529 research outputs found
Illusory Decoherence
If a quantum experiment includes random processes, then the results of
repeated measurements can appear consistent with irreversible decoherence even
if the system's evolution prior to measurement was reversible and unitary. Two
thought experiments are constructed as examples.Comment: 10 pages, 3 figure
Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum
We reconsider the scenario in which the knee in the cosmic ray spectrum is
explained as due to a change in the escape mechanism of cosmic rays from the
Galaxy from one dominated by transverse diffusion to one dominated by drifts.
We solve the diffusion equations adopting realistic galactic field models and
using diffusion coefficients appropriate for strong turbulence (with a
Kolmogorov spectrum of fluctuations) and consistent with the assumed magnetic
fields. We show that properly taking into account these effects leads to a
natural explanation of the knee in the spectrum, and a transition towards a
heavier composition above the knee is predicted.Comment: 17 pp., 6 figures; revised version with minor changes. To appear in
JHE
General Relativistic Mean Field Theory for Rotating Nuclei
We formulate a general relativistic mean field theory for rotating nuclei
starting from the special relativistic model Lagrangian. The
tetrad formalism is adopted to generalize the model to the accelerated frame.Comment: 13 pages, REVTeX, no figures, submitted to Phys. Rev. Lett., the word
`curved' is replaced by `non-inertial' or `accelerated' in several places to
clarify the physical situation interested, some references are added, more
detail discussions are given with omitting some redundant sentence
Magnetic Coordinate Systems
Geospace phenomena such as the aurora, plasma motion, ionospheric currents
and associated magnetic field disturbances are highly organized by Earth's main
magnetic field. This is due to the fact that the charged particles that
comprise space plasma can move almost freely along magnetic field lines, but
not across them. For this reason it is sensible to present such phenomena
relative to Earth's magnetic field. A large variety of magnetic coordinate
systems exist, designed for different purposes and regions, ranging from the
magnetopause to the ionosphere. In this paper we review the most common
magnetic coordinate systems and describe how they are defined, where they are
used, and how to convert between them. The definitions are presented based on
the spherical harmonic expansion coefficients of the International Geomagnetic
Reference Field (IGRF) and, in some of the coordinate systems, the position of
the Sun which we show how to calculate from the time and date. The most
detailed coordinate systems take the full IGRF into account and define magnetic
latitude and longitude such that they are constant along field lines. These
coordinate systems, which are useful at ionospheric altitudes, are
non-orthogonal. We show how to handle vectors and vector calculus in such
coordinates, and discuss how systematic errors may appear if this is not done
correctly
Association between hourly wages and dietary intake after the first phase of implementation of the Minneapolis minimum wage ordinance
Objective: In 2018, Minneapolis began phased implementation of an ordinance to increase the local minimum wage to 15/h. We sought to determine whether the first phase of implementation was associated with changes in frequency of consumption of fruits and vegetables (F&V), whole-grain-rich foods, and foods high in added sugars among low-wage workers. Design: Natural experiment. Setting: The Wages Study is a prospective cohort study of 974 low-wage workers followed throughout the phased implementation of the ordinance (2018-2022). We used difference-in-difference analysis to compare outcomes among workers in Minneapolis, Minnesota, to those in a comparison city (Raleigh, North Carolina). We assessed wages using participants' pay stubs and dietary intake using the National Cancer Institute Dietary Screener Questionnaire. Participants: Analyses use the first two waves of Wages data (2018 (baseline), 2019) and includes 267 and 336 low-wage workers in Minneapolis and Raleigh, respectively. Results: After the first phase of implementation, wages increased in both cities, but the increase was 0·84 greater in Minneapolis (P = 0·02). However, the first phase of the policy's implementation was not associated with changes in daily frequency of consumption of F&V (IRR = 1·03, 95 % CI: 0·86, 1·24, P = 0·73), whole-grain-rich foods (IRR = 1·23, 95 % CI: 0·89, 1·70, P = 0·20), or foods high in added sugars (IRR = 1·13, 95 % CI: 0·86, 1·47, P = 0·38) among workers in Minneapolis compared to Raleigh. Conclusions: The first phase of implementation of the Minneapolis minimum wage policy was associated with increased wages, but not with changes in dietary intake. Future research should examine whether full implementation is associated dietary changes
Field and Petrographic Analysis of the Indian Peak-Caliente Caldera Complex at Condor and English Canyons in Eastern Nevada
The Indian Peak-Caliente Caldera Complex, or IPCCC, is an ideal site to study how large-scale tectonic forces can influence mineralogy on a local scale. This research was completed and compiled by the Tectonics and Mineralogy classes at Southern Utah University during a joint class field study and subsequent laboratory analyses. During the field trip, the main focuses were to observe caldera collapse relationships and ignimbrite features and to collect samples at Condor Canyon and English Canyon, two sites near the border between Nevada and Utah within the IPCCC. After the field trip, the Tectonics class completed a detailed literature review of the overall tectonic evolution of the region while the Mineralogy students petrographically analyzed the collected samples. This report provides a summary of the results, including mineralogical descriptions; an interpretation of a piece-meal, or piston-like, collapse of the caldera complex; and a connection between the local geology and the regional tectonic setting
A-dependence of nuclear transparency in quasielastic A(e,e'p) at high Q^2
The A-dependence of the quasielastic A(e,e'p) reaction has been studied at
SLAC with H-2, C, Fe, and Au nuclei at momentum transfers Q^2 = 1, 3, 5, and
6.8 (GeV/c)^2. We extract the nuclear transparency T(A,Q^2), a measure of the
average probability that the struck proton escapes from the nucleus A without
interaction. Several calculations predict a significant increase in T with
momentum transfer, a phenomenon known as Color Transparency. No significant
rise within errors is seen for any of the nuclei studied.Comment: 5 pages incl. 2 figures, Caltech preprint OAP-73
Automated Coronal Hole Detection using Local Intensity Thresholding Techniques
We identify coronal holes using a histogram-based intensity thresholding
technique and compare their properties to fast solar wind streams at three
different points in the heliosphere. The thresholding technique was tested on
EUV and X-ray images obtained using instruments onboard STEREO, SOHO and
Hinode. The full-disk images were transformed into Lambert equal-area
projection maps and partitioned into a series of overlapping sub-images from
which local histograms were extracted. The histograms were used to determine
the threshold for the low intensity regions, which were then classified as
coronal holes or filaments using magnetograms from the SOHO/MDI. For all three
instruments, the local thresholding algorithm was found to successfully
determine coronal hole boundaries in a consistent manner. Coronal hole
properties extracted using the segmentation algorithm were then compared with
in situ measurements of the solar wind at 1 AU from ACE and STEREO. Our results
indicate that flux tubes rooted in coronal holes expand super-radially within 1
AU and that larger (smaller) coronal holes result in longer (shorter) duration
high-speed solar wind streams
Using an Observational Framework to investigate adult language input to young children in a naturalistic environment
The correlation between the communicative intent of parents, in terms of their expectation of a response and the response patterns of young children aged 23—25 months during parent—child interactions, was investigated. An Observational Framework was used to code these parameters in interactions between 36 children and their mothers. The children were assigned by cluster analysis to `advanced', `typical' and `delayed' language groups and their responses were coded with respect to the degree of correctness or appropriateness within the interaction. Differences in both the parental response expectations and the children's response patterns across the three clusters are discussed
Dynamics of escaping Earth ejecta and their collision probability with different Solar System bodies
It has been suggested that the ejection to interplanetary space of
terrestrial crustal material, accelerated in a large impact, may result in the
interchange of biological material between Earth and other Solar System bodies.
In this paper, we analyze the fate of debris ejected from Earth by means of
numerical simulations of the dynamics of a large collection of test particles.
This allows us to determine the probability and conditions for the collision of
ejecta with other planets of the Solar System. We also estimate the amount of
particles falling-back to Earth as a function of time after being ejected. We
find that, in general, the collision rates of Earth ejecta with Venus and the
Moon, as well as the fall-back rates, are consistent with results reported in
the literature. By considering a larger number of particles than in all
previous calculations we have also determined directly the collision
probability with Mars and, for the first time, computed collision probabilities
with Jupiter. We find that the collision probability with Mars is greater than
values determined from collision cross section estimations previously reported.Comment: 9 pages, 4 figures & 1 table. Submitted to Icaru
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