98 research outputs found
Experimental Model-Based Linearization of a S.I. Engine Gas Injector Flow Chart
Experimental tests previously executed by the authors on the simultaneous combustion of gasoline and gaseous fuel in a spark ignition
engine revealed the presence of strong nonlinearities in the lower part of the gas injector flow chart. These nonlinearities arise via the injector
outflow area variation caused by the needle impacts and bounces during the transient phenomena that take place in the opening and closing
phases of the injector and may seriously compromise the air-fuel mixture quality control for the lower injection times, thus increasing both fuel
consumption and pollutant emissions.
Despite the extensive literature about the operation and modelling of fuel injectors, there are no known studies focused on the
nonlinearities of the gas injector flow chart and on the way they can be reduced or eliminated. The authors thus developed a mathematical
model for the prediction of mass injected by a spark ignition (S.I.) engine gas injector, validated through experimental data. The gas injector
has been studied with particular reference to the complex needle motion during the opening and closing phases, which may strongly affect
the amount of fuel injected.
In this work, the mathematical model previously developed has been employed to study and determine an appropriate injection strategy
in order to linearize the injector flow chart to the greatest degree possible. The injection strategy proposed by the authors is based on minimum
injection energy considerations and may be easily implemented in current engine control units (ECU) without any hardware modification or
additional costs. Once calibrated by means of simulation, this strategy has been validated by experimental data acquired on an appropriately
equipped injector test bench. As a result, the real injector flow chart has been substantially improved, reducing its deviation from linearity to
one third of the original flow chart, which is an excellent result, especially if the typical measurement dispersion of the injected mass is taken
into account. The injection strategy proposed by the authors could extend the linear behaviour of gas injectors and improve the fuel supply by
means of a simple software update of the ECU, thus obtaining higher engine efficiency and lower pollutant emissions
A trans-Regulatory code for the forebrain expression of Six3.2 in the Medaka fish
A well integrated and hierarchically organized gene regulatory network is responsible for the progressive specification of the forebrain. The transcription factor Six3 is one of the central
components of this network. As such, Six3 regulates several components of the network, but its upstream regulators are still poorly characterized. Here we have systematically identified such regulators, taking advantage of the detailed functional characterization of the regulatory region of the medaka fish Six3.2 ortholog and of a time/cost-effective trans-regulatory screening, which complemented and overcame the limitations of in silico prediction approaches. The candidates resulting from this search were validated with dose-response luciferase assays and expression pattern criteria. Reconfirmed candidates with a matching expression pattern were also tested with chromatin immunoprecipitation and functional studies. Our results confirm the previously proposed direct regulation of Pax6 and further demonstrate that Msx2 and Pbx1 are bona fide direct regulators of early Six3.2 distribution in distinct domains of the medaka fish forebrain. They also point to other transcription factors, including Tcf3, as additional regulators of different spatial-temporal domains of Six3.2 expression. The activity of these regulators is discussed in the context of the gene regulatory network proposed for the specification of the forebrain.Spanish Ministerio de Economía y Competitividad (MINECO) Grants BFU2010-16031 and BFU2013-43213-P, cofounded by FEDER Funds; Comunidad Autónoma de Madrid (CAM) Grant CELL-DD S2010/BMD-2315; Fundaluce; Fundación ONCE; the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) del Instituto Carlos III (ISCIII); and an Institutional Grant from the Fundación Ramón Areces.Peer Reviewe
Genetic testing for Marfan syndrome
Abstract
Marfan syndrome (MFS) is an inherited connective tissue disorder caused by heterozygous mutations in the FBN 1 gene. Clinical manifestations of MFS include aortic dilatation and dissection, as well as cardiac valvular, ocular, skeletal and neurological manifestations. Prevalence varies from 6 to 20 per 100,000 individuals. Revised Ghent Nosology (2010) is used to establish a clinically based suspected diagnosis to be confirmed by molecular testing. This Utility Gene Test was prepared on the basis of an analysis of the literature and existing diagnostic protocols. Molecular testing is useful for diagnosis confirmation, as well as differential diagnosis, appropriate genetic counselling and access to clinical trials
Genetic testing for vascular Ehlers-Danlos syndrome and other variants with fragility of the middle arteries
Abstract
Ehlers-Danlos syndrome (EDS) is an umbrella term for various inherited connective tissue disorders associated with mutations in genes involved in extracellular matrix formation. "The 2017 International Classification of Ehlers-Danlos Syndromes and related disorders" identifies 13 clinical types with mutations in 19 distinct genes. The present module focuses on forms with major vascular involvement: vascular EDS (vEDS) caused by heterozygous mutations in COL3A1, "vascular-like" EDS (vlEDS) caused by recurrent mutations in COL1A1, classical EDS with vascular fragility associated with heterozygous mutations in COL5A1, and kyphoscoliotic EDS associated with recessive variations in PLOD1 and FKBP14. The overall prevalence of EDS is estimated between 1/10,000 and 1/25,000 and vEDS accounts for about 5 to 10% of all EDS cases. This Utility Gene Test was prepared on the basis of an analysis of the literature and existing diagnostic protocols. Molecular testing is useful for diagnosis confirmation, as well as differential diagnosis, appropriate genetic counselling and access to clinical trials
Genetic testing for Marfan-like disorders
Abstract
Marfan-like disorders are inherited conditions with features resembling Marfan syndrome but without a pathogenic variant in FBN1, and/or without a clinical diagnosis of Marfan syndrome according to the Revised Ghent criteria, and/or with a pathogenic variant in a different disease gene. Marfan-like disorders are clinically and genetically heterogeneous and have variable prognosis. They may have autosomal dominant or autosomal recessive patterns of inheritance. The prevalence of most Mar-fan-like disorders is unknown. This Utility Gene Test was prepared on the basis of an analysis of the literature and existing diagnostic protocols. Molecular testing is useful for diagnosis confirmation, as well as differential diagnosis, appropriate genetic counselling and access to clinical trials
TEASPOON: a once in a lifetime opportunity to Sedna
In the challenge of unveiling the enigmas that still surround the origin and early evolution of the Solar System, the study of trans-Neptunian objects plays a crucial role. For this purpose, Sedna is probably the most intriguing candidate for a space mission. A better understanding of its highly elliptical orbit could improve our knowledge of the evolution of the Solar System and could potentially lead to the discovery of an unknown planet. Moreover, the planetoid is expected to host a significant amount of tholins and probably a subsurface ocean of liquid water, making the analysis of its composition extremely interesting. In 2076, Sedna will reach its minimum distance of 76 AU from the Sun. This is a scientific opportunity that will not happen again in the next 11400 years.
Exploiting this instance, TransnEptuniAn Sedna PrObe for Outer exploratioN (TEASPOON) is a mission proposal to send a probe to Sedna, featuring a payload suite to perform an optical characterization, study the particle environment and conduct a radio-science experiment.
Moreover, the long travel will be an opportunity to explore the Kuiper Belt looking for observations or, hopefully, discover new objects. The harsh environment, characterized by objects with unknown trajectories, requires Collision Avoidance strategies, while long-term radiation exposition demands electronics shielding and the preference for rad-hard components. More generally, the 77 AU distance and 30 years duration of the mission makes the design even more demanding. Therefore, solving those challenges would inaugurate a new generation of space missions to the edges of the Solar System and beyond.
This proposal has been developed in the framework of a Space Mission Analysis and Design course by a team of students at the master level in Space Engineering at Politecnico di Milano. A concurrent engineering approach has been followed, leading the study through its phase
0/A. This enabled them to practice in actual working conditions of a space agency’s mission study, and underlined the importance of this kind of experience at a Master’s level course
Synthesis and Characterization of New Lithium and Boron Based Metal Organic Frameworks with NLO Properties for Application in Neutron Capture Therapy
In this work, we synthetized and characterized new crystalline materials with theranostic properties, i.e., they can be used both as bio-sensors and for "drug delivery". The two solid crystalline compounds studied are Metal Organic Frameworks and have formulas Li[(C6H12O6)2B]\ub72H2O and Li[(C4H2O6)2B]\ub75.5H2O. They can be synthetized both with natural isotopes of Li and B or with 6Li and 10B isotopes, that can be explored for Neutron Capture Therapy (NCT) for anti-cancer treatment. The presence of chiral organic molecules, such as mannitol and tartaric acid, provides the NLO property to the crystals and thus their capability to generate the Second Harmonic, which is useful for applications as bio-sensors. The two compounds were characterized with X-ray Diffraction and the Second Harmonic Generation (SHG) responses were estimated by theoretical calculations, and the results were compared with experimental measurements of powdered samples. In order to test the behavior of such compounds under thermal neutron irradiation, we preliminary exposed one of the two compounds in the e_LiBANS facility at the Torino Physics Department. Preliminary results are reported
Photometric determination of the mass accretion rates of pre-main sequence stars. II. NGC346 in the Small Magellanic Cloud
[Abridged] We have studied the properties of the stellar populations in the
field of the NGC346 cluster in the Small Magellanic Cloud, using a novel
self-consistent method that allows us to reliably identify pre-main sequence
(PMS) objects actively undergoing mass accretion, regardless of their age. The
method does not require spectroscopy and combines broad-band V and I photometry
with narrow-band Halpha imaging to identify all stars with excess Halpha
emission and derive the accretion luminosity Lacc and mass accretion rate Macc
for all of them. The application of this method to existing HST/ACS photometry
of the NGC346 field has allowed us to identify and study 680 bona-fide PMS
stars with masses from ~0.4 to ~4 Msolar and ages in the range from ~1 to ~30
Myr. This is the first study to reveal that, besides a young population of PMS
stars (~ 1 Myr old), in this field there is also an older population of PMS
objects with a median age of ~20 Myr. We provide for all of them accurate
physical parameters. We study the evolution of the mass accretion rate as a
function of stellar parameters and find that logMacc ~ -0.6 Log t + Log m + c,
where t is the age of the star, m its mass and c a quantity that is higher at
lower metallicity. The high mass accretion rates that we find suggest that a
considerable fraction of the stellar mass is accreted during the PMS phase and
that PMS evolutionary models that do not account for this effect will
systematically underestimate the true age when compared with the observations.Comment: Accepted for publication in the ApJ. 14 pages, 11 figures. Corrected
typos and reference
Clinical assessment for diet prescription
Accurate nutritional assessment based on dietary intake, physical activity, genetic makeup, and metabolites is required to prevent from developing and/or to treat people suffering from malnutrition as well as other nutrition related health issues. Nutritional screening ought to be considered as an essential part of clinical assessment for every patient on admission to healthcare setups, as well as on change in clinical conditions. Therefore, a detailed nutritional assessment must be performed every time nutritional imbalances are observed or suspected. In this review we have explored different techniques used for nutritional and physical activity assessment. Dietary Intake (DI) assessment is a multidimensional and complex process. Traditionally, dietary intake is assessed through self-report techniques, but due to limitations like biases, random errors, misestimations, and nutrient databases-linked errors, questions arise about the adequacy of self-reporting dietary intake procedures. Despite the limitations in assessing dietary intake (DI) and physical activity (PA), new methods and improved technologies such as biomarkers analysis, blood tests, genetic assessments, metabolomic analysis, DEXA (Dual-energy X-ray absorptiometry), MRI (Magnetic resonance imaging), and CT (computed tomography) scanning procedures have made much progress in the improvement of these measures. Genes also plays a crucial role in dietary intake and physical activity. Similarly, metabolites are also involved in different nutritional pathways. This is why integrating knowledge about the genetic and metabolic markers along with the latest technologies for dietary intake (DI) and physical activity (PA) assessment holds the key for accurately assessing one’s nutritional status and prevent malnutrition and its related complications
Star formation in 30 Doradus
Using observations obtained with the Wide Field Camera 3 (WFC3) on board the
Hubble Space Telescope (HST), we have studied the properties of the stellar
populations in the central regions of 30 Dor, in the Large Magellanic Cloud.
The observations clearly reveal the presence of considerable differential
extinction across the field. We characterise and quantify this effect using
young massive main sequence stars to derive a statistical reddening correction
for most objects in the field. We then search for pre-main sequence (PMS) stars
by looking for objects with a strong (> 4 sigma) Halpha excess emission and
find about 1150 of them over the entire field. Comparison of their location in
the Hertzsprung-Russell diagram with theoretical PMS evolutionary tracks for
the appropriate metallicity reveals that about one third of these objects are
younger than ~4Myr, compatible with the age of the massive stars in the central
ionising cluster R136, whereas the rest have ages up to ~30Myr, with a median
age of ~12Myr. This indicates that star formation has proceeded over an
extended period of time, although we cannot discriminate between an extended
episode and a series of short and frequent bursts that are not resolved in
time. While the younger PMS population preferentially occupies the central
regions of the cluster, older PMS objects are more uniformly distributed across
the field and are remarkably few at the very centre of the cluster. We
attribute this latter effect to photoevaporation of the older circumstellar
discs caused by the massive ionising members of R136.Comment: 15 pages, 12 figures. Accepted for publication in The Astrophysical
Journa
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