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Introduction Hamstring injury among athletes often results in significant morbidity. Currently, there are controversies regarding the clinical use of platelet-rich plasma (PRP) for the treatment of acute hamstring injury. Methods and analysis This study is a single-centre double-blind randomised placebo-controlled trial. Sixty-eight patients will be randomised to receive under ultrasound guidance either a single injection of leucocyte-rich PRP (LR-PRP) or normal saline. All patients will undergo a standardised hamstring rehabilitation programme under the supervision of a sports physiotherapist. Outcome data will be collected before intervention (baseline), and thereafter on a weekly basis. The primary outcome measure is the duration to return-to- play. It is defined as the duration (in days) from the date on which the injury occurred until the patients were pain-free, able to perform the active knee extension test and have regained hamstring muscle strength. Secondary outcome measures include assessment of pain intensity and the effect of pain on to day-to- day functions using the self-reported Brief Pain Inventory—Short Form questionnaire. Both the primary and secondary outcomes were assessed at baseline and thereafter once a week until return to play. Also, hamstring injury recurrence within the first 6 months after recovery will be monitored via telephone. The results of this study will provide insights into the effect of LR-PRP in muscle and may help to identify the best PRP application protocol for muscle injuries. Ethics and dissemination Ethics approval were obtained from the Medical Research Ethics Committee of the University of Malaya Medical Centre. Results of this trial will be submitted for publication in a peer-reviewed journal. [ABSTRACT FROM AUTHOR]

A “triaxial velocity sensor” consists of three uniaxial velocity sensors, which are nominally identical, orthogonally oriented among themselves, and co-centered at one point in space. A triaxial velocity sensor measures the acoustic particle velocity vector, by its three Cartesian components, individually component-by-component, thereby offering azimuth-elevation two-dimensional spatial directivity, despite the physical compactness that comes with the collocation of its three components. This sensing system’s azimuth-elevation beam-pattern has been much analyzed in the open literature, but only for an idealized case of the three uniaxial velocity sensors being exactly identical in gain. If this nominal identity is violated among the three uniaxial velocity sensors, as may occur in practical hardware, what would happen to the corresponding “spatial matched filter” beam-pattern’s peak direction? How would this effective peak direction deviate from the nominal “look direction”? This paper, by modeling each uniaxial velocity sensor’s gain as stochastic, derives this deviation’s statistical mean and variance, analytically in closed mathematical forms. This analytical derivation is verified by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

This paper proposes a new radar/sonar processing architecture that enables a low-rate time-sampling rate while still producing a high-resolution range profile over a narrow range-window. This new architecture generalizes the conventional ?stretch processing? architecture (which employs linear frequency modulated (LFM) waveforms that suffer from high range-sidelobes), to nonlinear frequency modulated (NLFM) waveforms, which can lower the range-sidelobes without tapering. Computational results demonstrate both the estimation efficacy and the time-sampling efficiency of the proposed scheme. [ABSTRACT FROM PUBLISHER]

The time-of-arrival (TOA) distributions of the uplink and downlink multipath are analytically derived in this paper. This is based on geometrical models that simplify the spatial relationship among a mobile transceiver, the scatterers, and a base-station transceiver. These models idealize the scatterers as lying on a circular disc centered around the mobile transceiver, with these scatterers concentrating in a conically shaped spatial density. The base-station transceiver may lie either among these scatterers (in an indoor propagation environment) or outside this disc of scatterers (for an elevated base-station outdoor receiver). In contrast to the customary uniform-disc density, this conical" scatterer density indirectly accounts for the multipath scattering power loss. These new TOA distribution formulas, herein derived explicitly in terms of the model's only two independent parameters, can better fit some empirical data than can all earlier models that also confine all scatterers to within a circular disc. [ABSTRACT FROM AUTHOR]

This purpose of this study was to investigate the impact of fabric moisture transport properties (MTP) on physiological responses when wearing protective clothing. Ten healthy subjects wore two kinds of personal protective equipment (PPE) ensembles and exercised on a treadmill, worked on a computer, and moved a mannequin in an environment that simulated where health carers work. PPE1 consisted of cotton underwear and 100% polyethylene outerwear. PPE2 consisted of cotton underwear with moisture management function and outerwear made of waterproof breathable fabric. The results showed that there were significantly higher cumulative one-way transport capacity, liquid moisture management capacity, and wetting time in PPE2 than in PPE1 underwear. There was significantly higher water vapor permeability (WVP) in PPE2 than in PPE1 outerwear. Deep ear canal temperature, mean skin temperature, and chest wall skin and clothing microclimates (temperature and humidity) were significantly lower with PPE2 than PPE1. The level of plasma oxygen saturation was significantly higher with PPE 2 than PPE1. In the present study, due to the MTP of the fabrics, liquid sweat transferred from the skin surface to the opposite surface quickly and speeded up the processes of evaporation and heat dissipation. It was concluded that the fabric's MTP, when incorporated into protective clothing, is the main physiological mechanism for reduced heat stress. [ABSTRACT FROM AUTHOR]

New quasi-Bayesian (hybrid) Cramér-Rao bound (CRB) expressions are herein derived for far-field deep-sea direction-of-arrival (DOA) estimation with a nominally linear towed-array that 1) is deformed by spatio-temporally correlated oceanic currents, which have been previously overlooked in the towed-array shape-deformation statistical analysis literature, 2) is deformed by temporally correlated motion of the towing vessel, which is modeled only as temporally uncorrelated in prior literature, and 3) suffers gain-uncertainties and phase-uncertainties in its constituent hydrophones. This paper attempts to bridge an existing literature gap in deformed towed-array DOA-estimation performance analysis, by simultaneously a) incorporating several essential fluid-mechanics considerations to produce a shape-deformation statistical model physically more realistic than those previously used for DOA performance analysis and b) rigorously derive a mathematical analysis to characterize quantitatively and qualitatively the DOA stimation's statistical performance. The derived CRB expressions are parameterized in terms of the towed-array's physically measurable nonidealities for the single-source case. The new hybrid-CRB expressions herein derived are numerically more stable than those in the current literature. [ABSTRACT FROM AUTHOR]

In this letter, a new "fractional self-decorrelation" technique is proposed to enhance the multipath-constructive-summation and interference-rejection capability of single-user-type DS-CDMA detectors at maximum-SINR blind space-time RAKE receivers, to tackle the near-far problem in wireless mobile communications. This technique can significantly decrease the error rate and can reduce the near-far problem's error floor at high SNR. This "blind" space-time processing receiver architecture needs no prior knowledge nor explicit estimation of: 1) the channel's multipath arrival angle or arrival delay or power profile-the fading channel's delay spread may be of arbitrary length, even as long as the symbol duration; 2) the receiver's nominal or actual antenna array manifold; and 3) the other DS-CDMA users' signature spreading codes. [ABSTRACT FROM PUBLISHER]

We study a model of two polymers confined to a slit with sticky walls. More precisely, we find and analyse the exact solution of two directed friendly walks in such a geometry on the square lattice. We compare the infinite slit limit, in which the length of the polymer (thermodynamic limit) is taken to infinity before the width of the slit is considered to become large, to the opposite situation where the order of the limits are swapped, known as the half-plane limit when one polymer is modelled. In contrast with the single polymer system we find that the half-plane and infinite slit limits coincide. We understand this result in part due to the tethering of polymers on both walls of the slit. We also analyse the entropic force exerted by the polymers on the walls of the slit. Again the results differ significantly from single polymer models. In a single polymer system both attractive and repulsive regimes were seen, whereas in our two walk model only repulsive forces are observed. We do, however, see that the range of the repulsive force is dependent on the parameter values. This variation can be explained by the adsorption of the walks on opposite walls of the slit. [ABSTRACT FROM AUTHOR]

Kainam Thomas Wong, co-author of the Letter 'Spatial correlation-coefficient across a receiving sensor-array - accounting for propagation loss' on page 1351, offers his insights into his latest work. [ABSTRACT FROM AUTHOR]