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Why are muscles strong, and why do they require little energy in eccentric action?

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Journal of Sport and Health Science 2018年第3期7卷 255-264页

作者： walter Herzog Human Performance Laboratory Faculty of Kinesiology University of Calgary

It is well acknowledged that muscles that are elongated while activated(i.e.,eccentric muscle action)are stronger and require less energy(per unit of force)than muscles that are shortening(i.e.,concentric contraction)or that remain at a constant length(i.e.,isometric contraction).Although the cross-bridge theory of muscle contraction provides a good explanation for the increase in force in active muscle lengthening,it does not explain the residual increase in force following active lengthening(residual force enhancement),or except with additional assumptions,the reduced metabolic requirement of muscle during and following active *** from the cross-bridge theory,2 other primary explanations for the mechanical properties of actively stretched muscles have emerged:(1)the so-called sarcomere length nonuniformity theory and(2)the engagement of a passive structural element *** this article,these theories are discussed,and it is shown that the last of these—the engagement of a passive structural element in eccentric muscle action—offers a simple and complete explanation for many hitherto unexplained observations in actively lengthening *** by no means fully proven,the theory has great appeal for its simplicity and beauty,and even if over time it is shown to be wrong,it nevertheless forms a useful framework for direct hypothesis testing.

关键词： Cross-bridge theory Eccentric Force-length relationship Residual force enhancement Titin

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Antecedent Precipitation Index to Estimate Soil Moisture and Correlate as a Triggering Process in the Occurrence of Landslides

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International Journal of Geosciences 2024年第1期15卷 70-86页

作者： Marcio Augusto Ernesto De Moraes walter Manoel Mendes Filho Rodolfo Moreda Mendes Cassiano Antonio Bortolozo Daniel Metodiev Marcio Roberto Magalhães De Andrade Harideva Marturano Egas Tatiana Sussel Gonçalves Mendes Luana Albertani Pampuch CEMADEN - National Centre for Monitoring and Early Warnings of Natural Disasters General Coordination of Research and Development S&#227o José dos Campos Brazil Faculty of Science and Technology Goias Federal University Aparecida de Goi&#226nia Brazil Institute of Science and Technology S&#227o Paulo State University (Unesp) S&#227o José dos Campos Brazil

Landslides are highly dangerous phenomena that occur in different parts of the world and pose significant threats to human populations. Intense rainfall events are the main triggering process for landslides in urbanized slope regions, especially those considered high-risk areas. Various other factors contribute to the process;thus, it is essential to analyze the causes of such incidents in all possible ways. Soil moisture plays a critical role in the Earth’s surface-atmosphere interaction systems;hence, measurements and their estimations are crucial for understanding all processes involved in the water balance, especially those related to landslides. Soil moisture can be estimated from in-situ measurements using different sensors and techniques, satellite remote sensing, hydrological modeling, and indicators to index moisture conditions. Antecedent soil moisture can significantly impact runoff for the same rainfall event in a watershed. The Antecedent Precipitation Index (API) or “retained rainfall,” along with the antecedent moisture condition from the Natural Resources Conservation Service, is generally applied to estimate runoff in watersheds where data is limited or unavailable. This work aims to explore API in estimating soil moisture and establish thresholds based on landslide occurrences. The estimated soil moisture will be compared and calibrated using measurements obtained through multisensor capacitance probes installed in a high-risk area located in the mountainous region of Campos do Jordão municipality, São Paulo, Brazil. The API used in the calculation has been modified, where the recession coefficient depends on air temperature variability as well as the climatological mean temperature, which can be considered as losses in the water balance due to evapotranspiration. Once the API is calibrated, it will be used to extrapolate to the entire watershed and consequently estimate soil moisture. By utilizing recorded mass movements and comparing them with AP

关键词： Landslides Antecedent Precipitation Index Soil Moisture Threshold Water Balance

Improved State-Based Peridynamic Lattice Model Including Elasticity, Plasticity and Damage

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Computer Modeling in Engineering & Sciences 2018年第9期116卷 323-347页

作者： Siavash Nikravesh walter Gerstle Department of Civil Construction and Environmental EngineeringUniversity of New MexicoAlbuquerqueNMUSA

In this study,a recently developed peridynamic lattice model called the“Statebased Peridynamic Lattice Model”(SPLM)is improved and *** the SPLM,rather than as a continuum,solids are simulated using a close-packed lattice of peridynamically interacting *** new SPLM approach advances the SPLM model by improving the damage and plasticity ***,plasticity and damage are coupled in this approach.A robust method for damage initiation is developed.A new damage model called the“two-spring damage model”allows damage to localize to a single lattice particle,thus allowing highly localized damage(cracks)to emerge in a realistic manner.A plasticity model that includes hardening,softening,and damage due to plasticity is proposed and *** boundary effects are modeled efficiently and *** improved SPLM method is then employed to simulate three common concrete laboratory tests:uniaxial tension,uniaxial compression,and the Brazilian split cylinder *** SPLM results are then compared with results from the earlier SPLM model,with simplified classical predictions,and with laboratory *** solving the same benchmark problems using various lattice rotations and lattice spacings,the approach is demonstrated to be sufficiently objective to be a useful engineering tool to predict the essentially random behavior of concrete laboratory *** improved SPLM demonstrates significant improvements over the previously published version and is found to simulate concrete structures accurately and efficiently using far less computational effort than comparable computational simulation methods.

关键词： Peridynamics SPLM lattice damage plasticity fracture concrete

Clinical features and epidemiology of spondyloarthritides associated with inflammatory bowel disease

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World Journal of Gastroenterology 2009年第20期15卷 2449-2455页

作者： Carlo Salvarani walter Fries Rheumatology Unit Department of Interna Medicine Department of Internal Medicine and MedicaTherapy University of Messina

Inflammation of axial and/or peripheral joints is one of the most frequent extra-intestinal manifestations complicating the clinical course and therapeutic approach in inflammatory bowel diseases(IBD).The frequency of these complications seems to be similar for both diseases, Crohn's disease and ulcerative *** associated with IBD belongs to the category of *** involvement ranges from isolated inflammatory back pain to ankylosing spondylitis, whereas peripheral arthritis is noted in pauciarticular and in polyarticular *** radiological involvement of the sacroiliac joints is reported to occur in up to 50% of *** musculoskeletal manifestations such as buttock pain, dactylitis, calcaneal enthesitis, and thoracic pain are frequently underdiagnosed and, consequently, are not treated *** diagnostic approaches and criteria have been proposed over the past 40 years in an attempt to correctly classify and diagnose such *** correct recognition of spondylarthropathies needs an integrated multidisciplinary approach in order to identify common therapeutic strategies, especially in the era of the new biologic therapies.

关键词： Crohn disease Ankylosing spondylitis Ulcerative colitis Spondylarthropathies Arthritis Enthesopathy

Indentation Size Effect inβCuAlBe and Cu-2Be Alloys

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Acta Metallurgica Sinica(English Letters) 2021年第12期34卷 1669-1678页

作者： Susana Montecinos Sebastian Tognana walter Salgueiro IFIMAT Facultad de Ciencias ExactasUniversidad Nacional del Centro de La Provincia de Buenos AiresPinto 3997000 TandilArgentina Consejo Nacional de Investigaciones Científicas y Técnicas CONICET Av.Rivadavia 1917C1033AAJ Buenos AiresArgentina CIFICEN(UNCPBA-CICPBA-CONICET) Pinto 3997000 TandilArgentina Comisión de Investigaciones Científicas de la Provincia de Bs.As Calle 526 entre 10 y 111900 La PlataArgentina

The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe *** in the load-depth curves at different loads would suggest a change in the behavior of the materials as the load *** was estimated at different loads taking into account the pile-up in each case,which was estimated from the images of the topography obtained by atomic force microscopy(AFM).The effect of the microstructure of Cu-2Be(wt%)samples on the ISE was also *** each copper alloy,the Nix and Gao model was applied to the hardness-depth curves,and significant differences were found for the parameters *** is in the constant nanohardness regime for depths below 500 nm,while microhardness exhibits the ISE *** behavior of the nanohardness and the plastic strain with the depth is almost *** presents the lowest values of plastic strains due to the pseudoelastic effect,while Cu presents an almost constant value around 8%,which corresponds to the highest plastic strain obtained.

关键词： Hardness Pseudoelasticity Copper alloys Plasticity Indentation size effect

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Normal families and fixed points of iterates

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Science China Mathematics 2010年第3期53卷 593-596页

作者： BERGWEILER walter Mathematisches Seminar der Christian–Albrechts–Universitt zu Kiel

Let F be a family of holomorphic functions and suppose that there exists ε > 0 such that if f ∈ F, then |(f 2 ) (ξ)|≤4-ε for all fixed points ξ of the second iterate f 2 . We show that then F is normal. This is deduced from a result which says that if p is a polynomial of degree at least 2, then p 2 has a fixed point ξ such that |(p 2 ) (ξ)|≥4. The results are motivated by a problem posed by Yang Lo.

关键词： fixed point multiplier normality iteration periodic point

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Inflammatory bowel disease-associated spondyloarthropathies

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World Journal of Gastroenterology 2009年第20期15卷 2441-2442页

作者： walter Fries Department of Internal Medicine and MedicaTherapy University of Messina

This issue presents a symposium held in Messina talking about inflammatory bowel disease(IBD) and associated *** topic covers epidemiology and clinical manifestations of IBD-related arthropathies, common genetic and immunologic features, combined therapies for gut and joint inflammation, and future biologic therapies etc.I believe this series of articles will deeply facilitate understanding of and the approach to IBD and associated arthropathies.

关键词： Inflammatory bowel disease Spondylo-arthropathies Anti-tumor necrosis factor α

Fat poetry: a kingdom for PPARγ

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Cell Research 2007年第6期17卷 486-511页

作者： Silvia I Anghel walter Wahli Center for Integrative Genomics National Research Center Frontiers in GeneticsUniversity of LausanneLausanne CH-1015Switzerland

Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cel-lular components with highly specialized and complex functions. In addition to managing the most important energyreserve of the body, it secretes a multitude of soluble proteins called adipokines, which have beneficial or, alternatively,deleterious effects on the homeostasis of the whole body. The expression of these adipokines is an integrated responseto various signals received from many organs, which depends heavily on the integrity and physiological status of theadipose tissue. One of the main regulators of gene expression in fat is the transcription factor peroxisome proliferator-activated receptor γ （PPARγ）, which is a fatty acid- and eicosanoid-dependent nuclear receptor that plays key roles inthe development and maintenance of the adipose tissue. Furthermore, synthetic PPARγagonists are therapeutic agentsused in the treatment of type 2 diabetes. This review discusses recent knowledge on the link between fat physiology and metabolic diseases, and the roles ofPPARγin this interplay via the regulation of lipid and glucose metabolism. Finally, we assess the putative benefits oftargeting this nuclear receptor with still-to-be-identified highly selective PPARγmodulators.

关键词： adipose tissue energy homeostasis obesity peroxisome proliferator-activated receptor

Evaluating the Impact of the Universal Test and Treat Strategy on the Survival of Patients in the Northwest Region of Cameroon

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World Journal of AIDS 2024年第3期14卷 45-60页

作者： Emmanuel Mboh Nshom Bereynuy Jude Cholong Kum Kang walter Khan Eveline Mboh Keng Vitalis Noela F. Ijang Gwendoline Nkenu Nsom Mirabel Mbueh Vifeme Esther Bonje Kuni Monju Johnson Vishi Gladys Enih Fosah Pius Muffih Tih AIDS Care and Prevention Program Cameroon Baptist Convention Health Services Bamenda Cameroon Regional Technical Group for the Fight against HIV and AID Northwest Region Cameroon

Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This study aims to assess the survival of antiretroviral therapy (ART) patients initiated under UTT in Northwest region of Cameroon. Methods: This retrospective cohort study included HIV-positive patients initiated in 2016 at 27 purposefully selected sites and followed until 2021. Data was anonymously abstracted from ART registers and patients’ charts. Kaplan-Meier survival estimates and Cox model were used to compare the survival of patients initiated under UTT with those initiated otherwise, using stata version 14.0. Results: In total, 2490 HIV-positive patients (median age 42.7 years, 94.7% adults, and 69.0% female) participated in the study. Of 1389 patients with viral load (VL) test results, 55% were initiated on ART late. The VL suppression rate of patients initiated late and those initiated early were similar. During follow-up, 1020 (40.9%) participants censored. The survival curves of patients initiated early on ART and those initiated late were similar during the first 2.5 years of follow-up but significantly (p Conclusions: This study confirms the expected impact of UTT. Programs only need to close existing implementation gaps along the critical pathways (diagnosis and treatment) of UTT, focusing more on males.

关键词： Universal Test and Treat Viral Load Survival Northwest Cameroon