47 research outputs found
Contextual and personal resources in unemployed job search: An intraâindividual perspective
Drawing from conservation of resources (COR) theory and the equifinality principle, we challenge the prominent âtheâmoreâresourcesâtheâbetterâ understanding by examining both the additive and interactive effects of contextual (i.e., networking behaviors and social support) and personal (i.e., job search selfâefficacy) resources on job seeking. Specifically, based on COR theory's resource gain corollary, we propose that higher levels of each resource are positively related to job search intensity and the number of interviews obtained (an additive effect). However, based on the equifinality principle that various resources can contribute to the same goal, we propose that each type of resource can compensate for low levels of the other (an interactive effect). In a fourâwave study following 89 unemployed job seekers over 6âmonths, we find positive intraâindividual relationships between networking behaviors and job search selfâefficacy with job search intensity. We find that networking behaviors and job search selfâefficacy are also positively related to the number of job interviews obtained and indirectly related through job search intensity for networking behaviors. In line with our predictions, high levels of either networking behaviors or job search selfâefficacy compensate for low levels of the other resource when predicting job search intensity and the number of interviews obtained
ESO Imaging Survey: infrared observations of CDF-S and HDF-S
This paper presents infrared data obtained from observations carried out at
the ESO 3.5m New Technology Telescope (NTT) of the Hubble Deep Field South
(HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part
of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to
promote follow-up observations with the VLT. In the HDF-S field the infrared
observations cover an area of ~53 square arcmin, encompassing the HST WFPC2 and
STIS fields, in the JHKs passbands. The seeing measured in the final stacked
images ranges from 0.79" to 1.22" and the median limiting magnitudes (AB
system, 2" aperture, 5sigma detection limit) are J_AB~23.0, H_AB~22.8 and
K_AB~23.0 mag. Less complete data are also available in JKs for the adjacent
HST NICMOS field. For CDF-S, the infrared observations cover a total area of
\~100 square arcmin, reaching median limiting magnitudes (as defined above) of
J_AB~23.6 and K_AB~22.7 mag. For one CDF-S field H-band data are also
available. This paper describes the observations and presents the results of
new reductions carried out entirely through the un-supervised, high-throughput
EIS Data Reduction System and its associated EIS/MVM C++-based image processing
library developed, over the past 5 years, by the EIS project and now publicly
available. The paper also presents source catalogs extracted from the final
co-added images which are used to evaluate the scientific quality of the survey
products, and hence the performance of the software. This is done comparing the
results obtained in the present work with those obtained by other authors from
independent data and/or reductions carried out with different software packages
and techniques. The final science-grade catalogs and co-added images are
available at CDS.Comment: Accepted for publication in A&A, 13 pages, 12 figures; a full
resolution version of the paper is available from
http://www.astro.ku.dk/~lisbeth/eisdata/papers/4528.pdf ; related catalogs
and images are available through http://www.astro.ku.dk/~lisbeth/eisdata
Coexisting conical bipolar and equatorial outflows from a high-mass protostar
The BN/KL region in the Orion molecular cloud is an archetype in the study of
the formation of stars much more massive than the Sun. This region contains
luminous young stars and protostars, but it is difficult to study because of
overlying dust and gas. Our basic expectations are shaped to some extent by the
present theoretical picture of star formation, the cornerstone of which is that
protostars acrete gas from rotating equatorial disks, and shed angular momentum
by ejecting gas in bipolar outflows. The main source of the outflow in the
BN/KL region may be an object known as radio source I, which is commonly
believed to be surrounded by a rotating disk of molecular material. Here we
report high-resolution observations of silicon monoxide (SiO) and water maser
emission from the gas surrounding source I; we show that within 60 AU (about
the size of the Solar System), the region is dominated by a conical bipolar
outflow, rather than the expected disk. A slower outflow, close to the
equatorial plane of the protostellar system, extends to radii of 1,000 AU.Comment: 10 pages, 2 figures. Accepted by Nature. To appear December 199
Nuclear obscuration in the high-ionization Seyfert 2 galaxy Tol 0109-383
We report the BeppoSAX detection of a hard X-ray excess in the X-ray spectrum
of the classical high-ionization Seyfert 2 galaxy Tol0109-383. The X-ray
emission of this source observed below 7 keV is dominated by reflection from
both cold and ionized gas, as seen in the ASCA data. The excess hard X-ray
emission is presumably due to the central source absorbed by an optically thick
obscuring torus with N(H)~2e24 cm-2. The strong cold X-ray reflection, if it is
produced at the inner surface of the torus, is consistent with the picture
where much of the inner nucleus of Tol0109-383 is exposed to direct view, as
indicated by optical and infrared properties. However, the X-ray absorption
must occur at small radii in order to hide the central X-ray source but leave
the optical high-ionization emission line region unobscured. This may also be
the case for objects like the Seyfert 1 galaxy Mrk231.Comment: 7 pages, MNRAS in pres
The density and peculiar velocity fields of nearby galaxies
We review the quantitative science that can be and has been done with
redshift and peculiar velocity surveys of galaxies in the nearby universe.
After a brief background setting the cosmological context for this work, the
first part of this review focuses on redshift surveys. The practical issues of
how redshift surveys are carried out, and how one turns a distribution of
galaxies into a smoothed density field, are discussed. Then follows a
description of major redshift surveys that have been done, and the local
cosmography out to 8,000 km/s that they have mapped. We then discuss in some
detail the various quantitative cosmological tests that can be carried out with
redshift data. The second half of this review concentrates on peculiar velocity
studies, beginning with a thorough review of existing techniques. After
discussing the various biases which plague peculiar velocity work, we survey
quantitative analyses done with peculiar velocity surveys alone, and finally
with the combination of data from both redshift and peculiar velocity surveys.
The data presented rule out the standard Cold Dark Matter model, although
several variants of Cold Dark Matter with more power on large scales fare
better. All the data are consistent with the hypothesis that the initial
density field had a Gaussian distribution, although one cannot rule out broad
classes of non-Gaussian models. Comparison of the peculiar velocity and density
fields constrains the Cosmological Density Parameter. The results here are
consistent with a flat universe with mild biasing of the galaxies relative to
dark matter, although open universe models are by no means ruled out.Comment: In press, Physics Reports. 153 pages. gzip'ed postscript of text plus
20 embedded figures. Also available via anonymous ftp at
ftp://eku.ias.edu/pub/strauss/review/physrep.p
Cigarette smoke exposure inhibits extracellular MMP-2 (gelatinase A) activity in human lung fibroblasts
BACKGROUND: Exposure to cigarette smoke is considered a major risk factor for the development of lung diseases, since its causative role has been assessed in the induction and maintenance of an inflamed state in the airways. Lung fibroblasts can contribute to these processes, due to their ability to produce proinflammatory chemotactic molecules and extracellular matrix remodelling proteinases. Among proteolytic enzymes, gelatinases A and B have been studied for their role in tissue breakdown and mobilisation of matrix-derived signalling molecules. Multiple reports linked gelatinase deregulation and overexpression to the development of inflammatory chronic lung diseases such as COPD. METHODS: In this study we aimed to determine variations in the gelatinolytic pattern of human lung fibroblasts (HFL-1 cell line) exposed to cigarette smoke extract (CSE). Gelatinolytic activity levels were determined by using gelatin zymography for the in-gel detection of the enzymes (proenzyme and activated forms), and the subsequent semi-quantitative densitometric evaluation of lytic bands. Expression of gelatinases was evaluated also by RT-PCR, zymography of the cell lysates and by western blotting. RESULTS: CSE exposure at the doses used (1â10%) did not exert any significant cytotoxic effects on fibroblasts. Zymographic analysis showed that CSE exposure resulted in a linear decrease of the activity of gelatinase A. Control experiments allowed excluding a direct inhibitory effect of CSE on gelatinases. Zymography of cell lysates confirmed the expression of MMP-2 in all conditions. Semi-quantitative evaluation of mRNA expression allowed assessing a reduced transcription of the enzyme, as well as an increase in the expression of TIMP-2. Statistical analyses showed that the decrease of MMP-2 activity in conditioned media reached the statistical significance (p = 0.0031 for 24 h and p = 0.0012 for 48 h), while correlation analysis showed that this result was independent from CSE cytotoxicity (p = 0.7833 for both exposures). CONCLUSION: Present work describes for the first time that, apart well characterized proinflammatory responses, human lung fibroblasts may react to CSE with a significant reduction of extracellular MMP-2 lytic activity. Therefore, fibroblasts may actively participate to the alteration of the proteolysis/antiproteolysis balance, which reflects the defective repair of the extracellular matrix. Such event should provide a further contribution to the maintenance of the inflamed state in the lungs
Protoplanetary Disks of T Tauri Binary Systems in the Orion Nebula Cluster
We present a study of protoplanetary disks in spatially resolved low-mass
binary stars in the Orion Nebula Cluster (ONC) to assess the impact of binarity
on the properties of circumstellar disks. This is currently the largest such
study in a clustered high-stellar-density star-forming environment. We
particularly aim to determine the presence of magnetospheric accretion and dust
disks for each binary component, and measure the overall disk frequency. We
carried out spatially resolved adaptive-optics-assisted observations to acquire
near-IR photometry and spectroscopy of 26 binaries in the ONC, and determine
stellar parameters such as effective temperatures, spectral types,
luminosities, and masses, as well as accretion properties and near-infrared
excesses for the individual binary components. A fraction of 40(+10/-9)% of the
binary components in the sample can be inferred to be T Tauri stars possessing
an accretion disk, marginally fewer than the disk fraction of single stars. We
find that disks in wide binaries of >200AU separation are consistent with
random pairing, while the evolution of circumprimary and circumsecondary disks
is observed to be synchronized in close binaries (separations <200AU).
Circumbinary disks appear to be unsuitable to explain this difference.
Furthermore, we identify several mixed pairs of accreting and non-accreting
components, suggesting that these systems are common and that there is no
preference for either the more or less massive component to evolve faster. The
derived accretion luminosities and mass accretion rates of the ONC binary
components are of similar magnitude as those for both ONC single stars and
binaries in the Taurus star-forming region. The paper concludes with a
discussion of the (presumably weak) connection between the presence of inner
accretion disks in young binary systems and the existence of planets in stellar
multiples.(abridged)Comment: 22 pages, 16 figures. Accepted for publication in Astronomy and
Astrophysic
Cascading Crises: Society in the Age of COVID-19
The tsunami of change triggered by the COVID-19 pandemic has transformed society in a series of cascading crises. Unlike disasters that are more temporarily and spatially bounded, the pandemic has continued to expand across time and space for over a year, leaving an unusually broad range of second-order and third-order harms in its wake. Globally, the unusual conditions of the pandemicâunlike other crisesâhave impacted almost every facet of our lives. The pandemic has deepened existing inequalities and created new vulnerabilities related to social isolation, incarceration, involuntary exclusion from the labor market, diminished economic opportunity, life-and-death risk in the workplace, and a host of emergent digital, emotional, and economic divides. In tandem, many less advantaged individuals and groups have suffered disproportionate hardship related to the pandemic in the form of fear and anxiety, exposure to misinformation, and the effects of the politicization of the crisis. Many of these phenomena will have a long tail that we are only beginning to understand. Nonetheless, the research also offers evidence of resilience on several fronts including nimble organizational response, emergent communication practices, spontaneous solidarity, and the power of hope. While we do not know what the post COVID-19 world will look like, the scholarship here tells us that the virus has not exhausted societyâs adaptive potential
The infrared properties of active extragalactic nuclei
In this paper we review the observed infrared properties of the general classes of active extragalactic nuclei with the purpose of relating the observations to the mechanisms responsible for the emission processes. We will first give a summary of those observations which define the energy distributions and emission line ratios of broad groups of objects. We will intersperse measurements of specific features throughout the discussion that illustrate definite emission mechanisms
Compton Thick AGN: the dark side of the X-ray background
The spectrum of the hard X-ray background records the history of accretion
processes integrated over the cosmic time. Several pieces of observational and
theoretical evidence indicate that a significant fraction of the energy density
is obscured by large columns of gas and dust. The absorbing matter is often
very thick, with column densities exceeding N_H > 1.5 10^24 cm-2, the value
corresponding to unity optical depth for Compton scattering. These sources are
called ``Compton thick'' and appear to be very numerous, at least in the nearby
universe. Although Compton thick Active Galactic Nuclei (AGN) are thought to
provide an important contribution to the overall cosmic energy budget, their
space density and cosmological evolution are poorly known. The properties of
Compton thick AGN are reviewed here, with particular emphasis on their
contributions to the extragalactic background light in the hard X-ray and
infrared bands.Comment: 28 pages, 10 figures. Review for "Supermassive Black Holes in the
Distant Universe", Ed. A. J. Barger, Kluwer Academi