Can diffusion-weighted imaging be used as a reliable sequence in the detection of malignant pulmonary nodules and masses?

Recent developments in diffusion-weighted magnetic resonance imaging (DWI) make it possible to image malignant tumors to provide tissue contrast based on difference with the diffusion of water molecules among tissues, which can be measured by the apparent diffusion coefficient (ADC) value. We aimed to assess the diagnostic accuracy of DWI for benign/malignant discrimination of pulmonary nodules/masses with a meta-analysis. The MEDLINE, EMBASE, Cancerlit and Cochrane Library database, from January 2001 to August 2011, were searched for studies evaluating the diagnostic accuracy of DWI for benign/malignant discrimination of pulmonary nodules. We determined sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LRP and LRN), and constructed summary receiver operating characteristic SROC) curves. Across 10 studies (545 patients), there was no evidence of publication bias (P= .22, bias=−19.19). DWI had a pooled sensitivity of 0.84 (95% CI, 0.76–0.90) and a pooled specificity of 0.84 (95% CI, 0.64–0.94). Overall, LRP was 5.3 (95% CI, 2.1–13.0) and LRN was 0.19 (95% CI, 0.12–0.30). In patients with high pretest probabilities, DWI enabled confirmation of malignant pulmonary lesion; in patients with low pretest probabilities, DWI enabled exclusion of malignant pulmonary lesion. Worst-case-scenario (pretest probability, 50%) posttest probabilities were 84% and 16% for positive and negative DWI results, respectively. Diffusion-weighted magnetic resonance imaging can be used to differentiate malignant from benign pulmonary lesions. High-quality prospective studies regarding DWI in the evaluation of pulmonary nodules are still needed to be conducted.     

Variational iteration method — a promising technique for constructing equivalent integral equations of fractional order

The variational iteration method is newly used to construct various integral equations of fractional order. Some iterative schemes are proposed which fully use the method and the predictor-corrector approach. The fractional Bagley-Torvik equation is then illustrated as an example of multi-order and the results show the efficiency of the variational iteration method’s new role.     

High-resolution X-ray imaging—a powerful nondestructive technique for applications in semiconductor industry

The availability of high-brilliance X-ray sources, high-precision X-ray focusing optics and very efficient CCD area detectors has contributed essentially to the development of transmission X-ray microscopy (TXM) and X-ray computed tomography (XCT) with sub-50 nm resolution. Particularly, the fabrication of high aspect ratio Fresnel zone plates with zone widths approaching 15 nm has contributed to the enormous improvement in spatial resolution during the previous years. Currently, Fresnel zone plates give the ability to reach spatial resolutions of 15 to 20 nm in the soft and of about 30 to 50 nm in the hard X-ray energy range. X-ray microscopes with rotating anode X-ray sources that can be installed in an analytical lab next to a semiconductor fab have been developed recently. These unique TXM/XCT systems provide an important new capability of nondestructive 3D imaging of internal circuit structures without destructive sample preparation such as cross sectioning. These lab systems can be used for failure localization in micro- and nanoelectronic structures and devices, e.g., to visualize voids and residuals in on-chip metal interconnects without physical modification of the chip. Synchrotron radiation experiments have been used to study new processes and materials that have to be introduced into the semiconductor industry. The potential of TXM using synchrotron radiation in the soft X-ray energy range is shown for the nondestructive in situ imaging of void evolution in embedded on-chip copper interconnect structures during electromigration and for the imaging of different types of insulating thin films between the on-chip interconnects (spectromicroscopy).     

Dual double arterial phase dynamic MR imaging with sensitivity encoding (SENSE): which is better for diagnosing hypervascular hepatocellular carcinomas, in-phase or opposed-phase imaging?

The purpose of this study was to investigate the efficacy of sensitivity encoding (SENSE) dynamic magnetic resonance imaging (MRI) with the dual (in-phase and opposed-phase) double arterial phase to detect hypervascular hepatocellular carcinomas (HCCs). MR images of the liver from 44 consecutive patients were obtained. Dynamic MRI with SENSE was performed six times (precontrast, early arterial, late arterial, 1 min, 3 min and 5 min after contrast injection) at 11 s per scan using the gradient recalled echo sequence (TR/TE/flip angle = 168/2.3 and 4.6/70). In-phase and opposed-phase images were obtained simultaneously each scan. For the quantitative analysis, the signal-to-noise ratio (S/N) of HCC and tumor-to-liver contrast-to-noise ratio (C/N) were analyzed for 55 HCCs. The mean S/N of HCCs on in-phase images showed significantly higher values than that on opposed-phase images regarding all phases (P < 0.001). In arterial phases, the mean tumor-to-liver C/N for in-phase images was significantly higher than that for opposed-phase images (P < 0.05). In portal and delayed-phase images, the mean tumor-to-liver C/N in opposed-phase images showed a negative value. In six HCCs with fatty metamorphosis, the mean tumor-to-liver C/N on arterial phase images approached zero in opposed-phase, while it showed a positive value in-phase. In dual double arterial phase dynamic MRI of the liver, in-phase images were superior to opposed-phase images for detecting early enhancement of hypervascular HCCs, while the latter were superior for detecting washout of contrast media from HCCs in the portal and delayed phase. The combination of both images overcomes the difficulty of diagnosing hypervascular HCCs with fatty metamorphosis.     

Theory of Z-scan technique using Gaussian-Bessel beams with a phase object

This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel (GB) beams beside a phase object (PO) to measure the third-order nonlinear susceptibility components.By using this method,the sign of refractive index which depends on the shape of the close aperture Z-scan curve can be easily determined.Meanwhile,the magnitude of nonlinear coefficients can also be deduced by theoretical fit.The proposed method is advantageous for high sensitivity and imposes a lower stress in the cases of fragile materials,since small pulse energy is enough for the measurement of nonlinear coefficients.Predictions of the models are compared with Gaussian Z-scan measurement and GB Z-scan measurement.By using GB beams with a PO,the sensitivity of Z-scan measurements is found to be a factor of over 60 times greater than for Gaussian beams and 2 times greater than for Gaussian-Bessel beams.     

Evaluation of the brain pH using a phosphorus magnetic resonance spectroscopy technique – a comparison of women and men

The aim of this study was to determine the reference value of pH in healthy women and men using the phosphorus magnetic resonance spectroscopy technique. The brains of 65 young volunteers were examined. The intracellular pH was calculated in the group of women and the group of men. In both groups, the average pH was slightly alkaline (respectively 7.10?±?0.08 and 7.08?±?0.12). No statistically significant sex difference in brain pH was found. Thus, in case if this method is used to estimate possible brain pathology in the young population, it is not needed to take the gender factor into consideration.     

The technique of detecting the laser—ultrasonic vector displacement with a confocal Fabry—Perot interferometer waves in a plate

Generally,a confocal Fabry-Perot interferometer is only able to detect the out-of-plane component of a displhacement field;while the in-plane component often has the information about the material which cannot be found in this out-of-plane component.In this paper,based on a confocal Fabry-Perot interferometer set-up for detecting the out-of-plane component of a laser generated acoustic field.,a technique is developed to detect both the out-of-plane and inplane displacement components simultaneously with a novel two-channel confocal Fabry-perot interferometer.     

Vibration control of multi—degrees—of—freedom system with dynamic absorbers based on power flow

In accordance with a multiple degrees of freedom vibration system with dynamic vibration absorbers (DVAs), an equivalent admittance matrix and the power flows input major structure and minor structure are deduced on the basis of the theories of structure mobility.Furthermore, regarding the net power flow of main vibration system as the controlled object,probed into are the single and multiple model controls of multi-degrees-of-freedom system with one or several absorbers attached. And the control mechanism and effect of dynamic vibration absorbers are revealed.     

Development of a technique for high pressure neutron diffraction at 40 GPa with a Paris-Edinburgh press

ABSTRACT

We have developed a technique for neutron diffraction experiments at pressures up to 40?GPa using a Paris-Edinburgh press at the PLANET beamline in J-PARC. To increase the maximum accessible pressure, the diameter of the dimple for sample chamber at the top of the sintered diamond anvils is sequentially reduced from 4.0?mm to 1.0?mm. As a result, the maximum pressure increased and finally reached 40?GPa. By combining this technique with the beam optics which defines the gauge volume, diffraction patterns sufficient for full-structure refinements are obtainable at such pressures.     

Trajectory engineering via a space-fractional Schr?dinger equation with dynamic linear index potential

We theoretically and numerically study the propagation dynamics of a Gaussian beam modeled by the fractional Schr?dinger equation with different dynamic linear potentials. For the limited case α = 1(α is the Lévy index) in the momentum space, the beam suffers a frequency shift which depends on the applied longitudinal modulation and the involved chirp. While in the real space, by precisely controlling the linear chirp, the beam will exhibit two different evolution characteristics: one is the zigzag trajectory propagation induced by multi-reflection occurring at the zeros of spatial spectrum,the other is diffraction-free propagation. Numerical simulations are in full accordance with the theoretical results. Increase of the Lévy index not only results in the drift of those turning points along the transverse direction, but also leads to the delocalization of the Gaussian beam.     

Single-shot imaging of OH radicals and simultaneous OH radical/acetone imaging with a tunable Nd : YAG laser

Single shot imaging capability for OH radical distributions in various atmospheric pressure methane flames upon excitation with a tunable frequency-quadrupled Nd:YAG laser is demonstrated. The laser wavelength can be tuned with an intra-cavity etalon to produce laser-induced fluorescence (LIF) signals from OH via absorption in the OH A–X (2,0) P ₁(10) line. Simultaneous single-shot imaging of the burnt and unburnt zones in laminar nonpremixed, premixed and turbulent flames is presented. The unburnt areas are visualized with LIF of acetone that is seeded to the methane fuel. Acetone levels are set to match signal intensities to that of the OH signals to allow imaging on a single intensified CCD camera. PACS 42.62.Fi; 33.50.Dq; 82.33.Vx     

High-purity Zirconium under Niobium ion implantation: possibility of a dynamic precipitation?

High-purity (6N purity) Zirconium was subjected to different Niobium ion (Nb⁺) fluences in a particle accelerator. Grazing incidence X-ray diffraction confirmed subsurface phase transformation. While an approximate scaling was noted between Nb⁺ fluence and quantum of phase transformation, the sample subjected to the highest ion irradiation also showed significant subsurface shear residual stresses (τ₁₃). Molecular dynamics simulations, considering momentum transfer, revealed a drop in τ₁₃ beyond a critical displacements per atom or Nb⁺ fluence. High-resolution cross-sectional transmission electron microscopy (HRXTEM) confirmed formation of bcc (body-centred cubic) β phase and also linked τ₁₃ with such transformation. HRXTEM revealed, at about 100 nm depth, presence of 10–15% β with 2–15 nm size. The β particles and the surrounding α also had significant microscopic shear strains. The dynamic nature of the Nb implantation is expected to create fluctuations in temperature, Nb concentration and relative lattice damage. Such fluctuation, on the other hand, is/was hypothesized to dynamically alter the critical nuclei size: a clear possibility of ‘dynamic precipitation’.     

Dynamic GD-enhanced MR imaging of hepatic hemangioma: Is high temporal resolution requisite for characterization?

We assessed the value of high temporal resolution in the dynamic characterization of hepatic hemangioma with use of magnetization-prepared gradient-echo (MP-GRE) imaging. Single-level inversion recovery incremental flip angle MP-GRE images were obtained in 26 patients with 34 hemangiomas before and at a repetition rate of 30 images/min after injection of Gd-DTPA without breath-holding. Enhancement patterns and temporal changes thereof were analyzed. Hemangiomas were categorized as small (<2.0 cm), medium (2.0–5.0 cm), and large (> 5 cm) lesions. Classic early peripheral nodular enhancement (PNE) with progressive hyperintense fill-in was observed in 31 lesions (91%). Two of 10 small and 1 of 20 medium lesions showed complete fill-in within 10 s, and three small and one medium lesions within 45 s after the onset of PNE. In no cases of hemangioma was immediate homogeneous hyperintensity observed without preceding PNE. In conclusion, temporal resolution of less than 10 s is a prerequisite for confident dynamic characterization of some hemangiomas, predominantly small hemangiomas.     

Cylindrically Symmetric Inhomogeneous Universes with?a?Cloud of Strings

Cylindrically symmetric inhomogeneous string cosmological models are investigated in presence of string fluid as a source of matter. To get the three types of exact solutions of Einstein’s field equations we assume A=f(x)k(t), B=g(x)ℓ(t) and C=h(x)ℓ(t). Some physical and geometric aspects of the models are discussed.     

Direct observation of λ-DNA molecule reversal movement within microfluidic channels under electric field with single molecule imaging technique

The electrodynamic characteristics of single DNA molecules moving within micro-/nano-fluidic channels are important in the design of biomedical chips and bimolecular sensors. In this study, the dynamic properties of λ-DNA molecules transferring along the microchannels driven by the external electrickinetic force were systemically investigated with the single molecule fluorescence imaging technique. The experimental results indicated that the velocity of DNA molecules was strictly dependent on the value of the applied electric field and the diameter of the channel. The larger the external electric field, the larger the velocity, and the more significant deformation of DNA molecules. More meaningfully, it was found that the moving directions of DNA molecules had two completely different directions:(i) along the direction of the external electric field, when the electric field intensity was smaller than a certain threshold value;(ii) opposite to the direction of the external electric field, when the electric field intensity was greater than the threshold electric field intensity.The reversal movement of DNA molecules was mainly determined by the competition between the electrophoresis force and the influence of electro-osmosis flow. These new findings will theoretically guide the practical application of fluidic channel sensors and lab-on-chips for precisely manipulating single DNA molecules.     

Read—out of a read—only super—resolution optical disc with a Si mask

A novel read-only super-resolution optical disc structure (substrate/mask layer/dielectric layer) is proposed in this paper. By using a Si thin film as the mask layer, the recording pits with a diameter 380nm and a depth 50nm are read out on the dynamic measuring equipment; the laser wavelength α is 632.8nm and the numerical aperture is 0.40. In the course of reproduction, the laser power is 5mW and the rotation velocity of the disc is 4m·s^-1. The optimum thickness of the Si thin film is 18nm and the signal-to-noise ratio is 32dB.     

Effect of dust charge variation on dust—acoustic solitary waves in a magnetized two—ion—temperature dusty plasma

The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may exite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).     

MR elastography of hepatocellular carcinoma: Correlation of tumor stiffness with histopathology features—Preliminary findings

PurposeTo determine if tumor stiffness by MR Elastography (MRE) is associated with hepatocellular carcinoma (HCC) pathologic features.Material and methodsA retrospective review was undertaken of all patients with pathologically confirmed HCC who underwent MRE prior to loco-regional therapy, surgical resection or transplant between 1/1/2007 to 12/31/2015. An independent observer measured tumor stiffness (kilopascals, kPa) by drawing regions of interest (ROI) covering the HCC and in the case of HCCs with non-enhancing/necrotic components, only the solid portion was included in the ROI. HCC tumor grade (WHO criteria), vascular invasion and tumor encapsulation were assessed from retrievable pathology specimens by an expert hepatobiliary pathologist. Tumor stiffness was compared by tumor grade, size, presence of capsule and vascular invasion using Student's t-test (or Exact Mann-Whitney test).Results21 patients were identified who had pathologically confirmed HCCs and tumor MRE data. 17 patients (81.0%) had underlying chronic liver disease. The mean ± SD tumor size (cm) was 5.3 ± 3.9 cm. The mean ± SD tumor stiffness was 5.9 ± 1.4 kPa. Tumors were graded as well differentiated (N = 2), moderately differentiated (N = 11) and poorly differentiated (N = 8). There was a trend toward increased tumor stiffness in well/moderately differentiated HCCs (6.5 ± 1.2 kPa; N = 13) compared to poorly differentiated HCCs (4.9 ± 1.2 kPa; N = 8) (p < 0.01). There was no significant correlation between tumor stiffness and liver stiffness or tumor size. There was no significant difference in tumor stiffness by presence or etiology of chronic liver disease, vascular invasion or tumor encapsulation.ConclusionPreliminary data suggest that tumor stiffness by MRE may be able to differentiate HCC tumor grade.     

Design and Evaluation of Dynamic Replication Strategies for a High—Performance Data Grid

Physics experiments that generate large amounts of data need to be able to share it with researchers around the world .High performance grids facilitate the distribution of such data to geographically remote places.Dynamic replication can be used as a technique to reduce bandwidth consumption and access latency in accessuing these huge amounts of data.We describe a simulation framework that we have developed to model a grid scenario,which enables comparative studies of alternative dynamic replication strategies.We present preliminary results obtained with this simulator,in which we evaluate the performance of six different replication strategies for three different kinds of access patterns.The simulation results show that the best strategy has significant savings in latency and bandwidth consumption if the access patterns contain a moderate amount of gerographical locality.     

Online charge calibration of LHAASO-WCDA——a study with the engineering array

LHAASO-WCDA is a large ground-based water Cherenkov detector array planned to be built at ShangriLa, Yunnan Province, China. As a major component of the LHAASO project, the main purpose of LHAASO-WCDA is to survey the northern sky for very-high-energy（above 100 GeV） gamma ray sources and measure the spectrum. To gain full knowledge of the water Cherenkov technique and to investigate the engineering issues, a 9-cell detector array has been built at the Yang-Ba-Jing site, neighboring the ARGO-YBJ experiment. With the array, charge calibration methods for both low and high ranges of the PMT readout are studied, whose result shows that a precision at several percentages can be reached, which can satisfy the requirement of the detector array. During the long term operation, the charge calibration stability and environmental afection are studied; in this paper, the results are discussed. These calibration methods are proposed to be applied in the future LHAASO-WCDA project.