210 research outputs found

    Application of unmanned aerial vehicle data and discrete fracture network models for improved rockfall simulations

    Get PDF
    In this research, we present a new approach to define the distribution of block volumes during rockfall simulations. Unmanned aerial vehicles (UAVs) are utilized to generate high-accuracy 3D models of the inaccessible SW flank of the Mount Rava (Italy), to provide improved definition of data gathered from conventional geomechanical surveys and to also denote important changes in the fracture intensity. These changes are likely related to the variation of the bedding thickness and to the presence of fracture corridors in fault damage zones in some areas of the slope. The dataset obtained integrating UAV and conventional surveys is then utilized to create and validate two accurate 3D discrete fracture network models, representative of high and low fracture intensity areas, respectively. From these, the ranges of block volumes characterizing the in situ rock mass are extracted, providing important input for rockfall simulations. Initially, rockfall simulations were performed assuming a uniform block volume variation for each release cell. However, subsequent simulations used a more realistic nonuniform distribution of block volumes, based on the relative block volume frequency extracted from discrete fracture network (DFN) models. The results of the simulations were validated against recent rockfall events and show that it is possible to integrate into rockfall simulations a more realistic relative frequency distribution of block volumes using the results of DFN analyse

    A Multi-Disciplinary Approach to the Study of Large Rock Avalanches Combining Remote Sensing, GIS and Field Surveys: The Case of the Scanno Landslide, Italy

    Get PDF
    This is the final version. Available from MDPI via the DOI in this record.This research aims to highlight the importance of adopting a multi-disciplinary approach to understanding the factors controlling large rock avalanches using the Scanno landslide, Italy, as a case study. The study area is the Mount Genzana, Abruzzi Central Apennines, characterized by the regional Difesa-Mount Genzana-Vallone delle Masserie fault zone. The Scanno landslide is famous for its role in the formation of the Scanno Lake. The landslide is characterized by a wide exposed scar, which was interpreted in previous studies as the intersection of high-angle joints and an outcropping bedding plane on which the landslide failed sometime between the Upper Pleistocene and the Holocene. In this study, the Scanno landslide was investigated through the integration of geological, geomechanical and geomorphological surveys. Remote sensing techniques were used to enrich the conventionally gathered datasets, while Geographic Information Systems (GIS) were used to integrate, manage and investigate the data. The results of the authors investigation show that the outcropping landslide scar can be interpreted as a low-angle fault, associated with the Difesa-Mount Genzana-Vallone delle Masserie fault zone, which di ers from previous investigations and interpretations of the area. The low-angle fault provides the basal failure surface of the landslide, with two systematic high-angle joint sets acting as lateral release and back scarp surfaces, respectively. In light of these new findings, pre- and post-failure models of the area have been created. The models were generated in GIS by combining LiDAR (Light Detection and Ranging) and geophysics data acquired on the landslide body and through bathymetric survey data of the Scanno Lake. Using the pre- and post-failure models it was possible to estimate the approximate volume of the landslide. Finally, back-analyses using static and dynamic limit equilibrium methods is also used to show the possible influence of medium-to-high magnitude seismic events in triggering the Scanno landslide

    Application of unmanned aerial vehicle data and discrete fracture network models for improved rockfall simulations

    Get PDF
    This is the final version. Available from the publisher via the DOI in this record.In this research, we present a new approach to define the distribution of block volumes during rockfall simulations. Unmanned aerial vehicles (UAVs) are utilized to generate high-accuracy 3D models of the inaccessible SW flank of the Mount Rava (Italy), to provide improved definition of data gathered from conventional geomechanical surveys and to also denote important changes in the fracture intensity. These changes are likely related to the variation of the bedding thickness and to the presence of fracture corridors in fault damage zones in some areas of the slope. The dataset obtained integrating UAV and conventional surveys is then utilized to create and validate two accurate 3D discrete fracture network models, representative of high and low fracture intensity areas, respectively. From these, the ranges of block volumes characterizing the in situ rock mass are extracted, providing important input for rockfall simulations. Initially, rockfall simulations were performed assuming a uniform block volume variation for each release cell. However, subsequent simulations used a more realistic nonuniform distribution of block volumes, based on the relative block volume frequency extracted from discrete fracture network (DFN) models. The results of the simulations were validated against recent rockfall events and show that it is possible to integrate into rockfall simulations a more realistic relative frequency distribution of block volumes using the results of DFN analyses

    Potential health effects of dietary nitrate supplementation in aging and chronic degenerative disease

    Get PDF
    In the United States, latest projections indicate the number of adults 65 years of age and older is expected to double by 2050. Given that increased oxidative stress is a hallmark of aging, it is understandable that waning nitric oxide and chronic degenerative disease arise in tandem. To this end, translational evidence-based strategies are needed to mitigate the impending toll on personal and public health. Dietary nitrate supplementation, particularly in the form of beetroot juice, is an active area of inquiry that has gained considerable attention in recent years. Compelling evidence has revealed beetroot juice can elicit potent physiological responses that may offer associated health benefits for multiple clinical disorders including hypertension, dementia, and sarcopenia. Even in the absence of overt disease, age-related impairments in cardiovascular and skeletal muscle function may uniquely benefit from beetroot juice supplementation as evidence has shown blood pressure lowering effects and improved muscle function/contractility – presumably from increased nitric oxide bioavailability. This, in turn, presents a practical opportunity for susceptible populations to support ease of movement and exercise tolerance, both of which may promote free-living physical activity. A theoretical rationale details the potential health effects of dietary nitrate supplementation, wherein a working framework hypothesizes beetroot juice consumption prior to structured exercise training may offer synergistic benefits to aid healthy aging and independent-living among older adults

    Klotho: An Emerging Factor With Ergogenic Potential

    Get PDF
    Sarcopenia and impaired cardiorespiratory fitness are commonly observed in older individuals and patients with chronic kidney disease (CKD). Declines in skeletal muscle function and aerobic capacity can progress into impaired physical function and inability to perform activities of daily living. Physical function is highly associated with important clinical outcomes such as hospitalization, functional independence, quality of life, and mortality. While lifestyle modifications such as exercise and dietary interventions have been shown to prevent and reverse declines in physical function, the utility of these treatment strategies is limited by poor widespread adoption and adherence due to a wide variety of both perceived and actual barriers to exercise. Therefore, identifying novel treatment targets to manage physical function decline is critically important. Klotho, a remarkable protein with powerful anti-aging properties has recently been investigated for its role in musculoskeletal health and physical function. Klotho is involved in several key processes that regulate skeletal muscle function, such as muscle regeneration, mitochondrial biogenesis, endothelial function, oxidative stress, and inflammation. This is particularly important for older adults and patients with CKD, which are known states of Klotho deficiency. Emerging data support the existence of Klotho-related benefits to exercise and for potential Klotho-based therapeutic interventions for the treatment of sarcopenia and its progression to physical disability. However, significant gaps in our understanding of Klotho must first be overcome before we can consider its potential ergogenic benefits. These advances will be critical to establish the optimal approach to future Klotho-based interventional trials and to determine if Klotho can regulate physical dysfunction

    Initiation of Dialysis Is Associated With Impaired Cardiovascular Functional Capacity

    Get PDF
    Background The transition to dialysis period carries a substantial increased cardiovascular risk in patients with chronic kidney disease. Despite this, alterations in cardiovascular functional capacity during this transition are largely unknown. The present study therefore sought to assess ventilatory exercise response measures in patients within 1 year of initiating dialysis. Methods and Results We conducted a cross‐sectional study of 241 patients with chronic kidney disease stage 5 from the CAPER (Cardiopulmonary Exercise Testing in Renal Failure) study and from the intradialytic low‐frequency electrical muscle stimulation pilot randomized controlled trial cohorts. Patients underwent cardiopulmonary exercise testing and echocardiography. Of the 241 patients (age, 48.9 [15.0] years; 154 [63.9%] men), 42 were predialytic (mean estimated glomerular filtration rate, 14 mL·min −1 ·1.73 m −2 ), 54 had a dialysis vintage ≤12 months, and 145 had a dialysis vintage >12 months. Dialysis vintage ≤12 months exhibited a significantly impaired cardiovascular functional capacity, as assessed by oxygen uptake at peak exercise (18.7 [5.8] mL·min −1 ·kg −1 ) compared with predialysis (22.7 [5.2] mL·min −1 ·kg −1 ; P <0.001). Dialysis vintage ≤12 months also exhibited reduced peak workload, impaired peak heart rate, reduced circulatory power, and increased left ventricular mass index ( P <0.05 for all) compared with predialysis. After excluding those with prior kidney transplant, dialysis vintage >12 months exhibited a lower oxygen uptake at peak exercise (17.0 [4.9] mL·min −1 ·kg −1 ) compared with dialysis vintage ≤12 months (18.9 [5.9] mL·min −1 ·kg −1 ; P =0.033). Conclusions Initiating dialysis is associated with a significant impairment in oxygen uptake at peak exercise and overall decrements in ventilatory and hemodynamic exercise responses that predispose patients to functional dependence. The magnitude of these changes is comparable to the differences between low‐risk New York Heart Association class I and higher‐risk New York Heart Association class II to IV heart failure

    Ruthenium polypyridyl complexes and their modes of interaction with DNA : is there a correlation between these interactions and the antitumor activity of the compounds?

    Get PDF
    Various interaction modes between a group of six ruthenium polypyridyl complexes and DNA have been studied using a number of spectroscopic techniques. Five mononuclear species were selected with formula [Ru(tpy) L1L2](2-n)?, and one closely related dinuclear cation of formula [{Ru(apy)(tpy)}2{l-H2N(CH2)6NH2}]4?. The ligand tpy is 2,20:60,200-terpyridine and the ligand L1 is a bidentate ligand, namely, apy (2,20-azobispyridine), 2-phenylazopyridine, or 2-phenylpyridinylmethylene amine. The ligand L2 is a labile monodentate ligand, being Cl-, H2O, or CH3CN. All six species containing a labile L2 were found to be able to coordinate to the DNA model base 9-ethylguanine by 1H NMR and mass spectrometry. The dinuclear cationic species, which has no positions available for coordination to a DNA base, was studied for comparison purposes. The interactions between a selection of four representative complexes and calf-thymus DNA were studied by circular and linear dichroism. To explore a possible relation between DNA-binding ability and toxicity, all compounds were screened for anticancer activity in a variety of cancer cell lines, showing in some cases an activity which is comparable to that of cisplatin. Comparison of the details of the compound structures, their DNA binding, and their toxicity allows the exploration of structure–activity relationships that might be used to guide optimization of the activity of agents of this class of compounds

    Beetroot supplementation in women enjoying exercise together (BEE SWEET): Rationale, design and methods

    Get PDF
    Background: Postmenopausal women exhibit higher rates of disability and cardiovascular disease (CVD) with aging compared to men. Whereas habitual exercise training is a known strategy to enhance physiologic function in men and premenopausal women, exercise-related adaptations are often modest in postmenopausal women. We propose dietary nitrate (beetroot juice) administered prior to exercise training may be a feasible approach to improve mobility and cardio-metabolic health outcomes in postmenopausal women. Methods: Our randomized, placebo-controlled study aims to determine preliminary effects sizes for changes in functional mobility and endothelium-dependent vasodilation across three study arms: exercise only (EX), exercise + placebo (EX + PL), and exercise + beetroot (EX + BR). Thirty-six postmenopausal women are recruited in small cohorts wherein group exercise is implemented to facilitate social support and adherence to an 8-week training progression. Participants are randomized to one of three study arms (n = 12 per group) following baseline assessments. Post-intervention assessments are used to determine pre-post changes in outcome measures including distance covered during a 6 min walk test, walking economy, muscle speed and power, and endothelial-dependent vasodilation as determined by flow-mediated dilation. Measures of feasibility include recruitment, retention, adherence to exercise prescription, perceived exercise session difficulty, and adverse event rates. Discussion: Evidence-based, translational strategies are needed to optimize exercise training-related adaptations in postmenopausal women. Findings will inform larger randomized clinical trials to determine if pre-exercise consumption of beetroot juice is an efficacious strategy to promote mobility and attenuate CVD disease risk

    Differences in selectivity to natural images in early visual areas (V1–V3)

    Get PDF
    High-level regions of the ventral visual pathway respond more to intact objects compared to scrambled objects. The aim of this study was to determine if this selectivity for objects emerges at an earlier stage of processing. Visual areas (V1–V3) were defined for each participant using retinotopic mapping. Participants then viewed intact and scrambled images from different object categories (bottle, chair, face, house, shoe) while neural responses were measured using fMRI. Our rationale for using scrambled images is that they contain the same low-level properties as the intact objects, but lack the higher-order combinations of features that are characteristic of natural images. Neural responses were higher for scrambled than intact images in all regions. However, the difference between intact and scrambled images was smaller in V3 compared to V1 and V2. Next, we measured the spatial patterns of response to intact and scrambled images from different object categories. We found higher within-category compared to between category correlations for both intact and scrambled images demonstrating distinct patterns of response. Spatial patterns of response were more distinct for intact compared to scrambled images in V3, but not in V1 or V2. These findings demonstrate the emergence of selectivity to natural images in V3
    • …
    corecore