2,443 research outputs found
J. H. Newman, hoy
Documentos del Instituto de Antropología y Ética, número 1
A procedure for indirect and automatic measurement of prior austenite grain size in bainite/martensite microstructures
An alternative procedure for indirect and automatic measurement of the prior austenite grain
size (PAGS) in bainite/martensite is proposed in this work. It consists in the determination of an
effective grain size (EGS) by means of statistical post-processing of electron backscatter diffraction
(EBSD) data. The algorithm developed for that purpose, which is available on-line, has been applied
to simulated EBSD maps as well as to both a nanocrystalline bainitic steel and a commercial hot-rolled
air-cooled steel with a granular bainitic microstructure. The new proposed method has been proven to
be robust and results are in good agreement with conventional PAGS measurements. The added value
of the procedure comes from its simplicity, as no parent reconstruction is involved during the process,
and its suitability for low-magnification EBSD maps, thus allowing a large step-size and coverage of a
substantially broader area of the sample than the previous methods reported.Spanish Ministry of Economy and
Competitiveness for funding this research under the contract IPT-2012-0320-420000. L.M.-R. also
acknowledges the Spanish Ministry of Economy and Competitiveness for financial support in the form
of a PhD research grant (FPI-Ref. BES-2011-044186).Peer reviewe
Dynamic simulations in SixTrack
The DYNK module allows element settings in SixTrack to be changed on a
turn-by-turn basis. This document contains a technical description of the DYNK
module in SixTrack. It is mainly intended for a developer or advanced user who
wants to modify the DYNK module, for example by adding more functions that can
be used to calculate new element settings, or to add support for new elements
that can be used with DYNK.Comment: Submission to CERN yellow report / conference proceeding, the 2015
collimation tracking code worksho
Deuteration around the ultracompact HII region Mon R2
The massive star-forming region Mon R2 hosts the closest ultra-compact HII
region that can be spatially resolved with current single-dish telescopes. We
used the IRAM-30m telescope to carry out an unbiased spectral survey toward two
important positions (namely IF and MP2), in order to studying the chemistry of
deuterated molecules toward Mon R2. We found a rich chemistry of deuterated
species at both positions, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO,
NH2D, and N2D+ and their corresponding hydrogenated species and isotopologs.
Our high spectral resolution observations allowed us to resolve three velocity
components: the component at 10 km/s is detected at both positions and seems
associated with the layer most exposed to the UV radiation from IRS 1; the
component at 12 km/s is found toward the IF position and seems related to the
molecular gas; finally, a component at 8.5 km/s is only detected toward the MP2
position, most likely related to a low-UV irradiated PDR. We derived the column
density of all the species, and determined the deuterium fractions (Dfrac). The
values of Dfrac are around 0.01 for all the observed species, except for HCO+
and N2H+ which have values 10 times lower. The values found in Mon R2 are well
explained with pseudo-time-dependent gas-phase model in which deuteration
occurs mainly via ion-molecule reactions with H2D+, CH2D+ and C2HD+. Finally,
the [H13CN]/[HN13C] ratio is very high (~11) for the 10 km/s component, which
also agree with our model predictions for an age of ~0.01-0.1 Myr. The
deuterium chemistry is a good tool for studying star-forming regions. The
low-mass star-forming regions seem well characterized with Dfrac(N2H+) or
Dfrac(HCO+), but it is required a complete chemical modeling to date massive
star-forming regions, because the higher gas temperature together with the
rapid evolution of massive protostars.Comment: 14 pages of manuscript, 17 pages of apendix, 7 figures in the main
text, accepted for publication in A&
Validation of a Spanish version of the Foreign Language Classroom Anxiety Scale in Peruvian secondary education students
BackgroundAnxiety in learning foreign languages is a global phenomenon that impacts students’ academic performance, with English being a critical language in secondary education. The Foreign Language Classroom Anxiety Scale (FLCAS) has been widely used to assess this anxiety. However, the need to validate and adapt the scale for specific cultural contexts remains a priority in educational research.ObjectiveTo assess the validity and reliability of a Spanish version of the FLCAS among a sample of Peruvian secondary education students, in order to better understand the structure of language learning anxiety in this context.MethodsA total of 818 students from four public educational institutions in southern Peru participated. An instrumental design was used, which included descriptive analysis, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and assessments of convergent, divergent validity, and measurement invariance by gender.ResultsThe EFA recommended a four-factor model that explained 32% of the total variance. Subsequent CFA adjusted this model to 24 items with optimal fit indices (CFI = 0.969; RMSEA = 0.045). The reliability of the factors was acceptable (α > 0.70 for all factors). Convergent and divergent validity was confirmed through significant correlations with related constructs (Fear of Negative Evaluation and Enjoyment of Foreign Language). Gender invariance analysis indicated that the scale is equally applicable to men and women.ConclusionThe Spanish version of the FLCAS is a valid and reliable tool for assessing foreign language classroom anxiety among Peruvian secondary education students. This study contributes to the field of language teaching by providing evidence of the cultural applicability of the FLCAS in the Peruvian context, thus facilitating more effective pedagogical interventions to address language learning anxiety
Spatial distribution of small hydrocarbons in the neighborhood of the Ultra Compact HII region Monoceros R2
We study the chemistry of small hydrocarbons in the photon-dominated regions
(PDRs) associated with the ultra-compact HII region Mon R2. Our goal is to
determine the variations of the abundance of small hydrocarbons in a high-UV
irradiated PDR and investigate their chemistry. We present an observational
study of CH, CCH and c-CH in Mon R2 combining data obtained with the
IRAM 30m telescope and Herschel. We determine the column densities of these
species, and compare their spatial distributions with that of polycyclic
aromatic hydrocarbon (PAH). We compare the observational results with different
chemical models to explore the relative importance of gas-phase, grain-surface
and time-dependent chemistry in these environments. The emission of the small
hydrocarbons show different patterns. The CCH emission is extended while CH and
c-CH are concentrated towards the more illuminated layers of the PDR.
The ratio of the column densities of c-CH and CCH shows spatial
variations up to a factor of a few, increasing from
_3_2 in the envelope to a maximum of
towards the 8m emission peak. Comparing these results
with other galactic PDRs, we find that the abundance of CCH is quite constant
over a wide range of G, whereas the abundance of c-CH is higher in
low-UV PDRs. In Mon R2, the gas-phase steady-state chemistry can account
relatively well for the abundances of CH and CCH in the most exposed layers of
the PDR, but falls short by a factor of 10 to reproduce c-CH.
In the molecular envelope, time-dependent effects and grain surface chemistry
play a dominant role in determining the hydrocarbons abundances. Our study
shows that CCH and c-CH present a complex chemistry in which UV
photons, grain-surface chemistry and time dependent effects contribute to
determine their abundances.Comment: 18 pages, 11 figures, 7 tables. Proposed for acceptance in A&A.
Abstract abridge
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