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Vitamin D deficiency is common in the general population and may impair skeletal muscle function. Very few data are available regarding this condition in professional athletes. To evaluate some skeletal parameters and in particular serum 25-hydroxyvitamin D status in professional rugby players during two different sunlight exposure times (October and early April) and to assess its impact on bone metabolism. Twenty-one male healthy professional rugby players living in northern Italy at latitude of 44°55′N (age 24.6 ± 4.3 years; height 182.0 ± 0.05 cm; mass 96.3 ± 14.6 kg; BMI 28.9 ± 3.7 kg/m2) participated in this observational study. During 2012/2013 Italian rugby season, 25-hydroxyvitamin D, PTH and other related biochemical parameters were monitored. Dietary calcium intake and body composition by DXA were also evaluated. Significant changes were observed between October and April data for 25-hydroxyvitamin D concentration (22.8 ± 5.8 vs. 19.1 ± 5.3 ng/ml; p= 0.001) whereas serum PTH, calcium and phosphorus plasma levels did not change. They presented with an appropriate daily intake of calcium (1,304.8 ± 477.9 mg; max 1,939 mg; min 228 mg). Professional rugby athletes practicing a sport characterized by intense outdoor training and with good calcium intake are at higher risk of hypovitaminosis D that worsens significantly during times of low cutaneous vitamin D production. Further studies are warranted to evaluate whether an appropriate supplementation with cholecalciferol in professional athletes is needed.

ABSTRACTThis study aims to assess whether or not incomplete filling of primary lithium heparin tubes may influence the activity of creatine kinase (CK), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamyltransferase (GGT). Blood was drawn from 20 healthy volunteer using an identical sequence of tubes. First, a 6 mL, 13 × 100 mm 14 unit/mL lithium heparin Vacuette was filled and discharged. Then, three identical lithium heparin Vacuette tubes were filled, one to the nominal volume (i.e., full-draw tube), another with half of the nominal volume (half-draw tube) and the last with one-third of the nominal volume (low-draw tube). The plasma was separated and tested for CK (non-activated by N-acetylcysteine), AST and ALT on a Beckman Coulter Unicel DxC 800. Tests for CK were performed with a different reagent on a Beckman Coulter AU5800 (activated by N-acetylcysteine). Although the concentrations of ASL and ALT measured on the Unicel DxC and that of CK measured on the AU5800 did not change significantly across the different specimens, those of CK and GGT measured on the Unicel DxC 800 were significantly increased in the half-draw and low-draw tubes. The percentage bias of CK on the Unicel DxC 800 (using Bland Altman plots) was 3.3% and 7.9% for the half-draw and low-draw tubes, respectively, whereas that of GGT was 10.3% and 16.6% for the half-draw and low-draw tubes, respectively. These results suggest that short-draw lithium heparin tubes might be unsuitable for testing GGT and CK using specific combinations of reagents and instrumentation.

This paper describes the design and implementation of a second-order switched-capacitor (SC) bandpass (BP) filter with very wide quality factor (Q) programmability range. The filter selectivity is digitally programmed by varying the effective sampling frequency of an SC branch, without modifying any capacitor value. The proposed approach allows a quasi-continuous Q-factor tunability avoiding, in principle, the inherent quantization error associated to any traditional programming technique. Automatic Q-factor tuning is performed by using a scheme based on an amplitude-locking loop approach. Experimental results obtained from a 0.8-μm CMOS integrated prototype demonstrate the versatility of the proposed technique for high-QSC BP filters.

The molecular orientation in Polymer Dispersed Liquid Crystals (PDLC) was monitored by 2H-NMR of a dissolved deuterated probe molecule in the presence of an applied electric field of variable intensity. Data of molecular orientations at different applied fields were extracted from NMR lineshapes by comparison with spectra at zero field. Such data were quantitatively analyzed using an empirical function. By comparison with optical data we concluded that the molecular reorientation due to the electric field is achieved by distortion of the minimum energy director configuration. With these highly distorted configurations the light transmission through films of the material is still low and the optical switching is in general at higher fields, when the majority of molecules are oriented along the electric field. Correlations between the reorientational switching voltage and the sharpness of the reorientation have been found and tied to the role played by different factors in orienting the liquid cristal director.

A push-pull current circuit for biasing CMOS amplifiers with rail-to-rail input common-mode range is presented. By means of a feedback action, the circuit avoids the large magnitude deviations inherent to this type of amplifier and thus facilitates their optimisation and compensation. Simulated and experimental results obtained from a fabricated 2 μm CMOS test chip are reported.

Room temperature measurements of the stationary noise of the monochromatic light scattered by a polymer-dispersed liquid crystal (PDLC) have been performed in order to get information about the parameters affecting the fluctuation modes within the LC droplets, such as the effective viscosity constant of the anisotropic medium. The power spectra of the scattered light appear to be described in terms of lorentzian functions, whose intensity and cut-off frequency are strongly dependent on both the scattering angle and the electric field across the sample. Hints about the optical-axis configuration within the LC droplets are provided by a thorough analysis of the measured noise. The main discrepancies between the experimental results and the predictions for an infinite nematic LC are pointed out and discussed in terms of the finite size of the LC droplets.

An analogue CMOS buffer configuration, which eliminates the tradeoff between high bandwidth and very low input capacitance, has been designed and simulated in a standard 2 μm process. The circuit shows a total input capacitance less than 50 fF up to 12 MHz and less than 110 fF overall with a 3 dB bandwidth of 20 MHz when driving a 15 pF and 100 kω load. The very small input capacitance and high bandwidth make the circuit very suitable for testing internal sensitive nodes in CMOS analog or mixed-mode circuits.

An accurate and robust ±nVT extractor is introduced. Basically, the circuit consists of a current comparator and a source follower. The output of the comparator controls the bias current level in the follower, and thus its low output resistance is divided by the loop gain providing high accuracy in most applications. Experimental results using commercial matched MOS transistor array TC4007, which have been compared with the value obtained by classical methods, confirm the validity of the proposed circuit.