Dynamics of femtosecond laser-induced melting and amorphization of indium phosphide

7 pages, 5 figures.-- PACS: 64.70.Dv; 81.30.Fb; 61.80.Ba; 78.66.Fd; 61.82.FkLaser-induced melting and resolidification of single-crystalline indium phosphide (InP) upon irradiation with 150 fs laser pulses at 800 nm has been investigated by means of real-time-reflectivity measurements with subnanosecond time resolution. Melting of the surface is observed to occur very rapidly on a time scale shorter than our experimental resolution while the lifetime of the liquid phase is several tens of nanoseconds. As a result of the subsequent rapid solidification process, a thin layer of amorphous material with a thickness of several tens of nanometers is formed on the surface. The formation of this amorphous layer has been observed for every fluence above the melting and below the ablation threshold. The evolution of the reflectivity has been modeled for several different solidification scenarios and compared to the experimental results. This comparison shows that solidification proceeds interfacially from the solid interface towards the surface. A lower limit for the critical solid-liquid interface velocity for amorphization in this compound semiconductor has been estimated to be in the range of 1–4 m/s.This work has been partially supported by the EU in the frame of the TMR Project XPOSE (Grant No. HPRN-CT- 2000-00160). S.M.W. acknowledges the funding in the frame of the same project. J.B. acknowledges the funding of the CSIC through a contract in the frame of the I3P programme (Ref. I3P-PC2002), co-funded by the European Social Fund.Peer reviewe

Управление денежными потоками на предприятии

Цель работы - разработка предложений по улучшению механизма управления денежными потоками, на основе проведенного анализа деятельности предприятия ООО «ПМК-Томь». Предмет исследования – финансовые процессы на предприятии ООО «ПМК-Томь», связанные с формированием и движением денежных потоков. Объектом исследования является финансово-хозяйственная деятельность предприятия ООО «ПМК-Томь». В процессе исследования проводился анализ теоретических аспектов управления денежными потоками; анализ финансово-хозяйственной деятельности предприятия; анализ денежных потоков предприятия. В результате исследования были разработаны предложения по повышению эффективности управления денежными потоками.The work purpose - development of offers on improvement of the mechanism of cash flow management, on the basis of the conducted analysis of activity. Subject of research – financial processes at the company, associated with the formation and movement of cash flows. The object of study is the financial-economic activity. In the process of investigation the analysis of theoretical aspects of the management of cash flows; analysis of financial and economic activity of the enterprise; the analysis of cash flows of the company. The study proposals have been developed for improving the effectiveness of cash flow management

Cholinergic Input Is Required during Embryonic Development to Mediate Proper Assembly of Spinal Locomotor Circuits

SummaryRhythmic limb movements are controlled by pattern-generating neurons within the ventral spinal cord, but little is known about how these locomotor circuits are assembled during development. At early stages of embryogenesis, motor neurons are spontaneously active, releasing acetylcholine that triggers the depolarization of adjacent cells in the spinal cord. To investigate whether acetylcholine-driven activity is required for assembly of the central pattern-generating (CPG) circuit, we studied mice lacking the choline acetyltransferase (ChAT) enzyme. Our studies show that a rhythmically active spinal circuit forms in ChAT mutants, but the duration of each cycle period is elongated, and right-left and flexor-extensor coordination are abnormal. In contrast, blocking acetylcholine receptors after the locomotor network is wired does not affect right-left or flexor-extensor coordination. These findings suggest that the cholinergic neurotransmitter pathway is involved in configuring the CPG during a transient period of development

Solid-State and Gas-Phase Structures and Energetic Properties of the Dangerous Methyl and Fluoromethyl Nitrates

Reichel M, Krumm B, Vishnevskiy Y, et al. Solid-State and Gas-Phase Structures and Energetic Properties of the Dangerous Methyl and Fluoromethyl Nitrates. Angewandte Chemie (International ed. in English). 2019;58(51):18557-18561.An improved synthesis of the simplest nitric acid ester, methyl nitrate, and a new synthesis of fluoromethyl nitrate use the metathesis of the corresponding iodomethanes with silver nitrate. Both compounds were identified by spectroscopy and the structures determined for in situ grown crystals by X-ray diffraction as well as in the gas phase by electron diffraction. Fluorination leads to structures with shorter C-O and N-O bonds, has an energetically destabilizing effect and increases friction sensitivity, but decreases detonation performance. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

HistMapR: rapid digitization of historical land-use maps in R

1. Habitat destruction and degradation represent serious threats to biodiversity, and quantification of land-use change over time is important for understanding the consequences of these changes to organisms and ecosystem service provision. 2. Comparing land use between maps from different time periods allows estimation of the magnitude of habitat change in an area. However, digitizing historical maps manually is time-consuming and analyses of change are usually carried out at small spatial extents or at low resolutions. 3. HistMapR contains a number of functions that can be used to semi-automatically digitize historical land use according to a map's colours, as defined by the RGB bands of the raster image. We test the method on different historical land-use map series and compare results to manual digitizations. 4. Digitization is fast, and agreement with manually digitized maps of around 80–90% meets common targets for image classification. We hope that the ability to quickly classify large areas of historical land use will promote the inclusion of land-use change into analyses of biodiversity, species distributions and ecosystem services

Soluciones terapéuticas para la reconstrucción de la dermis y la epidermis. Oportunidades en el medio antioqueño

En Antioquia, es necesario buscar una solución disponible, efectiva y económicamente viable para afrontar los problemas de la piel de los pacientes que, por accidentes o enfermedades, han disminuido su calidad de vida y se encuentran aislados a la espera de tratamientos que les permitan recuperar la funcionalidad de su cuerpo y les reduzcan los riesgos por la exposición de los tejidos internos. Las diferentes soluciones existentes en el mercado todavía no han llegado a superar algunos obstáculos tales como el cubrimiento de todas las extensiones, los altos costos, la funcionalidad de los tejidos restaurados, los rechazos de tipo inmune y la escasez de los sitios donantes. Este artículo presenta una revisión literaria que busca mostrar las diferentes alternativas de solución para pacientes con problemas de piel, dando énfasis en las soluciones clásicas aplicables y económicamente viables desde la ingeniería de tejidos en el sector antioqueño.In Antioquia (Colombia), there are many patients who suffer dermal injuries caused by accident or disease. Therefore, it is necessary to pursue available, effective and affordable solutions to overcome dermal problems. Physicians and patients are both expecting corrective treatments that can reduce inner tissue exposition and allow the possibility of recovering skin functionality. Although there are many solutions for skin replacement, some obstacles remain, such as: high costs, limited availability of skin for implantation in extended areas, adequate functionality of the restored tissue and immunological rejection. Due to these issues, this article presents some of the existing alternative solutions for patients with skin injuries, considering the histology and physiology of the skin, and regarding the classical and economically attainable solutions to be used in Antioquia

The Chemical Composition of Carbon-Rich, Very Metal-Poor Stars: A New Class of Mildly Carbon-Rich Objects Without Excess of Neutron-Capture Elements

We report on an analysis of the chemical composition of five carbon-rich, very metal-poor stars based on high-resolution spectra. One star, CS22948-027, exhibits very large overabundances of carbon, nitrogen, and the neutron-capture elements, as found in the previous study of Hill et al.. This result may be interpreted as a consequence of mass transfer from a binary companion that previously evolved through the asymptotic giant branch stage. By way of contrast, the other four stars we investigate exhibit no overabundances of barium ([Ba/Fe]<0), while three of them have mildly enhanced carbon and/or nitrogen ([C+N]+1). We have been unable to determine accurate carbon and nitrogen abundances for the remaining star (CS30312-100). These stars are rather similar to the carbon-rich, neutron-capture-element-poor star CS22957-027 discussed previously by Norris et al., though the carbon overabundance in this object is significantly larger ([C/Fe]=+2.2). Our results imply that these carbon-rich objects with ``normal'' neutron-capture element abundances are not rare among very metal-deficient stars. One possible process to explain this phenomenon is as a result of helium shell flashes near the base of the AGB in very low-metallicity, low-mass (M~< 1M_sun) stars, as recently proposed by Fujimoto et al.. The moderate carbon enhancements reported herein ([C/Fe]+1) are similar to those reported in the famous r-process-enhanced star CS22892-052. We discuss the possibility that the same process might be responsible for this similarity, as well as the implication that a completely independent phenomenon was responsible for the large r-process enhancement in CS22892-052.Comment: 53 pages, 8 figures, to appear in Ap