3,642 research outputs found
Computational Fluid Dynamics of Reacting Flows at Surfaces: Methodologies and Applications
This review presents the numerical algorithms and speed-up strategies developed to couple continuum macroscopic simulations and detailed microkinetic models in the context of multiscale approaches to chemical reactions engineering. CFD simulations and hierarchical approaches are discussed both for fixed and fluidized systems. The foundations of the methodologies are reviewed together with specific examples to show the applicability of the methods. These concepts play a pivotal role to enable the first-principles multiscale approach to systems of technological relevance
Local and system mechanisms for action execution and observation in parietal and premotor cortices
The action observation network (AON) includes a system of brain areas largely shared with action execution in both human and nonhuman primates. Yet temporal and tuning specificities of distinct areas and of physiologically identified neuronal classes in the encoding of self and others’ action remain unknown. We recorded the activity of 355 single units from three crucial nodes of the AON, the anterior intraparietal area (AIP), and premotor areas F5 and F6, while monkeys performed a Go/No-Go grasping task and observed an experimenter performing it. At the system level, during task execution, F6 displays a prevalence of suppressed neurons and signals whether an action has to be performed, whereas AIP and F5 share a prevalence of facilitated neurons and remarkable target selectivity; during task observation, F5 stands out for its unique prevalence of facilitated neurons and its stronger and earlier modulation than AIP and F6. By applying unsupervised clustering of spike waveforms, we found distinct cell classes unevenly distributed across areas, with different firing properties and carrying specific visuomotor signals. Broadly spiking neurons exhibited a balanced amount of facilitated and suppressed activity during action execution and observation, whereas narrower spiking neurons showed more mutually facilitated responses during the execution of one's own and others’ action, particularly in areas AIP and F5. Our findings elucidate the time course of activity and firing properties of neurons in the AON during one's own and others’ action, from the system level of anatomically distinct areas to the local level of physiologically distinct cell classes
Shared multisensory experience affects Others' boundary: The enfacement illusion in schizophrenia
Schizophrenia has been described as a psychiatric condition characterized by deficits in one's own and others' face recognition, as well as by a disturbed sense of body-ownership. To date, no study has integrated these two lines of research with the aim of investigating Enfacement Illusion (EI) proneness in schizophrenia. To accomplish this goal, the classic EI protocol was adapted to test the potential plasticity of both Self-Other and Other-Other boundaries. Results showed that EI induced the expected malleability of Self-Other boundary among both controls and patients. Interestingly, for the first time, the present study demonstrates that also the Other-Other boundary was influenced by EI. Furthermore, comparing the two groups, the malleability of the Other-Other boundary showed an opposite modulation. These results suggest that, instead of greater Self-Other boundary plasticity, a qualitative difference can be detected between schizophrenia patients and controls in the malleability of the Other-Other boundary. The present study points out a totally new aspect about body-illusions and schizophrenia disorder, demonstrating that EI is not only confined to self-sphere but it also affects the way we discriminate others, representing a potential crucial aspect in the social domain
Developing keratin sponges with tunable morphologies and controlled antioxidant properties induced by doping with polydopamine (PDA) nanoparticles
his work investigates the preparation of wool keratin sponges by freeze-drying procedure starting form keratin aqueous solutions. The study highlights the correlations between process parameters (protein concentration and freezing rate) and the chemical-physical properties of the final sponges.
In particular, as the keratin concentration increases from 1 to 20% wt, the mean pore size and the porosity decrease from 62 to 37 mu m and from 94 to 50% respectively, while the chemical stability in physiological conditions increases, as well as the thermal stability and the elastic modulus. On the other hand, the increase of the freezing rate affects the design of sponges that appear as stacked leaflets structures with oriented pores.
Moreover, in order to confer to keratin sponges antioxidant properties, polydopamine (PDA) nanoparticles were used as fillers. To this end, PDA nanoparticles of about 130 nm were successfully dispersed in the sponges, bestowing time-dependent anti-oxidant properties on the scaffolds, with no significant modification of sponges morphological structure as well as reduction of the thermal stability and mechanical behaviour
State space modelling and data analysis exercises in LISA Pathfinder
LISA Pathfinder is a mission planned by the European Space Agency to test the
key technologies that will allow the detection of gravitational waves in space.
The instrument on-board, the LISA Technology package, will undergo an
exhaustive campaign of calibrations and noise characterisation campaigns in
order to fully describe the noise model. Data analysis plays an important role
in the mission and for that reason the data analysis team has been developing a
toolbox which contains all the functionalities required during operations. In
this contribution we give an overview of recent activities, focusing on the
improvements in the modelling of the instrument and in the data analysis
campaigns performed both with real and simulated data.Comment: Plenary talk presented at the 9th International LISA Symposium, 21-25
May 2012, Pari
First array of enriched ZnSe bolometers to search for double beta decay
The R&D activity performed during the last years proved the potential of ZnSe
scintillating bolometers to the search for neutrino-less double beta decay,
motivating the realization of the first large-mass experiment based on this
technology: CUPID-0. The isotopic enrichment in Se, the ZnSe
crystals growth, as well as the light detectors production have been
accomplished, and the experiment is now in construction at Laboratori Nazionali
del Gran Sasso (Italy). In this paper we present the results obtained testing
the first three ZnSe crystals operated as scintillating bolometers, and
we prove that their performance in terms of energy resolution, background
rejection capability and intrinsic radio-purity complies with the requirements
of CUPID-0
A strategy to characterize the LISA-Pathfinder cold gas thruster system
The cold gas micro-propulsion system that will be used during the LISA-Pathfinder mission will be one of the most important component used to ensure the "free-fall" of the enclosed test masses. In this paper we present a possible strategy to characterize the effective direction and amplitude gain of each of the 6 thrusters of this system
Kinetic, Structural, and EPR Studies Reveal That Aldehyde Oxidoreductase from Desulfovibrio gigas Does Not Need a Sulfido Ligand for Catalysis and Give Evidence for a Direct Mo-C Interaction in a Biological System
J. Am. Chem. Soc., 2009, 131 (23), pp 7990–7998
DOI: 10.1021/ja809448rAldehyde oxidoreductase from Desulfovibrio gigas (DgAOR) is a member of the xanthine oxidase(XO) family of mononuclear Mo-enzymes that catalyzes the oxidation of aldehydes to carboxylic acids.
The molybdenum site in the enzymes of the XO family shows a distorted square pyramidal geometry in which two ligands, a hydroxyl/water molecule (the catalytic labile site) and a sulfido ligand, have been
shown to be essential for catalysis. We report here steady-state kinetic studies of DgAOR with the inhibitors cyanide, ethylene glycol, glycerol, and arsenite, together with crystallographic and EPR studies of the enzyme after reaction with the two alcohols. In contrast to what has been observed in other members of the XO family, cyanide, ethylene glycol, and glycerol are reversible inhibitors of DgAOR. Kinetic data with both
cyanide and samples prepared from single crystals confirm that DgAOR does not need a sulfido ligand for catalysis and confirm the absence of this ligand in the coordination sphere of the molybdenum atom in the active enzyme. Addition of ethylene glycol and glycerol to dithionite-reduced DgAOR yields rhombic Mo(V)EPR signals, suggesting that the nearly square pyramidal coordination of the active enzyme is distorted upon alcohol inhibition. This is in agreement with the X-ray structure of the ethylene glycol and glycerolinhibited enzyme, where the catalytically labile OH/OH2 ligand is lost and both alcohols coordinate the Mo site in a η2 fashion. The two adducts present a direct interaction between the molybdenum and one of the carbon atoms of the alcohol moiety, which constitutes the first structural evidence for such a bond in a
biological system
Free-flight experiments in LISA Pathfinder
The LISA Pathfinder mission will demonstrate the technology of drag-free test
masses for use as inertial references in future space-based gravitational wave
detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free
flight about a test mass while measuring the acceleration of this primary test
mass relative to a second reference test mass. Because the reference test mass
is contained within the same spacecraft, it is necessary to apply forces on it
to maintain its position and attitude relative to the spacecraft. These forces
are a potential source of acceleration noise in the LISA Pathfinder system that
are not present in the full LISA configuration. While LISA Pathfinder has been
designed to meet it's primary mission requirements in the presence of this
noise, recent estimates suggest that the on-orbit performance may be limited by
this `suspension noise'. The drift-mode or free-flight experiments provide an
opportunity to mitigate this noise source and further characterize the
underlying disturbances that are of interest to the designers of LISA-like
instruments. This article provides a high-level overview of these experiments
and the methods under development to analyze the resulting data.Comment: 13 pages, 5 figures. Accepted to Journal Of Physics, Conference
Series. Presented at 10th International LISA Symposium, May 2014,
Gainesville, FL, US
In-flight thermal experiments for LISA pathfinder: simulating temperature noise at the inertial sensors
Thermal Diagnostics experiments to be carried out on board LISA Pathfinder (LPF) will yield a detailed characterisation of how temperature fluctuations affect the LTP (LISA Technology Package) instrument performance, a crucial information for future space based gravitational wave detectors as the proposed eLISA. Amongst them, the study of temperature gradient fluctuations around the test masses of the Inertial Sensors will provide as well information regarding the contribution of the Brownian noise, which is expected to limit the LTP sensitivity at frequencies close to 1 mHz during some LTP experiments. In this paper we report on how these kind of Thermal Diagnostics experiments were simulated in the last LPF Simulation Campaign (November, 2013) involving all the LPF Data Analysis team and using an end-to-end simulator of the whole spacecraft. Such simulation campaign was conducted under the framework of the preparation for LPF operations
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