Solvent drag measurement of transcellular and basolateral membrane NaCl reflection coefficient in kidney proximal tubule.

The NaCl reflection coefficient in proximal tubule has important implications for the mechanisms of near isosmotic volume reabsorption. A new fluorescence method was developed and applied to measure the transepithelial (sigma NaClTE) and basolateral membrane (sigma NaClcl) NaCl reflection coefficients in the isolated proximal straight tubule from rabbit kidney. For sigma NaClTE measurement, tubules were perfused with buffers containing 0 Cl, the Cl-sensitive fluorescent indicator 6-methoxy-N-[3-sulfopropyl] quinolinium and a Cl-insensitive indicator fluorescein sulfonate, and bathed in buffers of differing cryoscopic osmolalities containing NaCl. The transepithelial Cl gradient along the length of the tubule was measured in the steady state by a quantitative ratio imaging technique. A mathematical model based on the Kedem-Katchalsky equations was developed to calculate the axial profile of [Cl] from tubule geometry, lumen flow, water (Pf) and NaCl (PNaCl) permeabilities, and sigma NaClTE. A fit of experimental results to the model gave PNaCl = (2.25 +/- 0.2) x 10(-5) cm/s and sigma NaClTE = 0.98 +/- 0.03 at 23 degrees C. For measurement of sigma NaClbl, tubule cells were loaded with SPQ in the absence of Cl. NaCl solvent drag was measured from the time course of NaCl influx in response to rapid (less than 1 s) Cl addition to the bath solution. With bath-to-cell cryoscopic osmotic gradients of 0, -60, and +30 mosmol, initial Cl influx was 1.23, 1.10, and 1.25 mM/s; a fit to a mathematical model gave sigma NaClbl = 0.97 +/- 0.04. These results indicate absence of NaCl solvent drag in rabbit proximal tubule. The implications of these findings for water and NaCl movement in proximal tubule are evaluated

The performance of thin NaI(Tl) scintillator plate for dark matter search

A thin (0.05cm) and wide area (5cmX5cm) NaI(Tl) scintillator was developed. The performance of the thin NaI(Tl) plate, energy resolution, single photoelectron energy and position sensitivity were tested. An excellent energy resolution of 20% (FWHM) at 60keV was obtained. The single photoelectron energy was calculated to be approximately 0.42 0.02keV. Position information in the 5cmx5cm area of the detector was also obtained by analyzing the ratio of the number of photons collected at opposite ends of the detector. The position resolution was obtained to be 1cm (FWHM) in the 5cmx5cm area.Comment: 10 pages. Accepted to Journal of Physical Society of Japa

A Comparative Study of Some Pseudorandom Number Generators

We present results of an extensive test program of a group of pseudorandom number generators which are commonly used in the applications of physics, in particular in Monte Carlo simulations. The generators include public domain programs, manufacturer installed routines and a random number sequence produced from physical noise. We start by traditional statistical tests, followed by detailed bit level and visual tests. The computational speed of various algorithms is also scrutinized. Our results allow direct comparisons between the properties of different generators, as well as an assessment of the efficiency of the various test methods. This information provides the best available criterion to choose the best possible generator for a given problem. However, in light of recent problems reported with some of these generators, we also discuss the importance of developing more refined physical tests to find possible correlations not revealed by the present test methods.Comment: University of Helsinki preprint HU-TFT-93-22 (minor changes in Tables 2 and 7, and in the text, correspondingly

Comparison of Nitrate Contents for Reed Canarygrass and Orchardgrass in Large Amounts of Compound Fertilization

Reed canarygrass (Phalaris arundinacea L.) could be an ideal candidate for manure application. We compared its growth, crude protein (CP) and nitrate N (NO3-N) content to that of orchardgrass (Dactylis glomerata L.) on different levels of nitrogen fertilization (3,10,15 and 20g N m-2, applied from May 15 to September 15 after each monthly cutting. The dry weight (DW) of reed canarygrass increased significantly with increasing amounts of N nitrogen on July, August and September. However, orchardgrass only showed a significant increase in yield on September. The concentration of CP of reed canarygrass was significantly lower than that of orchardgrass with 3 g N m-2 on June, July, August and 10 g N m-2 on August. In contrast to this, CP of reed canarygrass was significantly higher than that of orchardgrass with 15 g N m-2 on July and 20 g N m-2 on July and August. NO3-N content of reed canarygrass was significantly lower than that of orchardgrass with 3 g N m-2 and 10 g N m-2 on June, July and August. We had high NO3-N (\u3e 0.15% N as NO3-N was considered unsafe) with 15 g N m-2 and 20 g N m-2 in both forage species and with 10 g N m-2 in orchardgrass. Our results indicate that reed canarygrass accumulates less NO3-N than orchardgrass with applications of 3 g N m-2 and 10 g N m-2 per cutting