3,242 research outputs found
Paper Session II-B - NASA-ESA Technical Interchange: Capability of the Automated Transfer Vehicle to Resupply Space Station
The purpose of this paper is to describe the ATV configuration and focus on the NASA-ESATI evaluation results associated with the use of ATV in the Station servicing scenario. In addition, the implications of using the ATV for resupply of the redesigned International Space Station are also briefly addressed
Planetary formation in the Gamma-Cephei system
We numerically investigate under which conditions the planet detected at 2.1
AU of Gamma-Cephei could form through the core-accretion scenario despite the
perturbing presence of the highly eccentric companion star. We first show that
the initial stage of runaway accretion of kilometer-sized planetesimals is
possible within 2.5 AU from the central star only if large amounts of gas are
present. In this case, gaseous friction induces periastron alignment of the
orbits which reduces the otherwise high mutual impact velocities due to the
companion's secular perturbations. The following stage of mutual accretion of
large embryos is also modeled. According to our simulations, the giant impacts
among the embryos always lead to a core of 10 Mearth within 10 Myr, the average
lifetime of gaseous discs. However, the core always ends up within 1.5 AU from
the central star. Either the core grows more quickly in the inner region of the
disc, or it migrates inside by scattering the residual embryosComment: 8 pages, 12 figures to appear in Astronomy and Astrophysics (accepted
08/06/2004
Universal and phase covariant superbroadcasting for mixed qubit states
We describe a general framework to study covariant symmetric broadcasting
maps for mixed qubit states. We explicitly derive the optimal N to M
superbroadcasting maps, achieving optimal purification of the single-site
output copy, in both the universal and the phase covariant cases. We also study
the bipartite entanglement properties of the superbroadcast states.Comment: 19 pages, 8 figures, strictly related to quant-ph/0506251 and
quant-ph/051015
On the Thermodynamic Limit in Random Resistors Networks
We study a random resistors network model on a euclidean geometry \bt{Z}^d.
We formulate the model in terms of a variational principle and show that, under
appropriate boundary conditions, the thermodynamic limit of the dissipation per
unit volume is finite almost surely and in the mean. Moreover, we show that for
a particular thermodynamic limit the result is also independent of the boundary
conditions.Comment: 14 pages, LaTeX IOP journal preprint style file `ioplppt.sty',
revised version to appear in Journal of Physics
New data on the exploitation of obsidian in the mediterranean basin: The harbour of pyrgi and the trade in neolithic age
The contribution shows the first results of ongoing research on the origins and prehistoric assumptions of the well-known Etruscan and Roman harbour of Pyrgi, an ancient Ceretan harbour in southern Etruria. In the light of recent land and submarine investigations, traces of ancient frequentations and contacts dating back to the Neolithic era are emerging when the coastal morphology and environmental characteristics of the site were very different from the current ones. The Etruscan port of Pyrgi, which continues its historical history in Roman and Medieval times, appears as the heir of one or more landing points frequented perhaps already in the Middle Neolithic. As part of this contribution, around 60 obsidian finds (waste resulting from the manufacture of arrowheads) were analyzed using the LA-ICP-MS technique (Laser Ablation Inductively Coupled Plasma Mass Spectrometry). The comparison between the data obtained on the archaeological finds and the bibliographic data relating to the geological obsidians of the peri-Tyrrhenian area allowed the identification of the provenance of the finds. In particular, most of the finds can be attributed to the Aeolian area, highlighting the leading role played by the Aeolian archipelago in the development of trade of this material. Other sources of supply have been identified on the island of Palmarola and in Sardinia (Monte Arci) although with a lower incidence. The discovery of numerous findings in obsidian from overseas, which took place in the area immediately surrounding Pyrgi, offers different suggestions about the origin of the docking place, with traces of centuries-old frequentation, extended from the Neolithic to the modern era
Parallel processing in immune networks
In this work we adopt a statistical mechanics approach to investigate basic,
systemic features exhibited by adaptive immune systems. The lymphocyte network
made by B-cells and T-cells is modeled by a bipartite spin-glass, where,
following biological prescriptions, links connecting B-cells and T-cells are
sparse. Interestingly, the dilution performed on links is shown to make the
system able to orchestrate parallel strategies to fight several pathogens at
the same time; this multitasking capability constitutes a remarkable, key
property of immune systems as multiple antigens are always present within the
host. We also define the stochastic process ruling the temporal evolution of
lymphocyte activity, and show its relaxation toward an equilibrium measure
allowing statistical mechanics investigations. Analytical results are compared
with Monte Carlo simulations and signal-to-noise outcomes showing overall
excellent agreement. Finally, within our model, a rationale for the
experimentally well-evidenced correlation between lymphocytosis and
autoimmunity is achieved; this sheds further light on the systemic features
exhibited by immune networks.Comment: 21 pages, 9 figures; to appear in Phys. Rev.
A Social IoT-Based Solution for Real-Time Forest Fire Detection
Conservation of the natural ecosystem is a hot topic that is receiving increasing attention not only from the scientific community, but from the entire world population. Forests and woodlands are major contributors to climate change mitigation, able to absorb significant amounts of carbon dioxide. This paper proposes a novel real-time fire monitoring and detection system based on Digital Mobile Radio (DMR) nodes and a Social Internet of Things (SIoT) platform on which fire detection decision making algorithms have been implemented. The results obtained by employing a K-Nearest Neighbors (KNN) algorithm and a Recurrent Neural Network (RNN) show the ability to detect the slightest variation in the observed parameters, determining the direction and speed of fire propagation with an accuracy of more than 98%
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Targeting the CBM complex causes Treg cells to prime tumours for immune checkpoint therapy.
Solid tumours are infiltrated by effector T cells with the potential to control or reject them, as well as by regulatory T (Treg) cells that restrict the function of effector T cells and thereby promote tumour growth1. The anti-tumour activity of effector T cells can be therapeutically unleashed, and is now being exploited for the treatment of some forms of human cancer. However, weak tumour-associated inflammatory responses and the immune-suppressive function of Treg cells remain major hurdles to broader effectiveness of tumour immunotherapy2. Here we show that, after disruption of the CARMA1-BCL10-MALT1 (CBM) signalosome complex, most tumour-infiltrating Treg cells produce IFNγ, resulting in stunted tumour growth. Notably, genetic deletion of both or even just one allele of CARMA1 (also known as Card11) in only a fraction of Treg cells-which avoided systemic autoimmunity-was sufficient to produce this anti-tumour effect, showing that it is not the mere loss of suppressive function but the gain of effector activity by Treg cells that initiates tumour control. The production of IFNγ by Treg cells was accompanied by activation of macrophages and upregulation of class I molecules of the major histocompatibility complex on tumour cells. However, tumour cells also upregulated the expression of PD-L1, which indicates activation of adaptive immune resistance3. Consequently, blockade of PD-1 together with CARMA1 deletion caused rejection of tumours that otherwise do not respond to anti-PD-1 monotherapy. This effect was reproduced by pharmacological inhibition of the CBM protein MALT1. Our results demonstrate that partial disruption of the CBM complex and induction of IFNγ secretion in the preferentially self-reactive Treg cell pool does not cause systemic autoimmunity but is sufficient to prime the tumour environment for successful immune checkpoint therapy
Boundary Conformal Field Theory and Ribbon Graphs: a tool for open/closed string dualities
We construct and fully characterize a scalar boundary conformal field theory
on a triangulated Riemann surface. The results are analyzed from a string
theory perspective as tools to deal with open/closed string dualities.Comment: 40 pages, 7 figures; typos correcte
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