Analysis of in situ airborne measurements from the CalNex 2010 field experiment (Research at the Nexus of Air Quality and Climate Change) show that ozone in the boundary layer over Southern ...California was increased by downward mixing of air from the free troposphere (FT). The chemical composition, origin, and transport of air upwind and over Los Angeles, California, were studied using measurements of carbon monoxide (CO), ozone, reactive nitrogen species, and meteorological parameters from the National Oceanic and Atmospheric Administration WP‐3D aircraft on 18 research flights in California in May and June 2010. On six flights, multiple vertical profiles from 0.2–3.5 km above ground level were conducted throughout the Los Angeles (LA) basin and over the Pacific Ocean. Gas phase compounds measured in 32 vertical profiles are used to characterize air masses in the FT over the LA basin, with the aim of determining the source of increased ozone observed above the planetary boundary layer (PBL). Four primary air mass influences were observed regularly in the FT between approximately 1 and 3.5 km altitude: upper tropospheric air, long‐range transport of emissions, aged regional emissions, and marine air. The first three air mass types accounted for 89% of the FT observations. Ozone averaged 71 ppbv in air influenced by the upper troposphere, 69 ppbv in air containing emissions transported long distances, and 65 ppbv in air with aged regional emissions. Correlations between ozone and CO, and ozone and nitric acid, demonstrate entrainment of ozone from the FT into the LA PBL. Downward transport of ozone‐rich air from the FT into the PBL contributes to the ozone burden at the surface in this region and makes compliance with air quality standards challenging.
Key Points
Air mass chemical composition over Los Angeles Basin measured from aircraft
Upper tropospheric influence increased ozone in the lower free troposphere
Downward mixing of ozone‐rich air increased ozone in California
Transient slab flattening beneath Colombia Wagner, L. S.; Jaramillo, J. S.; Ramírez‐Hoyos, L. F. ...
Geophysical research letters,
16 July 2017, Letnik:
44, Številka:
13
Journal Article
Recenzirano
Subduction of the Nazca and Caribbean Plates beneath northwestern Colombia is seen in two distinct Wadati Benioff Zones, one associated with a flat slab to the north and one associated with normal ...subduction south of 5.5°N. The normal subduction region is characterized by an active arc, whereas the flat slab region has no known Holocene volcanism. We analyze volcanic patterns over the past 14 Ma to show that in the mid‐Miocene a continuous arc extended up to 7°N, indicating normal subduction of the Nazca Plate all along Colombia's Pacific margin. However, by ~6 Ma, we find a complete cessation of this arc north of 3°N, indicating the presence of a far more laterally extensive flat slab than at present. Volcanism did not resume between 3°N and 6°N until after 4 Ma, consistent with lateral tearing and resteepening of the southern portion of the Colombian flat slab at that time.
Key Points
The flat slab beneath Colombia originally extended much farther south than it does today
Volcanic ages suggest that flattening began at ~9 Ma, with full arc cessation by ~6 Ma
Modern arc in the south was reestablished after 4 Ma during slab tearing and resteepening
The Reynolds number for the onset of flow unsteadiness is determined for several canonical geometries (triangles, rectangles, ellipses and lozenges) at different sectional breadth (L) to height (d) ...ratios (aspect ratio AR=L∕d), for more than 70 shapes. The flow is modeled using a direct Navier–Stokes incompressible two-dimensional solver and the shape is defined by an Immersed Boundary Method. The employed procedure takes the fluctuation of the velocity in the wake as the criterion to define the unsteadiness and a binary search to find the transition. This procedure yields critical Reynolds number Rec values in agreement with available data in the literature. When AR approaches zero, the five shapes lead to almost the same value of 31, which corresponds to Rec for a flat plate normal to the flow. It is then found that Rec grows exponentially with the aspect ratio, the influence of the cross section shape being accounted for by a single regression parameter. For all aspect ratios, the ellipse exhibits the highest Rec, and the front-pointing triangle the lowest, the three other geometries laying in between those two. The physics of the influence of cross-section shape on Rec is analyzed, considering its link with recirculation length in particular. An exploitation of the results is outlined for the analysis of recent aeroacoustic shape optimizations at fixed Re=150, through correlation between the lift fluctuation at this regime with the distance to the onset of unsteadiness it corresponds to.
•The Reynolds number of the onset of vortex shedding is determined for 70 shapes.•Ellipses, rectangles, lozenges and triangles are considered, varying aspect ratio.•The critical Reynolds number increases exponentially with aspect ratio.•Inconsistency of Paul et al.’s law for the influence of aspect ratio is evidenced.•The shape influences the aeolian tone level via different critical Reynolds number.
The influence of valley geometry on thermally driven flows is studied by means of high‐resolution simulations. An idealized valley–plain topography and a spatially constant but time‐dependent surface ...sensible heat flux are used to generate upslope, upvalley and plain‐to‐mountain winds. A systematic variation of valley depth, width and length induces differences in the cross‐ and along‐valley flow field and thermal structure of the boundary layer. The deeper the valley, the stronger the upvalley winds and the more favoured the formation of vertically stacked circulation cells and an elevated valley inversion layer. Upvalley winds become weaker for wide valleys. The development of plain‐to‐mountain circulations increases vertical exchange processes between the boundary layer and the free atmosphere considerably, compared with vertical transport processes over a plain. The analysis of mass‐flux budgets and forward trajectories indicates that mass is transported three to four times more effectively from the surface to the free atmosphere over valleys than over flat terrain. Vertical transport processes are strongest for deep and narrow valleys.
Abstract Background Clinical reasoning (CR) is a crucial ability that can prevent errors in patient care. Despite its important role, CR is often not taught explicitly and, even when it is taught, ...typically not all aspects of this ability are addressed in health professions education. Recent research has shown the need for explicit teaching of CR for both students and teachers. To further develop the teaching and learning of CR we need to improve the understanding of students' and teachers' needs regarding content as well as teaching and assessment methods for a student and trainer CR curriculum. Methods Parallel mixed-methods design that used web-surveys and semi-structured interviews to gather data from both students (n survey = 100; n interviews = 13) and teachers (n survey = 112; n interviews = 28). The interviews and surveys contained similar questions to allow for triangulation of the results. This study was conducted as part of the EU-funded project DID-ACT ( https://did-act.eu ). Results Both the surveys and interview data emphasized the need for content in a clinical reasoning (CR) curriculum such as “gathering, interpreting and synthesizing patient information”, “generating differential diagnoses”, “developing a diagnostic and a treatment plan” and “collaborative and interprofessional aspects of CR”. There was high agreement that case-based learning and simulations are most useful for teaching CR. Clinical and oral examinations were favored for the assessment of CR. The preferred format for a train-the-trainer (TTT)-course was blended learning. There was also some agreement between the survey and interview participants regarding contents of a TTT-course (e.g. teaching and assessment methods for CR). The interviewees placed special importance on interprofessional aspects also for the TTT-course. Conclusions We found some consensus on needed content, teaching and assessment methods for a student and TTT-course in CR. Future research could investigate the effects of CR curricula on desired outcomes, such as patient care.
A
bstract
We introduce and explore new heavy Higgs scenarios in the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation, which have important phenomenological implications that ...may be testable at the LHC. For soft supersymmetry-breaking scales M
S
above a few TeV and a charged Higgs boson mass
M
H
+ above a few hundred GeV, new physics effects including those from explicit CP violation decouple from the light Higgs boson sector. However, such effects can significantly alter the phenomenology of the heavy Higgs bosons while still being consistent with constraints from low-energy observables, for instance electric dipole moments. To consider scenarios with a charged Higgs boson much heavier than the Standard Model (SM) particles but much lighter than the supersymmetric particles, we revisit previous calculations of the MSSM Higgs sector. We compute the Higgs boson masses in the presence of CP violating phases, implementing improved matching and renormalization-group (RG) effects, as well as two-loop RG effects from the effective two-Higgs Doublet Model (2HDM) scale
M
H
± to the scale
M
S
. We illustrate the possibility of non-decoupling CP-violating effects in the heavy Higgs sector using new benchmark scenarios named
.
Heat conduction in silicon can be effectively engineered by means of sub-micrometre porous thin free-standing membranes. Tunable thermal properties make these structures good candidates for ...integrated heat management units such as waste heat recovery, rectification or efficient heat dissipation. However, possible applications require detailed thermal characterisation at high temperatures which, up to now, has been an experimental challenge. In this work we use the contactless two-laser Raman thermometry to study heat dissipation in periodic porous membranes at high temperatures via lattice conduction and air-mediated losses. We find the reduction of the thermal conductivity and its temperature dependence closely correlated with the structure feature size. On the basis of two-phonon Raman spectra, we attribute this behaviour to diffuse (incoherent) phonon-boundary scattering. Furthermore, we investigate and quantify the heat dissipation via natural air-mediated cooling, which can be tuned by engineering the porosity.Nanostructuring of silicon allows acoustic phonon engineering, but the mechanism of related thermal transport in these structures is not fully understood. Here, the authors study the heat dissipation in silicon membranes with periodic nanoholes and show the importance of incoherent scattering.
In studies of the human microbiome, faecal samples are frequently used as a non-invasive proxy for the study of the intestinal microbiota. To obtain reliable insights, the need for bacterial DNA of ...high quality and integrity following appropriate faecal sample collection and preservation steps is paramount. In a study of dietary mineral balance in the context of type 2 diabetes (T2D), faecal samples were collected from healthy and T2D individuals throughout a 13-day residential trial. These samples were freeze-dried, then stored mostly at -20°C from the trial date in 2000/2001 until the current research in 2014. Given the relative antiquity of these samples (~14 years), we sought to evaluate DNA quality and comparability to freshly collected human faecal samples. Following the extraction of bacterial DNA, gel electrophoresis indicated that our DNA extracts were more sheared than extracts made from freshly collected faecal samples, but still of sufficiently high molecular weight to support amplicon-based studies. Likewise, spectrophotometric assessment of extracts revealed that they were of high quality and quantity. A subset of bacterial 16S rRNA gene amplicons were sequenced using Illumina MiSeq and compared against publicly available sequence data representing a similar cohort analysed by the American Gut Project (AGP). Notably, our bacterial community profiles were highly consistent with those from the AGP data. Our results suggest that when faecal specimens are stored appropriately, the microbial profiles are preserved and robust to extended storage periods.
We describe the Fortran code CPsuperH2.3, which incorporates the following updates compared with its predecessor CPsuperH2.0. It implements improved calculations of the Higgs-boson masses and mixing ...including stau contributions and finite threshold effects on the tau-lepton Yukawa coupling. It incorporates the LEP limits on the processes e+e−→HiZ,HiHj and the CMS limits on Hi→τ̄τ obtained from 4.6 fb−1 of data at a center-of-mass energy of 7 TeV. It also includes the decay mode Hi→Zγ and the Schiff-moment contributions to the electric dipole moments of Mercury and Radium 225, with several calculational options for the case of Mercury. These additions make CPsuperH2.3 a suitable tool for analyzing possible CP-violating effects in the MSSM in the era of the LHC and a new generation of EDM experiments.11The program may be obtained from http://www.hep.man.ac.uk/u/jslee/CPsuperH.html, or by contacting the first author at jslee@jnu.ac.kr.
Program title: CPsuperH2.3
Catalogue identifier: ADSR_v3_0
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSR_v3_0.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 24058
No. of bytes in distributed program, including test data, etc.: 158721
Distribution format: tar.gz
Programming language: Fortran77.
Computer: PC running under Linux and computers in Unix environment.
Operating system: Linux.
RAM: 32 MB
Classification: 11.1.
Does the new version supersede the previous version?: Yes
Catalogue identifier of previous version: ADSR_v2_0
Journal reference of previous version: Comput. Phys. Comm. 180(2009)312
Nature of problem:
The calculations of mass spectrum, decay widths and branching ratios of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation have been improved. The program is based on renormalization-group-improved diagrammatic calculations that include dominant higher-order logarithmic and threshold corrections, b-quark and τ-lepton Yukawa-coupling resummation effects and improved treatment of Higgs-boson pole-mass shifts. The couplings of the Higgs bosons to the Standard Model gauge bosons and fermions, to their supersymmetric partners and all the trilinear and quartic Higgs-boson self-couplings are also calculated. Also included are a full treatment of the 4×4 (2×2) neutral (charged) Higgs propagator matrix together with the center-of-mass dependent Higgs-boson couplings to gluons and photons, and an integrated treatment of several B-meson observables. The new implementations include the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon, as well as the anomalous magnetic moment of muon, (gμ−2), the top-quark decays, improved calculations of the Higgs-boson masses and mixing including stau contributions, the LEP limits, and the CMS limits on Hi→ττ̄. It also implements the decay mode Hi→Zγ and includes the corresponding Standard Model branching ratios of the three neutral Higgs bosons in the array GAMBRN(IM,IWB = 2,IH).
Solution method:
One-dimensional numerical integration for several Higgs-decay modes and EDMs, iterative treatment of the threshold corrections and Higgs-boson pole masses, and the numerical diagonalization of the neutralino mass matrix.
Reasons for new version:
Mainly to provide the full calculations of the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon as well as (gμ−2), improved calculations of the Higgs-boson masses and mixing including stau contributions, the LEP limits, the CMS limits on Hi→ττ̄, the top-quark decays, Hi→Zγ decay, and the corresponding Standard Model branching ratios of the three neutral Higgs bosons.
Summary of revisions:
Full calculations of the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon as well as (gμ−2). Improved treatment of Higgs-boson masses and mixing including stau contributions. The LEP limits. The CMS limits on Hi→ττ̄. The top-quark decays. The Hi→Zγ decay. The corresponding Standard Model branching ratios of the three neutral Higgs bosons.
Running time:
Less than 1.0 s.
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