External fluctuations in front dynamics with inertia: The overdamped limit

We study the dynamics of fronts when both inertial effects and external fluctuations are taken into account. Stochastic fluctuations are introduced as multiplicative noise arising from a control parameter of the system. Contrary to the non-inertial (overdamped) case, we find that important features of the system, such as the velocity selection picture, are not modified by the noise. We then compute the overdamped limit of the underdamped dynamics in a more careful way, finding that it does not exhibit any effect of noise either. Our result poses the question as to whether or not external noise sources can be measured in physical systems of this kind.Comment: 4 pages, 1 figure, accepted for publication in European Physical Journal

Genomic and toxigenic heterogeneity of bacillus cereus sensu lato Isolated from ready-to-eat foods and powdered milk in day care centers in Colombia

Bacillus cereus sensu lato (s.l.) is a group of bacteria commonly found in diverse environments, including foods, with potential to cause emesis and diarrhea. In Colombia, it is one of the main foodborne pathogens. The aim of this study was to determine the genomic and toxigenic heterogeneity of B. cereus s.l. isolated from ready-to-eat foods and powdered milk collected in day care centers of Medellin, Colombia. Of 112 B. cereus s.l. isolates obtained, 94% were beta-hemolytic. Toxigenic heterogeneity was established by the presence of nheABC, hblCDAB, cytK2, entFM, and cesB toxigenic genes. The nheABC operon and entFM gene were most frequently detected in the isolates, whereas the cesB gene was not found. According to the toxin genes content, nine toxigenic profiles were identified. A 44% of isolates had profiles with all genes for nonhemolytic enterotoxin, hemolysin BL, and enterotoxin FM production (profiles II and IV). Pulsed-field gel electrophoresis analysis indicated a high genomic heterogeneity among the B. cereus s.l., with 68 isolates grouping into 16 clusters and 33 placed separately in the dendrogram. This study provides useful information on the safety of ready-to-eat foods and powdered milk in day care centers where children, a susceptible population, are exposed and it should incentive for more studies to understand the distribution of different toxin-encoding genes among B. cereus s.l. isolates, enabling detailed risk assessment

Pancreatic Necrosectomy Through a Novel Double-flange Lumen-apposing Covered Metal Stent (Video)

AbstractPancreatic fluid collections (PFCs) represent a complication of acute pancreatitis. Endoscopic management of PFCs is an alternative to surgery [1]. Classic strategies include access to the collection under endoscopic ultrasound (EUS)-guidance and placement of several double-pigtail stents. PFCs containing organized necrosis are classified as walled-off necrosis (WON). In those cases necrosis is hardly evacuated and will require necrosectomy in most cases. Every necrosectomy session needs prior removal of the stents, dilatation of the tract, debridement and placement of new stents adding up a considerable overall cost to the intervention. A novel double-flanged lumen-apposing fully-covered self-expandable metal stent (FC-SEMS) with a 15mm diameter accelerates exit of the necrosis and facilitates multiple necrosectomy sessions.We present a 60 year old patient admitted to the intensive care unit for severe acute pancreatitis that developed WON with superinfection. The intensivists and surgeons indicated endoscopic cystgastrostomy to evacuate the collection. Using the echoendoscope we found a large collection adherent to the gastric wall. The collection was accessed under EUS-guidance using the Hot AXIOS™ catheter that features a cautery tip, then a 15mm AXIOS™ stent was deployed through the cystgastrostomy orifice to keep it patent. The patient required two necrosectomy sessions to clean the cavity. The WON resolved in 6 weeks and the stent was removed unevently. The patient was discharged.A double flange lumen apposing FC-SEMS used as a port for necrosectomy significantly improves management of walled-off pancreatic necrosis. Placement of this stents should be considered when multiple necrosectomy sessions are anticipated. Procedure time can be significantly decreased using a catheter that combines a cautery tip and stent delivery system

Virtual Instruments in Dimensional Metrology

During the last five years, in order to improve understanding of content related to "Coordinate Metrology", the Laboratorio de Metrología y Metrotecnia (LMM) from the Polytechnic University of Madrid offers its PhD students, as a course work, the construction of a virtual instrument. This virtual instrument simulates the imaging of a part to be measured by optical dimensional metrology instruments (microscopes, profile projectors, vision machines). The LMM provides students with images similar to those they would obtain with real instrumentation for the instrument adjustment and calibration process. Working with these images, students should determine the adjustment parameters of the virtual instrument. Once these parameters are set, the student can perform the proper calibration of the virtual instrument. Beyond this process, the instrument is already able to perform traceable measurement. In order to do that, LMM offers students some images of parts. Students should perform some measurements using those images and estimate the corresponding uncertainties

Effective potential at finite temperature in a constant hypermagnetic field: Ring diagrams in the Standard Model

We study the symmetry breaking phenomenon in the standard model during the electroweak phase transition in the presence of a constant hypermagnetic field. We compute the finite temperature effective potential up to the contribution of ring diagrams in the weak field, high temperature limit and show that under these conditions, the phase transition becomes stronger first order.Comment: 15 pages, 8 Postscript figure

Evaluation of the different numerical formats for HIL models of power converters after the adoption of VHDL-2008 by xilinx

Hardware in the loop is a widely used technique in power electronics, allowing to test and debug in real time (RT) at a low cost. In this context, field-programmable gate arrays (FPGAs) play an important role due to the high-speed requirements of RT simulations, in which area optimization is also crucial. Both characteristics, area and speed, are affected by the numerical formats (NFs) and their rounding modes. Regarding FPGAs, Xilinx is one of the largest manufacturers in the world, offering Vivado as its main design suite, but it was not until the release of Vivado 2020.2 that support for the IEEE NF libraries of VHDL-2008 was included. This work presents an exhaustive evaluation of the performance of Vivado 2020.2 in terms of area and speed using the native IEEE libraries of VHDL-2008 regarding NF. Results show that even though fixed-point NFs optimize area and speed, if a user prefers the use of floating-point NFs, with this new release, it can be synthesized—which could not be done in previous versions of Vivado. Although support for the native IEEE libraries of VHDL-2008 was included in Vivado 2020.2, it still lacks some issues regarding NF conversion during synthesis while support for simulation is not yet includedThis research received no external fundin