Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

The effect of acute maternal hypoglycaemia on fetal cardiovascular control

Aims: To investigate the effect of acute maternal hypoglycaemia on fetal cardiovascular (CV) function, as a sub-optimal environment in utero has been implicated in the development of CV disease in adult life.Subjects: Fetal sheep (n = 7) were studied in utero at 125 and 126 days gestational age (dGA, term = 147 days) following implantation of vascular catheters and an umbilical cord occluder at 119 dGA.Study design: Fetal CV parameters were measured during a maternal saline (day 125) and insulin (day 125) infusion. Fetal CV function was assessed by: (a) generating a dose response curve to angiotensin II; (b) a 90 sec total umbilical cord occlusion; (c) administration of phenylephrine to assess baroreflex function.Outcome measures: (a) Area under the mean arterial blood pressure (MAP) response (AUC) to increasing doses of angiotensin II; (b) MAP and heart rate (HR) response to cord occlusion; (c) sensitivity and operating point of the baroreflex response. Results: Maternal insulin infusion resulted in maternal and fetal hypoglycaemia. (a) The angiotensin II MAP AUC was not affected by hypoglycaemia. (b) The increase in MAP and decrease in HR following a 90 sec cord occlusion was not affected by hypoglycaemia. (c) Hypoglycaemia resulted in reduced fetal baroreflex sensitivity (P <0.05, paired t test).Conclusions: Our finding of reduced fetal baroreflex sensitivity during fetal hypoglycaemia indicates altered CV homeostatic mechanisms. Such fetal adaptations to a poor intrauterine environment could contribute towards the development of altered cardiovascular phenotype in adult life