Glacier-bed characteristics of midtre Lovénbreen, Svalbard, from high-resolution seismic and radar surveying

AbstractWe conducted a seismic and radar survey of the central part of midtre Lovénbreen, a small, polythermal valley glacier in Svalbard. We determined the physical properties of the material beneath the glacier by measuring the reflection coefficient of the bed by comparing the energy of the primary and multiple reflections, and deriving the acoustic impedance. By making reasonable assumptions about the properties of the basal ice, we determined the acoustic impedance of the bed material as (6.78 ± 1.53) × 106 kg m−2 s−1. We interpret the material beneath the glacier to be permafrost with up to 50% ice, and we speculate that the material may be frozen talus similar to a deposit observed directly by others beneath another Svalbard glacier. The implication for midtre Lovénbreen is that the basal material beneath the present glacier is not able to support fast flow. We conclude that midtre Lovénbreen has most likely had limited capability for faster flow in the past, with motion dominated by internal deformation. Midtre Lovénbreen is used as a ‘study glacier’ for the scientific community in Svalbard, and a large number of studies have been based there. Our results show that it cannot be used as an analogue for larger glaciers in Svalbard, having distinct basal boundary conditions.

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Variations in basal conditions on Rutford Ice Stream, West Antarctica

Journal of Glaciology ◽

10.3189/s0022143000003191 ◽

1997 ◽

Vol 43 (144) ◽

pp. 245-255 ◽

Cited By ~ 4

Author(s):

A. M. Smith

Keyword(s):

Acoustic Impedance ◽

West Antarctica ◽

Multiple Reflections ◽

Seismic Reflection Data ◽

Reflection Data ◽

Ice Stream ◽

Basal Sliding ◽

Third Line ◽

Water Saturated ◽

Bed Material

AbstractSeismic reflection data from two lines on Rutford Ice Streem are presented and are compared with data already published from a third line on the ice stream. The amplitude and phase of the reflections have been used io investigate the properties ol the sub-ice material. Multiple reflections on long record-length data allowed calibration of the reflection coefficient at the ice-bed interlace and determination of the acoustic impedance of the bed material. The characteristics of the bed material vary both along and across the ice stream. The average acoustic impedance of the bed material across the glacier at the upstream line is 3.88 x 106 kg−2 s−1. This decreases to 3.19 x 10−6 kg m−2s−1 52 km further downstream. These values are within the rang which is typical of soft sediments. Using acoustic impedance as an indicator of subgiacial porosity, some areas of the ice-stream bed are interpreted as dilatant water-saturated sediments undergoing pervasive deformation. In other areas, the bed is not deforming and basal sliding may be a more important process. The proportional the ice-stream width over which bed deformation occurs increases downstream.

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Variations in basal conditions on Rutford Ice Stream, West Antarctica

Journal of Glaciology ◽

10.1017/s0022143000003191 ◽

1997 ◽

Vol 43 (144) ◽

pp. 245-255 ◽

Cited By ~ 38

Author(s):

A. M. Smith

Keyword(s):

Acoustic Impedance ◽

West Antarctica ◽

Multiple Reflections ◽

Seismic Reflection Data ◽

Reflection Data ◽

Ice Stream ◽

Basal Sliding ◽

Third Line ◽

Water Saturated ◽

Bed Material

AbstractSeismic reflection data from two lines on Rutford Ice Streem are presented and are compared with data already published from a third line on the ice stream. The amplitude and phase of the reflections have been used io investigate the properties ol the sub-ice material. Multiple reflections on long record-length data allowed calibration of the reflection coefficient at the ice-bed interlace and determination of the acoustic impedance of the bed material. The characteristics of the bed material vary both along and across the ice stream. The average acoustic impedance of the bed material across the glacier at the upstream line is 3.88 x 106kg−2s−1. This decreases to 3.19 x 10−6kg m−2s−152 km further downstream. These values are within the rang which is typical of soft sediments. Using acoustic impedance as an indicator of subgiacial porosity, some areas of the ice-stream bed are interpreted as dilatant water-saturated sediments undergoing pervasive deformation. In other areas, the bed is not deforming and basal sliding may be a more important process. The proportional the ice-stream width over which bed deformation occurs increases downstream.

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Stellar Evolution

Transactions of the International Astronomical Union ◽

10.1017/s0251107x00022343 ◽

1962 ◽

Vol 11 (02) ◽

pp. 137-143

Author(s):

M. Schwarzschild

Keyword(s):

Solar System ◽

Stellar Evolution ◽

Space Craft ◽

New Techniques ◽

Substantial Body ◽

Individual Stars ◽

The Past ◽

Evolution Of Galaxies ◽

History Of ◽

Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

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The Contribution of Intermediate-Voltage, High-Resolution Electron Microscopy In Materials Science: An Appraisal

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181142 ◽

1990 ◽

Vol 48 (1) ◽

pp. 478-479

Author(s):

John L. Hutchison

Keyword(s):

High Resolution ◽

Materials Science ◽

High Resolution Electron Microscopy ◽

Optical Diffraction ◽

The Past ◽

Resolution Electron ◽

Extreme Sensitivity ◽

Electron Microscopes ◽

New Generation ◽

Small Metal Particles

Over the past five years or so the development of a new generation of high resolution electron microscopes operating routinely in the 300-400 kilovolt range has produced a dramatic increase in resolution, to around 1.6 Å for “structure resolution” and approaching 1.2 Å for information limits. With a large number of such instruments now in operation it is timely to assess their impact in the various areas of materials science where they are now being used. Are they falling short of the early expectations? Generally, the manufacturers’ claims regarding resolution are being met, but one unexpected factor which has emerged is the extreme sensitivity of these instruments to both floor-borne and acoustic vibrations. Successful measures to counteract these disturbances may require the use of special anti-vibration blocks, or even simple oil-filled dampers together with springs, with heavy curtaining around the microscope room to reduce noise levels. In assessing performance levels, optical diffraction analysis is becoming the accepted method, with rotational averaging useful for obtaining a good measure of information limits. It is worth noting here that microscope alignment becomes very critical for the highest resolution.In attempting an appraisal of the contributions of intermediate voltage HREMs to materials science we will outline a few of the areas where they are most widely used. These include semiconductors, oxides, and small metal particles, in addition to metals and minerals.

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The Contribution of Phonon-Scattered Electrons to High-Resolution Electron Micrographs of Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179063 ◽

1990 ◽

Vol 48 (1) ◽

pp. 62-63

Author(s):

H. Kohl

Keyword(s):

High Resolution ◽

Spherical Aberration ◽

High Resolution Electron Microscopy ◽

Static Potential ◽

Qualitative Comparison ◽

The Past ◽

Resolution Electron ◽

High Resolution Images ◽

High Resolution Electron Micrographs ◽

Extract Information

High-Resolution Electron Microscopy is able to determine structures of crystals and interfaces with a spatial resolution of somewhat less than 2 Å. As the image is strongly dependent on instrumental parameters, notably the defocus and the spherical aberration, the interpretation of micrographs necessitates a comparison with calculated images. Whereas one has often been content with a qualitative comparison of theory with experiment in the past, one is currently striving for quantitative procedures to extract information from the images [1,2]. For the calculations one starts by assuming a static potential, thus neglecting inelastic scattering processes.We shall confine the discussion to periodic specimens. All electrons, which have only been elastically scattered, are confined to very few directions, the Bragg spots. In-elastically scattered electrons, however, can be found in any direction. Therefore the influence of inelastic processes on the elastically (= Bragg) scattered electrons can be described as an attenuation [3]. For the calculation of high-resolution images this procedure would be correct only if we had an imaging energy filter capable of removing all phonon-scattered electrons. This is not realizable in practice. We are therefore forced to include the contribution of the phonon-scattered electrons.

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d4PDF: large-ensemble and high-resolution climate simulations for global warming risk assessment

Progress in Earth and Planetary Science ◽

10.1186/s40645-020-00367-7 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Masayoshi Ishii ◽

Nobuhito Mori

Keyword(s):

Risk Assessment ◽

Global Warming ◽

High Resolution ◽

Climate Changes ◽

Future Climate ◽

Atmospheric Models ◽

Large Ensemble ◽

Past Climate ◽

The Past ◽

Climate Simulations

Abstract A large-ensemble climate simulation database, which is known as the database for policy decision-making for future climate changes (d4PDF), was designed for climate change risk assessments. Since the completion of the first set of climate simulations in 2015, the database has been growing continuously. It contains the results of ensemble simulations conducted over a total of thousands years respectively for past and future climates using high-resolution global (60 km horizontal mesh) and regional (20 km mesh) atmospheric models. Several sets of future climate simulations are available, in which global mean surface air temperatures are forced to be higher by 4 K, 2 K, and 1.5 K relative to preindustrial levels. Nonwarming past climate simulations are incorporated in d4PDF along with the past climate simulations. The total data volume is approximately 2 petabytes. The atmospheric models satisfactorily simulate the past climate in terms of climatology, natural variations, and extreme events such as heavy precipitation and tropical cyclones. In addition, data users can obtain statistically significant changes in mean states or weather and climate extremes of interest between the past and future climates via a simple arithmetic computation without any statistical assumptions. The database is helpful in understanding future changes in climate states and in attributing past climate events to global warming. Impact assessment studies for climate changes have concurrently been performed in various research areas such as natural hazard, hydrology, civil engineering, agriculture, health, and insurance. The database has now become essential for promoting climate and risk assessment studies and for devising climate adaptation policies. Moreover, it has helped in establishing an interdisciplinary research community on global warming across Japan.

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Scientific literacy, public engagement and responsibility in science

Cultures of Science ◽

10.1177/20966083211009646 ◽

2021 ◽

pp. 209660832110096

Author(s):

Daya Reddy

Keyword(s):

Public Good ◽

Genome Editing ◽

Public Engagement ◽

Scientific Literacy ◽

Scientific Community ◽

Global Public Good ◽

Public Communication ◽

Digital Revolution ◽

The Past ◽

Responsibility Of Scientists

This work addresses the issue of scientific literacy and its connection to the responsibility of scientists in relation to public engagement. The points of departure are, first, the notion of science as a global public good, and, second, developments in the past few decades driven largely by the digital revolution. The latter lend a particular urgency to initiatives aimed at promoting scientific literacy. Arguments are presented for reassessing approaches to public communication. The particular example of genome editing is provided as a vehicle for highlighting the challenges in engagement involving the scientific community, policymakers and broader society.

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«Love Rejoices in Truth …»: to the 20th anniversary of the journal «Solovyov Studies»

Solov’evskie issledovaniya ◽

10.17588/2076-9210.2021.4.006-024 ◽

2021 ◽

pp. 6-24

Author(s):

M.V. Maksimov

Keyword(s):

United States Of America ◽

Scientific Community ◽

Geographical Location ◽

The United States ◽

Information Support ◽

The Past ◽

20Th Anniversary ◽

Student Projects

This essay presents a description of the scholarly events commemorating the 20th anniversary of the journal “Solovyov Studies”. It gives an overview of the exhibition "20 years of the journal “Solovyov Studies”: 2001–2021," prepared by the editorial board of the journal together with the Library of the ISPU. It highlights a variety of the sections of the exposition and the materials presented, reflecting the development of the journal over two decades, the composition of its editorial board, including authoritative experts from Russia, Bulgaria, Great Britain, Germany, Italy, the Netherlands, Poland, the United States of America, Ukraine, and France. The reader’s attention is drawn to the information about the journal's position in various ratings schemes, both domestic and foreign, and citation indices, the share of publications by foreign authors and their geographical location, as well as the number of journal-views over the past five years. The article shows the role of scientific communications in the development of the journal, Information is given on the participation of the editorial board in international scientific events, on publications devoted to the journal and its presentations in Russian and foreign publications, universities and research centers. The article describes the Solovyov seminar’s cultural and student projects, which received substantial content and information support from “Solovyov Studies”. The level of interest of the scientific community in the journal is also noted.

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Passive smoking in the Royal Navy

Journal of The Royal Naval Medical Service ◽

10.1136/jrnms-80-17 ◽

1994 ◽

Vol 80 (1) ◽

pp. 17-21

Author(s):

L B Cannon

Keyword(s):

Passive Smoking ◽

Scientific Community ◽

Current Evidence ◽

Royal Navy ◽

The Past ◽

Similar Survey ◽

The Media

AbstractPassive smoking is an emotive issue and one which has received considerable coverage in the past few years from both the scientific community and the media. The arguments for and against links between passive smoking and disease are as fiercely contested among members of the Royal Navy as among civilians. This article aims to present the current evidence in favour of such a link and also the views on the matter as expressed by the ship’s company of a Type 22 frigate. Their views will be compared to the result of a similar survey carried out among civilian workforces. Finally, based on the evidence and results presented, strategies for tackling this problem will be discussed.

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