Responsibility effects in decision making under risk

We systematically explore decision situations in which a decision maker bears responsibility for somebody else's outcomes as well as for her own in situations of payoff equality. In the gain domain we confirm the intuition that being responsible for somebody else's payoffs increases risk aversion. This is however not attributable to a 'cautious shift' as often thought. Indeed, looking at risk attitudes in the loss domain, we find an increase in risk seeking under responsibility. This raises issues about the nature of various decision biases under risk, and to what extent changed behavior under responsibility may depend on a social norm of caution in situations of responsibility versus naive corrections from perceived biases. To further explore this issue, we designed a second experiment to explore risk-taking behavior for gain prospects offering very small or very large probabilities of winning. For large probabilities, we find increased risk aversion, thus confirming our earlier finding. For small probabilities however, we find an increase of risk seeking under conditions of responsibility. The latter finding thus discredits hypotheses of a social rule dictating caution under responsibility, and can be explained through flexible self-correction models predicting an accentuation of the fourfold pattern of risk attitudes predicted by prospect theory. An additional accountability mechanism does not change risk behavior, except for mixed prospects, in which it reduces loss aversion. This indicates that loss aversion is of a fundamentally different nature than probability weighting or utility curvature. Implications for debiasing are discussed.

Fathoming solar effects in Neptune’s atmosphere

Long-duration observations of Neptune’s brightness in two visible wavelengths provide a disk-averaged estimate of its atmospheric aerosol. Brightness variations were previously associated with the 11-year solar cycle, through solar-modulated mechanisms linked with either ultra-violet (UV) or galactic cosmic ray (GCR) effects on atmospheric particles. Here we use a recently extended brightness dataset (1972-2014), with physically realistic modelling to show that rather than alternatives, UV and GCR are likely to be modulating Neptune’s atmosphere in combination. The importance of GCR is further supported by the response of Neptune's atmosphere to an intermittent 1.5 to 1.9 year periodicity, which occurred preferentially in GCR (not UV) during the mid-1980s. This periodicity was detected both at Earth, and in GCR measured by Voyager 2, then near Neptune. A similar coincident variability in Neptune’s brightness suggests nucleation onto GCR ions. Both GCR and UV mechanisms may occur more rapidly than the subsequent atmospheric particle transport.

Understanding three-dimensional effects in polarized observations with the ground-based ADMIRARI radiometer during the CHUVA campaign

Measurements of down-welling microwave radiation from raining clouds performed with the Advanced Microwave Radiometer for Rain Identification (ADMIRARI) radiometer at 10.7-21-36.5 GHz during the Global Precipitation Measurement Ground Validation ""Cloud processes of the main precipitation systems in Brazil: A contribution to cloud resolving modeling and to the Global Precipitation Measurement"" (CHUVA) campaign held in Brazil in March 2010 represent a unique test bed for understanding three-dimensional (3D) effects in microwave radiative transfer processes. While the necessity of accounting for geometric effects is trivial given the slant observation geometry (ADMIRARI was pointing at a fixed 30 elevation angle), the polarization signal (i.e., the difference between the vertical and horizontal brightness temperatures) shows ubiquitousness of positive values both at 21.0 and 36.5 GHz in coincidence with high brightness temperatures. This signature is a genuine and unique microwave signature of radiation side leakage which cannot be explained in a 1D radiative transfer frame but necessitates the inclusion of three-dimensional scattering effects. We demonstrate these effects and interdependencies by analyzing two campaign case studies and by exploiting a sophisticated 3D radiative transfer suited for dichroic media like precipitating clouds.

CD28 Exerts Protective and Detrimental Effects in a Pulmonary Model of Paracoccidioidomycosis

T-cell immunity has been claimed as the main immunoprotective mechanism against Paracoccidioides brasiliensis infection, the most important fungal infection in Latin America. As the initial events that control T-cell activation in paracoccidioidomycosis (PCM) are not well established, we decided to investigate the role of CD28, an important costimulatory molecule for the activation of effector and regulatory T cells, in the immunity against this pulmonary pathogen. Using CD28-deficient (CD28(-/-)) and normal wild-type (WT) C57BL/6 mice, we were able to demonstrate that CD28 costimulation determines in pulmonary paracoccidioidomycosis an early immunoprotection but a late deleterious effect associated with impaired immunity and uncontrolled fungal growth. Up to week 10 postinfection, CD28(-/-) mice presented increased pulmonary and hepatic fungal loads allied with diminished production of antibodies and pro-and anti-inflammatory cytokines besides impaired activation and migration of effector and regulatory T (Treg) cells to the lungs. Unexpectedly, CD28-sufficient mice progressively lost the control of fungal growth, resulting in an increased mortality associated with persistent presence of Treg cells, deactivation of inflammatory macrophages and T cells, prevalent presence of anti-inflammatory cytokines, elevated fungal burdens, and extensive hepatic lesions. As a whole, our findings suggest that CD28 is required for the early protective T-cell responses to P. brasiliensis infection, but it also induces the expansion of regulatory circuits that lately impair adaptive immunity, allowing uncontrolled fungal growth and overwhelming infection, which leads to precocious mortality of mice.

Coherent states of non-relativistic electron in the magnetic-solenoid field

In the present work we construct coherent states in the magnetic-solenoid field, which is a superposition of the Aharonov-Bohm field and a collinear uniform magnetic field. In the problem under consideration there are two kinds of coherent states, those which correspond to classical trajectories which embrace the solenoid and those which do not. The constructed coherent states reproduce exactly classical trajectories, maintain their form under the time evolution and form a complete set of functions, which can be useful in semiclassical calculations. In the absence of the solenoid field these states are reduced to the well known in the case of uniform magnetic field Malkin-Man`ko coherent states.

Breakup effects in fusion and total reaction cross sections of weakly bound systems

We use a new technique to investigate the systematic behavior of near barrier complete fusion, total fusion and total reaction cross sections of weakly bound systems. A dimensionless fusion excitation function is used as a benchmark to which renormalized fusion data are compared and dynamic breakup effects can be disentangled from static effects. The same reduction procedure is used to study the effect of the direct reaction mechanisms on the total reaction cross section.

Proton-halo effects in the (8)B+(58)Ni reaction near the Coulomb barrier

Elastic scattering of (8)B and (7)Be on a (58)Ni target has been measured at energies near the Coulomb barrier. The total reaction cross sections were deduced from Optical-model fits to the experimental angular distributions. Comparison with other systems shows evidence for proton-halo effects on (8)B, as well as for neutron-halo on (6)He reactions. While the enhancement in the cross section observed for (8)B is explained in terms of projectile breakup, in the case of (6)He reactions, the particle transfer proces explains the observed enhancement.

Spin-polarization effects in homogeneous and non-homogeneous diluted magnetic semiconductor heterostructures

Spin polarization is a key characteristic in developing spintronic devices. Diluted magnetic heterostructures (DMH), where subsequent layers of conventional and diluted magnetic semiconductors (DMS) are alternate, are one of the possible ways to obtain it. Si being the basis of modern electronics, Si or other group-IV DMH can be used to build spintronic devices directly integrated with conventional ones. In this work we study the physical properties and the spin-polarization effects of p-type DMH based in group-IV semiconductors (Si, Ge, SiGe, and SiC), by performing self-consistent (k) over right arrow . (p) over right arrow calculations in the local spin density approximation. We show that high spin polarization can be maintained in these structures below certain values of the carrier concentrations. Full spin polarization is attained in the low carrier concentration regime for carrier concentrations in the DMS layer up to similar to 2.0 x 10(19) cm(-3) for Si and up to similar to 6.0 x 10(19) cm(-3) for SiC. Partial, but still important spin polarization can be achieved for all studied group-IV DMH, with the exception of Ge for carrier concentrations up to 6.0 x 10(19) cm(-3). The role played by the effective masses and the energy splitting of the spin-orbit split-off hole bands is also discussed throughout the paper.

The Development of Dalton`s Atomic Theory as a Case Study in the History of Science: Reflections for Educators in Chemistry

The inclusion of the history of science in science curricula-and specially, in the curricula of science teachers-is a trend that has been followed in several countries. The reasons advanced for the study of the history of science are manifold. This paper presents a case study in the history of chemistry, on the early developments of John Dalton`s atomic theory. Based on the case study, several questions that are worth discussing in educational contexts are pointed out. It is argued that the kind of history of science that was made in the first decades of the twentieth century (encyclopaedic, continuist, essentially anachronistic) is not appropriate for the development of the competences that are expected from the students of sciences in the present. Science teaching for current days will benefit from the approach that may be termed the ""new historiography of science"".

Debt composition and exchange rate balance sheet effects in Brazil: A firm level analysis

In this paper we study the interaction between macroeconomic environment and firms’ balance sheet effects in Brazil during the 1990’s. We start by assessing the influence of macroeconomic conditions on firms’ debt composition in Brazil. We found that larger firms tend to change debt currency composition more in response to a change in the exchange rate risk than small firms. We then proceed to investigate if and how exchange rate balance sheet effects affected the firms’ investment decisions. We test directly the exchange rate balance sheet effect on investment. Contrary to earlier findings (Bleakley and Cowan, 2002), we found that firms more indebted in foreign currency tend to invest less when there is an exchange rate devaluation. We tried different controls for the competitiveness effect. First, we control directly for the effect of the exchange rate on exports and imported inputs. We then pursue an alternative investigation strategy, inspired by the credit channel literature. According to this perspective, Tobin’s q can provide an adequate control for the competitiveness effect on investment. Our results provide supporting evidence for imperfect capital markets, and for a negative exchange rate balance sheet effect in Brazil. The results concerning the exchange rate balance sheet effect on investment are statistically significant and robust across the different specifications. We tested the results across different periods, classified according to the macroeconomic environment. Our findings suggest that the negative exchange rate balance sheet effect we found in the whole sample is due to the floating exchange rate period. We also found that exchange rate devaluations have important negative impact on both cash flows and sales of indebted firms. Furthermore, the impact of exchange rate variations is asymmetric, and the significant effect detected when no asymmetry is imposed is engendered by exchange rate devaluations.

Demand aggregation and credit risk effects in pooled procurement: evidence from the Brazilian public purchases of pharmaceuticals and medical supplies

Pooled procurement has an important role in reducing acquisition prices of goods. A pool of buyers, which aggregates demand for its members, increases bargaining power and allows suppliers to achieve economies of scale and scope in the production. Such aggregation demand e ect lowers prices paid for buyers. However, when a buyer with a good reputation for paying suppliers in a timely manner is joined in the pool by a buyer with bad reputation may have its price paid increased due to the credit risk e ect on prices. This will happen because prices paid in a pooled procurement should refect the (higher) average buyers' credit risk. Using a data set on Brazilian public purchases of pharmaceuticals and medical supplies, we nd evidence supporting both e ects. We show that the prices paid by public bodies in Brazil are lower when they buy through pooled procurement than individually. On the other hand, federal agencies (i.e. good buyers) pay higher prices for products when they are joined by state agencies (i.e. bad buyers) in a pool. Such evidence suggests that pooled procurement should be carefully designed to avoid that prices paid increase for its members.

Anticipatory effects in the FTSE 100 index revisions

This paper examines the price impact of trading due to expected changes in the FTSE 100 index composition. We focus on the latter index because it employs publicly-known objective criteria to determine membership and hence it provides a natural context to investigate anticipatory trading e ects. We propose a panel-regression event study that backs out these anticipatory e ects by looking at the price impact of the ex-ante proba-bility of changing index membership status. Our ndings reveal that anticipative trading explains about 40% and 23% of the cumulative abnormal returns of additions and deletions, respectively. We con rm these in-sample results out of sample by tracking the performance of a trading strategy that relies on the addition/deletion probability estimates. The perfor-mance is indeed very promising in that it entails an average daily excess return of 11 basis points over the FTSE 100 index.

Interference effects in nonplanar wires with a two-dimensional electron gas

We have studied the universal conductance fluctuations (UCF) due to quantum interface in a two-dimensional electron gas (2DEG) grown on the substrates with pre-patterned, sub-micron wires. The dependence of UCF on the angle between the direction of the magnetic field and the substrate has been investigated. We found, that magnetoresistance traces for different angles are completely uncorrelated. A non-planar character of electron motion is responsible for these angular conductance fluctuations. We compared the experimental results with a simple geometrical model.

PHOSPHORUS EFFECTS IN THE NUTRITION and GROWTH of DEVELOPING MANGO PLANTS

The objective was to study the effects of phosphorous (P) fertilization on nutritional and developmental aspects of growing mango plants. The mango plants were evaluated by soil chemical analyses, leaf chemical analyses, biological examination of plant growth, and the starting point of fruit production. Having this in view, an experiment was set up on 2 January 2003, at Flora, a farm in Uberlandia, state of Minas Gerais, Brazil. The soil was a clayish Oxisol. The doses at planting were: D0 = zero, D1 = 40, D2 = 100, D3 = 200, and D4 = 300 g of P2O5 plant-1. These doses at the beginning of the second year were multiplied by 1.5 and at the beginning of the third year by 2.0 and applied to the plants. The fertilizer used in this experiment was triple superphosphate (44% of P2O5.). During August of 2004, 2005, and 2006, soil samples were taken at a depth of 20 cm in between the plant rows. Leaf samples were taken during August of 2004 and 2005 to determine macro- and micronutrient contents in the leaves. Plant stem diameter was measured during January of 2004 and 2005. Plant height and crown radius were measured during January of 2005 and fruit production in 2005 and 2006. Fertilizer applications increased the level of P in the soil but significantly influenced plant performance only after the second year. The effects of phosphorus on mango plants take place slowly leading to increments in plant stem diameter only at the third year. Fruit set was not influenced by phosphorous fertilization.

Use of direct and iterative solvers for estimation of SNP effects in genome-wide selection

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