Organic architecture and direct democracy: Claude Bragdon\u27s Festivals of Song and Light

Bragdon\u27s approach to organic architecture, based on communitarian principles, which contrasted with Sullivan and Wright\u27s

A systematic investigation into the effect of roughness on self-propelled swimming plates

This study examines the effects of surface topography on the flow and performance of a Self-Propelled Swimming (SPS) body. We consider a thin flat plate of length $L$ with an egg-carton roughness texture undergoing undulatory swimming kinematics at the typically observed biological Strouhal number of $0.3$, amplitude to length ratio of $0.1$, and Reynolds number of $12,000$. As the roughness wavelength, $\lambda$ is decreased, we find that the undulation wave speed $\zeta$ must be increased to maintain SPS. We find that large wavelength roughness results in the formation of horseshoe vortices around each element while smaller wavelengths result in large leading-edge vortices that dominate the flow field and the wake. Generally, increasing the wave speed $\zeta$ increases the power and side forces required to maintain SPS. However, when $\lambda\approx L/16$ there is a dramatic increase in the enstrophy (within the flow) that is not reflected in the forces on the body. The enstrophy increases when $\lambda$ is equivalent to the boundary layer thickness, a scaling known to amplify vorticity within the boundary layers. This indicates an interaction between the roughness and kinematics beyond a simple increase in viscous drag. Finally, we find that all but the longest roughness wavelength decreases the power required and reduces the RMS amplitude of the forces when compared to a smooth plate undergoing identical kinematics. This study reveals the nonlinear interaction between roughness and motion, illustrating that roughness studies on static shapes do not transfer directly to unsteady swimmers

Introduction: Black Lives Matter

Introduction: Black Lives Matter by Jonathan Massey and Meredith TenHoor with Sben Korsh — Inspired by the scholars, activists, and everyday citizens who spoke out, marched, and protested against police killings of African-Americans, we present this collection of short essays that put Black lives at the center of our thinking about architecture and its history. Addressing the Black Lives Matter movement through architectural and urban research, the essays in this collection diagnose sources of violence, identify forms of resistance, and reimagine Black aesthetics

Does normalization of voluntary EMG amplitude to MMAX account for the influence of electrode location and adiposity?

Voluntary surface electromyography (sEMG) amplitude is known to be influenced by both electrode position and subcutaneous adipose tissue thickness, and these factors likely compromise both between- and within-individual comparisons. Normalization of voluntary sEMG amplitude to evoked maximum M-wave parameters [MMAX peak-to-peak (P-P) and Area] may remove the influence of electrode position and subcutaneous tissue thickness. The purpose of this study was to: (i) assess the influence of electrode position on voluntary, evoked (MMAX P-P and Area) and normalized sEMG measurements across the surface of the vastus lateralis (VL; experiment 1: n=10); and (ii) investigate if MMAX normalization removes the confounding influence of subcutaneous tissue thickness [muscle-electrode distance (MED) from ultrasound imaging] on sEMG amplitude (experiment 2; n=41). Healthy young men performed maximum voluntary contractions (MVCs) and evoked twitch contractions during both experiments. Experiment 1: voluntary sEMG during MVCs was influenced by electrode location (P≤0.046, ES≥1.49 "large"), but when normalized to MMAX P-P showed no differences between VL sites (P=0.929) which was not the case when normalized to MMAX Area (P<0.004). Experiment 2: voluntary sEMG amplitude was related to MED, which explained 31-38% of the variance. Normalization of voluntary sEMG amplitude to MMAX P-P or MMAX Area reduced but did not consistently remove the influence of MED which still explained up to 16% (MMAX P-P) and 23% (MMAX Area) of the variance. In conclusion, MMAX P-P was the better normalization parameter for removing the influence of electrode location and substantially reduced but did not consistently remove the influence of subcutaneous adiposity

The influence of patellar tendon and muscle-tendon unit stiffness on quadriceps explosive strength in man

What is the central question of this study? \ud Do tendon and/or muscle–tendon unit stiffness influence rate of torque development? What is the main finding and its importance? In our experimental conditions, some measures of relative (to maximal voluntary torque and tissue length) muscle–tendon unit stiffness had small correlations with voluntary/evoked rate of torque development over matching torque increments. However, absolute and relative tendon stiffness were unrelated to voluntary and evoked rate of torque development. Therefore, the muscle aponeurosis but not free tendon influences the relative rate of torque development. Factors other than tissue stiffness more strongly determine the absolute rate of torque development. The influence of musculotendinous tissue stiffness on contractile rate of torque development (RTD) remains opaque. In this study, we examined the relationships between both patellar tendon (PT) and vastus lateralis muscle–tendon unit (MTU) stiffness and the voluntary and evoked knee-extension RTD. Fifty-two healthy untrained men completed duplicate laboratory sessions. Absolute and relative RTD were measured at 50 N m or 25% maximal voluntary torque (MVT) increments from onset and sequentially during explosive voluntary and evoked octet isometric contractions (supramaximal stimulation; eight pulses at 300 Hz). Isometric MVT was also assessed. Patellar tendon and MTU stiffness were derived from simultaneous force and ultrasound recordings of the PT and vastus lateralis aponeurosis during constant RTD ramp contractions. Absolute and relative (to MVT and resting tissue length) stiffness (k) was measured over identical torque increments as RTD. Pearson's correlations tested relationships between stiffness and RTD measurements over matching absolute/relative torque increments. Absolute and relative PT k were unrelated to equivalent voluntary/evoked (r = 0.020–0.255, P = 0.069–0.891). Absolute MTU k was unrelated to voluntary or evoked RTD (r ≤ 0.191, P ≥ 0.184), but some measures of relative MTU k were related to relative voluntary/evoked RTD (e.g. RTD for 25–50% MVT, r = 0.374/0.353, P = 0.007/0.014). In conclusion, relative MTU k explained a small proportion of the variance in relative voluntary and evoked RTD (both ≤19%), despite no association of absolute MTU k or absolute/relative PT k with equivalent RTD measures. Therefore, the muscle-aponeurosis component but not free tendon was associated with relative RTD, although it seems that an overriding influence of MVT negated any relationship of absolute MTU k and absolute RTD

Training-specific functional, neural, and hypertrophic adaptations to explosive- vs. sustained-contraction strength training

Training specificity is considered important for strength training, although the functional and underpinning physiological adaptations to different types of training, including brief explosive contractions, are poorly understood. This study compared the effects of 12 wk of explosive-contraction (ECT, n = 13) vs. sustained-contraction (SCT, n = 16) strength training vs. control (n = 14) on the functional, neural, hypertrophic, and intrinsic contractile characteristics of healthy young men. Training involved 40 isometric knee extension repetitions (3 times/wk): contracting as fast and hard as possible for ∼1 s (ECT) or gradually increasing to 75% of maximum voluntary torque (MVT) before holding for 3 s (SCT). Torque and electromyography during maximum and explosive contractions, torque during evoked octet contractions, and total quadriceps muscle volume (QUADSVOL) were quantified pre and post training. MVT increased more after SCT than ECT [23 vs. 17%; effect size (ES) = 0.69], with similar increases in neural drive, but greater QUADSVOL changes after SCT (8.1 vs. 2.6%; ES = 0.74). ECT improved explosive torque at all time points (17-34%; 0.54 ≤ ES ≤ 0.76) because of increased neural drive (17-28%), whereas only late-phase explosive torque (150 ms, 12%; ES = 1.48) and corresponding neural drive (18%) increased after SCT. Changes in evoked torque indicated slowing of the contractile properties of the muscle-tendon unit after both training interventions. These results showed training-specific functional changes that appeared to be due to distinct neural and hypertrophic adaptations. ECT produced a wider range of functional adaptations than SCT, and given the lesser demands of ECT, this type of training provides a highly efficient means of increasing function

Neural adaptations after 4 years vs. 12 weeks of resistance training vs. untrained

The purpose of this study was to compare the effect of resistance training (RT) duration, including years of exposure, on agonist and antagonist neuromuscular activation throughout the knee extension voluntary torque range. Fifty‐seven healthy men (untrained [UNT] n=29, short‐term RT [12WK] n=14, and long‐term RT [4YR] n=14) performed maximum and sub‐maximum (20‐80% maximum voluntary torque [MVT]) unilateral isometric knee extension contractions with torque, agonist and antagonist surface EMG recorded. Agonist EMG, including at MVT, was corrected for the confounding effects of adiposity (i.e. muscle‐electrode distance; measured with ultrasonography). Quadriceps maximum anatomical cross‐sectional area (QACSAMAX; via MRI) was also assessed. MVT was distinct for all three groups (4YR +60/+39% vs. UNT/12WK; 12WK +15% vs. UNT; 0.001<P≤0.021), and QACSAMAX was greater for 4YR (+50/+42% vs. UNT/12WK; [both] P<0.001). Agonist EMG at MVT was +44/+33% greater for 4YR/12WK ([both] P<0.001) vs. UNT; but did not differ between RT groups. The torque‐agonist EMG relationship of 4YR displayed a right/down shift with lower agonist EMG at the highest common torque (196 Nm) compared to 12WK and UNT (0.005≤P≤0.013; Effect size [ES] 0.90≤ES≤1.28). The torque‐antagonist EMG relationship displayed a lower slope with increasing RT duration (4YR<12WK<UNT; 0.001<P≤0.094; 0.56≤ES≤1.31), and antagonist EMG at the highest common torque was also lower for 4YR than UNT (‐69%; P<0.001; ES=1.18). In conclusion, 4YR and 12WK had similar agonist activation at MVT and this adaptation may be maximised during early months of RT. In contrast, inter‐muscular coordination, specifically antagonist co‐activation was progressively lower, and likely continues to adapt, with prolonged RT

Tendinous tissue properties after short and long-term functional overload: Differences between controls, 12 weeks and 4 years of resistance training.

AIM: The potential for tendinous tissues to adapt to functional overload, especially after several years of exposure to heavy resistance training is largely unexplored. This study compared the morphological and mechanical characteristics of the patellar tendon and knee-extensor tendon-aponeurosis complex between young men exposed to long-term (4 years; n=16), short-term (12 weeks; n=15) and no (untrained controls; n=39) functional overload in the form of heavy resistance training. METHODS: Patellar tendon cross-sectional area, vastus-lateralis aponeurosis area and quadriceps femoris volume, plus patellar tendon stiffness and Young's modulus, and tendon-aponeurosis complex stiffness, were quantified with MRI, dynamometry and ultrasonography. RESULTS: As expected long-term trained had greater muscle strength and volume (+58% and +56% vs untrained, both P<0.001), as well as a greater aponeurosis area (+17% vs untrained, P<0.01), but tendon cross-sectional area (mean and regional) was not different between groups. Only long-term trained had reduced patellar tendon elongation/strain over the whole force/stress range, whilst both short-term and long-term overload groups had similarly greater stiffness/Young's modulus at high force/stress (short-term +25/22%, and long-term +17/23% vs untrained; all P<0.05). Tendon-aponeurosis complex stiffness was not different between groups (ANOVA, P = 0.149). CONCLUSION: Despite large differences in muscle strength and size, years of resistance training did not induce tendon hypertrophy. Both short-term and long-term overload, demonstrated similar increases in high force mechanical and material stiffness, but reduced elongation/strain over the whole force/stress range occurred only after years of overload, indicating a force/strain specific time-course to these adaptations. This article is protected by copyright. All rights reserved