246 research outputs found
analysis of the al and ti additions influences on phases generation and damage in a hot dip galvanizing process
Abstract Cheap iron-based alloys, such as Ductile Cast Irons (DCIs) and low carbon steels, are more and more used in the mechanical field because they are characterized by good strength and good workability. However, the low value of electrochemical potential of low carbon steel leads to quick environmental corrosion that can compromise the operative life of mechanical components. Therefore, it is important to protect them against corrosion even for safety and reliability reasons. The use of a traditional protection technique, like Hot Dip Galvanizing (HDG), allows low costs too. In this work, the phase formation during HDG process is presented and discussed. In particular, the influence of Al and Ti additions on the pure Zn bath is shown in the metallographic analysis, presenting also the results of pure Zn bath
Potential for rupture before eruption at Campi Flegrei caldera, Southern Italy
Volcanoes reawakening after long repose must rupture the crust before magma can erupt. Rupture is preceded by repeatable variations in the rate of seismicity with ground movement, which trace the amount of applied stress that is released by local earthquakes. A rupturing sequence has been developing across four episodes of ground uplift at Italy’s Campi Flegrei caldera: in 1950-1952, 1969-1972, 1982-1984 and since 2004. We predicted in 2016 that the approach to rupture would continue after an additional uplift of 30-40 cm at the location of largest movement. We have updated our analysis with new data on changes in the numbers of local earthquakes with amounts of ground movement. Here we show that subsequent events have confirmed our prediction and that the unrest has been changing the structure of Campi Flegrei’s crust. The results provide new constraints for evaluating the volcano’s potential to erupt or to subside without eruption
A common source for the destructive earthquakes in the volcanic island of Ischia (Southern Italy): insights from historical and recent seismicity
AbstractThe island of Ischia, located in the Gulf of Naples, represents an unusual case of resurgent caldera where small-to-moderate magnitude volcano-tectonic earthquakes generate large damage and catastrophic effects, as in the case of 4 March 1881 (Imax-VIII-IXMCS) and 28 July 1883 (Imax X-XI MCS) historical earthquakes, and of the recent 21 August 2017 MW = 3.9, event. All these earthquakes struck the northern area of the island. With about 65,000 inhabitants, Ischia is a popular touristic destination for thermals baths, hosting more than 3,000,000 visitors per year, thus representing a high seismic risk area. Assessing its seismic potential appears a fundamental goal and, to this end, the estimate of the magnitude of significant historical events and the characterization of their source are crucial. We report here a reassessment of historical data of damage of 1881 and 1883 earthquakes to evaluate the main source parameters of these events (obtained with the BOXER and EXISM software) and quantitatively compare, for the first time, the results with the source characteristics, obtained from instrumental data, of the recent 2017 earthquake. The results allowed us to assess the location, as well as the possible dimension and the related maximum magnitude, of the seismogenic structure responsible for such damaging earthquakes. Our results also provide an additional framework to define the mechanisms leading to earthquakes associated with the dynamics of calderas
Light Nonabelian Monopoles and Generalized r-Vacua in Supersymmetric Gauge Theories
We study a class of N=1 supersymmetric U(N) gauge theories and find that
there exist vacua in which the low-energy magnetic effective gauge group
contains multiple nonabelian factors, \prod_i SU(r_i), supported by light
monopoles carrying the associated nonabelian charges. These nontrivially
generalize the physics of the so-called r-vacua found in softly broken N=2
supersymmetric SU(N) QCD, with an effective low-energy gauge group SU(r) \times
U(1)^{N-r}. The matching between classical and quantum (r_{1}, r_{2},...) vacua
gives an interesting hint about the nonabelian duality.Comment: 24 pages, 2 figures. v2 & v3: typos correcte
Nonabelian Monopoles
We study topological as well as dynamical properties of BPS nonabelian
magnetic monopoles of Goddard-Nuyts-Olive-Weinberg type in ,
and SO(N) gauge theories, spontaneously broken to nonabelian
subgroups . We find that monopoles transform under the group dual to in
a tensor representation of rank determined by the corresponding element in
. When the system is embedded in a supersymmetric theory
with an appropriate set of flavors with appropriate bare masses, the BPS
monopoles constructed semiclassically persist in the full quantum theory. This
result supports the identification of ``dual quarks'' found at -vacua of
theories with the nonabelian magnetic monopoles. We present
several consistency checks of our monopole spectra.Comment: 48 pages, 2 figures, Latex, references added, minor corrections mad
Non Abelian Magnetic Monopoles and Dynamics of Confinement
Magnetic monopoles having non-Abelian charges have been found recently to
play a crucial role in the infrared in a class of supersymmetric gauge
theories. We argue that these "dual quarks" can naturally be identified with
the non-Abelian magnetic monopoles of the type first discussed by Goddard,
Nuyts and Olive. Our argument is based on a few simple observations as regards
to their charge structure, flavor quantum numbers, and some general properties
of electromagnetic duality.Comment: 12 pages, Late
Modulation of Alpha-Synuclein Aggregation by Dopamine Analogs
The action of dopamine on the aggregation of the unstructured alpha-synuclein (α-syn) protein may be linked to the pathogenesis of Parkinson's disease. Dopamine and its oxidation derivatives may inhibit α-syn aggregation by non-covalent binding. Exploiting this fact, we applied an integrated computational and experimental approach to find alternative ligands that might modulate the fibrillization of α-syn. Ligands structurally and electrostatically similar to dopamine were screened from an established library. Five analogs were selected for in vitro experimentation from the similarity ranked list of analogs. Molecular dynamics simulations showed they were, like dopamine, binding non-covalently to α-syn and, although much weaker than dopamine, they shared some of its binding properties. In vitro fibrillization assays were performed on these five dopamine analogs. Consistent with our predictions, analyses by atomic force and transmission electron microscopy revealed that all of the selected ligands affected the aggregation process, albeit to a varying and lesser extent than dopamine, used as the control ligand. The in silico/in vitro approach presented here emerges as a possible strategy for identifying ligands interfering with such a complex process as the fibrillization of an unstructured protein
Measuring and benchmarking the quality of two different organizational ways in delivering infant vaccination
Introduction: The aim of this study was the quality of service evaluation of two different organizational ways in delivering infant vaccination according to a Regional Vaccination Plan.Ă‚Â Materials and Methods: Eleven vaccination centres were selected in two Local Health Units (ASLs) belonging to the Regional Health Service of the Lazio Region, Italy. The services offering paediatric vaccinations for children under three years of age, delivered with the need for an appointment (VACL) or else without an appointment (VACP), were investigated. The quality aspects under evaluation were communicational efficiency, organisational efficiency and comfort. Three steps are necessary to quantify the overall quality of service. Step 1 involves different stakeholders and the elicitation of best and worst feasible performance conditions for the ASLs when delivering VACP/VACL services (i.e., subjective data collection). Step 2 consists in the observation of current performances of the selected vaccination centres (i.e., objective data collection). Step 3 involves the combination of all data. Benchmarking between VACP and VACL, i.e., two different organisational ways in delivering infant vaccination, can be performed as a result of the probabilistic meaning of the evaluated scores.Ă‚Â Results: An expert of vaccination services, i.e., a virtual combination of patients, doctors and nurses, claims the quality of service delivery of the ASLs under investigation with probability 78.03% and 69.67% for VACL and VACP, respectively. In other words, for short, the quality scores of the ASLs were 78.03% for VACP and 69.67% for VACL. Furthermore our results show how to practically improve the current service delivery
Geometry and Dynamics of a Coupled 4D-2D Quantum Field Theory
Geometric and dynamical aspects of a coupled 4D-2D interacting quantum field
theory - the gauged nonAbelian vortex - are investigated. The fluctuations of
the internal 2D nonAbelian vortex zeromodes excite the massless 4D Yang-Mills
modes and in general give rise to divergent energies. This means that the
well-known 2D CP(N-1) zeromodes associated with a nonAbelian vortex become
nonnormalizable. Moreover, all sorts of global, topological 4D effects such as
the nonAbelian Aharonov-Bohm effect come into play. These topological global
features and the dynamical properties associated with the fluctuation of the 2D
vortex moduli modes are intimately correlated, as shown concretely here in a
U(1) x SU(N) x SU(N) model with scalar fields in a bifundamental representation
of the two SU(N) factor gauge groups.Comment: Latex, 39 pages, 5 figure
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