Resisting momentum in the abutment to rotating of freight car bogie

On the Latvian railway, derailments of freight cars take place in the course of shunting work on marshalling yards. A number of factors during shunting work on marshalling yards may contribute to the derailments of rolling stock: longitudinal dynamics during braking of cars with the turned off brakes by locomotive, hauling down cars from a marshalling hill with braking position controlled by an operator, dry internal rails in curves, absence of greasing in the pivot unit of freight bogies. At present, measures allowing elimination of the car derailments during shunting work are developed.During the period between repairs, the abutment unit of freight car often works in conditions of dry friction. Our observations suggest that at the time of taking a car into repair, there is often an absence of greasing between trail bearing and center plate of the abutment, and a presence of sandy dust. It increases a friction and, together with high contact pressures and dynamic influence, hinders the turn of bogie at motion of car.In this paper, the results of studying the resisting moment in the abutment to turning of bogie is reported. The study was conducted on the basis of freight bogie of type 18-100; the body was leant on the center plate unit of the abutment, on the center plate unit, and on the sliders. Experiments were conducted, with the use of greasing and at the dry friction of center plate unit

Analysis of factors affecting fractures of rails welded by alumino-thermic welding

On Latvian Railway the use of the alumino-thermic welding is widespread using the Elektro-Thermit Company technology. Today it is a basic method for rail joints on railway switches. The analysis of the metal structure in the thermic welding and in the thermic welded zone of rails showed that the weld metal had inclusions small pores and nonmetallics. Pores and nonmetallics are not reduce hardness but it is concentrators of stresses and sources of cracks development

Hervaeus Natalis, De secundis intentionibus, Distinctiones I&II : critical edition with introduction and indices

This critical edition covers the first two parts of De secundis intentionibus by Hervaeus Natalis (14th century). The introduction provides background information about the chronological and philosophical context of this work. At the beginning of the 14th century, the exact meaning and use of the intentio and the species intelligibilis formed an important theme in ontology, epistemology and logic. Compared to existing theories of, for instance, Thomas Aquinas, Hervaeus offers a new approach to the subject.UBL - phd migration 201

Flavour-kinematics duality for Goldstone modes

Three scalar effective field theories have special properties in terms of non-linear symmetries, soft limits and on-shell constructability that arise from their Goldstone nature: the non-linear $\sigma$-model, multi-DBI theory and the special Galileon. We discuss how these theories are related via flavour-kinematic duality, analogous to the colour-kinematic duality between gravity and gauge theories. At the off-shell level, we identify a specific mapping between the three theories that is crucially dependent on their non-linear symmetries. Similarly, we demonstrate how the on-shell amplitudes factorise into BCJ numerators describing flavour and a scalar version of kinematics, naturally leading to the inclusion of graviton exchange in the $SO(M,N)$ non-linear $\sigma$-model. Finally, we map those numerators onto each other, and comment on a similar relation to tensor kinematics. Our results highlight a common structure that underlies the physics of different Goldstone modes.Comment: 22 pages, 4 figure

A unifying Rayleigh-Plesset-type equation for bubbles in viscoelastic media

Understanding the ultrasound pressure-driven dynamics of microbubbles confined in viscoelastic materials is relevant for multiple biomedical applications, ranging from contrast-enhanced ultrasound imaging to ultrasound-assisted drug delivery. The volumetric oscillations of spherical bubbles is analyzed using the Rayleigh-Plesset equation, which describes the conservation of mass and momentum in the surrounding medium. Several studies have considered an extension of the Rayleigh-Plesset equation for bubbles embedded into viscoelastic media, but these are restricted to a particular choice of constitutive model and/or to small deformations. Here, we derive a unifying equation applicable to bubbles in viscoelastic media with arbitrary complex moduli and that can account for large bubble deformations. To derive this equation, we borrow concepts from finite-strain theory. We validate our approach by comparing the result of our model to previously published results and extend it to show how microbubbles behave in arbitrary viscoelastic materials. In particular, we use our viscoelastic Rayleigh-Plesset model to compute the bubble dynamics in benchmarked viscoelastic liquids and solids

De rol van arbeidsmarktinformatie in de opleidingskeuze van mbo'ers

De centrale vraag in dit rapport is in welke mate studiekiezers gebruik maken van arbeidsmarktinformatie bij het maken van hun opleidingskeuzes. In het bijzonder gaan wij in op de afruil tussen preferenties, competenties en arbeidsmarktperspectieven in het studiekeuzeproces. Dit rapport is opgesteld in het kader van het Project Onderwijs-Arbeidsmarkt. Het doel van het POA is om de transparantie van de arbeidsmarkt te vergroten

Anorexia nervosa versus hyperinsulinism: therapeutic effects of neuropharmacological manipulation

Fuad Lechin1,2, Bertha van der Dijs1,2, Betty Pardey-Maldonado1, Scarlet Baez1, Marcel E Lechin31Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Department of Pathophysiology, Institute of Experimental Medicine, Faculty of Medicine, Universidad Central de Venezuela, Caracas; 2Instituto de Vias Digestivas Caracas, Centro Clínico Profesional Caracas, Venezuela; 3Department of Internal Medicine, Texas A & M Health Science Center, College of Medicine, Texas, USABackground: We have demonstrated that anorexia nervosa is underpinned by overwhelming adrenal sympathetic activity which abolishes the neural sympathetic branch of the peripheral autonomic nervous system. This physiological disorder is responsible for gastrointestinal hypomotility, hyperglycemia, raised systolic blood pressure, raised heart rate, and other neuroendocrine disorders. Therefore, we prescribed neuropharmacological therapy to reverse this central and autonomic nervous system disorder, in order to normalize the clinical and neuroendocrine profile.Methods: The study included 22 female patients with anorexia nervosa (10 restricted type, 12 binge-eating type) who received three months of treatment with amantadine 100 mg/day. We measured blood pressure, heart rate, and circulating neurotransmitters, (noradrenaline, adrenaline, dopamine, platelet serotonin, free plasma serotonin) during supine resting, one minute of orthostasis, and a five-minute exercise test before and after one, two, and three months of treatment with amantadine, a drug which abrogates adrenal sympathetic activity by acting at the C1(Ad) medullary nuclei responsible for this branch of the peripheral sympathetic activity.Results: We found the amantadine abolished symptoms of anorexia nervosa from the first oral dose onwards. Normalization of autonomic and cardiovascular parameters was demonstrated within the early days of therapy. Abrupt and sustained increases in the plasma noradrenaline:adrenaline ratio and disappearance of abnormal plasma glucose elevation were registered throughout the three-month duration of the trial. Significant and sustained increases in body weight were documented in all cases. No relapses were observed.Conclusion: We have confirmed our previously published findings showing that the anorexia nervosa syndrome depends on the hypomotility of the gastrointestinal tract plus hyperglycemia, both of which are triggered by adrenal sympathetic hyperactivity. The above neuroendocrine plus neuroautonomic and clinical disorders which underpinned anorexia nervosa were abruptly suppressed since the first oral dose of amantadine, a drug able to revert the C1(Ad) over A5(NA) pontomedullary predominance responsible for adrenal and neural sympathetic activity, respectively. Keywords: amantadine, anorexia nervosa, adrenal sympathetic activity, hyperglycemia, hyperinsulinism, neural sympathetic activit

Early-life antibiotic use and risk of attention-deficit hyperactivity disorder and autism spectrum disorder:results of a discordant twin study

Background Development of the gut-brain axis in early life may be disturbed by antibiotic use. It has been hypothesized that this disturbance may contribute to development of neurodevelopmental disorders, including autism spectrum disorder and attention-deficit hyperactivity disorder. We aimed to assess the association between antibiotic use in early life and the risk of developing attention-deficit hyperactivity disorder or autism spectrum disorder, while controlling for shared genetic and environmental factors in a discordant twin design. Methods We conducted a cohort study in twins (7–12 years; 25 781 twins) from the Netherlands Twin Register (NTR) and a replication study in the Childhood and Adolescent Twin Study in Sweden (CATSS; 7946 9-year-old twins). Antibiotic use was recorded before age 2 years. Attention-deficit hyperactivity disorder and autism spectrum disorder were parent-reported in the Netherlands Twin Register and register-based in the Childhood and Adolescent Twin Study in Sweden. Results Early-life antibiotic use was associated with increased risk of attention-deficit hyperactivity disorder development [pooled odds ratio (OR) 1.10, 95% confidence interval (CI) 1.02-1.17] and autism spectrum disorder (pooled OR 1.15, 95% CI 1.06-1.25) in a case-control design. When restricting to monozygotic twin pairs discordant for the outcome, associations disappeared for both disorders in both cohorts (attention-deficit hyperactivity disorder OR 0.90, 95% CI 0.48-1.69 and OR 0.80, 95% CI 0.37-1.76, and autism spectrum disorder OR 0.66, 95% CI 0.38-1.16 and OR 0.29, 95% CI 0.02-4.50, respectively). Conclusions Our findings suggest that the association between early-life antibiotic use and risk of attention-deficit hyperactivity and autism spectrum disorder may be confounded by shared familial environment and genetics