1,093 research outputs found

    Condition-Based Monitoring on High-Precision Gearbox for Robotic Applications

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    This work presents a theoretical and experimental study regarding defect detection in a robotic gearbox using vibration signals in both cyclostationary and noncyclostationary conditions. The existing work focuses on inferring the health of the robot during operation with little regard toward the defective element of the components. This article illustrates the detection of specific element damage of a robotic gearbox during a robotic cycle based on domain knowledge and presents a novel data-driven method for asset health. This starts by studying the robotic gearbox, specifically its kinematics as a planetary 2-stage reduction gearbox to acquire the knowledge of the rotations of each component. The signals acquired from a test bench with four sensors undergo different acquisition methods and signal processing techniques to correlate the elements' frequencies. The work shows the detection of the artificially created defects from the acquired vibration data, verifying the kinematic methodology and identifying the root cause of failure of such gearboxes. A novel resampling method, Binning, is presented and compared with the traditional signal processing techniques. Binning combined with Principal Component Analysis (PCA) as a data-driven method to infer the state of the gearbox is presented, tested, and validated. This work presents methods as a step toward automatized predictive maintenance on robots in industrial applications

    Theoretical studies of the phase transition in the anisotropic 2-D square spin lattice

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    The phase transition occurring in a square 2-D spin lattice governed by an anisotropic Heisenberg Hamiltonian has been studied according to two recently proposed methods. The first one, the Dressed Cluster Method, provides excellent evaluations of the cohesive energy, the discontinuity of its derivative around the critical (isotropic) value of the anisotropy parameter confirms the first-order character of the phase transition. Nevertheless the method introduces two distinct reference functions (either N\'eel or XY) which may in principle force the discontinuity. The Real Space Renormalization Group with Effective Interactions does not reach the same numerical accuracy but it does not introduce a reference function and the phase transition appears qualitatively as due to the existence of two domains, with specific fixed points. The method confirms the dependence of the spin gap on the anisotropy parameter occurring in the Heisenberg-Ising domain

    The Evolution of Empathy and Women’s Precarious Leadership Appointments

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    Glass cliffs describe situations in which women are promoted to executive roles in declining organizations. To explain them, some authors suggest that people tend to “think crisis-think female.” However, the root cause of this association remains elusive. Using several subfields of evolutionary theory, we argue that biology and culture have shaped the perception of women as being more empathic than men and, consequently, as capable of quelling certain crises. Some crises are more intense than others and, whereas some brew within organizations, others originate from the external environment. We therefore propose that women will be selected to lead whenever a crisis is minimal to moderate and stems primarily from within the organization. Men, on the other hand, will be chosen as leaders whenever the crisis threatens the very existence of the firm and its source is an external threat. Leadership is a highly stressful experience, and even more so when leaders must scale glass cliffs. It is imperative that we understand what gives rise to them not only because they place women and potentially other minorities in positions where the likelihood of failure is high, but also because they help propagate stereotypes that undermine their true leadership ability

    Workplace Ostracism Seen through the Lens of Power

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    Drawing on approach/inhibition theory of power, we investigated two factors that influence the manner by which victims react to workplace ostracism: the hierarchical status of the ostracizer and the level of an ostracizee’s external social support including family, friends, and significant others. Across an experimental vignette study (Study 1) and a field study (Study 2), we found support for a three-way interaction with felt ostracism, ostracizee external social support, and ostracizer status influencing victims’ organizational citizenship behavior and deviance directed toward other individuals. In addition, felt ostracism and ostracizee external social support interacted to predict turnover intentions. Overall, victims who were ostracized by a legitimate higher-status authority (e.g., manager) and whose external social support network was limited experienced the most negative outcomes across both studies. Our findings suggest that contextual factors both inside and outside the organization jointly impact the way in which individuals react to perceived workplace ostracism. Implications and future research directions are discussed

    Breast cancer stem cell markers – the rocky road to clinical applications

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    Lately, understanding the role of cancer stem cells in tumor initiation and progression became a major focus in stem cell biology and in cancer research. Considerable efforts, such as the recent studies by Honeth and colleagues, published in the June issue of Breast Cancer Research, are directed towards developing clinical applications of the cancer stem cell concepts. This work shows that the previously described CD44+CD24- stem cell phenotype is associated with basal-type breast cancers in human patients, in particular BRCA1 inherited cancers, but does not correlate with clinical outcome. These very interesting findings caution that the success of our efforts in translating cancer stem cell research into clinical practice depends on how thorough and rigorous we are at characterizing these cells

    PREVALENCE OF CYTOMEGALOVIRUS IGG ANTIBODIES, POTENTIAL RISK FACTORS AND AWARENESS OF CONGENITAL CYTOMEGALOVIRUS AMONG FEMALE DOCTORS

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    Objective:  Female staff in children-Mother care hospitals may run an increased risk of cytomegalovirus (CMV) contact infection leading to a congenital CMV feto-pathy during pregnancy. Also, because of limited treatment options for congenital cytomegalovirus infection, preventive strategies are important so knowledge and awareness among doctors are essential for the success of preventive strategies. Thus this study was carried out to determine the positive rate of IgG among female doctors at age bearing who care for children and mothers in Sana'a hospitals. Also, to investigate the knowledge of congenital CMV among doctors involved in the study. Methods: This cross sectional study was carried out for one year (June 2017- June 2018); 178 Yemeni female doctors were included in this study. 23 (12.9%) of the total female doctors were pediatrics, 32(18%) gynecology and obstetrics, 9 (5.1%) Oto-rhinolaryngology and 114 (64%) were general practices. Blood samples were collected from all participants and tested for IgG antibodies of HCMV by ELISA. The individual's data were collected in a pre-designed questionnaire including; demographic data, risk factors. Also, a questionnaire on CMV infection was answered by doctors on the knowledge concerning epidemiology, transmission, symptoms and signs of CMV infection in adults and children; and treatment options. Results: 13.4% of female doctors were negative (HCMV IgG <9 SU), while the rest (86.6%) were positive (HCMV IgG ≄ 11 SU). There was escalate trend of positive HCMV IgG antibodies rate with increasing age, significance association between sero-positive HCMV IgG antibodies and parity (OR=3.1, p=0.01), 1-3 pregnancy rate (OR=2.2, p=0.05), and history of surgery (OR=3.8, p=0.01). Most of the doctors were aware that most healthy adults and pregnant women do not experience any symptoms of a CMV infection (66.8%); and only one-fifth of the respondents were aware that kissing, and changing diapers, are risk factors for the transmission of CMV. Also, only half of the total respondents were aware that microcephaly (59%), and hearing loss (56.7%) could be symptoms of congenital CMV. Conclusion: This study revealed that the HCMV is highly endemic in our population where the prevalence of IgG among the medical female doctors was 86.5%, thus HCMV should be considered as a possible cause of morbidity and mortality in fetus and might in mothers in Yemen. Increasing knowledge and awareness is expected to enhance the prevention of transmission, to improve recognition, and to stimulate diagnostic investigations and follow-up programs.                    Peer Review History: Received 8 October 2018;   Revised 22 October; Accepted 5 November, Available online 15 November 2018 Academic Editor:  Dr. Iman Muhammad Higazy, National Research Center, Egypt, [email protected] UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:        Reviewer's Comments: Average Peer review marks at initial stage: 5.0/10 Average Peer review marks at publication stage: 8.0/10 Reviewer(s) detail: Dr. Omonkhelin J Owolabi, University of Benin, Nigeria, [email protected]  Dr. Ali Abdullah A. Al-Mehdar, University of Basrah, Iraq, [email protected] Similar Articles: THE ASSOCIATION OF EPSTEIN-BARR VIRUS ANTIBODIES WITH RHEUMATOID ARTHRITIS AMONG YEMENI PATIENTS IN SANA’A CITY PREVALENCE OF RUBELLA IGG ANTIBODIES AMONG PRODUCTIVE-AGE ‎WOMEN IN AL-MAHWEET GOVERNORATE, YEME

    Stilbene derivatives promote Ago2-dependent tumour-suppressive microRNA activity

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    It is well known that natural products are a rich source of compounds for applications in medicine, pharmacy, and biology. However, the exact molecular mechanisms of natural agents in human health have not been clearly defined. Here, we demonstrate for the first time that the polyphenolic phytoalexin resveratrol promotes expression and activity of Argonaute2 (Ago2), a central RNA interference (RNAi) component, which thereby inhibits breast cancer stem-like cell characteristics by increasing the expression of a number of tumour-suppressive miRNAs, including miR-16, -141, -143, and -200c. Most importantly, resveratrol-induced Ago2 resulted in a long-term gene silencing response. We also found that pterostilbene, which is a natural dimethylated resveratrol analogue, is capable of mediating Ago2-dependent anti-cancer activity in a manner mechanistically similar to that of resveratrol. These findings suggest that the dietary intake of natural products contributes to the prevention and treatment of diseases by regulating the RNAi pathway

    PREVALENCE AND POTENTIAL RISK FACTORS OF HEPATITIS B VIRUS IN A SAMPLE OF CHILDREN IN TWO SELECTED AREAS IN YEMEN

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    Objective: The global epidemic of hepatitis B is a significant public health problem. The endemicity of HBV infection used to be believed high in Yemen. Data for the prevalence of HBsAg among children in rural and urban areas in Yemen is scarce and incompetent. The study was made to determine prevalence of HB surface antigen among children in 2 selected areas in Yemen. Methods: Eight hundred forty and 212 children were randomly chosen from Sana'a city and Shabowah governorate, respectively. Sera were tested for HBs antigen by ELISA technique, and HB genome was tested for positive HB surface antigen specimens to confirm positivity using polymerase chain reaction (PCR)-based test. Each data collected in a pre-designed questionnaire including sex, age, and risk factors of HBV and prior vaccine of HBV. Results: The prevalence of HB surface antigen among children in Sana'a city was only 1.8%, and in Shabowah governorate was 3.8%. There was a significant association of non-vaccinated children, birth by cesarean, and with a history of parental exposure with contracting HBV infection.Conclusion: Evidence from these studies in Yemen suggests that there is a steady increase in exposure to HBV over a lifetime. Hospital-acquired HBV infection is common in Yemen, and high vaccination coverage rate should be achieved, particularly in rural areas, in parallel with health education.                      Peer Review History: Received 21 June 2019;   Revised 6 July; Accepted 10 July, Available online 15 July 2019 Academic Editor: Dr. Amany Mohamed Alboghdadly, Princess Nourah bint abdulrahman university, Riyadh, [email protected] UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:                Reviewer's Comments: Average Peer review marks at initial stage: 6.5/10 Average Peer review marks at publication stage: 8.5/10 Reviewer(s) detail: Aya Mohammed Mohammed Essawy, MTI University- Mokattam, Egypt, [email protected] Dr. Dalia Kamal Zaffar Ali, Modern University for technology and information, Egypt, [email protected] Similar Articles: SERO-EPIDEMIOLOGICAL STUDY OF HEPATITIS B, C, HIV AND TREPONEMA PALLIDUM AMONG BLOOD DONORS IN HODEIDA CITY- YEMEN EXPLOSION OF HEPATITIS B AND C VIRUSES AMONG HEMODIALYSIS PATIENTS AS A RESULT OF HEMODIALYSIS CRISIS IN YEME
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