1,090 research outputs found
Gravitational eigenstates in weak gravity I: dipole decay rates of charged particles
The experimental demonstration that neutrons can reside in gravitational
quantum stationary states formed in the gravitational field of the Earth
indicates a need to examine in more detail the general theoretical properties
of gravitational eigenstates. Despite the almost universal study of quantum
theory applied to atomic and molecular states very little work has been done to
investigate the properties of the hypothetical stationary states that should
exist in similar types of gravitational central potential wells, particularly
those with large quantum numbers. In this first of a series of papers, we
attempt to address this shortfall by developing analytic, non-integral
expressions for the electromagnetic dipole state-to-state transition rates of
charged particles for any given initial and final gravitational quantum states.
The expressions are non-relativistic and hence valid provided the eigenstate
wavefunctions do not extend significantly into regions of strong gravity. The
formulae may be used to obtain tractable approximations to the transition rates
that can be used to give general trends associated with certain types of
transitions. Surprisingly, we find that some of the high angular momentum
eigenstates have extremely long lifetimes and a resulting stability that belies
the multitude of channels available for state decay.Comment: 25 pages, 2 tables, 2 figure
Does Death Render Life Absurd?
In this paper, I assess the claim that death renders life absurd. First, I characterize absurdity as something we perceive in situations involving extreme disharmonies which strike us as unexpected or unacceptable. Next, I outline several potential disharmonies which death might introduce into our existence (such as the disharmony between our dignity and capacities, and the undignified annihilation which death promises), but suggest that these examples need not be seen as necessarily absurd; there are perspectives available to us from which these facts can appear to be acceptable aspects of life. Finally, I consider a more problematic case of absurdity—that human beings allegedly fail to grasp the truth of their mortality—but suggest that the underlying disharmony here can be eliminated provided we develop an authentic attitude toward death (and that this is possible, despite some objections). In short, I argue that none of the most obvious potential absurdities which might arise from our mortality are strong enough to entail the claim that death inevitably renders life absurd, at least on one plausible and interesting interpretation of that claim
Ancient Egypt 1921 Part 3
Part 3 of the 1921 Ancient Egypt books. Contents include discoveries at Herakleopolis, the survivals of ancient Egyptians, oracular responses, and the Coptic New Year.https://knowledge.e.southern.edu/kweeks_coll/1016/thumbnail.jp
Right-Handed Sector Leptogenesis
Instead of creating the observed baryon asymmetry of the universe by the
decay of right-handed (RH) neutrinos to left-handed leptons, we propose to
generate it dominantly by the decay of the RH neutrinos to RH leptons. This
mechanism turns out to be successful in large regions of parameter space. It
may work, in particular, at a scale as low as ~TeV, with no need to
invoke quasi-degenerate RH neutrino masses to resonantly enhance the asymmetry.
Such a possibility can be probed experimentally by the observation at colliders
of a singlet charged Higgs particle and of RH neutrinos. Other mechanisms which
may lead to successful leptogenesis from the RH lepton sector interactions are
also briefly presented. The incorporation of these scenarios in left-right
symmetric and unified models is discussed.Comment: 14 pages, latex, axodraw; minor clarifications and references added,
extended discussion of the signatures at collider
Empirical Review of Youth-Employment Programs in Ghana
Ghana-s current youth unemployment rate is 19.7%, and the country faces a
significant youth unemployment problem. While a range of youth-employment
programs have been created over the years, no systematic documentation and
evaluation of the impacts of these public initiatives has been undertaken.
Clarifying which interventions work would guide policy makers in creating
strategies and programs to address the youth-employment challenge. By
complementing desk reviews with qualitative data gathered from focus-group
discussions and key informant interviews, we observe that most youth-employment
programs implemented in Ghana cover a broad spectrum that includes skills
training, job placement matching, seed capital, and subsidies. Duplication of
initiatives, lack of coordination, and few to non-existent impact evaluations
of programs are the main challenges that plague these programs. For better
coordination and effective policy making, a more centralized and coordinated
system is needed for program design and implementation. Along the same lines,
ensuring rigorous evaluation of existing youth-employment programs is necessary
to provide empirical evidence of the effectiveness and efficiency of these
programs
Routine delivery of artemisinin-based combination treatment at fixed health facilities reduces malaria prevalence in Tanzania: an observational study
BACKGROUND Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection. METHODS A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006. FINDINGS Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30). INTERPRETATION The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected.Financial support for IMPACT-Tz came primarily from CDC, the U.S. Agency for International Development and the Wellcome Trust
Alteration of Lung Physiology with the Administration of Convalescent Plasma in ARDS Patients Intubated with COVID-19 Pneumonia
**Background:** It remains unknown to what degree lung physiology is altered by administration of convalescent plasma in patients intubated with ARDS due to COVID-19 pneumonia. Although no longer clinically used as treatment for COVID-19, convalescent plasma therapy could be deployed again should new virus threats emerge in the future. **Aim:** To evaluate changes in ventilator physiologic variables in response to convalescent plasma transfusion using a retrospective, observational, case control study of intubated patients with COVID-19 pneumonia. **Methods:** Patients who were receiving mechanical ventilation due to COVID-19 at the time of administration of convalescent plasma therapy (CPT) were matched to control patients who did not receive convalescent plasma. Ventilatory data such as compliance, positive end-expiratory pressure (PEEP), FiO~2~ administered, PaO~2~/FiO~2~ ratio, and tidal volume were collected pre and post administration. Panel-level random-effects linear regression models were used to assess the mean difference and interactions between CPT and cases vs controls over time. **Results:** 12 patients received CPT while intubated and were matched to 35 intubated control patients who did not receive CPT. In total, 857 separate measurements of static compliance were obtained over time. No significant difference in static compliance was seen after CPT. In cases, adjusted mean static compliance was 30.8 (95% CI (23.3, 38.4))mL/cm H~2~O before CPT and 28.2 (95% CI (20.7,35.6)) mL/cm H~2~O afterwards. Controls adjusted mean static compliance was 33.9 (95% CI (29.5, 38.4)) mL/cm H~2~O before versus 32.2 (95% CI (27.9, 36.5)) mL/cm H~2~O afterwards. Variables that had small but statistically significant differences pre vs post CPT among cases and controls were systolic and diastolic blood pressure, FiO~2~, heart rate, applied PEEP, and respiratory rate. **Conclusion:** While some statistically significant physiologic effects were seen with CPT in mechanically ventilated patients, these were deemed to be small and clinically insignificant. This is consistent with prior research on less acutely ill COVID-19 patients
Discriminating neutrino mass models using Type II seesaw formula
In this paper we propose a kind of natural selection which can discriminate
the three possible neutrino mass models, namely the degenerate, inverted
hierarchical and normal hierarchical models, using the framework of Type II
seesaw formula. We arrive at a conclusion that the inverted hierarchical model
appears to be most favourable whereas the normal hierarchical model follows
next to it. The degenerate model is found to be most unfavourable. We use the
hypothesis that those neutrino mass models in which Type I seesaw term
dominates over the Type II left-handed Higgs triplet term are favoured to
survive in nature.Comment: No change in the results, a few references added, some changes in
Type[IIB] calculation
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