952 resultados para p-type GaN


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OBJECTIVE: To assess the applicability of photodynamic therapy (PDT) in the management of vulvodynia whereby a novel, patch-type system, loaded with 5-aminolevulinic acid (ALA), was used to administer PDT to vulvar regions displaying the characteristics of vulvodynia.

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Aims/hypothesis: We investigated whether children who are heavier at birth have an increased risk of type 1 diabetes. Methods: Relevant studies published before February 2009 were identified from literature searches using MEDLINE, Web of Science and EMBASE. Authors of all studies containing relevant data were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of birthweight were calculated for each study, before and after adjustment for potential confounders. Meta-analysis techniques were then used to derive combined ORs and investigate heterogeneity between studies. Results: Data were available for 29 predominantly European studies (five cohort, 24 case-control studies), including 12,807 cases of type 1 diabetes. Overall, studies consistently demonstrated that children with birthweight from 3.5 to 4 kg had an increased risk of diabetes of 6% (OR 1.06 [95% CI 1.01-1.11]; p=0.02) and children with birthweight over 4 kg had an increased risk of 10% (OR 1.10 [95% CI 1.04-1.19]; p=0.003), compared with children weighing 3.0 to 3.5 kg at birth. This corresponded to a linear increase in diabetes risk of 3% per 500 g increase in birthweight (OR 1.03 [95% CI 1.00-1.06]; p=0.03). Adjustments for potential confounders such as gestational age, maternal age, birth order, Caesarean section, breastfeeding and maternal diabetes had little effect on these findings. Conclusions/interpretation: Children who are heavier at birth have a significant and consistent, but relatively small increase in risk of type 1 diabetes. © 2010 Springer-Verlag.


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Aims Diabetic nephropathy is a leading cause of end-stage renal disease. The transforming growth factor beta-bone morphogenic protein (BMP) pathway is implicated in the pathogenesis of diabetic nephropathy. The BMP2, BMP4 and BMP7 genes are located near linkage peaks for renal dysfunction, and we hypothesize that genetic polymorphisms in these biological and positional candidate genes may be risk factors for diabetic kidney disease.

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In this study, 1124 week-old pigs were allocated at weaning in groups of 20 to one of five feeder types. These consisted of two multi-space designs ('dry' and 'wet and dry'), two feeders with communal troughs ('communal-rectangular' and 'communal-circular') and a single-space feeder. All feeders supplied water except the 'dry' multi-space feeder, Feed disappearance was higher and food conversion was poorer with 'wet and dry' multi-space feeders than with all other feeder types (P

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Background Renal cell carcinoma patients respond poorly to conventional chemotherapy, this unresponsiveness may be attributable to multidrug resistance (MDR). The mechanisms of MDR in renal cancer are not fully understood and the specific contribution of ABC transporter proteins which have been implicated in the chemoresistance of various cancers has not been fully defined in this disease. Methods In this retrospective study the expression of two of these transporter efflux pumps, namely MDR-1 P-gp (ABCB1) and MRP-1 (ABCC1) were studied by immunohistochemistry in archival material from 95 renal cell carcinoma patients. Results In the first study investigating MDR-1 P-gp and MRP-1 protein expression patterns in renal cell carcinoma patients, high levels of expression of both efflux pumps are observed with 100% of tumours studied showing MDR-1 P-gp and MRP-1 positivity. Conclusion Although these findings do not prove a causal role, the high frequency of tumours expressing these efflux pumps suggests that they may be important contributors to the chemoresistance of this tumour type.

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High-resolution optical spectra of 57 Galactic B-type supergiant stars have been analysed to determine their rotational and macroturbulent velocities. In addition, their atmospheric parameters (effective temperature, surface gravity and microturbulent velocity) and surface nitrogen abundances have been estimated using a non-local thermodynamic equilibrium grid of model atmospheres. Comparisons of the projected rotational velocities have been made with the predictions of stellar evolutionary models and in general good agreement was found. However, for a small number of targets, their observed rotational velocities were significantly larger than predicted, although their nitrogen abundances were consistent with the rest of the sample. We conclude that binarity may have played a role in generating their large rotational velocities. No correlation was found between nitrogen abundances and the current projected rotational velocities. However, a correlation was found with the inferred projected rotational velocities of the main-sequence precursors of our supergiant sample. This correlation is again in agreement with the predictions of single star evolutionary models that incorporate rotational mixing. The origin of the macroturbulence and microturbulent velocity fields is discussed and our results support previous theoretical studies that link the former to subphotospheric convection and the latter to non-radial gravity mode oscillations. In addition, we have attempted to identify differential rotation in our most rapidly rotating targets.

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Aims/hypothesis: The aim of this study was to investigate the evidence of an increased risk of childhood-onset type 1 diabetes in children born by Caesarean section by systematically reviewing the published literature and performing a meta-analysis with adjustment for recognised confounders.
Methods: After MEDLINE, Web of Science and EMBASE searches, crude ORs and 95% CIs for type 1 diabetes in children born by Caesarean section were calculated from the data reported in each study. Authors were contacted to facilitate adjustments for potential confounders, either by supplying raw data or calculating adjusted estimates. Meta-analysis techniques were then used to derive combined ORs and to investigate heterogeneity between studies.
Results: Twenty studies were identified. Overall, there was a significant increase in the risk of type 1 diabetes in children born by Caesarean section (OR 1.23, 95% CI 1.15-1.32, p<0.001). There was little evidence of heterogeneity between studies (p=0.54). Seventeen authors provided raw data or adjusted estimates to facilitate adjustments for potential confounders. In these studies, there was evidence of an increase in diabetes risk with greater birthweight, shorter gestation and greater maternal age. The increased risk of type 1 diabetes after Caesarean section was little altered after adjustment for gestational age, birth weight, maternal age, birth order, breast-feeding and maternal diabetes (adjusted OR 1.19, 95% CI 1.04-1.36, p=0.01).
Conclusions/interpretation: This analysis demonstrates a 20% increase in the risk of childhood-onset type 1 diabetes after Caesarean section delivery that cannot be explained by known confounders.

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OBJECTOVE - To examine mortality rates and causes of death among subjects diagnosed with type I diabetes aged

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We present mid-infrared (MIR) observations of the Type II-plateau supernova (SN) 2004et, obtained with the Spitzer Space Telescope between 64 and 1406 days past explosion. Late-time optical spectra are also presented. For the period 300-795 days past explosion, we argue that the spectral energy distribution (SED) of SN 2004et comprises (1) a hot component due to emission from optically thick gas, as well as free-bound radiation; (2) a warm component due to newly formed, radioactively heated dust in the ejecta; and (3) a cold component due to an IR echo from the interstellar-medium dust of the host galaxy, NGC 6946. There may also have been a small contribution to the IR SED due to free-free emission from ionized gas in the ejecta. We reveal the first-ever spectroscopic evidence for silicate dust formed in the ejecta of a supernova. This is supported by our detection of a large, but progressively declining, mass of SiO. However, we conclude that the mass of directly detected ejecta dust grew to no more than a few times 10(-4) M-circle dot. We also provide evidence that the ejecta dust formed in comoving clumps of fixed size. We argue that, after about two years past explosion, the appearance of wide, box-shaped optical line profiles was due to the impact of the ejecta on the progenitor circumstellar medium and that the subsequent formation of a cool, dense shell was responsible for a later rise in the MIR flux. This study demonstrates the rich, multifaceted ways in which a typical core-collapse supernova and its progenitor can produce and/or interact with dust grains. The work presented here adds to the growing number of studies that do not support the contention that SNe are responsible for the large mass of observed dust in high-redshift galaxies.

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We present photometric and spectroscopic observations at optical and near-infrared wavelengths of the nearby type Ic supernova 2007gr. These represent the most extensive data-set to date of any supernova of this sub-type, with frequent coverage from shortly after discovery to more than one year post-explosion. We deduce a rise time to B-band maximum of 11.5 +/- 2.7 d. We find a peak B-band magnitude of M-B = -16.8, and light curves which are remarkably similar to the so-called "hypernova" SN 2002ap. In contrast, the spectra of SNe 2007gr and 2002ap show marked differences, not least in their respective expansion velocities. We attribute these differences primarily to the density profiles of their progenitor stars at the time of explosion i.e. a more compact star for SN 2007gr compared to SN 2002ap. From the quasi-bolometric light curve of SN 2007gr, we estimate that 0.076 +/- 0.010 M-circle dot of Ni-56 was produced in the explosion. Our near-infrared (IR) spectra clearly show the onset and disappearance of the first overtone of carbon monoxide (CO) between similar to 70 to 175 d relative to B-band maximum. The detection of the CO molecule implies that ionised He was not microscopically mixed within the carbon/oxygen layers. From the optical spectra, near-IR light curves, and colour evolution, we find no evidence for dust condensation in the ejecta out to about +400 d. Given the combination of unprecedented temporal coverage, and high signal-to-noise data, we suggest that SN 2007gr could be used as a template object for supernovae of this sub-class.

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We present results based on mid-infrared (3.6-30 mm) observations with the Spitzer Space Telescope of the nearby Type IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne that, via spectral synthesis, may be used to constrain nucleosynthesis models.

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We present an extensive set of optical spectroscopy of the nearby type Ia supernova, SN 2002er, with 24 epochs spanning -11 to +34 days. Its spectral evolution is fairly typical of a type Ia supernova although it suffers high extinction. Nevertheless, there are differences in the spectral evolution when compared to coeval spectra of other normal type Ia supernova with comparable decline-rate parameters. Modelling of the photospheric phase spectra using a homogeneous abundance distribution in the atmosphere provides a fair match to the observations, but only by pushing the adopted distance and risetime close to the observational limits. Future improvements here will require models with a more realistic stratified abundance distribution. From simple modelling of a nebular spectrum obtained at +215 d, we infer a Ni-56 mass of 0.69 M-circle dot, consistent with that derived from the light curve.

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Objective/background Our objective was to investigate glycaemic control in children with Type 1 diabetes in Scotland and to analyse the effect of changing 'conventional' insulin regimen strategies on outcome. DIABAUD 2 ( 1997 - 1998) (D2) demonstrated that average glycaemic control in young people with Type 1 diabetes in Scotland was poor, with mean HbA(1c) of 9.0%. Over 90% were then treated with a twice-daily insulin regimen. The aim of DIABAUD 3 ( 2002 2004) (D3) was to determine if control had improved, and to examine changes in insulin regimen and effects on glycaemic control.