3,155 research outputs found
On fractional derivatives and primitives of periodic functions
In this paper we prove that the fractional derivative or the fractional
primitive of a -periodic function cannot be a -periodic function,
for any period , with the exception of the zero function.Comment: 12 page
Numerical analysis of run-up oscillations under dissipative conditions
This paper presents laboratory and numerical simulations of run-up induced by irregular waves breaking on a gentle-sloping planar beach. The experimental data are well reproduced by a numerical model based on the nonlinear shallow water equations. By extending the incoming wave conditions considered in the laboratory experiments, the model is applied to study the run-up variability under highly energetic incoming conditions. The numerical results support the idea that, for cases characterized by the same incident peak frequency, infragravity run-up increases almost linearly with the offshore significant wave height. Moreover, the most energetic conditions lead to an upper limit of the swash similarity parameter of about 1.8. © 2014 Elsevier B.V
Tuberculosis de la sínfisis del pubis : a propósito de un caso clínico.
Se presenta un caso muy infrecuente de tuberculosis osteoarticular de
localización en la sínfisis del pubis. Destaca la dificultad de su diagnóstico por lo inespecífico
de su clínica, por el desconocimiento de enfermedad pulmonar o lesión primaria tuberculosa,
y la dificultad para aislar al propio bacilo tuberculoso. Establecemos los diagnósticos diferenciales
más importantes con los que se puede confundir esta patología antes de llegar a un
diagnóstico certero y se valoran los síntomas, signos y hallazgos radiológicos más frecuentes
que contribuyen al diagnóstico, así como el tratamiento específico empleado.We presen t a cas e o f an infrecuen t locatio n o f osteoarticula r tuber -
culosis a t th e pubi x xymphisis. This patolog y is difficult t o determine , specil y if ther e
doe s no t exit a pulmonar y o r primar y TBC lesion . Also , th e difficult t o obtai n a
positiv e microbiolog y cultur e increase s th e dela y i n diagnosis. We establis h all
posibl e differencia l diagnoses. Whic h ca n lea d t o confusio n i n this typ e o f pathology .
A carefu l evaluatio n o f most commo n simptoms, sign s an d radiologien e fínding s ar e
described , a s wel l as, th e specifi c treatmen t employe d i n this particuler e case
Corrientes de retorno en medios reflejantes y disipativos
[ES] Se ha analizado teórica y experimentalmente los movimientos medios inducidos por la propagación de un tren de ondas de pequeña amplitud sobre un medio disipativo y reflejante cualquiera. A partir de la solución de teoría lineal, y sin considerar los efectos de rotura del oleaje, se ha obtenido la evolución de las magnitudes promediadas (nivel medio, flujo de masa, etc.) en el medio, teniendo en cuenta la transformación del oleaje. Las modificaciones del tren de ondas a su paso por el elemento disipativo-reflejante producen un desequilibrio espacial de las magnitudes medias, que se traduce en una sobreelevación y modulación del nivel medio y una disminución del flujo de masa. Esta variación espacial del caudal medio induce un sistema circulatorio de corrientes con estructura vertical. Dicho flujo ha sido modelado de forma analítica a través de la resolución del problema de contorno bidimensional de la función de corriente media. La teoría se ha aplicado a medios emergidos y sumergidos, tanto artificiales (dique permeable) como naturales (campo de algas), obteniéndose en todos ellos un buen ajuste de los resultados experimentales.Méndez, FJ.; Losada, IJ.; Losada, MÁ. (1998). Corrientes de retorno en medios reflejantes y disipativos. Ingeniería del Agua. 5(1):11-22. https://doi.org/10.4995/ia.1998.2740SWORD112251Dalrymple, R.A., M.A. Losada y P. Martin. (1991) Reflection and transmission from porous structures under oblique wave attack. Journal of Fluid Mechanics. Vol. 224, pp. 625-644.Gent, M.R.A. van. (1995) Wave interaction with permeable coastal structures. Ph.D. Thesis. Delft University of Technology. 173 pp.Kobayashi, N., A.W. Raichle y T. Asano. (1991) Prediction of wave attenuation by vegetation and seaweed. Research Report No. CACR-91-07, Center for Applied Coastal Research, University of Delaware, 55 pp.Losada, I.J., R.A. Dalrymple y M.A. Losada. (1997a) Wave-induced mean flows in breakwaters. Remitido al Coastal Engineering. Elsevier.Losada, I.J., M. Patterson y M.A. Losada. (1997b) Harmonic generation past a submerged porous step. Coastal Engineering. Elsevier. Vol. 31, pp. 281-304.Losada, I.J., R. Silva y M.A. Losada. (1996) 3-D non-breaking regular wave interaction with submerged breakwaters. Coastal Engineering. Elsevier. Vol. 28, pp. 229-248.Losada, I.J. (1991) Estudio de la propagación de un tren lineal de ondas por un medio discontinuo. Tesis Doctoral. Universidad de Cantabria. 183 pp.Méndez, F.J. 1997. Flujos medios inducidos por las ondas de gravedad en medios reflejantes y disipativos naturales o artificiales. Tesis Doctoral. Universidad de Cantabria. 343 pp.Sollitt, C.K. y R.H. Cross. (1972) Wave transmission through permeable breakwaters. Proc. 13th Coastal Engineering Conference. ASCE. New York, N.Y. pp. 1827-1846.Vidal, C., M.A. Losada y F.L. Martín. (1997) Diseño y aplicaciones de un canal experimental de oleaje-corriente. IV Jornadas Españolas de Ingeniería de Costas y Puertos. En prensa
Osteoma osteoide de rodilla Dos casos de difícil diagnóstico
Presentamos dos casos de osteoma osteoide yuxtacortical de localización infrecuente
en la rodilla y de difícil diagnóstico. La gammagrafía reveló la localización de la lesión
y la tomografía axial computerizada (TAC) en cortes finos indicó el lugar exacto, facilitando
así la planificación del abordaje quirúrgico de la zona. La resonancia magnética no aportó datos
de interés. Tras la cirugía, la sintomatología previa remitió completamente en ambos casos.We present two cases of osteoid osteoma affecting the knee, a very infrequent
localization and therefore of difficult diagnosis. The scintigraphy was found to be of valuable
assitance in revealing the presence of this lesion at the knee and CT-scan was likewise useful
for its precision in localizing the tumor as a basis for deciding upon a viable surgical approach.
MRI did not contribute some date. After surgical resection of the tumor, a complete relief of
the symptoms was experienced in both patients
Floating Bare Tether as Upper Atmosphere Probe
Use of a (bare) conductive tape electrically floating in LEO as an effective e-beam source that produces artificial auroras, and is free of problems that have marred standard beams, is considered. Ambient ions impacting the tape with KeV energies over most of its length liberate secondary electrons, which race down the magnetic field and excite neutrals in the E-layer, resulting in auroral emissions. The tether would operate at night-time with both a power supply and a plasma contactor off; power and contactor would be on at daytime for reboost. The optimal tape thickness yielding a minimum mass for an autonomous system is determined; the alternative use of an electric thruster for day reboost, depending on mission duration, is discussed. Measurements of emission brightness from the spacecraft could allow
determination of the (neutral) density vertical profile in the critical E-layer; the flux and energy in the beam, varying along the tether, allow imaging line-of-sight integrated emissions that mix effects with altitude-dependent neutral density and lead to a brightness
peak in the beam footprint at the E-layer. Difficulties in tomographic inversion, to determine the density profile, result from beam broadening, due to elastic collisions, which flattens the peak, and to the highly nonlinear functional dependency of line-of-sight brightness. Some
dynamical issues are discussed
Factores pronósticos en el tratamiento del condrosarcoma
Los autores 30 condrosarcomas tratados en su Departamento. Estudiando
la distribución por sexos, edad, localización, supervivencia y los factores pronósticos respecto
a la relación entre el tipo histológico, localización, tratamiento, origen y tiempo de
evolución.
Concluyen que son factores de mal pronóstico el grado histológico III, localización central,
especialmente en ilíaco, origen primario de la enfermedad y un tiempo mayor de 6
meses entre el diagnóstico y el tratamientoThe authors are reviewed 30 chondrosarcomas seen at their department
of orthopaedics surgery. They studied the age distribution, sex, localization,
survival and the prognostic factors between histopathology, localization, origin,
treatment and evolution times.
It is concluyed that the grade III, central localization (specially in pelvis),
primary origin and evolution times more than six months between diagnosis and
treatment are bad prognostic factors in chondrosarcoma of bone
Reductie stofemissie bij vleeskuikens door aanbrengen oliefilm = Reduction of dust emission from broilers by application of an oil film
The effect of application of an oil film on bedding on dust reduction in a broiler house was studied. The system proved to be effectiv
A Review of ENSO Influence on the North Atlantic. A Non-Stationary Signal
ReviewThe atmospheric seasonal cycle of the North Atlantic region is dominated by meridional movements of the circulation systems: from the tropics, where the West African Monsoon and extreme tropical weather events take place, to the extratropics, where the circulation is dominated by seasonal changes in the jetstream and extratropical cyclones. Climate variability over the North Atlantic is controlled by various mechanisms. Atmospheric internal variability plays a crucial role in the mid-latitudes. However, El Niño-Southern Oscillation (ENSO) is still the main source of predictability in this region situated far away from the Pacific. Although the ENSO influence over tropical and extra-tropical areas is related to different physical mechanisms, in both regions this teleconnection seems to be non-stationary in time and modulated by multidecadal changes of the mean flow. Nowadays, long observational records (greater than 100 years) and modeling projects (e.g., CMIP) permit detecting non-stationarities in the influence of ENSO over the Atlantic basin, and further analyzing its potential mechanisms. The present article reviews the ENSO influence over the Atlantic region, paying special attention to the stability of this teleconnection over time and the possible modulators. Evidence is given that the ENSO–Atlantic teleconnection is weak over the North Atlantic. In this regard, the multidecadal ocean variability seems to modulate the presence of teleconnections, which can lead to important impacts of ENSO and to open windows of opportunity for seasonal predictability.We thank the Climatic Research Unit (CRU), the National Centers for Environmental
Prediction (NCEP), the Met Office Hadley Centre and the US National Hurricane Center (NHC) for
the Land Precipitation, reanalysis, SST and HURDAT2 datasets, respectively. Belen Rodríguez-Fonseca,
Roberto Suárez-Moreno, Jorge López-Parages, Iñigo Gómara, Elsa Mohino, Teresa Losada and Antonio Castaño-Tierno
are supported by the research projects PREFACE (EUFP7/2007-2013 Grant Agreement 603521) and MULCLIVAR
(CGL2012-38923-C02-01-Spanish Ministry of Economy and Competitiveness). Blanca Ayarzagüena is supported
by the Natural Environment Research Council (grant number NE/M006123/1). Julián Villamayor is granted
through a scholarship from the MICINN—Spanish government (BES-2013-063821
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