A time-frequency analysis method for radar scattering

A time-frequency analysis method to study electromagnetic scattering is presented and demonstrated using canonical objects. The time-frequency analysis method utilizes the Bargmann transform to formulate the signal representation in phase space. The use of the Bargmann transform leads to an attractive parametric signal representation in terms of complex polynomials, and elliptical filters can be constructed to crop or extract selected areas of the phase plane. The signal representation and filtering operations are demonstrated using scattering responses from spheres and thin wires, and the prominent scattering features are identified and extracted     

Physical Characterization of Anhydrous and Hydrous Forms of the Hydrochloride Salt of BVT.5182 A Novel 5-HT6 Receptor Antagonist

ABSTRACT

The physicochemical properties of 1-benzenesulfonyl-4-(piperazin-1-yl)-indole hydrochloride, a novel 5-HT₆ receptor antagonist for the treatment of obesity were characterized. Two solid state forms were identified at ambient conditions (23°C): an anhydrate form (1) and a hydrate form (2), with 1.5 moles of H₂O. The latter easily dehydrates and rehydrates without affecting the crystal morphology. Investigations of the propensity for interconversion between the two forms reveal that a) conversion of 2→1 takes place above 145°C and that b) conversion of 1→2 only occurs after crystallization from supersaturated aqueous solutions at a water activity ≥0.94 or in the presence of comparable amounts of crystals of 2 in water at ambient conditions. However, in an equimolar suspension of 1 and 2 at 37°C no phase transformation was observed. Thus, the difference in chemical potential between the two forms is small. Form 1 was shown to have overall favorable solid state properties and, hence, considered the preferred form for continued pharmaceutical development. The characterization was performed by means of light microscopy, scanning electron microscopy, powder X-ray diffraction, FTIR/NIR-spectroscopy, differential scanning calorimetry, hot stage microscopy, thermogravimetry, dynamic vapor sorption, Karl Fischer water content determination, phase stability studies of suspensions, solubility, and intrinsic dissolution rate measurements.     

Laparoscopic splenectomy in beta-thalassemia major patients. Advantages and disadvantages

BACKGROUND: Splenectomy is indicated in patients with thalassemia major when they develop hypersplenism with subsequent need for increased transfusions. Extreme splenomegaly is considered a restrictive factor for laparoscopic splenectomy in these patients. METHODS: Laparoscopic splenectomy was undertaken in 12 beta-thalassemia major patients with massive splenomegaly. The devascularization of the organ was performed with serial ligations of the splenic vessels starting from the lower pole of the organ. The spleen was extracted from the abdominal cavity through a 5-cm incision in the left iliac fossa, which incorporated two port sites. RESULTS: The procedure was concluded laparoscopically in 10 cases, while two patients were converted due to difficulty in controlling bleeding from branches of the splenic vein. The patients tolerated the procedure well and had a postoperative hospital stay of 3-6 days. CONCLUSIONS: From our limited initial experience it seems that laparoscopic splenectomy in the difficult setting of thalassemia major patients is feasible, but extreme care is required in order to avoid hemorrhagic complications.     

Linear program synthesis for direct broadcast satellite phasedarrays

Synthesis based on sampling functions in fixed positions was used to optimize the radiation pattern of antenna phased arrays for direct broadcast satellite applications. The synthesis procedure described obtains the antenna excitations required to create a shaped sector beam which uniformly illuminates a desired region and minimizes the maximum sidelobe level. The method begins with the composing functions from Woodward-Lawson synthesis. By fixing the position of these functions, a simplex formulation can be used rather than iterative methods. The simplex formulation is more computer-efficient because the algorithm is guaranteed to converge. Examples of synthesis using this procedure are given     

Potential Temperature Rise Induced by Electromagnetic Field in Brain Tissues

The differential temperature rise in a spherical region stimulating a potential hot spot in the central region of a human head has been determined, takdng into account heat conduction as well as heat convection due to blood flow. The results apply in general to ali cases where the dimensions of the model and the frequency of the incident electromagnetic wave is such that a hot spot is formed near the central region. For a heat deposition rate of 10 mW/g in a hot spot of 1 cm radius, a differential temperature rise over the ambient tissues and blood is approximately 0.5°C. This corresponds to the case of a differential absorption cross section of 1 cm-1 for a 5 cm radius sphere exposed to an incident power density of 10 mW/cm2. For larger models of man's head the differential temperature rise is smaller.     

A zeolite family with chiral and achiral structures built from the same building layer

Porosity and chirality are two of the most important properties for materials in the chemical and pharmaceutical industry. Inorganic microporous materials such as zeolites have been widely used in ion-exchange, selective sorption/separation and catalytic processes. The pore size and shape in zeolites play important roles for specific applications. Chiral inorganic microporous materials are particularly desirable with respect to their possible use in enantioselective sorption, separation and catalysis. At present, among the 179 zeolite framework types reported, only three exhibit chiral frameworks. Synthesizing enantiopure, porous tetrahedral framework structures represents a great challenge for chemists. Here, we report the silicogermanates SU-32 (polymorph A), SU-15 (polymorph B) (SU, Stockholm University) and a hypothetical polymorph C, all built by different stacking of a novel building layer. Whereas polymorphs B and C are achiral, each crystal of polymorph A exhibits only one hand and has an intrinsically chiral zeolite structure. SU-15 and SU-32 are thermally stable on calcination.     

Inhibitory effect of organic acid salts on spoilage flora in culture medium and cured cooked meat products under commercial manufacturing conditions

Lactobacillus curvatus, isolated from a spoiled vacuum-packaged 'pariza' type meat product, was used to inoculate modified MRS broth containing sodium lactate, sodium acetate and potassium sorbate in different concentrations, alone or in inter se combinations. Two commercial preparations (MIX 1 and MIX 2) were also used containing combinations of the above antimicrobials. Results from the preservatives addition to the culture medium showed highest antimicrobial activity in the case of the sodium lactate (2%, 3% or 4%), sodium acetate (0.5%) and potassium sorbate (0.15%) combination. Results from the preservatives addition to two types of thermally processed meats showed that sodium lactate and the combination of sodium lactate, sodium acetate and potassium sorbate were the most effective; extending the products shelf life an additional 10 days. Finally, MIX 1 and MIX 2 suppressed the lactic acid bacteria (LAB) growth in the culture medium but not in the final product.     

Theoretical investigation of polymers near surface of various molecular weights,architecture and external parameters by mean-field variable-density model

We extend our recently developed numerical self-consistent mean-field method in order to investigate polydisperse polymer near surfaces and polymer brushes of variable density in the interfacial region. The system studied is melt polypropylene of various architectures (linear or star) and various molecular weights (monodisperse or polydisperse) under constant external pressure. Our main goal is to systematically study the mechanical properties of interfacial systems between solid surfaces and polymer melts. The mechanical properties and especially the fracture dynamics are investigated by a kinetic Monte Carlo simulation. The findings are supported and compared to several structural properties of the macromolecular interfacial system. Our results are in accordance to expected behavior and experimental data.     

Effect of surface cooling and blood flow on the microwave heating of tissue

The one-dimensional heat transport equation has been solved for a semi-infinite plane of tissue irradiated by microwave radiation, to determine the effects of thermal convection due to blood flow and transfer of heat from the tissue surface into space on the steady-state temperature distribution in the tissue. For microwaves in the 1 to 10-GHz range, the effective heating depth is 1 to 2 cm, and can be much deeper than the penetration depth of the radiation in the tissue. The position of the maximum tissue temperature can be varied by a centimeter or so by cooling the surface. The results suggest that microwave irradiation of simulated biomaterials is not likely to provide accurate estimates of the actual microwave-induced temperature distribution in tissue.     

Boundary waves along an impedance plane with a linearly varying impedance

A formal and asymptotic solution has been obtained for boundary waves which are supported by an infinite plane impedance boundary with a linearly varying impedance. The asymptotic solution (with respect to large distance from the origin) has three terms which are recognized as an incident, a reflected boundary wave, and a radiated wave. It is found that an increasing rate of change of the boundary impedance corresponds to more tightly bound boundary waves, to a power reflection coefficient approaching unity, and to a radiation efficiency approaching zero.