Collective ion dynamics in liquid zinc: evidence for complex dynamics in a non-free-electron liquid metal.

A detailed inelastic neutron scattering investigation of the THz dynamics of liquid zinc is presented. The observed Q dependence clearly reveals the existence of a complex dynamics made up of two distinct excitations. The highest energy mode is the prolongation of the longitudinal acoustic density fluctuations whereas the comparison with the phonon dynamics of crystalline hcp zinc suggests a transverse acousticlike nature for the second one. This mode seems related to peculiar anisotropic interactions, possibly connected to the behavior of the crystalline phase.

Water dynamics in a lithium chloride aqueous solution probed by Brillouin neutron and x-ray scattering.

We studied the collective excitations in an aqueous solution of lithium chloride over the temperature range of 270-205 K using neutron and x-ray Brillouin scattering. Both neutron and x-ray experiments revealed the presence of low- and high-frequency excitations, similar to the low- and high-frequency excitations in pure water. These two excitations were detectable through the entire temperature range of the experiment, at all probed values of the scattering momentum transfer (0.2 Å(-1) < Q < 1.8 Å(-1)). A wider temperature range was investigated using elastic intensity neutron and x-ray scans. Clear evidence of the crossover in the dynamics of the water molecules in the solution was observed in the single-particle relaxational dynamics on the µeV (nanosecond) time scale, but not in the collective dynamics on the meV (picosecond) time scale.

Tactile spatial working memory activates the dorsal extrastriate cortical pathway in congenitally blind individuals.

In sighted individuals, both the visual and tactile version of the same spatial working memory task elicited neural responses in the dorsal "where" cortical pathway (Ricciardi et al., 2006). Whether the neural response during the tactile working memory task is due to visually-based spatial imagery or rather reflects a more abstract, supramodal organization of the dorsal cortical pathway remains to be determined. To understand the role of visual experience on the functional organization of the dorsal cortical stream, using functional magnetic resonance imaging (fMRI) here we examined brain response in four individuals with congenital or early blindness and no visual recollection, while they performed the same tactile spatial working memory task, a one-back recognition of 2D and 3D matrices. The blind subjects showed a significant activation in bilateral posterior parietal cortex, dorsolateral and inferior prefrontal areas, precuneus, lateral occipital cortex, and cerebellum. Thus, dorsal occipito-parietal areas are involved in mental imagery dealing with spatial components in subjects without prior visual experience and in response to a non-visual task. These data indicate that recruitment of the dorsal cortical pathway in response to the tactile spatial working memory task is not mediated by visually-based imagery and that visual experience is not a prerequisite for the development of a more abstract functional organization of the dorsal stream. These findings, along with previous data indicating a similar supramodal functional organization within the ventral cortical pathway and the motion processing brain regions, may contribute to explain how individuals who are born deprived of sight are able to interact effectively with the surrounding world.

Neural correlates of spatial working memory in humans: a functional magnetic resonance imaging study comparing visual and tactile processes.

Recent studies of neural correlates of working memory components have identified both low-level perceptual processes and higher-order supramodal mechanisms through which sensory information can be integrated and manipulated. In addition to the primary sensory cortices, working memory relies on a widely distributed neural system of higher-order association areas that includes posterior parietal and occipital areas, and on prefrontal cortex for maintaining and manipulating information. The present study was designed to determine brain patterns of neural response to the same spatial working memory task presented either visually or in a tactile format, and to evaluate the relationship between spatial processing in the visual and tactile sensory modalities. Brain activity during visual and tactile spatial working memory tasks was measured in six young right-handed healthy male volunteers by using functional magnetic resonance imaging. Results indicated that similar fronto-parietal networks were recruited during spatial information processing across the two sensory modalities-specifically the posterior parietal cortex, the dorsolateral prefrontal cortex and the anterior cingulate cortex. These findings provide a neurobiological support to behavioral observations by indicating that common cerebral regions subserve generation of higher order mental representations involved in working memory independently from a specific sensory modality.

Chronic cryptosporidiosis in patients with AIDS: stable remission and possible eradication after long-term, low dose azithromycin.

AIMS: To investigate the effectiveness of long term, low dose azithromycin treatment for chronic cryptosporidiosis in patients with AIDS. METHODS: Azithromycin was administered as initial daily treatment to 13 patients with AIDS: 6 patients received 500 mg for 30 to 40 days (mean 35); 3 patients received 1000 mg for 21 to 50 days (mean 37); and 4 patients received 1500 mg for 20 days. Nine of the 13 patients were also given low dose maintenance treatment with different schedules of azithromycin for 30 to 360 days (mean 129). Patients were monitored, during and after treatment, for parasite shedding in stool and for daily stool frequency and body weight. All but one patient had severe immunodeficiency. RESULTS: Long term, low dose maintenance treatment was associated with major clinical and parasitological benefits: there was probable eradication of infection in 2 patients, and 7 patients showed a complete response with persistent high decrease (5 patients) or clearance (2 patients) of parasite in stool. The drug was well tolerated, and there was no relapse either during treatment or during follow up (up to 21 months). These results were more impressive than those observed after the short term initial course of azithromycin, which was unable at any tested dose to achieve parasite clearance in stool (except in the patient with less advanced immunodeficiency) or to prevent relapse in 3 patients who discontinued treatment. Reversible side effects occurred with the 1500 mg daily dose. CONCLUSIONS: Long term, low dose azithromycin is well tolerated and may induce stable remission of chronic cryptosporidiosis in patients with AIDS. It may lead to probable eradication of the infection in some patients, even those with severe immunodeficiency.

Type A behaviour pattern and traffic accidents.

This study examines the possible relationship between Type A behaviour pattern (TABP) and traffic accident risk in a cohort of traffic policemen. Data were gathered from 86 police drivers from a small Italian town, using the Bortner questionnaire. Results reveal that police drivers with Type A behaviour had higher traffic accident risk than those with lower scores at the Bortner scale. Adjusted odds ratio was 4.2 (95 per cent CI: 1.17-15.17) after correction for confounding variables in multiple logistic regression.

[Role of slime in the pathogenesis of pulmonary infections]. / Ruolo dello slime nella patogenesi delle infezioni polmonari.

Microorganisms have proved to produce an amorphous substance that adheres to surfaces of several medical devices like intravenous catheters and endotracheal tubes. We investigated the presence of slime in endotracheal tubes in our Intensive Care Unit (ICU) in 12 patients. We found in this study no correlation between the strain of bacteria on the surface of endotracheal devices and those responsible for pneumonia.

[Eye diseases in welders: a longitudinal study]. / Affezioni oculari nei saldatori: uno studio longitudinale.

A follow-up study of chronic conjunctivitis in arc welders in a foundry in Italy was conducted from 1979 up to 1989. Airborne dust concentration in the foundry often exceeded the TLV-TWA limit. The frequency of chronic conjunctivitis was markedly higher amongst the welders than in the unexposed controls (RR = 4.25). The incidence rate of conjunctivitis was 49.8% in the exposed group; manual welders showed a higher incidence rate (56.9%) than non manual welders (risk ratio = 1.76). Ocular symptoms (eye burning, tearing, photophobia) often occurred largely before the development of chronic conjunctivitis (predictive value = 61.5%). In current occupational health practice, the disclosure of a high prevalence of ocular symptoms should lead to careful examination of the working environment.

Arterial hypertension and noise: a cross-sectional study.

The occurrence of permanent arterial hypertension was studied among the workers of a textile plant (490 subjects) exposed to high frequency noise, at levels often exceeding 100 dBA. The prevalence of the disease among these workers was compared to that observed in a reference series (450 subjects). A prevalence rate ratio equal to 1.34 (1.14-1.57) was estimated, taking into account several determinants of disease acting as confounding factors in the study. The results, which are in good agreement with those obtained in similar studies, are discussed.