Osteopilus vastus

Number of Pages: 3Integrative BiologyGeological Science

THE HIDDEN INEQUALITY IN SOCIALISM

In the same time period over which the former socialist countries of Eastern Europe and Central Asia became freer, measured inequality of income for those countries increased. Researchers linked the increase to the egalitarian values of socialism and to the process of economic and political liberalization. We question that link, because we question whether socialism was egalitarian. The inequalities in socialism were hidden but, nevertheless, were real.Transition, Inequality, Socialism, Measurement

Examining the relationship between student performance and video interactions

In this work, we attempted to predict student performance on a suite of laboratory assessments using students' interactions with associated instructional videos. The students' performance is measured by a graded presentation for each of four laboratory presentations in an introductory mechanics course. Each lab assessment was associated with between one and three videos of instructional content. Using video clickstream data, we define summary features (number of pauses, seeks) and contextual information (fraction of time played, in-semester order). These features serve as inputs to a logistic regression (LR) model that aims to predict student performance on the laboratory assessments. Our findings show that LR models are unable to predict student performance. Adding contextual information did not change the model performance. We compare our findings to findings from other studies and explore caveats to the null-result such as representation of the features, the possibility of underfitting, and the complexity of the assessment.Comment: 4 pages, 1 figure, submitted to the PERC 2018 proceeding

Alsophis rufiventris

Number of Pages: 4Integrative BiologyGeological Science

A Preliminary Study of the Visual Field in Athletics

If a basketball player sees an area half as large as another player, he has less chance of sizing up the entire situation on the floor at any moment. Likewise, if one player secs less at a given time than he did previously or will in the future, he is probably less effective at that given time. This study attempts first to discover whether or not there is a reason to suspect a measurable relationship between the size of the visual field and successful basketball playing. If there is, obviously a test of visual fields would be advantageous to a coach deciding which inexperienced candidates should be trained. Secondly, this study investigates the effects of fatigue upon the size of the visual field, i.e., does a tired man actually see less? If he does see less, what are the characteristics of the recovery of normal vision? Rather than prepare and conduct an extensive survey immediately, this study was designed to precede a more complete research, to suggest tentative conclusions, and to reveal the difficulties and uncontrollable variations in such work

The stoichiometry of P2X2/6 receptor heteromers depends on relative subunit expression levels

Fast synaptic transmission involves the operation of ionotropic receptors, which are often composed of at least two types of subunit. We have developed a method, based on atomic force microscopy imaging to determine the stoichiometry and subunit arrangement within ionotropic receptors. We showed recently that the P2X(2) receptor for ATP is expressed as a trimer but that the P2X(6) subunit is unable to oligomerize. In this study we addressed the subunit stoichiometry of heteromers containing both P2X(2) and P2X(6) subunits. We transfected tsA 201 cells with both P2X(2) and P2X(6) subunits, bearing different epitope tags. We manipulated the transfection conditions so that either P2X(2) or P2X(6) was the predominant subunit expressed. By atomic force microscopy imaging of isolated receptors decorated with antiepitope antibodies, we demonstrate that when expression of the P2X(2) subunit predominates, the receptors contain primarily 2 x P2X(2) subunits and 1 x P2X(6) subunit. In contrast, when the P2X(6) subunit predominates, the subunit stoichiometry of the receptors is reversed. Our results show that the composition of P2X receptor heteromers is plastic and dependent on the relative subunit expression levels. We suggest that this property of receptor assembly might introduce an additional layer of subtlety into P2X receptor signaling

Evidence That the Product of the Human X-Linked Cgd Gene, Gp91-phox, Is a Voltage-Gated H+ Pathway

Expression of gp91-phox in Chinese hamster ovary (CHO91) cells is correlated with the presence of a voltage-gated H+ conductance. As one component of NADPH oxidase in neutrophils, gp91-phox is responsible for catalyzing the production of superoxide (O2·2). Suspensions of CHO91 cells exhibit arachidonate-activatable H+ fluxes (Henderson, L.M., G. Banting, and J.B. Chappell. 1995. J. Biol. Chem. 270:5909–5916) and we now characterize the electrical properties of the pathway. Voltage-gated currents were recorded from CHO91 cells using the whole-cell configuration of the patch-clamp technique under conditions designed to exclude a contribution from ions other than H+. As in other voltage-gated proton currents (Byerly, L., R. Meech, and W. Moody. 1984. J. Physiol. 351:199–216; DeCoursey, T.E., and V.V. Cherny. 1993. Biophys. J. 65:1590–1598), a lowered external pH (pHo) shifted activation to more positive voltages and caused the tail current reversal potential to shift in the manner predicted by the Nernst equation. The outward currents were also reversibly inhibited by 200 μM zinc. Voltage-gated currents were not present immediately upon perforating the cell membrane, but showed a progressive increase over the first 10–20 min of the recording period. This time course was consistent with a gradual shift in activation to more negative potentials as the pipette solution, pH 6.5, equilibrated with the cell contents (reported by Lucifer yellow included in the patch pipette). Use of the pH-sensitive dye 2′7′ bis-(2-carboxyethyl)-5(and 6) carboxyfluorescein (BCECF) suggested that the final intracellular pH (pHi) was ∼6.9, as though pHi was largely determined by endogenous cellular regulation. Arachidonate (20 μM) increased the amplitude of the currents by shifting activation to more negative voltages and by increasing the maximally available conductance. Changes in external Cl− concentration had no effect on either the time scale or the appearance of the currents. Examination of whole cell currents from cells expressing mutated versions of gp91-phox suggest that: (a) voltage as well as arachidonate sensitivity was retained by cells with only the NH2-terminal 230 amino acids, (b) histidine residues at positions 111, 115, and 119 on a putative membrane-spanning helical region of the protein contribute to H+ permeation, (c) histidine residues at positions 111 and 119 may contribute to voltage gating, (d) the histidine residue at position 115 is functionally important for H+ selectivity. Mechanisms of H+ permeation through gp91-phox include the possible protonation/deprotonation of His-115 as it is exposed alternatively to the interior and exterior faces of the cell membrane (see Starace, D.M., E. Stefani, and F. Bezanilla. 1997. Neuron. 19:1319–1327) and the transfer of protons across an “H-X-X-X-H-X-X-X-H” motif lining a conducting pore

An Ab Initio Study of Specific Solvent Effects on the Electronic Coupling Element in Electron Transfer Reactions

Specific solvent effects on the electronic coupling element for electron transfer are examined using two model donor–acceptor systems (Zn2+ and Li2+) and several model “solvent” species (He, Ne, H2O, and NH3). The effects are evaluated relative to the given donor–acceptor pair without solvent present. The electronic coupling element (Hab) is found to depend strongly on the identity of the intervening solvent, with He atoms decreasing Hab, whereas H2O and NH3 significantly increase Hab. The distance dependence (essentially exponential decay) is weakly affected by a single intervening solvent atom–molecule. However, when the donor–acceptor distance increases in concert with addition of successively greater numbers of solvent species, the decay with distance of Hab is altered appreciably. Effects due to varying the orientation of molecular solvent are found, somewhat surprisingly, to be quite modest

Observing prosociality and talent: the emotional characteristics and behavioral outcomes of elevation and admiration in 6.5- to 8.5-year-old children

Helping and seeing others being helped elicits positive emotions in young children but little is known about the nature of these emotions, especially in middle childhood. Here we examined the specific emotional characteristics and behavioral outcomes of two closely related other-praising moral emotions: elevation and admiration. We exposed 182 6.5- to 8.5-year-old children living in New Zealand, to an elevation- and admiration-inducing video clip. Afterwards children’s emotion experiences and prosocial behaviour was measured. Findings revealed higher levels of happiness, care, and warmth after seeing prosociality in others (elevation condition) and higher levels of upliftment after seeing talent in others (admiration condition). We found no differences in prosocial behavior between the elevation and admiration conditions. This is the first study to assess elevation in childhood and offers a novel paradigm to investigate the role of moral emotions as potential motivators underlying helping