1,948 research outputs found
Morphological and molecular diversity among cassava genotypes.
The objective of this work was to characterize morphologically and molecularly the genetic diversity of cassava accessions, collected from different regions in Brazil. A descriptive analysis was made for 12 morphological traits in 419 accessions. Data was transformed into binary data for cluster analysis and analysis of molecular variance. A higher proportion of white or cream (71%) root cortex color was found, while flesh colors were predominantly white (49%) and cream (42%). Four accession groups were classified by the cluster analysis, but they were not grouped according to their origin, which indicates that diversity is not structured in space. The variation was greater within regions (95.6%). Sixty genotypes were also evaluated using 14 polymorphic microsatellite markers. Molecular results corroborated the morphological ones, showing the same random distribution of genotypes, with no grouping according to origin. Diversity indices were high for each region, and a greater diversity was found within regions, with: a mean number of alleles per locus of 3.530; observed and expected heterozygosity of 0.499 and 0.642, respectively; and Shannon index of 1.03. The absence of spatial structure among cassava genotypes according to their origins shows the anthropic influence in the distribution and movement of germplasm, both within and among regions.TÃtulo em português: Diversidade morfológica e molecular entre genótipos de mandioca
Absolute calibration of the LOPES antenna system
Radio emission in extensive air showers arises from an interaction with the
geomagnetic field and is subject of theoretical studies. This radio emission
has advantages for the detection of high energy cosmic rays compared to
secondary particle or fluorescence measurement methods. Radio antennas like the
LOPES30 antenna system are suited to investigate this emission process by
detecting the radio pulses. The characteristic observable parameters like
electric field strength and pulse length require a calibration which was done
with a reference radio source resulting in an amplification factor representing
the system behavior in the environment of the KASCADE-Grande experiment.
Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is
calibrated absolutely for systematic analyses of the radio emission.Comment: 5 pages, Proceedings of International Workshop on Acoustic and Radio
EeV Neutrino detection Activities: ARENA, May 17-19, 2005, DESY Zeuthe
Single-qubit unitary gates by graph scattering
We consider the effects of plane-wave states scattering off finite graphs, as
an approach to implementing single-qubit unitary operations within the
continuous-time quantum walk framework of universal quantum computation. Four
semi-infinite tails are attached at arbitrary points of a given graph,
representing the input and output registers of a single qubit. For a range of
momentum eigenstates, we enumerate all of the graphs with up to vertices
for which the scattering implements a single-qubit gate. As increases, the
number of new unitary operations increases exponentially, and for the
majority correspond to rotations about axes distributed roughly uniformly
across the Bloch sphere. Rotations by both rational and irrational multiples of
are found.Comment: 8 pages, 7 figure
Low-energy electron scattering from methanol and ethanol
Measured and calculated differential cross sections for elastic (rotationally unresolved) electron scattering from two primary alcohols, methanol (CH3OH) and ethanol (C2H5OH), are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°–130°. There are no previous reports of experimental electron scattering differential cross sections for CH3OH and C2H5OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well
Epidural Block for Cesarean Section. A Comparative Study between 0.5% Racemic Bupivacaine (S50-R50) and 0.5% Enantiomeric Excess Bupivacaine (S75-R25) Associated with Sufentanil
SummaryBackground and objectivesEpidural 0.5% racemic bupivacaine associated with opioids is a technique used in cesarean sections; however, its toxicity has been questioned. 50% Enantiomeric excess bupivacaine has lower cardio- and neurotoxicity. The efficacy of epidural 0.5% racemic bupivacaine and 0.5% enantiomeric excess bupivacaine associated with sufentanil in parturients undergoing cesarean sections was evaluated.MethodsFifty gravida at term, undergoing elective cesarean section under epidural block, were divided in two groups according to the local anesthetic used: Group I – 0.5% racemic bupivacaine with vasoconstrictor; and Group II – 0.5% enantiomeric excess bupivacaine (S75-R25) with vasoconstrictor. In both groups, the local anesthetic (100 mg) was associated with sufentanil (20 μg), and a total of 24 mL of the solution was used. The following parameters were evaluated: latency of the sensitive blockade; maximal level of the sensitive blockade; degree for motor blockade; time of motor blockade regression; duration of analgesia; maternal side effects; and neonatal repercussions.ResultsLatency, maximal level of sensitive blockade, degree of motor blockade, and duration of analgesia were similar in both groups; the mean time for regression of the motor blockade was significantly smaller in Group II. The incidence of side effects was similar in both groups. Maternal cardiocirculatory changes and neonatal repercussions were not observed.ConclusionsEpidural racemic bupivacaine and 50% enantiomeric excess bupivacaine provided adequate anesthesia for cesarean sections. 50% Enantiomeric excess bupivacaine is a promising alternative for this procedure, since it has faster regression of the motor blockade, which is desirable in obstetric patients
IceCube-Plus: An Ultra-High Energy Neutrino Telescope
While the first kilometer-scale neutrino telescope, IceCube, is under
construction, alternative plans exist to build even larger detectors that will,
however, b e limited by a much higher neutrino energy threshold of 10 PeV or
higher rather than 10 to 100 GeV. These future projects detect radio and
acoustic pulses as w ell as air showers initiated by ultra-high energy
neutrinos. As an alternative, we here propose an expansion of IceCube, using
the same strings, placed on a gri d with a spacing of order 500 m. Unlike other
proposals, the expanded detector uses methods that are understood and
calibrated on atmospheric neutrinos. Atmosp heric neutrinos represent the only
background at the energies under consideratio n and is totally negligible.
Also, the cost of such a detector is understood. We conclude that supplementing
the 81 IceCube strings with a modest number of addi tional strings spaced at
large distances can almost double the effective volume of the detector.
Doubling the number of strings on a 800 m grid can deliver a d etector that
this a factor of 5 larger for horizontal muons at modest cost.Comment: Version to be published in JCA
The NANOGrav 12.5 yr Data Set: Observations and Narrowband Timing of 47 Millisecond Pulsars
We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars observed from 2004 to 2017 at the Arecibo Observatory and the Green Bank Telescope by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The observing cadence was three to four weeks for most pulsars over most of this time span, with weekly observations of six sources. These data were collected for use in low-frequency gravitational wave searches and for other astrophysical purposes. We detail our observational methods and present a set of TOA measurements, based on narrowband analysis, in which many TOAs are calculated within narrow radio-frequency bands for data collected simultaneously across a wide bandwidth. A separate set of wideband TOAs will be presented in a companion paper. We detail a number of methodological changes, compared to our previous work, which yield a cleaner and more uniformly processed data set. Our timing models include several new astrometric and binary pulsar measurements, including previously unpublished values for the parallaxes of PSRs J1832−0836 and J2322+2057, the secular derivatives of the projected semimajor orbital axes of PSRs J0613−0200 and J2229+2643, and the first detection of the Shapiro delay in PSR J2145−0750. We report detectable levels of red noise in the time series for 14 pulsars. As a check on timing model reliability, we investigate the stability of astrometric parameters across data sets of different lengths. We also report flux density measurements for all pulsars observed. Searches for stochastic and continuous gravitational waves using these data will be subjects of forthcoming publications
- …