DSpace Cris Angular :: Sfogliando Publications SISSA per Titolo

Pubblicazione

1 Body plan genes and human malformation

( 1998)

Boncinelli E.

;

Mallamaci A.

;

Broccoli V.

WOS© Citazioni 4 45

Pubblicazione

1D periodic potentials with gaps vanishing at k=0

( 2009)

Zagordi O.

;

Michelangeli A.

Appearance of energy bands and gaps in the dispersion relations of a periodic potential is a standard feature of Quantum Mechanics. We investigate the class of one-dimensional periodic potentials for which all gaps vanish at the center of the Brillouin zone. We characterize them through a necessary and sufficient condition. Potentials of the form we focus on arise in different fields of Physics, from supersymmetric Quantum Mechanics, to Korteweg-de Vries equation theory and classical diffusion problems. The O.D.E. counterpart to this problem is the characterisation of periodic potentials for which coexistence occur of linearly independent solutions of the corresponding Schroedinger equation (Hill's equation). This result is placed in perspective of the previous related results available in the literature.

5

Pubblicazione

1ST-PRINCIPLES CALCULATION OF THE VIBRATIONAL PROPERTIES OF GAXAL1-XAS ALLOYS

( 1990)

BARONI, S

;

DE GIRONCOLI, S

;

GIANNOZZI, P

Pubblicazione

1WGA J1216.9+3743: Chandra finds an extremely steep ultraluminous X-ray source

( 2003)

Cagnoni, I.

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Turolla, R.

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Treves, A.

;

Huang, J. -S.

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Kim, D. W.

;

Elvis, M.

;

Celotti, A.

We report the discovery of a new ultraluminous X-ray source (ULX) in the nearby galaxy NGC 4244 from Chandra archival data. The source, 1WGA J1216.9+3743, is one of the least luminous and softest ULXs discovered so far. Its X-ray spectrum is the best available for a representative of the soft ULXs, a class of sources recently discovered by Chandra and XMM-Newton. 1WGA J1216.9+3743 appears pointlike in the Chandra image and has a complex spectral shape; a multicolor disk model, suitable for brighter ULXs, is inadequate for this source. The 1WGA J1216.9+3743 spectrum is heavily absorbed (N-H similar to 1-4 x 10(21) cm(-2)) and very soft. The best-fit power-law model gives Gamma similar to 5 and implies a luminosity L(0.5-10 keV) similar to 10(39) ergs s(-1). A comparison with previous detections shows that, despite the variability displayed by the source during the Chandra observation, the 1WGA J1216.9+3743 count rate, spectral shape, and absorption are practically unchanged over a 9 yr period. We also performed deep optical imaging of the field containing the X-ray source and found a possible R similar to 23.7 counterpart.

WOS© Citazioni 9 3

Pubblicazione

1WGA J1226.9 + 3332: A high-redshift cluster discovered by Chandra

( 2001)

Cagnoni I.

;

Elvis M.

;

Kim D. -W.

;

Mazzotta P.

;

Huang J. -S.

;

Celotti A.

We report the detection of 1WGA J1226.9+3332 as an arcminute-scale extended X-ray source with the Chandra X-Ray Observatory. The Chandra observation and R- and K-band imaging strongly support the identification of 1WGA 1226.9+3332 as a high-redshift cluster of galaxies, most probably at z = 0.85 +/- 0.15, with an inferred temperature kT = 10(-3)(+4) keV, and an unabsorbed luminosity (in a r = 120" aperture) of 1.3(-0.14)(+0.16) x 10(45) ergs s(-1) (0.5-10 keV). This indication of redshift is also supported by the K- and R-band imaging and is in agreement with the spectroscopic redshift of 0.89 found by Ebeling and coworkers. The surface brightness profile is consistent with a beta model with beta = 0.770 +/- 0.025, r(c) = 18."1+/-0."9 (corresponding to 101 +/- 5 kpc at z = 0.89), and S(0) = 1.02 +/- 0.08 counts arcsec(-2). 1WGA J1226.9+3332 was selected as an extreme X-ray-loud source with F-X/F-V >60; this selection method, thanks to the large area sampled, seems to be a highly efficient method for finding luminous, high-z clusters of galaxies.

Scopus© Citazioni 15WOS© Citazioni 17 6

Pubblicazione

2 x 2 systems of conservation laws with L-infinity data

( 2010)

Bianchini, Stefano

;

Colombo, R. M.

;

Monti, F.

Consider a hyperbolic system of conservation laws with genuinely nonlinear characteristic fields. We extend the classical Glimm–Lax result proving the existence of solutions for L∞ initial datum, relaxing the assumptions taken therein on the geometry of the shock–rarefaction curves.

Scopus© Citazioni 5WOS© Citazioni 5 6

Pubblicazione

2+1 gravity with positive cosmological constant in LQG: a proposal for the physical state

( 2011)

Pranzetti D.

In this paper, I investigate the possible quantization, in the context of loop quantum gravity, of three-dimensional gravity in the case of positive cosmological constant and try to make contact with alternative quantization approaches already existing in the literature. Due to the appearance of an anomaly in the constraints algebra, previously studied as a first step of the analysis, alternative techniques developed for the quantization of systems with constraints algebras not associated with a structure Lie group need to be adopted. Therefore, I introduce an ansatz for a physical state, which gives some transition amplitudes in agreement with what one would expect from the TuraevViro model. Moreover, in order to check that this state implements the right dynamics, I show that it annihilates the master constraint for the theory up to the first order in Λ. © 2011 IOP Publishing Ltd.

Scopus© Citazioni 7WOS© Citazioni 7 2

Pubblicazione

2+1 Quantum de Sitter Gravity

(SISSA, 1989-10-27)

3

Pubblicazione

2-d stability of the Neel wall

( 2006)

DeSimone A.

;

Knupfer H.

;

Otto F.

We are interested in thin-film samples in micromagnetism, where the magnetization m is a 2-d unit-length vector field. More precisely we are interested in transition layers which connect two opposite magnetizations, so called Néel walls. We prove stability of the 1-d transition layer under 2-d perturbations. This amounts to the investigation of the following singularly perturbed energy functional: E2d(m)= ε ∫ |∇m| 2dx + 1/2 ∫ |∇-1/2∇̇m|2dx. The topological structure of this two-dimensional problem allows us to use a duality argument to infer the optimal lower bound. The lower bound relies on an ε-perturbation of the following logarithmically failing interpolation inequality ∫ |∇1/2/φ|2dx ¬ sup|φ| ∫ |∇φ|dx.

WOS© Citazioni 32 6

Pubblicazione

2-qubit quantum state transfer in spin chains and cold atoms with weak links

( 2017)

Lorenzo, Salvatore

;

Apollaro, Tony J. G.

;

Trombettoni, Andrea

;

Paganelli, Simone

In this paper we discuss the implementation of 2-qubit quantum state transfer (QST) in inhomogeneous spin chains where the sender and the receiver blocks are coupled through the bulk channel via weak links. The fidelity and the typical timescale of the QST are discussed as a function of the parameters of the weak links. Given the possibility of implementing with cold atoms in optical lattices a variety of condensed matter systems, including spin systems, we also discuss the possible implementation of the discussed 2-qubit QST with cold gases with weak links, together with a discussion of the applications and limitations of the presented results.

Scopus© Citazioni 6WOS© Citazioni 8 1

Pubblicazione

2000 CKM-triangle analysis. A critical review with updated experimental inputs and theoretical parameters

( 2001)

Ciuchini, M.

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D'Agostini, G

;

Franco, E.

;

Lubicz, V.

;

Martinelli, Guido

;

Parodi, F.

;

Roudeau, P.

;

Stocchi, A.

Within the Standard Model, a review of the current determination of the sides and angles of the CKM unitarity triangle is presented, using experimental constraints from the measurements of \ epsilon (K)\, \V-ub/V-cb\, Deltam(d) and from the limit on Deltam(s), available in September 2000. Results from the experimental search for B-s(0)-(B) over bar (0)(s) oscillations are introduced in the present analysis using the likelihood. Special attention is devoted to the determination of the theoretical uncertainties. The purpose of the analysis is to infer regions where the parameters of interest lie with given probabilities. The BaBar "95% C.L. scanning" method is also commented.

Scopus© Citazioni 136WOS© Citazioni 219 4

Pubblicazione

2009 Anno dell'Astronomia : L'immagine di Galileo tra organizzatori e cittadini della Toscana

(SISSA, 2009-02)

9

Pubblicazione

21 cm intensity mapping cross-correlation with galaxy surveys: Current and forecasted cosmological parameters estimation for the SKAO

( 2024)

Berti M.

;

Spinelli M.

;

Viel M.

We present a comprehensive set of forecasts for the cross-correlation signal between 21 cm intensity mapping and galaxy redshift surveys. We focus on the data sets that will be provided by the SKAO for the 21 cm signal, DESI and Euclid for galaxy clustering. We build a likelihood which takes into account the effect of the beam for the radio observations, the Alcock-Paczynski effect, a simple parametrization of astrophysical nuisances, and fully exploit the tomographic power of such observations in the range z = 0.7-1.8 at linear and mildly non-linear scales (k < 0.25h Mpc-1). The forecasted constraints, obtained with Monte Carlo Markov Chains techniques in a Bayesian framework, in terms of the six base parameters of the standard ΛCDM model, are promising. The predicted signal-to-noise ratio for the cross-correlation can reach ∼50 for z ∼1 and k ∼0.1h Mpc-1. When the cross-correlation signal is combined with current Cosmic Microwave Background (CMB) data from Planck, the error bar on and H0 is reduced by factors 3 and 6, respectively, compared to CMB only data, due to the measurement of matter clustering provided by the two observables. The cross-correlation signal has a constraining power that is comparable to the autocorrelation one and combining all the clustering measurements a sub-per cent error bar of 0.33 per cent on H0 can be achieved, which is about a factor 2 better than CMB only measurements. Finally, as a proof of concept, we test the full pipeline on the real data measured by the MeerKat collaboration (Cunnington et al. 2022) presenting some (weak) constraints on cosmological parameters.

Pubblicazione

21cmemu: an emulator of 21cmfast summary observables

( 2024)

Breitman, Daniela

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Mesinger, Andrei

;

Murray, Steven G

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Prelogović, David

;

Qin, Yuxiang

;

Trotta, Roberto

Recent years have witnessed rapid progress in observations of the epoch of reionization (EoR). These have enabled high-dimensional inference of galaxy and intergalactic medium (IGM) properties during the first billion years of our Universe. However, even using efficient, seminumerical simulations, traditional inference approaches that compute 3D lightcones on-The-fly can take 105 core hours. Here we present 21cmemu: An emulator of several summary observables from the popular 21cmfast simulation code. 21cmemu takes as input nine parameters characterizing EoR galaxies, and outputs the following summary statistics: (i) the IGM mean neutral fraction; (ii) the 21-cm power spectrum; (iii) the mean 21-cm spin temperature; (iv) the sky-Averaged (global) 21-cm signal; (vi) the ultraviolet (UV) luminosity functions (LFs); and (vii) the Thomson scattering optical depth to the cosmic microwave background (CMB). All observables are predicted with sub-per cent median accuracy, with a reduction of the computational cost by a factor of over 104. After validating inference results, we showcase a few applications, including: (i) quantifying the relative constraining power of different observational data sets; (ii) seeing how recent claims of a late EoR impact previous inferences; and (iii) forecasting upcoming constraints from the sixth observing season of the Hydrogen Epoch of Reionization Array (HERA) telescope. 21cmemu is publicly available, and is included as an alternative simulator in the public 21cmmc sampler.

Pubblicazione

22Ne and 23Na ejecta from intermediate-mass stars: the impact of the new LUNA rate for 22Ne(p, γ)23Na

( 2017)

Slemer, A.

;

Marigo, P.

;

Piatti, D.

;

Aliotta, M.

;

Bemmerer, D.

;

Best, A.

;

Boeltzig, A.

;

Bressan, Alessandro

;

Broggini, C.

;

Bruno, C. G.

;

Caciolli, A.

;

Cavanna, F.

;

Ciani, G. F.

;

Corvisiero, P.

;

Davinson, T.

;

Depalo, R.

;

Di Leva, A.

;

Elekes, Z.

;

Ferraro, F.

;

Formicola, A.

;

Fülöp, Z.s.

;

Gervino, G.

;

Guglielmetti, A.

;

Gustavino, C.

;

Gyürky, G.

;

Imbriani, G.

;

Junker, M.

;

Menegazzo, R.

;

Mossa, V.

;

Pantaleo, F. R.

;

Prati, P.

;

Straniero, O.

;

Szücs, T.

;

Takács, M. P.

;

Trezzi, D.

We investigate the impact of the new LUNA rate for the nuclear reaction 22Ne(p, γ)23Na on the chemical ejecta of intermediate-mass stars, with particular focus on the thermally pulsing asymptotic giant branch (TP-AGB) stars that experience hot-bottom burning. To this aim, we use the PARSEC and COLIBRI codes to compute the complete evolution, from the premain sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range 3.0-6.0M⊙ and metallicities Zi = 0.0005, 0.006 and 0.014. We find that the new LUNA measures have much reduced the nuclear uncertainties of the 22Ne and 23Na AGB ejecta that drop from factors of ≃10 to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of 23Na, the uncertainties that still affect the 22Ne and 23Na AGB ejecta are mainly dominated by the evolutionary aspects (efficiency of mass-loss, third dredge-up, convection). Finally, we discuss how the LUNA results impact on the hypothesis that invokes massive AGB stars as the main agents of the observed O-Na anticorrelation in Galactic globular clusters. We derive quantitative indications on the efficiencies of key physical processes (mass-loss, third dredgeup, sodium destruction) in order to simultaneously reproduce both the Na-rich, O-poor extreme of the anticorrelation and the observational constraints on the CNO abundance. Results for the corresponding chemical ejecta are made publicly available. © 2016 The Authors.

Pubblicazione

2D MXene interfaces preserve the basal electrophysiology of targeted neural circuits

( 2022)

Xiao, M.

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Li, X.

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Pifferi, S.

;

Pastore, B.

;

Liu, Y.

;

Lazzarino, M.

;

Torre, V.

;

Yang, X.

;

Menini, A.

;

Tang, M.

Neural interfaces enable the monitoring of the state of the brain and its composite cell networks, as well as stimulate them to treat nervous disorders. In addition to their highly efficient charge transduction and stability during operation, the neural electrodes should avoid altering the physiological properties of targeted neuronal tissues. Two-dimensional (2D) MXene materials integrate the advantages of metallic conductivity, high specific-surface area and surface functionality in aqueous dispersions, showing promising potential in neural interface applications. Here, we apply uncoated Ti3C2Tx MXene to interface neuronal development. The impacts of the uncoated Ti3C2Tx MXene interface on neuronal development and neuronal microcircuit activity were tested for the first time. Compared to the standard neuronal culture with a poly-l-ornithine coated coverslip, uncoated Ti3C2Tx MXene surfaces did not affect the cell morphology, density, neuron ratios, maturation or the compositions of the neuronal network. Moreover, calcium imaging, spontaneous postsynaptic currents (sPSCs) and also miniature postsynaptic currents (mPSCs) were recorded to demonstrate that Ti3C2Tx MXene interfaces preserved the basal physiology of neuronal activity. The ability to interface neuronal circuit development without altering neuronal signaling properties enables the construction of MXene-based neural prosthetic devices for neuroscience research, diagnosis, and therapies.

Pubblicazione

2d N=2 Landau-Ginzburg Models

(SISSA, 1990-10-26)

2

Pubblicazione

2′,3′-O-Substituted ATP derivatives as potent antagonists of purinergic P2X3 receptors and potential analgesic agents

( 2017)

Dal Ben, Diego

;

Thomas, Ajiroghene

;

Lambertucci, Catia

;

Spinaci, Andrea

;

Marucci, Gabriella

;

Volpini, Rosaria

;

Marchenkova, Anna

;

Nistri, Andrea

Blocking membrane currents evoked by the activation of purinergic P2X3 receptors localized on nociceptive neurons represents a promising strategy for the development of agents useful for the treatment of chronic pain conditions. Among compounds endowed with such antagonistic action, 2â 2,3â 2-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP) is an ATP analogue, whose inhibitory activity on P2X receptors has been previously reported. Based on the results of molecular modelling studies performed with homology models of the P2X3 receptor, novel adenosine nucleotide analogues bearing cycloalkyl or arylalkyl substituents replacing the trinitrophenyl moiety of TNP-ATP were designed and synthesized. These new compounds were functionally evaluated on native P2X3 receptors from mouse trigeminal ganglion (TG) sensory neurons using patch clamp recordings under voltage clamp configuration. Our data show that some of these molecules are potent (nanomolar range) and reversible inhibitors of P2X3 receptors, without any apparent effect on trigeminal GABAA and 5-HT3 receptors, whose membrane currents were unaffected by the tested compounds.

Pubblicazione

(3+1) massive Dirac fermions with ultracold atoms in frustrated cubic optical lattices

( 2010)

Lepori L.

;

Mussardo G.

;

Trombettoni A.

We propose the experimental realization of (3+1) relativistic Dirac fermions using ultracold atoms in a cubic optical lattice in a frustrating magnetic field which can be realized by rotating the lattice or, alternatively, using a synthetic gauge field. We show that it is possible to give mass to the Dirac fermions by coupling the ultracold atoms to a Bragg pulse: the method relies on the peculiar position of the Dirac points in the (magnetic) Brillouin zone, and it would not generally work for other lattices (e.g., for honeycomb lattices). A dimensional crossover from (3+1) to (2+1) Dirac fermions can be obtained by varying the anisotropy of the lattice. Finally, we also discuss under which conditions the interatomic potentials give rise to relativistically invariant interactions among the Dirac fermions.

Pubblicazione

3-dimensional left-invariant sub-Lorentzian contact structures

( 2016)

Grochowski, M.

;

Warhurst, B.

;

MEDVEDEV, Alexandr

We provide a classification of ts-invariant sub-Lorentzian structures on 3 dimensional contact Lie groups. Our approach is based on invariants arising form the construction of a normal Cartan connection. © 2016 Elsevier B.V.

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