Englacial architecture and age-depth constraints across the West Antarctic Ice Sheet

he englacial stratigraphic architecture of internal reflection horizons (IRHs) as imaged by ice‐penetrating radar (IPR) across ice sheets reflects the cumulative effects of surface mass balance, basal melt, and ice flow. IRHs, considered isochrones, have typically been traced in interior, slow‐flowing regions. Here, we identify three distinctive IRHs spanning the Institute and Möller catchments that cover 50% of West Antarctica's Weddell Sea Sector and are characterized by a complex system of ice stream tributaries. We place age constraints on IRHs through their intersections with previous geophysical surveys tied to Byrd Ice Core and by age‐depth modeling. We further show where the oldest ice likely exists within the region and that Holocene ice‐dynamic changes were limited to the catchment's lower reaches. The traced IRHs from this study have clear potential to nucleate a wider continental‐scale IRH database for validating ice sheet models

Digital three-dimensional imaging techniques provide new analytical pathways for malacological research

Author Posting. © BioOne Complete, 2019. This article is posted here by permission of BioOne Complete for personal use, not for redistribution. The definitive version was published in Ziegler, A., Bock, C., Ketten, D. R., Mair, R. W., Mueller, S., Nagelmann, N., Pracht, E. D., & Schroeder, L. Digital three-dimensional imaging techniques provide new analytical pathways for malacological research. American Malacological Bulletin, 36(2), (2018):248-273, doi:10.4003/006.036.0205.Research on molluscan specimens is increasingly being carried out using high-throughput molecular techniques. Due to their efficiency, these technologies have effectively resulted in a strong bias towards genotypic analyses. Therefore, the future large-scale correlation of such data with the phenotype will require a significant increase in the output of morphological studies. Three-dimensional (3D) scanning techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) can achieve this goal as they permit rapidly obtaining digital data non-destructively or even entirely non-invasively from living, fixed, and fossil samples. With a large number of species and a relatively complex morphology, the Mollusca would profit from a more widespread application of digital 3D imaging techniques. In order to provide an overview of the capacity of various MRI and CT techniques to visualize internal and external structures of molluscs, more than twenty specimens ranging in size from a few millimeters to well over one meter were scanned in vivo as well as ex vivo. The results show that all major molluscan organ systems can be successfully visualized using both MRI and CT. The choice of a suitable imaging technique depends primarily on the specimen's life condition, its size, the required resolution, and possible invasiveness of the approach. Apart from visual examples derived from more than two dozen scans, the present article provides guidelines and best practices for digital 3D imaging of a broad range of molluscan taxa. Furthermore, a comprehensive overview of studies that previously have employed MRI or CT techniques in malacological research is given.We would like to express our gratitude to Adam J. Baldinger, Thomas Bartolomaeus, Patrick Beckers, Rüdiger Bieler, Roger T. Hanlon, Carsten Lüter, Iliana Ruiz-Cooley, Tom Schiøtte, Andreas Schmidt-Rhaesa, and Sid Staubach for help with specimen collection or for providing access to museum material. Cornelius Faber, Julia Koch, Tony Stöcker, and W. Caroline West kindly facilitated use of scanning systems. We would also like to thank Julie Arruda, Scott Cramer, Jörg Döpfert, Charlotte Eymann, Bastian Maus, Malte Ogurreck, Christina L. Sagorny, Gillian Trombke, and Christopher Witte for support with data acquisition and analysis. We are particularly grateful to Elizabeth K. Shea for inviting the present contribution and for her extensive commentary on the manuscript. We also thank two anonymous reviewers for their helpful criticisms. Funding for this study was provided by the Ocean Life Institute, the Office of Naval Research, the Seaver Institute, and the Deutsche Forschungsgemeinschaft (INST 217/849-1 FUGG)

Noise reduction in 3D noncollinear parametric amplifier

We analytically find an approximate Bloch-Messiah reduction of a noncollinear parametric amplifier pumped with a focused monochromatic beam. We consider type I phase matching. The results are obtained using a perturbative expansion and scaled to a high gain regime. They allow a straightforward maximization of the signal gain and minimization of the parametric fluorescence noise. We find the fundamental mode of the amplifier, which is an elliptic Gaussian defining the optimal seed beam shape. We conclude that the output of the amplifier should be stripped of higher order modes, which are approximately Hermite-Gaussian beams. Alternatively, the pump waist can be adjusted such that the amount of noise produced in the higher order modes is minimized.Comment: 18 pages, 9 figures, accepted to Applied Physics

Open-Access, Low-Magnetic-Field MRI System for Lung Research

An open-access magnetic resonance imaging (MRI) system is being developed for use in research on orientational/gravitational effects on lung physiology and function. The open-access geometry enables study of human subjects in diverse orientations. This system operates at a magnetic flux density, considerably smaller than the flux densities of typical other MRI systems, that can be generated by resistive electromagnet coils (instead of the more-expensive superconducting coils of the other systems). The human subject inhales air containing He-3 or Xe-129 atoms, the nuclear spins of which have been polarized by use of a laser beam to obtain a magnetic resonance that enables high-resolution gas space imaging at the low applied magnetic field. The system includes a bi-planar, constant-current, four-coil electromagnet assembly and associated electronic circuitry to apply a static magnetic field of 6.5 mT throughout the lung volume; planar coils and associated circuitry to apply a pulsed magnetic-field-gradient for each spatial dimension; a single, detachable radio-frequency coil and associated circuitry for inducing and detecting MRI signals; a table for supporting a horizontal subject; and electromagnetic shielding surrounding the electromagnet coils

Water- and nutrient-dependent effects of dietary restriction on Drosophila lifespan

Dietary restriction (DR) is a widely conserved intervention leading to lifespan extension. Despite considerable effort, the mechanisms underlying DR remain poorly understood. In particular, it remains unclear whether DR prolongs life through conserved mechanisms in different species. Here, we show that, in the most common experimental conditions, lifespan extension by DR is abolished by providing Drosophila with ad libitum water, without altering food intake, indicating that DR, as conventionally studied in flies, is fundamentally different from the phenomenon studied in mammals. We characterize an alternative dietary paradigm that elicits robust lifespan extension irrespective of water availability, and thus likely represents a more relevant model for mammalian DR. Our results support the view that protein:carbohydrate ratio is the main dietary determinant of fly lifespan. These findings have broad implications for the study of lifespan and nutrition

Brain Genomics Superstruct Project initial data release with structural, functional, and behavioral measures

The goal of the Brain Genomics Superstruct Project (GSP) is to enable large-scale exploration of the links between brain function, behavior, and ultimately genetic variation. To provide the broader scientific community data to probe these associations, a repository of structural and functional magnetic resonance imaging (MRI) scans linked to genetic information was constructed from a sample of healthy individuals. The initial release, detailed in the present manuscript, encompasses quality screened cross-sectional data from 1,570 participants ages 18 to 35 years who were scanned with MRI and completed demographic and health questionnaires. Personality and cognitive measures were obtained on a subset of participants. Each dataset contains a T1-weighted structural MRI scan and either one (n=1,570) or two (n=1,139) resting state functional MRI scans. Test-retest reliability datasets are included from 69 participants scanned within six months of their initial visit. For the majority of participants self-report behavioral and cognitive measures are included (n=926 and n=892 respectively). Analyses of data quality, structure, function, personality, and cognition are presented to demonstrate the dataset’s utility

Proteomic identification of secreted proteins as surrogate markers for signal transduction inhibitor activity

Epidermal growth factor receptor is a potential target for cancer treatment and new small-molecule tyrosine kinase inhibitor drugs have been designed to inhibit its activity. In this work we identify potential surrogate markers of drug activity using a proteomic analysis. Two-dimensional electrophoresis was optimised to compare expression patterns of proteins secreted from the cancer cell lines A431 and A549 treated with Gefitinib (Iressa) vs untreated or vehicle-only-treated samples. Upregulated or downregulated proteins were detected using Phoretix 2D image analysis software. Several proteins were then identified using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. In one case, upregulation of Protein Disulphide Isomerase in response to Gefitinib was confirmed by Western blot analysis, and the response was shown to be concentration dependent. The identification of surrogate markers may be of use for the evaluation of new drugs, in preclinical models, in clinical trials and in the therapy of individual patients to give optimal biological drug doses

Government Influence on Patient Organizations

Patient organizations increasingly play an important role in health care decision-making in Western countries. The Netherlands is one of the countries where this trend has gone furthest. In the literature some problems are identified, such as instrumental use of patient organizations by care providers, health insurers and the pharmaceutical industry. To strengthen the position of patient organizations government funding is often recommended as a solution. In this paper we analyze the ties between Dutch government and Dutch patient organizations to learn more about the effects of such a relationship between government and this part of civil society. Our study is based on official government documents and existing empirical research on patient organizations. We found that government influence on patient organizations has become quite substantial with government influencing the organizational structure of patient organizations, the activities these organizations perform and even their ideology. Financing patient organizations offers the government an important means to hold them accountable. Although the ties between patient organizations and the government enable the former to play a role that can be valued as positive by both parties, we argue that they raise problems as well which warrant a discussion on how much government influence on civil society is acceptable