. Generalizing this new
wavefunction to be used in string theory, we propose a principle in string
theory that hopefully will lead us to the particular vacuum we live in, thus
avoiding the anthropic principle. As an illustration of this idea, we give a
phenomenological analysis of the probability of quantum tunneling to various
stringy vacua. We find that the preferred tunneling is to an inflationary
universe (like our early universe), not to a universe with a very small
cosmological constant (i.e., like today's universe) and not to a 10-dimensional
uncompactified de Sitter universe. Such preferred solutions are interesting as
they offer a cosmological mechanism for the stabilization of extra dimensions
during the inflationary epoch.Comment: 52 pages, 7 figures, 1 table. Added discussion on supercritical
string vacua, added reference
Creatine kinase-MB elevation after percutaneous coronary intervention predicts adverse outcomes in patients with acute coronary syndromes.
AIM: To study the relationship between outcomes and peak creatine kinase (CK)-MB levels after percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation acute coronar
Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method
Organic semiconductors with higher carrier mobility and better transparency have been
actively pursued for numerous applications, such as flat-panel display backplane and sensor
arrays. The carrier mobility is an important figure of merit and is sensitively influenced by the
crystallinity and the molecular arrangement in a crystal lattice. Here we describe the growth
of a highly aligned meta-stable structure of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene
(C8-BTBT) from a blended solution of C8-BTBT and polystyrene by using a novel offcentre
spin-coating method. Combined with a vertical phase separation of the blend, the
highly aligned, meta-stable C8-BTBT films provide a significantly increased thin film transistor
hole mobility up to 43 cm2 Vs�1 (25 cm2 Vs�1 on average), which is the highest value
reported to date for all organic molecules. The resulting transistors show high transparency of
490% over the visible spectrum, indicating their potential for transparent, high-performance
organic electronics
Demographic and Operational Factors Predicting Study Completion in a Multisite Case-Control Study of Preschool Children
Participant attrition can limit inferences drawn from study results and inflate research costs. We examined factors associated with completion of the Study to Explore Early Development (2007-2011), a multiple-component, case-control study of risk factors for autism spectrum disorder in preschoolers, conducted in California, Colorado, Georgia, Maryland, North Carolina, and Pennsylvania. Participants (n = 3,769) were asked to complete phone interviews, questionnaires, an in-person evaluation, and biologic sampling. We examined whether participant demographic and administrative factors predicted completion using mixed-effects logistic regression models. Completion of individual key study components was generally 70% or higher. However, 58% of families completed all per-protocol data elements (defined a priori as key study components). Per-protocol completion differed according to mother's age, race, educational level, driving distance to clinic, number of contact attempts to enroll, and number of telephone numbers provided (all P < 0.05). Case status was not associated with completion, despite additional data collection for case-confirmation. Analysis of a subset that completed an early interview revealed no differences in completion by household factors of income, primary language spoken, number of adults, or number of children with chronic conditions. Differences in completion by race and education were notable and need to be carefully considered in developing future recruitment and completion strategies
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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