1,359 research outputs found
Null-plane Quantum Universal -matrix
A non-linear map is applied onto the (non-standard) null-plane deformation of
(3+1) Poincar\'e algebra giving rise to a simpler form of this triangular
quantization. A universal -matrix for the null plane quantum algebra is then
obtained from a universal -matrix corresponding to a Hopf subalgebra.
Finally, the associated Poincar\'e Poisson--Lie group is quantized by using the
FRT approach.Comment: 8 pages, LaTe
3D reconstruction of train accident scene based on monocular image
To help with making an emergency rescue plan for train accidents, a rapid 3D reconstruction
method of train accident scene based on a monocular image was proposed. Taking two
camera projection models for different application scenarios into consideration, the SIFT algorithm
was introduced to extract and match image feature with the CAD model of an accident train.
Geometric constraints between carriages were provided to transform the 3D reconstruction to
solving a nonlinear least square problem with constraints, by which the position and pose of accident
subjects were reduced at last. To quantitatively and qualitatively verify the calculation performance
of this method, the mimicked train accident scene and real train accident scene were
respectively used to carry out 3D reconstruction. The precise finite camera projection model was
applied in the mimicked train accident scene to carry out offline calibration, and the stable
pin-hole model was adopted in the real train accident scene to carry out auto calibration. Analysis
result shows that through quantitative analysis of mimicked scene the maximal and average relative
error of 8 nodes for measurement in reconstructing two carriages are 4.54% and 1.85% respectively.
Through qualitative analysis of the real scene, the 3D reduction of position and pose
for carriages can also be realized with combining the topographic information correction. The
whole accident environmental panorama can be reduced visually with the help of 3D visualization
engine. This method can also be used in developing emergency rescue electronic sand table for
train accident analysis and safety education
mixing and new physics effects in a top quark two-Higgs doublet model
We calculate the new physics contributions to the neutral and
meson mass splitting and induced by the box diagrams
involving the charged-Higgs bosons in the top quark two-Higgs doublet model
(T2HDM). Using the precision data, we obtain the bounds on the parameter space
of the T2HDM: (a) for fixed GeV and , the
upper bound on is after the inclusion of
major theoretical uncertainties; (b) for the case of , a
light charged Higgs boson with a mass around 300 GeV is allowed; and (c) the
bounds on and are strongly correlated: a smaller (larger)
means a lighter (heavier) charged Higgs boson.Comment: 11 pages, 2 EPS figures, RevTex, new references adde
Universal Correlations of Coulomb Blockade Conductance Peaks and the Rotation Scaling in Quantum Dots
We show that the parametric correlations of the conductance peak amplitudes
of a chaotic or weakly disordered quantum dot in the Coulomb blockade regime
become universal upon an appropriate scaling of the parameter. We compute the
universal forms of this correlator for both cases of conserved and broken time
reversal symmetry. For a symmetric dot the correlator is independent of the
details in each lead such as the number of channels and their correlation. We
derive a new scaling, which we call the rotation scaling, that can be computed
directly from the dot's eigenfunction rotation rate or alternatively from the
conductance peak heights, and therefore does not require knowledge of the
spectrum of the dot. The relation of the rotation scaling to the level velocity
scaling is discussed. The exact analytic form of the conductance peak
correlator is derived at short distances. We also calculate the universal
distributions of the average level width velocity for various values of the
scaled parameter. The universality is illustrated in an Anderson model of a
disordered dot.Comment: 35 pages, RevTex, 6 Postscript figure
Revisiting the method to obtain the mechanical properties of hydrided fuel cladding in the hoop direction
The method reported in the literature to calculate the stress–strain curve of nuclear fuel cladding from ring tensile test is revisited in this paper and a new alternative is presented. In the former method, two universal curves are introduced under the assumption of small strain. In this paper it is shown that these curves are not universal, but material-dependent if geometric nonlinearity is taken into account. The new method is valid beyond small strains, takes geometric nonlinearity into consideration and does not need universal curves. The stress–strain curves in the hoop direction are determined by combining numerical calculations with experimental results in a convergent loop. To this end, ring tensile tests were performed in unirradiated hydrogen-charged samples. The agreement among the simulations and the experimental results is excellent for the range of concentrations tested (up to 2000 wppm hydrogen). The calculated stress–strain curves show that the mechanical properties do not depend strongly on the hydrogen concentration, and that no noticeable strain hardening occurs. However, ductility decreases with the hydrogen concentration, especially beyond 500 wppm hydrogen. The fractographic results indicate that as-received samples fail in a ductile fashion, whereas quasicleavage is bserved in the hydrogen-charged samples
Biomarker-guided sequential targeted therapies to overcome therapy resistance in rapidly evolving highly aggressive mammary tumors
Combinatorial targeted therapies are more effective in treating cancer by blocking by-pass mechanisms or inducing synthetic lethality. However, their clinical application is hampered by resistance and toxicity. To meet this important challenge, we developed and tested a novel concept of biomarker-guided sequential applications of various targeted therapies using ErbB2-overexpressing/PTEN-low, highly aggressive breast cancer as our model. Strikingly, sustained activation of ErbB2 and downstream pathways drives trastuzumab resistance in both PTEN-low/trastuzumab-resistant breast cancers from patients and mammary tumors with intratumoral heterogeneity from genetically-engineered mice. Although lapatinib initially inhibited trastuzumab-resistant mouse tumors, tumors by-passed the inhibition by activating the PI3K/mTOR signaling network as shown by the quantitative protein arrays. Interestingly, activation of the mTOR pathway was also observed in neoadjuvant lapatinib-treated patients manifesting lapatinib resistance. Trastuzumab + lapatinib resistance was effectively overcome by sequential application of a PI3K/mTOR dual kinase inhibitor (BEZ235) with no significant toxicity. However, our p-RTK array analysis demonstrated that BEZ235 treatment led to increased ErbB2 expression and phosphorylation in genetically-engineered mouse tumors and in 3-D, but not 2-D, culture, leading to BEZ235 resistance. Mechanistically, we identified ErbB2 protein stabilization and activation as a novel mechanism of BEZ235 resistance, which was reversed by subsequent treatment with lapatinib + BEZ235 combination. Remarkably, this sequential application of targeted therapies guided by biomarker changes in the tumors rapidly evolving resistance doubled the life-span of mice bearing exceedingly aggressive tumors. This fundamentally novel approach of using targeted therapies in a sequential order can effectively target and reprogram the signaling networks in cancers evolving resistance during treatment. © 2014 IBCB, SIBS, CAS All rights reserved
Granular discharge and clogging for tilted hoppers
We measure the flux of spherical glass beads through a hole as a systematic
function of both tilt angle and hole diameter, for two different size beads.
The discharge increases with hole diameter in accord with the Beverloo relation
for both horizontal and vertical holes, but in the latter case with a larger
small-hole cutoff. For large holes the flux decreases linearly in cosine of the
tilt angle, vanishing smoothly somewhat below the angle of repose. For small
holes it vanishes abruptly at a smaller angle. The conditions for zero flux are
discussed in the context of a {\it clogging phase diagram} of flow state vs
tilt angle and ratio of hole to grain size
Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths
[EN] Gas dynamic codes are computational tools applied to the analysis of air management in internal combustion engines. The governing equations in one-dimensional elements are approached assuming compressible unsteady non-homentropic flow and are commonly solved applying finite difference numerical methods. These techniques can also be applied to the calculation of flow transport in complex systems such as wallflow monoliths. These elements are characterized by alternatively plugged channels with porous walls. It filters the particulates when the flowgoes through thewall from the inlet to the outlet channels. Therefore, this process couples the solution of every pair of inlet and outlet channels. In this study, the adaptation of the two-step Lax and Wendroff method and the space-time Conservation Element and Solution Element method is performed to be applied in the solution of flow transport in wall-flow monolith channels. The influence on the prediction ability is analysed by a shock-tube test and experimental data obtained under impulsive flow conditions.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through grant number DPI2010-20891-C02-02.Serrano, JR.; Arnau Martínez, FJ.; Piqueras, P.; García Afonso, Ó. (2014). Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths. International Journal of Computer Mathematics. 91(1):71-84. https://doi.org/10.1080/00207160.2013.783206S718491
Unitarity Triangles and the Search for New Physics
Assuming that the Kobayashi-Maskawa mechanism gives the dominant contribution
to CP violation at low energies, we propose a novel way of testing the flavour
sector of the Standard Model which has the potencial for discovering New
Physics. Using 3 x 3 unitarity of the V_{CKM} matrix and choosing a complete
set of rephasing invariant phases, we derive a set of exact relations in terms
of measurable quantities, namely moduli of V_{CKM} and arguments of rephasing
invariant quartets. These tests complement the usual analysis in the \rho, \eta
plane and, if there is New Physics, may reveal its source.Comment: 20 pages, 7 figures, uses tcilate
Determination of maintenance energy requirement and responses of dry ewes to dietary inclusion of lucerne versus concentrate meal
Publication history: Accepted - 2 February 2021; Published online - 23 May 2021An accurate value for metabolizable energy (ME) requirement for maintenance (MEm) is essential to enable sheep husbandry practice to reach its potential. The objectives of the study were to use calorimetry chamber data of dry ewes (Hu × thin-tail Han F1 crossbred) to develop updated MEm, examine effects of substituting concentrate feed with lucerne hay on energy partitioning, and explore the relationships between energy utilization and fasting heat production (FHP). Data were collected from three experiments. In Exps. 1, 2a and 2b, lucerne hay was used to replace concentrates in three levels (0:40%, 15:25% and 30:10%), with diets containing 60% maize stover (Exp. 1), fresh rye forage (Exp. 2a) or dry rye forage (Exp. 2b). Within each experiment, diets were isoenergetic (digestible energy, DE) and isonitrogenous. Exp. 3 aimed at evaluating effects of three BW levels on nutrient utilization of dry ewes offered diets containing 60% maize stover, 15% lucerne hay and 25% concentrates. Energy metabolism data were measured using the respiration calorimeter chamber technique in all three experiments, followed by the measurement of FHP in Exps. 1, 2b and 3. The MEm derived from the linear regression between energy balance (EB) and ME intake was 0.440 MJ/kg BW0.75. The average FHP was 0.326 MJ/kg BW0.75. The fasting metabolism, net energy requirement for maintenance (NEm) and MEm were estimated to be 0.336, 0.359 and 0.511 MJ/kg BW0.75, respectively, through adjustment of FHP using fasting urinary energy output, activity allowance and efficiency of ME use for maintenance. The FHP was negatively correlated to EB/metabolic BW, ME/gross energy (GE), ME/DE, EB/GE intake and EB/ME intake, while positively correlated to HP/GE intake, HP/ME intake and CH4-E/GE intake. Compared to zero lucerne hay diet, the 15% lucerne hay intake decreased HP (MJ/d), and had no negative effects on EB (MJ/d) or energy utilization efficiencies. The results indicate that nutrient requirement standards currently used across the world are likely to underestimate MEm for dry ewes, and the selection of low FHP ewes for breeding has the potential to improve sheep production efficiency.This study was funded by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA2010010203), Gansu Provincial Science and Technology Support for Returning Grazing to Grass (18-0284), Gansu Provincial Key Project of Scientific and Technical Supporting Programs (18ZD2FA009), and the Program for Innovative Research Team of Chinese Ministry of Education (IRT_17R250)
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