723 research outputs found

    Some experiences with Krylov vectors and Lanczos vectors

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    This paper illustrates the use of Krylov vectors and Lanczos vectors for reduced-order modeling in structural dynamics and for control of flexible structures. Krylov vectors and Lanczos vectors are defined and illustrated, and several applications that have been under study at The University of Texas at Austin are reviewed: model reduction for undamped structural dynamics systems, component mode synthesis using Krylov vectors, model reduction of damped structural dynamics systems, and one-sided and two-sided unsymmetric block-Lanczos model-reduction algorithms

    Estimating remineralized phosphate and its remineralization rate in the northern East China Sea during Summer 1997 : a snapshot study before Three-Gorges Dam construction

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    © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Terrestrial, Atmospheric and Oceanic Sciences 27 (2016): 955-963, doi:10.3319/TAO.2016.01.24.01(Oc).The northern East China Sea (a.k.a., “The South Sea”) is a dynamic zone that exerts a variety of effects on the marine ecosystem due to Three-Gorges Dam construction. As the northern East China Sea region is vulnerable to climate forcing and anthropogenic impacts, it is important to investigate how the remineralization rate in the northern East China Sea has changed in response to such external forcing. We used an historical hydrographic dataset from August 1997 to obtain a baseline for future comparison. We estimate the amount of remineralized phosphate by decomposing the physical mixing and biogeochemical process effect using water column measurements (temperature, salinity, and phosphate). The estimated remineralized phosphate column inventory ranged from 0.8 to 42.4 mmol P m-2 (mean value of 15.2 ± 12.0 mmol P m-2). Our results suggest that the Tsushima Warm Current was a strong contributor to primary production during the summer of 1997 in the study area. The estimated summer (June - August) remineralization rate in the region before Three-Gorges Dam construction was 18 ± 14 mmol C m-2 d-1.T. Lee was supported by 2-Year Research Grant of Pusan National University. H.-C. Kim was partly supported by KOPRI project (PG15010). I.-N. Kim was partly supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2015R1C1A1A01052051). K.-T. Park was partly supported by KOPRI project (PE17010). J.-H. Kim was partly supported by the program of “Management of Marine Organisms Causing Ecological Disturbance and Harmful Effects” funded by KIMST/MOF. A.M. Macdonald’s contribution was supported by NOAA grant: #NA110AR4310063 and NSF grant: #OCE-1059881

    Spatiotemporally and Sequentially-Controlled Drug Release from Polymer Gatekeeper-Hollow Silica Nanoparticles

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    Combination chemotherapy has become the primary strategy against cancer multidrug resistance; however, accomplishing optimal pharmacokinetic delivery of multiple drugs is still challenging. Herein, we report a sequential combination drug delivery strategy exploiting a pH-triggerable and redox switch to release cargos from hollow silica nanoparticles in a spatiotemporal manner. This versatile system further enables a large loading efficiency for both hydrophobic and hydrophilic drugs inside the nanoparticles, followed by self-crosslinking with disulfide and diisopropylamine-functionalized polymers. In acidic tumour environments, the positive charge generated by the protonation of the diisopropylamine moiety facilitated the cellular uptake of the particles. Upon internalization, the acidic endosomal pH condition and intracellular glutathione regulated the sequential release of the drugs in a time-dependent manner, providing a promising therapeutic approach to overcoming drug resistance during cancer treatment.ope

    Zero mode in the time-dependent symmetry breaking of λϕ4\lambda\phi^4 theory

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    We apply the quartic exponential variational approximation to the symmetry breaking phenomena of scalar field in three and four dimensions. We calculate effective potential and effective action for the time-dependent system by separating the zero mode from other non-zero modes of the scalar field and treating the zero mode quantum mechanically. It is shown that the quantum mechanical properties of the zero mode play a non-trivial role in the symmetry breaking of the scalar λϕ4\lambda \phi^4 theory.Comment: 10 pages, 3 figure

    Modal Analysis and Correlation of International Space Station Early Configurations

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    This paper will summarize the modal analysis and model refinement results for the International Space Station (ISS) Flight-2A mated configuration. To maintain structural integrity of the ISS, structural loading distributions have been rigorously analyzed through numerical simulation and taken into account during the design of the structure and mission operations. The accuracy of the analysis results is directly affected by the precision of mathematical models and estimated input forces. A mathematical model of an ISS configuration is composed of individual component math models. Each component model is required to be correlated with ground test data

    Genetic Effects of FTO and MC4R Polymorphisms on Body Mass in Constitutional Types

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    Sasang constitutional medicine (SCM), a Korean tailored medicine, categorizes human beings into four types through states of physiological imbalances and responsiveness to herbal medicine. One SCM type susceptible to obesity seems sensitive to energy intake due to an imbalance toward preserving energy. Common variants of fat mass and obesity associated (FTO) and melanocortin 4 receptor (MC4R) genes have been associated with increased body mass index (BMI) by affecting energy intake. Here, we statistically examined the association of FTO and MC4R polymorphisms with BMI in two populations with 1370 Koreans before and after SCM typing, and with the lowering of BMI in 538 individuals who underwent a 1-month lifestyle intervention. The increased BMI replicated the association with FTO haplotypes (effect size ≃ 1.1 kg/m2) and MC4R variants (effect size ≃ 0.64 kg/m2). After the lifestyle intervention, the carriers of the haplotype represented by the minor allele of rs1075440 had a tendency to lose more waist-to-hip ratio (0.76%) than non-carriers. The constitutional discrepancy for the accumulation of body mass by the effects of FTO and/or MC4R variants seemed to reflect the physique differences shown in each group of SCM constitutional types. In conclusion, FTO and MC4R polymorphisms appear to play an important role in weight gain, while only FTO variants play a role in weight loss after lifestyle intervention. Different trends were observed among individuals of SCM types, especially for weight gain. Therefore, classification of individuals based on physiological imbalance would offer a good genetic stratification system in assessing the effects of obesity genes

    Anomalous Corrections to Hall Resistivity of Spin-Polarized Two-Dimensional Holes in a GaAs/AlGaAs Heterostructure

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    Hall effect of two-dimensional holes that are spin-polarized by a strong parallel magnetic field was explored with a small tilt angle. The Hall resistivity increases nonlinearly with the magnetic field and exhibits negative corrections. The anomalous negative corrections increase with the perpendicular magnetization of the two-dimensional hole system. We attribute this to the anomalous Hall effect of spin-polarized carriers in a nonmagnetic system. The anomalous corrections to the conductivity exhibit non-monotonic dependence on the magnetic field.Comment: 4 pages, 4 figures, accepted in Phys. Rev.

    Effect of Long-Term Dietary Arginyl-Fructose (AF) on Hyperglycemia and HbA1c in Diabetic db/db Mice

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    We have previously reported that Amadori compounds exert anti-diabetic effects by lowering sucrose-induced hyperglycemia in normal Sprague-Dawley rats. In the present study we extended our recent findings to evaluate whether α-glucosidase inhibitor arginyl-fructose (AF) lowers blood glucose level in diabetic db/db mice, a genetic model for type 2 diabetes. The db/db mice were randomly assigned to high-carbohydrate diets (66.1% corn starch) with and without AF (4% in the diet) for 6 weeks. Changes in body weight, blood glucose level, and food intake were measured daily for 42 days. Dietary supplementation of AF resulted in a significant decrease of blood glucose level (p \u3c 0.001) and body weight (p \u3c 0.001). The level of HbA1c, a better indicator of plasma glucose concentration over prolonged periods of time, was also significantly decreased for 6-week period (p \u3c 0.001). Dietary treatment of acarbose® (0.04% in diet), a positive control, also significantly alleviated the level of blood glucose, HbA1c, and body weight. These results indicate that AF Maillard reaction product improves postprandial hyperglycemia by suppressing glucose absorption as well as decreasing HbA1c level

    Effect of Long-Term Dietary Arginyl-Fructose (AF) on Hyperglycemia and HbA1c in Diabetic \u3cem\u3edb/db\u3c/em\u3e Mice

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    We have previously reported that Amadori compounds exert anti-diabetic effects by lowering sucrose-induced hyperglycemia in normal Sprague-Dawley rats. In the present study we extended our recent findings to evaluate whether α-glucosidase inhibitor arginyl-fructose (AF) lowers blood glucose level in diabetic db/db mice, a genetic model for type 2 diabetes. The db/db mice were randomly assigned to high-carbohydrate diets (66.1% corn starch) with and without AF (4% in the diet) for 6 weeks. Changes in body weight, blood glucose level, and food intake were measured daily for 42 days. Dietary supplementation of AF resulted in a significant decrease of blood glucose level (p \u3c 0.001) and body weight (p \u3c 0.001). The level of HbA1c, a better indicator of plasma glucose concentration over prolonged periods of time, was also significantly decreased for 6-week period (p \u3c 0.001). Dietary treatment of acarbose® (0.04% in diet), a positive control, also significantly alleviated the level of blood glucose, HbA1c, and body weight. These results indicate that AF Maillard reaction product improves postprandial hyperglycemia by suppressing glucose absorption as well as decreasing HbA1c level

    Gas tungsten arc welding of as-rolled CrMnFeCoNi high entropy alloy

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    Fundacao para a Ciencia e Tecnologia (FCT)- project UID/EMS/00667/2019 (UNIDEMI). FMBF acknowledges funding of CENIMAT by FEDER through the program COMPETE 2020 and National Funds through FCT-Portuguese Foundation for Science and Technology, under the project UID/CTM/50025/2019 and FCT/MCTES. This work was supported by the Future Material Discovery Project of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT of Korea (NRF-2016M3D1A1023383). NFFA-Europe Transnational Access Activity (project reference Nf-20010136 EC and ID-806).High entropy alloys have emerged as novel engineering alloys with remarkable mechanical properties in a wide range of temperatures. Among the several high entropy alloys that were already described, the equiatomic CrMnFeCoNi alloy is the most studied one. In this work, gas tungsten arc welding of as-rolled CrMnFeCoNi high entropy alloy sheets was performed. The microstructural characterization encompassed the use of electron microscopy, including electron backscattered diffraction, synchrotron X-ray diffraction analysis, microhardness testing and mechanical evaluation. A comprehensive description of the microstructural evolution, including texture and microstrain determination, of the joint is presented and discussed. Upon mechanical testing, the joints systematically failed in the fusion zone due. The large grain size and low hardness of this region justifies the failure location. The joints' mechanical behaviour is correlated with the material microstructure.publishersversionpublishe
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