843 research outputs found
Modifications et stabilité du phosphore échangeable d'un ferralsol ingéré par un ver géophage
L'un des paramètres des cinétiques de dilution isotopique du phosphore est modifié par l'ingestion, du ferralsol étudié, par le ver géophage #Pontoscolex corethrurus (#Glossoscolecidae, #Oligochaeta$). La concentation d'ions phosphate de la solution du sol et le compartiment d'ions immédiatement échangeables associé au sol sont nettement augmentés. Divers mécanismes pouvant expliquer ces modifications sont discutés. La minéralisation du phosphore organique s'effectue au profit des formes les plus rapidement échangeables. (Résumé d'auteur
: Introduction
Disponible en ligne sur le site de la revue (http://www.journal-reset.org/index.php/RESET/)International audienceLe premier numéro de la revue RESET a montré qu'il fallait nuancer l'enthousiasme suscité par les nouvelles technologies, notamment les approches qui soutiennent que l'accès à Internet ferait disparaitre les inégalités de classe. Dans le domaine de la santé mentale, on retrouve une même opposition, passablement stérile, entre enthousiasme et pessimisme : pour la dépasser, ce second numéro préfère, à l'opposition du " pour " et du " contre ", la question du " comment " et " sous quelles conditions " ; une telle problématisation apparaissant comme une condition de rupture avec nos prénotions. On se demandera comment Internet contribue à la production des catégories relatives à la santé mentale. Ou encore comment ces catégories se créent, puis sont réappropriées ou contestées par les individus et les groupes. On verra enfin comment Internet change les trajectoires de soin et les méthodes thérapeutiques et de quelles manières les outils de communication électronique sont utilisés par des groupes de patients
Quantitative assessment of the effects of space allowance, group size and floor characteristics on the lying behaviour of growing-finishing pigs
To obtain quantitative information that can be later used in animal welfare modelling, the relationship between the lying behaviour of growing-finishing pigs (initial body weight (BW) between 19 and 87 kg) and different factors related to the housing conditions, with a potential negative effect on their welfare, was studied by means of a meta-analytical approach. Data from 22 experiments reported in 21 scientific publications were collected. The space allowance, expressed on an allometric basis by means of a k-value (m2/BW0.667), the group size (n) and the floor characteristics (fully and partly slatted v. non-slatted floor), as well as their significant two-way interactions were used as fixed effects, and the experiment was used as a random factor to take into account the interexperiment effect. Further regression analyses were performed on the predicted values of observations in order to improve the adjustment of data. A significant quadratic relationship was established between space allowance (k-value, P <0.05; squared k-value, P <0.01) and the percentage of time spent lying. A significant interaction between the k-value and the floor type was also found (P <0.05), showing that the relationship between space allowance and lying behaviour is affected by the presence or absence of slats. Threshold k-values were obtained using broken-line analyses, being about 0.039 for slatted floors and almost double for non-slatted floors. Compared to other studies, these values suggest that the ability to rest as space availability decreases may be compromised before a reduced performance becomes apparent. Group size did not show a significant effect. Additional information should be added to the model, as further data become available, to adjust the proposed parameters as well as to try to include the effect of other important aspects such as that of ambient temperature
Skew-Product Decomposition of Planar Brownian Motion and Complementability
International audienceLet be a complex Brownian motion starting at 0 and the complex Brownian motion defined by . The natural filtration of is the filtration generated by up to an arbitrary rotation. We show that given any two different matrices and in , there exists an -previsible process taking values in such that the Brownian motion generates the whole filtration . As a consequence, for all and in such that , the Brownian motion is complementable in
Integrated crop-livestock management system: C and N stocks in a Brazilian clayey oxisol using NIRS.
Integrated crop-livestock management systems (ICLS) have been increasingly recommended in Brazil. However, knowledge on the indicators used to evaluate their impact on soil carbon (C) and nitrogen (N) concentrations and stocks is still limited. The study was undertaken to evaluate the effects of ICLS systems under two tillage and fertilization regimes on C and N stocks and concentrations at a 0-30 cm depth. The following soil management systems were studied: continuous pasture; continuous crop; crop/pasture rotation; and pasture/crop rotation. The native Cerrado was used as a control. The rotation systems were on a four year cycle. Under the rotation and continuous crop systems there were two levels of soil tillage (conventional and no-tillage) and fertility (maintenance and corrective fertility). The soil tillage and land use systems had a significant impact on the concentrations of C and N in the soil; however, no effect was observed for the fertilizer treatment. ICLS systems did not differ from continuous systems with regard to the C and N stocks; however, these elements tended to accumulate under ICLS systems associated with no-tillage. NIR spectroscopy proved to be a useful tool in quantifying the concentrations of C and N in the soil
Horizontal partial laryngectomy for supraglottic squamous cell carcinoma
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
Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors
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 -wave phase for a weak repulsive interchain
backscattering term , despite the persistence of dominant SDW
correlations in the normal state. Antiferromagnetism becomes unstable against
the formation of a charge-density-wave state when exceeds some
critical value. While these features persist when both Umklapp processes and
interchain forward scattering () are taken into account, the effect
of alone is found to frustrate nearest-neighbor interchain - and
-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 -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
Spin and orbital frustration in MnSc_2S_4 and FeSc_2S_4
Crystal structure, magnetic susceptibility, and specific heat were measured
in the normal cubic spinel compounds MnSc_2S_4 and FeSc_2S_4. Down to the
lowest temperatures, both compounds remain cubic and reveal strong magnetic
frustration. Specifically the Fe compound is characterized by a Curie-Weiss
temperature \Theta_{CW}= -45 K and does not show any indications of order down
to 50 mK. In addition, the Jahn-Teller ion Fe^{2+} is orbitally frustrated.
Hence, FeSc_2S_4 belongs to the rare class of spin-orbital liquids. MnSc_2S_4
is a spin liquid for temperatures T > T_N \approx 2 K.Comment: 4 pages, to be published in Physical Review Letter
Superconductivity in an organic insulator at very high magnetic fields
We investigate by electrical transport the field-induced superconducting
state (FISC) in the organic conductor -(BETS)FeCl. Below 4 K,
antiferromagnetic-insulator, metallic, and eventually superconducting (FISC)
ground states are observed with increasing in-plane magnetic field. The FISC
state survives between 18 and 41 T, and can be interpreted in terms of the
Jaccarino-Peter effect, where the external magnetic field {\em compensates} the
exchange field of aligned Fe ions. We further argue that the Fe
moments are essential to stabilize the resulting singlet, two-dimensional
superconducting stateComment: 9 pages 3 figure
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