1,143 research outputs found
Modéliser le fonctionnement d'exploitations agricoles de polyculture élevage pour une démarche de conseil. Cas de la zone cotonnière de l'ouest du Burkina Faso
CederomInternational audienceCette communication vise à montrer l'intérêt d'une méthode de conseil pour le pilotage stratégique des exploitations agricoles, en cours d'élaboration dans l'Ouest du Burkina Faso. Cette méthode s'appuie sur la modélisation du fonctionnement technico-économique des exploitations. La communication présente la structure du modèle en sept modules : ressources de l'exploitation, système de culture, système d'élevage, ration, production de fumure organique, fertilisation, économie de l'exploitation. Elle montre ensuite comment il peut être utilisé pour évaluer des scénarios d'évolution au sein d'une exploitation : réduction de la surface en coton, intégration d'une sole fourragère et d'un atelier d'embouche bovine. La situation initiale de l'exploitation est comparée aux scénarios en termes économiques (bilan vivrier, revenu, etc.) et techniques (bilan minéral partiel, disponibilité en fumure organique). La dernière partie de la communication permet de discuter des perspectives d'utilisation du modèle dans une démarche expérimentale de conseil transférable à moyen terme à des conseillers agricoles
Photometric study of the OB star clusters NGC 1502 and NGC 2169 and mass estimation of their members at the University Observatory Jena
In this work we present detailed photometric results of the trapezium like
galactic nearby OB clusters NGC 1502 and NGC 2169 carried out at the University
Observatory Jena. We determined absolute magnitudes of the mostly
resolved components using Landolt standard stars. This multi colour photometry
enables us to estimate spectral type and absorption as well as the masses of
the components, which were not available for most of the cluster members in the
literature so far, using models of stellar evolution. Furthermore, we
investigated the optical spectrum of the components ADS 2984A and SZ Cam of the
sextuple system in NGC 1502. Our spectra clearly confirm the multiplicity of
these components, which is the first investigation of this kind at the
University Observatory Jena.Comment: seven pages, eight pictures. Submitted to AN in Feb. 21st, accepted
April 30t
Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting
Fitting whole spectra at intermediate spectral resolution (R = 1000 -- 3000),
to derive physical properties of stellar populations, appears as an optimized
alternative to methods based on spectrophotometric indices: it uses all the
redundant information contained in the signal. This paper addresses the
validation of the method and it investigates the quality of the population
models together with the reliability of the fitting procedures. We are using
two algorithms: STECKMAP, a non-parametric regularized program and NBURSTS a
parametric non-linear minimization. We compare three spectral synthesis models
for single stellar populations: Pegase-HR, Galaxev (BC03) and Vazdekis/Miles,
and we analyse spectra of Galactic clusters whose populations are known from
studies of color-magnitude diagrams (CMD) and spectroscopy of individual stars.
We find that: (1) The quality of the models critically depends on the stellar
library they use. Pegase-HR and Vazdekis/Miles are consistent, while the
comparison between Pegase-HR and BC03 shows some systematics reflecting the
limitations of the stellar library (STELIB) used to generate the latter models;
(2) The two fitting programs are consistent; (3) For globular clusters and M67
spectra, the method restitutes metallicities in agreement with spectroscopy of
stars within 0.14 dex; (4) The spectroscopic ages are very sensitive to the
presence of a blue horizontal branch (BHB) or of blue stragglers. A BHB
morphology results in a young SSP-equivalent age. Fitting a free amount of blue
stars in addition to the SSP model to mimic the BHB improves and stabilizes the
fit and restores ages in agreement with CMDs studies. This method is
potentially able to disentangle age or BHB effects in extragalactic clusters.Comment: accepted in MNRAS; Full version available at
http://www-obs.univ-lyon1.fr/labo/perso/prugniel/mina/koleva.pd
Constraints on Early Nucleosynthesis from the Abundance Pattern of a Damped Ly-alpha System at z = 2.626
We have investigated chemical evolution in the young universe by analysing
the detailed chemical enrichment pattern of a metal-rich galaxy at high
redshift. The recent detection of over 20 elements in the gas-phase of a damped
Lyman-alpha absorber (DLA) at z = 2.626 represents an exciting new avenue for
exploring early nucleosynthesis. Given a strict upper age of ~2.5 Gyr and a
gas-phase metallicity about one third solar, we have shown the DLA abundance
pattern to be consistent with the predictions of a chemical evolution model in
which the interstellar enrichment is dominated by massive stars with a small
contribution from Type Ia supernovae. Discrepancies between the empirical data
and the models are used to highlight outstanding issues in nucleosynthesis
theory, including a tendency for Type II supernovae models to overestimate the
magnitude of the "odd-even" effect at subsolar metallicities. Our results
suggest a possible need for supplemental sources of magnesium and zinc, beyond
that provided by massive stars.Comment: 12 pages, 7 figs. Accepted for publication in ApJ (The Astrophysical
Journal
Micromorphology of the skin (epidermis, dermis, subcutis) of the dog
Grossly, the skin of the dog is characterized by varying thicknesses, density of the hair coat and the implantation angle of the hairs. Multiple folds varying in shape are formed by the epidermis and the papillary layer of the corium. The epidermis consists of a stratum profundum with a continuous layer of basal cells, a stratum spinosum consisting of 3-6 cell layers, a stratum superficiale with single granulosa and "lucidum" cells and a well-developed stratum corneum. The corium shows a narrow stratum papillare corii containing delicate fibres and a broad stratum reticulare corii with mainly coarse fibre bundles. The subcutis is divided into adipose and fibrous layers. The broad adipose layer displays breed and individual differences which vary with the region of the body. The fibrous layer corresponds to the connective tissue layer, formerly described as fascia trunci superficialis. The morphological and functional unity of the corium and subcutis is discussed.This article has been scanned in colour with a HP Scanjet 5590; 300dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-Format.German Research Fun
Porcine endogenous retroviruses PERV A and A/C recombinant are insensitive to a range of divergent mammalian TRIM5 proteins including human TRIM5
The potential risk of cross-species transmission of porcine endogenous retroviruses (PERV) to humans has slowed the development of xenotransplantation, using pigs as organ donors. Here, we show that PERVs are insensitive to restriction by divergent TRIM5{alpha} molecules despite the fact that they strongly restrict a variety of divergent lentiviruses. We also show that the human PERV A/C recombinant clone 14/220 reverse transcribes with increased efficiency in human cells, leading to significantly higher infectivity. We conclude that xenotransplantation studies should consider the danger of highly infectious TRIM5{alpha}-insensitive human-tropic PERV recombinants
Evolutionary synthesis of galaxies at high spectral resolution with the code PEGASE-HR
We present PEGASE-HR, a new stellar population synthesis program generating
high resolution spectra (R=10 000) over the optical range lambda=400--680 nm.
It links the spectro-photometric model of galaxy evolution PEGASE.2 (Fioc &
Rocca-Volmerange 1997) to an updated version of the ELODIE library of stellar
spectra observed with the 193 cm telescope at the Observatoire de
Haute-Provence (Prugniel & Soubiran 2001a). The ELODIE star set gives a fairly
complete coverage of the Hertzprung-Russell (HR) diagram and makes it possible
to synthesize populations in the range [Fe/H]=-2 to +0.4. This code is an
exceptional tool for exploring signatures of metallicity, age, and kinematics.
We focus on a detailed study of the sensitivity to age and metallicity of the
high-resolution stellar absorption lines and of the classical metallic indices
proposed until now to solve the age-metallicity degeneracy. Validity tests on
several stellar lines are performed by comparing our predictions for Lick
indices to the models of other groups. The comparison with the lower resolution
library BaSeL (Lejeune et al. 1997) confirms the quality of the ELODIE library
when used for simple stellar populations (SSPs) from 10 Myr to 20 Gyr.
Predictions for the evolved populations of globular clusters and elliptical
galaxies are given and compared to observational data. Two new high-resolution
indices are proposed around the Hgamma line. They should prove useful in the
analysis of spectra from the new generation of telescopes and spectrographs.Comment: 18 pages, 18 figures. Astronomy & Astrophysics, in press. The models
are available at http://www.iap.fr/pegase
Search for low-mass PMS companions around X-ray selected late B stars
We have observed 49 X-ray detected bright late B-type dwarfs to search for
close low-mass pre-main sequence (PMS) companions using the European Southern
Observatory's ADONIS (Adaptive Optics Near Infrared System) instrument. We
announce the discovery of 21 new companions in 9 binaries, 5 triple, 4
quadruple system and 1 system consisting of five stars. The detected new
companions have K magnitudes between 6.5 mag and 17.3 mag. and angular
separations ranging from 0.2 and 14.1 arcsec (18-2358 AU).Comment: Accepted for publication in Astronomy and Astrophysic
Maximal surgical tumour load reduction in immune-checkpoint inhibitor naïve patients with melanoma brain metastases correlates with prolonged survival
Background: Recent therapeutic advances in metastatic melanoma have led to improved overall survival (OS) rates, with consequently an increased incidence of brain metastases (BM). The role of BM resection in the era of targeted and immunotherapy should be reassessed. In the current study we analysed the role of residual intracranial tumour load in a cohort of melanoma BM patients.
Methods: Retrospective single-centre analysis of a prospective registry of resected melanoma BM from 2013 to 2021. Correlations of residual tumour volume and outcome were determined with respect to patient, tumour and treatment regimens characteristics.
Results: 121 individual patients (66% male, mean age 59.9 years) were identified and included in the study. Pre- and postoperative systemic treatments included BRAF/MEK inhibitors, as well as combination or monotherapy of immune-checkpoint inhibitors (ICIs). Median OS of the entire cohort was 20 months. Cox proportional-hazard analysis revealed postoperative anti-CTLA4+anti-PD-1 therapy (HR 0.07, p = .01) and postoperative residual intracranial tumour burden (HR 1.4, p = .027) as significant predictors for OS. Further analysis revealed that ICI-naïve patients with residual tumour volume ≤3.5 cm3 and postoperative ICI showed significantly prolonged OS compared to patients with residual volume >3.5 cm3 (p < .0001). Subgroup analysis of ICI-naïve patients showed steroid intake postoperatively to be negatively associated with OS, however residual tumour volume ≤3.5 cm3 remained independently correlated with superior OS (HR 0.14, p < .001).
Conclusion: Besides known predictive factors like postoperative ICI, a maximal intracranial tumour burden reduction seems to be beneficial, especially in ICI-naïve patients. This highlights the importance of local CNS control and the need to further investigating the role of initial surgical tumour load reduction in randomised clinical trials.
Keywords: Brain metastases; Extent of resection; Immunotherapy; Melanoma; Tumour residua
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