Abstract:
Several tetraoxane and 4-aminoquinoline molecules were prepared in order to examine the influence of ribofuranose as a carrier molecule on the antimalarial activity of test compounds. The synthesized compounds showed pronounced antimalarial activity against Plasmodium falciparum chloroquine susceptible D6, chloroquine resistant W2 and multidrug-resistant TM91C235 (Thailand) strains. The aminoquinoline derivative 4 was more active against W2 and TM91C235 strains than the control compounds (CQ and MFQ).

Abstract:
There are two main types of models of behavioral change. What are collectively referred to as "individual models" are the predominant frameworks for studying risk behaviors including those related to HIV/AIDS. Individual models focus on risk perceptions, attitudes, outcome expectations, perceived norms, and self-efficacy. Models of risk behavior that focus on social or community factors have more recently been developed in response to criticisms of individual models. I use longitudinal data from the Malawi Diffusion and Ideational Change Project to study worry about HIV/AIDS. Specifically, I ask, what factors determine how much a person worries about HIV/AIDS, and are the predominant factors those that individual models would suggest, or are there are other determinants that have a greater impact on worry? I find that levels of network worry and suspected spousal infidelity have the strongest and most robust influence on respondent worry, providing support for the importance of social factors.

Thetriterpene quassinoid ailanthinone is a structurally intricate natural product possessing highly potent antimalarial activity against multidrug resistance plasmodium parasites. Although the mechanism of action of ailanthinone is not completely understood, it is presumed to disrupt regular ribosomal functions by inhibiting parasite protein synthesis. Natural scarcity and low solubility of many quassinoids have impeded their development as potential clinical candidates, but exquisite potency of ailanthinone against Plasmodium remains compelling in the global fight against malaria. Herein, we report the highly selective synthesis of 1-hydroxyl derivatives of ailanthinone, including ester, carbonate, carbamate and sulfonate derivatives. The key feature of the synthesis is a one-step regioselective modification of the 1-hydroxyl group in favor of two other hydroxyl groups at C12 and C13. Derivatives were obtained via direct reaction with acyl/sulfonyl chlorides in the presence of a tertiary amine base without any protection-deprotection. In vitro antimalarial evaluations of these derivatives were compared with chloroquine and mefloquine against the Plasmodiumfalciparum clones, D6, W2, and TM91C235. The results demonstrate that modification of the 1-hydroxyl group is achievable, and the antimalarial activity of these derivatives relative to the parent product is significantly retained, thus paving the way for synthesis of derivatives with improved biological availability and/or increased potency.

Abstract:
We review the definition of the Casimir energy steming naturally from the concept of functional determinant through the zeta function prescription. This is done by considering the theory at finite temperature and by defining then the Casimir energy as its energy in the limit $T\to 0$. The ambiguity in the coefficient $C_{d/2}$ is understood to be a result of the necessary renormalization of the free energy of the system. Then, as an exact, explicit example never calculated before, the Casimir energy for a massive scalar field living in a general $(1+2)$-dimensional toroidal spacetime (i.e., a general surface of genus one) with flat spatial geometry ---parametrized by the corresponding Teichm\"uller parameters--- and its precise dependence on these parameters and on the mass of the field is obtained under the form of an analytic function.

Abstract:
In previous articles it was demonstrated that the total cross section of the scattering of two light particles (zero modes of the Kaluza-Klein tower) in the six-dimensional $\lambda \phi^{4}$ model differs significantly from the cross section of the same process in the conventional $\lambda \phi^{4}$ theory in four space-time dimensions even for the energies below the threshold of the first heavy particle. Here the analytical structure of the cross section in the same model with torus compactification for arbitrary radii of the two-dimensional torus is studied. Further amplification of the total cross section due to interaction of the scalar field with constant background Abelian gauge potential in the space of extra dimensions is shown.

Abstract:
We consider the heat-kernel expansion of the massive Laplace operator on the three dimensional ball with Dirichlet boundary conditions. Using this example, we illustrate a very effective scheme for the calculation of an (in principle) arbitrary number of heat-kernel coefficients for the case where the basis functions are known. New results for the coefficients $B_{\frac 5 2},...,B_5$ are presented.

Abstract:
The vacuum energy of a scalar field in a spherically symmetric background field is considered. It is expressed through the Jost function of the corresponding scattering problem. The renormalization is discussed in detail and performed using the uniform asymptotic expansion of the Jost function. The method is demonstrated in a simple explicit example.

Abstract:
We consider semitransparent pistons in the presence of extra dimensions. It is shown that the piston is always attracted to the closest wall irrespective of details of the geometry and topology of the extra dimensions and of the cross section of the piston. Furthermore, we evaluate the zeta regularized determinant for this configuration.

Abstract:
We develop a formalism for the calculation of the ground state energy of a spinor field in the background of a cylindrically symmetric magnetic field. The energy is expressed in terms of the Jost function of the associated scattering problem. Uniform asymptotic expansions needed are obtained from the Lippmann-Schwinger equation. The general results derived are applied to the background of a finite radius flux tube with a homogeneous magnetic field inside and the ground state energy is calculated numerically as a function of the radius and the flux. It turns out to be negative, remaining smaller by a factor of $\alpha$ than the classical energy of the background except for very small values of the radius which are outside the range of applicability of QED.