Book Reviews

Reviews of the following books: Women of Maine by Lee Agger; Nathaniel Hawthorne in His Times by James R. Mellow; In English Ways: The Movement of Societies and the Transferal of English Local Law and Customs to Massachusetts Bay in the Seventeenth Century by David Grayson Allen

Teledermatology in low-resource settings: the MSF experience with a multilingual tele-experise platform

Introduction: In 2010, Médecins Sans Frontières (MSF) launched a tele-expertise system to improve the access to specialized clinical support for its field health workers. Among medical specialties, dermatology is the second most commonly requested type of tele-expertise. The aim of the present study was to review all MSF teledermatology cases in the first 4 years of operation. Our hypothesis was that the review would enable the identification of key areas for improvement in the current MSF teledermatology system. Methods: We carried out a retrospective analysis of all dermatology cases referred by MSF field doctors through the MSF platform from April 2010 until February 2014. We conducted a quantitative and qualitative analysis based on a survey sent to all referrers and specialists involved in these cases. Results: A total of 65 clinical cases were recorded by the system and 26 experts were involved in case management. The median delay in providing the first specialist response was 10.2 h (IQR 3.7–21.1). The median delay in allocating a new case was 0.96 h (IQR 0.26–3.05). The three main countries of case origin were South Sudan (29%), Ethiopia (12%), and Democratic Republic of Congo (10%). The most common topics treated were infectious diseases (46%), inflammatory diseases (25%), and genetic diseases (14%). One-third of users completed the survey. The two main issues raised by specialists and/or referrers were the lack of feedback about patient follow-up and the insufficient quality of clinical details and information supplied by referrers. Discussion: The system clearly delivered a useful service to referrers because the workload rose steadily during the 4-year study period. Nonetheless, user surveys and retrospective analysis suggest that the MSF teledermatology system can be improved by providing guidance on best practice, using pre-filled referral forms, following-up the cases after teleconsultation, and establishing standards for clinical photography

Noble gas geochemistry of fluid inclusions in South African diamonds: implications for the origin of diamond-forming fluids

Fibrous diamond growth zones often contain abundant high-density fluid (HDF) inclusions and these provide the most direct information on diamond-forming fluids. Noble gases are incompatible elements and particularly useful in evaluating large-scale mantle processes. This study further constrains the evolution and origin of the HDFs by combining noble gas systematics with δ13C, N concentrations, and fluid inclusion compositions for 21 individual growth zones in 13 diamonds from the Finsch (n = 3), DeBeers Pool (n = 7), and Koffiefontein (n = 3) mines on the Kaapvaal Craton. C isotope compositions range from −2.8 to −8.6‰ and N contents vary between 268 and 867 at.ppm, except for one diamond with contents of <30 at.ppm N. Nine of the thirteen studied diamonds contained saline HDF inclusions, but the other four diamonds had carbonatitic or silicic HDF inclusions. Carbonatitic and silicic HDFs yielded low He concentrations, R/Ra (3He/4Hesample/3He/4Heair) values of 3.2–6.7, and low 40Ar/36Ar ratios of 390–1940. Noble gas characteristics of carbonatitic-silicic HDFs appear consistent with a subducted sediment origin and interaction with eclogite. Saline HDFs are characterised by high He concentrations, with R/Ra mostly between 3.9 and 5.7, and a wide range in 40Ar/36Ar ratios (389–30,200). The saline HDFs likely originated from subducted oceanic crust with low He but moderate Ar contents. Subsequent interaction of these saline HDFs with mantle peridotite could explain the increase in He concentrations and mantle-like He isotope composition, with the range in low to high 40Ar/36Ar ratios dependent on the initial 36Ar content and extent of lithosphere interaction. The observed negative correlation between 4He contents and R/Ra values in saline HDFs indicates significant in situ radiogenic 4He production

On the Origin of Hyper-Velocity Stars Near Sagittarius A*

We present our investigation into the origins of high- and hyper-velocity stars around the Milky Way by exploring Gaia data. We begin by establishing a working set of criteria for a star to even be considered as a potential hyper-velocity star, which we defined chronologically as: if the uncertainty in parallax is acceptably low; if the star has above average total velocity for its home set; and finally if the star has a velocity that is mostly radial we investigate it further. We also discuss the complications encountered trying to identify candidate stars. Finally, we perform a time-reversing procedure to trace our final set of stars back to where they may have originated. We found a large number of candidate stars in our initial broad range search, but by enforcing stricter constraints we found a final sample of 1,158 potential hyper-velocity stars. This set displayed zero stars passing close enough to Sagittarius A* to have been thrown out or boosted to their current velocities. However, by selecting hyper-velocity stars with little proper motion in right ascension and declination, we discovered five stars which may have passed close enough to Sagittarius A* to have had their orbits significantly altered. A detailed analysis of the trajectories of those stars was performed, resulting in one star that may have originated from a binary system that had a close encounter with Sagittarius A*. We propose a potential binary partner in some of the known stars orbiting Sagittarius A* with similar periapsis

High Temperature Validation of a Line Heat Source Technique for In-Pile Thermal Conductivity Determination

In-pile instrumentation is critical for advancing operations and materials discovery in the nuclear industry. Ensuring optimal performance of sensors in high temperatures is the first step in demonstrating their viability in the harsh in-pile environment. This work demonstrates the high temperature capabilities of a line heat source and measurement technique previously shown to extract thermal conductivity of nuclear fuel sized samples within a laboratory environment at room temperature. This method uses a hybrid AC/DC measurement technique to obtain rapid measurements of the temperature dependent voltage change of a heater wire, which also acts as a resistance thermometer. Once the temperature profile of the heating element is extracted it is matched to a multilayered analytical model to determine the thermal conductivity of the sample. Measurements are conducted over a range of temperatures to extract the thermal conductivity as a function of temperature for 10 mm diameter 6061 aluminum samples. Each measurement had a coefficient of correlation (R2) value higher than 0.995 when matched to its corresponding analytical model. The thermal diffusivity values for each temperature are also identified and reported. Microstructure analysis was also conducted to further characterize the material measured

Hydrogen Motion in Magnesium Hydride by NMR

In coarse-grained MgH2, the diffusive motion of hydrogen remains too slow (<10^5 hops s^−1) to narrow the H NMR line up to 400 °C. Slow-motion dipolar relaxation time T1D measurements reveal the motion, with hopping rate ωH from 0.1 to 430 s^−1 over the range of 260 to 400 °C, the first direct measurement of H hopping in MgH2. The ωH data are described by an activation energy of 1.72 eV (166 kJ/mol) and attempt frequency of 2.5 × 10^15 s^−1. In ball-milled MgH2 with 0.5 mol % added Nb2O5 catalyst, line-narrowing is evident already at 50 °C. The line shape shows distinct broad and narrow components corresponding to immobile and mobile H, respectively. The fraction of mobile H grows continuously with temperature, reaching ∼30% at 400 °C. This demonstrates that this material’s superior reaction kinetics are due to an increased rate of H motion, in addition to the shorter diffusion paths from ball-milling. In ball-milled MgH2 without additives, the line-narrowed component is weaker and is due, at least in part, to trapped H2 gas. The spin−lattice relaxation rates T1^−1 of all materials are compared, with ball-milling markedly increasing T1^−1. The weak temperature dependence of T1^−1 suggests a mechanism with paramagnetic relaxation centers arising from the mechanical milling

Variation in the carotid bifurcation geometry of young versus older adults: Implications for geometric risk of atherosclerosis

Background and Purpose - Retrospective analysis of clinical data has demonstrated major variations in carotid bifurcation geometry, in support of the notion that an individual\u27s vascular anatomy or local hemodynamics may influence the development of atherosclerosis. On the other hand, anecdotal evidence suggests that vessel geometry is more homogenous in youth, which would tend to undermine this geometric risk hypothesis. The purpose of our study was to test whether the latter is indeed the case. Methods - Cross-sectional images of the carotid bifurcations of 25 young adults (24±4 years) and a control group of 25 older subjects (63±10 years) were acquired via MRI. Robust and objective techniques were developed to automatically characterize the 3D geometry of the bifurcation and the relative dimensions of the internal, external, and common carotid arteries (ICA, ECA, and CCA, respectively). Results - Young vessels exhibited significantly less interindividual variation in the following geometric parameters: bifurcation angle (48.5±6.3° versus 63.6±15.4°); ICA angle (21.6±6.7° versus 29.2±11.3°); CCA tortuosity (0.010±0.003 versus 0.014±0.011); ICA tortuosity (0.025±0.013 versus 0.086±0.105); ECA/CCA diameter ratio (0.81±0.06 versus 0.75±0.13), ICA/CCA (0.81 ±0.06 versus 0.77±0.12) diameter ratio, and bifurcation area ratio (1.32±0.15 versus 1.19±0.35). Conclusions - The finding of more modest interindividual variations in young adults suggests that, if there is a geometric risk for atherosclerosis, its early detection may prove challenging. Taken together with the major interindividual variations seen in older vessels, it suggests a more complex interrelationship between vascular geometry, local hemodynamics, vascular aging, and atherosclerosis, the elucidation of which now calls for prospective studies. © 2005 American Heart Association, Inc

Chaos, Consternation and CALIPSO Calibration: New Strategies for Calibrating the CALIOP 1064 nm Channel

The very low signal-to-noise ratios of the 1064 nm CALIOP molecular backscatter signal make it effectively impossible to employ the "clear air" normalization technique typically used to calibrate elastic back-scatter lidars. The CALIPSO mission has thus chosen to cross-calibrate their 1064 nm measurements with respect to the 532 nm data using the two-wavelength backscatter from cirrus clouds. In this paper we discuss several known issues in the version 3 CALIOP 1064 nm calibration procedure, and describe the strategies that will be employed in the version 4 data release to surmount these problems