1,135 research outputs found
Forma-funzione nella concezione strutturale: il nuovo ponte sul fiume Pescara
Obiettivo di questa Tesi di Laurea è l’approfondimento dei concetti di “forma”, “funzione” e del loro rapporto nella progettazione strutturale
Unambiguous Detection of Reflection in Magnetic Cataclysmic Variables: Joint NuSTAR-XMM-Newton Observations of Three Intermediate Polars
In magnetic cataclysmic variables (CVs), X-ray emission regions are located
close to the white dwarf surface, which is expected to reflect a significant
fraction of intrinsic X-rays above 10 keV, producing a Compton reflection hump.
However, up to now, a secure detection of this effect in magnetic CVs has
largely proved elusive because of the limited sensitivity of non-imaging X-ray
detectors. Here we report our analysis of joint NuSTAR/XMM-Newton observations
of three magnetic CVs, V709 Cas, NY Lup, and V1223 Sgr. The improved hard X-ray
sensitivity of the imaging NuSTAR data has resulted in the first robust
detection of Compton hump in all three objects, with amplitudes of ~1 or
greater in NY Lup, and likely <1.0 in the other two. We also confirm earlier
report of a strong spin modulation above 10 keV in V709 Cas, and report the
first detection of small spin amplitudes in the others. We interpret this as
due to different height of the X-ray emitting region among these objects. A
height of ~0.2 white dwarf radii provides a plausible explanation for the low
reflection amplitude of V709 Cas. Since emission regions above both poles are
visible at certain spin phases, this can also explain the strong hard X-ray
spin modulation. A shock height of ~0.05 white dwarf radii can explain our
results on V1223 Sgr, while the shock height in NY Lup appears negligible.Comment: 16 pages including 3 figures and 2 tables; accepted for publication
in Astrophysical Journal Letter
MicroCT imaging of long bones: archaeozoology and domestication from a digital perspective
X-ray microCT imaging offers the possibility to
study interior structure of animal remains detecting agerelated changes of bone microstructure. In the present paper
we analyse patterns in the development of diaphyseal
structure in canids. In particular, the first metacarpal of
present-day and archaeological red fox (Vulpes vulpes) and
wolf (Canis lupus) individuals have been analysed. Variables
describing bone structure were measured by inferring bone
development through observation of cross-sections. Results
show how bone structure changes through life and how this
approach allows to separate young individuals from older
ones. This is important both from a zooarchaeological
perspective, since microCT imaging is a non-invasive tool to
estimate the age at death of animal remains, and to
discriminate taxa characterized by a close morphology but
different adult body size
San Rocco/Koromačnik military camps (2nd–1st centuries BC)
On the San Rocco hill, remote sensing and field-walking campaigns indicated the existence of a large Roman military camp (Camp 1) extending over the whole area, a small camp on the top of the hill (Camp 2), and a large area south of it where orthogonal structures have been identified. To clarify the function and chronology of the remains, three trenches were opened in 2019 and 2021. Part of a terrace construction dated between the end of the 2nd and mid-1st century BC was found in Trench 1. Together with orthogonal crop and shadow marks, it indicates that a large part of the hill was arranged in terraces. The northern rampart of Camp 1 was excavated in Trench 3. The 6.5-m-wide fortification of Phase 1 consisted of four lines of defence combining a low stone wall with a wooden superstructure, protected by a palisade, two lines of wooden obstacles, and a stone escarpment. The structure, dated to the 2nd century BC, was destroyed by a fire and restored by adding an earth bank in Phase 2 (end of the 2nd or beginning of the 1st century BC). Camp 2 on the top of the hill was protected by a low walkway that consisted of an earth rampart reinforced on the inside by a row of stones and on the outside by a stone accumulation (Trench 2). Its construction in Phase 1 is dated into the pre-Caesarean period and the renovation in Phase 2 into the mid-1st century BC
GRB 980425, SN1998bw and the EMBH model
The EMBH model, previously developed using GRB 991216 as a prototype, is here
applied to GRB 980425. We fit the luminosity observed in the 40-700 keV, 2-26
keV and 2-10 keV bands by the BeppoSAX satellite. In addition we present a
novel scenario in which the supernova SN1998bw is the outcome of an ``induced
gravitational collapse'' triggered by GRB 980425, in agreement with the
GRB-Supernova Time Sequence (GSTS) paradigm (Ruffini et al. 2001c). A further
outcome of this astrophysically exceptional sequence of events is the formation
of a young neutron star generated by the SN1998bw event. A coordinated
observational activity is recommended to further enlighten the underlying
scenario of this most unique astrophysical system.Comment: 10 pages, 3 figures, in the Proceedings of the 34th COSPAR scientific
assembly, Elsevier. Fixed some typos in this new versio
Decifrare e cartografare le tracce del paesaggio antico nel Carso triestino
The extensive analysis of remote-sensed data (among which ALS-derived images) and fieldwork carried out in the Trieste Karst (Northeastern Italy) have shed light on archaeological landscapes largely unknown until recent years. The chronological definition of this complex palimpsest was based on the collection of findings associ-ated to the archeological evidence, shape and orientation of detected structures and stratigraphic relations among features. This allowed to evaluate the interplay between archaeological and geo-morphological landforms through time and to reconstruct some long-term economic strategies pursued by past communities. As a result, we present a map of the easternmost sector of the Trieste area, next to the border between Italy and Slovenia, approximately corresponding to the area of the map Carta Tecnica Regionale “Grozzana”. The map aims at providing a tool for the protection of the cultural and envi-ronmental heritage, land use planning and touristic valorisation of the area
Using X-ray Microtomography to Discriminate Between Dogs’ and Wolves’ Lower Carnassial Tooth
Dogs and wolves exhibit similar dental features since they belong to the same species. Here we explore a new method to
discriminate between wild and domestic forms, based on the analysis of the internal structure of the teeth. We analysed the lower first molar of 21 dogs and 17 wolves. X-ray microtomographic analyses were performed and tooth tissue proportions were assessed by the proportion of the dentine volume. As a result, dog molars show a lower percentage of dentine than those of wolves. This analysis offers promising applications in the study of dog domestication origins
GRB970228 as a prototype for short GRBs with afterglow
GRB970228 is analyzed as a prototype to understand the relative role of short
GRBs and their associated afterglows, recently observed by Swift and HETE-II.
Detailed theoretical computation of the GRB970228 light curves in selected
energy bands are presented and compared with observational BeppoSAX data.Comment: 2 pages, 1 figure, to appear in the proceedings of "Swift and GRBs",
Venice, 2006, Il Nuovo Cimento, in pres
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