244 research outputs found
On the rms-radius of the proton
We study the world data on elastic electron-proton scattering in order to
determine the proton charge rms-radius. After accounting for the Coulomb
distortion and using a parameterization that allows to deal properly with the
higher moments we find a radius of 0.895+-0.018 fm, which is significantly
larger than the radii used in the past.Comment: 9 pages, 2 figures, submitted to Phys.Lett.
El teletrabajo y la productividad laboral en los trabajadores de la Municipalidad Distrital de Salitral Morropón, 2022
La presente investigación se ejecutó en la Municipalidad Distrital de Salitral,
provincia de Morropón, departamento de Piura; con el objetivo de determinar la
relación que existe entre el teletrabajo y la productividad laboral en los trabajadores
de dicha Municipalidad.
La metodología se realizó bajo un enfoque cuantitativo, con un nivel de
investigación correlacional, con un tipo de investigación básica con diseño no
experimental.
La población está integrada por 20 trabajadores y que al ser la muestra
censal es aplicado a la población total de estudio, se aplicó la técnica de la encuesta
y el instrumento fue el cuestionario, usando la escala de Likert, adicionalmente los
instrumentos fueron validados a través del juicio de expertos aplicando una
confiabilidad de Alfa de Cronbach.
Como principal resultado se obtuvo que el 60% de los trabajadores perciben
el teletrabajo como positivo, el 15% como relativo y el 25% como negativo de igual
manera el 70% de los trabajadores perciben la productividad laboral como positivo,
el 10% como relativo y el 20% como negativo.
Finalmente, entre las variables existe una relación directa y significativa,
obteniendo un valor de 0,891 que corrobora un grado muy significativo tal como se
había indicado en la hipótesis de investigación
The immediate environment of the Class 0 protostar VLA1623, on scales of ~50-100 AU, observed at millimetre and centimetre wavelengths
We present high angular resolution observations, taken with the Very Large
Array (VLA) and Multiple Element Radio Linked Interferometer Network (MERLIN)
radio telescopes, at 7mm and 4.4cm respectively, of the prototype Class 0
protostar VLA1623. At 7mm we detect two sources (VLA1623A & B) coincident with
the two previously detected components at the centre of this system. The
separation between the two is 1.2arcsec, or ~170AU at an assumed distance of
139pc. The upper limit to the size of the source coincident with each component
of VLA1623 is ~0.7arcsec, in agreement with previous findings. This corresponds
to a diameter of ~100AU at an assumed distance of 139pc. Both components show
the same general trend in their broadband continuum spectra, of a steeper dust
continuum spectrum shortward of 7mm and a flatter spectrum longward of this.
We estimate an upper limit to the VLA1623A disc mass of <0.13Msol and an
upper limit to its radius of ~50AU. The longer wavelength data have a spectral
index of \alpha~0.6+/-0.3. This is too steep to be explained by optically thin
free-free emission. It is most likely due to optically thick free-free
emission. Alternatively, we speculate that it might be due to the formation of
larger grains or planetesimals in the circumstellar disc. We estimate the mass
of VLA1623B to be <0.15M$sol. We can place a lower limit to its size of ~30x7
AU, and an upper limit to its diameter of ~100AU. The longer wavelength data of
VLA1623B also have a spectral index of \alpha~0.6+/-0.3. The nature of VLA1623B
remains a matter of debate. It could be a binary companion to the protostar, or
a knot in the radio jet from VLA1623A.Comment: 7 pages, 3 figures, 1 table, accepted for publication in MNRA
Self calibration of gravitational shear-galaxy intrinsic ellipticity correlation in weak lensing surveys
The galaxy intrinsic alignment is a severe challenge to precision cosmic
shear measurement. We propose to self-calibrate the induced gravitational
shear-galaxy intrinsic ellipticity correlation (the GI correlation,
\citealt{Hirata04b}) in weak lensing surveys with photometric redshift
measurement. (1) We propose a method to extract the intrinsic
ellipticity-galaxy density cross correlation (I-g) from the galaxy
ellipticity-density measurement in the same redshift bin. (2) We also find a
generic scaling relation to convert the extracted I-g correlation to the
demanded GI correlation. We perform concept study under simplified conditions
and demonstrate its capability to significantly reduce the GI contamination. We
discuss the impact of various complexities on the two key ingredients of the
self-calibration technique, namely the method to extract the I-g correlation
and the scaling relation between the I-g and the GI correlation. We expect none
of them is likely able to completely invalidate the proposed self-calibration
technique.Comment: 14 pages, 4 figures. Heavily expanded version. No changes in major
results and conclusions. Accepted to Ap
Optimising cosmic shear surveys to measure modifications to gravity on cosmic scales
We consider how upcoming photometric large scale structure surveys can be
optimized to measure the properties of dark energy and possible cosmic scale
modifications to General Relativity in light of realistic astrophysical and
instrumental systematic uncertainities. In particular we include flexible
descriptions of intrinsic alignments, galaxy bias and photometric redshift
uncertainties in a Fisher Matrix analysis of shear, position and position-shear
correlations, including complementary cosmological constraints from the CMB. We
study the impact of survey tradeoffs in depth versus breadth, and redshift
quality. We parameterise the results in terms of the Dark Energy Task Force
figure of merit, and deviations from General Relativity through an analagous
Modified Gravity figure of merit. We find that intrinsic alignments weaken the
dependence of figure of merit on area and that, for a fixed observing time, a
fiducial Stage IV survey plateaus above roughly 10,000deg2 for DE and peaks at
about 5,000deg2 as the relative importance of IAs at low redshift penalises
wide, shallow surveys. While reducing photometric redshift scatter improves
constraining power, the dependence is shallow. The variation in constraining
power is stronger once IAs are included and is slightly more pronounced for MG
constraints than for DE. The inclusion of intrinsic alignments and galaxy
position information reduces the required prior on photometric redshift
accuracy by an order of magnitude for both the fiducial Stage III and IV
surveys, equivalent to a factor of 100 reduction in the number of spectroscopic
galaxies required to calibrate the photometric sample.Comment: 13 pages, 6 figures. Fixed an error in equation 19 which changes the
right hand panels of figures 1 and 2, and modifies conclusions on the results
for fixed observing tim
Dispersion-Theoretical Analysis of the Nucleon Electromagnetic Formfactors
Dispersion relations allow for a coherent description of the nucleon
electromagnetic form factors measured over a large range of momentum transfer,
GeV. Including constraints from unitarity and
perturbative QCD, we present a novel parametrisation of the absorptive parts of
the various isoscalar and isovector nucleon form factors. Using the current
world data, we obtain results for the electromagnetic form factors, nucleon
radii and meson couplings. We stress the importance of measurements at large
momentum transfer to test the predictions of perturbative QCD.Comment: 33 pp, RevTEX or plain LaTeX, 7 figures (in ffig.uu
Constraining primordial non-Gaussianity with future galaxy surveys
We study the constraining power on primordial non-Gaussianity of future
surveys of the large-scale structure of the Universe for both near-term surveys
(such as the Dark Energy Survey - DES) as well as longer term projects such as
Euclid and WFIRST. Specifically we perform a Fisher matrix analysis forecast
for such surveys, using DES-like and Euclid-like configurations as examples,
and take account of any expected photometric and spectroscopic data. We focus
on two-point statistics and we consider three observables: the 3D galaxy power
spectrum in redshift space, the angular galaxy power spectrum, and the
projected weak-lensing shear power spectrum. We study the effects of adding a
few extra parameters to the basic LCDM set. We include the two standard
parameters to model the current value for the dark energy equation of state and
its time derivative, w_0, w_a, and we account for the possibility of primordial
non-Gaussianity of the local, equilateral and orthogonal types, of parameter
fNL and, optionally, of spectral index n_fNL. We present forecasted constraints
on these parameters using the different observational probes. We show that
accounting for models that include primordial non-Gaussianity does not degrade
the constraint on the standard LCDM set nor on the dark-energy equation of
state. By combining the weak lensing data and the information on projected
galaxy clustering, consistently including all two-point functions and their
covariance, we find forecasted marginalised errors sigma (fNL) ~ 3, sigma
(n_fNL) ~ 0.12 from a Euclid-like survey for the local shape of primordial
non-Gaussianity, while the orthogonal and equilateral constraints are weakened
for the galaxy clustering case, due to the weaker scale-dependence of the bias.
In the lensing case, the constraints remain instead similar in all
configurations.Comment: 20 pages, 10 Figures. Minor modifications; accepted by MNRA
Nucleon electromagnetic form factors and polarization observables in space-like and time-like regions
We perform a global analysis of the experimental data of the electromagnetic
nucleon form factors, in space-like and time-like regions. We give the
expressions of the observables in annihilation processes, such as , or , in terms of form factors. We discuss some
of the phenomenological models proposed in the literature for the space-like
region, and consider their analytical continuation to the time-like region.
After determining the parameters through a fit on the available data, we give
predictions for the observables which will be experimentally accessible with
large statistics, polarized annihilation reactions.Comment: 25 pages, 5 figures 7 table
Magnetism in reduced dimensions
We propose a short overview of a few selected issues of magnetism in reduced
dimensions, which are the most relevant to set the background for more
specialized contributions to the present Special Issue. Magnetic anisotropy in
reduced dimensions is discussed, on a theoretical basis, then with experimental
reports and views from surface to single-atom anisotropy. Then conventional
magnetization states are reviewed, including macrospins, single domains,
multidomains, and domain walls in stripes. Dipolar coupling is examined for
lateral interactions in arrays, and for interlayer interactions in films and
dots. Finally thermally-assisted magnetization reversal and superparamagnetism
are presented. For each topic we sought a balance between well established
knowledge and recent developments.Comment: 13 pages. Part of a Special Issue of the C. R. Physique devoted to
spinelectronics (2005
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