998 resultados para DISTANCE DETERMINATION


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Spatial resolution is a key parameter of all remote sensing satellites and platforms. The nominal spatial resolution of satellites is a well-known characteristic because it is directly related to the area in ground that represents a pixel in the detector. Nevertheless, in practice, the actual resolution of a specific image obtained from a satellite is difficult to know precisely because it depends on many other factors such as atmospheric conditions. However, if one has two or more images of the same region, it is possible to compare their relative resolutions. In this paper, a wavelet-decomposition-based method for the determination of the relative resolution between two remotely sensed images of the same area is proposed. The method can be applied to panchromatic, multispectral, and mixed (one panchromatic and one multispectral) images. As an example, the method was applied to compute the relative resolution between SPOT-3, Landsat-5, and Landsat-7 panchromatic and multispectral images taken under similar as well as under very different conditions. On the other hand, if the true absolute resolution of one of the images of the pair is known, the resolution of the other can be computed. Thus, in the last part of this paper, a spatial calibrator that is designed and constructed to help compute the absolute resolution of a single remotely sensed image is described, and an example of its use is presented.

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Introduction: Urinary steroid profiling is used in doping controls to detect testosterone abuse. A testosterone over epitestosterone (T/E) ratio exceeding 4.0 is considered as suspicious of testosterone administration, irrespectively of individual heterogeneous factors such as the athlete's ethnicity. A deletion polymorphism in the UGT2B17 gene was demonstrated to account for a significant part of the inter-individual variability in the T/E between Caucasians and Asians. However, the anti-doping strategy includes the determination of carbon isotope ratio on androgen metabolites which has been demonstrated to be reliable for the direct detection of testosterone misuse. Herein, we examined the profiles and the variability in the 13C/12Cratios of urinary steroids in a widely heterogeneous cohort of professional soccer players residing in different world countries (Argentina, Italy, Japan, South-Africa, Switzerland and Uganda). Aim: The determination of threshold values based on genotype information and diet specific of the ethnicity is expected to enhance significantly the detection of testosterone misuse. Methods: The steroid profile of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics was determined by gas chromatography-mass spectrometry. The carbon isotope ratio of selected androgens in urine specimens were determined by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS). Results: Significant differences have been observed between all ethnic groups. After estimation of the prevalence of the UGT2B17 deletion/deletion genotype (African:22%; Asian:81%; Caucasian:10%; Hispanic:7%), ethnicspecific thresholds were developed for a specificity of 99% for the T/E (African:5.6; Asian:3.8; Caucasian:5.7; Hispanic:5.8). Italian and Swiss populations recorded an enrichment in 13C of the urinary steroids with respect to the other groups, thereby supporting consumption of a relatively larger proportion of C3 plants in their diet. Noteworthy, detection criteria based on the difference in the carbon isotope ratio of androsterone and pregnanediol for each population were well below the established threshold value for positive cases. Conclusion: These profiling results demonstrate that a unique and nonspecific threshold to evidence testosterone misuse is not fit for purpose. In addition, the carbon isotopic ratio from these different diet groups highlight the importance to adapt the criteria for increasing the sensitivity in the detection of exogenous testosterone. In conclusion, it may be emphasized that combining the use of isotope ratio mass spectrometry including refined interpretation criteria for positivity and the subject-based profiling of steroids will most probably improve the efficiency of the confirmatory test.

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Growth of four variables of the femur (diapyseal length, diaphyseal length plus distal epiphysis, maximum length and vertical diameter of the head) was analyzed by polynomial regression for the purpose of evaluating its significance and capacity for age and sex determination throughout the entire life continuum. Materials included in analysis consisted of 346 specimens ranging from birth to 97 years of age from five documented osteological collections of Western European descent. Linear growth was displayed by each of the four variables. Significant sexual dimorphism was identified in two of the femoral measurements, including maximum length and vertical diameter of the head, from age 15 onward. These results indicate that the two variables may be of use in the determination of sex in sex determination from that age onward. Strong correlation coefficients were identified between femoral size and age for each of the four metric variables. These results indicate that any of the femoral measurements is likely to serve as a useful source to estimate sub-adult age in both archaeological and forensic samples.

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Sulfur in the soil occurs in two basic forms, organic and inorganic S. The organic form accounts for 95 % of S in most soils. The effectiveness of organic S to oxidate to sulfate was evaluated for total S determination in soil samples by wet (acid) and dry-ash (alkaline) oxidation methods. To evaluate the wet method and the possible use as a reference when evaluating the dry method proposed here, a reference standard from the US National Institute of Standards and Technology (NIST) was used (Montana Soil - NIST 2710). The dry-ash oxidation process with alkaline oxidizing agents is one of the simplest oxidation methods of organic S to the sulfate form and was compared with the wet process. The objective of the study was to develop a dry method that would be easy to apply and allow the complete conversion of organic S to sulfate in soil samples and later detection by turbidimetry. The effectiveness of organic S oxidation to sulfate was evaluated by means of three alkaline oxidation mixtures: NaHCO3 + Ag2O, Eschka mixture (17 % Na2CO3, 66 % MgO, and 17 % K2CO3), and NaHCO3 + CuO. The procedure to quantify the sulfate concentration was based on the reaction with barium chloride and turbidimetric detection. Sulfur quantification in the standard sample by the wet method proved adequate, precise and accurate. It should also be pointed out that no significant differences were found (95 % reliability) between the wet and dry processes (NaHCO3 and Ag2O oxidation mixture) in six different Brazilian soils. The proposed dry method can therefore be used in the preparation of soil samples for total S determination.

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We have devised a program that allows computation of the power of F-test, and hence determination of appropriate sample and subsample sizes, in the context of the one-way hierarchical analysis of variance with fixed effects. The power at a fixed alternative is an increasing function of the sample size and of the subsample size. The program makes it easy to obtain the power of F-test for a range of values of sample and subsample sizes, and therefore the appropriate sizes based on a desired power. The program can be used for the 'ordinary' case of the one-way analysis of variance, as well as for hierarchical analysis of variance with two stages of sampling. Examples are given of the practical use of the program.

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In their invasive ranges, Argentine ant populations often form one geographically vast supercolony, genetically and chemically uniform within which there is no intraspecific aggression. Here we present regional patterns of intraspecific aggression, cuticular hydrocarbons (CHCs) and population genetics of 18 nesting sites across Corsica and the French mainland. Aggression tests confirm the presence of a third European supercolony, the Corsican supercolony, which exhibits moderate to high levels of aggression, depending on nesting sites, with the Main supercolony, and invariably high levels of aggression with the Catalonian supercolony. The chemical analyses corroborated the behavioural data, with workers of the Corsican supercolony showing moderate differences in CHCs compared to workers of the European Main supercolony and strong differences compared to workers of the Catalonian supercolony. Interestingly, there were also clear genetic differences between workers of the Catalonian supercolony and the two other supercolonies at both nuclear and mitochondrial markers, but only very weak genetic differentiation between nesting sites of the Corsican and Main supercolonies (F(ST) = 0.06). A detailed comparison of the genetic composition of supercolonies also revealed that, if one of the last two supercolonies derived from the other, it is the Main supercolony that derived from the Corsican supercolony rather than the reverse. Overall, these findings highlight the importance of conducting more qualitative and quantitative analyses of the level of aggression between supercolonies, which has to be correlated with genetic and chemical data.

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Variables measured during static and dynamic pupillometry were factor-analyzed. Following factors were obtained regardless whether investigations were carried out in normals or in psychiatric patients: A static factor, a dynamic factor, a stimulus-specific factor and a restitution-dependent factor. Evaluation of reliability in normals demonstrated a high reliability for the static variables of pupillometry.

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Genetic caste determination has been described in two populations of Pogonomyrmex harvester ants, each comprising a pair of interbreeding lineages. Queens mate with males of their own and of the alternate lineage and produce two types of diploid offspring, those fertilized by males of the queens' lineage which develop into queens and those fertilized by males of the other lineage which develop into workers. Each of the lineages has been shown to be itself of hybrid origin between the species Pogonomyrmex barbatus and Pogonomyrmex rugosus, which both have typical, environmentally determined caste differentiation. In a large scale genetic survey across 35 sites in Arizona, New Mexico and Texas, we found that genetic caste determination associated with pairs of interbreeding lineages occurred frequently (in 26 out of the 35 sites). Overall, we identified eight lineages with genetic caste determination that always co-occurred in the same complementary lineage pairs. Three of the four lineage pairs appear to have a common origin while their relationship with the fourth remains unclear. The level of genetic differentiation among these eight lineages was significantly higher than the differentiation between P. rugosus and P. barbatus, which questions the appropriate taxonomic status of these genetic lineages. In addition to being genetically isolated from one another, all lineages with genetic caste determination were genetically distinct from P. rugosus and P. barbatus, even when colonies of interbreeding lineages co-occurred with colonies of either putative parent at the same site. Such nearly complete reproductive isolation between the lineages and the species with environmental caste determination might prevent the genetic caste determination system to be swept away by gene flow.

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A method to determine the thermal cross section of a deep level from capacitance measurements is reported. The results enable us to explain the nonexponential behavior of the capacitance versus capture time when the trap concentration is not negligible with respect to that of the shallow one, and the Debye tail effects are taken into account. A figure of merit for the nonexponential behavior of the capture process is shown and discussed for different situations of doping and applied bias. We have also considered the influence of the position of the trap level"s energy on the nonexponentiality of the capture transient. The experimental results are given for the gold acceptor level in silicon and for the DX center in Al0.55 Ga0.45As, which are in good agreement with the developed theory.

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A series of InxAl12xAs samples (0.51,x,0.55) coherently grown on InP was studied in order to measure the band-gap energy of the lattice matched composition. As the substrate is opaque to the relevant photon energies, a method is developed to calculate the optical absorption coefficient from the photoluminescence excitation spectra. The effect of strain on the band-gap energy has been taken into account. For x50.532, at 14 K we have obtained Eg05154966 meV. © 1997 American Institute of Physics.

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La regressió basada en distàncies és un mètode de predicció que consisteix en dos passos: a partir de les distàncies entre observacions obtenim les variables latents, les quals passen a ser els regressors en un model lineal de mínims quadrats ordinaris. Les distàncies les calculem a partir dels predictors originals fent us d'una funció de dissimilaritats adequada. Donat que, en general, els regressors estan relacionats de manera no lineal amb la resposta, la seva selecció amb el test F usual no és possible. En aquest treball proposem una solució a aquest problema de selecció de predictors definint tests estadístics generalitzats i adaptant un mètode de bootstrap no paramètric per a l'estimació dels p-valors. Incluim un exemple numèric amb dades de l'assegurança d'automòbils.

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A workshop on 'The evolution of sex determination systems' was held at a remote place in the Swiss Alps from 17 to 20 June 2009. It brought together theoreticians and empiricists, the latter ranging from molecular geneticists to evolutionary ecologists, all trying to understand key aspects of sex determination. The topics discussed included the evolutionary origins of sex determination, the diversity of sex determination mechanisms in different taxa, and the transition from genotypic to environmental sex determination and vice versa.

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We conducted a preliminary, questionnaire-based, retrospective analysis of training and injury in British National Squad Olympic distance (OD) and Ironman distance (IR) triathletes. The main outcome measures were training duration and training frequency and injury frequency and severity. The number of overuse injuries sustained over a 5-year period did not differ between OD and IR. However, the proportions of OD and IR athletes who were affected by injury to particular anatomical sites differed (p < 0.05). Also, fewer OD athletes (16.7 vs. 36.8%, p < 0.05) reported that their injury recurred. Although OD sustained fewer running injuries than IR (1.6 +/- 0.5 vs. 1.9 +/- 0.3, p < 0.05), more subsequently stopped running (41.7 vs. 15.8%) and for longer (33.5 +/- 43.0 vs. 16.7 +/- 16.6 days, p < 0.01). In OD, the number of overuse injuries sustained inversely correlated with percentage training time, and number of sessions, doing bike hill repetitions (r = -0.44 and -0.39, respectively, both p < 0.05). The IR overuse injury number correlated with the amount of intensive sessions done (r = 0.67, p < 0.01 and r = 0.56, p < 0.05 for duration of "speed run" and "speed bike" sessions). Coaches should note that training differences between triathletes who specialize in OD or IR competition may lead to their exhibiting differential risk for injury to specific anatomical sites. It is also important to note that cycle and run training may have a "cumulative stress" influence on injury risk. Therefore, the tendency of some triathletes to modify rather than stop training when injured-usually by increasing load in another discipline from that in which the injury first occurred-may increase both their risk of injury recurrence and time to full rehabilitation.