2,667 research outputs found
Including coronary ostia in patient-specific 3D models of the whole aortic valve apparatus, derived from TEE, for biomechanical simulations
There is an increasing interest in the numerical modeling and simulation of the aortic valve behavior and functioning, on the different stages involved as healthy, stenotic or replacement procedure. As echocardiography is a ubiquitous and economic modality, the geometric model construction based on such images is therefore of major interest.
In this paper, a new patient-specific approach for modeling the complete aortic valve apparatus - derived from parameters extracted from 3D transesophageal echocardiographs -that includes for the first time the left ventricle outflow tract and the coronary ostia, both crucial for proper assessment of valve biomechanical behavior, is presented. An innovative method for characterizing coronary pressures from patient-specific clinical data, to be used as boundary conditions for the numerical simulation is also described.
Results from experiments were presented to evaluate the novel aspects of the model, that permits to compare the existing models (non-coronary model NCM) and the proposed new coronary model (CM). Variations of displacement and stress on each leaflet prove the need of considering leaflet asymmetry. Computed quantities in the results sections are within the range of physiological data. This permits to conclude that the proposed aortic valve apparatus model of the aortic valve apparatus improves on previous ones by considering this extremely complex structure in greater detail.Xunta de Galicia | Ref. IN606A-2017/02
NIKA 2: next-generation continuum/polarized camera at the IRAM 30 m telescope and its prototype
NIKA 2 (New Instrument of Kids Array) is a next generation continuum and
polarized instrument successfully installed in October 2015 at the IRAM 30 m
telescope on Pico-Veleta (Granada, Spain). NIKA 2 is a high resolution
dual-band camera, operating with frequency multiplexed LEKIDs (Lumped Element
Kinetic Inductance Detectors) cooled at 100 mK. Dual color images are obtained
thanks to the simultaneous readout of a 1020 pixels array at 2 mm and 1140 x 2
pixels arrays at 1.15 mm with a final resolution of 18 and 12 arcsec
respectively, and 6.5 arcmin of Field of View (FoV). The two arrays at 1.15 mm
allow us to measure the linear polarization of the incoming light. This will
place NIKA 2 as an instrument of choice to study the role of magnetic fields in
the star formation process. The NIKA experiment, a prototype for NIKA 2 with a
reduced number of detectors (about 400 LEKIDs) and FoV (1.8 arcmin), has been
successfully operated at the IRAM 30 telescope in several open observational
campaigns. The performance of the NIKA 2 polarization setup has been
successfully validated with the NIKA prototype.Comment: 5 pages, 4 figures, proceeding for the conference: Extragalactic
radio surveys 201
First polarised light with the NIKA camera
NIKA is a dual-band camera operating with 315 frequency multiplexed LEKIDs
cooled at 100 mK. NIKA is designed to observe the sky in intensity and
polarisation at 150 and 260 GHz from the IRAM 30-m telescope. It is a
test-bench for the final NIKA2 camera. The incoming linear polarisation is
modulated at four times the mechanical rotation frequency by a warm rotating
multi-layer Half Wave Plate. Then, the signal is analysed by a wire grid and
finally absorbed by the LEKIDs. The small time constant (< 1ms ) of the LEKID
detectors combined with the modulation of the HWP enables the
quasi-simultaneous measurement of the three Stokes parameters I, Q, U,
representing linear polarisation. In this paper we present results of recent
observational campaigns demonstrating the good performance of NIKA in detecting
polarisation at mm wavelength.Comment: 7 pages, Proceeding for Journal of Low Temperature Physic
Genes involved in ethylene and gibberellins metabolism are required for endosperm-limited germiantion of Sisymbrium officinales L. Seeds
The rupture of the seed coat and that of the endosperm were found to be two sequential events in the germination of Sisymbrium officinale L. seeds, and radicle protrusion did not occur exactly in the micropylar area but in the neighboring zone. The germination patterns were similar both in the presence of gibberellins (GA4+7) and in presence of ethrel. The analysis of genes involved in GAs synthesis and breakdown demonstrated that (1) SoGA2ox6 expression peaked just prior to radicle protrusion (20â22 h), while SoGA3ox2 and SoGA20ox2 expression was high at early imbibition (6 h) diminishing sharply thereafter; (2) the accumulation of SoGA20ox2 transcript was strongly inhibited by paclobutrazol (PB) as well as by inhibitors of ET synthesis and signaling (IESS) early after imbibition (6 h), while SoGA3ox2 and SoGA2ox6 expression was slowly depressed as germination progressed; (3) ethrel and GA4+7 positively or negatively affected expression of SoGA3ox2, SoGA20ox2, and SoGA2ox6, depending on the germination period studied. Regarding genes involved in ET synthesis, our results showed that SoACS7 was expressed, just prior to radicle emergence while SoACO2 expression slowly increased as germination progressed. Both genes were strongly inhibited by PB but were almost unaffected by externally added ethrel or GA4+7. These results suggest that GAs are more important than ET during the early stages of imbibition, while ET is more important at the late phases of germination of S. officinale L. seed
Identification and characterization of a novel non-structural protein of bluetongue virus
Bluetongue virus (BTV) is the causative agent of a major disease of livestock (bluetongue). For over two decades, it has been widely accepted that the 10 segments of the dsRNA genome of BTV encode for 7 structural and 3 non-structural proteins. The non-structural proteins (NS1, NS2, NS3/NS3a) play different key roles during the viral replication cycle. In this study we show that BTV expresses a fourth non-structural protein (that we designated NS4) encoded by an open reading frame in segment 9 overlapping the open reading frame encoding VP6. NS4 is 77â79 amino acid residues in length and highly conserved among several BTV serotypes/strains. NS4 was expressed early post-infection and localized in the nucleoli of BTV infected cells. By reverse genetics, we showed that NS4 is dispensable for BTV replication in vitro, both in mammalian and insect cells, and does not affect viral virulence in murine models of bluetongue infection. Interestingly, NS4 conferred a replication advantage to BTV-8, but not to BTV-1, in cells in an interferon (IFN)-induced antiviral state. However, the BTV-1 NS4 conferred a replication advantage both to a BTV-8 reassortant containing the entire segment 9 of BTV-1 and to a BTV-8 mutant with the NS4 identical to the homologous BTV-1 protein. Collectively, this study suggests that NS4 plays an important role in virus-host interaction and is one of the mechanisms played, at least by BTV-8, to counteract the antiviral response of the host. In addition, the distinct nucleolar localization of NS4, being expressed by a virus that replicates exclusively in the cytoplasm, offers new avenues to investigate the multiple roles played by the nucleolus in the biology of the cell
Identifying and explaining the farming system composition of agricultural landscapes: The role of socioeconomic drivers under strong biophysical gradients
In mountain landscapes, agricultural abandonment is taking place in the most vulnerable areas, while intensification increases in the most productive lands. These
contrasting processes, which have different impacts on biodiversity and ecosystem services (BES), are related to changes in the farming system component of these
landscapes.
Farming systems are identified based on farmerâs decisions on, for example, type of crop and level of fertilizers, which represent the descriptors of farming systems
and can be grouped into several dimensions (e.g. land use and intensity). Since obtaining this data at farm-level is often difficult, an alternative is to study the spatial
combinations of farming systems at parish-level, i.e., Farming System Mixes (FSM), relying on agricultural census data.
Other biophysical (e.g. climate, soil) and socioeconomic (e.g. labour, farmerâs age) variables, independent of farmers' decisions, represent the exogenous drivers of
these decisions. The separation between descriptors and drivers is important to improve knowledge about what drives farmers' decisions regarding farming system
choice, as these choices are often the focus of policies aiming the support of BES.
In this study, we explored the underlying drivers of FSM and assessed the role of socioeconomic drivers, main target for policy makers, in a context of strong
biophysical gradients. Biophysical drivers emerge as those that primarily discriminate between the FSM located in different topographic positions (valleys, mountains
and plateau). In the situations where there is a greater range of productive choices available for farmers, such as in valleys, socioeconomic drivers assume a
preponderant role on farming system choiceinfo:eu-repo/semantics/publishedVersio
Assessment of Platelet REACtivity After Transcatheter Aortic Valve Replacement : The REAC-TAVI Trial
The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI. Current recommendations support short-term use of aspirin + clopidogrel for patients with severe AS undergoing TAVR despite the lack of compelling evidence. This was a prospective, randomized, multicenter investigation. Platelet reactivity was measured at 6 different time points with the VerifyNow assay (Accriva Diagnostics, San Diego, California). HPR was defined as (P2Y reaction units (PRU) âĽ208. Patients with HPR before TAVR were randomized to either aspirin + ticagrelor or aspirin + clopidogrel for 3 months. Patients without HPR continued with aspirin + clopidogrel (registry cohort). The primary endpoint was non-HPR status (PRU <208) in âĽ70% of patients treated with ticagrelor at 90 days post-TAVR. A total of 68 patients were included. Of these, 48 (71%) had HPR (PRU 273 Âą 09) and were randomized to aspirin + ticagrelor (n = 24, PRU 277 Âą 08) or continued with aspirin + clopidogrel (n = 24, PRU 269 Âą 49). The remaining 20 patients (29%) without HPR (PRU 133 Âą 12) were included in the registry. Overall, platelet reactivity across all the study time points after TAVR was lower in patients randomized to ticagrelor compared with those treated with clopidogrel, including those enrolled in the registry (p < 0.001). The primary endpoint was achieved in 100% of patients with ticagrelor compared with 21% with clopidogrel (p < 0.001). Interestingly, 33% of clopidogrel responder patients at baseline developed HPR status during the first month after TAVR. HPR to clopidogrel is present in a considerable number of patients with AS undergoing TAVR. Ticagrelor achieves a better and faster effect, providing sustained suppression of HPR to these patients. (Platelet Reactivity After TAVI: A Multicenter Pilot Study [REAC-TAVI]; NCT02224066
First observation of Bs -> D_{s2}^{*+} X mu nu decays
Using data collected with the LHCb detector in proton-proton collisions at a
centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and
Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass
spectrum at masses consistent with the known D^+_{s1}(2536) and
$D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the
total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)=
(3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm
1.2\pm 0.5)%, where the first uncertainty is statistical and the second is
systematic. This is the first observation of the D_{s2}^{*+} state in Bs
decays; we also measure its mass and width.Comment: 8 pages 2 figures. Published in Physics Letters
Precise measurement of the W-boson mass with the CDF II detector
We have measured the W-boson mass MW using data corresponding to 2.2/fb of
integrated luminosity collected in proton-antiproton collisions at 1.96 TeV
with the CDF II detector at the Fermilab Tevatron collider. Samples consisting
of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement
MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most
precise measurement of the W-boson mass to date and significantly exceeds the
precision of all previous measurements combined
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
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