Sources of Excitation and Models for Cylindrical Gear Dynamics: A Review

In this paper, a review of the evolution of the study of cylindrical gear dynamics is presented. After a brief historical introduction to the field, the first attempts to describe the complex interactions in those systems are analyzed introducing the dynamic factor and the first methodologies used to compute it. Next, the sources of excitation in geared systems are analyzed in detail and the models of the various contributions are discussed. Then, the paper focuses on the use of those sources in several dynamic models which are wildly different in terms of scope, applicability, complexity and methodology employed, ranging from simple analytical models, to lumped masses models up to multibody and finite element models. Finally, an outlook to the future evolution of the field is given and conclusions are drawn

A proposal of a unique formula for computing compliance in bolted joints

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2D/3D Nonlinear and Non-Hertzian Tooth Deflection Analysis for Compliant Gear Dynamics

L'abstract è presente nell'allegato / the abstract is in the attachmen

Gear Teeth Deflection Model for Spur Gears: Proposal of a 3D Nonlinear and Non-Hertzian Approach

In this paper, a three-dimensional model for the estimation of the deflections, load sharing attributes, and contact conditions will be presented for pairs of meshing teeth in a spur gear trans- mission. A nonlinear iterative approach based on a semi-analytical formulation for the deformation of the teeth under load will be employed to accurately determine the point of application of the load, its intensity, and the number of contacting pairs without a priori assumptions. At the end of this iterative cycle the obtained deflected shapes are then employed to compute the pressure distributions through a contact mechanics model with non-Hertzian features and a technique capable of obtaining correct results even at the free edges of the finite length contacting bodies. This approach is then applied to a test case with excellent agreement with its finite element counterpart. Finally, several results are shown to highlight the influence on the quasi-static behavior of spur gears of different kinds and amounts of flank and face-width profile modifications

Proposal of a novel approach for 3D tooth contact analysis and calculation of the static transmission error in loaded gears

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A proposal of a technique for correlating defect dimensions to vibration amplitude in bearing monitoring

The capability of early stage detection of a defect is gaining more and more importance because it can help the maintenance process, the cost reduction and the reliability of the systems. The increment of vibration amplitude is a well-known method for evaluating the damage of a component, but it is sometimes difficult to understand the exact level of damage. In other words, the amplitude of vibration cannot be directly connected to the dimension of the defect. In the present paper, based on a non-Hertzian contact algorithm, the spectrum of the pressure distribution in the contact surface between the race and the rolling element is evaluated. Such spectrum is then compared with the acquired spectrum of a vibration response of a defected bearing. The bearing vibration pattern was previously analyzed with monitoring techniques to extract all the damage information. The correlation between the spectrum of the pressure distribution in the defected contact surface and the analyzed spectrum of the damaged bearing highlights a strict relationship. By using that analysis, a precise correlation between defect aspect and dimension and vibration level can be addressed to estimate the level of damaging

Ilioinguinal nerve neurectomy is better than preservation in lichtenstein hernia repair. A systematic literature review and meta-analysis

Objective This study aimed to evaluate the incidence of chronic groin pain (primary outcome) and alterations of sensitivity (secondary outcome) after Lichtenstein inguinal hernia repair, comparing neurectomy with ilioinguinal nerve preservation surgery. Summary background data The exact cause of chronic groin postoperative pain after mesh inguinal hernia repair is usually unclear. Section of the ilioinguinal nerve (neurectomy) may reduce postoperative chronic pain. Methods We followed PRISMA guidelines to identify randomized studies reporting comparative outcomes of neurectomy versus ilioinguinal nerve preservation surgery during Lichtenstein hernia repairs. Studies were identified by searching in PubMed, Scopus, and Web of Science from April 2020. The protocol for this systematic review and meta-analysis was submitted and accepted from PROSPERO: CRD420201610. Results In this systematic review and meta-analysis, 16 RCTs were included and 1550 patients were evaluated: 756 patients underwent neurectomy (neurectomy group) vs 794 patients underwent ilioinguinal nerve preservation surgery (nerve preser- vation group). All included studies analyzed Lichtenstein hernia repair. The majority of the new studies and data comes from a relatively narrow geographic region; other bias of this meta-analysis is the suitability of pooling data for many of these studies. A statistically significant percentage of patients with prosthetic inguinal hernia repair had reduced groin pain a 6 months after surgery at 8.94% (38/425) in the neurectomy group versus 25.11% (113/450) in the nerve preservatio group [relative risk (RR) 0.39, 95% confidence interval (CI) 0.28–0.54; Z = 5.60 (P 0.00001)]. Neurectomy did no significantly increase the groin paresthesia 6 months after surgery at 8.5% (30/353) in the neurectomy group versu 4.5% (17/373) in the nerve preservation group [RR 1.62, 95% CI 0.94–2.80; Z = 1.74 (P = 0.08)]. At 12 months afte surgery, there is no advantage of neurectomy over chronic groin pain; no significant differences were found in th 12-month postoperative groin pain rate at 9% (9/100) in the neurectomy group versus 17.85% (20/112) in the inguina nerve preservation group [RR 0.50, 95% CI 0.24–1.05; Z = 1.83 (P = 0.07)]. One study (115 patients) reported dat about paresthesia at 12 months after surgery (7.27%, 4/55 in neurectomy group vs. 5%, 3/60 in nerve preservatio group) and results were not significantly different between the two groups [RR 1.45, 95% CI 0.34, 6.21;Z = 0.5 (P = 0.61)]. The subgroup analysis of the studies that identified the IIN showed a significant reduction of the 6th mont evaluation of pain in both groups and confirmed the same trend in favor of neurectomy reported in the previous overal analysis: statistically significant reduction of pain 6 months after surgery at 3.79% (6/158) in the neurectomy grou versus 14.6% (26/178) in the nerve preservation group [RR 0.28, 95% CI 0.13–0.63; Z = 3.10 (P = 0.002)]. Conclusion Ilioinguinal nerve identification in Lichtenstein inguinal hernia repair is the fundamental step to reduce or avoid postoperative pain. Prophylactic ilioinguinal nerve neurectomy seems to offer some advantages concerning pain in the first 6th month postoperative period, although it might be possible that the small number of cases contributed to the insignificancy regarding paresthesia and hypoesthesia. Nowadays, prudent surgeons should discuss with patients and their families the uncertain benefits and the potential risk of neurectomy before performing the hernioplasty

The lymphatic drain of below-knee malignant melanoma. Is the popliteal fossa a ghost station?

Sentinel lymph node biopsy is fundamental in the staging of primary cutaneous melanoma (PCL), but reported lymphoscintigraphic patterns are very heterogeneous. In this systematic review, we evaluated the role of the popliteal station in below-knee PCL. A systematic search of literature through was conducted on the electronic databases PubMed, SCOPUS and Web of Science (WOS) to identify eligible studies. A total of 22 studies (n=5,673 patients) were included. The average Breslow thickness of PCL was 2.86 mm. During the analysis of the included articles, it was not possible to classify patients into the 3 Menes popliteal drainage pattern, obtained by lymphoscintigraphy. The analysis of lymphatic drainage in patients undergoing lymphoscintigraphy for melanoma of the lower extremities below the knee was reported in 5,637 patients and the lymphatic popliteal drainage was reported only in 5.64% (320 patients). The rate of popliteal lymph nodes melanoma metastases was 1.48%: they were located exclusively at the popliteal level in 0.60%, at the popliteal and inguinal levels in 0.39%, at the popliteal and iliac level in 0.02% and at the groin level in 0.48%. In conclusion, the most common lymphoscintigraphic pattern is represented by popliteal nodes in-transit or interval nodes, so metastases from below-knee melanomas commonly transit through popliteal nodes stations and arrive to inguinal nodes stations. The popliteal nodes are the primary station in about 5.64% of cases. Larger studies are needed to corroborate these findings

Services écosystémiques et dis-services associés aux systèmes pastoraux de Patagonie, Argentine – Revue bibliographique

Pastoral systems worldwide secure rural livelihoods in the harshest environments on Earth. Their low productivity per area unit or head makes them the subject of much criticism with regard to their environmental impact, particularly in relation to global warming, desertification and land degradation. Such is the case of the traditional pastoral systems of Patagonia, a vast and isolated region where sedentary and mobile pastoralism coexist and contribute to shape landscapes and cultures. We argue that pastoral systems provide a wide range of ecosystem services that may compensate for their negative impact on the environment. We review the scarcely available evidence from Patagonia to identify ecosystem services and disservices associated with pastoralism, and pay special attention to the carbon balance: with C footprints between 10 to 40 kg CO2-eq.kg-1 carcass, pastoral systems in dry Patagonia are below or within the range of semi-extensive livestock systems worldwide (35-45 CO2-eq. kg-1 carcass). To inform development and policy, the assessment of trade-offs and synergies between ecosystem services needs to incorporate the intertwined social and ecological dynamics of complex pastoral systems, along resource regenerative trajectories.Les systèmes pastoraux du monde entier garantissent des moyens de subsistance aux ruraux dans les environnements les plus difficiles de la planète. Leur faible productivité par unité de surface ou par habitant suscite de nombreuses critiques quant à leur impact environnemental, notamment en relation avec le réchauffement climatique, la désertification et la dégradation des terres. C’est le cas des systèmes pastoraux traditionnels de Patagonie, une région vaste et isolée où le pastoralisme sédentaire et nomade coexistent et contribuent à façonner les paysages et les cultures. Nous soutenons que les systèmes pastoraux fournissent un large éventail de services écosystémiques qui peuvent compenser leur impact négatif sur l’environnement. Nous passons en revue les données disponibles sur la Patagonie pour identifier les services écosystémiques et les dis-services associés au pastoralisme, en accordant une attention particulière au bilan carbone : avec des empreintes carbone entre 10 et 40 kg CO2-éq/kg de viande, les systèmes pastoraux en Patagonie aride sont en dessous ou dans la gamme des systèmes d’élevage semi-extensifs dans le monde (35–45 éq-CO2/kg de viande). Pour éclairer les options de développement et les politiques, l’évaluation des compromis et des synergies entre services écosystémiques doit intégrer l’entrelacement de dynamiques sociales et écologiques, dans des systèmes pastoraux complexes, au fil de trajectoires de régénération des ressources.Fil: Tittonell, Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Hara, Sofía María. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Alvarez, Valeria Esther. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Aramayo, Valeria. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Bruzzone, Octavio Augusto. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Easdale, Marcos Horacio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Enriquez, Andrea Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Laborda, Luciana. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Trinco, Fabio Daniel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Villagra, Edgar Sebastián. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: El Mujtar, Verónica Andrea. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentin

Artificial Intelligence Predictive Models of Response to Cytotoxic Chemotherapy Alone or Combined to Targeted Therapy for Metastatic Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

Simple Summary Metastatic colorectal cancer (mCRC) has high incidence and mortality. Nevertheless, innovative biomarkers have been developed for predicting the response to therapy. We have examined the ability of learning methods to build prognostic and predictive models to predict response to chemotherapy, alone or combined with targeted therapy in mCRC patients, by targeting specific narrative publications. After a literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. We showed that all investigations conducted in this field provided generally promising results in predicting the response to therapy or toxic side-effects, using a meta-analytic approach. We found that radiomics and molecular biomarker signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Our study supports the use of computer science for developing personalized treatment decision processes for mCRC patients. Tailored treatments for metastatic colorectal cancer (mCRC) have not yet completely evolved due to the variety in response to drugs. Therefore, artificial intelligence has been recently used to develop prognostic and predictive models of treatment response (either activity/efficacy or toxicity) to aid in clinical decision making. In this systematic review, we have examined the ability of learning methods to predict response to chemotherapy alone or combined with targeted therapy in mCRC patients by targeting specific narrative publications in Medline up to April 2022 to identify appropriate original scientific articles. After the literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. Our results show that all investigations conducted on this field have provided generally promising results in predicting the response to therapy or toxic side-effects. By a meta-analytic approach we found that the overall weighted means of the area under the receiver operating characteristic (ROC) curve (AUC) were 0.90, 95% C.I. 0.80-0.95 and 0.83, 95% C.I. 0.74-0.89 in training and validation sets, respectively, indicating a good classification performance in discriminating response vs. non-response. The calculation of overall HR indicates that learning models have strong ability to predict improved survival. Lastly, the delta-radiomics and the 74 gene signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Specifically, when we evaluated the predictive models with tests reaching 80% sensitivity (SE) and 90% specificity (SP), the delta radiomics showed an SE of 99% and an SP of 94% in the training set and an SE of 85% and SP of 92 in the test set, whereas for the 74 gene signatures the SE was 97.6% and the SP 100% in the training set