1,506 research outputs found
Tightly Correlated X-ray/H Emitting Filaments in the Superbubble and Large-Scale Superwind of NGC 3079
Using Chandra and HST we show that X-ray and H filaments that form
the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns
at 0."8 resolution. This tight match seems to arise from cool disk gas that has
been driven by the wind, with X-rays being emitted from upstream, stand-off
bowshocks or by conductive cooling at the cloud/wind interfaces. We find that
the soft X-ray plasma has thermal and kinetic energies of
and erg
respectively, where is the filling factor of the X-ray gas and may be
small; these are comparable to the energies of the optical line-emitting gas.
X-rays are also seen from the base of the radio counterbubble that is obscured
optically by the galaxy disk, and from the nucleus (whose spectrum shows the Fe
K line). Hydrodynamical simulations reproduce the obbservations well
using large filling factors within both filament systems; assuming otherwise
seriously underestimates the mass loss in the superwind. The superbubble is
surrounded by a fainter conical halo of X-rays that fill the area delineated by
high angle, H-emitting filaments, supporting our previous assertion
that these filaments form the contact discontinuity/shock between galaxy gas
and shocked wind. About 40\arcsec (3 kpc) above the disk, an X-ray arc may
partially close beyond the bubble, but the north-east quadrant remains open,
consistent with the superwind having broken out into at least the galaxy halo.Comment: 8 pages, 3 figures, to appear in Sept. 10 Ap
Conformal smectics and their many metrics
We establish that equally spaced smectic configurations enjoy an infinite-dimensional conformal symmetry and show that there is a natural map between them and null hypersurfaces in maximally symmetric spacetimes. By choosing the appropriate conformal factor it is possible to restore additional symmetries of focal structures only found before for smectics on flat substrates
Multi-point Adjoint-Based Design of Tilt-Rotors in a Noninertial Reference Frame
Optimization of tilt-rotor systems requires the consideration of performance at multiple design points. In the current study, an adjoint-based optimization of a tilt-rotor blade is considered. The optimization seeks to simultaneously maximize the rotorcraft figure of merit in hover and the propulsive efficiency in airplane-mode for a tilt-rotor system. The design is subject to minimum thrust constraints imposed at each design point. The rotor flowfields at each design point are cast as steady-state problems in a noninertial reference frame. Geometric design variables used in the study to control blade shape include: thickness, camber, twist, and taper represented by as many as 123 separate design variables. Performance weighting of each operational mode is considered in the formulation of the composite objective function, and a build up of increasing geometric degrees of freedom is used to isolate the impact of selected design variables. In all cases considered, the resulting designs successfully increase both the hover figure of merit and the airplane-mode propulsive efficiency for a rotor designed with classical techniques
Device and method for measuring thermal conductivity of thin films
A device and method are provided for measuring the thermal conductivity of rigid or flexible, homogeneous or heterogeneous, thin films between 50 .mu.m and 150 .mu.m thick with relative standard deviations of less than five percent. The specimen is sandwiched between like material, highly conductive upper and lower slabs. Each slab is instrumented with six thermocouples embedded within the slab and flush with their corresponding surfaces. A heat source heats the lower slab and a heat sink cools the upper slab. The heat sink also provides sufficient contact pressure onto the specimen. Testing is performed within a vacuum environment (bell-jar) between 10.sup.-3 to 10.sup.-6 Torr. An anti-radiant shield on the interior surface of the bell-jar is used to avoid radiation heat losses. Insulation is placed adjacent to the heat source and adjacent to the heat sink to prevent conduction losses. A temperature controlled water circulator circulates water from a constant temperature bath through the heat sink. Fourier's one-dimensional law of heat conduction is the governing equation. Data, including temperatures, are measured with a multi-channel data acquisition system. On-line computer processing is used for thermal conductivity calculations
The rural almshouse population in Missouri
Cooperative rural research."June, 1938."This is a study of the rural almshouse in Missouri. The various types of almshouse administration and methods of inmate care are defined and described, together with the social characteristics of the inmate population. As a matter of considerable contemporary interest an analysis was made of the eligibility of inmates for old age assistance in order to determine the extent to which counties might be relieved of their inmate population through this type of public assistance. Examination of data on nearly 3,000 inmates indicated that more than one-half (52.4 per cent) were under 70 years of age which is the present minimum age limit for old age assistance. It was further determined that at least one-half of the ones eligible due to age were not likely to be approved for old age assistance since they were either physically or mentally disabled. It was concluded that less than one-fourth of the total inmate population might qualify for old age assistance and that additional provisions would be necessary if the rural counties are to be relieved of the care of their almshouse population.By C.T. Pihlblad, Arthur W. Nebel, and Joseph H. Stokes, in collaboration with Melvin W. Sneed and Cecil L. Gregory.Cooperative Rural Research ... The Agricultural Experiment Station, University of Missouri; The Rural Section, Division of Social Research, Federal Works Progress Administration; and the State Social Security Commission of Missouri Cooperating.Introduction -- Administration and control -- Personnel and management -- Almshouses and almshouse inmates -- Eligibility of inmates for old age assistance -- Consolidation of almshouses -- Suggested recommendations -- Appendix
Ruled Laguerre minimal surfaces
A Laguerre minimal surface is an immersed surface in the Euclidean space
being an extremal of the functional \int (H^2/K - 1) dA. In the present paper,
we prove that the only ruled Laguerre minimal surfaces are up to isometry the
surfaces R(u,v) = (Au, Bu, Cu + D cos 2u) + v (sin u, cos u, 0), where A, B, C,
D are fixed real numbers. To achieve invariance under Laguerre transformations,
we also derive all Laguerre minimal surfaces that are enveloped by a family of
cones. The methodology is based on the isotropic model of Laguerre geometry. In
this model a Laguerre minimal surface enveloped by a family of cones
corresponds to a graph of a biharmonic function carrying a family of isotropic
circles. We classify such functions by showing that the top view of the family
of circles is a pencil.Comment: 28 pages, 9 figures. Minor correction: missed assumption (*) added to
Propositions 1-2 and Theorem 2, missed case (nested circles having nonempty
envelope) added in the proof of Pencil Theorem 4, missed proof that the arcs
cut off by the envelope are disjoint added in the proof of Lemma
33rd New England Intercollegiate Geological Conference: October 8, 9 and 10, 1937, New York City
Excursion A-2: A Geological Traverse from the Hudson River to Long Island Sound; Excursion B-3: Paleontological Trip to the New Jersey Coastal Plain; Excursion C-1: Progressive Metamorphism of the Hudson River Series; Excursion C-2: Glacial Geology of Long Island; Excursion C-3: Engineering Projects in New York City
The SAMI Galaxy Survey: Gas Streaming and Dynamical M/L in Rotationally Supported Systems
Line-of-sight velocities of gas and stars can constrain dark matter (DM)
within rotationally supported galaxies if they trace circular orbits
extensively. Photometric asymmetries may signify non-circular motions,
requiring spectra with dense spatial coverage. Our integral-field spectroscopy
of 178 galaxies spanned the mass range of the SAMI Galaxy Survey. We derived
circular speed curves (CSCs) of gas and stars from non-parametric Diskfit fits
out to . For 12/14 with measured H I profiles, ionized gas and H I
maximum velocities agreed. We fitted mass-follows-light models to 163 galaxies
by approximating the radial starlight profile as nested, very flattened mass
homeoids viewed as a S\'ersic form. Fitting broad-band SEDs to SDSS images gave
median stellar mass/light 1.7 assuming a Kroupa IMF vs. 2.6 dynamically.
Two-thirds of the dynamical mass/light measures were consistent with
star+remnant IMFs. One-fifth required upscaled starlight to fit, hence
comparable mass of unobserved baryons and/or DM distributed similarly across
the SAMI aperture that came to dominate motions as the starlight CSC declined
rapidly. The rest had mass distributed differently from starlight. Subtracting
fits of S\'ersic profiles to 13 VIKING Z-band images revealed residual weak
bars. Near the bar PA, we assessed m = 2 streaming velocities, and found
deviations usually <30 km/s from the CSC; three showed no deviation. Thus,
asymmetries rarely influenced our CSCs despite co-located shock-indicating,
emission-line flux ratios in more than 2/3.Comment: 21 pages, 15 figures. Accepted to MNRA
Galactic-Scale Outflow and Supersonic Ram-Pressure Stripping in the Virgo Cluster Galaxy NGC 4388
The Hawaii Imaging Fabry-Perot Interferometer (HIFI) on the University of
Hawaii 2.2m telescope was used to map the Halpha and [O III] 5007 A
emission-line profiles across the entire disk of the edge-on Sb galaxy NGC
4388. We confirm a rich complex of highly ionized gas that extends ~4 kpc above
the disk of this galaxy. Low-ionization gas associated with star formation is
also present in the disk. Evidence for bar streaming is detected in the disk
component and is discussed in a companion paper (Veilleux, Bland-Hawthorn, &
Cecil 1999; hereafter VBC). Non-rotational blueshifted velocities of 50 - 250
km/s are measured in the extraplanar gas north-east of the nucleus. The
brighter features in this complex tend to have more blueshifted velocities. A
redshifted cloud is also detected 2 kpc south-west of the nucleus. The velocity
field of the extraplanar gas of NGC 4388 appears to be unaffected by the
inferred supersonic (Mach number M ~ 3) motion of this galaxy through the ICM
of the Virgo cluster. We argue that this is because the galaxy and the high-|z|
gas lie behind a Mach cone with opening angle ~ 80 degrees. The shocked ICM
that flows near the galaxy has a velocity of ~ 500 km/s and exerts insufficient
ram pressure on the extraplanar gas to perturb its kinematics. We consider
several explanations of the velocity field of the extraplanar gas. Velocities,
especially blueshifted velocities on the N side of the galaxy, are best
explained as a bipolar outflow which is tilted by > 12 degrees from the normal
to the disk. The observed offset between the extraplanar gas and the radio
structure may be due to buoyancy or refractive bending by density gradients in
the halo gas. Velocity substructure in the outflowing gas also suggests an
interaction with ambient halo gas.Comment: 29 pages including 5 figures, Latex, requires aaspp4.sty, to appear
in ApJ, 520 (July 20, 1999 issue
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