Comparison of pentacene and amorphous silicon AMOLED display driver circuits

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Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Efficient micro-Power Management for Solar Cells with Time Domain Array Reconfiguration

The goal of this dissertation is to demonstrate improvements to micro-power solar energy harvesting with a scalable approach. The improvements are demonstrated through a microchip designed to harvest energy optimally from a miniature, partially shaded Photovoltaic (PV) array with an adaptive, light weight, high efficiency power converter. The power converter dynamically reconfigures the array to operate each cell at its individual maximum power point using a new technique termed 'time-domain array-reconfiguration' (TDAR) to extract maximum energy from the miniature PV array. Directly harnessed solar power is an attractive primary energy source for integration into fully wire-free, self-sufficient, portable electronic devices. Photovoltaic cells are most efficient at harvesting when operated at a particular voltage and current, termed ‘maximum power point’. Density of harvested energy increases and cost per watt decreases when PV cells are operated efficiently, requiring dedicated PV management electronics. For both high power and portable applications, arraying PV cells increases voltage and current output. However, simply connecting PV cells in parallel or series leads to inefficient topologies where the weakest cell limits the output capacity of the array. The research challenge in PV power systems is thus to develop better power management techniques to boost PV efficiency. Portable PV arrays are small, low voltage, and subject to varying illumination and mechanical stress. Due to the additional constraints on portable systems, efficient PV management for portable and low-power systems presents a significant design challenge. This work addresses technical challenges of micro-power array management in the context of a portable sensor aimed at 1 gram system weight and 100 micro-watt average power. Energy is stored in a Lithium-polymer battery. Only 2-3 PV cells are available, and illumination is expected to vary quickly. The system is thus designed to efficiently boost PV voltage to charge the 3.7V-4.1V battery while tracking individual PV maximum power points, and keeping power components under 0.5 grams. Efficient analog power tracking and TDAR are leveraged to meet these significant design challenges, and constitute the contribution to the state of art.NSF grant DMR 012096

Screening of Marketed Formulations of Shatavari Tablets to Establish Pharmaceutical Equivalence

Using an in vitro dissolving research, compare the pharmacological equivalent of three brands of Shatavari tablets sold in India. According to IP rules, the dissolution was performed using apparatus I (the paddle device). According to the Indian Pharmacopoeia, evaluation of physicochemical characteristics including weight variation test, content uniformity test, hardness test, friability test, disintegration test, and dissolution test was conducted. For weight fluctuation, content homogeneity, hardness, friability, disintegration time, and dissolving study, all brands complied with official specifications. Two out of the three brands of Shatavari tablets achieved more than 75% dissolve in just 60 minutes, according to the dissolution profile. Out of three brands of Shatavari tablets, the results indicated that two of them had satisfactory quality and had passed all of the pharmacopoeia's tests. Keywords: Asparagus racemosus, pharmaceutical equivalence, in vitro dissolution