Louisiana State University

About: Louisiana State University is a education organization based out in Baton Rouge, Louisiana, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 40206 authors who have published 76587 publications receiving 2566076 citations. The organization is also known as: LSU & Louisiana State University and Agricultural and Mechanical College.

Soluble Narrow Band Gap and Blue Propylenedioxythiophene-Cyanovinylene Polymers as Multifunctional Materials for Photovoltaic and Electrochromic Applications

Abstract: A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported. The polymers were synthesized using Knoevenagel polycondensation or Yamamoto coupling polymerizations to yield polymers with molecular weights on the order of 10 000-20 000 g/mol, which possess solubility in common organic solvents. Thin film optical measurements revealed narrow band gaps of 1.5-1.8 eV, which gives the polymers a strong overlap of the solar spectrum. The energetic positions of the band edges were determined by cyclic voltammetry and differential pulse voltammetry and demonstrate that the polymers are both air stable and show a strong propensity for photoinduced charge transfer to fullerene acceptors. Such measurements also suggest that the polymers can be both p- and n-type doped, which is supported by spectroelectrochemical results. These polymers have been investigated as electron donors in photovoltaic devices in combination with PCBM ([6,6]-phenyl C(61)-butyric acid methyl ester) as an electron acceptor based on the near ideal band structures designed into the polymers. Efficiencies as high as 0.2% (AM1.5) with short circuit current densities as high as 1.2-1.3 mA/cm(2) have been observed in polymer/PCBM (1:4 by weight) devices and external quantum efficiencies of more than 10% have been observed at wavelengths longer than 600 nm. The electrochromic properties of the narrow band gap polymers are also of interest as the polymers show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms. The wide electrochemical range of electrochromic activity coupled with the strong observed changes in transmissivity between oxidation states makes these materials potentially interesting for application to electrochromic displays.

Helicobacter pylori and gastric carcinoma. Serum antibody prevalence in populations with contrasting cancer risks.

Abstract: This investigation examined the correlation between Helicobacter pylori (HP) infection, as reflected in immunoglobulin G serum antibodies, and the risk of gastric cancer. Serum samples were obtained from populations with contrasting gastric cancer risks. The highest prevalence of HP infection, 93%, was observed in the adult population at highest gastric cancer risk, the residents of Pasto, Colombia. In the lower risk Colombian city of Cali, a 63% overall prevalence rate was found. Both children and adults were sampled in New Orleans, Louisiana, where gastric cancer rates are high for blacks but not for whites. The prevalence of HP infection was significantly higher in black than in white adults, 70% versus 43%, P = 0.0001. A higher prevalence was also detected in black compared with white children, 49% versus 32%, P = 0.01; however, an even greater disparity was noted when comparing children from two hospitals, regardless of race, which serve different socioeconomic groups. A prevalence rate of 54% was found at Charity Hospital compared with 24% (P = 0.0001) at Children's Hospital. Our findings indicate that socioeconomic conditions, known to influence gastric cancer risk, are also important determinants of HP infection.

Multiple nutrients limit litterfall and decomposition in a tropical forest.

Abstract: To explore the importance of 12 elements in litter production and decomposition, we fertilized 36 1600 m 2 -plots with combinations of N, P, K, or micronutrients (i.e. B, Ca, Cu, Fe, Mg, Mn, Mo, S, Zn) for 6 years in a lowland Panamanian forest. The 90% of litter falling as leaves and twigs failed to increase with fertilization, but reproductive litter (fruits and flowers) increased by 43% with N. K enhanced cellulose decomposition; one or more micronutrients enhanced leaf-litter decomposition; P enhanced both. Our results suggest tropical forests are a non-Liebig world of multiple nutrient limitations, with at least four elements shaping rates of litterfall and decomposition. Multiple metallomic enzymes and cofactors likely create gradients in the break down of leaf litter. Selection favours individuals that make more propagules, and even in an N-rich forest, N is a non-substitutable resource for reproduction.

Sleep deprivation causes behavioral, synaptic, and membrane excitability alterations in hippocampal neurons

Abstract: Although the function of sleep remains elusive, several lines of evidence suggest that sleep has an important role in learning and memory. In light of the available data and with the prevalence of sleep deprivation (SD), we sought to determine the effect of SD on neuronal functioning. We found that the exposure of rats to 72 hr of primarily rapid eye movement SD impaired their subsequent performance on a hippocampus-dependent spatial learning task but had no effect on an amygdala-dependent learning task. To determine the underlying cellular level mechanisms of this hippocampal deficit, we examined the impact of SD on several fundamental aspects of membrane excitability and synaptic physiology in hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. We found that neuronal excitability was severely reduced in CA1 neurons but not in granule cells and that the production of long-term potentiation of synaptic strength was inhibited in both areas. Using multiple SD methods we further attempted to differentiate the effects of sleep deprivation from those associated with the nonspecific stress induced by the sleep deprivation methods. Together these data suggest that failure to acquire adequate sleep produces several molecular and cellular level alterations that profoundly inhibit hippocampal functioning.

Crisis in the IS field? A critical reflection on the state of the discipline

Abstract: This paper explores the issue of whether the field of IS is in crisis. To do so, the paper first starts by looking back on where the field has come from. Next, it assesses the status of the IS field by exploring where the field is now. That our current status remains a ‘fragmented adhocracy’ suggests the field may indeed be in crisis or headed for a crisis. This is compounded by the fact that there are two different views on the state of the IS field, each posing its own set of threats. One is the external view of the community (the view of IS from outside the academic field); the other is the internal view (the view from inside the IS community). By analyzing these two views, a better understanding of the problems the field faces emerges. In the next part of the paper, some thoughts are presented on where might the field go from here for overcoming its internal communication deficit. The paper proposes four different types of knowledge for structuring an IS Body of Knowledge (BoK) and following on from that, the value of creating a common BoK for the field. Lastly, the implications arising from the paper’s analysis are explored. More specifically, the paper considers various options that are available for overcoming the internal communications deficit the IS field faces. These include changing the way the field thinks about generalizations, changing the institutional publication practices, focusing more on understanding the field’s organizational stakeholders, and developing new knowledge creation and transformation networks. If IS as a field can overcome its internal communications deficits, it might ultimately contribute to the societal challenge of developing a deliberative cyber democracy and thereby help to address the social communication deficit which is a feature of modern mass societies.