691 research outputs found
Diffusive Logistic Equations with Harvesting and Heterogeneity Under Strong Growth Rate
We consider the equation âÎu=auâb(x)u2âch(x) in Ω,u=0 on âΩ, where Ω is a smooth bounded domain in RN, b(x) and h(x) are nonnegative functions, and there exists Ω0ââΩ such that {x:b(x)=0}=Ω¯¯¯0. We investigate the existence of positive solutions of this equation for c large under the strong growth rate assumption aâ„λ1(Ω0), where λ1(Ω0) is the first eigenvalue of the âÎ in Ω0 with Dirichlet boundary condition. We show that if hâĄ0 in ΩâΩ¯¯¯0, then our equation has a unique positive solution for all c large, provided that a is in a right neighborhood of λ1(Ω0). For this purpose, we prove and utilize some new results on the positive solution set of this equation in the weak growth rate case
Preventing effect of vitamin E on oocytes apoptosis in morphinetreated mice
Several studies have shown that Morphine Sulfate affects on fertility, embryogenesis and consequent pregnancy loss and ultrastructural alterations of oocytes in animal model. This study was done to determine the effect of morphine sulfate on oocytes apoptosis and preventive role of daily supplementation of Vitamin E on oocytes apoptosis in morphine sulfate -treated mice. Twenty-four NMARI female mice were randomly allocated into four experimental groups. For 15 days, control group received saline (0.2 ml/day by subcutaneous injection), group I Vitamin E (60 mg/kg/day orally), group II Morphine Sulfate (10 mg/kg/day by subcutaneous injection) and group III Morphine Sulfate with Vitamin E (60 mg/kg/day orally). Then, animals were superovulated with PSMG (10 Units) and 10 Unites of HCG. The next day the animals were sacrificed, oocytes were flushed from each fallopian tube. The collected oocytes were subjected to determine apoptosis by Tunnel assay with using Fluorescent Microscope. According to our results, the number of retrieved oocytes were 121, 132, 86 and 114 in control, experimental group I, II and III, respectively. Morphine Sulfate treatment increased apoptosis in oocytes to 17.44% whereas oocytes apoptosis was 4.13% in Controls. Supplementation with Vitamin E in Morphine Sulfate -treated mice reduced the oocytes apoptosis to 7.01%. This study showed that Morphine can increase apoptosis in oocytes and Vitamin E treatment significantly reduces oocytes apoptosis in the Morphine Sulfate -treated mice
Dimensions and Determinants of Financialisation: Comparing OECD Countries since 1997
The financialisation literature has grown over the past decades. Despite a generally accepted definition, financialisation has been used to describe different phenomena. We distinguish between financialisation of non-financial companies, households and the financial sector and use activity and vulnerability measures. We identify seven financialisation hypotheses in the literature and empirically investigate them in a cross-country analysis for 17 OECD countries and two time periods, 1997â2007 as well as 2008â17. We find different financialisation measures are only weakly correlated, suggesting the existence of distinct financialisation processes. There is strong evidence that financialisation is linked to asset price inflation and correlated with a debt-driven demand regime. Financial deregulation encourages financialisation. There is limited evidence that market-based financial systems are more financialised. Foreign financial inflows do not seem a main driver. We do not find indication that an investment slowdown precedes financialisation. Our findings suggest financialisation should be understood as a variegated process, playing out differently across economic sectors and countries
Bank Liquidity Creation: A New Global Dataset for Developing and Emerging Countries
The pre-Global Financial Crisis build-up, followed by the post-crisis collapse, in bank liquidity creation in developed countries is well-documented (Berger and Bowman, 2009). Comparable analyses on developing and emerging countries (DECs) have been severely hindered by the lack of detailed bank-by-bank balance sheet data. This paper proposes a new, high-frequency, Aggregate Bank Liquidity Creation (A-BLC) measure for 114 DECs on a comparable cross-country basis, which relies on macroeconomic, country-wide, banking systemsâ balance sheet data. The A-BLC database allows us to assess the extent of bank fragility arising from illiquidity associated with intermediation at the banking system level for every DEC, at a monthly frequency over the period 2001-2016. Our measure captures more accurately than other measures proposed in the literature the evolution of bank liquidity creation in the DECs. Stylised facts and panel-regression analysis suggest a sharp pre-crisis build-up and post-crisis fall in liquidity creation in DECs, larger then that observed for developed countries. In addition, financial depth and stability appear as particularly important drivers of A-BLC in DECs
Anisotropic low-temperature piezoresistance in (311)A GaAs two-dimensional holes
We report low-temperature resistance measurements in a modulation-doped,
(311)A GaAs two-dimensional hole system as a function of applied in-plane
strain. The data reveal a strong but anisotropic piezoresistance whose
magnitude depends on the density as well as the direction along which the
resistance is measured. At a density of cm and for a
strain of about applied along [01], e.g., the
resistance measured along this direction changes by nearly a factor of two
while the resistance change in the [33] direction is less than 10% and
has the opposite sign. Our accurate energy band calculations indicate a
pronounced and anisotropic deformation of the heavy-hole dispersion with
strain, qualitatively consistent with the experimental data. The extremely
anisotropic magnitude of the piezoresistance, however, lacks a quantitative
explanation.Comment: 4 pages. Submitted to Applied Physics Letter
Flexible Buffer Materials to Reduce Contact Resistance in Thermal Insulation Measurements
Thermal insulation test methods approach their lower limits as thermal resistance falls below 0.1 m2â
K/W. This is the minimum value specified in ASTM C 518 (ASTM International, 2010b) while ASTM C 177 (ASTM International, 2010a) proposes about 0.06 m2â
K/W. Nevertheless these are the test methods, along with their ISO equivalents, required by Australasian building codes and directed at many products and materials with thermal resistance on the low side of 0.1 m2â
K/W. Alternatives, such as ASTM E 1530 (ASTM International, 2011), cover much lower resistances but require carefully prepared small specimens and very-high contact pressures and are therefore largely unsuitable for both technical and compliance reasons. For these low resistances, the insulation test methods face large errors because of interface resistance between specimen and the apparatus hot and cold plates. Staying with C 518, the problem can be avoided by using direct measurement of the test specimen surface temperatures, but this is difficult, has its own accuracy issues, and is often impractical for commercial laboratories. This technique is generally used in conjunction with interface materials such as flexible foam between the specimen and the hot and cold plates, to enhance contact and also provide an access path for temperature sensors. The alternative prospect of using these interface materials to ensure good specimen contact has been studied, in conjunction with a simple two-step thermal resistance determination based on the difference between presence and absence of the test specimen.
This article presents results of a study using this difference approach for the measurement of 12 highly conducting materials, including sheets of aluminum, phenolic, HDPE, MgO, bonded rubber and cork granules, PMMA, and compressed wood fiber. For each material, repeated measurements have been performed with four different interface or âbufferâ materials: PVC, silicone, EVA, and nitrile. Silicone sponge provides the most uniform results, consistent with a measurably lower hysteresis. The difference technique yielded a lower indicated thermal resistance than direct measurement by between 0.003 and 0.01 m2â
K/W, with some variation depending on the specimen surface characteristics and to a lesser extent on the choice of buffer. Larger differences were associated with bowed, uneven or roughly surfaced specimens. The difference-technique results have greater variability, but they may be seen as better estimates of the actual specimen resistance, as contact resistance is much lower for soft-surface interfaces. An interface resistance of up to 0.01 m2â
K/W is large enough to be of significance in many thermal measurements
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