Altimetric sampling and mapping procedures induce spatial and temporal aliasing of the signal – characteristics of these aliasing effects in the Mediterranean Sea

International audienceThis study deals with spatial and temporal aliasing of the sea surface signal and its restitution with altimetric maps of Sea Level Anomalies (SLA) in the Mediterranean Sea. Spatial and temporal altimetry sampling, combined with a mapping process, are unable to restore high-frequency (HF) surface variability. In the Mediterranean Sea, it has been shown that signals whose intervals are less than 30–40 days are largely underestimated, and the residual HF restitution signal contains characteristic errors which make it possible to identify the spatial and temporal sampling of each satellite. The origin of these errors is relatively complex. Three main effects are involved: the sampling of the HF long-wavelength (LW) signal, the correction of this signal's aliasing and the mapping procedure. – The sampling depends on the characteristics of the satellites considered, but generally induces inter-track bias that needs to be corrected before the mapping procedure is applied. – Correcting the aliasing of the HF LW signal, carried out using a barotropic model output and/or an empirical method, is not perfect. In fact, the baroclinic part of the HF LW signal is neglected and the numerical model's capabilities are limited by the spatial resolution of the model and the forcing. The empirical method cannot precisely control the corrected signal. – The mapping process, which is optimised to improve restitution of mesoscale activity, does not propagate the LW signal far from the satellite tracks. Even though these residual errors are very low with respect to the total signal, their signature may be visible on maps of SLAs. However, these errors can be corrected by more careful consideration of their characteristics in terms of spatial distribution induced by altimetric along-track sampling. They can also be attenuated by increasing the altimetric spatial coverage through the merging of different satellites. Ultimately, the HF signal, which is missing in maps of SLA, can be completed using a numerical model in order to estimate the total surface signal. The barotropic HF (<30 days) component accounts for nearly 10% of the total variability. Locally, it contributes nearly 25% of the total variance

Datos imprecisos y mapas de distribución: el ejemplo de Phylan semicostatus Mulsant y Rey, 1854 (Coleoptera, Tenebrionidae) en la Serra de Tramuntana (Mallorca, Mediterráneo occidental)

Distribution maps are key tools for environmental management and biogeographic analyses. However, success in predicting spatial distribution is limited when using noisy presence/absence data sets. Both false absences and presences can be related with local departures from equilibrium (for example, temporary extinctions or unsuccessful colonisations). Moreover, false absences can arise from limited sampling effort. Here we explore an analytical strategy to get additional information on the presence/absence pattern of one target species from the presence/absence of all other species in the community. The logic is simple: the target species should display higher probability of presence at a site if a sample from this site is faunistically very close to the samples from other sites where the species occurs. Therefore, we first model presence/absence of the target species as a function of between-sample faunistic similarity. Second, the observed data for the target species are readjusted as a function of the expected probability of presence: current presences at sites with extreme low probability of presence are interpreted as unstable presences, and are recoded as absences. Seemingly, absences at sites with high probability of presence are interpreted as false absences, and are recoded as presences. In the experimental case presented herein, the recoding procedure is based on the presence/absence of 174 species, covering a broad taxonomic scope (snails, beetles, spiders and isopods). 1 km2 distribution maps of presence/absence of the endemic beetle Phylan semicostatus were modelled from these recoded data. Mapping is done using GARP based on four environmental explanatory variables. These maps seem to be more stable and less prone to fail in predicting presence than those derived directly from the observed data.Los mapas de distribución son herramientas clave para la gestión medioambiental y los análisis biogeográficos. Pero el éxito en las predicciones de distribución espacial es limitado cuando se dispone de datos imprecisos de la presencia/ausencia. Tanto falsas ausencias como falsas presencias pueden estar relacionadas con desviaciones locales del equilibrio (por ejemplo, extinciones temporales o colonizaciones no exitosas). Además, las falsas ausencias pueden surgir de un esfuerzo de muestreo limitado. Aquí se explora una estrategia analítica para obtener información adicional sobre el patron de presencia/ausencia de una especie diana a partir de la presencia/ausencia de otras especies en la comunidad. La logica es simple: la especie diana debería tener una mayor probabilidad de presencia en un punto si una muestra de este punto es faunísticamente muy similar a las muestras de otros puntos donde la especie ha sido detectada. Por tanto, primeros se modela la presencia/ausencia de la especie diana en función de la similaridad faunística entre puntos. En segundo lugar, los datos observados para la especie diana son reajustados en función de la probabilidad esperada de presencia: las presencias observadas en puntos con probabilidad de presencia muy baja son interpretadas como presencias inestables, y recodificadas como ausencias. De manera similar, las ausencias en puntos con probabilidad de presencia muy elevada son interpretadas como falsas ausencias, y recodificadas como presencias. En el caso experimental estudiado, el procedimiento de recodificación esta basado en los datos de presencia/ausencia de 174 especies, abarcando un abanico taxonómico muy amplio (caracoles terrestres, coleópteros, arañas e isópodos). El mapa de distribución de celdas de 1 km2 del coleóptero endémico Phylan semicostatus es modelado a partir de estos datos. El mapa de distribución es elaborado a partir de cuatro variables medioambientales, usando una estrategia analítica basada en algoritmos genéticos (GARP). Los mapas obtenidos con los datos recodificados parecen ser mas estables y menos susceptibles de fallar en sus predicciones que los mapas elaborados directamente con los datos originales

Primer registro de la medusa urticante invasora Gonionemus vertens en el hemisferio sur (Mar del Plata, Argentina)

En este trabajo registra el primer hallazgo de la hidromedusa Gonionemus vertens Agassiz, 1862 en el hemisferio sur. Alrededor de 30 medusas recientemente liberadas fueron encontradas en un acuario en septiembre de 2008. Este acuario contenía muestras bentónicas colectadas en la franja rocosa intermareal y submareal de Mar del Plata, cerca de uno de los puertos más importantes de Argentina. Las medusas fueron alimentadas con Artemia salina hasta su maduración gonadal. Se discute la posible vía de introducción de esta especie.In this paper we report the first finding of the hydromedusa Gonionemus vertens Agassiz, 1862 in the southern hemisphere. About thirty newly released medusae were found within an aquarium on September 2008. The aquarium contained benthic samples collected in intertidal and subtidal rocky fringe off Mar del Plata, near a commercially important harbor in Argentina. Medusae were feed with Artemia salina until sexual maturation. Possible way of species introduction is discussed.Fil: Rodriguez, Carolina Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pujol, M. G.. Provincia de Buenos Aires. Municipalidad de General Pueyrredon. Secretaría de Cultura. Museo Municipal de Ciencias Naturales Lorenzo Scaglia; ArgentinaFil: Mianzan, Hermes Walter. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Genzano, Gabriel Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentin

Calibration and First light of the Diabolo photometer at the Millimetre and Infrared Testa Grigia Observatory

We have designed and built a large-throughput dual channel photometer, Diabolo. This photometer is dedicated to the observation of millimetre continuum diffuse sources, and in particular, of the Sunyaev-Zel'dovich effect and of anisotropies of the 3K background. We describe the optical layout and filtering system of the instrument, which uses two bolometric detectors for simultaneous observations in two frequency channels at 1.2 and 2.1 mm. The bolometers are cooled to a working temperature of 0.1 K provided by a compact dilution cryostat. The photometric and angular responses of the instrument are measured in the laboratory. First astronomical light was detected in March 1995 at the focus of the new Millimetre and Infrared Testa Grigia Observatory (MITO) Telescope. The established sensitivity of the system is of 7 mK_RJ s^1/2$. For a typical map of at least 10 beams, with one hour of integration per beam, one can achieve the rms values of y_SZ ~ 7 10^-5 and the 3K background anisotropy Delta T/T ~ 7 10^-5, in winter conditions. We also report on a novel bolometer AC readout circuit which allows for the first time total power measurements on the sky. This technique alleviates (but does not forbid) the use of chopping with a secondary mirror. This technique and the dilution fridge concept will be used in future scan--modulated space instrument like the ESA Planck mission project.Comment: 10 pages, LaTeX, 12 figures, accepted for publication in Astronomy and Astrophysics Supplement Serie

Acquired Cold Urticaria: Clinical Features, Particular Phenotypes, and Disease Course in a Tertiary Care Center Cohort

BACKGROUND: Data about special phenotypes, natural course, and prognostic variables of patients with acquired cold urticaria (ACU) are scarce. OBJECTIVES: We sought to describe the clinical features and disease course of patients with ACU, with special attention paid to particular phenotypes, and to examine possible parameters that could predict the evolution of the disease. METHODS: This study was a retrospective chart review of 74 patients with ACU who visited a tertiary referral center of urticaria between 2005 and 2015. RESULTS: Fourteen patients (18.9%) presented with life-threatening reactions after cold exposure, and 21 (28.4%) showed negative results after cold stimulation tests (classified as atypical ACU). Nineteen patients (25.7%) achieved complete symptoms resolution at the end of the surveillance period and had no subsequent recurrences. Higher rates of atypical ACU along with a lower likelihood of achieving complete symptom resolution was observed in patients who had an onset of symptoms during childhood (P < .05). In patients with atypical ACU, shorter disease duration and lower doses of antihistamines required for achieving disease control were detected (P < .05). Age at disease onset, symptom severity, and cold urticaria threshold values were found to be related to disease evolution (P < .05). LIMITATIONS: This study was limited by its retrospective nature. CONCLUSIONS: The knowledge of the clinical predictors of the disease evolution along with the clinical features of ACU phenotypes would allow for the establishment of an early and proper therapeutic strategy

Is the biology of breast cancer changing? A study of hormone receptor status 1984-1986 and 1996-1997

Using archived tumours, those from 1984-1986 and 1996-1997 underwent immunohistochemistry for hormone receptors and grade analysis. A significant shift towards more ER-positive and low-grade disease was found; this appears to reflect screening practices, but could still influence survival

Channel waveguides and Mach-Zehnder structures on RbTiOPO₄ by Cs⁺ ion exchange

Cs+ ion exchange in RbTiOPO4 and (Yb,Nb):RTP/RTP(001) has been used to locally increase the refractive indices for waveguide circuit fabrication. Ti masks were fabricated on RTP samples by conventional photolithography. Cs+ exchange was done using a CsNO3 melt at 698 K during 2 h. Elemental analysis confirms an Cs+ profile with a variable depth. Apparently the Cs+ exchange is disfavored in the doped epitaxial sample. The refractive index variation is higher for nz than for nx,y. Near-field images of the guided modes at 633, 1064 and 1520 nm were recorded. The optical characterization shows propagation losses of 5 dB/cm at 1520 nm

Clonal and genetic structure of Iris odaesanensis and Iris rossii (Iridaceae): insights of the Baekdudaegan Mountains as a glacial refugium for boreal and temperate plants

The main Korean mountain range that stretches from north to south (the Baekdudaegan) has been suggested to harbor an important glacial refugium for boreal and temperate plant species. Under this scenario, we expect high levels of within-population genetic variation and low or moderate degree of among-population differentiation within these species. To test this hypothesis, we examined clonal diversity and levels of allozyme diversity in the boreal Iris odaesanensis and in its temperate congener Iris rossii. In addition, we compiled data on boreal and temperate species whose distribution in the Korean Peninsula is mostly centered in the Baekdudaegan to determine if there is a common pattern. We found lower clonal diversity in I. odaesanensis compared to I. rossii. Both studied species maintained high levels of genetic variation as well as a moderate genetic differentiation (%P = 52.5 and 47.5, A = 1.70 and 1.58, H e = 0.158 and 0.150, and F ST = 0.196 and 0.189 for I. odaesanensis and I. rossii, respectively), in line with what occurs for the species distributed on the Baekdudaegan (n = 14, %P = 46.7, A = 1.73, H e = 0.161, and F ST = 0.190). This study strongly suggests that the Baekdudaegan may have acted as a refugium for boreal and temperate species, in a similar way to the southern Appalachians in the eastern United States

Coupled Ising models with disorder

In this paper we study the phase diagram of two Ising planes coupled by a standard spin-spin interaction with bond randomness in each plane. The whole phase diagram is analyzed by help of Monte Carlo simulations and field theory arguments.Comment: 9 pages and 3 figure

Non-Abelian Bosonization and Haldane's Conjecture

We study the long wavelength limit of a spin S Heisenberg antiferromagnetic chain. The fermionic Lagrangian obtained corresponds to a perturbed level 2S SU(2) Wess-Zumino-Witten model. This effective theory is then mapped into a compact U(1) boson interacting with Z_{2S} parafermions. The analysis of this effective theory allows us to show that when S is an integer there is a mass gap to all excitations, whereas this gap vanishes in the half-odd-integer spin case. This gives a field theory treatment of the so-called Haldane's conjecture for arbitrary values of the spin S.Comment: 9 pages REVTeX, no figure