2,613 research outputs found
Endogenous circannual rhythm in LH secretion: insight from signal analysis coupled with mathematical modelling
In sheep as in many vertebrates, the seasonal pattern of reproduction is
timed by the annual photoperiodic cycle, characterized by seasonal changes in
the daylength. The photoperiodic information is translated into a circadian
profile of melatonin secretion. After multiple neuronal relays (within the
hypothalamus), melatonin impacts GnRH (gonadotrophin releasing hormone)
secretion that in turn controls ovarian cyclicity. The pattern of GnRH
secretion is mirrored into that of LH (luteinizing hormone) secretion, whose
plasmatic level can be easily measured. We addressed the question of whether
there exists an endogenous circannual rhythm in a tropical sheep population
that exhibits clear seasonal ovarian activity when ewes are subjected to
temperate latitudes. We based our analysis on LH time series collected in the
course of 3 years from ewes subjected to a constant photoperiodic regime. Due
to intra- and inter- animal variability and unequal sampling times, the
existence of an endogenous rhythm is not straightforward. We have used
time-frequency signal processing methods to extract hidden rhythms from the
data. To further investigate the LF (low frequency) and HF (high frequency)
components of the signals, we have designed a mathematical model of LH
plasmatic level accounting for the effect of experimental sampling times. The
model enables us to confirm the existence of an endogenous circannual rhythm,
to investigate the action mechanism of photoperiod on the pulsatile pattern of
LH secretion (control of the interpulse interval) and to conclude that the HF
component is mainly due to the experimental sampling protocol
Huertos infantiles con musgo de Madagascar en régimen de perfeccionamiento activo para entrega intracomunitaria
El objetivo de este proyecto es asesorar a la empresa francesa “Garden & the City” a abrir un nuevo mercado en Bélgica. Con ese fin creamos una consultoría, Guiar & Meclaire Export Asociados, cuyo objeto social se puede resumir en asesoramiento e intermediación en comercio internacional.
La operación consiste en comercializar unos huertos infantiles fabricados por la compañía francesa en la parte francófona de Bélgica, más concretamente en Thuin Gozée. Nuestra intervención suple las carencias exportadoras de la compañía francesa y lo hace a través de un contrato de consultoría y de agencia comercial. Hemos realizado un estudio de mercado en el país de destino y los hemos asesorado en temas de fiscalidad, transporte, de financiación y de comercialización. Además, hemos enriquecido el proceso productivo incluyendo una importación de musgo desde Madagascar en régimen de perfeccionamiento activo (RPA) para ser añadido en el producto con el fin de ahorrar costes a nuestro cliente
DynPeak : An algorithm for pulse detection and frequency analysis in hormonal time series
The endocrine control of the reproductive function is often studied from the
analysis of luteinizing hormone (LH) pulsatile secretion by the pituitary
gland. Whereas measurements in the cavernous sinus cumulate anatomical and
technical difficulties, LH levels can be easily assessed from jugular blood.
However, plasma levels result from a convolution process due to clearance
effects when LH enters the general circulation. Simultaneous measurements
comparing LH levels in the cavernous sinus and jugular blood have revealed
clear differences in the pulse shape, the amplitude and the baseline. Besides,
experimental sampling occurs at a relatively low frequency (typically every 10
min) with respect to LH highest frequency release (one pulse per hour) and the
resulting LH measurements are noised by both experimental and assay errors. As
a result, the pattern of plasma LH may be not so clearly pulsatile. Yet,
reliable information on the InterPulse Intervals (IPI) is a prerequisite to
study precisely the steroid feedback exerted on the pituitary level. Hence,
there is a real need for robust IPI detection algorithms. In this article, we
present an algorithm for the monitoring of LH pulse frequency, basing ourselves
both on the available endocrinological knowledge on LH pulse (shape and
duration with respect to the frequency regime) and synthetic LH data generated
by a simple model. We make use of synthetic data to make clear some basic
notions underlying our algorithmic choices. We focus on explaining how the
process of sampling affects drastically the original pattern of secretion, and
especially the amplitude of the detectable pulses. We then describe the
algorithm in details and perform it on different sets of both synthetic and
experimental LH time series. We further comment on how to diagnose possible
outliers from the series of IPIs which is the main output of the algorithm.Comment: Nombre de pages : 35 ; Nombre de figures : 16 ; Nombre de tableaux :
Evaluación de los elementos de la comunicación interna en el personal administrativo de la Marina de Guerra. Callao. 2021
La presente investigación tiene como título “Evaluación de los elementos de la
comunicación interna en el personal administrativo de la Marina de Guerra. Callao.
2021”, tuve como objetivo principal, Interpretar el nivel de evaluación de los
elementos de la comunicación interna en el personal administrativo de la Marina de
Guerra – Callao, 2021. La investigación corresponde al tipo aplicado, con un
enfoque cuantitativo, con un nivel de investigación descriptivo simple, con un diseño
no experimental. La recolección de la información fue a la Marina de Guerra del
Perú, direccionada al área administrativa, con una muestra censal con un total de
102 personas. El instrumento que se empleo fue cuestionario de preguntas, lo cual
fue realizado vía Google formulario, que detallo 18 preguntas que cumplieron con
la validez del 100% y confiabilidad mediante el coeficiente de “Alfa de Cron Bach”
con 0.88. Los resultados que se consiguieron con la encuesta fueron procesados
en el programa estadístico SPSS versión 25. El objetivo general de la investigación
dio como resultado que 1.9% no manejan los elementos de la comunicación interna,
el 6.5% manifiesta que casi nunca, el 26.4% de los trabajadores encuestados
aseguran a veces, el 44.1% de los trabajadores manejan los elementos de la
comunicación interna aseguraron “Casi siempre”. Mientras que el 21.1% confirman
que “siempre”. Se concluye que las herramientas utilizadas en la Institución,
tuvieron gran relevancia para que los mensajes enviados tengan gran aceptación
por parte del público interno, y, de esta forma, lograr que en la entidad pueda haber
un buen desempeño, de acuerdo a los objetivos planteados por la empresa
The Earth as an extrasolar transiting planet - II: HARPS and UVES detection of water vapor, biogenic O, and O
The atmospheric composition of transiting exoplanets can be characterized
during transit by spectroscopy. For the transit of an Earth twin, models
predict that biogenic and should be detectable, as well as water
vapour, a molecule linked to habitability as we know it on Earth. The aim is to
measure the Earth radius versus wavelength - or the atmosphere
thickness - at the highest spectral resolution available to fully
characterize the signature of Earth seen as a transiting exoplanet. We present
observations of the Moon eclipse of 21-12-2010. Seen from the Moon, the Earth
eclipses the Sun and opens access to the Earth atmosphere transmission
spectrum. We used HARPS and UVES spectrographs to take penumbra and umbra
high-resolution spectra from 3100 to 10400 Ang. A change of the quantity of
water vapour above the telescope compromised the quality of the UVES data. We
corrected for this effect in the data processing. We analyzed the data by 3
different methods. The 1st method is based on the analysis of pairs of penumbra
spectra. The 2nd makes use of a single penumbra spectrum, and the 3rd of all
penumbra and umbra spectra. Profiles are obtained with the three
methods for both instruments. The 1st method gives the best result, in
agreement with a model. The second method seems to be more sensitive to the
Doppler shift of solar spectral lines with respect to the telluric lines. The
3rd method makes use of umbra spectra which bias the result, but it can be
corrected for this a posteriori from results with the first method. The 3
methods clearly show the spectral signature of the Rayleigh scattering in the
Earth atmosphere and the bands of HO, O, and O. Sodium is detected.
Assuming no atmospheric perturbations, we show that the E-ELT is theoretically
able to detect the A-band in 8~h of integration for an Earth twin at
10pc.Comment: Final version accepted for publication in A&A - 21 pages, 27 figures.
Abstract above slightly shortened wrt the original. The ArXiv version has low
resolution figures, but a version with full resolution figures is available
here:
http://www.obs-hp.fr/~larnold/publi_to_download/eclipse2010_AA_v5_final.pd
Apport scientifique, éducatif et ludique de l’espace Blaise Pascal au muséum Henri-Lecoq de Clermont-Ferrand
Les responsables chargés de la mise en place d’un espace éducatif et ludique consacré aux travaux de Blaise Pascal dressent un premier bilan de cette expérience en montrant l’intérêt de ce projet – mené par une équipe pluridisciplinaire – dont l’objectif était d’associer explications et apports scientifiques, jeu et pédagogie et qui, en définitive, a contribué au renouvellement des outils et méthodes de travail du service éducatif du musée
The Earth as an extrasolar transiting planet: Earth's atmospheric composition and thickness revealed by Lunar eclipse observations
An important goal within the quest for detecting an Earth-like extrasolar
planet, will be to identify atmospheric gaseous bio-signatures. Observations of
the light transmitted through the Earth's atmosphere, as for an extrasolar
planet, will be the first step for future comparisons. We have completed
observations of the Earth during a Lunar eclipse, a unique situation similar to
that of a transiting planet. We aim at showing what species could be detected
in its atmosphere at optical wavelengths, where a lot of photons are available
in the masked stellar light. We present observations of the 2008 August 16 Moon
eclipse performed with the SOPHIE spectrograph at the Observatoire de
Haute-Provence. Locating the spectrograph fibers in the penumbra of the
eclipse, the Moon irradiance is then a mix of direct, unabsorbed Sun light and
solar light that has passed through the Earth's limb. This mixture essentially
reproduces what is recorded during the transit of an extrasolar planet. We
report here the clear detection of several Earth atmospheric compounds in the
transmission spectra, such as ozone, molecular oxygen, and neutral sodium as
well as molecular nitrogen and oxygen through the Rayleigh signature. Moreover,
we present a method that allows us to derive the thickness of the atmosphere
versus the wavelength for penumbra eclipse observations. We quantitatively
evaluate the altitude at which the atmosphere becomes transparent for important
species like molecular oxygen and ozone, two species thought to be tightly
linked to the presence of life. The molecular detections presented here are an
encouraging first attempt, necessary to better prepare for the future of
extremely-large telescopes and transiting Earth-like planets. Instruments like
SOPHIE will be mandatory when characterizing the atmospheres of transiting
Earth-like planets from the ground and searching for bio-marker signatures.Comment: 15 pages, 14 figures, 2 tables. Accepted for publication in Astronomy
and Astrophysic
Angular analysis of B0→D∗−D∗+s with D∗+s→D+sγ decays
The first full angular analysis of the B0→D∗−D∗+s decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The D∗+s→D+sγ and D*− → D¯¯¯¯0π− vector meson decays are used with the subsequent D+s → K+K−π+ and D¯¯¯¯0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ(B0→D∗−D∗+s) × ℬ(D∗+s→D+sγ)]/ℬ(B0 → D*−D+s) is measured to be 2.045 ± 0.022 ± 0.071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed Bs → D*−D+s decay is made with a significance of seven standard deviations. The branching fraction ratio ℬ(Bs → D*−D+s)/ℬ(B0 → D*−D+s) is measured to be 0.049 ± 0.006 ± 0.003 ± 0.002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractionsS
- …