1,129 research outputs found
LIMS Instrument Package (LIP) balloon experiment: Nimbus 7 satellite correlative temperature, ozone, water vapor, and nitric acid measurements
The Limb Infrared Monitor of the Stratosphere (LIMS) LIP balloon experiment was used to obtain correlative temperature, ozone, water vapor, and nitric acid data at altitudes between 10 and 36 kilometers. The performance of the LIMS sensor flown on the Nimbus 7 Satellite was assessed. The LIP consists of the modified electrochemical concentration cell ozonesonde, the ultraviolet absorption photometric of ozone, the water vapor infrared radiometer sonde, the chemical absorption filter instrument for nitric acid vapor, and the infrared radiometer for nitric acid vapor. The limb instrument package (LIP), its correlative sensors, and the resulting data obtained from an engineering and four correlative flights are described
Spectroscopy of the Methane {\nu}3 Band with an Accurate Mid-Infrared Coherent Dual- Comb Spectrometer
We demonstrate a high-accuracy dual-comb spectrometer centered at 3.4 \mu m.
The amplitude and phase spectra of the P, Q, and partial R-branch of the
methane {\nu}3 band are measured at 25 MHz to 100 MHz point spacing with ~kHz
resolution and a signal-to-noise ratio of up to 3500. A fit of the absorbance
and phase spectra yield the center frequency of 132 rovibrational lines. The
systematic uncertainty is estimated to be 300 kHz, which is 10-3 of the Doppler
width and a tenfold improvement over Fourier transform spectroscopy. These data
are the first high- accuracy molecular spectra obtained with a direct comb
spectrometer.Comment: journal articl
ACVIM consensus statement on the treatment of immune-mediated hemolytic anemia in dogs
Immune‐mediated hemolytic anemia (IMHA) causes severe anemia in dogs and is associated with considerable morbidity and mortality. Treatment with various immunosuppressive and antithrombotic drugs has been described anecdotally and in previous studies, but little consensus exists among veterinarians as to the optimal regimen to employ and maintain after diagnosis of the disease. To address this inconsistency and provide evidence‐based guidelines for treatment of IMHA in dogs, we identified and extracted data from studies published in the veterinary literature. We developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria, explanation of treatment regimens, and validity of statistical methods. In combination with our clinical experience and comparable guidelines for humans afflicted with autoimmune hemolytic anemia, we used the conclusions of this process to make a set of clinical recommendations regarding treatment of IMHA in dogs, which we refined subsequently by conducting several iterations of Delphi review. Additionally, we considered emerging treatments for IMHA in dogs and highlighted areas deserving of future research. Comments were solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted for publication. The resulting document is intended to provide clinical guidelines for management of IMHA in dogs. These guidelines should be implemented pragmatically, with consideration of animal, owner, and veterinary factors that may vary among cases
Coherent Dual Comb Spectroscopy at High Signal to Noise
Two frequency combs can be used to measure the full complex response of a
sample in a configuration which can be alternatively viewed as the equivalent
of a dispersive Fourier transform spectrometer, infrared time domain
spectrometer, or a multiheterodyne laser spectrometer. This dual comb
spectrometer retains the frequency accuracy and resolution inherent to the comb
sources. We discuss, in detail, the specific design of our coherent dual-comb
spectrometer and demonstrate the potential of this technique by measuring the
first overtone vibration of hydrogen cyanide, centered at 194 THz (1545 nm). We
measure the fully normalized, complex response of the gas over a 9 THz
bandwidth at 220 MHz frequency resolution yielding 41,000 resolution elements.
The average spectral signal-to-noise ratio (SNR) is 2,500 for both the
fractional absorption and the phase, with a peak SNR of 4,000 corresponding to
a fractional absorption sensitivity of 0.025% and phase sensitivity of 250
microradians. As the spectral coverage of combs expands, this dual-comb
spectroscopy could provide high frequency accuracy and resolution measurements
of a complex sample response across a range of spectral regions.Comment: 18 pages, 8 figures updated references, updated to match publication
versio
Estimating vehicle carbon dioxide emissions from Boulder, Colorado, using horizontal path-integrated column measurements
We performed 7.5 weeks of path-integrated concentration
measurements of CO2, CH4, H2O, and HDO over the city of Boulder, Colorado. An open-path dual-comb spectrometer simultaneously
measured time-resolved data across a reference path, located near the
mountains to the west of the city, and across an over-city path that
intersected two-thirds of the city, including two major commuter arteries. By
comparing the measured concentrations over the two paths when the wind is
primarily out of the west, we observe daytime CO2 enhancements over
the city. Given the warm weather and the measurement footprint, the dominant
contribution to the CO2 enhancement is from city vehicle traffic. We
use a Gaussian plume model combined with reported city traffic patterns to
estimate city emissions of on-road CO2 as (6.2±2.2) × 105 metric tons (t) CO2 yr−1
after correcting for non-traffic sources. Within the uncertainty, this value
agrees with the city's bottom-up greenhouse gas inventory for the on-road
vehicle sector of 4.5×105 t CO2 yr−1. Finally, we
discuss experimental modifications that could lead to improved estimates from
our path-integrated measurements.</p
Walking the walk: a phenomenological study of long distance walking
Evidence suggests that regular walking can elicit significant psychological benefits although little evidence exists concerning long distance walking. The purpose of this study was to provide detailed accounts of the experiences of long distance walkers. Phenomenological interviews were conducted with six long distance walkers. Data were transcribed verbatim before researchers independently analyzed the transcripts. Participants reported a cumulative effect with positive feelings increasing throughout the duration of the walk. Long distance walking elicited positive emotions, reduced the effects of life-stress, and promoted an increased sense of well-being and personal growth. Results are aligned to theories and concepts from positive psychology
On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principle (Part One)
In October 1924, the Physical Review, a relatively minor journal at the time,
published a remarkable two-part paper by John H. Van Vleck, working in virtual
isolation at the University of Minnesota. Van Vleck combined advanced
techniques of classical mechanics with Bohr's correspondence principle and
Einstein's quantum theory of radiation to find quantum analogues of classical
expressions for the emission, absorption, and dispersion of radiation. For
modern readers Van Vleck's paper is much easier to follow than the famous paper
by Kramers and Heisenberg on dispersion theory, which covers similar terrain
and is widely credited to have led directly to Heisenberg's "Umdeutung" paper.
This makes Van Vleck's paper extremely valuable for the reconstruction of the
genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did
not take the next step and develop matrix mechanics himself.Comment: 82 page
J D Bernal: philosophy, politics and the science of science
This paper is an examination of the philosophical and political legacy of John Desmond Bernal. It addresses the evidence of an emerging consensus on Bernal based on the recent biography of Bernal by Andrew Brown and the reviews it has received. It takes issue with this view of Bernal, which tends to be admiring of his scientific contribution, bemused by his sexuality, condescending to his philosophy and hostile to his politics. This article is a critical defence of his philosophical and political position
J D Bernal: philosophy, politics and the science of science
This paper is an examination of the philosophical and political legacy of John Desmond Bernal. It addresses the evidence of an emerging consensus on Bernal based on the recent biography of Bernal by Andrew Brown and the reviews it has received. It takes issue with this view of Bernal, which tends to be admiring of his scientific contribution, bemused by his sexuality, condescending to his philosophy and hostile to his politics. This article is a critical defence of his philosophical and political position
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