320 research outputs found
Determination of the vacancy migration enthalpy by Monte Carlo simulation of the short-range order kinetics by a vacancy diffusion mechanism in Ni-Al alloys.
Nickel-based superalloys are used for the manufacture of pieces evolving in hot parts of aircraft engines. They are constituted of a Ni3-Al long-range ordered intermetallic phase dispersed in a short-range order matrix corresponding to a nickel-based solid solution [1]. These materials have the particularity of having a high melting temperature, a relatively low density, a good resistance to oxidation and an extreme hardness [2]. Their performance strongly depends on the structural and dimensional stability (creep). They are therefore conditioned by atomic mobility and the properties of the vacancies. We proposed to study, a series of Nickel based alloys, presenting a short-range order and constituting the matrix' basis of these superalloys. In this work, the isothermal curves of electrical resistivity corresponding to ordering kinetics in a series of Ni-Al alloys, by the Monte Carlo method, were calculated up to the fourth neighbors. We have determined the migration enthalpies of the vacancy in these so-called alloys by the method of slope change [3]
Comparing Tea Leaf Products and Other Forages for In-vitro Degradability, Fermentation, and Methane for Their Potential Use as Natural Additives for Ruminants
Tea leaves are a rich source of plant secondary metabolites such as tannins and saponins that have the potential to manipulate rumen fermentation and to lessen methane (CH4) production.Samples of green tea (GTL), black tea (BTL), their spent leaves after water extraction (SGTL and SBTL), ryegrass hay (RH), ryegrass silage (RS), paddy straws (PS), barley straws (BS), and wheat straws (WS) were compared for their rumen in-vitro organic matter degradability (IVOMD, g/kg DM), pH, ammonia (NH3, mg/L), total volatile fatty acids (tVFA, mmol/L), total gas production (tGP, L/kg OM), and methane output (CH4,L/kg OM) after 28h incubation with buffered rumen fluid under anaerobic conditions at 39oC in glass syringes. One-way ANOVA on Minitab 16 was used to examine differences between products at P<0.05 for four replicate samples. There were no differences between tea leaf products, RH and RS but the straws tended to have lower IVOMD compared with tea leaf products and other forages. GTL produced the lowest NH3 followed by BTL, SGTL, SBTL, and other forages. There were no differences between most tea leaf products, RH, RS, and the straws for tVFA concentration but PS and WS produced the lowest tVFA. GTL, SGTL, and RH had higher tGP than BTL, SBTL, and the straws but they had a lower tGP than RS. GTL, BTL, and SBTL produced similar levels of CH4 as the straws but this was less than RS and SGTL. The results suggest that if tea leaf products are included in the straw-based diets as natural feed additives, they may improve degradability, tVFA, NH3,and tGP production without increasing CH4 output. Low NH3 production for tea leaf products could be the sign of more by-pass protein to be absorbed in small intestine.Keywords: Tea leafproducts, in-vitro measurements, and ruminants
Discrete-State Abstractions of Nonlinear Systems Using Multi-resolution Quantizer
Abstract. This paper proposes a design method for discrete abstrac-tions of nonlinear systems using multi-resolution quantizer, which is ca-pable of handling state dependent approximation precision requirements. To this aim, we extend the notion of quantizer embedding, which has been proposed by the authors ’ previous works as a transformation from continuous-state systems to discrete-state systems, to a multi-resolution setting. Then, we propose a computational method that analyzes how a locally generated quantization error is propagated through the state space. Based on this method, we present an algorithm that generates a multi-resolution quantizer with a specified error precision by finite refine-ments. Discrete abstractions produced by the proposed method exhibit non-uniform distribution of discrete states and inputs.
Immune related endonucleases and GTPases are not associated with tumor response in patients with advanced non-small cell lung cancer treated with checkpoint inhibitors
Immune related endonucleases have recently been described as potential therapeutic targets and predictors of response to treatment with immune checkpoint inhibitors (ICI). The aim is to evaluate the association between the expression of 5 biomarkers involved in the immune response (CD73, CD39, VISTA, Arl4d and Cytohesin-3) in parallel with the more common ICI-predictive markers, PD-L1 expression and Tumor Mutation Burden (TMB) with response to ICI therapy in an advanced non-small cell lung cancer (NSCLC) cohort. METHODS: Patients with advanced NSCLC treated with ICI single agent were divided into responders and non-responders according to RECIST v1.1 and duration of response (DOR) criteria. Immunohistochemistry was performed on pretreatment tumor tissue samples for PD-L1, CD73, CD39, VISTA, Arl4d, and Cytohesin-3 expression. TMB was estimated with NEOplus v2 RUO (NEO New Oncology GmbH) hybrid capture next generation sequencing assay. Resistance mutations in STK11/KEAP1 and positive predictive mutations in ARID1A/POLE were also evaluated. RESULTS: Included were 56 patients who were treated with ICI single agent. The median progression-free and overall survival for the whole cohort was 3.0 (95% CI, 2.4-3.6) and 15 (95% CI, 9.7-20.2) months, respectively. The distribution of CD73 in tumor cells and CD39, VISTA, Arl4d and Cytohesin-3 expression in immune cells were not different between responders and non-responders. Also, PD-L1 and TMB were not predictive for response. The frequency of STK11, KEAP1 and ARID1A mutations was low and only observed in the non-responder group. CONCLUSION: Separate and combined expression of 5 biomarkers involved in the immune response (CD73, CD39, VISTA, Arl4d, and Cytohesin-3) was not associated with response in our cohort of advanced NSCLC patients receiving single agent ICI. To confirm our findings the analysis of independent larger cohorts is warranted
Discovery of long-period variable stars in the very-metal-poor globular cluster M15
We present a search for long-period variable (LPV) stars among giant branch
stars in M15 which, at [Fe/H] ~ -2.3, is one of the most metal-poor Galactic
globular clusters. We use multi-colour optical photometry from the 0.6-m Keele
Thornton and 2-m Liverpool Telescopes. Variability of delta-V ~ 0.15 mag is
detected in K757 and K825 over unusually-long timescales of nearly a year,
making them the most metal-poor LPVs found in a Galactic globular cluster. K825
is placed on the long secondary period sequence, identified for metal-rich
LPVs, though no primary period is detectable. We discuss this variability in
the context of dust production and stellar evolution at low metallicity, using
additional spectra from the 6.5-m Magellan (Las Campanas) telescope. A lack of
dust production, despite the presence of gaseous mass loss raises questions
about the production of dust and the intra-cluster medium of this cluster.Comment: 13 pages, 9 figures, accepted by MNRA
Exact Controllability of the Time Discrete Wave Equation: A Multiplier Approach
In this paper we summarize our recent results on the exact boundary controllability of a trapezoidal time discrete wave equation in a bounded domain. It is shown that the projection of the solution in an appropriate space in which the high frequencies have been filtered is exactly controllable with uniformly bounded controls (with respect to the time-step). By classical duality arguments, the problem is reduced to a boundary observability inequality for a time-discrete wave equation. Using multiplier techniques the uniform observability property is proved in a class of filtered initial data. The optimality of the filtering parameter is also analyzed
Dust, pulsation, chromospheres and their role in driving mass loss from red giants in Galactic globular clusters
Context: Mass loss from red giants in old globular clusters affects the
horizontal branch (HB) morphology and post-HB stellar evolution including the
production of ultraviolet-bright stars, dredge up of nucleosynthesis products
and replenishment of the intra-cluster medium. Studies of mass loss in globular
clusters also allows one to investigate the metallicity dependence of the mass
loss from cool, low-mass stars down to very low metallicities.
Aims: We present an analysis of new VLT/UVES spectra of 47 red giants in the
Galactic globular clusters 47 Tuc (NGC 104), NGC 362, omega Cen (NGC 5139), NGC
6388, M54 (NGC 6715) and M15 (NGC 7078). The spectra cover the wavelength
region 6100-9900A at a resolving power of R = 110,000. Some of these stars are
known to exhibit mid-infrared excess emission indicative of circumstellar dust.
Our aim is to detect signatures of mass loss, identify the mechanism(s)
responsible for such outflows, and measure the mass-loss rates.
Methods: We determine for each star its effective temperature, luminosity,
radius and escape velocity. We analyse the H-alpha and near-infrared calcium
triplet lines for evidence of outflows, pulsation and chromospheric activity,
and present a simple model for estimating mass-loss rates from the H-alpha line
profile. We compare our results with a variety of other, independent methods.
Results: We argue that a chromosphere persists in Galactic globular cluster
giants and controls the mass-loss rate to late-K/early-M spectral types, where
pulsation becomes strong enough to drive shock waves at luminosities above the
RGB tip. This transition may be metallicity-dependent. We find mass-loss rates
of ~10^-7 to 10^-5 solar masses per year, largely independent of metallicity.Comment: 23 pages, 17 figures, accepted for publication in Astronomy and
Astrophysic
Integration of Tumor Mutation Burden and PD-L1 Testing in Routine Laboratory Diagnostics in Non-Small Cell Lung Cancer
In recent years, Non-small cell lung cancer (NSCLC) has evolved into a prime example for precision oncology with multiple FDA-approved "precision" drugs. For the majority of NSCLC lacking targetable genetic alterations, immune checkpoint inhibition (ICI) has become standard of care in first-line treatment or beyond. PD-L1 tumor expression represents the only approved predictive biomarker for PD-L1/PD-1 checkpoint inhibition by therapeutic antibodies. Since PD-L1-negative or low-expressing tumors may also respond to ICI, additional factors are likely to contribute in addition to PD-L1 expression. Tumor mutation burden (TMB) has emerged as a potential candidate; however, it is the most complex biomarker so far and might represent a challenge for routine diagnostics. We therefore established a hybrid capture (HC) next-generation sequencing (NGS) assay that covers all oncogenic driver alterations as well as TMB and validated TMB values by correlation with the assay (F1CDx) used for the CheckMate 227 study. Results of the first consecutive 417 patients analyzed in a routine clinical setting are presented. Data show that fast reliable comprehensive diagnostics including TMB and targetable alterations are obtained with a short turn-around time. Thus, even complex biomarkers can easily be implemented in routine practice to optimize treatment decisions for advanced NSCLC
Contribution of Each Leg to the Control of Unperturbed Bipedal Stance in Lower Limb Amputees: New Insights Using Entropy
The present study was designed to assess the relative contribution of each leg to unperturbed bipedal posture in lower limb amputees. To achieve this goal, eight unilateral traumatic trans-femoral amputees (TFA) were asked to stand as still as possible on a plantar pressure data acquisition system with their eyes closed. Four dependent variables were computed to describe the subject's postural behavior: (1) body weight distribution, (2) amplitude, (3) velocity and (4) regularity of centre of foot pressure (CoP) trajectories under the amputated (A) leg and the non-amputated (NA) leg. Results showed a larger body weight distribution applied to the NA leg than to the A leg and a more regular CoP profiles (lower sample entropy values) with greater amplitude and velocity under the NA leg than under the A leg. Taken together, these findings suggest that the NA leg and the A leg do not equally contribute to the control of unperturbed bipedal posture in TFA. The observation that TFA do actively control unperturbed bipedal posture with their NA leg could be viewed as an adaptive process to the loss of the lower leg afferents and efferents because of the unilateral lower-limb amputation. From a methodological point of view, these results demonstrate the suitability of computing bilateral CoP trajectories regularity for the assessment of lateralized postural control under pathological conditions
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