The structural organization and protein composition of lens fiber junctions.

The structural organization and protein composition of lens fiber junctions isolated from adult bovine and calf lenses were studied using combined electron microscopy, immunolocalization with monoclonal and polyclonal anti-MIP and anti-MP70 (two putative gap junction-forming proteins), and freeze-fracture and label-fracture methods. The major intrinsic protein of lens plasma membranes (MIP) was localized in single membranes and in an extensive network of junctions having flat and undulating surface topologies. In wavy junctions, polyclonal and monoclonal anti-MIPs labeled only the cytoplasmic surface of the convex membrane of the junction. Label-fracture experiments demonstrated that the convex membrane contained MIP arranged in tetragonal arrays 6-7 nm in unit cell dimension. The apposing concave membrane of the junction displayed fracture faces without intramembrane particles or pits. Therefore, wavy junctions are asymmetric structures composed of MIP crystals abutted against particle-free membranes. In thin junctions, anti-MIP labeled the cytoplasmic surfaces of both apposing membranes with varying degrees of asymmetry. In thin junctions, MIP was found organized in both small clusters and single membranes. These small clusters also abut against particle-free apposing membranes, probably in a staggered or checkerboard pattern. Thus, the structure of thin and wavy junctions differed only in the extent of crystallization of MIP, a property that can explain why this protein can produce two different antibody-labeling patterns. A conclusion of this study is that wavy and thin junctions do not contain coaxially aligned channels, and, in these junctions, MIP is unlikely to form gap junction-like channels. We suggest MIP may behave as an intercellular adhesion protein which can also act as a volume-regulating channel to collapse the lens extracellular space. Junctions constructed of MP70 have a wider overall thickness (18-20 nm) and are abundant in the cortical regions of the lens. A monoclonal antibody raised against this protein labeled these thicker junctions on the cytoplasmic surfaces of both apposing membranes. Thick junctions also contained isolated clusters of MIP inside the plaques of MP70. The role of thick junctions in lens physiology remains to be determined

Spread Supersymmetry

In the multiverse the scale of SUSY breaking, \tilde{m} = F_X/M_*, may scan and environmental constraints on the dark matter density may exclude a large range of \tilde{m} from the reheating temperature after inflation down to values that yield a LSP mass of order a TeV. After selection effects, the distribution for \tilde{m} may prefer larger values. A single environmental constraint from dark matter can then lead to multi-component dark matter, including both axions and the LSP, giving a TeV-scale LSP lighter than the corresponding value for single-component LSP dark matter. If SUSY breaking is mediated to the SM sector at order X^* X, only squarks, sleptons and one Higgs doublet acquire masses of order \tilde{m}. The gravitino mass is lighter by a factor of M_*/M_Pl and the gaugino masses are suppressed by a further loop factor. This Spread SUSY spectrum has two versions; the Higgsino masses are generated in one from supergravity giving a wino LSP and in the other radiatively giving a Higgsino LSP. The environmental restriction on dark matter fixes the LSP mass to the TeV domain, so that the squark and slepton masses are order 10^3 TeV and 10^6 TeV in these two schemes. We study the spectrum, dark matter and collider signals of these two versions of Spread SUSY. The Higgs is SM-like and lighter than 145 GeV; monochromatic photons in cosmic rays arise from dark matter annihilations in the halo; exotic short charged tracks occur at the LHC, at least for the wino LSP; and there are the eventual possibilities of direct detection of dark matter and detailed exploration of the TeV-scale states at a future linear collider. Gauge coupling unification is as in minimal SUSY theories. If SUSY breaking is mediated at order X, a much less hierarchical spectrum results---similar to that of the MSSM, but with the superpartner masses 1--2 orders of magnitude larger than in natural theories.Comment: 20 pages, 5 figure

Using Social Media to Promote STEM Education: Matching College Students with Role Models

STEM (Science, Technology, Engineering, and Mathematics) fields have become increasingly central to U.S. economic competitiveness and growth. The shortage in the STEM workforce has brought promoting STEM education upfront. The rapid growth of social media usage provides a unique opportunity to predict users' real-life identities and interests from online texts and photos. In this paper, we propose an innovative approach by leveraging social media to promote STEM education: matching Twitter college student users with diverse LinkedIn STEM professionals using a ranking algorithm based on the similarities of their demographics and interests. We share the belief that increasing STEM presence in the form of introducing career role models who share similar interests and demographics will inspire students to develop interests in STEM related fields and emulate their models. Our evaluation on 2,000 real college students demonstrated the accuracy of our ranking algorithm. We also design a novel implementation that recommends matched role models to the students.Comment: 16 pages, 8 figures, accepted by ECML/PKDD 2016, Industrial Trac

Feature Selection of Post-Graduation Income of College Students in the United States

This study investigated the most important attributes of the 6-year post-graduation income of college graduates who used financial aid during their time at college in the United States. The latest data released by the United States Department of Education was used. Specifically, 1,429 cohorts of graduates from three years (2001, 2003, and 2005) were included in the data analysis. Three attribute selection methods, including filter methods, forward selection, and Genetic Algorithm, were applied to the attribute selection from 30 relevant attributes. Five groups of machine learning algorithms were applied to the dataset for classification using the best selected attribute subsets. Based on our findings, we discuss the role of neighborhood professional degree attainment, parental income, SAT scores, and family college education in post-graduation incomes and the implications for social stratification.Comment: 14 pages, 6 tables, 3 figure

Is cannabis use a contributory cause of psychosis?

Objective: To assess whether cannabis use in adolescence and young adulthood is a contributory cause of schizophreniform psychosis in that it may precipitate psychosis in vulnerable individuals. Method: We reviewed longitudinal studies of adolescents and young adults that examined the relations between self-reported cannabis use and the risk of diagnosis with a psychosis or of reporting psychotic symptoms. We also reviewed studies that controlled for potential confounders, such as other forms of drug use and personal characteristics that predict an increased risk of psychosis. We assessed evidence for the biological plausibility of a contributory causal relation. Results: Evidence from 6 longitudinal studies in 5 countries shows that regular cannabis use predicts an increased risk of a schizophrenia diagnosis or of reporting symptoms of psychosis. These relations persisted after controlling for confounding variables, such as personal characteristics and other drug use. The relation did not seem to be a result of cannabis use to self-medicate symptoms of psychosis. A contributory causal relation is biologically plausible because psychotic disorders involve disturbances in the dopamine neurotransmitter systems with which the cannabinoid system interacts, as demonstrated by animal studies and one human provocation study. Conclusion: It is most plausible that cannabis use precipitates schizophrenia in individuals who are vulnerable because of a personal or family history of schizophrenia

Skyrmions in a ferromagnetic Bose-Einstein condensate

The recently realized multicomponent Bose-Einstein condensates provide opportunities to explore the rich physics brought about by the spin degrees of freedom. For instance, we can study spin waves and phase separation, macroscopic quantum tunneling, Rabi oscillations, the coupling between spin gradients and superfluid flow, squeezed spin states, vortices and other topological excitations. Theoretically, there have been already some studies of the ground-state properties of these systems and their line-like vortex excitations. In analogy with nuclear physics or the quantum Hall effect, we explore here the possibility of observing point-like topological excitations or skyrmions. These are nontrivial spin textures that in principle can exist in a spinor Bose-Einstein condensate. In particular, we investigate the stability of skyrmions in a fictitious spin-1/2 condensate of Rb87 atoms. We find that skyrmions can exist in this case only as a metastable state, but with a lifetime of the order of, or even longer than, the typical lifetime of the condensate itself. In addition to determining the size and the lifetime of the skyrmion, we also present its spin texture and finally briefly consider its dynamical properties.Comment: 4 pages (REVtex), 3 PDF figures. See also cond-mat/000237

The key role of nitric oxide in hypoxia: hypoxic vasodilation and energy supply-demand matching

Significance: a mismatch between energy supply and demand induces tissue hypoxia with the potential to cause cell death and organ failure. Whenever arterial oxygen concentration is reduced, increases in blood flow - 'hypoxic vasodilation' - occur in an attempt to restore oxygen supply. Nitric oxide is a major signalling and effector molecule mediating the body's response to hypoxia, given its unique characteristics of vasodilation (improving blood flow and oxygen supply) and modulation of energetic metabolism (reducing oxygen consumption and promoting utilization of alternative pathways). Recent advances: this review covers the role of oxygen in metabolism and responses to hypoxia, the hemodynamic and metabolic effects of nitric oxide, and mechanisms underlying the involvement of nitric oxide in hypoxic vasodilation. Recent insights into nitric oxide metabolism will be discussed, including the role for dietary intake of nitrate, endogenous nitrite reductases, and release of nitric oxide from storage pools. The processes through which nitric oxide levels are elevated during hypoxia are presented, namely (i) increased synthesis from nitric oxide synthases, increased reduction of nitrite to nitric oxide by heme- or pterin-based enzymes and increased release from nitric oxide stores, and (ii) reduced deactivation by mitochondrial cytochrome c oxidase. Critical issues: several reviews covered modulation of energetic metabolism by nitric oxide, while here we highlight the crucial role NO plays in achieving cardiocirculatory homeostasis during acute hypoxia through both vasodilation and metabolic suppression Future directions: we identify a key position for nitric oxide in the body's adaptation to an acute energy supply-demand mismatc

Individual differences in second language speech learning in classroom settings: roles of awareness in the longitudinal development of Japanese learners’ English /ɹ/ pronunciation

The current study longitudinally examined a crucial individual difference variable—i.e., awareness (operationalized as explicit attention and articulatory knowledge)—in adult second language (L2) speech learning in the context of 40 Japanese learners’ English /ɹ/ pronunciation development in an EFL classroom. The participants’ speech, elicited from word reading, sentence reading and timed picture description tasks at the beginning and end of one academic semester, were analyzed in terms of three acoustic dimensions of English /ɹ/—third formant (F3), second formant (F2) and duration. Whereas the participants showed gains in the relatively easy aspect of the English /ɹ/ acquisition (F2 reduction) as a function of increased L2 input, their explicit awareness of accurate English /ɹ/ pronunciation played a significant role in the acquisition of the relatively difficult dimension (lengthening phonemic duration). The awareness-acquisition link was not found, however, for the most difficult dimension (F3 reduction) at least within the timeframe of the project

Sr-Nd isotope geochemistry of the early Precambrian sub-alkaline mafic igneous rocks from the southern Bastar craton, Central India

Sr–Nd isotope data are reported for the early Precambrian sub-alkaline mafic igneous rocks of the southern Bastar craton, central India. These mafic rocks are mostly dykes but there are a few volcanic exposures. Field relationships together with the petrological and geochemical characteristics of these mafic dykes divide them into two groups; Meso-Neoarchaean sub-alkaline mafic dykes (BD1) and Paleoproterozoic (1.88 Ga) sub-alkaline mafic dykes (BD2). The mafic volcanics are Neoarchaean in age and have very close geochemical relationships with the BD1 type. The two groups have distinctly different concentrations of high-field strength (HFSE) and rare earth elements (REE). The BD2 dykes have higher concentrations of HFSE and REE than the BD1 dykes and associated volcanics and both groups have very distinctive petrogenetic histories. These rocks display a limited range of initial 143Nd/144Nd but a wide range of apparent initial 87Sr/86Sr. Initial 143Nd/144Nd values in the BD1 dykes and associated volcanics vary between 0.509149 and 0.509466 and in the BD2 dykes the variation is between 0.510303 and 0.510511. All samples have positive εNd values the BD1 dykes and associated volcanics have εNd values between +0.3 and +6.5 and the BD2 dykes between +1.9 to +6.0. Trace element and Nd isotope data do not suggest severe crustal contamination during the emplacement of the studied rocks. The positive εNd values suggest their derivation from a depleted mantle source. Overlapping positive εNd values suggest that a similar mantle source tapped by variable melt fractions at different times was responsible for the genesis of BD1 (and associated volcanics) and BD2 mafic dykes. The Rb–Sr system is susceptible to alteration and resetting during post-magmatic alteration and metamorphism. Many of the samples studied have anomalous apparent initial 87Sr/86Sr suggesting post-magmatic changes of the Rb–Sr system which severely restricts the use of Rb–Sr for petrogenetic interpretation

Neural development features: Spatio-temporal development of the Caenorhabditis elegans neuronal network

The nematode Caenorhabditis elegans, with information on neural connectivity, three-dimensional position and cell linage provides a unique system for understanding the development of neural networks. Although C. elegans has been widely studied in the past, we present the first statistical study from a developmental perspective, with findings that raise interesting suggestions on the establishment of long-distance connections and network hubs. Here, we analyze the neuro-development for temporal and spatial features, using birth times of neurons and their three-dimensional positions. Comparisons of growth in C. elegans with random spatial network growth highlight two findings relevant to neural network development. First, most neurons which are linked by long-distance connections are born around the same time and early on, suggesting the possibility of early contact or interaction between connected neurons during development. Second, early-born neurons are more highly connected (tendency to form hubs) than later born neurons. This indicates that the longer time frame available to them might underlie high connectivity. Both outcomes are not observed for random connection formation. The study finds that around one-third of electrically coupled long-range connections are late forming, raising the question of what mechanisms are involved in ensuring their accuracy, particularly in light of the extremely invariant connectivity observed in C. elegans. In conclusion, the sequence of neural network development highlights the possibility of early contact or interaction in securing long-distance and high-degree connectivity