2,231 research outputs found
What is the origin of the Scottish populations of the European endemic Cherleria sedoides (Caryophyllaceae)?
Cherleria sedoides L. (Minuartia sedoides (L.) Hiern) is a montane perennial which, with some species in Minuartia sect. Spectabiles, is more closely related to Scleranthus than to other Minuartia species and is therefore best restored to the reinstated and redefined genus Cherleria. Reconstruction of the ancestral area of the clade containing C. sedoides suggests that it evolved in the Alps or the Balkan peninsula. The species now has an unusual distribution, being present in the mountains of southern Europe and Scotland but absent from the Arctic. Three historical scenarios that might have led to the presence of the species in Scotland are outlined and tested by a molecular analysis comparing Scottish populations with populations from the Pyrenees and the Alps. The sampled populations show little variation in internal transcribed spacer (ITS)/external transcribed spacer (ETS) but much more in cpDNA. The latter reveals a major division between some Alpine material and the other Alpine, Pyrenean and Scottish plants. Once the anomalous Alpine haplotypes are excluded, Scottish populations are at least as variable as those from the Alps and Pyrenees, and are closely related to both. We conclude that they have not undergone a long period of isolation, nor have they originated by recent, long-distance dispersal from the Alps or Pyrenees. They appear to be derived from a metapopulation that was probably widespread at the last glacial maximum (LGM) and gave rise to the Alpine, Pyrenean and Scottish plants
Design and Development of a Dynamically Deforming Leading Edge Airfoil for Unsteady Flow Control
ICIASF '97 RECORD, IEEE Publication No. 97CH36121, pp. 132-140.A novel approach to unsteady flow separation and dynamic stall control using a dynamically deforming leading
edge airfoil is described. The design details of a carbon-fiber composite skin airfoil having a thickness of
0.002 in. at the leading edge and capable of deforming at 20 Hz in unsteady flow at freestream Mach numbers
of up to 0.45, are discussed. Implementation of the scheme at model scales places extraordinary demands on
the design, material and fabrication of such an airfoil. Rate scaling further requires very-rapid-response
instrumental ion, measurement techniques and data acquisition schemes. The special instrumentation control
system developed for these experiments as well as the fluid dynamic results of successful flow control that
was achieved using this method, are also discussed.U.S. Army Research Office ARO MIPR 133-94, ARO 32480.11-EGU.S. Army Research Office ARO MIPR 133-94, ARO 32480.11-E
Identification of Patient Safety Improvement Targets in Successful Vascular and Endovascular Procedures: Analysis of 251 hours of Complex Arterial Surgery
AbstractObjectivesTo investigate failures in patient safety for patients undergoing vascular and endovascular procedures to guide future quality and safety interventions.DesignSingle centre prospective observational study.Methods66 procedures (17 thoracoabdominal and 23 abdominal aortic aneurysms, 4 carotid and 22 limb procedures) were observed prospectively over a 9-month period (251 h operating time) by two trained observers. Event logs were recorded for each procedure. Two blinded experts identified and independently categorised failures into 22 types (using a validated category tool) and severity (5-point scale). Data are expressed as median (range). Statistical analysis was performed using Mann–Whitney U, Kruskal–Wallis and Spearman’s Rank tests.Results1145 failures were identified with good inter-assessor reliability (Cronbach’s alpha 0.844). The commonest failure types related to equipment (including unavailability, configuration and other failures) (269/1145 [23.5%]) and communication (240/1145 [21.0%]). A comparatively lower number of technical and psychomotor failures were identified (103 [9.0%]). The number of failures correlated with procedure duration (rho = 0.695, p < 0.001) but not anatomical site of the procedure or pathology of the disease process. Failure rate was higher in patients undergoing combined surgical/endovascular procedures compared to open surgery (median 5.7/h [IQR 4.2–8.1] vs 3.0/h [2.5–3.5]; p < 0.001). The severity of failures was similar (1.5/5 [1–2] vs 1/5 [1–2] respectively; p = 0.095). For combined procedures, failure rates were significantly higher during the endovascular phase (9.6/h [7.5–13.7]) compared to the non-endovascular phase (3.0/h [1.0–5.0]; p < 0.001).ConclusionsFailures in patient safety are common during complex arterial procedures. Few failures were severe, although minor failures during critical stages and accumulation of multiple minor failures may potentially be important. Failures occurred especially during the endovascular phase and were often related to equipment or communication aspects. Interventions to improve procedural safety and quality of care should primarily target these specific areas
Cirurgia muco-gengival: análise da variação da profundidade do sulco géngivo-labial
The author presents a clinical research desling with mucogingival surgery, two surgical produceres were used to deepen the labial fornix. The final results were roentgenographically measured. Both methds seemed to be efficient for the deepening of the fornix as well as the roentgenographical meansurements.O autor apresenta uma pesquisa clínica sobre cirurgia muco-gengival na qual foram empregadas duas técnicas de aprofundamento de sulco géngivo-labial. A manutenção dos resultados obtidos foi mensurada radiograficamente. Chegou-se a conclusão de que e reposição apical do retalho e a desnudação perióstica são métodos de sulco, assim como a mensuração radiográfica mostrou-se satisfatória como método de avaliação
Looking into the matter of light-quark hadrons
In tackling QCD, a constructive feedback between theory and extant and
forthcoming experiments is necessary in order to place constraints on the
infrared behaviour of QCD's \beta-function, a key nonperturbative quantity in
hadron physics. The Dyson-Schwinger equations provide a tool with which to work
toward this goal. They connect confinement with dynamical chiral symmetry
breaking, both with the observable properties of hadrons, and hence provide a
means of elucidating the material content of real-world QCD. This contribution
illustrates these points via comments on: in-hadron condensates; dressed-quark
anomalous chromo- and electro-magnetic moments; the spectra of mesons and
baryons, and the critical role played by hadron-hadron interactions in
producing these spectra.Comment: 11 pages, 7 figures. Contribution to the Proceedings of "Applications
of light-cone coordinates to highly relativistic systems - LIGHTCONE 2011,"
23-27 May, 2011, Dallas. The Proceedings will be published in Few Body
System
Survey of nucleon electromagnetic form factors
A dressed-quark core contribution to nucleon electromagnetic form factors is
calculated. It is defined by the solution of a Poincare' covariant Faddeev
equation in which dressed-quarks provide the elementary degree of freedom and
correlations between them are expressed via diquarks. The nucleon-photon vertex
involves a single parameter; i.e., a diquark charge radius. It is argued to be
commensurate with the pion's charge radius. A comprehensive analysis and
explanation of the form factors is built upon this foundation. A particular
feature of the study is a separation of form factor contributions into those
from different diagram types and correlation sectors, and subsequently a
flavour separation for each of these. Amongst the extensive body of results
that one could highlight are: r_1^{n,u}>r_1^{n,d}, owing to the presence of
axial-vector quark-quark correlations; and for both the neutron and proton the
ratio of Sachs electric and magnetic form factors possesses a zero.Comment: 43 pages, 17 figures, 12 tables, 5 appendice
P32 Interspecies comparison of meniscus properties in human, sheep and rabbit and development of animal models for meniscus repair
An Absolute Measurement of Neutron Flux Using Calorimetry
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Abstract kinetic equations with positive collision operators
We consider "forward-backward" parabolic equations in the abstract form , , where and are
operators in a Hilbert space such that , , and
. The following theorem is proved: if the operator is
similar to a self-adjoint operator, then associated half-range boundary
problems have unique solutions. We apply this theorem to corresponding
nonhomogeneous equations, to the time-independent Fokker-Plank equation , , , as well as to
other parabolic equations of the "forward-backward" type. The abstract kinetic
equation , where is injective and
satisfies a certain positivity assumption, is considered also.Comment: 20 pages, LaTeX2e, version 2, references have been added, changes in
the introductio
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