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Wu, Yan, Ding Guo Zhou, Si Qun Wang, Yang Zhang, Xin Wang und Hai Yan Mao. „Influence of Extruder Conditions on Mechanical Properties of Polypropylene Nanocomposites Reinforced with Rice Straw Micro/Nano Fibrils“. Advanced Materials Research 236-238 (Mai 2011): 1877–80. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1877.
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In this study, rice straw (Oryza sativa L.) fibril and fibril aggregates (RSFs) material isolated by high intensity ultrasonication (HIUS) was used as reinforcement in an RSFs/Polypropylene (PP) nanocomposites. The morphology of RSFs was investigated by scanning electron microscopy (SEM). The mechanical properties were evaluated by tensile test. The fourier transform infrared spectroscopy (FTIR) test was also performed to investigate the interface compatibility between RSFs and PP matrix. Results indicated that the tensile strength of RSFs/PP nanocomposites increased with increasing cycle time of extruder from 10 min to 30 min at 180°C. The maximum value of tensile strength was 31.2 MPa appeared at the conditions of 190°C and cycle 20 min. The elastic modulus increased by adding 5 wt% RSFs into the PP/MAPP matrix. However, there was no distinct difference of elongation in RSFs/PP nanocomposites at different extruder conditions. The RSFs embedded into the PP/MAPP matrix and exhibited better interaction by FTIR test.
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Fatkhullin, Bulat, Alexander Golubev, Natalia Garaeva, Shamil Validov, Azat Gabdulkhakov und Marat Yusupov. „Y98 Mutation Leads to the Loss of RsfS Anti-Association Activity in Staphylococcus aureus“. International Journal of Molecular Sciences 23, Nr. 18 (18.09.2022): 10931. http://dx.doi.org/10.3390/ijms231810931.
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Ribosomal silencing factor S (RsfS) is a conserved protein that plays a role in the mechanisms of ribosome shutdown and cell survival during starvation. Recent studies demonstrated the involvement of RsfS in the biogenesis of the large ribosomal subunit. RsfS binds to the uL14 ribosomal protein on the large ribosomal subunit and prevents its association with the small subunit. Here, we estimated the contribution of RsfS amino acid side chains at the interface between RsfS and uL14 to RsfS anti-association function in Staphylococcus aureus through in vitro experiments: centrifugation in sucrose gradient profiles and an S. aureus cell-free system assay. The detected critical Y98 amino acid on the RsfS surface might become a new potential target for pharmacological drug development and treatment of S. aureus infections.
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Christopherson, S. H., J. L. Anderson und D. M. Gustafson. „Evaluation of recirculating sand filter in a cold climate“. Water Science and Technology 51, Nr. 10 (01.05.2005): 267–72. http://dx.doi.org/10.2166/wst.2005.0375.
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Approximately 30% of Minnesota's residents rely on onsite technologies for their wastewater treatment. There is a growing need for ‘alternative, technologies to aid in treatment for difficult sites and sensitive environmental areas. Recirculating sand filters (RSFs) have been used since the 1970s for small communities with flows >20,000 L per day, but use for small flow application (<5,000 L/d) has been growing due to its small land use requirement. A research site was developed in southern Minnesota in 1995 to test alternative technologies, including two RSFs. In addition, in 1998, two RSFs were added to existing residential soil treatment systems that were having problems because of inadequate separation and fill soil conditions. All RSFs in this study used 0.6 metres of coarse sand for treatment, were loaded at approximately 204 L per day per square metre (5 gallons per square foot per day) and a recirculation rate of 5:1. All RSFs have effectively reduced Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Fecal Coliform (FC) and Nutrients (nitrogen and phosphorus). These systems are able to achieve secondary effluent treatment levels for BOD5 and TSS. The median FC reduction was 90% with a value of 5.7 E4 cfu/100 mL, indicating additional treatment is necessary to protect health and the environment. The RSFs consistently removed 25% or more total phosphorus (TP) and 40% or more total nitrogen (TN). The RSFs did not show significantly decreased performance during the winter months. Two of the RSFs receiving rather high strength domestic waste were able to reduce a greater percentage of total nitrogen, indicated that the addition of carbon from the high strength waste is a benefit resulting in greater TN removal.
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Wu, Yan, Ding Guo Zhou, Si Qun Wang, Yang Zhang, Yong Bao Shen und Zhi Hui Wu. „Mechanical and Thermal Properties of Poly(Vinyl Alcohol) Nanocomposite Material Reinforced with Rice Straw Fibril and Fibril Aggregates“. Advanced Materials Research 183-185 (Januar 2011): 1883–87. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.1883.
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Rice straw (Oryza sativa L.) pulp was treated by high intensity homogenizer to make fibril and fibril aggregates. The rice straw fibril and fibril aggregates (RSFs) material was used as reinforcement in a RSFs/ Poly (vinyl alcohol) (PVA) nanocomposite that prepared by film casting. The diameter distribution of RSFs was investigated by laser diameter instrument (LDI) and its crystallinity was evaluated by wide angle X-ray diffraction (WAXD). The morphological of RSFs was investigated by scanning electron microscopy (SEM). The mechanical properties were measured by tensile test and the dynamic mechanics analysis (DMA), thermal stability tests, i.e., differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) and the Fourier transform infrared spectroscopy (FTIR) test were also performed, respectively.
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Xu, Cong. „Impact of Strong Raman Self-Frequency Shift on Bound State of Dissipative Solitons“. International Journal of Optics 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/365648.
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Bound dissipative solitons are numerically studied by implementing strong Raman self-frequency shift (RSFS) in an all-normal-dispersion (ANDi) Yb-doped fiber laser. Results demonstrated that overstrong RSFS had no filter-like effect in the ANDi fiber laser when a bandpass filter was present in the intracavity. However, overstrong RSFS could cause the bandpass filter to destabilize the ANDi fiber laser. For the first time in the field, we have demonstrated that strong RSFS could destabilize bound DS pulses and generate noise-like bound pulses. Furthermore, the generation mechanism of destabilized noise-like bound pulses in the fiber laser with intracavity filter is different from the noise-like pulses in the fiber lasers without a bandpass filter.
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Zacharias, N., S. M. Essert, A. F. Brunsch, E. Christoffels, T. Kistemann und C. Schreiber. „Performance of retention soil filters for the reduction of hygienically-relevant microorganisms in combined sewage overflow and treated wastewater“. Water Science and Technology 81, Nr. 3 (01.02.2020): 535–43. http://dx.doi.org/10.2166/wst.2020.132.
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Abstract Environmental quality standards for surface waters have been significantly expanded through recent amendments to German regulations. Limit values are only established for applicable regulations if the water is indicated for certain uses, e.g. abstraction of irrigation water. Nevertheless, surface water bodies are often used for hygiene-sensitive purposes. In the course of climate change, stronger precipitation events will occur, which may lead to more frequent loading and discharge of combined sewer overflow (CSO) into surface water bodies. Retention soil filters (RSFs) are attracting attention as an extensive treatment technology for CSO and additional wastewater treatment. This study examined large-scale RSFs for CSO treatment, as well as the effectiveness of RSFs as a fourth purification stage. An RSF test facility was established at a municipal wastewater treatment plant (WWTP), consisting three semi-technical RSFs that were fed exclusively with treated water from the WWTP. The reduction of microorganisms mostly occurred within the first centimeters of the RSFs. For most hygienic-microbiological parameters, a 1–2 log unit reduction could be detected in addition to the reduction within the WWTP. Antibiotic-resistant bacteria were reduced to the same extent. Investigation of the large-scale RSFs showed that a flow rate reduced by half corresponded to better reduction performances.
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Darabi, Nazila, Abdalhossein Rezai und Seyedeh Shahrbanoo Falahieh Hamidpour. „BREAST CANCER DETECTION USING RSFS-BASED FEATURE SELECTION ALGORITHMS IN THERMAL IMAGES“. Biomedical Engineering: Applications, Basis and Communications 33, Nr. 03 (09.03.2021): 2150020. http://dx.doi.org/10.4015/s1016237221500204.
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Breast cancer is a common cancer in female. Accurate and early detection of breast cancer can play a vital role in treatment. This paper presents and evaluates a thermogram based Computer-Aided Detection (CAD) system for the detection of breast cancer. In this CAD system, the Random Subset Feature Selection (RSFS) algorithm and hybrid of minimum Redundancy Maximum Relevance (mRMR) algorithm and Genetic Algorithm (GA) with RSFS algorithm are utilized for feature selection. In addition, the Support Vector Machine (SVM) and k-Nearest Neighbors (kNN) algorithms are utilized as classifier algorithm. The proposed CAD system is verified using MATLAB 2017 and a dataset that is composed of breast images from 78 patients. The implementation results demonstrate that using RSFS algorithm for feature selection and kNN and SVM algorithms as classifier have accuracy of 85.36% and 75%, and sensitivity of 94.11% and 79.31%, respectively. In addition, using hybrid GA and RSFS algorithm for feature selection and kNN and SVM algorithms as classifier have accuracy of 83.87% and 69.56%, and sensitivity of 96% and 81.81%, respectively, and using hybrid mRMR and RSFS algorithms for feature selection and kNN and SVM algorithms as classifier have accuracy of 77.41% and 73.07%, and sensitivity of 98% and 72.72%, respectively.
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Kondo, Yuki, Ichiro Yoshida, Munetoshi Numada, Hiroyasu Koshimizu, Ryo Saito und Kaito Fujiyoshi. „Verification of Characteristics of Spline Filter Series Robust Filters for Surface Roughness and Proposal of Filter Selection Guidelines“. Applied Sciences 13, Nr. 6 (07.03.2023): 3390. http://dx.doi.org/10.3390/app13063390.
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In surface roughness measurements, the presence of spikes in the primary profile can disable a normal filter from extracting the shape and waviness components. The robust spline filter (RSF) has been proposed to solve this problem. However, because ISO 16610-32, an RSF standard, has a significant deficiency, it was withdrawn in the Technical Specifications stage. The other proposed RSFs only show the method and a few examples with normal roughness and spike. Therefore, because the characteristics of each RSF have not been clarified, which RSF should be used for which primary profiles is not clear. This is one of the reasons for the delay in establishing ISO. In addition, the measurement sites need the establishment of robust spline filter selection guidelines. Therefore, in this paper, the characteristics of RSFs are clarified. Additionally, the points to be considered in using RSFs are summarized. Finally, the filter that should be selected for the specific application is identified. These results are expected to contribute to the widespread use of RSFs in the industrial world, avoid confusion at the measurement site, and help establish a new RSF standard.
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Tian, Hongwei, Lin Cheng, Dongli Wu, Qingwei Wei und Liming Zhu. „Regional Monitoring of Leaf ChlorophyII Content of Summer Maize by Integrating Multi-Source Remote Sensing Data“. Agronomy 13, Nr. 8 (31.07.2023): 2040. http://dx.doi.org/10.3390/agronomy13082040.
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This study addresses the problem of restricted ability for large-scale monitoring due to the limited cruising time of unmanned aerial vehicles (UAV) by identifying an optimal leaf ChlorophyII content (LCC) inversion machine learning model at different scales and under different parameterization schemes based on simultaneous observations of ground sampling, UAV flight, and satellite imagery. The following results emerged: (1) The correlation coefficient between most remote sensing features (RSFs) and LCC increased as the remote scale expanded; thus, the scale error caused by the random position difference between GPS and measuring equipment should be considered in field sampling observations. (2) The LCC simulation accuracy of the UAV multi-spectral camera using four machine learning algorithms was ExtraTree > GradientBoost > AdaBoost > RandomForest, and the 20- and 30-pixel scales had better accuracy than the 10-pixel scale, while the accuracy for three feature combination schemes ranked combination of extremely significantly correlated RSFs > combination of significantly correlated and above RSFs > combination of all features. ExtraTree was confirmed as the optimal model with the feature combination of scheme 2 at the 20-pixel scale. (3) Of the Sentinel-2 RSFs, 27 of 28 were extremely significantly correlated with LCC, while original band reflectance was negatively correlated, and VIs were positively correlated. (4) The LCC simulation accuracy of the four machine learning algorithms ranked as ExtraTree > GradientBoost > RandomForest > AdaBoost. In a comparison of two parameterization schemes, scheme 1 had better accuracy, while ExtraTree was the best algorithm, with 11 band reflectance as input RSFs; the RMSE values for the training and testing data sets of 0.7213 and 1.7198, respectively.
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Jung, Sueun, und Jihyun Lee. „Exploring a Conceptual Framework of Koreans’ Residential Satisfaction Based on Maslow’s Human Needs: A Qualitative and Quantitative Integrated Study“. Sustainability 15, Nr. 19 (28.09.2023): 14312. http://dx.doi.org/10.3390/su151914312.
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Previous studies on residential satisfaction factors (RSFs) overlooked residents’ psychological needs. To bridge this gap, we linked RSFs to the Modified Maslow’s Hierarchy of Human Needs (MMHN) through a three-step qualitative and quantitative integrated analysis. First, RSFs were derived from the analysis of previous studies. Second, through an analytic hierarchy process and a focus group interview, RSFs and the MMHN were linked. Third, the MMHN-based model was applied to data from the 2020 Korea Housing Survey, and classification and regression tree analysis were performed to derive significant factors, which were then compared to significant factors from the conventional model. The comparative analysis results of the conventional and MMHN-based models were as follows: (1) The MMHN-based model presented significant factors in all five stages of human needs, reflecting various human needs. (2) The MMHN-based model assessed the housing needs of residents in the non-capital region in more detail. (3) The MMHN-based model investigated the differences in residential satisfaction factors between metropolitan and non-metropolitan regions more clearly. (4) Two factors influencing safety needs important in all regions in both models were deemed crucial for residential satisfaction. This study could support the customization of regional housing policies according to unique needs and life circumstances by region.
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Lytton, SD, B. Mester, I. Dayan, H. Glickstein, J. Libman, A. Shanzer und ZI Cabantchik. „Mode of action of iron (III) chelators as antimalarials: I. Membrane permeation properties and cytotoxic activity“. Blood 81, Nr. 1 (01.01.1993): 214–21. http://dx.doi.org/10.1182/blood.v81.1.214.214.
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Abstract We have designed two subfamilies of lipophilic iron (III) chelators previously termed reversed siderophores (RSFs). The agents display physicochemical properties that favor extraction of iron beyond membrane barriers of Plasmodium falciparum-infected red blood cells. We studied the in vitro antimalarial potency of RSFs and their relationship to the membrane permeation properties of these agents. The mode of RSF action involves: (1) fast access to intracellular compartments of parasitized cells; (2) selective and high-affinity chelation of iron (III) from parasitized cells; (3) fast exit from cells after iron (III) complexation; and (4) exertion of cell damage on parasites exposed for 3 to 5 hours to drugs, irrespective of the stage of parasite development. These results suggest that on reaching a critical intraerythrocyte target, RSFs induce an iron deficit that parasites in general, and rings in particular, have limited capacity to restore.
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Lytton, SD, B. Mester, I. Dayan, H. Glickstein, J. Libman, A. Shanzer und ZI Cabantchik. „Mode of action of iron (III) chelators as antimalarials: I. Membrane permeation properties and cytotoxic activity“. Blood 81, Nr. 1 (01.01.1993): 214–21. http://dx.doi.org/10.1182/blood.v81.1.214.bloodjournal811214.
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We have designed two subfamilies of lipophilic iron (III) chelators previously termed reversed siderophores (RSFs). The agents display physicochemical properties that favor extraction of iron beyond membrane barriers of Plasmodium falciparum-infected red blood cells. We studied the in vitro antimalarial potency of RSFs and their relationship to the membrane permeation properties of these agents. The mode of RSF action involves: (1) fast access to intracellular compartments of parasitized cells; (2) selective and high-affinity chelation of iron (III) from parasitized cells; (3) fast exit from cells after iron (III) complexation; and (4) exertion of cell damage on parasites exposed for 3 to 5 hours to drugs, irrespective of the stage of parasite development. These results suggest that on reaching a critical intraerythrocyte target, RSFs induce an iron deficit that parasites in general, and rings in particular, have limited capacity to restore.
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Tsafack, A., J. Libman, A. Shanzer und Z. I. Cabantchik. „Chemical Determinants of antimalarial activity of reversed siderophores.“ Antimicrobial Agents and Chemotherapy 40, Nr. 9 (September 1996): 2160–66. http://dx.doi.org/10.1128/aac.40.9.2160.
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Reversed siderophores (RSFs) are artificial hydroxamate-based iron chelators designed after the natural siderophore ferrichrome. The modular molecular design of RSF derivatives allowed the synthesis of various congeners with controlled iron-binding capacities and partition coefficients. These two physicochemical properties were assessed by a novel fluorescent method and were found to be the major determinants of RSF permeation across erythrocyte membranes and scavenging of compartmentalized iron. The partition coefficient apparently conferred upon RSFs two major features: (i) the ability to rapidly access iron pools of in vitro-grown Plasmodium falciparum at all developmental stages and to mobilize intracellular iron and transfer it to the medium and (ii) the ability to suppress parasite growth at all developmental stages. These features of RSFs were assessed by quantitative determination of the structure-activity relationships of the biological activities and partition coefficients spanning a wide range of values. The most effective RSF containing the aromatic group of phenylalanine (RSFm2phe) showed 50% inhibitory concentration of 0.60 +/- 0.03 nmol/ml in a 48-h test and a 2-h onset of inhibition of ring development at 5 nmol/ml. The lipophilic compound RSFm2phe and the lipophilic and esterase-cleavable compound RSFm2pee inhibited parasite growth at all developmental stages whether inhibition was assessed in a continuous mode or after discontinuing drug administration. The antimalarial effects of RSFm2phe and cleavable RSFm2pee were potentiated in the presence of desferrioxamine (DFO) at concentrations at which DFO alone had no effect on parasite growth. These studies provide experimental evidence indicating that the effective and persistent antimalarial actions of RSFs are associated with drug access to infected cells and scavenging of iron from intracellular parasites. Moreover, the optimal antimalarial actions of RSFs are apparently also determined by improved accessibility to critical iron pools or by specific interactions with critical parasite targets.
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Zia, Asad, Zhang Pu, Ivan Holly, Tariq Umar, Muhammad Atiq Ur Rehman Tariq und Muhammad Sufian. „A Comprehensive Review of Incorporating Steel Fibers of Waste Tires in Cement Composites and Its Applications“. Materials 15, Nr. 21 (22.10.2022): 7420. http://dx.doi.org/10.3390/ma15217420.
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Accumulating vast amounts of pollutants drives modern civilization toward sustainable development. Construction waste is one of the prominent issues impeding progress toward net-zero. Pollutants must be utilized in constructing civil engineering structures for a green ecosystem. On the other hand, large-scale production of industrial steel fibers (ISFs) causes significant damage to the goal of a sustainable environment. Recycled steel fibers (RSFs) from waste tires have been suggested to replace ISFs. This research critically examines RSF’s application in the mechanical properties’ improvement of concrete and mortar. A statistical analysis of dimensional parameters of RSFs, their properties, and their use in manufacturing various cement-based composites are given. Furthermore, comparative assessments are carried out among the improvements in compressive, split tensile, and flexural strengths of plain and RSF-incorporated concrete and mortar. In addition, the optimum contents of RSF for each strength property are also discussed. The influence of RSFs parameters on various strength properties of concrete and mortars is discussed. The possible applications of RSF for various civil engineering structures are reviewed. The limitations and errors noticed in previous review papers are also outlined. It is found that the maximum enhancement in compressive strength (CS), split tensile strength (STS), and flexure strength (FS) are 78%, 149%, and 157%, respectively, with the addition of RSF into concrete. RSF increased cement mortars’ CS, STS, and FS by 46%, 50.6%, and 69%, respectively. The current study encourages the building sector to use RSFs for sustainable concrete.
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Soltanzadeh, Fatemeh, Ali E. Behbahani, Kasra Hosseinmostofi und Carlos A. Teixeira. „Assessment of the Sustainability of Fibre-Reinforced Concrete by Considering Both Environmental and Mechanical Properties“. Sustainability 14, Nr. 10 (23.05.2022): 6347. http://dx.doi.org/10.3390/su14106347.
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The environmental consequences of human activities, e.g., the depletion of non-renewable fuel resources, consumption of natural raw materials, and release of huge amounts of CO2 into the atmosphere, resulted in new challenges in materials engineering. Based on these challenges, building materials must fulfil not only mechanical performance criteria, but also produce the least environmental impact accompanied by their production. In the present study, the possibility of employing scrap tire recycled steel fibres (RSF) as a substitution to industrial steel fibres (ISF) for developing more sustainable fibre-reinforced concretes was explored by adopting a life-cycle approach, integrated both environmental and mechanical properties. Four different fibre-reinforced self-compacting concretes–FRSCCs–were tailored by means of replacing the ISFs partially/totally (i.e., 0%, 50%, 67%, 100% by mass of) with the recycled ones. The effect of applying various dosages of RSFs on mechanical behavior of FRSCC–namely compressive, flexural, and splitting tensile responses–were evaluated experimentally. The environmental impacts associated with the production of each FRSCC were also assessed through life-cycle analysis. The potentiality of the RSFs to be used as concrete reinforcement with a comparable mechanical performance to that of ISF-reinforced concrete and lower environmental footprint was evaluated through a consolidated environmental and mechanical index (EM). In this study, using RSFs instead of industrial fibres for developing FRSCC has provided up to 37% higher EM index. The results confirmed the promising prospects for the application of RSFs in developing more eco-efficient and sustainable reinforced concrete.
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Popov, Elenko, Murtadha Almusafer, Arben Belba, Jibril O. Bello, Kamran Hassan Bhatti, Luca Boeri, Kaloyan Davidoff et al. „Obesity rates in renal stone formers from various countries“. Archivio Italiano di Urologia e Andrologia 93, Nr. 2 (30.06.2021): 189–94. http://dx.doi.org/10.4081/aiua.2021.2.189.
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Objective: To collect evidence on the rate of obesity in renal stone formers (RSFs) living in different climatic areas and consuming different diets. Materials and methods: Data of adult renal stone formers were retrospectively collected by members of U-merge from 13 participant centers in Argentina, Brazil, Bulgaria (2), China, India, Iraq (2), Italy (2), Nigeria, Pakistan and Poland. The following data were collected: age, gender, weight, height, stone analysis and procedure of stone removal. Results: In total, 1689 renal stone formers (1032 males, 657 females) from 10 countries were considered. Average age was 48 (±14) years, male to female ratio was 1.57 (M/F 1032/657), the average body mass index (BMI) was 26.5 (±4.8) kg/m2. The obesity rates of RSFs in different countries were significantly different from each other. The highest rates were observed in Pakistan (50%), Iraq (32%), and Brazil (32%), while the lowest rates were observed in China (2%), Nigeria (3%) and Italy (10%). Intermediate rates were observed in Argentina (17%), Bulgaria (17%), India (15%) and Poland (22%). The age-adjusted obesity rate of RSFs was higher than the age-adjusted obesity rate in the general population in Brazil, India, and Pakistan, whereas it was lower in Argentina, Bulgaria, China, Italy, and Nigeria, and similar in Iraq and Poland. Conclusions: The age-adjusted obesity rate of RSFs was not higher than the age-adjusted obesity rate of the general population in most countries. The relationship between obesity and the risk of kidney stone formation should be reconsidered by further studies carried out in different populations.
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Jepsen, Jane U., Nina E. Eide, Pål Prestrud und Linn B. Jacobsen. „The importance of prey distribution in habitat use by arctic foxes (Alopex lagopus)“. Canadian Journal of Zoology 80, Nr. 3 (01.03.2002): 418–29. http://dx.doi.org/10.1139/z02-023.
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The use of habitat by reproducing arctic foxes (Alopex lagopus) in relation to prey distribution was examined on the Svalbard archipelago in the Norwegian High Arctic during 19871988 and 19972000 by means of VHF telemetry. The distribution and abundance of the main prey species of foxes was registered in 4 separate periods during summer. The availability of 9 habitat types was estimated on the basis of a classification of a Landsat-5 TM scene. Three resource areas that differed with regard to distribution and availability of prey, vegetation, and terrain were identified within the study area: (1) inland areas with no geese, (2) inland areas with geese present, and (3) coastal areas with bird cliffs. The use of resources by foxes was calculated in the 4 separate periods, as was the average speed of movement (m/h) of foxes and the distance between fox locations and their natal dens. Resource-selection functions (RSFs) calculated for individual animals showed that resource use was nonrandom and similar for foxes that lived within the same resource area. In inland areas in which resource availability was low but fairly stable (area 1), RSFs were simple and in some cases of low significance compared with a no-selection model. In inland areas with highly dynamic resources (area 2), RSFs were complex and resource use differed significantly between periods. In coastal areas (area 3), where resources were plentiful, highly concentrated, and stable, RSFs were of intermediate complexity and resource use differed less between periods.
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Miftakhov, Aynur Kamilevich, Roderic Gilles Claret Diabankana, Mikhail Frolov, Marat Miratovich Yusupov, Shamil Zavdatovich Validov und Daniel Mawuena Afordoanyi. „Persistence as a Constituent of a Biocontrol Mechanism (Competition for Nutrients and Niches) in Pseudomonas putida PCL1760“. Microorganisms 11, Nr. 1 (21.12.2022): 19. http://dx.doi.org/10.3390/microorganisms11010019.
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Competition for nutrients and niches (CNN) is known to be one of the mechanisms for biocontrol mostly exhibited by Pseudomonas strains. Phenotypic and full genome analysis revealed Pseudomonas putida PCL1760 controlling tomato foot and root rot (TFRR) solely through CNN mechanism. Although the availability of nutrients and motility are the known conditions for CNN, persistence of bacteria through dormancy by ribosomal hibernation is a key phenomenon to evade both biotic and abiotic stress. To confirm this hypothesis, rsfS gene knockout mutant of PCL1760 (SB9) was first obtained through genetic constructions and compared with the wild type PCL1760. Primarily, relative expression of rsfS in PCL1760 was conducted on tomato seedlings which showed a higher expression at the apical part (1.02 ± 0.18) of the plant roots than the basal (0.41 ± 0.13). The growth curve and persistence in ceftriaxone after the induction of starvation with rifampicin were performed on both strains. Colonization on the tomato root by CFU and qPCR, including biocontrol ability against Fusarium, was also tested. The growth dynamics of both PCL1760 and SB9 in basal and rich medium statistically did not differ (p ≤ 0.05). There was a significant difference observed in persistence showing PCL1760 to be more persistent than its mutant SB9, while SB9 (pJeM2:rsfS) was 221.07 folds more than PCL1760. In colonization and biocontrol ability tests, PCL1760 was dominant over SB9 colonizing and controlling TFRR (in total, 3.044 × 104 to 6.95 × 103 fg/µL and 55.28% to 30.24%, respectively). The deletion of the rsfS gene in PCL1760 reduced the persistence and effectiveness of the strain, suggesting persistence as one important characteristic of the CNN.
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Donoghue, Terence G., Oliver C. Zafiriou und Craig D. Taylor. „Retractable Surface-Following Sampler“. Marine Technology Society Journal 35, Nr. 2 (01.06.2001): 29–35. http://dx.doi.org/10.4031/002533201788001848.
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The design and use of a Retractable Surface-Following Sampler (RSFS) for chemical sampling, particularly of trace gases on depth scales smaller than the draft of the research platform, is discussed. The RSFS is compared to other vessel-tethered surface water sampling systems, such as buckets, bottes/rosettes, catamarans, hull intakes, and booms. The RSFS is a 5 m welded aluminum sampling boom with a hinge-mounted rolling trolley support at the inboard end; at the outboard end, floatation spheres support a scientific payload at fixed depths relative to the sea surface on an adjustable mount. The wheels of the trolley are confined in a deck-mounted track, allowing the boom to be quickly and easily deployed and retrieved using a pneumatic tugger, or fixed at an intermediate position that allows access for maintenance. Data and water sample lines from the instrument mount are secured within the boom, allowing continuous, controlled near-surface sampling at a distance from the ship's hull. Field data from a comparison of different water intake methods for carbon monoxide sampling, along with CTD and fluorometer data, exemplify typical uses of the system.
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Koper, Nicola, und Micheline Manseau. „A guide to developing resource selection functions from telemetry data using generalized estimating equations and generalized linear mixed models“. Rangifer 32, Nr. 2 (08.03.2012): 195. http://dx.doi.org/10.7557/2.32.2.2269.
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Resource selection functions (RSF) are often developed using satellite (ARGOS) or Global Positioning System (GPS) telemetry datasets, which provide a large amount of highly correlated data. We discuss and compare the use of generalized linear mixed-effects models (GLMM) and generalized estimating equations (GEE) for using this type of data to develop RSFs. GLMMs directly model differences among caribou, while GEEs depend on an adjustment of the standard error to compensate for correlation of data points within individuals. Empirical standard errors, rather than model-based standard errors, must be used with either GLMMs or GEEs when developing RSFs. There are several important differences between these approaches; in particular, GLMMs are best for producing parameter estimates that predict how management might influence individuals, while GEEs are best for predicting how management might influence populations. As the interpretation, value, and statistical significance of both types of parameter estimates differ, it is important that users select the appropriate analytical method. We also outline the use of k-fold cross validation to assess fit of these models. Both GLMMs and GEEs hold promise for developing RSFs as long as they are used appropriately.
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CRISTESCU, BOGDAN, GORDON B. STENHOUSE, MARC SYMBALUK, SCOTT E. NIELSEN und MARK S. BOYCE. „Wildlife habitat selection on landscapes with industrial disturbance“. Environmental Conservation 43, Nr. 4 (04.07.2016): 327–36. http://dx.doi.org/10.1017/s0376892916000217.
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SUMMARYTechnological advancements in remote sensing and telemetry provide opportunities for assessing the effects of expanding extractive industries on animal populations. Here, we illustrate the applicability of resource selection functions (RSFs) for modelling wildlife habitat selection on industrially-disturbed landscapes. We used grizzly bears (Ursus arctos) from a threatened population in Canada and surface mining as a case study. RSF predictions based on GPS radiocollared bears (nduring mining = 7; npost mining = 9) showed that males and solitary females selected areas primarily outside mineral surface leases (MSLs) during active mining, and conversely inside MSLs after mine closure. However, females with cubs selected areas within compared to outside MSLs irrespective of mining activity. Individual variability was pronounced, although some environmental- and human-related variables were consistent across reproductive classes. For males and solitary females, regional-scale RSFs yielded comparable results to site-specific models, whereas for females with cubs, modelling the two scales produced divergent results. While mine reclamation may afford opportunities for bear persistence, managing public access will likely decrease the risk of human-caused bear mortality. RSFs are powerful tools that merit widespread use in quantitative and visual investigations of wildlife habitat selection on industrially-modified landscapes, using Geographic Information System layers that precisely characterize site-specific conditions.
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Paudel, Gagan, und Marisa Di Sabatino. „Quantification of discharge gas to optimize discharge parameters for relative sensitivity factors (RSFs) determination by slow-flow glow discharge mass spectrometry (GDMS)“. Journal of Analytical Atomic Spectrometry 35, Nr. 11 (2020): 2748–57. http://dx.doi.org/10.1039/d0ja00281j.
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KANE, R. P., und I. B. T. LIMA. „Inter-annual variability of some river stream-flows and rainfalls in the Amazon basin“. MAUSAM 56, Nr. 3 (20.01.2022): 627–42. http://dx.doi.org/10.54302/mausam.v56i3.994.
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For four locations (Samuel, 9° S, 63° W; Balbina, 1° S, 59° W; Curua-Una, 13° S, 54° W; Tucurui, 4° S, 50° W) in the Amazon, the river stream-flows (RSF) were maximum during March, April and/or May and minimum during September-October, while rainfalls in similar areas had maximum earlier, in January-March. There were considerable year-to-year fluctuations, not always similar at all the locations. An examination of the two largest El Niño events (1982-83 and 1997-98) showed some effects at some locations during intervals when the El Niños were active, but some effects were seen even outside these active intervals. Some RSFs showed relationship with South Atlantic SST. A spectral analysis showed that ENSO indices had prominent periodicities at 7-9, ~6 years and QTO (Quasi-triennial oscillation, 3-4 years) and not so prominent periodicities in the QBO (Quasi-biennial oscillation, 2-3 years). These were only partially reflected in some RSFs. There is an indication that some hydrological QBOs may be related to stratospheric wind QBO. Besides QBO and QTO, the RSFs had significant periodicities in 7-14 years range, ~22 years and ~55 years. Long-term trends (23-year running means) were not linear and showed oscillations of ~0.2%, grossly dissimilar at the different locations.
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Zhao, Qing, Yang Zhang, Gang Wang, Lionel Hill, Jing-Ke Weng, Xiao-Ya Chen, Hongwei Xue und Cathie Martin. „A specialized flavone biosynthetic pathway has evolved in the medicinal plant,Scutellaria baicalensis“. Science Advances 2, Nr. 4 (April 2016): e1501780. http://dx.doi.org/10.1126/sciadv.1501780.
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Wogonin and baicalein are bioactive flavones in the popular Chinese herbal remedy Huang-Qin (Scutellaria baicalensisGeorgi). These specialized flavones lack a 4′-hydroxyl group on the B ring (4′-deoxyflavones) and induce apoptosis in a wide spectrum of human tumor cells in vitro and inhibit tumor growth in vivo in different mouse tumor models. Root-specific flavones (RSFs) fromScutellariahave a variety of reported additional beneficial effects including antioxidant and antiviral properties. We describe the characterization of a new pathway for the synthesis of these compounds, in which pinocembrin (a 4′-deoxyflavanone) serves as a key intermediate. Although two genes encoding flavone synthase II (FNSII) are expressed in the roots ofS.baicalensis, FNSII-1 has broad specificity for flavanones as substrates, whereas FNSII-2 is specific for pinocembrin. FNSII-2 is responsible for the synthesis of 4′-deoxyRSFs, such as chrysin and wogonin, wogonoside, baicalein, and baicalin, which are synthesized from chrysin. A gene encoding a cinnamic acid–specific coenzyme A ligase (SbCLL-7), which is highly expressed in roots, is required for the synthesis of RSFs by FNSII-2, as demonstrated by gene silencing. A specific isoform of chalcone synthase (SbCHS-2) that is highly expressed in roots producing RSFs is also required for the synthesis of chrysin. Our studies reveal a recently evolved pathway for biosynthesis of specific, bioactive 4′-deoxyflavones in the roots ofS.baicalensis.
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Raulerson, Calen R., Sudeep C. Popat und Scott M. Husson. „Water Recovery from Bioreactor Mixed Liquors Using Forward Osmosis with Polyelectrolyte Draw Solutions“. Membranes 12, Nr. 1 (31.12.2021): 61. http://dx.doi.org/10.3390/membranes12010061.
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This paper reports on the use of forward osmosis (FO) with polyelectrolyte draw solutions to recover water from bioreactor mixed liquors. The work was motivated by the need for new regenerative water purification technologies to enable long-duration space missions. Osmotic membrane bioreactors may be an option for water and nutrient recovery in space if they can attain high water flux and reverse solute flux selectivity (RSFS), which quantifies the mass of permeated water per mass of draw solute that has diffused from the draw solution into a bioreactor. Water flux was measured in a direct flow system using wastewater from a municipal wastewater treatment plant and draw solutions prepared with two polyelectrolytes at different concentrations. The direct flow tests displayed a high initial flux (>10 L/m2/h) that decreased rapidly as solids accumulated on the feed side of the membrane. A test with deionized water as the feed revealed a small mass of polyelectrolyte crossover from the draw solution to the feed, yielding an RSFS of 80. Crossflow filtration experiments demonstrated that steady state flux above 2 L/m2·h could be maintained for 70 h following an initial flux decline due to the formation of a foulant cake layer. This study established that FO could be feasible for regenerative water purification from bioreactors. By utilizing a polyelectrolyte draw solute with high RSFS, we expect to overcome the need for draw solute replenishment. This would be a major step towards sustainable operation in long-duration space missions.
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Gustine, D. D., und K. L. Parker. „Variation in the seasonal selection of resources by woodland caribou in northern British Columbia“. Canadian Journal of Zoology 86, Nr. 8 (August 2008): 812–25. http://dx.doi.org/10.1139/z08-047.
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Conservation planning for species of concern or importance can be aided by resource selection functions (RSFs) that identify important areas or attributes. Models that can be interpreted biologically and provide reasonable predictive capacity may best be based on data from individuals grouped into seasonal selection strategies for particular geographical areas or similarities in topographical and vegetative associations. We used logistic regression, the information–theoretic approach, satellite imagery, and locational data (n = 31 females; 16 803 locations) from global positioning system (GPS) collared woodland caribou ( Rangifer tarandus caribou (Gmelin, 1788)) to model resource selection by animals during calving, summer, fall, breeding, winter, and late-winter seasons. Higher variation in resource use corresponded to times when caribou and their young were most susceptible to predation or when food resources were limited. Even with multiple selection strategies, caribou followed a general progression from higher to lower elevation habitats from calving and summer to late winter. Caribou selected against or completely avoided the burned–disturbed vegetation class in every season except summer. We incorporated RSFs with a raster geographic information system to create selection landscapes. We validated selection landscapes using withheld GPS data (n = 6077), 50 known calving sites, and Spearman’s rank correlation coefficient. Selection models and final selection landscapes performed well in validating use locations of woodland caribou in all seasons (all P < 0.003) and in predicting known calving sites (P < 0.001). When seasonal selection strategies are identified and models are coupled with validation, RSFs are effective tools to assist in conservation planning.
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Fatkhullin, Bulat F., Azat G. Gabdulkhakov und Marat M. Yusupov. „Is RsfS a Hibernation Factor or a Ribosome Biogenesis Factor?“ Biochemistry (Moscow) 87, Nr. 6 (Juni 2022): 500–510. http://dx.doi.org/10.1134/s0006297922060025.
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Ye, Yun-guang, Da-chuan Shi, Sara Poveda-Reyes und Markus Hecht. „Quantification of the influence of rolling stock failures on track deterioration“. Journal of Zhejiang University-SCIENCE A 21, Nr. 10 (Oktober 2020): 783–98. http://dx.doi.org/10.1631/jzus.a2000033.
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AbstractThis study focuses on the quantification of the influence of rolling stock failures (RSFs) on railway infrastructure. Taking the wheel flat, a common RSF, as an example, we introduce four quantification indexes to evaluate the influence on the following four deterioration mechanisms: track settlement (TS), track component fatigue (TCF), abrasive wear (AW), and rolling contact fatigue (RCF). Our results indicate that TS, TCF, and AW increase sharply with the increase of the wheel flat length and the vehicle speed, and this increasing trend becomes more acute with the increase of the wheel flat length and the vehicle speed. At low speeds, RCF increases gradually as the wheel flat length increases; at high speeds, it increases sharply at first and then decreases gradually. The influence of the wheel flat on TCF and AW is the most obvious, followed by TS and RCF. These findings can help infrastructure managers (IMs) to better understand infrastructure conditions related to RSFs and can aid them in managing problems with vehicle abnormality in track access charging.
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Teodorescu, Horia-Nicolai. „Reprinted from RSFS magazine: The history of fuzzy systems in Romania“. Fuzzy Sets and Systems 36, Nr. 3 (Juli 1990): 401–2. http://dx.doi.org/10.1016/0165-0114(90)90113-k.
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Chow, Fotini Katopodes, Robert L. Street, Ming Xue und Joel H. Ferziger. „Explicit Filtering and Reconstruction Turbulence Modeling for Large-Eddy Simulation of Neutral Boundary Layer Flow“. Journal of the Atmospheric Sciences 62, Nr. 7 (01.07.2005): 2058–77. http://dx.doi.org/10.1175/jas3456.1.
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Abstract Standard turbulence closures for large-eddy simulations of atmospheric flow based on finite-difference or finite-volume codes use eddy-viscosity models and hence ignore the contribution of the resolved subfilter-scale stresses. These eddy-viscosity closures are unable to produce the expected logarithmic region near the surface in neutral boundary layer flows. Here, explicit filtering and reconstruction are used to improve the representation of the resolvable subfilter-scale (RSFS) stresses, and a dynamic eddy-viscosity model is used for the subgrid-scale (SGS) stresses. Combining reconstruction and eddy-viscosity models yields a sophisticated (and higher order) version of the well-known mixed model of Bardina et al.; the explicit filtering and reconstruction procedures clearly delineate the contribution of the RSFS and SGS motions. A near-wall stress model is implemented to supplement the turbulence models and account for the stress induced by filtering near a solid boundary as well as the effect of the large grid aspect ratio. Results for neutral boundary layer flow over a rough wall using the combined dynamic reconstruction model and the near-wall stress model show excellent agreement with similarity theory logarithmic velocity profiles, a significant improvement over standard eddy-viscosity closures. Stress profiles also exhibit the expected pattern with increased reconstruction level.
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Street, Garrett M., Lucas M. Vander Vennen, Tal Avgar, Anna Mosser, Morgan L. Anderson, Arthur R. Rodgers und John M. Fryxell. „Habitat selection following recent disturbance: model transferability with implications for management and conservation of moose (Alces alces)“. Canadian Journal of Zoology 93, Nr. 11 (November 2015): 813–21. http://dx.doi.org/10.1139/cjz-2015-0005.
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Site-specific variation in relative habitat abundance and disturbance regimes may produce differences in habitat preferences of associated populations. An evaluation of the predictive power of habitat selection models across space would benefit our understanding of the reliability of models of selection and space use in predicting animal occurrence. We used presence–absence data from winter surveys of moose (Alces alces (L., 1758)) to estimate resource selection functions (RSFs) across two study sites using Far North Land Cover updated with recent disturbance from fire and timber harvest. Moose selected foraging habitat (e.g., deciduous land cover) and for increasing deciduous foliage cover (ΔNDVI, i.e., the difference in the normalized difference vegetation index). Snow depth negatively influenced habitat selection, likely due to increased predation risk and reduced movement and foraging efficiency. Models lost little predictive power when applied to another site based on comparison of receiver operating characteristic (ROC) curves. Our results corroborated the current body of knowledge concerning moose habitat selection, i.e., moose preferentially use forest stands dominated by deciduous species, but suggested that moose strongly avoided very recently disturbed areas. Minimal site-specific variation and ROC comparison suggests that RSFs may be extended into novel systems, given adequate consideration for habitat quality and abundance, thereby simplifying management needs of this important species.
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Jones, Nicholas E., und William M. Tonn. „Resource selection functions for age-0 Arctic grayling (Thymallus arcticus) and their application to stream habitat compensation“. Canadian Journal of Fisheries and Aquatic Sciences 61, Nr. 9 (01.09.2004): 1736–46. http://dx.doi.org/10.1139/f04-116.
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We developed resource selection functions (RSFs) for young-of-the-year (YOY) Arctic grayling (Thymallus arcticus) in a natural Barrenlands stream and used them to assess the habitat in an artificial stream created as part of a habitat compensation agreement in the Canadian Arctic. The model for small (1521 mm) grayling explained 55% of the variation in habitat use and included water velocity, average water depth, and percentage of detritus and fines. The model for large (3857 mm) grayling explained 36% of the variation in habitat use and included water depth, percentage of detritus and fines, and several cover variables. Model validation using a withheld sample of data indicated that the models provided good fits to the data, correctly classifying 7175% of habitat-use locations. Applying the RSFs to observed habitat use in the artificial stream indicated an abundance of quality habitat for small grayling, but a paucity for the larger YOY. These results reflect an ontogenetic shift in habitat requirements, from the simple needs of small YOY to the more complex demands of larger YOY, demands that could not be well met by the artificial stream. We suggest that this inability contributed to the poor productive capacity of the artificial stream.
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Saher, D. Joanne, und Fiona K. A. Schmiegelow. „Movement pathways and habitat selection by woodland caribou during spring migration“. Rangifer 25, Nr. 4 (01.05.2005): 143. http://dx.doi.org/10.7557/2.25.4.1779.
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Woodland caribou (Rangifer tarandus caribou) are a threatened species throughout Canada. Special management is therefore required to ensure habitat needs are met, particularly because much of their current distribution is heavily influenced by resource extraction activities. Although winter habitat is thought to be limiting and is the primary focus of conservation efforts, maintaining connectivity between summer and winter ranges has received little attention. We used global positioning system data from an interprovincial, woodland caribou herd to define migratory movements on a relatively pristine range. Non-linear models indicated that caribou movement during migration was punctuated; caribou traveled for some distance (movement phase) followed by a pause (resting/foraging phase). We then developed resource selection functions (RSFs), using case-controlled logistic regression, to describe resting/foraging sites and movement sites, at the landscape scale. The RSFs indicated that caribou traveled through areas that were less rugged and closer to water than random and that resting/foraging sites were associated with older forests that have a greater component of pine, and are further from water than were random available locations. This approach to analyzing animal location data allowed us to identify two patterns of habitat selection (travel and foraging/resting) for caribou during the migratory period. Resultant models are important tools for land use planning to ensure that connectivity between caribou summer and winter ranges is maintained.
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Huang, L. Q., R. J. Conzemius und R. S. Houk. „Relative Ionization Yields for Impurity Elements in Laser Mass Spectrometry of Steels and Brasses“. Applied Spectroscopy 41, Nr. 4 (Mai 1987): 667–70. http://dx.doi.org/10.1366/0003702874448715.
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Relative sensitivity factors (RSF) are studied for impurity elements in metal samples with the use of laser mass spectrometry in the power density range of 1 to 3 × 109 W cm−2 for the focused laser beam. Metallic impurities are found to have RSFs near unity, while nonmetallic impurities are less efficiently ionized relative to iron. The results indicate uniform sensitivities for all the elements may be expected as the power density reaches 5 × 10' 109 cm−2, in agreement with earlier studies.
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Usero, R., A. G. Coedo, M. T. Dorado und I. Padilla. „Influence of Different Metal Matrices on Manganese Signal Response in Laser Ablation Inductively Coupled Plasma—Mass Spectrometry“. Applied Spectroscopy 63, Nr. 8 (August 2009): 859–64. http://dx.doi.org/10.1366/000370209788964539.
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Laser ablation inductively coupled plasma–mass spectrometry (LA-ICP-MS) is applied for the quantitative determination of manganese concentration in metal samples. A set of Certified Reference Materials, with different matrix elements (Fe, Cu, Ni, Co, Al) and with certified Mn values, were analyzed. Absorption and plasma break-down depend on the solid phase; as a result, there are differences in mass ablation rates that influence the Mn signal response. In order to be able to compare Mn signals, the relative element-dependent response of tested metal matrices was determined from the ablation of Fe, Cu, Ni, Co, and Al pure metal targets. Relative sensitivity factors (RSFs), calculated as the ratio of the signal intensity of 59Co, 58Ni, 63Cu, and 27Al to the signal intensity of 56Fe, were: 0.79, 0.71, 0.74, and 0.51, respectively. All the isotope signals were matched to the value that should correspond to the relative abundance of 56Fe (91.75%). These experimentally determined RSFs were applied for compensating the observed differences. For quantitative measurements a set of CRM carbon steel samples (SS-451/1 to SS-460/1), with Fe contents of approximately 98%, was used for calibration. The samples with different matrices were measured using the main matrix element as internal standard; for this purpose, the measured intensity was firstly extrapolated, from their content in the sample, to the value that should correspond to a content of 98% and, after, was corrected with the calculated RSF. The developed quantification approach provides manganese results with deviations of 5–10% from the certified values, with relative standard deviations of 3–8%.
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Movahedi, Mahsa, Nicholas Zoulias, Stuart A. Casson, Peng Sun, Yun-Kuan Liang, Alistair M. Hetherington, Julie E. Gray und Caspar C. C. Chater. „Stomatal responses to carbon dioxide and light require abscisic acid catabolism in Arabidopsis“. Interface Focus 11, Nr. 2 (12.02.2021): 20200036. http://dx.doi.org/10.1098/rsfs.2020.0036.
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In plants, stomata control water loss and CO 2 uptake. The aperture and density of stomatal pores, and hence the exchange of gases between the plant and the atmosphere, are controlled by internal factors such as the plant hormone abscisic acid (ABA) and external signals including light and CO 2 . In this study, we examine the importance of ABA catabolism in the stomatal responses to CO 2 and light. By using the ABA 8′-hydroxylase-deficient Arabidopsis thaliana double mutant cyp707a1 cyp707a3 , which is unable to break down and instead accumulates high levels of ABA, we reveal the importance of the control of ABA concentration in mediating stomatal responses to CO 2 and light. Intriguingly, our experiments suggest that endogenously produced ABA is unable to close stomata in the absence of CO 2 . Furthermore, we show that when plants are grown in short day conditions ABA breakdown is required for the modulation of both elevated [CO 2 ]-induced stomatal closure and elevated [CO 2 ]-induced reductions in leaf stomatal density. ABA catabolism is also required for the stomatal density response to light intensity, and for the full range of light-induced stomatal opening, suggesting that ABA catabolism is critical for the integration of stomatal responses to a range of environmental stimuli.
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Rossetti, Tom, Stephanie Jackvony, Jochen Buck und Lonny R. Levin. „Bicarbonate, carbon dioxide and pH sensing via mammalian bicarbonate-regulated soluble adenylyl cyclase“. Interface Focus 11, Nr. 2 (12.02.2021): 20200034. http://dx.doi.org/10.1098/rsfs.2020.0034.
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Soluble adenylyl cyclase (sAC; ADCY10) is a bicarbonate (HCO 3 − )-regulated enzyme responsible for the generation of cyclic adenosine monophosphate (cAMP). sAC is distributed throughout the cell and within organelles and, as such, plays a role in numerous cellular signalling pathways. Carbonic anhydrases (CAs) nearly instantaneously equilibrate HCO 3 − , protons and carbon dioxide (CO 2 ); because of the ubiquitous presence of CAs within cells, HCO 3 − -regulated sAC can respond to changes in any of these factors. Thus, sAC can function as a physiological HCO 3 − /CO 2 /pH sensor. Here, we outline examples where we have shown that sAC responds to changes in HCO 3 − , CO 2 or pH to regulate diverse physiological functions.
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Casalino-Matsuda, S. Marina, Sergejs Berdnikovs, Naizhen Wang, Aisha Nair, Khalilah L. Gates, Greg J. Beitel und Peter H. S. Sporn. „Hypercapnia selectively modulates LPS-induced changes in innate immune and DNA replication-related gene transcription in the macrophage“. Interface Focus 11, Nr. 2 (12.02.2021): 20200039. http://dx.doi.org/10.1098/rsfs.2020.0039.
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Hypercapnia, the elevation of CO 2 in blood and tissues, commonly occurs in severe acute and chronic respiratory diseases and is associated with increased risk of death. Recent studies have shown that hypercapnia inhibits expression of select innate immune genes and suppresses host defence against bacterial and viral pneumonia in mice. In the current study, we evaluated the effect of culture under conditions of hypercapnia (20% CO 2 ) versus normocapnia (5% CO 2 ), both with normoxia, on global gene transcription in human THP-1 and mouse RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). We found that hypercapnia selectively downregulated transcription of LPS-induced genes associated with innate immunity, antiviral response, type I interferon signalling, cytokine signalling and other inflammatory pathways in both human and mouse macrophages. Simultaneously, hypercapnia increased expression of LPS-downregulated genes associated with mitosis, DNA replication and DNA repair. These CO 2 -induced changes in macrophage gene expression help explain hypercapnic suppression of antibacterial and antiviral host defence in mice and reveal a mechanism that may underlie, at least in part, the high mortality of patients with severe lung disease and hypercapnia.
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Masterson, Claire, Shahd Horie, Sean D. McCarthy, Hector Gonzalez, Declan Byrnes, Jack Brady, Juan Fandiño, John G. Laffey und Daniel O'Toole. „Hypercapnia in the critically ill: insights from the bench to the bedside“. Interface Focus 11, Nr. 2 (12.02.2021): 20200032. http://dx.doi.org/10.1098/rsfs.2020.0032.
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Carbon dioxide (CO 2 ) has long been considered, at best, a waste by-product of metabolism, and at worst, a toxic molecule with serious health consequences if physiological concentration is dysregulated. However, clinical observations have revealed that ‘permissive’ hypercapnia, the deliberate allowance of respiratory produced CO 2 to remain in the patient, can have anti-inflammatory effects that may be beneficial in certain circumstances. In parallel, studies at the cell level have demonstrated the profound effect of CO 2 on multiple diverse signalling pathways, be it the effect from CO 2 itself specifically or from the associated acidosis it generates. At the whole organism level, it now appears likely that there are many biological sensing systems designed to respond to CO 2 concentration and tailor respiratory and other responses to atmospheric or local levels. Animal models have been widely employed to study the changes in CO 2 levels in various disease states and also to what extent permissive or even directly delivered CO 2 can affect patient outcome. These findings have been advanced to the bedside at the same time that further clinical observations have been elucidated at the cell and animal level. Here we present a synopsis of the current understanding of how CO 2 affects mammalian biological systems, with a particular emphasis on inflammatory pathways and diseases such as lung specific or systemic sepsis. We also explore some future directions and possibilities, such as direct control of blood CO 2 levels, that could lead to improved clinical care in the future.
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Chen, Stephanie Turner, Joel Kowalewski und Anandasankar Ray. „Prolonged activation of carbon dioxide-sensitive neurons in mosquitoes“. Interface Focus 11, Nr. 2 (12.02.2021): 20200043. http://dx.doi.org/10.1098/rsfs.2020.0043.
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Many insects can detect carbon dioxide (CO 2 ) plumes using a conserved receptor made up of members of the gustatory receptor (Gr) family Gr1, Gr2 and Gr3. Mosquitoes are attracted to host animals for blood meals using plumes of CO 2 in the exhaled breath using the receptor expressed in the A neuron of the capitate peg sensilla type on the maxillary palps. The receptor is known to also detect several other classes of odorants, including ones emitted from human skin. Here, we discover that a common skin odorant, butyric acid, can cause a phasic activation followed by an unusually prolonged tonic activity after the stimulus is over in the CO 2 neurons of mosquitoes. The effect is conserved in both Aedes aegypti and Anopheles gambiae mosquitoes. This raises a question about its role in a mosquito's preference for the skin odour of different individuals. Butyric acid belongs to a small number of odorants known to cause the prolonged activation of the CO 2 receptor. A chemical informatic analysis identifies a specific set of physico-chemical features that can be used in a machine learning predictive model for the prolonged activators. Interestingly, this set is different from physico-chemical features selected for activators or inhibitors, indicating that each has a distinct structural basis. The structural understanding opens up an opportunity to find novel ligands to manipulate the CO 2 receptor and mosquito behaviour.
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Linthwaite, Victoria L., Eoin Cummins und Martin J. Cann. „Carbon dioxide detection in biological systems“. Interface Focus 11, Nr. 2 (12.02.2021): 20210001. http://dx.doi.org/10.1098/rsfs.2021.0001.
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Phelan, D. E., C. Mota, C. Lai, S. J. Kierans und E. P. Cummins. „Carbon dioxide-dependent signal transduction in mammalian systems“. Interface Focus 11, Nr. 2 (12.02.2021): 20200033. http://dx.doi.org/10.1098/rsfs.2020.0033.
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Carbon dioxide (CO 2 ) is a fundamental physiological gas known to profoundly influence the behaviour and health of millions of species within the plant and animal kingdoms in particular. A recent Royal Society meeting on the topic of ‘Carbon dioxide detection in biological systems' was extremely revealing in terms of the multitude of roles that different levels of CO 2 play in influencing plants and animals alike. While outstanding research has been performed by leading researchers in the area of plant biology, neuronal sensing, cell signalling, gas transport, inflammation, lung function and clinical medicine, there is still much to be learned about CO 2 -dependent sensing and signalling. Notably, while several key signal transduction pathways and nodes of activity have been identified in plants and animals respectively, the precise wiring and sensitivity of these pathways to CO 2 remains to be fully elucidated. In this article, we will give an overview of the literature relating to CO 2 -dependent signal transduction in mammalian systems. We will highlight the main signal transduction hubs through which CO 2 -dependent signalling is elicited with a view to better understanding the complex physiological response to CO 2 in mammalian systems. The main topics of discussion in this article relate to how changes in CO 2 influence cellular function through modulation of signal transduction networks influenced by pH, mitochondrial function, adenylate cyclase, calcium, transcriptional regulators, the adenosine monophosphate-activated protein kinase pathway and direct CO 2 -dependent protein modifications. While each of these topics will be discussed independently, there is evidence of significant cross-talk between these signal transduction pathways as they respond to changes in CO 2 . In considering these core hubs of CO 2 -dependent signal transduction, we hope to delineate common elements and identify areas in which future research could be best directed.
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Salmerón, Cristina, Till S. Harter, Garfield T. Kwan, Jinae N. Roa, Salvatore D. Blair, Jodie L. Rummer, Holly A. Shiels, Greg G. Goss, Rod W. Wilson und Martin Tresguerres. „Molecular and biochemical characterization of the bicarbonate-sensing soluble adenylyl cyclase from a bony fish, the rainbow trout Oncorhynchus mykiss“. Interface Focus 11, Nr. 2 (12.02.2021): 20200026. http://dx.doi.org/10.1098/rsfs.2020.0026.
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Soluble adenylyl cyclase (sAC) is a HC O 3 − -stimulated enzyme that produces the ubiquitous signalling molecule cAMP, and deemed an evolutionarily conserved acid–base sensor. However, its presence is not yet confirmed in bony fishes, the most abundant and diverse of vertebrates. Here, we identified sAC genes in various cartilaginous, ray-finned and lobe-finned fish species. Next, we focused on rainbow trout sAC (rtsAC) and identified 20 potential alternative spliced mRNAs coding for protein isoforms ranging in size from 28 to 186 kDa. Biochemical and kinetic analyses on purified recombinant rtsAC protein determined stimulation by HC O 3 − at physiologically relevant levels for fish internal fluids (EC 50 ∼ 7 mM). rtsAC activity was sensitive to KH7, LRE1, and DIDS (established inhibitors of sAC from other organisms), and insensitive to forskolin and 2,5-dideoxyadenosine (modulators of transmembrane adenylyl cyclases). Western blot and immunocytochemistry revealed high rtsAC expression in gill ion-transporting cells, hepatocytes, red blood cells, myocytes and cardiomyocytes. Analyses in the cell line RTgill-W1 suggested that some of the longer rtsAC isoforms may be preferentially localized in the nucleus, the Golgi apparatus and podosomes. These results indicate that sAC is poised to mediate multiple acid–base homeostatic responses in bony fishes, and provide cues about potential novel functions in mammals.
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Dale, Nicholas. „CO 2 sensing by connexin26 and its role in the control of breathing“. Interface Focus 11, Nr. 2 (12.02.2021): 20200029. http://dx.doi.org/10.1098/rsfs.2020.0029.
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Breathing is essential to provide the O 2 required for metabolism and to remove its inevitable CO 2 by-product. The rate and depth of breathing is controlled to regulate the excretion of CO 2 to maintain the pH of arterial blood at physiological values. A widespread consensus is that chemosensory cells in the carotid body and brainstem measure blood and tissue pH and adjust the rate of breathing to ensure its homeostatic regulation. In this review, I shall consider the evidence that underlies this consensus and highlight historical data indicating that direct sensing of CO 2 also plays a significant role in the regulation of breathing. I shall then review work from my laboratory that provides a molecular mechanism for the direct detection of CO 2 via the gap junction protein connexin26 (Cx26) and demonstrates the contribution of this mechanism to the chemosensory regulation of breathing. As there are many pathological mutations of Cx26 in humans, I shall discuss which of these alter the CO 2 sensitivity of Cx26 and the extent to which these mutations could affect human breathing. I finish by discussing the evolution of the CO 2 sensitivity of Cx26 and its link to the evolution of amniotes.
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Clarke, Victoria C., Florence R. Danila und Susanne von Caemmerer. „CO 2 diffusion in tobacco: a link between mesophyll conductance and leaf anatomy“. Interface Focus 11, Nr. 2 (12.02.2021): 20200040. http://dx.doi.org/10.1098/rsfs.2020.0040.
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The partial pressure of CO 2 at the sites of carboxylation within chloroplasts depends on the conductance to CO 2 diffusion from intercellular airspace to the sites of carboxylation, termed mesophyll conductance ( g m ). We investigated how g m varies with leaf age and through a tobacco ( Nicotiana tabacum ) canopy by combining gas exchange and carbon isotope measurements using tunable diode laser spectroscopy. We combined these measurements with the anatomical characterization of leaves. CO 2 assimilation rate, A , and g m decreased as leaves aged and moved lower in the canopy and were linearly correlated. This was accompanied by large anatomical changes including an increase in leaf thickness. Chloroplast surface area exposed to the intercellular airspace per unit leaf area ( S c ) also decreased lower in the canopy. Older leaves had thicker mesophyll cell walls and g m was inversely proportional to cell wall thickness. We conclude that reduced g m of older leaves lower in the canopy was associated with a reduction in S c and a thickening of mesophyll cell walls.
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Shigemura, Masahiko, und Jacob I. Sznajder. „Elevated CO 2 modulates airway contractility“. Interface Focus 11, Nr. 2 (12.02.2021): 20200021. http://dx.doi.org/10.1098/rsfs.2020.0021.
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Carbon dioxide (CO 2 ), a primary product of oxidative metabolism, can be sensed by eukaryotic cells eliciting unique responses via specific signalling pathways. Severe lung diseases such as chronic obstructive pulmonary disease are associated with hypoventilation that can lead to the elevation of CO 2 levels in lung tissues and the bloodstream (hypercapnia). However, the pathophysiological effects of hypercapnia on the lungs and specific lung cells are incompletely understood. We have recently reported using combined unbiased molecular approaches with studies in mice and cell culture systems on the mechanisms by which hypercapnia alters airway smooth muscle contractility. In this review, we provide a pathophysiological and mechanistic perspective on the effects of hypercapnia on the lung airways and discuss the recent understanding of high CO 2 modulation of the airway contractility.
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Michenkova, Marie, Sara Taki, Matthew C. Blosser, Hyea J. Hwang, Thomas Kowatz, Fraser J. Moss, Rossana Occhipinti et al. „Carbon dioxide transport across membranes“. Interface Focus 11, Nr. 2 (12.02.2021): 20200090. http://dx.doi.org/10.1098/rsfs.2020.0090.
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Carbon dioxide (CO 2 ) movement across cellular membranes is passive and governed by Fick's law of diffusion. Until recently, we believed that gases cross biological membranes exclusively by dissolving in and then diffusing through membrane lipid. However, the observation that some membranes are CO 2 impermeable led to the discovery of a gas molecule moving through a channel; namely, CO 2 diffusion through aquaporin-1 (AQP1). Later work demonstrated CO 2 diffusion through rhesus (Rh) proteins and NH 3 diffusion through both AQPs and Rh proteins. The tetrameric AQPs exhibit differential selectivity for CO 2 versus NH 3 versus H 2 O, reflecting physico-chemical differences among the small molecules as well as among the hydrophilic monomeric pores and hydrophobic central pores of various AQPs. Preliminary work suggests that NH 3 moves through the monomeric pores of AQP1, whereas CO 2 moves through both monomeric and central pores. Initial work on AQP5 indicates that it is possible to create a metal-binding site on the central pore's extracellular face, thereby blocking CO 2 movement. The trimeric Rh proteins have monomers with hydrophilic pores surrounding a hydrophobic central pore. Preliminary work on the bacterial Rh homologue AmtB suggests that gas can diffuse through the central pore and three sets of interfacial clefts between monomers. Finally, initial work indicates that CO 2 diffuses through the electrogenic Na/HCO 3 cotransporter NBCe1. At least in some cells, CO 2 -permeable proteins could provide important pathways for transmembrane CO 2 movements. Such pathways could be amenable to cellular regulation and could become valuable drug targets.
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Linthwaite, Victoria L., und Martin J. Cann. „A methodology for carbamate post-translational modification discovery and its application in Escherichia coli“. Interface Focus 11, Nr. 2 (12.02.2021): 20200028. http://dx.doi.org/10.1098/rsfs.2020.0028.
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Carbon dioxide can influence cell phenotypes through the modulation of signalling pathways. CO 2 regulates cellular processes as diverse as metabolism, cellular homeostasis, chemosensing and pathogenesis. This diversity of regulated processes suggests a broadly conserved mechanism for CO 2 interactions with diverse cellular targets. CO 2 is generally unreactive but can interact with neutral amines on protein under normal intracellular conditions to form a carbamate post-translational modification (PTM). We have previously demonstrated the presence of this PTM in a subset of protein produced by the model plant species Arabidopsis thaliana . Here, we describe a detailed methodology for identifying new carbamate PTMs in an extracted soluble proteome under biologically relevant conditions. We apply this methodology to the soluble proteome of the model prokaryote Escherichia coli and identify new carbamate PTMs . The application of this methodology, therefore, supports the hypothesis that the carbamate PTM is both more widespread in biology than previously suspected and may represent a broadly relevant mechanism for CO 2 –protein interactions.
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Traff, Jordan, und David J. Daegling. „What does ‘toughness’ look like? An examination of the breakdown of young and mature leaves under cyclical loading“. Interface Focus 11, Nr. 5 (13.08.2021): 20200087. http://dx.doi.org/10.1098/rsfs.2020.0087.
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The material property of leaf toughness is considered the crucial mechanical challenge facing folivorous primates. Mature leaves have higher recorded toughness values than young leaves on average, leading to many assumptions about the patterning of food breakdown that follow a tough/not-tough dichotomy. We tested three hypotheses about how leaves break down under repetitive loading cycles, predicting that mature leaves (i) experience more force during simulated occlusal loads, (ii) more effectively resist fragmentation into small pieces, and (iii) show a more gradual decline in resistance over consecutive cycles than young leaves. Under displacement control using a mechanical testing system, we subjected young and mature leaves to 20 cycles of axial loading using interlocking steel wedges, then collected and quantified the size of the leaf fragments. While we found that mature leaves experienced more overall force than young leaves ( p < 0.001), they also shattered into smaller pieces ( p = 0.004) and showed a steeper decline in their resistance to the cycles over the course of a test ( p < 0.01). These results suggest that putatively ‘tougher’ foods (i.e. mature versus young leaves) do not necessarily resist fragmentation as commonly assumed. The current tough/not-tough paradigm of primate foods may not accurately reflect how leaves break down during masticatory behaviour.
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Hammerberg, Alexandra G., und Patricia Ann Kramer. „Consistent inconsistencies in braking: a spatial analysis“. Interface Focus 11, Nr. 5 (13.08.2021): 20200058. http://dx.doi.org/10.1098/rsfs.2020.0058.
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The dynamic system that is the bipedal body in motion is of interest to engineers, clinicians and biological anthropologists alike. Spatial statistics is more familiar to public health researchers as a way of analysing disease clustering and spread; nonetheless, this is a practical approach to the two-dimensional topography of the foot. We quantified the clustering of the centre of pressure (CoP) on the foot for peak braking and propulsive vertical ground reaction forces (GRFs) over multiple, contiguous steps to assess the consistency of the location of peak forces on the foot during walking. The vertical GRFs of 11 participants were collected continuously via a wireless insole system (MoticonReGo AG) across various experimental conditions. We hypothesized that CoPs would cluster in the hindfoot for braking and forefoot for propulsion, and that braking would demonstrate more consistent clustering than propulsion. Contrary to our hypotheses, we found that CoPs during braking are inconsistent in their location, and CoPs during propulsion are more consistent and clustered across all participants and all trials. These results add to our understanding of the applied forces on the foot so that we can better predict fatigue failures and better understand the mechanisms that shaped the modern bipedal form.