Extreme Angles Research Articles

Excitation of the electric pygmy dipole resonance by inelastic electron scattering⋆

To complete earlier studies of the properties of the electric pygmy dipole resonance (PDR) obtained in various nuclear reactions, the excitation of the 1$^-$ states in $^{140}$Ce by $(e,e')$ scattering for momentum transfers $q=0.1-1.2$~fm$^{-1}$ is calculated within the plane-wave and distorted-wave Born approximations. The excited states of the nucleus are described within the Quasiparticle Random Phase Approximation (QRPA), but also within the Quasiparticle-Phonon Model (QPM) by accounting for the coupling to complex configurations. It is demonstrated that the excitation mechanism of the PDR states in $(e,e')$ reactions is predominantly of transversal nature for scattering angles $\theta_e \approx 90^o-180^o$. Being thus mediated by the convection and spin nuclear currents, the $(e,e')$ like the $(\gamma,\gamma')$ reaction, may provide additional information to the one obtained from Coulomb- and hadronic excitations of the PDR in $(p,p')$, $(\alpha,\alpha')$, and heavy-ion scattering reactions. The calculations predict that the $(e,e')$ cross sections for the strongest individual PDR states are in general about three orders of magnitude smaller as compared to the one of the lowest $2^+_1$ state for the studied kinematics, but that they may become dominant at extreme backward angles.

Robotic-assisted simultaneous resection of a left-sided thymic neoplasm and a right-sided lower thoracic paravertebral neoplasm via the same ports and two docking steps: a case report

BackgroundThe authors presented a 63-year old female synchronously complicated with a thymic tumor located at the left-side of the superior mediastinum, and a paravertebral tumor located at the right-side of the lower thorax. Conventional thoracoscopic surgical procedure using rigid instruments to simultaneously resect the two tumors via the same ports might be technically challenging. To our knowledge, the use of a surgical robot allowed the surgeon to perform precise dissection from extreme angles with the characteristic of articulating surgical instruments.Case presentationTwo lesions were successfully dissected using the da Vinci Surgical System through the same four ports on the right side of the chest and two-step docking. Firstly, the patient cart came from the dorsal side of the patient and the paravertebral neoplasm was dissected. Afterwards, the patient cart was undocked and the operation table was rotated 180 degrees counterclockwise. The robot was re-introduced and the patient cart came from the ventral side of the patient and the whole thymus was resected.ConclusionThis case report suggests that two-step docking via the same four ports for these two tumors located at different directions of the thorax was safe and effective, demonstrating a clear advantage of the surgical robot.

Multiangle retrodirective cascaded metasurface

In this paper, a cascaded retrodirective metasurface is designed and demonstrated to operate simultaneously at a wide range of incident angles from −30° to −10° and 10° to 30°. It is based on the design of several retrodirective super-cells following the generalized Snell’s law of reflection, where each super-cell is designed to redirect an incoming wave back in the same direction with high efficiency. This metasurface is a very good candidate as a retroreflector for radar cross-section (RCS) enhancement of targets with poor backscattering. Retrodirective topologies have been a subject of interest, and several engineered topologies exist, such as the corner dihedral. Despite their good performances at a range of incident angles, their 3-dimensional bulky structure makes them hard to implement for different applications and they do not address extreme incident angles. The metasurface proposed can be a complementary solution to existing topologies for addressing extreme oblique incident angles while being more compact due to its two-dimensional subwavelength structure design. The monostatic radar cross-section (RCS) performance of the designed metasurface of dimensions 8.163×56.23 cm2 has been compared to that of a conventional corner dihedral of dimensions 8×15.5×7.75 cm3, and a gain of up to 50 dB of monostatic radar cross section (RCS) in the ranges −30° to −20° and 20° to 30° was obtained. Comparable performances are observed in the ranges −20° to −10° and 10° to 20° between the designed metasurface and the corner dihedral. Experimental results are shown to be in good agreement with simulation results.

Production of $ \phi$(2170) and $ \eta$(2225) in a kaon induced reaction

In this work, we study the production of strange quarkoniums, the $\phi(2170)$, also named $Y(2175)$, and the $\eta(2225)$, via a kaon induced reaction on a proton target in an effective Lagrangian approach. The total and differential cross sections of the reactions $K^{-}p\rightarrow \phi (2170)\Lambda $ and $K^{-}p\rightarrow \eta (2225)\Lambda $ are calculated by the Reggeized $t $-channel Born term under an assumption that the $\phi(2170)$ and $\eta(2225)$ are $\Lambda\bar{\Lambda}$ molecular states. At the center of mass energies of about 4.2 GeV, the total cross section for the $\phi(2170)$ production is predicted to be about 1 $\mu $b. The numerical results indicate that it is feasible to produce the $\phi (2170)$ via kaon beam scattering at the best energy window near 4.2 GeV. The total cross section for the $\eta(2225)$ production is smaller than that for the $\phi(2170)$ production and it may reach an order of the magnitude of 0.1 $\mu$b. The differential cross sections for both reactions at different center of mass energies are also presented. It is found that the Reggeized $t$ channel gives a considerable contribution at forward angles. As the energy increases, the contribution from the $t$-channel almost concentrates at extreme forward angles. From these theoretical predictions, the relevant experimental research is suggested, which could provide important information to clarify the internal structure and production mechanism of these two strange quarkoniums.

Winglet effect on hydrodynamic performance and trajectory of a blended-wing-body underwater glider

Winglet has been widely used in aviation industries to improve the performance of aircraft. However, according to the authors' knowledge, the effect of winglet on underwater gliders has not been investigated in detail. This paper aims to investigate the impact of winglet on hydrodynamic performance and gliding trajectory of a blended-wing-body underwater glider (BWBUG). The hydrodynamic performance of the BWBUG without winglet (BWBUG-I) is firstly calculated. Then the hydrodynamic performance of BWBUG with winglet (BWBUG-II) is analyzed and compared. To estimate the influence of winglet on gliding trajectory, a dynamic model is established by considering the buoyancy and pitch regulating system. From the CFD results, the lift force acting on the glider is increased by the winglet, while the drag force remains at the same level. The lift-to-drag ratio is thereby improved. By comparing trajectories, the average gliding ratio for BWBUG-II is 5.10, 2.2% higher than 4.99 for BWBUG-I. With the winglet, the extreme attack angle is reduced from 7.2° to 6.1° when switching from rising to diving. The steady gliding speed is improved by 6.3%, and the squat depth is reduced by 11% under particular condition.

Topology optimization of metasurfaces for anomalous reflection of longitudinal elastic waves

A numerical method based on topology optimization is developed for designing a metasurface that anomalously reflects longitudinal elastic waves. While the analysis and design of metasurfaces and metamaterials have received much attention recently, no numerical method to design elastic metasurfaces for anomalous reflection has been explored. Here, we formulate a density-based topology optimization suitable for finding a set of phase-delaying unit cells forming a metasurface that anomalously reflects longitudinal waves impinged upon it. Each unit cell is designed to yield the specific phase delay between the incident and reflected elastic waves. The transfer matrix approach using the averaged finite element results is employed to efficiently and accurately calculate the phase delay while the wave phenomena are analyzed by the finite element analysis. As case studies, metasurfaces converting normally incident longitudinal waves to anomalously reflected longitudinal waves were designed. Various target anomalous reflection angles were considered including the extreme reflection angle of 90°. To investigate the numerical aspect of the developed method, we investigated the effect of the sizes of the unit cells, both along the perpendicular and normal directions to the wave incidence. The mesh dependence issue was also investigated. Finally, we applied the developed topology optimization method to design metasurfaces for wave focusing and trapping in a waveguide.

Pion-induced production of hidden-charm pentaquarks Pc(4312),Pc(4440), and Pc(4457)

The production of the hidden-charm pentaquarks via a pion-induced reaction on a proton target is investigated within an effective Lagrangian approach. Three experimentally observed states, Pc(4312), Pc(4440), and Pc(4457), are considered in calculation, and the Reggeized t-channel meson exchange is considered as main background for the reaction π−p→J/ψn. The numerical results show that the experimental data of the total cross section at W≃5 GeV can be well explained by the contribution from the Reggeized t channel with reasonable cutoff. If the branching ratios Br[Pc→J/ψN]≃3% and Br[Pc→πN]≃0.05% are taken, the average value of the cross section from the Pc(4312) is about 1.2 nb/100 MeV, which is consistent with existing rude data at near-threshold energies. The results indicate that the branching ratios of the Pc state decays into J/ψN and πN should be small. The differential cross section shows a sharp increase at extreme forward angles due to the Reggeized t-channel contribution while the contributions from the Pc states are relatively flat. High-precision experimental measurement on the reaction π−p→J/ψn at near-threshold energies is suggested to confirm the LHCb hidden-charm pentaquarks as genuine states, and such measurement is also helpful to understand the origins of these resonance structures.

Electric and magnetic dipole modes in high-resolution inelastic proton scattering at 0°

Inelastic proton scattering under extreme forward angles including $0^\circ$ and at energies of a few hundred MeV has been established as a new spectroscopic tool for the study of complete dipole strength distributions in nuclei. Such data allow an extraction of the electric dipole polarizability which provides important constraints parameters of the symmetry energy, which determine the neutron skin thickness and the equation of state (EOS) of neutron-rich matter. Also new insight into the much-debated nature of the pygmy dipole resonance (PDR) is obtained. Additionally, the isovector spin-M1 resonance can be studied in heavy nuclei, where only limited experimental information exists so far. Together with much improved results on the isoscalar spin-M1 strength distributions in $N = Z$ nuclei, these data shed new light on the phenomenon of quenching of the nuclear spin response. Using dispersion matching techniques, high energy resolution ($\Delta E/E \leq 10^{-4} \,\,$ full width at half maximum, FWHM) can be achieved in the experiments. In spherical-vibrational nuclei considerable fine structure is observed in the energy region of the isovector giant dipole resonance (IVGDR). A quantitative analysis of the fine structure with wavelet methods provides information on the role of different damping mechanisms contributing to the width of the IVGDR. Furthermore, level densities can be extracted from a fluctuation analysis at excitation energies well above neutron threshold, a region hardly accessible by other means. The combination of the gamma strength function (GSF) extracted from the E1 and M1 strength distributions with the independently derived level density permits novel tests of the Brink-Axel hypothesis underlying all calculations of statistical model reaction cross sections in astrophysical applications in the energy region of the PDR.

Sound Source Localization Fusion Algorithm and Performance Analysis of a Three-Plane Five-Element Microphone Array

To reduce the negative effect on sound source localization when the source is at an extreme angle and improve localization precision and stability, a theoretical model of a three-plane five-element microphone array is established, using time-delay values to judge the sound source’s quadrant position. Corresponding judgment criteria were proposed, solving the problem in which a single-plane array easily blurs the measured position. Based on sound source geometric localization, a formula for the sound source azimuth calculation of a single-plane five-element microphone array was derived. The sinusoids and cosines of two elevation angles based on two single-plane arrays were introduced into the sound source spherical coordinates as composite weighted coefficients, and a sound source localization fusion algorithm based on a three-plane five-element microphone array was proposed. The relationship between the time-delay estimation error, elevation angle, horizontal angle, and microphone array localization performance was discussed, and the precision and stability of ranging and direction finding were analyzed. The results show that the measurement precision of the distance from the sound source to the array center and the horizontal angle are improved one to threefold, and the measurement precision of the elevation angle is improved one to twofold. Although there is a small error, the overall performance of the sound source localization is stable, reflecting the advantages of the fusion algorithm.

Possibility to study the pentaquark states Pc(4312) , Pc(4440) , and Pc(4457) in the reaction γp→J/ψp

Inspired by the observation of the pentaquark states $P_{c}(4312),P_{c}(4440)$ and $P_{c}(4457)$ at LHCb, photoproduction of these three $P_{c}$ states via the interaction $\gamma p\rightarrow J/\psi p$ is investigated in an effective Lagrangian approach. The $t$-channel Pomeron exchange diffractive process is considered as the main background for the $J/\psi $ photoproduction. The numerical results show that the theoretical cross section, which is calculated by assuming a branching ratio $Br[P_{c}\rightarrow J/\psi p]\simeq 3\%$, is consistent with the existing experimental data of the $ \gamma p\rightarrow J/\psi p$ process. With such a branching ratio, if experimental precision reaches 0.1 nb within a bin of 100 MeV for photon energy, two peaks are expected to be obviously observed in the $J/\psi $ photoproduction. To observe the two-peak structure from $P_{c}(4440)$ and $ P_{c}(4457)$, higher precision, about 0.1nb/10 MeV, is required to distinguish two close pentaquarks. If the physical branching ratio is larger, the requirement of experimental precision will be reduced. The differential cross sections for reaction $\gamma p\rightarrow J/\psi p$ are also present. It is found that the $t$-channel Pomeron exchange provides a sharp increase at extreme forward angles and gives a sizable contribution at most energy points, while the contributions from the $s$-channel $P_{c}$ exchanges play important roles at threshold energies. The experimental measurement of the $\gamma p\rightarrow J/\psi p$ process in the near-threshold energy region around $E_{\gamma }\simeq 9.4-10.5$ GeV is suggested, and is accessible at CEBAF@JLab and COMPASS.

Modeling Star–Planet Interactions in Far-out Planetary and Exoplanetary Systems

Abstract The magnetized wind from a host star plays a vital role in shaping the magnetospheric configuration of the planets it harbors. We carry out three-dimensional (3D) compressible magnetohydrodynamic simulations of the interactions between magnetized stellar winds and planetary magnetospheres corresponding to a far-out star–planet system, with and without planetary dipole obliquity. We identify the pathways that lead to the formation of a dynamical steady-state magnetosphere and find that magnetic reconnection plays a fundamental role in the process. The magnetic energy density is found to be greater on the nightside than on the dayside, and the magnetotail is comparatively more dynamic. It is found that stellar wind plasma injection into the inner magnetosphere is possible through the magnetotail. We further study magnetospheres with extreme tilt angles, keeping in perspective the examples of Uranus and Neptune. High dipole obliquities may also manifest due to polarity excursions during planetary field reversals. We find that global magnetospheric reconnection sites change for large planetary dipole obliquity, and more complex current sheet structures are generated. We discuss the implications of these findings for atmospheric erosion, the introduction of stellar and interplanetary species that modify the composition of the atmosphere, auroral activity, and magnetospheric radio emission. This study is relevant for exploring star–planet interactions and its consequence on atmospheric dynamics and habitability in solar system planets and exoplanets.

Extreme angle, tip-tilt MEMS micromirror enabling full hemispheric, quasi-static optical coverage.

Beam steering is essential for a variety of optical applications such as communication, LIDAR, and imaging. Microelectromechanical system (MEMS) mirrors are an effective method of achieving modest speeds and angular range at low cost. Typically there are a number of tradeoffs considered when designing a tip-tilt mirror, such as tilt angle and speed. For example, many mirrors are designed to scan at their resonant frequency to achieve large angles. This is effective for a scanning mode; however, this makes the device slow and ineffective as a galvo (quasi-static). Here, we present a magnetic MEMS mirror with extreme quasi-static mechanical tilt angles of ±60° (±120° optical) about two rotation axes. This micromirror enables full hemispheric optical coverage without compromising speed; settling in 4.5 ms using advanced drive techniques. This mirror will enable new applications for MEMS micromirrors previously thought impossible due to their limited angular range and speed.

Prediction of mechanical behavior of cartilaginous infant hips in pavlik harness: A subject-specific simulation study on normal and dysplastic hips.

In dysplastic infant hips undergoing abduction harness treatment, cartilage contact pressure is believed to have a role in therapeutic cartilage remodeling and also in the complication of femoral head avascular necrosis. To improve our understanding of the role of contact pressure in the remodeling and the complication, we modeled cartilage contact pressure in cartilaginous infant hips undergoing Pavlik harness treatment. In subject-specific finite element modeling, we simulated contact pressure of normal and dysplastic hips in Pavlik harness at 90° flexion and gravity-induced abduction angles of 40°, 60° and 80°. We demonstrated that morphologies of acetabulum and femoral head both affected contact pressure distributions. The simulations showed that in Pavlik harness, contact pressure was mainly distributed along anterior and posterior acetabulum, leaving the acetabular roof only lightly loaded (normal hip) or unloaded (dysplastic hip). From a mechanobiological perspective, these conditions may contribute to therapeutic remodeling of the joint in Pavlik harness. Furthermore, contact pressure increased with the angle of abduction, until at the extreme abduction angle (80°), the lateral femoral head also contacted the posterior acetabular edge. Contact pressure in this area could contribute to femoral head avascular necrosis by reducing flow in femoral head blood vessels. The contact pressure we simulated can plausibly account for both the therapeutic effects and main adverse effect of abduction harness treatment for developmental dysplasia of the hip. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Productions of f1(1420) in pion and kaon induced reactions

The $f_{1}(1420)$ productions via pion and kaon induced reactions on a proton target are investigated in an effective Lagrangian approach. Two treatments of the $t$-channel Born term, the Feynman model and the Regge model, are introduced to calculate the total and differential cross sections of the $\pi^{-}p\rightarrow f_{1}(1420)n$ and $K^{-}p\rightarrow f_{1}(1420)\Lambda $ reactions. The numerical results indicate that the experimental data of the total cross section of the $\pi ^{-}p\rightarrow f_{1}(1420)n$ reaction can be reproduced in both the Feynman and the Regge models. Based on the parameters determined in the pion induced reaction, the cross sections of the $K^{-}p\rightarrow f_{1}(1420)\Lambda $ reaction, about which there is little data found in the literature, are predicted in the same beam momentum range. It is found that the line shapes of the total cross section obtained in a kaon induced reaction with two treatments are quite different. The cross sections for both reactions are at an order of magnitude of $\mu$b, or larger, at a beam momenta up to 10 GeV/c. The differential cross sections for both pion and kaon induced reactions are also present. It is found that in the Regge model, the $t$ channel provides a sharp increase at extreme forward angles. The results suggest that the experimental study of the $f_1(1420)$ in the kaon induced reaction on a proton target is as promising as in the pion induced reaction. Such an experimental measurement is also very helpful to clarify the production mechanism of the $f_1(1420)$.

Magnetometer-Based Phase Shifting Ratio Method for High Spinning Projectile’s Attitude Measurement

Accurate measurement of high spinning projectiles' attitude is the basis of guidance and control. In order to reduce the attitude measurement error and improve the attitude update rate, a magnetometer-based phase shifting ratio method is proposed in this paper. This method does not introduce additional installation errors as the existing methods, simplifies the calibration of the extreme value ratio-pitch angle curve, and makes full use of the measurement data of the sensors. The attitude update is synchronized with the magnetometer output without using the local geomagnetic information. Simultaneously, the local geomagnetic errors are avoided. The results of numerical simulation and semi-physical simulation experiments show that compared with the three orthogonal ratio method and the crest and trough method, the proposed algorithm in this paper can increase the attitude update rate by more than 2 times and the attitude calculation accuracy can be enhanced by 30%.

Low Complication Rate of Surgical Mitral Valve Replacement in High-Risk Patients

Introduction: Transcatheter mitral valve replacement (MVR) has emerged in recent times as a new technique in the field of cardiac interventions. However, significant challenges have been encountered, including mitral valve anatomy complexity, subvalvular apparatus, interaction with the left ventricular outflow tract and aortic valve. It requires large transcatheter devices and large catheters, which are required to negotiate an extreme angle within a relatively small space (through the transseptal approach) to reach the mitral valve (Ruguiero et al., 2017, Guerro et al., 2017). Transcatheter MVR has been associated with high 30-day mortality rates ranging from 25–50%. This study aimed to explore the functional and health outcomes of surgical MVR.

Wide band wide scan low cross‐polarised grooved tapered slot antenna array

The present study proposes a new geometry of tapered slot antenna (TSA), called as a grooved TSA ( GTSA ). The antenna is designed to operate in L-band for phased array applications. The topology of TSA's fins is modified by introducing electrically thin grooves, which split fins into separate sections, electromagnetically coupled to each other. The motive behind this modification is to reduce high cross-polarisation (x-pol) level in the radiation pattern of TSAs by altering the flow of surface currents intelligently. The design and optimisation are done using commercial FEM solver, HFSS . Furthermore, an embedded performance of GTSA in 7 × 7 elements array is presented. The mutual coupling between the array elements is minimised by the introduction of metallic baffles parallel to H -plane. GTSA demonstrates a fractional bandwidth of 0.58 illustrating a reflection coefficient <;-10 dB, half power beam width not less than 120° and 90° in E - and H -planes, respectively. It demonstrates an x-pol level <;-20 dB at the extreme scan angles (up to 60°) from the broad side. The GTSA array demonstrates a wide scan performance up to 60° from the broad side. The present work is extremely useful in the realisation of active-phased array radars.

Postquarter-Point Case of Ship’s Side-Berthing and Its Influence on Marine Fender Pitch

This paper presents a critical analysis of some selected codes and practical recommendations used as basic rules in the design procedures of modern marine fender systems. The first part of the discussion pertains to the existing equations used in calculating the eccentricity coefficient in the ship’s kinetic energy equation and the maximum allowable fender pitch (spacing) in a set of fenders installed along a quay wall. A new approach for the single-fender ship-to-fender contact mode during the side-berthing procedure is introduced, assuming three different special cases (i.e., the prequarter-point case, the quarter-point case, and the postquarter-point case) of the relative position of the ship’s hull with respect to the compressed fender unit. New equations are proposed for the maximum allowable fender pitch and the extreme berthing angles associated with the postquarter-point case of the single-fender and two-fender contact modes. Taking a ferry contact with an MV-type (or pi-type) modular fender as an example, a detailed computational analysis has been performed, illustrating permissible geometrical ship-fender-quay configurations and their influence on the eccentricity coefficient, and, consequently, on the effective kinetic energy of a berthing ship.

Differences in Strength & Power profiles between Road and Time Trial cyclists

Introduction Within the scientific literature there is little evidence available to provide practitioners with information on strength and power profiles of cyclists, resulting in a limited understanding of neuromuscular factors related to cycling performance. Information on the legs’ elastic energy utilisation, force-velocity and length-tension curves can inform training programs and aid in talent identification. Other sports where such information is more widely available have already successfully implemented this within preparation programmes (e.g. McBride et al., 1999). Methods A total of 44 cyclists were recruited for this project, of which 15 classified in a Novice category by having no racing experience at all (age 35.5 ± 11.4 yrs; height 177.4 ± 6.5 cm; mass 77.4 ± 9.3 kg; FTP 3.28 ± 0.47 W/kg), 14 in the Road racing category as they competed for at least the past year at British Cycling Category 2 level or higher and no experience in Time-Trial (TT) races (age 35.9 ± 12.7 yrs; height 179.1 ± 6.5 cm; mass 76.6 ± 9.0 kg; FTP 3.88 ± 0.49 W/kg), and 15 in the TT category as they considered TT racing as their main competitive aim, rode in dedicated TT positions and had recently produced a 10 or 25 mile personal best of 1) for all groups. This dominance was significantly less prominent in the TT group for flexion conditions (1.35 ± 0.18) compared to Road (1.56 ± 0.22; p = 0.031) and Novice (1.53 ± 0.19; p = 0.004) groups. Joint flexion torques showed non-significant trends; they were slightly higher in the knee and lower for the hip (1.43 & 2.08 Nm/kg respectively) in TT athletes compared to Road (1.35 & 2.14 Nm/kg) and Novices (1.36 & 2.22 Nm/kg) (p = 0.429 & 0.189). No differences were found for the angle at which peak torque occurred. The velocity effect on torque production was comparable between the groups. It decreased from its peak at 30 °/s, to 82 ± 11 % of that when tested at 270 °/s for knee flexion and to 61 ± 9 % for knee extension. Hip torque reduced to 66 ± 10 % and 79 ± 10 % for flexion and extension respectively, when tested at 210 °/s compared to 30 °/s condition. Discussion The CMJ data show that cyclists – both novice and competitive – perform poorly on vertical jumping (29 ± 6 cm) compared to strength trained (48.2 ± 2.8 cm) and even untrained individuals (33.7 ± 2.3 cm) (McBride et al., 1999). This is in line with previous research on endurance type athletes showing long-distance runners to perform inferiorly on jump tasks compared to an untrained population (27.8 ± 4.3 cm vs 37.3 ± 3.1 cm; Kubo et al., 2000). In contrast to the findings by Kubo et al. (2000), the tested competitive cyclists showed lower SJ/CMJ ratios compared to the untrained controls indicating a relatively large utilisation of elastic energy storage compared to muscular power in jump performance. Based on the dynamometry testing, it seems most plausible to suggest that the reduced hip flexion capacity in TT riders results from these muscles being disused during cycling due to the extreme hip flexion angles common in their riding positions. It could be suggested that an attempt is made to compensate for this loss in hip flexion capacity through increased knee flexors’ strength. An increased knee flexor torque in TT riders could also indicate a mechanically more effective pedalling technique on the bike, as previous literature has linked hamstring activity with increases in Index of Force Effectiveness on the bike (Bini et al., 2013). Greater separation between tested groups might have been masked due to variation in preferred bike setup within the groups, TT riders also training in road setups and novice cyclists having undergone minor adaptations through recreational cycling activities. Based on these results, it seems appropriate to advise strength training to be tailored to the type of competition a cyclist is aiming to perform on. TT riders should focus on knee flexor strength, while road cyclists could benefit from a more balanced approach between hip and knee strength. Currently ongoing research is investigating how these strength characteristics relate to determinants of cycling performance in order to further help optimising training protocols and talent identification strategies. References Bini RR, Hume P, Croft J, Kilding A. (2013) J Sci Cycl, 2(1), 11-24. Kubo K, Kanehisa H, Kawakami Y, Fukunaga T. (2000). EJAP, 81(3), 181-187. McBride JM, Triplett-McBride T, Davie H, Newton RU. (1999). J Biom, 32(10), 1021-1026. Cuk I, Markovic M, Nedeljkovic A, Ugarkovic D, Kukolj M, Jaric S. (2014). EJAP, 114(8), 1703-1714.

The design of large mode-area, single mode Yb:KYW rib loaded waveguide for high performance waveguide laser applications

Direct fiber-laser diode pumping is intriguing for waveguide laser operation, for robustness and high laser efficiency. However, the huge mismatch between waveguide and fiber modes limits the further improvement of waveguide laser performance. Here we design and take numerical study on the large-mode-area, single-mode Yb:KYW loaded-rib waveguide structure with tilt side walls, which is easy to fabricate using existing techniques. It is demonstrated that the waveguide structure guarantees direct butt coupling with insertion loss <3 dB for fibers with core diameter ranging from 11.0 to 55.5 μm. The effect of alignment mismatch is also studied, showing good alignment tolerance. The overlap ratio of modes between pumping and laser emission wavelength is as high as 99.84%, with extreme small laser divergence angle. These features make the waveguide promising candidate for high power waveguide laser applications.