Showing papers by "University of Kansas published in 2023"

Interactions between amyloid, amyloid precursor protein, and mitochondria

Abstract: Mitochondrial dysfunction and Aβ accumulation are hallmarks of Alzheimer's disease (AD). Decades of research describe a relationship between mitochondrial function and Aβ production. Amyloid precursor protein (APP), of which Aβ is generated from, is found within mitochondria. Studies suggest Aβ can be generated in mitochondria and imported into mitochondria. APP and Aβ alter mitochondrial function, while mitochondrial function alters Aβ production from APP. The role these interactions contribute to AD pathology and progression are unknown. Here, we discuss prior research, the rigor of those studies, and the critical knowledge gaps of relationships between APP, Aβ, and mitochondria.

The Resilience of the Phonological Network May Have Implications for Developmental and Acquired Disorders

Abstract: A central tenet of network science states that the structure of the network influences processing. In this study of a phonological network of English words we asked: how does damage alter the network structure (Study 1)? How does the damaged structure influence lexical processing (Study 2)? How does the structure of the intact network "protect" processing with a less efficient algorithm (Study 3)? In Study 1, connections in the network were randomly removed to increasingly damage the network. Various measures showed the network remained well-connected (i.e., it is resilient to damage) until ~90% of the connections were removed. In Study 2, computer simulations examined the retrieval of a set of words. The performance of the model was positively correlated with naming accuracy by people with aphasia (PWA) on the Philadelphia Naming Test (PNT) across four types of aphasia. In Study 3, we demonstrated another way to model developmental or acquired disorders by manipulating how efficiently activation spread through the network. We found that the structure of the network "protects" word retrieval despite decreases in processing efficiency; words that are relatively easy to retrieve with efficient transmission of priming remain relatively easy to retrieve with less efficient transmission of priming. Cognitive network science and computer simulations may provide insight to a wide range of speech, language, hearing, and cognitive disorders.

Comparative Pharmacology of the 3 Marketed Dual Orexin Antagonists—Daridorexant, Lemborexant, and Suvorexant—Part 2. Principal Drug Metabolizing Enzyme, Drug-Drug Interactions, and Effects of Liver and Renal Impairment on Metabolism

Abstract: Log in or Register Subscribe to journalSubscribe Get new issue alertsGet alerts Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed to maintaining your privacy and will not share your personal information without your express consent. For more information, please refer to our Privacy Policy. Subscribe to eTOC Secondary Logo Journal Logo All Articles Images Videos Podcasts Blogs Advanced Search Toggle navigation Subscribe Register Login Articles & Issues Current IssuePrevious IssuesOnline First CollectionsFor Authors Submit a ManuscriptInformation for AuthorsLanguage Editing ServicesAuthor Permissions Journal Info About the JournalEditorial BoardOpen AccessSubscription ServicesReprintsRights and PermissionsAdvertising All Articles Images Videos Podcasts Blogs Advanced Search

Active supervision: empowering teachers and families to support students in varied learning contexts

Abstract: In this article, we introduce active supervision as a simple, feasible strategy for teachers and families to increase student engagement as well as decrease off-task and disruptive behaviors across a range of contexts. We provide step-by-step guidance to illustrate how active supervision can be used by teachers in in-person and virtual learning environments as well as how families can incorporate active supervision into daily routines at home.

Behavior-specific praise: Empowering teachers and families to support students in varied learning contexts

Abstract: In this article, we introduce behavior-specific praise as a portable, feasible strategy for teachers and families to increase student engagement as well as to decrease off-task and disruptive behaviors in a variety of environments. We provide step-by-step guidance to illustrate how behavior-specific praise can be used by teachers during in-person and remote learning environments and how families can incorporate behavior-specific praise into daily routines at home.

The Metaphysics of Margaret Cavendish and Anne Conway

Abstract: Abstract This book is an examination of the metaphysical systems of Margaret Cavendish and Anne Conway, who share many superficial similarities. By providing a detailed analysis of their views on substance, monism, self-motion, individuation, and identity over time, as well as causation, perception, and freedom, it demonstrates the interesting ways in which their accounts differ. Seeing their systems in tandem highlights the originality of each philosopher. In addition to providing the details of their metaphysical views, the book also shows how they put these views to use: for Cavendish in grounding her natural philosophy and for Conway in developing her theodicy. The account of Cavendish is more naturalistic than current interpretations. It argues that God plays no substantive role in Cavendish’s philosophy. The book provides an account of Cavendish’s matter and her biological holism. It shows how sensitive and rational matter are expressed differently in different natural kinds. It provides the first account of Cavendish’s views on individuation and identity over time and a detailed account of her views on causation, arguing that nature is the only principal cause. The book also provides an account of Conway’s spiritual substance, arguing that it is a unique type of substance. It discusses Conway’s two types of motions and causation. In addition, a detailed account of her view of motion as a mode of body, and how it is transferred, is provided. Finally, the book concludes that Conway’s metaphysics and morality are inseparable and that she holds a type of perfectionism.

Clinical efficacy of retreatment of daratumumab‐based therapy ( <scp>D2</scp> ) in daratumumab‐refractory multiple myeloma

Abstract: Daratumumab demonstrates activity as a single agent and in combination with either immunomodulatory agents (IMiDs) or proteasome inhibitors (PIs) in relapsed refractory multiple myeloma (RRMM). However, little is known about the benefit of daratumumab retreatment in daratumumab-refractory MM. This study aimed to analyze the clinical efficacy of daratumumab-based retreatment (D2) in patients who are daratumumab refractory MM. Retrospectively, we identified 43 RRMM patients from a single-center database review. The median age was 65 years, 42% patients had high-risk cytogenetics, and 23% had an extramedullary disease, while the median time between D2 and prior daratumumab was 1 (0.25-39) month. All D2 patients received combination therapy with either pomalidomide, carfilzomib, bortezomib, or lenalidomide. The response rate, median progression-free, and overall survival were 49%, 7.97 and 32.6 months, respectively. Our study raises the possibility of re-utilizing daratumumab in combination with different classes of anti-myeloma drugs to generate responses in RRMM patients who are daratumumab-refractory.

Assessing the Impacts of COVID-19 and Social Isolation on Mental Health in the United States of America

Abstract: The COVID-19 pandemic has had a devastating impact on the world at large with over 750 million cases and almost 7 million deaths reported thus far. Of those, over 100 million cases and 1 million deaths have occurred in the United States of America (USA). The mental health of the general population has been impacted by several aspects of the pandemic including lockdowns, media sensationalism, social isolation, and spread of the disease. In this paper, we examine the associations that social isolation and COVID-19 infection and related death had with the prevalence of anxiety and depression in the general population of the USA in a state-by-state multiple time-series analysis. Vector Error Correction Models are estimated and we subsequently evaluated the coefficients of the estimated models and calculated their impulse response functions for further interpretation. We found that COVID-19 incidence was positively associated with anxiety across the studied period for a majority of states. Variables related to social isolation had a varied effect depending on the state being considered.

Precorrection: empowering teachers and families to support students in varied learning contexts

Abstract: In this article, the authors introduce precorrection as a feasible, effective strategy for teachers and families to use to increase engagement and minimize disruptive behavior in a range of learning contexts. The authors provide step-by-step guidance to illustrate how precorrection can be used by teachers in in-person and remote learning environments as well as how families can incorporate precorrection into daily routines at home.

Linguicism in U.S. Higher Education: A Critical Autoethnography

Abstract: Abstract This critical autoethnography discusses the emotional and cognitive dissonance encountered by the author, an international faculty member, during her professional journey at a large public research university in the United States. Despite being recognized for her scholarship as a promising researcher in the field of TESOL (Teaching English to Speakers of Other Languages), she has still encountered covert linguicism (Skutnabb-Kangas, 2012), a phenomenon ubiquitous in the English-dominant higher education context. This chapter discusses the ways in which the linguistic discrimination has shaped the author’s professional identity and how she exerts her agency as a teacher educator-researcher through critical reflexivity to promote legitimacy and self-efficacy in her professional community. By unpacking and problematizing the dominant discourse, such as native speakerism (Holliday, 2015), in English language teaching, this study aims to provide a nuanced understanding of the lived experience of a bilingual faculty member in a teacher education program in the United States.

Context-dependent sexual changes during women’s midlife transitions

Abstract: For women, midlife represents an important stage of transition, including shifts in physiological, social, and sexual experiences. Prior research demonstrates that women's sexuality is more dynamic and context-dependent than men's. Most research focused on women's sexuality in mid- to later-life emphasizes physiological changes, while largely ignoring changes stemming from social, psychological, and relational contexts. The present study examined midlife women's diverse sexual experiences within the context of their lives. We conducted semi-structured interviews with 27 women, ages 39-57, and used interpretative phenomenological analysis to investigate perceptions and interpretations of midlife sexual experiences and changes. Themes included changes in sexual engagement, unwanted sexual experiences, body image, and sexual healthcare. Participants reported changes in the frequency of sex and sexual desire within the context of their diverse social roles and identities, prior intimate relationships, and sexual health. Women contrasted perceptions of their own bodies with societal perceptions of sexiness. Frequently reported negative experiences with sexual healthcare informed a distrust of healthcare systems. The diverse and changing nature of participants' experiences supports prior evidence of sexual fluidity and context-dependence. By questioning societal expectations around sexuality and body image, participants illustrated the potential of counternarratives to combat dominant beliefs and stereotypes about midlife women's sexuality. To improve sexual health and education, psychoeducational interventions for women in midlife are needed.

Extending aquifer lifespans with pumping reductions: Experiences from the High Plains aquifer

Abstract: The High Plains aquifer in the central United States is one of the world&#8217;s largest and most important regional aquifers in terms of the agricultural production that its waters support. The portion of the aquifer in the state of Kansas has been heavily stressed for decades, producing large water-level declines that have called into question the continued viability of groundwater-based irrigated agriculture and the rural communities that depend on it. Given the sparsity of surface water in the region, reductions in pumping, which are typically accompanied by modifications of agricultural practices, are often the only option to extend the aquifer lifespan. Such reductions, however, must be implemented over a relatively large area to make a signi&#64257;cant impact on regional decline rates. In 2012, the Kansas Legislature approved a new groundwater management option to facilitate pumping reductions, the Local Enhanced Management Area (LEMA) program. This program allows the development of locally generated management plans that are then supported by regulatory oversight. The first LEMA, the Sheridan-6 (SD-6) LEMA, was established in 2013 in a 255 square kilometer area in northwest Kansas with the goal of reducing water use by 20% relative to the prior average use. In the first decade, the pumping reduction was close to 30% after controlling for climatic conditions. More importantly, the water-level decline rate decreased by over 50%, thereby extending the aquifer lifespan by over five years during the first ten years of the LEMA. The ultimate extension of the aquifer lifespan, which will likely be much greater, depends on how net inflow changes with time. Until now, net inflow has remained close to the pre-reduction level. Eventually, however, it will decrease in response to the pumping reductions. Continued monitoring will enable the timing and magnitude of that decrease to be quantified. The success of the SD-6 LEMA has led to the establishment of larger LEMAs in 2018 (12,623 square kilometers) and 2021 (663 square kilometers) with an additional LEMA under consideration. If the success of the irrigators in the SD-6 LEMA can be duplicated in these larger areas, the lifespan of the High Plains aquifer in Kansas will be significantly extended.

Hepatic dysfunction in patients receiving intravenous lipid emulsions

Abstract: Log in or Register Subscribe to journalSubscribe Get new issue alertsGet alerts Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed to maintaining your privacy and will not share your personal information without your express consent. For more information, please refer to our Privacy Policy. Subscribe to eTOC Secondary Logo Journal Logo All Articles Images Videos Podcasts Blogs Advanced Search Toggle navigation Subscribe Register Login Articles & Issues Current IssuePrevious IssuesPublished Ahead-of-Print VideosFor Authors Submit a ManuscriptInformation for AuthorsLanguage Editing ServicesAuthor PermissionsLippincott® Preprints Journal Info About the JournalEditorial BoardAdvertisingOpen AccessSubscription ServicesReprintsRights and Permissions All Articles Images Videos Podcasts Blogs Advanced Search

Analysis of heparin-induced thrombocytopenia diagnostic and management strategies in individuals with inconclusive antibody optical densities

Abstract: Heparin-induced thrombocytopenia (HIT) is an uncommon but serious complication of exposure to heparin. Antibody optical densities (ODs) used to diagnose HIT exceeding 2 are highly suggestive of disease, whereas ODs less than 0.5 often ‘rule out’ HIT. Variation in the clinical care of patients with inconclusive ODs between 0.5 and 2 is likely. This single-centre, retrospective analysis evaluates the diagnosis, management and outcomes of those with antibody ODs between 0.5 and 2. We queried our institution's Healthcare Enterprise Repository for Ontological Narration (HERON) database to identify individuals with antibody ODs between 0.5 and 2. Chart review was completed to calculate 4T scores, corroborate diagnosis codes with documented information in our electronic health record (EHR) and evaluate the diagnosis, management and outcomes of these individuals. These data were evaluated using descriptive and univariate statistics. Among individuals evaluated for HIT between November 2007 and July 2020, we identified 302 individuals with ODs between 0.5 and 2. Serotonin release assays (SRAs) were assessed in 55% (165/302) and were positive in 12% (20/165). In those with available data, 96% with low 4T scores had negative SRAs and 4% had positive SRAs. As 4T scores and antibody ODs proportionally increased, SRA positivity also increased. Clinical management varied widely; however, 4T scoring remains a valuable assessment in this cohort. In those with HIT antibody ODs between 0.5 and 2, true positives were uncommon, and their clinical management varied widely. Fortunately, 4T scoring is a useful prognostic tool that improves the diagnosis and management among those with inconclusive HIT.

tracked_changes

Abstract: Abstract. Utilizing the well-calibrated, high spectral resolution, and equal-quality-performance for day and night observations (9:30 a.m. and 9:30 p.m. equator passing time) of the Infrared Atmospheric Sounder Interferometer (IASI) products, this study investigates the day-night differences in dust activities over the dust belt of North Africa, the Middle East, and Asia. Both daytime and nighttime dust optical depth (DOD) at 10 microns shows high consistency with solar and lunar observations from AErosol RObotic NETwork (AERONET) sites across the dust belt, with correlation coefficients of 0.8–0.9 for most sites. IASI reveals significant (95 % confidence level) day-night differences in dust activities over the major dust sources within the dust belt. Annual mean daytime DOD at 9:30 a.m. is significantly higher than that of nighttime at 9:30 p.m. in the central to northern Sahara Desert, the central to eastern Arabian Peninsula and dust source regions in South and East Asia including the Taklamakan Desert, but lower over the southern Sahel to the Guinea Coast, and the central to southern Indian subcontinent. The magnitude of the day-night difference in DOD is larger and more significant in boreal winter and spring than other seasons. An analysis of 10 m wind fields and dust uplift potential using the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) suggests that the positive day-night differences in DOD over the central Sahara, the Middle East, and Asia are associated with enhanced dust emissions driven by stronger wind speed. Dust layer heights demonstrate negative day-night differences (i.e., lower daytime versus higher nighttime values) over dust source regions in the central Sahara, central Arabian Peninsula, and Asia, and positive height differences in the southern Sahel to the Guinea Coast, southern parts of the Arabian Peninsula, and large parts of the Indian subcontinent. The higher dust layer height over the Guinea Coast and the Indian subcontinent during daytime is associated with a deeper planetary boundary layer height and greater convective instability around 9:30 a.m. than that during 9:30 p.m., which promotes vertical transport and mixing of dust. The corresponding lower daytime DOD over these downwind regions indicates a possible dilution of dust aerosols when they are transported to higher altitude by convection and are more susceptible to horizontal transport. Ground observations from the Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA) and AERONET show surface PM₁₀ concentration and dust aerosols exhibit a spatially varying diurnal cycle across the dust belt with peak coarse-mode aerosol optical depth (CAOD; around 7–9 a.m.) and PM₁₀ concentrations (around 9–11 a.m.) in the morning hours and late afternoon to midnight in the Sahel, peak CAOD from morning to early afternoon (around 9 a.m.–1 p.m.) and around midnight in the Middle East and Asia, generally consistent with day-night differences in dust activities revealed by IASI. An examination of DOD from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and ECMWF Atmospheric Composition Reanalysis 4 (EAC4) products reveals that reanalysis products largely capture the temporal and spatial variability of DOD on the seasonal scale but failed to capture the day-night differences in DOD in large parts of the dust belt except in a few dust source hotspots over North Africa, such as the northeastern Bodélé Depression and the northeastern North Africa. Overall, this study provides a detailed and comprehensive analysis of the day-night differences in dust activities over the dust belt, which could improve our current understanding of physical mechanisms of dust cycle at the diurnal timescale in various dust source and downwind regions.

Reply on RC1

Abstract: Abstract. Utilizing the well-calibrated, high spectral resolution, and equal-quality-performance for day and night observations (9:30 a.m. and 9:30 p.m. equator passing time) of the Infrared Atmospheric Sounder Interferometer (IASI) products, this study investigates the day-night differences in dust activities over the dust belt of North Africa, the Middle East, and Asia. Both daytime and nighttime dust optical depth (DOD) at 10 microns shows high consistency with solar and lunar observations from AErosol RObotic NETwork (AERONET) sites across the dust belt, with correlation coefficients of 0.8–0.9 for most sites. IASI reveals significant (95 % confidence level) day-night differences in dust activities over the major dust sources within the dust belt. Annual mean daytime DOD at 9:30 a.m. is significantly higher than that of nighttime at 9:30 p.m. in the central to northern Sahara Desert, the central to eastern Arabian Peninsula and dust source regions in South and East Asia including the Taklamakan Desert, but lower over the southern Sahel to the Guinea Coast, and the central to southern Indian subcontinent. The magnitude of the day-night difference in DOD is larger and more significant in boreal winter and spring than other seasons. An analysis of 10 m wind fields and dust uplift potential using the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) suggests that the positive day-night differences in DOD over the central Sahara, the Middle East, and Asia are associated with enhanced dust emissions driven by stronger wind speed. Dust layer heights demonstrate negative day-night differences (i.e., lower daytime versus higher nighttime values) over dust source regions in the central Sahara, central Arabian Peninsula, and Asia, and positive height differences in the southern Sahel to the Guinea Coast, southern parts of the Arabian Peninsula, and large parts of the Indian subcontinent. The higher dust layer height over the Guinea Coast and the Indian subcontinent during daytime is associated with a deeper planetary boundary layer height and greater convective instability around 9:30 a.m. than that during 9:30 p.m., which promotes vertical transport and mixing of dust. The corresponding lower daytime DOD over these downwind regions indicates a possible dilution of dust aerosols when they are transported to higher altitude by convection and are more susceptible to horizontal transport. Ground observations from the Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA) and AERONET show surface PM₁₀ concentration and dust aerosols exhibit a spatially varying diurnal cycle across the dust belt with peak coarse-mode aerosol optical depth (CAOD; around 7–9 a.m.) and PM₁₀ concentrations (around 9–11 a.m.) in the morning hours and late afternoon to midnight in the Sahel, peak CAOD from morning to early afternoon (around 9 a.m.–1 p.m.) and around midnight in the Middle East and Asia, generally consistent with day-night differences in dust activities revealed by IASI. An examination of DOD from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and ECMWF Atmospheric Composition Reanalysis 4 (EAC4) products reveals that reanalysis products largely capture the temporal and spatial variability of DOD on the seasonal scale but failed to capture the day-night differences in DOD in large parts of the dust belt except in a few dust source hotspots over North Africa, such as the northeastern Bodélé Depression and the northeastern North Africa. Overall, this study provides a detailed and comprehensive analysis of the day-night differences in dust activities over the dust belt, which could improve our current understanding of physical mechanisms of dust cycle at the diurnal timescale in various dust source and downwind regions.

Empathic Concern

Abstract: Abstract Empathic Concern provides an evidence-based review of developments over the past five decades in our understanding of other-oriented emotion felt for another in need, including the motivational and behavioral consequences of this emotional state. Empathic concern, or empathy for short, is an umbrella term that refers to feelings that may be described as sympathy, compassion, tenderness, and the like. The book considers what empathic concern is (and isn’t), where it comes from, its forms, its motivational consequences, and its importance in interpersonal and intergroup relations. Rather than touting empathic concern as a panacea or castigating it as a problem, the empirical evidence supports a more nuanced view: Empathic concern has potential benefits but also liabilities, and its benefits can be realized only if we recognize and address its liabilities. Programs that have employed empathic concern as a means to improve interpersonal and intergroup relations are described. The hope is that this review will stimulate more theory-based research on the nature and function of empathic concern, and more theory-based applications of what we now know.

Pandemics Interlaced: The Impact of the COVID-19 Pandemic on the Wellbeing of Sober Living Home Residents

Abstract: Objectives This study aimed to discover how the COVID-19 pandemic altered the implementation of the social model of recovery in sober living homes (SLHs). Researchers analyzed associations between residents’ feelings of interconnectedness, social service utilization, and relapse predictors throughout the pandemic. This study provides an understanding of how the COVID-19 pandemic impacted treatment of substance use disorder (SUD). Methods This study used retrospective surveyed data from 105 SLH residents. Correlational analysis was used to determine the relationship between social service use, social connectivity, and relapse predictors at three different time points: February 2020, December 2020, and June 2021. Three residents underwent additional interviews. Results There was a decline in social service utilization from February 2020 to December 2020 with an associated decline in feelings of social connectivity. From December 2020 to June 2021, there was an increase in residents’ use of social services with an associated increase in connectivity. There was a significant negative correlation between relapse predictors and number of supportive services used in February 2020 (r = −0.217, P < 0.05) and in December 2020 (r = −0.352, P < 0.001). In June 2020, there was a significant negative correlation between interconnectedness and relapse predictors (r = −0.297, P < 0.05). The number of interviews was not sufficient for formal qualitative analysis. Conclusions The results suggest the COVID-19 pandemic possibly interrupted the course of recovery in SLHs. These findings offer insight to how the pandemic impacted individuals recovering from SUD and suggest that SUD treatment professionals should develop interventions to enhance social connectivity to deploy in response to global stressors.

Justice-Involved Youths’ Perceptions of Placement Instability and Adjustment Related Outcomes

Abstract: Unique challenges associated with dual involvement in the child welfare and juvenile justice systems are well documented. However, there is a paucity of research focusing on the out-of-home placement experiences of youth involved in the justice system and implications for relevant outcomes. The current study examined out-of-home placement experiences and placement instability of justice-involved youth and how these experiences relate to relevant outcomes for youth involved with multiple service systems: attitudes toward seeking help, intolerance of uncertainty, and perceived containment. Participants included youth detained at two juvenile detention centers (n = 225; 71.1% male; Mage = 15.50). Self-report measures were read by research assistants who recorded the youths’ responses. Results revealed that over 50% of detained youth had been removed from their parents’ custody, and of these youth, nearly 60% reported experiencing three or more placement changes. Attitudes toward seeking help and intolerance of uncertainty in youth who experienced out-of-home placement were not significantly different than in youth who did not. However, youth who had experienced out-of-home placement exhibited significantly lower perceived containment scores. These findings suggest that placement instability is common among detained youth and may be meaningfully related to youth’s feelings about the ability of authorities to control them.

Fourier Analysis of Magnetic Fields in the Ionosphere of Mars

Abstract: The two main sources of the magnetic field in the Martian ionosphere are the solar wind interaction with the planet, and, mainly in the southern hemisphere, remnant crustal magnetization. The magnetic fields measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) and Mars Global Surveyor spacecraft displayed a wide range of spatial scales, from the global (i.e., L ≈ 103 km) to mesoscale (L ≈ 102 km) to small-scale (L < 10 km). Hamil et al. (2022) used MAVEN magnetometer and Langmuir Probe data to study these structures and suggested that they might be advected into the ionosphere from the solar wind and magnetosheath. In the current study, we apply a Fourier analysis to the fields and interpret the resulting power spectral density profiles versus frequency. The power spectral density function found from MAVEN data resembles that of the solar wind magnetic field (or interplanetary magnetic field) (i.e., power law with an index of about −2), but shifted upward in frequency by a factor of about 100. From a comparison of ionospheric power spectra with solar wind power spectra, we deduce that plasma, carrying a magnetic field with it moves from the magnetic pile-up region downward into the ionosphere with speeds of roughly tens of meters per second. The derived power spectra in the ionosphere, in addition to the basic power law shape, show hints of extra power at a spatial scale of about 10 km, and this might be due to the creation of a magnetic structure within the ionosphere itself.

Greenland ice-stream dynamics: short-lived and agile?

Abstract: Reliable knowledge of ice discharge dynamics for the Greenland ice sheet via its ice streams is essential if we are to understand its stability under future climate scenarios as well as their dynamics in the past, especially when using numerical models for diagnosis and prediction. Currently active ice streams in Greenland have been well mapped using remote-sensing data while past ice-stream paths in what are now deglaciated regions can be reconstructed from the landforms they left behind. However, little is known about possible former and now defunct ice streams in areas still covered by ice. Here we use radio-echo sounding data to decipher the regional ice-flow history of the northeastern Greenland ice sheet on the basis of its internal stratigraphy. By creating a three-dimensional reconstruction of time-equivalent horizons, we map folds deep below the surface that we then attribute to the deformation caused by now-extinct ice streams. We propose that locally this ancient ice-!ow regime was much more focused and reached much farther inland than today&#8217;s and was deactivated when the main drainage system was reconfigured and relocated southwards. The insight that major ice streams in Greenland might start, shift or abruptly disappear will affect our approaches to understanding and modelling the past or future response of Earth&#8217;s ice sheets to global warming. Such behaviour has to be sufficiently reproduced by numerical models operating on the mid- to longer-term timescales to be considered adequate physical representations of the naturally occuring dynamic behaviour of ice streams.