728 research outputs found
Uniform materials and the multiplicative decomposition of the deformation gradient in finite elasto-plasticity
In this work we analyze the relation between the multiplicative decomposition
of the deformation gradient as a product
of the elastic and plastic factors and the theory of uniform materials. We
prove that postulating such a decomposition is equivalent to having a uniform
material model with two configurations - total and the inelastic
. We introduce strain tensors characterizing different types of
evolutions of the material and discuss the form of the internal energy and that
of the dissipative potential. The evolution equations are obtained for the
configurations and the material metric .
Finally the dissipative inequality for the materials of this type is
presented.It is shown that the conditions of positivity of the internal
dissipation terms related to the processes of plastic and metric evolution
provide the anisotropic yield criteria
Historical roots and the evolving science of forest management under a systemic perspective
In recent history, both a growing awareness of how scientific and societal uncertainty impacts management decisions and of the intrinsic value of nature have suggested new approaches to forest management, with a growing debate in forest science over the need for a paradigmatic shift from the classic conventional world view, based on determinism, predictability, and output-oriented management, towards a world view that has roots in complex adaptive systems theory and is consistent with a nature-based ethic. A conceptual framework under this context is provided by systemic silviculture. In this discussion, we analyze how this approach can be linked to three fundamental moments of the history of forestry and forest science: the Dauerwald theory, Gurnaud's control method, and the origins of environmental ethics. Relationships with the recent history of forest management science and current research perspectives are also highlighted.4n
Digital Libraries in Open Education: the Italy case,
Open Education strategies, and specifically MOOC (Massive Open Online Courses) and OER (Open
Educational Resources), play an important role in supporting policies for educational innovation, lifelong
learning, and, more generally, the enlargement of educational opportunities for all. While there is an
increasing interest in Open Education, there is little awareness about the role of Digital Library as learning
incubators for learning enhancement. The paper presents briefly the state of art of Digital libraries in the
light of the most recent initiatives of Open Education in Italy, towards an integrated model of Digital
libraries as “knowledge and learning open hubs”
Assessment of Health Literacy and validation of single-item literacy screener (SILS) in a sample of Italian people
Modeling of shock absorption in athletics track surfaces
In this work, the possibility of predicting the force reduction (FR) characterizing the shock absorption capability of track surfaces by finite element modeling was investigated. The mechanical responses of a typical sport surface and of a reference material were characterized by quasi-static uniaxial compression experiments and fitted by Neo-Hookean and Mooney–Rivlin’s hyperelastic models to select the more appropriate one. Furthermore, in order to examine the materials behavior at strain rates typical of athletics applications, the rate dependence of the constitutive parameters was investigated. A finite element model, taking into consideration the post-impact nonlinear dynamics of the track surface and of the system (track surface + artificial athlete), was developed and validated through comparison with the results of FR tests. The simulations showed a very good agreement with the experiments and allowed to interpret the experimentally observed combined effect of track thickness and material intrinsic properties on the overall surface behavior
Multiple double-exchange mechanism by Mn-doping in manganite compounds
Double-exchange mechanisms in REAEMnO manganites (where
RE is a trivalent rare-earth ion and AE is a divalent alkali-earth ion) relies
on the strong exchange interaction between two Mn and Mn ions
through interfiling oxygen 2p states. Nevertheless, the role of RE and AE ions
has ever been considered "silent" with respect to the DE conducting mechanisms.
Here we show that a new path for DE-mechanism is indeed possible by partially
replacing the RE-AE elements by Mn-ions, in La-deficient
LaMnO thin films. X-ray absorption spectroscopy demonstrated
the relevant presence of Mn ions, which is unambiguously proved to be
substituted at La-site by Resonant Inelastic X-ray Scattering. Mn is
proved to be directly correlated to the enhanced magneto-transport properties
because of an additional hopping mechanism trough interfiling Mn-ions,
theoretically confirmed by calculations within the effective single band model.
The very idea to use Mn both as a doping element and an ions
electronically involved in the conduction mechanism, has never been foreseen,
revealing a new phenomena in transport properties of manganites. More
important, such a strategy might be also pursed in other strongly correlated
materials.Comment: 6 pages, 5 figure
Recurrent Ascending Colon Cancer Manifesting as Inferior Vena cava Thrombus
We report an extremely rare case of recurrent ascending colon cancer manifesting as inferior vena cava (IVC) thrombus. A 77-year-old woman previously diagnosed with ascending colon cancer underwent right hemicolectomy with lymph node dissection. Though the tumor invaded the retroperitoneum and involved the right ovarian artery and vein, curative operation was performed. The patient took 5-FU p.o. Two and a half years later, tumor thrombus in the IVC extending into the right atrium was incidentally found and diagnosed as recurrence of colon cancer by biopsy. RF-induced hyperthermia using 5-FU and CDDP i.v. was immediately performed, but she died after 6 months because of multiple liver and pulmonary metastases. In treating colon cancers invading the retroperitoneum, it should be recalled that some cases recur as tumor thrombus in the IVC and that close follow-up is therefore necessary
A retrospective study on acute health effects due to volcanic ash exposure during the eruption of Mount Etna (Sicily) in 2002
Acoustic telemetry and accelerometers: a field comparison of different proxies for activity in the marine environment
Different proxies for activity are used in the field of acoustic telemetry, a leading technology for the study of behaviour in the aquatic environment. Acoustic telemetry poses some shortcomings that may condition data interpretation. Here, we assessed some approaches commonly used to infer activity from acoustic telemetry data using acceleration biologgers as a benchmark. Specifically, we assessed (1) the performance of internal acceleration transmitters, (2) the consequences of averaging acceleration data into increasing time bins, (3) the occurrence of sampling bias in telemetry data acquisition, and (4) the performance of the number of detections and the depth range as proxies for activity. Despite some constraints of acoustic telemetry, acceleration transmitters had a good performance. Conversely, the number of detections and the depth range did not match well the activity estimates provided by acceleration biologgers. Besides, our results pointed to some issues in models concerning the predictive power of acceleration transmitters (linear predictor) over acceleration biologgers, warned about potential sampling bias associated with data acquisition with acoustic telemetry, and highlighted the relevance of considering inter-individual differences in behavioural studies. Finally, we provided some methodological perspectives that should be considered to plan fieldwork, analyse data, and interpret results on animal activity obtained with acoustic telemetry.info:eu-repo/semantics/publishedVersio
The southernmost beech (Fagus sylvatica) forests of Europe (Mount Etna, Italy): ecology, structural stand-type diversity and management implications
The southernmost European beech forests are located in the upper forest vegetation belt on Mount Etna volcano. Their standstructural
patterns were analysed to assess the effects of the site-ecological factors and previous management practices on the
forest structure. Five main structural-silvicultural types were identified among the main beech forest types: coppice, highmountain
coppice (HMCo), high forest, coppice in conversion to high-forest and non-formal stand. A detailed standstructural
analysis was carried out through measured dendrometric parameters and derived structural characters linked to
both the horizontal and the vertical profiles. Plant regeneration processes were also assessed, and several biodiversity
indicators were calculated. The collected data indicate a high variability of beech stand structures in relation to the
heterogeneity of the site-ecological characteristics as well as to the effects of both natural and anthropic disturbance factors.
The occurrence of particular stand structures along the altitude gradient on Mount Etna is evident. It is especially visible in
the multi-stemmed HMCos in relation to the changing, and increasingly limiting, ecological factors, although at higher
altitudes historical anthropic actions (felling) also have had an influence. Inside the Mediterranean area, these stands highlight
their ecological marginality, in terms of both latitude and altitude, especially regarding current climate change processes
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