1,696 research outputs found
Bounds on the cosmological abundance of primordial black holes from diffuse sky brightness: single mass spectra
We constrain the mass abundance of unclustered primordial black holes (PBHs),
formed with a simple mass distribution and subject to the Hawking evaporation
and particle absorption from the environment. Since the radiative flux is
proportional to the numerical density, an upper bound is obtained by comparing
the calculated and observed diffuse background values, (similarly to the Olbers
paradox in which point sources are considered) for finite bandwidths. For a
significative range of formation redshifts the bounds are better than several
values obtained by other arguments ; and they apply
to PBHs which are evaporating today.Comment: 20 pages, 5 figures, to appear in PR
Evaluation of Libraries and Informations Units: A Proposition to Adopt Participatory Research Techniques In Order To Build Management Tools
Introduction. We report an investigation designed to present a specific model to build management tools for libraries and information units. A management evaluation model is shown to be necessary, because these units are undergoing transformations more sharply than other organizations, therefore changes and strategies need to be monitored and controlled. Method. Questionnaires, interviews, meetings and documentary research were conducted with a researcher at Brasíia University, Brasília, Brazil. Participative methodology was used for data collection in order to get staffs commitment and involvement in the process of building management tools. Participative research showed important because its use helped participants to solve problems as well as to deal with control and management tolls. Analysis. Transcription of the interviews, recorded tape of meetings, documents and questionnaires tabulation formed the data for analysis. Principles of grounded theory were adopted, notably coding that allows recursive data analysis to be used to obtain the consensus from participants about what need to be measured. Results. It proved possible to build management tools for libraries and information units applying participatory techniques. The investigation resulted in a set of coherent and fully contextualized indicators for a selected information unit. Conclusions. Participatory techniques appear to be appropriated to enable managers and employees to handle information in order to solve problems. Commitment and involvement of participants were observed, and this is the most important finding of this investigation
Holographic Principle bounds on Primordial Black Hole abundances
The generalized Second Law of thermodynamics and the Holographic Principle
are combined to obtain the maximum mass of black holes formed inside a static
spherical box of size filled with radiation at initial temperature .
The final temperature after the formation of black holes is evaluated, and we
show that a critical threshold exists for the radiation to be fully consumed by
the process. We next argue that if some form of Holographic Principle holds,
upper bounds to the mass density of PBHs formed in the early universe may be
obtained. The limits are worked out for inflationary and non-inflationary
cosmological models. This method is independent of the known limits based on
the background fluxes (from cosmic rays, radiation and other forms of energy)
and applies to potentially important epochs of PBH formation, resulting in
quite strong constraints to .Comment: Latex file, 2 .ps figures. To appear in Classical and Quantum Gravit
Correlação entre distância genética e heterose para comprimento de panícula por cruzamento dialélico entre acessos de arroz (Oryza sativa L.) de base genética ampla.
O objetivo desse trabalho foi correlacionar os dados de distância genética de Rogers modificada por Wright e a heterose observada no caractere comprimento de panícula, um dos componentes de produtividade do arroz, dos 120 híbridos obtidos nesses cruzamentos
The design of a digital coincidence-detection trigger system for a RPC-based pet
A complex task for PET cameras is the design of an appropriate coincidence-detection trigger as it usually encompasses coincidences in a large number of channels and tight time specifications. Those requirements are even greater for a resistive plate chamber (RPC)-based detector technology as the time window specification is quite small (in the order of a few hundred picoseconds) and the number of coincidence-channels can be quite large (more than 100 in a large camera). In this work we discuss on-going work aimed at implementing the coincidence-detection algorithm inside a FPGA along with the necessary TDCs. The use of the developed solution in a first prototype of an RPC-based small animal PET and its scalability to the case of a human, all-body, PET, is discussed.info:eu-repo/semantics/publishedVersio
Collagenofibrotic Glomerulopathy: Three Case Reports in Brazil
<p>Abstract</p> <p>Background</p> <p>We are reporting the first Collagenofibrotic Glomerulopathy (CG) in South America. So, this collagen type III glomerulopathy is not limited to Japan but may be found throughout the world.</p> <p>Case Reports</p> <p>We describe three patients that presented some factors in common, such as sex, age and the presence of non-nephrotic proteinuria associated with microscopic hematuria. The findings with the immunofluorescence microscopy, of immunoglobulins, and components of the complement were usually negative. The picrosyrius staining showed the presence of reddish material in the mesangium, when it was seen under standard microscopy; however, when it was seen with birefringence, it became greenish under polarized light, showed the collagen found in this area of the glomerulus. The identification of CG was made through electronic microscopic scanning, and curved and disorganized fibers were found.</p> <p>Conclusion</p> <p>These cases are the first from South America to be reported, and they are about an idiopathic renal disease that is not related to any specific races or locations. The reports contribute to a better understanding of this disease, which although not so prevalent, should be considered as an importantly differential diagnostic of cases of proteinuria.</p
Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System
Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.This work was financially supported by the project PTDC/CTM-NAN/3547/2014
(POCI-01-0145-FEDER-016639) funded by FEDER funds through the Programa Operacional Competitividade
e Internacionalização-COMPETE 2020 and Portuguese funds through FCT–Fundação para a Ciência e a
Tecnologia. A.P.S., B.C. and S.D.S. acknowledge FCT for the Ph.D. scholarships (SFRH/BD/137073/2018 and
SFRH/BD/145652/2019) and the contract under the Norma Transitória–DL57/2016/CP/CP1360/CT0013, respectively.
V.L. acknowledges her contract in the framework of the project NORTE-01-0247-FEDER-033399, funded by
FEDER funds through the Sistema de Incentivos à Investigação e Desenvolvimento Tecnológico (SI I&DT), Aviso
nº 03/SI/2017, Projetos em Co-promoção do Programa Interfac
Hydroxytamoxifen interaction with human erythrocyte membrane and induction of permeabilization and subsequent hemolysis
4-Hydroxytamoxifen (OHTAM) is the most active metabolite of the widely prescribed anticancer drug tamoxifen (TAM) used in breast cancer therapy. This work describes the effects of OHTAM on isolated human erythrocytes, using standardized test conditions, to check for a putative contribution to the TAM-induced hemolysis and to study basic mechanisms involved in the interaction of OHTAM with cell membranes. Incubation of isolated human erythrocytes with relatively high concentrations of OHTAM results in a concentration-dependent hemolysis, its hemolytic effect being about one-third of that induced by TAM. OHTAM-induced hemolysis is prevented by either [alpha]-tocopherol ([alpha]-T) or [alpha]-tocopherol acetate ([alpha]-TAc) and it occurs in the absence of oxygen consumption and hemoglobin oxidation, ruling out the oxidative damage of erythrocytes. However, OHTAM remarkably increases the osmotic fragility of erythrocytes, increasing the susceptibility of erythrocytes to hypotonic lysis. Additionally, the hemoglobin release induced by OHTAM is preceded by a rapid efflux of intracellular K+. Therefore, our data suggest that OHTAM-induced hemolysis does not contribute to TAM-induced hemolytic anemia and it is a much weaker toxic drug as compared with TAM. Moreover, at variance with the membrane disrupting effects of TAM, OHTAM promotes perturbation of the membrane's backbone region due to its strong binding to proteins with consequent formation of membrane paths of permeability to small solutes and retention of large solutes like hemoglobin, followed by osmotic swelling and cell lysis. The prevention of OHTAM-induced hemolysis by [alpha]-T and [alpha]-TAc is probably committed to the permeability sealing resulting from structural stabilization of membrane.http://www.sciencedirect.com/science/article/B6TCP-44B2835-2/1/29f8930b906a9b147f7df74b698fdbb
Seasonal variations of the nutritive value and phytotherapeutic potential of Cladium mariscus L. (Pohl.) targeting ruminant’s production
In our endeavor to identify salt-tolerant plants with potential veterinary uses in ruminants' production strategies, we focused on Cladium mariscus L. Pohl (sawgrass), due to its high total phenolic and tannin content, anti-radical properties, and ethnomedicinal uses. Aerial parts were collected along the year in Southern Portugal and evaluated for the nutritional profile and in vitro organic matter digestibility (IVOMD), aiming for its use as feed. Acetone extracts were appraised for total contents in phenolics (TPC), flavonoids (TFC), and tannins (CTC), as well as the chemical composition by HPLC-DAD and in vitro antioxidant and anti-inflammatory properties, targeting its exploitation as phytotherapeutic products. Sawgrass biomass has a limited nutritive value, due to its high neutral detergent fiber (NDF; 596-690 g kg-1 dry matter (DM)) and acid detergent fiber (ADF; 330-418 g kg-1 DM) contents, low crude protein (51.8-87.3 g kg-1 DM) and IVOMD (172-317 g kg-1 organic matter (OM)). Despite differences among seasons, the mineral profile was adequate. The extracts were rich in TPC (88-112 mg g-1), CTC (115-169 mg g-1), and TFC (18.5-20.2 mg g-1), and displayed significant antioxidant capacity, particularly in summer and autumn, whilst no seasonal influence was detected for anti-inflammatory properties (30% reduction of nitric oxide production). Eleven phenolics were quantified: chlorogenic, ferulic, and syringic acids were the most abundant, especially in the autumn sample. Overall, despite the low nutritional interest, sawgrass extracts hold the potential as a source of antioxidant and anti-inflammatory phenolic compounds.FCT: GreenVet-ALG-01-0145-FEDER-028876/ UIDB/04326/2020/ SFRH/BD/116604/2016/ CEECIND/00425/2017.info:eu-repo/semantics/publishedVersio
Caracterização da deleção do gene pgk em uma cepa vacinal geneticamente modificada de Brucella abortus.
Neste trabalho objetiva-se expressar o gene pgk de B. abortus para a caracterização da cepa vacinal geneticamente modificada de B. abortus, 2308Δpgk, e utilização da proteína PGK em testes sorológicos
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