Fatigue investigation at high load ratio R of a quenched and tempered chromium molybdenum steel

Abstract The fatigue behavior at high number of cycles in elastic-plastic field of quenched and tempered carbon chromium steel was experimentally investigated for high performance reciprocating compressors application. Fatigue tests on un-notched specimens were performed both under load and strain controls, by imposing different levels of stress/strain and for each of them different values of stress ratios R, especially high values. Stress and strain trends have been monitored, during the fatigue life, and either ratcheting or relaxation, respectively, was evident. The stress control tests have resulted into fatigue fractures only for low values of R with significant ratcheting and an increasing rate during the final part of the test, thus the fracture could be considered as a synergy between fatigue damage and plastic failure. On the contrary, the ratcheting stabilized for high values of R and the tests were finalized without any fracture. Within an intermediate region, for medium/high values of R, a minor ratcheting and the fracture transition have been found. Similarly, for the tests under strain control, low values of R showed fatigue fractures despite a considerable relaxation, conversely for high values of R, the relaxation was limited without any fracture. After reporting the tests on the Haigh plane, the Smith-Watson-Topper equation (SWT) provided the best prediction of the fatigue strength, at least until the intersection with the ultimate stress line, both under stress and strain control loadings. The cyclic behavior of the material was then investigated through several static and cyclic tests on plain specimens. A kinematic hardening Chaboche model, with three parameter couples, was proposed and the values of these parameters derived and discussed. Finally, other tests have been conducted on notched specimens with C geometry and blunt radius, again at high R values. FE analysis allowed the prediction of the stress evolution during the loading cycling, implementing the Chaboche model, and observing a combined effect of ratcheting and relaxation at the notch tip. The stabilized stresses were finally reported on the Haigh diagram and the results were found in agreement with the plain specimen fatigue line

Processes of Acquisition in Individuals with High and Low Baseball Knowledge: The First Inning

This paper is concerned with the question of whether and why individuals who know more about a particular knowledge domain acquire domain-related information more readily than individuals who know less about the domain. A conceptual framework is presented that hypothesizes differences in the memory structure of the high-knowledge and low-knowledge individuals, primarily with respect to concepts, higher ordered conceptual groupings, goal structures, and related strategies. Acquisition differences between high-knowledge and low-knowledge individuals are assumed to be a function of differences in memory structure, and the primary factor involved in the acquisition of domain-related information is assumed to be a process termed structural mapping, i.e., encoding input information in terms of one's existing memory structure. The results of six experiments using male and female college students that were designed to study various aspects of the acquisition process are reported. The findings support the general framework and also emphasize the facilitative effect of conceptual differentiation and of context in the high-knowledge individuals

A Modular, Low Latency, A2B-based Architecture for Distributed Multichannel Full-Digital Audio Systems

Despite the increasing demand for multichannel audio systems, existing solutions are still mainly analog or audio-over-IP based, leading to well-known limitations: bulky wiring, high latency (0.5-2 ms), and expensive devices for protocol stack management. This paper presents a cost-effective, low latency, full-digital solution that overcomes all the previously mentioned problems. The proposed architecture is based on the new Automotive Audio Bus (A2B) protocol. It guarantees deterministic latency of 2 samples, 32 downstream/upstream channels over a single Unshielded Twisted Pair (UTP) cable and phase-aligned signals. A single A2B chip is required for each node, reducing dramatically the system cost. The developed architecture is composed by a main board and an A2B network. The main board handles up to 64 channels, and it converts standard protocols usually employed for audio signal delivery, such as AES10, AVB and AES67, into A2B streams and vice versa. The A2B network can include a series of devices, for instance power amplifiers, codecs, DSPs, and transducers. There are many application examples including, but not limited to, transducer arrays (e.g., microphone, loudspeaker, accelerometer arrays), audio distribution in meeting rooms, Wave Field Synthesis (WFS), Ambisonics immersive audio systems and Active Noise Control (ANC). A modular and portable WFS system was developed employing the above-described architecture. It is based on eight channels soundbars, which can be daisy-chained in reconfigurable geometries and featuring up to 192 channels

Older People Living in Nursing Homes: An Oral Health Screening Survey in Florence, Italy

The oral health state plays an important role in the concept of ‘elderly frailty’, since institutionalized older people are prone to suffering from bad oral conditions. The aim of this study is to assess the state of oral health in the older residents of nursing homes and to measure its potential association with the cognitive state, the degree of functional autonomy, and the malnutrition risk. Methods: We enrolled 176 subjects from 292 residents in five nursing homes in Florence. For each subject, we performed the Malnutrition Universal Screening Tool, the Pfeiffer test, the Minimum Data Set—Long Form, a dental examination, and the Geriatric Oral Health Assessment Index questionnaire. The results show that the oral condition was poor in 43.8% of cases, medium in 38.1%, and good in 18.2%. A worse oral health state was significantly associated (p < 0.05) with a worse cognitive state and with a higher dependency in daily living activities. The malnutrition score among the older people was unrelated to the oral health condition (p = 0.128). It can be concluded that the oral health condition in older institutionalized subjects is an open challenge for the public healthcare system, since the maintenance of adequate good oral health is an essential element of good physical as well as cognitive and psychological health

Linguistic and content validation of the translated and culturally adapted patient-generated subjective global assessment (PG-SGA)

The Patient-Generated Subjective Global Assessment (PG-SGA) is an instrument to screen, assess and monitor malnutrition and risk factors, and to triage for interventions. After having translated and culturally adapted the original PG-SGA for the Italian setting, according to International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Principles, we tested linguistic validity, i.e., perceived comprehensibility and difficulty, and content validity (relevance) of the Italian version of the PG-SGA in patients with cancer and a multidisciplinary sample of healthcare professionals (HCPs). Methods: After the translation and cultural adaptation of the original PG-SGA for the Italian setting, the patient component (i.e., PG-SGA Short Form (SF) was tested for linguistic validity (i.e., comprehensibility ad difficulty) in 120 Italian patients with cancer and 81 Italian HCPs. The full PG-SGA, i.e., patient and professional component of the PG-SGA, was tested for content validity, i.e., relevance, in 81 Italian HCPs. The data were collected by a questionnaire and evaluations were operationalized by a 4-point scale. Through item and scale indices we evaluated the comprehensibility (I–CI, S–CI), difficulty (I-DI, S-DI) and content validity (I-CVI, S-CVI). Scale indices 0.80–0.89 were considered acceptable, and scale indices ≥0.90 were considered excellent. Results: Patients perceived comprehensibility and difficulty of the PG-SGA SF (Boxes) as excellent (S–CI = 0.98, S-DI = 0.96). Professionals perceived comprehensibility of the professional component (Worksheets) as excellent (S–CI = 0.92), difficulty as acceptable (S-DI = 0.85), and content validity of the full PG-SGA as excellent (S-CVI = 0.92). Dietitians gave higher scores (indicating better scores) on comprehensibility, difficulty, and content validity of Worksheet 4 (physical exam) than the other professions. In Worksheet 4, four items were considered most difficult to complete and were considered below acceptable range. Relevance was perceived as excellent by professionals for both the patient component (S-CVI = 0.93) and the professional component (S-CVI = 0.90), resulting in S-CVI = 0.92 for the full PG-SGA. Slight textual modifications were implemented resulting in the final version of the Italian PG-SGA. Conclusions: Translation and cultural adaptation of the original PG-SGA resulted in the Italian version of the PG-SGA that maintained its original purpose and meaning and can be completed adequately and easily by patients and professionals. The Italian PG-SGA is considered relevant for screening, assessing and monitoring malnutrition and risk factors, as well as triaging for interventions by Italian HCPs.</p

Proton dynamics in cancer

Cancer remains a leading cause of death in the world today. Despite decades of research to identify novel therapeutic approaches, durable regressions of metastatic disease are still scanty and survival benefits often negligible. While the current strategy is mostly converging on target-therapies aimed at selectively affecting altered molecular pathways in tumor cells, evidences are in parallel pointing to cell metabolism as a potential Achilles' heel of cancer, to be disrupted for achieving therapeutic benefit. Critical differences in the metabolism of tumor versus normal cells, which include abnormal glycolysis, high lactic acid production, protons accumulation and reversed intra-extracellular pH gradients, make tumor site a hostile microenvironment where only cancer cells can proliferate and survive. Inhibiting these pathways by blocking proton pumps and transporters may deprive cancer cells of a key mechanism of detoxification and thus represent a novel strategy for a pleiotropic and multifaceted suppression of cancer cell growth

Health communication in covid-19 era: Experiences from the italian vaccinarsì network websites

In 2013, in a bid to combat Vaccine Hesitancy (VH) and provide information on vaccines by communicating with the general public and the health community (e.g., healthcare workers and public health operators), the Italian Society of Hygiene and Preventive Medicine (S.It.I.) published the national website “VaccinarSì”. The project was subsequently extended to ten Italian Regions. This led to the creation of the VaccinarSì Network, whose websites are publicly owned. The aim of this work was to present the framework of the websites of the VaccinarSì Network and to analyse user behaviour in the pre-COVID-19-era (dating from each website’s publication until 31 January 2020) and in the COVID-19-era (from 1 February 2020 to 31 January 2021). Some metrics such as the number of visits to the site (sessions, number of users and average session duration), user behaviour (pages viewed, bounce rate and organic search) and the session acquisition path (direct traffic, referrals and social traffic) were searched, extrapolated and processed with Google Analytics. Qualitative and normally distributed quantitative variables were summarised with their absolute (relative) frequencies and means. Statistical differences between the means of the two periods were evaluated through paired t-test. A two-tailed p-value less than 0.05 was considered to be statistically significant. When the total values recorded over the period were compared, an overall increase in metrics was observed—the number of individual users, visits and individual pageviews rose in a statistically significant way. Our study aimed to highlight how combining disciplines such as health education and digital communication via Information and Communication Technologies (ICT) represents the best strategy to support citizens. This approach gives them the tools to become independent and responsible players that are capable of voluntarily and consciously choosing to adhere to vaccination programs. The VaccinarSì Network’s goal for the future is to reach an even wider audience. By building each user’s critical knowledge, this network enables users to be active components of a wider, more empowered community