161 research outputs found
Masked Discriminators for Content-Consistent Unpaired Image-to-Image Translation
A common goal of unpaired image-to-image translation is to preserve content
consistency between source images and translated images while mimicking the
style of the target domain. Due to biases between the datasets of both domains,
many methods suffer from inconsistencies caused by the translation process.
Most approaches introduced to mitigate these inconsistencies do not constrain
the discriminator, leading to an even more ill-posed training setup. Moreover,
none of these approaches is designed for larger crop sizes. In this work, we
show that masking the inputs of a global discriminator for both domains with a
content-based mask is sufficient to reduce content inconsistencies
significantly. However, this strategy leads to artifacts that can be traced
back to the masking process. To reduce these artifacts, we introduce a local
discriminator that operates on pairs of small crops selected with a similarity
sampling strategy. Furthermore, we apply this sampling strategy to sample
global input crops from the source and target dataset. In addition, we propose
feature-attentive denormalization to selectively incorporate content-based
statistics into the generator stream. In our experiments, we show that our
method achieves state-of-the-art performance in photorealistic sim-to-real
translation and weather translation and also performs well in day-to-night
translation. Additionally, we propose the cKVD metric, which builds on the sKVD
metric and enables the examination of translation quality at the class or
category level.Comment: 24 pages, 22 figures, under revie
Kinetics of Phase Separation in Thin Films: Simulations for the Diffusive Case
We study the diffusion-driven kinetics of phase separation of a symmetric
binary mixture (AB), confined in a thin-film geometry between two parallel
walls. We consider cases where (a) both walls preferentially attract the same
component (A), and (b) one wall attracts A and the other wall attracts B (with
the same strength). We focus on the interplay of phase separation and wetting
at the walls, which is referred to as {\it surface-directed spinodal
decomposition} (SDSD). The formation of SDSD waves at the two surfaces, with
wave-vectors oriented perpendicular to them, often results in a metastable
layered state (also referred to as ``stratified morphology''). This state is
reminiscent of the situation where the thin film is still in the one-phase
region but the surfaces are completely wet, and hence coated with thick wetting
layers. This metastable state decays by spinodal fluctuations and crosses over
to an asymptotic growth regime characterized by the lateral coarsening of
pancake-like domains. These pancakes may or may not be coated by precursors of
wetting layers. We use Langevin simulations to study this crossover and the
growth kinetics in the asymptotic coarsening regime.Comment: 39 pages, 19 figures, submitted to Phys.Rev.
No association between variation in the NR4A1 gene locus and metabolic traits in white subjects at increased risk for type 2 diabetes
<p>Abstract</p> <p>Background</p> <p>The nuclear receptor NR4A1 is implicated in metabolic regulation in insulin-sensitive tissues, such as liver, adipose tissue, and skeletal muscle. Functional loss of NR4A1 results in insulin resistance and enhanced intramuscular and hepatic lipid content. Therefore, we investigated in a cohort of white European subjects at increased risk for type 2 diabetes whether genetic variation within the <it>NR4A1 </it>gene locus contributes to prediabetic phenotypes, such as insulin resistance, ectopic fat distribution, or β-cell dysfunction.</p> <p>Methods</p> <p>We genotyped 1495 subjects (989 women, 506 men) for five single nucleotide polymorphisms (SNPs) tagging 100% of common variants (MAF = 0.05) within the <it>NR4A1 </it>gene locus with an r<sup>2 </sup>= 0.8. All subjects underwent an oral glucose tolerance test (OGTT), a subset additionally had a hyperinsulinemic-euglycemic clamp (n = 506). Ectopic hepatic (n = 296) and intramyocellular (n = 264) lipids were determined by magnetic resonance spectroscopy. Peak aerobic capacity, a surrogate parameter for oxidative capacity of skeletal muscle, was measured by an incremental exercise test on a motorized treadmill (n = 270).</p> <p>Results</p> <p>After appropriate adjustment and Bonferroni correction for multiple comparisons, none of the five SNPs was reliably associated with insulin sensitivity, ectopic fat distribution, peak aerobic capacity, or indices of insulin secretion (all p ≥ 0.05).</p> <p>Conclusions</p> <p>Our data suggest that common genetic variation within the <it>NR4A1 </it>gene locus may not play a major role in the development of prediabetic phenotypes in our white European population.</p
Common Genetic Variation in the SERPINF1 Locus Determines Overall Adiposity, Obesity-Related Insulin Resistance, and Circulating Leptin Levels
OBJECTIVE: Pigment epithelium-derived factor (PEDF) belongs to the serpin family of peptidase inhibitors (serpin F1) and is among the most abundant glycoproteins secreted by adipocytes. In vitro and mouse in vivo data revealed PEDF as a candidate mediator of obesity-induced insulin resistance. Therefore, we assessed whether common genetic variation within the SERPINF1 locus contributes to adipose tissue-related prediabetic phenotypes in humans. SUBJECTS/METHODS: A population of 1,974 White European individuals at increased risk for type 2 diabetes was characterized by an oral glucose tolerance test with glucose and insulin measurements (1,409 leptin measurements) and genotyped for five tagging SNPs covering 100% of common genetic variation (minor allele frequency ≥ 0.05) in the SERPINF1 locus. In addition, a subgroup of 486 subjects underwent a hyperinsulinaemic-euglycaemic clamp and a subgroup of 340 magnetic resonance imaging (MRI) and spectroscopy (MRS). RESULTS: After adjustment for gender and age and Bonferroni correction for the number of SNPs tested, SNP rs12603825 revealed significant association with MRI-derived total adipose tissue mass (p = 0.0094) and fasting leptin concentrations (p = 0.0035) as well as nominal associations with bioelectrical impedance-derived percentage of body fat (p = 0.0182) and clamp-derived insulin sensitivity (p = 0.0251). The association with insulin sensitivity was completely abolished by additional adjustment for body fat (p = 0.8). Moreover, the fat mass-increasing allele of SNP rs12603825 was significantly associated with elevated fasting PEDF concentrations (p = 0.0436), and the PEDF levels were robustly and positively associated with all body fat parameters measured and with fasting leptin concentrations (p<0.0001, all). CONCLUSION: In humans at increased risk for type 2 diabetes, a functional common genetic variant in the gene locus encoding PEDF contributes to overall body adiposity, obesity-related insulin resistance, and circulating leptin levels
Proton magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations
H-1-MR spectroscopy of skeletal muscle provides insight into metabolism that is not available noninvasively by other methods. The recommendations given in this article are intended to guide those who have basic experience in general MRS to the special application of H-1-MRS in skeletal muscle. The highly organized structure of skeletal muscle leads to effects that change spectral features far beyond simple peak heights, depending on the type and orientation of the muscle. Specific recommendations are given for the acquisition of three particular metabolites (intramyocellular lipids, carnosine and acetylcarnitine) and for preconditioning of experiments and instructions to study volunteers.Peer reviewe
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Impact of the Adipokine Adiponectin and the Hepatokine Fetuin-A on the Development of Type 2 Diabetes: Prospective Cohort- and Cross-Sectional Phenotyping Studies
Background: Among adipokines and hepatokines, adiponectin and fetuin-A were consistently found to predict the incidence of type 2 diabetes, both by regulating insulin sensitivity. Objective: To determine to what extent circulating adiponectin and fetuin-A are independently associated with incident type 2 diabetes in humans, and the major mechanisms involved. Methods: Relationships with incident diabetes were tested in two cohort studies: within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study (628 cases) and the Nurses' Health Study (NHS; 470 cases). Relationships with body fat compartments, insulin sensitivity and insulin secretion were studied in the Tübingen Lifestyle Intervention Program (TULIP; N = 358). Results: Circulating adiponectin and fetuin-A, independently of several confounders and of each other, associated with risk of diabetes in EPIC-Potsdam (RR for 1 SD: adiponectin: 0.45 [95% CI 0.37–0.54], fetuin-A: 1.18 [1.05–1.32]) and the NHS (0.51 [0.42–0.62], 1.35 [1.16–1.58]). Obesity measures considerably attenuated the association of adiponectin, but not of fetuin-A. Subjects with low adiponectin and concomitantly high fetuin-A had the highest risk. Whereas both proteins were independently (both p<1.8×10−7) associated with insulin sensitivity, circulating fetuin-A (r = −0.37, p = 0.0004), but not adiponectin, associated with insulin secretion in subjects with impaired glucose tolerance. Conclusions: We provide novel information that adiponectin and fetuin-A independently of each other associate with the diabetes risk. Furthermore, we suggest that they are involved in the development of type 2 diabetes via different mechanisms, possibly by mediating effects of their source tissues, expanded adipose tissue and nonalcoholic fatty liver
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