First passage and arrival time densities for L\'evy flights and the failure of the method of images

We discuss the first passage time problem in the semi-infinite interval, for homogeneous stochastic Markov processes with L{\'e}vy stable jump length distributions $\lambda(x)\sim\ell^{\alpha}/|x|^{1+\alpha}$ ($|x|\gg\ell$), namely, L{\'e}vy flights (LFs). In particular, we demonstrate that the method of images leads to a result, which violates a theorem due to Sparre Andersen, according to which an arbitrary continuous and symmetric jump length distribution produces a first passage time density (FPTD) governed by the universal long-time decay $\sim t^{-3/2}$. Conversely, we show that for LFs the direct definition known from Gaussian processes in fact defines the probability density of first arrival, which for LFs differs from the FPTD. Our findings are corroborated by numerical results.Comment: 8 pages, 3 figures, iopart.cls style, accepted to J. Phys. A (Lett

Evidence of Strong Quantum Turbulence in Bose Einstein Condensates

By combining experiments and numerical simulations which model precisely the dynamics of shaken atomic Bose-Einstein condensates, we reveal the surprising nature of quantum turbulence in these systems. Unlike the tangles of vortex lines described in the superfluid helium literature, we find that a turbulent atomic condensate contains a mixture of strong fragmented density fluctuations and small random vortex loops which are not homogeneously distributed. This unusual form of quantum turbulence, with its own properties and scaling behaviour, is significantly different from the turbulence which is observed in either classical or other quantum systems, thus posing a new challenge in turbulence research.Comment: 8 pages, 5 figure

Design and operation of a cryogenic charge-integrating preamplifier for the MuSun experiment

The central detector in the MuSun experiment is a pad-plane time projection ionization chamber that operates without gas amplification in deuterium at 31 K; it is used to measure the rate of the muon capture process $\mu^- + d \rightarrow n + n + \nu_\mu$. A new charge-sensitive preamplifier, operated at 140 K, has been developed for this detector. It achieved a resolution of 4.5 keV(D$_2$) or 120 $e^-$ RMS with zero detector capacitance at 1.1 $\mu$s integration time in laboratory tests. In the experimental environment, the electronic resolution is 10 keV(D$_2$) or 250 $e^-$ RMS at a 0.5 $\mu$s integration time. The excellent energy resolution of this amplifier has enabled discrimination between signals from muon-catalyzed fusion and muon capture on chemical impurities, which will precisely determine systematic corrections due to these processes. It is also expected to improve the muon tracking and determination of the stopping location.Comment: 18 pages + title page, 13 figures, to be submitted to JINST; minor corrections, added one reference, updated author lis

The second flight of the SUNRISE balloon-borne solar observatory: overview of instrument updates, the flight, the data and first results

The SUNRISE balloon-borne solar observatory, consisting of a 1~m aperture telescope that provided a stabilized image to a UV filter imager and an imaging vector polarimeter, carried out its second science flight in June 2013. It provided observations of parts of active regions at high spatial resolution, including the first high-resolution images in the Mg~{\sc ii}~k line. The obtained data are of very high quality, with the best UV images reaching the diffraction limit of the telescope at 3000~\AA\ after Multi-Frame Blind Deconvolution reconstruction accounting for phase-diversity information. Here a brief update is given of the instruments and the data reduction techniques, which includes an inversion of the polarimetric data. Mainly those aspects that evolved compared with the first flight are described. A tabular overview of the observations is given. In addition, an example time series of a part of the emerging active region NOAA AR~11768 observed relatively close to disk centre is described and discussed in some detail. The observations cover the pores in the trailing polarity of the active region, as well as the polarity inversion line where flux emergence was ongoing and a small flare-like brightening occurred in the course of the time series. The pores are found to contain magnetic field strengths ranging up to 2500~G and, while large pores are clearly darker and cooler than the quiet Sun in all layers of the photosphere, the temperature and brightness of small pores approach or even exceed those of the quiet Sun in the upper photosphere.Comment: Accepted for publication in The Astrophysical Journa

Modelling and Interpreting The Effects of Spatial Resolution on Solar Magnetic Field Maps

Different methods for simulating the effects of spatial resolution on magnetic field maps are compared, including those commonly used for inter-instrument comparisons. The investigation first uses synthetic data, and the results are confirmed with {\it Hinode}/SpectroPolarimeter data. Four methods are examined, one which manipulates the Stokes spectra to simulate spatial-resolution degradation, and three "post-facto" methods where the magnetic field maps are manipulated directly. Throughout, statistical comparisons of the degraded maps with the originals serve to quantify the outcomes. Overall, we find that areas with inferred magnetic fill fractions close to unity may be insensitive to optical spatial resolution; areas of sub-unity fill fractions are very sensitive. Trends with worsening spatial resolution can include increased average field strength, lower total flux, and a field vector oriented closer to the line of sight. Further-derived quantities such as vertical current density show variations even in areas of high average magnetic fill-fraction. In short, unresolved maps fail to represent the distribution of the underlying unresolved fields, and the "post-facto" methods generally do not reproduce the effects of a smaller telescope aperture. It is argued that selecting a method in order to reconcile disparate spatial resolution effects should depend on the goal, as one method may better preserve the field distribution, while another can reproduce spatial resolution degradation. The results presented should help direct future inter-instrument comparisons.Comment: Accepted for publication in Solar Physics. The final publication (including full-resolution figures) will be available at http://www.springerlink.co

The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory

The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne telesocope in June 2009 for almost six days over the Arctic Circle. As a polarimeter IMaX uses fast polarization modulation (based on the use of two liquid crystal retarders), real-time image accumulation, and dual beam polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to achieve a spectral resolution of 85 mAA. IMaX uses the high Zeeman sensitive line of Fe I at 5250.2 AA and observes all four Stokes parameters at various points inside the spectral line. This allows vector magnetograms, Dopplergrams, and intensity frames to be produced that, after reconstruction, reach spatial resolutions in the 0.15-0.18 arcsec range over a 50x50 arcsec FOV. Time cadences vary between ten and 33 seconds, although the shortest one only includes longitudinal polarimetry. The spectral line is sampled in various ways depending on the applied observing mode, from just two points inside the line to 11 of them. All observing modes include one extra wavelength point in the nearby continuum. Gauss equivalent sensitivities are four Gauss for longitudinal fields and 80 Gauss for transverse fields per wavelength sample. The LOS velocities are estimated with statistical errors of the order of 5-40 m/s. The design, calibration and integration phases of the instrument, together with the implemented data reduction scheme are described in some detail.Comment: 17 figure

Lactancia materna ineficaz: prevalencia y factores asociados

RESUMENIntroducción: Es posible evitar muertes neonatales mediante la lactancia materna desde el primer día devida, pues la leche materna es el alimento óptimo para el lactante por su contenido nutricional necesariofavorecer el crecimiento y desarrollo. Objetivo: Determinar la prevalencia y factores asociados aldiagnóstico de enfermería “Lactancia materna ineficaz” en lactantes menores de 6 meses hospitalizados enuna institución de tercer nivel.Metodología: Estudio de corte transversal. Se seleccionaron 108 binomios(madre e hijo) hospitalizados en una institución de tercer nivel de atención en el año 2009, se aplicó unformato validado para identificar el diagnóstico. Se realizó análisis Rasch a las variables que representanlas características definitorias del diagnóstico, con el cual se creó una escala de 0 a 100 y se construyóun modelo de regresión lineal con las variables asociadas a la medida del diagnóstico.Resultados:la prevalencia del diagnóstico fue de 93,5 %, la característica definitoria más fácil de encontrar fueIncapacidad del lactante para agarrarse al pecho materno y la más difícil fue agitación y llanto del lactantedentro de la primera hora después de la lactancia materna. La regresión lineal mostró factores asociadoscomo: género femenino, peso del lactante y necesidad de la madre de ir a orinar.Conclusiones: Existeuna tendencia desfavorable tanto en la prevalencia como en la duración de la lactancia materna para loslactantes hospitalizados; la promoción de la lactancia materna debe ser un trabajo interdisciplinario;modificar las normas hospitalarias favoreciendo el contacto del binomio y la puesta temprana al pechomaterno. Salud UIS 2011; 43 (3): 271-279Palabras clave: Lactancia materna, diagnóstico de enfermería, lactante, prevalencia,factores asociadosABSTRACTIntroduction: neonatal deaths can be prevented by breastfeeding from the first day of life, as is the optimal foodfor infants by their nutritional content required for better growth and development.Objective: To determine theprevalence and associated factors with nursing diagnosis “ineffective breastfeeding” in infants under than 6 monthshospitalized in a tertiary institution.Methodology: Cross sectional study. We selected 108 pairs (mother and child)hospitalized in an institution of tertiary care in 2009, we applied a validated format to identify the diagnosis. Raschanalysis was performed for variables that represent the defining characteristics of the diagnosis, which created ascale of 0 to 100 and built a linear regression model the variables associated with the extent of diagnosis.Results:Prevalence of diagnosis was 93,5 %, the defining characteristic was easier to find the infant’s inability to hold onto the breast and the hardest was shaking and crying of the infant within the first hour after breastfeeding. Linearregression was associated factors such as: female gender, weight infant and the mother need to urinate.Conclusions:There is an unfavorable trend in both the prevalence and duration of breastfeeding for infants hospitalized, promotionof breastfeeding should be an interdisciplinary, modify hospital policies favoring the contact of the binomial and theearly start to the chest maternal. Salud UIS 2011; 43 (3): 271-279Keywords: Breastfeeding, nursing diagnosis, infant, prevalence, associated factor

Lactancia materna ineficaz: prevalencia y factores asociados

RESUMENIntroducción: Es posible evitar muertes neonatales mediante la lactancia materna desde el primer día devida, pues la leche materna es el alimento óptimo para el lactante por su contenido nutricional necesariofavorecer el crecimiento y desarrollo. Objetivo: Determinar la prevalencia y factores asociados aldiagnóstico de enfermería “Lactancia materna ineficaz” en lactantes menores de 6 meses hospitalizados enuna institución de tercer nivel.Metodología: Estudio de corte transversal. Se seleccionaron 108 binomios(madre e hijo) hospitalizados en una institución de tercer nivel de atención en el año 2009, se aplicó unformato validado para identificar el diagnóstico. Se realizó análisis Rasch a las variables que representanlas características definitorias del diagnóstico, con el cual se creó una escala de 0 a 100 y se construyóun modelo de regresión lineal con las variables asociadas a la medida del diagnóstico.Resultados:la prevalencia del diagnóstico fue de 93,5 %, la característica definitoria más fácil de encontrar fueIncapacidad del lactante para agarrarse al pecho materno y la más difícil fue agitación y llanto del lactantedentro de la primera hora después de la lactancia materna. La regresión lineal mostró factores asociadoscomo: género femenino, peso del lactante y necesidad de la madre de ir a orinar.Conclusiones: Existeuna tendencia desfavorable tanto en la prevalencia como en la duración de la lactancia materna para loslactantes hospitalizados; la promoción de la lactancia materna debe ser un trabajo interdisciplinario;modificar las normas hospitalarias favoreciendo el contacto del binomio y la puesta temprana al pechomaterno. Salud UIS 2011; 43 (3): 271-279Palabras clave: Lactancia materna, diagnóstico de enfermería, lactante, prevalencia,factores asociadosABSTRACTIntroduction: neonatal deaths can be prevented by breastfeeding from the first day of life, as is the optimal foodfor infants by their nutritional content required for better growth and development.Objective: To determine theprevalence and associated factors with nursing diagnosis “ineffective breastfeeding” in infants under than 6 monthshospitalized in a tertiary institution.Methodology: Cross sectional study. We selected 108 pairs (mother and child)hospitalized in an institution of tertiary care in 2009, we applied a validated format to identify the diagnosis. Raschanalysis was performed for variables that represent the defining characteristics of the diagnosis, which created ascale of 0 to 100 and built a linear regression model the variables associated with the extent of diagnosis.Results:Prevalence of diagnosis was 93,5 %, the defining characteristic was easier to find the infant’s inability to hold onto the breast and the hardest was shaking and crying of the infant within the first hour after breastfeeding. Linearregression was associated factors such as: female gender, weight infant and the mother need to urinate.Conclusions:There is an unfavorable trend in both the prevalence and duration of breastfeeding for infants hospitalized, promotionof breastfeeding should be an interdisciplinary, modify hospital policies favoring the contact of the binomial and theearly start to the chest maternal. Salud UIS 2011; 43 (3): 271-279Keywords: Breastfeeding, nursing diagnosis, infant, prevalence, associated factor