130 research outputs found
Johnson(-like)-Noise-Kirchhoff-Loop Based Secure Classical Communicator Characteristics, for Ranges of Two to Two Thousand Kilometers, via Model-Line
A pair of Kirchhoff-Loop-Johnson(-like)-Noise communicators, which is able to
work over variable ranges, was designed and built. Tests have been carried out
on a model-line performance characteristics were obtained for ranges beyond the
ranges of any known direct quantum communication channel and they indicate
unrivalled signal fidelity and security performance of the exchanged raw key
bits. This simple device has single-wire secure key generation and sharing
rates of 0.1, 1, 10, and 100 bit/second for corresponding copper wire
diameters/ranges of 21 mm / 2000 km, 7 mm / 200 km, 2.3 mm / 20 km, and 0.7 mm
/ 2 km, respectively and it performs with 0.02% raw-bit error rate (99.98 %
fidelity). The raw-bit security of this practical system significantly
outperforms raw-bit quantum security. Current injection breaking tests show
zero bit eavesdropping ability without triggering the alarm signal, therefore
no multiple measurements are needed to build an error statistics to detect the
eavesdropping as in quantum communication. Wire resistance based breaking tests
of Bergou-Scheuer-Yariv type give an upper limit of eavesdropped raw bit ratio
of 0.19 % and this limit is inversely proportional to the sixth power of cable
diameter. Hao's breaking method yields zero (below measurement resolution)
eavesdropping information.Comment: Featured in New Scientist, Jason Palmer, May 23, 2007.
http://www.ece.tamu.edu/%7Enoise/news_files/KLJN_New_Scientist.pdf
Corresponding Plenary Talk at the 4th International Symposium on Fluctuation
and Noise, Florence, Italy (May 23, 2007
Discovery of a Classic FR-II Broad Absorption Line Quasar from the FIRST Survey
We have discovered a remarkable quasar, FIRST J101614.3+520916, whose optical
spectrum shows unambiguous broad absorption features while its double-lobed
radio morphology and luminosity clearly indicate a classic Fanaroff-Riley Type
II radio source. Its radio luminosity places it at the extreme of the recently
established class of radio-loud broad absorption line quasars (Becker et al.
1997, 2000; Brotherton et al. 1998). Because of its hybrid nature, we speculate
that FIRST J101614.3+520916 is a typical FR-II quasar which has been
rejuvenated as a broad absorption line (BAL) quasar with a Compact Steep
Spectrum core. The direction of the jet axis of FIRST J101614.3+520916 can be
estimated from its radio structure and optical brightness, indicating that we
are viewing the system at a viewing angle of > 40 degrees. The position angles
of the radio jet and optical polarization are not well-aligned, differing by 20
to 30 degrees. When combined with the evidence presented by Becker et al.
(2000) for a sample of 29 BAL quasars showing that at least some BAL quasars
are viewed along the jet axis, the implication is that no preferred viewing
orientation is necessary to observe BAL systems in a quasar's spectrum. This,
and the probable young nature of compact steep spectrum sources, leads
naturally to the alternate hypothesis that BALs are an early stage in the lives
of quasars.Comment: 14 pages, 6 postscript figures; accepted for publication in the
Astrophysical Journa
An automated pattern recognition system for the quantification of inflammatory cells in hepatitis-C-infected liver biopsies
This paper presents an automated system for the quantification of inflammatory cells in hepatitis-C-infected liver biopsies. Initially, features are extracted from colour-corrected biopsy images at positions of interest identified by adaptive thresholding and clump decomposition. A sequential floating search method and principal component analysis are used to reduce dimensionality. Manually annotated training images allow supervised training. The performance of Gaussian parametric and mixture models is compared when used to classify regions as either inflammatory or healthy. The system is optimized using a response surface method that maximises the area under the receiver operating characteristic curve. This system is then tested on images previously ranked by a number of observers with varying levels of expertise. These results are compared to the automated system using Spearman rank correlation. Results show that this system can rank 15 test images, with varying degrees of inflammation, in strong agreement with five expert pathologists
Stellar Crowding and the Science Case for Extremely Large Telescopes
We present a study of the effect of crowding on stellar photometry. We
develop an analytical model through which we are able to predict the error in
magnitude and color for a given star for any combination of telescope
resolution, stellar luminosity function, background surface brightness, and
distance. We test our predictions with Monte Carlo simulations of the LMC
globular cluster NGC 1835, for resolutions corresponding to a seeing-limited
telescope, the , and an AO-corrected 30-m (near diffraction limited)
telescope. Our analytically predicted magnitude errors agree with the
simulation results to within 20%. The analytical model also predicts that
errors in color are strongly affected by the correlation of crowding--induced
photometric errors between bands as is seen in the simulations. Using
additional Monte Carlo simulations and our analytical crowding model, we
investigate the photometric accuracy which 30-m and 100-m Extremely Large
Telescopes (ELTs) will be able to achieve at distances extending to the Virgo
cluster. We argue that for stellar populations work, ELTs quickly become
crowding-limited, suggesting that low--Strehl AO systems may be sufficient for
this type of science.Comment: 25 pages, 19 figures in 35 separate files, Astronomical Journal,
accepte
Performance of a quasi-steady, multi megawatt, coaxial plasma thruster
The Los Alamos National Laboratory Coaxial Thruster Experiment (CTX) has been upgraded to enable the quasisteady operation of magnetoplasmadynamic (MPD) type thrusters at power levels from 2 to 40 MW for 10 ms. Diagnostics include an eight position, three axis magnetic field probe to measure magnetic field fluctuations during the pulse; a triple Langmuir probe to measure ion density, electron temperature, and plasma potential; and a time-of-flight neutral particle spectrometer to measure specific impulse. Here we report on the experimental observations and associated analysis and interpretation of long-pulse, quasisteady, coaxial thruster performance in the CTX device
Airborne sampling of aerosol particles: Comparison between surface sampling at Christmas Island and P-3 sampling during PEM-Tropics B
Bulk aerosol sampling of soluble ionic compounds from the NASA Wallops Island P-3 aircraft and a tower on Christmas Island during PEM-Tropics B provides an opportunity to assess the magnitude of particle losses in the University of New Hampshire airborne bulk aerosol sampling system. We find that most aerosol-associated ions decrease strongly with height above the sea surface, making direct comparisons between mixing ratios at 30 m on the tower and the lowest flight level of the P-3 (150 m) open to interpretation. Theoretical considerations suggest that vertical gradients of sea-salt aerosol particles should show exponential decreases with height. Observed gradients of Na+ and Mg2+, combining the tower observations with P-3 samples collected below 1 km, are well described by exponential decreases (r values of 0.88 and 0.87, respectively), though the curve fit underestimates average mixing ratios at the surface by 25%. Cascade impactor samples collected on the tower show that \u3e99% of the Na+ and Mg2+mass is on supermicron particles, 65% is in the 1â6 micron range, and just 20% resides on particles with diameters larger than 9 microns. These results indicate that our airborne aerosol sampling probes must be passing particles up to at least 6 microns with high efficiency. We also observed that nss SO42â and NH4+, which are dominantly on accumulation mode particles, tended to decrease between 150 and 1000 m, but they were often considerably higher at the lowest P-3 sampling altitudes than at the tower. This finding is presently not well understood
Isotopic characterization of nitrogen oxides (NO\u3ci\u3ex\u3c/i\u3e), nitrous acid (HONO), and nitrate (\u3ci\u3ep\u3c/i\u3eNO3-) from laboratory biomass burning during FIREX
New techniques have recently been developed and applied to capture reactive nitrogen species, including nitrogen oxides (NOx D NOCNO2), nitrous acid (HONO), nitric acid (HNO3), and particulate nitrate (pNO3 ), for accurate measurement of their isotopic composition. Here, we report â for the first time â the isotopic composition of HONO from biomass burning (BB) emissions collected during the Fire Influence on Regional to Global Environments Experiment (FIREX, later evolved into FIREX-AQ) at the Missoula Fire Science Laboratory in the fall of 2016. We used our newly developed annular denuder system (ADS), which was verified to completely capture HONO associated with BB in comparison with four other high-timeresolution concentration measurement techniques, including mist chamberâion chromatography (MCâIC), open-path Fourier transform infrared spectroscopy (OP-FTIR), cavityenhanced spectroscopy (CES), and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF)
Isotopic characterization of nitrogen oxides (NOx), nitrous acid (HONO), and nitrate (pNO3â) from laboratory biomass burning during FIREX
New techniques have recently been developed and applied to capture reactive nitrogen species, including nitrogen oxides (NOx=NO+NO2), nitrous acid (HONO), nitric acid (HNO3), and particulate nitrate (pNOâ3), for accurate measurement of their isotopic composition. Here, we report â for the first time â the isotopic composition of HONO from biomass burning (BB) emissions collected during the Fire Influence on Regional to Global Environments Experiment (FIREX, later evolved into FIREX-AQ) at the Missoula Fire Science Laboratory in the fall of 2016. We used our newly developed annular denuder system (ADS), which was verified to completely capture HONO associated with BB in comparison with four other high-time-resolution concentration measurement techniques, including mist chamberâion chromatography (MCâIC), open-path Fourier transform infrared spectroscopy (OP-FTIR), cavity-enhanced spectroscopy (CES), and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF).
In 20 âstackâ fires (direct emission within âź5âs of production by the fire) that burned various biomass materials from the western US, δ15NâNOx ranges from â4.3ââ° to +7.0ââ°, falling near the middle of the range reported in previous work. The first measurements of δ15NâHONO and δ18OâHONO in biomass burning smoke reveal a range of â5.3ââ° to +5.8ââ° and +5.2ââ° to +15.2ââ°, respectively. Both HONO and NOx are sourced from N in the biomass fuel, and δ15NâHONO and δ15NâNOx are strongly correlated (R2=0.89, p\u3c0.001), suggesting HONO is directly formed via subsequent chain reactions of NOx emitted from biomass combustion. Only 5 of 20 pNOâ3 samples had a sufficient amount for isotopic analysis and showed δ15N and δ18O of pNOâ3 ranging from â10.6ââ° to â7.4ââ° and +11.5ââ° to +14.8ââ°, respectively.
Our δ15N of NOx, HONO, and pNOâ3 ranges can serve as important biomass burning source signatures, useful for constraining emissions of these species in environmental applications. The δ18O of HONO and NOâ3 obtained here verify that our method is capable of determining the oxygen isotopic composition in BB plumes. The δ18O values for both of these species reflect laboratory conditions (i.e., a lack of photochemistry) and would be expected to track with the influence of different oxidation pathways in real environments. The methods used in this study will be further applied in future field studies to quantitatively track reactive nitrogen cycling in fresh and aged western US wildfire plumes
The Grizzly, February 18, 1983
Rally at Bomberger: Students Protest Criticism ⢠Rushes, Administration Meet Before Pledging ⢠Editorial: Staff Members Defend Grizzly ⢠USGA Notes ⢠Letters to the Editor: Letter to the Editor Receives Support; Constructive Criticism Appreciated; Student Interest Sparked; Irresponsible Groups Cause Anger ⢠Is Reaganomics a Reality? ⢠Admissions Standards at Ursinus ⢠President\u27s Corner ⢠Happy Birthday to U ⢠Talent Show Tonight ⢠Occupational Hazards ⢠Fighting Ursini Head to MACs Optimistically ⢠Inconsistency Still Haunting Women\u27s Basketball ⢠Gymnastics Ranked 13th ⢠Badminton Team Tops Rosemont and Moravian ⢠Lady Swimmers Boast 9-1 Record ⢠Werley\u27s Record Speaks for Itselfhttps://digitalcommons.ursinus.edu/grizzlynews/1094/thumbnail.jp
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