Preliminary results on underground muon bundles observed in the Frejus proton-decay detector

The proton-decay detector installed in the Modane Underground laboratory (4400 mwe) in the Frejus tunnel (French Alps) has recorded 80 880 single muon and 2 322 multi-muon events between March '84 and March '85 (6425 hours of active time). During this period, a part of this modular detector was running, while new modules were being mounted, so that the detector size has continuously increased. The final detector has been completed in May '85

COURANTS NEUTRES ET CHARME DANS LES INTERACTIONS DE NEUTRINOS

Depuis quatre ans, la Physique du Neutrino a connu deux développements importants : l'étude des processus dus aux courants neutres faibles et l'étude de la production de particules charmées par des neutrinos. Pour illustrer les progrès expérimentaux accomplis dans ces domaines jusqu'en juin 1977, nous présentons dans cet article quelques résultats choisis parmi les plus marquants

Collagen fiber network infiltration : permeability and capillary infiltration

International audienceIn dentin restoration, collagen fiber network infiltration is an issue. Using data from the litterature, we have constructed a relevant numerical geometrical model of the network. The specificity of our model is that the fibers are taken into account implicitly using a regularized Heaviside function. This function is either used to set the viscosity or to localize the contact line where capillary forces are applied. A level set technique with respect to fluid infiltration front tracking in five fiber networks using the level set method and Navier-Stokes equations with capillary terms is used to point out efficient critical infiltration parameters. A variational formulation which can be implemented in FEM is proposed both for the infiltration front and the contact line. Because of lack of knowledge on fiber orientation, different configurations were tested through permeability assessment of the whole network. Fiber orientation, interfibrillar space and contact angle influence were investigated

Le processus de professionnalisation des étudiants des écoles de l’enseignement supérieur agricole

Le réseau « Egalité des Chances entre les femmes et les hommes » de l’enseignement supérieur agricole a initiée en 2005, dans un contexte de féminisation croissante de ses effectifs, une étude visant à mieux comprendre les choix d’orientation et motivation des étudiants et la construction progressive de leur identité professionnelle. On cherche en particulier à dégager des informations sur le rôle de la formation dans l’avenir des jeunes diplômés/es en s’intéressant aux différences sexuées d’aspiration et d’orientation professionnelles ainsi qu’à l’évolution de ces choix en cours de formation

Lognormal variability in BL Lacertae

X-ray data from the blazar BL Lac are used to investigate the nature of its variability, and more precisely the flux dependency of the variability and the distribution of fluxes. The variations in the flux are found to have a lognormal distribution and the average amplitude of variability is proportional to the flux level. BL Lac is the first blazar in which lognormal X-ray variability is clearly detected. Lognormal variability in X-ray light curves, probably related to accretion disk activity, has been discovered in various compact systems, such as Seyfert galaxies and X-ray binaries. The light curve is orders of magnitude less variable than other blazars, with few bursting episodes. If this defines a specific state of the source, then the lognormality might be the imprint of the accretion disk on the jet, linking for the first time accretion and jet properties in a blazar.Comment: Accepted for Astronomy & Astrophysic

Mikroleakage of Sealants Placed After Enamel Treatment With Self Etching Adhesive

Samojetkajući adhezivni sustavi istodobno s jetkanjem omogućuju penetraciju adheziva u jetkanu površinu cakline. Važne prednosti uporabe smojetkajućih adhezivnih sustava u postupku pečaćenja kao zamjeni za klasično jetkanje fosfornom kiselinom jesu: nema nanošenja kiseline i nema ispiranja. Svrha je istraživanja bila analizirati penetraciju i rubnu propustljivost pečata apliciranih nakon tretmana cakline samojetkajućim adhezivnim sustavom. 45 zuba podijelje nih u 3 skupine zapečaćeno je materijalom Concise White Sealant (3M Dental Products) nakon sljedećeg postupka pripreme površine cakline: Skupina 1: okluzalna površina jetkana je 37% fosfornom kiselinom 30 s, ispirana 15 s i sušena 15 s, nakon sušenja nanesen je materijal za pečaćenje i osvijetljen 20 s; skupina 2: Okluzalna površina tretirana je samojetkajućim adhezivnim sustavom Prompt- L-Pop (Espe Dental AG) 20 s i osvijetljen 10 s (Optilux, Demetron Research Company), materijal za pečaćenje zatim je nanesen i osvijetljen 20 s; skupina 3: Okluzalna površina tretirana ja samojetkajućim adhezivnim sustavom Prompt-L-Pop 20 s i odmah nakon tretmana nanesen je materijal za pečaćenje, oba materijala istodobno su osvijetljena 20 s. Svi su zubi termociklirani 1.800 ciklusa na temperaturi 5 - 55°C s 10 s imerzije u svakoj kupki. Rubna propustljivost ispitana je postupkom bojenja otopinom AgNO3. Zubi su uloženi u akrilnu smolu, prerezani (3-5 rezova po uzorku) i fotografirani pod 10 x povećanjem stereo mikroskopa. Rubna propustljivost mjerena je postupkom po Överböu i Raadalu. Statistička je rašlamba učinjena neparametrijskim testovima Kruskal-Wallis i Mann-Whitney. Penetracija materijala u dubinu fisura bila je između 87,8 - 92,1% bez statistički znatne razlike između skupina. Ustanovljena je statistički znatna razlika između klasičnoga postupka jetkanja i uporabe samojetkajućeg adhezivnog sustava (p = 0,003). Nije ustanovljena statistički znatna razlika u skupinama tretiranim samojetkajućim adhezivnim sustavom s polimerizacijom ili bez nje (p = 0,1234). Muguće je zaključiti da “all in one” samojetkajući adhezivni sustav Prompt-L-Pop nije tako djelotvoran kao kombinacija jetkanja fosfornom kiselinom i materijala za pečaćenje za dobivanje dobroga rubnog zatvaranja.Self-etching adhesives with enamel treatment at the same time as adhesive infiltration offers simplification of the classic technique of placing sealants. Main advantages in clinical work are: non need for applying acid, and no rinsing. Aim of the study was to evaluate both the penetration an sealing ability of a sealant applied after enamel treatment with a self-etching adhesive. The study was performed on forty-five teeth divided into three groups of fifteen teeth sealed with Concise White Sealant (3M Dental Products) after enamel surface was treated as fallows: Group 1: occlusal surface etched with 37% phosphoric acid for 30 s, rinsed for 15 s and air-dried for 15 s. After drying the sealant was applied and polymerized for 20 s. Group 2: The occlusal surface treated with self-etching adhesive Prompt-L-Pop (Espe Dental AG) for 20 s and lightened for 10 s (Optilux, Demetron Research Company). The sealant was then applied and lightened for 20 s. Group 3: The occlusal surface was treated with the selfetching adhesive Promt-L-Pop for 20 s and directly folloved by sealant application, the two materials were then simultaneously lightened 20 s. All teeth were thermocycled between 5 and 55°C for 1800 cycles with dwelling time of 10 s. AgNO3 dye solution was used for microleakage testing. After dyeing the teeth were embedded in acrylic resin, sectioned (3-5 sections per sample) and photographed under a stereo-microscope (10 X). Microleakage scores were recorded using the method of Övrebö and Raadal. Non-parametric Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis. The sealant penetration rate was between 87.8 - 92.1% whatever the batch with no statistical significant difference between groups. Significant statistical difference was established between the classic H3PO4 pre-etch technique and the self-etching conditioning (p = 0.003). No significant difference was found between self-etching batches with or without polymerisation (p = 0.1234). Obtained data lead to the conclusion that the “all in one” self-etching adhesive Prompt-L-Pop is not as efficient as the classic H3PO4 etching + sealant in achieving a good enamel marginal sealing

BeppoSAX Observations of Markarian 501 in June 1999

We present the preliminary results of a long BeppoSAX observation of the BL Lac object Mkn501 carried out in June 1999. The source was fainter than found during the BeppoSAX pointings of 1997 and 1998, but is still detected with a good signal-to-noise ratio up to ~40 keV. The X-ray spectrum in the energy range 0.1-40 keV, produced through synchrotron radiation, is steeper than in the previous years, it is clearly curved, and peaks (in nu*F_nu) at ~0.5 keV. This energy is much lower than those at which the synchrotron component was found to peak in 1997 and 1998. Some intraday variability suggests that activity of the source on small time scales accompanies the large long time scale changes of brightness and spectrum.Comment: 4 pages, Latex, 2 PostScript figures, to appear in the Proceedings of the Conference "X-ray Astronomy '999: Stellar Endpoints, AGNs, and the Diffuse X-ray Background" (Bologna, 6-10 September 1999

Searching for TeV dark matter by atmospheric Cerenkov techniques

There is a growing interest in the possibility that dark matter could be formed of weakly interacting particles with a mass in the 100 GeV - 2 TeV range, and supersymmetric particles are favorite candidates. If they constitute the dark halo of our Galaxy, their mutual annihilations produce energetic gamma rays that could be detected using existing atmospheric \u{C}erenkov techniques.Comment: 10 pp, LaTex (3 figures available by e-mail) PAR-LPTHE 92X

Construction of two large-size four-plane micromegas detectors

We report on the construction and initial performance studies of two micromegas detector quadruplets with an area of 0.5 m$^2$. They serve as prototypes for the planned upgrade project of the ATLAS muon system. Their design is based on the resistive-strip technology and thus renders the detectors spark tolerant. Each quadruplet comprises four detection layers with 1024 readout strips and a strip pitch of 415 $\mu$m. In two out of the four layers the strips are inclined by $\pm$1.5$^{\circ}$ to allow for the measurement of a second coordinate. We present the detector concept and report on the experience gained during the detector construction. In addition an evaluation of the detector performance with cosmic rays and test-beam data is given.Comment: 26 pages, 25 figure