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Current sea-level rise partly stems from increased surface melting and meltwater runoff from the Greenland ice sheet. Multi-year snow, also known as firn, covers about 80% of the ice sheet and retains part of the surface meltwater. Since the firn cold content integrates its physical and thermal characteristics, it is a valuable tool for determining the meltwater-retention potential of firn. We use gap-filled climatological data from nine automatic weather stations in the ice-sheet accumulation area to drive a surface-energy-budget and firn model, validated against firn density and temperature observations, over the 1998–2017 period. Our results show a stable top 20 m firn cold content (CC20) at most sites. Only at the lower-elevation Dye-2 site did CC20 decrease, by 24% in 2012, before recovering to its original value by 2017. Heat conduction towards the surface is the main process feeding CC20 at all nine sites, while CC20 reduction occurs through low-cold-content fresh-snow addition at the surface during snowfall and latent-heat release when meltwater refreezes. Our simulations suggest that firn densification, while reducing pore space for meltwater retention, increases the firn cold content, enhances near-surface meltwater refreezing and potentially sets favourable conditions for ice-slab formation.
Anxiety is among the most frequently studied emotions in second language acquisition (SLA). Study abroad (SA) researchers have examined its effects on SLA in that setting in a number of studies. The current study goes beyond previous SA research by examining how anxiety develops and connects with language proficiency development over SA. Specifically, it uses anxiety-related measures of foreign language classroom anxiety (FLCA), foreign language enjoyment (FLE), and a physiological manifestation of anxiety (hair cortisol). As far as the classroom is concerned, learners grew more comfortable, experiencing less anxiety and more enjoyment over the period of SA. However, learners showed physiological signs of overall elevated anxiety despite these increasing classroom comfort levels. Two key factors that may have influenced their anxiety levels abroad were tendency toward anxiety prior to SA and language proficiency upon departure for SA. The latter provides support for having students more proficient prior to SA, since doing so may lead to less anxiety during SA.
Little is known about potential harmful effects as a consequence of self-guided internet-based cognitive behaviour therapy (iCBT), such as symptom deterioration rates. Thus, safety concerns remain and hamper the implementation of self-guided iCBT into clinical practice. We aimed to conduct an individual participant data (IPD) meta-analysis to determine the prevalence of clinically significant deterioration (symptom worsening) in adults with depressive symptoms who received self-guided iCBT compared with control conditions. Several socio-demographic, clinical and study-level variables were tested as potential moderators of deterioration.
Randomised controlled trials that reported results of self-guided iCBT compared with control conditions in adults with symptoms of depression were selected. Mixed effects models with participants nested within studies were used to examine possible clinically significant deterioration rates.
Thirteen out of 16 eligible trials were included in the present IPD meta-analysis. Of the 3805 participants analysed, 7.2% showed clinically significant deterioration (5.8% and 9.1% of participants in the intervention and control groups, respectively). Participants in self-guided iCBT were less likely to deteriorate (OR 0.62, p < 0.001) compared with control conditions. None of the examined participant- and study-level moderators were significantly associated with deterioration rates.
Self-guided iCBT has a lower rate of negative outcomes on symptoms than control conditions and could be a first step treatment approach for adult depression as well as an alternative to watchful waiting in general practice.
We present our latest 3D model atmospheres for carbon-enhanced metal-poor (CEMP) stars computed with the CO5BOLD code. The stellar parameters are representative of hot turn-off objects (Teff ~ 6250 K, log g = 4.0, [Fe/H]=−3). The main purpose of these models is to investigate the role of 3D effects on synthetic spectra of the CH G-band (4140-4400 Å), the CN BX-band (3870-3890 Å), and several UV OH transitions (3122-3128 Å). By comparison with the synthetic spectra from standard 1D model atmospheres (assuming local thermodynamic equilibrium, LTE), we derive 3D abundance corrections for carbon and oxygen of up to −0.5 and −0.7 dex, respectively.
The role of episodic mass loss in evolved massive stars is one of the outstanding questions in stellar evolution theory. Integral field spectroscopy of nebulae around massive stars provide information on their recent mass-loss history. η Car is one of the most massive evolved stars and is surrounded by a complex circumstellar environment. We have conducted a three-dimensional morpho-kinematic analysis of η Car’s ejecta outside its famous Homunculus nebula. SHAPE modelling of VLT MUSE data establish unequivocally the spatial cohesion of the outer ejecta and the correlation of ejecta with the soft X-ray emission.
Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in glacier melt independently from model output. Here, we present a comprehensive database of Greenland glacier surface mass-balance observations from the ablation area of the ice sheet and local glaciers. The database spans the 123 a from 1892 to 2015, contains a total of ~3000 measurements from 46 sites, and is openly accessible through the PROMICE web portal (http://www.promice.dk). For each measurement we provide X, Y and Z coordinates, starting and ending dates as well as quality flags. We give sources for each entry and for all metadata. Two thirds of the data were collected from grey literature and unpublished archive documents. Roughly 60% of the measurements were performed by the Geological Survey of Denmark and Greenland (GEUS, previously GGU). The data cover all regions of Greenland except for the southernmost part of the east coast, but also emphasize the importance of long-term time series of which there are only two exceeding 20 a. We use the data to analyse uncertainties in point measurements of surface mass balance, as well as to estimate surface mass-balance profiles for most regions of Greenland.
Agitation is common across neuropsychiatric disorders and contributes to disability, institutionalization, and diminished quality of life for patients and their caregivers. There is no consensus definition of agitation and no widespread agreement on what elements should be included in the syndrome. The International Psychogeriatric Association formed an Agitation Definition Work Group (ADWG) to develop a provisional consensus definition of agitation in patients with cognitive disorders that can be applied in epidemiologic, non-interventional clinical, pharmacologic, non-pharmacologic interventional, and neurobiological studies. A consensus definition will facilitate communication and cross-study comparison and may have regulatory applications in drug development programs.
The ADWG developed a transparent process using a combination of electronic, face-to-face, and survey-based strategies to develop a consensus based on agreement of a majority of participants. Nine-hundred twenty-eight respondents participated in the different phases of the process.
Agitation was defined broadly as: (1) occurring in patients with a cognitive impairment or dementia syndrome; (2) exhibiting behavior consistent with emotional distress; (3) manifesting excessive motor activity, verbal aggression, or physical aggression; and (4) evidencing behaviors that cause excess disability and are not solely attributable to another disorder (psychiatric, medical, or substance-related). A majority of the respondents rated all surveyed elements of the definition as “strongly agree” or “somewhat agree” (68–88% across elements). A majority of the respondents agreed that the definition is appropriate for clinical and research applications.
A provisional consensus definition of agitation has been developed. This definition can be used to advance interventional and non-interventional research of agitation in patients with cognitive impairment.
The Mediterranean diet has been reported to be inversely associated with incident metabolic syndrome (MetSyn) among older adults; however, this association has not been studied in young African American and white adults. The objective of the present study was to evaluate the association of a modified Mediterranean diet (mMedDiet) score with the 25-year incidence of the MetSyn in 4713 African American and white adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. A diet history questionnaire was used to assess dietary intake at baseline, year 7 and year 20 and a mMedDiet score was created. Cardiovascular risk factors were measured at multiple examinations over 25 years. The MetSyn was defined according to the National Cholesterol Education Program Adult Treatment Panel III (ATP III) criteria. Cox proportional-hazards regression analysis was use to evaluate associations for incident MetSyn across the mMedDiet score categories adjusting for demographic characteristics, lifestyle factors and BMI. Higher mMedDiet scores represented adherence to a dietary pattern rich in fruit, vegetables, whole grains, nuts and fish, but poor in red and processed meat and snack foods. The incidence of MetSyn components (abdominal obesity, elevated TAG concentrations and low HDL-cholesterol concentrations) was lower in those with higher mMedDiet scores than in those with lower scores. Furthermore, the incidence of the MetSyn was lower across the five mMedDiet score categories; the hazard ratios and 95 % CI from category 1 to category 5 were 1·0; 0·94 (0·76, 1·15); 0·84 (0·68, 1·04); 0·73 (0·58, 0·92); and 0·72 (0·54, 0·96), respectively (Ptrend= 0·005). These findings suggest that the risk of developing the MetSyn is lower when consuming a diet rich in fruit, vegetables, whole grains, nuts and fish.
Continuous good-quality deep ice cores provide excellent scientific data with which to reconstruct a past climate record for >800 ka. At depths starting from ∼100m using an electromechanical drill, a drilling liquid is essential for successful recovery of the very high-quality ice cores demanded by modern scientific analysis techniques (e.g. continuous flow analysis). Finding a suitable drill fluid for use at deep ice-coring drill sites is not an easy task. Temperatures vary greatly not just from site to site, but also at a site where the average mean temperature from surface to bedrock can vary from –55°C to –2.75°C. In the past 60 years, many fluids have been used, with varying degrees of success, but for various reasons are either unavailable, are now considered unsafe and dangerous or are too environmentally damaging to be permitted. Here we report on our pre-season investigation into possible candidate drill fluids, with specific information concerning ESTISOL™ 240 and COASOL™, the rationale behind the redesign of our drill successfully used at NorthGRIP, Greenland, and EPICA DML, Antarctica, the knock-on effect of those changes, and our field experience in Greenland at Flade Isblink in 2006 and at NEEM in 2009–10.
A drill liquid is essential for the purpose of recovering good-quality scientifically useful ice cores at intermediate to deep depths, i.e. >∼100 m. The pressure produced by the liquid helps to eliminate the detrimental effects of the abrupt release of isostatic pressure in the ice during the drilling process, prevents consequential fractures within the ice core, and is essential to produce an even distribution of hydrostatic pressure to balance the ice isostatic pressure and so minimize borehole deformation. To perform these tasks, while minimizing risks to health and the environment, the liquid needs to exhibit specific physical, chemical and biological characteristics. Here we report on two promising candidate drill liquids, ESTISOL™ 140 and ESTISOL™ 165, for use in the extreme conditions found within the ice sheets of Greenland and Antarctica, where the temperature can range from close to 0°C to below −57°C and pressures can exceed 40 MPa. From both the manufacturer’s data and our laboratory tests and observations we report on the physical, chemical and biological characteristics that both liquids exhibit. We also report on how one of the candidates was field-tested on the Greenland ice sheet and the East Antarctic high plateau.
We assess the runoff and surface mass balance (SMB) of the Greenland ice sheet in the Nuuk region (southwest) using output of two regional climate models (RCMs) evaluated by observations. The region encompasses six glaciers that drain into Godthåbsfjord. RCM data (1960–2012) are resampled to a high spatial resolution to include the narrow (relative to the native grid spacing) glacier trunks in the ice mask. Comparing RCM gridded results with automatic weather station (AWS) point measurements reveals that locally models can underestimate ablation and overestimate accumulation by up to tens of per cent. However, comparison with lake discharge indicates that modelled regional runoff totals are more accurate. Model results show that melt and runoff in the Nuuk region have doubled over the past two decades. Regional SMB attained negative values in recent high-melt years. Taking into account frontal ablation of the marine-terminating glaciers, the region lost 10–20 km3 w.e. a–1 in 2010–12. If 2010 melting prevails during the remainder of this century, a low-end estimate of sea-level rise of 5 mm is expected by 2100 from this relatively small section (2.6%) of the ice sheet alone.
We present a critical review of the construction of 3D model atmospheres with emphasis on modeling challenges. We discuss the basic physical processes which give rise to the effects which set 3D models apart from 1D standard models. We consider elemental abundances derived from molecular features, and the determination of the microturbulence with 3D models. The examples serve as illustration of the limitations inherent to 1D, however, also to 3D modeling. We find that 3D models can provide constraints on the microturbulence parameter, and predict substantial corrections for abundances derived from molecular species.
We present a new determination of the solar nitrogen abundance making use of 3D hydrodynamical modelling of the solar photosphere, which is more physically motivated than traditional static 1D models. We selected suitable atomic spectral lines, relying on equivalent width measurements already existing in the literature. For atmospheric modelling we used the co5bold 3D radiation hydrodynamics code. We investigated the influence of both deviations from local thermodynamic equilibrium (non-LTE effects) and photospheric inhomogeneities (granulation effects) on the resulting abundance. We also compared several atlases of solar flux and centre-disc intensity presently available. As a result of our analysis, the photospheric solar nitrogen abundance is A(N) = 7.86 ± 0.12.
Deriving glacier outlines from satellite data has become increasingly popular in the past decade. In particular when glacier outlines are used as a base for change assessment, it is important to know how accurate they are. Calculating the accuracy correctly is challenging, as appropriate reference data (e.g. from higher-resolution sensors) are seldom available. Moreover, after the required manual correction of the raw outlines (e.g. for debris cover), such a comparison would only reveal the accuracy of the analyst rather than of the algorithm applied. Here we compare outlines for clean and debris-covered glaciers, as derived from single and multiple digitizing by different or the same analysts on very high- (1 m) and medium-resolution (30 m) remote-sensing data, against each other and to glacier outlines derived from automated classification of Landsat Thematic Mapper data. Results show a high variability in the interpretation of debris-covered glacier parts, largely independent of the spatial resolution (area differences were up to 30%), and an overall good agreement for clean ice with sufficient contrast to the surrounding terrain (differences ∼5%). The differences of the automatically derived outlines from a reference value are as small as the standard deviation of the manual digitizations from several analysts. Based on these results, we conclude that automated mapping of clean ice is preferable to manual digitization and recommend using the latter method only for required corrections of incorrectly mapped glacier parts (e.g. debris cover, shadow).
A functionalization method for the specific and selective immobilization of the streptavidin (SA) protein on semiconductor nanowires (NWs) was developed. Silicon (Si) and silicon carbide (SiC) NWs were functionalized with 3-aminopropyltriethoxysilane (APTES) and subsequently biotinylated for the conjugation of SA. Existence of a thin native oxide shell on both Si and SiC NWs enabled efficient binding of APTES with the successive attachment of biotin and SA as was confirmed with x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and atomic force microscopy. Fluorescence microscopy demonstrated nonspecific, electrostatic binding of the SA and the bovine serum albumin (BSA) proteins to APTES-coated NWs. Inhibition of nonspecific BSA binding and enhancement of selective SA binding were achieved on biotinylated NWs. The biofunctionalized NWs have the potential to be used as biosensing platforms for the specific and selective detection of proteins.
We present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.
We present the results of 3D hydrodynamic simulations aimed to explore the binary scenario for shaping bipolar, point- and mirror-symmetric proto-Planetary Nebulae. We consider a jet launched by the secondary star of a binary system, located at the center of the PPN, which propagates within a circumstellar medium swept previously up by the wind of the giant companion. As a result of the presence of the companion star, the accretion disk around the jet source is likely to precess. We have carried out 3D hydrodynamical simulations with the YGUAZÚ-A code including the combination of an orbital motion plus a precession. Our results show that to produce a multipolar nebula, it is necessary to have a precessing jet in a binary system with a time-dependent ejection velocity.
In this talk, we review the basic assumptions and physics covered by classical 1D LTE model atmospheres. We will focus on ATLAS and MARCS models of F-G-K stars and describe what resources are available through the web, both in terms of codes and model-atmosphere grids. We describe the advances made in hydrodynamical simulations of convective stellar atmospheres with the CO5BOLD code and what grids and resources are available, with a prospect of what will be available in the near future.