812 research outputs found
An Experiment to Evaluate Skylab Earth Resources Sensors for Detection of the Gulf Stream
The author has identified the following significant results. An experiment to evaluate the Skylab earth resources package for observing ocean currents was performed in the Straits of Florida in January 1974. Data from the S190 photographic facility, S191 spectroradiometer and S192 multispectral scanner, were compared with surface observations. The anticyclonic edge of the Gulf Stream could be identified in the Skylab S190A and B photographs, but the cyclonic edge was obscured by clouds. The aircraft photographs were judged not useful for spectral analysis because vignetting caused the blue/green ratios to be dependent on the position in the photograph. The spectral measurement technique could not identify the anticyclonic front, but mass of Florida Bay water which was in the process of flowing into the Straits could be identified and classified. Monte Carlo simulations of the visible spectrum showed that the aerosol concentration could be estimated and a correction technique was devised
A polarized version of the CCFM equation for gluons
A derivation for a polarized CCFM evolution equation which is suitable to
describe the scaling behavior of the the unintegrated polarized gluon density
is given. We discuss the properties of this polarized CCFM equation and compare
it to the standard CCFM equation in the unpolarized case.Comment: 15 pages, 6 figures, RevTeX, some minor typos corrected, version to
appear in Phys. Rev.
Summary of results of an experiment to evaluate Skylab earth resources sensors for detection of the Gulf Stream
There are no author-identified significant results in this report
Search for Chargino and Neutralino Production at sqrt(s) = 192-209 GeV at LEP
Approximately 438 pb-1 of e+e- data from the OPAL detector, taken with the
LEP collider running at centre-of-mass energies of 192-209 Gev, are analyzed to
search for evidence of chargino pair production, e+e- -> tilde chi^+_1 tilde
chi^-_1, or neutralino associated production, e+e- -> tilde chi^0_2 tilde
chi^0_1. Limits are set at the 95% confidence level on the product of the
cross-section for the process e+e- -> tilde chi^+_1 tilde chi^-_1 and its
branching ratios to topologies containing jets and missing energy, of jest with
a lepton and missing energy, and on the product of the cross-section for e+e-
-> tilde chi^0_2 tilde chi^0_1 and its branching ratio to jets. R-parity
conservation is assumed throughout this paper. When these results are
interpreted in the context of the Constrained Minimal Supersymmetric Standard
Model, limits are also set on the masses of the tilde chi^+-_1, tilde chi^0_1
and tilde chi^0_2, and regions of the parameter space of the model are ruled
out. Nearly model-independent limits are also set at the 95% confidence level
on sigma(e+e- -> tilde chi^+_1 tilde chi^-_1) with the assumption that each
chargino decays via a W boson, and on sigma(e+e- -> tilde chi^0_2 tilde
chi^0_1) with the tilde chi^0_2 assumed to decay via a Z^0.Comment: 33 pages, 13 figures, Submitted to Eur Phys J.
Parton distribution functions from nonlocal light-cone operators with definite twist
We introduce the chiral-even and chiral-odd quark distributions as forward
matrix elements of related bilocal quark operators with well-defined
(geometric) twist. Thereby, we achieve a Lorentz invariant classification of
these distributions which differ from the conventional ones by explicitly
taking into account the necessary trace terms. The relations between both kinds
of distribution functions are given and the mismatch between their different
definition of twist is discussed. Wandzura-Wilczek--like relations between the
conventional distributions (based on dynamical twist) are derived by means of
geometric twist distribution functions.Comment: 17 pages, REVTEX, Extended version, The Introduction has been
rewritten, Setion V "Wandzura-Wilczek--like relations" and App. B are added;
Sign errors are correcte
Effects of COVID-19 Lockdown on Melanoma Diagnosis in Switzerland: Increased Tumor Thickness in Elderly Females and Shift towards Stage IV Melanoma during Lockdown.
At the early stages of the COVID-19 outbreak in 2020, Switzerland was among the countries with the highest number of SARS-CoV2-infections per capita in the world. Lockdowns had a remarkable impact on primary care access and resulted in postponed cancer screenings. The aim of this study was to investigate the effects of the COVID-19 lockdown on the diagnosis of melanomas and stage of melanomas at diagnosis. In this retrospective, exploratory cohort study, 1240 patients with a new diagnosis of melanoma were analyzed at five tertiary care hospitals in German-speaking Switzerland over a period of two years and three months. We compared the pre-lockdown (01/FEB/19-15/MAR/20, n = 655) with the lockdown (16/MAR/20-22/JUN/20, n = 148) and post-lockdown period (23/JUN/20-30/APR/21, n = 437) by evaluating patients' demographics and prognostic features using Breslow thickness, ulceration, subtype, and stages. We observed a short-term, two-week rise in melanoma diagnoses after the major lift of social lockdown restrictions. The difference of mean Breslow thicknesses was significantly greater in older females during the lockdown compared to the pre-lockdown (1.9 ± 1.3 mm, p = 0.03) and post-lockdown period (1.9 ± 1.3 mm, p = 0.048). Thickness increase was driven by nodular melanomas (2.9 ± 1.3 mm, p = 0.0021; resp. 2.6 ± 1.3 mm, p = 0.008). A proportional rise of advanced melanomas was observed during lockdown (p = 0.047). The findings provide clinically relevant insights into lockdown-related gender- and age-dependent effects on melanoma diagnosis. Our data highlight a stable course in new melanomas with a lower-than-expected increase in the post-lockdown period. The lockdown period led to a greater thickness in elderly women driven by nodular melanomas and a proportional shift towards stage IV melanoma. We intend to raise awareness for individual cancer care in future pandemic management strategies
Investigation of the rotational spectrum of CDOD and an astronomical search toward IRAS 162932422
Solar-type prestellar cores and protostars display large amounts of
deuterated organic molecules. Recent findings on CHDOH and CDOH toward
IRAS 16293-2422 suggest that even fully deuterated methanol, CDOD, may be
detectable as well. However, searches for CDOD are hampered in particular
by the lack of intensity information from a spectroscopic model. The objective
of the present investigation is to develop a spectroscopic model of CDOD in
low-lying torsional states that is sufficiently accurate to facilitate searches
for this isotopolog in space. We carried out a new measurement campaign for
CDOD involving two spectroscopic laboratories that covers the 34 GHz-1.1
THz range. A torsion-rotation Hamiltonian model based on the rho-axis method
was employed for our analysis. Our resulting model describes the ground and
first excited torsional states of CDOD well up to quantum numbers and . We derived a line list for radio-astronomical
observations from this model that is accurate up to at least 1.1 THz and should
be sufficient for all types of radio-astronomical searches for this methanol
isotopolog. This line list was used to search for CDOD in data from the
Protostellar Interferometric Line Survey of IRAS 162932422 obtained with the
Atacama Large Millimeter/submillimeter Array. While we found several emission
features that can be attributed largely to CDOD, their number is still not
sufficiently high enough to establish a clear detection. Nevertheless, the
estimate of 2 cm derived for the CDOD column density
may be viewed as an upper limit that can be compared to column densities of
CDOH, CHOD, and CHOH. The comparison indicates that the CDOD
column density toward IRAS 16293-2422 is in line with the enhanced D/H ratios
observed for multiply deuterated complex organic molecules.Comment: 10 pages total, including figures, tables, and references; abstract
slightly shortened; Astron. Astrophys., accepte
kt Effects in Direct-Photon Production
We discuss the phenomenology of initial-state parton-kt broadening in
direct-photon production and related processes in hadron collisions. After a
brief summary of the theoretical basis for a Gaussian-smearing approach, we
present a systematic study of recent results on fixed-target and collider
direct-photon production, using complementary data on diphoton and pion
production to provide empirical guidance on the required amount of kt
broadening. This approach provides a consistent description of the observed
pattern of deviation of next-to-leading order QCD calculations relative to the
direct-photon data, and accounts for the shape and normalization difference
between fixed-order perturbative calculations and the data. We also discuss the
uncertainties in this phenomenological approach, the implications of these
results on the extraction of the gluon distribution of the nucleon, and the
comparison of our findings to recent related work.Comment: LaTeX, uses revtex and epsf, 37 pages, 15 figure
Evidence for Parton kT Effects in High pT Particle Production
Inclusive pizero and direct-photon cross sections in the kinematic range 3.5
< pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c
proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current
Next-to-Leading-Order perturbative QCD calculations fail to adequately describe
the data for conventional choices of scales. Kinematic distributions from these
hard scattering events provide evidence that the interacting partons carry
significant initial-state parton transverse momentum (kT). Incorporating these
kT effects phenomenologically greatly improves the agreement between
calculations and the measured cross sections.Comment: 11 pages including 6 pages of figures with caption
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