Design and characterization of ultra high frame rate burst image sensors

This thesis research was aimed at investigating and designing novel architectures required for ultra high frame rate (UHFR) imagers capable of operating at frame rates in excess of 106 frames/sec. To demonstrate the feasibility of these architectures, a 180 x 180 element UHFR-I imager was designed and fabricated. The imager chip stored the latest 32 frames at its on-chip memory locations rather than performing a continuous readout. It was demonstrated that this architecture approach could achieve a frame acquisition rate of 2 x 106 frames/sec. Additionally, other novel design features were incorporated to minimize optical cross talk and output amplifier noise, and maximize charge handling capacity. Two-dimensional (2-D) process and device simulations were performed to optimize optical cross talk and results compared favorably with experimental data of the fabricated chip. This tested imager was fabricated at the research laboratory of Sarnoff Corporation and had 4-levels of polysilicon, 3-levels of metal, eight implants and 21 photo mask levels. Simulations were also performed to characterize optical cross talk as a function of wavelength, optical shield aperture and epi-substrate doping. The measured value of optical cross talk was at least a factor of 40 times lower and maximum frame rate was a factor of 4 higher than previously published results for very high frame rate (VHFR) imager. The experimental results were used to design a new 64 x 64 element UHFR-II imager with an architecture capable of an image capture rate of 107 frames/sec. This architecture requires only 3-levels of polysilicon and 2-levels of metal and stores the latest 12 frames at its on-chip memory locations. Simulation results indicate that a frame rate of 107 frames/sec can certainly be obtained

Gallium nitride nanoparticles for solar-blind detectors

We investigate the properties of GaN semiconducting nanoparticles as a potential candidate for photodetection in the solar- blind region. The photocurrent spectral response is studied spanning the range 1·6-5·5 eV. A significant fraction of the response is in the range 4-5·5 eV. The results are compared to other optical properties and the origins of the features observed in the spectra are speculated upon

Arrested States formed on Quenching Spin Chains with Competing Interactions and Conserved Dynamics

We study the effects of rapidly cooling to T = 0 a spin chain with conserved dynamics and competing interactions. Depending on the degree of competition, the system is found to get arrested in different kinds of metastable states. The most interesting of these has an inhomogeneous mixture of interspersed active and quiescent regions. In this state, the steady-state autocorrelation function decays as a stretched exponential $\sim \exp(-{(t/\tau_{o})}^{{1}\over{3}})$, and there is a two-step relaxation to equilibrium when the temperature is raised slightly.Comment: 4 pages, Latex, 3 postscript figures. Phys. Rev. E to appear (1999

Bronchodilatory effect of inhaled budesonide/formoterol and budesonide/salbutamol in acute asthma: a double-blind, randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>There are no published studies that have compared bronchodilatory effect of inhaled budesonide/formoterol combination with budesonide/salbutamol delivered by metered dose inhaler with a spacer in acute exacerbation of asthma in children. We, therefore, compared the bronchodilatory effects of inhaled budesonide/formoterol (dose: 200 μg and 12 μg respectively) combination with budesonide (200 μg)/salbutamol (200 μg) administered by metered dose inhaler and spacer in children of 5-15 years with mild acute exacerbation of asthma [Modified Pulmonary Index Score (MPIS) between 6-8] in this double-blind, randomized controlled trial. The primary outcome was FEV1 (% predicted) in the two groups at 1, 5, 15, 30, 60 min after administration of the study drug.</p> <p>Results</p> <p>We did not observe any significant differences in the % predicted FEV1 and MPIS between formoterol and salbutamol at various time points from 1 min to 60 min post drug administration. There was significant improvement in FEV1 (% predicted) from baseline in both the groups as early as 1 min after drug administration.</p> <p>Conclusions</p> <p>Salbutamol or formoterol delivered along with inhaled corticosteroid by metered dose inhaler with spacer in children between 5-15 years of age with mild acute exacerbation of asthma had similar bronchodilatory effects.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00900874">NCT00900874</a></p

A rare case of vulval leiomyoma

Vulval leiomyomas are rare smooth muscle tumors that may arise from smooth muscle cells within erectile tissue, blood vessel wall or round ligament remnants in the labia majora and they are clinically misdiagnosed as Bartholin cyst or lipoma. In our case, a 40-year-old woman presented with 8 years history of progressively increasing painless swelling on her vulva. Clinically it was diagnosed as a solid tumour due to its consistency and location. Hence surgical excision was done. Histopathology report was suggestive of leiomyoma with hyaline changes on microscopy. Major diagnostic problem with smooth muscle tumors of the vulva is the distinction between benign and malignant form, since many vulval lesions have similar appearances making it difficult to distinguish benign from malignant lesions by gross inspection. The recommended treatment option is local excision of the mass with pathological examination

Second trimester termination of pregnancy with misoprostol alone and misoprostol with isosorbide mononitrate: a comparative study

Background: Aim of the study was to compare the efficacy of misoprostol   alone and misoprostol with isosorbide mononitrate in reducing the induction abortion time interval in second trimester termination of pregnancy.Methods: A randomized control prospective study was conducted. Patients seeking second trimester abortions were randomized in to two groups. Group A received 400 ugm of misoprostol per vaginum every 4 hours up to maximum of 5 doses. Group B patients received 400 ugm of misoprostol and 40mg of isosorbide nitrate intravaginally. Repeat dose of 400 ugm misoprostol and 20 mg of isosorbide mononitrate was given every 4 hours up to a maximum of 5 doses. The induction to abortion interval and side effects of the drugs used were noted.Results: A total 71 women seeking second trimester termination between 12 to 20 weeks gestation were recruited for the study. In group A, there were 36 patients and in group B there were 35 patients. In group A the mean induction abortion interval was 14.8±4.16 hours while in group B the mean induction-abortion interval was 12.45±3.9 hours. Patients treated with isosorbide mononitrate and misoprostol combination had statistically significantly lower induction abortion time interval when compared with misoprostol alone (p value 0.018).Conclusions: The study demonstrates that the combination of isosorbide mononitrate and misoprostol is more effective for termination of second trimester pregnancy than misoprostol alone.

Concurrent infections by all four dengue virus serotypes during an outbreak of dengue in 2006 in Delhi, India

<p>Abstract</p> <p>Background</p> <p>Co-circulation of multiple dengue virus serotypes has been reported from many parts of the world including India, however concurrent infection with more than one serotype of dengue viruses in the same individual is rarely documented. An outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) occurred in and around Delhi in 2006. This is the first report from India with high percentage of concurrent infections with different dengue virus serotypes circulating during one outbreak.</p> <p>Results</p> <p>Acute phase sera from patients were tested for the presence of dengue virus RNA by RT-PCR assay. Of the 69 samples tested for dengue virus RNA, 48 (69.5%) were found to be positive. All the four dengue virus serotypes were found to be co-circulating in this outbreak with DENV-3 being the predominant serotype. In addition in 9 of 48 (19%) dengue virus positive samples, concurrent infection with more than one dengue virus serotype were identified.</p> <p>Conclusion</p> <p>This is the first report in which concurrent infections with different dengue virus serotypes is being reported during an outbreak from India. Delhi is now truly hyperendemic for dengue.</p