Influence of clay properties on shoe-kinematics and friction during tennis movements

Tennis is a sport characterised by being played on different surfaces: hard court, grass and clay. These surfaces influence the style of play and tennis specific movements. Specifically on clay, most of the common movements performed by players (e.g. accelerating, side stepping and braking), are performed with some level of controlled sliding. In order to reduce the player's injury risk, and assess the shoe-surface requirements on clay surfaces, there is a need for a scientific understanding of the player's kinematics and tribological mechanisms occurring at the shoe-surface interface. The purpose of this study was to identify the kinematics of the shoe during the sliding phase, and to assess the friction that is present. Baseline areas of both ends of a clay court were prepared with two different mixes of clay, varying the particle size. Eight experienced clay players participated in this study which took place during the Conde de Godó tennis tournament in Barcelona, Spain. 3D kinematic data data was collected using two synchronised high speed video cameras, and after the tests, perception questionnaires were applied to the players. Additionally, three different mechanical devices were utilised to measure the friction of the two clay surfaces. Displacement and velocity data of the shoe in contact with the surface were correlated with the friction measurements from both clay surfaces. Results indicated that significant differences occurred between the two clay surfaces for some shoe kinematic data, and mechanical friction. However, the perception scores suggest the opposite behaviour stated by the mechanical test and shoe-kinematic data. The present study has provided evidence that shoe kinematics and friction of the shoe-surface interaction are affected by the surface conditions, specifically particle size

SU(3) Predictions for Weak Decays of Doubly Heavy Baryons -- including SU(3) breaking terms

We find expressions for the weak decay amplitudes of baryons containing two b quarks (or one b and one c quark -- many relationship are the same) in terms of unknown reduced matrix elements. This project was originally motivated by the request of the FNAL Run II b Physics Workshop organizers for a guide to experimentalists in their search for as yet unobserved hadrons. We include an analysis of linear SU(3) breaking terms in addition to relationships generated by unbroken SU(3) symmetry, and relate these to expressions in terms of the complete set of possible reduced matrix elements.Comment: 49 page

Effect of slight crosslinking on the mechanical relaxation behavior of poly(2-ethoxyethyl methacrylate) chains

The synthesis, thermal and mechanical characterizations of uncrosslinked and lightly crosslinked poly(2-ethoxyethyl methacrylate) are reported. The uncrosslinked poly(2-ethoxyethyl methacrylate) exhibits in the glassy state two relaxations called in increasing order of temperature, the gamma and beta processes respectively. These are followed by a prominent glass rubber or alpha relaxation. By decreasing the chains mobility by a small amount of crosslinking, the beta relaxation disappears and the peak maximum associated with the alpha relaxation is shifted from 268 K to 278 K, at 1 Hz. An investigation of the storage relaxation modulus of the crosslinked polymer indicates two inflexion points that presumably are related to segmental motions of dangling chains of the crosslinked networks and to cooperative motions of the chains between crosslinking points. Nanodomains formed by side-groups flanked by the backbone give rise to a Maxwell Wagner Sillars relaxation in the dielectric spectra that have no incidence in the mechanical relaxation spectra.We thank Dr. J. Guzman (Madrid) for providing us with the CEOEMA sample. This work was financially supported by the DGCYT and CAM through the Grant MAT2008-06725-C03 and MAT2012-33483. In memoriam of Professor Emeritus Evaristo Riande in recognition of his contribution to Polymer Science.Carsí Rosique, M.; Sanchis Sánchez, MJ.; Díaz Calleja, R.; Riande, E.; Nugent, MJD. (2013). Effect of slight crosslinking on the mechanical relaxation behavior of poly(2-ethoxyethyl methacrylate) chains. European Polymer Journal. 49(6):1495-1502. doi:10.1016/j.eurpolymj.2012.12.012S1495150249

Molecular dynamics of carrageenan composites reinforced with Cloisite Na+ montmorillonite nanoclay

[EN] Nanocomposites comprising biodegradable carrageenan and glycerol(KCg) as the host polymer, with different contents of natural montmorillonite (MMT) as filler, were prepared by a solution casting process. Different techniques have been used to determine the interaction/behavior among the different components of the samples such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscope (TEM) and, mainly, Dielectric relaxation spectroscopy (DRS). FTIR indicates hydrogen interaction between carrageenan matrix and silicate that is confirmed by the XRD data indicating some kind of carrageenan intercalation between the MMT layers. A rather homogenous distribution of MMT into KCg matrix were observed using transmission electron microscopy. The MMT effect on the molecular mobility at the glass transition was studied by dielectric relaxation spectroscopy. The MMT addition resulted in a slower relaxation and a wider distribution ofthe relaxation times. The fragility index, m, increased upon MMT incorporation, which may be attributed to a reduction in mobility chains, due to the MMT confinement of the KCg network. In addition, the apparent activation energy associated with the relaxation dynamics of the chains at Tg increased with the MMT content. The modified films developed in this paper could be used to prepare biodegradable and edible packaging films and films for biomedical applications with improved mechanical and good dielectric response.This work was supported by the Direccion General de Ciencia y Tecnologia (DGCYT) [MAT2015-63955-R]; the Vice-Rectorate for Research of the Pontificia Universidad Catolica del Peru and the National Council of Science, Technology and Technological Innovation of Peru (CONCYTEC/FONDECYT).Sanchis Sánchez, MJ.; Carsí Rosique, M.; Culebras, M.; Gomez- Clari, CM.; Rodríguez, S.; García-Torres. F. (2017). Molecular dynamics of carrageenan composites reinforced with Cloisite Na+ montmorillonite nanoclay. Carbohydrate Polymers. 176:117-126. https://doi.org/10.1016/j.carbpol.2017.08.012S11712617

Methodology based on genetic heuristics for in-vivo characterizing the patient-specific biomechanical behavior of the breast tissues

[EN] This paper presents a novel methodology to in-vivo estimate the elastic constants of a constitutive model proposed to characterize the mechanical behavior of the breast tissues. An iterative search algorithm based on genetic heuristics was constructed to in-vivo estimate these parameters using only medical images, thus avoiding invasive measurements of the mechanical response of the breast tissues. For the first time, a combination of overlap and distance coefficients were used for the evaluation of the similar- ity between a deformed MRI of the breast and a simulation of that deformation. The methodology was validated using breast software phantoms for virtual clinical trials, compressed to mimic MRI-guided biopsies. The biomechanical model chosen to characterize the breast tissues was an anisotropic neo-Hookean hyperelastic model. Results from this analysis showed that the algorithm is able to find the elastic constants of the constitutive equations of the proposed model with a mean relative error of about 10%. Furthermore, the overlap between the reference deformation and the simulated deformation was of around 95% showing the good performance of the proposed methodology. This methodology can be easily extended to characterize the real biomechanical behavior of the breast tissues, which means a great novelty in the field of the simulation of the breast behavior for applications such as surgical planing, surgical guidance or cancer diagnosis. This reveals the impact and relevance of the presented work.This project has been funded by MECD (reference AP2009-2414) and US National Institutes of Health (R01 Grant #CA154444), and the US National Science Foundation (III Grant #0916690). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, and NSF. The authors of this manuscript have no conflict of interest with the presented workLago, MA.; Rupérez Moreno, MJ.; Martínez Martínez, F.; Martinez-Sanchis, S.; Bakic, P.; Monserrat, C. (2015). Methodology based on genetic heuristics for in-vivo characterizing the patient-specific biomechanical behavior of the breast tissues. Expert Systems with Applications. 42(21):7942-7950. https://doi.org/10.1016/j.eswa.2015.05.058S79427950422

Mass spectra of doubly heavy Omega_QQ' baryons

We evaluate the masses of baryons composed of two heavy quarks and a strange quark with account for spin-dependent splittings in the framework of potential model with the KKO potential motivated by QCD with a three-loop beta-function for the effective charge consistent with both the perturbative limit at short distances and linear confinement term at long distances between the quarks. The factorization of dynamics is supposed and explored in the nonrelativistic Schroedinger equation for the motion in the system of two heavy quarks constituting the doubly heavy diquark and the strange quark interaction with the diquark. The limits of approach, its justification and uncertainties are discussed. Excited quasistable states are classified by the quantum numbers of heavy diquark composed by the heavy quarks of the same flavor.Comment: 14 pages, revtex4-file, 3 eps-figures, 5 tables, typos correcte

An experimental study of dynamic behaviour of graphite polycarbonatediol polyurethane composites for protective coatings

Segmented polycarbonatediol polyurethane (PUPH) has been synthesized and modified with different amounts of graphite conductive filler (from 0 to 50 wt%). Thermal and dynamical thermal analysis of the composites clearly indicates changes in the polyurethane relaxations upon addition of graphite. Broadband dielectric spectroscopy has been used to study the dielectric properties of the (PUPH) and one composite in the frequency range from 10−2 to 107 Hz and in the temperature window of −140 to 170 ◦C. Relaxation processes associated with different molecular motions and conductivity phenomena (Maxwell–Wagner–Sillars and electrode polarization) are discussed and related to the graphite contentWe acknowledge the financial support of the Ministry of Finances and Competitiveness through the Grant CDS2010-0044 belonging to the "Consolider-Ingenio Programme" and for the Grant MAT2012-33483. The authors thank UBE Chem Eur for the PCD supply for this work.Gómez, C.; Culebras, M.; Cantarero Saez, A.; Redondo Foj, MB.; Ortiz Serna, MP.; Carsí Rosique, M.; Sanchis Sánchez, MJ. (2013). An experimental study of dynamic behaviour of graphite polycarbonatediol polyurethane composites for protective coatings. Applied Surface Science. 275:295-302. https://doi.org/10.1016/j.apsusc.2012.12.108S29530227

Electrical conductivity of natural rubber cellulose II nanocomposites

[EN] Nanocomposite materials obtained from natural rubber (NR) reinforced with different amounts of cellulose II (cell) nanoparticles (in the range of 0 to 30 phr) are studied by dielectric spectroscopy (DS) in a broad temperature range (¿150 to 150 °C). For comparative purposes, the pure materials, NR and cell, are also investigated. An analysis of the cell content effect on the conductive properties of the nanocomposites was carried out. The dielectric spectra exhibit conductivity phenomena at low frequencies and high temperatures: Maxwell¿Wagner¿ Sillars (MWS) and electrode polarization (EP) conductive processes were observed in the nanocomposite samples.We thank Professor Regina Nunes of the Instituto de Macromoleculas Eloisa Mano (Universidade Federal do Rio de Janeiro) for providing us the NR and NR-cell samples. This work was financially supported by DGCYT through grant MAT2012-33483.Ortiz Serna, MP.; Carsí Rosique, M.; Redondo Foj, MB.; Sanchis Sánchez, MJ. (2014). Electrical conductivity of natural rubber cellulose II nanocomposites. Journal of Non-Crystalline Solids. 405:180-187. https://doi.org/10.1016/j.jnoncrysol.2014.09.026S18018740

What to consider when pseudohypoparathyroidism is ruled out: IPPSD and differential diagnosis

Background: Pseudohypoparathyroidism (PHP) is a rare disease whose phenotypic features are rather difficult to identify in some cases. Thus, although these patients may present with the Albright''s hereditary osteodystrophy (AHO) phenotype, which is characterized by small stature, obesity with a rounded face, subcutaneous ossifications, mental retardation and brachydactyly, its manifestations are somewhat variable. Indeed, some of them present with a complete phenotype, whereas others show only subtle manifestations. In addition, the features of the AHO phenotype are not specific to it and a similar phenotype is also commonly observed in other syndromes. Brachydactyly type E (BDE) is the most specific and objective feature of the AHO phenotype, and several genes have been associated with syndromic BDE in the past few years. Moreover, these syndromes have a skeletal and endocrinological phenotype that overlaps with AHO/PHP. In light of the above, we have developed an algorithm to aid in genetic testing of patients with clinical features of AHO but with no causative molecular defect at the GNAS locus. Starting with the feature of brachydactyly, this algorithm allows the differential diagnosis to be broadened and, with the addition of other clinical features, can guide genetic testing. Methods: We reviewed our series of patients (n = 23) with a clinical diagnosis of AHO and with brachydactyly type E or similar pattern, who were negative for GNAS anomalies, and classify them according to the diagnosis algorithm to finally propose and analyse the most probable gene(s) in each case. Results: A review of the clinical data for our series of patients, and subsequent analysis of the candidate gene(s), allowed detection of the underlying molecular defect in 12 out of 23 patients: five patients harboured a mutation in PRKAR1A, one in PDE4D, four in TRPS1 and two in PTHLH. Conclusions: This study confirmed that the screening of other genes implicated in syndromes with BDE and AHO or a similar phenotype is very helpful for establishing a correct genetic diagnosis for those patients who have been misdiagnosed with "AHO-like phenotype" with an unknown genetic cause, and also for better describing the characteristic and differential features of these less common syndromes

A framework for modelling the biomechanical behaviour of the human liver during breathing in real time using machine learning

Progress in biomechanical modelling of human soft tissue is the basis for the development of new clinical applications capable of improving the diagnosis and treatment of some diseases (e.g. cancer), as well as the surgical planning and guidance of some interventions. The finite element method (FEM) is one of the most popular techniques used to predict the deformation of the human soft tissue due to its high accuracy. However, FEM has an associated high computational cost, which makes it difficult its integration in real-time computer-aided surgery systems. An alternative for simulating the mechanical behaviour of human organs in real time comes from the use of machine learning (ML) techniques, which are much faster than FEM. This paper assesses the feasibility of ML methods for modelling the biomechanical behaviour of the human liver during the breathing process, which is crucial for guiding surgeons during interventions where it is critical to track this deformation (e.g. some specific kind of biopsies) or for the accurate application of radiotherapy dose to liver tumours. For this purpose, different ML regression models were investigated, including three tree-based methods (decision trees, random forests and extremely randomised trees) and other two simpler regression techniques (dummy model and linear regression). In order to build and validate the ML models, a labelled data set was constructed from modelling the deformation of eight ex-vivo human livers using FEM. The best prediction performance was obtained using extremely randomised trees, with a mean error of 0.07 mm and all the samples with an error under 1 mm. The achieved results lay the foundation for the future development of some real-time software capable of simulating the human liver deformation during the breathing process during clinical interventions.This work has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) through research projects TIN2014-52033-R and DPI2013-40859-R, both also supported by European FEDER funds. The authors acknowledge the kind collaboration of the personnel from the hospital involved in the research.Lorente, D.; Martínez-Martínez, F.; Rupérez Moreno, MJ.; Lago, MA.; Martínez-Sober, M.; Escandell-Montero, P.; Martínez-Martínez, JM.... (2017). A framework for modelling the biomechanical behaviour of the human liver during breathing in real time using machine learning. Expert Systems with Applications. 71:342-357. doi:10.1016/j.eswa.2016.11.037S3423577