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Abstract: (U)BVRI photometry of 27 mainly small () Trojans show that the previously reported size-spectral slope trend among Trojans and Hildas must be modified. The small-slope small-bodies gap present in previous works does not exist. This has also been noted by other recent reported observations. While the largest asteroids have slopes less than about 10% kÅ−1 the smallest asteroids have both small and large slopes. The maximum slope is about 15% kÅ−1 for all outer main belt groups (Cybeles, Hildas and Trojans). Combining observations from different authors reveal that these three groups have small asteroids (below 50 km) in the same slope range, while the large Trojans () have in general significantly steeper slopes than Hildas and Cybeles of similar size. The size-slope trend would favor organic materials as mainly responsible for the reflectance properties of the surfaces. [Copyright &y& Elsevier]

Rosetta observations of 67P/Churyumov‐Gerasimenko (67P) reveal that most changes occur in the fallback‐generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation and evolution. Here we present a self‐consistent model that thoroughly explains the activity and mass loss from Hapi's smooth terrains. Our model predicts the removal of dust via reradiated solar insolation localized within depression scarps that are substantially more ice rich than previously expected. We couple our model with numerous Rosetta observations to thoroughly capture the seasonal erosion of Hapi's smooth terrains, where local scarp retreat gradually removes the uppermost dusty mantle. As sublimation‐regolith interactions occur on rocky planets, comets, icy moons, and Kuiper belt objects, our coupled model and observations provide a foundation for future understanding of the myriad of sublimation‐carved worlds. Key Points: We report the discovery of transient, migrating depressions within the smooth terrains on comet 67PMigration is via uniform scarp retreat, which removes regolith completely from the nucleus and is driven by sublimating subsurface water iceWe develop a model that fully captures our own, and many previous, disparate observations, with implications for how comets seasonally erode [ABSTRACT FROM AUTHOR]

By using the Rosetta /OSIRIS-NAC data set taken in 2014 August, we focus on the neck region, called Hapi, located on 67P Churyumov–Gerasimenko's Northern hemisphere. The gravitational potential and slopes of Hapi, coupled with the geological unit identification and the boulder size–frequency distributions, support the interpretation that both taluses and gravitational accumulation deposits observable on Hapi are the result of multiple cliff collapses that occurred at different times. By contrast, the fine-particle deposits observable in the central part of the study area are made of aggregates coming from the Southern hemisphere and deposited during each perihelion passage. Both the consolidated terrains on the western part of Hapi, as well as the centrally aligned ridge made of boulder-like features, suggest that Hapi is in structural continuity with the onion-like structure of the main lobe of 67P. Despite the dusty blanket observable on Hapi, its terrains are characterized by water-ice-rich components that, once repeatedly and rapidly illuminated, sublimate, hence resulting in the strong jet activity observed in 2014 August. [ABSTRACT FROM AUTHOR]

Abstract The previously defined regions on the nucleus of comet 67P/Churyumov-Gerasimenko have been mapped back onto the 3D SHAP7 model of the nucleus (Preusker et al., 2017). The resulting regional definition is therefore self-consistent with boundaries that are well defined in 3 dimensions. The facets belonging to each region are provided as supplementary material. The shape model has then been used to assess inhomogeneity of nucleus surface morphology within individual regions. Several regions show diverse morphology. We propose sub-division of these regions into clearly identifiable units (sub-regions) and a comprehensive table is provided. The surface areas of each sub-region have been computed and statistics based on grouping of unit types are provided. The roughness of each region is also provided in a quantitative manner using a technique derived from computer graphics applications. The quantitative method supports the sub-region definition by showing that differences between sub-regions can be numerically justified. Highlights • Regions are defined upon the latest 3D shape model (SHAP7) of comet 67P/Churyumov-Gerasimenko. • The definition is provided in a publicly accessible shape file. • Sub-regions of similar properties are defined to support more detailed work. • Roughness calculations are performed to quantify differences between regions and sub-regions. [ABSTRACT FROM AUTHOR]

Between 2014 and 2016, ESA’s Rosetta OSIRIS cameras acquired multiple-filters images of the layered nucleus of comet 67P/Churyumov–Gerasimenko, ranging from ultraviolet to near-infrared wavelengths. No correlation between layers disposition and surface spectral variegation has been observed so far. This paper investigates possible spectral differences among decametre-thickness outcropping layers of the biggest lobe of the comet by means of OSIRIS image dataset. A two-classes maximum likelihood classification was applied on consolidated outcrops and relative deposits identified on post-perihelion multispectral images of the big lobe. We distinguished multispectral data on the basis of the structural elevation of the onion-shell Ellipsoidal Model of 67P. The spatial distribution of the two classes displays a clear dependence on the structural elevation, with the innermost class resulting over 50 per cent brighter than the outermost one. Consolidated cometary materials located at different structural levels are characterized by different brightness and revealed due to the selective removal of large volumes. This variegation can be attributed to a different texture of the outcrop surface and/or to a different content of refractory materials. [ABSTRACT FROM AUTHOR]

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard the European Space Agency's Rosetta spacecraft acquired images of comet 67P/Churyumov–Gerasimenko (67P) and its surrounding dust coma starting from May 2014 until September 2016. In this paper we present methods and results from analysis of OSIRIS images regarding the dust outflow in the innermost coma of 67P. The aim is to determine the global dust outflow behaviour and place constraints on physical processes affecting particles in the inner coma. We study the coma region right above the nucleus surface, spanning from the nucleus centre out to a distance of about 50 km comet centric distance (approximately 25 average comet radii). We primarily adopt an approach used by Thomas and Keller (1990) to study the dust outflow. We present the effects on azimuthally-averaged values of the dust reflectance of non-radial flow and non-point-source geometry, acceleration of dust particles, sublimation of icy dust particles after ejection from the surface, dust particle fragmentation, optical depth effects and the influence of gravitationally bound particles. All of these physical processes could modify the observed distribution of light scattered by the dust coma. In the image analysis, profiles of azimuthally averaged dust brightness as a function of impact parameter b (azimuthal average, “Ā-curve”) were fitted with a simple function that best fits the shape of our profile curves ( f ( b ; u , v , w , z ) = u / b v + w b + z ). The analytical fit parameters ( u, v, w, z ), which hold the key information about the dust outflow behaviour, were saved in a comprehensive database. Through statistical analysis of these information, we show that the spatial distribution of dust follows free-radial outflow behaviour (i.e. force-free radial outflow with constant velocity) beyond distances larger than ∼11.9 km from the comet centre, which corresponds to a relative distance of about 6 average comet radii from the comet centre. Hence, we conclude that beyond this distance, and on average, fragmentation and gravitationally bound particles are negligible processes in determining the optically scattered light distribution in the innermost coma. Closer to the nucleus we observe dust outflow behaviour that deviates from free-radial outflow. A comparison of our result profiles with numerical models using a Direct Simulation Monte Carlo (DSMC) approach with dust particle distributions calculated using a test particle approach has been used to demonstrate the influence of a complex shape and particle acceleration on the azimuthal average profiles. We demonstrate that, while other effects such as fragmentation or sublimation of dust particles cannot be ruled out, acceleration of the dust particles and effects arising from the shape of the irregular nucleus (non-point source geometry) are sufficient to explain the observed dust outflow behaviour from image data analysis. As a by-product of this work, we have calculated “Afρ” values for the 1/r regime. We found a peak in the coma activity in terms of Afρ (normalised to a phase angle of 90°) of ∼210 cm 20 days after perihelion. Furthermore, based on simplified models of particle motion within bound orbits, it is shown that limits on the total cross-sectional area of bound particles might be derived through further analysis. An example is given. [ABSTRACT FROM AUTHOR]

We report on the detection and characterization of more than 6300 polygons on the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, using images acquired by the OSIRIS camera onboard Rosetta between August 2014 and March 2015. They are found in consolidated terrains and grouped in localized networks. They are present at all latitudes (from North to South) and longitudes (head, neck, and body), sometimes on pit walls or following lineaments. About 1.5% of the observed surface is covered by polygons. Polygons have an homogeneous size across the nucleus, with 90% of them in the size range 1 – 5 m and a mean size of 3.0 ± 1.4 m. They show different morphologies, depending on the width and depth of their trough. They are found in networks with 3- or 4-crack intersection nodes. The polygons observed on 67P are consistent with thermal contraction crack polygons formed by the diurnal or seasonal temperature variations in a hard (MPa) and consolidated sintered layer of water ice, located a few centimeters below the surface. Our thermal analysis shows an evolution of thermal contraction crack polygons according to the local thermal environment, with more evolved polygons (i.e. deeper and larger troughs) where the temperature and the diurnal and seasonal temperature range are the highest. Thermal contraction crack polygons are young surface morphologies that probably formed after the injection of 67P in the inner solar system, typically 100,000 years ago, and could be as young as a few orbital periods, following the decreasing of its perihelion distance in 1959 from 2.7 to 1.3 a.u. Meter scale thermal contraction crack polygons should be common features on the nucleus of Jupiter family comets. [ABSTRACT FROM AUTHOR]

The ESA Rosetta mission has shown that Comet 67P/Churuymov–Gerasimenko is bi-lobed, has a high average porosity of around 70%, does not have internal cavities on size scales larger than 10 m, the lobes could have individual sets of onion shell-like layering, and the nucleus surface contains 100 m-scale cylindrical pits. It is currently debated whether these properties are consistent with high-velocity collisional evolution or if they necessarily are surviving signatures of low-velocity primordial accretion. We use an Eulerian hydrocode to study collisions between highly porous bodies of different sizes, material parameters and relative velocities with emphasis on 5–100 m/s to characterize the effects of collisions in terms of deformation, compaction, and heating. We find that accretion of 1 km cometesimals by 3 km nuclei at 13.5 m/s flattens and partially buries the cometesimal with  ∼ 1% reduction of the bulk porosity. This structure locally becomes more dense but the global effect of compaction is minor, suggesting that low-velocity accretion does not lead to a ‘bunch of grapes’ structure with large internal cavities but a more homogeneous interior, consistent with Rosetta findings. The mild local compaction associated with accretion is potentially the origin of the observed nucleus layering. In 2D axially symmetric impacts hit-and-stick collisions of similarly-sized nuclei are possible at velocities up to 30 m/s where deformation becomes severe. The bulk porosity is reduced significantly, even at 30–50 m/s relative velocity. To avoid hit-and-run collisions the impact angle must be less than 35°–45° from the surface normal at 10 m/s, and even smaller at higher velocities. Impact heating is insignificant. We find that the small cross section of the 67P neck may require a  ≤ 5 m/s impact, unless the cohesion exceeds 10 kPa. We conclude that bi-lobe nucleus formation is possible at velocities typically discussed in hierarchical growth scenarios. Impacts of a 7 m projectile at 100–500 m/s create a rimless cylindrical shaft with vertical walls, up to 50 m wide and 70 m deep. These shafts bear some resemblance with the pits on 67P, particularly if the depth-to-width ratio is reduced by nucleus erosion. Collisions between similarly-sized nuclei above 100 m/s lead to complete disintegration, and even small fragments suffer different degrees of compaction. Thus, we strongly doubt that 67P has been subjected to high-velocity collisions by projectiles larger than those that might have formed the pits, or is the fragment of a larger parent body. We suggest that the observed properties of 67P are more consistent with primordial accretion. [ABSTRACT FROM AUTHOR]

The Rosetta spacecraft has investigated comet 67P/Churyumov-Gerasimenko from large heliocentric distances to its perihelion passage and beyond. We trace the seasonal and diurnal evolution of the colors of the 67P nucleus, finding changes driven by sublimation and recondensation of water ice. The whole nucleus became relatively bluer near perihelion, as increasing activity removed the surface dust, implying that water ice is widespread underneath the surface. We identified large (1500 square meters) ice-rich patches appearing and then vanishing in about 10 days, indicating small-scale heterogeneities on the nucleus. Thin frosts sublimating in a few minutes are observed close to receding shadows, and rapid variations in color are seen on extended areas close to the terminator. These cyclic processes are widespread and lead to continuously, slightly varying surface properties. [ABSTRACT FROM AUTHOR]

Highly impaired individuals stand to benefit greatly from cutting-edge bionic technology, however concurrent functional deficits may complicate the adaptation of such technology. Here, we present a case in which a visually impaired individual with bilateral burn injury amputation was provided with a novel transradial neuromusculoskeletal prosthesis comprising skeletal attachment via osseointegration and implanted electrodes in nerves and muscles for control and sensory feedback. Difficulties maintaining implant hygiene and donning and doffing the prosthesis arose due to his contralateral amputation, ipsilateral eye loss, and contralateral impaired vision necessitating continuous adaptations to the electromechanical interface. Despite these setbacks, the participant still demonstrated improvements in functional outcomes and the ability to control the prosthesis in various limb positions using the implanted electrodes. Our results demonstrate the importance of a multidisciplinary, iterative, and patient-centered approach to making cutting-edge technology accessible to patients with high levels of impairment.

We present a summary of the campaign of remote observations that supported the European Space Agency's Rosetta mission. Telescopes across the globe (and in space) followed comet 67P/Churyumov-Gerasimenko from before Rosetta's arrival until nearly the end of the mission in September 2016. These provided essential data for mission planning, large-scale context information for the coma and tails beyond the spacecraft and a way to directly compare 67P with other comets. The observations revealed 67P to be a relatively 'well-behaved' comet, typical of Jupiter family comets and with activity patterns that repeat from orbit to orbit. Comparison between this large collection of telescopic observations and the in situ results from Rosetta will allow us to better understand comet coma chemistry and structure. This work is just beginning as the mission ends-in this paper, we present a summary of the ground-based observations and early results, and point to many questions that will be addressed in future studies.This article is part of the themed issue 'Cometary science after Rosetta'., (© 2017 The Author(s).)

The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by exposure to sunlight and other processes. While the localized changes suggest compositional or physical heterogeneity, their scale has not resulted in substantial alterations to the comet's landscape. This suggests that most of the major landforms were created early in the comet's current orbital configuration. They may even date from earlier if the comet had a larger volatile inventory, particularly of CO or CO 2 ices, or contained amorphous ice, which could have triggered activity at greater distances from the Sun., (Copyright © 2017, American Association for the Advancement of Science.)

The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes. Here we report that the comet's major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov-Gerasimenko is an accreted body of two distinct objects with 'onion-like' stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov-Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.

Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.

Images of comet 67P/Churyumov-Gerasimenko acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) imaging system onboard the European Space Agency's Rosetta spacecraft at scales of better than 0.8 meter per pixel show a wide variety of different structures and textures. The data show the importance of airfall, surface dust transport, mass wasting, and insolation weathering for cometary surface evolution, and they offer some support for subsurface fluidization models and mass loss through the ejection of large chunks of material., (Copyright © 2015, American Association for the Advancement of Science.)

Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck. The nucleus has a bulk density less than half that of water. Activity at a distance from the Sun of >3 astronomical units is predominantly from the neck, where jets have been seen consistently. The nucleus rotates about the principal axis of momentum. The surface morphology suggests that the removal of larger volumes of material, possibly via explosive release of subsurface pressure or via creation of overhangs by sublimation, may be a major mass loss process. The shape raises the question of whether the two lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss., (Copyright © 2015, American Association for the Advancement of Science.)

Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency's Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10(-10) to 10(-7) kilograms, and 48 grains of mass 10(-5) to 10(-2) kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails., (Copyright © 2015, American Association for the Advancement of Science.)

Quantitative determination of staphylococcal protein A in plasma is often hampered by the interaction between protein A and immunoglobulins. In human plasma, these interactions may not only involve the non-immune binding to the Fc or Fab regions of Ig but also antigen/antibody interaction by specific antibodies directed against protein A. In this paper we describe a method which can be used to quantitate nanogram amounts of protein A in the presence of human plasma. The ELISA used for the quantification of protein A is based on a double antibody solid-phase assay utilizing chicken anti-protein A as both capture and detector antibody. Protein A may be measured down to 5 ng/ml in plasma and 0.5 ng/ml in buffer. The plasma samples were heat-inactivated before analysis and this eliminated interference in the assay caused by interaction of protein A with an excess of immunoglobulins. This assay provides a reliable and convenient method for the detection and quantitation of soluble protein A in human plasma.

An excess mortality from chronic cardio-cerebrovascular diseases among dynamite workers has recently been reported from two Swedish explosives industries. This study summarizes the exposure situation with regard to nitroglycol and nitroglycerine during the last two decades in one of these factories. The manufacturing process is described as well as the sampling and analytic procedures. The mean 8-hour TWA concentrations of nitrate esters for different job types during three seven-year periods 1958-1978 have been calculated from a large number of simi-annually measured short-time samples. The concentrations are estimated to have been in the range of 0.2 - 1.1 mg/m3, with the highest levels for cartridge fillers and mix house workers. The representativeness of short-time samples was found to be comparatively good in relation to 8-1/2 hour personal air sampling. The presented exposure calculations could be used for international comparison and dose-response discussions in future epidemiological studies on chronic effects of nitrate esters.