993 resultados para optical behaviour


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Consider the density of the solution $X(t,x)$ of a stochastic heat equation with small noise at a fixed $t\in [0,T]$, $x \in [0,1]$.In the paper we study the asymptotics of this density as the noise is vanishing. A kind of Taylor expansion in powers of the noiseparameter is obtained. The coefficients and the residue of the expansion are explicitly calculated.In order to obtain this result some type of exponential estimates of tail probabilities of the difference between the approximatingprocess and the limit one is proved. Also a suitable local integration by parts formula is developped.

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Purpose: To determine whether the need for retreatment after an initial phase of 3 monthly intravitreal injections of ranibizumab shows an intra-individual regular rhythm and to what degree it varies between different patients. Methods: Prospective study with 42 patients with exudative AMD, treatment naïve. Loading dose of 3 monthly doses of ranibizumab (0,5 mg), followed by a 12 months pro re nata (PRN) regimen according to early exudative signs on HD-OCT Cirrus, Zeiss. The follow-up visits were intensified (week 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, etc after each injection) in order to detect recurrences early, and injection followed within 3 days in cases of subretinal fluid, cysts, or central thickness increase of>50microns. Intervals were calculated between injections for the 12 month follow-up with PRN treatment. Variability was expressed as standard deviation (SD). Results: Visual acuity (VA) improved from a mean ETDRS score of 61.6 (SD 10.8) at baseline to 68.0 (SD 10.2) at month 3 and to 74.7(SD 9.0) at month 12. The 15 patients who have already completed the study showed maintenance of the VA improvement. Central foveal thickness improved from a mean value of 366 microns (baseline) to 253 microns (month 3), well maintained thereafter. Mean number of injections was 8.8 (SD 3.5,range 0-12) per 12 months of follow-up (after 3 doses), with mean individual treatment-recurrence (TR) intervals ranging from 28->365 days (mean 58). Intraindividual variability of TR intervals (SD) was 7.1 days as a mean value (range 1.7¡V22.6). It ranged within 20% of the mean intra-individual interval for 30 (91%) and within 15% for 21 patients (64%). The first interval was within 1 week of the mean intra-individual interval in 64% and within 2 weeks in 89% of patients. Conclusions: The majority of AMD patients showed a relatively stable rhythm for PRN injections of ranibizumab after initial loading phase, associated with excellent functional/anatomical results. The initial interval last loading dose-first recurrence may have a predictive value for further need of treatment, potentially facilitating follow-up and patient care.

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Isolates of the Trichophyton mentagrophytes complex vary phenotypically. Whether the closely related zoophilic and anthropophilic anamorphs currently associated with Arthroderma vanbreuseghemii have to be considered as members of the same biological species remains an open question. In order to better delineate species in the T. mentagrophytes complex, we performed a mating analysis of freshly collected isolates from humans and animals with A. benhamiae and A. vanbreuseghemii reference strains, in comparison to internal transcribed spacer (ITS) and 28S rDNA sequencing. Mating experiments as well as ITS and 28S sequencing unambiguously allowed the distinction of A. benhamiae and A. vanbreuseghemii. We have also shown that all the isolates from tinea pedis and tinea unguium identified as T. interdigitale based on ITS sequences mated with A. vanbreuseghemii tester strains, but had lost their ability to give fertile cleistothecia. Therefore, T. interdigitale has to be considered as a humanized species derived from the sexual relative A. vanbreuseghemii.

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BACKGROUND: Little is known about smoking, unhealthy use of alcohol, and risk behaviours for sexually transmitted diseases (STDs) in immigrants from developed and developing countries. METHOD: We performed a cross-sectional study of 400 patients who consulted an academic emergency care centre at a Swiss university hospital. The odds ratios for having one or more risk behaviours were adjusted for age, gender, and education level. RESULTS: Immigrants from developing countries were less likely to use alcohol in an unhealthy manner (OR = 0.35, 95% CI 0.22-0.57) or practise risk behaviours for STDs (OR = 0.31, 95% CI 0.13-0.74). They were also less likely to have any of the three studied risk behaviours (OR = 2.5, 95% CI 1.5-4.3). DISCUSSION: In addition to the usual determinants, health behaviours are also associated with origin; distinguishing between immigrants from developing and developed countries is useful in clinical settings. Surprisingly, patients from developing countries tend to possess several protective characteristics.

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Analiza las reservas de vitelino y su funcion en el aumento proporcional en la longitud del tamaño del cuerpo.

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BACKGROUND: To determine male outpatient attenders' sexual behaviours, expectations and experience of talking about their sexuality and sexual health needs with a doctor. METHODS: A survey was conducted among all male patients aged 18-70, recruited from the two main medical outpatient clinics in Lausanne, Switzerland, in 2005-2006. The anonymous self-administered questionnaire included questions on sexual behaviour, HIV/STI information needs, expectations and experiences regarding discussion of sexual matters with a doctor. RESULTS: The response rate was 53.0% (N = 1452). The mean age was 37.7 years. Overall, 13.4% of patients were defined as at STI risk--i.e. having not consistently used condoms with casual partners in the last 6 months, or with a paid partner during the last intercourse--regarding their sexual behaviour in the last year. 90.9% would have liked their physician to ask them questions concerning their sexual life; only 61.4% had ever had such a discussion. The multivariate analysis showed that patients at risk tended to have the following characteristics: recruited from the HIV testing clinic, lived alone, declared no religion, had a low level of education, felt uninformed about HIV/AIDS, were younger, had had concurrent sexual partners in the last 12 months. However they were not more likely to have discussed sexual matters with their doctor than patients not at risk. CONCLUSION: Recording the sexual history and advice on the prevention of the risks of STI should become routine practice for primary health care doctors.

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Male bees of the tribe Euglossini collect volatile chemicals secreted by orchids using dense patches of hair on the front tarsi. After collecting chemicals, the bee hovers while transferring these fragrances to invaginations on the hind tibiae. The fragrance collection and hovering behaviours are repeated multiple times. Here I report preliminary field observations on the length of fragrance collection and hovering phases in bees of the Eulaema meriana (Oliver, 1789) mimicry complex visiting the orchid Catasetum discolor in Kavanayén,Venezuela. I observed that in extended visits with many cycles of fragrance collection and hovering, the length of each collection phase gradually increased, while the length of hovering phase was static. This suggests either that chemicals secreted by orchids are in limited supply or that efficiency of fragrance collection drops.

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The siderophore pyochelin is made by a thiotemplate mechanism from salicylate and two molecules of cysteine. In Pseudomonas aeruginosa, the first cysteine residue is converted to its D-isoform during thiazoline ring formation whereas the second cysteine remains in its L-configuration, thus determining the stereochemistry of the two interconvertible pyochelin diastereoisomers as 4'R, 2''R, 4''R (pyochelin I) and 4'R, 2''S, 4''R (pyochelin II). Pseudomonas fluorescens CHA0 was found to make a different stereoisomeric mixture, which promoted growth under iron limitation in strain CHA0 and induced the expression of its biosynthetic genes, but was not recognized as a siderophore and signaling molecule by P. aeruginosa. Reciprocally, pyochelin promoted growth and induced pyochelin gene expression in P. aeruginosa, but was not functional in P. fluorescens. The structure of the CHA0 siderophore was determined by mass spectrometry, thin-layer chromatography, NMR, polarimetry, and chiral HPLC as enantio-pyochelin, the optical antipode of the P. aeruginosa siderophore pyochelin. Enantio-pyochelin was chemically synthesized and confirmed to be active in CHA0. Its potential biosynthetic pathway in CHA0 is discussed.

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Jurassic volcanic formations interlayered with (ammonite-bearing) sediments are common in the Caucasus area; this situation is of interest for the numerical calibration of the poorly documented Jurassic portion of the time scale. However, following petrographic study on thin sections no whole-rocks can be considered reliable geochronometers due to subsequent alteration; from about 20 samples, two were selected for plagioclase dating; one (V134) is probably early Kimmeridgian in age; the other (V136) is probably located in the Lower Bathonian stage according to diagnostic ammonites. Cathodoluminescence (CTL) study has shown that sample V136 was similar to usual volcanic feldspars (blue to green colour); however, the lack of CTL of the V134 plagioclase is a character common to diagenetic feldspars; consequently, in spite of a good optical preservation, this geo-chronometer cannot give an age representative of the time of emplacement of the lava flow. We have combined CTL observation with microprobe analysis in order to document the poorly known CTL behaviour of volcanic feldspars; cations Ti4+ and Fe2+ play a major role in the CTL colour of plagioclases and are able to document the growing history of these feldspars ; phenocrysts are initially rich in Fe2+ (core of the crystals, green in colour), then richer in Ti toward the exterior; microcrysts are even richer in Ti (blue to bright blue). We have also observed that natural CTL colour was modified resulting from acid ``cleaning'' of the separated feldspars : the initial blue or green colour tends to change to yellow or violet, respectively, after acid treatment probably due to oxydation of Fe2+ toward Fe3+. X-ray and microprobe analyses both indicated that plagioclases from sample V134 was near the sodic end member (albite) suggesting a diagenetic origin in this andesitic basalt; In contrast, sample V136 contains a calcic plagioclase of common composition for a doleritic basalt. The K-Ar conventional technique was applied as a preliminary tool for radiometric analysis. The Kimmeridgian Na-plagioclase sample gave a ``rejuvenated'' (85 Ma) apparent age which confirms a late genesis for the separated plagioclase phase; this interpretation is based on CTL observation, X-ray analysis, and microprobe analysis ; these techniques are able to distinguish samples which have been submitted to diagenetic alteration from those which have not. An age consistent with the stratigraphic location has been obtained from sample V136. This age of 161 +/- 3 (2-sigma) Ma, is the first one available from a sample palaeontologically located with reasonable precision within the mid Jurassic time.