Representing moisture fluxes and phase changes in glacier debris cover using a reservoir approach

Due to the complexity of treating moisture in supraglacial debris, surface energy balance models to date have neglected moisture infiltration and phase changes in the debris layer. The latent heat flux (QL) is also often excluded due to the uncertainty in determining the surface vapour pressure. To quantify the importance of moisture on the surface energy and climatic mass balance (CMB) of debris-covered glaciers, we developed a simple reservoir parameterization for the debris ice and water content, as well as an estimation of the latent heat flux. The parameterization was incorporated into a CMB model adapted for debris-covered glaciers. We present the results of two point simulations, using both our new “moist” and the conventional “dry” approaches, on the Miage Glacier, Italy, during summer 2008 and fall 2011. The former year coincides with available in situ glaciological and meteorological measurements, including the first eddy-covariance measurements of the turbulent fluxes over supraglacial debris, while the latter contains two refreeze events that permit evaluation of the influence of phase changes. The simulations demonstrate a clear influence of moisture on the glacier energy and mass-balance dynamics. When water and ice are considered, heat transmission to the underlying glacier ice is lower, as the effective thermal diffusivity of the saturated debris layers is reduced by increases in both the density and the specific heat capacity of the layers. In combination with surface heat extraction by QL, subdebris ice melt is reduced by 3.1% in 2008 and by 7.0% in 2011 when moisture effects are included. However, the influence of the parameterization on the total accumulated mass balance varies seasonally. In summer 2008, mass loss due to surface vapour fluxes more than compensates for the reduction in ice melt, such that the total ablation increases by 4.0 %. Conversely, in fall 2011, the modulation of basal debris temperature by debris ice results in a decrease in total ablation of 2.1 %. Although the parameterization is a simplified representation of the moist physics of glacier debris, it is a novel attempt at including moisture in a numerical model of debris-covered glaciers and one that opens up additional avenues for future research

Fear appeals prior to a high-stakes examination can have a positive or negative impact on engagement depending on how the message is appraised

Previous studies have shown that teachers may use messages that focus on the importance of avoiding failure (fear appeals) prior to high-stakes examinations as a motivational tactic. The aim of this study was to examine whether fear appeals, and their appraisal as challenging or threatening, impacted on student engagement. Data were collected from 1373 students, clustered in 46 classes, and 81 teachers responsible for instruction in those classes, prior to a high-stakes mathematics secondary school exit examination. Data were analyzed in a multilevel structural equation model. The appraisal of fear appeals as challenging leads to greater student engagement and as threatening to lower student engagement. The impact of fear appeals on engagement was mediated by challenge and threat appraisals. The effectiveness of fear appeals as a motivational strategy depends on how they are interpreted by students

Homotopy classification of 4-manifolds whose fundamental group is dihedral

We show that the homotopy type of a finite oriented Poincar\'{e} 4-complex is determined by its quadratic 2-type provided its fundamental group is finite and has a dihedral Sylow 2-subgroup. By combining with results of Hambleton-Kreck and Bauer, this applies in the case of smooth oriented 4-manifolds whose fundamental group is a finite subgroup of SO(3). An important class of examples are elliptic surfaces with finite fundamental group.Comment: 23 pages. Final version, to appear in Algebraic & Geometric Topolog

Structural and Functional Studies of GDP-6-Deoxy-Talose and GDP-Rhamnose Biosynthetic Enzymes

GDP-6-deoxy-D-talose and its 4-epimer GDP-D-rhamnose are unusual sugars found on the cell surface of certain Gram-negative bacteria. GDP-6-deoxy-talose and GDP-rhamnose are produced by enzymes called GTS and RMD, respectively. These sugars are produced from the same common intermediate and are 4\u27-epimers of each other, which provides an interesting paradigm to study the stereo-selective reduction of unusual sugars. We have determined a novel X-ray crystallographic structure of RMD from Pseudomonas aeruginosa that contains its cosubstrate NADPH within the active site. A superposition of our RMD structure with a previously-determined one gives clear insight into the mechanism of hydride transfer from the cofactor during catalysis. We also report progress toward the structural analysis of GTS and functional analyses of both enzymes. Characterization of GTS and RMD will allow for an understanding of how bacteria utilize these sugars and may give insight into the pathogenicity of certain Gram-negative bacteria. Furthermore, an understanding of the production of unusual sugars can allow for the derivitization of existing antibiotics in an effort to combat bacterial resistance via a process called glycodiversification

Emergency medical services (EMS) training in Kenya: Findings and recommendations from an educational assessment

Background: Over the past twenty years, Kenya has been developing many important components of a prehospital emergency medical services (EMS) system. This is due to the ever-increasing demand for emergency medical care across the country. To better inform the next phase of this development, we undertook an assessment of the current state of EMS training in Kenya. Methods: A group of international and Kenyan experts with relevant EMS and educational expertise conducted an observational qualitative assessment of Kenyan EMS training institutions in 2016. Three assessment techniques were utilised: semi-structured interviews, document review, and structured observations. Recommendations were reached through a consensus process amongst the assessment team. Results: Key findings include: (i) No national or state-level policy exists that establishes levels of EMS providers or expected fund of knowledge and skills; (ii) Training institutions have independently created their own individual training standards; (iii) Training materials are not adapted for the local context; (iv) The foundation of basic anatomy and physiology education is weak; (v) Training does not focus on symptom- or syndrome-based complaints; (vi) Students had difficulty applying foundational classroom knowledge in simulations and clinical encounters; (vii) There is limited emphasis on complex critical thinking. Discussion: Standardisation of training is needed in Kenya, including clearly defined levels of providers and expected learning outcomes. A nationally standardised EMS provider scope of practice may also help focus EMS education. Instructors must reinforce basic anatomy and physiology amongst all trainees to establish a robust foundation, then layer on field experience before trainees receive advanced training. Training graduates should be EMS providers who approach patient care with high-order symptom- or syndrome-based critical thinking. While these recommendations are specific to the Kenyan EMS environment, they may have wider applicability to other developing EMS systems in resource-limited settings

Epidermal growth factor receptor downregulation by small heterodimeric binding proteins

No single engineered protein has been shown previously to robustly downregulate epidermal growth factor receptor (EGFR), a validated cancer target. A panel of fibronectin-based domains was engineered to bind with picomolar to nanomolar affinity to multiple epitopes of EGFR. Monovalent and homo- and hetero-bivalent dimers of these domains were tested for EGFR downregulation. Selected orientations of non-competitive heterodimers decrease EGFR levels by up to 80% in multiple cell types, without activating receptor signaling. These heterodimers inhibit autophosphorylation, proliferation and migration, and are synergistic with the monoclonal antibody cetuximab in these activities. These small (25 kDa) heterodimers represent a novel modality for modulating surface receptor levels.National Institutes of Health (U.S.) (NIH grant CA96504)National Institutes of Health (U.S.) (NIH grant CA118705)National Science Foundation (U.S.) (Graduate Research Fellowship Program

Transcriptional regulation of the piRNA pathway by Ovo in animal ovarian germ cells

The gene-regulatory mechanisms controlling the expression of the germline PIWI-interacting RNA (piRNA) pathway components within the gonads of metazoan species remain largely unexplored. In contrast to the male germline piRNA pathway, which in mice is known to be activated by the testis-specific transcription factor A-MYB, the nature of the ovary-specific gene-regulatory network driving the female germline piRNA pathway remains a mystery. Here, using Drosophila as a model, we combined multiple genomics approaches to reveal the transcription factor Ovo as regulator of the germline piRNA pathway in ovarian germ cells. Ectopic expression of Ovo in ovarian somatic cells activates germline piRNA pathway components, including the ping-pong factors Aubergine, Argonaute-3, and Vasa, leading to assembly of perinuclear cellular structures resembling nuage bodies of germ cells. We found that in ovarian somatic cells, transcription of ovo is repressed by l(3)mbt, thus preventing expression of germline piRNA pathway genes in the soma. Cross-species ChIP-seq and motif analyses demonstrate that Ovo is binding to genomic CCGTTA motifs within the promoters of germline piRNA pathway genes, suggesting a regulation by Ovo in ovaries analogous to that of A-MYB in testes. Our results also show consistent engagement of the Ovo transcription factor family at ovarian piRNA clusters across metazoan species, reflecting a deep evolutionary conservation of this regulatory paradigm from insects to humans

Recognising diversity in older adults' cybersecurity needs

Older adults continue to be targeted by cybersecurity attacks: a trend which shows no signs of slowing, and one that has become even more problematic given that many older adults adopted new digital technologies during the Covid-19 lockdowns. Yet there remains a scarcity of solutions designed to help older adults protect themselves online. In part, this is due to a lack of understanding of the specific needs of older adults, who are the fastest growing, and arguably most technologically diverse population on the internet. This study draws upon recent qualitative research to identify key dimensions which are likely to influence older adult cybersecurity behaviour and subsequent vulnerability. We show how these dimensions can be used, for example, to develop a wide range of personas that help illustrate the range of abilities and attitudes in the older adult population. The dimensions outlined here can be used to help researchers, designers, and developers better understand the diverse needs of older adult users when developing digital or security solutions for this population

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde