1,890 research outputs found
Electron-lattice kinetics of metals heated by ultrashort laser pulses
We propose a kinetic model of transient nonequilibrium phenomena in metals
exposed to ultrashort laser pulses when heated electrons affect the lattice
through direct electron-phonon interaction. This model describes the
destruction of a metal under intense laser pumping. We derive the system of
equations for the metal, which consists of hot electrons and a cold lattice.
Hot electrons are described with the help of the Boltzmann equation and
equation of thermoconductivity. We use the equations of motion for lattice
displacements with the electron force included. The lattice deformation is
estimated immediately after the laser pulse up to the time of electron
temperature relaxation. An estimate shows that the ablation regime can be
achieved.Comment: 7 pages; Revtex. to appear in JETP 88, #1 (1999
Recommended from our members
Cardiac Biomarkers and Risk of Atrial Fibrillation in Chronic Kidney Disease: The CRIC Study.
Background We tested associations of cardiac biomarkers of myocardial stretch, injury, inflammation, and fibrosis with the risk of incident atrial fibrillation (AF) in a prospective study of chronic kidney disease patients. Methods and Results The study sample was 3053 participants with chronic kidney disease in the multicenter CRIC (Chronic Renal Insufficiency Cohort) study who were not identified as having AF at baseline. Cardiac biomarkers, measured at baseline, were NT-proBNP (N-terminal pro-B-type natriuretic peptide), high-sensitivity troponin T, galectin-3, growth differentiation factor-15, and soluble ST-2. Incident AF ("AF event") was defined as a hospitalization for AF. During a median follow-up of 8 years, 279 (9%) participants developed a new AF event. In adjusted models, higher baseline log-transformed NT-proBNP (N-terminal pro-B-type natriuretic peptide) was associated with incident AF (adjusted hazard ratio [HR] per SD higher concentration: 2.11; 95% CI, 1.75, 2.55), as was log-high-sensitivity troponin T (HR 1.42; 95% CI, 1.20, 1.68). These associations showed a dose-response relationship in categorical analyses. Although log-soluble ST-2 was associated with AF risk in continuous models (HR per SD higher concentration 1.35; 95% CI, 1.16, 1.58), this association was not consistent in categorical analyses. Log-galectin-3 (HR 1.05; 95% CI, 0.91, 1.22) and log-growth differentiation factor-15 (HR 1.16; 95% CI, 0.96, 1.40) were not significantly associated with incident AF. Conclusions We found strong associations between higher NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity troponin T concentrations, and the risk of incident AF in a large cohort of participants with chronic kidney disease. Increased atrial myocardial stretch and myocardial cell injury may be implicated in the high burden of AF in patients with chronic kidney disease
Improving the prognostic value of blunt abdominal trauma scoring systems in children
Purpose Blunt abdominal trauma (BAT) is a frequent reason for hospital admission and a significant cause of death in children older than 2 years of age. Mechanisms causing abdominal injuries are predominantly motorvehicle accidents, falls, and intentional injuries. Blunt trauma accounts for 90% of pediatric injuries. There are many scoring systems that are designed to monitor victims of BAT and to predict victims who may require conservative management and those who may require surgical intervention. None of these scoring systems is perfect and fulfill the data for accurate prediction of the prognosis of these victims. We assessed three different clinical scoring systems and their prognostic properties alone and after their modification by adding a plain, erect, abdominal radiographic film to improve their prognostic values.Patients and methods We included all patients presenting with BAT older than 2 years and younger than 18 years. All children were subjected to three different trauma scoring systems. We evaluated all children usingPediatric Trauma Score, Clinical Abdominal Score System, and Blunt Abdominal Trauma in Children. We then added plain, erect, abdominal radiographic films to these systems.Results A total of 250 children with BAT were subjected to three different scoring systems. Among them, 58% were boys and 42% were girls. The cause for BAT in two hundred and two cases was car accidents, falling from heights in seven, and kicks and abuse in 41 cases. The mean time until hospital arrival was 2 h. The mean age was 15 years. The mean time for every scoring system was 5 min. Radiographic imaging showed positive signs of trauma (air under diaphragm, elevated copula of diaphragm) in 45 patients.Conclusion Adding a simple radiographic film in the erect position of the abdomen and lower chest markedly improved the prognostic value of the different scoring systems included. Keywords: children, scoring systems, traum
Prospects for terahertz imaging the human skin cancer with the help of gold-nanoparticles-based terahertz-to-infrared converter
The design is suggested, and possible operation parameters are discussed, of
an instrument to inspect a skin cancer tumour in the terahertz (THz) range,
transferring the image into the infrared (IR) and making it visible with the
help of standard IR camera. The central element of the device is the THz-to-IR
converter, a Teflon or silicon film matrix with embedded 8.5 nm diameter gold
nanoparticles. The use of external THz source for irradiating the biological
tissue sample is presumed. The converter's temporal characteristics enable its
performance in a real-time scale. The details of design suited for the
operation in transmission mode (in vitro) or on the human skin in reflection
mode {in vivo) are specified.Comment: To be published in the proceedings of the FANEM2018 workshop - Minsk,
3-5 June 201
Enrichment of antioxidant capacity and vitamin E in pita made from barley
This study aimed to enhance total antioxidant and vitamin E content of pita bread, by replacing 50% of the standard baker's flour with flours milled from covered (WI2585 and Harrington) or hulless (Finniss) barley genotypes, previously shown to have high antioxidant and vitamin E levels at harvest. Pita breads were made from either 100% baker's flour (control) or 50% malt flour, whole-grain flour, or flour from barley grains pearled at 10%, 15%, and 20% grain weight. Antioxidant capacity and vitamin E content of flours and pitas were determined by their ability to scavenge 2,2-diphenyl-1-picrylhydrazyl radicals and high performance liquid chromatography, respectively. The physical and sensory properties of the pitas were also assessed. All pitas made from either whole grain or pearled barley flour had a higher antioxidant capacity and most also had higher vitamin E content than standard pita. The antioxidant and vitamin E levels were reduced in pearled compared to whole grains, however the extent of that reduction varied among genotypes. The greatest antioxidant and vitamin E levels were found in pita made from malt flour or Finniss whole grain flour. Furthermore, sensory analysis suggested these pitas were acceptable to consumers and retained similar physical and sensory properties to those in the control pita.Thi Thu Dung Do, Beverly Muhlhausler, Amanda Box and Amanda J. Abl
Efficient multiscale modeling of heterogeneous materials using deep neural networks
Material modeling using modern numerical methods accelerates the design process and reduces the costs of developing new products. However, for multiscale modeling of heterogeneous materials, the well-established homogenization techniques remain computationally expensive for high accuracy levels. In this contribution, a machine learning approach, convolutional neural networks (CNNs), is proposed as a computationally efficient solution method that is capable of providing a high level of accuracy. In this work, the data-set used for the training process, as well as the numerical tests, consists of artificial/real microstructural images (“input”). Whereas, the output is the homogenized stress of a given representative volume element RVE . The model performance is demonstrated by means of examples and compared with traditional homogenization methods. As the examples illustrate, high accuracy in predicting the homogenized stresses, along with a significant reduction in the computation time, were achieved using the developed CNN model
Needs assessment to strengthen capacity in water and sanitation research in Africa:experiences of the African SNOWS consortium
Despite its contribution to global disease burden, diarrhoeal disease is still a relatively neglected area for research funding, especially in low-income country settings. The SNOWS consortium (Scientists Networked for Outcomes from Water and Sanitation) is funded by the Wellcome Trust under an initiative to build the necessary research skills in Africa. This paper focuses on the research training needs of the consortium as identified during the first three years of the project
Mastitogenic Bacteria Isolated from Clinical Mastitis Cases Associated with Teat Lesions and their Antimicrobial Sensitivity
Mastitis is the most common and most expensive disease that impacts dairy farms in Egypt. In this study, we investigated bacterial mastitis cases that did not respond to antimicrobial treatment from buffaloes and cows. Milk samples (11) were collected from diseased animals (5 buffaloes and 6 cows). The samples were tested microbiologically to isolate and identify the causative bacteria and antimicrobial susceptibility. The antimicrobial sensitivity of the isolated bacteria was tested by using minimum inhibitory concentration technique according to the clinical national laboratory standards. The total number of bacterial isolates from the cases was 15 isolates. Staphylococcus aureus (S. aureus) was isolated alone in two cases (13.33% of the isolates), and S. aureus isolated in combination with Arcanobacterium pyogenes (A. pyogenes) in one case (6.67%), and S. aureus isolated in combination with both A. pyogenes and Streptococcus agalactiae (S. agalactiae) in two cases (13.33%), and Coagulase negative staphylococci (CNS) isolated alone in one case (6.67%), and CNS isolated in combination with Klebsiella pneumoniae in one case (6.67%), and A. pyogenes isolated alone in two cases (13.33%). In two cases were not able to isolate any bacterial pathogen. In terms of susceptibility to antibiotics, the isolated strains were sensitive to clindamycin with MICs ranging from 0.125 to <0.03125 µM. The same isolates exhibited medium sensitivity to gentamicin and ciprofloxacin with MICs ranging from 0.5 to 8 µM. Most S. aureus isolates were resistant to oxytetracycline with a MIC of 128 µM. Most of the isolated bacteria were resistant to polymyxin B with a MIC > 128 µM. With the exception of the A. pyogenes isolates, all the isolated bacteria were sensitive to enrofloxacin with a MIC <1 µM.  
- …
