Triple-ionised carbon associated with the low-density neutral hydrogen gas at 1.7 < z < 3.3: the integrated N(HI)-N(CIV) relation

From the Voigt profile fitting analysis of 183 intervening CIV systems at 1.7 < z < 3.3 in 23 high-quality UVES/VLT and HIRES/Keck QSO spectra, we find that a majority of CIV systems (~75%) display a well-characterised scaling relation between integrated column densities of HI and CIV with a negligible redshift evolution, when column densities of all the HI and CIV components are integrated within a given (-150, +150) km/sec range centred at the CIV flux minimum. The integrated CIV column density N(CIV, sys) increases with N(HI, sys) at log N(HI, sys) = 14.0--15.5 and log N(CIV, sys) = 11.8--14.0, then becomes almost independent of N(HI, sys) at log N(HI, sys) > 16, with a large scatter: at log N(HI, sys) = 14--22, log N(CIV, sys) = C1 / (log(NHI, sys) + C2) + C3, with C1 = -1.90+0.55, C2 = -14.11+0.19 and C3 = 14.76+0.17, respectively. The steep (flat) part is dominated by SiIV-free (SiIV-enriched) CIV systems. Extrapolating the N(HI, sys)-N(CIV, sys) relation implies that most absorbers with log N(HI) < 14 are virtually CIV-free. The N(HI, sys)-N(CIV, sys) relation does not hold for individual components, clumps or the integration velocity range less than +-100 km/sec. It is expected if the line-of-sight extent of CIV is smaller than HI and N(CIV, sys) decreases more rapidly than N(HI, sys) at the larger impact parameter, regardless of the location of the HI+CIV gas in the IGM filaments or in the intervening galactic halos.Comment: Accepted for publication on MNRAS, 26 pages, 20 figures, 4 tables. On-line materials are found in the submitted civ.tar.gz file: complete Table 2, complete Table 3, complete Table 4, velocity plots civ1.pdf, civ2.pdf, civ3.pdf, civ4.pdf and civ5.pd

Software Model Checking with Explicit Scheduler and Symbolic Threads

In many practical application domains, the software is organized into a set of threads, whose activation is exclusive and controlled by a cooperative scheduling policy: threads execute, without any interruption, until they either terminate or yield the control explicitly to the scheduler. The formal verification of such software poses significant challenges. On the one side, each thread may have infinite state space, and might call for abstraction. On the other side, the scheduling policy is often important for correctness, and an approach based on abstracting the scheduler may result in loss of precision and false positives. Unfortunately, the translation of the problem into a purely sequential software model checking problem turns out to be highly inefficient for the available technologies. We propose a software model checking technique that exploits the intrinsic structure of these programs. Each thread is translated into a separate sequential program and explored symbolically with lazy abstraction, while the overall verification is orchestrated by the direct execution of the scheduler. The approach is optimized by filtering the exploration of the scheduler with the integration of partial-order reduction. The technique, called ESST (Explicit Scheduler, Symbolic Threads) has been implemented and experimentally evaluated on a significant set of benchmarks. The results demonstrate that ESST technique is way more effective than software model checking applied to the sequentialized programs, and that partial-order reduction can lead to further performance improvements.Comment: 40 pages, 10 figures, accepted for publication in journal of logical methods in computer scienc

Characterization of sheep (Ovis aries) palatine tonsil innervation

Palatine tonsils (PTs), together with ileal Peyer's patches, rank among the first colonization sites for infectious prions. After replicating in these lymphoid tissues, prions undertake the process of "neuroinvasion," which is likely mediated by the peripheral nerves connecting lymphoid tissues to the central nervous system (CNS). To study the connections between the tonsils and the CNS, we injected fluorescent tracers into the PTs of lambs; the highest number of Fast Blue (FB)-labeled neurons was found in cranial cervical ganglia (CCG), whereas a progressively decreasing number of cells were detected in proximal glossopharyngeal, proximal vagal, trigeminal, pterygopalatine, and cervicothoracic ganglia. Immunohistochemistry was carried out on tonsil and ganglia cryosections. Immunoreactivity (IR) for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), neuronal nitric oxide synthase (nNOS), calcitonin gene-related peptide (CGRP), substance P (SP), and calcium-binding protein S100 (S100), was observed in the fibers around and within PT lymphoid nodules. In the trigeminal, proximal glossopharyngeal and vagal ganglia the retrogradely-labeled neurons showed nNOS-, SP- and CGRP-IR. In all ganglia some retrogradely-labeled neurons showed nNOS-, SP- and CGRP-IR co-localization. It is worth noting that only 66+/-19% and 75+/-13% of retrogradely-labeled neurons in CCG showed TH- and DBH-IR, respectively. The present results allow us to attribute PT innervation mainly to the sympathetic component and to the glossopharyngeal, vagal and trigeminal cranial nerves. Furthermore, these data also provide a plausible anatomic route through which infectious agents, such as prions, may access the CNS, i.e. by traveling along several cranial and sympathetic nerves, as well as by migration via glial cells.[...

Automatic environmental disinfection with hydrogen peroxide and silver ions versus manual environmental disinfection with sodium hypochlorite: A multicentre randomized before-and-after trial.

BACKGROUND: New technologies for automated disinfection have been developed, including the use of hydrogen peroxide atomized by specific equipment, with associated silver compounds. AIMS: To compare the effectiveness of an automated disinfection system with hydrogen peroxide <8% and silver ion versus a manual method with 0.5% sodium hypochlorite solution when evaluating the reduction of microbial mesophilic contamination and Clostridium difficile presence; and to evaluate the time required for both of these processes. METHODS: This was a randomized multicentre trial performed in different hospital wards that had been occupied previously by patients with Clostridium difficile infection. When patients were discharged their rooms were randomized to one of two decontamination arms. The surfaces where sampled using swabs, before and after disinfection. Swab samples were cultured for quantitative detection of microbial mesophilic contamination and qualitative detection of C. difficile. FINDINGS: Before disinfection, 13% of surfaces decontaminated with hydrogen peroxide and silver ions and 20% of surfaces decontaminated with sodium hypochlorite showed presence of C. difficile spores. After disinfection, the samples containing C. difficile were 0% (P < 0.001) in the group decontaminated with hydrogen peroxide and silver ions, and were 3% (P < 0.001) in the group decontaminated with sodium hypochlorite. This difference was not statistically significant; nor was the difference in the reduction of the microbial mesophilic contamination. CONCLUSION: The differences between the groups were not statistically significant; however, the disinfection with hydrogen peroxide and silver ions is preferable due to less dependence on operators

Innervazione delle tonsille palatine nella pecora

Palatine tonsils (PTs) are replication sites for infectious prions (PrPSc). From the PTs PrPSc take part to neuroinvasion. To study the connections between PTs, central and peripheral nervous system, we injected in the lamb PTs the tracer Fast Blue (FB). FB-labelled neurons were observed in the sympathetic cervical cranial ganglia (CCG), vagal and glossopharingeal ganglia, and trigeminal ganglia (TG). Immunohistochemistry was performed on PTs and ganglia cryosections. FB-labeled sensory neurons expressed NOS-, CGRP-, and SPIR. CCG FB-labeled neurons expressed DBH-IR, but FB-labeled neurons DBH-negative were also observed. The present results provide a plausible anatomic basis through which infectious prions may gain access to the CNS. Immunoreactivity for dopamine-beta-hydroxylase (DBH), nitric oxide synthase (NOS), calcitonin gene-related peptide (CGRP), and substance P (SP) was observed in PTs fibres