In situ mineralogical-chemical analysis of Martian materials at landing/roving sites by active and passive remote sensing methods

Remote sensing of the Martian surface from the ground and from orbiting spacecraft has provided some first-order insight into the mineralogical-chemical composition and the weathering state of Martian surface materials. Much more detailed information can be gathered from performing such measurements in situ at the landing sites or from a rover in combination with analogous measurements from orbit. Measurements in the wavelength range of approximately 0.3 to 12.0 micrometers appear to be suitable to characterize much of the physical, mineralogical, petrological, and chemical properties of Martian surface materials and the weathering and other alteration processes that have acted on them. It is of particular importance to carry out measurements at the same time over a broad wavelength range since the reflectance signatures are caused by different effects and hence give different and complementing information. It appears particularly useful to employ a combination of active and passive methods because the use of active laser spectroscopy allows the obtaining of specific information on thermal infrared reflectance of surface materials. It seems to be evident that a spectrometric survey of Martian materials has to be focused on the analysis of altered and fresh mafic materials and rocks, water-bearing silicates, and possibly carbonates

Reductio ad absurdum como estratégia argumentativa. Um estudo de caso

Nos argumentos darwinianos, há uma tácita suposição da "explicabilidade" racional dos fenômenos naturais. A essa tarefa explicativa, em situações ejemplares da Origem das Espécies como a do argumento a favor da origem comum das raças de pombo doméstico (cap. I), a ser presentemente examinado, a reductio ad absurdum reveste-se de um alcance estratégico que excede o de mera aplicão de urna regra lógica inferencial e garante a "explicabilidade" dos fatos. Esse modo de argumentar serve de modo bastante eficaz áquelas suposições -de resto tão comuns ao raciocínio filosófico, como nos diz Ryle- em que carecemos do que seria urna "prova" direta a favor de urna determinada hipótese

O “AVESSO” E O “DIREITO” EM BUSCA DA RACIONALIDADE DA CIÊNCIA

Tradicionalmente, “racionalidade” é o exercício da faculdade superior de
 conhecimento e ação, “razão”, e a propriedade dos produtos resultantes desse exercício, “razões”. Buscar o significado da “racionalidade” pressupõe perscrutá-la “em ação” – não há como “sair fora” do racional para encontrá-la. O valor de face que apresenta é o lado “direito” de sua tessitura. Mas a condição (auto)reguladora da racionalidade demanda que
 se lhe busque também o “avesso”, lado nem sempre visível das costuras que dão a feitura do “direito”. Em face da contextualidade da racionalidade “em ação”, cabe examinar essa distinção através de dois “casos exemplares”: a visão aristotélica de racionalidade e a argumentação de Charles Darwin na Origem das espécies. De um lado, encontramos uma
 outra vertente da Retórica aristotélica, mostrando a interpenetração de demonstrar e persuadir no “avesso” da racionalidade; de outro, encontramos no “avesso” da argumentação científica darwiniana a essencialidade de procedimentos ditos “retóricos”. Cruzam-se as fronteiras.
 
 Palavras-chave: Racionalidade, argumentação, retórica, ciência, Aristóteles, Charles Darwin

Embryogenesis in microspore culture of Vitis subspecies

Embryoid structures showing epidermal layers have been regenerated from isolated Vitis microspores. Experiments were carried out on 8 genotypes of Vitis including different donor plant growth conditions, chilling of microspores (4 °C), heat shock (35 °C) and colchicine exposure (10, 25 and 50 mg/l) as induction treatments and incubation of the cultures on 87 different solid and liquid NN and LS media. The reactions of the cultured microspores included enlargement and thickening of the exine, formation of microcalli, calli, globular proembryos and embryoid structures displaying cell differentiation. Callus formation took place mainly on solid LS media with 3 % or 12 % sucrose, whereas most of the embryoids developed on NN media with 3 % sucrose. Both, callus and embryoid formation, were promoted by colchicine treatment. 8 months after transfer of calli and embryoids to subculture media, 4 embryoids still showed cell proliferation

Historia, naturaleza e historia de la naturaleza

Contemporáneamente, al hablar de "historia" existe una tendencia a identificarla con el estudio de hechos humanos, distinguiéndolos de los hechos naturales, exhibiendo ambos diferentes modelos explicativos. Contrariando esta tendencia, quiero retomar el tema de las relaciones entre historia de los "hechos humanos" e historia de los "hechos naturales" desde un ángulo bastante más específico, es decir, de una "Historia de la Naturaleza"

Pay What You Want as a Marketing Strategy in Monopolistic and Competitive Markets

Pay What You Want (PWYW) can be an attractive marketing strategy to price discriminate between fair-minded and selfish customers, to fully penetrate a market without giving away the product for free, and to undercut competitors that use posted prices. We report on laboratory experiments that identify causal factors determining the willingness of buyers to pay voluntarily under PWYW. Furthermore, to see how competition affects the viability of PWYW, we implement markets in which a PWYW seller competes with a traditional seller. Finally, we endogenize the market structure and let sellers choose their pricing strategy. The experimental results show that outcome-based social preferences and strategic considerations to keep the seller in the market can explain why and how much buyers pay voluntarily to a PWYW seller. We find that PWYW can be viable in isolation, but it is less successful as a competitive strategy because it does not drive traditional posted-price sellers out of the market. Instead, the existence of a posted-price competitor reduces buyers’ payments and prevents the PWYW seller from fully penetrating the market. If given the choice, the majority of sellers opt for setting a posted price rather than a PWYW pricing. We discuss the implications of these results for the use of PWYW as a marketing strategy

Land-use impacts of Brazilian wind power expansion

While wind power is a low-carbon renewable energy technology with relatively little land footprint, the necessary infrastructure expansion still has land-related environmental impacts. Brazil has seen more than a ten-fold increase in wind power capacity in the last decade. However, little is known about these impacts of wind power generation in Brazil compared to other world regions, although Brazilian wind power infrastructure is concentrated in the least protected ecosystems that are prone to degradation, desertification and species extinction. This study focuses on land-use impacts of past wind power generation development in four Brazilian federal states, covering 80% of the country's installed capacity. We assessed their spatial installation patterns, associated land-use and land cover change in the period before installation until 2018, and potential alternative installation locations, using a detailed wind turbine location database in combination with a high-resolution land-use and land cover map. In contrast to wind parks built in Europe, we found that 62% of the studied wind park area was covered by native vegetation and coastal sands. Overall, 3.2% of the total wind cluster area was converted from native vegetation to anthropogenic use. Wind parks installed mainly on native vegetation, on average, underwent higher land-use change compared to other wind parks. As Brazil intends to more than double its current wind power capacities by 2029, we explored possibilities to reduce environmental risks due to wind power expansion. We showed that this is feasible by integrating wind parks into human-altered areas, as sufficient wind resources there are available

Calibrating Convective properties of Solar-like Stars in the Kepler Field of View

Stellar models generally use simple parametrizations to treat convection. The most widely used parametrization is the so-called "Mixing Length Theory" where the convective eddy sizes are described using a single number, \alpha, the mixing-length parameter. This is a free parameter, and the general practice is to calibrate \alpha using the known properties of the Sun and apply that to all stars. Using data from NASA's Kepler mission we show that using the solar-calibrated \alpha is not always appropriate, and that in many cases it would lead to estimates of initial helium abundances that are lower than the primordial helium abundance. Kepler data allow us to calibrate \alpha for many other stars and we show that for the sample of stars we have studied, the mixing-length parameter is generally lower than the solar value. We studied the correlation between \alpha and stellar properties, and we find that \alpha increases with metallicity. We therefore conclude that results obtained by fitting stellar models or by using population-synthesis models constructed with solar values of \alpha are likely to have large systematic errors. Our results also confirm theoretical expectations that the mixing-length parameter should vary with stellar properties.Comment: 16 pages, 4 figures, accepted for publication in ApJ

Does shear wave ultrasound independently predict axillary lymph node metastasis in women with invasive breast cancer?

Shear wave elastography (SWE) shows promise as an adjunct to greyscale ultrasound examination in assessing breast masses. In breast cancer, higher lesion stiffness on SWE has been shown to be associated with features of poor prognosis. The purpose of this study was to assess whether lesion stiffness at SWE is an independent predictor of lymph node involvement. Patients with invasive breast cancer treated by primary surgery, who had undergone SWE examination were eligible. Data were retrospectively analysed from 396 consecutive patients. The mean stiffness values were obtained using the Aixplorer(®) ultrasound machine from SuperSonic Imagine Ltd. Measurements were taken from a region of interest positioned over the stiffest part of the abnormality. The average of the mean stiffness value obtained from each of two orthogonal image planes was used for analysis. Associations between lymph node involvement and mean lesion stiffness, invasive cancer size, histologic grade, tumour type, ER expression, HER-2 status and vascular invasion were assessed using univariate and multivariate logistic regression. At univariate analysis, invasive size, histologic grade, HER-2 status, vascular invasion, tumour type and mean stiffness were significantly associated with nodal involvement. Nodal involvement rates ranged from 7 % for tumours with mean stiffness <50 kPa to 41 % for tumours with a mean stiffness of >150 kPa. At multivariate analysis, invasive size, tumour type, vascular invasion, and mean stiffness maintained independent significance. Mean stiffness at SWE is an independent predictor of lymph node metastasis and thus can confer prognostic information additional to that provided by conventional preoperative tumour assessment and staging

Does social context impact metacognition? Evidence from stereotype threat in a visual search task

While recent studies have emphasized the role of metacognitive judgments in social interactions, whether social context might reciprocally impact individuals’ metacognition remains an open question. It has been proposed that such might be the case in situations involving stereotype threat. Here, we provide the first empirical test of this hypothesis. Using a visual search task, we asked participants, on a trial-by-trial basis, to monitor the unfolding and accuracy of their search processes, and we developed a computational model to measure the accuracy of their metacognition. Results indicated that stereotype threat enhanced metacognitive monitoring of both outcomes and processes. Our study thus shows that social context can actually affect metacognition