2,698 research outputs found

    Reliability and Relationships between Supine Medicine Ball Throw Kinetics and Vertical Jump Height

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    Supine medicine ball throw (SMBT) assessments have been used previously to evaluate upper-body explosive strength in young adults. Kinetic variables, such as peak force and rate of force development (RFD), can be measured during a SMBT. These variables have been suggested to be important predictors of athletic performance capacities. However, limited data exist regarding the reliability of SMBT peak force and RFD measurements and how they associate with performance during a vertical jump (VJ) test. PURPOSE: The purpose of this study was to examine the reliability of SMBT variables and their relationship with VJ height. METHODS: Twenty young, healthy women (age = 21 ± 3 years) volunteered for this study. Participants reported for testing on two different occasions, separated by 2-7 days at approximately the same time of day (± 2 hours). For each testing session, participants completed three VJs followed by three SMBT assessments. All VJs were performed on a jump mat. The jump mat measured VJ height (cm) based on flight time. For the SMBTs, participants laid on a force plate in the supine position with their hands on the ball (2.7 kg) and knees and hips flexed at 90º. Participants were instructed to throw the ball explosively upward with as much force as possible, using a motion similar to a basketball chest pass. The vertical force signal (N) from the force plate was recorded during each throw and used to measure peak force and RFD variables. Peak force was calculated as the highest force value. RFDmax was calculated as the highest slope for any 20 ms epoch that occurred over the rising portion of the force signal. RFD30% and RFD40-80% were calculated as the linear slope of the force signal from the onset of the throw to 30% peak force and from 40% to 80% peak force, respectively. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated between sessions to assess the reliability of SMBT peak force and RFD variables. The relationships between these variables and VJ height were assessed by Pearson correlation coefficients (r). RESULTS: The ICC for SMBT RFD30% was 0.55. This ICC was considerably lower than the ICCs for the other SMBT variables (0.82-0.88). The CV value for SMBT RFD30% was 27.2%, whereas the CV values for SMBT peak force, RFDmax, and RFD40-80% were all less than or equal to 14.0%. There were significant relationships between VJ height and SMBT peak force (r = 0.483, P = 0.031), RFDmax (r = 0.484, P = 0.031), and RFD40-80% (r = 0.491, P = 0.028); however, there was no significant relationship between VJ height and RFD30% (r = 0.359, P = 0.120). CONCLUSION: The results of this study demonstrated that SMBT peak force, RFDmax, and RFD40-80% were reliable measures for assessing upper-body explosive strength in young, healthy adults. These measurements were significantly associated with VJ height and therefore, may be effective parameters at predicting a person’s jumping ability and overall athletic performance potential. RFD30% was unreliable and not significantly correlated with VJ height. As a result, this variable should not be used as a performance measure when conducting SMBT assessments

    Handgrip Peak Force and Rate of Force Development Measurements: Are They Reliable and Do They Correlate with Vertical Jump Power?

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    Handgrip peak force and rate of force development (RFD) measurements have been shown to be effective parameters at characterizing the strength capacities of numerous muscle groups, including those of the lower extremities. However, the reliability of these measurements and their relationship with vertical jump (VJ) peak power remains uncertain. PURPOSE: The purpose of this study was to examine the reliability of handgrip peak force and RFD measurements. A secondary aim was to determine if these measurements are correlated with the peak power produced during a VJ test. METHODS: Twenty young, healthy women (age = 21 ± 3 years) volunteered for this study. Participants reported for testing on two different occasions, separated by 2-7 days at approximately the same time of day (± 2 hours). For each testing session, participants completed three VJs followed by three handgrip maximal voluntary contraction (MVC) assessments with the dominant hand. VJs were performed using a linear velocity transducer that was attached to the posterior portion of a belt fastened around the participants’ waistline. For all VJs, participants were instructed to jump up as explosively as possible with both feet at the same time and land on the floor in the starting position. Prior to the VJ assessments, each participant\u27s body mass was entered into the linear velocity transducer microcomputer. Estimated peak power output was calculated in watts (W) and displayed by the microcomputer at the conclusion of each jump. Handgrip MVCs were performed using a novel strength testing device. This device consisted of a microcomputer and a load cell that was equipped with two semi-cylindrical handles for gripping. For each MVC, participants sat in an upright position and were instructed to squeeze the handles of the load cell “as hard and fast as possible” for 3-4 seconds. Handgrip peak force, peak RFD, and RFD at 0-100 (RFD100) and 0-200 (RFD200) milliseconds from contraction onset were calculated and displayed by the device at the conclusion of each assessment. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated between sessions to assess the reliability of handgrip peak force and RFD variables. The relationships between these variables and VJ peak power were determined by Pearson correlation coefficients (r). RESULTS: Handgrip peak force, peak RFD, RFD100, and RFD200 were highly consistent between sessions, with ICCs ranging between 0.89 and 0.92 and CV values between 4.9 and 6.4%. There were significant correlations between VJ peak power and handgrip peak force (r = 0.612, P = 0.004), peak RFD (r = 0.731, P \u3c 0.001), RFD100 (r = 0.671, P = 0.001), and RFD200 (r = 0.701, P = 0.001). CONCLUSION: The results of this study showed that peak force, peak RFD, RFD100, and RFD200 were reliable measures for assessing handgrip strength in young, healthy adults. These measurements were significantly correlated with VJ peak power and thus, could be effective parameters at predicting lower-body explosiveness. The predictive capacity of such parameters to determine a person’s peak power may be important in the early stages of rehabilitation, especially if that person is unable to perform a VJ test

    Age-related Differences in Handgrip Strength Characteristics and Vertical Jump Performance

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    Handgrip strength characteristics, such as peak force and rate of force development (RFD), have been shown to be significantly associated with the performance capacities of the lower-body musculature. Declines in lower-body performance are commonly reported as a consequence of aging. However, few studies have investigated the influence of age on handgrip peak force and RFD. PURPOSE: The purpose of this study was to examine age-related differences in handgrip peak force and RFD between young and older women and the relationships of these characteristics with lower-body performance during a vertical jump (VJ) test. METHODS: Twenty young (age = 21 ± 3 years) and twenty older (67 ± 5 years) healthy women completed three VJs followed by three handgrip maximal voluntary contraction (MVC) assessments with the dominant hand. All VJs were performed on a jump mat. The jump mat assessed lower-body performance by measuring VJ height (cm). Handgrip MVCs were performed using a novel strength testing device. This device consisted of a microcomputer and a load cell that was equipped with two semi-cylindrical handles for gripping. For each MVC, participants sat in an upright position and were instructed to squeeze the handles of the load cell “as hard and fast as possible” for 3-4 seconds. Handgrip peak force, peak RFD, and RFD at 0-100 (RFD100) and 0-200 (RFD200) milliseconds from contraction onset were calculated and displayed by the device at the conclusion of each MVC and were normalized to body mass. Independent samples t-tests were used to compare VJ height and handgrip peak force and RFD characteristics between the young and older women. Pearson correlation coefficients (r) were calculated separately for the young and older women to examine the relationships between VJ height and handgrip peak force and RFD. RESULTS: The older women exhibited significantly lower VJ height (older = 20.3 ± 3.8 cm; young = 34.4 ± 5.9 cm; P \u3c 0.001), peak force (older = 2.4 ± 0.4 N·kg-1; young = 2.7 ± 0.5 N·kg-1; P = 0.028), peak RFD (older = 13.6 ± 2.6 N·s-1·kg-1; young = 16.4 ± 2.9 N·s-1·kg-1; P = 0.003), RFD100 (older = 13.2 ± 3.0 N·s-1·kg-1; young = 15.7 ± 3.3 N·s-1·kg-1; P = 0.016), and RFD200 (older = 9.3 ± 1.6 N·s-1·kg-1; young = 10.8 ± 1.6 N·s-1·kg-1; P = 0.003) than the younger women. Positive correlations were observed between VJ height and handgrip RFD200 (r = 0.502, P = 0.024) and peak RFD (r = 0.453, P = 0.045) for the younger women. Positive correlations were also observed between VJ height and handgrip RFD200 (r = 0.446, P = 0.049) and peak RFD (r = 0.408, P = 0.074) for the older women, although the latter correlation did not reach statistical significance. There were no significant correlations between VJ height and handgrip peak force (young: r = 0.389, P = 0.090; older: r = 0.311, P = 0.183) or RFD100 (young: r = 0.366, P = 0.113; older: r = 0.382, P = 0.096) for either age group. CONCLUSION: These findings demonstrated that VJ height and handgrip peak force and RFD characteristics decrease in old age. The significant correlations observed between VJ height and RFD200 in the young and older women suggest that handgrip rapid strength (0-200 milliseconds) may be an effective predictor of one’s jumping ability

    Intraluminal measurement of papillary duct urine pH, in vivo: a pilot study in the swine kidney

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    We describe the in vivo use of an optic-chemo microsensor to measure intraluminal papillary duct urine pH in a large mammal. Fiber-optic pH microsensors have a tip diameter of 140-µm that allows insertion into papillary Bellini ducts to measure tubule urine proton concentration. Anesthetized adult pigs underwent percutaneous nephrolithotomy to access the lower pole of the urinary collecting system. A flexible nephroscope was advanced towards an upper pole papilla with the fiber-optic microsensor contained within the working channel. The microsensor was then carefully inserted into Bellini ducts to measure tubule urine pH in real time. We successfully recorded tubule urine pH values in five papillary ducts from three pigs (1 farm pig and 2 metabolic syndrome Ossabaw pigs). Our results demonstrate that optical microsensor technology can be used to measure intraluminal urine pH in real time in a living large mammal. This opens the possibility for application of this optical pH sensing technology in nephrolithiasis

    Global increases in both common and rare copy number load associated with autism.

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    Children with autism have an elevated frequency of large, rare copy number variants (CNVs). However, the global load of deletions or duplications, per se, and their size, location and relationship to clinical manifestations of autism have not been documented. We examined CNV data from 516 individuals with autism or typical development from the population-based Childhood Autism Risks from Genetics and Environment (CHARGE) study. We interrogated 120 regions flanked by segmental duplications (genomic hotspots) for events >50 kbp and the entire genomic backbone for variants >300 kbp using a custom targeted DNA microarray. This analysis was complemented by a separate study of five highly dynamic hotspots associated with autism or developmental delay syndromes, using a finely tiled array platform (>1 kbp) in 142 children matched for gender and ethnicity. In both studies, a significant increase in the number of base pairs of duplication, but not deletion, was associated with autism. Significantly elevated levels of CNV load remained after the removal of rare and likely pathogenic events. Further, the entire CNV load detected with the finely tiled array was contributed by common variants. The impact of this variation was assessed by examining the correlation of clinical outcomes with CNV load. The level of personal and social skills, measured by Vineland Adaptive Behavior Scales, negatively correlated (Spearman's r = -0.13, P = 0.034) with the duplication CNV load for the affected children; the strongest association was found for communication (P = 0.048) and socialization (P = 0.022) scores. We propose that CNV load, predominantly increased genomic base pairs of duplication, predisposes to autism

    Preliminary Report on Stone Breakage and Lesion Size Produced by a New Extracorporeal Electrohydraulic (Sparker Array) Discharge Device

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    Objective To determine if an innovative extracorporeal electrohydraulic shock wave device (sparker array) can effectively fracture artificial stones in vitro and in vivo, and if sparker array treatment produces a renal lesion in our pig model of lithotripsy injury. Results of these experiments will be used to help evaluate the suitability of this device as a clinical lithotripter. Methods Utracal-30 artificial stones were placed in a holder at the focus of the sparker array and treated with 600 shock waves (21.6 kV, 60 shocks/min). Stone fragments were collected, dried and weighed to determine stone breakage. In vivo stone breakage entailed implanting stones into pigs. These stones were treated with 600 or 1200 shock waves and the fragments collected for analysis. Lesion analysis consisted of treating the left kidney of pigs with 1200 or 2400 shock waves and quantitating the hemorrhagic lesion. Results In vitro, 71±2% of each artificial stone was fractured to < 2 mm in size. In vivo stone breakage averaged 63%. Renal injury analysis revealed that only 1 out of 7 kidneys showed evidence of hemorrhagic injury in the treated area. Conclusions The sparker array consistently comminuted artificial stones demonstrating its ability to fracture stones like other lithotripters. Also, the sparker array caused little to no renal injury at the settings used in this study. These findings suggest further research is warranted to determine the potential of this device as a clinical lithotripter

    Comparative outcomes between COVID-19 and influenza patients placed on veno-venous extracorporeal membrane oxygenation for severe ARDS

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    Background ECMO is an established supportive adjunct for patients with severe, refractory ARDS from viral pneumonia. However, the exact role and timing of ECMO for COVID-19 patients remains unclear. Methods We conducted a retrospective comparison of the first 32 patients with COVID-19-associated ARDS to the last 28 patients with influenza-associated ARDS placed on V-V ECMO. We compared patient factors between the two cohorts and used survival analysis to compare the hazard of mortality over sixty days post-cannulation.Results COVID-19 patients were older (mean 47.8 vs. 41.2 years, p = 0.033), had more ventilator days before cannulation (mean 4.5 vs. 1.5 days, p < 0.001). Crude in-hospital mortality was significantly higher in the COVID-19 cohort at 65.6% (n = 21/32) versus 36.3% (n = 11/28, p = 0.041). The adjusted hazard ratio over sixty days for COVID-19 patients was 2.81 (95% CI 1.07, 7.35) after adjusting for age, race, ECMO-associated organ failure, and Charlson Comorbidity Index. Conclusion ECMO has a role in severe ARDS associated with COVID-19 but providers should carefully weigh patient factors when utilizing this scarce resource in favor of influenza pneumonia

    Progress toward superconductor electronics fabrication process with planarized NbN and NbN/Nb layers

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    To increase density of superconductor digital and neuromorphic circuits by 10x and reach integration scale of 10810^8 Josephson junctions (JJs) per chip, we developed a new fabrication process on 200-mm wafers, using self-shunted Nb/Al-AlOx/Nb JJs and kinetic inductors. The process has a layer of JJs, a layer of resistors, and 10 fully planarized superconducting layers: 8 Nb layers and 2 layers of high kinetic inductance materials, Mo2_2N and NbN, with sheet inductance of 8 pH/sq and 3 pH/sq, respectively. NbN films were deposited by two methods: with TcT_c=15.5 K by reactive sputtering of a Nb target in Ar+N2_2 mixture; with TcT_c in the range from 9 K to 13 K by plasma-enhanced chemical vapor deposition (PECVD) using Tris(diethylamido)(tert-butylimido)niobium(V) metalorganic precursor. PECVD of NbN was investigated to obtain conformal deposition and filling narrow trenches and vias with high depth-to-width ratios, which was not possible to achieve using sputtering and other physical vapor deposition (PVD) methods at temperatures below 200oC200 ^oC required to prevent degradation of Nb/Al-AlOx/Nb junctions. Nb layers with 200 nm thickness are used in the process layer stack as ground planes to maintain a high level of interlayer shielding and low intralayer mutual coupling, for passive transmission lines with wave impedances matching impedances of JJs, typically <=50 Ω\Omega, and for low-value inductors. NbN and NbN/Nb bilayer are used for cell inductors. Using NbN/Nb bilayers and individual pattering of both layers to form inductors allowed us to minimize parasitic kinetic inductance associated with interlayer vias and connections to JJs as well as to increase critical currents of the vias. Fabrication details and results of electrical characterization of NbN films, wires, and vias, and comparison with Nb properties are given.Comment: 12 pages, 16 figures, 4 tables, 49 references. Submitted to IEEE TAS on Nov. 10, 202

    Responses of a wetland ecosystem to the controlled introduction of invasive fish

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136368/1/fwb12900_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136368/2/fwb12900.pd
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