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Biomedical subjects

G Giacomelli

Publications and source records attributed to G Giacomelli.

At least 19 recordsLinked to original sources
PubMed2005

Inguino-scrotal hernia of a double district ureter: case report and literature review.

Ureteral hernia is uncommon and usually misdiagnosed. From an anatomic point of view, we can distinguish between two uretero-inguinal hernias: intraperitoneal and extraperitoneal. Ureter inguinal hernias are nearly always indirect. This kind of hernia can include the ureter alone or, frequently, other abdominal sliding organs within the hernia sac (bladder, bowel tracts, etc.). Kidneys and urinary tracts present normal anatomic conformation, although renal ptosis may be found. As of July 2004, 139 cases of ureteral hernia had been described in the literature. Here we report a case of inguino-scrotal herniation of double district ureter and review the current literature to analyze the main clinical characteristics of this pathology and to establish pitfalls.

Diabetes Mellitus, Type 2↗
PubMed2004

A 24-month survey on root canal treatment performed by NiTi engine driven files and warm gutta-percha filling associated system.

AIM: Techniques based on NiTi engine driven files for shaping and warm gutta percha for obturing the root canal space are becoming more and more popular. Aim of this paper is to evaluate, by a clinical longitudinal study, the type of sealing and the outcome of endodontic treatment, performed by new Profile and Thermafil technique, in teeth with or without periapical lesions. METHODS: A total of 122 teeth in 64 patients were consecutively enrolled in the study; 63 teeth had normal periapical status (Group A) and 59 teeth had periapical lesion (Group B). Endodontic therapy was carried out by Profile .04 and Profile .06 NiTi engine driven files and the obturation was made by Thermafil, a filling technique based on heated gutta-percha surrounding a plastic carrier. The type of sealing was evaluated by a score (A best - D worst) and the type of healing was classified as complete, incomplete and failure according to previous published data. The radiographical outcome of the teeth was evaluated by independent observers after 24 months. Data were analysed by non parametric statistics. RESULTS: At the end of the study, 115 teeth (59 group A and 56 group B) were examined. The quality of sealing was evaluated and some differences were reported comparing different types of teeth. The radiographic outcome was evaluated and 94.9% showed to be completely healed in group A and 48.2% in group B (p=0.0001). CONCLUSION: The technique based on NiTi engine driven files and Thermafil heated gutta-percha has shown, after 24 months, results which were comparable to other root canal shaping and filling methods.

Adult↗
PubMed2003

Experimental evidence of "vibrational resonance" in an optical system.

The experimental evidence and characterization of "vibrational resonance" in a bistable vertical cavity laser are reported. The system is driven by two periodic forcings, with frequencies differing by several orders and studied in the case of both symmetrical and asymmetrical quasipotentials. The phenomenon shows up in the dynamics of the polarized laser emission as a resonance in the low-frequency response and signal-to-noise ratio, depending on the amplitude of an applied high-frequency modulation. The possibility to use the phenomenon for low-level detection is experimentally demonstrated.

Models, Theoretical↗
PubMed2001

A very mild and chemoselective oxidation of alcohols to carbonyl compounds.

Efficient oxidation of primary alcohols and beta-amino alcohols to the corresponding aldehydes and alpha-amino aldehydes can be carried out at room temperature and in methylene chloride, using trichloroisocyanuric acid in the presence of catalytic TEMPO: aliphatic, benzylic, and allylic alcohols, and beta-amino alcohols are rapidly oxidized without no overoxidation to carboxylic acids. Secondary carbinols are slowly oxidized so that the reaction is highly chemoselective. Reaction: see text.

Journal Article↗
PubMed2001

Noise-assisted transmission of binary information: theory and experiment.

We study the response of a bistable vertical cavity surface emitting laser to an aperiodic binary signal, by adding a variable amount of noise. The resulting behavior is an example of aperiodic stochastic resonance, and in this work we give a detailed comparison between analytical and numerical results and accurate experimental measurements. We characterize the phenomenon by using different appropriate indicators, which also allow us to quantify the binary information transmission. We show that the quality of the transmission is enhanced by a suitable amount of noise, and we give a physical picture of the phenomenon.

Journal Article↗
PubMed2001

A new supported reagent for the photochemical generation of radicals in solution.

A new polymer-supported radical source was developed by loading an N-hydroxy thiazole 2(3)-thione on a Wang resin. This new supported reagent can be employed for a solid-phase version of the Hunsdiecker reaction or to liberate free alkoxy radicals, in a variant of the "catch and release" technique, under very mild conditions (irradiation with a discharge lamp) and simplifying the purification procedure.

Journal Article↗
PubMed2000

Experimental evidence of binary aperiodic stochastic resonance

A novel kind of aperiodic stochastic resonance is experimentally studied in a vertical cavity surface emitting laser. We characterize the response of the system to a random, binary signal as a function of an applied external noise. A maximum in the input-output correlation is found for a nonzero added noise. We present analytic results with a good agreement with the measurements. We also discuss the physical meaning of the phenomenon using simple arguments, and we compare it to stochastic resonance.

Journal Article↗
PubMed2000

Convective lyapunov exponents and propagation of correlations

We conjecture that in one-dimensional spatially extended systems the propagation velocity of correlations coincides with a zero of the convective Lyapunov spectrum. This conjecture is successfully tested in three different contexts: (i) a Hamiltonian system (a Fermi-Pasta-Ulam chain of oscillators); (ii) a general model for spatiotemporal chaos (the complex Ginzburg-Landau equation); (iii) experimental data taken from a CO2 laser with delayed feedback. In the last case, the convective Lyapunov exponent is determined directly from the experimental data.

Journal Article↗
PubMed2000

Experimental evidence of coherence resonance in an optical system

Experimental evidence of coherence resonance in an optical system is reported. We show that the regularity of the excitable pulses in the intensity of a laser diode with optical feedback increases when adding noise, up to an optimal value of the noise strength. Both phase and amplitude fluctuations of the pulses play a relevant role in the dynamics of the system. We introduce the joint entropy of the two variables to generalize the indicator of coherence, and we put in evidence the mechanism of destruction of the excitable orbit after the resonance.

Journal Article↗
PubMed2000

Stochastic resonance in vertical cavity surface emitting lasers

We report a detailed experimental investigation of stochastic resonance (SR) in the polarized emission of a pump-modulated vertical cavity surface emitting laser. We characterize SR in the time and frequency domains, with a quantitative agreement with existing theories. We further report a statistical analysis of SR in terms of residence-time probability distributions exhibiting alternative features which are fully explained here. By using an accurate choice of the indicator, we are also able to give clear evidence of bona fide resonance.

Journal Article↗
PubMed1998

White blood cell DNA adducts, smoking, and NAT2 and GSTM1 genotypes in bladder cancer: a case-control study.

We conducted a case-control study on 114 bladder cancer patients and 46 hospital controls. DNA adducts were measured in WBCs by 32P postlabeling and showed no association with smoking habits and the glutathione-S-transferase M1 genotype. A strong association between adduct levels and the N-acetyltransferase (NAT2) genotype was found (P = 0.0002). The NAT2 genotype was associated in a nonstatistically significant way to the case-control status (odds ratio, 1.6; 95% confidence interval, 0.8-3.2). In a logistic regression model, the log of DNA adduct levels was associated in a highly significant way to the risk of bladder cancer (regression coefficient, 0.75; P = 0.0006), independently of smoking habits. Using the median of DNA adducts (RAL, 0.3) as a cutoff point, the odds ratio for the risk of bladder cancer was 4.1 (age-adjusted; 95% confidence interval, 1.9-9.0). Our study suggests that sources other than tobacco smoke contribute to the formation of aromatic DNA adducts in WBCs. The role of WBC-DNA adducts in predicting bladder cancer is still to be clarified.

Adult↗
PubMed1997

A study of the radiobiological effectiveness with track etch detectors.

CR-39 nuclear track detectors have been used in this experiment to study the killing effect of low energy protons on V79-753B Chinese hamster cells and to monitor the proton beam. The estimated surviving fractions and the beam parameters are comparable to those found with conventional electronic devices. The surviving fractions fitted by the linear quadratic model support the idea of single-hit mechanism for the cell killing.

Animals↗
PubMed1997

Radon measurements in the Gran Sasso Underground Laboratory.

Systematic radon monitoring in the Gran Sasso Underground Laboratory was performed in order to determine the background radon contribution to the sophisticated experimental apparatus and to check health physics standards for the personnel. As expected, the radon concentrations were found to depend strongly on the ventilation in the three experimental halls. Considerable reductions in the radon concentrations were obtained in 1993, when fresh air was drawn into the laboratory through a pipe and exhaust air was routed into the highway tunnel.

Air Pollutants, Radioactive↗