Indicators of the Anthropocene: is there a case for conservation?

The Earth's atmosphere, biosphere and lithosphere are increasingly being modified by human activity. Given this anthropogenic influence on the natural environment, the case for recognizing an Anthropocene Epoch has recently been made and there is ongoing debate as to whether, and how, to formally characterize and define such an epoch. As a contribution to this debate, this article explores whether or not the landscapes, deposits, landforms and key marker horizons that may be used to characterize and define an Anthropocene Epoch could, and should, be identified and conserved in the same manner as other parts of the geological succession. Anthropogenic features pose a conservation challenge, however, as they often cross cut existing conservation frameworks which tend to focus on the natural, historic or cultural environment. Developing a coherent approach to the conservation of the indicators of an Anthropocene Epoch would, therefore, require an integrated system of describing, auditing and designating features for conservation. A major benefit of such an approach would be the opportunities for interdisciplinary collaboration between the wide range of researchers interested or involved in studying and conserving the record of anthropogenic activity

Probing Light Atoms at Sub-nanometer Resolution: Realization of Scanning Transmission Electron Microscope Holography

Atomic resolution imaging in transmission electron microscopy (TEM) and scanning TEM (STEM) of light elements in electron-transparent materials has long been a challenge. Biomolecular materials, for example, are rapidly altered when illuminated with electrons. These issues have driven the development of TEM and STEM techniques that enable the structural analysis of electron beam-sensitive and weakly scattering nano-materials. Here, we demonstrate such a technique, STEM holography, capable of absolute phase and amplitude object wave measurement with respect to a vacuum reference wave. We use an amplitude-dividing nanofabricated grating to prepare multiple spatially separated electron diffraction probe beams focused at the sample plane, such that one beam transmits through the specimen while the others pass through vacuum. We raster-scan the diffracted probes over the region of interest. We configure the post specimen imaging system of the microscope to diffraction mode, overlapping the probes to form an interference pattern at the detector. Using a fast-readout, direct electron detector, we record and analyze the interference fringes at each position in a 2D raster scan to reconstruct the complex transfer function of the specimen, t(x). We apply this technique to image a standard target specimen consisting of gold nanoparticles on a thin amorphous carbon substrate, and demonstrate 2.4 angstrom resolution phase images. We find that STEM holography offers higher phase-contrast of the amorphous material while maintaining Au atomic lattice resolution when compared with high angle annular dark field STEM.Comment: 9 pages, 5 figures in main text, 1 supplemental figure in the appendi

Deep dielectric charging of regolith within the Moon\u27s permanently shadowed regions

Abstract Energetic charged particles, such as galactic cosmic rays (GCRs) and solar energetic particles (SEPs), can penetrate deep within the lunar surface, resulting in deep dielectric charging. This charging process depends on the GCR and SEP currents, as well as on the regolith\u27s electrical conductivity and permittivity. In permanently shadowed regions (PSRs) near the lunar poles, the discharging timescales are on the order of a lunation (∼20 days). We present the first predictions for deep dielectric charging of lunar regolith. To estimate the resulting subsurface electric fields, we develop a data-driven, one-dimensional, time-dependent model. For model inputs, we use GCR data from the Cosmic Ray Telescope for the Effects of Radiation on board the Lunar Reconnaissance Orbiter and SEP data from the Electron, Proton, and Alpha Monitor on the Advanced Composition Explorer. We find that during the recent solar minimum, GCRs create persistent electric fields up to ∼700 V/m. We also find that large SEP events create transient but strong electric fields (≥106 V/m) that may induce dielectric breakdown. Such breakdown would likely result in significant modifications to the physical and chemical properties of the lunar regolith within PSRs. Key Points Energetic charged particles deep dielectrically charge the lunar regolithWe model the resulting subsurface electric fieldsThe electric fields may be great enough to induce dielectric breakdown

Interpretable and efficient contrast in scanning transmission electron microscopy with a diffraction grating beamsplitter

Efficient imaging of biomolecules, 2D materials and electromagnetic fields depends on retrieval of the phase of transmitted electrons. We demonstrate a method to measure phase in a scanning transmission electron microscope using a nanofabricated diffraction grating to produce multiple probe beams. The measured phase is more interpretable than phase-contrast scanning transmission electron microscopy techniques without an off-axis reference wave, and the resolution could surpass that of off-axis electron holography. We apply the technique to image nanoparticles, carbon sub- strates and electric fields. The contrast observed in experiments agrees well with contrast predicted in simulations

Non-histopathological parameters associated with upgrade of breast tumours yielding a core biopsy report of histological grade 2 ductal no special type to grade 3 on excision

Purpose: The aim of the study was to identify clinical, radiological and immuno-histochemical factors that may help predict upgrade of invasive ductal cancers of no special type (IDC-NST) with a core biopsy grade of 2 to grade 3 on final histology.Methods: A prospectively maintained database of ultrasound visible solid masses was used to identify lesions yielding a core biopsy result of IDC-NST grade 2 who underwent immediate surgery yielding a grade 2 or grade 3 tumour. Associations were sought between the source of patient (screening/symptomatic), core biopsy receptor status and imaging findings and the grade of the excision specimen tumour. Statistical analysis, which included the chi-squared test, ROC curves and Cox regression analysis, was used to compare upgrade vs no upgrade for each factor.Results: 463 IDC-NST breast cancers of core biopsy grade 2 gave 344 grade 2 and 119 grade 3 tumours at excision. Factors significantly associated with upgrade were large ultrasound (US) size, hyperechogencity, stiffness at shearwave elastography (SWE), calcification on mammography and oestrogen receptor (ER) and progesterone receptor (PR) negativity. Patient source, Human epidermal growth factor receptor 2 (HER-2) status, ultrasound (US) distal effect and mammographic spiculation were not significantly associated with chance of upgrade. On multivariate analysis, only US size maintained statistical significance.Conclusion: Oncologists and surgeons should be aware that lesions with a core biopsy diagnosis of grade 2 IDC-NST measuring over 15 mm on US have a 37% chance of being grade 3 on excision and this should be considered when deciding pre-operative management.</p

Magnetic properties of the honeycomb oxide Na2_2Co2_2TeO6_6

We have studied the magnetic properties of Na$_2$Co$_2$TeO$_6$, which features a honeycomb lattice of magnetic Co$^{2+}$ ions, through macroscopic characterization and neutron diffraction on a powder sample. We have shown that this material orders in a zig-zag antiferromagnetic structure. In addition to allowing a linear magnetoelectric coupling, this magnetic arrangement displays very peculiar spatial magnetic correlations, larger in the honeycomb planes than between the planes, which do not evolve with the temperature. We have investigated this behavior by Monte Carlo calculations using the $J_1$-$J_2$-$J_3$ model on a honeycomb lattice with a small interplane interaction. Our model reproduces the experimental neutron structure factor, although its absence of temperature evolution must be due to additional ingredients, such as chemical disorder or quantum fluctuations enhanced by the proximity to a phase boundary.Comment: 9 pages, 13 figure

A comparison of the imaging features of pleomorphic and classical invasive lobular carcinoma

Purpose: Pleomorphic invasive lobular carcinoma (pILC) is a distinct morphological variant of ILC with a poorer prognosis than classical ILC (cILC). The aim of this study was to ascertain whether the conventional imaging appearances of the two entities differ.Methods: A single-center retrospective review of conventional imaging was undertaken in 150 consecutive patients with histopathologically confirmed ILC (38 pILC; 112 cILC) between April 2010 and July 2015. Mammographic and sonographic findings were evaluated using the BI-RADS lexicon by a radiologist blinded to pathology, and the findings in the two groups were compared. The degree of discrepancy between imaging and pathological sizing in the two groups was evaluated.Results: Lesions were mammographically occult in 11% of pILC and 14% of cILC (p = 0.56). On mammography, skin or trabecular thickening and microcalcification were commoner in pILC than cILC (13% vs. 1%, p &lt; 0.01; 25% vs. 5%, p &lt; 0.01). Architectural distortion was more frequent in cILC than pILC (26% vs. 9%, p = 0.01). On ultrasound, pILC more frequently exhibited mixed echogenicity (28% vs. 13%; p = 0.04), skin thickening, subcutaneous or parenchymal edema (8% vs. 0%; p = 0.02), echogenic surrounding fat (33% vs. 9%; p &lt; 0.01), and posterior acoustic enhancement (10% vs. 1%; p = 0.02) than cILC. CILC was more frequently manifested as a focal area of altered echogenicity (24% vs. 8%; p = 0.04). Mean elastography stiffness was higher for pILC (174.8 vs. 124.6 kPa; p = 0.02). Imaging-pathological size disparity was similar for both subtypes.Conclusion: There are differences in the imaging features between pILC and cILC which reflect the more aggressive nature of pILC.</p

High contrast imaging with an arbitrary aperture: active correction of aperture discontinuities: fundamental limits and practical trade-offs

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and / or segment gaps. We solve the highly non-linear Monge-Ampere equation that is the fundamental equation describing the physics of phase induced amplitude modulation. We determine the optimum configuration for our two sequential Deformable Mirror system and show that high-throughput and high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to JWST, ACAD can attain at least 10-7 in contrast and an order of magnitude higher for future Extremely Large Telescopes, even when the pupil features a "missing segment" . Because the converging non-linear mappings resulting from our Deformable Mirror shapes damps near-field diffraction artifacts in the vicinity of the discontinuities this solution is particularly appealing in terms of spectral bandwidth. We present preliminary results that illustrate the performances of ACAD in the presence of diffraction for apertures for with secondary support structures of varying width and argue that the ultimate contrast achieved can by combining ACAD with modern wavefront control algorithms

Lunar radiation environment and space weathering from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER)

[1] The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) measures linear energy transfer by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) on the Lunar Reconnaissance Orbiter (LRO) Mission in a circular, polar lunar orbit. GCR fluxes remain at the highest levels ever observed during the space age. One of the largest SEP events observed by CRaTER during the LRO mission occurred on June 7, 2011. We compare model predictions by the Earth-Moon-Mars Radiation Environment Module (EMMREM) for both dose rates from GCRs and SEPs during this event with results from CRaTER. We find agreement between these models and the CRaTER dose rates, which together demonstrate the accuracy of EMMREM, and its suitability for a real-time space weather system. We utilize CRaTER to test forecasts made by the Relativistic Electron Alert System for Exploration (REleASE), which successfully predicts the June 7th event. At the maximum CRaTER-observed GCR dose rate (∼11.7 cGy/yr where Gy is a unit indicating energy deposition per unit mass, 1 Gy = 1 J/kg), GCRs deposit ∼88 eV/molecule in water over 4 billion years, causing significant change in molecular composition and physical structure (e.g., density, color, crystallinity) of water ice, loss of molecular hydrogen, and production of more complex molecules linking carbon and other elements in the irradiated ice. This shows that space weathering by GCRs may be extremely important for chemical evolution of ice on the Moon. Thus, we show comprehensive observations from the CRaTER instrument on the Lunar Reconnaissance Orbiter that characterizes the radiation environment and space weathering on the Moon

Comparing computer-generated and pathologist-generated tumour segmentations for immunohistochemical scoring of breast tissue microarrays

BACKGROUND: Tissue microarrays (TMAs) have become a valuable resource for biomarker expression in translational research. Immunohistochemical (IHC) assessment of TMAs is the principal method for analysing large numbers of patient samples, but manual IHC assessment of TMAs remains a challenging and laborious task. With advances in image analysis, computer-generated analyses of TMAs have the potential to lessen the burden of expert pathologist review. METHODS: In current commercial software computerised oestrogen receptor (ER) scoring relies on tumour localisation in the form of hand-drawn annotations. In this study, tumour localisation for ER scoring was evaluated comparing computer-generated segmentation masks with those of two specialist breast pathologists. Automatically and manually obtained segmentation masks were used to obtain IHC scores for thirty-two ER-stained invasive breast cancer TMA samples using FDA-approved IHC scoring software. RESULTS: Although pixel-level comparisons showed lower agreement between automated and manual segmentation masks (κ=0.81) than between pathologists' masks (κ=0.91), this had little impact on computed IHC scores (Allred; [Image: see text]=0.91, Quickscore; [Image: see text]=0.92). CONCLUSIONS: The proposed automated system provides consistent measurements thus ensuring standardisation, and shows promise for increasing IHC analysis of nuclear staining in TMAs from large clinical trials