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排序方式: 共有233条查询结果,搜索用时 11 毫秒
1.
Larisa Anghel Radu Sascu Ioana Mdlina Zota Cristian Sttescu 《International journal of molecular sciences》2021,22(11)
Non-ischemic dilated cardiomyopathy encompasses a wide spectrum of myocardial disorders, characterized by left ventricular dilatation with systolic impairment and increased risk of sudden cardiac death. In spite of all the therapeutic progress that has been made in recent years, dilated cardiomyopathy continues to be an important cause of cardiac transplant, being associated with an enormous cost burden for health care systems worldwide. Predicting the prognosis of patients with dilated cardiomyopathy is essential to individualize treatment. Late gadolinium enhancement-cardiac magnetic resonance imaging, microvolt T-wave alternans, and genetic testing have emerged as powerful tools in predicting sudden cardiac death occurrence and maximizing patient’s selection. Despite all these new diagnostic modalities, additional tests to complement or replace current tools are required for better risk stratification. Therefore, biomarkers are an easy and important tool that can help to detect patients at risk of adverse cardiovascular events. Additionally, identifying potential biomarkers involved in dilated cardiomyopathy can provide us important information regarding the diagnostic, prognostic, risk stratification, and response to treatment for these patients. Many potential biomarkers have been studied in patients with dilated cardiomyopathy, but only a few have been adopted in current practice. Therefore, the aim of our review is to provide the clinicians with an update on the well-known and novel biomarkers that can be useful for risk stratification of patients with non-ischemic dilated cardiomyopathy. 相似文献
2.
Prosenjit Bose Paz Carmi Mirela Damian Robin Flatland Matthew J. Katz Anil Maheshwari 《Algorithmica》2014,69(2):397-409
For any angle α<2π, we show that any connected communication graph that is induced by a set P of n transceivers using omni-directional antennas of radius 1, can be replaced by a strongly connected communication graph, in which each transceiver in P is equipped with a directional antenna of angle α and radius r dir, for some constant r dir=r dir(α). Moreover, the new communication graph is a c-spanner of the original graph, for some constant c=c(α), with respect to number of hops. 相似文献
3.
A tangent vector field on a surface is the generator of a smooth family of maps from the surface to itself, known as the flow. Given a scalar function on the surface, it can be transported, or advected, by composing it with a vector field's flow. Such transport is exhibited by many physical phenomena, e.g., in fluid dynamics. In this paper, we are interested in the inverse problem: given source and target functions, compute a vector field whose flow advects the source to the target. We propose a method for addressing this problem, by minimizing an energy given by the advection constraint together with a regularizing term for the vector field. Our approach is inspired by a similar method in computational anatomy, known as LDDMM, yet leverages the recent framework of functional vector fields for discretizing the advection and the flow as operators on scalar functions. The latter allows us to efficiently generalize LDDMM to curved surfaces, without explicitly computing the flow lines of the vector field we are optimizing for. We show two approaches for the solution: using linear advection with multiple vector fields, and using non‐linear advection with a single vector field. We additionally derive an approximated gradient of the corresponding energy, which is based on a novel vector field transport operator. Finally, we demonstrate applications of our machinery to intrinsic symmetry analysis, function interpolation and map improvement. 相似文献
4.
Justin Solomon Mirela Ben‐Chen Adrian Butscher Leonidas Guibas 《Computer Graphics Forum》2011,30(2):365-374
The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost‐isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently‐developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state‐of‐the‐art methods using the Princeton Segmentation Benchmark. 相似文献
5.
On the performance of distributed space-time coding systems with one and two non-regenerative relays
Spatial diversity can be induced by using wireless relay stations, which cooperate by amplifying and retransmitting the information received from a source to a destination station. In this context we propose a distributed space-time coding (DSTC) system based on the Alamouti codes. We characterize the symbol error rate of systems with one and two non-regenerative relays using bounds and high signal-to-noise ratio (SNR) approximations. The asymptotic (high SNR) symbol error probability formulas are used to optimize the power allocation in the DSTC system. Furthermore, using the asymptotic symbol error probability formulas we argue that the DSTC system has at least 1.5 times the diversity achieved by point-to-point transmissions with the same bandwidth. Simulations show not only that the DSTC outperforms the amplify-and-forward cooperative system with orthogonal transmissions, but also convolutional encoded one-hop transmissions with the same information rate as the DSTC system. Assuming full channel knowledge at the source and the relays, we find an optimum cooperative system by minimizing the bit error rate of the DSTC system with one and two non-regenerative relays subject to fixed transmit energy constraints at each radio. Numerical results show that the DSTC system with two relays performs very close to the optimum cooperative system. 相似文献
6.
The esterification of cellulose hydroxyl groups with natural carboxylic acids in mild conditions represents an adequate pathway in obtaining cellulose derivatives with different useful properties. In this article, authors report the synthesis of new mixed ester of cellulose and cellulose acetate nicotinate (CAN) , in a homogenous medium using DMF as solvent, cellulose acetate (CA) as starting cellulosic material, and nicotinic acid as an esterification agent in the presence of p-toluenesulfonyl chloride and pyridine. FTIR and NMR techniques were used to prove the binding of nicotinoyl group at free hydroxyl groups of CA. The obtained CAN was electrospun by electrospinning technique to obtain adsorbent ultrafine fibers, evidenced by SEM images, with high specific surface area. Monolayer Langmuir and empirical Leundrich isotherms were used to assess the adsorption capacity for rhodamine B dye of electrospun CAN in comparison with that of electrospun CA used as starting material. Langmuir isotherm led to a better assessment of experimental data suggesting that the adsorption is mainly determined by hydrogen bonds formed between carboxylic OH hydrogen bonding donor and pyridine N hydrogen bonding acceptor. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47772. 相似文献
7.
8.
The kinetics of a batch solid–liquid extraction of total phenolic compounds (PC) from milled grape seed (Vitis vinifera L. cv. “Frankovka”) using 50% ethanol at different extraction temperatures (25–80 °C) was studied. The maximum yield of PC was 0.13 kgGAE/kgdb after 200 min of extraction in agitated vessel at 80 °C. A new model based on the assumptions of a first order kinetics mechanism for the solid–liquid extraction and a linear equilibrium at the solid–liquid interface was developed. The model involves the concept of broken and intact cells in order to describe two successive extraction periods: a very fast surface washing process followed by slow diffusion of phenolic compounds from grape seeds to the solvent.The proposed model is suited to fit experimental data and to simulate the extraction of phenolic compounds, which was confirmed by the correlation coefficient (r ? 0.965), the root mean square error (RMSE ? 0.003 kgGAE/kgdb) and the mean relative deviation modulus (E ? 2.149%). The temperature influenced both equilibrium partition coefficients of phenolic compounds and transport properties, which is manifested by a relatively high value of activation energy (23–24) kJ/mol and by values of effective diffusivity in seed particles. 相似文献
9.
Metallopolymers based on a polyazomethine ligand containing rigid oxadiazole and flexible tetramethyldisiloxane units 下载免费PDF全文
Mirela‐Fernanda Zaltariov Maria Cazacu Carmen Racles Valentina Musteata Angelica Vlad Anton Airinei 《应用聚合物科学杂志》2015,132(11)
Soluble, easily processable polymer–metal complexes with improved optical and dielectric properties for optoelectronic functional materials were obtained. For this, a new polyazomethine (PAZ2) was prepared by the reaction of a siloxane dialdehyde and bis(formyl‐p‐phenoxymethyl) tetramethyldisiloxane with 2,5‐bis(p‐aminophenyl)‐1,3,4‐oxadiazole, and it was used as a ligand for Cu(II), Co(II), and Zn(II) ions on the basis of the presence of the electron‐donor nitrogen atoms from the azomethine group and oxadiazole ring. The structure of the PAZ2 was determined by spectral [Fourier transform infrared (FTIR) and 1H‐NMR spectroscopy] techniques. The metal complexation was proven by FTIR spectroscopy, and the silicon‐to‐metal ratios in the complexes were established by energy‐dispersive X‐ray fluorescence. The new materials were characterized by gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. The optical properties of PAZ2 and the derived metal complexes were studied by ultraviolet–visible and fluorescence spectroscopies. PAZ2 shows fluorescence emission, and it was significantly enhanced by metal complexation. The emission was enhanced by protonation; this behavior is useful, especially for sensors. The electrical properties were investigated by dielectric spectroscopy at various frequencies and temperatures, and this emphasized the existence of dipolar relaxations. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41631. 相似文献
10.
Ángeles Guinda Mirela Rada Mohamed Benaissa Ibtissam Ourrach José Antonio Cayuela 《Journal of the American Oil Chemists' Society》2015,92(8):1143-1151
The suitability of using visible/near infrared spectroscopy (Vis/NIR), as a rapid and non‐destructive technique for monitoring the quality of argan seeds (Argania spinosa Skeels) was studied. The analyzed parameters were the fatty acid composition of argan seed oil, seed moisture content, seed oil content and oil stability index (OSI). The ratio between major unsaturated and saturated fatty acids (U/S) during the oxidation assay at constant temperature was studied. Values from infrared drying were used as a laboratory reference for the moisture. Argan seed oil content was determined by Soxhlet extraction. A fatty acid analysis was carried out by gas chromatography and the OSI was determined by the Rancimat test. Predictive models of argan seed moisture, ratio U/S and OSI showed good accuracy. Therefore, Vis/NIR measurements can be used for controlling several argan seed quality parameters. This procedure might be of interest to the argan oil industry, which is currently in the process of modernization and expansion. 相似文献