PCA-RECT: An Energy-efficient Object Detection Approach for Event Cameras

We present the first purely event-based, energy-efficient approach for object detection and categorization using an event camera. Compared to traditional frame-based cameras, choosing event cameras results in high temporal resolution (order of microseconds), low power consumption (few hundred mW) and wide dynamic range (120 dB) as attractive properties. However, event-based object recognition systems are far behind their frame-based counterparts in terms of accuracy. To this end, this paper presents an event-based feature extraction method devised by accumulating local activity across the image frame and then applying principal component analysis (PCA) to the normalized neighborhood region. Subsequently, we propose a backtracking-free k-d tree mechanism for efficient feature matching by taking advantage of the low-dimensionality of the feature representation. Additionally, the proposed k-d tree mechanism allows for feature selection to obtain a lower-dimensional dictionary representation when hardware resources are limited to implement dimensionality reduction. Consequently, the proposed system can be realized on a field-programmable gate array (FPGA) device leading to high performance over resource ratio. The proposed system is tested on real-world event-based datasets for object categorization, showing superior classification performance and relevance to state-of-the-art algorithms. Additionally, we verified the object detection method and real-time FPGA performance in lab settings under non-controlled illumination conditions with limited training data and ground truth annotations.Comment: Accepted in ACCV 2018 Workshops, to appea

Applying neuromorphic vision sensors to planetary landing tasks

Recently there has been an increasing interest in application of bio-mimetic controller s and neuromorphic vision sensor s to planetary landing tasks. Within this context, we present combined low-level (SPICE) and high-level (behavioral) simulations of a novel neuromorphic VLSI vision sensor in a realistic planetary landing scenar io. We use results from low level simulations to build an abstr act descr iption of the chip which can be used in higher level simulations which include closed-loop control of the cr aft

Static stretching of the hamstring muscle for injury prevention in football codes: a systematic review

Purpose: Hamstring injuries are common among football players. There is still disagreement regarding prevention. The aim of this review is to determine whether static stretching reduces hamstring injuries in football codes. Methods: A systematic literature search was conducted on the online databases PubMed, PEDro, Cochrane, Web of Science, Bisp and Clinical Trial register. Study results were presented descriptively and the quality of the studies assessed were based on Cochrane’s ‘risk of bias’ tool. Results: The review identified 35 studies, including four analysis studies. These studies show deficiencies in the quality of study designs. Conclusion: The study protocols are varied in terms of the length of intervention and follow-up. No RCT studies are available, however, RCT studies should be conducted in the near future

BB-CLIPS: Blackboard extensions to CLIPS

This paper describes a set of extensions made to CLIPS version 4.3 that provide capabilities similar to the blackboard control architecture described by Hayes-Roth. There are three types of additions made to the CLIPS shell. The first extends the syntax to allow the specification of blackboard locations for CLIPS facts. The second implements changes in CLIPS rules and the agenda manager that provide some of the powerful features of the blackboard control architecture. These additions provide dynamic prioritization of rules on the agenda allowing control strategies to be implemented that respond to the changing goals of the system. The final category of changes support the needs of continuous systems, including the ability for CLIPS to continue execution with an empty agenda

A Path Integral for the Chiral-Form Partition Function

38 pages; v2: minor correctionsStarting from the recent action proposed by Sen [1,2], we evaluate the partition function of the compact chiral boson on a two-dimensional torus using a path-integral formulation. Crucially, we use a Wick-rotation procedure obtained from a complex deformation of the physical spacetime metric. This directly reproduces the expected result including general characteristics for the theta functions. We also present results for the chiral 2-form potential in six dimensions which can be readily extended to 4k+2 dimensions

Elevated cerebral spinal fluid biomarkers in children with mucopolysaccharidosis I-H.

Mucopolysaccharidosis (MPS) type-IH is a lysosomal storage disease that results from mutations in the IDUA gene causing the accumulation of glycosaminoglycans (GAGs). Historically, children with the severe phenotype, MPS-IH (Hurler syndrome) develop progressive neurodegeneration with death in the first decade due to cardio-pulmonary complications. New data suggest that inflammation may play a role in MPS pathophysiology. To date there is almost no information on the pathophysiologic changes within the cerebral spinal fluid (CSF) of these patients. We evaluated the CSF of 25 consecutive patients with MPS-IH. While CSF glucose and total protein were within the normal range, we found a significantly mean elevated CSF opening pressure at 24 cm H2O (range 14-37 cm H2O). We observed a 3-fold elevation in CSF heparan sulfate and a 3-8 fold increase in MPS-IH specific non-reducing ends, I0S0 and I0S6. Cytokine analyses in CSF of children with MPS-IH showed significantly elevated inflammatory markers including: MCP-1 SDF-1a, IL-Ra, MIP-1b, IL-8, and VEGF in comparison to unaffected children. This is the largest report of CSF characteristics in children with MPS-IH. Identification of key biomarkers may provide further insight into the inflammatory-mediated mechanisms related to MPS diseases and perhaps lead to improved targeted therapies

Biochemical and clinical response after umbilical cord blood transplant in a boy with early childhood-onset beta-mannosidosis.

BACKGROUND: Deficiency in the enzyme β-mannosidase was described over three decades ago. Although rare in occurrence, the presentation of childhood-onset β-mannosidase deficiency consists of hypotonia in the newborn period followed by global development delay, behavior problems, and intellectual disability. No effective pharmacologic treatments have been available. METHODS: We report 2-year outcomes following the first umbilical cord blood transplant in a 4-year-old boy with early childhood-onset disease. RESULTS: We show restoration of leukocyte β-mannosidase activity which remained normal at 2 years posttransplant, and a simultaneous increase in plasma β-mannosidase activity and dramatic decrease in urine-free oligosaccharides were also observed. MRI of the brain remained stable. Neurocognitive evaluation revealed test point gains, although the magnitude of improvement was less than expected for age, causing lower IQ scores that represent a wider developmental gap between the patient and unaffected peers. CONCLUSION: Our findings suggest that hematopoietic cell transplant can correct the biochemical defect in β-mannosidosis, although preservation of the neurocognitive trajectory may be a challenge

Acidosis slows electrical conduction through the atrio-ventricular node

Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis

Spatial and temporal variations of water and nutrient fluxes within a steep-sloped agricultural catchment.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.A proper understanding of the spatial and temporal variations of runoff and nutrient fluxes are critical in understanding catchment hydrology. Runoff and nutrient fluxes may exhibit large variations both spatially and temporally, but this issue has largely been overlooked in the existing literature. The present study intends to respond to two main research objectives: (a) improve the understanding of the spatial and temporal variations (i.e. the dynamics) of overland flow (OF) and its factors of control and (b) quantify the evolution of runoff, nutrient and sediment fluxes from hillslope crest to catchment outlet. The research study was undertaken in a 1000 ha agricultural catchment of the Drakensberg foothills in the Bergville District, KwaZulu-Natal, South Africa under rangeland, small scale agriculture and commercial agriculture. The first objective was to evaluate the dynamics of OF during four rainfall seasons (2007 to 2011) by using 1×1m² microplots (n=15) located at five landscape positions within the rangeland upper part of the catchment. Automatic tipping buckets linked to a datalogger were used to estimate the delay between the start of the rain and the start of OF, which corresponded to the time of runoff initiation (TRI). Multivariate analysis was applied to the OF data and the information on selected environmental factors (rainfall characteristics, selected soil physical properties, soil water content and soil surface conditions). Nested scales of 1 and 10 m2 plots, and 23, 100 and 1000 ha catchments equipped with buckets for plots and conventional H-flumes for catchments, were used to quantify the downstream evolution of water and nutrient (C, NO3 - and P) fluxes. The fluxes were compared with data from the shallow and deep groundwater (GW) collected from piezometers and boreholes, respectively. This allowed for the determination of the mixing sources at the three catchment outlets, using stable isotopes of water (to differentiate between old and new water) and silica concentrations to identify soil water (SW) contributions. The average OF rate varied 2.3-fold across the Potshini Catchment (from 15% footslope to 35% backslope), while the average TRI varied by a 10.6-fold factor (between 0.6 minutes in the bottomland and 6.4 minutes at the footslope position). TRI temporal variations correlated the most with the duration of rainfall (Pearson r coefficient of 0.8) and the cumulative amount of rainfall after the onset of the rainy season (r=-0.47), while TRI spatial variations were significantly controlled by soil crusting (-0.97<r<-0.77). Water fluxes were found to increase iii from the microplot scale (208 l/m2) to the runoff plot scale (350 l/m2, delivery ratio of 1.68). The scale ratios calculated for the period of 2010-2011 show that there was a steady decrease in the delivery of water from the hillslope scale to the catchment scale. Cumulative water fluxes were found to be 316 l/m2 at the 23 ha catchment and 284 l/m2 at the 100 ha catchment (delivery ratios of 0.90 and 0.89 respectively). Water fluxes decreased sharply to 198 l/m2 at the 1000 ha catchment outlets (delivery ratio of 0.70). Runoff at the 23 ha catchment outlet was sourced from the mixing of GW (average of 63%), OF (22%) and SW (15%.) At the 100 ha outlet, GW contributions decreased to 50%, while OF contributions remained constant at 22% and SW contributions increased to 28%. The main contributor at the 1000 ha catchment was GW (55%) followed by SW (37%) and OF (8%). During the strongest rainfall event of the study period, OF contributed 97% to total runoff at the 23 ha catchment outlet, whilst at the 100 ha catchment, OF and SW both contributed 50% each. Groundwater in all cases was the major contributor to runoff at the 1000 ha catchment outlet. Both dissolved organic Carbon (DOC) and particulate organic Carbon (POC) increased from the microplot (8.44 and 25.51 g/m2 for DOC and POC) to the plot scale (14.92 and 26.91 g/m2). Lower yields occurred at the 23 ha catchment than on the hillslope (5.03 g/m2 and 8.18 g/m2). From the 23 and 100 ha catchment outlets, POC sharply decreased to 0.06 g/m2, while DOC increased considerably to 9.58 g/m2. This pointed to the decomposition of POC, which not only releases CO2 to the atmosphere but also adds DOC to runoff. At the 1000 ha catchment, POC yields were minimal due to a lack of eroded sediments whilst DOC decreased slightly (6.42 g/m2). These results yield a better understanding of the processes of water, nutrient and Carbon movements within landscapes. A further understanding of the processes leading to changes of nutrient and carbon fluxes needs to be performed in order to link this study with the overall ecosystem functioning of a landscape

Electrophysiological properties of myocytes isolated from the mouse atrioventricular node:L-type ICa, IKr, If, and Na-Ca exchange

The atrioventricular node (AVN) is a key component of the cardiac pacemaker-conduction system. This study investigated the electrophysiology of cells isolated from the AVN region of adult mouse hearts, and compared murine ionic current magnitude with that of cells from the more extensively studied rabbit AVN. Whole-cell patch-clamp recordings of ionic currents, and perforated-patch recordings of action potentials (APs), were made at 35–37°C. Hyperpolarizing voltage commands from −40 mV elicited a Ba(2+)-sensitive inward rectifier current that was small at diastolic potentials. Some cells (Type 1; 33.4 ± 2.2 pF; n = 19) lacked the pacemaker current, I(f), whilst others (Type 2; 34.2 ± 1.5 pF; n = 21) exhibited a clear I(f), which was larger than in rabbit AVN cells. On depolarization from −40 mV L-type Ca(2+) current, I(C)(a,L), was elicited with a half maximal activation voltage (V(0.5)) of −7.6 ± 1.2 mV (n = 24). I(C)(a,L) density was smaller than in rabbit AVN cells. Rapid delayed rectifier (I(K)(r)) tail currents sensitive to E-4031 (5 μmol/L) were observed on repolarization to −40 mV, with an activation V(0.5) of −10.7 ± 4.7 mV (n = 8). The I(K)(r) magnitude was similar in mouse and rabbit AVN. Under Na-Ca exchange selective conditions, mouse AVN cells exhibited 5 mmol/L Ni-sensitive exchange current that was inwardly directed negative to the holding potential (−40 mV). Spontaneous APs (5.2 ± 0.5 sec(−1); n = 6) exhibited an upstroke velocity of 37.7 ± 16.2 V/s and ceased following inhibition of sarcoplasmic reticulum Ca(2+) release by 1 μmol/L ryanodine, implicating intracellular Ca(2+) cycling in murine AVN cell electrogenesis