1,563 research outputs found
Overlap of QRPA states based on ground states of different nuclei --mathematical properties and test calculations--
The overlap of the excited states in quasiparticle random-phase approximation
(QRPA) is calculated in order to simulate the overlap of the intermediate
nuclear states of the double-beta decay. Our basic idea is to use the
like-particle QRPA with the aid of the closure approximation and calculate the
overlap as rigorously as possible by making use of the explicit equation of the
QRPA ground state. The formulation is shown in detail, and the mathematical
properties of the overlap matrix are investigated. Two test calculations are
performed for relatively light nuclei with the Skyrme and volume delta-pairing
energy functionals. The validity of the truncations used in the calculation is
examined and confirmed.Comment: 17 pages, 15 figures, full paper following arXiv:1205.5354 and Phys.
Rev. C 86 (2012) 021301(R
Resolving a One-Year Ecesis Interval for Alaska Paper Birch: Dating a Rockfall Event, Wishbone Hill, Southcentral Alaska
Numerous large boulders at the base of Wishbone Hill, northeast of Anchorage, Alaska, suggest a historic rockfall event and potential for future surface instability, putting lives and property at risk. The source of the rockfall-boulders is an exposed syncline with a cliff face composed of conglomerate. The age of trees growing atop boulders provides a minimum exposure-age of those boulders and, thus, the rockfall event. To determine when the rockfall occurred, we dated trees growing atop the boulders using tree-ring samples collected from 30 Alaska paper birch trees. After mounting and polishing, each tree-ring sample was dot-counted, and tree-ring widths were measured using Measure J2X software to generate a master chronology (1938-2017). To estimate the youngest age for the rockfall event, we recorded pith-year for each sample. For samples lacking a pith (n=21), we used pith indicators to match existing rings to diagrams of corresponding ring widths, projecting approximate pith for each sample. All samples we corrected for sampling height (mean=0.8m) using a low estimate growth rate (0.6m/yr). The oldest birch tree sampled included pith and, with height correction, we estimate a germination year of 1936. When using first-year growth as an event’s temporal marker, accounting for the ecesis interval, the time between the availability of a new surface (i.e., boulders) and germination provides a more representative date of the event than using the pith/germination date alone. Considering birch ecesis and primary observations recorded in 1935, we propose that the rockfall event most likely occurred in 1934-1935. This finding suggests an ecesis interval as low as one year for Alaska paper birch in fresh rockfall areas. The risk of another destabilizing event may prompt those utilizing this area for recreational and residential purposes to reconsider future use
Comparison of Two Lidar Methods of Wind Measurement by Cloud Tracking
We measured the horizontal wind speed vector with two separate lidar cloud tracking techniques. Data were taken during two measurement campaigns: HOLO-1, at Utah State University (USU), Utah, and HOLO-2 at St. Anselm College, New Hampshire. Army Research Office Lidar (AROL-2), Holographic Airborne Rotating Lidar Instrument (HARLIE), and a wide-angle camera were used during HOLO-1. Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS) also participated in HOLO-2. Two measurement methods are described, and selected results from the two HOLO campaigns are shown
Energy Content of Seeds of Switchgrass (Panicum virgatum) in the Diet of Mourning Doves (Zenaida macroura) in Southeastern New Mexico
Switchgrass (Panicum virgatum) is a common forage plant that grows over much of the United States. It has drawn interest as a possible feedstock for biofuels, is used as forage for livestock, is planted for soil conservation, and is a component of the diet of some species of wildlife. We analyzed the energy content of seeds of switchgrass obtained from the crops of mourning doves (Zenaida macroura) collected from plains-mesa sand-scrub in Lea and Eddy counties, New Mexico. Seeds were removed from crops and dried for 48 hours at 60°C to remove moisture and standardize masses. Seeds were then analyzed for gross caloric value (i.e., energy content) in an oxygen bomb calorimeter. Energy content of seeds of switchgrass from New Mexico averaged 18.4 J/kg (4.4 kcal/g—standard deviation, 0.7 J/kg [0.2 kcal/g]) and was lower than that of most other food items previously reported from the diet of mourning doves
Step Aerobics: A Kinematic And Kinetic Analysis
Step aerobics has become a popular form of aerobic exercise. Information regarding the mechanical stresses on the lower extremity during step aerobics may guide in determining the factors contributing to the risk of injury during progressions within this activity. Therefore, the purpose of this study was to investigate selected kinematic and kinetic variables during step aerobics at three heights and two cadences. Nine female subjects, mean age of 25.22 ± 4.3 yrs and mean height of 164 . 81 ±4.5 cm, performed conventional step aerobics. A conventional step was defined as right foot up, left foot up, right foot down, and left foot down. Three step heights of 4,6, and 8 in. and two cadences of 100 and 120 steps/minute (SPM) were performed by each subject in random order. These conditions were similar to those used in a typical step aerobics class. High speed cinematographic data collected at 90 frames/second were used to determine 2-D coordinates of the right leg in the sagittal plane. A Kistler force platform was used to measure ground reaction forces (GRF) of the right foot during step down.
Identical mean vertical peak GRF were observed for both cadences. These forces were 1. 60, 1 .66, and 1 .76 percent body weight, at 4,6, and 8 in. respectively.
Thus, increasing cadence from 100 to 120 SPM did not increase the risk of experiencing higher GRF in the lower extremity. Significant differences were found only between compressive joint forces and step heights at the ankle, knee, and hip. The magnitude of these joint forces were similar, indicating that there was no dissipation of forces throughout the lower extremity, unlike what has been observed during walking and running. Examination of the knee and hip moments revealed oscillating patterns that varied at different heights and cadences. This may indicate that these joints were used uniquely by individuals in stabilization of the body during the step down phase. With the possible exception of injury due to the lack of force dissipation, these findings suggest that progression of height and/or cadence may not be risk factors contributing to injury
Search for a T-odd, P-even Triple Correlation in Neutron Decay
Background: Time-reversal-invariance violation, or equivalently CP violation,
may explain the observed cosmological baryon asymmetry as well as signal
physics beyond the Standard Model. In the decay of polarized neutrons, the
triple correlation D\cdot(p_{e}\timesp_{\nu}) is a parity-even,
time-reversal- odd observable that is uniquely sensitive to the relative phase
of the axial-vector amplitude with respect to the vector amplitude. The triple
correlation is also sensitive to possible contributions from scalar and tensor
amplitudes. Final-state effects also contribute to D at the level of 1e-5 and
can be calculated with a precision of 1% or better. Purpose: We have improved
the sensitivity to T-odd, P-even interactions in nuclear beta decay. Methods:
We measured proton-electron coincidences from decays of longitudinally
polarized neutrons with a highly symmetric detector array designed to cancel
the time-reversal-even, parity-odd Standard-Model contributions to polarized
neutron decay. Over 300 million proton-electron coincidence events were used to
extract D and study systematic effects in a blind analysis. Results: We find D
= [-0.94\pm1.89(stat)\pm0.97(sys)]e-4. Conclusions: This is the most sensitive
measurement of D in nuclear beta decay. Our result can be interpreted as a
measurement of the phase of the ratio of the axial-vector and vector coupling
constants (CA/CV= |{\lambda}|exp(i{\phi}_AV)) with {\phi}_AV = 180.012{\deg}
\pm0.028{\deg} (68% confidence level) or to constrain time-reversal violating
scalar and tensor interactions that arise in certain extensions to the Standard
Model such as leptoquarks. This paper presents details of the experiment,
analysis, and systematic- error corrections.Comment: 21 pages, 22 figure
Lineage divergence detected in the malaria vector Anopheles marajoara (Diptera: Culicidae) in Amazonian Brazil
<p>Abstract</p> <p>Background</p> <p>Cryptic species complexes are common among anophelines. Previous phylogenetic analysis based on the complete mtDNA <it>COI </it>gene sequences detected paraphyly in the Neotropical malaria vector <it>Anopheles marajoara</it>. The "Folmer region" detects a single taxon using a 3% divergence threshold.</p> <p>Methods</p> <p>To test the paraphyletic hypothesis and examine the utility of the Folmer region, genealogical trees based on a concatenated (<it>white </it>+ 3' <it>COI </it>sequences) dataset and pairwise differentiation of <it>COI </it>fragments were examined. The population structure and demographic history were based on partial <it>COI </it>sequences for 294 individuals from 14 localities in Amazonian Brazil. 109 individuals from 12 localities were sequenced for the nDNA <it>white </it>gene, and 57 individuals from 11 localities were sequenced for the ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS2).</p> <p>Results</p> <p>Distinct <it>A. marajoara </it>lineages were detected by combined genealogical analysis and were also supported among <it>COI </it>haplotypes using a median joining network and AMOVA, with time since divergence during the Pleistocene (<100,000 ya). <it>COI </it>sequences at the 3' end were more variable, demonstrating significant pairwise differentiation (3.82%) compared to the more moderate 2.92% detected by the Folmer region. Lineage 1 was present in all localities, whereas lineage 2 was restricted mainly to the west. Mismatch distributions for both lineages were bimodal, likely due to multiple colonization events and spatial expansion (~798 - 81,045 ya). There appears to be gene flow within, not between lineages, and a partial barrier was detected near Rio Jari in Amapá state, separating western and eastern populations. In contrast, both nDNA data sets (<it>white </it>gene sequences with or without the retention of the 4th intron, and ITS2 sequences and length) detected a single <it>A. marajoara </it>lineage.</p> <p>Conclusions</p> <p>Strong support for combined data with significant differentiation detected in the <it>COI </it>and absent in the nDNA suggest that the divergence is recent, and detectable only by the faster evolving mtDNA. A within subgenus threshold of >2% may be more appropriate among sister taxa in cryptic anopheline complexes than the standard 3%. Differences in demographic history and climatic changes may have contributed to mtDNA lineage divergence in <it>A. marajoara</it>.</p
Comment on "Evidence for Neutrinoless Double Beta Decay"
We comment on the recent claim for the experimental observation of
neutrinoless double-beta decay. We discuss several limitations in the analysis
provided in that paper and conclude that there is no basis for the presented
claim.Comment: A comment written to Modern Physics Letters A. 4 pages, no figures.
Updated version, accepted for publicatio
emiT: an apparatus to test time reversal invariance in polarized neutron decay
We describe an apparatus used to measure the triple-correlation term (\D
\hat{\sigma}_n\cdot p_e\times p_\nu) in the beta-decay of polarized neutrons.
The \D-coefficient is sensitive to possible violations of time reversal
invariance. The detector has an octagonal symmetry that optimizes
electron-proton coincidence rates and reduces systematic effects. A beam of
longitudinally polarized cold neutrons passes through the detector chamber,
where a small fraction beta-decay. The final-state protons are accelerated and
focused onto arrays of cooled semiconductor diodes, while the coincident
electrons are detected using panels of plastic scintillator. Details regarding
the design and performance of the proton detectors, beta detectors and the
electronics used in the data collection system are presented. The neutron beam
characteristics, the spin-transport magnetic fields, and polarization
measurements are also described.Comment: 15 pages, 13 figure
The BNO-LNGS joint measurement of the solar neutrino capture rate in 71Ga
We describe a cooperative measurement of the capture rate of solar neutrinos
by the reaction 71Ga(\nu_e,e^-)71Ge. Extractions were made from a portion of
the gallium target in the Russian-American Gallium Experiment SAGE and the
extraction samples were transported to the Gran Sasso laboratory for synthesis
and counting at the Gallium Neutrino Observatory GNO. Six extractions of this
type were made and the resultant solar neutrino capture rate was 64
^{+24}_{-22} SNU, which agrees well with the overall result of the gallium
experiments. The major purpose of this experiment was to make it possible for
SAGE to continue their regular schedule of monthly solar neutrino extractions
without interruption while a separate experiment was underway to measure the
response of 71Ga to neutrinos from an 37Ar source. As side benefits, this
experiment proved the feasibility of long-distance sample transport in ultralow
background radiochemical experiments and familiarized each group with the
methods and techniques of the other.Comment: 7 pages, no figures; minor additions in version
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