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Search Results: 1 - 10 of 606277 matches for " Sarah A. N.;Costa "
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Determina??o espectrofotométrica simultanea de cobre e ferro em álcool etílico combustível com reagentes derivados da ferroína
Teixeira, Leonardo S. G.;Brasileiro, Jo?o F.;Borges Jr., Mário M.;Cordeiro, Paulo W. L.;Rocha, Sarah A. N.;Costa, Antonio C. Spínola;
Química Nova , 2006, DOI: 10.1590/S0100-40422006000400020
Abstract: in the present work three ferroin reagents were studied for the simultaneous spectrophotometric determination of iron and copper: 1,10-phenanthroline, 2,2'-bipyridine and 2,4,6-tri(2-pyridyl)-1,3,5-triazine. effect of ph, conditions, order reagent addition, interferences, amount of reagents, lineal range, sensitivity and stability of each system were compared. the 2,4,6-tri(2-pyridyl)-1,3,5-triazine can be used for determination of iron in the presence of copper with a detection limit of 5 μg l-1 and coefficient of variation of 2.0%; however it was not possible to determine directly copper in the presence of iron with this reagent. 1,10-phenanthroline can be used for simultaneous determination of the metallic ions with detection limits of 7 and 8 mg l-1 and coefficients of variation of 1.8 and 2.3% in the determination of iron and copper, respectively. the results showed also that 2,2'-bipyridine can be used for simultaneous determination of the metallic ions with detection limits of 11 and 32 μg l-1 and coefficients of variation of 1.9 and 2.5% in the determination of iron and copper, respectively. the reagents were used for spectrophotometric determination of iron and copper in ethanol fuel.
Lagged Coherence of Photon Emissions and Spectral Power Densities between the Cerebral Hemispheres of Human Subjects during Rest Conditions: Phase Shift and Quantum Possibilities  [PDF]
J. N. Costa, B. T. Dotta, M. A. Persinger
World Journal of Neuroscience (WJNS) , 2016, DOI: 10.4236/wjns.2016.62015
Abstract: Photon counts about 15 cm from the left and right sides of the head while subjects sat quietly during baseline conditions within a hyper-dark chamber were measured by photomultiplier units. Lag/lead analyses for photon emissions between the two hemispheres indicated a weak but statistically significant correlation between the amplitude fluctuations that were separated by about 800 to 900 ms. Analyses of the spectral power densities of photon amplitude variations from the left and right hemispheres revealed peak values between 2 and 3 Hz which were equivalent to a difference of about 900 ms. The radiant flux densities were estimated to be in the order of 10?12?W?m?2?and to include the equivalence of about 107?neurons. Our calculations, which accounted for the small magnitude of the strength of the interhemispheric coefficients, suggest that the coherence could be strongly correlated with processes associated with the unmyelinated axons with diameters between 400 to 800 nm, the visible wavelengths, within the corpus callosum. When the ratio of the phase shift was applied to the Aharanov-Bohm equation, the time required for a photon-related electron to be within a cerebral magnetic field was the same duration as a single orbit of an electron and a photon’s traversal latency across a neuronal plasma membrane. We suggest that the peak photon decoherence between the two cerebral hemispheres may reveal a neuronal-quanta substrate to the conditions associated with consciousness.
Differential Spontaneous Photon Emissions from Cerebral Hemispheres of Fixed Human Brains: Asymmetric Coupling to Geomagnetic Activity and Potentials for Examining Post-Mortem Intrinsic Photon Information  [PDF]
Justin N. Costa, Nicolas Rouleau, Michael A. Persinger
Neuroscience & Medicine (NM) , 2016, DOI: 10.4236/nm.2016.72006
Abstract: The emissions of biophotons have been considered a ubiquitous property of living systems and their components. We measured the “spontaneous” photon emissions from fixed whole and sectioned human brains within hyper-dark settings. Significant differences in photon counts were measured from different spatial planes. The flux densities were in the order of 2 × 10-12 W per m2. The right hemispheres but not the left hemispheres displayed more photon emissions whose spectral power density profiles exhibited a conspicuous amplitude peak between 7.9 and 8 Hz. Brains measured in the hyperdark (~10-12 W·m2) after removal from the typical lighting of the laboratory emitted more photons than those that had been maintained in the hyperdark for one week. The significant correlation between the numbers of photons emitted from the left hemisphere (but not the right) and global geomagnetic activity also exhibited energy equivalence between the photon flux densities and the geomagnetic shift within the cerebral volumes. These results indicate that what has been assumed to be fixed unresponsive human brain tissue still emits small numbers of photons that may be residuals from ambient light and can potentially interact with global geomagnetic activity. The medical implications for post-mortem intrinsic photonic information based upon the anisotropic microstructures within the hemispheres of the human cerebrum are discussed.
Evaluating the Signal Processing Capacities of Post-Mortem Cerebral Cortical Tissue by Artificial Phototransduction of Dynamic Visual Stimuli  [PDF]
Nicolas Rouleau, Justin N. Costa, Michael A. Persinger
Open Journal of Biophysics (OJBIPHY) , 2017, DOI: 10.4236/ojbiphy.2017.71001
Abstract: The signal processing function of human cerebral cortical tissues is determined by the regional cytoarchitectures distributed throughout the brain. Based upon this assumption, we pursued the hypothesis that residual microstructure within the primary and associative visual cortices of a fixed, post-mortem whole human brain would process electrical signals differentially. To this end, we designed and engineered a very simple brain-photocell interface. Photostimuli, presented as either periodic flashes or as dynamic visual images, were transduced by photocells attached to the optic nerve of a post-mortem human brain specimen. The novel approach revealed that microvolt fluctuations within the primary and associative visual cortices could be discriminated. Simple light-dark discrimination was noted for the primary visual area (BA17) whereas within the right occipito-parietal cortices of the dorsal visual stream (BA19, BA7), spectral power of microvolt fluctuations could discriminate moving visual stimuli from those which were non-moving. Discriminant analysis classified movement represented within the right parietal lobe with 80% success. Together, the results suggest that artificially generated electrical signals are processed differentially by alternative cortical regions in the post-mortem brain.
The Sound of Danger: Threat Sensitivity to Predator Vocalizations, Alarm Calls, and Novelty in Gulls
Sarah A. MacLean, David N. Bonter
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082384
Abstract: The threat sensitivity hypothesis predicts that organisms will evaluate the relative danger of and respond differentially to varying degrees of predation threat. Doing so allows potential prey to balance the costs and benefits of anti-predator behaviors. Threat sensitivity has undergone limited testing in the auditory modality, and the relative threat level of auditory cues from different sources is difficult to infer across populations when variables such as background risk and experience are not properly controlled. We experimentally exposed a single population of two sympatric gull species to auditory stimuli representing a range of potential threats in order to compare the relative threat of heterospecific alarm calls, conspecific alarms calls, predator vocalizations, and novel auditory cues. Gulls were able to discriminate among a diverse set of threat indicators and respond in a graded manner commensurate with the level of threat. Vocalizations of two potential predators, the human voice and bald eagle call, differed in their threat level compared to each other and to alarm calls. Conspecific alarm calls were more threatening than heterospecfic alarm calls to the larger great black-backed gull, but the smaller herring gull weighed both equally. A novel cue elicited a response intermediate between known threats and a known non-threat in herring gulls, but not great black-backed gulls. Our results show that the relative threat level of auditory cues from different sources is highly species-dependent, and that caution should be exercised when comparing graded and threshold threat sensitive responses.
Functional insights into modulation of BKCa channel activity to alter myometrial contractility
Ramón A. Lorca,Sarah K. England
Frontiers in Physiology , 2014, DOI: 10.3389/fphys.2014.00289
Abstract: The large-conductance voltage- and Ca2+-activated K+ channel (BKCa) is an important regulator of membrane excitability in a wide variety of cells and tissues. In myometrial smooth muscle, activation of BKCa plays essential roles in buffering contractility to maintain uterine quiescence during pregnancy and in the transition to a more contractile state at the onset of labor. Multiple mechanisms of modulation have been described to alter BKCa channel activity, expression, and cellular localization. In the myometrium, BKCa is regulated by alternative splicing, protein targeting to the plasma membrane, compartmentation in membrane microdomains, and posttranslational modifications. In addition, interaction with auxiliary proteins (i.e., β1- and β2-subunits), association with G-protein coupled receptor signaling pathways, such as those activated by adrenergic and oxytocin receptors, and hormonal regulation provide further mechanisms of variable modulation of BKCa channel function in myometrial smooth muscle. Here, we provide an overview of these mechanisms of BKCa channel modulation and provide a context for them in relation to myometrial function.
Public Imaging Surveys: Scientific Opportunities
L. A. N. da Costa
Physics , 2001,
Abstract: The start of operation of several large-aperture telescopes has motivated several groups around the world to conduct deep large imaging surveys, complementing other wide-area but shallower surveys. A special class of imaging surveys are the public ones such as those being conducted by the ESO Imaging Survey (EIS) project established with the primary objective of providing to the ESO community large datasets from which samples can be drawn for VLT programs. To date several surveys have been carried out providing multi-passband optical data over relatively large areas to moderate depth, deep optical/infrared surveys of smaller fields as well as observations of a large number of selected stellar fields. These surveys have produced a large amount of well-defined datasets with known limits from which a variety of data products have been extracted and distributed. The goal of the present contribution is to give an overview of the EIS project, to present the end-to-end survey system being developed by this program and to highlight the effort being made to standardize procedures, to build software tools to assess the quality of the derived products and to explore the available datasets in a systematic and consistent way to search for astronomical objects of potential scientific interest.
Bevacizumab Related Hypertension and Reversible Posterior Leukoencephalopathy Syndrome in Gynecologic Malignancies: A case Control Study  [PDF]
Sarah N. Cross, Elena S. Ratner, Dan A. Silasi, Alessandro D. Santin, Masoud Azodi, Thomas J. Rutherford, Peter E. Schwartz
Journal of Cancer Therapy (JCT) , 2011, DOI: 10.4236/jct.2011.22028
Abstract: Background: Bevacizumab is increasingly being used in the treatment of gynecologic malignancies, but has significant side-effects including hypertension and reversible posterior leukoencephalopathy (RPLS), which must be recognized by the gynecologic oncologist. Methods: A 26-month institutional retrospective review of bevacizumab in the treatment of gynecologic malignancies. Patients were grouped according to whether they had bevacizumab-related hypertension (defined as at least a grade one hypertensive toxicity) or not. There were no differences in patient demographics between the groups. Risk factors for developing bevacizumab-related hypertension were assessed using t-tests, Wilcoxon rank sum test and Fisher’s exact test. Results: Our group has treated 45 patients with bevacizumab. Fifteen (33%) patients had a pre-existing diagnosis of hypertension, 12 (80%) of whom had at least one elevated blood pressure during treatment. The 30 (67%) patients who did not have a pre-existing diagnosis of hypertension still had a high incidence of bevacizumab-related elevated blood pressure (14, 47%). The majority of patients (26, 58%) had at least one therapy cycle complicated by hypertension. Patients who experienced bevacizumab-related hypertension were significantly more likely than not to have a history of hypertension (odds ratio of 4.6, 95% CI 1.1-19.6). There was a 4.4% incidence of reversible posterior leukoencephalopathy. Patients with age equal to or greater than 75 years, stage IV disease, and creatinine elevations greater than or equal to 1.4 mg/dL were significantly more likely to develop bevacizumab-related hypertension. Other factors such as numbers of prior chemotherapies, cycles of bevacizumab, BMI, cancer site, and histology were not significantly associated with bevacizumab-related hypertension. Conclusions: Hypertension is a problem for patients on bevacizumab whether or not they have a pre-existing diagnosis. However, those with a history of hypertension were significantly more likely to have bevacizumab-related hypertension.
Alimentos e Nutri??o , 2008,
Abstract: A presente pesquisa tem como finalidade esclarecer as possíveis rela es, articulando teoricamente a Educa o em Saúde e a Pesquisa Qualitativa. Para tanto, apresenta uma retrospectiva histórica do campo da Educa o em Saúde sinaliza a situa o presente desse campo e complementa sua fundamenta o teórica nos pressupostos de Paulo Freire. A seguir s o tecidas considera es relativas a Pesquisa Qualitativa esclarecendo suas concep es, alcance e etapas.A partir de ent o, ficam afirmadas rela es possíveis entre o campo da Educa o em Saúde e o da Pesquisa Qualitativa, uma vez que ambas se preocupam com os contornos científico, popular e social.
The Jigsaw Puzzle of Teaching Writing in English Now Resolved with Self-Regulated Learning  [PDF]
óscar García Gaitero, óscar Costa Rormán, José Julio Real García
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.616176
Abstract: Society is experiencing growth and profound changes. Among other aspects, we take into account the rapid development of new technologies, which requires new approaches and methodological principles for handling, processing and information processing. All students have the power and ability to become smart if learners learn and use techniques of self-regulation. Thanks to the self-regulated learning cyclic program, students evaluate themselves and establish objectives, strategies and adjust according to their needs and specific learning context, thus improving their outcomes. This article is a reflection based in a wide bibliographic study attempts to shed light on the importance of self-regulated learning in bilingual contexts.
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