Pbte Quantum Dots - Sio2 Multilayers For Optical Devices Produced By Laser Ablation

Thin films of glass doped with PbTe quantum dots were successfully fabricated. The semiconducting quantum dots were grown by laser ablation of a PbTe target (99.99%) using the second harmonic of a Q-Switched Quantel Nd:YAG laser under high purity argon atmosphere. The glass matrix was fabricated by a plasma chemical vapor deposition method using vapor of tetramethoxysilane (TMOS) as precursor. The QD's and the glass matrix were alternately deposited onto a Si (100) wafer for 60 cycles. Cross-section TEM image clearly showed QD's layer well separated from each other with glass matrix layers. The influence of the ablation time on the size distribution of the quantum dots is studied. HRTEM revealed anisotropy in the size of the QD's: they were about 9nm in the high and 3-5 in diameter. Furthermore HRTEM studies revealed that the QD's basically growth in the (200) and (220) directions. The thickness of the glass matrix layer was about 20 nm. Absorption, photo luminescence and relaxation time of the multilayer were also measured.5734116123Alivisatos, A.P., (1996) Sci., 271, p. 933Warnock, J., Awschalom, D.D., (1985) Phys. Rev. B, 32, p. 5529Borrelli, N.F., May, D.W., Holland, H.J., Smith, D.W., (1987) J. Appl. Phys., 61, p. 399Potter, B.G., Simmons, J.H., (1988) Phys. Rev. B, 37, p. 10838Gleiter, H., (1989) Prog. Mater. Sci., 33, p. 223Tsunetomo, K., Shunsuke, S., Koyama, T., Tanaka, S., Sasaki, F., Kobayashi, S., (1995) Nonlinear Opt., 13, p. 109Reynoso, V.C.S., De Paula, A.M., Cuevas, R.F., Neto, J.A.M., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Electr. Lett., 31 (12), pp. 1013-1015Jacob, G.J., Cesar, C.L., Barbosa, L.C., (2002) Chem. Phys. Glass, 43 C, pp. 250-252Singh, R.K., Narayan, J., (1990) Phys. Rev. B, 41, p. 8843Barnes, J.P., (2002) Nanotechnology, 13, p. 465Tudury, G.E., Marquezini, M.V., Ferreira, L.G., Barbosa, L.C., Cesar, C.L., (2000) Phys. Rev. B, 62 (11), pp. 7357-7364Cesar, C.L., Jacob, G.J., Tudury, G.E., Marquezini, M.V., Barbosa, L.C., (2004) Atti della Fondazione G. Ronchi Journal, (4), pp. 519-528. , Anno LI

Correlations in the Sine-Gordon Model with Finite Soliton Density

We study the sine-Gordon (SG) model at finite densities of the topological charge and small SG interaction constant, related to the one-dimensional Hubbard model near half-filling. Using the modified WKB approach, we find that the spectrum of the Gaussian fluctuations around the classical solution reproduces the results of the Bethe ansatz studies. The modification of the collective coordinate method allows us to write down the action, free from infra-red divergencies. The behaviour of the density-type correlation functions is non-trivial and we demonstrate the existence of leading and sub-leading asymptotes. A consistent definition of the charge-raising operator is discussed. The superconducting-type correlations are shown to decrease slowly at small soliton densities, while the spectral weight of right (left) moving fermions is spread over neighboring "4k_F" harmonics.Comment: 12 pages, 3 eps figures, REVTEX; a discussion of fermions is adde

A five year longitudinal study investigating the prevalence of childhood obesity: comparison of BMI and waist circumference.

Objective: The purpose of this study was to examine the prevalence of obesity over time in the same individuals comparing body mass index (BMI), waist circumference (WC) and waist to height ratio (WHtR). Study design: Five year longitudinal repeated measures study (2005–2010). Children were aged 11–12 (Y7) years at baseline and measurements were repeated at age 13–14 (Y9) years and 15–16 (Y11) years. Methods: WC and BMI measurements were carried out by the same person over the five years and raw values were expressed as standard deviation scores (sBMI and sWC) against the growth reference used for British children. Results: Mean sWC measurements were higher than mean sBMI measurements for both sexes and at all assessment occasions and sWC measurements were consistently high in girls compared to boys. Y7 sWC = 0.792 [95% confidence interval (CI) 0.675–0.908], Y9 sWC = 0.818 (95%CI 0.709–0.928), Y11 sWC = 0.943 (95%CI 0.827–1.06) for boys; Y7 sWC = 0.843 (0.697–0.989), Y9 sWC = 1.52 (95%CI 1.38–0.67), Y11 sWC = 1.89 (95%CI 1.79–2.04) for girls. Y7 sBMI = 0.445 (95%CI 0.315–0.575), Y9 sBMI = 0.314 (95%CI 0.189–0.438), Y11 sBMI = 0.196 (95%CI 0.054–0.337) for boys; Y7 sBMI = 0.353 (0.227–0.479), Y9 sBMI = 0.343 (95%CI 0.208–0.478), Y11 sBMI = 0.256 (95%CI 0.102–0.409) for girls. The estimated prevalence of obesity defined by BMI decreased in boys (18%, 12% and 10% in Y 7, 9 and 11 respectively) and girls (14%, 15% and 11% in Y 7, 9 and 11). In contrast, the prevalence estimated by WC increased sharply (boys; 13%, 19% and 23%; girls, 20%, 46% and 60%). Conclusion: Central adiposity, measured by WC is increasing alongside a stabilization in BMI. Children appear to be getting fatter and the additional adiposity is being stored centrally which is not detected by BMI. These substantial increases in WC are a serious concern, especially in girls

Coastal sedimentation across North America doubled in the 20th century despite river dams

The proliferation of dams since 1950 promoted sediment deposition in reservoirs, which is thought to be starving the coast of sediment and decreasing the resilience of communities to storms and sea-level rise. Diminished river loads measured upstream from the coast, however, should not be assumed to propagate seaward. Here, we show that century-long records of sediment mass accumulation rates (g cm−2 yr−1) and sediment accumulation rates (cm yr−1) more than doubled after 1950 in coastal depocenters around North America. Sediment sources downstream of dams compensate for the river-sediment lost to impoundments. Sediment is accumulating in coastal depocenters at a rate that matches or exceeds relative sea-level rise, apart from rapidly subsiding Texas and Louisiana where water depths are increasing and intertidal areas are disappearing. Assuming no feedbacks, accelerating global sea-level rise will eventually surpass current sediment accumulation rates, underscoring the need for including coastal-sediment management in habitat-restoration projects

A Systematic Study on Energy Dependence of Quasi-Periodic Oscillation Frequency in GRS 1915+105

Systematically studying all the RXTE/PCA observations for GRS 1915+105 before November 2010, we have discovered three additional patterns in the relation between Quasi-Periodic Oscillation (QPO) frequency and photon energy, extending earlier outcomes reported by Qu et al. (2010). We have confirmed that as QPO frequency increases, the relation evolves from the negative correlation to positive one. The newly discovered patterns provide new constraints on the QPO models

Anthropogenic impacts on tidal creek sedimentation since 1900

Land cover and use around the margins of estuaries has shifted since 1950 at many sites in North America due to development pressures from higher population densities. Small coastal watersheds are ubiquitous along estuarine margins and most of this coastal land-cover change occurred in these tidal creek watersheds. A change in land cover could modify the contribution of sediments from tidal creek watersheds to downstream areas and affect estuarine habitats that rely on sediments to persist or are adversely impacted by sediment loading. The resilience of wetlands to accelerating relative sea-level rise depends, in part, on the supply of lithogenic sediment to support accretion and maintain elevation; however, subtidal habitats such as oyster reefs and seagrass beds are stressed under conditions of high turbidity and sedimentation. Here we compare sediment accumulation rates before and after 1950 using 210Pb in 12 tidal creeks across two distinct regions in North Carolina, one region of low relief tidal-creek watersheds where land cover change since 1959 was dominated by fluctuations in forest, silviculture, and agriculture, and another region of relatively high relief tidal-creek watersheds where land-use change was dominated by increasing suburban development. At eight of the creeks, mass accumulation rates (g cm-2 y-1) measured at the outlet of the creeks increased contemporaneously with the largest shift in land cover, within the resolution of the land-cover data set (~5-years). All but two creek sites experienced a doubling or more in sediment accumulation rates (cm yr-1) after 1950 and most sites experienced sediment accumulation rates that exceeded the rate of local relative sea-level rise, suggesting that there is an excess of sediment being delivered to these tidal creeks and that they may slowly be infilling. After 1950, land cover within one creek watershed changed little, as did mass accumulation rates at the coring location, and another creek coring site did not record an increase in mass accumulation rates at the creek outlet despite a massive increase in development in the watershed that included the construction of retention ponds. These abundant tidal-creek watersheds have little relief, area, and flow, but they are impacted by changes in land cover more, in terms of percent area, than their larger riverine counterparts, and down-stream areas are highly connected to their associated watersheds. This work expands the scientific understanding of connectivity between lower coastal plain watersheds and estuaries and provides important information for coastal zone managers seeking to balance development pressures and environmental protections

Wide Angle Polarization Analysis with Neutron Spin Filters

AbstractWe report substantial improvements in a compact wide angle neutron spin filter system that was recently employed on the Multi- Axis Crystal Spectrometer at the Center for Neutron Research at the U.S. National Institute of Standards and Technology. The apparatus consists of a cylindrical 3He polarizer cell and wide-angle 3He analyzer cells, a vertical solenoid to provide a uniform magnetic field, and a shielded radio-frequency solenoid for the polarizer cell. Nuclear magnetic resonance is employed to reverse the polarization in the polarizer cell and monitor the 3He polarization in all cells. The first experiment using this apparatus was carried out with cylindrical analyzer cells with limited angular coverage due to low polarizations in fused quartz cells. We present results for aluminosilicate glass analyzer cells that cover 110 ∘ and have long relaxation times (100h to 400h). Using two 100W diode bars spectrally narrowed with chirped volume Bragg gratings, we have obtained 65% - 80% 3He polarization in these cells. The 3He polarization has been measured by neutron transmission and electron paramagnetic resonance. Additional progress includes an improved holding field solenoid and decreased spin-flip losses

Diet and lifestyle changes during the COVID-19 pandemic in Ibero-American countries: Argentina, Brazil, Mexico, Peru, and Spain

This study aimed to evaluate changes in dietary and lifestyle habits during the period of confinement due to the first wave of the COVID-19 pandemic in Ibero-American countries. A cross-sectional investigation was conducted with 6,325 participants of both genders (68% women), over 18 years of age and from five countries: Brazil (N = 2,171), Argentina (N = 1,111), Peru (N = 1,174), Mexico (N = 686), and Spain (N = 1,183). Data were collected during the year 2020, between April 01 and June 30 in Spain and between July 13 and September 26, in the other countries studied using a self-administered online survey designed for the assessment of sociodemographic, employment, physical activity, health status, and dietary habits changes. Most participants (61.6%), mainly those from Spain, remained constant, without improving or worsening their pattern of food consumption. Among those who changed, a pattern of better eating choices prevailed (22.7%) in comparison with those who changed toward less healthy choices (15.7%). Argentina and Brazil showed the highest proportion of changes toward a healthier pattern of food consumption. Peruvians and Mexicans were less likely to make healthy changes in food consumption (OR: 0.51; 95% CI: 0.4–0.6 and OR: 0.69; 95% CI: 0.4–0.8, respectively), when compared to Argentinians. Most respondents did not change their pattern of meal consumption, but those who did reduced their consumption of main meals and increased intake of small meals and snacks. Although most participants affirmed to be doing physical activity at home, about one-half reported perception of weight gain. Individuals with alterations in sleep pattern (either by increasing or decreasing sleep time) were more likely to change their diets to a healthier pattern. In contrast, individuals with confirmed diagnosis of COVID-19 and those who reported feeling anxious were more likely to perform changes to a less healthy eating pattern (OR: 1.72; 95% CI: 1.2–2.3 and OR: 1.21; 95% CI: 1.1–1.4, respectively). In conclusion, although most participants remained constant in their eating habits, lifestyle changes and anxiety feelings were reported. Among those who changed patterns of food consumption, healthier choices prevailed, with differences between countries. However, there were alterations in the distribution of meals, with higher consumption of snacks and small meals. These results can be used to guide policies to prevent deleterious consequences that may affect the incidence of chronic diseasesWe acknowledge the National Council for Scientific and Technological Development (CNPq) which provided MCBM a productivity fellowship and the Coordination for the Improvement of Higher Education Personnel (CAPES) which granted OE-M a Ph.D. scholarship. The project developed in Spain was supported by the Program of R&D activities between research groups of the Community of Madrid in Social Sciences and Humanities, co-financed with the European Social Fund (H2019/HUM-5802

Investigating Safety And Preliminary Efficacy Of Afm13 Plus Pembrolizumab In Patients With Relapsed/Refractory Hodgkin Lymphoma After Brentuximab Vedotin Failure

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149522/1/hon134_2629.pd

Spin-Charge Separation in the t−Jt-J Model: Magnetic and Transport Anomalies

A real spin-charge separation scheme is found based on a saddle-point state of the $t-J$ model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed-point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at {\em finite doping} so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic {\em residual} couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at ($\pi/a$, $\pi/a$) with a doping-dependent width ($\propto \sqrt{\delta}$, $\delta$ is the doping concentration). This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exits a characteristic temperature scale below which a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a {\em finite} energy regime. In transport, a strong short-range phase interference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-$T$ resistivity and $T^2$ Hall-angle. We discuss the striking similarities of these theoretical features with those found in the high-$T_c$ cuprates and give aComment: 70 pages, RevTex, hard copies of 7 figures available upon request; minor revisions in the text and references have been made; To be published in July 1 issue of Phys. Rev. B52, (1995