120 research outputs found
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The importance of being little: MA-XRF on manuscripts on a Venetian island
The XRF scanning spectrometer developed in the framework of CHNet-INFN (Cultural Heritage Network - National Institute of Nuclear Physics), is specifically customised for cultural heritage applications, designed with a focus on having a lightweight scanner (weighing approximately 10 kg), easy to handle and thus easily transportable in two medium-sized boxes. The research presented here deals with the study of a set of choir books preserved in the Abbey of San Giorgio Maggiore on the homonymous island in Venice. Produced for the Abbey itself from the mid-15th century onwards, the manuscripts have never left the island, making the study of the materials of particular interest as they have undergone little or no modification over time. During their history in the Abbey, however, the volumes have been disassembled and reassembled in various ways, bringing complexity to the current cataloguing work. Thus, analytical investigations of the pigments and painting techniques might help identify the original arrangement of displaced leaves and provide evidence for the attribution of individual illuminations to certain artists. Thanks to its easy transportability, it was possible to take the scanner to the small island by means of the water-based Venetian public transport. Selected results are presented, derived from the high-quality MA-XRF maps obtained
TTRV30M oligomeric aggregates inhibit proliferation of renal progenitor cells but maintain their capacity to differentiate into podocytes in vitro
Publicado em: The Proceedings of the XIIIth International Symposium on Amyloidosis,
May 6-10, 2012, Groningen, The NetherlandsIn Familial Amyloidotic Polyneuropathy, the amyloid deposition of mutant transthyretin TTR V30M can lead to renal complications. An unexplored mechanism is the toxicity of oligomeric TTR aggregates. A subset of renal progenitor cells (RPC) in the adult human kidney can induce regeneration of podocytes and tubular structures of the nephron, which can be critical for preventing irreversible renal failure. We assessed whether RPC are vulnerable, in vitro, to TTRV30M oligomers. RPC proliferation was reduced by 16.3±9.7% and 32.6±6.3% after 48 and 72 hours, respectively, in the presence of the oligomers. However, oligomers did not induce apoptosis or alterations in cell cycle to any significant extent, and did not influence RPC differentiation into podocytes. From this first attempt, we can say that TTRV30M oligomers inhibit RPC proliferation but do not influence their capacity to differentiate into mature podocytes, and thus should not compromise tissue regeneration.FC
Ultrathin Tropical Tropopause Clouds (UTTCs) : I. Cloud morphology and occurrence
Subvisible cirrus clouds (SVCs) may contribute to dehydration close to the tropical tropopause. The higher and colder SVCs and the larger their ice crystals, the more likely they represent the last efficient point of contact of the gas phase with the ice phase and, hence, the last dehydrating step, before the air enters the stratosphere. The first simultaneous in situ and remote sensing measurements of SVCs were taken during the APE-THESEO campaign in the western Indian ocean in February/March 1999. The observed clouds, termed Ultrathin Tropical Tropopause Clouds (UTTCs), belong to the geometrically and optically thinnest large-scale clouds in the Earth´s atmosphere. Individual UTTCs may exist for many hours as an only 200--300 m thick cloud layer just a few hundred meters below the tropical cold point tropopause, covering up to 105 km2. With temperatures as low as 181 K these clouds are prime representatives for defining the water mixing ratio of air entering the lower stratosphere
Observing Ultra High Energy Cosmic Particles from Space: SEUSO, the Super Extreme Universe Space Observatory Mission
The experimental search for ultra high energy cosmic messengers, from eV to beyond eV, at the very end of the known energy
spectrum, constitutes an extraordinary opportunity to explore a largely unknown
aspect of our universe. Key scientific goals are the identification of the
sources of ultra high energy particles, the measurement of their spectra and
the study of galactic and local intergalactic magnetic fields. Ultra high
energy particles might, also, carry evidence of unknown physics or of exotic
particles relics of the early universe. To meet this challenge a significant
increase in the integrated exposure is required. This implies a new class of
experiments with larger acceptances and good understanding of the systematic
uncertainties. Space based observatories can reach the instantaneous aperture
and the integrated exposure necessary to systematically explore the ultra high
energy universe. In this paper, after briefly summarising the science case of
the mission, we describe the scientific goals and requirements of the SEUSO
concept. We then introduce the SEUSO observational approach and describe the
main instrument and mission features. We conclude discussing the expected
performance of the mission
Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission
The longitudinal development and other characteristics of the EECR induced
atmospheric showers can be studied from space by detecting the fluorescence
light induced in the atmospheric nitrogen. According to the Airwatch concept a
single fast detector can be used for measuring both intensity and time
development of the streak of fluorescence light produced by the atmospheric
shower induced by an EECR. In the present communication the detection
capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9
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CheriABI: Enforcing Valid Pointer Provenance and Minimizing Pointer Privilege in the POSIX C Run-time Environment
The CHERI architecture allows pointers to be implemented as capabilities (rather than integer virtual addresses) in a manner that is compatible with, and strengthens, the semantics of the C language. In addition to the spatial protections offered by conventional fat pointers, CHERI capabilities offer strong integrity, enforced provenance validity, and access monotonicity. The stronger guarantees of these architectural capabilities must be reconciled with the real-world behavior of operating systems, run-time environments, and applications. When the process model, user-kernel interactions, dynamic linking, and memory management are all considered, we observe that simple derivation of architectural capabilities is insufficient to describe appropriate access to memory. We bridge this conceptual gap with a notional \emph{abstract capability} that describes the accesses that should be allowed at a given point in execution, whether in the kernel or userspace. To investigate this notion at scale, we describe the first adaptation of a full C-language operating system (FreeBSD) with an enterprise database (PostgreSQL) for complete spatial and referential memory safety. We show that awareness of abstract capabilities, coupled with CHERI architectural capabilities, can provide more complete protection, strong compatibility, and acceptable performance overhead compared with the pre-CHERI baseline and software-only approaches. Our observations also have potentially significant implications for other mitigation techniques.This work was supported by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL), under contracts FA8750-10-C-0237 (``CTSRD'') and HR0011-18-C-0016 (``ECATS''). The views, opinions, and/or findings contained in this report are those of the authors and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government. We also acknowledge the EPSRC REMS Programme Grant (EP/K008528/1), the ERC ELVER Advanced Grant (789108), Arm Limited, HP Enterprise, and Google, Inc. Approved for Public Release, Distribution Unlimited
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