1,236 research outputs found

    Subharmonic and Endoscopic Contrast Imaging of Pancreatic Masses: A Pilot Study.

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    OBJECTIVES: To use subharmonic imaging (SHI) to depict the vascularity of pancreatic masses compared to contrast-enhanced endoscopic ultrasound (EUS) and pathologic results. METHODS: Sixteen patients scheduled for biopsy of a pancreatic mass were enrolled in an Institutional Review Board-approved study. Pulse-inversion SHI (transmitting/receiving at 2.5/1.25 MHz) was performed on a LOGIQ 9 system (GE Healthcare, Milwaukee, WI) with a 4C transducer, whereas contrast harmonic EUS (transmitting/receiving at 4.7/9.4 MHz) was performed with a radial endoscope (GF-UTC180; Olympus Corporation, Tokyo, Japan) connected to a ProSound SSD α-10 scanner (Hitachi Aloka, Tokyo, Japan). Two injections of the contrast agent Definity (Lantheus Medical Imaging, North Billerica, MA) were administrated (0.3-0.4 and 0.6-0.8 mL for EUS and SHI, respectively). Contrast-to-tissue ratios (CTRs) in the mass and an adjacent vessel were calculated. Four physicians independently scored the images (benign to malignant) for diagnostic accuracy and inter-reader agreement. RESULTS: One patient dropped out before imaging, leaving 11 adenocarcinomas, 1 gastrointestinal stromal tumor with pancreatic infiltration, and 3 benign masses. Marked subharmonic signals were obtained in all patients, with intratumoral blood flow clearly visualized with SHI. Significantly greater CTRs were obtained in the masses with SHI than with EUS (mean ± SD, 1.71 ± 1.63 versus 0.63 ± 0.89; P = .016). There were no differences in the CTR in the surrounding vessels or when grouped by pathologic results (P \u3e .60). The accuracies for contrast EUS and SHI were low (\u3c53%), albeit with a greater κ value for SHI (0.34) than for EUS (0.13). CONCLUSIONS: Diagnostic accuracy of contrast EUS and transabdominal SHI for assessment of pancreatic masses was quite low in this pilot study. However, SHI had improved tumoral CTRs relative to contrast EUS

    AMPK Directly Inhibits NDPK Through a Phosphoserine Switch to Maintain Cellular Homeostasis

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    AMP-activated protein kinase (AMPK) is a key energy sensor that regulates metabolism to maintain cellular energy balance. AMPK activation has also been proposed to mimic benefits of caloric restriction and exercise. Therefore, identifying downstream AMPK targets could elucidate new mechanisms for maintaining cellular energy homeostasis. We identified the phosphotransferase nucleoside diphosphate kinase (NDPK), which maintains pools of nucleotides, as a direct AMPK target through the use of two-dimensional differential in-gel electrophoresis. Furthermore, we mapped the AMPK/NDPK phosphorylation site (serine 120) as a functionally potent enzymatic “off switch” both in vivo and in vitro. Because ATP is usually the most abundant cellular nucleotide, NDPK would normally consume ATP, whereas AMPK would inhibit NDPK to conserve energy. It is intriguing that serine 120 is mutated in advanced neuroblastoma, which suggests a mechanism by which NDPK in neuroblastoma can no longer be inhibited by AMPK-mediated phosphorylation. This novel placement of AMPK upstream and directly regulating NDPK activity has widespread implications for cellular energy/nucleotide balance, and we demonstrate in vivo that increased NDPK activity leads to susceptibility to energy deprivation–induced death

    A diamond AGPM coronagraph for VISIR

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    In recent years, phase mask coronagraphy has become increasingly efficient in imaging the close environment of stars, enabling the search for exoplanets and circumstellar disks. Coronagraphs are ideally suited instruments, characterized by high dynamic range imaging capabilities, while preserving a small inner working angle. The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) consists of a vector vortex induced by a rotationally symmetric subwavelength grating. This technique constitutes an almost unique solution to the achromatization at longer wavelengths (mid-infrared). For this reason, we have specially conceived a mid-infrared AGPM coronagraph for the forthcoming upgrade of VISIR, the mid-IR imager and spectrograph on the VLT at ESO (Paranal), in collaboration with members of the VISIR consortium. The implementation phase of the VISIR Upgrade Project is foreseen for May-August 2012, and the AGPM installed will cover the 11-13.2 ÎĽm spectral range. In this paper, we present the entire fabrication process of our AGPM imprinted on a diamond substrate. Diamond is an ideal material for mid-infrared wavelengths owing to its high transparency, small dispersion, extremely low thermal expansion and outstanding mechanical and chemical properties. The design process has been performed with an algorithm based on the rigorous coupled wave analysis (RCWA), and the micro-fabrication has been carried out using nano-imprint lithography and reactive ion etching. A precise grating profile metrology has also been conducted using cleaving techniques. Finally, we show the deposit of fiducials (i.e. centering marks) with Aerosol Jet Printing (AJP). We conclude with the ultimate coronagraph expected performances

    A theoretical study of the 1B2u and 1B1u vibronic bands in benzene

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    The two lowest bands, 1B2u and 1B1u, of the electronic spectrum of the benzene molecule have been studied theoretically using a new method to compute vibronic excitation energies and intensities. The complete active space (CAS) self-contained field (SCF) method (with six active Ď€-orbitals) was used to compute harmonic force field for the ground state and the 1B2u and 1B1u electronic states. A linear approximation has been used for the transition dipole as a function of the nuclear displacement coordinates. Derivatives of the transition dipole were computed using a variant of the CASSCF state interaction method. Multiconfigurational second-order perturbation theory (CASPT2) was used to obtain absolute excitation energies (12 active Ď€-orbitals). The results show that the approach works well. Vibrational progressions are well described in both bands and intensities, and energies are in agreement with experiment, in particular when CASPT2 derived geometries are used. One interesting result is that computed vertical energies fall about 0.1 eV on the high energy side of the band [email protected]

    L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCam

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    We present the first observations obtained with the L'-band AGPM vortex coronagraph recently installed on LBTI/LMIRCam. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from diamond subwavelength gratings. It is designed to improve the sensitivity and dynamic range of high-resolution imaging at very small inner working angles, down to 0.09 arcseconds in the case of LBTI/LMIRCam in the L' band. During the first hours on sky, we observed the young A5V star HR\,8799 with the goal to demonstrate the AGPM performance and assess its relevance for the ongoing LBTI planet survey (LEECH). Preliminary analyses of the data reveal the four known planets clearly at high SNR and provide unprecedented sensitivity limits in the inner planetary system (down to the diffraction limit of 0.09 arcseconds).Comment: 9 pages, 4 figures, SPIE proceeding

    A Convolutional Approach to Vertebrae Detection and Labelling in Whole Spine MRI

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    We propose a novel convolutional method for the detection and identification of vertebrae in whole spine MRIs. This involves using a learnt vector field to group detected vertebrae corners together into individual vertebral bodies and convolutional image-to-image translation followed by beam search to label vertebral levels in a self-consistent manner. The method can be applied without modification to lumbar, cervical and thoracic-only scans across a range of different MR sequences. The resulting system achieves 98.1% detection rate and 96.5% identification rate on a challenging clinical dataset of whole spine scans and matches or exceeds the performance of previous systems on lumbar-only scans. Finally, we demonstrate the clinical applicability of this method, using it for automated scoliosis detection in both lumbar and whole spine MR scans.Comment: Accepted full paper to Medical Image Computing and Computer Assisted Intervention 2020. 11 pages plus appendi

    Association of Exposure to Infections in Childhood with Risk of Eating Disorders in Adolescent Girls

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    Importance: Infections are recognized as playing a critical role in the risk of psychiatric disorders and suicidal behavior; however, few studies have evaluated the risk of eating disorders. Objective: To evaluate the association of hospitalization for infections and treatment with anti-infective agents with the risk of an eating disorder diagnosis. Design, Setting, and Participants: A nationwide, population-based, prospective cohort study of 525643 girls born from January 1, 1989, to December 31, 2006, and followed up until December 31, 2012, was conducted using individual-level data drawn from Danish longitudinal registers. Data were analyzed from January 15 to June 15, 2018, using survival analysis models and adjusted for age, calendar period, parental educational level, and parental history of psychiatric illness. Exposures: Hospital admission for infections and prescribed anti-infective agents for infections. Main Outcomes and Measures: The main outcome of interest was diagnosis of an eating disorder (anorexia nervosa, bulimia nervosa, or eating disorder not otherwise specified) in a hospital, outpatient clinic, or emergency department setting. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and accompanying 95% CIs. Results: The study population consisted of 525643 adolescent girls: 2131 received a diagnosis of anorexia nervosa (median [range] age, 15.2 [8.6-21.3] years), 711 received a diagnosis of bulimia nervosa (median [range] age, 17.9 [13.4-22.7] years), and 1398 received a diagnosis of an eating disorder not otherwise specified (median [range] age, 15.6 [8.6-21.6] years). A total of 525643 adolescent girls were followed up for 4601720.4 person-years until a mean age of 16.2 years (range, 10.5-22.7 years). Severe infections that required hospitalization were associated with an increased risk of a subsequent diagnosis of anorexia nervosa by 22% (HR, 1.22; 95% CI, 1.10-1.35), bulimia nervosa by 35% (HR, 1.35; 95% CI, 1.13-1.60), and eating disorder not otherwise specified by 39% (HR, 1.39; 95% CI, 1.23-1.57) compared with adolescent girls without hospitalizations for infections. Infections treated with anti-infective agents were associated with an increased risk of a subsequent diagnosis of anorexia nervosa by 23% (HR, 1.23; 95% CI, 1.10-1.37), bulimia nervosa by 63% (HR, 1.63; 95% CI, 1.32-2.02), and eating disorder not otherwise specified by 45% (HR, 1.45; 95% CI, 1.25-1.67) compared with adolescent girls without infections treated with anti-infective agents. Conclusions and Relevance: The findings suggest that hospital-treated infections and less severe infections treated with anti-infective agents are associated with increased risk of subsequent anorexia nervosa, bulimia nervosa, and eating disorders not otherwise specified and that future studies should investigate whether these associations are causal and identify the exact mechanisms between infections and subsequent inflammatory processes with eating disorders

    Density growth in Kantowski-Sachs cosmologies with cosmological constant

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    In this work the growth of density perturbations in Kantowski-Sachs cosmologies with a positive cosmological constant is studied, using the 1+3 and 1+1+2 covariant formalisms. For each wave number we obtain a closed system for scalars formed from quantities that are zero on the background and hence are gauge-invariant. The solutions to this system are then analyzed both analytically and numerically. In particular the effects of anisotropy and the behaviour close to a bounce in the cosmic scale factor are considered. We find that typically the density gradient in the bouncing directions experiences a local maximum at or slightly after the bounce.Comment: 33 pages, 17 picture
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