1,611 research outputs found
Risk factors for major adverse cardiovascular events after osteoporotic hip fracture repair surgery
Osteoporotic hip fracture (OHF) is an increasingly frequent age-related pathology, which results in high rates of functional loss and mortality within the first year after surgery. This study assessed whether preoperative levels of brain natriuretic peptide (NT-proBNP) and troponin I were related to early occurrence (30d) of major adverse cardio-vascular events (MACE) after OHF repair surgery. During a 6-month period, perioperative clinical and analytical data from consecutive patients, without known history of cardiovascular disease and undergoing surgery for OHF repair at a single centre, were prospectively collected. MACE was defined as acute myocardial ischaemia or infarction, acute heart failure or cardiovascular death. amongst the 140 patients included, 23 (16.4%) developed postoperative MACE (MACE group) and 117 did not (Control group). Compared to those from control group, patients from MACE group were older, had poorer physical status (ASA III–IV), received preoperative red blood cell transfusion (RBCT) more frequently, presented with lower haemoglobin concentrations and higher NT-proBNP, creatinine and troponin I concentrations. Overall, RBCT requirements and 30d mortality rate were also higher in MACE group. However, in multivariate analysis, only preoperative RBCT, creatinine >1 mg/dL and NT-proBNP >450 pg/mL remained as independent preoperative risks factors for postoperative MACE, while 95% confidence intervals of odds ratios were wide. Though our findings require confirmation in a larger multicentre cohort, identifying risk factors for early postoperative MACE after OHF repair surgery, might facilitate assessing patients’ risk prior to and following surgery, and targeting them the appropriate preventive and/or therapeutic interventions
Arteriolopatía calcificante urémica, reporte de un caso tratado con tiosulfato de sodio
We describe a case of calcific uremic arteriolopathyinitially associated with skin lesions within the context of a patient with chronic kidney disease on automated peritoneal dialysis therapy. Among the most relevant findings, the patient hadhyperphosphatemia, normocalcemia and severe hyperparathyroidism without nodular hyperplasia. Clinical improvement with multimodal management of enhancement in dialysis therapy and intravenous sodium thiosulfate is highlighted. Calciphylaxis is a disorder that has a high morbidity and mortality, secondary to sepsis. It occurs more frequently in patients with chronic renal failure who are on hemodialysis. It is characterized by systemic medial calcification of the arterioles, triggering ischemia and subcutaneous necrosis of skin and soft tissues. Histopathological evaluation helps to confirm the diagnosis.Describimos un caso de arteriolopatía calcificante urémica asociada, inicialmente, a lesiones cutáneas,en unpaciente con insuficiencia renal crónica, en terapia de diálisis peritoneal automatizada, como hallazgos másrelevantes presentaba hiperfosfatemia, normocalcemia e hiperparatiroidismo severo sin hiperplasia nodular.Se destaca la mejoría clínica con manejo multimodal de intensificación en la terapia dialítica y tiosulfato desodio intravenoso.La calcifilaxis es un trastorno que debuta con alta morbilidad ymortalidad, secundaria a sepsis, ocurre con mayor frecuencia en pacientes con insuficiencia renal crónica que se encuentran en hemodiálisis. Se caracteriza por calcificación sistémica en la media de las arteriolas, desencadenándose isquemia y necrosis subcutánea de piel y tejidos blandos. La evaluación histopatológica ayuda a confirmar el diagnóstico
Evaluating the capacity of human gut microorganisms to colonize the zebrafish larvae (Danio rerio)
Indexación: Scopus.In this study we evaluated if zebrafish larvae can be colonized by human gut microorganisms. We tested two strategies: (1) through transplantation of a human fecal microbiota and (2) by successively transplanting aerotolerant anaerobic microorganisms, similar to the colonization in the human intestine during early life. We used conventionally raised zebrafish larvae harboring their own aerobic microbiota to improve the colonization of anaerobic microorganisms. The results showed with the fecal transplant, that some members of the human gut microbiota were transferred to larvae. Bacillus, Roseburia, Prevotella, Oscillospira, one unclassified genus of the family Ruminococcaceae and Enterobacteriaceae were detected in 3 days post fertilization (dpf) larvae; however only Bacillus persisted to 7 dpf. Successive inoculation of Lactobacillus, Bifidobacterium and Clostridioides did not improve their colonization, compared to individual inoculation of each bacterial species. Interestingly, the sporulating bacteria Bacillus clausii and Clostridioides difficile were the most persistent microorganisms. Their endospores persisted at least 5 days after inoculating 3 dpf larvae. However, when 5 dpf larvae were inoculated, the proportion of vegetative cells in larvae increased, revealing proliferation of the inoculated bacteria and better colonization of the host. In conclusion, these results suggest that it is feasible to colonize zebrafish larvae with some human bacteria, such as C. difficile and Bacillus and open an interesting area to study interactions between these microorganisms and the host. © 2018 Valenzuela, Caruffo, Herrera, Medina, Coronado, Feijóo, Muñoz, Garrido, Troncoso, Figueroa, Toro, Reyes-Jara, Magne and Navarrete.https://www.frontiersin.org/articles/10.3389/fmicb.2018.01032/ful
Negative pressures in CaWO4 nanocrystals
Tetragonal scheelite-type CaWO4 nanocrystals recently prepared by a hydrothermal method show an enhancement of its structural symmetry with the decrease in nanocrystal size. The analysis of the volume dependence of the structural parameters in CaWO4 nanocrystals with the help of ab initio total-energy calculations shows that the enhancement of the symmetry in the scheelite-type nanocrystals is a consequence of the negative pressure exerted on the nanocrystals; i.e., the nanocrystals are under tension. Besides, the behavior of the structural parameters in CaWO4 nanocrystals for sizes below 10 nm suggests an onset of a scheelite-to-zircon phase transformation in good agreement with the predictions from our ab initio calculations. CaWO4 nanocrystals exhibit a reconstructive-type mechanism for the scheelite-to-zircon phase transition that seems to follow the tetragonal path that links both structures. This result is in contrast with the mechanism recently proposed for this transition in bulk ZrSiO4 where the transition goes through an intermediate monoclinic [email protected]
Design of a case management model for people with chronic disease (Heart Failure and COPD). Phase I: modeling and identification of the main components of the intervention through their actors: patients and professionals (DELTA-ICE-PRO Study
Background
Chronic diseases account for nearly 60% of deaths around the world. The extent of this silent epidemic has not met determined responses in governments, policies or professionals in order to transform old Health Care Systems, configured for acute diseases. There is a large list of research about alternative models for people with chronic conditions, many of them with an advanced practice nurse as a key provider, as case management. But some methodological concerns raise, above all, the design of the intervention (intensity, frequency, components, etc).
Methods/Design
Objectives: General: To develop the first and second phases (theorization and modeling) for designing a multifaceted case-management intervention in people with chronic conditions (COPD and heart failure) and their caregivers. Specific aims: 1) To identify key events in people living with chronic disease and their relation with the Health Care System, from their point of view. 2) To know the coping mechanisms developed by patients and their caregivers along the story with the disease. 3) To know the information processing and its utilization in their interactions with health care providers. 4) To detect potential unmet needs and the ways deployed by patients and their caregivers to resolve them. 5) To obtain a description from patients and caregivers, about their itineraries along the Health Care System, in terms of continuity, accessibility and comprehensiveness of care. 6) To build up a list of promising case-management interventions in patients with Heart Failure and COPD with this information in order to frame it into theoretical models for its reproducibility and conceptualization. 7) To undergo this list to expert judgment to assess its feasibility and pertinence in the Andalusian Health Care. Design: Qualitative research with two phases: For the first five objectives, a qualitative technique with biographic stories will be developed and, for the remaining objectives, an expert consensus through Delphi technique, on the possible interventions yielded from the first phase. The study will be developed in the provinces of Almería, Málaga and Granada in the Southern Spain, from patients included in the Andalusian Health Care Service database with the diagnosis of COPD or Heart Failure, with the collaboration of case manager nurses and general practitioners for the assessment of their suitability to inclusion criteria. Patients and caregivers will be interviewed in their homes or their Health Centers, with their family or their case manager nurse as mediator.
Discussion
First of a series of studies intended to design a case-management service for people with heart failure and COPD, in the Andalusian Health Care System, where case management has been implemented since 2002. Accordingly with the steps of a theoretical model for complex interventions, in this study, theorization and intervention modeling phases will be developed.This research was carried out with the support of one research grant, awarded by the Regional Health Ministry of Andalusia (Exp. 0222/2008
Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure
[EN] This paper reports an experimental and theoretical investigation on the electronic structure of bismuth selenide (Bi2Se3) up to 9 GPa. The optical gap of Bi2Se3 increases from 0.17 eV at ambient pressure to 0.45 eV at 8 GPa. The quenching of the Burstein-Moss effect in degenerate samples and the shift of the free-carrier plasma frequency to lower energies reveal a quick decrease of the bulk three-dimensional (3D) electron concentration under pressure. On increasing pressure the behavior of Hall electron concentration and mobility depends on the sample thickness, consistently with a gradual transition from mainly 3D transport at ambient pressure to mainly two-dimensional (2D) transport at high pressure. Two-carrier transport equations confirm the trapping of high-mobility 3D electrons, an effect that can be related to a shallow-to-deep transformation of donor levels, associated with a change in the ordering of the conduction band minima. The high apparent areal density and low electron mobility of 2D electrons are not compatible with their expected properties in a Dirac cone. Measured transport parameters at high pressure are most probably affected by the presence of holes, either in an accumulation surface layer or as minority carriers in the bulk. ©2012 American Physical SocietyThis work has been done under financial support from Spanish MICINN under Grants No. MAT2008-06873-C02-02, No. MAT2007-66129, No. MAT2010-21270-C04-03/04, No. CSD2007-00045, and Prometeo No. GV2011/035. The supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster.Segura, A.; Panchal, V.; Sánchez-Royo, JF.; Marín-Borrás, V.; Muñoz-Sanjosé, V.; Rodríguez-Hernández, P.; Muñoz, A.... (2012). Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure. Physical Review B. 85:195139-1-195139-9. https://doi.org/10.1103/PhysRevB.85.195139S195139-1195139-985Mishra, S. K., Satpathy, S., & Jepsen, O. (1997). Electronic structure and thermoelectric properties of bismuth telluride and bismuth selenide. Journal of Physics: Condensed Matter, 9(2), 461-470. doi:10.1088/0953-8984/9/2/014Hor, Y. S., Richardella, A., Roushan, P., Xia, Y., Checkelsky, J. G., Yazdani, A., … Cava, R. J. (2009). p-typeBi2Se3for topological insulator and low-temperature thermoelectric applications. Physical Review B, 79(19). doi:10.1103/physrevb.79.195208Zhang, H., Liu, C.-X., Qi, X.-L., Dai, X., Fang, Z., & Zhang, S.-C. (2009). Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface. Nature Physics, 5(6), 438-442. doi:10.1038/nphys1270Hasan, M. Z., & Kane, C. L. (2010). Colloquium: Topological insulators. Reviews of Modern Physics, 82(4), 3045-3067. doi:10.1103/revmodphys.82.3045Moore, J. E. (2010). The birth of topological insulators. Nature, 464(7286), 194-198. doi:10.1038/nature08916Xia, Y., Qian, D., Hsieh, D., Wray, L., Pal, A., Lin, H., … Hasan, M. Z. (2009). Observation of a large-gap topological-insulator class with a single Dirac cone on the surface. Nature Physics, 5(6), 398-402. doi:10.1038/nphys1274Chen, Y. L., Analytis, J. G., Chu, J.-H., Liu, Z. K., Mo, S.-K., Qi, X. L., … Shen, Z.-X. (2009). Experimental Realization of a Three-Dimensional Topological Insulator, Bi2Te3. Science, 325(5937), 178-181. doi:10.1126/science.1173034Hsieh, D., Xia, Y., Qian, D., Wray, L., Dil, J. H., Meier, F., … Hasan, M. Z. (2009). A tunable topological insulator in the spin helical Dirac transport regime. Nature, 460(7259), 1101-1105. doi:10.1038/nature08234Alpichshev, Z., Analytis, J. G., Chu, J.-H., Fisher, I. R., Chen, Y. L., Shen, Z. X., … Kapitulnik, A. (2010). STM Imaging of Electronic Waves on the Surface ofBi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects. Physical Review Letters, 104(1). doi:10.1103/physrevlett.104.016401Roushan, P., Seo, J., Parker, C. V., Hor, Y. S., Hsieh, D., Qian, D., … Yazdani, A. (2009). Topological surface states protected from backscattering by chiral spin texture. Nature, 460(7259), 1106-1109. doi:10.1038/nature08308Butch, N. P., Kirshenbaum, K., Syers, P., Sushkov, A. B., Jenkins, G. S., Drew, H. D., & Paglione, J. (2010). Strong surface scattering in ultrahigh-mobilityBi2Se3topological insulator crystals. Physical Review B, 81(24). doi:10.1103/physrevb.81.241301Wang, Z., Lin, T., Wei, P., Liu, X., Dumas, R., Liu, K., & Shi, J. (2010). Tuning carrier type and density in Bi2Se3 by Ca-doping. Applied Physics Letters, 97(4), 042112. doi:10.1063/1.3473778Ren, Z., Taskin, A. A., Sasaki, S., Segawa, K., & Ando, Y. (2010). Large bulk resistivity and surface quantum oscillations in the topological insulatorBi2Te2Se. Physical Review B, 82(24). doi:10.1103/physrevb.82.241306Kulbachinskii, V. A., Miura, N., Nakagawa, H., Arimoto, H., Ikaida, T., Lostak, P., & Drasar, C. (1999). Conduction-band structure ofBi2−xSbxSe3mixed crystals by Shubnikov–de Haas and cyclotron resonance measurements in high magnetic fields. Physical Review B, 59(24), 15733-15739. doi:10.1103/physrevb.59.15733Analytis, J. G., McDonald, R. D., Riggs, S. C., Chu, J.-H., Boebinger, G. S., & Fisher, I. R. (2010). Two-dimensional surface state in the quantum limit of a topological insulator. Nature Physics, 6(12), 960-964. doi:10.1038/nphys1861Cho, S., Butch, N. P., Paglione, J., & Fuhrer, M. S. (2011). Insulating Behavior in Ultrathin Bismuth Selenide Field Effect Transistors. Nano Letters, 11(5), 1925-1927. doi:10.1021/nl200017fZhang, Y., He, K., Chang, C.-Z., Song, C.-L., Wang, L.-L., Chen, X., … Xue, Q.-K. (2010). Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit. Nature Physics, 6(8), 584-588. doi:10.1038/nphys1689Kong, D., Cha, J. J., Lai, K., Peng, H., Analytis, J. G., Meister, S., … Cui, Y. (2011). Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3. ACS Nano, 5(6), 4698-4703. doi:10.1021/nn200556hBenia, H. M., Lin, C., Kern, K., & Ast, C. R. (2011). Reactive Chemical Doping of theBi2Se3Topological Insulator. Physical Review Letters, 107(17). doi:10.1103/physrevlett.107.177602King, P. D. C., Hatch, R. C., Bianchi, M., Ovsyannikov, R., Lupulescu, C., Landolt, G., … Hofmann, P. (2011). Large Tunable Rashba Spin Splitting of a Two-Dimensional Electron Gas inBi2Se3. Physical Review Letters, 107(9). doi:10.1103/physrevlett.107.096802Hamlin, J. J., Jeffries, J. R., Butch, N. P., Syers, P., Zocco, D. A., Weir, S. T., … Maple, M. B. (2011). High pressure transport properties of the topological insulator Bi2Se3. Journal of Physics: Condensed Matter, 24(3), 035602. doi:10.1088/0953-8984/24/3/035602Köhler, H., & Hartmann, J. (1974). Burstein Shift of the Absorption Edge of nBi2Se3. physica status solidi (b), 63(1), 171-176. doi:10.1002/pssb.2220630116Panchal, V., Segura, A., & Pellicer-Porres, J. (2011). Low-cost set-up for Fourier-transform infrared spectroscopy in diamond anvil cell from 4000 to 400 cm−1. High Pressure Research, 31(3), 445-453. doi:10.1080/08957959.2011.594049Chervin, J. C., Canny, B., Besson, J. M., & Pruzan, P. (1995). A diamond anvil cell for IR microspectroscopy. Review of Scientific Instruments, 66(3), 2595-2598. doi:10.1063/1.1145594Piermarini, G. J., Block, S., Barnett, J. D., & Forman, R. A. (1975). Calibration of the pressure dependence of theR1ruby fluorescence line to 195 kbar. Journal of Applied Physics, 46(6), 2774-2780. doi:10.1063/1.321957Errandonea, D., Segura, A., Martínez-García, D., & Muñoz-San Jose, V. (2009). Hall-effect and resistivity measurements in CdTe and ZnTe at high pressure: Electronic structure of impurities in the zinc-blende phase and the semimetallic or metallic character of the high-pressure phases. Physical Review B, 79(12). doi:10.1103/physrevb.79.125203Errandonea, D., Martínez-García, D., Segura, A., Ruiz-Fuertes, J., Lacomba-Perales, R., Fages, V., … Mũnoz-San José, V. (2006). High-pressure electrical transport measurements on p-type GaSe and InSe. High Pressure Research, 26(4), 513-516. doi:10.1080/08957950601101787Hohenberg, P., & Kohn, W. (1964). Inhomogeneous Electron Gas. Physical Review, 136(3B), B864-B871. doi:10.1103/physrev.136.b864Kresse, G., & Hafner, J. (1993). Ab initiomolecular dynamics for liquid metals. Physical Review B, 47(1), 558-561. doi:10.1103/physrevb.47.558Kresse, G., & Hafner, J. (1994). Ab initiomolecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium. Physical Review B, 49(20), 14251-14269. doi:10.1103/physrevb.49.14251Kresse, G., & Furthmüller, J. (1996). Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Computational Materials Science, 6(1), 15-50. doi:10.1016/0927-0256(96)00008-0Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Perdew, J. P., Ruzsinszky, A., Csonka, G. I., Vydrov, O. A., Scuseria, G. E., Constantin, L. A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Mujica, A., Rubio, A., Muñoz, A., & Needs, R. J. (2003). High-pressure phases of group-IV, III–V, and II–VI compounds. Reviews of Modern Physics, 75(3), 863-912. doi:10.1103/revmodphys.75.863Köhler, H., & Becker, C. R. (1974). Optically Active Lattice Vibrations in Bi2Se3. physica status solidi (b), 61(2), 533-537. doi:10.1002/pssb.2220610218Vilaplana, R., Santamaría-Pérez, D., Gomis, O., Manjón, F. J., González, J., Segura, A., … Kucek, V. (2011). Structural and vibrational study of Bi2Se3under high pressure. Physical Review B, 84(18). doi:10.1103/physrevb.84.184110LaForge, A. D., Frenzel, A., Pursley, B. C., Lin, T., Liu, X., Shi, J., & Basov, D. N. (2010). Optical characterization ofBi2Se3in a magnetic field: Infrared evidence for magnetoelectric coupling in a topological insulator material. Physical Review B, 81(12). doi:10.1103/physrevb.81.125120Penn, D. R. (1962). Wave-Number-Dependent Dielectric Function of Semiconductors. Physical Review, 128(5), 2093-2097. doi:10.1103/physrev.128.2093PHILLIPS, J. C. (1970). Ionicity of the Chemical Bond in Crystals. Reviews of Modern Physics, 42(3), 317-356. doi:10.1103/revmodphys.42.317Van Vechten, J. A. (1969). Quantum Dielectric Theory of Electronegativity in Covalent Systems. I. Electronic Dielectric Constant. Physical Review, 182(3), 891-905. doi:10.1103/physrev.182.891Van Vechten, J. A. (1969). Quantum Dielectric Theory of Electronegativity in Covalent Systems. II. Ionization Potentials and Interband Transition Energies. Physical Review, 187(3), 1007-1020. doi:10.1103/physrev.187.1007Larson, P., Greanya, V. A., Tonjes, W. C., Liu, R., Mahanti, S. D., & Olson, C. G. (2002). Electronic structure ofBi2X3(X=S,Se,T)compounds: Comparison of theoretical calculations with photoemission studies. Physical Review B, 65(8). doi:10.1103/physrevb.65.085108Chang, J., Jadaun, P., Register, L. F., Banerjee, S. K., & Sahu, B. (2011). Dielectric capping effects on binary and ternary topological insulator surface states. Physical Review B, 84(15). doi:10.1103/physrevb.84.155105Suski, T., Piotrzkowski, R., Wiśniewski, P., Litwin-Staszewska, E., & Dmowski, L. (1989). High pressure andDXcenters in heavily doped bulk GaAs. Physical Review B, 40(6), 4012-4021. doi:10.1103/physrevb.40.4012Errandonea, D., Segura, A., Sánchez-Royo, J. F., Mun-|Atoz, V., Grima, P., Chevy, A., & Ulrich, C. (1997). Investigation of conduction-band structure, electron-scattering mechanisms, and phase transitions in indium selenide by means of transport measurements under pressure. Physical Review B, 55(24), 16217-16225. doi:10.1103/physrevb.55.16217Analytis, J. G., Chu, J.-H., Chen, Y., Corredor, F., McDonald, R. D., Shen, Z. X., & Fisher, I. R. (2010). Bulk Fermi surface coexistence with Dirac surface state inBi2Se3: A comparison of photoemission and Shubnikov–de Haas measurements. Physical Review B, 81(20). doi:10.1103/physrevb.81.205407Köhler, H., & Fabbicius, A. (1975). Galvanomagnetic Properties of Bi2Se3with Free Carrier Densities below 5 × 1017 cm−3. physica status solidi (b), 71(2), 487-496. doi:10.1002/pssb.222071020
Presencia de la familia Helicopsychidae (Trichoptera) en la mitad meridional de España peninsular
La familia Helicopsychidae Ulmer, 1906, cuesta con unas 250 especies distribuidas por todo el mundo y pertenecientes en casi su totalidad al género Helicopsyche von Siebold, 1856, salvo una especie endémica de Nueva Zelanda: Rakiura vernale McFarlane, 1973
Fossil Groups Origins III. Characterization of the sample and observational properties of fossil systems
(Abridged) Fossil systems are group- or cluster-sized objects whose
luminosity is dominated by a very massive central galaxy. In the current cold
dark matter scenario, these objects formed hierarchically at an early epoch of
the Universe and then slowly evolved until present day. That is the reason why
they are called {\it fossils}. We started an extensive observational program to
characterize a sample of 34 fossil group candidates spanning a broad range of
physical properties. Deep band images were taken for each candidate and
optical spectroscopic observations were obtained for 1200 galaxies. This
new dataset was completed with SDSS DR7 archival data to obtain robust cluster
membership and global properties of each fossil group candidate. For each
system, we recomputed the magnitude gaps between the two brightest galaxies
() and the first and fourth ranked galaxies ()
within 0.5 . We consider fossil systems those with mag or mag within the errors. We find
that 15 candidates turned out to be fossil systems. Their observational
properties agree with those of non-fossil systems. Both follow the same
correlations, but fossils are always extreme cases. In particular, they host
the brightest central galaxies and the fraction of total galaxy light enclosed
in the central galaxy is larger in fossil than in non-fossil systems. Finally,
we confirm the existence of genuine fossil clusters. Combining our results with
others in the literature, we favor the merging scenario in which fossil systems
formed due to mergers of galaxies. The large magnitude gap is a
consequence of the extreme merger ratio within fossil systems and therefore it
is an evolutionary effect. Moreover, we suggest that at least one candidate in
our sample could represent a transitional fossil stage.Comment: 14 pages, 11 figures, accepted for publication in A&
Physical capacity in youth football players of a profesional club
Las características físicas del fútbol son muy diversas, aunque se reconocen como muy importantes la capacidad de realizar esfuerzos de alta intensidad y la de retrasar la fatiga en la mayor medida posible en esfuerzos intermitentes. Son diversos los trabajos que analizan dichas características en el fútbol profesional, aunque son menores los que analizan las categorías de
formación. En el presente estudio se analiza la evolución por categorías de pruebas de salto, velocidad, agilidad y resistencia aeróbica específica, en jugadores de fútbol jóvenes de la cantera de un club profesional de la liga española. Se produjo un incremento de las marcas con la edad, aunque no se observaron diferencias significativas en grupos de edad cercanos, produciéndose una meseta en el rendimiento en la fuerza explosiva y velocidad de aceleración a partir de los 17 años y en la velocidad de desplazamiento y agilidad a los 15 añosPhysical characteristics of football are very different, but are recognized as very important the ability to perform high-intensity efforts and to delay fatigue as much as possible in intermittent efforts. There are several studies that analyze these characteristics in professional football but are less those who analyze the categories of training. In the present study analyzes the evolution of categories of jumping, speed, agility and specific endurance in young soccer players from a professional club of the Spanish league. There was an increase of the marks with age, although no significant differences in age groups encircle. Producing a plateau in performance in explosive strength and acceleration speed from 17 years and in speed and agility at age of 1
- …