81 research outputs found
Three-Dimensional Comparison in Palatal Forms Between Modified Presurgical Nasoalveolar Molding Plate and Hotz's Plate Applied to the Infants With Unilateral Cleft Lip and Palate
AbstractThe presurgical nasoalveolar molding plate appliance with stent (PNAM) extended from the palatal molding plate; to correct the nostril shape of infants with cleft lip and palate is well known. The PNAM appliance is based on the finding that a high degree of plasticity is maintained in the cartilage of infants during the first 6 weeks after birth. However, on the current PNAM protocol described by Grayson et al. the nasal stent is supposed to be an adjunct to the palatal molding plate after reducing the severity of the alveolar cleft width. We have used the modified Hotz's plate from the setup model and built up the nasal stent even before reducing the severity of the alveolar deformity. In this study we assess the effects of the modified Hotz's plate and the modified PNAM appliance for the alveolar and palatal form. The lateral deviation of the incisal point, the width of the palatal cleft, and the degree of curvature of the palatal vault were first evaluated on plaster models. The PNAM group is smaller on the lateral deviation of the incisal point than the modified Hotz's group. The decreased average width of the palatal cleft and curvature of the palate, was almost the same in both the modified Hotz's and PNAM groups. In comparison with the modified Hotz's plate, the modified PNAM appliance also improves the molding of the alveolar segments and reduces cleft width
Infrared spectroscopic confirmation of z~2 photometrically-selected obscured quasars
The census of obscured quasar populations is incomplete, and remains a major
unsolved problem, especially at higher redshifts, where we expect a greater
density of galaxy formation and quasar activity. We present Gemini GNIRS
near-infrared spectroscopy of 24 luminous obscured quasar candidates from the
Sloan Digital Sky Survey's Stripe 82 region. The targets were photometrically
selected using a WISE/W4 selection technique that is optimized to identify
IR-bright and heavily-reddened/optically-obscured targets at . We detect
emission lines of , , and/or in 23
sources allowing us to measure spectroscopic redshifts in the range
with bolometric luminosities spanning erg s. We
observe broad km s Balmer emissions with large ratios, and we directly observe a heavily reddened
rest-frame optical continuum in several sources, suggesting high extinction
( mag). Our observations demonstrate that such optical/infrared
photometric selection successfully recovers high-redshift obscured quasars. The
successful identification of previously undetected red, obscured high-redshift
quasar candidates suggests that there are more obscured quasars yet to be
discovered.Comment: Accepted by MNRAS, 13 pages, 8 figures, 2 table
High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 1, data analysis and results
High-resolution broadband spectroscopy at near-infrared wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar. Observations of stars were performed with the “TEDI” interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec near-infrared echelle spectrograph. These are the first multidelay EDI demonstrations on starlight, as earlier measurements used a single delay or laboratory sources. We demonstrate very high (10×) resolution boost, from original 2700 to 27,000 with current set of delays (up to 3 cm), well beyond the classical limits enforced by the slit width and detector pixel Nyquist limit. Significantly, the EDI used with multiple delays rather than a single delay as used previously yields an order of magnitude or more improvement in the stability against native spectrograph point spread function (PSF) drifts along the dispersion direction. We observe a dramatic (20×) reduction in sensitivity to PSF shift using our standard processing. A recently realized method of further reducing the PSF shift sensitivity to zero is described theoretically and demonstrated in a simple simulation which produces a 350× times reduction. We demonstrate superb rejection of fixed pattern noise due to bad detector pixels—EDI only responds to changes in pixel intensity synchronous to applied dithering. This part 1 describes data analysis, results, and instrument noise. A section on theoretical photon limited sensitivity is in a companion paper, part 2
Cold Mode Gas Accretion on Two Galaxy Groups at z2
We present Keck Cosmic Web Imager (KCWI) integral field spectroscopy (IFS)
observations of rest-frame UV emission lines , C IV 1548 \AA, 1550\AA and He II 1640 \AA observed in the circumgalactic
medium (CGM) of two radio-loud quasar host galaxies. We detect extended
emission on 80-90 kpc scale in in both systems with C IV, and He
II emission also detected out to 30-50 kpc. All emission lines show kinematics
with a blue and redshifted gradient pattern consistent with velocities seen in
massive dark matter halos and similar to kinematic patterns of inflowing gas
seen in hydrodynamical simulations. Using the kinematics of both resolved emission and absorption, we can confirm that both kinematic
structures are associated with accretion. Combining the KCWI data with
molecular gas observations with Atacama Large Millimeter/submillimeter Array
(ALMA) and high spatial resolution of ionized gas with Keck OSIRIS, we find
that both quasar host galaxies reside in proto-group environments at . We
estimate M of warm-ionized gas within 30-50 kpc from
the quasar that is likely accreting onto the galaxy group. We estimate inflow
rates of 60-200 Myr, within an order of magnitude of the outflow
rates in these systems. In the 4C 09.17 system, we detect narrow gas streams
associated with satellite galaxies, potentially reminiscent of ram-pressure
stripping seen in local galaxy groups and clusters. We find that the quasar
host galaxies reside in dynamically complex environments, with ongoing mergers,
gas accretion, ISM stripping, and outflows likely playing an important role in
shaping the assembly and evolution of massive galaxies at cosmic noon.Comment: 24 pages, 11 figures, 6 tabes. Accepted for publication in MNRA
Faulting structure above the Main Himalayan Thrust as shown by relocated aftershocks of the 2015 Mw7.8 Gorkha, Nepal, earthquake
The 25 April 2015, Mw7.8 Gorkha, Nepal, earthquake ruptured a shallow section of the Indian‐Eurasian plate boundary by reverse faulting with NNE‐SSW compression, consistent with the direction of current Indian‐Eurasian continental collision. The Gorkha main shock and aftershocks were recorded by permanent global and regional arrays and by a temporary local broadband array near the China‐Nepal border deployed prior to the Gorkha main shock. We relocate 272 earthquakes with Mw>3.5 by applying a multiscale double‐difference earthquake relocation technique to arrival times of direct and depth phases recorded globally and locally. We determine a well‐constrained depth of 18.5 km for the main shock hypocenter which places it on the Main Himalayan Thrust (MHT). Many of the aftershocks at shallower depths illuminate faulting structure in the hanging wall with dip angles that are steeper than the MHT. This system of thrust faults of the Lesser Himalaya may accommodate most of the elastic strain of the Himalayan orogeny.Key PointsWe relocate the 2015 Gorkha earthquakes using teleseismic and regional waveformsThe main shock is located on the horizontal Main Himalaya Thrust (MHT) at a depth of 18.5 kmAftershocks show faulting structure in the hanging wall above the MHTPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135634/1/grl53895.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135634/2/grl53895_am.pd
Unresolved z~8 point sources and their impact on the bright end of the galaxy luminosity function
The distribution and properties of the first galaxies and quasars are
critical pieces of the puzzle in understanding galaxy evolution and cosmic
reionization. Previous studies have often excluded unresolved sources as
potential low redshift interlopers. We combine broadband color and photometric
redshift analysis with morphological selections to identify a robust sample of
candidates consistent with unresolved point sources at redshift using
deep Hubble Space Telescope images. We also examine G141 grism spectroscopic
data to identify and eliminate dwarf star contaminants. From these analyses, we
identify three, bright ( ABmag) dropout point sources at
. Spectral energy distribution analyses suggest that these sources
are either quasars or compact star-forming galaxies. The flux captured by the
IRAC 4.5 m channel suggests that they have moderate +
equivalent widths. We calculate the number density of point sources at
-8, and find that a double powerlaw model well describes the point
source distribution. We then extend our analysis to estimate the combined point
source + galaxy luminosity function and find that the point sources have a
non-negligible contribution to the bright-end excess. The fact that the point
sources dominate only at suggests that their contribution
to cosmic reionization is likely limited. While spectroscopic follow-up is
needed to confirm the nature of these point sources, this work demonstrates
that the inclusion of Lyman dropout point sources is necessary for a complete
census of the early galaxies at the epoch of cosmic reionization.Comment: 21 pages. 10 figure
Efficient focusing of hard x rays to 25 nm by a total reflection mirror
Nanofocused x rays are indispensable because they can provide high spatial resolution and high sensitivity for x-ray nanoscopy/spectroscopy. A focusing system using total reflection mirrors is one of the most promising methods for producing nanofocused x rays due to its high efficiency and energy-tunable focusing. The authors have developed a fabrication system for hard x-ray mirrors by developing elastic emission machining, microstitching interferometry, and relative angle determinable stitching interferometry. By using an ultraprecisely figured mirror, they realized hard x-ray line focusing with a beam width of 25 nm at 15 keV. The focusing test was performed at the 1-km -long beamline of SPring-8. © 2007 American Institute of Physics.Hidekazu Mimura, Hirokatsu Yumoto, et al. "Efficient focusing of hard x rays to 25nm by a total reflection mirror", Appl. Phys. Lett. 90(5), 051903 (2007) https://doi.org/10.1063/1.2436469
An optical fiber double scrambler and mechanical agitator system for the Keck planet finder spectrograph
We present the design and test results of a double-scrambler and fiber agitator system for the Keck Planet Finder (KPF) spectrograph. The mechanical agitator for modal noise suppression is constructed from two linear stages with the fibers mounted in a “W” curve. When driven back-and-forth at different rates, the stages change the position of the fiber curves, and hence vary the modes propagating through the fiber. Near-field temporal centroid shifts caused by modal-noise are reduced by a factor of 100 by the agitator, while mid-range spatial frequencies have reduced power by a factor of ∼300 in the near-field, and ∼1000 in the far-field. The scrambling system incorporates two octagonal fibers, and a scrambler consisting of two identical cemented lenses ∼20 cm apart, which exchanges the optical near- and far-fields of the fibers. The scrambler shows scrambling gains >16,000 in the near-field, and >40,000 in the far-field. The measured throughput efficiency of 99.3% of the expected maximum demonstrates that scrambler-induced focal ratio degradation (FRD) is minimal. The scrambler also serves as the feed-through into the vacuum chamber where the spectrograph is housed, thereby removing concerns about stressing the fibers, and introducing FRD, at this interface. Our illumination stabilization system, consisting of two octagonal fibers, a two lens scrambler, and a mechanical agitator, produces very homogeneous fiber output in both the near and far-fields. When coupled to the Keck Planet Finder spectrograph, this system provides illumination stability corresponding to a velocity of 0.30 m s^(−1)
Relative angle determinable stitching interferometry for hard x-ray reflective optics
Metrology plays an important role in surface figuring with subnanometer accuracy. We have developed relative angle determinable stitching interferometry for the surface figuring of elliptical mirrors, in order to realize hard x-ray nanofocusing. In a stitching system, stitching angles are determined not by the general method using a common area between neighboring shots, but by the new method using the mirror's tilt angles measured at times when profile data are acquired. The high measurement accuracy of approximately 4 nm (peak-to-valley) was achieved in the measurement of a cylindrical surface having the same curvature as the elliptically designed shape to enable hard x-ray nanofocusing. © 2005 American Institute of Physics.Hidekazu Mimura, Hirokatsu Yumoto, Satoshi Matsuyama, Kazuya Yamamura, Yasuhisa Sano, Kazumasa Ueno, Katsuyoshi Endo, Yuzo Mori, Makina Yabashi, Kenji Tamasaku, Yoshinori Nishino, Tetsuya Ishikawa and Kazuto Yamauchi, "Relative angle determinable stitching interferometry for hard x-ray reflective optics", Review of Scientific Instruments 76(4), 045102 (2005) https://doi.org/10.1063/1.186847
Fabrication of elliptically figured mirror for focusing hard x rays to size less than 50 nm
In this study, we designed, fabricated, and evaluated a hard x-ray focusing mirror having an ideally focused beam with a full width at half maximum in the intensity profile of 36 nm at an x-ray energy of 15 keV. The designed elliptically curved shape was fabricated by a computer-controlled fabrication system using plasma chemical vaporization machining and elastic emission machining, on the basis of surface profiles accurately measured by combining microstitching interferometry with relative angle determinable stitching interferometry. A platinum-coated surface was employed for hard x-ray focusing with a large numerical aperture. Line-focusing tests on the fabricated elliptical mirror are carried out at the 1-km -long beamline of SPring-8. A full width at half maximum of 40 nm was achieved in the focused beam intensity profile under the best focus conditions. © 2005 American Institute of Physics.Hirokatsu Yumoto, Hidekazu Mimura, Satoshi Matsuyama, Hideyuki Hara, Kazuya Yamamura, Yasuhisa Sano Kazumasa Ueno, Katsuyoshi Endo Yuzo Mori, Makina Yabashi, Yoshinori Nishino, Kenji Tamasaku, Tetsuya Ishikawa and Kazuto Yamauchi, "Fabrication of elliptically figured mirror for focusing hard x rays to size less than 50nm", Review of Scientific Instruments 76(6), 063708 (2005) https://doi.org/10.1063/1.1922827
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