250 research outputs found
Trajectory Analysis for Sport and Video Surveillance
In video surveillance and sports analysis applications, object trajectories offer the possibility of extracting rich information on the underlying behavior of the moving targets. To this end we introduce an extension of Point Distribution Models (PDM) to analyze the object motion in their spatial, temporal and spatiotemporal dimensions. These trajectory models represent object paths as an average trajectory and a set of deformation modes, in the spatial, temporal and spatiotemporal domains. Thus any given motion can be expressed in terms of its modes, which in turn can be ascribed to a particular behavior. The proposed analysis tool has been tested on motion data extracted from a vision system that was tracking radio-guided cars running inside a circuit. This affords an easier interpretation of results, because the shortest lap provides a reference behavior. Besides showing an actual analysis we discuss how to normalize trajectories to have a meaningful analysis
Does regretting first vaginal intercourse have an effect on young adults' sexual behaviour?
Background The aims of this research were to determine personal differences depending on the reason for regretting or not first vaginal intercourse and its effects on sexual behaviour later on among young adults, and to assess the association between reasons for engaging in first vaginal intercourse and regretting it.
Data were drawn from the 2017 Swiss national survey on youth sexual behaviours among young adults (mean age 26 years) living in Switzerland. Out of the 7142 participants, 4793 (51% females) answered the question 'Looking back now to the first time you had vaginal intercourse, do you think that…' with five possible answers: (1) I should not have done it (6.7%); (2) I should have waited longer (7.7%); (3) I should have done it earlier (7.4%); (4) It was about the right time (67.9%); and (5) I don't know (10.3%). The five groups were compared on sociodemographic and sex behaviour-related variables, analysed separately by gender.
One-third of participants regretted their first experience. In the multivariate analysis, compared with the 'right time' group, all other groups were more likely to find their first experience unpleasant and to have done it with a casual partner. Those in the 'I should not have done it' and 'I should have waited longer' groups were also more likely to have done it because of external pressure, especially among females.
The study results underline the significance to choose the right time and the right partner for first vaginal intercourse and the importance of including partner respect and avoiding external pressure as part of sexual education
Does the Primary Resource of Sex Education Matter? A Swiss National Study.
Sex education (SE) remains a subject of debate, including controversies on resources. The purpose of this paper was to determine the main SE resource during adolescence and its associations with personal characteristics and sexual behaviors of youths. Data were obtained from a self-administrated Swiss national survey on sexuality among young adults (mean age 26.3). Participants (N = 4978) were divided into six groups according to their main SE resource during their adolescence: Friends (1939; 38.9%), Parents (1361; 27.3%), School (n = 949; 19.1%), The Internet (399; 8.0%), Nobody (172; 3.5%) and Other (157; 3.2%). Groups were compared on sociodemographic, first sexual experiences, pregnancy, risky sexual behaviors, and undesired sexual experiences data. Males and non-heterosexual participants were overrepresented in the Internet group while, females more often reported their parents as their main SE resource. Participants in the School group reported the lowest rates of sexually transmitted infections and Friends the highest. Compared to the School group, those in the Friends, Internet, Nobody, and Other groups were more likely to report undesired sexual experiences. Few differences appeared between parents and school. Even though some resources such as friends or the Internet presented negative outcomes when they were assessed individually, we cannot deny the important place that they occupy in the lives of some youths
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Numerical simulation of fluid flow, solidification and defects in high pressure die casting (HPDC) process
The high pressure die casting process is extensively used to manufacture light metal parts with high productivity. A major drawback of the process is the relatively high variability in mechanical properties and poor repeatability between casting cycles, limiting the achievement of weight reduction through lighter design. Although it has been established that mechanical properties are adversely affected by casting defects, the origin of the relatively high randomness in the HPDC process is not well understood. Numerical simulation is a powerful and cost-effective tool to address this question, as it gives access to quantities that are difficult to obtain experimentally. A numerical simulation approach based on the finite element casting software ProCAST has been developed. The model was applied to the casting of aluminium tensile test samples, which were used to measure the tensile properties of the alloy. Simulation permitted the study of fluid flow, solidification and defect formation during each stage of the HPDC process: pouring, injection and cooling. Air entrapment and porosity distribution in the cast part were predicted. The results were compared with temperature measurements, porosity observations and solid distribution in the sleeve prior to injection. Although the results are still very preliminary, some trends could be established between the level of turbulence of the melt during injection and reduced elongation.This project is financially supported by EPSRC UK in the EPSRC Centre for Innovative Manufacturing in Liquid Metal Engineering (The EPSRC Centre — LiME)
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Turbulent Breakup of Non-Metallic Inclusions and Equiaxed Crystals During Solidification of a Hypoeutectic Al-Si Alloy
© 2021 The Author(s). The breakup of agglomerates and bodies suspended in turbulent flows are important phenomena that influence many aspects of modern solidification processing. It is often assumed that breakup operates in high-pressure die casting, wherein molten metal is transported at high speed through a narrow orifice system. To test this assumption, X-ray tomography and electron backscatter diffraction mapping are used to characterise pores, inclusions, and primary α-Al grains in die-cast samples produced with different flow field intensities. Numerical simulations are performed in ProCAST (ESI Group) to quantify the three-dimensional flow fields and to relate the derived quantities to breakage. Increasing the dissipation rate of turbulent kinetic energy is shown to induce a refinement of both non-metallic inclusions and primary α-Al1 grains nucleated in the shot chamber, a phenomenon which is ascribed to breakage. Several breakup mechanisms are discussed, with emphasis on the role of fluid turbulence.Engineering and Physical Sciences Research Council and Jaguar Land Rover Automotive PLC [project reference 2043200]
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On the probabilistic nature of high-pressure die casting
© 2021 The Authors. This article unmasks the probabilistic nature of high-pressure die casting; specifically, the cause of scatter in the tensile ductility of die-cast Al8Si0·4Mn0·3Mg (wt.%) alloy. Scatter in tensile ductility is related to the size of large pores and non-metallic inclusions. We propose that these non-metallic inclusions form during the pyrolysis of commercial plunger lubricants, and that these large pores derive from dilatational strains introduced during semi-solid deformation. The apparent randomness of pore formation is thus ascribed to the heterogeneous nature of the semi-solid network. Reducing heat loss in the shot chamber is shown to promote a more homogeneous grain structure, leading to a decrease in the maximum pore size from 1.32 mm to 0.37 mm, and an increase in the minimum tensile ductility from 6.8% to 9.4%.Engineering and Physical Sciences Research Council and Jaguar Land Rover Ltd. [project reference 2043200]
Amniotic fluid-derived stem cells for cardiovascular tissue engineering applications
Recent research has demonstrated that a population of stem cells can be isolated from amniotic fluid removed by amniocentesis that are broadly multipotent and non-tumorogenic. These amniotic fluid-derived stem cells (AFSC) could potentially provide an autologous cell source for treatment of congenital defects identified during gestation, particularly cardiovascular defects. In this review, the various methods of isolating, sorting and culturing AFSC are compared, along with techniques for inducing differentiation into cardiac myocytes and endothelial cells. Though research has not demonstrated complete and high yield cardiac differentiation, AFSC have been shown to effectively differentiate into endothelial cells and can effectively support cardiac tissue. Additionally, several tissue engineering and regenerative therapeutic approaches for the use of these cells in heart patches, injection after myocardial infarction, heart valves, vascularized scaffolds and blood vessels are summarized. These applications show great promise in the treatment of congenital cardiovascular defects, and further studies of isolation, culture, and differentiation of AFSC will help to develop their use for tissue engineering, regenerative medicine, and cardiovascular therapies
Calmodulin-like proteins localized to the conoid regulate motility and cell invasion by Toxoplasma gondii
Toxoplasma gondii contains an expanded number of calmodulin (CaM)-like proteins whose functions are poorly understood. Using a combination of CRISPR/Cas9-mediated gene editing and a plant-like auxin-induced degron (AID) system, we examined the roles of three apically localized CaMs. CaM1 and CaM2 were individually dispensable, but loss of both resulted in a synthetic lethal phenotype. CaM3 was refractory to deletion, suggesting it is essential. Consistent with this prediction auxin-induced degradation of CaM3 blocked growth. Phenotypic analysis revealed that all three CaMs contribute to parasite motility, invasion, and egress from host cells, and that they act downstream of microneme and rhoptry secretion. Super-resolution microscopy localized all three CaMs to the conoid where they overlap with myosin H (MyoH), a motor protein that is required for invasion. Biotinylation using BirA fusions with the CaMs labeled a number of apical proteins including MyoH and its light chain MLC7, suggesting they may interact. Consistent with this hypothesis, disruption of MyoH led to degradation of CaM3, or redistribution of CaM1 and CaM2. Collectively, our findings suggest these CaMs may interact with MyoH to control motility and cell invasion
An Experimental Area for Short Baseline Neutrino Physics on the CERN Neutrino Beam to Gran Sasso
A new neutrino beam line from the CERN SPS to the Gran Sasso laboratory in Italy is presently under study. The new neutrino beam will allow both long baseline and short baseline neutrino oscillation experiments to be performed. This report presents a conceptual design of the short baseline experimental area to be located at a distance of 1858 m from the neutrino target
High-Pressure Die Casting: A Review of Progress from the EPSRC Future LiME Hub
Data Availability Statement: The datasets generated and analysed during the current study are available from the corresponding author on reasonable request.Copyright: © 2022 by the authors. This article provides an overview of high-pressure die casting (HPDC)-related research undertaken at the EPSRC Future LiME Hub between 2015–2022. The project aimed to identify the cause of variability in the tensile ductility of die-cast structures, and to develop novel processing techniques to address this issue. Variability in tensile ductility was related to the size of large pores and non-metallic inclusions. It was proposed that these non-metallic inclusions formed during the pyrolysis of commercial plunger lubricants in the shot sleeve, and that these large pores derived from dilatational strains introduced during semi-solid deformation. Processing parameters and die design were found to significantly influence the microstructure of die-cast products, and the subsequent variability in tensile ductility. To close, recent progress on the application of intensive melt shearing to HPDC is reviewed. Intensive melt shearing was found to induce significant grain refinement in both Al and Mg alloys due to the effective dispersion of native oxide particles, and the use of these particles as heterogeneous nucleation substrates. The presence of native oxide particles also enabled the use of novel heat treatment procedures that avoided conventional issues such as surface blistering and geometrical distortion.Engineering and Physical Sciences Research Council (EPSRC) and Jaguar Land Rover Ltd. as part of the EPSRC Future Liquid Metal Engineering (LiME) Hub (grant number: 2043200); the APC was funded by Brunel University London
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