3,606 research outputs found
Increasing returns to scale and international diffusion of technology: an empirical study for Brazil (1976-2000)
This article aims at exploring the empirical evidence regarding the effects of increasing returns to scale and international technological diffusion on the Brazilian manufacturing industry. Our departure point is a Kaldorian-type theoretical model that provides not only the positive effects of scale but also of diffusion on industrial performance. We use Vector Auto Regressive (VAR) for testing the model. VAR will estimate the coefficients related to industrial output, labor productivity, exports and the technological gap between the United States and Brazil. This technique also provides simulations for the short-term and long-term trajectories under exogenous shocks. The observations are on a three-month period basis and the sampling period runs from the second half of 1976 to the second half of 2000. The conclusion highlights both evidences of increasing returns on the Brazilian industry that faces, however, some structural constraints. Besides, the model also reveals Brazil's difficulties to catch uptechnological gap; increasing returns to scale; economic growth; Brazil
New Five Dimensional Black Holes Classified by Horizon Geometry, and a Bianchi VI Braneworld
We introduce two new families of solutions to the vacuum Einstein equations
with negative cosmological constant in 5 dimensions. These solutions are static
black holes whose horizons are modelled on the 3-geometries nilgeometry and
solvegeometry. Thus the horizons (and the exterior spacetimes) can be foliated
by compact 3-manifolds that are neither spherical, toroidal, hyperbolic, nor
product manifolds, and therefore are of a topological type not previously
encountered in black hole solutions. As an application, we use the
solvegeometry solutions to construct Bianchi VI braneworld cosmologies.Comment: LaTeX, 20 pages, 2 figures Typographical errors corrected, and
references to printed matter added in favour of preprints where possibl
The Roosevelt – Rondon expedition marmoset (Mico marcai) : unveiling the conservation status of a data deficient species
The Roosevelt-Rondon Expedition marmoset, Mico marcai, was collected in 1914 and to date, all information on this species comes from three skins brought back by the Expedition and two additional skins collected in the 1990s. It is no surprise then that M.marcai has been classified as Data Deficient (DD). Given that Mico marcai’s suspected range sits on the path of the advancing Brazilian “Arc-of-Deforestation”, it is urgent that relevant data be collected to assess this taxon. Here we present the first comprehensive field data on the distribution, population size and threats on M. marcai with the goal of removing the species from the DD category. From 2012 to 2015, we surveyed for the species in 11 localities, in and around the Marmelos-Aripuanã interfluve, and estimated density using distance sampling on 10 transects. We also used spatial predictive modelling to project the amount of habitat that will be lost within its range in 18 years under different deforestation scenarios. We found marmosets in 14 localities and calculated its Extent of Occurrence to be 31,073 km2. We walked 271 km and detected 30 marmoset groups, allowing us to estimate their density to be 8.31 individuals/km2 and a total population of 258,217.71 individuals. By a “Business as usual” scenario, 20,181 km2 of habitat will be lost in three marmoset generations (~18 years), compromising 33% of the species’ range. Accordingly, M. marcai should be classified as globally Vulnerable under category A3c. Following our study, we propose the Amazonian marmosets, genus Mico, should undergo similar re-assessment as their ranges all fall in the path of the Arc-of-Deforestation.
Keywords: Amazonian marmosets, Conservation Status, Data Deficient, Habitat Loss, Southern Amazoni
Graded Poisson-Sigma Models and Dilaton-Deformed 2D Supergravity Algebra
Fermionic extensions of generic 2d gravity theories obtained from the graded
Poisson-Sigma model (gPSM) approach show a large degree of ambiguity. In
addition, obstructions may reduce the allowed range of fields as given by the
bosonic theory, or even prohibit any extension in certain cases. In our present
work we relate the finite W-algebras inherent in the gPSM algebra of
constraints to algebras which can be interpreted as supergravities in the usual
sense (Neuveu-Schwarz or Ramond algebras resp.), deformed by the presence of
the dilaton field. With very straightforward and natural assumptions on them
--like demanding rigid supersymmetry in a certain flat limit, or linking the
anti-commutator of certain fermionic charges to the Hamiltonian constraint-- in
the ``genuine'' supergravity obtained in this way the ambiguities disappear, as
well as the obstructions referred to above. Thus all especially interesting
bosonic models (spherically reduced gravity, the Jackiw-Teitelboim model etc.)\
under these conditions possess a unique fermionic extension and are free from
new singularities. The superspace supergravity model of Howe is found as a
special case of this supergravity action. For this class of models the relation
between bosonic potential and prepotential does not introduce obstructions as
well.Comment: 22 pages, LaTeX, JHEP class. v3: Final version, to appear in JHE
Quantum Pair Creation of Soliton Domain Walls
A large body of experimental evidence suggests that the decay of the false
vacuum, accompanied by quantum pair creation of soliton domain walls, can occur
in a variety of condensed matter systems. Examples include nucleation of charge
soliton pairs in density waves [eg. J. H. Miller, Jr. et al., Phys. Rev. Lett.
84, 1555 (2000)] and flux soliton pairs in long Josephon junctions. Recently,
Dias and Lemos [J. Math. Phys. 42, 3292 (2001)] have argued that the mass
of the soliton should be interpreted as a line density and a surface density,
respectively, for (2+1)-D and (3+1)-D systems in the expression for the pair
production rate. As the transverse dimensions are increased and the total mass
(energy) becomes large, thermal activation becomes suppressed, so quantum
processes can dominate even at relatively high temperatures. This paper will
discuss both experimental evidence and theoretical arguments for the existence
of high-temperature collective quantum phenomena
Costs in the Treatment of Schizophrenia in Adults Receiving Atypical Antipsychotics: An 11-Year Cohort in Brazil
Background: Schizophrenia is associated with significant economic burden. In Brazil, antipsychotics drugs, outpatient and hospital services are provided by the Brazilian National Health System for patients with schizophrenia. However, there are few studies that capture the cost of managing these patients within the Brazilian NHS. This is important to appraise different management approaches within universal healthcare systems. Objective: Describe the costs associated with the treatment of schizophrenia in adults receiving atypical antipsychotics in Brazil from 2000 to 2010 through real world data. Methods: We integrated three national databases for adult patients with schizophrenia receiving one or more atypical antipsychotics. Only direct medical costs were assessed as the perspective is a public payer. A multivariate log-linear regression model was performed to evaluate associations between costs and clinical and demographic variables. Results: 174,310 patients with schizophrenia were identified with mean (± SD) annual costs of USD 1,811.92 ± 284.39 per patient. Atypical antipsychotics accounted for 79.7% of the total cost, with a mean (± SD) annual cost per patient of USD 1,578.74 ± 240.40. Mean (± SD) annual costs per patient of psychiatric hospitalization were USD 2,482.90 ± 302.92 and outpatient psychiatric care was USD 862.96 ± 160.18. Olanzapine was used by 47.7% of patients and represented 62.8% of the total cost of atypical antipsychotics. Patients who used clozapine had the highest mean annual cost per patient regarding outpatient psychiatric care and psychiatric hospitalization. Conclusions: Atypical antipsychotics were responsible for the majority of the schizophrenia treatment cost, and psychiatric hospitalization costs were the highest mean annual cost per patient. As a result, authorities should ensure good quality of use of atypical antipsychotic and encourage outpatient psychiatric care over psychiatric hospitalization where possible
Prevalence, predictors, and prognostic implications of residual impairment of functional capacity after transcatheter aortic valve implantation
Background: Patients with degenerative aortic stenosis (AS) referred for transcatheter aortic valve implantation (TAVI) typically have advanced cardiac and vascular adverse remodeling and multiple comorbidities and, therefore, might not recover a normal functional capacity after valve replacement. We sought to investigate the prevalence, the predictors, and the prognostic impact of residual impairment of functional capacity after TAVI.
Methods and results: Out of 790 patients undergoing TAVI with impaired functional capacity (NYHA II–IV
Estudo comparativo entre as soluções de manitol, picossulfato de sódio e fosfato monobásico e dibásico de sódio no preparo de cólon para colonoscopia
PURPOSE: Colonoscopy plays an essential role in the therapeutic and diagnostic approach in various colonic pathologies, the aim of the present study was to compare three solutions and their efficacy for the bowel preparation in adult patients submitted to elective colonoscopy. METHODS: Sixty patients were randomly divided into three groups of 20 each. Each group was submitted to a bowel preparation with one of the following solutions: 10% manitol, sodium picosulphate or sodium phosphate. The parameters evaluated were: taste, tolerance, associated side effects and quality of cleansing. Postural blood pressure and pulse rate as well as serum sodium, potassium, calcium and phosphate were compared. RESULTS: Sodium phosphate and 10% manitol solutions provided superior results in terms of colon cleansing compared to sodium picosulphate solution. All serum electrolytes evaluated were significantly altered in the three groups, without important clinical signs. DISCUSSION: High levels of serum phosphate were the most striking alteration in patients prepared with sodium phosphate solution, again with no clinical signs. Variations related to blood pressure and pulse rate suggested contraction of intravascular volume, with no clinical effects. CONCLUSION: Sodium phosphate and 10% manitol solutions are equivalent in providing good quality colon cleansing, with no significant side effects that could compromise the procedure.INTRODUÇÃO: A colonoscopia é exame fundamental na avaliação das doenças do cólon e na abordagem terapêutica de determinado grupo de patologias. O preparo intestinal é obrigatório para a realização das colonoscopias eletivas, e a qualidade encontra-se relacionada ao sucesso do procedimento. Comparou-se três soluções para limpeza anterógrada do cólon em pacientes adultos, submetidos à colonoscopia. METODOS: Sessenta pacientes foram distribuídos em três grupos de vinte. Cada grupo realizou o preparo do cólon com uma das três soluções estudadas: manitol a 10% (MN), picossulfato sódico (PS) e fosfato monobásico e dibásico de sódio (NaP). O sabor, a tolerância, os efeitos colaterais, os custos e a qualidade de limpeza do preparo foram avaliados. Frequência cardíaca e pressão arterial sistêmica foram analisados. Variações dos eletrólitos foram dosados antes e após o preparo. RESULTADOS: Os resultados foram semelhantes em relação aos efeitos colaterais. O sabor da solução de NaP não chegou a comprometer a sua aceitação. DISCUSSÃO: Soluções de NaP e MN proporcionaram resultados superiores tanto em qualidade de limpeza colônica, como em relação aos custos, quando comparadas à solução de PS. CONCLUSÃO: Comparados os três, os eletrólitos avaliados apresentaram diferenças significativas, sendo a hiperfosfatemia dos pacientes com a solução de NaP, a mais importante
A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles
In recent years, there has been a dramatic increase in the use of unmanned
aerial vehicles (UAVs), particularly for small UAVs, due to their affordable
prices, ease of availability, and ease of operability. Existing and future
applications of UAVs include remote surveillance and monitoring, relief
operations, package delivery, and communication backhaul infrastructure.
Additionally, UAVs are envisioned as an important component of 5G wireless
technology and beyond. The unique application scenarios for UAVs necessitate
accurate air-to-ground (AG) propagation channel models for designing and
evaluating UAV communication links for control/non-payload as well as payload
data transmissions. These AG propagation models have not been investigated in
detail when compared to terrestrial propagation models. In this paper, a
comprehensive survey is provided on available AG channel measurement campaigns,
large and small scale fading channel models, their limitations, and future
research directions for UAV communication scenarios
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