Flowing ConvNets for Human Pose Estimation in Videos

The objective of this work is human pose estimation in videos, where multiple frames are available. We investigate a ConvNet architecture that is able to benefit from temporal context by combining information across the multiple frames using optical flow. To this end we propose a network architecture with the following novelties: (i) a deeper network than previously investigated for regressing heatmaps; (ii) spatial fusion layers that learn an implicit spatial model; (iii) optical flow is used to align heatmap predictions from neighbouring frames; and (iv) a final parametric pooling layer which learns to combine the aligned heatmaps into a pooled confidence map. We show that this architecture outperforms a number of others, including one that uses optical flow solely at the input layers, one that regresses joint coordinates directly, and one that predicts heatmaps without spatial fusion. The new architecture outperforms the state of the art by a large margin on three video pose estimation datasets, including the very challenging Poses in the Wild dataset, and outperforms other deep methods that don't use a graphical model on the single-image FLIC benchmark (and also Chen & Yuille and Tompson et al. in the high precision region).Comment: ICCV'1

Superhumps in Low-Mass X-Ray Binaries

We propose a mechanism for the superhump modulations observed in optical photometry of at least two black hole X-ray transients (SXTs). As in extreme mass-ratio cataclysmic variables (CVs), superhumps are assumed to result from the presence of the 3:1 orbital resonance in the accretion disc. This causes the disc to become non-axisymmetric and precess. However the mechanism for superhump luminosity variations in low mass X-ray binaries (LMXBs) must differ from that in CVs, where it is attributed to a tidally-driven modulation of the disc's viscous dissipation, varying on the beat between the orbital and disc precession period. By contrast in LMXBs, tidal dissipation in the outer accretion disc is negligible: the optical emission is overwhelming dominated by reprocessing of intercepted central X-rays. Thus a different origin for the superhump modulation is required. Recent observations and numerical simulations indicate that in an extreme mass-ratio system the disc area changes on the superhump period. We deduce that the superhumps observed in SXTs arise from a modulation of the reprocessed flux by the changing area. Therefore, unlike the situation in CVs, where the superhump amplitude is inclination-independent, superhumps should be best seen in low-inclination LMXBs, whereas an orbital modulation from the heated face of the secondary star should be more prominent at high inclinations. Modulation at the disc precession period (10s of days) may indicate disc asymmetries such as warping. We comment on the orbital period determinations of LMXBs, and the possibility and significance of possible permanent superhump LMXBs.Comment: 6 pages, 1 encapsulated figure. MNRAS in press; replaced to correct typographical error

Tariff-Rate Quotas : Difficult to model or plain simple?

The difficulty of reliably and accurately incorporating tariffrate quotas (TRQs) into trade models has received a lot of attention in recent years. As a result of the Uruguay Round of GATT negotiations, TRQs replaced an assortment of tariff and nontariff instruments in an effort to standardise trade barriers, and facilitate their future liberalisation. Understanding the nuances of TRQs is now particularly crucial for New Zealand because of the preferential access arrangements that New Zealand has for a number of products in highly protected markets such as the European Union, Japan, and the United States. It has been argued that TRQs are complex instruments and are difficult to model because for any trade flow between two countries, one of three regimes may be applicable : 1. The import quota may not be binding and the within-quota tariff applies; 2. The quota may be binding, the within-quota tariff applies, and a quota rent is created; or 3. Trade occurs over and above the quota, in which case an over-quota tariff applies (although, even in this regime, someone is still able to collect the quota rent on within-quota trade). But even this characterisation, which many claim is too complex to model, is a major simplification of reality. Bilateral preferences are ubiquitous, and such preferences are usually included in the determination of multilateral market access quotas. It is usual, therefore, that the TRQ instrument has several tiers to the quota schedule, plus a number of within and over-quota tariff rates applicable on either a bilateral or a multilateral basis. Further trade liberalisation creates something of a dilemma for New Zealand. Any decrease in over-quota tariffs and/or increase in quota levels potentially reduces the value of quota rents, many of which accrue to New Zealand due to the bilateral preferences. It is important, therefore, that New Zealand trade negotiators understand how much additional trade is required to offset the loss of New Zealands quota rents. Modelling trade in the presence of TRQs is the only way to ascertain this knowledge. The purpose of this paper is to show that complex TRQs can be modelled very easily and precisely. The only catch is that the model must be formulated as a complementarity problem rather than the more conventional linear or nonlinear optimisation problem. The concept will be demonstrated using a simple 3-region, single commodity spatial price equilibrium model of trade.Tariff-rate quota, trade modelling, mathematical programming, complementarity

Derived Demand for Food Nutrients as Welfare Indicator of Biofortified Crops: High-Iron Rice in the Philippines

The study estimates potential consumer gains from the introduction of High-Iron Rice in the Philippines. By deriving the demand for dietary iron from a national survey on household food consumption and expenditure, we project consumer welfare implications under both non-market and market analytical frameworks.Crop Production/Industries,

A Spatiotemporal White Noise Analysis of Photoreceptor Responses to UV and Green Light in the Dragonfly Median Ocellus

Adult dragonflies augment their compound eyes with three simple eyes known as the dorsal ocelli. While the ocellar system is known to mediate stabilizing head reflexes during flight, the ability of the ocellar retina to dynamically resolve the environment is unknown. For the first time, we directly measured the angular sensitivities of the photoreceptors of the dragonfly median (middle) ocellus. We performed a second-order Wiener Kernel analysis of intracellular recordings of light-adapted photoreceptors. These were stimulated with one-dimensional horizontal or vertical patterns of concurrent UV and green light with different contrast levels and at different ambient temperatures. The photoreceptors were found to have anisotropic receptive fields with vertical and horizontal acceptance angles of 15° and 28°, respectively. The first-order (linear) temporal kernels contained significant undershoots whose amplitudes are invariant under changes in the contrast of the stimulus but significantly reduced at higher temperatures. The second-order kernels showed evidence of two distinct nonlinear components: a fast acting self-facilitation, which is dominant in the UV, followed by delayed self- and cross-inhibition of UV and green light responses. No facilitatory interactions between the UV and green light were found, indicating that facilitation of the green and UV responses occurs in isolated compartments. Inhibition between UV and green stimuli was present, indicating that inhibition occurs at a common point in the UV and green response pathways. We present a nonlinear cascade model (NLN) with initial stages consisting of separate UV and green pathways. Each pathway contains a fast facilitating nonlinearity coupled to a linear response. The linear response is described by an extended log-normal model, accounting for the phasic component. The final nonlinearity is composed of self-inhibition in the UV and green pathways and inhibition between these pathways. The model can largely predict the response of the photoreceptors to UV and green light

Healthcare provider adherence in prescribing antiplatelet therapy for patients with stroke symptoms within 48 hours upon arrival to hospital

Background: According to the Center of Disease Control, stroke accounted for 1 in every 6 cardiovascular-related deaths in the U.S in 2018. This disease is the leading cause of long-term disability and limits mobility in more than half of people who survive stroke older than 65 (Centers for Disease Control and Disease Prevention [CDC], 2020). Due to the difficulty of a full recovery for cerebral vascular accidents, stroke prevention is the top priority in the approach to reduce the mortality and morbidity of the disease. Antiplatelet platelet therapy has been proven to reduce the incidence and complications of an ischemic stroke. Context: A South Florida Hospital is less than excellent in initiating antiplatelet therapy for patients suspected of ischemic stroke. An educational intervention should be provided to healthcare providers to increase compliance to antiplatelet therapy for stroke patients. Purpose: The objective of the quality improvement project is to improve healthcare providers’ knowledge and compliance towards initiating antiplatelet therapy for patients admitted to the hospital with stroke symptoms. Methods: A sample of 13 healthcare providers was provided with a link from the medical director of an acute care hospital in South Florida via email. The link included the pre-test survey, education intervention PowerPoint, and post-test survey. The pre-and post- test measure of knowledge and practice habits related to treating patients with ischemic stroke. Results: There was an 8.9% improvement in scores on the knowledge-based questions in the post-test. Regarding the questions based on practice habits, post-test scores showed a 2% increase when compared to similar pre-test questions. Conclusions: Therefore, it was proven that the education intervention could improve the knowledge of healthcare providers related to increasing compliance for prescribing antiplatelet therapy for patients with stroke symptoms within 48 hours upon arrival to the hospital

Phloem loading and the control of solute transport in Ricinus communis L

This thesis presents the results of an investigation into the control of phloem loading in Ricinus commtinis L. The metabolic relationship between solute accumulation in the leaves and the longdistance transport pathways was first investigated to assess the significance of phloem-sap composition. The characteristics of phloem-sap exudation from bark incisions were then studied in terms of the osmotic properties of the transport system. Comparison of plant growth on a NO3- -N versus NH4+-N water-culture medium showed that there were marked differences in metabolism. Malate accumulation in the leaves of NO3- -N plants accounted for nearly 70% of the total anion balance, whereas malate levels were negligible in NH4+-N plants. However, the NH4+-N plants possessed much higher levels of organic N in the shoots. Despite these differences in solute accumulation, the organic C and organic N content of the phloem sap in the two groups of plants were very similar. Excess OH- (from the NO3- -N plants) and H+ (from the NH4+-N plants) generated during N assimilation in the roots was excreted to the root medium, but phloem transport did not constitute a quantitatively important mechanism for removal of excess OH- or H+ from the shoots. The differences in metabolism in these plants were considered in relation to control of intracellular pH during growth and solute accumulation. The bulk solute concentration of phloem sap exuding from bark incisions remained relatively constant over prolonged periods in plants maintained under controlled environmental conditions. Exudation rate increased immediately in response to fresh incisions, and these changes were directly related to alterations in solute flux. Calculation of the total capacity of the sieve tubes in the shoot indicated that prolonged exudation was maintained by phloem loading. Fully expanded leaves were the main sources of assimilates for transport. The kinetics of changes in exudation rate indicated that flow occurred through a low-resistance pathway and was influenced by the water relations of the vascular system. Solute flux through the phloem was found to increase when water deficits were imposed on the shoot, which suggested that loading was affected by changes in phloem turgor rather than sap concentration. Under conditions of continuous darkness, a rapid fall in sucrose levels in the phloem was associated with an increase in concentration. This tended partially to maintain phloem turgor, and implied that the mechanism of solute transfer into the tissue was directly involved in osmoregulation. The sites of phloem loading in source leaves were examined by transmission electron microscopy, and the sieve element-companion cell complex was typical of that found in other species. Multiple branched plasmodesmata were associated with wall swellings in this cell junction; they may have served to allow high rates of symplastic transport into the sieve tubes. The osmotic characteristics of sucrose loading were also studied using a leaf-disc system. The results suggested that phloem turgor rather than total water potential affected solute uptake, but the system has a limited bearing on the question of solute loading in the intact plant. The manner in which the solute content of the phloem is controlled supports the concept that the sap constitutes a symplastic phase. In addition, the effects of changes in the osmotic relations of the phloem on solute flux suggested that loading was turgor-pressure dependent. It is proposed that this may represent the mechanism by which phloem transport responds to alterations in the source-sink balance in intact plants

Control of electron, ion and neutral heating in a radio-frequency electrothermal microthruster via dual-frequency voltage waveforms

The development of low power micro-propulsion sources is of recent interest for application on miniature satellite platforms. Radio-frequency. (rf) plasma electrothermal microthrusters can operate without a space-charge neutralizer and provide increased control of spatiotemporal power deposition. Further understanding of how the phase-resolved rf plasma heating mechanisms affect the phase-averaged bulk plasma properties, e.g. neutral gas temperature, could allow for in-flight tailoring of plasma thrusters. In this work, experimentally validated two-dimensional fluid-kinetic simulations were employed to study the spatially resolved electron and ion power deposition and neutral gas heating in a dual-frequency rf electrothermal microthruster operating at 1.5. Torr plenum pressure in argon. Experimental validation was performed through a comparison of the measured and simulated phase resolved Ar(2p(1)) excitation rates, showing close agreement. Two types of dual-frequency voltage waveforms were investigated, and comprise the combination of a 13.56 MHz voltage waveform with 27.12 MHz and 40.68 MHz waveforms, respectively. Varying the phase offset of the higher harmonic relative to the fundamental 13.56. MHz voltage waveform was found to modulate the dc self-bias voltage by 11% and 3% of the maximum applied peak-to-peak voltage, respectively. The 13.56. MHz, 27.12. MHz dual-frequency voltage waveform provided the highest degree of control, where the fraction of total rf power deposited into Ar+ ions was found to vary from 57% to 77%, modulating the on-axis neutral gas temperature by 35%. This control is attributed to the variation in the fraction of the rf phase cycle for which the sheath is collapsed, altering the phase-averaged electric field strength adjacent to the radial wall. The application of dual-frequency waveforms provides the ability to optimize the particle heating mechanisms with application to electrothermal propulsion.The work presented herein was funded by the Engineering and Physical Sciences Research Council (EPSRC, EP/M508196/1)