1,399 research outputs found
FERMI transient J1544-0649: a flaring radio-weak BL Lac
On May 15th, 2017, the \emph{FERMI}/LAT gamma-ray telescope observed a
transient source not present in any previous high-energy catalogue: J1544-0649.
It was visible for two consecutive weeks, with a flux peak on May 21st.
Subsequently observed by a \emph{Swift}/XRT follow-up starting on May 26, the
X-ray counterpart position was coincident with the optical transient
ASASSN-17gs = AT2017egv, detected on May 25, with a potential host galaxy at
=0.171. We conducted a 4-months follow-up in radio (Effelsberg-100m) and
optical (San Pedro M\'artir, 2.1m) bands, in order to build the overall
Spectral Energy Distribution (SED) of this object. The radio data from 5 to 15
GHz confirmed the flat spectrum of the source, favoring a line of sight close
to jet axis, not showing significant variability in the explored post-burst
time-window. The Rx ratio, common indicator of radio loudness, gives a value at
the border between the radio-loud and radio-quiet AGN populations. The
Ca H\&K break value (0.290.05) is compatible with the range
expected for the long-sought intermediate population between BL Lacs and FRI
radio galaxies. An overall SED fitting from Radio to -ray band shows
properties typical of a low-power BL Lac. As a whole, these results suggest
that this transient could well be a new example of the recently discovered
class of radio-weak BL Lac, showing for the first time a flare in the
gamma/X-ray bands.Comment: Accepted for publication in ApJ Letter
A multi-agent system with distributed bayesian reasoning for network fault diagnosis
In this paper, an innovative approach to perform distributed Bayesian inference using a multi-agent architecture is presented. The final goal is dealing with uncertainty in network diagnosis, but the solution can be of applied in other fields. The validation testbed has been a P2P streaming video service. An assessment of the work is presented, in order to show its advantages when it is compared with traditional manual processes and other previous systems
Use and Impact of Social Networks on Physical Medicine and Rehabilitation Scientific Journals
Q4Objectives: Our research seeks to examine the correlation between the presence of physical medicine and rehabilitation journals in social networks and the SJR impact factor.
Methods: We carried out a correlation study. For the research, we took into account all physical medicine and rehabilitation journals included in the SCImago Journal Rank. The number of followers on Twitter, Facebook, YouTube, and the number of tweets were extracted from verified accounts. Journal differences according to the presence in social networks were evaluated using non-parametric tests, and the Spearman correlation coefficient was calculated between the metrics of dissemination in social networks and the SCImago Journal Rank.
Results: Out of 122 physical medicine and rehabilitation journals, 25.4% had the presence in one social network. The H Index medians (32 vs 17, P=0.014) and of the SJR (0.67 vs 0.32, P= 0.001) were better in journals with the presence in social networks. A moderate correlation was found between the SJR and the number of followers on Twitter (r=0.5, P=0.066). The global correlation between the SJR and followers on Facebook was acceptable (r=0.4, P=0.1205).
Discussion: Our data show that scientific journals of physical medicine and rehabilitation with presence in social networks have superior quality metrics. Additionally, SJR and the indicators of dissemination in social networks are moderately correlated. Both metrics offer complementary information. Presence in social networks could improve the visibility of journals and their interaction with readers.Revista Internacional - Indexad
Aflatoxin M Determination in Infant Formulae Distributed in Monterrey, Mexico
The occurrence of aflatoxin M (AFM) in infant formulae commercialized in the metropolitan area of Monterrey (Nuevo LeĂłn, Mexico) was determined by using immunoaffinity column clean-up followed by HPLC determination with fluorimetric detection. For this, 55 infant formula powders were classified in two groups, starter (49 samples) and follow-on (6 samples) formulae. Eleven of the evaluated samples (20%) presented values above the permissible limit set by the European Union for infant formulae (25 ng/L), ranging from 40 to 450 ng/L. The estimated daily intake (EDI) for AFM was determined employing the average body weight (bw) of the groups of age in the ranges of 0-6 and 6-12 months, and 1-2 years. The results evidenced high intake values, ranging from 1.56 to 14 ng/kg bw/day, depending on the group. Finally, with the EDI value, the carcinogenic risk index was determined, presenting a high risk for all the evaluated groups. Based on these results, it is a necessary extra effort by the regulatory agencies to reduce the AFM presence in infant formulae consumed in Mexico
Anålisis multivariante de los horizontes orgånico-minerales de los suelos del Parque Natural de Sierra Mågina (Jaén)
Soils are described normally using a great number of properties (variables). This generates a great quantity of data not easily understandable in a direct way. Consequently, multivariate analysis is necessary to support and confirm impressions and interpretations of investigations in field and laboratory. In the present work we quantify, through multivariate analysis, the relative influence of the different factors of soil formation that act on the soil system. We have studied 203 organo-mineral horizons, sampled to a depth between 0 and 25 cm of soils in the Sierra Mågina natural park (Jaén, Spain). The studied soils are from calcareous rocks. Five factors were found to be significant and showed that the organic carbon accumulation, decarbonatation and the argillization/rubefacction, as internal variables, and the hill slope, as external variable, they are those which explain a greater percentage of the natural variability of the soil system
The central star of the planetary nebula PB 8: a Wolf-Rayet-type wind of an unusual WN/WC chemical composition
A considerable fraction of the central stars of planetary nebulae (CSPNe) are
hydrogen-deficient. As a rule, these CSPNe exhibit a chemical composition of
helium, carbon, and oxygen with the majority showing Wolf-Rayet-like emission
line spectra. These stars are classified as CSPNe of a spectral type [WC]. We
perform a spectral analysis of CSPN PB 8 with the Potsdam Wolf-Rayet (PoWR)
models for expanding atmospheres. The source PB 8 displays wind-broadened
emission lines from strong mass loss. Most strikingly, we find that its surface
composition is hydrogen-deficient, but not carbon-rich. With mass fractions of
55% helium, 40% hydrogen, 1.3% carbon, 2% nitrogen, and 1.3% oxygen, it differs
greatly from the 30-50% of carbon which are typically seen in [WC]-type central
stars. The atmospheric mixture in PB 8 has an analogy in the WN/WC transition
type among the massive Wolf-Rayet stars. Therefore we suggest to introduce a
new spectral type [WN/WC] for CSPNe, with PB 8 as its first member. The central
star of PB 8 has a relatively low temperature of T=52kK, as expected for
central stars in their early evolutionary stages. Its surrounding nebula is
less than 3000 years old, i.e. relatively young. Existing calculations for the
post-AGB evolution can produce hydrogen-deficient stars of the [WC] type, but
do not predict the composition found in PB 8. We discuss various scenarios that
might explain the origin of this unique object.Comment: 10 pages, 10 figure
THU0626 Social networks as a source of information for patients with rheumatic diseases
Background: Internet is an informative source for patients with different diseases. False information in social networks about health issues is a growing problem. Rheumatology is no stranger to this problem and there is a lot of false information regarding rheumatic diseases.
Objectives: To show objective data on misinformation published in social networks available to spanish-speaking rheumatic patients
Methods: We create accounts on Facebook (FB) and Google unique for this work. Multimedia was included in Spanish, with a convenience sampling according to the deployment of the platform (FB) or in descending order for reproductions on YouTube (YT). Two independent reviewers extracted information on online time, number of reproductions and characteristics of the most popular videos. Videos consulted on 10-11-18.
Results: With the search term ârheumatoid arthritisâ (RA), the most reproduced video is titled âcelery green juice for arthritisâ (6.4 million reproductions). Of the first 50 videos with more reproductions, 39 are of natural or home remedies such as vinegar, âmoringaâ, etc., and 35 videos indicate in their content, that they can cure RA. With the term âlupusâ, the most reproduced video is titled âGodâs tea, cure chronic tiredness, thyroid, arthritis, lupus and vertigoâ (1.4 million reproductions). Of the first 50 videos with more reproductions, 31 correspond to natural or home remedies such as celery, thyme, diets among others and 29 videos indicate that they can cure lupus. With the term âfibromyalgiaâ, the most reproduced video is entitled âI am 61 years old and this cured my arthritis, vertigo, fibromyalgia, lupus, chronic fatigue and the thyroidâ (1.1 million reproductions). Of the 50 first videos with more reproductions, 40 are of natural or home remedies such as thyme, tea, among others and 33 videos indicate that they can cure the disease. With the data of the videos uploaded online in October 2018, 50 videos were chosen in YT and FB. There was no correlation between online time and the number of views on any platform. In FB, 56% of the videos contained false information, with no difference in online time in both groups (16 [12-22] vs 18 [13-25], p = 0.3).). In YT, only 38% was considered false information, without differences between groups in online time (19 [11-26] vs 22 [12-24])
Effect of organic and conventional systems used to grow pecan trees on diversity of soil microbiota
Agronomic management modifies the soil bacterial communities and may alter the carbon fractions. Here, we identify differences in several chemical and biological soil variables, as well as bacterial composition between organic (Org) and conventional (Conv) agronomic management in pecan (Carya illinoinensis) orchards located in Coahuila, Mexico. The analyzed variables were pH, N, P, K, soil organic matter, organic matter quality, soil organic carbon, C/N ratio, carbon fractions, microbial biomass carbon, easily extractable Glomalin, colony-forming units, CO2 emissions, and the enzyme activity. The DNA of soil bacteria was extracted, amplified (V3-V4 16S rRNA), and sequenced using Illumina. To compare variables between agronomic managements, t tests were used. Sequences were analyzed in QIIME (Quantitative Insights Into Microbial Ecology). A canonical correspondence analysis (CCA) was used to observe associations between the ten most abundant phyla and soil variables in both types of agronomic managements. In Org management, variables related to the capture of recalcitrant carbon compounds were significant, and there was a greater diversity of bacterial communities capable of promoting organic carbon sequestration. In Conv management, variables related to the increase in carbon mineralization, as well as the enzymatic activity related to the metabolism of labile compounds, were significant. The CCA suggested a separation between phyla associated with some variables. Agronomic management impacted soil chemical and biological parameters related to carbon dynamics, including bacterial communities associated with carbon sequestration. Further research is still necessary to understand the plasticity of some bacterial communities, as well as the soilâplant dynamics.Fil: Cabrera RodrĂguez, Alejandra. Universidad AutĂłnoma de Chapingo; MĂ©xicoFil: Nava Reyna, Erika. Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias; MĂ©xicoFil: Trejo Calzada, Ricardo. Universidad AutĂłnoma de Chapingo; MĂ©xicoFil: GarcĂa de la Peña, Cristina. Universidad JuĂĄrez del Estado de Durango; MĂ©xicoFil: Arreola Avila, JesĂșs G.. Universidad AutĂłnoma de Chapingo; MĂ©xicoFil: Collavino, MĂłnica Mariana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Nordeste. Instituto de BotĂĄnica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de BotĂĄnica del Nordeste; ArgentinaFil: Vaca Paniagua, Felipe. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: DĂaz VelĂĄsquez, Clara. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Constante GarcĂa, Vicenta. Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias; MĂ©xic
The Iron abundance in Galactic Planetary Nebulae
We constrain the iron abundance in a sample of 33 low-ionization Galactic
planetary nebulae (PNe) using [Fe III] lines and correcting for the
contribution of higher ionization states with ionization correction factors
(ICFs) that take into account uncertainties in the atomic data. We find very
low iron abundances in all the objects, suggesting that more than 90% of their
iron atoms are condensed onto dust grains. This number is based on the solar
iron abundance and implies a lower limit on the dust-to-gas mass ratio, due
solely to iron, of M_dust/M_gas>1.3x10^{-3} for our sample. The depletion
factors of different PNe cover about two orders of magnitude, probably
reflecting differences in the formation, growth, or destruction of their dust
grains. However, we do not find any systematic difference between the gaseous
iron abundances calculated for C-rich and O-rich PNe, suggesting similar iron
depletion efficiencies in both environments. The iron abundances of our sample
PNe are similar to those derived following the same procedure for a group of 10
Galactic H II regions. These high depletion factors argue for high depletion
efficiencies of refractory elements onto dust grains both in molecular clouds
and AGB stars, and low dust destruction efficiencies both in interstellar and
circumstellar ionized gas.Comment: Accepted for publication in ApJ. 15 pages, 4 Postscript figures,
corrected typos, Tables 2 and 3 correcte
- âŠ