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A Ferrari

Publications and source records attributed to A Ferrari.

At least 37 records · Page 2Linked to original sources
PubMed2005

FLUKA simulation of TEPC response to cosmic radiation.

The aircrew exposure to cosmic radiation can be assessed by calculation with codes validated by measurements. However, the relationship between doses in the free atmosphere, as calculated by the codes and from results of measurements performed within the aircraft, is still unclear. The response of a tissue-equivalent proportional counter (TEPC) has already been simulated successfully by the Monte Carlo transport code FLUKA. Absorbed dose rate and ambient dose equivalent rate distributions as functions of lineal energy have been simulated for several reference sources and mixed radiation fields. The agreement between simulation and measurements has been well demonstrated. In order to evaluate the influence of aircraft structures on aircrew exposure assessment, the response of TEPC in the free atmosphere and on-board is now simulated. The calculated results are discussed and compared with other calculations and measurements.

Aerospace Medicine↗
PubMed2005

Review article: chronic hepatitis C--natural history and cofactors.

Chronic hepatitis C is highly heterogeneous in clinical presentation and outcomes. This heterogeneity is largely related to host factors that have been clearly proven to affect the severity and rapidity of disease progression. The most relevant factors that have been shown to accelerate progression to cirrhosis include age at infection, alcohol abuse and the metabolic syndrome with insulin resistance, obesity and hepatic steatosis. Co-infection with HIV and/or HBV also increases the risk of progression to cirrhosis and to hepatocellular carcinoma. Surprisingly enough, viral related factors appear as less important and neither the virus genotype and load have been found to exert a clear influence on disease severity and progression, although more data in this field, and particularly on the role of different viral proteins in causing cytopathic effects, are awaited and may change this view in the near future.

Age Factors↗
PubMed2005

Serum progesterone at human chorionic gonadotropin injection significantly correlate with female age.

AIM: In in vitro fertilization-embryo transfer (IVF-ET) higher age and low responses are associated with accelerated luteinization of mature follicles rather than diminished responsiveness. The aim of this study was to determine whether an elevated serum progesterone (P) on the day of human chorionic gonadotropin (hCG) administration during gonadotropin stimulation for IVF-ET is associated with age. METHODS: E2 (17beta estradiol) and P concentrations on the day of hCG administration, number and quality of oocytes and embryos, and clinical pregnancies were retrospectively analyzed in 460 women undergoing IVF-ET. We evaluated patients according to age; the 25-30 age group (n=140), the 31-35 age group (n=100), the 36-40 (n=90), and the 41-45 age group (n=130). RESULTS: In the 25-30 age group (n=140) P was 0.67+/-0.3 ng/mL, in the 31-35 age group (n=100) P was 0.87+/-0.2 ng/mL, in the 36-40 age group (n=90) P was 0.95+/-0.2 ng/mL, in the 41-45 age group (n=130) P was 1+/-0.2 ng/mL. The difference between the 25-30 age group and the 41-45 age group was statistically significant (P<0.05). CONCLUSIONS: Periovulatory levels of serum P vary according to ovarian response to controlled ovarian hyperstimulation. Periovulatory P may reflect inadequate steroidogenesis. In women stimulated with recombinant follicle stimulating hormone for IVF, the serum P on the day of hCG administration increases with age.

Adult↗
PubMed2004

Monte Carlo calculation of the angular distribution of cosmic rays at flight altitudes.

The angular distribution of the secondary radiation produced by the galactic component of cosmic rays has been determined by simulating the penetration of the primary spectra in the Earth's atmosphere. The simulations have been carried out with the latest version of the FLUKA code. Particles have been scored at various altitudes according to their angle of incidence for some significant values of vertical cut-off rigidity and solar modulation parameter. The calculated results at typical cruise altitudes for a civil aircraft are presented. The data at 10.7 km have been fitted with simple mathematical equations. It has been demonstrated that the major contribution to the doses at aviation altitudes arises from downward-directed particles. The isotropic irradiation usually assumed for the evaluation of aircrew exposure could be a very poor approximation.

Aircraft↗
PubMed2004

Neutron capture cross section measurement of 151Sm at the CERN neutron time of flight facility (n_TOF).

The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant branch stars. At a thermal energy of kT=30 keV the Maxwellian averaged cross section of this unstable isotope (t(1/2)=93 yr) was determined to be 3100+/-160 mb, significantly larger than theoretical predictions.

Journal Article↗
PubMed2004

The FLUKA code for space applications: recent developments.

The FLUKA Monte Carlo transport code is widely used for fundamental research, radioprotection and dosimetry, hybrid nuclear energy system and cosmic ray calculations. The validity of its physical models has been benchmarked against a variety of experimental data over a wide range of energies, ranging from accelerator data to cosmic ray showers in the earth atmosphere. The code is presently undergoing several developments in order to better fit the needs of space applications. The generation of particle spectra according to up-to-date cosmic ray data as well as the effect of the solar and geomagnetic modulation have been implemented and already successfully applied to a variety of problems. The implementation of suitable models for heavy ion nuclear interactions has reached an operational stage. At medium/high energy FLUKA is using the DPMJET model. The major task of incorporating heavy ion interactions from a few GeV/n down to the threshold for inelastic collisions is also progressing and promising results have been obtained using a modified version of the RQMD-2.4 code. This interim solution is now fully operational, while waiting for the development of new models based on the FLUKA hadron-nucleus interaction code, a newly developed QMD code, and the implementation of the Boltzmann master equation theory for low energy ion interactions.

Computer Simulation↗
PubMed2004

Role of shielding in modulating the effects of solar particle events: Monte Carlo calculation of absorbed dose and DNA complex lesions in different organs.

Distributions of absorbed dose and DNA clustered damage yields in various organs and tissues following the October 1989 solar particle event (SPE) were calculated by coupling the FLUKA Monte Carlo transport code with two anthropomorphic phantoms (a mathematical model and a voxel model), with the main aim of quantifying the role of the shielding features in modulating organ doses. The phantoms, which were assumed to be in deep space, were inserted into a shielding box of variable thickness and material and were irradiated with the proton spectra of the October 1989 event. Average numbers of DNA lesions per cell in different organs were calculated by adopting a technique already tested in previous works, consisting of integrating into "condensed-history" Monte Carlo transport codes--such as FLUKA--yields of radiobiological damage, either calculated with "event-by-event" track structure simulations, or taken from experimental works available in the literature. More specifically, the yields of "Complex Lesions" (or "CL", defined and calculated as a clustered DNA damage in a previous work) per unit dose and DNA mass (CL Gy-1 Da-1) due to the various beam components, including those derived from nuclear interactions with the shielding and the human body, were integrated in FLUKA. This provided spatial distributions of CL/cell yields in different organs, as well as distributions of absorbed doses. The contributions of primary protons and secondary hadrons were calculated separately, and the simulations were repeated for values of Al shielding thickness ranging between 1 and 20 g/cm2. Slight differences were found between the two phantom types. Skin and eye lenses were found to receive larger doses with respect to internal organs; however, shielding was more effective for skin and lenses. Secondary particles arising from nuclear interactions were found to have a minor role, although their relative contribution was found to be larger for the Complex Lesions than for the absorbed dose, due to their higher LET and thus higher biological effectiveness.

Astronauts↗
PubMed2004

Natural history of initially mild chronic hepatitis C.

The hepatitis C virus is a leading cause of chronic liver disease, cirrhosis and hepatocellular carcinoma in western countries. Chronic hepatitis C is highly heterogeneous and many patients present with a mild form of liver disease. Population-based studies have indeed demonstrated that around 50% of hepatitis C virus carriers have persistently normal ALT and two-third have mild histological liver lesions. Studies on the natural history of initially mild chronic disease indicate that the short-term outcome is always benign. However, progression of liver fibrosis can be observed at long-term (>5-7 years) follow-up, particularly in those cases who have elevated and/or fluctuating transaminase levels. Observational prospective studies and outcome modelling projections indicate that the risk of liver disease progression towards severe fibrosis/cirrhosis is minimal at 10-15 years in hepatitis C virus carriers with persistently normal ALT, around 5-10% in patients with elevated ALT and F0 (no fibrosis) in the initial biopsy but >30-40% in chronic carriers with elevated ALT and F1 (portal fibrosis) in the initial biopsy. Cofactors like age at infection, alcohol, coinfections and liver steatosis accelerate disease progression. On the basis of these findings, patients with initially mild chronic hepatitis C and elevated ALT should be proposed for antiviral therapy in the absence of contraindications.

Alanine Transaminase↗
PubMed2004

Tailored dialysis start may allow persistence of residual renal function after graft failure: a case report.

BACKGROUND: Restarting dialysis after kidney transplantation is a critical step with psychological and clinical implications. Maintenance of residual renal function a known factor affecting survival in chronic kidney disease, has so far not been investigated after a kidney transplantation. THE CASE: A 54-year-old woman who started dialysis in 1974 (first graft, 1975-1999) received a second "marginal" kidney graft in February 2001 (donor age, 65 years). Her chronic therapy was tacrolimus and steroids. She had a clinical history as follows: nadir creatinine level of 1.5 mg/dL, moderate-severe hypertension, progressive graft dysfunction, nonresponsiveness to addition of mycophenolate, tapering FK levels, and a rescue switch from tacrolimus to rapamycin. From October to December 2003, the creatinine level increased from 2-2.8 to 7 mg/dL. Biopsy specimen showed malignant and "benign" nephrosclerosis, posttransplantation glomerulopathy, and tacrolimus toxicity. Chronic dialysis was started (GFR <3 mL/min). Rapamycin was discontinued. Dialysis was tailored to reach an equivalent renal clearance of >15 mL/min (2 sessions/wk). Blood pressure control improved, nephrotoxic drugs were avoided, and fluid loss was minimized (maximum 500 mL/hr). By this policy, renal function progressively increased to GFR >10 mL/min in May 2004, allowing a once or twice weekly dialysis schedule, with good clinical balance, and obvious advantages for the quality of life. CONCLUSION: This long-term patient, who restarted dialysis with severely reduced renal function, regained sufficient renal function to allow once weekly dialysis. Thus, careful tailoring of dialysis sessions at the restart of dialysis may allow preservation of residual kidney function, at least in individuals for whom a subsequent graft is unlikely.

Female↗
PubMed2004

Evaluation of the influence of aircraft shielding on the aircrew exposure through an aircraft mathematical model.

In order to investigate the influence of aircraft shielding on the galactic component of cosmic rays, an aircraft mathematical model has been developed by the combinatorial geometry package of the Monte-Carlo transport code FLUKA. The isotropic irradiation of the aircraft in the cosmic ray environment has been simulated. Effective dose and ambient dose equivalent rates have been determined inside the aircraft at several locations along the fuselage, at a typical civil aviation altitude (10 580 m), for vertical cut-off rigidity of 0.4 GV (poles) and 17.6 GV (equator) and deceleration potential of 465 MV. The values of both quantities were generally lower than those in the free atmosphere. They depend, in an intricate manner, on the location within the aircraft, quantity of fuel, number of passengers, etc. The position onboard of crew members should be taken into account when assessing individual doses. Likewise due consideration must be taken when positioning detectors which are used to measure H*(10). Care would be needed to avoid ambiguity when comparing the results of calculation with the experimental data.

Aircraft↗
PubMed2004

Dosimetric considerations on TEPC fluka-simulation and measurements.

The response of a tissue equivalent proportional counter (TEPC) has been simulated with the Monte Carlo transport code FLUKA. The absorbed dose distribution of lineal energy y has been determined for several monoenergetic photon and neutron sources. The agreement between the calculated results and the measurements carried out with different well-known sources is well demonstrated. Work is in progress in order to evaluate the response of the instrument in the cosmic ray environment.

Algorithms↗
PubMed2004

Clinically equivocal melanocytic skin lesions with features of regression: a dermoscopic-pathological study.

BACKGROUND: Benign melanocytic skin lesions may be difficult to differentiate from melanoma both clinically and dermoscopically. One of the most confounding dermoscopic features, commonly seen in melanoma but in our experience also in melanocytic naevi, is represented by the so-called blue-white structures (BWS). OBJECTIVES: To evaluate diagnostic significance and histopathological correlates of BWS seen by dermoscopy in a series of clinically equivocal melanocytic skin lesions that were excised. METHODS: Patients were recruited from six specialized pigmented lesion clinics in Austria, Italy and Spain over a period of 9 months. All consecutive patients showing one or more melanocytic lesions with BWS, but not classified as melanoma dermoscopically, were included. Each lesion was photographed clinically and dermoscopically. All images were reviewed by one of us and the degree, type and location of BWS evaluated for each lesion. A panel of four experienced dermatopathologists independently reviewed all specimens for diagnosis and one of them evaluated presence and degree of melanosis and/or fibrosis. The main outcome measures were the percentage and histopathological correlates of lesions with different degree, type and location of BWS. RESULTS: All included lesions with BWS (n = 158) showed partial or focal regression histopathologically. One hundred and thirty-five (85.4%) lesions were diagnosed as melanocytic naevi (complete histopathological interobserver agreement), whereas 23 (14.6%) were defined as equivocal because at least one of four pathologists diagnosed the given lesion as melanoma. Only one lesion was diagnosed as melanoma by all four pathologists. The majority of naevi exhibited blue areas (84.4%) with a central distribution (57%) and involving < 50% of the lesion surface (89.6%). By contrast, 78.3% of equivocal lesions revealed a combination of white and blue areas with an irregular distribution (60.9%) and involving > 50% of the lesion surface (47.8%). CONCLUSIONS: Using degree and type of BWS, an algorithm was constructed that can be applied for the management of lesions exhibiting dermoscopic features of regression.

Adolescent↗
PubMed2004

Headache treatment before and after the consultation of a specialized centre: a pharmacoepidemiology study.

Our aim was to study and compare pharmacoepidemiology of headache treatment in two different settings: inside and outside a specialized Centre. We analysed the differences in headache treatment between 612 subjects admitted for the first visit ('naive') (F/M: 2.41; mean age = 37.31 +/- 14.09 years) and 620 subjects admitted for a control visit (F/M: 3.18; mean age = 44.30 +/- 15.37 years) to the Headache Centre of the University of Modena and Reggio Emilia. Most patients suffered from migraine. As acute treatment, on the first visit, 49.4% of them were taking drugs prescribed by a doctor; 41.5% were taking over-the-counter analgesics (OTCAs); 9.1% were not taking any drug. On the control visit, 81.3% of patients were taking prescription drugs; 15.8% OTCAs; 2.9% were not taking drugs (overall chi-square = 139.229, P < 0.001). Non-selective analgesics were the most-used drugs. Triptans were used by 9.1% of 'naive' patients and by 31.8% of patients attending for the control visit (Fisher's Z = 7.655, P < 0.001). Nimesulide was the most-used drug. A prophylactic treatment was made by 16.8% of 'naive' patients, and by 58.2% of patients admitted to the control visit (Fisher's Z = 12.135, P < 0.001). Antidepressants were the class of drugs most used for prophylaxis. Amitriptyline was the drug for prophylaxis most frequently used by patients attending the control visit, while flunarizine was the most frequently used by 'naive' patients. Before being examined in a specialized centre, few patients take prescription drugs, triptans, or prophylactic drugs; specialized care increases the proportion of patients taking prophylactic drugs, and changes the type of acute treatment used into disease-specific medication for headache.

Adolescent↗
PubMed2004

Feasibility study for a microchip-based approach for noninvasive prenatal diagnosis of genetic diseases.

Fetal DNA in maternal plasma may represent a source of genetic material for prenatal noninvasive diagnosis of genetic diseases. We evaluated a cohort of physiological pregnancies to determine if fetal DNA can be retrieved at any gestational week in sufficient quantity to be analyzed with advanced mutation detection technologies. We performed fetal DNA quantification by real-time polymerase chain reaction (PCR) on the SRY gene in 356 women sampled from 6 to 40 gestational weeks. Fetal DNA was retrieved at any week. All female fetuses were correctly identified. In 5 of 188 (2.6%) male-bearing pregnancies, no amplification was obtained. For noninvasive testing, complete clearance of fetal DNA after delivery is mandatory. Long-term persistence was not detected in women with previous sons or abortions. These findings confirm that maternal plasma may represent the optimal source of fetal genetic material. For noninvasive diagnosis of genetic diseases, we evaluated microchip technology. The detection limit for a minority allele determined by diluting a mutated DNA into a wild-type plasma sample was 5 genome equivalents, indicating that the test might be applied to the identification of paternally inherited fetal alleles in maternal plasma. The addition of peptide nucleic acids (PNAs) to either the PCR reaction or the chip hybridization mixture allowed approximately 50% inhibition of wild-type allele signals.

Adult↗
PubMed2003

Estimating mixed field effects: an application supporting the lack of a non-linear component for chromosome aberration induction by neutrons.

The action of neutron fields on biological structures was investigated on the basis of chromosome aberration induction in human cells. Available experimental data on aberration induction by neutrons and their interaction products were reviewed. Present criteria adopted in neutron radiation protection were discussed. The linear coefficient alpha and the quadratic coefficient beta describing dose-response curves for dicentric chromosomes induced by neutrons of different energies were calculated via integration of experimental data on dicentric induction by photons and charged particles into the Monte Carlo transport code FLUKA. The predicted values of the linear coefficients for neutron beams of different energies showed good agreement with the corresponding experimental values, whereas the data themselves indicated that the neutron quadratic coefficient cannot be obtained by 'averaging' the beta values of recoil ions and other nuclear reaction products. This supports the hypothesis that neutron induced aberrations increase substantially linearly with dose, a question that has been object of debate for a long time and is still open.

Chromosome Aberrations↗
PubMed2003

On the conversion coefficients for cosmic ray dosimetry.

Calculations of fluence-to-effective dose conversion coefficients have typically been limited to the standard irradiation geometries of the human body: anterior-to-posterior (AP), posterior-to-anterior (PA), lateral from the right side to the left side (RLAT), lateral from the left side to the right side (LLAT), rotational around the vertical axis (ROT), and isotropic incidence from all directions (ISO). In order to estimate the doses to air crew members exposed to cosmic radiation, the geometrical conditions of irradiation are usually assumed to be isotropic. However, the assumption of isotropic irradiation is in many cases invalid for the high energy component of the radiation field, which is often peaked in the forward direction. Therefore, it was considered useful to extend the calculations of conversion coefficients to other geometries. New sets of conversion coefficients fluence-to-effective dose are presented for the semi-isotropic irradiation of the human body and for the irradiation from the top. Their application to cosmic ray dosimetry is discussed.

Aircraft↗