2,640 research outputs found
Is the Cepheus E Outflow driven by a Class 0 Protostar?
New early release observations of the Cepheus E outflow and its embedded
source, obtained with the Spitzer Space Telescope, are presented. We show the
driving source is detected in all 4 IRAC bands, which suggests that traditional
Class 0 classification, although essentially correct, needs to accommodate the
new high sensitivity infrared arrays and their ability to detected deeply
embedded sources. The IRAC, MIPS 24 and 70 microns new photometric points are
consistent with a spectral energy distribution dominated by a cold, dense
envelope surrounding the protostar. The Cep E outflow, unlike its more famous
cousin the HH 46/47 outflow, displays a very similar morphology in the near and
mid-infrared wavelengths, and is detected at 24 microns. The interface between
the dense molecular gas (where Cep E lies) and less dense interstellar medium,
is well traced by the emission at 8 and 24 microns, and is one of the most
exotic features of the new IRAC and MIPS images. IRS observations of the North
lobe of the flow confirm that most of the emission is due to the excitation of
pure H2 rotational transitions arising from a relatively cold (Tex~700 K) and
dense (N{H}~9.6E20 cm-2 molecular gas.Comment: 14 pages (pre-print format), including 6 figures. Published in ApJ
Special Spitzer Issue (2004
Molecular orbital calculations of two-electron states for P donor solid-state spin qubits
We theoretically study the Hilbert space structure of two neighbouring P
donor electrons in silicon-based quantum computer architectures. To use
electron spins as qubits, a crucial condition is the isolation of the electron
spins from their environment, including the electronic orbital degrees of
freedom. We provide detailed electronic structure calculations of both the
single donor electron wave function and the two-electron pair wave function. We
adopted a molecular orbital method for the two-electron problem, forming a
basis with the calculated single donor electron orbitals. Our two-electron
basis contains many singlet and triplet orbital excited states, in addition to
the two simple ground state singlet and triplet orbitals usually used in the
Heitler-London approximation to describe the two-electron donor pair wave
function. We determined the excitation spectrum of the two-donor system, and
study its dependence on strain, lattice position and inter donor separation.
This allows us to determine how isolated the ground state singlet and triplet
orbitals are from the rest of the excited state Hilbert space. In addition to
calculating the energy spectrum, we are also able to evaluate the exchange
coupling between the two donor electrons, and the double occupancy probability
that both electrons will reside on the same P donor. These two quantities are
very important for logical operations in solid-state quantum computing devices,
as a large exchange coupling achieves faster gating times, whilst the magnitude
of the double occupancy probability can affect the error rate.Comment: 15 pages (2-column
Recommended from our members
Tungsten Cathode Catalyst for PEMFC
Final report for project to evaluate tungsten-based catalyst as a cathode catalyst for PEM cell applications
Assessing the Sheltering Response in the Middle East: Studying Syrian Camps in Jordan
This study focuses on the sheltering response in the Middle East, specifically through reviewing two Syrian refugee camps in Jordan, involving Zaatari and Azraq. Zaatari camp involved the rapid deployment of tents and shelters over a very short period of time and Azraq was purpose built and pre-planned over a longer period. At present, both camps collectively host more than 133,000 occupants. Field visits were taken to both camps and the main issues and problems in the sheltering response were highlighted through focus group discussions with camp occupants and inspection of shelter habitats. This provided both subjective and objective research data sources. While every case has its own significance and deployment to meet humanitarian needs, there are some common requirements irrespective of geographical region. The results suggest that there is a gap in the suitability of the required habitat needs and what has been provided. It is recommended that the global international response and support could be improved in relation to the habitat form, construction type, layout, function and critically the cultural aspects. Services, health and hygiene are key elements to the shelter habitat provision. The study also identified the amendments to shelters undertaken by the beneficiaries providing insight into their key main requirements. The outcomes from this study could provide an important learning opportunity to develop improved habitat response for future shelters
Technology use by people with intellectual and developmental disabilities to support employment activities: A single-subject design meta analysis
This is the published version. Copyright 2006 IOS PressObjectives: Technology has the potential to improve employment and rehabilitation related outcomes for persons with disabilities. The purpose of this study was to examine the impact of technology use on employment-related outcomes for people with intellectual and developmental disabilities. Study design: A comprehensive search of the literature pertaining to technology use by people with intellectual disabilities was conducted, and a single-subject design meta analysis was conducted for a subset of those studies, which focused on employment and rehabilitation related outcomes. Results: The use of technology to promote outcomes in this area was shown to be generally effective, in particular when universal design features were addressed. Conclusions: Technology has the potential to enable people with intellectual and developmental disabilities to achieve more positive employment and rehabilitation outcomes. It is important to focus on universal design features important to persons with cognitive disabilities, and there is a need for more research in this area
University of Kentucky Measurements of Wind, Temperature, Pressure and Humidity in Support of LAPSE-RATE Using Multisite Fixed-Wing and Rotorcraft Unmanned Aerial Systems
In July 2018, unmanned aerial systems (UASs) were deployed to measure the properties of the lower atmosphere within the San Luis Valley, an elevated valley in Colorado, USA, as part of the Lower Atmospheric Profiling Studies at Elevation â a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). Measurement objectives included detailing boundary layer transition, canyon cold-air drainage and convection initiation within the valley. Details of the contribution to LAPSE-RATE made by the University of Kentucky are provided here, which include measurements by seven different fixed-wing and rotorcraft UASs totaling over 178 flights with validated data. The data from these coordinated UAS flights consist of thermodynamic and kinematic variables (air temperature, humidity, pressure, wind speed and direction) and include vertical profiles up to 900âm above the ground level and horizontal transects up to 1500âm in length. These measurements have been quality controlled and are openly available in the Zenodo LAPSE-RATE community data repository (https://zenodo.org/communities/lapse-rate/, last access: 23 July 2020), with the University of Kentucky data available at https://doi.org/10.5281/zenodo.3701845 (Bailey et al., 2020)
WHOI Hawaii Ocean Timeseries Station (WHOTS) : WHOTS-3 mooring turnaround cruise report
The Woods Hole Oceanographic Institution (WHOI) Hawaii Ocean Timeseries (HOT) Site (WHOTS), 100 km north of Oahu, Hawaii,
is intended to provide long-term, high-quality air-sea fluxes as a coordinated part of the HOT program and contribute to the goals of
observing heat, fresh water, and chemical fluxes at a site representative of the oligotrophic North Pacific Ocean. The approach is to
maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 22.75N 158W by successive
mooring turnarounds. These observations will be used to investigate air-sea interaction processes related to climate variability.
The first WHOTS mooring (WHOTS-1) was deployed in August 2004. WHOTS-1 was recovered and WHOTS-2 deployed in July 2005.
This report documents recovery of the WHOTS-2 mooring and deployment of the third mooring (WHOTS-3) at the same site. Both
moorings used Surlyn foam buoys as the surface element and were outfitted with two Air-Sea Interaction Meteorology (ASIMET)
systems. Each system measures, records, and transmits via Argos satellite, the surface meteorological variables necessary to compute
air-sea fluxes of heat, moisture, and momentum. WHOTS-2 was equipped with one Iridium data transmitter, and WHOTS-3 had two
Iridium data transmitters. In cooperation with R. Lukas of the University of Hawaii, the upper 155 m of the morrings were outfitted with
oceanographic sensors for the measurement of temperature, conductivity, and velocity.
The WHOTS mooring turnaround was done on the Scripps Institution of Oceanography ship Revelle, Cruise AMAT-07, by the Upper
Ocean Processes Group of the Woods Hole Oceanographic Institution and Roger Lukasâgroup at the University of Hawaii. The cruise took
place between 22 and 29 June 2006. Operations on site were initiated with an intercomparison of shipboard meteorological observations
with the WHOTS-2 buoy. Dr. Frank Bradley, CSIRO, Australia, assisted with these comparisons. This was followed by recovery of the
WHOTS-2 mooring on 24 June. A number of recovered instruments were calibrated by attaching them to the rosette frame of the CTD.
Shallow CTD profiles were taken every two hours for 12 hours on the 25th of June. A fish trap was deployed on June 25th by John Yeh, a
University of Hawaii graduate student. The WHOTS-3 mooring was deployed on 26 June at approximately 22°46'N, 157°54'W in 4703 m
of water. A ship-buoy intercomparison period and series of shallow CTDs followed along with a second deployment of the fishtrap.
A NOAA Teacher-At-Sea, Diana Griffiths, and a NOAA Hollings Scholar, Terry Smith, participated in the cruise. This report describes
the mooring operations, some of the pre-cruise buoy preparations and CTD casts taken during the cruise, the fish trap deployments, and
the experiences of the Teacher-at-Sea and Hollings Scholar.Funding was provided by the National Oceanic and Atmospheric Administration under grant No. NA17RJ1223
for the Cooperative Institute for Climate and Ocean Research (CICOR)
A biâorganellar phylogenomic study of Pandanales: inference of higherâorder relationships and unusual rateâvariation patterns
We used a biâorganellar phylogenomic approach to address higherâorder relationships in Pandanales, including the first molecular phylogenetic study of the panamaâhat family, Cyclanthaceae. Our genusâlevel study of plastid and mitochondrial gene sets includes a comprehensive sampling of photosynthetic lineages across the order, and provides a framework for investigating clade ages, biogeographic hypotheses and organellar molecular evolution. Using multiple inference methods and both organellar genomes, we recovered mostly congruent and strongly supported relationships within and between families, including the placement of fully mycoheterotrophic Triuridaceae. Cyclanthaceae and Pandanaceae plastomes have slow substitution rates, contributing to weakly supported plastidâbased relationships in Cyclanthaceae. While generally slowly evolving, mitochondrial genomes exhibit sporadic rate elevation across the order. However, we infer wellâsupported relationships even for slower evolving mitochondrial lineages in Cyclanthaceae. Clade age estimates across photosynthetic lineages are largely consistent with previous studies, are well correlated between the two organellar genomes (with slightly younger inferences from mitochondrial data), and support several biogeographic hypotheses. We show that rapidly evolving nonâphotosynthetic lineages may bias age estimates upwards at neighbouring photosynthetic nodes, even using a relaxed clock model. Finally, we uncovered new genome structural variants in photosynthetic taxa at plastid inverted repeat boundaries that show promise as interfamilial phylogenetic markers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/33/cla12417-sup-0025-TableS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/32/cla12417-sup-0017-FigS17.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/31/cla12417-sup-0004-FigS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/30/cla12417-sup-0019-FigS19.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/29/cla12417-sup-0020-FigS20.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/28/cla12417_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/27/cla12417-sup-0005-FigS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/26/cla12417-sup-0012-FigS12.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/25/cla12417-sup-0007-FigS7.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/24/cla12417-sup-0022-FigS22.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/23/cla12417-sup-0029-TableS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/22/cla12417-sup-0010-FigS10.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/21/cla12417-sup-0011-FigS11.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/20/cla12417-sup-0014-FigS14.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/19/cla12417-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/18/cla12417-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/17/cla12417.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/16/cla12417-sup-0030-TableS6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/15/cla12417-sup-0021-FigS21.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/14/cla12417-sup-0023-FigS23.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/13/cla12417-sup-0009-FigS9.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/12/cla12417-sup-0031-TableS7.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/11/cla12417-sup-0006-FigS6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/10/cla12417-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/9/cla12417-sup-0024-FigS24.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/8/cla12417-sup-0008-FigS8.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/7/cla12417-sup-0028-TableS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/6/cla12417-sup-0016-FigS16.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/5/cla12417-sup-0013-FigS13.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/4/cla12417-sup-0018-FigS18.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/3/cla12417-sup-0026-TableS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/2/cla12417-sup-0015-FigS15.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162810/1/cla12417-sup-0027-TableS3.pd
Maximal Success Probabilities of Linear-Optical Quantum Gates
Numerical optimization is used to design linear-optical devices that
implement a desired quantum gate with perfect fidelity, while maximizing the
success rate. For the 2-qubit CS (or CNOT) gate, we provide numerical evidence
that the maximum success rate is using two unentangled ancilla
resources; interestingly, additional ancilla resources do not increase the
success rate. For the 3-qubit Toffoli gate, we show that perfect fidelity is
obtained with only three unentangled ancilla photons -- less than in any
existing scheme -- with a maximum . This compares well with
, obtainable by combining two CNOT gates and a
passive quantum filter [PRA 68, 064303 (2003)]. The general optimization
approach can easily be applied to other areas of interest, such as quantum
error correction, cryptography, and metrology [arXiv:0807.4906, PRL 99 070801
(2007)].Comment: 4 pages, 3 figures, presented at Quantum Computing and Algorithms
Program Review in Atlanta, GA (August 11-15, 2008
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