Odd-primary homotopy exponents of compact simple Lie groups

We note that a recent result of the second author yields upper bounds for odd-primary homotopy exponents of compact simple Lie groups which are often quite close to the lower bounds obtained from v_1-periodic homotopy theory.Comment: This is the version published by Geometry & Topology Monographs on 22 February 200

The Effects of Private Self-Consciousness and Perspective Taking on Satisfaction in Close Relationships.

131 heterosexual student couples, aged 17–32 yrs, 30 of whom were married or engaged answered questions concerning themselves and their relationships. It was predicted that individual differences in private self-consciousness would be positively related to relationship satisfaction because of the greater self-disclosure resulting from that heightened self-attention. It was further predicted that individual differences in perspective taking would foster relationship satisfaction, independent of any influence of self-disclosure. Both expectations were confirmed. Scores on the private self-consciousness scale were predictive of reported self-disclosure, and self-disclosure was predictive of satisfaction in the relationship. Once the influence of self-disclosure was removed, no effect of self-consciousness on satisfaction remained. In contrast, after disclosure was controlled, perspective-taking scores were significantly related to satisfaction and were in fact unrelated to disclosure at all. Findings indicate that 2 personality characteristics having to do with habitual attention to behavioral tendencies, emotions, and motivations significantly enhance the quality of close heterosexual relationships in different ways

Cosmic Strings, Zero Modes and SUSY breaking in Nonabelian N=1 Gauge Theories

We investigate the microphysics of cosmic strings in Nonabelian gauge theories with N=1 supersymmetry. We give the vortex solutions in a specific example and demonstrate that fermionic superconductivity arises because of the couplings and interactions dictated by supersymmetry. We then use supersymmetry transformations to obtain the relevant fermionic zero modes and investigate the role of soft supersymmetry breaking on the existence and properties of the superconducting strings.Comment: 12 pages, RevTex, submitted to Phys. Rev.

Activity And Localization Of Maltodextrin Binding Site Mutants Of Glycogen Synthase In Saccharomyces Cerevisiae

Mentor: Wayne A. WilsonGlycogen is a glucose polymer formed by the enzyme glycogen synthase and is used in many organisms to store chemical energy. Saccharomyces cerevisiae (baker’s yeast) was used to study the activity and localization of glycogen synthase. Genes GSY1 and GSY2 encode glycogen synthase. GSY2 is responsible for the formation of Gsy2p, whose action accounts for ~90% of glycogen synthase activity; the remainder of total glycogen synthase activity stems from Gsy1p. Because glycogen synthase binds to glycogen, it can be used to determine glycogen localization. Glycogen synthase can appear in distinct patterns throughout the cell. Gsy2p has been shown to be regulated by phosphorylation. Phosphorylation of Gsy2p leads to inactivation of the enzyme, a decrease in glycogen storage, and a more localized pattern of glycogen synthase. Conversely, lowering the phosphorylation state of Gsy2p results in increased glycogen production and delocalization of glycogen synthase throughout the cell. Glucose-6-P (glucose-6-phosphate) activates glycogen synthase regardless of its phosphorylation state. We obtained a set of plasmids from a collaborator, encoding Gsy2p mutated at sites believed to be involved with maltodextrin binding. Maltodextrin is a chain of 20 or fewer dextrose molecules with α (1→4) glycosidic bonds. A protein sequence involved in maltodextrin binding likely would also bind to glycogen. Our task was to discover the localization pattern shown by the maltodextrin binding site mutants of glycogen synthase using a GFP tag on GSY2. The goal of this study was to determine the 16 effects of Gsy2p maltodextrin binding mutants on glycogen synthase activity, localization, and glycogen accumulation

Shoot dieback during prolonged drought in Ceanothus (Rhamnaceae) chaparral of California: a possible case of hydraulic failure

Journal ArticleProgressive diebacks of outer canopy branchlets of Ceanothus crassifolius were repeatedly observed after rainless periods up to 9 mo in duration in the Santa Monica Mountains of southern California. Mean xylem pressures of branchlets near the end of drought were as low as -11.2 MPa (N = 22) with a mean of about 60 dead branchlets per shrub

Relationship between Dehydration Tolerance of California Ferns and the Mechanical Strength of their Stipes

In vascular plants, water moves upwards through xylem vessels/tracheids due to negative pressures created by the evaporative pull of water. Under severe dehydrated, extreme negative pressures are known to cause xylem cavitation and embolism. In seed-bearing plants, the mechanical support of stem xylem has been shown to be a good predictor of cavitation resistance, presumably because sclerenchyma fibers buttress against micro-fracture or collapse of conduit walls. In spore-bearing plants, such as ferns, current anatomical theory indicates that mechanical support lies external to underlying xylem, in the outer hypodermal region, leaving the central xylem in ferns without any fiber support. In light of this anatomical difference, we hypothesized that there would be no correlation between the mechanical strength of fern stipes and their cavitation resistance. In this study we used dehydration tolerance of twelve California fern species as a surrogate for cavitation resistance. We used a Scholander-Hammel pressure chamber to examine minimum seasonal water potential (Ymin) and pressure-volume curves to estimate the osmotic potential of leaf tissue at the turgor loss point (Ys,tlp). We used a four point bending test via an Instron Mechanical Testing Devise to estimate stipe mechanical strength (Modulus of Elasticity, MOE). We found large differences among our 12 fern species. Minimum seasonal water potential varied between -1.1 and -8.3 MPa and mean Ys,tlp varied between -1.1 and -3.4 MPa. Modulus of Elasticity of fern stipes varied nearly ten-fold, between 0.0025 N/m2 and 0.023 N/m2. Consistent with our initial hypothesis, we found no correlation between the mechanical strength of stems (MOE) and their dehydration tolerance, either in terms of Ys,tlp (r2 = 0.005) or Ymin (r2 = 0.011). Taken together, we speculate that the lack of a correlation between stipe mechanical strength and dehydration tolerance reflects the relictual separation of fern water transport conduits from mechanical support

Oxygen Compatibility of Brass-Filled PTFE Compared to Commonly Used Fluorinated Polymers for Oxygen Systems

Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to demonstrate the importance of the metal chosen and relative percentage of filler. General conclusions on the oxygen compatibility of this formulation are drawn, with an emphasis on comparing and contrasting the materials performance to the performance of the current state-of-the-art oxygen compatible polymers