446 research outputs found

    Learning Curves and p-charts for a preliminary estimation of asymptotic performances of a manufacturing process

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    This paper presents a method for a preliminary estimation of asymptotic performances of a manufacturing process based on the knowledge of its learning curve estimated during the setting up of p-chart. The main novelties of the method are the possibility of estimating the asymptotic variability of a process and providing a simple approach for evaluating the period of revision of process control limits. An application of the method to a real example taken from the literature is also provided

    Work and Home: balancing the considerations and considering the balance

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    In contemporary society, work and home represent the two most significant domains in the life of a working individual. Work-Home Interference (WHI) and Home-Work Interference (HWI) is experienced when pressures from both domains is incompatible. This thesis explored the phenomenon of WHI/HWI from multiple methodologies and contributed to the field by the introduction of a more systematic approach to the measurement of the antecedents of both. Chapter 1 provided a political, social, empirical and theoretical overview of the area. This introductory chapter provided the following conclusions; (1) WHI and HWI is a problem for both men and women, (2) the antecedents of WHI and HWI needed to be studied in a more systematic fashion, (3) a more comprehensive view of the phenomena can be ascertained by also examining positive spillover. This chapter introduced the main research questions to be examined. Chapter 2 tested a job and home demands model of WHI/HWI using a sample recruited from the Internet. More specifically, the study evaluated the mediational role of both WHI and HWI between demands and job burnout. Overall, this research made the following contributions: (1) It expanded upon our knowledge of the nature of the mediational effect of WHI and HWI on the demands-burnout relationship, (2) It offered a more precise specification of job and home demands likely to affect burnout, (3) explored possible gender differences in the network of demands, WHI/HWI, and burnout. In Chapter 3, the previous model was extended and a more complete model of demands and resources among newspaper managers was tested. The central idea underlying the theoretical model of this study was that work and home demands lead to work strain and decreased feelings of engagement, while work and home resources lead to increased feelings of engagement and reduced burnout. Results indicated that negative interference mediated between demands and outcomes, and positive interference mediated between resources and outcomes. In Chapter 4, the phenomenon of crossover was examined. Crossover was examined in a sample of information technology (IT) professionals and their working spouses. Results indicated the following: (1) For IT professionals, work-home interference (WHI) was directly linked to work-related outcomes (i.e., burnout, turnover intention); (2) Crossover effects were found between the home-work interference (HWI) of the IT professional and the exhaustion and turnover intentions of their spouse. In Chapter 5, longitudinal data concerning WHI were examined. A two-wave panel study was carried out to examine reciprocal relationships of job demands/resources and WHI with job burnout and job engagement. The results primarily showed that Time 1 job demands were causally related to WHI-negative and burnout at Time 2. Furthermore, reversed causal effects were found for engagement at Time 1, which was causally related to WHI-positive at Time 2. The reversed effects found for our resources model suggests that positive spillover is antecedent (or triggered) by feelings of engagement at work. In conclusion, work, home and the interaction between the two has been recognized as a major problem for employees, employers, families, organizations and society at large

    The Greek Burnout Assessment Tool: Examining Its Adaptation and Validity

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    Burnout is a significant challenge in the workplace. Its extent is global and its unfavourable consequences are diverse, affecting the individual, the organization, and society. The aim of the present study was to examine the adaptation and assess the validity of the Greek version of the Burnout Assessment Tool (BAT). The adaptation process included the translation and back-translation of the BAT. Data were collected from 356 Greek employees from diverse sectors. Confirmatory factor analysis and item response theory were utilized to assess the validity of the Greek version of the BAT. According to the findings of the present research, the core symptoms scale and the secondary symptoms scale of BAT-23 and BAT-12 models demonstrated adequate structures for the analysis and measurement of burnout in the Greek context. Finally, the psychometric performance of the BAT-GR-12 compared to the BAT-GR-23 establishes it as a more optimum instrument for the assessment of burnout across Greek working adults

    pi-NN Coupling Constants from NN Elastic Data between 210 and 800 Mev

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    High partial waves for pppp and npnp elastic scattering are examined critically from 210 to 800 MeV. Non-OPE contributions are compared with predictions from theory. There are some discrepancies, but sufficient agreement that values of the πNN\pi NN coupling constants g02g_0^2 for π0\pi ^0 exchange and gc2g^2_{c} for charged π\pi exchange can be derived. Results are g02=13.91±0.13±0.07g^2_0 = 13.91 \pm 0.13 \pm 0.07 and gc2=13.69±0.15±0.24g^2_c = 13.69 \pm 0.15 \pm 0.24, where the first error is statistical and the second is an estimate of the likely systematic error, arising mostly from uncertainties in the normalisation of total cross sections and dσ/dΩd\sigma/d\Omega.Comment: 21 pages of LaTeX, UI-NTH-940

    cMET inhibitor crizotinib impairs angiogenesis and reduces tumor burden in the C3(1)-Tag model of basal-like breast cancer

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    Epidemiologic studies have associated obesity with increased risk of the aggressive basal-like breast cancer (BBC) subtype. Hepatocyte growth factor (HGF) signaling through its receptor, cMET, is elevated in obesity and is a pro-tumorigenic pathway strongly associated with BBC. We previously reported that high fat diet (HFD) elevated HGF, cMET, and phospho-cMET in normal mammary gland, with accelerated tumor development, compared to low fat diet (LFD)-fed lean controls in a murine model of BBC. We also showed that weight loss resulted in a significant reversal of HFD-induced effects on latency and elevation of HGF/cMET signaling in normal mammary and cMET in normal mammary and tumors. Here, we sought to inhibit BBC tumor progression in LFD- and HFD-fed C3(1)-Tag BBC mice using a small molecule cMET inhibitor, and began crizotinib treatment (50 mg/kg body weight by oral gavage) upon identification of the first palpable tumor. We next investigated if administering crizotinib in a window prior to tumor development would inhibit or delay BBC tumorigenesis. Treatment: Crizotinib significantly reduced mean tumor burden by 27.96 and 37.29 %, and mean tumor vascularity by 35.04 and 33.52 %, in our LFD- and HFD-fed C3(1)-Tag BBC mice, respectively. Prevention: Crizotinib significantly accelerated primary tumor progression in both diet groups but had no effect on total tumor progression or total tumor burden. In sum, cMET inhibition by crizotinib limited tumor development and microvascular density in basal-like tumor-bearing mice but did not appear to be an effective preventive agent for BBC

    Geometric Approach to Pontryagin's Maximum Principle

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    Since the second half of the 20th century, Pontryagin's Maximum Principle has been widely discussed and used as a method to solve optimal control problems in medicine, robotics, finance, engineering, astronomy. Here, we focus on the proof and on the understanding of this Principle, using as much geometric ideas and geometric tools as possible. This approach provides a better and clearer understanding of the Principle and, in particular, of the role of the abnormal extremals. These extremals are interesting because they do not depend on the cost function, but only on the control system. Moreover, they were discarded as solutions until the nineties, when examples of strict abnormal optimal curves were found. In order to give a detailed exposition of the proof, the paper is mostly self\textendash{}contained, which forces us to consider different areas in mathematics such as algebra, analysis, geometry.Comment: Final version. Minors changes have been made. 56 page

    Shortening the length of stay and mechanical ventilation time by using positive suggestions via MP3 players for ventilated patients

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    Long stay in intensive care unit (ICU) and prolonged ventilation are deleterious for subsequent quality of life and surcharge financial capacity. We have already demonstrated the beneficial effects of using suggestive communication on recovery time during intensive care. The aim of our present study was to prove the same effects with standardized positive suggestive message delivered by an MP3 player. Patients ventilated in ICU were randomized into a control group receiving standard ICU treatment and two groups with a standardized pre-recorded material delivered via headphones: a suggestive message about safety, self-control, and recovery for the study group and a relaxing music for the music group. Groups were similar in terms of age, gender, and mortality, but the SAPS II scores were higher in the study group than that in the controls (57.8 ± 23.6 vs. 30.1 ± 15.5 and 33.7 ± 17.4). Our post-hoc analysis results showed that the length of ICU stay (134.2 ± 73.3 vs. 314.2 ± 178.4 h) and the time spent on ventilator (85.2 ± 34.9 vs. 232.0 ± 165.6 h) were significantly shorter in the study group compared to the unified control. The advantage of the structured positive suggestive message was proven against both music and control groups

    Separate and combined effects of advanced age and obesity on mammary adipose inflammation, immunosuppression and tumor progression in mouse models of triple negative breast cancer

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    Introduction: Advanced age and obesity are independent risk and progression factors for triple negative breast cancer (TNBC), which presents significant public health concerns for the aging population and its increasing burden of obesity. Due to parallels between advanced age- and obesityrelated biology, particularly adipose inflammation, we hypothesized that advanced age and obesity each accelerate mammary tumor growth through convergent, and likely interactive, mechanisms. Methods: To test this hypothesis, we orthotopically transplanted murine syngeneic TNBC cells into the mammary glands of young normoweight control (7 months), young diet-induced obese (DIO), aged normoweight control (17 months), and aged DIO female C57BL/6J mice. Results: Here we report accelerated tumor growth in aged control and young DIO mice, compared with young controls. Transcriptional analyses revealed, with a few exceptions, overlapping patterns of mammary tumor inflammation and tumor immunosuppression in aged control mice and young DIO mice, relative to young controls. Moreover, aged control and young DIO tumors, compared with young controls, had reduced abundance ofcytotoxic CD8 T cells. Finally, DIO in advanced age exacerbated mammary tumor growth, inflammation and tumor immunosuppression. Discussion: These findings demonstrate commonalities in the mechanisms driving TNBC in aged and obese mice, relative to young normoweight controls. Moreover, we found that advanced age and DIO interact to accelerate mammary tumor progression. Given the US population is getting older and more obese, age- and obesity-related biological differences will need to be considered when developing mechanism-based strategies for preventing or controlling breast cancer

    The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

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    This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics
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