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This communication demonstrates that an open-ended coaxial waveguide can be a good aperture antenna for generating conical-beam radiation. Design equations are derived to obtain the radii of inner and outer conductors of a coaxial waveguide radiating into a half free space. A design example is provided to verify the design concept and derived equations. Simulated and measured results of a fabricated aperture antenna are presented and compared to demonstrate its conical-beam radiation performance.

To take into account reasonably the safety requirements of the disabled on emergency evacuation in the design, usage, management and emergency response of public places, the authors of this paper organized on-site experiments for 100 disabled individuals (40 people with no supporting tools, 20 people using a single crutch and 40 people two crutches) and 17 healthy people at a subway station in Beijing. The experiments were designed to measure the unimpeded free walking speed of the participants during horizontal and stair ascending/descending movement, and to assess the possible impact of passage width on movement speed. Based on the results of the tests, the authors systematically analyzed the speed variation patterns with disability grade, gender and passage width. The validity of the value of an important parameter for evacuation safety design in the prescribed fire codes in mainland China, the width of a single stream of people, is assessed. Finally the results of the experiments are compared with that from other researches to identify the similarities and differences between them.

Background and Purpose— The purpose of this study was to evaluate the potential clinical value of arterial spin-labeled (ASL) perfusion MRI in acute ischemic stroke (AIS) through comparison with dynamic susceptibility contrast (DSC) enhanced perfusion MRI. Methods— Pseudocontinuous ASL with 3-dimensional background-suppressed gradient and spin echo readout was applied with DSC perfusion MRI on 26 patients with AIS. ASL cerebral blood flow and multiparametric DSC perfusion maps were rated for image quality and lesion severity/conspicuity. Mean ASL cerebral blood flow and DSC perfusion values were obtained in main vascular territories. Kendall coefficient of concordance was calculated to evaluate the reliability of ratings. Spearman correlation coefficients were calculated to compare ratings and quantitative perfusion values between ASL and DSC perfusion maps. Results— ASL cerebral blood flow and DSC perfusion maps provided largely consistent results in delineating hypoperfused brain regions in AIS. Hyperemic lesions, which also appeared frequently in the AIS cases studied, were more conspicuous on ASL cerebral blood flow than on DSC cerebral blood flow, mean transit time and time to the maximum of the tissue residual function maps. Conclusions— As a rapid, noninvasive, and quantitative technique, ASL has clinical use in detecting blood flow abnormalities in patients with AIS.

A new technique is introduced in this study for in vivo measurement of arterial cerebral blood volume by combining arterial spin labeling with a segmented multiphase balanced steady-state free precession (bSSFP) readout sequence. This technique takes advantage of the phenomenon that the longitudinal magnetization of flowing blood is not or only marginally disturbed (besides T(1) relaxation) by the bSSFP ± α pulse train. When the blood water exchanges into tissue, it becomes quickly saturated by the bSSFP pulse train due to 0 velocity and reduced T(1), T(2) relaxation times. Therefore, labeled blood water behaves like an intravascular contrast agent in multiphase bSSFP scans, and can be used to quantify arterial cerebral blood volume in a similar way as dynamic susceptibility contrast MRI. Both Bloch equation simulation and in vivo experiments were carried out to demonstrate the feasibility for quantifying cerebral blood volume in arteries, arterioles, and capillaries using two variants of the proposed method. Functional MRI of visual cortex stimulation was further performed using multiphase bSSFP-based arterial spin labeling and compared with vascular-space occupancy contrast. The proposed multiphase bSSFP-based arterial spin labeling technique may allow separation of cerebral blood volume of different vascular compartments for functional MRI studies and clinical evaluation of the cerebral vasculature.

Aging effects on blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) have been studied using task induced hemodynamic responses with controversial findings. The present study systematically investigated the normal aging effect in the visual cortex using 3 indices of low frequency fluctuations of resting state BOLD fMRI, i.e., amplitude of low frequency fluctuations (ALFF), regional homogeneity (ReHo) and functional connectivity (FC). These 3 resting state measurements were compared with task induced BOLD activation in the visual cortex of 2 groups of 10 young and 10 elderly subjects. Our results showed reduced functional connectivity and regional homogeneity of low frequency fluctuations of BOLD fMRI in aged subjects as compared to young subjects. While the mean magnitude of BOLD activation and the mean amplitude of low frequency fluctuations of BOLD fMRI did not vary between the 2 age groups, larger variances were observed in both measures in aged subjects. These data suggest that normal aging may be associated with “loss of coherence” of low frequency fluctuations of resting state BOLD fMRI in the visual cortex, and may affect task induced BOLD response through increased inter- and intra-subject variability.

Background The purpose of this study was to report the risk of pharyngoesophageal stricture after treatment for head and neck cancer. Methods Human studies on radiation therapy with or without chemotherapy for head and neck cancer published in peer-reviewed journals with assessment of pharyngoesophageal stricture with barium swallow or endoscopy were included. Results A total of 4727 patients from 26 studies treated between 1989 and 2008 were eligible for analysis. The reported overall risk of stricture was 7.2%. The risks of pharyngoesophageal stricture in both conventional and intensity-modulated radiation therapy (IMRT) studies were 5.7% and 16.7%, respectively (p < .001). Use of concurrent (p < .001) and taxane (p = .01) chemotherapy was associated with the IMRT technique. Prospective studies reported a 3.3-fold increased risk of stricture compared with that of retrospective studies (odds ratio: 3.3; 95% confidence interval: 2.3–4.8; p < .001). Conclusions Pharyngoesophageal stricture after IMRT and chemotherapy treatment for head and neck cancer is not uncommon. Videofluoroscopic swallow study should be performed prospectively to evaluate swallowing function. © 2011 Wiley Periodicals, Inc. Head Neck, 2012

Recent attempts to understand the biological bases of depression vulnerability have revealed that both the short allele of the serotonin transporter-linked polymorphic region (5-HTTLPR) and activity in the amygdala are associated with depression. Other studies have reported amygdala hyperactivity associated with the 5-HTTLPR short allele, linking the genetic and neuroimaging lines of research and suggesting a mechanism whereby the short allele confers depression risk. However, fewer investigations have examined the associations between depression, 5-HTTLPR variability, and amygdala activation in a single study. The current study thus investigated whether 5-HTTLPR genotype modulates the association between depressive symptoms and amygdala activity among psychiatrically healthy adults. Regional cerebral blood flow was measured with perfusion fMRI during a task-free scan. We hypothesized differential associations between depressive symptoms and amygdala activity among individuals homozygous for the short allele and individuals homozygous for the long allele. Both whole brain analyses and region-of-interest analyses confirmed this prediction, revealing a significant negative association among the long allele group and a trend of positive association among the short allele group. These results complement existing reports of short allele related amygdala hyperactivity and suggest an additional neurobiological mechanism whereby the 5-HTTLPR is associated with psychiatric outcomes.

To compare arterial transit time estimates from two efficient transit time mapping techniques using arterial spin labeling (ASL)—flow encoded arterial spin tagging (FEAST) and Look-Locker ASL (LL-ASL). The effects of bipolar gradients and label location were investigated. Six healthy subjects were scanned with pseudo-continuous ASL (pCASL) FEAST and pulsed (PASL) and pCASL variants of LL-ASL at different labeling locations with and without bipolar gradients. Application of transit time mapping was demonstrated in a clinical case. Mean (±SD) macrovascular transit times were 363 ± 39, 676 ± 73 and 908 ± 170 ms for LL-PASL, LL-pCASL with labeling offsets of 60 and 90 mm respectively, showing linear dependence on labeling locations. Mean microvascular transit time for LL-pCASL was 1,463±135 ms, in good agreement with the FEAST estimate of 1,444 ± 128 ms. Data acquired from a patient with stroke demonstrate how transit time and CBF maps provide complementary information for clinical diagnosis. Both FEAST and LL-ASL provide transit time information in clinically acceptable scan times. Bipolar gradients can be used to tailor transit time estimates for different experimental and clinical situations.

Brain activation and deactivation induced by N-back working memory tasks and their load effects have been extensively investigated using positron emission tomography (PET) and blood-oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). However, the underlying mechanisms of BOLD fMRI are still not completely understood and PET imaging requires injection of radioactive tracers. In this study, a pseudo-continuous arterial spin labeling (pCASL) perfusion imaging technique was used to quantify cerebral blood flow (CBF), a well understood physiological index reflective of cerebral metabolism, in N-back working memory tasks. Using pCASL, we systematically investigated brain activation and deactivation induced by the N-back working memory tasks and further studied the load effects on brain activity based on quantitative CBF. Our data show increased CBF in the fronto-parietal cortices, thalamus, caudate, and cerebellar regions, and decreased CBF in the posterior cingulate cortex and medial prefrontal cortex, during the working memory tasks. Most of the activated/deactivated brain regions show an approximately linear relationship between CBF and task loads (0, 1, 2 and 3 back), although several regions show non-linear relationships (quadratic and cubic). The CBF-based spatial patterns of brain activation/deactivation and load effects from this study agree well with those obtained from BOLD fMRI and PET techniques. These results demonstrate the feasibility of ASL techniques to quantify human brain activity during high cognitive tasks, suggesting its potential application to assessing the mechanisms of cognitive deficits in neuropsychiatric and neurological disorders.

The objective of this study was to explore the relationships between IQ and cerebral blood flow (CBF) measured by arterial spin labeling (ASL) in children and adolescents. ASL was used to collect perfusion MRI data on 39 healthy participants aged 7 to 17. The Wechsler Abbreviated Intelligence Scale was administered to determine IQ scores. Multivariate regression was applied to reveal correlations between CBF and IQ scores, accounting for age, sex and global mean CBF. Voxel Based Morphometry (VBM) analysis, which measures regional cortical volume, was performed as a control. Regression analyses were further performed on CBF data with adjustment of regional gray matter density (GMD). A positive correlation between CBF and IQ scores was primarily seen in the subgenual/anterior cingulate, right orbitofrontal, superior temporal and right inferior parietal regions. An inverse relationship between CBF and IQ was mainly observed in bilateral posterior temporal regions. After adjusting for regional GMD, the correlations between CBF and IQ in the subgenual/anterior cingulate cortex, right orbitofrontal, superior temporal regions and left insula remained significant. These findings support the Parieto-Frontal Integration Theory of intelligence, especially the role of the subgenual/anterior cingulate cortex in the neural networks associated with intelligence. The present study also demonstrates the unique value of CBF in assessing brain-behavior relationships, in addition to structural morphometric measures.

Manufacturing of precise couples is the most important key technology for hydraulic products. The hydraulic characteristics are not only strongly correlated with their geometric elements, but also associated with the surface qualities of the couples, including surface roughness and surface texture, and which primarily influence the dead zone, lag rings and friction of the couples. In order to get better surface machining quality of the precise hydraulic couples, the process of surface grinding and polishing was researched. Through process test, the optimum parameters of grinding and polishing processing were found, which made the surface roughness achieved Ra 0.031μm.

Purpose To compare the test–retest reproducibility of three variants of arterial spin labeling (ASL): pseudo-continuous (pCASL), pulsed (PASL) and continuous (CASL). Materials and Methods Twelve healthy subjects were scanned on a 3.0T scanner with PASL, CASL, and pCASL. Scans were repeated within-session, after 1 hour, and after 1 week to assess reproducibility at different scan intervals. Results Comparison of within-subject coefficients of variation (wsCV) demonstrated high within-session reproducibility (ie, low wsCV) for CASL-based methods (gray matter [GM] wsCV for pCASL: 3.5% ± 0.02%, CASL: 4.1% ± 0.07%) compared to PASL (wsCV: 7.5% ± 0.06%), due to the higher signal-to-noise ratio (SNR) associated with continuous labeling, evident in the 20% gain in temporal SNR and 58% gain in raw SNR for pCASL relative to PASL. At the 1-week scan interval, comparable reproducibility between PASL (GM wsCV 9.2% ± 0.12%) and pCASL (GM wsCV 8.5% ± 0.14%) was observed, indicating the dominance of physiological fluctuations. Conclusion Although all three approaches are capable of measuring cerebral blood flow within a few minutes of scanning, the high precision and SNR of pCASL, with its insensitivity to vessel geometry, make it an appealing method for future ASL application studies. J. Magn. Reson. Imaging 2011;33:940–949. © 2011 Wiley-Liss, Inc.

Proton exchange membrane fuel cell (PEMFC) has high power density and energy conversion efficiency. Bipolar plate is one of the key components of the proton exchange membrane fuel cell, not only affects the performance of the battery, but also affects the cost of the battery, which is become a bottlenecks. This paper introduces several common forms of the bipolar plate flow channel of the PEMFC, analyzes their advantages and disadvantages, and then some new type of flow channel type comes up after improvements on this basis, so the future development trend of fuel cells summed up is combined with bionics or using a complex flow field. An overview of the commonly used material and processing of the bipolar plate, respectively, graphite sheet, sheet metal and composite bipolar plates.

Arterial spin labeling (ASL) allows noninvasive quantification of cerebral blood flow (CBF), which can be used as a biomarker of drug effects in pharmacological magnetic resonance imaging (phMRI). In a double-blind, placebo-controlled crossover study, we investigated the effects of a single oral dose of citalopram (20 mg) on resting CBF in 12 healthy subjects, using ASL phMRI. Support-vector machine (SVM) analysis detected significant drug-induced reduction in CBF in brain regions including the amygdala, fusiform gyrus, insula, and orbitofrontal cortex. These regions have been shown to have abnormally elevated CBF in patients with major depression, as well as in subjects genetically prone to depression. Mixed-effects analysis on data extracted from selected regions of interest (ROIs) revealed significant drug effect only in serotonergic areas of the brain (z = -4.45, P < 0.005). These results demonstrate the utility of ASL phMRI as a biomarker of pharmacological activity of orally administered drugs in the brain.

Arterial spin labeling (ASL) provides noninvasive measurement of tissue blood flow, but sensitivity to motion has limited its application to imaging of myocardial blood flow (MBF). While different cardiac phases can be synchronized using ECG triggering, breath holding is generally required to minimize effects of respiratory motion during ASL scanning, which may be challenging in clinical populations. Here a free-breathing myocardial ASL technique with the potential for reliable clinical application is presented, by combining ASL with a navigator-gated, ECG-triggered TrueFISP readout sequence. Dynamic myocardial perfusion signals were measured at multiple delay times that allowed simultaneous fitting of MBF and arterial transit time (ATT). With the assist of a non-rigid motion correction program, the estimated mean MBF was 1.00±0.55mL/g/min with a mean transit time of approximately 400ms. The intraclass correlation coefficient of repeated scans was 0.89 with a mean within subject coefficient of variation (wsCV) of 22%. Perfusion response during mild to moderate stress was further measured. The capability for non-invasive, free-breathing assessment of MBF using ASL may offer an alternative approach to first-pass perfusion MRI for clinical evaluation of patients with coronary artery disease.

Neurovascular coupling associated with visual and vibrotactile stimulations in baboons anesthetized sequentially with isoflurane and ketamine was evaluated using multimodal functional magnetic resonance imaging (fMRI) on a clinical 3-Tesla scanner. Basal cerebral blood flow ( CBF), and combined blood-oxygenation-level-dependent ( BOLD) and CBF fMRI of visual and somatosensory stimulations were measured using pseudo-continuous arterial spin labeling. Changes in stimulus-evoked cerebral metabolic rate of oxygen ( CMRO2) were estimated using calibrated fMRI. Arterial transit time for vessel, gray matter (GM), and white matter (WM) were 250, 570, and 823 ms, respectively. Gray matter and WM CBF, respectively, were 107.8 ± 7.9 and 47.8 ± 3.8 mL per 100 g per minute under isoflurane, and 108.8 ± 10.3 and 48.7 ± 4.2 mL per 100 g per minute under ketamine (mean ± s.e.m., N = 8 sessions, five baboons). The GM/WM CBF ratio was not statistically different between the two anesthetics, averaging 2.3 ± 0.1. Hypercapnia evoked global BOLD and CBF increases. Blood-oxygenation-level-dependent, CBF, and CMRO2 signal changes by visual and vibrotactile stimulations were 0.19% to 0.22%, 18% to 23%, and 4.9% to 6.7%, respectively. The CBF/CMRO2 ratio was 2.9 to 4.7. Basal CBF and fMRI responses were not statistically different between the two anesthetics. This study establishes a multimodal fMRI protocol to probe clinically relevant functional, physiological and metabolic information in large nonhuman primates.

True fast imaging with steady-state precession–based spin tagging with alternating radiofrequency is a promising unenhanced four-dimensional dynamic MR angiography technique for clinical evaluation of cerebrovascular disorders such as arteriovenous malformation, steno-occlusive disease, and aneurysm.

Introduction Colorectal cancer is the third most commonly diagnosed cancer in the word. Carnosine is an endogenous dipeptide found in muscle and brain tissues. The aims of this study are to investigate the regulation of carnosine on adhesion and extravasation of metastasis in human colorectal cancer. Material and methods The human colorectal cancer cells (HCT-116) and human umbilical vein cell line (EA. hy926) cultured were as experimental models. Those adhesive and extravasate abilities and regulate molecular expression were analysed in this study. Results and discussions In adhesion ability assay results shown carnosine were significantly decreased HCT-116 cells adhesion to endothelial cells (EA. hy926 cells). From adhesion-regulating proteins expression analysis result show that carnosine was decreased the levels of integrin in HCT-116 cells and ICAM-1 and E-selectin in EA hy926 cells after 24 hour incubation (p Conclusion The results indicate that carnosine can inhibit the adhesion and extravasation through suppressing of carnosine on NF-κB transcript activation and its regulator adhesion and extravasation related molecular expression in HCT-116 cells and EA hy926 cells.

Arterial spin labeling (ASL) perfusion magnetic resonance imaging has gained wide acceptance for its value in clinical and neuroscience applications during recent years. Its capability for noninvasive and absolute perfusion quantification is a key characteristic that makes ASL attractive for many clinical applications. In the present review, we discuss the main parameters or factors that affect the reliability and accuracy of ASL perfusion measurements. Our secondary goal was to outline potential solutions that may improve the reliability and accuracy of ASL in clinical settings. It was found that, through theoretical analyses, flow quantification is most sensitive to tagging efficiency and estimation of the equilibrium magnetization of blood signal (M(0b)). Variations of blood T1 have a greater effect on perfusion quantification than variations of tissue T1. Arterial transit time becomes an influential factor when it is longer than the postlabeling delay time. The T2's of blood and tissue impose minimal effects on perfusion calculation at field strengths equal to or lower than 3.0 T. Subsequently, we proposed various approaches for in vivo estimation or calibration of the above parameters, such as the use of phase-contrast magnetic resonance imaging for calibration of the labeling efficiency as well as the use of inversion recovery TrueFISP (true fast imaging with steady-state precession) sequence for blood T1 mapping. We also list representative clinical cases in which implicit assumptions for ASL perfusion quantification may be violated, such as the venous outflow effect in children with sickle cell disease. Finally, an optimal imaging protocol including in vivo measurements of several critical parameters was recommended for clinical ASL studies.

The bath compositions are critical to mechanical performance of the coating layer for electroplated diamond tools. In this paper, the effects of different chemical components in bath solution on mechanical properties including tensile strength and hardness of the electroplated coating were investigated by orthogonal experiments. The influences of different chemical components including nickel sulphate, cobalt sulphate and sodium chloride on mechanical properties of the electroplated coating were analysed. The results showed that increasing the component of nickel sulphate caused an unstable situation on tensile strength and hardness of the electroplated coating. However, hardness of the electroplated coating could be improved by increasing the component of cobalt sulphate. The concentration of sodium chloride had no obvious effect on mechanical properties of the electroplated coating layer. The experimental results revealed that the optimised bath compositions were at 270 g/L nickel sulphate, 20 g/L cobalt sulphate, and 10 g/L sodium chloride.

In this paper we describe the operation and performance of the HERA-B Outer Tracker, a 112674 channel system of planar drift tube layers. The performance of the HERA-B Outer Tracker system fullfilled all requirements for stable and efficient operation in a hadronic environment, thus confirming the adequacy of the honeycomb drift tube technology and of the front-end readout system. The detector was stably operated with a gas gain of 30000 in an Ar/CF4/CO2 (65:30:5) gas mixture, yielding a good efficiency for triggering and track reconstruction, larger than 95 % for tracks with momenta above 5 GeV/c. The hit resolution of the drift cells was 300 to 320 micrometers and the relative momentum resolution can be described as: sigma(p)/p (in %) = (1.61 +- 0.02) + (0.0051 +- 0.0006) p. At the end of the HERA-B running no aging effects in the Outer Tracker cells were observed., Comment: 38 pages, 20 figures. v2: Added clarifications about trigger efficiency, momentum resolution and alignment precision. Corrected typos. Improved figure quality

The expression of neuropeptide Y (NPY) and its co-messenger, agouti-related peptide (AgRP), in arcuate neurons of the hypothalamus is increased during lactation in rats. Our research has been addressing the questions of the physiological actions of these peptides during lactation and the physiological signals associated with lactation that result in increased expression of their genes. Our studies indicate that NPY and AgRP exert pleiotropic actions during lactation that help integrate neuroendocrine regulation of energy balance with controls over anterior and posterior pituitary hormone secretion. Further, reciprocal signaling to the NPY/AgRP system by leptin and ghrelin is responsible for the changes in expression of these hypothalamic peptides in lactating animals, and thus, may contribute to regulation of food intake and the various neuroendocrine adaptations of lactation.

Hyperperfusion detected on arterial spin labeling (ASL) images acquired after acute stroke onset has been shown to correlate with development of subsequent intracerebral hemorrhage. We present in this study a quantitative hyperperfusion detection model that can provide an objective decision support for the interpretation of ASL cerebral blood flow (CBF) maps and rapidly delineate hyperperfusion regions. The detection problem is solved using Deep Learning such that the model relates ASL image patches to the corresponding label (normal or hyperperfused). Our method takes into account the regional intensity values of contralateral hemisphere during the labeling of a pixel. Each input vector is associated to a label corresponding to the presence of hyperperfusion that was manually established by a clinical researcher in Neurology. When compared to the manually established hyperperfusion, the predicted maps reached an accuracy of 97.45 ± 2.49% after crossvalidation. Pattern recognition based on deep learning can provide an accurate and objective measure of hyperperfusion on ASL CBF images and could therefore improve the detection of hemorrhagic transformation in acute stroke patients.

International audience; PURPOSE: To identify potential biomarkers of the renal impairment in lupus nephritis using a multi-parametric renal quantitative MRI (qMRI) protocol including diffusion weighted imaging (DWI), blood oxygen level dependent (BOLD), arterial spin labeling (ASL) and T1rho MRI between a cohort of healthy volunteers and lupus nephritis (LN) patients. MATERIALS AND METHODS: The renal qMRI protocol was performed twice with repositioning in between on 10 LN patients and 10 matched controls at 1.5 T. Navigator-gated and breath-hold acquisitions followed by non-rigid image registration were used to control respiratory motion. The repeatability of the 4 MRI modalities was evaluated with the intra-class correlation coefficient (ICC) and within-subject coefficient of variation (wsCV). Unpaired t-test and stepwise logistic regression were carried out to evaluate qMRI parameters between the LN and control groups. RESULTS: The reproducibility of the 4 qMRI modalities ranged from moderate to good (ICC=0.4-0.91, wsCV≤12%) with a few exceptions. T1rho MRI and ASL renal blood flow (RBF) demonstrated significant differences between the LN and control groups. Stepwise logistic regression yielded only one significant parameter (medullar T1rho) in differentiating LN from control groups with 95% accuracy. CONCLUSION: A reasonable degree of test-retest repeatability and accuracy of a multi-parametric renal qMRI protocol has been demonstrated in healthy volunteers and LN subjects. T1rho and ASL RBF are promising imaging biomarkers of LN.

Arterial spin labeling (ASL) is an increasingly established magnetic resonance imaging (MRI) technique that is finding broader applications in studying the healthy and diseased brain. This review addresses the use of ASL to assess brain function in the resting state. Following a brief technical description, we discuss the use of ASL in the following main categories: (1) resting-state functional connectivity (FC) measurement: the use of ASL-based cerebral blood flow (CBF) measurements as an alternative to the blood oxygen level-dependent (BOLD) technique to assess resting-state FC; (2) the link between network CBF and FC measurements: the use of network CBF as a surrogate of the metabolic activity within corresponding networks; and (3) the study of resting-state dynamic CBF-BOLD coupling and cerebral metabolism: the use of dynamic CBF information obtained using ASL to assess dynamic CBF-BOLD coupling and oxidative metabolism in the resting state. In addition, we summarize some future challenges and interesting research directions for ASL, including slice-accelerated (multiband) imaging as well as the effects of motion and other physiological confounds on perfusion-based FC measurement. In summary, this work reviews the state-of-the-art of ASL and establishes it as an increasingly viable MRI technique with high translational value in studying resting-state brain function.

© 2015 The Authors. Background: Neuroimaging studies can shed light on the neurobiological underpinnings of autism spectrum disorders (ASD). Studies of the resting brain have shown both altered baseline metabolism from PET/SPECT and altered functional connectivity (FC) of intrinsic brain networks based on resting-state fMRI. To date, however, no study has investigated these two physiological parameters of resting brain function jointly, or explored the relationship between these measures and ASD symptom severity. Methods: Here, we used pseudo-continuous arterial spin labeling with 3D background-suppressed GRASE to assess resting cerebral blood flow (CBF) and FC in 17 youth with ASD and 22 matched typically developing (TD) children. Results: A pattern of altered resting perfusion was found in ASD versus TD children including frontotemporal hyperperfusion and hypoperfusion in the dorsal anterior cingulate cortex. We found increased local FC in the anterior module of the default mode network (DMN) accompanied by decreased CBF in the same area. In our cohort, both alterations were associated with greater social impairments as assessed with the Social Responsiveness Scale (SRS-total T scores). While FC was correlated with CBF in TD children, this association between FC and baseline perfusion was disrupted in children with ASD. Furthermore, there was reduced long-range FC between anterior and posterior modules of the DMN in children with ASD. Conclusion: Taken together, the findings of this study - the first to jointly assess resting CBF and FC in ASD - highlight new avenues for identifying novel imaging markers of ASD symptomatology.

Introduction: A main obstacle that impedes standardized clinical and research applications of arterial spin labeling (ASL), is the substantial differences between the commercial implementations of ASL from major MRI vendors. In this study, we compare a single identical 2D gradient-echo EPI pseudo-continuous ASL (PCASL) sequence implemented on 3T scanners from three vendors (General Electric Healthcare, Philips Healthcare and Siemens Healthcare) within the same center and with the same subjects. Material and methods: Fourteen healthy volunteers (50% male, age 26.4 +/- 4.7 years) were scanned twice on each scanner in an interleaved manner within 3 h. Because of differences in gradient and coil specifications, two separate studies were performed with slightly different sequence parameters, with one scanner used across both studies for comparison. Reproducibility was evaluated by means of quantitative cerebral blood flow (CBF) agreement and inter-session variation, both on a region-of-interest (ROI) and voxel level. In addition, a qualitative similarity comparison of the CBF maps was performed by three experienced neuro-radiologists. Results: There were no CBF differences between vendors in study 1 (p > 0.1), but there were CBF differences of 2-19% between vendors in study 2 (p 0.1) but one of the ROIs (p

© 2015 Elsevier Inc. Simultaneous multi-slice (SMS) or multiband (MB) imaging has recently been attempted for arterial spin labeled (ASL) perfusion MRI in conjunction with echo-planar imaging (EPI) readout. It was found that SMS-EPI can reduce the T1relaxation effect of the label and improve image coverage and resolution with little penalty in signal-to-noise ratio (SNR). However, EPI still suffers from geometric distortion and signal dropout from field inhomogeneity effects especially at high and ultrahigh magnetic fields. Here we present a novel scheme for achieving high fidelity distortion-free quantitative perfusion imaging by combining pseudo-continuous ASL (pCASL) with SMS Turbo-FLASH (TFL) readout at both 3 and 7T. Bloch equation simulation was performed to characterize and optimize the TFL-based pCASL perfusion signal. Two MB factors (3 and 5) were implemented in SMS-TFL pCASL and compared with standard 2D TFL and EPI pCASL sequences. The temporal SNR of SMS-TFL pCASL relative to that of standard TFL pCASL was 0.76±0.10 and 0.74±0.11 at 7T and 0.70±0.05 and 0.65±0.05 at 3T for MB factor of 3 and 5, respectively. By implementing background suppression in conjunction with SMS-TFL at 3T, the relative temporal SNR improved to 0.84±0.09 and 0.79±0.10 for MB factor of 3 and 5, respectively. Compared to EPI pCASL, significantly increased temporal SNR (p

There has been tremendous interest in applying functional magnetic resonance imaging-based resting-state functional connectivity (rs-fcMRI) measurements to the study of brain function. However, a lack of understanding of the physiological mechanisms of rs-fcMRI limits their ability to interpret rs-fcMRI findings. In this work, the authors examine the regional associations between rs-fcMRI estimates and dynamic coupling between the blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF), as well as resting macrovascular volume. Resting-state BOLD and CBF data were simultaneously acquired using a dual-echo pseudocontinuous arterial spin labeling (pCASL) technique, whereas macrovascular volume fraction was estimated using time-of-flight MR angiography. Functional connectivity within well-known functional networks—including the default mode, frontoparietal, and primary sensory-motor networks—was calculated using a conventional seed-based correlation approach. They found the functional connectivity strength to be significantly correlated with the regional increase in CBF-BOLD coupling strength and inversely proportional to macrovascular volume fraction. These relationships were consistently observed within all functional networks considered. Their findings suggest that highly connected networks observed using rs-fcMRI are not likely to be mediated by common vascular drainage linking distal cortical areas. Instead, high BOLD functional connectivity is more likely to reflect tighter neurovascular connections, attributable to neuronal pathways.

Blood oxygenation level dependent (BOLD) and arterial spin labeling (ASL) are two predominant resting-state fMRI techniques in mapping spontaneous brain activities. At single voxel level, cerebral blood flow (CBF) measured by ASL and amplitude of low frequency fluctuations (ALFF) of BOLD have been recognized as useful indices to characterize brain function in health and disease. However, no study has directly compared the test-retest reliability between BOLD and CBF contrasts on the same group of subjects at single voxel level. Moreover, both eyes-open and eyes-closed conditions have been employed as resting states, but it is still not clear which state is more reliable. Here we collected BOLD and ASL data during eyes-open and eyes-closed states across three scanning visits on twenty-two healthy young subjects. CBF-mean, BOLD- and CBF-ALFF were computed to characterize corresponding brain activities at single voxel level. Seed-based functional connectivity (FC) with the posterior cingulate cortex (PCC) was further calculated for both BOLD and CBF data. Intra-class correlation was used as the index of long-term reliability between visits 1 and 2 (two months apart) and short-term reliability between visits 2 and 3 (on the same day). Both short- and long-term reliabilities for CBF-mean and BOLD-ALFF were high, but were lower for CBF-ALFF, BOLD- and CBF-FC in both eyes-open and eyes-closed states. Direct comparisons showed that brain regions with the highest reliability of CBF-mean were mainly in the gray matter. The reliability of CBF-ALFF and BOLD-FC was lower than that of BOLD-ALFF, and the reliability of CBF-FC was lower than those of both CBF-ALFF and BOLD-FC. Furthermore, we observed that reliabilities of the eyes-open state were higher than those of the eyes-closed state for both imaging contrasts, though the effect size was small. Voxel-wise comparisons demonstrated that the long-term reliability of BOLD-ALFF was significantly higher with eyes open in the visual system, and both the short- and long-term reliability of BOLD-FC was slightly higher with eyes open in the default mode network. Moreover, we showed that denoising decreased the reliability of both ALFF and FC of both BOLD and ASL contrasts. In conclusion, our results indicated that CBF-mean and BOLD-ALFF could both be used as reliable indices for characterizing resting-state brain activities at single voxel level and recommended the eyes-open state for resting-state studies, especially for those targeting the visual system and default mode network.

© 2015 International Society for Cerebral Blood Flow & Metabolism, Inc. The purpose of this study was to investigate the relationship between hyperperfusion and hemorrhagic transformation (HT) in acute ischemic stroke (AIS). Pseudo-continuous arterial spin labeling (ASL) with background suppressed 3D GRASE was performed during routine clinical magnetic resonance imaging (MRI) on AIS patients at various time points. Arterial spin labeling cerebral blood flow (CBF) maps were visually inspected for the presence of hyperperfusion. Hemorrhagic transformation was followed during hospitalization and was graded on gradient recalled echo (GRE) scans into hemorrhagic infarction (HI) and parenchymal hematoma (PH). A total of 361 ASL scans were collected from 221 consecutive patients with middle cerebral artery stroke from May 2010 to September 2013. Hyperperfusion was more frequently detected posttreatment (odds ratio (OR)=4.8, 95% confidence interval (CI) 2.5 to 8.9, P

We present RIPMMARC (Rotation Invariant Patch-based Multi-Modality Analysis aRChitecture), a flexible and widely applicable method for extracting information unique to a given modality from a multi-modal data set. We use RIPMMARC to improve the interpretation of arterial spin labeling (ASL) perfusion images by removing the component of perfusion that is predicted by the underlying anatomy. Using patch-based, rotation invariant descriptors derived from the anatomical image, we learn a predictive relationship between local neuroanatomical structure and the corresponding perfusion image. This relation allows us to produce an image of perfusion that would be predicted given only the underlying anatomy and a residual image that represents perfusion information that cannot be predicted by anatomical features. Our learned structural features are significantly better at predicting brain perfusion than tissue probability maps, which are the input to standard partial volume correction techniques. Studies in test-retest data show that both the anatomically predicted and residual perfusion signals are highly replicable for a given subject. In a pediatric population, both the raw perfusion and structurally predicted images are tightly linked to age throughout adolescence throughout the brain. Interestingly, the residual perfusion also shows a strong correlation with age in selected regions including the hippocampi (corr = 0.38, p-value

Resting-state fMRI studies have increasingly focused on multi-contrast techniques, such as BOLD and ASL imaging. However, these techniques may reveal different aspects of brain activity (e.g., static vs. dynamic), and little is known about the similarity or disparity of these techniques in detecting resting-state brain activity. It is therefore important to assess the static and dynamic characteristics of these fMRI techniques to guide future applications. Here we acquired fMRI data while subjects were in eyes-closed (EC) and eyes-open (EO) states, using both ASL and BOLD techniques, at two research centers (NIDA and HNU). Static brain activity was calculated as voxel-wise mean cerebral blood flow (CBF) using ASL, i.e., CBF-mean, while dynamic activity was measured by the amplitude of low frequency fluctuations (ALFF) of BOLD, i.e., BOLD-ALFF, at both NIDA and HNU, and CBF, i.e., CBF-ALFF, at NIDA. We showed that mean CBF was lower under EC than EO in the primary visual cortex, while BOLD-ALFF was higher under EC in the primary somatosensory cortices extending to the primary auditory cortices and lower in the lateral occipital area. Interestingly, mean CBF and BOLD-ALFF results overlapped at the visual cortex to a very small degree. Importantly, these findings were largely replicated by the HNU dataset. State differences found by CBF-ALFF were located in the primary auditory cortices, which were generally a subset of BOLD-ALFF and showed no spatial overlap with CBF-mean. In conclusion, static brain activity measured by mean CBF and dynamic brain activity measured by BOLD- and CBF-ALFF may reflect different aspects of resting-state brain activity and a combination of ASL and BOLD may provide complementary information on the biophysical and physiological processes of the brain.

Magnetic resonance imaging (MRI) captures the dynamics of brain development with multiple modalities that quantify both structure and function. These measurements may yield valuable insights into the neural patterns that mark healthy maturation or that identify early risk for psychiatric disorder. The Pediatric Template of Brain Perfusion (PTBP) is a free and public neuroimaging resource that will help accelerate the understanding of childhood brain development as seen through the lens of multiple modality neuroimaging and in relation to cognitive and environmental factors. The PTBP uses cross-sectional and longitudinal MRI to quantify cortex, white matter, resting state functional connectivity and brain perfusion, as measured by Arterial Spin Labeling (ASL), in 120 children 7–18 years of age. We describe the PTBP and show, as a demonstration of validity, that global summary measurements capture the trajectories that demarcate critical turning points in brain maturation. This novel resource will allow a more detailed understanding of the network-level, structural and functional landmarks that are obtained during normal adolescent brain development.

Versazyme (VZ) is a keratinase-based feed additive. Broiler diets were formulated with low (95%), medium (100%), or high (105%) CP and amino acid levels relative to US Poultry Industry Reporting Service averages (2003). In each diet, amino acid minimums were maintained relative to the percentage of CP. The protein levels were as follows: starter—21, 22, 23%; grower—19, 20, 21%; finisher—17, 18, 19%; and withdrawal—16, 17, 18%. Mixed sex broilers 0 to 48 d of age were fed the 3 protein levels with and without VZ (0.10%) in a 3 × 2 factorial experiment. Statistical main effects indicated 48-d BW was greater on the high protein diets (2.42 kg) compared with low protein (2.36 kg), with the medium protein diet being intermediate (2.40 kg). Overall, VZ significantly (P

The paper states the characteristic of Granite Surface Profiles. Gauss Filtering has been adopted on original granite surface profiles curver, and then researching its Roughness and Fractal. The method is an available and fast computation method for roughness and fractal to Granite surface profiles. The Relation Study of Roughness and Glossiness to Fractal have been Study by experiment.

A measurement of the polarization of Λ and Λ ¯ baryons produced in pC and pW collisions at s = 41.6 GeV has been performed with the HERA-B spectrometer. The measurements cover the kinematic range of 0.6 GeV / c p ⊥ 1.2 GeV / c in transverse momentum and − 0.15 x F 0.01 in Feynman-x. The polarization results from the two different targets agree within the statistical error. In the combined data set, the largest deviation from zero, + 0.054 ± 0.029 , is measured for x F ≲ − 0.07 . Zero polarization is expected at x F = 0 in the absence of nuclear effects. The polarization results for the Λ agree with a parametrization of previous measurements which were performed at positive x F values, where the Λ polarization is negative. Results of Λ ¯ polarization measurements are consistent with zero.

This paper studies differentially-driven microstrip antennas. The theory of microstrip antennas based on the improved cavity model is expanded to analyze the input impedance and radiation characteristics of the differentially-driven microstrip antennas. The differentially-driven microstrip antennas were fabricated. Their performances were experimentally verified. Results show that the occurrence of resonance for the differentially-driven microstrip antennas also depends on the ratio of the separation /spl xi/ of the dual feeds to the free-space wavelength /spl lambda//sub o/. When the dual feeds are located far from each other /spl xi///spl lambda//sub o/>0.1, the resonance occurs, and the input resistance at resonance is rather large. However, when the dual feeds are located near to each other /spl xi///spl lambda//sub o/

This paper presents the circuit model of a microstrip patch antenna on a ceramic land grid array (CLGA) package for the antenna-chip codesign of a highly integrated radio-frequency (RF) transceiver. The microstrip patch antenna is fed by packaging interconnect components such as bond wires, signal traces, and vias in a ground-signal-ground (G-S-G) configuration from the carried chip. The circuit model that consists of RLC lumped elements of both microstrip patch antenna and feeding interconnect components has been developed with an emphasis on verifying existing or deriving analytical formulas. The RLC values of the microstrip patch antenna are calculated with our improvements to existing computer-aided design formulas, while the RLC values of the feeding interconnect components are calculated with more efforts. In particular the C values related to the vias and signal traces require to be calculated numerically and they are calculated here with the method of moments and the conformal mapping method, respectively. The circuit model is validated with numerical simulations (High Frequency Structure Simulator) and network analyzer measurements.

The authors have developed a nanomanufacturing platform based on wafer-level nanoreplication with mold and nanopattern transfer by nanolithography. The nanoreplication process, which is based on imprinting a single-layer spin-coated ultraviolet (UV)-curable resist, achieved good nanopatterning fidelity and on-wafer uniformity with high throughput. Some manufacturing issues of the nanoreplication process, such as the impact of wafer and mold surface particles on nanoreplication yield, are also discussed. Nano-optic devices, such as, quarter-wave plates and polarizers, were manufactured with the nanomanufacturing platform. An average wafer-level optical performance yield of 86% was achieved. The developed technology is applied for high-throughput and low-cost manufacturing nanostructure-based optical devices and integrated optical devices.

1, 6-Bis[4-(4-amino-3-hydroxyphenoxy)phenyl]diamantine (DPD), a new cytostatic and differentiation inducing agent, was found to inhibit the growth of several cancer cell lines in the National Cancer Institute (NCI) Anticancer Drug Screen system. Previously, we demonstrated that DPD inhibited the growth of human colon cancer cell lines both in vitro and in vivo. In this study, we examined the anticancer effects of DPD on two human leukemia cells lines. DPD exerted growth inhibitory activities in vitro against two human leukemia cell lines, the promyeloid line HL-60 and the lymphoblastic line Molt-3. The in vivo effect of tumor growth suppression by DPD was also observed in mouse xenografts. No acute toxicity was observed after an intra-peritoneal challenge of DPD in "severe combined immune-deficiency" (SCID) mice twice a week. The in vitro study showed HL-60 was more sensitive to DPD than Molt-3 through induction of G(0)/G(1) cell-cycle arrest with the appearance of a hypodiploid DNA fraction. The increased superoxide (O(2)(-)), dissipation of the mitochondrial membrane potential, activation of caspase 3, and increase in annexin V binding were evident before apoptosis in DPD-treated cells. The superoxide dismutase 1 (SOD1) mRNA expression was also decreased in DPD-treated HL-60 and Molt-3 cells. Thus, it appeared that inhibition of SOD might be the major cause for the production of cellular superoxide with concomitant decrease of H(2)O(2) in DPD-treated cells. Addition of antioxidant can reduce DPD-induced mitochondrial damage, caspase activation, and annexin V binding in HL-60 cells. The results suggest that the cellular generation of O(2)(-) plays a role in initiating and coordinating DPD-mediated growth arrest and apoptosis of HL-60 cells. Importantly, addition of arsenic trioxide, a compound capable of reactive oxygen species (ROS) generation, significantly enhanced the in vitro activity of DPD. These results suggest that DPD appears to be a potential new modality in human leukemia therapy.

We developed a new type of wire-grid polarizer, the so-called nanowire-grid polarizer, which has achieved commercial quality optical performance and reliability. The nanowire-grid polarizer has cores composed of silicon dioxide nanowalls with metal coating on one side. These cores are surrounded by multilayer thin films for antireflection. The core nanowire grid utilizes nano-sized high-aspect ratio dielectric walls as a support for forming a high aspect ratio metal nanowire grid, which significantly reduces energy loss due to metal absorption for the transmitted beam while achieving high extinction ratio for the blocked beam. For all design simulations, we utilized a rigorous coupled-wave analysis and modal method. The nanowire-grid structure was fabricated by a wafer-based nanoreplication lithography and pattern-transfer techniques, which are capable of producing a large-area high aspect ratio nanostructure with high throughput and low cost. The optical performance of the nanowire-grid polarizer was characterized thoroughly. Furthermore, the nanowire-grid polarizer has been integrated monolithically with a Faraday magnetooptic garnet, which results in an integrated semi-isolator. Full free-space isolators based on the integrated semi-isolators have been also developed, which achieved excellent performance, good enough for commercial applications.

Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (U) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((U) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.

The corrosion behavior of weathering steel and carbon steel exposed in marine atmosphere for 4 years were studied by means of regression analysis, rust structure observation, X-ray diffraction, Raman spectrum and electrochemical impedance spectra techniques. The results show that the corrosion procedure of weathering steel is divided into two steps. In the first step, the corrosion rate is higher, while in the second step the corrosion rate is remarkably reduced due to a compact rust layer formed gradually during exposure. The compact rust layer on weathering steel, darkened observed using polarized light, is composed of Cr substitute iron oxyhydroxide. Furthermore, an equivalent circuit is set up to represent the interfaces between rusted steels and 3% NaCl solution, and the rust layer resistances of the steels were deduced from an extrapolation of the electrochemistry impedance spectra to estimate the protective properties.

Background: It was reported that multidrug resistance gene 1 (MDR1) encoding human P-glycoprotein (Pgp) may play an important role in multidrug resistance of lung cancer. Therefore, before initiating chemotherapy, it is important to accurately determine the presence of Pgp in lung cancer, to achieve a satisfactory chemotherapy response. Objectives: The aim of this study was to compare immunohistochemical analyses of Pgp expression and response to paclitaxel in non-small-cell lung cancer (NSCLC). Methods: Before chemotherapy with paclitaxel, 50 patients with stage IIIb or IV NSCLC were enrolled in this study. Immunohistochemical analyses were performed on multiple nonconsecutive sections of the biopsy specimens to determine Pgp expression. Chemotherapy response was evaluated in the 3rd month after completion of treatment by clinical and radiological methods. Results: All of the 28 (100%) cases with good response had negative Pgp expression and 15 of the 22 (68%) cases with poor response had positive Pgp expression (p < 0.05). No significant differences were found for other prognostic factors (age, sex, body weight loss, performance status, tumor cell type, and tumor stage) between good response and poor response groups. Conclusions: Although Pgp expression in NSCLC does not fully predict chemotherapy response to paclitaxel-based therapy, detection of Pgp expression will aid in planning paclitaxel-based therapy for patients with advanced NSCLC. Further studies with a larger number of patients and a longer time of follow-up are necessary to confirm our findings.

Background: Systemic lupus erythematosus (SLE) can affect every organ. Involvement of the lungs in this disease is a significant cause of morbidity and mortality. Objectives: To assess pulmonary vascular endothelium damage in SLE by lung uptake of technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO). Methods: Lung uptake of 99mTc-HMPAO was measured in 20 SLE patients and for comparison in 25 controls without SLE, referred for brain imaging due to dementia or stroke. Of the 20 SLE patients, 10 had significant clinical pulmonary manifestations. However, all SLE patients had normal chest X-ray findings. Anterior lung image, including a large part of the liver, was taken 10 min after intravenous injection of 20–25 mCi of 99mTc-HMPAO. Regions of interest were calculated over the liver and lung. Results: The mean lung/liver uptake ratio in patients without SLE was 0.36 ± 0.1. The mean lung/liver uptake ratio in SLE patients was 0.79 ± 0.58. The difference was significant. Conclusions: Our results indicated that determining the ratio of lung/liver uptake of 99mTc-HMPAO may be a useful complementary method to assess pulmonary injury in SLE patients.