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Search Results: 1 - 10 of 192033 matches for " Mariangela D’Onghia "
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Low Serum Urate Levels Are Associated to Female Gender in Multiple Sclerosis Patients
Stefano Zoccolella, Carla Tortorella, Pietro Iaffaldano, Vita Direnzo, Mariangela DOnghia, Elena Luciannatelli, Damiano Paolicelli, Paolo Livrea, Maria Trojano
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040608
Abstract: Background Urate is a natural antioxidant and may prevent CNS tissue damage and the clinical manifestations of experimental autoimmune encephalitis. Results from clinical studies are conflicting and the contribution of urate to the pathogenesis of Multiple Sclerosis (MS) remains uncertain. Objective To evaluate serum urate levels in MS patients and their relationships with clinical, demographic and MRI variables. Methods Levels of non-fasting serum uric acid and creatinine were determined by an automated enzymatic assay and glomerular filtration rate was assessed in 245 MS patients, in 252 age/sex-matched neurological controls (NC) and in 59 Healthy controls (HC). Results Median serum urate levels did not differ between MS patients (3.8 mg/dL), HC (4.0 mg/dl) and NC (4.0 mg/dL). Serum urate levels were lower in females than in males in all groups (p = <0.0001). In female-MS, serum urate levels (3.2 mg/dL) were lower compared to those in female HC (3.8; p = 0.01) and NC (3.5 mg/dL; p = 0.02), whereas in male-MS they(4.8 mg/dL) did not differ from those in male HC (4.5 mg/dl) and NC (4.8 mg/dL). Urate concentrations trended to be lower in Clinically isolated syndromes suggestive of MS (3.7 mg/dL) and in relapsing MS (3.7 mg/dL), compared to patients with progressive MS (4.4 mg/dL; p = 0.06), and in patients with an annual relapse rate (ARR) >2 (3.3 mg/dL) than in those with an ARR ≤2: 3.9 mg/dL; p = 0.05). Significant lower serum urate levels were found in females than in males in all clinical MS subtypes (p<0.01), separately evaluated. Female sex (beta: ?0.53; p<0.00001) was the most significant determinant of serum urate concentrations in MS patients on multivariate regression analysis. Conclusions Our findings suggest that low urate levels could be of significance in predominantly inflammatory phases of MS even at the early stage and mainly in females.
Impact of Natalizumab on Cognitive Performances and Fatigue in Relapsing Multiple Sclerosis: A Prospective, Open-Label, Two Years Observational Study
Pietro Iaffaldano, Rosa Gemma Viterbo, Damiano Paolicelli, Guglielmo Lucchese, Emilio Portaccio, Benedetta Goretti, Vita Direnzo, Mariangela D'Onghia, Stefano Zoccolella, Maria Pia Amato, Maria Trojano
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035843
Abstract: Background and Objectives Natalizumab reduces the relapse rate and magnetic resonance imaging activity in patients with Relapsing-Remitting Multiple Sclerosis (RRMS). So far the influence of natalizumab on cognitive functions and fatigue in MS remains uncertain. The aim of this prospective, open-label, observational study was to evaluate the possible effects of natalizumab on cognition and fatigue measures in RRMS patients treated for up to two years. Methods Cognitive performances were examined by the Rao's Brief Repeatable Battery (BRB), the Stroop test (ST) and the Cognitive Impairment Index (CII), every 12 months. Patients who failed in at least 3 tests of the BRB and the ST were classified as cognitively impaired (CI). Fatigue Severity Scale (FSS) was administered every 12 months to assess patient's self-reported fatigue. One hundred and 53 patients completed 1 and 2 year-natalizumab treatment, respectively. Results After 1 year of treatment the percentage of CI patients decreased from 29% (29/100) at baseline to 19% (19/100) (p = 0.031) and the mean baseline values of CII (13.52±6.85) and FSS (4.01±1.63) scores were significantly reduced (10.48±7.12, p<0.0001 and 3.61±1.56, p = 0.008). These significant effects were confirmed in the subgroup of patients treated up to two years. Conclusions These results demonstrate that a short-term NTZ treatment may significantly improve cognitive performances and fatigue in RRMS patients.
Disk-stability constraints on the number of arms in spiral galaxies
Elena D'Onghia
Physics , 2015, DOI: 10.1088/2041-8205/808/1/L8
Abstract: A model based on disk-stability criteria to determine the number of spiral arms of a general disk galaxy with an exponential disk, a bulge and a dark halo described by a Hernquist model is presented. The multifold rotational symmetry of the spiral structure can be evaluated analytically once the structural properties of a galaxy, such as the circular speed curve, and the disk surface brightness, are known. By changing the disk mass, these models are aimed at varying the critical length scale parameter of the disk and lead to a different spiral morphology in agreement with prior models. Previous studies based on the swing amplification and disk stability have been applied to constrain the mass-to-light ratio in disk galaxies. This formalism provides an analytic expression to estimate the number of arms expected by swing amplification making its application straight-forward to large surveys. It can be applied to predict the number of arms in the Milky Way as a function of radius and to constrain the mass-to-light ratio in disk galaxies for which photometric and kinematic measurements are available, like in the DiskMass survey. Hence, the halo contribution to the total mass in the inner parts of disk galaxies can be inferred in light of the ongoing and forthcoming surveys.
The Failure of Self-Interacting Dark Matter to solve the Overabundance of Dark Satellites and the Soft Core Question
Elena D'Onghia,Andreas Burkert
Physics , 2002, DOI: 10.1086/367606
Abstract: Self-interacting dark matter was proposed by Spergel & Steinhardt (2000) to alleviate two conflicts between Cold Dark Matter (CDM) models and observations. Firstly, CDM N-body simulations predict dark matter halo density profiles that diverge at the centre in disagreement with the constant density cores observed in late-type dwarf and Low Surface Brightness (LSB) galaxies. Secondly, N-body simulations predict an overabundance of subhalos in the Galactic halo. Using a simple semi-analytical argument we show that weakly self-interacting dark matter models, which can produce halo cores of the sizes observed in dark matter dominated galaxies, are unable to reconcile the number of satellites in the Galactic halo with the observed number of dwarf galaxies in the Local Group.
Improvement of Detection Methods and Further Characterization of Spiroplasma citri, the Causal Agent of Citrus Stubborn Disease in Egypt  [PDF]
Mohamed Mannaa, Anna Maria DOnghia, Khaled Djelouah, Giuseppe Cavallo, Franco Valentini
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.42032
Abstract: Stubborn disease of citrus is one of the main causes of quality deterioration of citrus fruits in Egypt. The early detection and the molecular characterization of the causal agent are vital for revealing its real distribution and for management. In 2011, several samples were collected at different times of the year from stubborn suspected symptomatic trees within the main citrus growing area in Egypt, the Nile-delta region. After culturing the causal agent on artificial LD8 media from the field fresh samples, two new and improved methods of biological indexing were set up and compared with the traditional method in order to increase the detection efficiency by increasing the greenhouse transmission rate; which reached 85% with the new inverse inoculation method. Different PCR primer pairs were evaluated for their detection efficiency of the Egyptian Isolates of Spiroplasma citri and the most specific primer pair for these local isolates was determined. Improving the efficiency of biological indexing, along with determining the most specific and efficient PCR primer pair for the detection, will enhance and facilitate the citrus certification programs in Egypt, making them better tools for the early detection of stubborn disease. Furthermore obtained Egyptian isolates were characterized molecularly by the analysis of the obtained sequences showing close relationship with the Moroccan strain (GII3).
The collective origin of spiral structures in disk galaxies
DOnghia E.,Vogelsberger M.,Hernquist L.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20121907004
Abstract: After almost fifty years the origin of spiral arms in disk galaxies remains one of the major unsolved problems in astrophysics. Recent attempts have indicated that substructures in the dark matter halos of galaxies could induce spiral patterns in disks by generating localized disturbances that grow by swing amplification. However, there are indications that dark matter substructures orbiting in the inner regions of galaxy halos would be destroyed by dynamical processes such as disk shocking, and hence would not be able to seed the formation of spiral structure. Instead, we use numerical simulations of unprecedented resolution explore the possibility that spiral arms might be generated by the dynamical response of the disk to overdensities corotating within the disk. These perturbations can be identified with fluctuations in the distribution of gas in the interstellar medium of galaxies, such as giant molecular clouds. We develop a new theory for spiral structure formation based on the non-linear effects of swing amplification. Our model makes numerous testable predictions, making it possible to finally confront theory with observations.
Self-Perpetuating Spiral Arms in Disk Galaxies
Elena D'Onghia,Mark Vogelsberger,Lars Hernquist
Physics , 2012, DOI: 10.1088/0004-637X/766/1/34
Abstract: The causes of spiral structure in galaxies remain uncertain. Leaving aside the grand bisymmetric spirals with their own well-known complications, here we consider the possibility that multi-armed spiral features originate from density inhomogeneities orbiting within disks. Using high-resolution N-body simulations, we follow the motions of stars under the influence of gravity, and show that mass concentrations with properties similar to those of giant molecular clouds can induce the development of spiral arms through a process termed swing amplification. However, unlike in earlier work, we demonstrate that the eventual response of the disk can be highly non-linear, significantly modifying the formation and longevity of the resulting patterns. Contrary to expectations, ragged spiral structures can thus survive at least in a statistical sense long after the original perturbing influence has been removed.
The Halo Density Profiles with Non-Standard N-body Simulations
Elena D'Onghia,Claudio Firmani,Guido Chincarini
Physics , 2002, DOI: 10.1046/j.1365-8711.2003.06029.x
Abstract: We propose a new numerical procedure to simulate a single dark halo of any size and mass in a hierarchical framework coupling the extended Press-Schechter formalism (EPSF) to N-body simulations. The procedure consists of assigning cosmological initial conditions to the particles of a single halo with a EPSF technique and following only the dynamical evolution using a serial N-body code. The computational box is fixed with a side of $0.5 h^{-1}$ Mpc. This allows to simulate galaxy cluster halos using appropriate scaling relations, to ensure savings in computing time and code speed. The code can describe the properties of halos composed of collisionless or collisional dark matter. For collisionless Cold Dark Matter (CDM) particles the NFW profile is reproduced for galactic halos as well as galaxy cluster halos. Using this numerical technique we study some characteristics of halos assumed to be isolated or placed in a cosmological context in presence of weak self-interacting dark matter: the soft core formation and the core collapse. The self-interacting dark matter cross section per unit mass is assumed to be inversely proportional to the particle collision velocity: $\sigma/m_{x} \propto 1/v$.
Modelling Self-Interacting CDM Haloes with a Cosmological Boltzmann Code
C. Firmani,E. D'Onghia,G. Chincarini
Physics , 2000,
Abstract: We investigate the density profiles and evolution of weakly self-interacting cold dark matter haloes using a numerical code based on the collisional Boltzmann equation. This approach is alternative to N-body techniques in following the dynamical evolution of haloes in the cosmological context and taking into account particle self-interaction. The physical case with a cross section inversely proportional to the relative velocity of the colliding particles is modelled with an unprecedented resolution, spanning five orders of magnitude on the radius for each halo. The modelled haloes cover a mass range from dwarf galaxies to galaxy clusters. We find that for \sigma v_{100} \approx 10^{-24} cm^2/GeV, where \sigma is the cross section per unit mass and v_{100} is the collision velocity in units of 100 km/s, soft cores in good agreement with observations on galactic as well as on galaxy cluster scales are obtained. Remarkably, the observed nearly invariance of the halo central density with mass is reproduced.
Detectability of Free Floating Planets in Open Clusters with JWST
Fabio Pacucci,Andrea Ferrara,Elena D'Onghia
Physics , 2013, DOI: 10.1088/2041-8205/778/2/L42
Abstract: Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, as in the Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters we determine the rate of occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate (total number of free-floating planets per unit of time, normalized by the total number of stars) is proportional to the stellar density of the cluster, with a constant of proportionality equal to (23 +/- 5)10^-6 pc^3 Myr^-1. For the Pleiades (M45) we predict that about 26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the NIR band. Assuming a surface temperature of the planet of 500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux @4.4 micron of approximately 400 nJy, which would lead to a very clear detection (S/N of order 100) in only one hour of integration.
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