839 resultados para Parameters influencing the characteristics of short fibre -polymer composites
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Background: Recently, with the access of low toxicity biological and targeted therapies, evidence of the existence of a long-term survival subpopulation of cancer patients is appearing. We have studied an unselected population with advanced lung cancer to look for evidence of multimodality in survival distribution, and estimate the proportion of long-term survivors. Methods: We used survival data of 4944 patients with non-small-cell lung cancer (NSCLC) stages IIIb-IV at diagnostic, registered in the National Cancer Registry of Cuba (NCRC) between January 1998 and December 2006. We fitted one-component survival model and two-component mixture models to identify short-and long-term survivors. Bayesian information criterion was used for model selection. Results: For all of the selected parametric distributions the two components model presented the best fit. The population with short-term survival (almost 4 months median survival) represented 64% of patients. The population of long-term survival included 35% of patients, and showed a median survival around 12 months. None of the patients of short-term survival was still alive at month 24, while 10% of the patients of long-term survival died afterwards. Conclusions: There is a subgroup showing long-term evolution among patients with advanced lung cancer. As survival rates continue to improve with the new generation of therapies, prognostic models considering short-and long-term survival subpopulations should be considered in clinical research.
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Currently entrepreneurship is a basic pillar in the socioeconomic area of any country since it contributes to attain the government objectives of job creation and boost of dynamism and competitiveness of the business network. These aspects are even more crucial nowadays due to the global economic crisis. This paper attempts to provide some new insights about the scientific field entrepreneurship in the Basque Country analyzing some aspects related to the entrepreneurial activity, the profile of the entrepreneur and the characteristics of the entrepreneurial businesses. It also aims to provide empirical evidence that proves the good features of the spin-offs and TBF groups as job creators, technology transferors to the society and important actors in the growth and development of the economies for both the business network and its surrounding society. To this aim, a descriptive study has been performed of the firms belonging to the Zitek Program of Bizkaia Campus of the University of the Basque Country (UPV/EHU).
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Identification of the spatial scale at which marine communities are organized is critical to proper management, yet this is particularly difficult to determine for highly migratory species like sharks. We used shark catch data collected during 2006–09 from fishery-independent bottom-longline surveys, as well as biotic and abiotic explanatory data to identify the factors that affect the distribution of coastal sharks at 2 spatial scales in the northern Gulf of Mexico. Centered principal component analyses (PCAs) were used to visualize the patterns that characterize shark distributions at small (Alabama and Mississippi coast) and large (northern Gulf of Mexico) spatial scales. Environmental data on temperature, salinity, dissolved oxygen (DO), depth, fish and crustacean biomass, and chlorophyll-a (chl-a) concentration were analyzed with normed PCAs at both spatial scales. The relationships between values of shark catch per unit of effort (CPUE) and environmental factors were then analyzed at each scale with co-inertia analysis (COIA). Results from COIA indicated that the degree of agreement between the structure of the environmental and shark data sets was relatively higher at the small spatial scale than at the large one. CPUE of Blacktip Shark (Carcharhinus limbatus) was related positively with crustacean biomass at both spatial scales. Similarly, CPUE of Atlantic Sharpnose Shark (Rhizoprionodon terraenovae) was related positively with chl-a concentration and negatively with DO at both spatial scales. Conversely, distribution of Blacknose Shark (C. acronotus) displayed a contrasting relationship with depth at the 2 scales considered. Our results indicate that the factors influencing the distribution of sharks in the northern Gulf of Mexico are species specific but generally transcend the spatial boundaries used in our analyses.
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A pilot study on the characteristics of crab pot buoy line movements to assess bottlenose dolphin entanglement was conducted from 19 September to 30 September 2005 in the Charleston Harbor, Charleston, South Carolina. The objectives of this study were to determine: 1) the movements of the buoy line in the water at various tidal stages, current strengths, lengths of line, and water depth, 2) if lead-core rope was a better alternative to nylon rope, 3) and if the manner of deployment of the gear affected the suspension of the line in the water and on the bottom. Diamond braided nylon (#10) rope of varying length (20 ft. – 80 ft.) were used during 31 trials and stiffened (polypropylene lead-core) rope was used in four trials. Observations of the buoy line movements were captured with an Atlantis underwater camera attached to a Digital DPC-1000 video recorder. Results from this study showed that: 1) the method used for deployment was important in keeping the buoy line from arcing or coiling, 2) little to no arcing occurred in water current velocities of >0.20 m/s, 3) rope lengths of ≥50 ft. deployed in <10 ft. of water produced waving in the water column and arcing on the bottom, 4) slack tide was a period of increased risk of entanglement for bottlenose dolphins, and 5) poly lead-core rope was not a good alternative to nylon rope unless in deep water with strong water current velocities. This pilot study produced questions that can be used for future studies on the characteristics of buoy line movements in the crab pot fishery as it relates to bottlenose dolphin entanglements.
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The characteristics of the fish and prawn seed resources of the Gulf of Kutch are described. Results of experiments conducted in a primary low saline reservoir of a solar salt works to study their utility for aquaculture are reported. The prospective role of aquaculture in augmenting fish production along the coast is also discussed.
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The effect of vitamins C and E on some of growth factors of cultured Acipenser ruthenus was studied in this thesis. For this purpose diets supplemented with a combination of 100 and 400 mg/kg vitamin C, L-ascorbyl-2-polyphosphate and 100 and 400 mg/kg vitamin E, D-alpha-tocopherol,were each fed to sterlet in 2 replications for 15 weeks. Fifteen fish with average weight of 350.92±14.28 gr were distributed to each of 18 tanks after adaptation with experimental diet. After 5 weeks, there were significant differences in RBC, ESR, HCT and differential counting of white blood cells among the treatments (P<0.05), but there was no significant difference in the amount of WBC among the treatments (P>0.05). After 10 weeks, there were significant differences in the amounts of Monocytes, Lymphocytes and Eosinophils (P<0.05), but there was no significant differences in the amount of other hematologic factors (P>0.05). At the end of the experiment (15th week) only WBC, RBC, Monocyte, lymphocyte and neutrophil showed significant differences between the treatments (P<0.05) and other hematologic factors did not show any significant differences between the treatments (P>0.05). The results of biochemical indices analysis showed significant differences (P<0.05) among treatments for all of the parameters for 5th weeks, total protein and glucose for 10th week and only cholesterol for 15th week. The carcass analysis at the end of experiment showed that only the amount of carbohydrate, protein and ash were significantly difference between the treatments (P<0.05). The results of growth parameters at the end of 3th, 9th, 12th and 15th week showed significant differences between the treatments (P<0.05), but at the end of 6th week only GR was significantly different between the treatments (P<0.05). After concerning acute stress test including reduce water volume, cutting the aeration for 30 minutes at the end of experiment, cortisol and glucose significantly increased (P<0.05) compared with prestress period, but the lowest response to the stressor was observed in fish fed by E400 C 400 mg/kg. On the other hand the survival was 100% during the experiment and no mortality was occurred during this period. Results of this study indicate that Vitamins C and E can have remarkable effects on hematological, biochemical and growth indices in different growth periods. So regarding the effects of vitamin C and E on some growth indices, it seems that the diet containing E400 C 100 mg/kg can be considered as the optimum diet in the rearing condition for this weigth range of fish.
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In order to study of the artificial propagation efficiency in white fish (Coregonus lavaretus) and its fingerlings producing in IRAN, a 9 mounts study project was been done which during it, the characteristics of the matures and brood stocks fishes, the condition of their natural and artificial propagation, and the characteristics of produced frys, were been studied. Throughout the total 82 pieces caught fishes during September til February 2003, 10 pieces of them were the female brood stocks which during the catch time did not have spouse. The study of these fishes showed that there was no significant correlation between their weight and their length. The most and the least absolute fecundity of these brood stocks were 19120 and 11496 respectively. The artificial propagation was been done by 5 males and 4 females broods took which 57602 ova, with 89/2% fertilization rate, earned from them. The incubation period prolonged 55 days in 8°c. At the end of the incubation, 23913 larvae released. So the artificial propagation efficiency was calculated 41/51% in this study. Yolk sack absorption prolonged 4 days. 3 different food treatment were considered for fry breeding which contain of Brachiouns plicatilis as live food, salmon starter food as commercial food, and the mixed of equal amounts of live and commercial foods as third treatment. For each treatment, 3 repeat has been considered. Breeding duration prolonged 13 weeks throughout this period, different characteristics of fry were been studied weekly. The breeding results showed that there was very significant correlation between the weight and the length of frys. However the live food provided better results in growth and survival rate of frys during breeding initial 6 weeks. More ever, commercial food, in some characteristics, provided more acceptable results in comparing the live food after sixth week. The results of this study project showed that the artificial propagation in whitefish is possible in IRAN and the producing of its frys in order to restocking or introducing this species to the other Iranian suitable water resources is executable. Based on the earned information from this study, the suitable time for natural spawning of whitefish in IRAN (Amirkabir dam lake) determined between 10th January til 20th February.
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This work is concerned with the characteristics of the impact force produced when two randomly vibrating elastic bodies collide with each other, or when a single randomly vibrating elastic body collides with a stop. The impact condition includes a non-linear spring, which may represent, for example, a Hertzian contact, and in the case of a single body, closed form approximate expressions are derived for the duration and magnitude of the impact force and for the maximum deceleration at the impact point. For the case of two impacting bodies, a set of algebraic equations are derived which can be solved numerically to yield the quantities of interest. The approach is applied to a beam impacting a stop, a plate impacting a stop, and to two impacting beams, and in each case a comparison is made with detailed numerical simulations. Aspects of the statistics of impact velocity are also considered, including the probability that the impact velocity will exceed a specified value within a certain time. © 2012 Elsevier Ltd. All rights reserved.
Thermogravimetric study on the hydration of reactive magnesia and silica mixture at room temperature
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The synthesis of magnesium silicate hydrate (MSH), which has wide applications in both construction and environmental fields, has been studied for decades. However, it is known that the characteristics of magnesia (MgO) vary significantly depending on their calcination conditions, which is expected to affect their performance in the MgO-SiO2-H2O system. This paper investigated the effect of different MgO and silica sources on the formation of magnesium silicate hydrate (MSH) at room temperature. The hydration process was studied by mixing commercial reactive MgO and silica powders with water and curing for 1, 7 and 28 days. The hydration products were analysed with the help of X-ray diffraction (XRD) and thermogravimatric analysis (TGA). The results showed the continuous consumption of MgO and the existence of MSH and brucite and other minor phases such as magnesite and calcite. It is found that the Mg and Si sources have significant effect on the hydration process of MgO-SiO2-H2O system. The reaction degree is controlled by the availability of dissolved Mg and Si in the solution. The former is determined by the reactivity of MgO and the latter is related to the reactivity of the silica as well as the pH of the system. © 2013 Elsevier B.V. All rights reserved.
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Nano-patterned sapphire substrates (NPSSs) were fabricated by a chemical wet etching technology using nano-sized SiO2 as masks. The NPSS was applied to improve the performance of GaN-based light emitting diodes (LEDs). GaN-based LEDs on NPSSs were grown by metal organic chemical vapour deposition. The characteristics of LEDs grown on NPSSs and conventional planar sapphire substrates were studied. The light output powers of the LEDs fabricated on NPSSs were considerably enhanced compared with that of the conventional LEDs grown on planar sapphire substrates.
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Narrow stripe selective MOVPE has been used to grow high quality oxide-free InGaAlAs layers on an InP substrate patterned with SiO2 masks at optimized growth conditions. Mirror-like surface morphologies and abrupt cross sections are obtained in all samples without spike growth at the mask edge. For the narrow stripe selectively grown InGaAlAs layers with a mesa width of about 1.2 mu m, a bandgap wavelength shift of 70 nm, a photoluminescence (PL) intensity of more than 80% and a PL full width at half maximum (FWHM) of less than 60 meV are obtained simultaneously with a small mask width variation from 0 to 40 mu m. The characteristics of the thickness enhancement ratio and the PL spectrum dependence on the mask width are presented and explained by considering both the migration effect from a masked region and the lateral vapour diffusion effect.
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Directional emission triangle and square InGaAsP/InP lasers have been fabricated by standard photolithography, inductively coupled plasma etching technique combined with wet chemical etching process. In this article, the characteristics of the microcavity lasers are presented. For an equilateral triangle microcavity laser with the side length of 30 mu m, we got the laser spectra fitted very well with the mode wavelength formulate LIP to the 8(th) transverse mode at room temperature. But the laser spectra are usually more complex than the formulae for the lasers, especially for the lasers with a smaller side length. For a square microcavity laser with side length of 20 mu m, we observed the mode competition between the Fabry-Perot (FP) modes and Whispering-Gallery (WG) modes at 200K. The output spectra below the threshold have the mode interval of FP modes with a large mode interval, and the laser spectra agree very well with the WG modes, which have mode interval less than the FP modes. The output spectra are dominated by the FP modes below the threshold, because the FP modes have a higher output coupling efficiency than the WG modes.
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Helicon plasma source is known as efficient generator of uniform and high density plasma. A helicon plasma source was developed for investigation of plasma neutralization and plasma lens in the Institute of Modern Physics in China. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high argon plasma density up to 3.9x10(13) cm(-3) have been achieved with the Nagoya type III antenna at the conditions of the magnetic intensity of 200 G, working gas pressure of 2.8x10(-3) Pa, and rf power of 1200 W with a frequency of 27.12 MHz. In the experiment, the important phenomena have been found: for a given magnetic induction intensity, the plasma density became greater with the increase in rf power and tended to saturation, and the helicon mode appeared at the rf power between 200 and 400 W.
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A flow injection system for the determination of organophosphate and carbamate pesticides is described. A sensitive fluorescence probe was synthesized and used as the pH indicator to detect the inhibition of the enzyme acetylcholinesterase (ACNE). The percentage inhibition of enzyme activity is correlated to the pesticide concentration. Several parameters influencing the performance of the system are discussed. The detection limits of 3.5, 50, 12 and 25 mug/l for carbofuran, carbaryl, paraoxon and dichlorvos, in pure water, respectively were achieved with an incubation time of 10 min. A complete cycle of analysis, including incubation time, took 14 min. The detection system has been applied to the determination of carbofuran in spiked vegetable juices (Chinese cabbage and cole), achieving recovery values between 93.2 and 107% for Chinese cabbage juice and 108 and 118% for cole juice at the different concentration levels assayed. (C) 2004 Elsevier B.V. All rights reserved.