A unified model for the LISA measurements and instrument simulations

LISA is a space-based mHz gravitational-wave observatory, with a plannedlaunch in 2034. It is expected to be the first detector of its kind, and willpresent unique challenges in instrumentation and data analysis. An accuratepre-flight simulation of LISA data is a vital part of the development of boththe instrument and the analysis methods. The simulation must include a detailedmodel of the full measurement and analysis chain, capturing the main featuresthat affect the instrument performance and processing algorithms. Here, wepropose a new model that includes, for the first time, proper relativistictreatment of reference frames with realistic orbits; a model for onboard clocksand clock synchronization measurements; proper modeling of total laserfrequencies, including laser locking, frequency planning and Doppler shifts;better treatment of onboard processing and updated noise models. We thenintroduce two implementations of this model, LISANode and LISA Instrument. Wedemonstrate that TDI processing successfully recovers gravitational-wavesignals from the significantly more realistic and complex simulated data.LISANode and LISA Instrument are already widely used by the LISA community and,for example, currently provide the mock data for the LISA Data Challenges.<br

Ictioplancton asociado a praderas de Posidonia oceanica durante la época estival en la reserva marina de Tabarca

El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton.Habitat complexity plays a key role in survival in early stages of fish larvae. We investigated fish larvae assemblage and its relation with P. oceanica seagrass at the Tabarca Island Marine Reserve. Samples were taken using moored plankton nets at two depths (0 and 2 m from P. oceanica meadow) over five consecutive days in July 2000. Three hundred and fifty-three larvae were captured. The most abundant families were Clupeidae (31%), Sparidae (27%), Engraulidae (11%) and Gobiidae (6%). We observed that small fish larvae were able to select nursery areas. We conclude that the P. oceanica leaf canopy is a major factor in structuring the larval fish assemblages of some demersal species. Key words: Fish larvae, Seagrasses, Habitat shelter, Moored plankton nets.El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton

Structure and magnetism of self-organized Ge(1-x)Mn(x) nano-columns

We report on the structural and magnetic properties of thin Ge(1-x)Mn(x)films grown by molecular beam epitaxy (MBE) on Ge(001) substrates at temperatures (Tg) ranging from 80deg C to 200deg C, with average Mn contents between 1 % and 11 %. Their crystalline structure, morphology and composition have been investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy and x-ray diffraction. In the whole range of growth temperatures and Mn concentrations, we observed the formation of manganese rich nanostructures embedded in a nearly pure germanium matrix. Growth temperature mostly determines the structural properties of Mn-rich nanostructures. For low growth temperatures (below 120deg C), we evidenced a two-dimensional spinodal decomposition resulting in the formation of vertical one-dimensional nanostructures (nanocolumns). Moreover we show in this paper the influence of growth parameters (Tg and Mn content) on this decomposition i.e. on nanocolumns size and density. For temperatures higher than 180deg C, we observed the formation of Ge3Mn5 clusters. For intermediate growth temperatures nanocolumns and nanoclusters coexist. Combining high resolution TEM and superconducting quantum interference device magnetometry, we could evidence at least four different magnetic phases in Ge(1-x)Mn(x) films: (i) paramagnetic diluted Mn atoms in the germanium matrix, (ii) superparamagnetic and ferromagnetic low-Tc nanocolumns (120 K 400 K) and (iv) Ge3Mn5 clusters.Comment: 10 pages 2 colonnes revTex formatte