Le couplage phosphore-phosphore dans l'adenosine di- et triphosphate

AbstractThe pH dependence of spin-spin coupling constants JP-O-P of ADP and ATP has been determined from the phosphorus NMR spectra at 0°. The variation curves have been interpreted as titration curves. These give different pK values. Comparison with the tripolyphosphate shows the existence of triphosphate chain structural deformation in the nucleotides

Optical and Morphological Studies of Thermally Vacuum Evaporated ZnSe Thin Films

Zinc selenide (ZnSe) thin films were deposited on optical glass substrates using thermal vacuum evaporation, by sublimation of zinc selenide powder from a single quartz crucible heated at 600 degrees C. The substrates temperatures were maintained constant during deposition at 220 degrees C. All the samples were subjected to post - deposition thermal treatments in the same deposition chamber, at 250 degrees C for 20 minutes. AFM and SEM studies confirmed that post - deposition annealing improved the grains growth and their distribution over the entire surface of the film. Optical constants (refraction indices and extinction coefficients) of semiconducting ZnSe thin films were measured by spectroscopic ellipsometry in the range of 190 nm to 500 nm. Optical measurements were completed with the spectral dependencies of transmission and absorption using a double beam UV - VIS spectrophotometer. The values for optical bandgaps calculated from the absorption spectra were found to be around 2.7 eV. All these results lead to the conclusion, that ZnSe thin films are good candidates to replace the conventional CdS thin films used as n-type window layers in the thin film heterojunction solar cells

I/O-efficient map overlay and point location in low-density subdivisions

We present improved and simplified i/o-efficient algorithms for two problems on planar low-density subdivisions, namely map overlay and point location. More precisely, we show how to preprocess a lowdensity subdivision with n edges in O(sort(n)) i/o’s into a compressed linear quadtree such that one can: (i) compute the overlay of two such preprocessed subdivisions in O(scan(n)) i/o’s, where n is the total number of edges in the two subdivisions, (ii) answer a single point location query in O(logB n) i/o’s and k batched point location queries in O(scan(n) + sort(k)) i/o’s. For the special case where the subdivision is a fat triangulation, we show how to obtain the same bounds with an ordinary (uncompressed) quadtree, and we show how to make the structure fully dynamic using O(logB n) i/o’s per update. Our algorithms and data structures improve on the previous best known bounds for general subdivisions both in the number of i/o’s and storage usage, they are significantly simpler, and several of our algorithms are cache-oblivious

I/O-efficient map overlay and point location in low-density subdivisions

We present improved and simplified i/o-efficient algorithms for two problems on planar low-density subdivisions, namely map overlay and point location. More precisely, we show how to preprocess a lowdensity subdivision with n edges in O(sort(n)) i/o’s into a compressed linear quadtree such that one can: (i) compute the overlay of two such preprocessed subdivisions in O(scan(n)) i/o’s, where n is the total number of edges in the two subdivisions, (ii) answer a single point location query in O(logB n) i/o’s and k batched point location queries in O(scan(n) + sort(k)) i/o’s. For the special case where the subdivision is a fat triangulation, we show how to obtain the same bounds with an ordinary (uncompressed) quadtree, and we show how to make the structure fully dynamic using O(logB n) i/o’s per update. Our algorithms and data structures improve on the previous best known bounds for general subdivisions both in the number of i/o’s and storage usage, they are significantly simpler, and several of our algorithms are cache-oblivious

Food Waste and Food Safety Linkagesalong the Supply Chain

Food safety, whether actual or perceived, is one of the major reasons for food waste along the agri‐food supply chain. Food safety hazards at farm level such as mycotoxin contamination of feed, overuse of antimicrobials in livestock disease control, and zoonotic disease incursion may lead to food unfit for human consumption and thus waste. Given the importance of safety as one of the most important attributes of food, the appropriate management of risks along the supply chain can contribute to reductions in food loss and waste. However, a better coordination between food waste and safety policies is also needed, which requires: balancing the scientific evidence and the precautionary principle; reviewing current food safety regulations to identify areas potentially leading to avoidable waste; combining the monitoring of safety hazards and waste along the agri‐food chain; provision of tailored information on linkages between food safety and waste; and investment in technologies to accurately assess the edibility of food. Attention needs to be paid to policies and practices on food labelling and packaging to ensure that they do not lead to unintended or unnecessary impacts on food safety and waste, which are not justified by scientific evidence

Analysis of short-term blood pressure variability in pheochromocytoma/paraganglioma patients

Data on short-term blood pressure variability (BPV), which is a well-established cardiovascular prognostic tool, in pheochromocytoma and paraganglioma (PPGL) patients is still lack and conflicting. We retrospectively evaluated 23 PPGL patients referred to our unit from 2010 to 2019 to analyze 24 h ambulatory blood pressure monitoring (24-h ABPM)-derived markers of short-term BPV, before and after surgical treatment. PPGL diagnosis was assessed according to guidelines and confirmed by histologic examination. The 24-h ABPM-derived markers of short-term BPV included: circadian pressure rhythm; standard deviation (SD) and weighted SD (wSD) of 24-h, daytime, and night-time systolic and diastolic blood pressure (BP); average real variability (ARV) of 24-h, daytime, and night-time systolic and diastolic BP. 7 males and 16 females of 53 ± 18 years old were evaluated. After surgical resection of PPGL we found a significant decrease in 24-h systolic BP ARV (8.8 ± 1.6 vs. 7.6 ± 1.3 mmHg, p < 0.001), in 24-h diastolic BP ARV (7.5 ± 1.6 vs. 6.9 ± 1.4 mmHg, p = 0.031), and in wSD of 24-h diastolic BP (9.7 ± 2.0 vs 8.8 ± 2.1 mmHg, p = 0.050) comparing to baseline measurements. Moreover, baseline 24-h urinary metanephrines significantly correlated with wSD of both 24-h systolic and diastolic BP. Our study highlights as PPGL patients, after proper treatment, show a significant decrease in some short-term BPV markers, which might represent a further cardiovascular risk factor

Effect of position on intracranial pressure and compliance: a cross-sectional study including 101 patients

OBJECTIVE: A better understanding of the effect of position on intracranial pressure (ICP) and compliance is important for the development of treatment strategies that can restore normal cerebrospinal fluid (CSF) dynamics. There is limited knowledge on the effect of position on intracranial compliance. In this cross-sectional study the authors tested the association of pulse amplitude (PA) with position and the day/night cycle. Additionally, they describe the postural ICP and PA changes of patients with “normal” ICP dynamics. METHODS: This single-center retrospective study included patients with suspected and/or confirmed CSF dynamics abnormalities who had been examined with elective 24-hour ICP monitoring between October 2017 and September 2019. Patients had been enrolled in a short exercise battery including four positions: supine, lumbar puncture position in the left lateral decubitus position, sitting, and standing. Each position was maintained for 2 minutes, and mean ICP and PA were calculated for each position. The 24-hour day and night median ICP and PA data were also collected. Linear regression models were used to test the correlation of PA with position and day/night cycle. All linear regressions were corrected for confounders. The postural ICP monitoring results of patients without obvious ICP dynamics abnormality were summarized. RESULTS: One hundred one patients (24 males and 77 females) with a mean age of 39 ± 13years (mean ± standard deviation) were included in the study. The adjusted linear regression models demonstrated a significant association of ICP with position and day/night cycle, with upright (sitting and standing) and day ICP values lower than supine and night ICP values. The adjusted linear regression model was also significant for the association of PA with position and day/night cycle, with upright and day PA values higher than supine and night PA results. These associations were confirmed for patients with and without shunts. Patients without clear ICP dynamics abnormality had tighter control of their postural ICP changes than the other patients; however, the difference among groups was not statistically significant. CONCLUSIONS: This is the largest study investigating the effect of postural changes on intracranial compliance. The results of this study suggest that PA, as well as ICP, is significantly associated with posture, increasing in upright positions compared to that while supine. Further studies will be needed to investigate the mechanism behind this association

Uni-directional transport properties of a serpent billiard

We present a dynamical analysis of a classical billiard chain -- a channel with parallel semi-circular walls, which can serve as a model for a bended optical fiber. An interesting feature of this model is the fact that the phase space separates into two disjoint invariant components corresponding to the left and right uni-directional motions. Dynamics is decomposed into the jump map -- a Poincare map between the two ends of a basic cell, and the time function -- traveling time across a basic cell of a point on a surface of section. The jump map has a mixed phase space where the relative sizes of the regular and chaotic components depend on the width of the channel. For a suitable value of this parameter we can have almost fully chaotic phase space. We have studied numerically the Lyapunov exponents, time auto-correlation functions and diffusion of particles along the chain. As a result of a singularity of the time function we obtain marginally-normal diffusion after we subtract the average drift. The last result is also supported by some analytical arguments.Comment: 15 pages, 9 figure (19 .(e)ps files