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M Gai

Publications and source records attributed to M Gai.

At least 19 recordsLinked to original sources
PubMed2003

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis.

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Journal Article↗
PubMed2003

Coulomb dissociation of 8B and the low-energy cross section of the 7Be(p,gamma)8B solar fusion reaction.

An exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254A MeV allowed the study of the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates and that E2 multipolarity can be neglected. By using a simple single-particle model for 8B and treating the breakup in first-order perturbation theory, we extract a zero-energy S factor of S17(0)=18.6+/-1.2+/-1.0 eV b, where the first error is experimental and the second one reflects the theoretical uncertainty in the extrapolation.

Journal Article↗
PubMed2003

First measurement of transferred polarization in the exclusive ep-->e'K+Lambda--> reaction.

The first measurements of the transferred polarization for the exclusive e-->p-->e(')K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Journal Article↗
PubMed2003

Photoproduction of the omega meson on the proton at large momentum transfer.

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Journal Article↗
PubMed2002

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV.

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Journal Article↗
PubMed2002

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition.

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Journal Article↗
PubMed2002

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region.

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

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PubMed2002

Plasma homocysteine, methylenetetrahydrofolate reductase gene polymorphism and carotid intima-media thickness in Italian type 2 diabetic patients.

BACKGROUND: Moderately elevated levels of homocysteine have been associated with an increased cardiovascular risk in type 2 diabetic patients. The role of methylenetetrahydrofolate reductase gene polymorphism is less clear. MATERIALS AND METHODS: We investigated the contribution of plasma homocysteine levels and the methylenetetrahydrofolate reductase gene polymorphism to the variability of carotid intima-media thickness in 124 consecutive Italian patients with type 2 diabetes mellitus. Fasting plasma homocysteine was measured by high-pressure liquid chromatography with an electrochemical detector; methylenetetrahydrofolate reductase genotypes were determined by polymerase chain reaction and restriction enzyme digestion. The carotid intima-media thickness was evaluated with high-resolution B-mode ultrasonography. RESULTS: Age, creatinine and plasma homocysteine levels showed a positive correlation with mean carotid intima-media thickness values, but only age and creatinine levels were still associated with mean carotid intima-media thickness values in the multivariate analysis. Plasma homocysteine levels were significantly higher in the patients bearing the 677T/677T genotype of the methylenetetrahydrofolate reductase polymorphism; mean carotid intima-media thickness values were not different in the three different methylenetetrahydrofolate reductase genotypes. CONCLUSION: In 124 Italian patients with type 2 diabetes mellitus, basal levels of plasma homocysteine, as well as methylenetetrahydrofolate reductase gene polymorphism, did not explain the variability of mean carotid intima-media thickness.

Aged↗
PubMed2002

Teaching technology with technology: computer assisted lessons in the medical school the first Italian experience in nephrology and dialysis.

BACKGROUND: Dialysis is often neglected in academic teaching. At the University of Torino, Italy, teaching Nephrology (4th year of Medical School) consists of 21 hours of formal lessons, 10 hours/student of interactive lessons (4/10 dedicated to dialysis) and 10 optional lessons (3 regarding dialysis). Interactive and optional lessons widely employ computer assisted teaching. Aim of the study was to evaluate student satisfaction on this approach. METHODS: Student satisfaction was assessed on 4 sample lessons (166 students), by two short dedicated questionnaires (0-10 scale, open questions). RESULTS: High scores were given to the dialysis lessons (median 8/10). Computer assisted interface (median 8/10, range 6-10) was of help in check of knowledge in real time (86%), enhancing participation (61%); 62% suggest extending this experience to selected courses, 38% to all. CONCLUSIONS: Medical students consider dialysis an important part of the academic teaching of Nephrology; new interfaces may help to enhance student satisfaction.

Adult↗
PubMed2002

[Daily dialysis: evaluation of the first year of experience at home and in a limited care center].

BACKGROUND: Among self dialysis treatments, daily dialysis is encountering a growing interest. Aim of this study was to evaluate results of the first year of daily dialysis in our Center. METHODS: Since November 1998, twelve patients started daily dialysis. One patient started RRT on daily dialysis; one patient was in training; 8 were on home dialysis, 3 in the limited care center. Selection of patients was performed according to wide acceptance criteria as for age (range 33-61 years), dialysis follow-up (range 1-23 years), comorbidity (=/>1 comorbid factor present in 8). Dialysis schedule consisted of 6 sessions per week (2-3 hours), blood flow 250-320 ml/min, individualized dialysate. Occasional shift to 3-4 times per week were allowed for logistic or working reasons. RESULTS: Results were analyzed taking into account patient satisfaction and main clinical parameters. In 9/12 the choice of treatment resulted from both clinical reasons and patient preferences, while in 3 was due to clinical indications (1/3 dropped out). The main reasons of choice were logistic or research of the best treatment. The most common fears regarded fistula and needle puncturing. Despite the time unconvenience, the rapidly regained well being was the reason for choosing this treatment. Also in this relatively short follow-up the favorable results reported as for weight gain, blood pressure control and metabolic pattern are confirmed. The few side effects were multifactorial (fistula thrombosis after blood pressure normalization, 2 recurrences of atrial fibrillation). CONCLUSIONS: In conclusion, daily dialysis resulted also in our centre as a promising alternative even in difficult patients.

Adult↗
PubMed2001

Photoproduction of the rho(0) meson on the proton at large momentum transfer.

The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction.

Journal Article↗
PubMed2001

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance.

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Journal Article↗
PubMed2001

Daily dialysis Kt/V and flexible schedules: is it possible to control efficiency, when and how?

BACKGROUND: Daily hemodialysis is a promising treatment schedule but uniform criteria for defining efficiency are lacking. METHODS: On our daily dialysis (DD) schedule, duration is flexible (2-3 hours, patients are free to add up to 30 min/session), Qb 250-350 mL/min; dialyser 1.6-1.8 m2. Study was performed on 12 pts on DD for > or = 2 months, with > or = 4 Kt/V on subsequent days, tested in the same laboratory. GOAL: To evaluate variability and identify a simple method for weekly calculation, Kt/V was assessed for 133 sessions. RESULTS: On flexible DD, variability of Kt/V-session is high (relative error 4.9%-22%). On flexible schedules, within the time range chosen (2-3 hours) variability of average hourly Kt/V is lower (standard deviation: min (0.014; max (0.052 hour, relative error 4.9%-10%) allowing calculation of weekly Kt/V (averaging 3 sessions: relative error < 6%) suitable for clinical practice. CONCLUSIONS: Flexible schedules, allowing patients to increase treatment time, are an interesting clinical option, but a challenge for Kt/V assessment.

Adult↗
PubMed2001

[Diagnosis and treatment of pulmonary embolism during pregnancy].

OBJECTIVE: To study high risk factors, clinical presentation, diagnosis and treatment of pulmonary embolism (PE) during pregnancy and postpartum. METHODS: Two patients with pulmonary embolism were reported retrospectively. RESULTS: The 1st case was a pregnant woman with congenital heart disease at 39 weeks gestation, who underwent uneventful cesarean section (CS) because of heart disease, but she had tachycardia, tachypnea, cyanosis, dyspnea suddenly on the 10 days after CS and died immediately after the onset of above symptoms, the diagnosis of PE was highly suspected clinically. The 2nd case was a pregnant women with twin gestation, at 35 weeks, because of severe prenatal myocardiopathy, cesarean section was performed, Maternal death occurred suddenly during the surgery. The diagnosis of PE was confirmed by autopsy. CONCLUSIONS: The maternal mortality of PE during pregnancy and postpartum is very high, whenever there is any suspects, the objective examination for PE should be started early in order to get the chance to give anticoagulant therapy.

Adult↗
PubMed2001

[Clinical analysis of idiopathic thrombocytopenic purpura with pregnancy].

OBJECTIVE: To study the optimal management of pregnant women with idiopathic thrombocytopenic purpura (ITP). METHODS: The outcomes of 37 pregnancies with ITP about 10 years from (1990 to 1999) were analysed. RESULTS: Among the 37 cases, vaginal delivery and cesarean section were done in 16 and 21 cases respectively. Neonatal thrombocytopenia was diagnosed in 3 newborns. None of them had intracranial hemorrhage. The incidences of postpartum hemorrhage and infection were 8.1% and 2.7%, respectively. No maternal mortality was noted. CONCLUSIONS: In view of very low morbidity in babies of ITP mothers, we suggest that they be delivered vaginally if there is no obstetrical complications. Selected cesarean delivery should be performed in severely thrombocytopenic cases when there are sufficient fresh blood and platelet. The invasive interventions should not be used to avoid newborn thrombocytopenia.

Adult↗
PubMed2000

Education as a clinical tool for self-dialysis.

Therapeutic compliance and patient education are presently considered crucial parts of end-stage renal disease (ESRD) therapy. In the center where Italian home and self-care dialysis treatment started, an education program was designed as multi-step pathway--following patients from chronic renal failure to dialysis and eventual graft--employing lessons, booklets, and books. Each step was validated in various subsets of patients. Lessons involved two hours of informal discussion on the main aspects of ESRD and renal replacement therapy (RRT); booklets were created from tape recordings of the lessons. Patient participation was good, with 28 of 33 patients on charge in the center for 6 months or more taking part in more than one lesson in 1999. In 16 of 16 patients who answered a questionnaire after two lessons, expressed opinion was "good" to "fair." All asked for further material. With regard to books, 500 copies of the book What does dialysis mean? were given out in the region; this book was validated in 22 patients on peritoneal dialysis (PD) and 18 on hemodialysis (HD). It helped patients to accept dialysis in 65% of cases and to comprehend it in 90%. Four thousand copies of the book Stories, containing 18 interviews on transplantation, were printed, and this book was validated in 21 patients on self-care and 35 on hospital dialysis (potential candidates for graft). Of 56 patients, 53 asked for further material; 19 changed their initial opinion (10 choose transplantation, despite initial skepticism; 9 put off transplantation, despite initial acceptance). On a local scale, the program led 12 of 18 new patients, who followed at least part of the program, to choose self-dialysis (PD, home, and self-care dialysis).

Adult↗