In the past L. Ferrari has collaborated on articles with J. Chahoud and G.L. Braglia. One of their most recent publications is On the low-temperature behaviour of amorphous semiconductors. Which was published in journal Journal of Non-Crystalline Solids.

More information about L. Ferrari research including statistics on their citations can be found on their Copernicus Academic profile page.

L. Ferrari's Articles: (24)

On the low-temperature behaviour of amorphous semiconductors

AbstractA model is proposed in order to explain the existence of elementary excitations different from Debye phonons in the amorphous structures. As a basic idea it is assumed that for any amorphous materials a distribution of clusters exhibiting a certain degree of order will be present in the full disordered bulk. A rough extimate performed on a-As data shows that the concentration of such heterogeneous clusters is so low to have no influence on the macroscopic homogeneity of the amorphous material.

Solution of the Boltzmann equation for electrons in a gas in electric and magnetic fields: I. Steady-state solution

AbstractIn this article, we discuss a general method for obtaining an approximate solution of the Boltzmann equation. The method is applied to a Maxwell-Lorentz gas, in electric and magnetic fields, for which an analytical solution can be given. A detailed analysis of the steady-state solution is presented and the usual approximations are tested in the light of our theory. Particular attention is directed to the determination 1) of the anisotropies of the velocity distribution, and 2) of the errors affecting the solution.

Solution of the Boltzmann equation for electrons in a gas in electric and magnetic fields: II. Time-dependent solution

AbstractThe method of solution of the Boltzmann equation presented in our preceding paper is used to obtain the time-dependent velocity distribution of the electrons of a Maxwell-Lorentz gas in electric and magnetic fields. A detailed analysis of the solution and of its limits of validity is given. Our study is limited to isotropic initial distributions. The two particular cases in which the initial distribution is maxwellian or a δ function are studied in detail.

Optical properties and characterizationObservation of luminescence and Franz-Keldish effect on cleaved CdTe(110) surfaces

AbstractWe present data on photoluminescence (PL) and the Franz-Keldish (FK) effect on ultra-high-vacuum-cleaved CdTe(110)1 × 1 surfaces by surface differential reflectivity (SDR). PL and the FK effect on a clean surface have been studied as a function of argon laser power with the sample at room temperature. PL spectra have been deconvoluted into two contributions: a free excition peak, which determines the PL peak position, and an interband recombination structure, which dominates most of the PL spectra. The linear dependence of the area of the PL spectra on laser power confirms that the PL spectrum is mainly due to the contribution from free-carrier recombination. The PL peak position shifts towards lower energies (18 meV maximum), linearly with increasing laser power, presumably due to local heating of the sample. The FK effect has an exponential dependence upon laser power. Upon switching off the laser, the FK effect exponentially disappears with a time constant of about 1300 s. Angle-resolved photoemission has been used to evaluate the shift of the Fermi level upon laser irradiation. FK and photoemission results are compared to evaluate the magnitude of the FK effect. Moreover, the photovoltage induced by the photoemission lamp has been measured through the FK effect and resulted to be 80 meV.

Geology of Los Azufres Caldera, Mexico, and its relationships with regional tectonics

AbstractThe Los Azufres geothermal field is one of several silicic centres of the Mexican Volcanic Belt (MVB) for which a caldera structure was suggested. Geological and structural surveys in a wide area surrounding Los Azufres reveal that this complex is situated in an area of unusual concentration of acid volcanism, consisting of four pyroclastic units and several dome complexes. Although a complete caldera structure is not morphologically evident, several facts suggest a long collapse history at Los A zufres: •- the geothermal field lies at the centre of a subcircular depressed area (27 × 26 kminsize) filled by a distinctive fluviolascustrine sequence;•- Middle to Late Miocene rocks bound to the south and to the north of this depression and are encountered only at depth inside it;•- four large ignimbritic suites of latest Miocene and Pliocene age outcrop outside the depression;•- volume estimations of these pyroclastic products are comparable with the missing volume of the depressed area;•- no alternative caldera structures exist in a radius of 200 km from Los Azufres;•- dacitic to rhyolitic lavas, principally extruded as dome complexes, were emplaced inside this depression during the Pleistocene.Los Azufres is therefore interpreted as a nested caldera of latest Miocene and Pliocene age.The recent regional tectonic evolution of the central sector of MVB comprises a Late Miocene-Early Pliocene left-lateral transcurrent phase, followed by a Late Pliocene-Quaternary transtensional one. The silicic volcanism occurring between 6.1 and 2.8 Ma can be linked to the first phase, while in the adjacent areas of MVB a volcanic hiatus can be recognized. The following transtensional phase reached the Los Azufres area only during the Pleistocene and disrupted the caldera structure. Normal faults, developed during this period, controlled the uprising of basic magma which partly interacted with the remaining differentiated one and produced part of the recent intracaldera cycle.

On the three-term approximation of the solution of the Boltzmann equation for weakly ionized gases☆

AbstractIn this paper we discuss an improvement of the current technique of solution of the Boltzmann equation for weakly ionized gases in an electric field. The method is based on the usual expansion of the velocity distribution in spherical harmonics, but three terms of the expansion are retained instead of two. In the light of the results obtained for a particular interaction law between charged and neutral particles, a procedure is established which is consistent in the orders of approximation. This procedure requires an improvement of the degree of accuracy commonly used for the terms deriving from the Boltzmann collision operator. For this reason, the general expression of the isotropic collision operator correct to second order in the ion-neutral mass ratio is calculated. Finally, a new steady-state solution of the Boltzmann equation is obtained which is valid both for electrons and light ions in heavy gases.

Carbon periodic cellular architectures

AbstractThe first carbon periodic cellular architectures derived from 3D printing, in the form of new tetrakaidecahedra meshes, are reported and investigated in this paper. They were prepared in hydrothermal conditions by a template method based on polymer periodic structures of the same geometry, and fabricated by a 3D printer using photocurable resin. Several formulations based on resorcinol–formaldehyde were tested, and the best ones were those using low concentrations of resorcinol at 150 °C in a pressurised solution of nickel nitrate. After pyrolysis at 1000 °C, catalytic graphitisation was demonstrated by TEM, XRD and Raman studies. The higher was the amount of nickel, the higher was the resultant graphitisation level. Mechanical tests were also carried out on such extremely lightweight periodic carbon structures, showing that these new materials present a much higher modulus than carbon foams of similar bulk densities.

OriginalCáncer de próstata: concordancia entre PET 18F-colina y TC en recaída bioquímicaProstate cancer: concordance between 18F-choline PET and CT in biochemical relapse

ResumenObjetivoEstablecer la concordancia de la tomografía por emisión de positrones (PET) con 18-flúor colina y la tomografía computada (TC) para la reestadificación ganglionar (N) y metastásica (M) del TNM en la recaída bioquímica del cáncer de próstata.Materiales y métodosSe revisaron retrospectivamente historias clínicas de pacientes atendidos en Imágenes moleculares. En cada método establecimos la clasificación TNM ganglionar y metastásica. Se utilizó el índice de concordancia Kappa, categorizando los resultados según lo propuesto por Landis y Koch.ResultadosDe los 32 pacientes con PET-colina y TC, en la clasificación ganglionar con PET-colina, 19 (59,4%) fueron N0 y 13 (40,6%), N1; mientras que en la TC, 28 (87,5%) fueron N0 y 4 (12,5%), N1. En la clasificación metastásica, el método PET-colina identificó M0 en 17 (53,1%) pacientes, M1a en 1 (3,1%), M1b en 5 (15,6%), M1c en 1 (3,1%), M1a + M1b en 7 (21,9%), M1b + M1c en 1 (3,1%); mientras que la TC reportó M0 en 23 (71,9%), M1a en 2 (6,25%), M1a + M1b en 2 y M1b + M1c en 5 (15,6%). La concordancia en la clasificación TNM ganglionar y metastásica entre PET-colina y TC fue de 71,88% con 0,3455 de Kappa (error estándar: 0,1336; p= 0,0049) y de 62,5% con 0,3725 de Kappa (error estándar: 0,0847; p = 0,0001), respectivamente.DiscusiónEl método PET-colina demostró alta exactitud diagnóstica en la extensión de la enfermedad, con respecto a los métodos convencionales.ConclusiónLa concordancia entre el método PET-colina y la TC para la clasificación TNM ganglionar y metastásica no es buena.

Characterization of an Endopeptidase from Alfalfa (Medicago sativa L.) Leaves

SummaryOne endopeptidase was present in alfalfa (Medicago sativa L. cv. Messe) leaves, as detected by gel-filtration, ion-exchange chromatography, and high pressure liquid chromatography.The endopeptidase found, as judged by phenylmethylsulfonyl fluoride inhibition, behaves as a serine endopeptidase, with a functional histidyl residue as judged by diethyl pyrocarbonate inhibition.The enzyme digested hemoglobin and casein at optimum pH 3.5 and 4.5 respectively; however it retains 50% of the activity at higher pH. The molecular weight, estimated by gel filtration, was 117,000.

Delamination of sub-crustal lithosphere beneath the Isthmus of Tehuantepec, Mexico: Insights from numeric modelling

AbstractThe Isthmus of Tehuantepec (IT) is a tectonically active and complex physiographic province in southern Mexico marked by an anomalous volcanism with unusual location and geochemical signature, an extensional stress regime and a well-imaged high seismic-velocity anomaly in form of a slab-like structure whose origin remains still not well understood. Here we use numeric modelling, tectonic information and composition of volcanic rocks from the Los Tuxtlas Volcanic Field (LTVF) to reconstruct the geodynamic evolution of the Isthmus of Tehuantepec from the Late Miocene to the present, and propose a model that reconciles the seismic observations with the tectonic evolution of the region. Using a high-resolution thermomechanical petrological coupled model, we show that rollback of delaminated continental lithosphere and associated asthenospheric upwelling provides a plausible mechanism for generating the observed high seismic-velocity anomalies beneath the Isthmus of Tehuantepec. Our model proposes that delamination of the entire lithospheric mantle initiated some 7 Myr ago by infiltration of hot and buoyant asthenospheric material into the base of the crust, when a slab gap appeared in the subducting Cocos slab. A geodynamic model involving sub-crustal lithosphere delamination reconciles the geological and geophysical observations and explains the complex oceanic-continental tectonics of the Isthmus of Tehuantepec.

Full length articleVaginal birth after prior myomectomy

AbstractObjectiveThe aim of this retrospective cohort study was to evaluate the obstetrical and perinatal outcomes of vaginal birth in case of pregnancies achieved after prior myomectomy. We also analyzed how operative characteristics at the time of surgery might influence the choice of obstetricians about mode of delivery.Study designWe analyzed retrospectively all women who underwent laparoscopic (LPS) or laparotomic (LPT) myomectomy between January 2002 and December 2014, in a network of three Institutions belonging to the University of Milano Bicocca, Italy. Women were contacted by phone interview and only cases with available follow-up data and who had a subsequent pregnancy were included. Operative characteristics and subsequent obstetrical outcomes were recorded and analyzed.Results469 women who underwent myomectomy were contacted by phone interview, and 152 pregnancies were achieved after surgery, 96 after LPS and 56 after LPT. A total of 110 pregnancies ended in deliveries at ≥24 weeks. Seventy-three (66.4%) women had trial of labor after myomectomy (TOLAM), while 24 (21.8%) had a planned cesarean delivery (CD). Sixty-six (90.4%) of the TOLAM cases successfully accomplished vaginal delivery. No cases of uterine rupture (UR) were reported, and all deliveries ended in live births. The incidence of Neonatal Intensive Care Unit admission was 14.5% (16/110), with no cases of perinatal death. Comparing the surgical details at the time of myomectomy, the incidence of uterine cavity entered was significantly higher in planned CD group compared to TOLAM cases (p < 0.001). No other significant difference between the two groups was reported.ConclusionsA successful vaginal delivery was accomplished by 90.4% of women who had TOLAM, without any case of UR or severe maternal and perinatal complications. TOLAM may be considered and offered as feasible and relatively safe option.Obstetricians’ attitude toward mode of delivery after prior myomectomy seems to be influenced by the reported entry into the uterine cavity at the time of surgery.

Some bijective results about the area of Schröder paths

AbstractIn the existing literature there are many combinatorial interpretations for the sequence (ai)i⩾1=1,3,7,17,41,… (M2665 in The Encyclopedia of Integer Sequences, Academic Press, New York, 1995), and at least one for the subsequence of its odd-indexed terms, i.e. 1,7,41,239,…, using the area under elevated Schröder paths. We provide a combinatorial interpretation for the subsequence given by the remaining terms 3,17,99,…, also in this case by using the area under Schröder paths.

Original paperThe minimal effective exemestane dose for endocrine activity in advanced breast cancer

AbstractPhase I studies have demonstrated that exemestane, an irreversible oral aromatase inhibitor, is able to suppress circulating oestrogen levels. In our previous experience, doses ranging from 2.5 to 25 mg induced a similar suppression of oestrogens. The aim of this study was to identify the minimum effective exemestane dose on the basis of endocrine activity. 20 evaluable postmenopausal advanced breast cancer patients were randomly given exemestane 0.5, 1, 2.5 or 5 mg, in double-blind conditions. Oestrone (E1), oestradiol (E2), oestrone sulphate (E1S), gonadotrophins, sex-hormone binding globulin and dehydroepiandrosterone sulphate serum levels were evaluated from the first day of treatment to the 7th, 14th, 28th and 56th day. Serum E1, E2 and E1S levels were suppressed by all doses starting from day 7; the degree of inhibition versus baseline was 25 up to 72% for E1, 30 up to 62% for E2 and 16 up to 52% for E1S, with higher doses achieving greater suppression; these changes were maintained over time. A significant increase in FSH and LH levels was observed for all doses. Treatment tolerability was satisfactory. The endocrine effects of exemestane appear to be dose related and 0.5 and l mg are ineffective for adequately suppressing circulating oestrogens.

Research paperBiomethane grid injection or biomethane liquefaction: A technical-economic analysis

Highlights•Biomethane grid injection or liquefaction? Assessments for biogas producers.•Detailed model of the liquefaction plant has been created in Aspen HYSYS.•Sensitivity analysis on selling price to assess economic convenience of two systems.•Biomethane injection minimized investment risk for connection costs below 500 k$.•Liquefaction is profitable in some cases only if liquefaction process is efficient.

Original ArticlesLaparoscopic Myomectomy: Technique, Complications, and Ultrasound Scan Evaluations

AbstractStudy ObjectiveTo evaluate the feasibility, limits, and complications of laparoscopic myomectomy, assess time to full recovery, and evaluate uterine wound healing by ultrasound in the early postoperative period.DesignProspective study (Canadian Task Force classification II-2).SettingGeneral hospital.PatientsThree hundred sixty-eight women undergoing laparoscopic myomectomy.InterventionLaparoscopic myomectomy and laparoscopic and/or hysteroscopic treatment of associated pathologies.Measurements and Main ResultsIn these women 768 myomas were removed laparoscopically. Mean operating time was 100.78 ± 43.83 minutes, mean decreases in hemoglobin and hematocrit were 1.38 ± 0.93 g/100 ml and 4.8 ± 2.9 g/100 ml, respectively, and mean length of hospital stay was 2.89 ± 1.3 days. Intraoperative complications occurred in 12 patients (3.34%) and intraoperative transfusion of autologous blood was required in 10. Main postoperative complications were continuing hemorrhage requiring blood transfusion in three women and second laparoscopy in two. Pyrexia occurred in 12 patients. Average time to full recovery was 10.58 ± 6.68 days. At 1-month follow-up 12 of 282 women developed further complications: abdominal pain 5, vaginitis 4, metrorrhagia 2, and dysuria 1. Sonographic evaluation of the uterine scar showed a highly echogenic area with ill-defined margins. In 81 women who had sonographic evaluation 30 days postoperatively, the uterine scar was reduced by an average of 44.1% (p <0.001). Of 176 patients screened at day 30, 6 (3.4%) had anechoic areas adjacent to the uterine scar, possibly due to hematoma. A previously unknown myoma, two ovarian cysts, and two pelvic hematoma were also discovered.ConclusionLaparoscopic myomectomy is effective and relatively safe. In skilled hands it has a low risk of complications and appears to be a valid alternative to the open procedure. Sonographic assessment allows detection of alterations in muscular echotexture, but its effectiveness in identifying women at risk of uterine rupture or dehiscence has to be proved.

Effects of carbon dioxide feeding rate and light intensity on the fed-batch pulse-feeding cultivation of Spirulina platensis in helical photobioreactor

AbstractThe behavior of S. platensis was investigated in this study through fed-batch pulse-feeding cultures performed at different carbon dioxide feeding rates (F = 0.44–1.03 g L−1 d−1) and photosynthetic photon flux density (PPFD = 80–250 μmol photons m−2 s−1) in a bench-scale helical photobioreactor. To achieve this purpose, an inorganic medium lacking the carbon source was enriched by gaseous carbon dioxide from a cylinder. The maximum cell concentration achieved was 12.8 g L−1 at PPFD = 166 μmol photons m−2 s−1 and F = 0.44 g L−1 d−1 of CO2. At PPFD = 80 and 125 μmol photons m−2 s−1, the carbon utilization efficiency (CUE) reached maximum values of 50 and 69%, respectively, after about 20 days, and then it decreased, thus highlighting a photolimitation effect. At PPFD = 166 μmol photons m−2 s−1, CUE was ≥90% between 20 and 50 days. The photosynthetic efficiency reached its maximum value (9.4%) at PPFD = 125 μmol photons m−2 s−1. The photoinhibition threshold appeared to strongly depend on the feeding rate: at high PPFD, an increase in the amount of fed CO2 delayed the inhibitory effect on biomass growth, whereas at low PPFD, excess CO2 addition caused the microalga to stop growing.

50. Clinical and neurophysiological effect of deep rTMS with H-COIL in Parkinson’s disease

Our aim was to evaluate safety and clinico-neurophysiological effects of repetitive Deep Transcranial Magnetic Stimulation (DTMS) in Parkinson’s Disease (PD), using the novel H-COIL. Fourteen PD-patients underwent 12 sessions 10 Hz-DTMS (4 weeks) over primary motor area opposite to their most affected side (W-M1) and prefrontal cortices. Clinical assessment (UPDRSIII; timed-tests including arm/foot tapping-AT/FT) and neurophysiological evaluation (Resting Motor Threshold-RMT, input–output curves-IO, Cortical Silent Period-CSP, intracortical inhibition-ICI/facilitation-ICF) were performed for worse (WS) and less affected (BS) sides. Patients were evaluated OFF therapy at baseline (T0) and before the last DTMS-session (T1). We found significant clinical improvements in UPDRSIII (41.9 ± 9.4 vs. 31.4 ± 7.9; p < 0.001), lateralized scores (p < 0.001 for both sides) and timed-test (p < 0.05 for AT and FT in both sides). Neurophysiological measures disclosed modifications in M1 excitability only in the worse hemisphere. RMT lowered from 36.5 ± 6.7 to 34.3 ± 6.4 (p = 0.04), MEP amplitude (120%RMT) increased (p = 0.04); ICI and ICF paralleled these modifications (3 and 15 ms; p = 0.05 and p = 0.04 respectively); CSP shortened (p = 0.05). No changes were observed for IO curves. Despite the lack of blindness, DTMS appears as a safe and promising new therapeutic perspective for non-invasive stimulation in PD. Neurophysiological changes on the worse side motor excitability paralleled clinical findings.

85. Deep repetitive transcranial magnetic stimulation with H-coil for motor symptoms in Parkinson’s disease: A randomized, double blind, placebo-controlled study

To evaluate the effect of repetitive deep transcranial magnetic stimulation—rDTMS on motor symptoms in Parkinson’s Disease—PD in a randomized, placebo controlled study. Sixty patients underwent 12 sessions (3 sessions/week) of 10 Hz rDTMS, after randomization into 3 groups: Group 1 (real rDTMS on primary motor—M1 and prefrontal—PF areas); Group 2 (M1-real/PF-sham), Group 3 (M1-sham/PF-sham). Primary outcome was percent reduction of Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III, OFF therapy. Secondary outcomes were: changes in UPDRSIII sub-scores; improvement in timed tests (Hand Tapping—HT, Foot Tapping—FT, Walking Time—WT, Nine Hole Peg Test—NHPT). Statistical analysis was performed using Mann–Whitney or t-test. Outcomes were tested in hierarchical order, by comparing the two real groups (1–2) only if their pooled data significantly differed from sham. No drop-outs or serious adverse effects were recorded. Both real groups improved significantly more than sham in UPDRSIII (p = .010 and p = .045, respectively), while they did not significantly differ between them. Pooled real groups showed a significant improvement vs sham in UPDRSIII (p = .007), tremor (p = .011) and lateralized sub-scores (p = .042 and p = .012 for worse and better side, respectively). Timed tests significantly improved more in the real group vs sham on the worse side (HT p = .041, FT p = .012, NHPT p = .003). rDTMS with H-coil appeared safe and effective on motor symptoms as add-on treatment in PD.

12. Sensitivity and predictive value of OCT and VEP in multiple sclerosis

Aim of the study was to evaluate the role of optical coherence tomography (OCT) and visual evoked potentials (VEPs) in patients with multiple sclerosis (MS), on 121 consecutive subjects with MS. Of 242 eyes, 166 had no previous history of optic neuritis (ON), 22 had a single recent ON episode (<3 months); 54 had chronic ON (at least 1 episode >3 months before). All patients underwent assessment of EDSS, OCT retinal nerve fiber layer (RNFL) thickness and VEP (checkerboard, size 15′); 77 subjects underwent a second EDSS (EDSS2) evaluation after a mean time of 2 ± 0.69) years (median EDSS 2, range 0–7). In eyes with recent ON, the sensitivity of OCT was 38.9% with a higher sensitivity of VEP (77.3%; McNemar p < 0.02). In eyes with chronic ON, no significant difference was found between OCT (68.5%) and VEP (81.5%) sensitivity. In asymptomatic eyes, VEPs had a higher sensitivity (31.7%) vs OCT (19.9%; p = 0.005); VEP/OCT combined detected abnormalities in 39.2%. In follow up evaluation, OCT alterations were associated with development of disability after 2 years (p = 0.013). VEP alterations did not predict future disability development neither in patients with previous ON nor in those without. The present findings confirm a higher sensitivity of VEPs in the subacute phases of optic neuritis (less than 3 months) and in asymptomatic eyes. In eyes without previous optic neuritis, early asymptomatic OCT abnormalities are associated with short-term worsening of disability. Further longitudinal studies are needed to confirm our findings.

Loss of Thy-1 (CD90) antigen expression on mesenchymal stromal cells from hematologic malignancies is induced by in vitro angiogenic stimuli and is associated with peculiar functional and phenotypic characteristics

BackgroundLittle is known about human mesenchymal stromal cell (hMSC) phenotypic and functional subsets in response to environmental stimuli. The strategy used in this study focused on defining hMSC functional subpopulations based in particular on their Thy-1 (CD90) antigen (Ag) surface expression.MethodsThe effect of different in vitro microenvironmental conditions on the isolation and expansion of bone marrow-derived (BM) hMSC from hematologic malignancies (HM) and normal samples (NS) was assayed. hMSC clonogenic and differentiation potential, phenotypic profile and long-term capacity to sustain in vitro hemopoiesis were considered in relation to the different expansion protocols.ResultsThe results showed that angiogenic supplements used in combination with low serum content gave rise to the appearance of Thy-1− HM-MSC with high proliferative potential, capable of restoring the typical HM stromal impairment. The expression of the CD271 was partially maintained. We further report an enhancement towards the osteogenic and adipogenic differentiation capacity by the Thy-1− HM-MSC subset. Despite the angiogenic treatment, the Thy-1− MSC stopped short of full endothelial differentiation.DiscussionIn this paper we provide evidence that in vitro angiogenic stimuli generate HM-MSC lacking CD90 Ag expression. The Thy-1− MSC subset is characterized by peculiar functional and phenotypic characteristics, thus supporting the role played by the microenvironment in selecting particular hMSC subsets maintaining normal tissue homeostasis or inducing pathologic processes.

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