487 research outputs found
Effect of CH4 addition on excess electron mobility in liquid Kr
No full textThe mobility μ of excess electrons has been measured in liquid mixtures of Kr and CH4 as a function of the electric field up to E~104 V/cm and of the CH4 concentration x up to x~10%, at a temperature T~125 K, fairly close to the normal boiling point of Kr (Tb~120 K) [Nucl. Instrum. Methods Phys. Res. A 430, 277 (1997)]. We present here new data extending the previous set in the low E region. At small E, μ appears to be quite independent of x. CH4 impurities prove to be less efficient in enhancing momentum transfer than liquified rare gas impurities Kr and Xe in liquid Ar. The dependence of μ on E at higher strengths is complicated. On the one hand, the addition of CH4 extends the range of E in which μ is field independent, by efficiently thermalizing the electrons. On the other hand, at the highest field, the presence of the impurities accomplishes a large increase of the electron drift velocity with respect to the pure liquid (up to a factor of 7 for the highest x). Moreover, at intermediate values of E, where electrons are epithermal, there appears to be a crossover between two different behaviors of μ as a function of E. The electric field strength at the crossover, E*, is well correlated with x. The behavior of μ can be rationalized in terms of a gas-kinetic model proposed to explain its concentration dependence in the liquified rare gas mixtures Ar-Kr and Ar-Xe. This analysis suggests that the observed crossover is related to the excitation of the first vibrational level of CH4
Identification of polymorphisms in the rabbit melanocortin 4 receptor gene and association with finishing weight in a commercial rabbit population
No full textMelanocortin 4 receptor (MC4R) is a member of the G proteincoupled receptor (GPCR) superfamily consisting of seven transmembrane domains with an extracellular NH2 tail and an intracellular COOH terminus. MC4R is mainly expressed in the hypothalamus in which plays a key role in controlling energy homeostasis and food intake with effects on body weight and fat deposition. Polymorphisms in the melanocortin 4 receptor (MC4R) gene have been already associated with growth performance in different species, like pigs, cattle, sheep and chicken and in humans several mutations cause severe obesity. For these reasons MC4R can be considered a candidate gene to identify markers associated with production traits in rabbits. In this study we resequenced 1729 bp of the MC4R gene in 31 rabbits from different breeds and lines and identified ten polymorphisms: one was a missense mutation (p.G34D), located in a conserved position of the extracellular tail of the MC4R protein. The missense mutation was genotyped in 516 performance tested rabbits of a commercial paternal line under selection for growth efficiency. Association analysis indicated that rabbits with the less frequent genotype in this population (DD) had a lighter weight at 70 postnatal days than animals with genotype GD (P<0.10) and animals with genotype GG (P<0.05). This result may confirm the important roles of variability in the MC4R gene in affecting growth and related traits across species
Particle identification in a LKr ionization chamber by multiple induced current measurements using the shape analysis of the signal
No full textCharged particle (π/K) separation in the momentum range 0.5-0.7 GeV/c using a new method of shape analysis of the signal from a liquid krypton ionization chamber has been studied experimentally. The detector has been exposed to pions and protons at the T11 test beam at CERN PS. The shape of preamplifier output signal has been recorded by a waveform digitizer and differentiated to obtain multiple measurements of induced current inside a 2 cm gap. Results on particle separation are presented and compared with a Monte Carlo simulation
Malignant vasovagal syncope: A randomised trial of metoprolol and clonidine
No full textObjective-To evaluate the efficacy of head up tilt guided treatment with metoprolol and clonidine in preventing the recurrence of syncope in patients with malignant vasovagal syncope. Patients-20 patients (9 men and 11 women, mean age 33 (SD 17), range 14 to 62 years) with severe symptoms. Design-Randomised double blind cross-over trial; efficacy was assessed by head up tilt testing. Results-Metoprolol was more effective than clonidine in abolishing syncope (19/20 v 1/20, P < 0.001) but clonidine showed some beneficial effects on time to syncope and severity of hypotension in 12 patients. During an average follow up of 15 (3) months there was a significant reduction in the recurrence of symptoms compared with the previous year in patients who had tilt up guided treatment (18 metoprolol, 1 clonidine). Conclusions-Treatment guided by head up tilting is a reliable method of treating patients with malignant vasovagal syndrome. Metoprolol was an effective long term treatment for preventing syncope. High doses were more effective and a careful dose titration period helped to minimise withdrawal symptoms and side effects
A Wide band photon beam at the Fermilab Tevatron to study heavy flavors.
No full textE687 COLLABORATIO
A Measurement of elastic J / psi photoproduction cross-section at fermilab E687.
No full textE687 COLLABORATIO
L'evoluzione delleprocedure di sanificazione negli ospedali: prospettive di riduzione e controlo della carica batterica potenzialmente atogena mediante tecniche di biostabilizzazione
No full textNella memoria vengono esposti i risultati di ricerche sperimentali condotte negli anni 2010-2011 e tuttora in corso, inerenti all’impiego di procedure di pulizia/sanificazione di superfici di diverso tipo di aree ospedaliere (pavimenti, apparecchi sanitari e arredi) mediante “tecniche di biostabilizzazione” della carica potenzialmente patogena. Tali tecniche vengono perseguite mediante l’utilizzo di prodotti probiotici (Bacillus spp. sotto forma vegetativa e sporigena), in grado di colonizzare le superfici su cui vengono applicati, contrastando la proliferazione delle altre specie batteriche e/o funginee, in accordo con la legge di Gause. Lo studio si pone l’obiettivo di verificare, sotto il profilo quali quantitativo sia in vitro che in campo, l’azione di tali prodotti rispetto all’impiego di trattamenti tradizionali a base di disinfettanti chimici. I risultati ottenuti dimostrano che con le nuove metodologie si ottiene una riduzione della carica di Stafilococcus aureus, Pseudomonas species, coliformi (compreso Escherichia Coli), Candida Albicans e Acinetobacter spp. di oltre l’80 % rispetto ai valori ottenibili mediante tecniche tradizionali di disinfezione chimica. Inoltre, mentre in quest’ultimo caso si verificano, nell’arco delle 24 ore, oscillazioni molto elevate della carica batterica superficiale potenzialmente patogena, i prodotti probiotici garantiscono un valore più costante del numero delle unità formanti colonie dei medesimi microrganismi per l’intera giornata. Questi risultati aprono nuovi scenari al problema della valutazione della efficacia delle procedure di pulizia in ambienti ospedalieri (e non), che mostrano i seri limiti delle attuali metodologie correntemente in uso
Sperimentazione di tecniche di biostabilizzazione nelle procedure di sanificazione di degenze ospedaliere
No full textNella memoria vengono esposti i risultati di una ricerca sperimentale inerente all’impiego di nuove metodologie di pulizia/sanificazione di superfici di diverso tipo appartenenti ad aree ospedaliere (pavimenti, apparecchi sanitari e arredi), basate su “tecniche di biostabilizzazione” della carica potenzialmente patogena, perseguite mediante l’utilizzo di prodotti probiotici (Bacillus spp. sotto forma vegetativa e sporigena). Il principio di azione consiste nel fatto che tali microrganismi sono in grado di colonizzare le superfici su cui vengono applicati, contrastando la proliferazione delle altre specie batteriche e/o funginee in accordo con la legge di Gause. Lo studio si poneva l’obiettivo di verificare, sotto il profilo quali quantitativo sia in vitro che in campo, l’azione di tali prodotti rispetto all’impiego di trattamenti tradizionali a base di disinfettanti chimici. I risultati ottenuti dimostrano che con le nuove metodologie si ottiene una riduzione della carica di Stafilococcus aureus, Pseudomonas species, coliformi (compreso Escherichia Coli), Candida Albicans e Acinetobacter spp. di oltre l’80 % rispetto ai valori ottenibili mediante tecniche tradizionali di disinfezione chimica
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