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F Minardi

Publications and source records attributed to F Minardi.

13 recordsLinked to original sources
PubMed2001

Josephson junction arrays with Bose-Einstein condensates.

We report on the direct observation of an oscillating atomic current in a one-dimensional array of Josephson junctions realized with an atomic Bose-Einstein condensate. The array is created by a laser standing wave, with the condensates trapped in the valleys of the periodic potential and weakly coupled by the interwell barriers. The coherence of multiple tunneling between adjacent wells is continuously probed by atomic interference. The square of the small-amplitude oscillation frequency is proportional to the microscopic tunneling rate of each condensate through the barriers and provides a direct measurement of the Josephson critical current as a function of the intermediate barrier heights. Our superfluid array may allow investigation of phenomena so far inaccessible to superconducting Josephson junctions and lays a bridge between the condensate dynamics and the physics of discrete nonlinear media.

Journal Article↗
PubMed2001

Superfluid and dissipative dynamics of a Bose-Einstein condensate in a periodic optical potential.

We create Bose-Einstein condensates of 87Rb in a static magnetic trap with a superimposed blue-detuned 1D optical lattice. By displacing the magnetic trap center we are able to control the condensate evolution. We observe a change in the frequency of the center-of-mass oscillation in the harmonic trapping potential, in analogy with an increase in effective mass. For fluid velocities greater than a local speed of sound, we observe the onset of dissipative processes up to full removal of the superfluid component. A parallel simulation study visualizes the dynamics of the Bose-Einstein condensate and accounts for the main features of the observed behavior.

Journal Article↗
PubMed2000

Collective oscillations of two colliding bose-einstein condensates

Two 87Rb condensates ( F = 2, m(f) = 2, and m(f) = 1) are produced in highly displaced harmonic traps and the collective dynamical behavior is investigated. The mutual interaction between the two condensates is evidenced in the center-of-mass oscillations as a frequency shift of 6.4(3)%. Calculations based on a mean-field theory well describe the observed effects of periodical collisions both on the center-of-mass motion and on the shape oscillations.

Journal Article↗
PubMed1999

Mega-experiments to identify and assess diffuse carcinogenic risks.

Diffuse carcinogenic risks, that is, those of low potency involving large areas of population and sometimes all mankind, pose a serious public health problem. Controlling these risks might help to reduce the incidence of, and mortality from, cancer. Because of their low expected carcinogenic potential, these risks are difficult to expose or assess. Epidemiologic investigation is of limited use in this field and yields its data too late to be useful. Experimental studies offer the only possible approach for assessing such risks. To increase experimental sensitivity and consistency of results, mega-experiments must be designed. That is, experiments that use a large number of animals with a well-known basic tumorigram, that extend the exposure and the biophase for as long as possible, that carefully observe the effects, and that are performed with suitable standardized methods. In the last 15 years the Ramazzini Foundation, in its Cancer Research Center at Bentivoglio, has conducted or planned five mega-experiments. Initial results indicate the great potential of these methods for identifying and assessing diffuse risks.

Carcinogens↗
PubMed1997

Results of three life-span experimental carcinogenicity and anticarcinogenicity studies on tamoxifen in rats.

Tamoxifen was submitted to carcinogenicity bioassays on Sprague-Dawley rats (of the colony used at the Cancer Research Center in the Castle of Bentivoglio of the European Ramazzini Foundation of Oncology and Environmental Sciences) at the dose of 3.3 mg/kg b.w., by stomach tube, in three experiments. In the first experiment the drug was administered once daily, 6 days a week to male and female rats, 8 weeks old at start for their life span. In the second experiment, the drug was administered to female rats, 12 weeks old at start, once daily for 8 consecutive days every 8 weeks for their life span. In the third experiment the drug was administered to female rats, 56 weeks old at start, 6 times weekly for 40 weeks; and then the animals were kept alive for their life span. In the first experiment, a mild increase in hepatocarcinomas with low grading was detected. In the first and second experiments, a borderline increase in uterine malignancies was found. No carcinogenic effect was observed in the third experiment. In the three experiments, tamoxifen showed a strong, long-lasting chemopreventive effect on mammary benign tumors and cancers. The presented data also indicate that tamoxifen treatment reduces the incidence of other tumors: pituitary adenomas, adrenal pheochromocytomas, islet cell pancreatic tumors, Leydig cell testicular tumors, and polyps of the uterus.

Animals↗
PubMed1989

Recent results of carcinogenicity bioassays of fibres and other particulate materials.

Different types of natural, commercial and modified asbestos fibres were tested in a highly standardized manner by peritoneal injection into rats and mice in order to assess their carcinogenicity. Differences in mesotheliomatogenic effect were found between the various materials tested. Of particular interest is the finding that treatment of the fibres with phosphorus oxychloride and heating to 300 degrees C markedly reduces the carcinogenicity of chrysotile fibres.

Animals↗
PubMed1988

Results of recent experimental research on the carcinogenicity of natural and modified asbestos.

Long-term experimental bioassays were carried out on natural asbestos of different types and origin (crocidolite, chrysotile, amosite, antophyllite), on asbestos cement, and on industrially modified chrysotiles. The materials were tested on Sprague-Dawley rats by intraperitoneal and intrapleural injection. The experiments were carried out with highly standardized procedures on all materials to enable comparative evaluation of the results. The data presented confirm that asbestos of different types produces peritoneal and pleural mesotheliomas, show that asbestos cement is also mesotheliomatogenic, and demonstrate that the peritoneum is more responsive than the pleura. Furthermore, evidence is provided that the mesotheliomatogenic effects of different types of asbestos vary with the types and origin of the minerals, and that physical and chemical modifications of the natural chrysotile can lower its carcinogenic effect.

Administration, Inhalation↗
PubMed1988

First available results of long-term carcinogenicity bioassay on detergency zeolites (MS 4A and MS 5A).

Long-term experimental carcinogenicity bioassay was carried out on MS 4A and MS 5A zeolites. The materials were tested on Sprague-Dawley rats by intraperitoneal, intrapleural, and subcutaneous injection of 25 mg in 1 ml of H2O. The results of this bioassay (the onset of one peritoneal mesothelioma in a male rat treated by intraperitoneal injection of zeolite MS 4A) calls for further and more sophisticated tests on zeolites used as detergents.

Aluminum Silicates↗
PubMedDate not supplied

Long-term carcinogenicity bioassays on industrial chemicals and man-made mineral fibers, at the Bentivoglio (BT) laboratories of the Bologna Institute of Oncology: premises, programs, and results.

After having stressed the need of primary prevention in the strategy for cancer control, the crucial role of the long-term carcinogenicity bioassays in providing scientific support to primary prevention has been focused. The state-of-the-art, the present inadequacies, the necessity of implementation, and the perspectives of the long-term carcinogenicity bioassays have been briefly reviewed. The performed and ongoing programs of carcinogenicity bioassays at the Bentivoglio (BT) Laboratories of the Bologna Institute of Oncology have been presented, together with the currently available results on several compounds of industrial and commercial relevance.

Biological Assay↗
PubMedDate not supplied

Mesotheliomas following exposure to asbestos used in sugar refineries: report of 12 Italian cases.

Twelve Italian cases of mesothelioma (all the cases but one from the Emilia Romagna Region), following exposure to asbestos used in sugar refinery plants, are reported. Eleven cases arose in workers occupationally exposed, and one in the daughter of an exposed worker, following family contact. Eleven of the cases were pleural and one peritoneal. In the 11 cases following occupational exposure the average latency time was 36.0 (range 23-48) years, and the average age at onset was 63.4 years. In the case which followed family contact, the latency time and the age of the onset were 37 years. This represents the largest series of cases of mesothelioma due to the asbestos present in sugar refinery plants reported to date in the scientific literature. While these cases demonstrate the risk of asbestos mesothelioma in the sugar refinery industry, they in no way give the dimension of the pathological effects of asbestos (and man-made mineral fibres) used in this industry. To assess this risk further research is suggested.

Adult↗