10,000 publications from this institution
EEG sleep measures in 35 depressed and 33 normal control adolescents were examined in relation to stressful life events occurring in the year before sleep studies. There was a significant interaction between stressful life events and diagnostic status for REM latency and total REM time. In the normal controls, the presence of stressful life events was significantly associated with reduced REM latency and increased total REM time. Among the depressed adolescents, there were no significant effects of stressful life events on REM latency or total REM time. The depressed adolescents with no stressful life events (n = 9) had significantly lower REM latency values compared to normal control adolescents with no stressful life events (n = 13)(61.7 +/- 50.0 vs. 132.1 +/- 79.0, p < or = .01). It appears that stressful life events influence at least some measures of adolescent sleep and should be considered in future controlled studies aimed at understanding sleep changes in adolescent depression.
Objective To examine the extent to which physician‐to‐system ownership transitions are associated with declines in practice‐reported patient responsiveness ( PRPR ). Data Sources A longitudinal cohort of practices ( n = 897) from the National Survey of Large Physician Organizations/National Survey of Small‐ and Medium‐Sized Physician Organizations (2006/08) and the National Survey of All‐Size Physician Organizations (2012/13). Study Design Multivariable regression estimated the effect of ownership on changes in PRPR , controlling for practice size, specialty composition, other practice, and market characteristics. Data Collection/Extraction Methods Data were collected from three nationally representative surveys of physician organizations consisting of 40‐minute interviews with the medical director, president, or chief executive officer. Principal Findings Nine percent of organizations transitioned to system ownership. Compared to practices that were continuously physician‐owned, practices that switched to system ownership did not have significantly lower PRPR at baseline but continuously system‐owned practices did. Transitions to system ownership were associated with increased PRPR compared to continuously physician ownership. Increased practice size and changes in specialty composition, however, were associated with diminished PRPR . Conclusions Practices can maintain or improve strategies to address patient concerns when transferring ownership to systems with careful attention to the impact of increased size and changes in specialty composition.
The coexistence of posttraumatic stress disorder (PTSD) and traumatic head or brain injury (TBI) in the same individual has been proposed to be paradoxical. It has been argued that individuals who sustain a TBI and have no conscious memory of their trauma will not experience fear, helplessness and horror during the trauma, nor will they develop reexperiencing symptoms or establish the negative associations that underlie avoidance symptoms. However, single case reports and incidence studies suggest that PTSD can be diagnosed following TBI. We highlight critical issues in assessment, definitions, and research methods, and propose two possible resolutions of the paradox. One resolution focuses on ambiguity in the criteria for diagnosing PTSD. The other involves accepting that TBI patients do experience similar symptoms to other PTSD patients, but that there are crucial differences in symptom content. ( JINS , 2003, 9 , 663–676.)
The many-body localization transition (MBLT) between ergodic and many-body\nlocalized phase in disordered interacting systems is a subject of much recent\ninterest. Statistics of eigenenergies is known to be a powerful probe of\ncrossovers between ergodic and integrable systems in simpler examples of\nquantum chaos. We consider the evolution of the spectral statistics across the\nMBLT, starting with mapping to a Brownian motion process that analytically\nrelates the spectral properties to the statistics of matrix elements. We\ndemonstrate that the flow from Wigner-Dyson to Poisson statistics is a\ntwo-stage process. First, fractal enhancement of matrix elements upon\napproaching the MBLT from the metallic side produces an effective power-law\ninteraction between energy levels, and leads to a plasma model for level\nstatistics. At the second stage, the gas of eigenvalues has local interaction\nand level statistics belongs to a semi-Poisson universality class. We verify\nour findings numerically on the XXZ spin chain. We provide a microscopic\nunderstanding of the level statistics across the MBLT and discuss implications\nfor the transition that are strong constraints on possible theories.\n
Photobiological hydrogen production is a sustainable alternative to thermo-chemical and electrolytic technologies with the added advantage of carbon dioxide mitigation. However, the scale-up of this technology from bench top to mass culture in industrial photobioreactors suffers from low solar-to-chemical conversion efficiency and irradiance transmittance limitations. In order to overcome these challenge, algae such as Chlamydomonas reinhardtii, can be genetically engineered to have reduced pigment concentrations in their photosystems. Thus, algae do not absorb more light than they can utilize. Moreover, reducing pigment concentration will enable solar radiation to penetrate deeper in the photobioreactor thus facilitating greater productivity in the high density mass culture. The objective of this study is to experimentally measure the radiation characteristics of the unicellular green algae Chlamydomonas reinhardtii CC125 and its truncated chlorophyll antenna transformants tla1 and tlaX. Their extinction and absorption coefficients are obtained from normal-normal and normal-hemispherical transmittance measurements over the spectral range from 300 to 1,300 nm. Moreover, a nephelometer with a He-Ne laser source is used to measure the scattering phase function of the microorganisms at 632.8 nm. Results indicate that the mass absorption cross-sections decrease for the truncated chlorophyll transformants while the single scattering albedo increases. Therefore, light scattering becomes more important in photobioreactors using the genetically engineered strains. The results reported can be used with the radiative transport equation (RTE) to accurately predict and optimize light transport in photobioreactors for photobiological hydrogen production and/or carbon dioxide mitigation using genetically engineered microorganisms.
NMR spectroscopy is a powerful technique for identifying the structure and concentration of silicate and aluminosilicate anions in gels and solutions used for zeolite synthesis. A review is presented of the types species that have been observed and the dependence of the distribution of these species on pH and the nature of the cations present.
Hindered chiral ethers with one or two stereocenters are now readily available by allylic etherification of primary and secondary alkoxides (see reaction). When an Ir–phosphoramidite complex is used as the catalyst, the reaction proceeds with high regio-, enantio-, and diastereoselectivity. Np=1-naphthyl.
A multitrophic model integrating the effects of flooding disturbance and food web interactions in rivers predicted that removing floods would cause increases of predator-resistant grazing insects, which would divert energy away from the food chain leading to predatory fish. Experimental manipulations of predator-resistant grazers and top predators, and large-scale comparisons of regulated and unregulated rivers, verified the model predictions. Thus, multitrophic models can successfully synthesize a variety of ecological processes, and conservation programs may benefit by taking a food web perspective instead of concentrating on a single species.
South Africa was one of the fastest growing economies of the 1930s. This paper seeks to identify the roots of this macroeconomic outperformance and reconcile it with the country's delayed departure from the gold standard, such departure having typically been the event inaugurating recovery from the slump. It emphasizes South Africa's dependence on gold production, which gave the economy an additional boost from currency depreciation, over and above that felt in other countries, when depreciation finally took place. This highlights the paradox of South African policy makers' resistance to currency depreciation, as epitomized by the report of the Select Committee on the Gold Standard in 1932.
