24,149 research outputs found
MEMORANDUM: Quality Assurance of 2016 Great Bay Estuary Water Quality Data and 2017 Cocheco River and Bellamy River Water Quality Data collected by UNH
The purpose of this memorandum is to document the results of quality assurance checks on the 2016-2017 water quality data collected by UNH for the Great Bay National Estuarine Research Reserve (GBNERR) System-Wide Monitoring Program, GBNERR Diel Sampling, and UNH Tidal Water Quality Monitoring stations. These programs were previously established in the NHDES Environmental Monitoring Database with project identifiers of “NERRTWQ”, “NERRDIEL”, and “JELTWQ”, respectively. UNH/GRB NERR reviewed these data to ensure that they met data quality objectives for the National Estuarine Research Reserve and its partners
Variability and polarization in the inner jet of 3C395
We present new results on the parsec-scale jet of the quasar 3C395, derived
from VLBI polarization sensitive observations made in 1995.91 and 1998.50 at
8.4, 15.4 and 22.2 GHz. The observations show a complex one-sided jet extending
up to 20 mas, with a projected magnetic field essentially aligned with the
radio jet. The emission is strongly dominated, in total intensity and
polarization, by the core and the inner jet region (of ~3 mas length). We have
studied the details of this dominant region finding clear structural variations
during this ~2.5 years period, in contrast with the apparent quietness of the
jet structure inferred from lower resolution VLBI observations. We observe the
ejection of a new component from the core and variations in the degree of
polarization of the inner jet components. We estimate a high Faraday Rotation
Measure close to the core, with a strong decrease along the inner jet.Comment: 7 pages, 4 figures, A&A in pres
Self-Selection Patterns among Return Migrants: Mexico 1990-2010
This paper analyzes the self-selection patterns among Mexican return migrants during the period from 1990 to 2010. Using census data, we can identify return migrants who have lived in the United States within the previous 5 years but who currently live in Mexico. To calculate the selection patterns, we non parametrically estimate the counterfactual wages that the return migrants would have experienced had they never migrated by using the wage structure of non migrants. We find evidence that the selection patterns change over time toward negative selection. For example, in 1990, the wages that the male return migrants would have experienced had they not migrated was 6 percent larger than the wages of male non migrants. However, by 2010, the difference had declined to -14 percent. The increasing negativity of the degree of selection is robust to the analysis of specific subgroups: rural and urban, men and women, and states with high migration rates and low migration rates. Moreover, the negative selection results for the period from 2000 to 2010 are robust to the use of different surveys that define a return migrant by using distinct characteristics. Additionally, we observe that the wages of return migrants are larger than those that the migrants would have obtained had they not migrated. This finding shows that migration has a positive effect on the Mexican economy.Mexican migration, self-selection, return migration, wages
Self-consistent 2D models of fast rotating early-type star
This work aims at presenting the first two-dimensional models of an isolated
rapidly rotating star that include the derivation of the differential rotation
and meridional circulation in a self-consistent way.We use spectral methods in
multidomains, together with a Newton algorithm to determine the steady state
solutions including differential rotation and meridional circulation for an
isolated non-magnetic, rapidly rotating early-type star. In particular we
devise an asymptotic method for small Ekman numbers (small viscosities) that
removes the Ekman boundary layer and lifts the degeneracy of the inviscid
baroclinic solutions.For the first time, realistic two-dimensional models of
fast-rotating stars are computed with the actual baroclinic flows that predict
the differential rotation and the meridional circulation for intermediate-mass
and massive stars. These models nicely compare with available data of some
nearby fast-rotating early-type stars like Ras Alhague ( Oph), Regulus
( Leo), and Vega ( Lyr). It is shown that baroclinicity drives
a differential rotation with a slow pole, a fast equator, a fast core, and a
slow envelope. The differential rotation is found to increase with mass, with
evolution (here measured by the hydrogen mass fraction in the core), and with
metallicity. The core-envelope interface is found to be a place of strong shear
where mixing will be efficient.Two-dimensional models offer a new view of
fast-rotating stars, especially of their differential rotation, which turns out
to be strong at the core-envelope interface. They also offer more accurate
models for interpreting the interferometric and spectroscopic data of
early-type stars.Comment: 16 pages, 17 figures, to appear in Astronomy and Astrophysic
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