The period function for quadratic integrable systems with cubic orbits

AbstractThis paper is concerned with the monotonicity of the period function for families of quadratic systems with centers whose orbits lie on cubic planar curves. It is proved that each such system has a period function with at most one critical point

Molecular Sites and Mechanisms of Action of Alcohol on the NMDA Receptor GluN2B Subunit

Alcohol abuse and alcoholism are behavioral disorders involving altered synaptic transmission in the brain. The N-methyl-D-aspartate (NMDA) receptor, a subtype of glutamate-gated ion channel, has been shown to be one of the most important target sites of alcohol in the central nervous system. The NMDA receptor is formed between two obligatory GluN1 subunits and two GluN2 subunits (2A-2D). Previous studies have been mainly focused on the GluN2A subunit-containing NMDA receptor to study the molecular sites and mechanisms of alcohol action on the NMDA receptors. However, a major role for the GluN2B subunits in the action of alcohol has been pointed out recently. To test the hypothesis that alcohol interacts with specific residues in the membrane-associated (M) domains of the GluN2B subunit to modulate ion channel gating and alcohol sensitivity, we performed site-directed mutagenesis at positions in the GluN2B subunit, transfected mutant receptors into human embryonic kidney (HEK 293) cells, and did whole-cell patch-clamp recording on these cells. One position in the GluN2B subunit showed significant influence on ethanol sensitivity and ion channel functions. Moreover, the manner in which mutations at positions in the GluN2B subunit alter ethanol sensitivity differ from that of the cognate positions in the GluN2A subunit. The predicted structure of the NMDA receptor indicates a close apposition of the alcohol-sensitive positions in the M3 and M4 domains between the GluN1 and GluN2 subunits. By using both two-way ANOVA and mutant cycle analysis, significant interactions affecting ethanol inhibition and glutamate potency were observed at three pairs of positions in GluN1/GluN2B: Met818/Phe637, Phe639/Leu825, and Gly638/Met824; the last pair also interact with each other to regulate ion channel desensitization. To study whether characteristics of NMDA receptor mutations observed in a non-neuronal cell line are also observed in central nervous system (CNS) neurons, we transfected our constructed GluN1/GluN2A NMDA receptors into rat cortical neurons from postnatal day 2 or 3 by using electroporation. Because there is only few endogenous GluN2A subunits in rat cortical neurons early in development, the currents recorded from these transfected neurons are attributable to the introduced NMDA receptors. Electrophysiological recording in these transfected neurons so far yielded currents that closely resemble those observed in HEK293 cells

How do Brazil's mandated blending requirement and world crude oil price affect international markets

Title from PDF of title page (University of Missouri--Columbia, viewed on September 12, 2013).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Julian BinfieldIncludes bibliographical references.M.S. University of Missouri-Columbia, 2013.Dissertations, Academic -- University of Missouri--Columbia -- Agricultural economics."May 2013"In recent years, more and more countries and areas have become increasingly concerned with environmental problems, and energy independence goals as a result of the high crude oil price. In this context, biofuels are widely recognized as an important means of lowering the carbon emissions of transport, and utilizing alternative energy sources, which are beneficial to increasing energy security. Consequently, a great number of national governments across the world have made legislation to require biofuels to form a proportion of transport fuel use. Brazil is one of such countries. It is the second largest country in terms of biofuel production. Also, its biofuels exports and imports have remarkable impacts on international markets. This study examines, in particular, the impacts of Brazil's mandate blending ratio of biofuel in pure gasoline, and a rise in world crude oil price on international ethanol markets. A structure model of Brazil's sugar and ethanol markets is developed and estimated based on regressions and modeler's judgments. This study uses two ways to close the model. The first one is to use single equations for demand from the rest of world. The other way is to link Brazil's markets to FAPRI's models of U.S., EU, and world markets. A baseline projection for the period marketing year 2011/2012 to 2020/2021 is determined. Then, two shocks of the mandated blending ratio and world crude oil are applied. The first scenario indicates blending requirement boosts anhydrous ethanol price, gasoline C price and international hydrous ethanol price. Also, there is a rise in Brazil's consumption of anhydrous ethanol and gasoline C. For the second model, the direction of change for all the endogenous variables are consistent with those in model one, but the magnitude differs. An increase in world crude oil price gives rise to a large switch from petroleum products to biofuels

Bifurcations of limit cycles from cubic Hamiltonian systems with a center and a homoclinic saddle-loop

It is provedin this paper that the maximum number of limit cycles of system [formula] is equal to two in the finite plane, where [formula]. This is partial answer to the seventh question in [2], posed by Arnold

An Estimation of Relationship between Foreign Direct Investment and Industrial Structure Upgrading in Pakistan: Decomposition Analysis

FDI plays an important role in the industrial structure transformation in Pakistan over the years. However, due to the turbulent international financial markets, political instability, frequent strike processions, deteriorating law and order situation, energy crisis and so on, have resulted in FDI fluctuations which seriously impacts the normal operation of the national economy in general and have severe implications for industrial structure improvement in particular. As a result, FDI in Pakistan declined sharply. Many foreign enterprises withdraw their business from Pakistan. There is an urgent need for industrial structure upgrading in Pakistan so as to regain the considerable market potential and attract more FDI in the country. This paper uses co integration analysis and dynamic variance decomposition, to present the relationship between FDI and Pakistan’s industrial structure upgrading. The result shows that there is a stable relationship between FDI and industrial structure upgrading especially in the long-term. Moreover to successfully achieve the task of dual transformation of stabilizing economy for attracting more FDI and upgrading industrial structure government have to follow a viable policy option culminating the hindrances in the process of sustainable development. Keywords: Foreign Direct Investment, Industrial Structure, Political Stability, Decomposition analysi