170,016 research outputs found
Connecting Irreversible to Reversible Aggregation: Time and Temperature
No full textWe report molecular dynamics simulations of a gel-forming mixture of ellipsoidal patchy particles with different functionality. We show that in this model, which disfavors the formation of bond-loops, elapsed time during irreversible aggregation-leading to the formation of an extended network-can be formally correlated with equilibrium temperature in reversible aggregation. We also show that it is possible to develop a parameter-free description of the self-assembly kinetics, bringing reversible and irreversible aggregation of loopless branched systems to the same level of understanding as equilibrium polymerization
Modeling the Crossover between Chemically and Diffusion-Controlled Irreversible Aggregation in a Small-Functionality Gel-Forming System
No full textThe analysis of realistic numerical simulations of a gel-forming irreversible aggregation process provides information on the role of cluster diffusion in controlling the late stages of the aggregation kinetics. Interestingly, the crossover from chemically controlled to diffusion-controlled aggregation takes place well beyond percolation, after most of the particles have aggregated in the spanning network and only small clusters remain in the sol. The simulation data are scrutinized to gain insight into the origin of this crossover. We show that a single additional time scale (related to the average diffusion time) is sufficient to provide an accurate description of the evolution of the extent of reaction at all times
Madri da mille giorni: dinamiche di impoverimento, risorse e strategie di resilienza dei nuclei familiari
No full textCurare e curarsi nella marginalità: i risultati dell’Indagine su senza dimora, salute e accesso alle cure in Toscana
No full textSenza Misura: studio longitudinale della povertà e della percezione delle politiche di contrasto
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
L’occupazione alla prova versus la prova dell’occupazione. Percorsi progettuali e reputazionali nell’esperienza dei social workers del terzo settore
Get PDFL’indagine ha concentrato la sua attenzione sui lavoratori del sociale afferenti adenti del terzo settore attualmente occupati su progetti di reinserimento lavorativo nel tentativo di analizzare caratteristiche, modalità operative, problematiche della loro attività professionale.
Dopo avere approfondito nei precedenti Rapporti dell’Osservatorio Sociale Regionale su povertà e inclusione sociale in Toscana (2021 e 2022) la situazione lavorativa degli assistenti sociali all’interno dei servizi pubblici, infatti, è emersa la necessità di approfondire anche lo spaccato parallelo e contiguo, talvolta inseparabile, di coloro che, con professionalità differenti compresa quella di assistente sociale, operano nel sempre più diffuso e sussidiario ambito del terzo settore
CHANGES IN THE DYNAMICS OF SUPERCOOLED SYSTEMS REVEALED BY DIELECTRIC SPECTROSCOPY
No full textThe dynamics of monoepoxy, diepoxy, and triepoxy glass-formers from below to above the glass transition temperature, T-g, has been investigated through the temperature behavior of relaxation times, strengths, and conductivity, determined in a wide frequency range (10(2)-2x10(10) Hz). In all systems the main and secondary relaxations define a splitting temperature T(S)similar to 1.3xT(g); moreover, a crossover temperature T(B)similar to T-S is recognized, marking the separation between two different Vogel-Fulcher regimes for the structural dynamics. The strengths behavior reflects the distribution of the overall energy between the relaxation processes and no peculiar behavior is revealed at T-S. A strong increase characterizes the strength of the secondary relaxation on crossing the glass transition from the lower temperatures. Conductivity data have been analyzed to test the dynamics in terms of the Debye-Stokes-Einstein (DSE) diffusion law. The prediction of the DSE model is well verified for mono- and diepoxide up to the high viscosity regime, while a fractional DSE law with exponent similar to 0.81, accounting for a decoupling between translational and rotational motions, replaces the DSE relation in triepoxide for temperatures below T-S. The change of the structural dynamics, the splitting between main and secondary relaxation and the breakdown of the DSE behavior, all occur within a narrow temperature range around T-S; this finding argues in favor of the existence of a change of the dynamics in the supercooled liquid state well above the glass transition temperature. (C) 1999 American Institute of Physics. [S0021-9606(99)50444-3]
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
A parameter-free description of the kinetics of formation of loop-less branched structures and gels
No full textWe study, via Brownian dynamics simulation, the kinetics of formation of branched loop-less structures for a mixture of particles with functionalities of two and three, the three-functional ones providing the branching points in the resulting network. We show that for this system, by combining the appropriate Smoluchowski rate equations, including condensation and fragmentation terms, with the thermodynamic perturbation theory of Wertheim, it is possible to provide a parameter-free description of the assembly process, even in the limit of irreversible aggregation (low T). Our work provides evidence of a connection between physical and chemical gelation in low-valence particle systems, properly relating aging (or curing) time with temperature
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