997 resultados para Unstable conditions


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We analysed the whole-genome transcriptional profile of 6 cell lines of dark melanocytes (DM) and 6 of light melanocytes (LM) at basal conditions and after ultraviolet-B (UVB) radiation at different time points to investigate the mechanisms by which melanocytes protect human skin from the damaging effects of UVB. Further, we assessed the effect of different keratinocyte-conditioned media (KCM+ and KCM-) on melanocytes. Our results suggest that an interaction between ribosomal proteins and the P53 signaling pathway may occur in response to UVB in both DM and LM. We also observed that DM and LM show differentially expressed genes after irradiation, in particular at the first 6h after UVB. These are mainly associated with inflammatory reactions, cell survival or melanoma. Furthermore, the culture with KCM+ compared with KCM- had a noticeable effect on LM. This effect includes the activation of various signaling pathways such as the mTOR pathway, involved in the regulation of cell metabolism, growth, proliferation and survival. Finally, the comparison of the transcriptional profiles between LM and DM under basal conditions, and the application of natural selection tests in human populations allowed us to support the significant evolutionary role of MIF and ATP6V0B in the pigmentary phenotype.

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The management of municipal solid waste (MSW), particularly the role of incineration, is currently a subject of public debate. Incineration shows to be a good alternative of reducing the volume of waste and eliminating certain infectious components. Moreover, Municipal Waste Incinerators (MWI), are reported to be highly hygienic and apart from that MWIs are immediately effective in terms of transport (incinerators can be built close to the waste sources) and incineration's nature. Nevertheless, the emissions of many hazardous substances make the Municipal Waste Incineration (MWI) plants to be unpopular. Metals (especially lead, manganese, cadmium, chromium and mercury) are concentrated in fly and bottom ashes. Furthermore, incomplete combustion produces a wide variety of potentially hazardous organic compounds, such as aldehydes, polycyclic aromatic hydrocarbons (PAH), chlorinated hydrocarbons including polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF), and even acid gases, including NOx. Many of these hazardous substances are carcinogenic and some have direct systemic toxicity.

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Background Quality of cardiopulmonary resuscitation (CPR) is key to increase survival from cardiac arrest. Providing chest compressions with adequate rate and depth is difficult even for well-trained rescuers. The use of real-time feedback devices is intended to contribute to enhance chest compression quality. These devices are typically based on the double integration of the acceleration to obtain the chest displacement during compressions. The integration process is inherently unstable and leads to important errors unless boundary conditions are applied for each compression cycle. Commercial solutions use additional reference signals to establish these conditions, requiring additional sensors. Our aim was to study the accuracy of three methods based solely on the acceleration signal to provide feedback on the compression rate and depth. Materials and Methods We simulated a CPR scenario with several volunteers grouped in couples providing chest compressions on a resuscitation manikin. Different target rates (80, 100, 120, and 140 compressions per minute) and a target depth of at least 50 mm were indicated. The manikin was equipped with a displacement sensor. The accelerometer was placed between the rescuer's hands and the manikin's chest. We designed three alternatives to direct integration based on different principles (linear filtering, analysis of velocity, and spectral analysis of acceleration). We evaluated their accuracy by comparing the estimated depth and rate with the values obtained from the reference displacement sensor. Results The median (IQR) percent error was 5.9% (2.8-10.3), 6.3% (2.9-11.3), and 2.5% (1.2-4.4) for depth and 1.7% (0.0-2.3), 0.0% (0.0-2.0), and 0.9% (0.4-1.6) for rate, respectively. Depth accuracy depended on the target rate (p < 0.001) and on the rescuer couple (p < 0.001) within each method. Conclusions Accurate feedback on chest compression depth and rate during CPR is possible using exclusively the chest acceleration signal. The algorithm based on spectral analysis showed the best performance. Despite these encouraging results, further research should be conducted to asses the performance of these algorithms with clinical data.

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Micro-scale abrasion (ball cratering) tests were performed with different combinations of ball and bulk specimen materials, under different test conditions, such as load and abrasive slurry concentration. Wear modes were classified into two types: with rolling particle motion and with grooving particle motion. Wear rates observed with rolling particle motion were relatively insensitive to test conditions, whereas with grooving motion they varied much more. It is suggested that rolling abrasion is therefore a more appropriate mode if reproducible test results are desired. The motion of the abrasive particles can be reliably predicted from the knowledge of hardnesses and elastic properties of the ball and the specimen, and from the normal load and the abrasive slurry concentration. General trends in wear resistance measured in the micro-scale abrasion test with rolling particle motion are similar to those reported in tests with fixed abrasives with sliding particle motion, although the variation in wear resistance with hardness is significantly smaller. © 2004 Published by Elsevier B.V.

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Abu Al Abyad island is characterized by harsh environmental conditions. A preliminary trial conducted at the island to investigate the spawning and hatching performance of the blue finned sea bream Sparidentex hasta indicated that the fish can be successfully bred at high salinity levels exceeding 50 ppt.