LROC analysis of detector-response compensation in SPECT

Localization ROC (LROC) observer studies examined whether detector response compensation (DRC) in ordered-subset, expectation-maximization (OSEM) reconstructions helps in the detection and localization of hot tumors. Simulated gallium (Ga-67) images of the thoracic region were used in the study. The projection data modeled the acquisition of attenuated 93- and 185-keV photons with a medium-energy parallel-hole collimator, but scatter was not modeled. Images were reconstructed with five strategies: 1) OSEM with no DRC; 2) OSEM preceded by restoration filtering; 3) OSEM with iterative DRC; 4) OSEM with an ideal DRC; and 5) filtered backprojection (FBP) with no DRC. All strategies included attenuation correction. There were four LROC studies conducted. In a study using a single tumor activity, the ideal DRC offered the best performance, followed by iterative DRC, restoration filtering, OSEM with no DRC, and FBP. Statistical significance at the 5% level was found between all pairs of strategies except for restoration filtering and OSEM with no DRC. A similar ranking was found for a more realistic study using multiple tumor activities. Additional studies considered the effects of OSEM iteration number and tumor activity on the detection improvement that iterative DRC offered with respect to OSEM with no DRC.     

Integrated starter generator for 42-V powernet using induction machine and direct torque control technique

This paper describes an integrated starter generator (ISG) for automobile applications with 42-V powernet. This system is based on an induction machine which is directly mounted on the engine crankshaft and controlled using the technique of direct torque control (DTC). The suitability of the technique for ISG application is explained. The control structure of DTC for ISG application is described. Detailed experimental results from a 1.4-1 diesel engine are presented demonstrating the performance of the system during cranking as well as generation. The ISG also incorporates the feature of "on the fly start" during generation mode. Details of a low voltage high current power converter developed for this application are also given.     

Solution of PDEs-electrically coupled systems with electrical analogy

This paper presents an approach to solve coupled systems where electrical/mechanical devices, whose behaviour is governed by a PDE or a system of PDEs, are connected together through an electrical circuit. In an earlier paper [1], it had been shown that PDEs can be modeled by an electrical equivalent circuit generated from the complete set of equations arising from the Finite Element Method (FEM). In this paper, the approach is extended to solve a system of PDEs. The approach allows the simulation of coupled systems with circuit simulation tools alone since the resultant system becomes an electrical circuit after an application of electrical analogy. The coupled system is solved by directly replacing PDE devices with the equivalent circuits. Further, a special circuit simulation technique, viz. multiport decomposition is used in order to solve a large coupled system. A sequential as well as a parallel simulator is built for coupled problems based on the proposed approach. A circuit with 100 linear PDE devices (the equivalent circuit contains 8 million nodes) has been simulated using the parallel simulator in less than 1 h. We have achieved a speedup of 5 over the sequential simulator using 8 processors on distributed memory architecture. The characteristic of p–n junction diode (drift–diffusion equation) is analyzed by our circuit simulator to show that the proposed approach can be used to build a circuit-cum-device simulator.     

Athermalised monolithic VMUX employing silica arrayed waveguide grating multiplexer

The realisation of a monolithic athermalised variable-optical-attenuator-integrated multiplexer (VMUX) implemented in silica-on-silicon waveguide technology is reported. The VMUX incorporates an athermal arrayed waveguide grating, providing <0.05 nm of peak transmission wavelength shift over 20-70/spl deg/C operating ambient independent of attenuator settings.     

Ion implantation of titanium based biomaterials

Titanium and its alloys are widely used as implant materials. Their integration in the bone is in general very good without fibrous interface layer. However, titanium and its alloys have certain limitations. Metal ions are released from the implant alloy and have been detected in tissues close to titanium implants. The release of these elements, even in small amounts, may cause local irritation of the tissues surrounding the implant. Cell and tissue responses are affected not only by the chemical properties of the implant surface, but also by the surface topography or roughness of the implants. To overcome the problem of ion release and to improve the biological, chemical, and mechanical properties, many surface treatment techniques are used. Any surface treatment that would elicit favorable response from tissues can be applied to enhance the usefulness of the implants. In view of this, the current review describes surface modification of titanium and titanium alloys by ion beam implantation.     

Metallographic investigations of the failed superheater tubes used in liquid hydrogen plant

2.25Cr–1Mo low alloy steel tubes of diameter 42.5 mm ID and 46.5 mm OD were used in superheater of liquid hydrogen plant. This superheater had 10 rows of tubes for carrying naphtha and steam and is heated by flue gas. The flue gas directly impinges on the first three tubes of the tube bank. A failure occurred in the first tube leading to the removal of a portion of the material causing to shut down of the plant.Detailed metallurgical investigations were carried out to understand the cause of failure. This paper brings out the metallographic investigations on the failed tubes and the necessary remedial actions thereon.     

Leaching of residues of certain pesticides from black tea to brew

Tea is the most commonly consumed beverage in the world. It is prepared after infusing processed black tea in hot water. During the process of brewing, along with flavour and aroma, the residues of plant protection chemicals may also be transferred into the tea brew or infusion. The leaching of certain pesticides, such as ethion, endosulfan, dicofol, chlorpyrifos, deltamethrin, hexaconazole, fenpropathrin, propargite, quinalphos and lambdacyhalothrin from powdered black tea into the brew was studied. The rate of transfer of the pesticide residue from black tea to the hot brew was largely influenced by physicochemical parameters, such as water solubility and octanol-water partition coefficient. Tea brews prepared from untreated black tea samples were fortified with standard solutions of the respective pesticides, extracted and analysed using GC and HPLC by following standardised methods. Results revealed that the rate of leaching of residues of these pesticides into the tea brew was low due to their low solubilities in aqueous medium and high octanol-water partitioning coefficients.     

Haemorrhagic syndrome after massive transfusion of blood for traumatic liver rupture: disseminated intravascular coagulation? (Author''s transl)

The rate of control of thyrotoxicosis during the first 2 weeks of treatment was documented in 63 patients. Twenty-three patients received carbimazole 40 mg plus lithium carbonate 750 mg daily and a comparable group of 20 patients were given carbimazole 40 mg plus potassium iodide 120 mg daily. In the lithium treated patients the mean percentage fall of serum T4 after 2 weeks treatment was 49% and the fall in serum T3 57%. The results were similar in the iodide treated patients; the mean falls in serum T4 and T3 being 47% and 64%, respectively. Serum lithium values varied between 0.1-1.25 mEq./l; lithium side effects were minor. In a companion study 20 patients were treated with carbimazole alone. The responses in this group were less impressive; the mean falls in serum T4 and T3 at 2 weeks being 18% and 36%, respectively. It is concluded that lithium is a safe adjunct to conventional antithyroid drug therapy in the initial treatment of acute thyrotoxicosis.     

Extratemporal facial nerve injury

Isolated traumatic facial nerve injury, frequently seen in wartime combat, may also be encountered among civilians. The clinical picture occurring as a result of such injury may be confusing because partial, or incomplete, damage to the peripheral nerve may mimic impairment of the central facial motor mechanism. In treating the patient with facial injury, life-threatening aspects of the injury must be assessed and stabilized first. Then, attention may be focused on the injured facial nerve, for which prompt surgical repair is the treatment of choice. Prior to surgery, the assessment of taste and hearing, as well as mastoid and skull x-ray films and electrodiagnostic tests are helpful in localizing the facial nerve injury.     

Consumer-professional collaboration for evaluation in neighborhood mental health programs

Neighborhood mental health programs are challenged with the scientific and fiscal necessity of evaluating their services. Since most such programs are joint endeavors of neighborhood residents (usually a consumer board) and nonneighborhood professionals, such evaluative efforts require the sanction and collaboration of both groups to be maximally effective. However, the authors point out that collaboration is often strained by lack of trust and conflicts of interest. Study design may fail to consider neighborhood values, with the result that the provision of services is impeded, consumers are frightened or coerced, the role of paraprofessionals is threatened, and the consumer board's responsibilities to the neighborhood are ignored. The authors discuss those four issues and suggest ways of resolving them.