Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions, we were able to constrain the typical values of the cYORP parameter as between 0.05 and 0.6.Comment: Accepted for publication in A&A, January 15, 201

The Hybrid SPECT/CT as an Additional Lymphatic Mapping Tool in Patients with Breast Cancer

Background Conventional lymphoscintigraphy does not always define the exact anatomic location of a sentinel node. The lymphatic drainage pattern may be unusual or may not be shown at all. The recently introduced hybrid SPECT/CT imaging could help overcome these difficulties. SPECT is a tomographic version of conventional lymphoscintigraphy and the images have better contrast and resolution. When fused with the anatomical details provided by CT into one image, a meaningful surgical ‘‘roadmap’’ can be created. So far, there is little literature on the use of hybrid SPECT/CT in lymphatic mapping in patients with breast cancer. The purpose of this review was to report on these publications, including our own experience, focusing on patient selection, SPECT/CT settings, anatomic localization, and the detection of additional sentinel nodes. Methods The majority of investigators did not formulate indications for additional SPECT/CT after conventional imaging but scanned all patients eligible for sentinel node biopsy. The SPECT/CT settings used in the studies of this review were mostly similar, but the methods used for conventional imaging were more variable. Results All studies demonstrated an improved anatomical localization by performing additional SPECT/CT; sentinel nodes outside the axilla or nodes close to the injection sit

Imaging with non-FDG PET tracers: outlook for current clinical applications

Apart from the historical and clinical relevance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG), various other new tracers are gaining a remarkable place in functional imaging. Their contribution to clinical decision-making is irreplaceable in several disciplines. In this brief review we aimed to describe the main non-FDG PET tracers based on their clinical relevance and application for patient care

Low-dose unenhanced CT for IV contrast bolus timing: is it reliable to assess hepatic steatosis?

RATIONALE AND OBJECTIVES: To determine whether an unenhanced low-dose image acquired during automated contrast bolus timing can be used to assess hepatic steatosis. MATERIALS AND METHODS: Fifty subjects (29 male, 21 female; 26-92 years; mean body mass index (BMI; 26.9) with abdominal multiphasic computed tomography were included. Abdominal diameters and circumferences were derived from anteroposterior and lateral scout radiographs. Hepatic attenuation (HA) was measured on unenhanced low-dose images (120 kV; 40 mA; 0.5 seconds' rotation time) and corresponding unenhanced standard-dose images (120 kV, z-axis automatic tube current modulation, noise index 11.5). Noise estimates were measured in surrounding air. Pearson correlation was calculated between abdominal circumference and BMI. Mean HA assessed on low-dose images and standard-dose images was compared using a paired Student's t-test and Bland Altman plots. RESULTS: Abdominal circumference (mean, 142.8cm) correlated well with BMI (r = 0.83). No significant difference was found for HA on low-dose images (mean +57.7 HU) compared to HA on standard-dose images (+56.0 HU) (P = .077). Image noise (+11.5 HU) was significantly higher on low-dose images compared to image noise (+8.1 HU) on standard-dose images (P < .05). For HA mean difference comparing low- and standard-dose images was -1.7 HU (limits of agreement: -14.6, 11.2). CONCLUSION: In all subjects, hepatic attenuation can be correctly assessed on unenhanced low-dose images

Optimization of heat treatment of steels

12.00; Translated from Russian (Sb. Ved. Pr. Vys. Sk. Banske Ostrave 1982 v. 28(1) p. 11-20)SIGLEAvailable from British Library Lending Division - LD:9023.19(VR--2446)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Fragmentation of transient water anions following low-energy electron capture by H2O/D2O

Dissociative electron attachment (DEA) to water in the gaseous phase has been studied using two different crossed electron–molecule beam apparatus. Ion yields for the formation of the three fragments H-, O- and OH- were measured as a function of the incident electron energy. The kinetic energies of the fragment ions were measured and compared with the values derived from ab initio calculations to provide information on the energy partitioning in the fragmentation process. Isotope and temperature effects on the attachment process are discussed and the production of OH- via DEA is confirmed

Ligaments and plicae of the elbow: Normal MR imaging variability in 60 asymptomatic subjects

PURPOSE: To prospectively evaluate the normal variability of ligaments, plicae, and the posterior capitellum on conventional magnetic resonance (MR) images of the elbow in asymptomatic volunteers. MATERIALS AND METHODS: The study was approved by the institutional ethics board, and informed consent was obtained from all subjects. MR imaging was performed at 1.5 T in 60 asymptomatic volunteers (30 women, 30 men; age range, 22-51 years; median age, 32.8 years) by using the following five pulse sequences: transverse T1-weighted spin-echo, sagittal T2-weighted fast spin-echo, coronal fast spin-echo short-inversion-time inversion recovery, transverse intermediate-weighted with fat saturation, and coronal three-dimensional water-excitation true fast imaging with steady-state precession. The visibility (completely visible over the entire course, partially visible, or not visible) and signal intensity characteristics (hypointense or hyperintense to muscle, homogeneous signal intensity vs striation) of the elbow ligaments and plicae were evaluated by three independent readers. The presence of pseudodefects at the posterior capitellum was determined. The dimensions of all structures were measured by two independent readers. RESULTS: The anterior ulnar collateral ligament (UCL) and radial collateral ligament (RCL) were visible over their entire course in all 60 subjects (100%). The posterior UCL, lateral UCL, and annular ligament (AL) were completely visible in 58 (97%), 51 (85%), and 59 (98%) of the 60 subjects, respectively, and partially visible in the remaining subjects. Increased signal intensity with fluid-sensitive sequences was found in the anterior UCL in nine of the 60 subjects (15%), posterior UCL in four subjects (7%), RCL in one subject (2%), lateral UCL in six subjects (10%), and AL in one subject (2%). The median thickness and 90th percentile were 2.5 and 3.5 mm, respectively, for the anterior UCL, 1.0 and 1.7 mm for the posterior UCL, 1.9 and 2.8 mm for the RCL, 2.3 and 3.8 mm for the lateral UCL, and 1.0 and 1.3 mm for the AL. A posterolateral plica (median dimension, 4.3 × 1.9 × 3.9 mm) was found in 59 of the 60 subjects (98%), whereas a posterior plica (median dimension, 1.8 × 1.4 mm) could be detected in only 20 (33%). A pseudodefect of the capitellum was noted in 51 of the 60 subjects (85%). CONCLUSION: The elbow ligaments and the posterolateral plica are consistently visible on conventional MR images of asymptomatic subjects. Most normal ligaments are thinner than 4 mm, and most plicae are thinner than 3 mm