6,954 research outputs found
On-Line Processing and Computer Control in High Resolution Transmission Electron Microscopy
Recent advances in hardware and software make it possible to perform real-time image processing, and to do simultaneous analysis of the image characteristics in the transmission electron microscope (TEM). We have used a commercially available image processor and a suitable computer/TEM interface to build a automated computer-control system for a JEOL 4000EX TEM. We report here the characteristics of the system, which has direct access to all electronic controls of a JEOL 4000EX. The various microscope parameters are set by changing one parameter at a time while the image processor measures a specific image variable such as the variance. From the plot of the variable the program select its optimum value. Through-focus series are taken at the speed of one frame per second, which allows time for reaching electron lens stability, storage of the image, calculation of parameters such as contrast, and the plotting of values; all of this occuring while the image series is being generated. Results obtained using this system for on-line processing and computer control for crystalline and amorphous materials are presented
Barriers to Breast Cancer-Screening Adherence in Vulnerable Populations
: Breast cancer screening through periodic mammography has been effective in decreasing mortality and reducing the impact of this disease. However, adherence to screening does not meet the desired expectations from all populations. The main objective of this review is to explore the barriers that affect adherence to breast cancer-screening programs in vulnerable populations according to race and/or ethnicity in order to propose measures to reduce the lack of adherence. We conducted a search of publications in the PubMed Central and Scopus databases. The eligible criteria for the articles were as follows: original quantitative studies appearing in SJR- and/or JCR-indexed journals from 2016 to 2021 in English or Spanish. Most of them present common barriers, such as race/ethnicity (47%), low socioeconomic (35.3%) and educational levels (29.4%), no family history of cancer and being single (29.4%), medical mistrust and a health information gap (23.5%), lack of private health insurance (17.6%) and not having annual health checks (17.6%). The target populations with the lowest adherence were Black, Asian, Hispanic and foreign women. Implementing awareness campaigns focused on these populations should be promoted, as well as working on diversity, cultural acceptance and respect with healthcare workers, in order to improve breast cancer-screening adherence worldwide
High coercivity induced by mechanical milling in cobalt ferrite powders
In this work we report a study of the magnetic behavior of ferrimagnetic
oxide CoFe2O4 treated by mechanical milling with different grinding balls. The
cobalt ferrite nanoparticles were prepared using a simple hydrothermal method
and annealed at 500oC. The non-milled sample presented coercivity of about 1.9
kOe, saturation magnetization of 69.5 emu/g, and a remanence ratio of 0.42.
After milling, two samples attained coercivity of 4.2 and 4.1 kOe, and
saturation magnetization of 67.0 and 71.4 emu/g respectively. The remanence
ratio MR/MS for these samples increase to 0.49 and 0.51, respectively. To
investigate the influence of the microstructure on the magnetic behavior of
these samples, we used X-ray powder diffraction (XPD), transmission electron
microscopy (TEM), and vibrating sample magnetometry (VSM). The XPD analysis by
the Williamson-Hall plot was used to estimate the average crystallite size and
strain induced by mechanical milling in the samples
Semi-Analytical Estimation for the Escape of Solutions of Linear Differential Equations with Slowly Varying Coefficients
Emerging vibrations are a major and often unpredictable limitation in engineering design. The engineering description of these vibrations is usually based on linear models with constant parameters. However, in reality, this is rarely the case and parameters do vary in engineering systems during operation. Among these systems, we consider the simplest case: a scalar system with two time scales, one fast describing the process dynamics, and another slow for parameter change. It has been noted that at a bifurcation point, going from stable to unstable, dynamical systems are resilient and do not immediately lose stability. However, traditional numerical schemes are not able to handle this situation, and numerical solutions cannot be trusted.
We present and test a method for approximating solutions, and we name these approximations \textit{semi-analytical solutions};
we rigorously prove the efficacy of the method. Our main result shows that semi-analytical solutions exist beyond the bifurcation time
One Step Non SUSY Unification
We show that it is possible to achieve one step gauge coupling unification in
a general class of non supersymmetric models which at low energies have only
the standard particle content and extra Higgs fields doublets. The constraints
are the experimental values of , and
at , and the lower bounds for FCNC and proton decay rates. Specific
example are pointed out.Comment: 10 pages, Latex file,, uses epsf style, Two Postscript figures
included. To appear in Europhysics Letter
Semilinear equations with exponential nonlinearity and measure data
We study the existence and non-existence of solutions of the problem [GRAPHICS] where Omega is a bounded domain in R-N, N >=, 3, and it is a Radon measure. We prove that if it 4 pi HN-2, then (0.1) has a unique solution. We also show that the constant 4 pi in this condition cannot be improved. (c) 2005 Elsevier SAS. All rights reserved
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Liquidity Creation and Bank Capital
This paper aims to evaluate the relationship between capital and liquidity following the implementation of the Basel III rules. These regulatory measures target both increased capital ratios and a reduction of banks’ maturity transformation risk , which could result in excessive constraints on bank liquidity creation, thereby negatively affecting economic growth. Using a simultaneous equation model, we find a bi-causal negative relationship, which suggests that banks may reduce liquidity creation as capital increases; and when liquidity creation increases, banks reduce capital ratios. Our results therefore imply a trade-off between financial stability (higher capital, reduced risk) and economic growth (liquidity creation)
Concentration of atomic hydrogen diffused into silicon in the temperature range 900–1300 °C
Boron-doped Czochralski silicon samples with [B]~1017 cm−3 have been heated at various temperatures in the range 800–1300 °C in an atmosphere of hydrogen and then quenched. The concentration of [H-B] pairs was measured by infrared localized vibrational mode spectroscopy. It was concluded that the solubility of atomic hydrogen is greater than [Hs] = 5.6 × 1018 exp( − 0.95 eV/kT)cm−3 at the temperatures investigated
Spatial prioritization for biodiversity conservation in a megadiverse country
Mexico is a biologically megadiverse country, but its biodiversity is endangered due to high deforestation rates. Impacts of land-use/cover-change and climate change are unevenly distributed, which hinders the execution of conservation practices. Consequently, an adequate spatial conservation prioritization is crucial to minimize the negative impacts on biodiversity. Global and national efforts to prioritize conservation show that >45 % of Mexico should be protected. This study develops an applicable spatial conservation prioritization to minimize impacts on biodiversity, under three scenarios. They integrate exposure to land-use/cover-change and climate change scenarios, adaptive capacity to deal with the exposure, and the distribution of endemic species on risk of extinction. Our results show that by 2050 between 11.6 %, 13.9 % and 16.1 % of Mexico would reach score ≥50 in vulnerability (VI), under the optimistic, BAU, and the worst-case scenarios, respectively. By 2070, these figures would rise to 11.9 %, 14.8 % and 18.4 %. Amphibians are the most threatened vertebrates with 62.2 % of endemic species being critically endangered or endangered, while 39.2 %, 11.8 %, and 8.5 % of endemic mammals, birds and reptiles are endangered or critically endangered. The distribution of these amphibians accounts for 3.3 % of the country’s area, while mammals, birds, and reptiles represent 9.9 %, 16.2 %, and 28.7 % of Mexico. Moreover, seven municipalities (0.39 % of the country) represent 30 % of the most vulnerable areas (VI = 70). This study offers relevant information at the levels of municipality and species to help decision-makers prioritize national efforts for the conservation of ecosystems and biodiversity under land-use/cover and climate change. This study is replicable in other regions which aim to adapt decision-making and land management for biodiversity conservation
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