219 research outputs found
What is Wrong with Water Barometers?
Every student who studies atmospheric pressure in physics or chemistry learns the principles behind the construction of barometers. Cistern barometers, such as those found in most laboratories, consist of a long glass tube containing an inverted column of liquid having an open end in a cistern of the liquid. Students learn that the column of liquid is supported by air pressure and is equal in weight to a column of air of the same diameter
Characterization of traverse slippage experienced by Spirit rover on Husband Hill at Gusev crater
Spirit rover experienced significant slips traversing Husband Hill. This paper analyzes the slippage Spirit experienced from Sol 154 to Sol 737. Slippage with respect to terrain type and slope is computed using data downlinked from the rover, rover position, and orientation estimations from visual odometry (VO) and photogrammetry based bundle adjustment (BA) method. Accumulated slippage reached a maximum of 83.86 m on Sol 648. However, as Spirit descended into the Inner Basin, the direction of slippage reversed, and accumulated slippage approached zero by the end of the entire traverse. Eight local regions with significant slips and nineteen traverse segments have been analyzed. Slippage was found to be highly correlated to slope direction and magnitude; the reverse of slope directions in the ascending and descending portions of the traverse proves to be the main contributor to the observed cancellation of slippage. While the horizontal component of the slippage almost canceled out, the difference in elevation continually accumulated, mainly during the ascent. In general, long traverse segments created more slips than short ones. This is reflected in both the accumulated and individual slippages. In considering the four major Mars terrain types, Spirit performed best on bedrock, managing to drive on slopes close to 30°. Fine-grain surfaces were the most challenging; though progress was made on slopes up to 15°, slippages of over 100% (more slippage than distance traveled) occurred for short segments. The results of this work can be incorporate into a traverse planning framework in which rover slippage is minimized. Results can be employed in landed planetary missions for precision navigation to avoid potentially dangerous regions by considering expected slippage
Palliative care early in the care continuum among patients with serious respiratory illness an official ATS/AAHPM/HPNA/SWHPN policy statement
Background:
Patients with serious respiratory illness and their caregivers suffer considerable burdens, and palliative care is a fundamental right for anyone who needs it. However, the overwhelming majority of patients do not receive timely palliative care before the end of life, despite robust evidence for improved outcomes.
Goals:
This policy statement by the American Thoracic Society (ATS) and partnering societies advocates for improved integration of high-quality palliative care early in the care continuum for patients with serious respiratory illness and their caregivers and provides clinicians and policymakers with a framework to accomplish this.
Methods:
An international and interprofessional expert committee, including patients and caregivers, achieved consensus across a diverse working group representing pulmonary–critical care, palliative care, bioethics, health law and policy, geriatrics, nursing, physiotherapy, social work, pharmacy, patient advocacy, psychology, and sociology.
Results:
The committee developed fundamental values, principles, and policy recommendations for integrating palliative care in serious respiratory illness care across seven domains: 1) delivery models, 2) comprehensive symptom assessment and management, 3) advance care planning and goals of care discussions, 4) caregiver support, 5) health disparities, 6) mass casualty events and emergency preparedness, and 7) research priorities. The recommendations encourage timely integration of palliative care, promote innovative primary and secondary or specialist palliative care delivery models, and advocate for research and policy initiatives to improve the availability and quality of palliative care for patients and their caregivers.
Conclusions:
This multisociety policy statement establishes a framework for early palliative care in serious respiratory illness and provides guidance for pulmonary–critical care clinicians and policymakers for its proactive integration
Overview of Spirit Microscopic Imager Results
This paper provides an overview of Mars Exploration Rover Spirit Microscopic Imager (MI) operations and the calibration, processing, and analysis of MI data. The focus of this overview is on the last five Earth years (2005-2010) of Spirit's mission in Gusev crater, supplementing the previous overview of the first 450 sols of the Spirit MI investigation. Updates to radiometric calibration using in-flight data and improvements in high-level processing are summarized. Released data products are described, and a table of MI observations, including target/feature names and associated data sets, is appended. The MI observed natural and disturbed exposures of rocks and soils as well as magnets and other rover hardware. These hand-lens-scale observations have provided key constraints on interpretations of the formation and geologic history of features, rocks, and soils examined by Spirit. MI images complement observations by other Spirit instruments, and together show that impact and volcanic processes have dominated the origin and evolution of the rocks in Gusev crater, with aqueous activity indicated by the presence of silica-rich rocks and sulfate-rich soils. The textures of some of the silica-rich rocks are similar to terrestrial hot spring deposits, and observations of subsurface cemented layers indicate recent aqueous mobilization of sulfates in places. Wind action has recently modified soils and abraded many of the rocks imaged by the MI, as observed at other Mars landing sites. Plain Language Summary The Microscopic Imager (MI) on NASA's Spirit rover returned the highest-resolution images of the Martian surface available at the time of the 2004-2010 mission. Designed to survive 90 Mars days (sols) and search for evidence of water in the past, Spirit returned data for 2210 sols, far exceeding all expectations. This paper summarizes the scientific insights gleaned from the thousands of MI images acquired during the last 5years of the mission, supplementing the summary of the first 450 sols of the Spirit MI investigation published previously (Herkenhoff et al., ). Along with data from the other instruments on Spirit, MI images guided the scientific interpretation of the geologic history of the rocks and soils observed in Gusev crater on Mars. We conclude that the geologic history of the area explored by Spirit has been dominated by impacts and volcanism, and that water, perhaps very hot water, was involved in the evolution of some of the rocks and soils. More recently, winds have moved soil particles and abraded rocks, as observed elsewhere on Mars. These results have improved our understanding of Mars' history and informed planning of future missions to Mars.National Aeronautics and Space AdministrationPublic domain articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Terahertz All-Optical Modulation in a Silicon-Polymer Hybrid System
Although Gigahertz-scale free-carrier modulators have been previously
demonstrated in silicon, intensity modulators operating at Terahertz speeds
have not been reported because of silicon's weak ultrafast optical
nonlinearity. We have demonstrated intensity modulation of light with light in
a silicon-polymer integrated waveguide device, based on the all-optical Kerr
effect - the same ultrafast effect used in four-wave mixing. Direct
measurements of time-domain intensity modulation are made at speeds of 10 GHz.
We showed experimentally that the ultrafast mechanism of this modulation
functions at the optical frequency through spectral measurements, and that
intensity modulation at frequencies in excess of 1 THz can be obtained in this
device. By integrating optical polymers through evanescent coupling to
high-mode-confinement silicon waveguides, we greatly increase the effective
nonlinearity of the waveguide for cross-phase modulation. The combination of
high mode confinement, multiple integrated optical components, and high
nonlinearities produces all-optical ultrafast devices operating at
continuous-wave power levels compatible with telecommunication systems.
Although far from commercial radio frequency optical modulator standards in
terms of extinction, these devices are a first step in development of
large-scale integrated ultrafast optical logic in silicon, and are two orders
of magnitude faster than previously reported silicon devices.Comment: Under consideration at Nature Material
Bostonia: The Boston University Alumni Magazine. Volume 31
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Recommended from our members
1960
Recent Developments Affecting Golf Course Design (page 1) From the Editor (3) Five Year Results (3) Turf Management Club News (4) Quotes from 1960 Seniors (5) Poa annua - - Friend or Foe (6) The Horticulture Show (7) Cartoons (8) Message from the Winter School President of 1960 (10) The Most Outstanding Turf Senior for 1959 (10) The Value of the Proper Use of Lime (11) Summer Placement (12) A Greenhouse on the Golf Course (13) More Opportunities in the Future for the Aggressive Superintendent at Country Clubs (14) Soil, Sawdust and Turfgrass (15) Picture - Senior Stockbridge Turf majors (16) Picture - Freshman Stockbridge Turf majors (17) Susceptibility of Merion Bluegrass to Stripe Smut (18) Bents in the South (19) Picture - Honorary Members of Turf Management Club (20) Picture - Graduates of Winter School for Turf mangers- 1960 (21) Weather - We are Going to Have Weather, Whether or Not - What Should we Expect by O. Tennebaum & R. E. Lautzenheiser (A-1) The Nature of Winter Injury to Plants by Dr. Johnson Parker (A-1) Turf Problems: You Name it and We\u27ve Had It in \u2759 by Alexander Radko ad T.T. Taylor (A-3) Topdressing Experiences with Greens at Century by James Fulwider (A-5) Poa annua - Fairway Rennovation at winged Foot by Sherwood A. Moore (A-6) Winter Problems at Ekwanaok by Paul O\u27Leary (A-8) Progress Through Drainage by Kayem Ovian (A-10) Winter Injury on Home Lawns by Orlando Capizzi (A-12) The Status of Pre-emergence Chemicals for the Control of Crabgrass by Dr. E. Engel (A-12) Turf Nurseries - Establishment, Maintenance & Utilization by Robert Grant (A-14) Soil Compaction by Dr. R. B. Alderfer (A-16) Water Management Practices on Turf Areas by Dr. J.R. Watson (A-18) Getting to Know Your Members by Owen Griffith (A-23) New Trends in Clubhouse Landscaping by Alfred Boicourt (A-26) General Lawn Management (Alternate Session) Conserving Soil for a good Lawn by Dr. William G. Colby (A-27) Fertilizting and Liming by Dr. Joseph Steckel (A-28) Grasses and Grass Mixtures for New England Lawns by Dr. Robert Schery (A-29) The Care and Maintenance of Establishment Lawns by Dr. John R. Davi
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
GENE-Counter: A Computational Pipeline for the Analysis of RNA-Seq Data for Gene Expression Differences
GENE-counter is a complete Perl-based computational pipeline for analyzing RNA-Sequencing (RNA-Seq) data for differential gene expression. In addition to its use in studying transcriptomes of eukaryotic model organisms, GENE-counter is applicable for prokaryotes and non-model organisms without an available genome reference sequence. For alignments, GENE-counter is configured for CASHX, Bowtie, and BWA, but an end user can use any Sequence Alignment/Map (SAM)-compliant program of preference. To analyze data for differential gene expression, GENE-counter can be run with any one of three statistics packages that are based on variations of the negative binomial distribution. The default method is a new and simple statistical test we developed based on an over-parameterized version of the negative binomial distribution. GENE-counter also includes three different methods for assessing differentially expressed features for enriched gene ontology (GO) terms. Results are transparent and data are systematically stored in a MySQL relational database to facilitate additional analyses as well as quality assessment. We used next generation sequencing to generate a small-scale RNA-Seq dataset derived from the heavily studied defense response of Arabidopsis thaliana and used GENE-counter to process the data. Collectively, the support from analysis of microarrays as well as the observed and substantial overlap in results from each of the three statistics packages demonstrates that GENE-counter is well suited for handling the unique characteristics of small sample sizes and high variability in gene counts
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