Cost optimal, parallel reliability systems with fixed repair sanction

Optimisation methods under varied criteria for different parameters in stochastic reliability systems are being increasingly developed and have been reported in recent literature. The large interest evinced in this fascinating area is primarily due to its applicational value and operational role in the decision making process. Recently a parallel system has been considered and the optimal number of units discussed, as well as optimal replacement times for the system based on acquisition and replacement costs.In this paper we consider an improved version of the model formulation, by bringing in additionally the maintenance and per unit repair time costs, and develop a procedure to obtain the optimal number of components in the system with the condition that the system is allowed to undergo a prefixed maximum number of repairs, after which the system is to be replaced.The applicational use of the results is illustrated through numerical work, specialising to some known laws governing the system parameters and corresponding to different fixed number of repair sanctions.     

Parallel Gauss-Jordan elimination for the solution of dense linear systems

Any factorization/back substitution scheme for the solution of linear systems consists of two phases which are different in nature, and hence may be inefficient for parallel implementation on a single computational network. The Gauss-Jordan elimination scheme unifies the nature of the two phases of the solution process and thus seems to be more suitable for parallel architectures, especially if reconfiguration of the communication pattern is not permitted. In this communication, a computational network for the Gauss-Jordan algorithm is presented. This network compares favorably with optimal implementations of the Gauss elimination/back substitution algorithm.     

Nanomembrane‐Based,Thermal‐Transport Biosensor for Living Cells

Knowledge of materials' thermal‐transport properties, conductivity and diffusivity, is crucial for several applications within areas of biology, material science and engineering. Specifically, a microsized, flexible, biologically integrated thermal transport sensor is beneficial to a plethora of applications, ranging across plants physiological ecology and thermal imaging and treatment of cancerous cells, to thermal dissipation in flexible semiconductors and thermoelectrics. Living cells pose extra challenges, due to their small volumes and irregular curvilinear shapes. Here a novel approach of simultaneously measuring thermal conductivity and diffusivity of different materials and its applicability to single cells is demonstrated. This technique is based on increasing phonon‐boundary‐scattering rate in nanomembranes, having extremely low flexural rigidities, to induce a considerable spectral dependence of the bandgap‐emission over excitation‐laser intensity. It is demonstrated that once in contact with organic or inorganic materials, the nanomembranes' emission spectrally shift based on the material's thermal diffusivity and conductivity. This NM‐based technique is further applied to differentiate between different types and subtypes of cancer cells, based on their thermal‐transport properties. It is anticipated that this novel technique to enable an efficient single‐cell thermal targeting, allow better modeling of cellular thermal distribution and enable novel diagnostic techniques based on variations of single‐cell thermal‐transport properties.     

Exploring precrash maneuvers using classification trees and random forests

Taking evasive actions vis-à-vis critical traffic situations impending to motor vehicle crashes endows drivers an opportunity to avoid the crash occurrence or at least diminish its severity. This study explores the drivers, vehicles, and environments’ characteristics associated with crash avoidance maneuvers (i.e., evasive actions or no evasive actions). Rear-end collisions, head-on collisions, and angle collisions are analyzed separately using decision trees and the significance of the variables on the binary response variable (evasive actions or no evasive actions) is determined. Moreover, the random forests method is employed to rank the importance of the drivers/vehicles/environments characteristics on crash avoidance maneuvers. According to the exploratory analyses’ results, drivers’ visibility obstruction, drivers’ physical impairment, drivers’ distraction are associated with crash avoidance maneuvers in all three types of accidents. Moreover, speed limit is associated with rear-end collisions’ avoidance maneuvers and vehicle type is correlated with head-on collisions and angle collisions’ avoidance maneuvers. It is recommended that future research investigates further the explored trends (e.g., physically impaired drivers, visibility obstruction) using driving simulators which may help in legislative initiatives and in-vehicle technology recommendations.     

Reliability Analysis of Type III Gas Storage Vessel Under Pressure Loading

Journal of Failure Analysis and Prevention - This work presents the suggestion of a model for the prediction of the reliability of type III gas storage vessel under pressure, considering the...     

Intermittent pneumatic compression in patients with ESRD. A systematic review

Introduction: Patients with end‐stage renal disease (ESRD) experience frequent hemodialysis (HD) complications. Intradialytic hypotension (IDH) is a common complication presenting in approximately between 20 and 50% of HD sessions. Available interventions such as volume replacement or vasoactive medications are associated with significant side effects. Intermittent pneumatic compression (IPC) has been proposed as a feasible intervention for the prevention of IDH, treatment of peripheral arterial disease and venous ulcers. These devices apply intermittent pressure to the legs improving arterial blood flow, mobilization of pooled blood with an increase in venous return increasing the effective circulatory volume. Our goal was to identify the published clinical evidence on whether IPC has a circulatory benefit and is it well‐tolerated among patients receiving HD. Methods: We conducted a systematic review to identify studies assessing the efficacy and safety of IPC in patients with ESRD. Our primary outcome was IDH. Secondary outcomes such as HD comfort, ultrafiltration volume, and physical activity were collected. No restrictions where used and we included all observational and interventional studies. Two reviewers performed screening and study quality assessment. Findings: We included seven studies. Out of the seven studies, five addressed IDH, and the rest were included for secondary outcomes such as physical capacity and HD comfort. In one randomized crossover trial comparing exercise against IPC, 21 patients were randomized to 3 different arms (no intervention, cycling, IPC) a decrease in the rates of IDH with IPC was described (43%, 38%, and 24% respectively P = 0.014). The smaller studies corroborated these results. All studies where at high risk of bias. Discussion: IPC might offer significant benefits for patients undergoing HD not limited to prevention of IDH but also improvement of hemodialysis comfort and physical capacity. However, our results should be interpreted in the context of its limitations.     

Berries and Their Polyphenols as a Potential Therapy for Coronary Microvascular Dysfunction: A Mini-Review

Ischemia with no obstructive coronary artery disease (INOCA) is a common diagnosis with a higher prevalence in women compared to men. Despite the absence of obstructive coronary artery disease and no structural heart disease, INOCA is associated with major adverse cardiovascular outcomes as well a significant contributor to angina and related disability. A major feature of INOCA is coronary microvascular dysfunction (CMD), which can be detected by non-invasive imaging and invasive coronary physiology assessments in humans. CMD is associated with epicardial endothelial-dependent and -independent dysfunction, diffuse atherosclerosis, and left-ventricular hypertrophy, all of which lead to insufficient blood flow to the myocardium. Inflammatory and oxidative stress signaling, upregulation of the renin-angiotensin-aldosterone system and adrenergic receptor signaling are major drivers of CMD. Treatment of CMD centers around addressing cardiovascular risk factors; however, there are limited treatment options for those who do not respond to traditional anti-anginal therapies. In this review, we highlight the ability of berry-derived polyphenols to modulate those pathways. The evidence supports the need for future clinical trials to investigate the effectiveness of berries and their polyphenols in the treatment of CMD in INOCA patients.     

Fatalities and injuries in the Kuwaiti construction industry

This paper presents an analysis of construction accidents in Kuwait along with accident causation and injuries that can be considered serious or fatal, so that corrective measures can be taken to decrease casualties, resulting in a safer construction industry. The paper evaluates the existing injury and cost reporting-investigation system of construction accidents in government agencies and private firms.

This research confirms that construction is the most hazardous industry in Kuwait, with accidents accounting for 48%, 38% and 34% of all disabling injuries and 62%, 38% and 42% of all fatalities in 1994, 1995 and 1996, respectively. These rates are considered high and can be compared to construction accident statistics in the U.S.A. which accounted for 14% of all work-related deaths and 9% of disabling injuries in 1993. Based on the study, falling from a height appears to be the major cause of construction injuries and fatalities in Kuwait. Poor accident records and reporting systems hide the extent of the construction safety problem in Kuwait. In addition, many people at management level are unaware of accident-related costs and the effectiveness of a safety program in reducing project costs.     

Regiocontrolled Synthesis of 4-Halo-5,6-Dihydro-4H-1,2-Oxazines; A Novel Route for α-Fluorovinyl Ketones

Regiocontrolled deprotonation (e.g. lithiation) of 3-methyl-4-H-5,6-dihydro-1,2-oxazine 1 is achieved at −65°C. The lithiated compound reacts cleanly with the halogens Cl₂, Br₂ and I₂ at low temperatures (−65°C) to give the corresponding 4-halo derivatives. Reaction of the 4-iodo compound 2a with KF in diethyleneglycol gives the elimination product 4 whereas the bromo compound 2b reacts under substitution to the 4-fluoro derivatives 5. The fluorooxazine derivatives 8a-c were converted to the αfluoroenones 11 a-c via the oxoiminium salts 10a-c. The U.V. and ¹HNMR of the novel series of halides 2a-c and 5 were studied.     

Muscarinic-receptor antagonist scopolamine rescues hippocampal neurons from death induced by glutamate

Preprodynorphin and preproenkephalin mRNA expression was examined in the CNS of two rat strains, the alcohol-preferring Fawn-Hooded (FH) and the alcohol-non-preferring Wistar-Kyoto (WKY), using in situ hybridisation histochemistry. Relative to the WKY, the FH showed significantly lower levels of preproenkephalin mRNA in the striatum and nucleus accumbens (-24% and -17% respectively), but a higher level of preprodynorphin mRNA in the hippocampus (+33%). The depressed level of preproenkephalin mRNA in the nucleus accumbens may be implicated in alcohol-seeking behaviour.