Consistency of field-theoretical and kinetic calculations of viscous transport coefficients for a relativistic fluid

The transport coefficients of causal relativistic dissipative fluid dynamics are calculated both in a field-theoretical and a kinetic approach. We find that the results from the traditional kinetic calculation by Israel and Stewart are modified. The new expressions for the viscous transport coefficients agree with the results obtained in the field-theoretical approach when the contributions from pair creation and annihilation are neglected.Comment: 4 pages, 2 figure

Consistency of field-theoretical and kinetic calculations of viscous transport coefficients for a relativistic fluid

The transport coefficients of causal relativistic dissipative fluid dynamics are calculated both in a field-theoretical and a kinetic approach. We find that the results from the traditional kinetic calculation by Israel and Stewart are modified. The new expressions for the viscous transport coefficients agree with the results obtained in the field-theoretical approach when the contributions from pair creation and annihilation are neglected.Comment: 4 pages, 2 figure

Increasing Atmospheric Humidity and CO\u3csub\u3e2\u3c/sub\u3e Concentration Alleviate Forest Mortality Risk

Climate-induced forest mortality is being increasingly observed throughout the globe. Alarmingly, it is expected to exacerbate under climate change due to shifting precipitation patterns and rising air temperature. However, the impact of concomitant changes in atmospheric humidity and CO2 concentration through their influence on stomatal kinetics remains a subject of debate and inquiry. By using a dynamic soil–plant–atmosphere model, mortality risks associated with hydraulic failure and stomatal closure for 13 temperate and tropical forest biomes across the globe are analyzed. The mortality risk is evaluated in response to both individual and combined changes in precipitation amounts and their seasonal distribution, mean air temperature, specific humidity, and atmospheric CO2 concentration. Model results show that the risk is predicted to significantly increase due to changes in precipitation and air temperature regime for the period 2050–2069. However, this increase may largely get alleviated by concurrent increases in atmospheric specific humidity and CO2 concentration. The increase in mortality risk is expected to be higher for needleleaf forests than for broadleaf forests, as a result of disparity in hydraulic traits. These findings will facilitate decisions about intervention and management of different forest types under changing climate

The Rise of 144A Market for Convertible Debt

We document and study the migration of convertible debt offerings from the public to the 144A market during 1991-2004. Over 88% of the 144A convertible debt issues are subsequently registered. An analysis of financing costs (gross spreads, yields, and stock price announcements) and issue characteristics indicates that convertible debt issues in these two markets are essentially the same. We find evidence that the 144A market allows firms to better time equity market conditions. Our findings are consistent with the hypothesis that the 144A market is attractive because it allows firms to issue convertible debt more quickly

Effects of unclipping and converting enzyme inhibition on bilateral renal function in Goldblatt hypertensive rats

Effects of unclipping and converting enzyme inhibition on bilateral renal function in Goldblatt hypertensive rats. Previous studies have demonstrated that blockade of the renin-angiotensin system in two-kidney, one clip Goldblatt hypertensive rats induced arterial pressure associated reductions in the function of the renin rich, clipped kidney even though the renin-depleted, contralateral kidney exhibited enhanced renal hemodynamics and excretory function. This study was performed to evaluate the influence of inhibition of the activity of the renin-angiotensin system on the function of each kidney following the unclipping of the clipped kidney. Renin-angiotensin system blockade was accomplished by intravenous infusion of converting enzyme inhibitor (CEI, SQ 20881, 3 mg/hr · kg), either before (group 1, N = 15) or after (group 2, N = 16) removal of the clip. CEI infusion before unclipping decreased arterial blood pressure (BP), from 157 ± 3 to 124 ± 3mm Hg and led to increases in renal blood flow (RBF), GFR, urinary volume and sodium excretion in the nonclipped kidney. When the clip was still in place, renal function decreased in the clipped kidney during CEI infusion. Upon removal of the clip, there were immediate increases in RBF and GFR, and pronounced diuresis; natriuresis and kaliuresis ensued despite a further reduction of BP from 124 ± 3 to 110 ± 3mm Hg. In group 2, unclipping of the clipped kidney prior to administration of CEI reduced BP from 161 ± 4 to 118 ± 3mm Hg within 2hr. Nevertheless, RBF, GFR, urine flow, and sodium and potassium excretion rates increased in this newly undipped kidney. Subsequent infusion of CEI decreased BP further, but RBF, GFR, and urinary excretion rates of both kidneys increased significantly. These results suggest that hemodynamic and excretory function of both the nonclipped and clipped kidneys are influenced substantially by the renin-angiotensin system; however, this influence on the clipped kidney can be unmasked only after the clip has been removed.Effets de l'ablation du clip et de l'inhibition de l'enzyme de conversion sur la fonction rénale bilatérale chez des rats hypertendus selon Goldblatt. Les études antérieures ont démontré que le blocage du système rénine-angiotensine chez des rats hypertendus selon Goldblatt à deux reins et un clip entrainait des réductions de la fonction du rein riche en rénine clippé, en rapport avec la pression artérielle, bien que le rein contralatéral, déplété en rénine, ait une augmentation de l'hémodynamique et de la fonction excrétoire rénales. Cette étude a été entreprise afin d'évaluer l'influence de l'inhibition de l'activité du système rénine-angiotensine sur la fonction de chaque rein après ablation du clip du rein clippé. Le blocage du système rénine-angiotensine a été effectué par perfusion intra-veineuse de l'inhibiteur de l'enzyme de conversion (CEI, SQ 20881, 3 mg/hr · kg) soit avant (groupe 1, N = 15) soit après (groupe 2, N = 16) ablation du clip. La perfusion de CEI avant l'ablation du clip a abaissé la pression artérielle (BP) de 157 ± 3 à 124 ± 3mm Hg, et a augmenté le flux sanguin (RBF), le GFR, le volume urinaires et l'excrétion sodée du rein non clippé. Lorsque le clip était encore en place, la fonction rénale diminuait du côté du rein clippé pendant la perfusion de CEI. Lors de l'ablation du clip, il y avait des augmentations immédiates du RBF et de GFR et une diurèse; une natriurèse et une kaliurèse prononcées se produisaient malgré une réduction supplémentaire de la BP de 124 ± 3 à 110 ± 3mm Hg. Dans le groupe 2, l'ablation du clip avant l'administration de CEI a réduit la BP du rein clippé de 161 ± 4 à 118 ± 3mm Hg en 2hr. Cependant, le RBF, le GFR, le débit urinaire, et l'excrétion de sodium et de potassium se sont élevés dans ce rein dont le clip a été récemment enlevé. La perfusion ultérieure de CEI diminuait BP plus mais RBF, GFR, et les excrétions urinaires des deux reins ont augmenté significativement. Ces résultats suggèrent que les fonctions hémodynamique et excrétoire des reins clippés et non-clippés sont substantiellement influencées par le système rénine-angiotensine; cependant, cette influence sur le rein clippé ne peut être démasquée qu'après ablation du clip