Finite-dimensional crystals B 2,s for quantum affine algebras of type D (1) n

The Kirillov–Reshetikhin modules W^r,s are finite-dimensional representations of quantum affine algebras U’_q labeled by a Dynkin node r of the affine Kac–Moody algebra and a positive integer s. In this paper we study the combinatorial structure of the crystal basis B^2,s corresponding to W^2,s for the algebra of type D⁽¹⁾_n. 2000 Mathematics Subject Classification Primary—17B37; Secondary—81R10 Supported in part by the NSF grants DMS-0135345 and DMS-0200774.     

Ab initio and analytic intermolecular potentials for Ar-CH(3)OH

Ab initio calculations at the CCSD(T)/aug-cc-pVTZ level of theory were used to characterize the Ar-CH(3)OH intermolecular potential energy surface (PES). Potential energy curves were calculated for four different Ar + CH(3)OH orientations and used to derive an analytic function for the intermolecular PES. A sum of Ar-C, Ar-O, Ar-H(C), and Ar-H(O) two-body potentials gives an excellent fit to these potential energy curves up to 100 kcal mol(-1), and adding an additional r(-n) term to the Buckingham two-body potential results in only a minor improvement in the fit. Three Ar-CH(3)OH van der Waals minima were found from the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ calculations. The structure of the global minimum is in overall good agreement with experiment (X.-C. Tan, L. Sun and R. L. Kuczkowski, J. Mol. Spectrosc., 1995, 171, 248). It is T-shaped with the hydroxyl H-atom syn with respect to Ar. Extrapolated to the complete basis set (CBS) limit, the global minimum has a well depth of 0.72 kcal mol(-1) with basis set superposition error (BSSE) correction. The aug-cc-pVTZ basis set gives a well depth only 0.10 kcal mol(-1) smaller than this value. The well depths of the other two minima are within 0.16 kcal mol(-1) of the global minimum. The analytic Ar-CH(3)OH intermolecular potential also identifies these three minima as the only van der Waals minima and the structures predicted by the analytic potential are similar to the ab initio structures. The analytic potential identifies the same global minimum and the predicted well depths for the minima are within 0.05 kcal mol(-1) of the ab initio values. Combining this Ar-CH(3)OH intermolecular potential with a potential for a OH-terminated alkylthiolate self-assembled monolayer surface (i.e., HO-SAM) provides a potential to model Ar + HO-SAM collisions.     

Enhancement of the critical temperature of HgBa₂CuO(4+δ) by applying uniaxial and hydrostatic pressure: implications for a universal trend in cuprate superconductors

It is well known that the superconducting transition temperature (T(c)) of cuprate superconductors can be enhanced by varying certain structural and electronic parameters, such as the flatness of the CuO? planes or their doping level. We determine the uniaxial and hydrostatic pressure derivatives of T(c) in the structurally simple tetragonal compound HgBa?CuO(4+δ) near optimal doping. Our results provide experimental evidence for two further methods to enhance T(c): (i) reducing the area of the CuO? planes, and (ii) increasing the separation of the CuO? planar groups. T(c) is found to couple much more strongly to the ratio c/a of the lattice constants than to the unit cell volume. A comparison with prior results for structurally more complicated cuprates reveals a general trend of uniaxial pressure derivatives with T(c).     

Pressure as a parameter in the study of dilute magnetic alloys

A large body of data is reviewed, which illustrates how the high pressure technique can be used to gain information about the magnetic and electronic state of dilute magnetic alloys. Values for the pressure dependence of the elementary effective exchange interaction between a magnetic impurity spin and the conduction electron sea are extracted from the data and tabulated for a number of extremely dilute alloys containing both transition metal and rare earth impurities. Results of experiments on host alloy series employing ‘lattice pressure’ are compared to the present ‘external pressure’ results and critically analysed; it is shown how such a comparison can be used to give information about the extent of the electronic screening around an impurity potential. The effect of pressure on impurity-impurity interactions in spin glasses is also examined; a comparison of the pressure studies on extremely dilute alloys to those on spin glasses allows an estimate of the nature of the interaction mechanisms important in the latter case. Evidence for a pressure-induced spin glass to Kondo transition in LaCe is also presented. It is suggested that the present results fit into a larger picture that magnetism, when present, tends to be weakened when high pressure is applied.     

A Novel Prospective Study Assessing the Combination of Photodynamic Therapy and Proton Radiation Therapy: Safety and Outcomes When Treating Malignant Pleural Mesothelioma

Malignant pleural mesothelioma remains difficult to treat, with high failure rates despite optimal therapy. We present a novel prospective trial combining proton therapy (PT) and photodynamic therapy (PDT) and the largest‐ever mesothelioma PT experience (n = 10). PDT photosensitizers included porfimer sodium (2 mg·kg^?1; 24 h drug‐light interval) or 2‐[1‐hexyloxyethyl]‐2‐devinyl pyropheophorbide‐a (HPPH) (4 mg·m^?2;48 h) with wavelengths of 630 nm to 60J·cm^?2 and 665 nm to 15‐45J·cm^?2, respectively. With a median age of 69 years, patients were predominantly male (90%) with epithelioid histology (100%) and stage III‐IV disease (100%). PT was delivered to a median of 55.0 CGE/1.8‐2.0 CGE (range 50–75 CGE) adjuvantly (n = 8) or as salvage therapy (n = 2) following extended pleurectomy/decortication (ePD)/PDT. Two‐year local control was 90%, with distant and regional failure rates of 50% and 30%, respectively. All patients received chemotherapy, and four received immunotherapy. Surgical complications included atrial fibrillation (n = 3), pneumonia (n = 2), and deep vein thrombosis (n = 2). Median survival from PT completion was 19.5 months (30.3 months from diagnosis), and 1‐ and 2‐year survival rates were 58% and 29%. No patient experienced CTCAEv4 grade ≥2 acute or late toxicity. Our prolonged survival in very advanced‐stage patients compares favorably to survival for PT without PDT and photon therapy with PDT, suggesting possible spatial or systemic cooperativity and immune effect.     

Chemical Derivatization and Characterization of Novel Antitrypanosomals for African Trypanosomiasis

The search for novel antitrypanosomals and the investigation into their mode of action remain crucial due to the toxicity and resistance of commercially available antitrypanosomal drugs. In this study, two novel antitrypanosomals, tortodofuordioxamide (compound 2) and tortodofuorpyramide (compound 3), were chemically derived from the natural N-alkylamide tortozanthoxylamide (compound 1) through structural modification. The chemical structures of these compounds were confirmed through spectrometric and spectroscopic analysis, and their in vitro efficacy and possible mechanisms of action were, subsequently, investigated in Trypanosoma brucei (T. brucei), one of the causative species of African trypanosomiasis (AT). The novel compounds 2 and 3 displayed significant antitrypanosomal potencies in terms of half-maximal effective concentrations (EC₅₀) and selectivity indices (SI) (compound 1, EC₅₀ = 7.3 μM, SI = 29.5; compound 2, EC₅₀ = 3.2 μM, SI = 91.3; compound 3, EC₅₀ = 4.5 μM, SI = 69.9). Microscopic analysis indicated that at the EC₅₀ values, the compounds resulted in the coiling and clumping of parasite subpopulations without significantly affecting the normal ratio of nuclei to kinetoplasts. In contrast to the animal antitrypanosomal drug diminazene, compounds 1, 2 and 3 exhibited antioxidant absorbance properties comparable to the standard antioxidant Trolox (Trolox, 0.11 A; diminazene, 0.50 A; compound 1, 0.10 A; compound 2, 0.09 A; compound 3, 0.11 A). The analysis of growth kinetics suggested that the compounds exhibited a relatively gradual but consistent growth inhibition of T. brucei at different concentrations. The results suggest that further pharmacological optimization of compounds 2 and 3 may facilitate their development into novel AT chemotherapy.     

More efficient time integration for Fourier pseudospectral DNS of incompressible turbulence

Time integration of Fourier pseudospectral DNS is usually performed using the classical fourth-order accurate Runge-Kutta method or other second- or third-order methods, with a fixed step size. We investigate the use of higher-order Runge-Kutta pairs and automatic step size control based on local error estimation. We find that the fifth-order accurate Runge-Kutta pair of Bogacki and Shampine gives much greater accuracy at a significantly reduced computational cost. Specifically, we demonstrate speedups of 2× to 10× for the same accuracy. Numerical tests (including the Taylor-Green vortex, Rayleigh-Taylor instability, and homogeneous isotropic turbulence) confirm the reliability and efficiency of the method. We also show that adaptive time stepping provides a significant computational advantage for some problems (like the development of a Rayleigh-Taylor instability) without compromising accuracy.