Lesiones de partes blandas por fricción

La lesión por fricción es una lesión de partes blandas que dentro de su rareza se encuentra más frecuentemente en el contexto de los accidentes de tráfico. Las fuerzas tangenciales se transmiten des del asfalto, ruedas de los vehículos a tejido celular subcutáneo conduciendo a un gran deslizamiento del mismo sobre la fascia muscular. El movimiento anormal provoca la rotura de vasos linfáticos y vasculares conduciendo una colección serohemática. Las situaciones más frecuentemente encontrada son aquellas las cuales contienen masas musculares grandes. Normalmente es una lesión de larga evolución e infradiagnosticada en sus estados iniciales. Se presenta como una tumoración fría, dolorosa e incapacitante con piel adyacente intacta o con petequías. Se diagnostica con exploración física y pruebas complementarias, como ecografía. El tratamiento teniendo en cuenta diferentes ítems puede consistir en medida conservadoras o llegar a procedimientos quirúrgicos. En la literatura no se pone de manifiesto variabilidad en los resultados de diferentes procedimientos terapéuticos.Injury by friction is an injury of soft parts that although not frequent it is not unusual in the context of the traffic accidents. The tangential forces are transmitted from the asphalt and the wheels of the vehicles to the cellular subcutaneous fabric, producing a big sliding on the muscular fascia. The abnormal movement breaks the lymphatic and vascular glasses leading to a serohematic collection. The most usual situations are that ones which contain muscular big masses. Normally it is an injury of long evolution and infradiagnosticated in its initial conditions. The skin appears as a cold, painful tumor and disabling with adjacent skin intact or with petechiae. It is diagnosed by physical exploration and with additional tests, like ultrasound scan. The treatment, considering different items, can consist on conservative measures or even surgical procedures. In the literature variability is not revealed in the results of different therapeutic procedures.Peer ReviewedAward-winnin

MASSIV: Mass Assembly Survey with SINFONI in VVDS. V. The major merger rate of star-forming galaxies at 0.9 < z < 1.8 from IFS-based close pairs

We aim to measure the major merger rate of star-forming galaxies at 0.9 < z <1.8, using close pairs identified from integral field spectroscopy (IFS). We use the velocity field maps obtained with SINFONI/VLT on the MASSIV sample, selected from the star-forming population in the VVDS. We identify physical pairs of galaxies from the measurement of the relative velocity and the projected separation (r_p) of the galaxies in the pair. Using the well constrained selection function of the MASSIV sample we derive the gas-rich major merger fraction (luminosity ratio mu = L_2/L_1 >= 1/4), and, using merger time scales from cosmological simulations, the gas-rich major merger rate at a mean redshift up to z = 1.54. We find a high gas-rich major merger fraction of 20.8+15.2-6.8 %, 20.1+8.0-5.1 % and 22.0+13.7-7.3 % for close pairs with r_p <= 20h^-1 kpc in redshift ranges z = [0.94, 1.06], [1.2, 1.5) and [1.5, 1.8), respectively. This translates into a gas-rich major merger rate of 0.116+0.084-0.038 Gyr^-1, 0.147+0.058-0.037 Gyr^-1 and 0.127+0.079-0.042 Gyr^-1 at z = 1.03, 1.32 and 1.54, respectively. Combining our results with previous studies at z < 1, the gas-rich major merger rate evolves as (1+z)^n, with n = 3.95 +- 0.12, up to z = 1.5. From these results we infer that ~35% of the star-forming galaxies with stellar masses M = 10^10 - 10^10.5 M_Sun have undergone a major merger since z ~ 1.5. We develop a simple model which shows that, assuming that all gas-rich major mergers lead to early-type galaxies, the combined effect of gas-rich and dry mergers is able to explain most of the evolution in the number density of massive early-type galaxies since z ~ 1.5, with our measured gas-rich merger rate accounting for about two-thirds of this evolution.Comment: Published in Astronomy and Astrophysics, 24 pages, 30 figures, 2 tables. Appendix with the residual images from GALFIT added. Minor changes with respect to the initial versio

The dominant role of mergers in the size evolution of massive early-type galaxies since z ∼ 1

Aims. The role of galaxy mergers in massive galaxy evolution, and in particular to mass assembly and size growth, remains an open question. In this paper we measure the merger fraction and rate, both minor and major, of massive early-type galaxies (M_⋆ ≥ 10^(11) M_⊙) in the COSMOS field, and study their role in mass and size evolution. Methods. We used the 30-band photometric catalogue in COSMOS, complemented with the spectroscopy of the zCOSMOS survey, to define close pairs with a separation on the sky plane 10 h^(-1) kpc ≤ r_p ≤ 30 h^(-1) kpc and a relative velocity Δv ≤ 500 km s^(-1) in redshift space. We measured both major (stellar mass ratio μ ≡ M_(⋆,2)/M_(⋆,1) ≥ 1/4) and minor (1/10 ≤ μ < 1/4) merger fractions of massive galaxies, and studied their dependence on redshift and on morphology (early types vs. late types). Results. The merger fraction and rate of massive galaxies evolves as a power-law (1 + z)^n, with major mergers increasing with redshift, n_(MM) = 1.4, and minor mergers showing little evolution, n_(mm) ~ 0. When split by their morphology, the minor merger fraction for early-type galaxies (ETGs) is higher by a factor of three than that for late-type galaxies (LTGs), and both are nearly constant with redshift. The fraction of major mergers for massive LTGs evolves faster (n_(MM)^(LT) ~ 4 ) than for ETGs (n_(MM)^(ET)= 1.8). Conclusions. Our results show that massive ETGs have undergone 0.89 mergers (0.43 major and 0.46 minor) since z ~ 1, leading to a mass growth of ~30%. We find that μ ≥ 1/10 mergers can explain ~55% of the observed size evolution of these galaxies since z ~ 1. Another ~20% is due to the progenitor bias (younger galaxies are more extended) and we estimate that very minor mergers (μ < 1/10) could contribute with an extra ~20%. The remaining ~5% should come from other processes (e.g., adiabatic expansion or observational effects). This picture also reproduces the mass growth and the velocity dispersion evolution of these galaxies. We conclude from these results, and after exploring all the possible uncertainties in our picture, that merging is the main contributor to the size evolution of massive ETGs at z ≲ 1, accounting for ~50−75% of that evolution in the last 8 Gyr. Nearly half of the evolution due to mergers is related to minor (μ < 1/4) events

Demonstration of Time Delay Interferometry and Spacecraft Ranging in a Space-based Gravitational Wave Detector using the UF-LISA Interferometry Simulator

Space-based gravitational-wave observatories such as the Laser Interferometer Space Antenna (LISA) use time-shifted and time-scaled linear combinations of differential laser-phase beat signals to cancel the otherwise overwhelming laser frequency noise. Nanosecond timing precision is needed to accurately form these Time-Delay Interferometry (TDI) combinations which defines a ~1 meter requirement on the inter-spacecraft ranging capability. The University of Florida Hardware-in-the-loop LISA Interferometry Simulator (UFLIS) has been used to test Time-Delay Interferometry in a configuration which incorporates variable delays, realistic Doppler shifts, and simulated gravitational-wave signals. The TDI 2.0 combinations are exploited to determine the time-changing delays with nanosecond accuracy using a TDI-ranging reference tone. These variable delays are used in forming the TDI combinations to achieve the LISA interferometry sensitivity resulting from 10 orders of magnitude laser frequency noise cancellation.Comment: Accepted: Physical Review D, 12 pages, 12 figure

Spectro-photometric close pairs in GOODS-S: major and minor companions of intermediate-mass galaxies

(Abriged) Our goal here is to provide merger frequencies that encompass both major and minor mergers, derived from close pair statistics. We use B-band luminosity- and mass-limited samples from an Spitzer/IRAC-selected catalogue of GOODS-S. We present a new methodology for computing the number of close companions, Nc, when spectroscopic redshift information is partial. We select as close companions those galaxies separated by 6h^-1 kpc < rp < 21h^-1 kpc in the sky plane and with a difference Delta_v <= 500 km s^-1 in redshift space. We provide Nc for four different B-band-selected samples. Nc increases with luminosity, and its evolution with redshift is faster in more luminous samples. We provide Nc of M_star >= 10^10 M_Sun galaxies, finding that the number including minor companions (mass ratio >= 1/10) is roughly two times the number of major companions alone (mass ratio >= 1/3) in the range 0.2 <= z < 1.1. We compare the major merger rate derived by close pairs with the one computed by morphological criteria, finding that both approaches provide similar merger rates for field galaxies when the progenitor bias is taken into account. Finally, we estimate that the total (major+minor) merger rate is ~1.7 times the major merger rate. Only 30% to 50% of the M_star >= 10^10 M_Sun early-type (E/S0/Sa) galaxies that appear z=1 and z=0 may have undergone a major or a minor merger. Half of the red sequence growth since z=1 is therefore unrelated to mergers.Comment: Accepted in A&A. 14 pages, 6 figures, 8 tables. We have tested the method with a local, volume-limited spectroscopic sample