2,056 research outputs found
K-Amenability for SU(n,1)
AbstractWe show that SU(n, 1) is K-amenable by constructing a homotopy between the trivial Fredholm SU(n, 1)-module and a Fredholm SU(n, 1)-module for which the representations of SU(n, 1) are weakly contained in the left regular representation
Patient centred diagnosis: sharing diagnostic decisions with patients in clinical practice.
Patient centred diagnosis is best practised through shared decision making; an iterative dialogue between doctor and patient, whichrespects a patient’s needs, values, preferences, and circumstances.
Shared decision making for diagnostic situations differs fundamentally from that for treatment decisions. This has important implications when considering its practical application.
The nature of dialogue should be tailored to the specific diagnostic decision; scenarios with higher stakes or uncertainty usually require more detailed conversation
Hemodynamic and ADH responses to central blood volume shifts in cardiac-denervated humans
Hemodynamic responses and antidiuretic hormone (ADH) were measured during body position changes designed to induce blood volume shifts in ten cardiac transplant recipients to assess the contribution of cardiac and vascular volume receptors in the control of ADH secretion. Each subject underwent 15 min of a control period in the seated posture, then assumed a lying posture for 30 min at 6 deg head down tilt (HDT) followed by 20 min of seated recovery. Venous blood samples and cardiac dimensions (echocardiography) were taken at 0 and 15 min before HDT, 5, 15, and 30 min of HDT, and 5, 15, and 30 min of seated recovery. Blood samples were analyzed for hematocrit, plasma osmolality, plasma renin activity (PRA), and ADH. Resting plasma volume (PV) was measured by Evans blue dye and percent changes in PV during posture changes were calculated from changes in hematocrit. Heart rate (HR) and blood pressure (BP) were recorded every 2 min. Results indicate that cardiac volume receptors are not the only mechanism for the control of ADH release during acute blood volume shifts in man
Beware the recent past: a bias in spectral energy distribution modelling due to bursty star formation
We investigate how the recovery of galaxy star formation rates (SFRs) using
energy-balance spectral energy distribution (SED) fitting codes depends on
their recent star formation histories (SFHs). We use the Magphys and Prospector
codes to fit 6,706 synthetic spectral energy distributions (SEDs) of simulated
massive galaxies at from the Feedback in Realistic Environments
(FIRE) project. We identify a previously unknown systematic error in the
Magphys results due to bursty star formation: the SFR estimates of individual
galaxies can differ from the true values by as much as 1 dex, at large
statistical significance (), depending on the details of their recent
SFH. The SFRs inferred using Prospector do not exhibit this trend, likely
because unlike Magphys, Prospector uses non-parametric SFHs. We urge caution
when using Magphys, or other codes assuming parametric SFHs, to study galaxies
where the average SFR may have changed significantly over the last 100
Myr, such as those which have recently quenched their star formation or those
experiencing an ongoing burst. This concern is especially relevant, for
example, when fitting JWST observations of very high-redshift galaxies.Comment: 5 pages, 3 figures, submitted to MNRAS Letter
Beware the recent past: a bias in spectral energy distribution modelling due to bursty star formation
© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We investigate how the recovery of galaxy star formation rates (SFRs) using energy-balance spectral energy distribution (SED) fitting codes depends on their recent star formation histories (SFHs). We use the Magphys and Prospector codes to fit 6,706 synthetic spectral energy distributions of simulated massive galaxies at ), depending on the details of their recent SFH. SFRs inferred using Prospector with non-parametric SFHs do not exhibit this trend. We show that using parametric SFHs (pSFHs) causes SFR uncertainties to be underestimated by a factor of up to . Although this undoubtedly contributes to the significance of the systematic, it cannot explain the largest biases in the SFRs of the starbursting galaxies, which could be caused by details of the stochastic prior sampling or the burst implementation in the Magphys libraries. We advise against using pSFHs and urge careful consideration of starbursts when SED modelling galaxies where the SFR may have changed significantly over the last ~100 Myr, such as recently quenched galaxies, or those experiencing a burst. This concern is especially relevant, e.g. when fitting JWST observations of very high-redshift galaxies.Peer reviewe
Elliptic operators on manifolds with singularities and K-homology
It is well known that elliptic operators on a smooth compact manifold are
classified by K-homology. We prove that a similar classification is also valid
for manifolds with simplest singularities: isolated conical points and fibered
boundary. The main ingredients of the proof of these results are: an analog of
the Atiyah-Singer difference construction in the noncommutative case and an
analog of Poincare isomorphism in K-theory for our singular manifolds.
As applications we give a formula in topological terms for the obstruction to
Fredholm problems on manifolds with singularities and a formula for K-groups of
algebras of pseudodifferential operators.Comment: revised version; 25 pages; section with applications expande
Density-dependent invariance, dimensionless life-histories and the energy-equivalence rule
It is suggested that Damuth’s ‘energy-equivalence rule’ for mammal populations follows from a particular population dynamics invariance rule, one which leads to similar population dynamics when various species are viewed in a particular density and rate-of-change space
Conceptual learning : the priority for higher education
The common sense notion of learning as the all-pervasive acquisition of new behaviour and knowledge, made vivid by experience, is an incomplete characterisation, because it assumes that the learning of behaviour and the learning of knowledge are indistinguishable, and that acquisition constitutes learning without reference to transfer. A psychological level of analysis is used to argue that conceptual learning should have priority in higher education
Office-based optical coherence tomographic imaging of human vocal cords
Optical coherence tomography (OCT) is an evolving noninvasive imaging modality and has been used to image the larynx during surgical endoscopy. The design of an OCT sampling device capable of capturing images of the human larynx during a typical office based laryngoscopy examination is discussed. Both patient’s and physician\u27s movements were addressed. In vivo OCT imaging of the human larynx is demonstrated. Though the long focal length limits the lateral resolution of the image, the basement membrane can still be readily distinguished. Office-based OCT has the potential to guide surgical biopsies, direct therapy, and monitor disease. This is a promising imaging modality to study the larynx
An algebraic approach to problems with polynomial Hamiltonians on Euclidean spaces
Explicit expressions are given for the actions and radial matrix elements of
basic radial observables on multi-dimensional spaces in a continuous sequence
of orthonormal bases for unitary SU(1,1) irreps. Explicit expressions are also
given for SO(N)-reduced matrix elements of basic orbital observables. These
developments make it possible to determine the matrix elements of polynomial
and a other Hamiltonians analytically, to within SO(N) Clebsch-Gordan
coefficients, and to select an optimal basis for a particular problem such that
the expansion of eigenfunctions is most rapidly convergent.Comment: 19 pages, 8 figure
- …