3,364 research outputs found
Photon deflection by a Coulomb field in noncommutative QED
In noncommutative QED photons present self-interactions in the form of triple
and quartic interactions. The triple interaction implies that, even though the
photon is electrically neutral, it will deflect when in the presence of an
electromagnetic field. If detected, such deflection would be an undoubted
signal of noncommutative space-time. In this work we derive the general
expression for the deflection of a photon by any electromagnetic field. As an
application we consider the case of the deflection of a photon by an external
static Coulomb field.Comment: 07 pages, some typos corrected, accepted for publication in JP
Influencia da embalagem e condicoes de armazenamento na longevidade de sementes florestais.
Permite conhecer as condicoes de embalagens de armazenamento que proporcionem maior longevidade das sementes de angico (Anadenanthera macrocarpa (Benth) Brenan, Pau d'arco (Tabebuia impetiginosa Mart) e imbirucu (Pseudobombax simpliciflolium A. Robyns)
Sustainability assessment of an oil palm farm through the implementation of an integrated indicators system.
Sustainability assessment of an oil palm farm through the implementation of an integrated indicators system.
Rural establishments environmental management and insertion in production chains of oleaginous crops for biofuels.
Building upon a set of socio-environmental impact assessments carried out in five rural territories across the country, regarding the context of increasing demand for oleaginous crops for biofuels production, this study presents the sustainability assessment of rural establishments in those territories, aiming at checking the impact results against current local agricultural settings. The main results point out that, in general, the ecological dimensions of sustainability, such as Landscape Ecology and Atmosphere, Water, and Soil quality indicators, show adequate field conditions, seemingly not yet negatively affected by inputs and natural resources pressure increases, predicted as important potential impacts. On the other hand, most valuable positive consequences expected from the socio-environmental impact assessments, such as improved Socio-cultural Values and Management & Administration indicators, are still opportunities to be realized, if sustainable local rural development is to occur under the emerging agro-energy scenario
Synthesis and characterization of oxidized bacterial cellulose through electrochemical methods: its biodegradability and potential as hemostatic material
Bacterial cellulose (BC) is a biocompatible material with high purity, high crystallinity, high degree of polymerization and high-water content [1,2]. It could be applied in several fields, being the biomedical field the most relevant to this work where biodegradability is a key requirement. BC may be chemically modified through its hydroxyl groups, e.g., by oxidation, becoming reabsorbable and acquiring new features, such as hemostatic behaviour. Oxidation of BC membranes was achieved through electrolysis using tetramethylpiperidine-1-oxyl (TEMPO) radical. TEMPO is able to perform selective oxidation of the primary hydroxyl groups, meaning that only C6 is oxidized into carboxyl groups [3].
BC membranes were characterized by FT-IR, SEM, XRD and 13C-NMR. The degree of oxidation was evaluated by titration of the carboxyl groups and the hemostatic behaviour was investigated through whole blood coagulation tests. Both in vitro and in vivo biodegradability of oxidized membranes was evaluated. In vitro biodegradability was assessed in ultra-pure water after 3, 7, 14 and 63 days of incubation while in vivo biodegradability was studied in a rat model, for 3, 14 and 56 days.
FT-IR spectra showed an increase on the absorption band around 1628 cm-1 attributed to the carboxylic acid vibration, as compared to non-oxidized membranes, revealing the formation of carboxylic acid groups [4]. SEM images revealed that the morphology of the membranes was not changed by the oxidation [5]. XRD patterns for all the oxidized samples were very similar to non-oxidized ones, suggesting that the crystal structure was preserved [6]. 13C-RMN results showed that the signal around 62 ppm corresponding to superficial C6 primary hydroxyl group decreased after the oxidation, while the peak around 174.6 ppm assigned to carboxylate groups appeared after oxidation, confirming the selective oxidation of C6 [7]. In vitro results showed that almost no degradation occurred on non-oxidized membranes demonstrating the relevance of the oxidation on the improvement on BC biodegradability. The hemostatic behaviour of the membranes evaluated through the whole blood clotting times assay demonstrated that, contrarily to non-oxidized membranes, the oxidized ones exhibited hemostatic activity [8]. In vivo biodegradability and biocompatibility of oxidized membranes was evaluated. Membranes were implanted subcutaneously and the inflammatory response was studied. The obtained results showed that there were no microscopic evidences of inflammation and even after 56 days of implantation, the oxidized membranes did not degrade completely. Nevertheless, oxidized membranes revealed good biocompatibility [9].info:eu-repo/semantics/publishedVersio
Polinização da abóbora (Cucurbita pepo L.): comunidade de abelhas, em sistemas orgânicos e convencionais de produção no Distrito Federal.
Speed and pressure of handwriting as critical issues of the contemporary age: A research in Italian students in early literacy
Among the present critical issues that pedagogy and special teaching have to
deal with it is possible to notice the contrast between writing and technology,
up to the pertinent field of prevention and observation of dysgraphies. The
authors present in the following article a study conducted in Italy aimed at
evaluating writing, specifically in the speed and pressure parameters in early
literacy using NeuroScript Movalyzer Software. The aim is to implement
suitable research paths to support the dissemination of observation procedures
and inclusive teaching practices, capable of enhancing the fluidity of writing
by all students
Pseudohypoparathyroidism type I-b with neurological involvement is associated with a homozygous PTH1R mutation
Pseudohypoparathyroidism type 1b (PHP1b) is characterized by hypocalcemia, hyperphosphatemia, increased levels of circulating parathyroid hormone (PTH), and no skeletal or developmental abnormalities. The goal of this study was to perform a full characterization of a familial case of PHP1b with neurological involvement and to identify the genetic cause of disease. The initial laboratory profile of the proband showed severe hypocalcemia, hyperphosphatemia and normal levels of PTH, which was considered to be compatible with primary hypoparathyroidism. With disease progression the patient developed cognitive disturbance, PTH levels were found to be slightly elevated and a picture of PTH resistance syndrome seemed more probable. The diagnosis of PHP1b was established after the study of family members and blunted urinary cAMP results were obtained in a PTH stimulation test. Integration of whole genome genotyping and exome sequencing data supported this diagnosis by revealing a novel homozygous missense mutation in PTH1R (p.Arg186His) completely segregating with the disease. Here, we demonstrate segregation of a novel mutation in PTH1R with a phenotype of PHP1b presenting with neurological symptoms, but no bone defects. This case represents the extreme end of the spectrum of cognitive impairment in PTH dysfunction and defines a possible novel form of PHP1b resulting from the impaired interaction between PTH and PTH1R
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