5,465 research outputs found
Effect of metal clusters on the swelling of gold-fluorocarbon-polymer composite films
We have investigated the phenomenon of swelling due to acetone diffusion in
fluorocarbon polymer films doped with different gold concentrations below the
percolation threshold. The presence of the gold clusters in the polymer is
shown to improve the mixing between the fluorocarbon polymer and the acetone,
which is not a good solvent for this kind of polymers. In order to explain the
experimental results the stoichiometry and the morphology of the polymer--metal
system have been studied and a modified version of the Flory--Huggins model has
been developed
Biofilms and cyclic di-GMP (c-di-GMP) signaling: lessons from Pseudomonas aeruginosa and other bacteria
The cyclic di-GMP (c-di-GMP) second messenger represents a signaling system that regulates many bacterial behaviors and is of key importance for driving the lifestyle switch between motile loner cells and biofilm formers. This review provides an up-to-date compendium of c-di-GMP pathways connected to biofilm formation, biofilm-associated motilities, and other functionalities in the ubiquitous and opportunistic human pathogen Pseudomonas aeruginosa. This bacterium is frequently adopted as a model organism to study bacterial biofilm formation. Importantly, its versatility and adaptation capabilities are linked with a broad range of complex regulatory networks, including a large set of genes involved in c-di-GMP biosynthesis, degradation, and transmission
Geometrical view of quantum entanglement
Although a precise description of microscopic physical problems requires a
full quantum mechanical treatment, physical quantities are generally discussed
in terms of classical variables. One exception is quantum entanglement which
apparently has no classical counterpart. We demonstrate here how quantum
entanglement may be within the de Broglie-Bohm interpretation of quantum
mechanics visualized in geometrical terms, giving new insight into this
mysterious phenomenon and a language to describe it. On the basis of our
analysis of the dynamics of a pair of qubits, quantum entanglement is linked to
concurrent motion of angular momenta in the Bohmian space of hidden variables
and to the average angle between these momenta
A first experimental test of de Broglie-Bohm theory against standard quantum mechanics
De Broglie - Bohm (dBB) theory is a deterministic theory, built for
reproducing almost all Quantum Mechanics (QM) predictions, where position plays
the role of a hidden variable. It was recently shown that different coincidence
patterns are predicted by QM and dBB when a double slit experiment is realised
under specific conditions and, therefore, an experiment can test the two
theories. In this letter we present the first realisation of such a double slit
experiment by using correlated photons produced in type I Parametric Down
Conversion. Our results confirm QM contradicting dBB predictions
Web services and historical cadastral maps: the first step in the implementation of the Web C.A.R.T.E. system
In the State Archive of Como, Northern Italy, about 15000 historical cadastral maps corresponding to 246 current municipalities of Como and Lecco districts are preserved. These maps belong to different cadastral
productions: the Theresian cadastre, promoted in 1718 by Emperor Carl VI and come into force in 1760 during the reign of Maria Teresa; the Lombardo-
Veneto cadastre, started in 1854 and completed, with continuous updates during the time, at the end of the century; and finally some maps of 1905 belonging to the New Lands Cadastre, the first national geometric cadastre after Italian unification of 1861. Maps have not only a considerable artistic value but mostly a cultural and historical one, since they constitute a great source to derive an accurate representation of the territory and its evolutions. For these reasons, the old maps represent nowadays a valuable instrument for historians, scholars and professionals working both in the historical research field and in the urban and territorial planning. The project Web C.A.R.T.E. (Web Catalogo e Archivio delle Rappresentazioni del Territorio e delle sue Evoluzioni), sponsored by the Fondazione Provinciale della Comunità Comasca Onlus, has been started to enhance the immense
cartographic heritage of the State Archive of Como using the most recent technologies of map processing and web services.
After the maps digitization step, performed by the State Archive in agreement with the interested municipalities, a georeferencing and warping procedure is needed to place the cadastral maps in the actual Italian reference system, thus making it possible to overlap them to the current cartography. Being the most of the maps divided in sheets, that have been surveyed and drawn independently from each other, the preliminary step has been to combine the sheets in a single map by applying to them a roto-
translation with a scale variation. The georeferencing of unified maps has then been performed and tested in different software and GIS packages to determine the optimal solution. Finally PCI Geomatica OrthoEngine has been chosen, thanks to its variety of implemented mathematical models and to the possibility of inserting not only Ground Control Points (points of known coordinates, both in the actual cartography and in the historical map, that are used to compute the mathematical model) but also Check Points, points with known coordinates that are not included in the transformation and can therefore be used to check the model accuracy. The residuals of the transformation have then been used to determine the best georeferencing model for each cadastral map, confirming the choice with statistical techniques.
The following step has been the documentation of georeference d maps in terms of metadata, a series of information needed to precisely identify the data and get information about their content, accuracy, accessibility and usage constrains. Metadata schema are currently defined by national and international standards: at the Italian level, the CNIPA (Centro Nazionale per l’Informatica nella Pubblica Amministrazione) proposed in 2006 a standard which is in agreement with the European Directive INSPIRE and defines a common set of metadata related to all kinds of geographic information used by national Public Administrations. Metadata for the historical georeferenced maps have therefore been compiled according to the Italian standard; last step has been their publication on the Internet through GeoNetwork, an open source web geo-catalogue that allows users to immediately identify a data and derive (from its metadata) information about language, spatial extent, reference system, responsible person or agency, accessibility, possible limitations on the usage, data origin and production process, and other features.
Digitized and georeferenced maps, accompanied by their metadata, can finally be visualized and navigated online through the implementation of a dedicated webGIS. The realization of this viewing service implies the usage of software and tools both from the server and the client-side. Applying FOSS (Free and Open Source Software) solutions, a system with interactive functionalities and able to manage large raster maps has been developed. The entire service is currently in a test phase to verify its fulfilment of specific requests and needs expressed by experts from the State Archive; for this reason it may be possible that new and improved solutions will be introduced in the future
Host galaxies of high-redshift quasars: SMBH growth and feedback
The properties of quasar-host galaxies might be determined by the growth and feedback of their supermassive black holes (SMBHs, 108-10 M⊙). We investigate such connection with a suite of cosmological simulations of massive (halo mass ≈1012 M⊙) galaxies at z ≃ 6 that include a detailed subgrid multiphase gas and accretion model. BH seeds of initial mass 105 M⊙ grow mostly by gas accretion, and become SMBH by z = 6 setting on the observed MBH-M∗ relation without the need for a boost factor. Although quasar feedback crucially controls the SMBH growth, its impact on the properties of the host galaxy at z = 6 is negligible. In our model, quasar activity can both quench (via gas heating) or enhance (by interstellar medium overpressurization) star formation. However, we find that the star formation history is insensitive to such modulation as it is largely dominated, at least at z > 6, by cold gas accretion from the environment that cannot be hindered by the quasar energy deposition. Although quasar-driven outflows can achieve velocities > 1000 km s-1, only ≈4 per cent of the outflowing gas mass can actually escape from the host galaxy. These findings are only loosely constrained by available data, but can guide observational campaigns searching for signatures of quasar feedback in early galaxies
Alveolar recruitment manoeuvre in laterally recumbent anaesthetized sheep.
General anaesthesia in laterally recumbent sheep under spontaneous ventilating may cause hypoxaemia as previously reported.
The stepwise ARM followed by mechanical ventilation with PEEP at 5 cmH2O, improves the oxygenation indices and decrease the amount of venous admixture evaluated by the F-shunt.
The positive effects of the ARM are still present in most of the animals at recovery
Advances in the management of HPV-related oropharyngeal cancer
Patients with human papillomavirus- (HPV-) related oropharyngeal squamous cell carcinoma (OPSCC) have a better prognosis
than HPV-negative OPSCC when treated with standard high-dose cisplatin-based chemoradiotherapy. Consistent with this
assertion and due to younger age at diagnosis, novel approaches tominimize treatment sequelaewhile preserving survival outcomes
become of paramount importance. Here, we critically reviewed the evidence-based literature supporting the deintensification
strategies in HPV-related OPSCC management, including radiotherapy dose and/or volume reduction, replacement of cisplatin
radiosensitising chemotherapy, and the use of transoral surgery. Undoubtedly, further researches are needed before changing the
standard of care in this setting of patients
Protein stability, folding and misfolding in human PGK1 deficiency
Conformational diseases are often caused by mutations, altering protein folding and stability in vivo. We review here our recent work on the effects of mutations on the human phosphoglycerate kinase 1 (hPGK1), with a particular focus on thermodynamics and kinetics of protein folding and misfolding. Expression analyses and in vitro biophysical studies indicate that disease-causing mutations enhance protein aggregation propensity. We found a strong correlation among protein aggregation propensity, thermodynamic stability, cooperativity and dynamics. Comparison of folding and unfolding properties with previous reports in PGKs from other species suggests that hPGK1 is very sensitive to mutations leading to enhance protein aggregation through changes in protein folding cooperativity and the structure of the relevant denaturation transition state for aggregation. Overall, we provide a mechanistic framework for protein misfolding of hPGK1, which is insightful to develop new therapeutic strategies aimed to target native state stability and foldability in hPGK1 deficient patients. © 2013 by the authors; licensee MDPI, Basel, Switzerland
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