863 research outputs found

    Power loss estimation in the Electrostatic Separators of the ILC alternative head-on scheme at 500 GeV in the center-of-mass

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    This memo presents the power loss estimation in the Electrostatic Separators of the ILC alternative head-on scheme at 500 GeV in the center-of-mass, for the Nominal and High Luminosity beam parameters set, induced both by beam particles and radiative Bhabha processes

    Digestion of a vertisol by the endogeic earthworm Polypheretima elongata, Megascolecidae, increases soil phosphate extractibility

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    L'effet du ver de terre endogé #Polypheretima elongata$ sur l'état du phosphore dans des vertisols (Sud-Est de la Martinique, Antilles) a été étudié au laboratoire. Des turricules ont été récoltés en surface et comparés à du sol non ingéré. Les phosphates ont été extraits par un traitement séquentiel mettant en oeuvre des résines anioniques suivies d'une extraction au bicarbonate de sodium. Pour certaines répétitions, une fumigation au chloroforme a suivi l'extraction par résine pour l'immobilisation microbienne. Les teneurs en phosphates extractibes sont plus élevées de 43% dans les turricules que dans le sol mais il n'a ya pas de différences de teneurs en phosphore total. La fumigation n'a aucun effet sur les teneurs des turricules en phosphates extractibles au bicarbonate. Un fractionnement granulométrique des turricules et du sol indique que les vers ingÚrent préférentiellement des particules fines du sol. Cependant, l'augmentation des phosphates extraits par résine anionique est principalement attribuable à la digestion et aux processus microbiens qui ont lieu durant le transit intestinal. (Résumé d'auteur

    Consequences of transformation of native Cerrado in pasture land on the porosity of a clayey-sand red latosol

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    In the Brazilian savannah (Cerrados area), about 60 % of the surface area is used as pasture land and 30 % of the latter is cultivated pasture. Many studies have reported that pastures degrade quickly and degradation would be more intense when the soil was tilled prior pasture sowing. Pasture degradation (decrease in the pasture quality and yield, weed invasion) would be partly a consequence of the soil structure evolution (Balbino & Di Stefano, 1999). Origin of pasture degradation is still under discussion and analysis of the literature showed that there is a lack of quantitative data. The aim of this study is to perform a detailed analysis of the porosity in a low productivity cultivated pasture and to compare the results with the porosity of a similar soil still under native vegetation (CerradĂŁo, i.e. Scierophylous forest)

    Horizontal partial laryngectomy for supraglottic squamous cell carcinoma

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    Between 1981-1999, 75 patients treated for supraglottic SCC with horizontal supraglottic laryngectomy (HSL) at the Otolaryngology Head and Neck Surgery Department of Lausanne University Hospital were retrospectively studied. There were 16 patients with T1, 46 with T2 and 13 with T3 tumors. Among these, 16 patients (21%) had clinical neck disease corresponding to stage I, II, III and IV in 12, 39, 18 and 6 patients, respectively. All patients had HSL. Most patients had either elective or therapeutic bilateral level II-IV selective neck dissection. Six patients (8%) with advanced neck disease had ipsilateral radical and controlateral elective II-IV selective neck dissections. Adjuvant radiotherapy was given to 25 patients (30%) for either positive surgical margins (n=8), pathological nodal status (n=14) or both (n=3). Median follow-up was 48months (range, 24-199). Five-year disease-specific survival and locoregional and local control were 92, 90 and 92.5%, respectively. Among five patients who were diagnosed with local recurrence, one had a total laryngectomy (1.4%); the others were treated by endoscopic laser surgery. Two patients had both a local and regional recurrence. They were salvaged with combined surgery and radiotherapy, but eventually died of their disease. Cartilage infiltration seems to influence both local control (P=0.03) and disease-specific survival (P=0.06). There was a trend for worse survival with pathological node involvement (P=0.15) and extralaryngeal extension of the cancer (P=0.1). All patients except one recovered a close to normal function after the treatment. Aspiration was present in 16 patients (26%) in the early postoperative period. A median of 16days (7-9) was necessary to recover a close to normal diet. Decannulation took a median of 17days (8-93). Seven patients kept a tracheotomy tube for up to 3months because of persistent aspiration. There was no permanent tracheostomy or total laryngectomy for functional purposes. Horizontal supraglottic laryngectomy remains an adequate therapeutic alternative for supraglottic squamous cell carcinoma, offering an excellent oncological outcome. The postoperative functional morbidity is substantial, indicating the need for careful patient selection, but good laryngeal function recovery is the rule. The surgical alternative is endoscopic laser surgery, which may offer comparable oncological results with less functional morbidity. Nevertheless, these two different techniques need to be compared prospectivel

    Glassy freezing of orbital dynamics in FeCr2S4 and FeSc2S4

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    We report on a thorough dielectric investigation of the glass-like freezing of the orbital reorientation-dynamics, recently found for the crystalline sulpho-spinels FeCr2S4 and FeSc2S4. As the orbital reorientations are coupled to a rearrangement of the surrounding ionic lattice via the Jahn-Teller effect, the freezing of the orbital moments is revealed by a relaxational behaviour of the complex dielectric permittivity. Additional conductivity (both dc and ac) and contact contributions showing up in the spectra are taken into account by an equivalent circuit description. The orbital relaxation dynamics continuously slows down over six decades in time, before at the lowest temperatures the glass transition becomes suppressed by quantum tunnelling.Comment: J. Non-Cryst. Solids, in press. 6 pages, 4 figure

    Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors

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    Using a renormalization group approach, we determine the phase diagram of an extended quasi-one-dimensional electron gas model that includes interchain hopping, nesting deviations and both intrachain and interchain repulsive interactions. d-wave superconductivity, which dominates over the spin-density-wave (SDW) phase at large nesting deviations, becomes unstable to the benefit of a triplet ff-wave phase for a weak repulsive interchain backscattering term g1⊄>0g_1^\perp>0, despite the persistence of dominant SDW correlations in the normal state. Antiferromagnetism becomes unstable against the formation of a charge-density-wave state when g1⊄g_1^\perp exceeds some critical value. While these features persist when both Umklapp processes and interchain forward scattering (g2⊄g_2^\perp) are taken into account, the effect of g2⊄g_2^\perp alone is found to frustrate nearest-neighbor interchain dd- and ff-wave pairing and instead favor next-nearest-neighbor interchain singlet or triplet pairing. We argue that the close proximity of SDW and charge-density-wave phases, singlet d-wave and triplet ff-wave superconducting phases in the theoretical phase diagram provides a possible explanation for recent puzzling experimental findings in the Bechgaard salts, including the coexistence of SDW and charge-density-wave phases and the possibility of a triplet pairing in the superconducting phase.Comment: 19 pages, 13 figure

    Change in the hydraulic properties of a Brazilian clay Ferralsol on clearing for pasture.

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    32 ref. doi: 10.1016/j.geoderma.2003.08.017Ferralsols under native vegetation have a weak to moderate macrostructure and a well-developed microstructure corresponding to subrounded microaggregates that are usually 80 to 300 ÎŒm in size. The aim of this study was to analyze how the hydraulic properties of a clay Ferralsol were affected by a change of structure when the native vegetation is cleared for pasture. We studied the macrostructure in the field and microstructure in scanning electron microscopy. The water retention properties were determined by using pressure cell equipment. We determined the saturated hydraulic conductivity, Ks, by applying a constant hydraulic head to saturated core samples, and the unsaturated hydraulic conductivity, K(Κ), by applying the evaporation method to undisturbed core samples. Results showed a significant decrease in the water retained at −1 and −10 hPa from 0- to 40-cm-depth when the native vegetation is cleared for pasture. That decrease in the water retained was related to a smaller development of microaggregation and greater proportion of microaggregates in close packing. For smaller water potential, there was no difference of water retained at every depth between native vegetation and pasture. Pedotransfer functions established earlier for Brazilian Ferralsols and using clay content as single predictor gave pretty good results but the precision of the estimation decreased when the water potential increased. This decrease in the precision was related to the lack of predictor taking structure into account. Ks and K(Κ) showed an upward trend with depth under native vegetation and pasture. Except at 0–7-cm depth between the Brachiaria clumps in the pasture where smaller Ks and K(Κ) than at the other depth was recorded whatever land use, we did not record any significant difference of Ks and K(Κ) at every depth between native vegetation and pasture. The upward trend shown by the hydraulic conductivity with depth was related to the increase in the development of microaggregation with depth

    4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line.

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    TUPC087International audienceEmittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to ver- tical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emit- tance growth and ïŹnd possible remedies. This requires ef- ïŹcient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods devel- oped at SLAC and KEK have been used to estimate the ver- tical emittance, based on multiple location beam size mea- surements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement er- rors and other ïŹ‚uctuations in the beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their per- formance in the ATF extraction line
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