Quasiconformality and mass

We identify universal quasiconformal (walking) behaviour in non-Abelian gauge field theories based on the mass-dependent all-order beta-function introduced in arXiv:0908.1364. We find different types of walking behaviour in the presence of (partially) massive species. We employ our findings to the construction of candidate theories for dynamical electroweak symmetry breaking by walking technicolour.Comment: 16 pages, 8 figures

Quark-antiquark pair production in space-time dependent fields

Fermion-antifermion pair-production in the presence of classical fields is described based on the retarded and advanced fermion propagators. They are obtained by solving the equation of motion for the Dirac Green's functions with the respective boundary conditions to all orders in the field. Subsequently, various approximation schemes fit for different field configurations are explained. This includes longitudinally boost-invariant forms. Those occur frequently in the description of ultrarelativistic heavy-ion collisions in the semiclassical limit. As a next step, the gauge invariance of the expression for the expectation value of the number of produced fermion-antifermion pairs as a functional of said propagators is investigated in detail. Finally, the calculations are carried out for a longitudinally boost-invariant model-field, taking care of the last issue, especially.Comment: 32 pages, 8 figures, revised versio

Abradable compressor and turbine seals, volume 1

The application and advantages of abradable coatings as gas-path seals in a general aviation turbine engine were evaluated for use on the high-pressure compressor, the high-pressure turbine, and the low-pressure turbine shrouds. Topics covered include: (1) the initial selection of candidate materials for interim full-scale engine testing; (2) interim engine testing of the initially selected materials and additional candidate materials; (3) the design of the component required to adapt the hardware to permit full-scale engine testing of the most promising materials; (4) finalization of the fabrication methods used in the manufacture of engine test hardware; and (5) the manufacture of the hardware necessary to support the final full-scale engine tests

Abradable compressor and turbine seals, volume 2

The applications and advantages of abradable coatings as gas path seals in a general aviation turbofan engine were investigated. Abradable materials were evaluated for the high pressure radial compressor and the axial high and low pressure turbine shrouds

Expert consensus for respiratory physiotherapy management of mechanically ventilated adults with community-acquired pneumonia: A Delphi study

Rationale and aims: Patients with community‐acquired pneumonia (CAP) are frequently admitted to an intensive care unit. Physiotherapy may be provided to optimize respiratory function; however, there is significant variability in clinical practice and limited research directing best practice for this cohort. This study aimed to determine expert consensus for best physiotherapy practice for invasively ventilated adults with CAP. Method: A modified Delphi technique involved an international expert panel completing three rounds of an online questionnaire. The initial 35‐statement questionnaire, based on a systematic literature review and survey of current clinical practice, covered physiotherapy assessment and treatment of intubated patients with CAP. Quantitative data using Likert scales determined level of agreement, with qualitative data collected through open‐ended responses. Consensus threshold was set a priori at 70%. Items not achieving consensus were modified and new items added based on themes from qualitative data. Quantitative data were analysed descriptively, with thematic analysis used on qualitative data. Results: The panel comprised 29 international clinical and academic experts in critical care physiotherapy. Response rate was more than 95% for each round. Outcome achieved was 38 consensus statements covering assessment and treatment, with 28 statements (74%) providing consensus on recommended clinical practice, two consensus disagreement statements (7%) for what practice is not recommended, and eight statements (21%) indicating which treatments may be beneficial. Conclusion: Expert consensus regarding physiotherapy for intubated adults with CAP patients provides an evidence‐based approach to guide clinical practice. The consensus statements can also be used to guide research evaluating physiotherapy interventions for patients with CAP

Slowly decaying classical fields, unitarity, and gauge invariance

In classical external gauge fields that fall off less fast than the inverse of the evolution parameter (time) of the system the implementability of a unitary perturbative scattering operator ($S$-matrix) is not guaranteed, although the field goes to zero. The importance of this point is exposed for the counter-example of low-dimensionally expanding systems. The issues of gauge invariance and of the interpretation of the evolution at intermediate times are also intricately linked to that point.Comment: 8 pages, no figure

Silurian-Permian palaeocontinental reconstructions and circum-Atlantic tectonics

On the basis of the palaeomagnetic record, supplemented by constraints provided by faunal and tectonic information, reconstructions involving Laurentia, Baltica, Gondwana and numerous continent-like fragments and terranes within the circum-Atlantic Palaeozoic orogenic belts are made for three critical time intervals, late Silurian, early Carboniferous and late Carboniferous-early Permian, all of which bracket important phases of tectonic activity. The late Caledonian-Scandian-Acadian-Ligerian orogenies are due to the predominantly E-W final closure of Iapetus. This phase was followed in mid-Devonian times by a major sinistral megashear along the orogen which eliminated latitudinal separations and resulted in a Pangea-like assembly by the latest Devonian. The final phase involved a rotation of Gondwana with respect to the assembled Euramerican landmass, expressed as late Variscan-Hercynian dextral shear from central Europe to northeastern N America and culminating in the late Carboniferous-Permian Alleghanian orogeny in the Appalachians from New England S and in the Mauritanides

Regional trends in the timing of Alleghanian remagnetization in the Appalachians

Pole positions related to remagnetized components isolated in Appalachian limestone and redbed rock units range over about 60 m.y. of the Permian-Carboniferous apparent polar wander path for North America. Apparent ages of remagnetization are older in the southern Appalachians and younger to the north. If the remagnetizations are associated with fluids expelled during the Alleghany orogeny, then the apparent remagnetization age trend could describe the timing of thrust-sheet emplacement

Paleomagnetism of the Devonian Catskill Red Beds: Evidence for Motion of the Coastal New England-Canadian Maritime Region Relative to Cratonic North America

The natural remanent magnetizations of reddish clay stones, siltstones, and sandstones from the nearly flat lying Middle to Upper Devonian Catskill sequence of southeastern New York were analyzed with thermal, alternating field, and chemical demagnetization techniques. After removal of a low blocking temperature component along the present geomagnetic field direction a characteristic direction of magnetization was isolated: D = 172.3°, I = 1.0°, k = 116, and α_95 = 4.7° for N = 9 sites (43 samples), giving a paleomagnetic north pole at 46.8°N, 116.7°E, dp = 2.4°, and dm = 4.7°. The combined demagnetization analyses show this to be the only stable component of magnetization present in these rocks. The derived pole position agrees well with the poles reported for some Devonian limestones in Ohio, all falling near the Permian poles for North America, but disagrees with Devonian results from eastern Maine-New Brunswick and eastern Massachusetts which give poles at lower latitudes. A similar geographical grouping with similar directions is also apparent for Lower Carboniferous (Mississippian) paleomagnetic poles for North America. We interpret these and other late Paleozoic paleomagnetic data to show that the coastal Canadian Maritime-New England region was not an integral part of cratonic North America until about the Late Carboniferous. Geological considerations suggest that the Carboniferous relative motion was along transcurrent shear zones

Paleomagnetism of the Silurian-Devonian Andreas redbeds: Evidence for an Early Devonian supercontinent?

Two components of magnetization were isolated in the Silurian-Devonian Andreas redbeds of the central Appalachians of Pennsylvania (lat 40.75 degrees N, long 75.78 degrees W): a thermally distributed, synfolding B component, and a thermally discrete, pre-Alleghenian-age folding C component. The C component mean direction and associated pole position correspond to a Silurian-Devonian paleolatitude for the Andreas location of about 35 degrees S, which, in conjunction with Early Devonian results from Gondwana, is consistent with an Early Devonian supercontinent configuration