Predictions with Lattice QCD

In recent years, we used lattice QCD to calculate some quantities that were unknown or poorly known. They are the $q^2$ dependence of the form factor in semileptonic $D\to Kl\nu$ decay, the leptonic decay constants of the $D^+$ and $D_s$ mesons, and the mass of the $B_c$ meson. In this paper, we summarize these calculations, with emphasis on their (subsequent) confirmation by measurements in $e^+e^-$, $\gamma p$ and $\bar{p}p$ collisions.Comment: 5 pages; update of hep-lat/0509169, with experimental confirmation of form factors from Belle and fDs from BaBar; presented at SciDAC 2006 for the Fermilab Lattice, MILC, and HPQCD Collaboration

Cool Companions to White Dwarf Stars from the Two Micron All Sky Survey All Sky Data Release

We present the culmination of our near-infrared survey of the optically spectroscopically identified white dwarf stars from the McCook and Sion catalog, conducted using photometric data from the Two Micron All Sky Survey final All Sky Data Release. The color selection technique, which identifies candidate binaries containing a white dwarf and a low-mass stellar (or substellar) companion via their distinctive locus in the near-infrared color-color diagram, is demonstrated to be simple to apply and to yield candidates with a high rate of subsequent confirmation. We recover 105 confirmed binaries, and identify 27 firm candidates (19 of which are new to this work) and 21 tentative candidates (17 of which are new to this work) from the 2MASS data. Only a small number of candidates from our survey have likely companion spectral types later than M5, none of which is an obvious L-type (i.e., potential brown dwarf) companion. Only one previously known white dwarf + brown dwarf binary is detected. This result is discussed in the context of the 2MASS detection limits, as well as other recent observational surveys that suggest a very low rate of formation (or survival) for binary stars with extreme mass ratios

Beyond backscattering: Optical neuroimaging by BRAD

Optical coherence tomography (OCT) is a powerful technology for rapid volumetric imaging in biomedicine. The bright field imaging approach of conventional OCT systems is based on the detection of directly backscattered light, thereby waiving the wealth of information contained in the angular scattering distribution. Here we demonstrate that the unique features of few-mode fibers (FMF) enable simultaneous bright and dark field (BRAD) imaging for OCT. As backscattered light is picked up by the different modes of a FMF depending upon the angular scattering pattern, we obtain access to the directional scattering signatures of different tissues by decoupling illumination and detection paths. We exploit the distinct modal propagation properties of the FMF in concert with the long coherence lengths provided by modern wavelength-swept lasers to achieve multiplexing of the different modal responses into a combined OCT tomogram. We demonstrate BRAD sensing for distinguishing differently sized microparticles and showcase the performance of BRAD-OCT imaging with enhanced contrast for ex vivo tumorous tissue in glioblastoma and neuritic plaques in Alzheimer's disease

Mediterranean diet, diet quality, and bone mineral content in adolescents: the HELENA study

Summary: Dietary scores, rather than individual nutrients, allow exploring associations between overall diet and bone health. The aim of the present study was to assess the associations between the Mediterranean Diet Score for Adolescents (MDS-A) and the Diet Quality Index for Adolescents (DQI-A) and bone mineral content (BMC) among Spanish adolescents. Our results do not support an association between dietary scores or indices and BMC in adolescents. Introduction: To assess the associations between the MDS-A and a DQI-A with the BMC measured with dual-energy X-ray absorptiometry. Methods: The MDS-A and the DQI-A were calculated in 179 Spanish adolescents, based on two 24-h dietary recalls from the HELENA cross-sectional study. The associations between the diet scores and the BMC outcomes [total body less head (TBLH), femoral neck (FN), lumbar spine (LS), and hip] were analyzed using logistic regression models adjusting for several confounders. Results: Four hundred ninety-two models were included and only fruits and nuts and cereal and roots were found to provide significant ORs with regard to BMC. The risk of having low BMC reduced by 32% (OR 0.684; CI 0.473–0.988) for FN when following the ideal MDS-A, but this association lost significance when adjusting for lean mass and physical activity. For every 1-point increase in the cereal and root and the fruit and nut components, the risk of having low FN diminished by 56% (OR 0.442; CI 0.216–0.901) and by 67% (OR 0.332; CI 0.146–0.755), respectively. Conclusion: An overall dietary score or index is not associated with BMC in our adolescent Spanish sample

Fragmentation of daily rhythms associates with obesity and cardiorespiratory fitness in adolescents: The HELENA study

Background & aims: Chronobiology studies periodic changes in living organisms and it has been proposed as a promising approach to investigate obesity. We analyze the association of the characteristics of the rest-activity rhythms with obesity, cardiorespiratory fitness and metabolic risk in adolescents from nine European countries. Methods: 1044 adolescents (12.5-17.5 y) were studied. Circadian health was evaluated by actigraphy with accelerometers (Actigraph GT1M). Characteristics of the daytime activity such as fragmentation (intradaily variability), estimated acrophase, and 10 h mean daytime activity index were obtained. Body composition was assessed using Bioelectrical-Impedance-Analysis, skinfold thickness, air-displacement-plethysmography and Dual-energy-X-ray-Absorptiometry. Cardiorespiratory fitness (VO2max) and metabolic risk were studied. Results: Highly fragmented activity rhythms were associated with obesity and central adiposity (P < 0.05). Obese adolescents had-3 times higher odds of having a high fragmentation of daytime activity compared to normal weight adolescents OR (95% CI) = 2.8 (1.170, 6.443). A highly fragmented rhythm was also related to lower cardiorespiratory fitness and higher metabolic risk (P < 0.05) so those adolescents classified as low fitness showed a significantly higher fragmentation of daytime activity than those included in the high fitness group (P < 0.0001). Other characteristics of the rhythms such as smaller 10 h daytime mean activity index and delayed estimated acrophase were also related to obesity and metabolic risk (P < 0.05). Conclusions: Our results indicate that the daily organization of the rest-activity cycle is more fragmented in obese and less fit adolescents and correlates with higher metabolic risk. This fact reinforces our hypothesis that disturbances in daily rhythms can be considered as sensitive markers of poorer adolescent's health

Association of body composition indices with insulin resistance in European adolescents: The HELENA study

Background: The different body components may contribute to the development of insulin resistance and type 2 diabetes mellitus. The aim of the present study was to examine the association of fat mass and fat free mass indices with markers of insulin resistance, independently of each other and giving, at the same time, gender-specific information in a wide cohort of European adolescents. Methods: A cross-sectional study in a school setting was conducted in 925 (430 males) adolescents (14.9 ± 1.2 years). Weight, height, anthropometric, bioimpedance and blood parameters were measured. Indices for fat mass and fat free mass, and homeostatic model assessment (HOMA) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat free mass and fat mass when possible. Results: Indices of fat mass were positively associated with HOMA (all p < 0.01) after adjusting for all the confounders including fat free mass indices, in both sexes. Fat free mass indices were associated with HOMA, in both males and females, after adjusting for center, pubertal status, socioeconomic status and cardiorespiratory fitness, but the associations disappear when including fat mass indices in the adjustment’s model. Conclusion: Fat mass indices derived from different methods are positively associated with insulin resistance independently of several confounders including fat free mass indices. In addition, the relationship of fat free mass with insulin resistance is influenced by the amount of fat mass in European adolescents. Nevertheless, future studies should focus not only on the role of fat mass, but also on other body components such as fat free mass because its role could vary depending of the level and distribution of fat mass

Association of heart rate and blood pressure among European adolescents with usual food consumption: the HELENA study

Background and aim: In adults, there is some evidence that improving diet reduces blood pressure (BP) and the subsequent risk of cardiovascular diseases (CVDs). However, studies that analyse this association in adolescents are still scarce. The objective of the present study was to examine the associations between heart rate, systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP) among European adolescents and usual intake of vegetables, fruits, dairy products, meat, fish, high-sugar foods and savoury snacks. Methods and results: In total, 2283 adolescents from the HELENA-study (12.5-17.5 years old; 1253 girls) were included. Dietary intake was assessed using two computerized 24-hour dietary recalls. Age, sex, body mass index, maternal educational level, physical activity and Tanner stage were considered as confounders. Associations were examined by mixed model analysis stratified by sex. Tests for trend were assessed by tertiles of intake while controlling for the aforementioned confounders. Dairy products and fish intake were negatively associated with BP and heart rate. Significant decreasing trends were observed for heart rate and BP across tertiles of dairy products, fish intake and high-sugar foods intake (p < 0.05). Significant increasing trends were observed for SBP and MAP across tertiles of savoury snack intake (p < 0.05). Conclusion: Significant but small inverse associations between fish and dairy products consumption with blood pressure and heart rate have been found in European adolescents. Dietary intervention studies are needed to explore these associations in the context of the modification of several risk factors for the prevention of cardiovascular diseases