A meshfree-based local Galerkin method with condensation of degree of freedom for elastic dynamic analysis

Condensation technique of degree of freedom is first proposed to improve the computational efficiency of meshfree method with Galerkin weak form for elastic dy- namic analysis. In the present method, scattered nodes with- out connectivity are divided into several subsets by cells with arbitrary shape. Local discrete equation is established over each cell by using moving Kriging interpolation, in which the nodes that located in the cell are used for approxima- tion. Then local discrete equations can be simplified by con- densation of degree of freedom, which transfers equations of inner nodes to equations of boundary nodes based on cells. The global dynamic system equations are obtained by as- sembling all local discrete equations and are solved by using the standard implicit Newmark＇s time integration scheme. In the scheme of present method, the calculation of each cell is carried out by meshfree method, and local search is imple- mented in interpolation. Numerical examples show that the present method has high computational efficiency and good accuracy in solving elastic dynamic problems.

Value of CA19-9, CA125 and CEA combined magnetic resonance imaging in the diagnosis of pancreatic cancer

Objective:To study the value of CA19-9, CA125 and CEA combined magnetic resonance imaging (MRI) in the diagnosis of pancreatic cancer, and to provide a reference for clinical diagnosis and treatment.Methods:A total of 110 cases of pancreatic cancer admitted to our hospital from November 2015 to November 2017 were selected as the observation group, and another 80 normal pancreas organizers who participated in the physical examination in the same period were selected as the control group. The change of magnetic resonance scanning parameters and serum CA19-9, CA125 and CEA detection were compared between the two groups of subjects at the same time, contrast scan and serum magnetic resonance detection of CA19-9, CA125 and CEA positive rate, and to evaluate the four alone and in combination with the diagnosis of pancreatic cancer specificity, sensitivity, negative predictive value and positive predictive value.Results:The T1WI of the observation group was low or slightly low signal, T2WI was slightly high signal, and the tumor of fat suppression sequence was low signal, which was in line with the typical characteristics of pancreatic cancer. The serum levels of CA19-9, CA125 and CEA in the observation group were significantly higher than those in the control group, and the difference was statistically significant. Compared with the two groups, the positive rates of MRI and serum CA19-9, CA125 and CEA in the observation group were higher than those in the control group, and the difference was statistically significant. The sensitivity and accuracy of MRI scan combined with three serological markers were higher than those of single detection. The specificity was between four.Conclusion: CA19-9, CA125 and CEA combined magnetic resonance imaging (MRI) have good sensitivity and accuracy in diagnosis of pancreatic cancer, but their specificity is common, which should be used for reference.

Inhibition of Notch 1 signaling in the subacute stage after stroke promotes striatal astrocyte-derived neurogenesis

Inhibition of Notch1 signaling has been shown to promote astrocyte-derived neurogenesis after stroke.To investigate the regulatory role of Notch1 signaling in this process,in this study,we used a rat model of stroke based on middle cerebral artery occlusion and assessed the behavior of reactive astrocytes post-stroke.We used theγ-secretase inhibitor N-[N-(3,5-diuorophenacetyl)-1-alanyl]-S-phenylglycine t-butylester(DAPT)to block Notch1 signaling at 1,4,and 7 days after injury.Our results showed that only administration of DAPT at 4 days after stroke promoted astrocyte-derived neurogenesis,as manifested by recovery of white matter fiber bundle integrity on magnetic resonance imaging,which is consistent with recovery of neurologic function.These findings suggest that inhibition of Notch1 signaling at the subacute stage post-stroke mediates neural repair by promoting astrocyte-derived neurogenesis.

Low noise,continuous-wave single-frequency 1.5-μm laser generated by a singly resonant optical parametric oscillator

We report a low noise continuous-wave （CW） single-frequency 1.5-μm laser source obtained by a singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO was pumped by a CW single-frequency Nd：YVO4 laser at 1.06μm. The 1.02 W of CW single-frequency signal laser at 1.5 μm was obtained at pump power of 6 W. At the output power of around 0.75 W, the power stability was better than ±l.5% and no mode-hopping was observed in 30 min and frequency stability was better than 8.5 MHz in 1 min. The signal wavelength could be tuned from 1.57 to 1.59 μm by varying the PPLN temperature. The 1.5-μm laser exhibits low noise characteristics, the intensity noise of the laser reaches the shot noise limit （SNL） at an analysis frequency of 4 MHz and the phase noise is less than 1 dB above the SNL at analysis frequencies above 10 MHz.

κ-卡拉胶比例对明胶凝胶体系凝胶特性、水分分布及微观结构的影响

论文采用质地剖面(texture profile analysis,TPA)/穿刺分析、低场核磁场共振(low-field nuclear magnetic resonance,LF-NMR)、计算机断层扫描技术(computed tomography,CT)和流变仪研究了κ-卡拉胶的比例对明胶凝胶的凝胶强度、质构特性、水分分布、动态黏弹性和微观结构的影响,并分析了几者之间的相关性。结果表明:随κ-卡拉胶比例的增加,混合凝胶体系的凝胶强度、硬度、咀嚼性、胶凝温度及熔化温度相对增大,弹性及内聚性降低,黏性和回复性先下降后上升;凝胶网络结构趋向于致密、均匀;结合水比例(S_(21))下降,不易流动水比例(S_(22))相对增加,且当体系中κ-卡拉胶的比例逐渐增加至50%时,单组份弛豫时间(T_(2W))及不易流动水的弛豫时间(T_(22))的减小较为明显,而结合水的弛豫时间(T21)变化相对较小;相关性分析表明,凝胶强度、硬度、咀嚼性与S_(21)负相关,与S_(22)、T21正相关。弹性与S_(21)、T_(22)和T_(2W)正相关,与S_(22)负相关。内聚性与T_(22)和T_(2W)正相关。研究可为明胶-κ-卡拉胶复配胶在食品中的应用提供理论支持。

7.0T nuclear magnetic resonance evaluation of the amyloid beta(1–40) animal model of Alzheimer's disease: comparison of cytology verification

3.0T magnetic resonance spectroscopic imaging brain function in Alzheimer＇s disease. However, is a commonly used method in the research ot the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer＇s disease remains unclear. In this study, 7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer＇s disease rats, the N-acetylaspartate wave crest was reduced, and the creatine and choline wave crest was elevated. This finding was further supported by hematoxylin-eosin staining, which showed a loss of hippocampal neurons and more glial cells. Moreover, electron microscopy showed neuronal shrinkage and mitochondrial rupture, and scanning electron microscopy revealed small size hippocampal synaptic vesicles, incomplete synaptic structure, and reduced number. Overall, the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer＇s disease rats in vivo, allowing the possibility for assessing the success rate and grading of the amyloid beta （1-40） animal model of Alzheimer＇s disease.

Nonlinear study of the dynamic behavior of a string-beam coupled system under combined excitations

In this paper,the nonlinear dynamic behavior of a string-beam coupled system subjected to external,parametric and tuned excitations is presented.The governing equations of motion are obtained for the nonlinear transverse vibrations of the string-beam coupled system which are described by a set of ordinary differential equations with two degrees of freedom.The case of 1：1 internal resonance between the modes of the beam and string,and the primary and combined resonance for the beam is considered.The method of multiple scales is utilized to analyze the nonlinear responses of the string-beam coupled system and obtain approximate solutions up to and including the second-order approximations.All resonance cases are extracted and investigated.Stability of the system is studied using frequency response equations and the phase-plane method.Numerical solutions are carried out and the results are presented graphically and discussed.The effects of the different parameters on both response and stability of the system are investigated.The reported results are compared to the available published work.

Coupled extension and thickness-twist vibrations of lateral field excited AT-cut quartz plates

In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation （LFE） with variations along the x1- direction. Mindlin＇s two-dimensional equations are used for anisotropic crystal plates. Both free and electrically forced vibrations are considered. Important vibration characteristics are obtained, including dispersion relations, frequency spectra, and motional capacitances. It is shown that, to avoid the effects of the couplings between extension and thickness-twist vibrations, a series of discrete values of the length/thickness ratio of the crystal plate need to be excluded. The results are of fundamental significance for the design of LFE resonators and sensors.

Periodic Orbits in Rotating Second Degree and Order Gravity Fields

Periodic orbits in an arbitrary 2nd degree and order uniformly rotating gravity field are studied. We investigate the four equilibrium points in this gravity field. We see that close relation exists between the stability of these equilibria and the existence and stability of their nearby periodic orbits. We check the periodic orbits with non-zero periods. In our searching procedure for these periodic orbits, we remove the two unity eigenvalues from the state transition matrix to find a robust, non-singular linear map to solve for the periodic orbits. The algorithm converges well, especially for stable periodic orbits. Using the searching procedure, which is relatively automatic, we find five basic families of periodic orbits in the rotating second degree and order gravity field for planar motion, and discuss their existence and stability at different central body rotation rates.

Ciliated hepatic foregut cyst with high intra-cystic carbohydrate antigen 19-9 level

A ciliated hepatic foregut cyst (CHFC) is a rare foregut developmental malformation usually diagnosed in adulthood. Five percent of reported cases of CHFC transform into squamous cell carcinoma. We report the presentation, evaluation, and surgical management of a symptomatic 45-year-old male found to have a 6.2 cm CHFC. Contrast tomography-guided fine-needle aspiration demonstrated columnar, ciliated epithelium consistent with the histologic diagnosis of CHFC. The intracystic levels of carbohydrate antigen (CA) 19-9 and carcinoembryonic antigen (CEA) were extremely high (978118 U/mL and 973 μg/L, respectively). Histologically, the wall of the cyst showed characteristic pseudopapillae lined with a ciliated stratified columnar epithelium, underlying smooth muscle, an outer fibrous layer and no atypia. Immunohistochemistry for CA19-9 and CEA was positive. This is the first case report of a CHFC in which levels of CA 19-9 and CEA were measured. Our findings suggest that a large sized multilocular cyst and elevated cyst CA19-9 and CEA levels do not exclude a CHFC from consideration in the diagnosis. CHFCs should be included in the differential diagnosis of hepatic lesions. Accurate diagnosis of a CHFC is necessary given its potential for malignant transformation, and surgical excision is recommended.

Nonlinear dynamic response of beam and its application in nanomechanical resonator

Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application. Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed. The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach. The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity, its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects. However, for the nanomechanical resonator of the curvature-dominant nonlinearity, its dynamic nonlinearity is only dependent on axial loading. Compared with the tension-dominant nonlinearity, the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity

2-channel all optical demultiplexer based on photonic crystal ring resonator

In this paper, we proposed a 2-channel demultiplexer based on photonic crystal ring resonator （PCRR）. For performing wavelength selection, we used two ring resonators, two different wavelengths were obtained by using two resonant rings with different values for the radius of dielectric rods. All the simulations and calculations have been done using Rsoft Photonic CAD software, which employs finite difference time domain （FDTD） method. The output channels were respectively at 1590.8 and 1593.8nm, correspondingly had the quality factors of 7954 and 3984, the crosstalk values of -22 and -11 dB separately. The total footprint of our proposed structure is 681.36 μm2. Results suggest that 2-channels in the proposed structure are characterized with high transmission efficiency and low band width, resulting in a very sharp output spectrum and high quality factor values.

“附加共鸣”技术的理论与实践

“附加共鸣”技术是20世纪法国作曲家奥利维埃·梅西安的一种音乐语言技巧,它是一种基于音乐音响的作曲技术,是一种“人为地增加音响共鸣”的技术,它的运用极大地丰富了音乐作品的音响色彩。文章以“附加共鸣”技术作为研究对象,试图梳理和总结其基本理论,对影响该技术的音乐要素进行详细展开。

Multifunctional dextran micelles as drug delivery carriers and magnetic resonance imaging probes

Multifunctional nanoparticles combining diagnostic and therapeutic agents into a single platform make cancer theranostics possible and have attracted wide interests in the field. In this study, a multifunctional nanocomposite based on dextran and superparamagnetic iron oxide nanoparticles （SPIO） was prepared for drug delivery and magnetic resonance imaging （MRI）. Amphiphilic dextran was synthesized by grafting stearyl acid onto the carbohydrate backbone, and micelle was formed by the resulted amphiphilic dextran with low critical micelle concentration at 1.8 mg L^-1. Doxorubicin （DOX） and a cluster of the manganese-doped iron oxide nanoparticles （Mn-SPIO） nanocrystals were then coencapsulated successfully inside the core of dextran micelles, resulting in nanocomposites with diameter at about 100 nm. Cell culture experiments demonstrated the potential of these Mn-SPIO/DOX nanocomposites as an effective multifunctional nanoplat- lk）rm for the delivery of anticancer drug DOX with a loading content （DLC） of 16 %. Confocal laser scanning microscopy reveals that the Mn-SPIO/DOX had excellent internalization ability against MCF-7/Adr cells after 2-h labeling compared with flee DOX.HCI. Under a 3.0-T MRI scanner, Mn-SPIO/ DOX nanocomposite-labeled cells in gelatin phantom show much darker images than the control. Their transverse relaxation （T2） rate is also significantly higher than that of the control cells （33.9 versus 2.3 s^-1）. Our result offers an effective strategy to treat MCF-7/Adr at optimized low dosages with imaging capability.

Growth of ZnSe∶Mn Nanocrystals from Vapour Phase

ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction (ED) studies. The size of the crystals was observed using transmission electron microscope (TEM). The oxidation state of Mn in ZnSe nanocrystal was found using electron spin resonance (ESR) spectrum. The room temperature luminescence measurements show the peaks corresponding to both bandgap of the material and Mn in ZnSe.

A Characterization for a Sequence to be Potentially K_(r+1) — e-graphic

Let n 〉 r, let lr --- （dl,d2,-,dn） be a non-increasing sequence of nonnegative integers and let Kr＋l - e be the graph obtained from Kr＋l by deleting one edge. If zr has a realization G containing Kr＋l - e as a subgraph, then r is said to be potentially Kr＋l - e-graphic. In this paper, we give a characterization for a sequence π to be potentially Kr＋l - e-graphic.

Decision making for pancreatic resection in patients with intraductal papillary mucinous neoplasms

AIM: To identify a practical approach for preoperative decision-making in patients with intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. METHODS: Between March 1999 and November 2006, the clinical characteristics, pathological data and computed tomography/magnetic resonance imaging (CT/MRI) of 54 IPMNs cases were retrieved and analyzed. The relationships between the above data and decision-making for pancreatic resection were analyzed using SPSS 13.0 software. Univariate analysis of risk factors for malignant or invasive IPMNs was performed with regard to the following variables: carcinoembryonic antigen, carbohydrate antigen 19-9 (CA19-9) and the characteristics from CT/MRI images. Receiver operating characteristic (ROC) curve analysis for pancreatic resection was performed using significant factors from the univariate analysis. RESULTS: CT/MRI images, including main and mixed duct IPMNs, tumor size > 30 mm or a solid component appearance in the lesion, and preoperative serum CA19-9 > 37 U/mL had good predictive value for determining pancreatic resection (P < 0.05), but with limitations. Combining the above factors (CT/MRI images and CA19-9) improved the accuracy and sensitivity for determining pancreatic resection in IPMNs. Using ROC analysis, the area under the curve reached 0.893 (P<0.01, 95%CI: 0.763-1.023), with a sensitivity, specificity, positive predictive value and negative predictive value of 95.2%, 83.3%, 95.2% and 83.3%, respectively. CONCLUSION: Combining preoperative CT/MRI images and CA19-9 level may provide useful information for surgical decision-making in IPMNs.

Developments in auxiliary examination of Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD), which is caused by prion scrapie protein, is a rare, chronic, transmissible and fatal disease. Clinical manifestations of CJD include rapidly progressive dementia, cerebellar ataxia, visual disturbance, as well as pyramidal and extrapyramidal tract signs. Four subtypes of CJD have been reported, including sporadic, familial or genetic, iatrogenic and variant. Given the infectiousness and high mortality of the disease, it is imperative that earlier and more accurate diagnostic methods are developed. In the past years, 14-3-3 protein testing and periodic sharp wave complexes in electroencephalogram have been widely used in CJD clinical diagnosis;and the abnormal hyper-intensity in diffusion weighted imaging has also been used. Recently, there has been a focus on the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography. New findings of potential biomarkers in cerebrospinal fluid and decreases in diffusion tensor imaging measures have emerged as having an association with CJD. Magnetic resonance spectroscopy has also drawn attention as an emerging method for diagnosis. In this review, the progress in auxiliary examinations of CJD is discussed and the potential, future diagnostic methods are introduced.

Degree dependence entropy descriptor for complex networks

In order to supply better accordance for mod eling and simulation of complex networks, a new degree dependence entropy （DDE） descriptor is proposed to describe the degree dependence relationship and corre sponding characteristic in this paper. First of all, degrees of vertices and the shortest path lengths between all pairs of ,ertices are computed. Then the degree dependence matrices under different shortest path lengths are con structed. At last the DDEs are extracted from the degree dependence matrices. Simulation results show that the DDE descriptor can reflect the complexity of degree dependence relationship in complex networks; high DDE indicates complex degree dependence relationship; low DDE indicates the opposite one. The DDE can be seen as a quantitative statistical characteristic, which is meaningful for networked modeling and simulation.

Fast computation of observed cross section for ψ′ → PP decays

It has been conjectured that the relative phase between strong and electromagnetic amplitudes is universally -90° in charmonium decays. ψ′ decaying into a pseudoscalar pair provides a possibility to test this conjecture. However, the experimentally observed cross section for such a process is depicted by the two-fold integral, which takes into account the initial state radiative （ISR） correction and energy spread effect. Using the generalized linear regression approach, a complex energy-dependent factor is approximated by a linear function of energy. Taking advantage of this simplification, the integration of ISR correction can be performed and an analytical expression with accuracy at the level of 1% is obtained. Then, the original two-fold integral is simplified into a one-fold integral, which reduces the total computing time by two orders of magnitude. Such a simplified expression for the observed cross section usually plays an indispensable role in the optimization of scan data taking, the determination of systematic uncertainty, and the analysis of data correlation.