Synthesis of submicron size silver powder for passive components application

Submicron silver powder was prepared from AgNO₃ by a chemical reduction method in the presence of a mixture of caprylic acid and triethanolamine as a surfactant. Hydrazine hydrate (N₂H₄·H₂O) is preferred as a reducing agent. A spherical silver powder with an average particle size of about 150 nm was achieved. Effort was also made to correlate the crystal structure and microstructure evolution of the prepared powders with the resultant thick film characteristics.     

Eyeblink conditioning in the rabbit (Oryctolagus cuniculus) with stimulation of the mystacial vibrissae as a conditioned stimulus.

Eyeblink conditioning is a well-understood paradigm for the study of learning and memory and has been successfully employed with the use of auditory and visual conditioned stimuli (CSs). In this study, vibrotactile stimulation of the mystacial vibrissae was examined as an alternative CS in the rabbit ( Oryctolagus cuniculus). The technique is described and acquisition of eyeblink conditioning (EBC) with stimulation of a single row of vibrissae in a delay paradigm is reported. Extinction of EBC with presentation of the CS alone is demonstrated, as well as reacquisition with stimulation of a single whisker. Finally, control experiments ensure that the CS has no auditory components. Ipsilateral presentation of the CS and airpuff is a more effective combination for training than contralateral presentations. Vibrotactile stimulation of the vibrissae as a CS will enable further examination of the neural correlates of learning in a well-characterized sensory system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Utility of catalytic models in the estimation of incidence and prevalence of malaria in a hyperendemic situation

Simple catalytic models were used for estimating the true incidence of malaria in hyperendemic villages of Koraput District in Orissa State where Plasmodium falciparum is predominant. The hill top villages recorded a slide positive rate of 45.68. The daily rate of inoculation among infants was estimated to be 0.00781. The inoculation rate was so high that the recovery from one infection was compensated by the subsequent infection and hence the prevalence continued to increase with age. The model adequately represents the observed data for infants but could not be used for estimating the true prevalence in the adult population without incorporating other factors like immunity and superinfection.     

Colloid cyst xanthogranuloma of the third ventricle--a case report

Diagnosis and treatment of malignant pericardial effusion are difficult in clinical practice. This paper reports the feasibility and reliability of percutanous trans-catheter intervention for the diagnosis and treatment of malignant pericardial effusion. Under echocardiagraphic guidence, pericardial puncture was performed and a heamostasis sheath was placed in situ by Seldinger technique. Through the sheath multiple biopsies of the pericardium were taken for pathological examination. A pigtail catheter was inserted to drain off the effusion. According to pathological report suitable anti-cancer drugs were instilled into the pericardial cavity through indwelling catheter for 3-5 days. The catheter was withdrawn when fluid did not re-accumulate. Diagnosis was made in over 96.0% of the cases. Upon follow-up for 3-6 months, complete remission was seen in 96.0% of the treated patients. No significant complication was found in all patients. Percutaneous trans-catheter intervention is a useful approach for the diagnosis and treatment of malignant pericardial effusion.     

Enhancement of Tensile and Microhardness of AA 6082-T6 Friction Stir Welds via Brass Interlayers

Russian Journal of Non-Ferrous Metals - This paper investigates the effects of brass interlayer on the microstructural and mechanical properties of friction stir welded AA 6082-T6. To analyze the...     

Deuteron and helium ion irradiation of ceramic coatings on Nb-1% Zr

The surface damage to insulating barium alumino-silicate glass coatings due to irradiation by 100- and 250-keV deuterons and helium ions at room temperature and at 300° C has been studied. Blisters are observed after irradiation at room temperature with both deuterons and helium ions with energies of 100 keV and 250 keV. For deuteron irradiation a large fraction of the blisters have diameters which are approximately 3 to 5 times larger than the diameter observed with helium ions for identical irradiation conditions, but the density of blisters is nearly an order of magnitude lower. For irradiation at 300° C, no blisters are observed with either type of particle. The sharp rise in permeation rate with temperature is thought to be responsible for this behavior. The blister skin thicknesses have been measured and correlated with calculated projected-range values.     

Ultralow concentrations of proenkephalin and [met5]-enkephalin differentially affect IgM and IgG production by B cells

Adenovirus-mediated gene transfer is a promising method for studies of vascular biology and potentially for gene therapy. Intravascular approaches for gene transfer to blood vessels in vivo generally require interruption of blood flow and have several limitations. We have used two alternative approaches for gene transfer to blood vessels in vivo using perivascular application of vectors. First, replication-deficient adenovirus expressing nuclear-targeted bacterial beta-galactosidase was injected into cerebrospinal fluid via the cisterna magna of rats. Leptomeningeal cells over the major arteries were efficiently transfected, and adventitial cells of large vessels and smooth muscle cells of small vessels were occasionally stained. When viral suspension was injected with the rat in a lateral position, the reporter gene was expressed extensively on the ipsilateral surface of the brain. Thus, adenovirus injected into cerebrospinal fluid provides gene transfer in vivo to cerebral blood vessels and, with greater efficiency, to perivascular tissue. Furthermore, positioning of the head may 'target' specific regions of the brain. Second, vascular gene delivery was accomplished by perivascular injection of virus in peripheral vessels. Injection of the adenoviral vector within the periarterial sheath of monkeys resulted in gene transfer to the vessel wall that was substantial in magnitude although limited to cells in the adventitia. Approximately 20% of adventitial cells expressed the transgene, with no gene transfer to cells in the intima or media. These approaches may provide alternative approaches for gene transfer to blood vessels, and may be useful for studies of vascular biology and perhaps vascular gene therapy.     

A call admission and control scheme for quality‐of‐service (QoS) provisioning in next generation wireless networks

We propose a framework for quality‐of‐service (QoS) provisioning for multimedia services in next generation wireless access networks. This framework aims at providing a differentiated treatment to multimedia traffic flows at the link layer, which can be broadly classified as real‐time (or delay‐sensitive) and non‐real‐time (or delay‐tolerant). Various novel schemes are proposed to support the differential treatment and guarantee QoS. These schemes include bandwidth compaction, channel reservation and degradation, with the help of which a call admission and control algorithm is developed. The performance of the proposed framework is captured through analytical modeling and simulation experiments. Analytically, the average carried traffic and the worst case buffer requirements for real‐time and non‐real‐time calls are estimated. Simulation results show up to 21% improvement in the admission probability of real‐time calls and up to 17% improvement in the admission probability of non‐real‐time calls, when various call control techniques like bandwidth compaction are employed. Using our channel reservation technique, we observe a 12% improvement in the call admission probability compared to another scheme proposed in the literature. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enhanced corrugated QWIP performance using dielectric coverage

We report here the effect of dielectric/metal coverage on the performance of the corrugated quantum well infrared photodetectors (C-QWIP) in two wavelength regimes. We found that with proper dielectrics, both the detector dark current and the spectral responsivity can he improved upon the monitoring 45° edge coupled QWIP. In the 8 μm regime, the normalized responsivity of a Si₃ N₄ covered C-QWIP was found to be improved by 3.3 times. In the 14 μm regime, the improvement is a factor of 1.8 using Si₃N₄ coverage and a factor of 2.5 using SiO₂ coverage