Reproducing the UVJ Color Distribution of Star-forming Galaxies at 0.5 < z < 2.5 with a Geometric Model of Dust Attenuation

We analyze the distribution of rest-frame U − V and V − J colors for star-forming galaxies at 0.5 < z < 2.5. Using stellar population synthesis, stochastic star formation histories, and a simple prescription for the dust attenuation that accounts for the shape and inclination of galaxies, we construct a model for the distribution of galaxy colors. With only two free parameters, this model is able to reproduce the observed galaxy colors as a function of redshift and stellar mass remarkably well. Our analysis suggests that the wide range of dust attenuation values measured for star-forming galaxies at a given redshift and stellar mass is almost entirely due to the effect of inclination; if all galaxies at a given stellar mass were observed edge-on, they would show very similar dust attenuation. This result has important implications for the interpretation of dust attenuation measurements, the treatment of UV and IR luminosity, and the comparison between numerical simulations and observations.

Adrenal wash-out CT: moderate diagnostic value in distinguishing benign from malignant adrenal masses

Objective: Reliable results of wash-out CT in the diagnostic workup of adrenal incidentalomas are scarce. Thus, we evaluated the diagnostic accuracy of delayed wash-out CT and determined thresholds to accurately differentiate adrenal masses. Design: Retrospective, single-center cohort study including 216 patients with 252 adrenal lesions who underwent delayed wash-out CT. Definitive diagnoses based on histopathology (n=92) or comprehensive follow-up. Methods: Size, average attenuation values of the adrenal lesions in all CT scan phases, absolute and relative percentage washout (APW/RPW) were determined by an expert radiologist blinded for clinical data. Adrenal lesions with unenhanced attenuation values >10HU built a subgroup (n=142). Diagnostic accuracy were calculated. Results: The study group consisted of 171 adenomas, 32 other benign tumors, 11 pheochromocytomas, 9 adrenocortical carcinomas and 29 other malignant tumors. All (potentially) malignant and 46% of benign lesions showed unenhanced attenuation values >10HU. In this most relevant subgroup, the established thresholds of 60% for APW and 40% for RPW misclassified 35.9% and 35.2% of masses, respectively. When we applied optimized cutoffs (APW>83%; RPW>58%) and excluded pheochromocytomas, we missed only 1 malignant tumor by APW and none by RPW. However, only 11% and 15% of benign tumors were correctly identified. Conclusions: Washout CT with the established thresholds for APW und RPW is insufficient to reliably diagnose adrenal masses. Using the proposed cutoff of 58% for RPW, malignant tumors will be correctly identified, but the added value is limited, namely 15% of patients with benign tumors can be prevented from additional imaging or even unnecessary surgery.

Development of a new rain attenuation model for tropical location

This study proposes a new rain attenuation prediction model (RAM) based on the rain cell concept for tropical locations. The new model addresses the research gap in the international telecommunications union (ITU) model. Results obtained show that the proposed RAM predicted the possibility of signal across seven (7) out of thirteen (13) stations monitored. The predicted attenuation values were 18.3427 dB, 18.8106 dB, 18.3921 dB, 13.8062 dB, 20.8803 dB, 9.4519 dB, and 19.6018 dB for Jalingo, Jos, Makurdi, Mubi, Otukpo, Sokoto, and Abuja respectively. However, the RAM predicted outage across six stations with predicted attenuation values of 31.7040 dB, 26.8302 dB, 28.6635 dB, 29.6562 dB, 28.8827 dB, and 30.0614 dB for Akwa-Ibom, Benin, Donga, Port-Harcourt, Owerri, and Aba respectively. The proposed RAM hence suggests an additional Ku-band spot beam power of at least 331.97 watts for Nigeria's Nigerian communication satellite-1 (NIGCOMSAT-1R) Ku-band transponder to overcome the predicted attenuation across the six stations which recorded signal outage. The results from this study can be used by network engineers for the implementation of fade mitigation techniques (FMTs) such as site diversity and power control to aid telecommunication networks anticipate changes and allocate resources accordingly.

“Black ring-shaped burn” in button battery ingestion is not a burn — Comparison with charring using spectral CT

Objectives: To compare “black ring-shaped burn” (BRSB) and charring using spectral computed tomography (CT). Methods: Spectral CT was performed using chicken pectoralis minor muscle, processed in three ways and unprocessed as a control: a) BRSB generated by bringing the negative pole surface of a 3 V button battery (BB) into contact with the muscle; b) BRSB caused by a 1.5 V BB; c) charring caused by broiling; and d) control. Attenuation values were compared between BRSB and charring. Muscles were formalin-fixed and stained with Perls’ Prussian blue. Results: Attenuation values from polychromatic 120-kVp images were significantly higher for BRSBs than for charring. In the spectral Hounsfield unit curve, attenuation values for BRSBs were higher for lower energy. Histopathologically, BRSBs stained positively with Perls’ Prussian blue. Conclusions: This study using spectral CT revealed that BRSB contains metal and confirmed the presence of Fe3+ histopathologically. BRSB differs from charring due to burns. Advances in knowledge: The exact composition of BRSB remains unclear, but this report is the first to show that BRSB differs from charring using spectral CT. Clarification of the composition of BRSB is expected to facilitate the development of more effective BRSB removal therapy.

Potential of Gold Nanoparticles for Noninvasive Imaging and Therapy for Vascular Inflammation

Purpose Macrophages contribute to the progression of vascular inflammation, making them useful targets for imaging and treatment of vascular diseases. Gold nanoparticles (GNPs) are useful as computed tomography (CT) contrast agents and light absorbers in photothermal therapy. In this study, we aimed to assess the viability of macrophages incubated with GNPs after near-infrared (NIR) laser light exposure and to evaluate the utility of intravenously injected GNPs for in vivo imaging of vascular inflammation in mice using micro-CT. Procedures Mouse macrophage cells (RAW 264.7) were incubated with GNPs and assessed for GNP cellular uptake and cell viability before and after exposure to NIR laser light. For in vivo imaging, macrophage-rich atherosclerotic lesions were induced by carotid ligation in hyperlipidemic and diabetic FVB mice (n = 9). Abdominal aortic aneurysms (AAAs) were created by angiotensin II infusion in ApoE-deficient mice (n = 9). These mice were scanned with a micro-CT imaging system before and after the intravenous injection of GNPs. Results The CT attenuation values of macrophages incubated with GNPs were significantly higher than those of cells incubated without GNPs (p < 0.04). Macrophages incubated with and without GNPs showed similar viability. The viability of macrophages incubated with GNPs (100 μg/ml or 200 μg/ml) was decreased by high-intensity NIR laser exposure but not by low-intensity NIR laser exposure. In vivo CT images showed higher CT attenuation values in diseased carotid arteries than in non-diseased contralateral arteries, although the difference was not statistically significant. The CT attenuation values of the perivascular area in AAAs of mice injected with GNPs were significantly higher than those of mice without injection (p = 0.0001). Conclusions Macrophages with GNPs had reduced viability upon NIR laser exposure. GNPs intravenously injected into mice accumulated in sites of vascular inflammation, allowing detection of carotid atherosclerosis and AAAs in CT imaging. Thus, GNPs have potential as multifunctional biologically compatible particles for the detection and therapy of vascular inflammation.

Aerodynamic and acoustical effects caused by placing two prefabricated duct silencers in series

It once was not uncommon to find ductborne noise control designs and recommendations that would attempt to provide high sound attenuation values, especially for problematic lower frequencies, by using a pair of prefabricated duct silencers in series with one another, sometimes immediately adjacent but typically separated by some distance. Similarly, heating, ventilating, and air-conditioning (HVAC) duct silencers are occasionally required to accommodate fire dampers or access sections that effectively break up the silencer along its length, creating an empty gap between the noise-attenuating internal elements. Typical published performance characteristics of prefabricated duct silencers do not include effects from the use of additional silencers nearby and little information is available in common duct design and application literature. This paper will present information from a series of tests of various silencers in different configurations and spacings in an aero-acoustic test facility that will help describe the effects on insertion loss, generated noise, and pressure drop.

Determination of Gallstone Composition using Dual-Energy Computed Tomography: An Ex-vivo Study

Purpose: This study aimed to investigate whether ex-vivo gallstones are distinguishable by type using dualenergy computed tomography (DECT).Materials and Methods: A total of 124 gallstones from 65 patients with acute or chronic calculous cholecystitis were evaluated using DECT. The extracted gallstones were submerged in distilled water in an acrylic container and scanned at tube voltages of 80/140 kVp and 100/140 kVp. The images were grouped into three sets: 80, 100, and 140 kVp. Qualitative analyses of DECT sensitivity and attenuation patterns in each image set were performed, and quantitative analyses included calculation of mean attenuation values and measurement of the gallstone size. Semi-quantitative Fourier transform infrared (FTIR) spectroscopy was used as the reference standard to confirm the chemical composition of the gallstones.Results: FTIR spectroscopy identified 66 gallstones from 33 patients as cholesterol gallstones and 58 gallstones from 32 patients as pigment gallstones. Qualitative analysis indicated that DECT sensitivity for cholesterol gallstones was greatest at 80 kVp. Most cholesterol gallstones (79%) showed low attenuation at 80 kVp and high attenuation (65%) at 140 kVp. Pigment gallstones demonstrated high attenuation at all image sets. On quantitative analysis, the mean calculated attenuation values of cholesterol gallstones were -17 ± 50 Hounsfield Units (HU), -5.1 ± 43 HU, and 19.2 ± 39 HU at 80, 100, and 140 kVp, respectively, and 342 ± 173 HU, 286 ± 116 HU, and 195 ± 91 HU, respectively, for pigment stones.Conclusions: Ex-vivo gallstones were distinguishable as cholesterol or pigment gallstones by using DECT.

Application of low-dose CT combined with model-based iterative reconstruction algorithm in oncologic patients during follow-up: dose reduction and image quality

Objectives: To compare image quality and radiation dose of CT images reconstructed with model-based iterative reconstruction (MBIR) and hybrid-iterative (HIR) algorithm in oncologic patients. Methods: 125 oncologic patients underwent both contrast-enhanced low- (100 kV), and standard (120 kV) dose CT, were enrolled. Image quality was assessed by using a 4-point Likert scale. CT attenuation values, expressed in Hounsfield unit (HU), were recorded within a regions of interest (ROI) of liver, spleen, paraspinal muscle, aortic lumen, and subcutaneous fat tissue. Image noise, expressed as standard deviation (SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated. Radiation dose were analyzed. Paired Student’s t-test was used to compare all continuous variables. Results: The overall median score assessed as image quality for CT images with the MBIR algorithm was significantly higher in comparison with HIR [4 (range 3–4) vs 3 (3-4), p = 0.017]. CT attenuation values and SD were significantly higher and lower, respectively, in all anatomic districts in images reconstructed with MBIR in comparison with HIR ones (all p < 0.001). SNR and CNR values were higher in CT images reconstructed with MBIR, reaching a significant difference in all districts (all p < 0.001). Radiation dose were significantly lower in the MBIR group compared with the HIR group (p < 0.001). Conclusions: MBIR combined with low-kV setting allows an important dose reduction in whole-body CT imaging, reaching a better image quality both qualitatively and quantitatively. Advances in knowledge: MBIR with low-dose approach allows a reduction of dose exposure, maintaining high image quality, especially in patients which deserve a longlasting follow-up.

Spectral Relative Attenuation of Solar Radiation through a Skylight Focused on Preventive Conservation: Museo De L’almoina in Valencia (Spain) Case Study

The aim of the present study was to evaluate the relative attenuation of VIS, UV and NIR solar radiation through a large pond skylight into the interior of the l’Almoina Archaeological Museum (Valencia, Spain), and to determine how relative attenuation varied throughout the year and time of day. Measurements were taken at 9:00 a.m., 12:00 p.m. and 3:00 p.m. during July 2019 and January 2020. Relative attenuation values were obtained from the measurement of spectral irradiance in the exterior and at different points in the interior by means of two Ocean Optics spectrometers: HR4000CG-UV-NIR for VIS (400–700 nm) and NIR (700–1000 nm) bands, and FLAME-S-UV-VIS for UV-A (280–315 nm) and UV-A (315–400 nm) bands. The central points of the skylight had relative attenuation at 520 nm, reaching a value of 50% in summer at noon and 38% in the afternoon. At noon in winter, there were two relative attenuation peaks above 33% at 520 nm and at 900 nm. For mean relative attenuation, in the UVB range, the highest relative attenuation (20%) was inside the ruins in the morning in both summer and winter, and the UVA band relative attenuation was quite constant throughout the museum, but lower than that of the UVB band, in the range 0–3%.