Dead Time Compensation for High-Flux Ranging

Dead time effects have been considered a major limitation for fast data acquisition in various time-correlated single photon counting applications, since a commonly adopted approach for dead time mitigation is to operate in the low-flux regime where dead time effects can be ignored. Through the application of lidar ranging, this work explores the empirical distribution of detection times in the presence of dead time and demonstrates that an accurate statistical model can result in reduced ranging error with shorter data acquisition time when operating in the high-flux regime. Specifically, we show that the empirical distribution of detection times converges to the stationary distribution of a Markov chain. Depth estimation can then be performed by passing the empirical distribution through a filter matched to the stationary distribution. Moreover, based on the Markov chain model, we formulate the recovery of arrival distribution from detection distribution as a nonlinear inverse problem and solve it via provably convergent mathematical optimization. By comparing per-detection Fisher information for depth estimation from high- and low-flux detection time distributions, we provide an analytical basis for possible improvement of ranging performance resulting from the presence of dead time. Finally, we demonstrate the effectiveness of our formulation and algorithm via simulations of lidar ranging.Comment: Revision with added estimation results, references, and figures, and modified appendice

SMART Infrastructure Dashboard: A Fusion between Business Intelligence and Geographic Information Systems

Abstract: Business Intelligence (BI) has popularly been adopted as a process that enables easy access, analysis and visualization of information through specialized set of tools for informed decision making. Two most noticeable characteristics of traditional BI is that it (a) is largely used in single-organization environments and (b) uses predominantly aspatial data. We believe that BI has applications beyond single-organization environments, but it very much requires integration of geospatial capabilities given the increasing availability of large volumes of spatial data and a growing interest to see things spatial. The SMART Infrastructure Dashboard (SID), our innovative solution that fuses BI and Geographic Information Systems (GIS), fills this significant gap. In this study, we demonstrate how SID can be used to perform spatio-temporal analysis and visualization of diverse sets of data to uncover complex interrelationships among utility usage, demographics and weather patterns at local and regional scale. Citation: Wickramasuriya, R., Ma, J., Somashekar, V., Perez, P. & Berryman, M. (2014). SMART Infrastructure Dashboard: A Fusion between Business Intelligence and Geographic Information Systems. In: Campbell P. and Perez P. (Eds), Proceedings of the International Symposium of Next Generation Infrastructure, 1-4 October 2013, SMART Infrastructure Facility, University of Wollongong, Australia

Capital account liberalization in China: the need for a balanced approach

This repository item contains a single issue of the Pardee Center Task Force Reports, a publication series that began publishing in 2009 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.This is the third report stemming from the Pardee Center Task Force on Regulating Capital Flows for Long-Run Development, a project of the Global Economic Governance Initiative (GEGI) at Boston University. This report is the collective work of experts examining the benefits and risks of accelerated capital account liberalization in China. The contributing authors – all leading scholars and practitioners from around the world (listed below) – met at Boston University in February 2014 to discuss the experiences of other emerging market countries that liberalized the capital account to glean lessons for China as it considers this delicate task. This volume is an outcome from that meeting, presenting the authors’ perspectives on important aspects of capital account liberalization that China should pay special attention to, not only for its own sake, but also in consideration of the potential impacts that China’s actions may have on other emerging markets and the global economy overall

miR-10a is aberrantly overexpressed in Nucleophosmin1 mutated acute myeloid leukaemia and its suppression induces cell death

<p>Abstract</p> <p>Background</p> <p>Acute myeloid leukaemia (AML) with nucleophosmin-1 (<it>NPM1</it>) mutation is a major subtype of AML. The <it>NPM1 </it>mutation induces a myeloproliferative disorder, but evidence indicates that other insults are necessary for the development of AML. We utilised microRNA microarrays and functional assays to determine if microRNA dysregulation could be involved in the pathogenesis of in <it>NPM1 </it>mutated (<it>NPM1^mut</it>)-AML.</p> <p>Results</p> <p>We used a stringent locked nucleic acid (LNA) based microRNA microarray platform to profile bone marrow samples of patients with normal karyotype AML. A panel of five microRNAs dichotomised AML patients according to their <it>NPM1 </it>mutational status. miR-10a, let-7b and let-7c were significantly over-expressed, while miR-130a and miR-335 were under-expressed in <it>NPM1^mut</it>-AML when compared to <it>NPM1^wildtype</it>-AML. Of these, miR-10a is the most differentially expressed in <it>NPM1^mut</it>-AML versus <it>NPM1^wildtype</it>-AML (> 10 fold higher as confirmed by qRT-PCR). To investigate the functions of miR-10a, the OCI-AML3 cell line was utilised, which is the only commercially available cell line bearing <it>NPM1^mut</it>. OCI-AML3 cells were firstly demonstrated to have a similarly high miR-10a expression to primary <it>NPM1^mut</it>-AML patient samples. Inhibition of miR-10a expression by miRCURY LNA Inhibitors (Exiqon) in these cells resulted in increased cell death as assessed by MTS, cell cycle and Annexin-V assays and reduced clonogenic capacity, indicative of an involvement in leukaemic cell survival. <it>In silico </it>filtering of bioinformatically predicted targets of miR-10a identified a number of potential mRNA targets with annotated functions in haematopoiesis, cell growth and apoptosis. Lucferase reporter assays confirmed a number of these putative tumorogenic genes that are miR-10a suppressible including <it>KLF4 </it>and <it>RB1CC1</it>. This provides a potential mechanism for the pathogenic role of miR-10a in <it>NPM1^mut</it>-AML.</p> <p>Conclusions</p> <p>This study provides, for the first time, <it>in vitro </it>evidence of a pro-survival role of miR-10a in <it>NPM1^mut</it>-AML, that it may contribute to the pathogenesis of <it>NPM1^mut</it>-AML and identifies putative tumorogenic targets.</p

High-flux single-photon lidar

In time-correlated single-photon counting (TCSPC), photons that arrive during the detector and timing electronics dead times are missed, causing distortion of the detection time distribution. Conventional wisdom holds that TCSPC should be performed with detections in fewer than 5% of illumination cycles to avoid substantial distortion. This requires attenuation and leads to longer acquisition times if the incident flux is too high. Through the example of ranging with a single-photon lidar system, this work demonstrates that accurately modeling the sequence of detection times as a Markov chain allows for measurements at much higher incident flux without attenuation. Our probabilistic model is validated by the close match between the limiting distribution of the Markov chain and both simulated and experimental data, so long as issues of calibration and afterpulsing are minimal. We propose an algorithm that corrects for the distortion in detection histograms caused by dead times without assumptions on the form of the transient light intensity. Our histogram correction yields substantially improved depth imaging performance, and modest additional improvement is achieved with a parametric model assuming a single depth per pixel. We show results for depth and flux estimation with up to 5 photoelectrons per illumination cycle on average, facilitating an increase in time efficiency of more than two orders of magnitude. The use of identical TCSPC equipment in other fields suggests that our modeling and histogram correction could likewise enable high-flux acquisitions in fluorescence lifetime microscopy or quantum optics applications.https://www.osapublishing.org/optica/fulltext.cfm?uri=optica-8-1-30&id=445715Published versio

Two-dimensional non-line-of-sight scene estimation from a single edge occluder

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Finding Your Mate at a Cocktail Party: Frequency Separation Promotes Auditory Stream Segregation of Concurrent Voices in Multi-Species Frog Choruses

Vocal communication in crowded social environments is a difficult problem for both humans and nonhuman animals. Yet many important social behaviors require listeners to detect, recognize, and discriminate among signals in a complex acoustic milieu comprising the overlapping signals of multiple individuals, often of multiple species. Humans exploit a relatively small number of acoustic cues to segregate overlapping voices (as well as other mixtures of concurrent sounds, like polyphonic music). By comparison, we know little about how nonhuman animals are adapted to solve similar communication problems. One important cue enabling source segregation in human speech communication is that of frequency separation between concurrent voices: differences in frequency promote perceptual segregation of overlapping voices into separate “auditory streams” that can be followed through time. In this study, we show that frequency separation (ΔF) also enables frogs to segregate concurrent vocalizations, such as those routinely encountered in mixed-species breeding choruses. We presented female gray treefrogs (Hyla chrysoscelis) with a pulsed target signal (simulating an attractive conspecific call) in the presence of a continuous stream of distractor pulses (simulating an overlapping, unattractive heterospecific call). When the ΔF between target and distractor was small (e.g., ≤3 semitones), females exhibited low levels of responsiveness, indicating a failure to recognize the target as an attractive signal when the distractor had a similar frequency. Subjects became increasingly more responsive to the target, as indicated by shorter latencies for phonotaxis, as the ΔF between target and distractor increased (e.g., ΔF = 6–12 semitones). These results support the conclusion that gray treefrogs, like humans, can exploit frequency separation as a perceptual cue to segregate concurrent voices in noisy social environments. The ability of these frogs to segregate concurrent voices based on frequency separation may involve ancient hearing mechanisms for source segregation shared with humans and other vertebrates

Dynamically evolving Mg II broad absorption line flow in SDSS J133356.02+001229.1

We report a dynamically evolving low ionization broad absorption line flow in the QSO SDSS J133356.02+001229.1 (at z_em = 0.9197). These observations are part of our ongoing monitoring of low ionization broad absorption line (BAL) QSOs with the 2m telescope at IUCAA Girawali observatory (IGO). The broad Mg II absorption with an ejection velocity of 1.7x10^4 km/s, found in the Sloan Digital Sky Survey (SDSS) spectra, has disappeared completely in our IGO spectra. We found an emerging new component at an ejection velocity of 2.8 x 10^4 km/s. During our monitoring period this component has shown strong evolution both in its velocity width and optical depth and nearly disappeared in our latest observations. Acceleration of a low velocity component seen in SDSS spectrum to a higher velocity is unlikely as the Mg II column densities are always observed to be higher for the new component. We argue that the observed variations may not be related to ionization changes and are consistent with absorption produced by multi-streaming flow transiting across our line of sight. We find a possible connection between flux variation of the QSO and N(Mg II) of the newly emerged component. This could mean the ejection being triggered by changes in the accretion disk or dust reddening due to the outflowing gas.Comment: 5 pages, 3 figures. Accepted for publication in the MNRAS letter