8,737 research outputs found
The sutures in dentistry
In oral surgery, the last phase of a surgical operation is represented by the tissues suture, that allows the wound lips edges approximation and their stabilization, to promote haemostasis, to avoid the alimentary residues accumulation on the incision line and allow the first intention healing. A good suture avoids that the displacing forces generated by the muscular insertions, functional movements and by the external agents destabilize or cause the surgical wound deiscence. The purpose of this study was to re-examine the suture threads characteristics, properties and biological interactions evaluating the different studies published in literature results and conclusions. In conclusion, the authors recommended the use of the different suture threads on the dependence of the oral surgery operation type that must be performed, of the patient compliance and of the various suture materials physical and biocompatibility characteristics
Spin dynamics in hole-doped two-dimensional S=1/2 Heisenberg antiferromagnets: ^{63}Cu NQR relaxation in La_{2-x}Sr_xCuO_4 for
The effects on the correlated Cu^{2+} S = 1/2 spin dynamics in the
paramagnetic phase of La_{2-x}Sr_xCuO_4 (for ) due to the
injection of holes are studied by means of ^{63}Cu NQR spin-lattice relaxation
time T_1 measurements. The results are discussed in the framework of the
connection between T_1 and the in-plane magnetic correlation length
. It is found that at high temperatures the system remains in
the renormalized classical regime, with a spin stiffness constant
reduced by small doping to an extent larger than the one due to Zn doping. For
the effect of doping on appears to level off. The
values for derived from T_1 for K are much larger
than the ones estimated from the temperature behavior of sublattice
magnetization in the ordered phase (). It is argued that these
features are consistent with the hypothesis of formation of stripes of
microsegregated holes.Comment: 10 pages, 3 figure
The 346 A.D. earthquake( Central-Southern Italy): an archaeoseismological approach
The 346 A.D. earthquake is known through sparse historical sources. It is mentioned by Hyeronimus as felt in Rome and responsible for damage in the ancient Campania Province. Four epigraphs report the earthquake as the cause for the restorations of buildings at Aesernia-Isernia, Allifae-Alife, Telesia-Telese and Saepinum-Sepino. On this basis, an area possibly struck by the earthquake was already defined in the literature. Another
seventeen epigraphs mentioning restoration or re-building of edifices in localities of central-southern Italy (without explicitly referring to the earthquake as the cause of the damage) are possibly related to the earthquake effects. We tried to enhance our knowledge on the 346 earthquake through archaeoseismological analyses. The investigation has benefited from specific fieldwork during archaeological excavations and a critical review of the available archaeological literature. However, a correct archaeoseismological interpretation is hindered by the occurrence of two earthquakes (346 and 375 A.D.) in a short time span and in adjacent areas (whose effects may be archaeo-chronologically undistinguishable) and the not always univocal evidence of the seismic origin of the detected collapses or restoration of structures. For this reason we propose a representation of the 346 A.D. effects
through two extreme pictures: 1) the localities for which conclusive data on the earthquake effects are available and 2) the data of point 1 plus the localities for which archaeoseismological data consistent with the earthquake are available. The latter view defines an area of possible damage related to the 346 event larger than that previously known. In particular, the earthquake damage may result from a seismic sequence similar to that, which struck a part of the central and the southern Apennines in 1456, or from an event comparable to that which occurred in 1805, responsible for widespread damage in the northern sector of the southern Apennines
Searching for Dark Matter in the CMB: A Compact Parameterization of Energy Injection from New Physics
High-precision measurements of the temperature and polarization anisotropies
of the cosmic microwave background radiation have been previously employed to
set robust constraints on dark matter annihilation during recombination. In
this work we improve and generalize these constraints to apply to energy
deposition during the recombination era with arbitrary redshift dependence. Our
approach also provides more rigorous and model-independent bounds on dark
matter annihilation and decay scenarios. We employ principal component analysis
to identify a basis of weighting functions for the energy deposition. The
coefficients of these weighting functions parameterize any energy deposition
model and can be constrained directly by experiment. For generic energy
deposition histories that are currently allowed by WMAP7 data, up to 3
principal component coefficients are measurable by Planck and up to 5
coefficients are measurable by an ideal cosmic variance limited experiment. For
WIMP dark matter, our analysis demonstrates that the effect on the CMB is
described well by a single (normalization) parameter and a "universal" redshift
dependence for the energy deposition history. We give WMAP 7 constraints on
both generic energy deposition histories and the universal WIMP case.Comment: 30 pages, 24 figure
Total energy global optimizations using non orthogonal localized orbitals
An energy functional for orbital based calculations is proposed, which
depends on a number of non orthogonal, localized orbitals larger than the
number of occupied states in the system, and on a parameter, the electronic
chemical potential, determining the number of electrons. We show that the
minimization of the functional with respect to overlapping localized orbitals
can be performed so as to attain directly the ground state energy, without
being trapped at local minima. The present approach overcomes the multiple
minima problem present within the original formulation of orbital based
methods; it therefore makes it possible to perform calculations for an
arbitrary system, without including any information about the system bonding
properties in the construction of the input wavefunctions. Furthermore, while
retaining the same computational cost as the original approach, our formulation
allows one to improve the variational estimate of the ground state energy, and
the energy conservation during a molecular dynamics run. Several numerical
examples for surfaces, bulk systems and clusters are presented and discussed.Comment: 24 pages, RevTex file, 5 figures available upon reques
Paleoseismology of silent faults in the Central Apennines (Italy): the Campo Imperatore Fault (Gran Sasso Range Fault System)
Paleoseismological analyses were performed along the Campo Imperatore Fault (part of the Gran Sasso Range
Fault System) in order to define the seismogenic behaviour (recurrence interval for surface faulting events, elapsed
time since the last activation, maximum expected magnitude). Four trenches were excavated across secondary
faults which are related to the main fault zone. The youngest event (E1) occurred after 3480-3400 years BP;
a previous event (E2) occurred between 7155-7120/7035-6790 years BP and 5590-5565/5545-5475 years BP,
while the oldest one (E3) has a Late Pleistocene age. The chronological interval between the last two displacement
events ranges between 1995 and 6405 years. The minimum elapsed time since the last activation is 800
years, due to the absence of historical earthquakes which may have been caused by the Campo Imperatore Fault
and based on the completeness of the historical catalogues for the large magnitude events in the last eight centuries.
Based on the length of the fault surficial expression, earthquakes with M 6.95 may be expected from the
activation of the entire Gran Sasso Range Fault System. The effects of the fault activation were investigated
through the simulation of a damage scenario obtained by means of the FaCES computer code, made by the
National Seismic Survey for civil protection purposes. The damage scenario shows that the activation of the Gran
Sasso Range Fault System may be responsible for an earthquake with epicentral intensity I0 10.5 MCS, with a
number of collapsed buildings ranging between 7900 and 31100 and a number of damaged buildings ranging between
99 000 and 234 000. The investigated case defines, therefore, a high risk level for the region affected by
the Campo Imperatore Fault
Landslide hazard assessment in the Collazzone area, Umbria, Central Italy
We present the results of the application of a recently proposed model to determine landslide hazard. The model predicts where landslides will occur, how frequently they will occur, and how large they will be in a given area. For the Collazzone area, in the central Italian Apennines, we prepared a multi-temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1941 and 1997 and field surveys conducted in the period between 1998 and 2004. We then partitioned the 79 square kilometres study area into 894 slope units, and obtained the probability of spatial occurrence of landslides by discriminant analysis of thematic variables, including morphology, lithology, structure and land use. For each slope unit, we computed the expected landslide recurrence by dividing the total number of landslide events inventoried in the terrain unit by the time span of the investigated period. Assuming landslide recurrence was constant, and adopting a Poisson probability model, we determined the exceedance probability of having one or more landslides in each slope unit, for different periods. We obtained the probability of landslide size, a proxy for landslide magnitude, by analysing the frequency-area statistics of landslides, obtained from the multi-temporal inventory map. Lastly, assuming independence, we determined landslide hazard for each slope unit as the joint probability of landslide size, of landslide temporal occurrence, and of landslide spatial occurrence
Identification and mapping of recent rainfall-induced landslides using elevation data collected by airborne Lidar
International audienceA high resolution Digital Elevation Model with a ground resolution of 2 m×2 m (DEM2) was obtained for the Collazzone area, central Umbria, through weighted linear interpolation of elevation points acquired by Airborne Lidar Swath Mapping. Acquisition of the elevation data was performed on 3 May 2004, following a rainfall period that resulted in numerous landslides. A reconnaissance field survey conducted immediately after the rainfall period allowed mapping 70 landslides in the study area, for a total landslide area of 2.7×105 m2. Topographic derivative maps obtained from the DEM2 were used to update the reconnaissance landslide inventory map in 22 selected sub-areas. The revised inventory map shows 27% more landslides and 39% less total landslide area, corresponding to a smaller average landslide size. Discrepancies between the reconnaissance and the revised inventory maps were attributed to mapping errors and imprecision chiefly in the reconnaissance field inventory. Landslides identified exploiting the Lidar elevation data matched the local topography more accurately than the same landslides mapped using the existing topographic maps. Reasons for the difference include an incomplete or inaccurate view of the landslides in the field, an unfaithful representation of topography in the based maps, and the limited time available to map the landslides in the field. The high resolution DEM2 was compared to a coarser resolution (10 m×10 m) DEM10 to establish how well the two DEMs captured the topographic signature of landslides. Results indicate that the improved topographic information provided by DEM2 was significant in identifying recent rainfall-induced landslides, and was less significant in improving the representation of stable slopes
Rainfall induced landslides in December 2004 in south-western Umbria, central Italy: types, extent, damage and risk assessment
International audienceThe autumn of 2004 was particularly wet in Umbria, with cumulative rainfall in the period from October to December exceeding 600 mm. On 4?6 December and on 25?27 December 2004, two storms hit the Umbria Region producing numerous landslides, which were abundant near the town of Orvieto where they affected volcanic deposits and marine sediments. In this work, we document the type and abundance of the rainfall-induced landslides in the Orvieto area, in south-western Umbria, we study the rainfall conditions that triggered the landslides, including the timing of the slope failures, we determine the geotechnical properties of the failed volcanic materials, and we discuss the type and extent of damage produced by the landslides. We then use the recent event landslide information to test a geomorphological assessment of landslide hazards and risk prepared for the village of Sugano, in the Orvieto area. Based on the results of the test, we update the existing landslide hazards and risk scenario for extremely rapid landslides, mostly rock falls, and we introduce a new landslide scenario for rapid and very rapid landslides, including soil slides, debris flows and debris avalanches
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