58 research outputs found
Flight test results from a supercritical mission adaptive wing with smooth variable camber
The mission adaptive wing (MAW) consisted of leading- and trailing-edge variable-camber surfaces that could be deflected in flight to provide a near-ideal wing camber shape for any flight condition. These surfaces featured smooth, flexible upper surfaces and fully enclosed lower surfaces, distinguishing them from conventional flaps that have discontinuous surfaces and exposed or semiexposed mechanisms. Camber shape was controlled by either a manual or automatic flight control system. The wing and aircraft were extensively instrumented to evaluate the local flow characteristics and the total aircraft performance. This paper discusses the interrelationships between the wing pressure, buffet, boundary-layer and flight deflection measurement system analyses and describes the flight maneuvers used to obtain the data. The results are for a wing sweep of 26 deg, a Mach number of 0.85, leading and trailing-edge cambers (delta(sub LE/TE)) of 0/2 and 5/10, and angles of attack from 3.0 deg to 14.0 deg. For the well-behaved flow of the delta(sub LE/TE) = 0/2 camber, a typical cruise camber shape, the local and global data are in good agreement with respect to the flow properties of the wing. For the delta(sub LE/TE) = 5/10 camber, a maneuvering camber shape, the local and global data have similar trends and conclusions, but not the clear-cut agreement observed for cruise camber
First Simultaneous Optical and EUV Observations of the Quasi-Coherent Oscillations of SS Cygni
Using EUV photometry obtained with the Extreme Ultraviolet Explorer (EUVE)
satellite and UBVR optical photometry obtained with the 2.7-m telescope at
McDonald Observatory, we have detected quasi-coherent oscillations (so-called
``dwarf nova oscillations'') in the EUV and optical flux of the dwarf nova SS
Cygni during its 1996 October outburst. There are two new results from these
observations. First, we have for the first time observed ``frequency
doubling:'' during the rising branch of the outburst, the period of the EUV
oscillation was observed to jump from 6.59 s to 2.91 s. Second, we have for the
first time observed quasi-coherent oscillations simultaneously in the optical
and EUV. We find that the period and phase of the oscillations are the same in
the two wavebands, finally confirming the long-held assumption that the periods
of the optical and EUV/soft X-ray oscillations of dwarf novae are equal. The
UBV oscillations can be simply the Rayleigh-Jeans tail of the EUV oscillations
if the boundary layer temperature kT_bb <~ 15 eV and hence the luminosity L_bb
>~ 1.2e34 (d/75 pc)^2 erg/s (comparable to that of the accretion disk).
Otherwise, the lack of a phase delay between the EUV and optical oscillations
requires that the optical reprocessing site lies within the inner third of the
accretion disk. This is strikingly different from other cataclysmic variables,
where much or all of the disk contributes to the optical oscillations.Comment: 16 pages including 3 tables and 4 encapsulated postscript figures;
LaTeX format, uses aastex.cls; accepted on 2001 August 2 for publication in
The Astrophysical Journa
The Masses and Evolutionary State of the Stars in the Dwarf Nova SS Cygni
The dwarf nova SS Cygni is a close binary star consisting of a K star transferring mass to a white dwarf by way of an accretion disk. We have obtained new spectroscopic observations of SS Cyg with the Hobby-Eberly Telescope (HET). Fits of synthetic spectra for Roche-lobe-filling stars to the absorption-line spectrum of the K star yield the amplitude of the K star's radial velocity curve and the mass ratio: K_{K} = 162.5 +/- 1.0 km/s and q= M_{K} /M_{wd} = 0.685 +/- 0.015. The fits also show that the accretion disk and white dwarf contribute a fraction f = 0.535 +/- 0.075 of the total flux at 5500 angstroms. Taking the weighted average of our results with previously published results obtained using similar techniques, we find = 163.7 +/- 0.7 km/s and = 0.683 +/- 0.012. The orbital light curve of SS Cyg shows an ellipsoidal variation diluted by light from the disk and white dwarf. From an analysis of the ellipsoidal variations we limit the orbital inclination to the range 45 deg. <= i <= 56 deg. The derived masses of the K star and white dwarf are M_{K} = 0.55 +/- 0.13 M_sun and M_{wd} = 0.81 +/- 0.19 M_sun, where the uncertainties are dominated by systematic errors in the orbital inclination. The K star in SS Cyg is 10% to 50% larger than an unevolved star with the same mass and thus does not follow the mass-radius relation for Zero-Age Main-Sequence stars; nor does it follow the ZAMS mass/spectral-type relation. Its mass and spectral type are, however, consistent with models in which the core hydrogen has been significantly depleted
1966: Abilene Christian College Bible Lectures - Full Text
THE BIBLE TODAY
Being the Abilene Christian College Annual Bible Lectures 1966
Price: $3.95
Published by
ABILENE CHRISTIAN COLLEGE STUDENTS EXCHANGE
ACC Station Abilene, Texa
The Dwarf Novae During Quiescence
We present a synthetic spectral analysis of nearly the entire FUV IUE archive
of spectra of DNe in or near quiescence. We have examined all of the systems
for which S/N permitted an analysis. The study includes 53 systems of all DN
subtypes both above and below the period gap. The spectra were uniformly
analyzed using synthetic spectral codes for optically thick accretion disks and
stellar photospheres along with the best-available distance measurements or
estimates. We present newly determined approximate WD temperatures or upper
limits and estimated accretion rates. The average temperature of WDs in DNe
below the period gap is ~18,000K. For WDs in DNe above the period gap, the
average WD temperature is ~26,000K. There is a flux component, in addition to a
WD photosphere, which contributes >60% of the flux in the FUV in 53% of the
quiescent DNe in this study. We find that for 41% of the DNe in our sample, a
WD photosphere provides >60% of the FUV flux. Accretion rates estimated from
the FUV alone for the sample of DNe during quiescence ranged from 10^-12
Msun/yr to 10^-10 Msun/yr.The additional flux component is almost certainly not
an optically thick accretion disk since, according to the disk instability
model, the disk should be optically thin and too cool during DN quiescence to
be a significant FUV continuum emitter. Among the candidates for the second
component of FUV light are the quiescent inner disk, a hot equatorial accretion
belt, and a hot rotating ring. The implications of our study for disk accretion
physics and CV evolution are discussed.Comment: 36 pages, 3 tables, 8 figures, final accepted version of manuscrip
Superhumps in Cataclysmic Binaries. XXIV. Twenty More Dwarf Novae
We report precise measures of the orbital and superhump period in twenty more
dwarf novae. For ten stars, we report new and confirmed spectroscopic periods -
signifying the orbital period P_o - as well as the superhump period P_sh. These
are GX Cas, HO Del, HS Vir, BC UMa, RZ Leo, KV Dra, KS UMa, TU Crt, QW Ser, and
RZ Sge. For the remaining ten, we report a medley of P_o and P_sh measurements
from photometry; most are new, with some confirmations of previous values.
These are KV And, LL And, WX Cet, MM Hya, AO Oct, V2051 Oph, NY Ser, KK Tel, HV
Vir, and RX J1155.4-5641.
Periods, as usual, can be measured to high accuracy, and these are of special
interest since they carry dynamical information about the binary. We still have
not quite learned how to read the music, but a few things are clear. The
fractional superhump excess epsilon [=(P_sh-P_o)/P_o] varies smoothly with P_o.
The scatter of the points about that smooth curve is quite low, and can be used
to limit the intrinsic scatter in M_1, the white dwarf mass, and the
mass-radius relation of the secondary. The dispersion in M_1 does not exceed
24%, and the secondary-star radii scatter by no more than 11% from a fixed
mass-radius relation. For the well-behaved part of epsilon(P_o) space, we
estimate from superhump theory that the secondaries are 18+-6% larger than
theoretical ZAMS stars. This affects some other testable predictions about the
secondaries: at a fixed P_o, it suggests that the secondaries are (compared
with ZAMS predictions) 40+-14% less massive, 12+-4% smaller, 19+-6% cooler, and
less luminous by a factor 2.5(7). The presence of a well-defined mass-radius
relation, reflected in a well-defined epsilon(P_o) relation, strongly limits
effects of nuclear evolution in the secondaries.Comment: PDF, 62 pages, 7 tables, 21 figures; accepted, in press, to appear
November 2003, PASP; more info at http://cba.phys.columbia.edu
Haploidentical vs. sibling, unrelated, or cord blood hematopoietic cell transplantation for acute lymphoblastic leukemia
The role of haploidentical hematopoietic cell transplantation (HCT) using posttransplant cyclophosphamide (PTCy) for acute lymphoblastic leukemia (ALL) is being defined. We performed a retrospective, multivariable analysis comparing outcomes of HCT approaches by donor for adults with ALL in remission. The primary objective was to compare overall survival (OS) among haploidentical HCTs using PTCy and HLA-matched sibling donor (MSD), 8/8 HLAmatched unrelated donor (MUD), 7 /8 HLA-MUD, or umbilical cord blood (UCB) HCT. Comparing haploidentical HCT to MSD HCT, we found that OS, leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and acute graft-versus-host disease (aGVHD) were not different but chronic GVHD (cGVHD) was higher in MSD HCT. Compared with MUD HCT, OS, LFS, and relapse were not different, but MUD HCT had increased NRM (hazard ratio [HR], 1.42; P = .02), grade 3 to 4 aGVHD (HR, 1.59; P = .005), and cGVHD. Compared with 7/8 UD HCT, LFS and relapse were not different, but 7/8 UD HCT had worse OS (HR, 1.38; P = .01) and increased NRM (HR, 2.13; P <_ .001), grade 3 to 4 aGVHD (HR, 1.86; P = .003), and cGVHD (HR, 1.72; P <_ .001). Compared with UCB HCT, late OS, late LFS, relapse, and cGVHD were not different but UCB HCT had worse early OS (<_18 months; HR, 1.93; P < .001), worse early LFS (HR, 1.40; P = .007) and increased incidences of NRM (HR, 2.08; P < .001) and grade 3 to 4 aGVHD (HR, 1.97; P < .001). Haploidentical HCT using PTCy showed no difference in survival but less GVHD compared with traditional MSD and MUD HCT and is the preferred alternative donor HCT option for adults with ALL in complete remission
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Does subtype matter? Assessing the effects of maltreatment on functioning in preadolescent youth in out-of-home care
a b s t r a c t Objectives: Attempts to understand the effects of maltreatment subtypes on childhood functioning are complicated by the fact that children often experience multiple subtypes. This study assessed the effects of maltreatment subtypes on the cognitive, academic, and mental health functioning of preadolescent youth in out-of-home care using both "variable-centered" and "person-centered" statistical analytic approaches to modeling multiple subtypes of maltreatment. Methods: Participants included 334 preadolescent youth (ages 9-11) placed in out-ofhome care due to maltreatment. The occurrence and severity of maltreatment subtypes (physical abuse, sexual abuse, physical neglect, and supervisory neglect) were coded from child welfare records. The relationships between maltreatment subtypes and children's cognitive, academic, and mental health functioning were evaluated with the following approaches: (1) "Variable-centered" analytic methods: a. Regression approach: Multiple regression was used to estimate the effects of each maltreatment subtype (separate analyses for occurrence and severity), controlling for the other subtypes. b. Hierarchical approach: Contrast coding was used in regression analyses to estimate the effects of discrete maltreatment categories that were assigned based on a subtype occurrence hierarchy (sexual abuse > physical abuse > physical neglect > supervisory neglect). (2) "Person-centered" analytic method: Latent class analysis was used to group children with similar maltreatment severity profiles into discrete classes. The classes were then compared to determine if they differed in terms of their ability to predict functioning. Results: The approaches identified similar relationships between maltreatment subtypes and children's functioning. The most consistent findings indicated that maltreated children who experienced physical or sexual abuse were at highest risk for caregiver-reported externalizing behavior problems, and those who experienced physical abuse and/or physical & Neglect 36 (2012) 633-644 neglect were more likely to have higher levels of caregiver-reported internalizing problems. Children experiencing predominantly low severity supervisory neglect had relatively better functioning than other maltreated youth. Conclusions: Many of the maltreatment subtype differences identified within the maltreated sample in the current study are consistent with those from previous research comparing maltreated youth to non-maltreated comparison groups. Results do not support combining supervisory and physical neglect. The "variable-centered" and "person-centered" analytic approaches produced complementary results. Advantages and disadvantages of each approach are discussed
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