336 research outputs found
Quons as su(2) Irreducible Tensor Operators
We prove that, for the quon algebra, which interpolates between the Bose and
Fermi statistics and depends on a free parameter q,it is possible to build an
su(2) irreducible representation. One of the consequences of this fact is that
the quons couple via the same angular momentum coupling rules obeyed by
ordinary bosons and fermions.Comment: 8 pages,Late
Quons Restricted to the Antisymmetric Subspace: Formalism and Applications
In this work we develop a formalism to treat quons restricted to the
antisymmetric part of their many-body space. A model in which a system of
identical quons interact through a pairing force is then solved within this
restriction and the differences between our solution and the usual fermionic
model solution are then presented and discussed in detail. Possible connections
to physical systems are also considered.Comment: 12 pages, 3 figure
The importance of the mixed phase in hybrid stars built with the Nambu-Jona-Lasinio model
We investigate the structure of hybrid stars based on two different
constructions: one is based on the Gibbs condition for phase coexistence and
considers the existence of a mixed phase (MP), and the other is based on the
Maxwell construction and no mixed phase is obtained. The hadron phase is
described by the non-linear Walecka model (NLW) and the quark phase by the
Nambu-Jona-Lasinio model (NJL). We conclude that the masses and radii obtained
are model dependent but not significantly different for both constructions.Comment: 8 pages, 7 figures, 3 table
Fontes orgânicas de nutrientes em sistemas de produção de batata.
Nos últimos anos, diminuiu muito o número de bataticultores na região da Quarta Colônia, no centro do Estado do Rio Grande do Sul (RS), devido ao elevado risco econômico na produção da batata. A partir de uma demanda da Associação dos Produtores de Batata da Região Central do Rio Grande do Sul (ASBAT), foram instalados experimentos visando a avaliar, técnica e economicamente, fontes orgânicas alternativas à adubação mineral tradicional dos produtores de batata, objetivando diminuir os custos de produção e o impacto do seu cultivo no ambiente. Foram estabelecidas rotações envolvendo culturas comerciais e plantas de cobertura de solo para o cultivo da batata na safra e na safrinha. As fontes de nutrientes foram camas de frango e de suínos e adubo mineral tradicionalmente utilizado pelos bataticultores. Os resultados mostraram que a utilização de fontes orgânicas de nutrientes no cultivo da batata é uma alternativa viável técnica e economicamente. Contudo, sua eficiência pode ser maximizada quando associada com a adubação mineral, especialmente para aumentar a quantidade de nitrogênio disponível desde o início do ciclo da cultura e isso é particularmente importante quando do uso da cama de suínos. A cama de frango, por conter maior quantidade de nutrientes, é uma alternativa melhor do que a cama de suínos, tanto técnica quanto economicamente
Warm stellar matter with deconfinement: application to compact stars
We investigate the properties of mixed stars formed by hadronic and quark
matter in -equilibrium described by appropriate equations of state (EOS)
in the framework of relativistic mean-field theory. We use the non- linear
Walecka model for the hadron matter and the MIT Bag and the Nambu-Jona-Lasinio
models for the quark matter. The phase transition to a deconfined quark phase
is investigated. In particular, we study the dependence of the onset of a mixed
phase and a pure quark phase on the hyperon couplings, quark model and
properties of the hadronic model. We calculate the strangeness fraction with
baryonic density for the different EOS. With the NJL model the strangeness
content in the mixed phase decreases. The calculations were performed for T=0
and for finite temperatures in order to describe neutron and proto-neutron
stars. The star properties are discussed. Both the Bag model and the NJL model
predict a mixed phase in the interior of the star. Maximum allowed masses for
proto-neutron stars are larger for the NJL model ( M)
than for the Bag model ( M).Comment: RevTeX,14 figures, accepted to publication in Physical Review
New Lump-like Structures in Scalar-field Models
In this work we investigate lump-like solutions in models described by a
single real scalar field. We start considering non-topological solutions with
the usual lump-like form, and then we study other models, where the bell-shape
profile may have varying amplitude and width, or develop a flat plateau at its
top, or even induce a lump on top of another lump. We suggest possible
applications where these exotic solutions might be used in several distinct
branches of physics.Comment: REvTex4, twocolumn, 10 pages, 9 figures; new reference added, to
appear in EPJ
Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water
The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio
Histopathological diagnoses on pleural biopsy specimens over a 15-year period at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa: A retrospective review
Background. Pleural effusions are a common reason for presentation to healthcare facilities. Blind closed pleural biopsy can be a useful tool to diagnose their cause, especially in resource-limited settings.Objectives. To determine the aetiology, frequency and change in profile of histopathological diagnoses made at Chris Hani Baragwanath Academic Hospital (CHBAH), Johannesburg, South Africa, over the period 1 January 2001 - 31 December 2015.Methods. Pleural biopsies performed at CHBAH and analysed by histopathologists from the National Health Laboratory Service at the hospital over the study period were retrospectively reviewed by accessing reports from two databases (DISA and TrakCare). The subjects’ ages, genders, HIV status and histopathological diagnoses as well as adenosine deaminase and Ziehl-Neelsen results were recorded.Results. A total of 1 013 samples were included in the study, with 780 considered adequate for assessment. The most common diagnosis was granulomatous inflammation (48.1%, n=375), with the most common type being necrotising granulomatous inflammation (73.6%, n=276). Ten percent of biopsies (n=78) showed malignancy, most commonly adenocarcinoma, with 46.2% (n=36) metastatic and 23.1% (n=18) primary lung adenocarcinoma. The odds of being diagnosed with malignancy showed increasing statistical significance above the age of 40 years: 40 - 49 years odds ratio (OR) 8.7, 95% confidence interval (CI) 1.1 - 66.9 (p=0.038); 50 - 59 years OR 12.4, 95% CI 1.6 - 95.0 (p=0.015); ≥60 years OR 23.0, 95% CI 3.1 - 171.3 (p=0.002). HIV seropositivity was associated with lower odds of being diagnosed with malignancy compared with HIV-negative patients (OR 0.5, 95% CI 0.2 - 0.9; p=0.040), with greater odds of a ‘non-cancer’ diagnosis in HIV positive patients (including granulomatous inflammation and pleuritis (OR 2.16, 95% CI 1.03 - 4.51; p=0.040)).Conclusions. Blind closed pleural biopsy has a role to play in the diagnosis of exudative pleural effusions in resource-limited settings, particularly for patients suspected to have tuberculosis (TB) or malignancy. TB remains a common cause of exudative pleural effusions. Patients aged >40 years presenting with an exudative pleural effusion should routinely have pleural biopsy performed. However, this study showed a high frequency of inadequate specimens from closed pleural biopsy. Training in the performance of this procedure to increase diagnostic rates is recommended
Generalized Global Defect Solutions
We investigate the presence of defect structures in generalized models
described by real scalar field in space-time dimensions. We work with
two distinct generalizations, one in the form of a product of functions of the
field and its derivative, and the other as a sum. We search for static
solutions and study the corresponding linear stability on general grounds. We
illustrate the results with several examples, where we find stable defect
structures of modified profile. In particular, we show how the new defect
solutions may give rise to evolutions not present in the standard scenario in
higher spatial dimensions.Comment: RevTex, 10 pages, 2 figures; version to appear in EPJ
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Family-Friendly Management, Organizational Performance and Social Legitimacy
Research on family-friendly practices has concentrated on the predictors of their use, particularly from the perspective of either institutional theory or the high involvement or commitment management vogue. This paper first shows how such perspectives can be used to generate hypotheses about the link between family-friendly management and organizational performance. Second, the paper reports research designed to test these, using data from a national representative sample of workplaces across the British economy, the Workplace Employment Relations Survey of 2004 (WERS2004). The results support the high commitment thesis that family-friendly management will strengthen the relationship between commitment and key economic outcomes, as the relationships between workforce commitment and productivity or quality are stronger in organizations when friendly management is high, which is consistent with social exchange theory. Family-friendly management is not, however, related to the human resource outcomes of labour turnover and absenteeism. Nor does the study find support for the argument that its use in conjunction with high involvement management enhances the performance effects of both. Equally, there is no support for the hypothesis from the institutional thesis that family-friendly management has positive effects on the legitimacy of the organization
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