Hasil untuk "cond-mat.str-el"

Michael R. Perlet, L. I. Mendonça, P. Hosick et al.

Perlet, MR, Mendonça, LI, Hosick, PA, Licameli, N, and Matthews, EL. Heart rate variability after blood flow restriction resistance exercise and traditional resistance exercise in trained men and women. J Strength Cond Res XX(X): 000–000, 2025—Autonomic nervous system responses are attenuated after blood flow restriction (BFR) resistance exercise vs. traditional resistance exercise (TRE) in men, but women's responses are unknown. The purpose of this investigation is to compare the effects of a single BFR vs. TRE session on HRV. Thirty-nine adults (M=20, W=19, age: 23±4yrs, body mass: 72.3±13.2kg, height: 169±9cm) participated in the study. Barbell back squat 1 repetition maximum (1RM) testing was performed followed by 2 randomized and counterbalanced exercise visits ≥48 hours apart (BFR: 4 sets, 30-15-15-15 repetitions, 30% 1RM, 60 s rest; TRE: 4 sets × 10 repetitions, 70% 1RM, 60 s rest). Pre- and postexercise resting electrocardiograms were analyzed using heart rate variability (HRV) normalized units for low frequency (LF), high frequency (HF), and LF/HF. Two-way repeated measures analysis of variances with sex as a between-subjects effect were analyzed (alpha p 0.05). Post hoc testing found that LF increased and HF decreased postexercise, but with greater effects in the TRE condition (all p < 0.05). Low frequency/HF also increased postexercise, and there was a sex by time interaction (all p < 0.05). Post hoc testing found greater increases in LF/HF postexercise in men than in women ( p < 0.05) across exercise conditions. Both TRE and BFR increased sympathetic activity and decreased parasympathetic activity HRV indices, and the changes were attenuated for BFR in both sexes. However, men have a greater shift toward sympathetic dominance independent of exercise type. These changes in HRV indices may have beneficial applications for exercise training/recovery when trying to reduce autonomic stress.

S. Talpey, Liam Haintz, Micah Drake et al.

ABSTRACT Talpey, SW, Haintz, L, Drake, M, Mundy, PM, Rayner, R, James, LP, O'Grady, M, Gabbett, TJ, and Gardner, EC. The utility of the countermovement rebound jump for the assessment of neuromuscular status in National Collegiate Athletic Association Division I American football players. J Strength Cond Res XX(X): 000-000, 2025-The purpose of this study was to explore the sensitivity of the countermovement rebound jump (CMRJ) for assessing neuromuscular status after National Collegiate Athletic Association (NCAA) Division I American Football games. Twenty-nine male NCAA Division I American football players completed CMJ and CMRJ assessments 24 hours pregame, and at 24 and 72 hours postgame across 2 competitive matches. Jump testing was performed using dual force plates, and total PlayerLoad was recorded during games via Global Positioning System tracking. Linear mixed-effects models were used to examine the effects of time, match load, and game on CMRJ and CMJ metrics. Significant findings were followed by post-hoc pairwise comparisons and calculation of effect sizes. Significant time-dependent decrements were observed in CMRJ average power (p = 0.001, d = 0.67), RSImod (p = 0.03, d = 0.49), and jump height (p = 0.046, d = 0.46) at 24 hours postmatch, with recovery evident in average (p = 0.002, d = -0.63) and peak power (p = 0.004, d = -0.60) by 72 hours. Countermovement jump height increased significantly by 72 hours (p = 0.02, d = -0.49). Match load significantly mediated recovery trajectories for CMJ RSImod (p = 0.004) and time to take-off (p = 0.016), with higher loads associated with impaired recovery. The CMRJ appears to be more sensitive to acute fatigue. Whereas certain CMJ metrics were more sensitive to detecting how recovery trajectories were moderated by game load. The CMRJ offers practitioners a time-efficient and informative tool to assess the presence of acute fatigue after competition.

John William Long, Matthew Gonzalez, John Farrell et al.

ABSTRACT Long, JW, Gonzalez, M, Farrell, J, Carmargo, ME, and Cheever, K. Sleep duration and sleep quality as season-long predictors of ratings of perceived exertion and psychological well-being in female soccer athletes. J Strength Cond Res XX(X): 000-000, 2025-Sleep's effect on physiologic and psychological well-being has been examined through cross-sectional studies, but research is limited on the longitudinal impact sleep has on well-being in collegiate athletes. Thus, the purpose of this study was to explore daily fluctuations in subjective measures of psychological wellness and physiologic stress (soreness, rating of perceived exertion [RPE]) across a competitive soccer season, and the extent to which sleep duration and quality modify daily measures of wellness. Twenty female collegiate soccer players underwent daily measures of psychological well-being (mental stress, mental fatigue, anxiety, and depression), physical stress (active time, total distance, GPS load, soreness, and RPE), and sleep (duration and quality) across a 120-day competitive season. Generalized linear mixed-effects models with a zero-inflation component were used to examine the effects of sleep duration and quality on measures of physiologic and psychological stress. Sleep duration was a predictor of RPE and anxiety, and there was an interaction between sleep duration and the day of the soccer season affecting RPE, anxiety, and soreness (p < 0.05). Sleep quality was a predictor of anxiety, mental stress, and RPE (p < 0.05). Significant interactions were observed between sleep quality and the day of the soccer season affecting soreness, anxiety, mental fatigue, and mental stress (all p < 0.05). Findings suggest sleep duration and sleep quality are protective of measures of psychological well-being, with increasingly protective effects across a competitive soccer season. These findings have utility in helping to maximize both student athlete performance and wellness.

Minghui Li, Matteo Crotti, R. Martins et al.

ABSTRACT Li, M, Crotti, M, Martins, R, Tiernan, C, Lyons, M, Lander, N, Barnett, LM, and Duncan, MJ. The road to designing integrated neuromuscular training programs for children and adolescents: A systematic review and meta-analysis. J Strength Cond Res 39(8): e1043-e1060, 2025-Integrative neuromuscular training (INT) combines motor competence and strength development to boost athletic performance, but its specific components and effects on children and adolescents are not well understood. Three predetermined principles (INT exercise categories, INT progression modalities, and INT program effectiveness) were used to guide this review. Electronic databases SPORTDiscus, MEDLINE (Ovid), APA PsycINFO, Cochrane Library, Web of Science, and Embase were searched. Search terms related to study design, population, and intervention were identified, and risk of bias was appraised using the Physiotherapy Evidence Database (PEDro) Scale. Narrative synthesis indicated "strength training" (18 out of 30 studies, 60%), particularly core strength exercises (72.2%), was the most common in INT exercise categories. Twelve out of 30 studies (40%) met at least 2 types of INT progression modalities (i.e., volume-based progressions, intensity-based progressions, and complexity-oriented progressions). Meta-analysis reported significant improvements in countermovement jump (mean difference [MD] 3.32 cm, 95% CI [2.07, 4.38]; p = 0.00), push-up (MD 3.74 repetitions, 95% CI [1.53, 5.95]; p = 0.00), and sprint (standardized MD -0.18 s, 95% CI [-0.26 to -0.09]; p = 0.00), but not in flexibility. Subgroup analysis revealed that meeting all the 3 progression modalities significantly enhanced sprint (standardized MD -0.76 s, 95% CI [1.21 to -0.31]; p = 0.03) and flexibility (MD 6.38 cm, 95% CI [5.45 to 7.31]; p = 0.00). This review provides evidence that INT programs have a positive effect on improving children and adolescents' physical fitness and is regarded as a promising protocol. This review and future research can inform a call to action for using INT as a novel approach for developing motor competence, strength, and conditioning simultaneously during childhood and adolescence.

Paulo Augusto Arteaga Uribe

Las condicionales del español con la estructura cond + imperfecto de subjuntivo + condicional simple de indicativo evidencian la aparición de la flexión condicional en la prótasis, contrario a lo establecido en el español estándar. Además, de acuerdo con Lavandera (1984) y De Granda (1998), la diferencia entre grado de realidad podría motivar la aparición de dicha flexión de condicional en prótasis. Así, se busca vincular el grado de realidad con la aparición de la flexión de condicional simple de indicativo en la prótasis. A partir de lo propuesto por Thompson, Longacre y Hwang (2007) sobre grados de realidad, la Gramática de Construcciones (Hoffman y Trousdale, 2013), así como las investigaciones de Lavandera (1984) y De Granda (1998), se pone a prueba esa variable con cuestionarios escritos1.

M. D. Pinto, Cristiano Ughini, João Pedro Nunes et al.

Supplemental Digital Content is Available in the Text. Abstract Pinto, MD, Ughini, C, Nunes, JP, Cadore, EL, and Pinto, RS. Pectoralis clavicular and sternocostal thicknesses increase similarly in response to one and three sets of pec deck resistance training in untrained young men. J Strength Cond Res 39(5): 523–530, 2025—Perceived lack of time is a commonly cited reason for not engaging in resistance training (RT). Consequently, there is interest in identifying time-efficient and minimum-effective RT doses. Although RT and rehabilitation programs typically aim for muscle-specific growth, research on the pectoralis major is notably limited despite it being a frequently targeted muscle group. Here we compare the effects of two RT volumes on regional pectoralis major hypertrophy and shoulder horizontal abduction strength using a within-subject design. Following a non-training control period, 15 untrained young men (age: 24.1 ± 3.1 years) participated in a 12-week RT program, comprised of the pec deck exercise, performed in 1 set (1S) vs. 3 sets (3S), in a linear periodization of 20 to 8 repetitions maximum to failure. B-mode ultrasound imaging was used to analyze muscle thicknesses of the pectoralis major clavicular and sternocostal portions, and maximal strength was determined by 1-repetition maximum tests on the pec deck exercise. After 12 weeks of RT, similar increases were observed between conditions for the pectoralis major clavicular (1S = 17%; 3S = 18%) and sternocostal (1S = 21%; 3S = 21%) thicknesses, and maximum strength (1S = 46%; 3S = 43%). Our results indicate no effect of RT volume (1S vs. 3S) on changes in muscle size and strength and do not support regional hypertrophy after pec deck exercise in untrained men. These results have important implications for RT prescription and rehabilitation practices for individuals who may have limited time or those undergoing brief rehabilitation sessions targeting the pectoralis musculature.

H. Scammell, Jia Li, M. Scheurer

In a recent experiment (Lin et al 2021 arXiv:2112.07841 [cond-mat.str-el]), the superconducting phase hosted by a heterostructure of mirror-symmetric twisted trilayer graphene and WSe2 was shown to exhibit significantly different critical currents in opposite directions in the absence of external magnetic fields. We here develop a microscopic theory and analyze necessary conditions for this zero-field superconducting diode effect. Taking into account the spin–orbit coupling induced in trilayer graphene via the proximity effect, we classify the pairing instabilities and normal-state orders and derive which combinations are consistent with the observed diode effect, in particular, its field trainability. We perform explicit calculations of the diode effect in several different models, including the full continuum model for the system, and illuminate the relation between the diode effect and finite-momentum pairing. Our theory also provides a natural explanation of the observed sign change of the current asymmetry with doping, which can be related to an approximate chiral symmetry of the system, and of the enhanced transverse resistance above the superconducting transition. Our findings not only elucidate the rich physics of trilayer graphene on WSe2, but also establish a means to distinguish between various candidate interaction-induced orders in spin-orbit-coupled graphene moiré systems, and could therefore serve as a guide for future experiments as well.

Yang Shen, Mingpu Qin

We study the ground state of the doped Hubbard model on honeycomb lattice with both nearest ($t$) and next-nearest neighboring hoppings ($t'$) in the small doping and strongly interacting region. Previous study on the model without $t'$ showed the ground state is a half-filled stripe. We employ density matrix renormalization group and extrapolate the results with truncation errors in the converged region. In the $t' < 0$ side, we find the half-filled stripe phase at $t' = 0$ is stable against the frustration of $t'$ until a critical point $-0.4 < t'_c < -0.3$, beyond which the ground state switches to anti-ferromagnetic N$\acute e$el phase with charge modulation. With further increase of $t'$ to $-0.7$, the ground state becomes paramagnetic. In the $t' > 0$ side, the half-filled stripe stretches to $t' \approx 0.7$. We don't find obvious enhancement of pairing for the range of $t'$ studied. We study width-4 cylinders in this work but the results for spin, charge, and pairing correlation agree qualitatively for periodic and anti-periodic boundary conditions in the half-filled stripe and anti-ferromagnetic N$\acute e$el phases, suggesting the results are likely to be representative for true two-dimensional systems. The half-filled stripe to anti-ferromagnetic N$\acute e$el phase transition can be realized on real materials or ultra-cold atom platform.

Tamaghna Hazra, P. Volkov

An important open puzzle in the superconductivity of UTe$_2$ is the emergence of time-reversal broken superconductivity from a non-magnetic normal state. Breaking time-reversal symmetry in a single second-order superconducting transition requires the existence of two degenerate superconducting order parameters, which is not natural for orthorhombic UTe$_2$. Moreover, experiments under pressure (Braithwaite et. al., Comm. Phys. \bf{2}, 147 (2019), arXiv:1909.06074 [cond-mat.str-el]) suggest that superconductivity sets in at a single transition temperature in a finite parameter window, in contrast to the splitting between the symmetry breaking temperatures expected for accidental degenerate orders. Motivated by these observations, we propose a mechanism for the emergence of time-reversal breaking superconductivity without accidental or symmetry-enforced order parameter degeneracies in systems close to a magnetic phase transition. We demonstrate using Landau theory that a cubic coupling between incipient magnetic order and magnetic moments of Cooper pairs (pair-Kondo coupling) can drive time-reversal symmetry breaking superconductivity that onsets in a single, weakly first order transition over an extended region of the phase diagram. We discuss the experimental signatures of such transition in thermodynamic and resonant ultrasound measurements. A microscopic origin of pair-Kondo coupling is identified as screening of magnetic moments by chiral Cooper pairs, built out of two non-degenerate order parameters - an extension of Kondo screening to unconventional pairs.

J. Hirsch

The following letter, titled "Electron-Superconductivity in Oxides?", was submitted to Nature [Scientific Correspondence Section] on March 2, 1989, shortly after the experimental discovery of electron-doped cuprates announced in Nature on January 26, 1989. It predicted the findings recently reported in arXiv:1810.04634 by Yangmu Li, W. Tabis, Y. Tang, G. Yu, J. Jaroszynski, N. Barisic and M. Greven that "clearly point to hole-pocket-driven superconductivity in these nominally electron-doped materials", "reveal hole superconductivity in the electron-doped high-temperature superconductors" "after three decades of enormous scientific inquiry", and point to "a single underlying hole-related mechanism of superconductivity in the cuprates regardless of nominal carrier type". Many more papers on this topic were published by F. Marsiglio and the author in the ensuing 30 years from 1989 to the present. In omitting to refer to any of these theoretical works, arXiv:1810.04634 presents a misleading picture.

Aaron R. Caldwell, M. Tucker, Cory L. Butts et al.

Evan C. Johnson, Riana R. Pryor, D. Casa et al.

José Antonio-Santos, D. J. Ferreira, Gizelle L. Gomes Costa et al.

Abstract Antonio-Santos, J, Ferreira, DJS, Gomes Costa, GL, Matos, RJB, Toscano, AE, Manhães-de-Castro, R, and Leandro, CG. Resistance training alters the proportion of skeletal muscle fibers but not brain neurotrophic factors in young adult rats. J Strength Cond Res 30(12): 3531–3538, 2016—Resistance training (RT) is related to improved muscular strength and power output. Different programs of RT for rats have been developed, but peripheral and central response has not been evaluated directly in the same animal. To test the hypothesis that RT induces central and peripheral adaptations, this study evaluated the effects of a RT on the performance of a weekly maximum overload test, fiber-type typology, and brain neurotrophic factors in young adult rats. Thirty-one male Wistar rats (65 ± 5 days) were divided in 2 groups: nontrained (NT, n = 13) and trained (T, n = 18). Trained group was submitted to a program of RT ladder climbing, gradually added mass, 5 days per week during 8 weeks at 80% of individual maximum overload. This test was weekly performed to adjust the individual load throughout the weeks for both groups. After 48 hours from the last session of exercise, soleus and extensor digital longus (EDL) muscles were removed for myofibrillar ATPase staining analysis. Spinal cord, motor cortex, and cerebellum were removed for RT-PCR analysis of BDNF and insulin-like growth factor-1 (IGF-1) gene expression. In EDL muscle, T animals showed an increase in the proportion of type IIb fibers and a reduction of type IIa fibers. Insulin-like growth factor-1 gene expression was reduced in the cerebellum of T animals (NT: 1.025 ± 0.12; T: 0.57 ± 0.11). Our data showed that 8 weeks of RT were enough to increase maximum overload capacity and the proportion of glycolytic muscle fibers, but there were no associations with the expression of growth neurotrophic factors.

M. P. Mosti, Trude Carlsen, E. Aas et al.

R. Simão, J. Spineti, B. D. de Salles et al.

L. Armstrong, D. Casa, Holly Emmanuel et al.

Rebecca L. Stearns, D. Casa, R. Lopez et al.

T. Lobo, M. S. Figueira, M. E. Foglio

T. Lobo, M. S. Figueira, M. E. Foglio

In the present work we apply the atomic approach to the single impurity Anderson model (SIAM). A general formulation of this approach, that can be applied both to the impurity and to the lattice Anderson Hamiltonian, was developed in a previous work (arXiv:0903.0139v1 [cond-mat.str-el]). The method starts from the cumulant expansion of the periodic Anderson model (PAM), employing the hybridization as perturbation. The atomic Anderson limit is analytically solved and its sixteen eigenenergies and eigenstates are obtained. This atomic Anderson solution, which we call the (AAS), has all the fundamental excitations that generate the Kondo effect, and in the atomic approach is employed as a seed to generate the approximate solutions for finite U. The width of the conduction band is reduced to zero in the AAS, and we choose its position so that the Friedel sum rule (FSR) be satisfied, close to the chemical potential. We perform a complete study of the density of states of the SIAM in all the relevant range of parameters: the empty dot, the intermediate valence (IV-regime),the Kondo and the magnetic regime. In the Kondo regime we obtain a density of states that characterizes well the structure of the Kondo peak. To shown the usefulness of the method we have calculated the conductance of a quantum dot, side coupled to a conduction band.

P. Lunkenheimer, J. Hemberger, V. Tsurkan et al.

In the present work we reply to the Comment by Catalan and Scott (cond-mat/0607500) on two of our papers. This Comment has been rejected from publication in Physical Review Letters and, hence, our Reply is based on the cond-mat version.