590 research outputs found
Transcutaneous measurement of volume blood flow
Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated
Experimental evidence of a natural parity state in Mg and its impact to the production of neutrons for the s process
We have studied natural parity states in Mg via the
Ne(Li,d)Mg reaction. Our method significantly improves the
energy resolution of previous experiments and, as a result, we report the
observation of a natural parity state in Mg. Possible spin-parity
assignments are suggested on the basis of published -ray decay
experiments. The stellar rate of the Ne(,)Mg
reaction is reduced and may give rise to an increase in the production of
s-process neutrons via the Ne(,n)Mg reaction.Comment: Published in PR
Quantifying Resonant Structure in NGC 6946 from Two-dimensional Kinematics
We study the two-dimensional kinematics of the H-alpha-emitting gas in the
nearby barred Scd galaxy, NGC 6946, in order to determine the pattern speed of
the primary m=2 perturbation mode. The pattern speed is a crucial parameter for
constraining the internal dynamics, estimating the impact velocities of the
gravitational perturbation at the resonance radii, and to set up an
evolutionary scenario for NGC 6946. Our data allows us to derive the best
fitting kinematic position angle and the geometry of the underlying gaseous
disk, which we use to derive the pattern speed using the Tremaine-Weinberg
method. We find a main pattern speed Omega_p=22 km/s/kpc, but our data clearly
reveal the presence of an additional pattern speed Omega_p=47 km/s/kpc in a
zone within 1.25 kpc of the nucleus. Using the epicyclic approximation, we
deduce the location of the resonance radii and confirm that inside the outer
Inner Lindblad Resonance radius of the main oval, a primary bar has formed
rotating at more than twice the outer pattern speed. We further confirm that a
nuclear bar has formed inside the Inner Lindblad Resonance radius of the
primary bar, coinciding with the inner Inner Lindblad Resonance radius of the
large-scale m=2 mode oval.Comment: Accepted for publication in ApJ Letter
Spatially explicit species distribution models: A missed opportunity in conservation planning?
Aim: Systematic conservation planning is vital for allocating protected areas given the spatial distribution of conservation features, such as species. Due to incomplete species inventories, species distribution models (SDMs) are often used for predicting species habitat suitability and species probability of occurrence. Currently, SDMs mostly ignore spatial dependencies in species and predictor data. Here, we provide a comparative evaluation of how accounting for spatial dependencies, that is, autocorrelation, affects the delineation of optimized protected areas. Location: Southeast Australia, Southeast U.S. Continental Shelf, Danube River Basin. Methods: We employ Bayesian spatially explicit and non-spatial SDMs for terrestrial, marine and freshwater species, using realm-specific planning unit shapes (grid, hexagon and subcatchment, respectively). We then apply the software gurobi to optimize conservation plans based on species targets derived from spatial and non-spatial SDMs (10% 50% each to analyse sensitivity), and compare the delineation of the plans. Results: Across realms and irrespective of the planning unit shape, spatially explicit SDMs (a) produce on average more accurate predictions in terms of AUC, TSS, sensitivity and specificity, along with a higher species detection probability. All spatial optimizations meet the species conservation targets. Spatial conservation plans that use predictions from spatially explicit SDMs (b) are spatially substantially different compared to those that use non-spatial SDM predictions, but (c) encompass a similar amount of planning units. The overlap in the selection of planning units is smallest for conservation plans based on the lowest targets and vice versa. Main conclusions: Species distribution models are core tools in conservation planning. Not surprisingly, accounting for the spatial characteristics in SDMs has drastic impacts on the delineation of optimized conservation plans. We therefore encourage practitioners to consider spatial dependencies in conservation features to improve the spatial representation of future protected areas. © 2019 The Authors. Diversity and Distributions Published by John Wiley and Sons LtdThis study was funded by the European Unionâs Horizon 2020 research and innovation programme under grant agreement No. 642317. SDL has received funding from the European Unionâs Horizon 2020 research and innovation programme under the Marie SkĆodowskaâCurie grant agreement No. 748625, and SCJ from the German Federal Ministry of Education and Research (BMBF) for the âGLANCEâ project (Global Change Effects in River Ecosystems; 01 LN1320A). We wish to thank Gwen Iacona and two anonymous referees for their constructive comments on an earlier version of the manuscript
Atomic and Molecular Gas Components in Spiral Galaxies of the Virgo Cluster
Based on two models, we investigate the molecular-to-atomic gas ratio in
Virgo cluster galaxies in comparison with field galaxies. We show that the
enhanced metallicity for cluster members and the ram pressure stripping of
atomic gas from the disk periphery cannot fully explain the observed gas
component ratios. The additional environmental factors affecting the
interstellar medium and leading to an increase in the molecular gas fraction
should be taken into account for cluster galaxies.Comment: 11 pages, 4 figure
The rapid formation a large rotating disk galaxy three billion years after the Big Bang
[Abridged] Over the past two decades observations and theoretical simulations
have established a global frame-work of galaxy formation and evolution in the
young Universe. Galaxies formed as baryonic gas cooled at the centres of
collapsing dark matter halos. Mergers of halos led to the build up of galaxy
mass. A major step forward in understanding these issues requires well resolved
physical information on individual galaxies at high redshift. Here we report
adaptive optics, spectroscopic observations of a representative luminous star
forming galaxy when the Universe was only twenty percent of its age. The
superior angular resolution of these data reveals the physical and dynamical
properties of a high redshift galaxy in unprecedented detail. A large and
massive rotating proto-disk is channelling gas towards a growing central
stellar bulge hosting an accreting massive black hole.Comment: Narure, accepted (Released Aug 17th
First Case Start Times for Vascular Surgery
Problem/Impact Statement:
85% of first cases at Maine Medical Center for Vascular Surgery start late. According to one study done by Aurora Health Care; of 5,500 first case surgeries, 88% of them started late. The impact of this is far reaching. It is not in alignment with MMC value of Patient Centered Care because the patient becomes dissatisfied waiting to be brought in to surgery , they are fasting for longer than anticipated, and being away from their family while they wait causing anxiety. The financial impact is $1995 for each 1â2 hr. of O.R. time. Furthermore, this may result in elective cases being canceled, late cases create a back log of cases to be done, the hospital loses potential revenue, and staff stay later causing overtime accrual
Gravitational stability and dynamical overheating of stellar disks of galaxies
We use the marginal stability condition for galactic disks and the stellar
velocity dispersion data published by different authors to place upper limits
on the disk local surface density at two radial scalelengths .
Extrapolating these estimates, we constrain the total mass of the disks and
compare these estimates to those based on the photometry and color of stellar
populations. The comparison reveals that the stellar disks of most of spiral
galaxies in our sample cannot be substantially overheated and are therefore
unlikely to have experienced a significant merging event in their history. The
same conclusion applies to some, but not all of the S0 galaxies we consider.
However, a substantial part of the early type galaxies do show the stellar
velocity dispersion well in excess of the gravitational stability threshold
suggesting a major merger event in the past. We find dynamically overheated
disks among both seemingly isolated galaxies and those forming pairs. The ratio
of the marginal stability disk mass estimate to the total galaxy mass within
four radial scalelengths remains within a range of 0.4---0.8. We see no
evidence for a noticeable running of this ratio with either the morphological
type or color index.Comment: 25 pages, 5 figures, accepted to Astronomy Letter
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