4,297 research outputs found
Жизнь в Риме. Древний Рим в зеркале латинских инскрипций
В настоящей монографии представлена жизнь всех слоев римского общества на основе данных латинских инскрипций. Рассматриваются следующие темы: аристократия, религия, военное дело, римская семья и домашнее хозяйство, жизнь римского обывателя.Публикуемые латинские инскрипции снабжены параллельными переводами на английский язык и краткими историко-филологическими комментариями. Прилагается избранная библиография для дальнейшего чтения, составленная по тематическому принципу (с. 185-188)
Adaptive response to oxidative stress in the filamentous fungus Aspergillus niger B1-D
In the present study, we used a recombinant filamentous fungus strain, Aspergillus niger B1-D, as a model system, and investigated the antioxidant defences in this organism. Our findings indicate that pretreatment with low concentrations of H2O2 completely prevents killing by this oxidant at high concentrations. It shows that A. niger adapts to exposure to H2O2 by reducing growth and inducing a number of antioxidant enzyme activities, including superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, of which the induction of catalase is the most pronounced. Moreover the decline of these antioxidant enzymes activities after H2O2 detoxification, coincides with recommencement of growth. Results from monitoring the extracellular H2O2 concentration clearly indicate a very rapid detoxification rate for H2O2 in adapted A. niger cultures. A mathematical model predicts only very low concentrations of intracellular H2O2 accumulating in such cultures. Our results also show that glutathione plays a role in the oxidative defence against H2O2 in A. niger. On addition of H2O2, the intracellular pool of glutathione increases while the redox state of glutathione becomes more oxidized
INDIGENOUS LAND TENURE AND LAND USE IN ALASKA: COMMUNITY IMPACTS OF THE ALASKA NATIVE CLAIMS SETTLEMENT ACT
Through the utilization of qualitative methods such as archival analysis, semi-structured interviewing, comparative and extended case studies, and observation, this paper closely examines two related Alaska Native communities. Our purpose is to document the impact of the Alaska Native Claims Settlement Act of 1971 (ANCSA) on land tenure, land use, and community structure. In all, 41 interviews were conducted, focusing on the following issues: (1) the role of the tribal government in relation to the regional and village corporate structure; (2) the recent changes in traditional land uses; and (3) how group decisions are made regarding land management and distribution of resources. By locating ANCSA within a broader context of economic, political, and cultural globalization that seeks to substitute traditional collective rights in land with individual tenure in a "free market" economy, the findings of this research may carefully and cautiously be applied beyond North America to other indigenous-state struggles regarding control of land and resources.United States. -- [Alaska Native Claims Settlement Act], Indians of North America -- Legal status, laws, etc. -- Alaska, Land tenure -- Law and legislation -- Alaska, Indians of North America -- Alaska -- Claims, Indians of North America -- Land tenure -- Alaska, Indians of North America -- Alaska -- Government relations -- History, Land Economics/Use,
Obtaining Wave Equations From the Vlasov Equation for Plasmas in Inhomogeneous Magnetic Fields
Abstract Not Provided
A Dynamic Agency Model With Borrowing
Recent research on agency models has emphasized multiperiod contracts. However, most research has assumed the principal could control agents\u27 consumption, choosing to deny them access to a capital market. The few papers that have examined the role of capital markets in an agency model (Braverman and Stiglitz (1982), Rogerson (1985a)) do not allow agents a joint choice of effort and borrowing. This thesis extends these models by allowing agents this joint choice of borrowing and effort, showing how previous results change.;Agents are allowed access to two types of imperfect capital markets. In one model of the capital market, agents can borrow a maximum amount, while in the other model agents can borrow more, risking default and payment of default costs. In addition, compensation contracts are restricted to dynamic rank-order tournaments. Given this specific structure, the agent\u27s and the principal\u27s problems are solved, the optimal forms of contracts are derived, and specific testable predictions are generated about observable variables.;The major prediction, contrary to Fellingham and Newman (1985), is that with risk-neutrality and borrowing, memory contracts dominate nonmemory contracts. This generalizes the results found under risk-aversion by Rogerson (1985a) and Lambert (1983). Second, within these multiperiod memory contracts, the spread and mean of consumption will be rising over the length of the contest, as will the mean value of wages. The third prediction is that agents who do not receive promotions will be observed working extra hours, and those who have missed two promotions in a row will work a higher number of extra hours. These are new, testable predictions, not found in other agency models.;This thesis extends agency models by introducing capital markets in a fuller manner then previously done, and by concentrating on a dynamic rank-order tournament, also in a fuller manner then previously done. The importance of these extensions is shown by the fact that the introduction of a capital has made a crucial difference to the results. Results from models without capital markets are generalized or changed, and new testable predictions are generated
Mechanical determinants of intact airway responsiveness
Airway hyperresponsiveness (AHR) is a hallmark of asthma where constriction of airway smooth muscle (ASM) causes excessive airway narrowing. Asthmatics, unlike healthy subjects, cannot prevent or reverse this narrowing by stretching their airways with a deep inspiration (DI). Since stretching of isolated ASM causes dramatic reductions in force generation and asthmatics tend to have stiffer airways, researchers hypothesize that reduced ASM stretching during breathing and DIs results in hyperreactive airways. However, counterintuitively, excised measurement on intact airways show narrowing is minimally reversed by pressure oscillations simulating breathing and DIs. We hypothesized that AHR does not result from reduced capacity to stretch the airways; furthermore, each constituent of the airway wall experiences different strain magnitude during breathing and DIs.
To test this, we used an intact airway system which controls transmural pressure (Ptm) to simulate breathing while measuring luminal diameter in response to ASM agonists. An ultrasound system and automated segmentation algorithm were implemented to quantify and compare the ability of Ptm fluctuations to reverse and prevent narrowing in larger (diameter=5.72±0.52mm) relative to smaller airways (diameter=2.92±0.29mm). We found the ability of Ptm oscillations to reverse airway narrowing was proportional to strain imposed on the airway wall. Further, tidal-like breathing Ptm oscillations (5-15cmH2O) after constriction imposed 196% more strain in smaller compared to larger airways (14.6% vs. 5.58%), resulting in 76% greater reversal of narrowing (41.2% vs. 23.4%). However, Ptm oscillations applied before and during constriction resulted in the same steady-state diameter as when Ptm oscillations were applied only after constriction.
To better understand these results, we optimized an ultrasound elastography technique utilizing finite element-based image registration to estimate spatial distributions of displacements, strains, and material properties throughout an airway wall during breathing and bronchoconstriction. This required we formulate and solve an inverse elasticity problem to reconstruct the distribution of nonlinear material properties. Strains and material properties were radially and longitudinally heterogeneous, and patterns and magnitudes changed significantly after induced narrowing. Taken together, these data show AHR likely does not emerge due to reduced straining of airways prior to challenge, but remodeling that stiffens airway walls might serve to sustain constriction during an asthmatic-like attack
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