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排序方式: 共有56条查询结果,搜索用时 15 毫秒
1.
Transfer matrix models have been frequently used to analyze the structural behavior of rods, including curved and pretwisted ones. The advantages of these models include their relative simplicity, numerical efficiency and ease of implementation. Previous investigations did not include nonlinear analyses of curved rods that undergo large deformations. The present paper describes a nonlinear transfer matrix model of curved and pretwisted rods, which is capable of analyzing very large spatial deformations. The rod is divided into segments. A body system of coordinates is attached to each segment. This system translates and rotates with the segment during the deformation. If the segments are kept small enough, the local deformations of each segment, relative to its body system of coordinates, are small. The segments’ systems of coordinates rotate relative to their neighbors and if this rotation is dealt with properly, large rotations and displacement of the curved rod can be analyzed. In spite of its nonlinear nature, the model remains relatively simple and efficient. The new model is used to solve a few problems and the results show very good agreement with other analytical, finite-element, and experimental results. 相似文献
2.
M Horiguchi M Kimura J Lytton J Skurnick F Nash G Awad E Poch A Aviv 《Canadian Metallurgical Quarterly》1998,31(2):595-602
In this work, we explored the relationship between the freely exchangeable Ca2+ (FECa2+) in the dense tubules (DT) and the sarco(endo)plasmic reticulum (SER) Ca2+-ATPase (SERCA) in circulating human platelets and examined the relationship between blood pressure (BP) and these platelet parameters. Studying platelets from 32 healthy men, we showed that the maximal reaction velocity (Vmax) of the SERCA significantly correlated with FECa2+ in the DT and with the protein expressions of SERCA 2 and 3. BP positively correlated with both the Vmax of the SERCA (r=.462, P=.010) and the FECa2+ sequestered in the DT (r=.492, P=.005). The relationships between these platelet Ca2+ parameters and BP were in part confounded by increased levels of serum triglycerides and diminished HDL cholesterol with a higher BP. No correlation was observed between the resting cytosolic Ca2+ and BP. Collectively, these findings indicate that (1) an increase in the cellular Ca2+ load in platelets is expressed by a higher activity of the SERCA and an increase in the expressions of SERCA 2 and 3 proteins, coupled with an increase in the FECa2+ in the DT, and (2) a higher BP is associated with an increase in platelet Ca2+ load in human beings, expressed by a rise in the FECa2+ in the DT and the upregulation of SERCA activity. 相似文献
3.
Biosynthesis and stability of the mRNA population in DMSO-induced Friend erythroleukemic cells were studied after labeling the RNA with 3H-uridine and then chasing it with nonlabeled uridine. Globin RNA metabolism was studied by hybridization to excess complementary DNA convalently coupled to oligo(dT)-cellulose. After a labeling period of 120 min, 2-4% of the poly(A)-containing labeled RNA was in globin RNA; it decayed with a half-life of 16-17 hr. The rest of the poly(A)-containing RNA was composed to two kinetic populations: 85-90% decayed with a half-life of about 3 hr, while 10% decayed with a half-life of about 37 hr. The portion of globin RNA in labeled poly(A)-containing RNA behaved in an unexpected fashion during the chase period. During the initial chase period, the percentage of globin RNA increased rapidly, reaching a maximum of about 15% at 20 hr, but it subsequently declined gradually. Based on these findings, a model was built that describes the changes in the proportion of globin mRNA in poly(A)-containing RNA during continuous synthesis and after chase of the labeled RNA. It appears that if the parameters described remain constant during the maturation of erythroblasts, then this model would not account for the almost exclusive presence of globin RNA in the reticulocyte. By far the most effective way to achieve this high level of globin RNA is the destabilization of the mRNA population which is more stable than globin RNA, and not the stabilization of globin RNA itself. 相似文献
4.
Aviv Segev Jussi Kantola Chihoon Jung Jaehwa Lee 《Expert systems with applications》2013,40(17):7010-7023
In the process of analyzing knowledge innovation, it is necessary to identify the existing boundaries of knowledge so as to determine whether knowledge is new – outside these boundaries. For a patent to be granted, all aspects of the patent request must be studied to determine the patent innovation. Knowledge innovation for patent requests depends on analyzing current state of the art in multiple languages. Currently the process is usually limited to the languages and search terms the patent seeker knows. The paper describes a model for representing the patent request by a set of concepts related to a multilingual knowledge ontology. The search for patent knowledge is based on Fuzzy Logic Decision Support and allows a multilingual search. The model was analyzed using a twofold approach: a total of 104,296 patents from the United States Patent and Trademark Office were used to analyze the patent extraction process, and patents from the Korean, US, and Chinese patent offices were used in the analysis of the multilingual decision process. The results display high recall and precision and suggest that increasing the number of languages used only has minor effects on the model results. 相似文献
5.
G Aviv 《Coloration Technology》1989,105(11):406-408
The kinetic and thermodynamic aspects of dyeing Thunderon SSN fibres (polyacrilonitrile fibres coated with a copper sulphide layer) have been studied and compared with results obtained on uncoated fibres. A considerable difference in the kinetic behaviour was found, and the apparent diffusion coefficients as well as the rate constants differ from each other by a factor of about three. At equilibrium the fibres react almost in the same way; their absorption isotherms were found to be quite similar. 相似文献
6.
The features of supersonic molecular beams (SMB) are used to improve gas chromatography—mass spectrometry (GC–MS) performance and establish a new method of fast GC–MS. In SMB, the sample compounds are vibrationally cooled such that their electron impact mass spectra are characterized by enhanced M+ peaks, together with library-searchable fragments. A new ionization method, hyperthermal surface ionization (HSI), provides ultrasensitive ionization coupled with a tunable degree of selectivity for nitrogen-containing drugs. SMB enables the use of very high carrier gas flow rates which, when a short megabore column is used, results in ultra-fast GC–MS having conventional chromatographic peak widths. Thus, fast GC–MS in SMB can be performed with conventional quadrupole analyzers. The slightly reduced GC resolution can, in many cases, be compensated for by the selectivity of hyperthermal surface ionization or by the increased EI selectivity through enhanced M+. “Fast”, “very-fast”, and “ultra-fast” GC–MS are defined and demonstrated with drugs, and the ability to analyze underivatized steroids is shown. Practical examples are shown including ultra-fast GC–MS of lidocaine in human plasma extract achieved in a few seconds and screening of other drugs, without any sample preparation or extraction, achieved in less than three minutes. We conclude that GC–SMB–MS exhibits a combination of faster analysis with improved sensitivity and selectivity, a wider range of molecules amenable to GC–MS, improved MS information, and higher a degree of flexibility. 相似文献
7.
8.
Danielle Regev Sharon Etzion Hen Haddad Jacob Gopas Aviv Goldbart 《International journal of molecular sciences》2022,23(18)
Cardiovascular morbidity is the leading cause of death of obstructive sleep apnea (OSA) syndrome patients. Nocturnal airway obstruction is associated with intermittent hypoxia (IH). In our previous work with cell lines, incubation with sera from OSA patients induced changes in cell morphology, NF-κB activation and decreased viability. A decrease in beating rate, contraction amplitude and a reduction in intracellular calcium signaling was also observed in human cardiomyocytes differentiated from human embryonic stem cells (hESC-CMs). We expanded these observations using a new controlled IH in vitro system on beating hESC-CMs. The Oxy-Cycler system was programed to generate IH cycles. Following IH, we detected the activation of Hif-1α as an indicator of hypoxia and nuclear NF-κB p65 and p50 subunits, representing pro-inflammatory activity. We also detected the secretion of inflammatory cytokines, such as MIF, PAI-1, MCP-1 and CXCL1, and demonstrated a decrease in beating rate of hESC-CMs following IH. IH induces the co-activation of inflammatory features together with cardiomyocyte alterations which are consistent with myocardial damage in OSA. This study provides an innovative approach for in vitro studies of OSA cardiovascular morbidity and supports the search for new pharmacological agents and molecular targets to improve diagnosis and treatment of patients. 相似文献
9.
Prostate cancer requires the attention of social workers in health care for three reasons: the growing elderly population which will increase the number diagnosed, the recent introduction of new treatments and the lack of social acceptability for this condition. Interventions for prostate cancer are specific to the stage of the disease. These individual, family and group interventions are a model for social work services to elderly men with other forms of cancer. Social workers have opportunity to research quality of life and decision-making issues to enhance medical practise in prostate cancer. 相似文献
10.
ORF3 of the cytoplasmic linear plasmid pGKL2 was disrupted in vivo by integration of a selectable marker. Long-term cultivation of transformants carrying hybrid plasmids with a disrupted ORF3 under selective pressure did not deprive strains of the native counterpart, thereby proving its essentiality for pGKL2 replication and maintenance. The predicted ORF3 polypeptide was found to contain conserved motifs acquainted with mRNA-capping enzymes in the required order, just as in cytoplasmic viruses; new conserved motifs were also identified. 相似文献