Alternatives to the stochastic "noise vector" approach

Several important observables, like the quark condensate and the Taylor coefficients of the expansion of the QCD pressure with respect to the chemical potential, are based on the trace of the inverse Dirac operator and of its powers. Such traces are traditionally estimated with "noise vectors" sandwiching the operator. We explore alternative approaches based on polynomial approximations of the inverse Dirac operator.Comment: Eight pages, thirteen figures. Proceedings of the 35th International Symposium on Lattice Field Theor

The Tale of Parathyroid Function in Idiopathic Hypercalciuria

At the origin, idiopathic hypercalciuria has been described as a syndrome consisting of normocalcemia, low plasma phosphate levels and abnormally high urinary calcium excretion. The cause of this syndrome was subject to many investigations throughout the years. Two main pathophysiologic hypotheses have been proposed: a) primary intestinal hyperabsorption of calcium, leading to depression of parathyroid hormone (PTH) secretion ( absorptive hypercalciuria); and b) primary renal tubular leak of calcium which stimulates PTH secretion (secondary hyperparathyroidism). Most of the published studies indicate that intestinal hyperabsorption of calcium with subsequent relative hypoparathyroidism is the primary event causing idiopathic hypercalciuria, and that this occurs as a consequence of increased production of 1,25(OH)2-vitamin D3 (calcitriol). Fasting hypercalciuria, originally taken as evidence for a renal leak of calcium, appears to be, at least in part, the consequence of relative hypoparathyroidism

Vitamin B6 metabolites in idiopathic calcium stone formers: no evidence for a link to hyperoxaluria

Vitamin B6 metabolites and their potential correlates to urinary oxalate excretion in idiopathic calcium stone formers (ICSF) compared with healthy subjects were investigated. This clinical study was performed in a population of male ICSF with (Hyperoxalurics, n=55) or without hyperoxaluria (Normooxalurics, n=57) as well as in 100 healthy male control subjects. Pyridoxal 5'-phosphate serum concentration (S-pyridoxal 5'P) and 24-h urinary excretion of 4-pyridoxic acid (U-4pyridoxic acid) were measured using HPLC; 24-h urinary excretion of oxalate (U-oxalate) was measured concurrently. A subgroup of subjects (40 Hyperoxalurics, 15 Normooxalurics and 50 controls) underwent the same measurements before and after 7-day pyridoxine loading per os (pyridoxine hydrochloride, 300mg/d). Under usual conditions, U-4pyridoxic acid was similar in the three groups, whereas mean S-pyridoxal 5'P was significantly lower (p<0.0001) in the Hyperoxalurics (59.6±21.2nmol/L) and in the Normooxalurics (64.9±19.7nmol/L) than in the controls (86.0±31.0nmol/L). No correlation could be found between U-oxalate and U-4pyridoxic acid or S-pyridoxal 5'P. After B6 loading, S-pyridoxal 5'P was still significantly lower in the Hyperoxalurics (415±180nmol/L, p<0.001) and in the Normooxalurics (429±115nmol/L, p=0.036) than in the controls (546±180nmol/L), although there was no difference between groups for U-4pyridoxic acid. No correlation in any group could be found between changes in U-oxalate and changes in U-4pyridoxic acid or S-pyridoxal 5'P. Although there is no vitamin B6 deficiency in ICSF with or without hyperoxaluria, these patients, on average, have lower levels of S-pyridoxal 5'P than healthy subjects. However, this slight decrease does not seem to account for idiopathic hyperoxaluri

Modelling the Guayule plant growth and development with a Functional Structural Plant Model

The Guayule (Parthenium argentatum, Asteraceae), is a small ramified tree native to the northern Mexico and southwestern United States. The guayule shows a growing interest in research and agriculture (Ray, 1993) due to its hypoallergenic latex properties (Taurines et al., 2019), and seems adapted to South France climate (Sfeir and al., 2014). However, the production itineraries in relation to latex production are still not assessed, and so far little studies were done on the plant structure and functioning. This study aims to propose a first FSPM of the species using the GreenLab model, calibrated from data issued from two varieties in different environmental conditions. The studying methodology is first based on a qualitative architectural analysis (Barthelemy and al., 2007). Second, on the various axis typologies, the development and branching stochastic rules can then be retrieved from field internode distributions collections. Finally, the organ source and sink relations parameters can be fitted from dedicated dry weight measurements (Kang et al., 2018). Experimental plots were hold south of France, close to Montpellier on two varieties CL1 and CLA1, with six environmental conditions related to density (9091 and 62500 plants per hectare) and hydric pressure (no stress, low stress and high stress). 50 plants per environmental conditions were measured. The sampling was optimized to the plant structure and to quantify the polyisoprene and resins contents. The guayule shows a sympodial development is composed of modules with terminal inflorescence. Its architecture corresponds to the Leeuwenberg's model (Hallé et al., 1978). The axes are constituted of successive modules. Over a year, the plant produces eight to nine successive modules. Studying the plant structure, we found out that the number of relay axis per module follows a binomial distribution. The modules are ordered from the plant base to the top. And these modules are composed of internodes whose number also follows a binomial law, which parameters are quite stable from one order to another. In the further modelling process, we thus did consider that the plant elementary unit was the module, called as a meta-phytomer. Under this assumption, we summarized the total dry weight of leaves and internodes per module to build the axis organic series (Buis and Barthou, 1984). Field measurements issued from these two series constituted then a target to be adjusted by the structural functional GreenLab model (Kang et al, 2018) in order to calibrate the organ source parameters. An initial analysis calculated the strength sink of leaves and internodes in a context of free growth and analysed the differences between the two varieties. We are currently applying the methodology to assess the impact on the parameters of development and growth, the effects of planting density and irrigation. This first modelling study hold on two varieties on the Guayule tree shows that the plant structure can be efficiently modelled using a simple module approach. The development parameters, defining the module number of phytomers and branching rules are nearly stable and close for both varieties under the various environmental conditions. First functioning parameters were also retrieved from the measurements. These parameters make it possible to obtain the first stochastic 3D simulations of the Guayule's growth and architecture for both varieties

Chronic respiratory alkalosis induces renal PTH-resistance, hyperphosphatemia and hypocalcemia in humans

Chronic respiratory alkalosis induces renal hyperphosphatemia and hypocalcemia in humans. The effects of chronic respiratory alkalosis on divalent ion homeostasis have not been reported in any species. We studied four normal male subjects during a four-day control period (residence at 500 m), during six days of chronic respiratory alkalosis induced by hypobaric hypoxia (residence at 3450 m), followed by a six-day eucapnic recovery period (500 m) under metabolic balance conditions. Chronic respiratory alkalosis (ΔPaCO2, -8.4mm Hg, Δ[H+] -3.2 nmol/liter) resulted in a sustained decrement in plasma ionized calcium concentration (Δ[IoCa++]p, -0.10 mmol/liter, P < 0.05) and a sustained increment in plasma phosphate concentration (Δ[PO4]p, +0.14 mmol/liter, P < 0.005) associated with increased fractional excretion of Ca++ (+0.5%, P < 0.005), decreased phosphate clearance (-6.1 ml/min, P < 0.025) and decreased excretion of nephrogenous cAMP (-1.5 nmol/100 ml GFR, P < 0.0025). Urinary phosphate excretion decreased by 15.4 mmol/24 hr on day 1 of chronic respiratory alkalosis (P < 0.0025), but returned to control values by day 6 despite hyperphosphatemia. Serum intact [PTH] did not change. Sustained hypomagnesuria (-0.8 mmol/24 hr, P < 0.05) occurred during chronic respiratory alkalosis and was accounted for, at least in part, by decreased fractional excretion of Mg++ (-0.7%, P < 0.05) in the absence of change in plasma magnesium concentration. Serum 1,25(OH)2D levels were unchanged by chronic respiratory alkalosis. In conclusion, the decrease in nephrogenous cAMP generation despite unchanged serum intact PTH concentration suggests that chronic respiratory alkalosis results in impaired renal responsiveness to PTH as manifested by alterations in PTH-dependent renal calcium and phosphate transport. Hypomagnesuria in chronic respiratory alkalosis may be due, at least in part, to hypocalcemia-induced enhancement of renal magnesium reabsorption. The failure of [PTH] to increase during hypocalcemia may reflect defective PTH secretion

On modeling and measuring viscoelasticity with dynamic Atomic Force Microscopy

The interaction between a rapidly oscillating atomic force microscope tip and a soft material surface is described using both elastic and viscous forces with a moving surface model. We derive the simplest form of this model, motivating it as a way to capture the impact dynamics of the tip and sample with an interaction consisting of two components: interfacial or surface force, and bulk or volumetric force. Analytic solutions to the piece-wise linear model identify characteristic time constants, providing a physical explanation of the hysteresis observed in the measured dynamic force quadrature curves. Numerical simulation is used to fit the model to experimental data and excellent agreement is found with a variety of different samples. The model parameters form a dimensionless impact-rheology factor, giving a quantitative physical number to characterize a viscoelastic surface that does not depend on the tip shape or cantilever frequency.Comment: 13 pages, 7 figure

Reduction Theorems for Optimal Unambiguous State Discrimination of Density Matrices

We present reduction theorems for the problem of optimal unambiguous state discrimination (USD) of two general density matrices. We show that this problem can be reduced to that of two density matrices that have the same rank $n$ and are described in a Hilbert space of dimensions $2n$. We also show how to use the reduction theorems to discriminate unambiguously between N mixed states (N \ge 2).Comment: 6 pages, 1 figur