2,124 research outputs found
Description of rotating nuclei in terms of isovector pairing
A systematic investigation of the rotating even-even nuclei in the mass
region has been performed within the frameworks of the Cranked
Relativistic Mean field, Cranked Relativistic Hartree Bogoliubov theories and
cranked Nilsson-Strutinsky approach. Most of the experimental data is well
accounted for in the calculations. The present study suggests that there is
strong isovector -pair field at low spin, the strength of which is defined
by the isospin symmetry. At high spin, the isovector pair field is destroyed
and the data are well described by the calculations assuming zero pairing. No
clear evidence for the existence of the isoscalar -pairing has been
obtained in the present investigation.Comment: 20 pages + 19 figures, submitted to Phys. Rev.
Bouncing wave packets, Ehrenfest theorem, and uncertainty relation based upon a new concept for the momentum of a particle in a box
For a particle in a box, the operator
is not self-adjoint and thus does not qualify as the physical momentum. As a result, in general the Ehrenfest theorem is violated. Based upon a recently developed new concept for a self-adjoint momentum operator, we reconsider the theorem and find that it is now indeed satisfied for all physically admissible boundary conditions. We illustrate these results for bouncing wave packets which first spread, then shrink, and return to their original form after a certain revival time. We derive a very simple form of the general HeisenbergâRobertsonâSchrödinger uncertainty relation and show that our construction also provides a physical interpretation for it
Molecular structure of highly-excited resonant states in Mg and the corresponding Be+O and C+C decays
Exotic Be and C decays from high-lying resonances in Mg are
analyzed in terms of a cluster model. The calculated quantities agree well with
the corresponding experimental data. It is found that the calculated decay
widths are very sensitive to the angular momentum carried by the outgoing
cluster. It is shown that this property makes cluster decay a powerful tool to
determine the spin as well as the molecular structures of the resonances.Comment: 17 pages, no figur
Glasslike Arrest in Spinodal Decomposition as a Route to Colloidal Gelation
Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich
and colloid-poor regions. Gelation results when interconnected colloid-rich
regions solidify. We show that this occurs when these regions undergo a glass
transition, leading to dynamic arrest of the spinodal decomposition. The
characteristic length scale of the gel decreases with increasing quench depth,
and the nonergodicity parameter exhibits a pronounced dependence on scattering
vector. Mode coupling theory gives a good description of the dynamics, provided
we use the full static structure as input.Comment: 14 pages, 4 figures; replaced with published versio
Acceptability of a prime vendor system in public healthcare facilities in Tanzania
BACKGROUND: Pharmaceutical supply chain management in low- and middle-income countries has received substantial attention to address the shortage of medicines at peripheral facilities. The focus has been on health system interventions, including the establishment of public-private partnerships (PPPs). In 2014, the United Republic of Tanzania began implementing the Jazia prime vendor system (Jazia PVS) with a contracted private wholesale supplier to complement the national medicines supply chain in public facilities. Few studies have investigated the acceptability of such a prime vendor system. This study analyses factors that contributed to the acceptability of Jazia PVS introduced in Tanzania. We used qualitative analytical methods to study experiences of Jazia PVS implementers in 4 districts in mid-2018. METHODS: Data were drawn from 14 focus group discussions (FGDs), 7 group discussions (GDs) and 30 in-depth interviews (IDIs) with a range of actors involved in Jazia PVS. The study analysed 7 acceptability dimensions as defined in the acceptability framework by Sekhon et al. Framework analysis was adopted to summarise the results using a deductive and an inductive approach. RESULTS: The findings show that participants' acceptability of Jazia PVS was influenced by the increased availability of essential medicines at the facilities, higher order fulfilment rates, and timely delivery of the consignment. Furthermore, acceptability was also influenced by the good reputation of the prime vendor, close collaboration with district managers, and participants' understanding that the prime vendor was meant to complement the existing supply chain. Intervention coherence, experienced opportunity cost and intervention burden, affective attitude and self-efficacy were also important in explaining the acceptability of the Jazia PVS. CONCLUSION: In conclusion, the most critical factor contributing to the acceptability of the Jazia PVS was the perceived effectiveness of the system in achieving its intended purpose. Districts purchasing directly from the prime vendor have a policy based on the possibility to increase availability of essential medicines at peripheral facilities in a low income setting; however, it is crucial to select a reputable and competent vendor, as well as to abide by the contractual agreements
A note on the uniqueness of D=4 N=1 Supergravity
We investigate in 4 spacetime dimensions, all the consistent deformations of
the lagrangian , which is the sum of the
Pauli-Fierz lagrangian for a free massless spin 2 field and the
Rarita-Schwinger lagrangian for a free massless spin 3/2
field. Using BRST cohomogical techniques, we show, under the assumptions of
locality, Poincar\'e invariance, conservation of the number of gauge symmetries
and the number of derivatives on each fields, that N=1 D=4 supergravity is the
only consistent interaction between a massless spin 2 and a massless spin 3/2
field. We do not assume general covariance. This follows automatically, as does
supersymmetry invariance. Various cohomologies related to conservations laws
are also given.Comment: 22+1 pages, LaTeX. References adde
PathOrganic â Risks and Recommendations Regarding Human Pathogens in Organic Vegetable Production Chains
PathOrganic assesses risks associated with the consumption of fresh and minimally
processed vegetables due to the prevalence of bacterial human pathogens in plant
produce. The project evaluates whether organic production poses a risk on food safety,
taking into consideration sources of pathogen transmission (e.g. animal manure).
The project also explores whether organic versus conventional production practices
may reduce the risk of pathogen manifestation. In Europe, vegetable-linked outbreaks
are not well investigated. A conceptual model together with novel sampling strategies
and specifically adjusted methods provides the basis for large-scale surveys of organically
grown plant produce in five European countries. Critical control points are
determined and evaluated and factors contributing to a food safety problem are analyzed
in greenhouse and field experiments. The project aims at developing a quantitative
risk assessment model and at formulating recommendations for improving food
safety in organic vegetable production
Linear Relaxation Processes Governed by Fractional Symmetric Kinetic Equations
We get fractional symmetric Fokker - Planck and Einstein - Smoluchowski
kinetic equations, which describe evolution of the systems influenced by
stochastic forces distributed with stable probability laws. These equations
generalize known kinetic equations of the Brownian motion theory and contain
symmetric fractional derivatives over velocity and space, respectively. With
the help of these equations we study analytically the processes of linear
relaxation in a force - free case and for linear oscillator. For a weakly
damped oscillator we also get kinetic equation for the distribution in slow
variables. Linear relaxation processes are also studied numerically by solving
corresponding Langevin equations with the source which is a discrete - time
approximation to a white Levy noise. Numerical and analytical results agree
quantitatively.Comment: 30 pages, LaTeX, 13 figures PostScrip
Aharonov-Bohm-Type Oscillations of Thermopower in a Quantum Dot Ring Geometry
We investigate Aharonov-Bohm-type oscillations of the thermopower of a
quantum dot embedded in a ring for the case when the interaction between
electrons can be neglected. The thermopower is shown to be strongly flux
dependent, and typically the amplitude of oscillations exceeds the background
value. It is also shown to be essentially dependent on the phase of the
scattering matrix which is determined by the experimental geometry and is not
known in the given experiment. Two procedures to compare theory and experiment
are proposed.Comment: Revtex, 5 figures include
The Borrego Mountain, California, earthquake of 9 April 1968: A preliminary report
The largest earthquake to hit California in more than 15 years occurred at
02:28:58.9 GCT on 9 April 1968 near Borrego Mountain, on the western edge of
the Imperial Valley. The Seismological Laboratory at Pasadena has tentatively
assigned the shock a magnitude of 6.5, an epicentral location of 33 ° 08.8' N, 116 °
07.5' W, and a focal depth of 20 km. The earthquake was felt throughout most
of southern California and adjacent areas, but the absence of severe damage and
casualties was in large part due to the relatively undeveloped nature of the epicentral
region. Indeed, it would have been difficult to pick a location in the southernmost
part of the State more remote from centers of population
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