11,189 research outputs found
VLT and GTC observations of SDSS J0123+00: a type 2 quasar triggered in a galaxy encounter?
We present long-slit spectroscopy, continuum and [OIII]5007 imaging data
obtained with the Very Large Telescope and the Gran Telescopio Canarias of the
type 2 quasar SDSS J0123+00 at z=0.399. The quasar lies in a complex, gas-rich
environment. It appears to be physically connected by a tidal bridge to another
galaxy at a projected distance of ~100 kpc, which suggests this is an
interacting system. Ionized gas is detected to a distance of at least ~133 kpc
from the nucleus. The nebula has a total extension of ~180 kpc. This is one of
the largest ionized nebulae ever detected associated with an active galaxy.
Based on the environmental properties, we propose that the origin of the nebula
is tidal debris from a galactic encounter, which could as well be the
triggering mechanism of the nuclear activity. SDSS J0123+00 demonstrates that
giant, luminous ionized nebulae can exist associated with type 2 quasars of low
radio luminosities, contrary to expectations based on type 1 quasar studies.Comment: 6 pages, 5 figures. Accepted for publication in MNRAS Letter
High-Intensity Radiated Field Fault-Injection Experiment for a Fault-Tolerant Distributed Communication System
Safety-critical distributed flight control systems require robustness in the presence of faults. In general, these systems consist of a number of input/output (I/O) and computation nodes interacting through a fault-tolerant data communication system. The communication system transfers sensor data and control commands and can handle most faults under typical operating conditions. However, the performance of the closed-loop system can be adversely affected as a result of operating in harsh environments. In particular, High-Intensity Radiated Field (HIRF) environments have the potential to cause random fault manifestations in individual avionic components and to generate simultaneous system-wide communication faults that overwhelm existing fault management mechanisms. This paper presents the design of an experiment conducted at the NASA Langley Research Center's HIRF Laboratory to statistically characterize the faults that a HIRF environment can trigger on a single node of a distributed flight control system
The Effect of Conservation Agriculture and Environmental Factors on CO2 Emissions in a Rainfed Crop Rotation
There are many factors involved in the release of CO2 emissions from the soil, such as the type of soil management, the soil organic matter, the soil temperature and moisture conditions, crop phenological stage, weather conditions, residue management, among others. This study aimed to analyse the influence of these factors and their interactions to determine the emissions by evaluating the environmental cost expressed as the kg of CO2 emitted per kg of production in each of the crops and seasons studied. For this purpose, a field trial was conducted on a farm in Seville (Spain). The study compared Conservation Agriculture, including its three principles (no-tillage, permanent soil cover, and crop rotations), with conventional tillage. Carbon dioxide emissions measured across the four seasons of the experiment showed an increase strongly influenced by rainfall during the vegetative period, in both soil management systems. The results of this study confirm that extreme events of precipitation away from the normal means, result in episodes of high CO2 emissions into the atmosphere. This is very important because one of the consequences for future scenarios of climate change is precisely the increase of extreme episodes of precipitation and periods extremely dry, depending on the area considered. The total of emission values of the different plots of the study show how the soils under the conventional system (tillage) have been emitting 67% more than soils under the conventional agriculture system during the 2010/11 campaign and 25% for the last campaign where the most appreciable differences are observed
Evidence for internal field in graphite: A conduction electron spin resonance study
We report conduction electron spin resonance measurements performed on highly
oriented pyrolitic graphite samples between 10 K and 300 K using S (f = 4 GHz),
X (f = 9.4 GHz), and Q (f = 34.4 GHz) microwave bands for the external
dc-magnetic field applied parallel (H || c) and perpendicular (H perp c) to the
sample hexagonal c-axis. The results obtained in the H || c geometry are
interpreted in terms of the presence of an effective internal
ferromagnetic-like field Heff-int(T,H) that increases as the temperature
decreases and the applied dc-magnetic field increases. We associate the
occurrence of the Heff-int(T,H) with the field-induced metal-insulator
transition in graphite and discuss its origin in the light of relevant
theoretical models.Comment: 10 pages (tex), 5 figures (ps
Editorial: Human rights and inequity in health access of Central American Migrants
Frontiers in Public Health is very pleased to publish this journal issue focusing on the health access of immigrants. Contributions to this journal issue include five articles that rely on different methodologies while focusing on diverse geographic world regions and target populations. This editorial summarizes these features while also highlighting the unique contributions of each article
Advantages and disadvantages on photosynthesis measurement techniques: A review
Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to molecular reaction centers for conversion into chemical energy with nearly 100% efficiency. Speed is the key as the transfer of the solar energy takes place almost instantaneously such that little energy is wasted as heat. How photosynthesis achieves this near instantaneous energy transfer is a longstanding mystery that may have finally been solved. Measurements of this process are useful in order to understand how it might be controlled and how the phytomonitoring of plant development to increase productivity can be carried out. Techniques in this sense have evolved and nowadays several have been used for this purpose. Thus, the aim of this paper is to present a review of the various methods and principles that have been used in measuring photosynthesis presenting the advantages and disadvantages of various existing measurement methodologies in order to recommend the most appropriate method according to the needs of specific investigations
Incidence, in-hospital case-fatality rates, and management practices in Puerto Ricans hospitalized with acute myocardial infarction
OBJECTIVE: There are extremely limited data on minority populations, especially Hispanics, describing the clinical epidemiology of acute coronary disease. The aim of this study is to examine the incidence rate of acute myocardial infarction (AMI), in-hospital case-fatality rate (CFR), and management practices among residents of greater San Juan (Puerto Rico) who were hospitalized with an initial AMI.
METHODS: Our trained study staff reviewed and independently validated the medical records of patients who had been hospitalized with possible AMI at any of the twelve hospitals located in greater San Juan during calendar year 2007.
RESULTS: The incidence rate (# per 100,000 population) of 1,415 patients hospitalized with AMI increased with advancing age and were significantly higher for older patients for men (198) than they were for women (134). The average age of the study population was 64 years, and women comprised 45% of the study sample. Evidence-based cardiac therapies, e.g., aspirin, beta blockers, ACE inhibitors/angiotensin receptor blockers, and statins, were used with 60% of the hospitalized patients, and women were less likely than men to have received these therapies (59% vs. 65%) or to have undergone interventional cardiac procedures (47% vs. 59%) (p \u3c 0.05). The in-hospital CFR increased with advancing age and were higher for women (8.6%) than they were for men (6.0%) (p \u3c 0.05).
CONCLUSION: Efforts are needed to reduce the magnitude of AMI, enhance the use of evidence-based cardiac therapies, reduce possible gender disparities, and improve the short-term prognoses of Puerto Rican patients hospitalized with an initial AMI
The Low Redshift survey at Calar Alto (LoRCA)
The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of
galaxies provides a standard ruler to measure the accelerated expansion of the
Universe. To extract all available information about dark energy, it is
necessary to measure a standard ruler in the local, z<0.2, universe where dark
energy dominates most the energy density of the Universe. Though the volume
available in the local universe is limited, it is just big enough to measure
accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body
simulations and approximate methods based on Lagrangian perturbation theory, we
construct a suite of a thousand light-cones to evaluate the precision at which
one can measure the BAO standard ruler in the local universe. We find that
using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a
K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a
precision of 4\% and 1.2\% using reconstruction). We also find that such a
survey would help to detect the dynamics of dark energy.Therefore, we propose a
3-year long observational project, named the Low Redshift survey at Calar Alto
(LoRCA), to observe spectroscopically about 200,000 galaxies in the northern
sky to contribute to the construction of aforementioned galaxy sample. The
suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website:
http://lorca-survey.ft.uam.es
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