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An “electromagnetic vector sensor” (EMVS) comprises three orthogonal dipoles and three orthogonal loops, all in spatial collocation. The former triplet aims to directly measure the $3 \times 1$ electric-field vector ${\mathbf{e}} $ , whereas the latter triplet aims to directly measure the $3 \times 1$ magnetic-field vector ${\mathbf{h}} $ . Their vector cross product $ {\mathbf{e}} \times {\mathbf{h}} $ would yield the incident source’s Poynting vector, which specifies the incident wavefield’s propagation direction. In reality, all these are only an idealization. Instead, a real-world dipole triad’s measurement could equal the incident ${\mathbf{e}} $ , only if the dipoles were electrically short (i.e., with an electrical length of $({L}/{\lambda }) ). Likewise, a practical loop triad’s measurement could equal the incident ${\mathbf{h}} $ , only if the loops were electrically small (i.e., with an electrical circumference of $2 \pi ({R}/{\lambda }) ). However, such short dipoles and small loops would be electromagnetically inefficient receivers. For a practical dipole that is electrically long , its measurement equals not the incident wavefield’s ${\mathbf{e}} $ but a vector dot product between: 1) the incident wave’s ${\mathbf{e}}$ and 2) that dipole antenna’s “effective length” vector (which depends on that dipole’s $({L}/{\lambda })$ and orientation). An analogous complexity exists for a practical loop that is electrically large . For such practical dipoles and loops, the aforementioned vector-cross-product would fail to yield the Poynting vector, hence it would inaccurately estimate the direction-of-arrival. Instead, this article will advance a new closed-form algorithm to simultaneously estimate an incident source’s direction-of-arrival and polarization, despite the practical dipoles’/ loops’ mathematically complicated gain/phase responses as described earlier, but without any prior knowledge of the dipoles’ electric length $({L}/{\lambda })$ nor the loops’ electric radius $({R}/{\lambda })$ .

The linear array's one-dimensional spatial geometry is simple but suffices for univariate direction finding, i.e., is adequate for the estimation of an incident source's direction-of-arrival relative to the linear array axis. However, this nominal one-dimensional ideality could be often physically compromised in the real world, as the constituent sensors may dislocate three-dimensionally from their nominal positions. For example, a towed array is subject to ocean-surface waves and to oceanic currents [Tichavsky and Wong (2004). IEEE Trans. Sign. Process. 52(1), 36-47]. This paper analyzes how a nominally linear array's one-dimensional direction-finding accuracy would be degraded by the three-dimensional random dislocation of the constituent sensors. This analysis derives the hybrid Cramér-Rao bound (HCRB) of the arrival-angle estimate in a closed form expressed in terms of the sensors' dislocation statistics. Surprisingly, the sensors' dislocation could improve and not necessarily degrade the HCRB, depending on the dislocation variances but also on the incident source's arrival angle and the signal-to-noise power ratio.

A series of 16 conjugates of the tubulin polymerization inhibitor combretastatin A4 (CA-4) and other functionally related stilbene with four 18-carbon fatty acids, namely, stearic, oleic, linoleic, and linolenic acids, have been synthesized in good yields. These new derivatives have been evaluated against the KB-3-1 (human epidermoid carcinoma), NCI-H460 (human lung cancer), HEK293 (human embryonic kidney), and MCF-7 (human breast adenocarcinoma) cell lines for antiproliferative activity, with the exhibited cytotoxic activities comparable with those of CA-4 and colchicine. Compounds 22 and 23, CA-4 conjugates of linoleic and linolenic acids, respectively, were determined to have exhibited the most active in vitro assays, with compound 23 exhibiting very similar activity to the parent compound against the NCI-H460 cell line. Our studies further delineated the structurally required Z-geometry of the stilbene moiety and that conjugation of the less active E-stilbenes with the most active fatty acid had minimal or no improvement in their respective activities.

High-frequency power converters enabled by wide bandgap (WBG) and silicon semiconductor devices offer distinct advantages in power density and dynamic performance. However, switching oscillations are commonly observed in these circuits with undesirable consequences. This paper reviews the impacts, root causes, and mitigation techniques of switching oscillations through literature survey, modeling analysis, and experimental investigation. We categorize the following root causes for oscillations during switching transients: 1) damped oscillation triggered by high di/dt and/or dv/dt coupled with parasitic elements; 2) undamped oscillation of WBG devices as part of a negative resistance oscillator; and 3) semiconductor device physical mechanisms such as the negative capacitance phenomenon due to conductivity modulation in insulated gate bipolar transistors or impact ionization in MOSFETs, the plasma extraction transit-time effect in bipolar power devices, and the reverse conduction property of GaN HEMTs. Furthermore, this paper discusses various circuit techniques to suppress switching oscillations, and techniques of extracting parasitic inductances of power devices.

Peripheral artery disease (PAD) is atherosclerotic occlusion of vessels outside the heart and most commonly affects the lower extremities. Diabetes worsens PAD outcomes, but the mechanisms involved are poorly understood. A key component of perfusion recovery in experimental PAD is induction of NFkB signaling in ischemic endothelial cells (EC). We have shown that prolonged exposure of ECs to high glucose before simulated ischemic exposure resulted in impairment of the canonical NFkB pathway through activation of protein kinase C β (PKC β). However, the signaling pathways upstream of PKC β involved in this high glucose induced desensitization of NFkB signaling are not known. We used arrays of antibodies to approximately 100 proteins known to participate in the NFkB pathway to identify the changes in their phosphorylation states in human umbilical vein endothelial cells (HUVEC). Cells grown for three days either in culture medium with normal glucose (NG) or high glucose (HG) were subjected to ischemia for 24 hours (NGI and HGI, respectively). Cell lysates were then incubated with the array of antibodies printed on glass slides and fluorescent signals were digitally recorded and normalized. The change in protein phosphorylation was calculated by dividing the intensity of the phosphorylated spot by the signal intensity of the corresponding non-phosphorylated spot for each protein. Differential expression between samples, were calculated by dividing the phosphorylation ratio of the NGI and HGI with that of the NG and HG controls, respectively. A combination of pathway analyses using bioinformatics tools on 65 modulated phosphorylation sites in HGI (represented by 35 genes) and analysis of differential phosphorylation between NGI and HGI samples suggested involvement of B cell linker/adapter protein (BLNK)/Bruton's tyrosine kinase (BTK). BTK plays a key role in B cell antigen receptor (BCR)-coupled signaling but not known to be expressed in ECs or play a role in EC function. Here we confirmed BTK expression in ECs by immunoblotting. Inhibition of BTK by a specific inhibitor terreic acid or by shRNA mediated knockdown decreased PKCβ-S661 phosphorylation and restored NFkB activation in ECs suggesting a critical role of BLNK/BTK in the EC. Thus, we have identified BLNK/BTK as a potentially new component of the NFkB pathway in ECs that may be a therapeutic target to improve PAD outcomes in diabetes. Presentation: Saturday, June 11, 2022 1:06 p.m. - 1:11 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Directional sensors, if collocated but perpendicularly oriented among themselves, would facilitate signal processing to uncouple the azimuth-polar direction from the time-frequency dimension-in addition to the physical advantage of spatial compactness. One such acoustical sensing unit is the well-known "tri-axial velocity sensor" (also known as the "gradient sensor," the "velocity-sensor triad," the "acoustic vector sensor," and the "vector hydrophone"), which comprises three identical figure-8 sensors of the first directivity-order, collocated spatially but oriented perpendicularly of each other. The directivity of the figure-8 sensors is hypothetically raised to a higher order in this analytical investigation with an innocent hope to sharpen the overall triad's directionality and steerability. Against this wishful aspiration, this paper rigorously analyzes how the directivity-order would affect the triad's "spatial-matched-filter" beam's directional steering capability, revealing which directivity-order(s) would allow the beam-pattern of full maneuverability toward any azimuthal direction and which directivity-order(s) cannot. Published version S.S.D. and K.T.W. were supported, in part, by the National Natural Science Foundation of China via Grant No. 62071018. Y.S. was supported, in part, by the National Natural Science Foundation of China via Grant No. 61801128.

The use of additive manufacturing and different metallization techniques for prototyping radio frequency components such as antennas and waveguides are rising owing to their high precision and low costs. Over time, additive manufacturing has improved so that its utilization is accepted in satellite payloads and military applications. However, there is no record of the frequency response in the millimeter-wave band for inductive 3D frequency selective structures implemented by different metallization techniques. For this reason, three different prototypes of dielectric 3D frequency selective structures working in the millimeter-wave band are designed, simulated, and manufactured using VAT photopolymerization. These prototypes are subsequently metallized using metallic paint atomization and electroplating. The manufactured prototypes have been carefully selected, considering their design complexity, starting with the simplest, the square aperture, the medium complexity, the woodpile structure, and the most complex, the torus structure. Then, each structure is measured before and after the metallization process using a measurement bench. The metallization used for the measurement is nickel spray flowed by the copper electroplating. For the electroplating, a detailed table showing the total area to be metallized and the current applied is also provided. Finally, the effectiveness of both metallization techniques is compared with the simulations performed using CST Microwave Studio. Results indicate that a shifted and reduced band-pass is obtained in some structures. On the other hand, for very complex structures, as in the torus case, band-pass with lower loss is obtained using copper electroplating, thus allowing the manufacturing of inductive 3D frequency selective structures in the millimeter-wave band at a low cost.

Peripheral artery disease (PAD) is caused by atherosclerotic occlusion of vessels outside the heart and most commonly affects vessels of the lower extremities. Angiogenesis is a part of the post ischemic adaption involved in restoring blood flow in PAD. Previously, in a murine hind limb ischemia (HLI) model of PAD, we identified ADAM12 as a key genetic modifier of post-ischemic perfusion recovery. However, less is known about ADAM12 regulation in ischemia. MiRNAs are a class of small, non-coding, single-stranded RNAs that regulate gene expression primarily through transcriptional repression of mRNA. We showed miR29a modulates ADAM12 expression in the setting of type 1 DM and ischemia. However, how miR29a modulates ADAM12 was not known. Moreover, the physiological effects of miR29a modulation in a non-diabetic setting was not known. Here, we demonstrate that AAV-mediated ectopic overexpression of miR29a in ischemic mouse hind limbs impairs post ischemic perfusion recovery and angiogenesis. We further demonstrate that miR29a regulates ADAM12 through direct interaction with ADAM12 mRNA. Treatment of ischemic mouse hind limbs with AAV9 particles containing miR29a (pAV-miR29a) increased miR29a expression (pAV-control vs pAV-miR29a: 3.22 ± 0.36, vs 1.0 ± 0.09, p

This paper describes the collaborative development of an agenda for research on e-assessment in university mathematics. We adapted an established approach to develop the agenda from the contributions of 22 mathematics education researchers, university teachers and learning technologists interested in this topic. The resulting set of 55 questions are grouped into 5 broad themes: errors and feedback, students, design and implementation, affordances, and mathematical skills. This agenda gives the framework for a programme of research aligned with practical concerns, that will contribute to both theoretical and practical development.

Efficient first-principle simulation with self-consistence of the feedback-interferometric fiber laser sensor has been studied. The feedback-interferometric fiber laser sensor consists of a Distributed Bragg Reflectors/Distributed Feedback (DBR/DFB) fiber laser and an external feedback sensing element. The approach is self-consistent in that it effectively integrates the inter-dependence of the 980-nm pump/1550-nm laser powers and the rate equations of the Er/Yb co-doped fiber laser medium. The 1550-nm laser field is efficiently solved by Coupled Modes Theory (CMT) method while the solutions of the rate equations are obtained with the iterative Newton-Raphson method. Four types of external reflection schemes have been simulated: 1) without reflection at either side; 2) reflection at the pump side; 3) reflection at the remote side; and 4) reflections at both sides of the fiber laser. With the self-consistent simulation, the lasing wavelength and lasing signal power for various reflection schemes are obtained. In this investigation, the procedure to optimize the reflections to achieve optimal sensor sensitivity is demonstrated.

Peripheral artery disease (PAD) is caused by atherosclerotic occlusions of vessels outside the heart, particularly those of the lower extremities. Angiogenesis is one critical physiological response to vessel occlusion in PAD, but our understanding of the molecular mechanisms involved in angiogenesis is incomplete. Dual specificity phosphatase 5 (DUSP5) has been shown to play a key role in embryonic vascular development, but its role in post-ischemic angiogenesis is not known. We induced hind limb ischemia in mice and found robust upregulation of Dusp5 expression in ischemic hind limbs. Moreover, in vivo knockdown of Dusp5 resulted in impaired perfusion recovery in ischemic limbs and was associated with increased limb necrosis. In vitro studies showed upregulation of DUSP5 in human endothelial cells exposed to ischemia, and knockdown of DUSP5 in these ischemic endothelial cells resulted in impaired endothelial cell proliferation and angiogenesis, but did not alter apoptosis. Finally, we show that these effects of DUSP5 on post-ischemic angiogenesis are a result of DUSP5-dependent decrease in ERK1/2 phosphorylation and p21 protein expression. Thus, we have identified a role of DUSP5 in post-ischemic angiogenesis and implicated a DUSP5-ERK-p21 pathway that may serve as a therapeutic target for the modulation of post-ischemic angiogenesis in PAD.

Using two electrically long dipoles to estimate the polarizations of impinging sources, this paper pioneers signal-processing algorithms in closed forms. The existing literature on crossed-dipoles polarimetry are restricted to electrically short dipoles with an electrical length of $(L/\lambda) \le (1/10)$ , which have subpar efficiency in radiation and in reception. In contrast, this paper allows electrically long dipoles—two of them here are perpendicularly oriented but may be collocated or may be separated by a known displacement. Using such a pair of electrically long dipoles for polarization estimation, this paper proposes new closed-form formulas and derives the associated Cramer–Rao bounds.

An eight-element broadband wide-beam circularly polarized (CP) antenna array is developed for mobile wireless communications. The CP antenna element consists of two rectangular loops with gaps for circular polarization and parasitic elements for bandwidth enhancement. A wide beamwidth is achieved in the horizontal plane because the CP antenna elements have a narrow cross section in the plane. The CP antenna array also has higher isolation between antenna elements than a linear polarized (LP) array with the same element space, which is due to the polarization mismatch caused by the currents in the CP antenna elements. The eight-element CP antenna array achieves a bandwidth of 40% (1.7–2.55 GHz) for return loss >15 dB and a bandwidth of 47% (1.67–2.7 GHz) for axial ratio (AR) < 3 dB. The half-power beamwidth and the 3 dB AR beamwidth in the horizontal plane are ~65° ± 8° and approximately 100°, respectively. The antenna gain for the array is about 17 dBi. The CP antenna array is suitable for applications in urban macrocell base stations.

Peripheral artery disease (PAD) is characterized by impaired blood flow to the lower extremities, resulting in ischemic limb injuries. Individuals with diabetes and PAD typically have more severe ischemic limb injuries and limb amputations, but the mechanisms involved are poorly understood. Previously, we identified BAG3 as a gene within a mouse genetic locus termed limb salvage QTL1 on mouse chromosome 7 that determined the extent of limb necrosis following ischemic injury in C57Bl/6 mice. Whether BAG3 deficiency plays a role in the severe ischemic injury observed in diabetic PAD is not known. In vitro, we found simulated ischemia enhanced BAG3 expression in primary human skeletal muscle cells, whereas BAG3 knockdown increased necroptosis markers and decreased cell viability. In vivo, ischemic skeletal muscles from hind limbs of high-fat diet (HFD)-fed mice showed poor BAG3 expression compared to normal chow diet (NCD)-fed mice, and this was associated with increased limb amputations. BAG3 overexpression in ischemic skeletal muscles from hind limbs of HFD mice rescued limb amputation and improved autophagy, necroptosis, skeletal muscle function and regeneration. Therefore, BAG3 deficiency in ischemic skeletal muscles contributes to the severity of ischemic limb injury in diabetic PAD, likely through autophagy and necroptosis pathways.

To identify a length scale to characterize space-charge interactions in semiconductor nanoparticles (SNPs), numerical solutions to a system of equations based on charge transport and electromagnetic field coupling were studied, leading to the notion of a frequency dependent Debye length, which can be seen to evolve from the static case where the space charge satisfies the Poisson-Boltzmann equation. An effective field formulation was developed to enable the computation of the total induced dipole moment of simple clusters of SNPs. The dipole moment facilitates construction of equivalent circuits for the SNPs as well as the representation of the polarization in terms of point dipoles. Computational results obtained for a semiconductor nanodimer are employed to delineate the application of the formulation.

Semiconductor nanodimer provides substantial terahertz electric field intensification in the gap region as a result of geometric local field effect and surface plasmon resonance. In a dimer formed by two nanoparticles with unequal doping levels, the intrinsic resonances of the nanoparticles are carried over to the coupled configuration of the dimer, giving rise to two resonances, slightly shifted from those of the intrinsic particles. An important characteristic of the enhanced field in the gap is the intensity profile swaying when the frequency of the applied field is varied from one resonance to the other. In this work, the field distribution in an asymmetric semiconductor nanodimer is computed by numerical simulation of the charge-field interaction in the semiconductor, employing a transport formulation for charge dynamics. Charge distribution in the semiconductor, field intensity in the gap and the collective response in terms of the total dipole moment are obtained. Interpretation of the results is presented in light of polarization coupling and interference effects between the particles. Potential application of the dynamical response as a field scanning sensor in the terahertz range is explored.

The consensus molecular subtype (CMS) classification of colorectal cancer is based on bulk transcriptomics. The underlying epithelial cell diversity remains unclear. We analyzed 373,058 single-cell transcriptomes from 63 patients, focusing on 49,155 epithelial cells. We identified a pervasive genetic and transcriptomic dichotomy of malignant cells, based on distinct gene expression, DNA copy number and gene regulatory network. We recapitulated these subtypes in bulk transcriptomes from 3,614 patients. The two intrinsic subtypes, iCMS2 and iCMS3, refine CMS. iCMS3 comprises microsatellite unstable (MSI-H) cancers and one-third of microsatellite-stable (MSS) tumors. iCMS3 MSS cancers are transcriptomically more similar to MSI-H cancers than to other MSS cancers. CMS4 cancers had either iCMS2 or iCMS3 epithelium; the latter had the worst prognosis. We defined the intrinsic epithelial axis of colorectal cancer and propose a refined 'IMF' classification with five subtypes, combining intrinsic epithelial subtype (I), microsatellite instability status (M) and fibrosis (F). ispartof: NATURE GENETICS vol:54 issue:7 pages:963-+ ispartof: location:United States status: published

Marine ecosystems with a diverse range of animal groups became established during the early Cambrian (~541 to ~509 Ma). However, Earth’s environmental parameters and palaeogeography in this interval of major macro-evolutionary change remain poorly constrained. Here, we test contrasting hypotheses of continental configuration and climate that have profound implications for interpreting Cambrian environmental proxies. We integrate general circulation models and geological observations to test three variants of the ‘Antarctocentric’ paradigm, with a southern polar continent, and an ‘equatorial’ configuration that lacks polar continents. This quantitative framework can be applied to other deep-time intervals when environmental proxy data are scarce. Our results show that the Antarctocentric palaeogeographic paradigm can reconcile geological data and simulated Cambrian climate. Our analyses indicate a greenhouse climate during the Cambrian animal radiation, with mean annual sea-surface temperatures between ~9 °C to ~19 °C and ~30 °C to ~38 °C for polar and tropical palaeolatitudes, respectively., There is a lot of uncertainty about what Earth’s climate and geography were like in the early Cambrian, when animal life diversified throughout the oceans. Here we show that numeric comparisons of model simulations and climatically influenced rocks can help constrain geography and climate during this time.

We evaluate the micromagnetic energy of a domain wall contained in a thin, horn-shaped nanostructure and propose a method to extract the strength of the interfacial Dzyaloshinskii-Moriya interaction based on the equilibrium position of the wall. An inplane magnetic field coupled with the interfacial DMI balances a competing driving force related to the "nanohorn" tapering and consequent variation in length. It is evident that the strength of the the DMI is directly correlated to the equilibrium position of the DW. Moreover, the range of measurable DMI values can be controlled by varying the degree of tapering in the nanohorn. Numerical and semi-analytical calculations were separately performed and show broad agreement. The calculations provided here offer an alternative framework for future measurement of DMI, which has been notoriously difficult to do experimentally., 3 pages, 3 figures, submitted to IEEE Transactions on Magnetics

Two new graptolite assemblages are identified from discrete intervals within the Phu Ngu Formation, Na Ri District, Bac Kan Province, north-east Vietnam. The graptolites occur in laminated mud/siltstones thought to be distal turbidite deposits. A low-diversity diplograptid sensu lato assemblage occurs in mud-rich layers that are interlaminated with silty and sandy horizons containing the dendroid graptolite Dictyonema sp. This level also contains orthoconic nautiloids and conulariids. A few metres stratigraphically above, a second more diverse graptolite assemblage comprises a single Dicellograptus, tentatively identified as D. flexuosus, together with Climacograptus dorotheus and Orthograptus truncatus pauperatus in mud and silt laminae that also yield brachiopods, orthoconic nautiloids, conulariids, fragmentary trilobites, and ostracods. The ostracods include the first East Asian occurrence of the typically Baltic genus Kinnekullea, and we describe the new species Kinnekullea gaia. The graptolites suggest a Late Ordovician Katian age, most probably in the Dicranograptus clingani Biozone, this being older than previous biostratigraphical constraints on the Phu Ngu Formation.

Drilling into carbonate reservoirs presents challenges involving damaging vibrations to drilling assembly components, encountering total drilling fluid losses, formation damage, potential loss of directional control if drilling into karst structures, and formation evaluation, particularly with high reservoir uncertainty. These challenges are exacerbated by the need to drill a long, relatively smooth 6,000-ft horizontal ERD well for autonomous inflow control device (AICD) smart well completion at 45 ft TVDss below the GOC. This paper describes collaborative efforts amongst different facets of drilling, fluids, and drill bits with the operator drilling team. Planning, risk assessment, directional drilling, and formation evaluation solutions are discussed for total drilling performance from spud to well TD for three wells in Phase 1 of this campaign. The elongated narrow nature of the carbonate pinnacles and optimal oil ultimate recovery dictates horizontal production hole placement in the mid-point of the thin oil rim. Well designs were optimized with consideration for anticollision risk, optimum reservoir recovery, karst avoidance, shallow hazard, extended reach drilling the long horizontal section with minimal undulation, in-field referencing (IFR) surveys to minimize well bore uncertainty, fluid management for optimum hole cleaning, and drill bit designed for penetration rate and minimal vibration. BHAs were modeled for directional control, drilling efficiency and damaging vibrations from drill-bit and BHA components. BHA simulation incorporating downhole vibration isolation tool mitigates and decouples damaging vibrations. The high fluctuation of 5 to 40 kpsi compressive strength from offset Carbonate sections induces vibration damage to drill-bit cutters if not designed out. Fluids design focused on drilling using a waterbased mud and readiness to combat severe or total losses. Fluids design for the horizontal section requires both an easy to clean filter-cake if switched to Pressurize Mud Cap Drilling (PMCD), and on acid-degradability of the filter-cake if drilled using conventional drilling allowing the application of an in-situ acid generator filter-cake breaker system, optimized fluid performance for hole cleaning, pressure management, and torque and drag reduction by means of nondamaging lubricants. The ultradeep-resistivity inversion successfully mapped and reduced seismic uncertainties and achieved optimal well placement within the thin oil rim. The rigorous planning and risk mitigations paid dividends. All three wells were flawlessly drilled with one run BHA in each hole sections, no karst losses necessitating PMCD, and delivery within a 10-ft TVDss window for the 6,000-ft horizontal sections. Drilling rate of penetration was 50% faster compared to offset benchmarking, setting new best in class performance for the Sarawak carbonate field. Particle size distribution in the drill- in fluid was kept within a narrow range to maximize bridging and reduce fines invasion. The combination of a nondamaging fluid and in situ acid precursor rendered predicted hydrocarbon production above expected productivity of the well.

IntroductionHamstring 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 analysisThis 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 disseminationEthics 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.Trial registration numberISRCTN76844299.