The effects of adding mass to the legs on the energetics and biomechanics of walking.

. Purpose: The metabolic cost of walking increases when mass is added to the legs, but the effects of load magnitude and location on the energetics and biomechanics of walking are unclear. We hypothesized that with leg loading 1) net metabolic rate would be related to the moment of inertia of the leg (I leg ), 2) kinematics would be conserved, except for heavy foot loads, and 3) swing-phase sagittal-plane net muscle moments and swing-phase leg-muscle electromyography (EMG) would increase. Methods: Five adult males walked on a forcemeasuring treadmill at 1.25 mIs j1 with no load and with loads of 2 and 4 kg per foot and shank, 4 and 8 kg per thigh, and 4, 8, and 16 kg on the waist. We recorded metabolic rate and sagittal-plane kinematics and net muscle moments about the hip, knee, and ankle during the single-stance and swing phases, and EMG of key leg muscles. Results: Net metabolic rate during walking increased with load mass and more distal location and was correlated with I leg (r 2 = 0.43). Thigh loading was relatively inexpensive, helping to explain why the metabolic rate during walking is not strongly affected by body mass distribution. Kinematics, single-stance and swing-phase muscle moments, and EMG were similar while walking with no load or with waist, thigh, or shank loads. The increase in net metabolic rate with foot loading was associated with greater EMG of muscles that initiate leg swing and greater swing-phase muscle moments. Conclusions: Distal leg loads increase the metabolic rate required for swinging the leg. The increase in metabolic rate with more proximal loads may be attributable to a combination of supporting (via hip abduction muscles) and propagating the swing leg. Key Words: LOCOMOTION, LEG LOADING, ELECTROMYOGRAPHY, METABOLIC RATE, LOAD CARRIAGE R ecent studies suggest that the primary determinants of the net metabolic rate during walking are performing work to propel the center of mass forward, supporting body weight, and swinging the legs (10-12). Gottschall and Kram (10) estimate that leg swing can account for only about 10% of the net metabolic rate during human walking. Yet, when a modest mass is added to the shank or foot, the metabolic rate during walking increases dramatically (29). A biomechanical explanation for this increase in net metabolic rate during walking has not been clearly established. A better understanding of the relationship between lower-extremity loading and the energetics and biomechanics of walking has practical importance for the study of obesity as well as the design of lower-extremity body armor, prosthetic legs, and powered leg exoskeleton devices. For example, we may gain insight into the effects of increased leg mass, via obesity or body armor, on the net metabolic rate of walking. Also, designers of lowerextremity prosthetic and assistive devices (e.g., powered orthosis) may be able to better estimate how the mass of these devices will affect the energetics and biomechanics of walking. We may also improve our understanding of neuromuscular control strategies that are used during gait. Walking with an external load generally increases metabolic rate. At normal walking speeds, adding a moderate load via a backpack or around the body`s center of mass increases gross metabolic rate in direct proportion to the added mass (i.e., a 20% body weight load results in a 20% increase in metabolic rate) (13). When expressed as net metabolic rate (gross j standing) per kilogram of body mass, the increase is greater than proportional to the load. For example, when walking at 1.5 mIs j1 , Griffin et al. (12) report a 98% increase in net metabolic rate with a load of 50% of body mass. When mass is added to the extremities, metabolic rate increases disproportionately with load and is greater with more distal locations of the load (29). Rose et al. (26) have shown that adding just 2 kg to each foot increased the gross metabolic rate by 30%. Royer and Martin (28) report tha

Urban river recovery inspired by nature-based solutions and biophilic design in Albufeira, Portugal

Mass urbanisation presents one of the most urgent challenges of the 21st century. The development of cities and the related increasing ground sealing are asking even more for the restoration of urban rivers, especially in the face of climate change and its consequences. This paper aims to demonstrate nature-inspired solutions in a recovery of a Southern European river that was canalised and transformed in culvert pipes. The river restoration project naturally tells the history of the city, creates a sense for the place, as well as unifying blue-green infrastructure in a symbolic way by offering areas for recreation. To improve well-being and city resilience in the long term, a regenerative sustainability approach based on biophilic design patterns was proposed. Such actions will provide greater health, social cohesion, and well-being for residents and simultaneously reduce the risks of climate change, such as heat island effect and flash floods, presenting the benefits of the transition to a regenerative economy and holistic thinking.Foundation for Science and Technology; PTDC/GES-URB/31928/2017; Erasmus+ programme of the European Unioninfo:eu-repo/semantics/publishedVersio

The Effects of Close Companions (and Rotation) on the Magnetic Activity of M Dwarfs

We present a study of close white dwarf and M dwarf (WD+dM) binary systems and examine the effect that a close companion has on the magnetic field generation in M dwarfs. We use a base sample of 1602 white dwarf -- main sequence binaries from Rebassa et al. to develop a set of color cuts in GALEX, SDSS, UKIDSS, and 2MASS color space to construct a sample of 1756 WD+dM high-quality pairs from the SDSS DR8 spectroscopic database. We separate the individual WD and dM from each spectrum using an iterative technique that compares the WD and dM components to best-fit templates. Using the absolute height above the Galactic plane as a proxy for age, and the H{\alpha} emission line as an indicator for magnetic activity, we investigate the age-activity relation for our sample for spectral types \leqM7. Our results show that early-type M dwarfs (\leqM4) in close binary systems are more likely to be active and have longer activity lifetimes compared to their field counterparts. However, at a spectral type of M5 (just past the onset of full convection in M dwarfs), the activity fraction and lifetimes of WD+dM binary systems becomes more comparable to that of the field M dwarfs. One of the implications of having a close binary companion is presumed to be increased stellar rotation through disk-disruption, tidal effects, or angular momentum exchange. Thus, we interpret the similarity in activity behavior between late-type dMs in WD+dM pairs and late-type field dMs to be due to a decrease in sensitivity in close binary companions (or stellar rotation), which has implications for the nature of magnetic activity in fully-convective stars. (Abridged)Comment: 21 pages, 19 figures, emulateapj style, accepted to Astronomical Journal June 28, 201

Effect of Neuromuscular Electrical Muscle Stimulation on Energy Expenditure in Healthy Adults

Weight loss/weight control is a major concern in prevention of cardiovascular disease and the realm of health promotion. The primary aim of this study was to investigate the effect of neuromuscular electrical stimulation (NMES) at different intensities on energy expenditure (oxygen and calories) in healthy adults. The secondary aim was to develop a generalized linear regression (GEE) model to predict the increase of energy expenditure facilitated by NMES and identify factors (NMES stimulation intensity level, age, body mass index, weight, body fat percentage, waist/hip ratio, and gender) associated with this NMES-induced increase of energy expenditure. Forty sedentary healthy adults (18 males and 22 females) participated. NMES was given at the following stimulation intensities for 10 minutes each: sensory level (E1), motor threshold (E2), and maximal intensity comfortably tolerated (E3). Cardiopulmonary gas exchange was evaluated during rest, NMES, and recovery stage. The results revealed that NMES at E2 and E3 significantly increased energy expenditure and the energy expenditure at recovery stage was still significantly higher than baseline. The GEE model demonstrated that a linear dose-response relationship existed between the stimulation intensity and the increase of energy expenditure. No subject’s demographic or anthropometric characteristics tested were significantly associated with the increase of energy expenditure. This study suggested NMES may be used to serve as an additional intervention for weight loss programs. Future studies to develop electrical stimulators or stimulation electrodes to maximize the comfort of NMES are recommended

Effect of the stellar spin history on the tidal evolution of close-in planets

We investigate how the evolution of the stellar spin rate affects, and is affected by, planets in close orbits, via star-planet tidal interactions. To do this, we used a standard equilibrium tidal model to compute the orbital evolution of single planets orbiting both Sun-like stars and 0.1 M\odot M-dwarfs. We tested two stellar spin evolution profiles, one with fast initial rotation (P=1.2 day) and one with slow initial rotation (P=8 day). We tested the effect of varying the stellar and planetary dissipation and the planet's mass and initial orbital radius. Conclusions: Tidal evolution allows to differentiate the early behaviors of extremely close-in planets orbiting either a rapidly rotating star or a slowly rotating star. The early spin-up of the star allows the close-in planets around fast rotators to survive the early evolution. For planets around M-dwarfs, surviving the early evolution means surviving on Gyr timescales whereas for Sun-like stars the spin-down brings about late mergers of Jupiter planets. In light of this study, we can say that differentiating between one spin evolution from another given the present position of planets can be very tricky. Unless we can observe some markers of former evolution it is nearly impossible to distinguish the two very different spin profiles, let alone intermediate spin profiles. Though some conclusions can still be drawn from statistical distributions of planets around fully convective M-dwarfs. However, if the tidal evolution brings about a merger late in its history it can also entail a noticeable acceleration of the star in late ages, so that it is possible to have old stars that spin rapidly. This raises the question of better constraining the age of stars

Chronic Wasting Disease Prions in Elk Antler Velvet

Residue 226 of cervid prion proteins may be a determinant of CWD pathogenesis

Invasive Propionibacterium acnes infections in a non-selective patient cohort: clinical manifestations, management and outcome

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Purpose An increasing number of reports suggest that Propionibacterium acnes can cause serious invasive infections. Currently only limited data exist regarding the spectrum of invasive P. acnes infections. Methods Non-selective cohort study at a tertiary hospital in the UK over a nine-year-period (2003-2012) investigating clinical manifestations, risk factors, management and outcome of invasive P. acnes infections. Results Forty-nine cases were identified; the majority were neurosurgical infections and orthopaedic infections (n=28 and n=15, respectively). Only two cases had no predisposing factors; all neurosurgical and 93.3% of orthopaedic cases had a history of previous surgery and/or trauma. Foreign material was in situ at the infection site in 59.3% and 80.0% of neurosurgical and orthopaedic cases, respectively. All neurosurgical and orthopaedic cases required one or more surgical interventions to treat P. acnes infection, with or without concomitant antibiotic therapy; the duration of antibiotic therapy was significantly longer in the group of orthopaedic cases (median 53 versus 19 days; p=0.0025). All tested P. acnes isolates were susceptible to penicillin, ampicillin and chloramphenicol; only one was clindamycin-resistant. Conclusions Neurosurgical and orthopaedic infections account for the majority of invasive P. acnes infections. The majority of cases have predisposing factors, including previous surgery and/or trauma; spontaneous infections are rare. Foreign material is commonly present at the site of infection, indicating that the pathogenesis of invasive P. acnes infections likely involves biofilm formation. Since invasive P. acnes infections are associated with considerable morbidity, further studies are needed to establish effective prevention and optimal treatment strategies

Structure and evolution of Subtropical Cyclone Anita as evaluated by heat and vorticity budgets

This paper explores the evolution of subtropical cyclone Anita, which occurred near the east coast of Brazil (~19.S-37.W) in March 2010. Thermodynamic and dynamic processes during Anita's lifecycle are investigated using the heat and vorticity budget equations. The cyclone developed with hybrid characteristics and moved anomalously to the southwest where it coupled with an upper level cut-off low during the mature phase. This coupling was the main dynamical mechanism for further cyclone deepening. Anita then remained quasi-stationary about 30.S -47.W for two days due to an upper level dipole pattern which prevented earlier displacement of the upper level low counterpart. When the dipole pattern dissipated, the cyclone moved southeast and underwent extratropical transition whilst merging with a mid-latitude frontal cyclone. Diabatic heating and horizontal temperature advection are found to be essential for the subtropical development. During extratropical transition, it is instead diabatic cooling together with adiabatic cooling and warm air advection that act as the main mechanisms to influence the local temperature tendencies at low levels. Low level cyclonic tendencies were mostly due to convergent flow, and the residual vorticity partially destroyed the vorticity tendencies produced by the divergence term. Moreover, in regions and levels where convection could explain some of the vorticity tendencies, it is found that apparent sinks of cyclonic vorticity were related to negative vorticity due to divergence (i.e., convergent flow), whilst apparent sources were related to positive vorticity due to divergence (i.e., divergent flow)