3,688 research outputs found
Reconstruction of the Cosmic Equation of State for High Redshift
We investigate the possibilities of reconstructing the cosmic equation of
state (EoS) for high redshift. In order to obtain general results, we use two
model-independent approaches. The first reconstructs the EoS using comoving
distance and the second makes use of the Hubble parameter data. To implement
the first method, we use a recent set of Gamma-Ray Bursts (GRBs) measures. To
implement the second method, we generate simulated data using the Sandage-Loeb
() effect; for the fiducial model, we use the model. In both
cases, the statistical analysis is conducted through the Gaussian processes
(non-parametric). In general, we demonstrate that this methodology for
reconstructing the EoS using a non-parametric method plus a model-independent
approach works appropriately due to the feasibility of calculation and the ease
of introducing a priori information ( and ). In the near
future, following this methodology with a higher number of high quality data
will help obtain strong restrictions for the EoS.Comment: 9 pages, 5 figure
Interacting photon-baryon fluid, warm dark matter and the first acoustic peak
The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in
1965 for deriving the cosmic microwave background (CMB) spectrum. It was
recently reinvented by some of us to achieve an interpolation between the
radiation and dust epochs in the evolution of the Universe. This model
circumvents the complicated structure of the Boltzmann-Einstein system of
equations and admits a transparent description of warm-dark-matter effects. It
is extended here to include, on a phenomenological basis, an out-of-equilibrium
interaction between radiation and baryons which is supposed to account for
relevant aspects of pre-recombination physics in a simplified manner.
Furthermore, we use the tight-coupling approximation to explore the influence
of both this interaction and of the RRG warmness parameter on the anisotropy
spectrum of the CMB. The predictions of the model are very similar to those of
the {\Lambda}CDM model if both the interaction and the dark-matter warmness
parameters are of the order of or smaller. As far as the warmness
parameter is concerned, this is in good agreement with previous estimations on
the basis of results from structure formation.Comment: 10 pages and 4 figure
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SOCIAL WORKERS PERSPECTIVE ON BARRIERS TO FAMILY REUNIFICATION
The focus of this study is social worker’s potential perspective on barriers to family reunification in a child welfare services agency located in Central California. A constructivist research paradigm was applied to this study as it permitted the researchers to use a subjective methodology for collecting qualitative data. The study gathered data using interviews with child welfare social workers to construct a joint understanding of social workers perspective on barriers they face when reunifying child welfare families. Child welfare social workers identified numerous barriers to effective social work both in practice and in policy. The barriers found were a lack of partnerships with outside agencies, funding, conflicting policies between the state and local level, high caseloads, and an overwhelming amount of social work job duties all of which affect family reunification according to the social workers’ perspectives. Social workers shared several factors decreased a worker’s effectiveness in serving families such as high caseloads and what practice and policy changes could address these issues. On a micro level, policy and practice changes should improve social work practice to decrease caseload size decrease, which may help families reunify
Therapeutic Strategies Based on Polymeric Microparticles
The development of the field of materials science, the ability to perform multidisciplinary scientific work, and the need for novel administration technologies that maximize therapeutic effects and minimize adverse reactions to readily available drugs have led to the development of delivery systems based on microencapsulation, which has taken one step closer to the target of personalized medicine. Drug delivery systems based on polymeric microparticles are generating a strong impact on preclinical and clinical drug development and have reached a broad development in different fields supporting a critical role in the near future of medical practice. This paper presents the foundations of polymeric microparticles based on their formulation, mechanisms of drug release and some of their innovative therapeutic strategies to board multiple diseases
Superparamagnetic Poly (3-hydroxybutyrate-co-3 hydroxyvalerate) (PHBV) nanoparticles for biomedical applications
Indexación: ScieloBackground: The progress in material science and the recent advances in biodegradable/biocompatible polymers and magnetic iron oxide nanoparticles have led to develop innovative diagnostic and therapeutic strategies for diseases based on multifunctional nanoparticles, which include contrast medium for magnetic resonance imaging, agent for hyperthermia and nanocarriers for targeted drug delivery. The aim of this work is to synthesize and characterize superparamagnetic iron oxide (magnetite), and to encapsulate them into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles for biomedical applications.
Results: The magnetite nanoparticles were confirmed by X-ray diffraction and exhibited a size of 22.3 ± 8.8 nm measured by transmission electron microscopy (TEM). Polymeric PHBV nanoparticles loaded with magnetite (MgNPs) were analyzed using dynamic light scattering and showed a size of 258.6 ± 35.7 nm and a negative zeta potential (-10.8 ± 3.5 mV). The TEM examination of MgNPs exhibited a spherical core-shell structure and the magnetic measurements showed in both, non-encapsulated magnetite and MgNPs, a superparamagnetic performance. Finally, the in vitro studies about the magnetic retention of MgNPs in a segment of small intestine of rats showed an active accumulation in the region of the magnetic field.
Conclusions: The results obtained make the MgNPs suitable as potential magnetic resonance imaging contrast agents, also promoting hyperthermia and even as potential nanocarriers for site-specific transport and delivery of drugs.
Keywords: hyperthermia, magnetic resonance image (MRI), magnetite, PHBV, polymeric nanoparticles.http://ref.scielo.org/cxt57
A new bias-correction method for precipitation over complex terrain suitable for different climate states: a case study using WRF (version 3.8.1)
Marijuana on Main Streets? The Story Continues in Colombia: An Endogenous Three-part Model
Cannabis is the most common illicit drug, and understanding its demand is
relevant to analyze the potential implications of its legalization. This paper
proposes an endogenous three-part model taking into account incidental
truncation and access restrictions to study demand for marijuana in Colombia,
and analyze the potential effects of its legalization. Our application suggests
that modeling simultaneously access, intensive and extensive margin is
relevant, and that selection into access is important for the intensive margin.
We find that younger men that have consumed alcohol and cigarettes, living in a
neighborhood with drug suppliers, and friends that consume marijuana face
higher probability of having access and using this drug. In addition, we find
that marijuana is an inelastic good (-0.45 elasticity). Our results are robust
to different specifications and definitions. If marijuana were legalized,
younger individuals with a medium or low risk perception about marijuana use
would increase the probability of use in 3.8 percentage points, from 13.6% to
17.4%. Overall, legalization would increase the probability of consumption in
0.7 p.p. (2.3% to 3.0%). Different price settings suggest that annual tax
revenues fluctuate between USD 11.0 million and USD 54.2 million, a potential
benchmark is USD 32 million
Occupational Health and Safety Prevention Plan in Water Treatment Plant
The research was carried out at the "El Guarumo" drinking water plant located in Santa Ana, province of Manabí, Ecuador. The objective of the investigation was the proposal of a plan of prevention of occupational risks that allows the management of the labor risks in said plant. The main tools used were: survey, interview, checklist, LEST questionnaire for the diagnosis of the current situation in terms of working conditions, the risk identification matrix and the binary method of risk assessment. The main results obtained were the identification of the risks in their different categories, observing that the critical risk factors are related to the physical overexertion, the uncomfortable postures and the manual lifting of the load. Among the important risks are falling objects, skin contact with toxic substances and mental overwork, closely related to work pressures and job security? It was possible to carry out the proposal of preventive and corrective measures in order to properly manage the risks and contribute to the safety and health of the workers
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