3,883 research outputs found
Alkali-activated materials â cementing a sustainable future
This paper presents an overview examining the microstructural and macrostructural properties of alkali-activated binders based on granulated blast furnace slags, metakaolin and their blends, developed by the Composite Materials Group of Universidad del Valle over the past decade. Durability results of activated binders when exposed to aggressive agents such as chlorides, and carbon dioxide are reported. The results of this research have elucidated the great feasibility of adopting alkali-activation technology in Colombia for producing high strength concretes based on industrial by-products, with a wide range of properties that can be suitable for different civil infrastructure applications, and contribute to the valorization of low-cost industrial by products through production of more environmentally friendly building materials. Our research highlights the fact that a deep understanding of the chemistry of these systems allows the manipulation of the microstructure and therefore the performance of the final products, toward the production of sustainable and versatile materials
The spanish body image state scale: factor structure, reliability and validity in a colombian population
Objective: Body image is a construct highly dependent on culture and ethnicity.
Furthermore, recent studies reveal that body image is not only a trait, but also a
momentary state subject to change in diverse situational contexts. However, cultural
influences on momentary body image have not been sufficiently investigated. To assess
the influence of Latin American culture on momentary body image and to enable its
comparison to Western countries, the Spanish translation of an existing state body
image scale such as the Body Image States Scale (BISS) is needed. In addition, the
factor structure, reliability and general validity of the Spanish BISS (S-BISS) should be
evaluated prior to its application in diverse situational contexts.
Method: We conducted a cross-sectional study evaluating 1137 individuals between
the ages of 18 and 28 years from Barranquilla, Colombia, South America. The
original BISS, which assesses body satisfaction, was translated from English
to Spanish. Factorial structure, scale score reliability and convergent/divergent
validity were assessed.
Results: Exploratory and confirmatory factor analyses revealed that a one-factor
model with correlated items best described the factorial structure present in the
BISS questionnaire. The coefficient of scale score reliability was a = 0.92 (McDonalds
& = 0.93), with similar results for men and women. Significant differences between
males and females were found with lesser body satisfaction in females (W = 163260,
p = 0.016). Lower S-BISS scores indicating less body satisfaction were associated
with higher BMI (r = â0.287, p < 0.001) and obtained in participants who were
currently on a diet (t1135 = â3.98, p < 0.001). The S-BISS was negatively correlated
with a trait body image measurement assessing body dissatisfaction (Body Shape
Questionnaire, r = â0.577, p < 0.001) and a psychopathology questionnaire (Brief
Symptom Inventory 53, r = â0.331, p < 0.001). Conclusion: The S-BISS is a valid and reliable instrument to assess body image in
the Colombian population, and exhibits similar psychometric properties to those of the
original version. Future studies should examine whether the S-BISS captures change in
state body image when applied in diverse situational contexts
"Validity of a scale of Latin American perception of fear and concern transmitted by the media during the pandemic (MED-LAT-COVID-19)"
"Introduction: The pandemic has caused fear, especially due to the daily disseminated news; however, there is not
an instrument to measure this fear in multiple realities.
Objective: To validate a scale for Latin American perception of fear and concern transmitted by the media during
the pandemic.
Methodology: This is an instrumental study. The survey was based on an instrument which was pre-validated in
Peru and submitted to 15 experts in almost 10 countries. Subsequently, thousands of people were surveyed in 13
Latin American countries, whose answers were used for descriptive statistics for validation.
Results: Confirmatory Factor Analysis (CFA) generated two re-specifications, where four items were eliminated
from the original scale. With these changes, the global goodness of fit (absolute and incremental) were satisfactory
(CFI Œ 0.978; TLI Œ 0.964; GFI Œ 0.976; AGFI Œ 0.949; RMSEA Œ 0.075 and RMR Œ 0.029). The first factor
measures the media exaggeration (three questions); the second, the fear transmitted by the media (three questions); and the third, the fear transmitted by others different from the media (two questions). The Cronbachâs
alpha coefficient was higher than 0.70 for the scale and its factors.
Conclusion: The MED-LAT-COVID-19 scale reported a good adjustment. It has eight items in three factors, which
could be measured in an isolated way, or along with other tests that assess mental health in the current pandemic
context.
Father's occupational exposure to carcinogenic agents and childhood acute leukemia: a new method to assess exposure (a case-control study)
<p>Abstract</p> <p>Background</p> <p>Medical research has not been able to establish whether a father's occupational exposures are associated with the development of acute leukemia (AL) in their offspring. The studies conducted have weaknesses that have generated a misclassification of such exposure. Occupations and exposures to substances associated with childhood cancer are not very frequently encountered in the general population; thus, the reported risks are both inconsistent and inaccurate. In this study, to assess exposure we used a new method, an exposure index, which took into consideration the industrial branch, specific position, use of protective equipment, substances at work, degree of contact with such substances, and time of exposure. This index allowed us to obtain a grade, which permitted the identification of individuals according to their level of exposure to known or potentially carcinogenic agents that are not necessarily specifically identified as risk factors for leukemia. The aim of this study was to determine the association between a father's occupational exposure to carcinogenic agents and the presence of AL in their offspring.</p> <p>Methods</p> <p>From 1999 to 2000, a case-control study was performed with 193 children who reside in Mexico City and had been diagnosed with AL. The initial sample-size calculation was 150 children per group, assessed with an expected odds ratio (OR) of three and a minimum exposure frequency of 15.8%. These children were matched by age, sex, and institution with 193 pediatric surgical patients at secondary-care hospitals. A questionnaire was used to determine each child's background and the characteristics of the father's occupation(s). In order to determine the level of exposure to carcinogenic agents, a previously validated exposure index (occupational exposure index, OEI) was used. The consistency and validity of the index were assessed by a questionnaire comparison, the sensory recognition of the work area, and an expert's opinion.</p> <p>Results</p> <p>The adjusted ORs and 95% confidence intervals (CI) were 1.69 (0.98, 2.92) during the preconception period; 1.98 (1.13, 3.45) during the index pregnancy; 2.11 (1.17, 3.78) during breastfeeding period; 2.17 (1.28, 3.66) after birth; and 2.06 (1.24, 3.42) for global exposure.</p> <p>Conclusion</p> <p>This is the first study in which an OEI was used to assess a father's occupational exposure to carcinogenic agents as a risk factor for the development of childhood AL in his offspring. From our results, we conclude that children whose fathers have been exposed to a high level of carcinogenic agents seem to have a greater risk of developing acute leukemia. However, confounding factors cannot be disregarded due to an incomplete control for confounding.</p
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Measurement of the relative rate of prompt Ïc0, Ïc1 and Ïc2 production at âs=7TeV
Prompt production of charmonium Ïc0, Ïc1 and Ïc2 mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of âs=7TeV. The Ïc mesons are identified through their decay to J/ÏÎł, with J/ÏâÎŒ+muâ using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of 1.0fbâ1 collected by the LHCb detector, is used to measure the relative prompt production rate of Ïc1 and Ïc2 in the rapidity range 2.0<y<4.5 as a function of the J/Ï transverse momentum from 3 to 20 GeV/c. First evidence for Ïc0 meson production at a hadron collider is also presented
Measurements of the branching fractions of B+âppK+ decays
The branching fractions of the decay B+ â ppÌK+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment. The total branching fraction, its charmless component MppÌ < 2.85 GeV/c2 and the branching fractions via the resonant ccÌ states η c(1S) and Ï(2S) relative to the decay via a J/Ï intermediate state are [Equation not available: see fulltext.] Upper limits on the B + branching fractions into the η c(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained
Search for the decay Bs0âD*âϱ
A search for the decay Bs0âD*âϱ is presented using a data sample corresponding to an integrated luminosity of 1.0ââfb-1 of pp collisions collected by LHCb. This decay is expected to be mediated by a W-exchange diagram, with little contribution from rescattering processes, and therefore a measurement of the branching fraction will help us to understand the mechanism behind related decays such as Bs0âÏ+Ï- and Bs0âDD- . Systematic uncertainties are minimized by using B0âD*âϱ as a normalization channel. We find no evidence for a signal, and set an upper limit on the branching fraction of B(Bs0âD*âϱ)<6.1(7.8)Ă10-6 at 90% (95%) confidence level
Observation of associated production of a boson with a meson in the~forward region
A search for associated production of a boson with an open charm meson is
presented using a data sample, corresponding to an integrated luminosity of
of proton--proton collisions at a centre-of-mass energy
of 7\,TeV, collected by the LHCb experiment. %% Seven candidate events for
associated production of a boson with a meson and four candidate
events for a boson with a meson are observed with a combined
significance of 5.1standard deviations. The production cross-sections in the
forward region are measured to be where the first uncertainty is statistical and the
second systematic.Comment: 18 pages, 2 figure
- âŠ