Performance of merging lines with uneven buffer capacity allocation: the effects of unreliability under different inventory-related costs

This simulation study investigates whether machine efficiency, mean time to failure (MTTF) and mean time to repair (MTTR) significantly affect the performance of uneven buffer capacity allocation patterns for merging lines. Also studied is the trade-off between increasing throughput via bigger buffers and their associated inventory-related costs, since previous studies have shown that higher overall buffer capacity and higher average inventory content result in higher throughput. Results suggest that an ascending buffer allocation pattern (concentrating buffer capacity towards the end of the line) produces higher throughput in shorter, more unreliable lines; whereas the balanced pattern shows better performance in longer, more reliable lines. Increasing average buffer capacity per station and/or having higher average buffer content was found to be more cost-effective in lines with lower machine inefficiency, shorter MTTF and MTTR, and longer lines. Results differed between reliable and unreliable lines since reliable lines were particularly penalised by buffer capacity investiment/maintenance costs due to a relatively low increase in throughput resulting from the addition of extra buffer capacity

Shop-floor scheduling as a competitive advantage:A study on the relevance of cyber-physical systems in different manufacturing contexts

The aim of this paper is to analyse the relevance of cyber-physical systems (CPS) in different manufacturing contexts and to study whether CPS could provide companies with competitive advantage by carrying out a better scheduling task. This paper is developed under the umbrella of contingency theory which states that certain technologies and practices are not universally applicable or relevant in every context; thus, only certain companies will benefit from using particular technologies or practices. The conclusion of this paper, developed through deductive reasoning and supported by preliminary simulation experiments and statistical tests, is that factories with an uncertain and demanding market environment as well as a complex production process could benefit the most from implementing a CPS at shop-floor level since a cyber-physical shop-floor will provide all the capabilities needed to carry out the complex scheduling task associated with this type of context. On the other hand, an increase in scheduling performance due to a CPS implementation in factories with simple production flows and stable demand could not be substantial enough to overcome the high cost of installing a fully operational CPS

The impact of unequal processing time variability on reliable and unreliable merging line performance

Research on merging lines is expanding as their use grows significantly in the contexts of remanufacturing, reverse logistics and developing economies. This article is the first to study the behavior of unpaced, reliable, and unreliable merging assembly lines that are deliberately unbalanced with respect to their coefficients of variation (CV). Conducting a series of simulation runs with varying line lengths, buffer storage capacities and unbalanced CV patterns delivers intriguing results. For both reliable and unreliable lines, the best pattern for generating higher throughput is found to be a balanced configuration (equal CVs along both parallel lines), except for unreliable lines with a station buffer capacity of six. In that case, the highest throughput results from the descending configuration, i.e. concentrating the variable stations close to the beginning of both parallel lines and the steady stations towards the end of the line. Ordering from the least to most steady station also provides the best average buffer level. By exploring the experimental Pareto Frontier, this study shows the combined performance of unbalanced CV patterns for throughput and average buffer level. Study results suggest that caution should be exercised when assuming equivalent behavior from reliable and unreliable lines, or single serial lines and merging lines, since the relative throughput performance of some CV patterns changed between the different configurations

Studying the effects of skewness of inter-arrival and service times on the probability distribution of waiting times

Previous studies have shown that the mean queue length of a GI/G/1 system is significantly influenced by the skewness of inter-arrival times, but not by the skewness of service times. These results are limited because all the distributions considered in previous studies were positively skewed. To address this limitation, this paper investigates the effects of the skewness of inter-arrival and service times on the probability distribution of waiting times, when a negatively skewed distribution is used to model inter-arrival and service times. Subsequent to a series of experiments on a GI/G/1 queue using discrete-event simulation, results have shown that the lowest mean waiting time and the lowest variance of waiting times can be attained with a combination of positive inter-arrival skewness and negative service skewness. Results also show an interesting effect of the skewness of service times in the probability of no-delay in environments with a higher utilization factor

Studying the Effects of the Skewness of Inter-Arrival and Service Times on the Probability Distribution of Waiting Times

Previous studies have shown that the mean queue length of a GI/G/1 system is significantly influenced by the skewness of inter-arrival times, but not by the skewness of service times. These results are limited because all the distributions considered in previous studies were positively skewed. To address this limitation, this paper investigates the effects of the skewness of inter-arrival and service times on the probability distribution of waiting times, when a negatively skewed distribution is used to model inter-arrival and service times. Subsequent to a series of experiments on a GI/G/1 queue using discrete-event simulation, results have shown that the lowest mean waiting time and the lowest variance of waiting times can be attained with a combination of positive inter-arrival skewness and negative service skewness. Results also show an interesting effect of the skewness of service times in the probability of no-delay in environments with a higher utilization factor

Protein expression of PKCZ (Protein Kinase C Zeta), Munc18c, and Syntaxin-4 in the insulin pathway in endometria of patients with polycystic ovary syndrome (PCOS)

Artículo de publicación ISIBackground: Polycystic Ovary Syndrome (PCOS) is an endocrine-metabolic disorder commonly associated with insulin resistance (IR). Previous studies indicate about the expression of molecules involved in the insulin pathway in endometria of women with PCOS-IR. Therefore, the aim of the present study was to evaluate the effect of insulin and testosterone in the expression of these proteins in the endometria and immortal endometrial stromal cell line (T-HESCs). Methods: We examined the protein levels of Munc18c, PKC zeta, phospho-PKC Zeta, and Syntaxin-4. Protein levels were assessed by Western Blot and/or immunohistochemistry in proliferative endometria (NPE = 6) and in PCOS endometria with insulin resistance (PCOSE-IR = 6). We also evaluated whether high concentrations of insulin (100 nM) and/or testosterone (100 nM), during a 24 h stimulatory period, affected the expression of these proteins in an immortal endometrial stromal cell line (T-HESCs). Once stimulated, proteins were extracted from cells and were assessed by Western Blot analysis. Immunocytochemistry was performed to detect AR in T-HESC cells. Results: Western Blot data showed decreased expression (p < 0,05) of Munc18c and phospho-PKC Zeta in PCOS-IR endometria (PCOSE-IR) with respect to the control (NPE). In the in vitro study, Western Blot analysis showed decreased levels of Munc18c, PKC Zeta and phospho-PKC Zeta with the different hormonal treatments when compared to the control condition (no hormonal stimulation) (p < 0,05). The AR was present in the endometrial stromal cell line (T-HESC). Conclusion: The conditions of hyperinsulinism and hyperandrogenism present in PCOS-IR patients modulate the expression and/or phosphorylation of the proteins involved in the insulin pathway at the endometrial level. These data extend to the T-HESCs cells results, where insulin and testosterone exert an effect on both the expression and phosphorylation of proteins present in the pathway.This study was supported by grant number 1095127 from the Fondo Nacional de Desarrollo Científico y Tecnológico, Chile

Effects of post-COVID-19 syndrome on cardiovascular and pulmonary function

Introducción. la pandemia de COVID-19 ha tenido un impacto significativo en los sistemas cardiovascular y pulmonar, con síntomas persistentes en algunos pacientes, conocidos como "long COVID", que incluyen fatiga, disnea, dolor torácico y palpitaciones, así como complicaciones como miocarditis, arritmias y fibrosis pulmonar. Objetivo. evaluar los efectos a largo plazo del síndrome post-COVID-19 en la función cardiovascular y pulmonar de pacientes recuperados. Metodología. se realizó un estudio retrospectivo observacional utilizando bases de datos como PubMed y Google Scholar, analizando pacientes recuperados de COVID-19 con síntomas post-COVID. Se excluyeron casos sin síntomas post-COVID o datos claros de recuperación, realizando un análisis descriptivo de los datos recolectados. Resultados. Se esperan resultados que detallen las alteraciones en los sistemas cardiovascular y pulmonar después de COVID, además de analizar la relación entre la gravedad inicial de la enfermedad y las secuelas a largo plazo. Estos hallazgos mejorarán la comprensión y el manejo de las complicaciones post-COVID en estos sistemas. Conclusión. la pandemia de COVID-19 afecta múltiples sistemas del cuerpo, generando síntomas persistentes conocidos como "Long COVID". Las complicaciones cardiacas y pulmonares son preocupantes, destacando la importancia del monitoreo cardiovascular y la rehabilitación pulmonar. Además, se subraya la necesidad de abordar el impacto psicológico y se reconocen las limitaciones de la investigación. Área de estudio general: Medicina. Área de estudio específica: Medicina General. Tipo de estudio:&nbsp; Revisión bibliográfica.Introduction. the COVID-19 pandemic has had a significant impact on the cardiovascular and pulmonary systems, with persistent symptoms in some patients, known as "long COVID," which include fatigue, shortness of breath, chest pain, and palpitations, as well as complications such as myocarditis, arrhythmias, and pulmonary fibrosis. Objective. to assess the long-term effects of post-COVID-19 syndrome on the cardiovascular and pulmonary function of recovered patients. Methodology. a retrospective observational study was conducted using databases such as PubMed and Google Scholar, analyzing recovered COVID-19 patients with post-COVID symptoms. Cases without post-COVID symptoms or clear recovery data were excluded, and a descriptive analysis of the collected data was performed. Results. expected results will detail the alterations in the cardiovascular and pulmonary systems after COVID, as well as analyze the relationship between the initial severity of the disease and long-term sequelae. These findings will enhance understanding and management of post-COVID complications in these systems. Conclusion. the COVID-19 pandemic affects multiple body systems, leading to persistent symptoms known as "long COVID." Cardiac and pulmonary complications are concerning, emphasizing the importance of cardiovascular monitoring and pulmonary rehabilitation. Additionally, the need to address the psychological impact is underscored, and the limitations of the research are acknowledged

INVESTIGAÇÃO DE SEGURANÇA NO MOODLE

O Moodle é uma aplicação Web definida como uma plataforma de educação a distância usada em muitas universidades como forma de permitir a interação do aluno on-line. Instituições fazem uso do Moodle por causa da sua flexibilidade, adaptabilidade e facilidade de uso. De modo que, possui uma substancial base de usuários com 56.185 sites ativos e 46.343.749 usuários finais. Este artigo tem como objetivo descrever as falhas de segurança encontradas através da aplicação de técnicas de exploração de vulnerabilidades. O Moodle foi escolhido para validação por ser a principal aplicação de código aberto utilizada nos dias de hoje para prover educação a distância

Successful isolation of Leishmania infantum from Rhipicephalus sanguineus sensu lato (Acari : Ixodidae) collected from naturally infected dogs

Background: The main transmission route of Leishmania infantum is through the bites of sand flies. However, alternative mechanisms are being investigated, such as through the bites of ticks, which could have epidemiological relevance. The objective of this work was to verify the presence of Leishmania spp. In Rhipicephalus sanguineus sensu lato collected from naturally infected dogs in the Federal District of Brazil. Methods: Ticks were dissected to remove their intestines and salivary glands for DNA extraction and the subsequent amplification of the conserved region of 120 bp of kDNA and 234 bp of the hsp70 gene of Leishmania spp. The amplified kDNA products were digested with endonucleases HaeIII and BstUI and were submitted to DNA sequencing. Isolated Leishmania parasites from these ticks were analyzed by multilocus enzyme electrophoresis, and the DNA obtained from this culture was subjected to microsatellite analyses. Results: Overall, 130 specimens of R. sanguineus were collected from 27 dogs. Leishmania spp. were successfully isolated in culture from five pools of salivary glands and the intestines of ticks collected from four dogs. The amplified kDNA products from the dog blood samples and from the tick cultures, when digested by HaeIII and BstUI, revealed the presence of L. braziliensis and L. infantum. One strain was cultivated and characterized as L. infantum by enzyme electrophoresis. The amplified kDNA products from the blood of one dog showed a sequence homology with L. braziliensis; however, the amplified kDNA from the ticks collected from this dog showed a sequence homology to L. infantum. Conclusion: The results confirm that the specimens of R. sanguineus that feed on dogs naturally infected by L. infantum contain the parasite DNA in their intestines and salivary glands, and viable L. infantum can be successfully isolated from these ectoparasites