CiteULike: Author Gabrielli

First finding of Dirofilaria repens in a natural population of Aedes albopictus.

G Cancrini — 2008-07-21T08:16:50-00:00

Medical and veterinary entomology, Vol. 17, No. 4. (December 2003), pp. 448-451.

The invasive mosquito Aedes albopictus (Skuse) (Diptera: Culicidae) has become widespread in Italy during the past decade. Also Italy has foci of canine filariasis caused by Dirofilaria (Spirurida: Onchocercidae), due to subcutaneous D. repens Railliet & Henry as well as the dog heartworm D. immitis (Leidy) transmitted by various vector mosquitoes (Diptera: Culicidae). In 2002, at Fiumicino, west of Rome (Lazio Region), 17% of dogs were found to have D. repens microfilariae in peripheral blood. To evaluate the role of Ae. albopictus as a vector of Dirofilaria in this area, female mosquitoes were collected daily, June-October 2002, landing on dog or human bait in a rural house at Focene. Mosquitoes were maintained at 27 degrees C and 70% RH for 6 days, to allow development or purging of filaria larvae, then identified and frozen for subsequent molecular assay with filaria-specific ribosomal S2-S16 primers. To distinguish specimens harbouring infective L3 Dirofilaria larvae, DNA was extracted separately from the mosquito abdomen and head-thorax. Dirofilaria species were identified by sequencing, confirmed by polymerase chain reaction of positive specimens using primers specific for D. immitis and D. repens. Dirofilaria DNA was detected in 3/154 (2%) of Ae. albopictus females examined: D. repens DNA in head-thorax and abdomen of one collected 27th July; D. immitis in the abdomen of one collected 24th September; DNA of both D. immitis and D. repens in the head-thorax of one collected 11th October 2002. Thus Ae. albopictus is a potential vector of both Dirofilarias in Italy, representing risks for veterinary and human health.

Aedes albopictus and Culex pipiens implicated as natural vectors of Dirofilaria repens in central Italy.

G Cancrini — 2008-07-21T08:02:32-00:00

Journal of medical entomology, Vol. 44, No. 6. (November 2007), pp. 1064-1066.

To identify the natural vectors of Dirofilaria repens Railliet et Henry, entomological samplings were carried out in four sites within the Lazio region, foci of canine subcutaneous dirofilariasis. Collections were made in 2002-2003 by means of dog-baited and miniature Centers for Disease Control and Prevention traps as well as on humans. Microscopy identified 1576 attracted mosquito females as belonging to six species, but molecular diagnostics detected filarial DNA only in Culex pipiens L. and Aedes albopictus (Skuse, 1894). Dirofilaria immitis Leidy DNA, D. repens DNA, or both were found in the head and thorax of both mosquitoes. The simultaneous presence of vectors showing diurnal and nocturnal activity patterns is of concern for animal and human health. The finding of D. immitis DNA in mosquitoes in areas where only D. repens was been recovered in dogs also demonstrates that this filarial parasite circulates among carnivores (wild or domesticated pets).

Intellectual performance in children of alcoholics.

WF Gabrielli — 2008-07-19T22:08:46-00:00

The Journal of nervous and mental disease, Vol. 171, No. 7. (July 1983), pp. 444-447.

Alcoholics tend to show some cognitive deficits relative to nonalcoholics. The present study of a sample from a Danish birth cohort examined whether these deficits might be present in children at high risk for later alcoholism. The subjects were tested at age 12 with a Danish translation of the Weschler Intelligence Scale for Children. Risk status for later alcoholism was defined by parental alcoholism as determined by interview and medical records. Results suggest that Performance IQ deficits may be consequential to alcoholism whereas Verbal deficits (characteristic of the high risk children) may be antecedent to alcoholism.

Remus: a security-enhanced operating system

Massimo Bernaschi — 2006-05-26T15:55:59-00:00

ACM Trans. Inf. Syst. Secur., Vol. 5, No. 1. (February 2002), pp. 36-61.

We present a detailed analysis of the UNIX system calls and classify them according to their level of threat with respect to system penetration. Based on these results, an effective mechanism is proposed to control the invocation of critical, from the security viewpoint, system calls. The integration into existing UNIX operating systems is carried out by instrumenting the code of the system calls in such a way that the execution is granted only in the case where the invoking process and the value of the arguments comply with the rules held in an access control database. This method does not require changes in the kernel data structures and algorithms. All kernel modifications are transparent to the application processes that continue to work correctly with no need of source code changes or recompilation. A working prototype has been implemented as a loadable kernel module for the Linux operating system. The prototype is able to detect and block any attacks by which an intruder tries to gain direct access to the system as a privileged user.

A comparison of two antimicrobial-impregnated central venous catheters. Catheter Study Group.

RO Darouiche — 2008-07-03T05:03:29-00:00

The New England journal of medicine, Vol. 340, No. 1. (7 January 1999), pp. 1-8.

BACKGROUND: The use of central venous catheters impregnated with either minocycline and rifampin or chlorhexidine and silver sulfadiazine reduces the rates of catheter colonization and catheter-related bloodstream infection as compared with the use of unimpregnated catheters. We compared the rates of catheter colonization and catheter-related bloodstream infection associated with these two kinds of antiinfective catheters. METHODS: We conducted a prospective, randomized clinical trial in 12 university-affiliated hospitals. High-risk adult patients in whom central venous catheters were expected to remain in place for three or more days were randomly assigned to undergo insertion of polyurethane, triple-lumen catheters impregnated with either minocycline and rifampin (on both the luminal and external surfaces) or chlorhexidine and silver sulfadiazine (on only the external surface). After their removal, the tips and subcutaneous segments of the catheters were cultured by both the roll-plate and the sonication methods. Peripheral-blood cultures were obtained if clinically indicated. RESULTS: Of 865 catheters inserted, 738 (85 percent) produced culture results that could be evaluated. The clinical characteristics of the patients and the risk factors for infection were similar in the two groups. Catheters impregnated with minocycline and rifampin were 1/3 as likely to be colonized as catheters impregnated with chlorhexidine and silver sulfadiazine (28 of 356 catheters [7.9 percent] vs. 87 of 382 [22.8 percent], P<0.001), and catheter-related bloodstream infection was 1/12 as likely in catheters impregnated with minocycline and rifampin (1 of 356 [0.3 percent], vs. 13 of 382 [3.4 percent] for those impregnated with chlorhexidine and silver sulfadiazine; P<0.002). CONCLUSIONS: The use of central venous catheters impregnated with minocycline and rifampin is associated with a lower rate of infection than the use of catheters impregnated with chlorhexidine and silver sulfadiazine.

Visualizing locations of off-screen objects on mobile devices: a comparative evaluation of three approaches

Stefano Burigat — 2008-03-24T21:21:20-00:00

(2006), pp. 239-246.

Clustering and coalescence from multiplicative noise: the Kraichnan ensemble

Andrea Gabrielli — 2008-05-28T15:17:36-00:00

Journal of Physics A: Mathematical and Theoretical, Vol. 41, No. 23. (2008), 235003.

We study the dynamics of the two-point statistics of the Kraichnan ensemble which describes the transport of a passive pollutant by a stochastic turbulent flow characterized by scale invariant structure functions. The fundamental equation of this problem consists of the Fokker-Planck equation for the two-point correlation function of the density of particles performing spatially correlated Brownian motions with scale invariant correlations. This problem is equivalent to the stochastic motion of an effective particle driven by a generic multiplicative noise. In this paper, we propose an alternative and more intuitive approach to the problem than the original one (Gawedzki and Vergassola 2000 Physica D 138 63) leading to the same conclusions. The general features of this new approach make possible to fit it to other more complex contexts.

Molecular characterization of human breast tumor vascular cells.

R Bhati — 2008-05-23T15:58:58-00:00

The American journal of pathology, Vol. 172, No. 5. (May 2008), pp. 1381-1390.

A detailed understanding of the assortment of genes that are expressed in breast tumor vessels is needed to facilitate the development of novel, molecularly targeted anti-angiogenic agents for breast cancer therapies. Rapid immunohistochemistry using factor VIII-related antibodies was performed on sections of frozen human luminal-A breast tumors (n = 5) and normal breast (n = 5), followed by laser capture microdissection of vascular cells. RNA was extracted and amplified, and fluorescently labeled cDNA was synthesized and hybridized to 44,000-element long-oligonucleotide DNA microarrays. Statistical analysis of microarray was used to compare differences in gene expression between tumor and normal vascular cells, and Expression Analysis Systematic Explorer was used to determine enrichment of gene ontology categories. Protein expression of select genes was confirmed using immunohistochemistry. Of the 1176 genes that were differentially expressed between tumor and normal vascular cells, 55 had a greater than fourfold increase in expression level. The extracellular matrix gene ontology category was increased while the ribosome gene ontology category was decreased. Fibroblast activation protein, secreted frizzled-related protein 2, Janus kinase 3, and neutral sphingomyelinase 2 proteins localized to breast tumor endothelium as assessed by immunohistochemistry, showing significantly greater staining compared with normal tissue. These tumor endothelial marker proteins also exhibited increased expression in breast tumor vessels compared with that in normal tissues. Therefore, these genetic markers may serve as potential targets for the development of angiogenesis inhibitors.

An effective strategy for the use of commercial full-wave simulators in the design of waveguide filters and diplexers

A Morini — 2008-05-08T06:36:17-00:00

Microwave Conference, 2003. 33rd European, Vol. 1 (2003), pp. 211-213 Vol.1.

The paper presents a strategy for the design of waveguide filters and diplexers, with the help of commercially available 3D full-wave simulators. The problem in hand is subdivided into an appropriate number of well defined steps, starting from the choice of the circuit prototype to the final full-wave EM simulation. The computational effort is adequate and, often, the overall design time for the complete design is reduced to less than 1 day. One example, concerning a WR12 filter, employing non-standard coupling elements is discussed.

Histone deacetylase inhibitors induce mitotic slippage

FE Stevens — 2007-09-17T15:46:10-00:00

Oncogene, Vol. aop, No. current.

Things aren't what they seem to be: innovation through technology inspiration

Yvonne Rogers — 2006-11-21T22:54:39-00:00

(2002), pp. 373-378.

Gravitational dynamics of an infinite shuffled lattice: Particle coarse-graining, nonlinear clustering, and the continuum limit

T Baertschiger — 2008-03-10T16:55:57-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 1. (2007)

We study the evolution under their self-gravity of particles evolving from infinite “shuffled lattice” initial conditions. We focus here specifically on the comparison between the evolution of such a system and that of “daughter” coarse-grained particle distributions. These are sparser (i.e., lower density) particle distributions, defined by a simple coarse-graining procedure, which share the same large-scale mass fluctuations. We consider both the case that such coarse-grainings are performed (i) on the initial conditions, and (ii) at a finite time with a specific additional prescription. In numerical simulations we observe that, to a first approximation, these coarse-grainings represent well the evolution of the two-point correlation properties over a significant range of scales. We note, in particular, that the form of the two-point correlation function in the original system, when it is evolving in the asymptotic “self-similar” regime, may be reproduced well in a daughter coarse-grained system in which the dynamics are still dominated by two-body (nearest neighbor) interactions. This provides a simple physical description of the origin of the form of part of the asymptotic nonlinear correlation function. Using analytical results on the early time evolution of these systems, however, we show that small observed differences between the evolved system and its coarse-grainings at the initial time will in fact diverge as the ratio of the coarse-graining scale to the original interparticle distance increases. The second coarse-graining studied, performed at a finite time in a specified manner, circumvents this problem. It also makes it more physically transparent why gravitational dynamics from these initial conditions tends toward a self-similar evolution. We finally discuss the precise definition of a limit in which a continuum (specifically Vlasov-type) description of the observed linear and nonlinear evolution should be applicable. This requires the introduction of an additional intrinsic length scale (e.g., a physical smoothing in the force at small scales), which is kept fixed as the particle density diverges. In this limit the different coarse-grainings are equivalent and leave the evolution of the “mother” system invariant.

Gravitational dynamics of an infinite shuffled lattice of particles

T Baertschiger — 2008-03-10T16:54:38-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 2. (2007)

We study, using numerical simulations, the dynamical evolution of self-gravitating point particles in static Euclidean space, starting from a simple class of infinite “shuffled lattice” initial conditions. These are obtained by applying independently to each particle on an infinite perfect lattice a small random displacement, and are characterized by a power spectrum (structure factor) of density fluctuations which is quadratic in the wave number k, at small k. For a specified form of the probability distribution function of the “shuffling” applied to each particle, and zero initial velocities, these initial configurations are characterized by a single relevant parameter: the variance 2 of the “shuffling” normalized in units of the lattice spacing . The clustering, which develops in time starting from scales around , is qualitatively very similar to that seen in cosmological simulations, which begin from lattices with applied correlated displacements and incorporate an expanding spatial background. From very soon after the formation of the first nonlinear structures, a spatiotemporal scaling relation describes well the evolution of the two-point correlations. At larger times the dynamics of these correlations converges to what is termed “self-similar” evolution in cosmology, in which the time dependence in the scaling relation is specified entirely by that of the linearized fluid theory. Comparing simulations with different , different resolution, but identical large scale fluctuations, we are able to identify and study features of the dynamics of the system in the transient phase leading to this behavior. In this phase, the discrete nature of the system explicitly plays an essential role.

Force distribution in a randomly perturbed lattice of identical particles with 1/r[sup 2] pair interaction

Andrea Gabrielli — 2008-03-10T16:53:37-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 74, No. 2. (2006)

We study the statistics of the force felt by a particle in the class of a spatially correlated distribution of identical pointlike particles, interacting via a 1/r2 pair force (i.e., gravitational or Coulomb), and obtained by randomly perturbing an infinite perfect lattice. We specify the conditions under which the force on a particle is a well-defined stochastic quantity. We then study the small displacements approximation, giving both the limitations of its validity and, when it is valid, an expression for the force variance. The method introduced by Chandrasekhar to find the force probability density function for the homogeneous Poisson particle distribution is extended to shuffled lattices of particles. In this way, we can derive an approximate expression for the probability distribution of the force over the full range of perturbations of the lattice, i.e., from very small (compared to the lattice spacing) to very large where the Poisson limit is recovered. We show in particular the qualitative change in the large-force tail of the force distribution between these two limits. Excellent accuracy of our analytic results is found on detailed comparison with results from numerical simulations. These results provide basic statistical information about the fluctuations of the interactions (i) of the masses in self-gravitating systems like those encountered in the context of cosmological N-body simulations, and (ii) of the charges in the ordered phase of the one-component plasma, the so-called Coulomb or Wigner crystal.

Linear perturbative theory of the discrete cosmological N-body problem

B Marcos — 2008-03-10T16:52:13-00:00

Physical Review D (Particles, Fields, Gravitation, and Cosmology), Vol. 73, No. 10. (2006)

We present a perturbative treatment of the evolution under their mutual self-gravity of particles displaced off an infinite perfect lattice, both for a static space and for a homogeneously expanding space as in cosmological N-body simulations. The treatment, analogous to that of perturbations to a crystal in solid state physics, can be seen as a discrete (i.e. particle) generalization of the perturbative solution in the Lagrangian formalism of a self-gravitating fluid. Working to linear order, we show explicitly that this fluid evolution is recovered in the limit that the initial perturbations are restricted to modes of wavelength much larger than the lattice spacing. The full spectrum of eigenvalues of the simxple cubic lattice contains both oscillatory modes and unstable modes which grow slightly faster than in the fluid limit. A detailed comparison of our perturbative treatment, at linear order, with full numerical simulations is presented, for two very different classes of initial perturbation spectra. We find that the range of validity is similar to that of the perturbative fluid approximation (i.e. up to close to "shell-crossing"), but that the accuracy in tracing the evolution is superior. The formalism provides a powerful tool to systematically calculate discreteness effects at early times in cosmological N-body simulations.

Scale invariant forces in one-dimensional shuffled lattices

Andrea Gabrielli — 2008-03-10T16:48:52-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 72, No. 6. (2005)

We present a detailed and exact study of the probability density function P(F) of the total force F acting on a point particle belonging to a perturbed lattice of identical point sources of a power-law pair interaction. The main results concern the large-F tail of P(F) for which two cases are mainly distinguished: (i) Gaussian-like fast decreasing P(F) for lattice with perturbations forbidding any pair of particles to be found arbitrarily close to one each other and (ii) Lévy-like power-law decreasing P(F) when this possibility is instead permitted. It is important to note that in the second case the exponent of the power-law tail of P(F) is the same for all perturbations (apart from very singular cases) and is in a one-to-one correspondence with the exponent characterizing the behavior of the pair interaction with the distance between the two particles.

Chemical etching of a disordered solid: From experiments to field theory

Andrea Gabrielli — 2008-03-10T15:38:50-00:00

Physica A: Statistical Mechanics and its Applications, Vol. 357, No. 1. (1 November 2005), pp. 122-128.

We present a two-dimensional theoretical model for the slow chemical corrosion of a thin film of a disordered solid by suitable etching solutions. This model explains different experimental results showing that the corrosion stops spontaneously in a situation in which the concentration of the etchant is still finite while the corrosion surface develops clear fractal features. We show that these properties are strictly related to the percolation theory, and in particular to its behavior around the critical point. This task is accomplished both by a direct analysis in terms of a self-organized version of the gradient percolation model and by field theoretical arguments.

Gravitational Evolution of a Perturbed Lattice and its Fluid Limit

M Joyce — 2008-03-10T16:18:57-00:00

Physical Review Letters, Vol. 95, No. 1. (2005)

We apply a simple linearization, well known in solid state physics, to approximate the evolution at early times of cosmological N-body simulations of gravity. In the limit that the initial perturbations, applied to an infinite perfect lattice, are at wavelengths much greater than the lattice spacing l, the evolution is exactly that of a pressureless self-gravitating fluid treated in the analogous (Lagrangian) linearization, with the Zeldovich approximation as a subclass of asymptotic solutions. Our less restricted approximation allows one to trace the evolution of the discrete distribution until the time when particles approach one another (i.e., "shell crossing"). We calculate modifications of the fluid evolution, explicitly dependent on l, i.e., discreteness effects in the N-body simulations. We note that these effects become increasingly important as the initial redshift is increased at fixed l.

Point processes and stochastic displacement fields

Andrea Gabrielli — 2008-03-10T15:17:48-00:00

Physical Review E, Vol. 70, No. 6. (23 December 2004), 066131.

The effect of a stochastic displacement field on a statistically independent point process is analyzed. Stochastic displacement fields can be divided into two large classes: spatially correlated and uncorrelated. For both cases exact transformation equations for the two-point correlation function and the power spectrum of the point process are found; and a detailed study of them with important paradigmatic examples is done. The results are general and in any dimension. Particular attention is devoted to the kind of large-scale correlations that can be introduced by the displacement field and to the realizability of arbitrary “superhomogeneous” point processes.

Invasion Percolation and Critical Transient in the Barab[a-acute]si Model of Human Dynamics

A Gabrielli — 2008-03-08T11:25:29-00:00

Physical Review Letters, Vol. 98, No. 20. (2007)

We introduce an exact probabilistic description for L=2 of the Barabási model for the dynamics of a list of L tasks. This permits us to study the problem out of the stationary state and to solve explicitly the extremal limit case where a critical behavior for the waiting time distribution is observed. This behavior deviates at any finite time from that of the stationary state. We study also the characteristic relaxation time for finite time deviations from stationarity in all cases showing that it diverges in the extremal limit, confirming that these deviations are important at all time.

Diffusion, super-diffusion and coalescence from a single step

Andrea Gabrielli — 2007-10-16T06:53:18-00:00

J. Stat. Mech., Vol. 2007, No. 10. (October 2007), P10007.

Appropriating and Assessing Heuristics for Mobile Computing

Enrico Bertini — 2006-10-03T10:44:58-00:00

(2006), pp. 119-126.

Mobile computing presents formidable challenges not only to the design of applications but also to each and every phase of the systems lifecycle. In particular, the HCI community is still struggling with the challenges that mobile computing poses to evaluation. Expert-based evaluation techniques are well known and they do enable a relatively quick and easy evaluation. Heuristic evaluation, in particular, has been widely applied and investigated, most likely due to its efficiency in detecting most of usability flaws at front of a rather limited investment of time and human resources in the evaluation. However, the capacity of expert-based techniques to capture contextual factors in mobile computing is a major concern. In this paper, we report an effort for realizing usability heuristics appropriate for mobile computing. The effort intends to capture contextual requirements while still drawing from the inexpensive and flexible nature of heuristic-based techniques. This work has been carried out in the context of a research project task geared toward developing a heuristic-based evaluation methodology for mobile computing. This paper describes the methodology that we adopted toward realizing mobile heuristics. It also reports a study that we carried out in order to assess the relevance of the realized mobile heuristics by comparing their performance with that of the standard/traditional usability heuristics. The study yielded positive results in terms of the number of usability flaws identified and the severity ranking assigned.

Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles

EW Wolff — 2006-03-23T02:32:56-00:00

Nature, Vol. 440, No. 7083., pp. 491-496.

Rayleigh loops in the random-field Ising model on the Bethe lattice

Francesca Colaiori — 2007-09-14T12:47:28-00:00

Physical Review B, Vol. 65, No. 22. (20 May 2002), 224404.

We analyze the demagnetization properties of the random-field Ising model on the Bethe lattice focusing on the behavior near the disorder induced phase transition. We derive an exact recursion relation for the magnetization and integrate it numerically. Our analysis shows that demagnetization is possible only in the continuous high disorder phase; where at low field the loops are described by the Rayleigh law. In the low disorder phase; the saturation loop displays a discontinuity that is reflected by a nonvanishing magnetization m ∞ after a series of nested loops. In this case; at low fields the loops are not symmetric and the Rayleigh law does not hold.

Current fluctuations in stochastic lattice gases.

L Bertini — 2007-08-09T18:26:55-00:00

Phys Rev Lett, Vol. 94, No. 3. (28 January 2005)

We study current fluctuations in lattice gases in the macroscopic limit extending the dynamic approach for density fluctuations developed in previous articles. More precisely, we establish a large deviation theory for the space-time fluctuations of the empirical current which include the previous results. We then estimate the probability of a fluctuation of the average current over a large time interval. It turns out that recent results by Bodineau and Derrida [Phys. Rev. Lett. 92, 180601 (2004)]] in certain cases underestimate this probability due to the occurrence of dynamical phase transitions.

Comment on the run time statistics in models of growth in disordered media

A Gabrielli — 2007-01-22T10:54:19-00:00

Journal of Statistical Physics, Vol. V84, No. 3. (1996), pp. 889-893.

Operating system enhancements to prevent the misuse of system calls

Massimo Bernaschi — 2006-08-04T21:29:31-00:00

(2000), pp. 174-183.

A conceptual framework for mixed reality environments: designing novel learning activities for young children

Yvonne Rogers — 2006-01-24T15:09:27-00:00

Presence: Teleoper. Virtual Environ., Vol. 11, No. 6. (December 2002), pp. 677-686.