164 research outputs found

    Deuxième contribution é l'étude de Formica bruni Kutter (Hymenoptera, Formicidae)

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    Formica bruni décrite en 1966 par Kutter appartient au sous-genre Coptoformica Müll. connue de Forel sous le nom de Formica pressilabris "un peu exsecta ". La biologie de cette espèce est demeurée inconnue jusqu'à nous jours. La découverte d'une nouvelle station au Bois de Chênes, près de Nyon (Vaud, Suisse), nous a poussé à entreprendre une série de travaux afin de savoir dans quelle mesure cette espèce diffère des autres espèces de Coptoformica. La zone étudiée comportait 61 nids en 1978, 18 nids habités par 7 sociétés en 1983 et 2 nids occupés par deux sociétés en juillet 1984. F. bruni est une espèce vraisemblablement polygyne et facultativement polycalique; aucune agressivité n'a été observée entre les sociétés qui, d'autre part, exploitent en commun un même territoire trophique. Les sociétés sont de petites tailles et leur territoire exploité ainsi que leur taux d'activité dépendent principalement de la quantité de nourriture à disposition. Différents facteurs susceptibles de la quasi extinction de cette espèce dans cette station sont discutés (fauchage, pâturage, etc...)

    The unresolved case of sacral chordoma: from misdiagnosis to challenging surgery and medical therapy resistance.

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    PURPOSE: A sacral chordoma is a rare, slow-growing, primary bone tumor, arising from embryonic notochordal remnants. Radical surgery is the only hope for cure. The aim of our present study is to analyse our experience with the challenging treatment of this rare tumor, to review current treatment modalities and to assess the outcome based on R status. METHODS: Eight patients were treated in our institution between 2001 and 2011. All patients were discussed by a multidisciplinary tumor board, and an en bloc surgical resection by posterior perineal access only or by combined anterior/posterior accesses was planned based on tumor extension. RESULTS: Seven patients underwent radical surgery, and one was treated by using local cryotherapy alone due to low performance status. Three misdiagnosed patients had primary surgery at another hospital with R1 margins. Reresection margins in our institution were R1 in two and R0 in one, and all three recurred. Four patients were primarily operated on at our institution and had en bloc surgery with R0 resection margins. One had local recurrence after 18 months. The overall morbidity rate was 86% (6/7 patients) and was mostly related to the perineal wound. Overall, 3 out of 7 resected patients were disease-free at a median follow-up of 2.9 years (range, 1.6-8.0 years). CONCLUSION: Our experience confirms the importance of early correct diagnosis and of an R0 resection for a sacral chordoma invading pelvic structures. It is a rare disease that requires a challenging multidisciplinary treatment, which should ideally be performed in a tertiary referral center

    Isometric group actions on Banach spaces and representations vanishing at infinity

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    Our main result is that the simple Lie group G=Sp(n,1)G=Sp(n,1) acts properly isometrically on Lp(G)L^p(G) if p>4n+2p>4n+2. To prove this, we introduce property ({\BP}_0^V), for VV be a Banach space: a locally compact group GG has property ({\BP}_0^V) if every affine isometric action of GG on VV, such that the linear part is a C0C_0-representation of GG, either has a fixed point or is metrically proper. We prove that solvable groups, connected Lie groups, and linear algebraic groups over a local field of characteristic zero, have property ({\BP}_0^V). As a consequence for unitary representations, we characterize those groups in the latter classes for which the first cohomology with respect to the left regular representation on L2(G)L^2(G) is non-zero; and we characterize uniform lattices in those groups for which the first L2L^2-Betti number is non-zero.Comment: 28 page

    X-RED: A Satellite Mission Concept To Detect Early Universe Gamma Ray Bursts

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    Gamma ray bursts (GRBs) are the most energetic eruptions known in the Universe. Instruments such as Compton-GRO/BATSE and the GRB monitor on BeppoSAX have detected more than 2700 GRBs and, although observational confirmation is still required, it is now generally accepted that many of these bursts are associated with the collapse of rapidly spinning massive stars to form black holes. Consequently, since first generation stars are expected to be very massive, GRBs are likely to have occurred in significant numbers at early epochs. X-red is a space mission concept designed to detect these extremely high redshifted GRBs, in order to probe the nature of the first generation of stars and hence the time of reionisation of the early Universe. We demonstrate that the gamma and x-ray luminosities of typical GRBs render them detectable up to extremely high redshifts (z~10-30), but that current missions such as HETE2 and SWIFT operate outside the observational range for detection of high redshift GRB afterglows. Therefore, to redress this, we present a complete mission design from the science case to the mission architecture and payload, the latter comprising three instruments, namely wide field x-ray cameras to detect high redshift gamma-rays, an x-ray focussing telescope to determine accurate coordinates and extract spectra, and an infrared spectrograph to observe the high redshift optical afterglow. The mission is expected to detect and identify for the first time GRBs with z > 10, thereby providing constraints on properties of the first generation of stars and the history of the early Universe.Comment: 14 pages, 10 figures, spie.cls neede

    Occurrence and prognosis of lymph node metastases in patients selected for isolated limb perfusion with soft tissue sarcoma.

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    <b> <i>Background and Objectives:</i> </b> Extensive surgery is often required for advanced soft tissue sarcoma (STS) of the limb. In the 1980s, a new approach was developed: isolated limb perfusion (ILP). This study aimed to assess incidence and impact on patient survival based on lymph node metastasis with systematic radical lymphadenectomy during ILP. <b> <i>Methods:</i> </b> Retrospective study of 57 consecutive patients treated by ILP for limb STS with simultaneous radical lymph node dissection in our tertiary referral center between 1992 and 2015. <b> <i>Results:</i> </b> Median age was 62 years (19-87) and 30 patients were male (53%). Lymph node involvement was observed in 13 patients (N1, 23%), regarded as metastatic spreading in 4 angiosarcomas, 3 epithelioid sarcomas, 2 leiomyosarcomas, 2 undifferentiated sarcomas and 2 synovial sarcomas. For the N0 patient group, median survival was 73.9 months (CI 95% 41.9-105.9) compared to 15.1 months (CI 95% 7.4-22.6) in case of metastatic lymph node ( <i>p</i> =0.002). The median disease-free survival was 33,0 months (CI 95% 12,5-53.5) in N0 group and 8.0 months (CI 95% 4.0-11.9) in N1 ( <i>p</i> =0.006). <b> <i>Conclusions:</i> </b> Lymph node metastases of STS patients selected for ILP seemed to have a negative impact on both overall and disease-free survival. Radical lymph node dissection should be included in ILP procedure

    Monitoring butterfly abundance: beyond Pollard walks.

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    Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability

    Codeine accumulation and elimination in larvae, pupae, and imago of the blowfly Lucilia sericata and effects on its development.

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    The aim of this study was to evaluate the reliability of insect larvae as samples for toxicological investigations. For this purpose, larvae of Lucilia sericata were reared on samples of minced pig liver treated with different concentrations of codeine: therapeutic, toxic, and potentially lethal doses. Codeine was detected in all tested larvae, confirming the reliability of these specimens for qualitative toxicology analysis. Furthermore, concentrations measured in larvae were correlated with levels in liver tissue. These observations bring new elements regarding the potential use of opiates concentrations in larvae for estimation of drug levels in human tissues. Morphine and norcodeine, two codeine metabolites, have been also detected at different concentrations depending on the concentration of codeine in pig liver and depending on the substance itself. The effects of codeine on the development of L. sericata were also investigated. Results showed that a 29-h interval bias on the evaluation of the larval stage duration calculated from the larvae weight has to be considered if codeine was present in the larvae substrate. Similarly, a 21-h interval bias on the total duration of development, from egg to imago, has to be considered if codeine was present in the larvae substrate
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