1,322 research outputs found
Caracterización mecánica de hormigones autocompactantes reforzados con fibras de acero
El hormigón autocompactante reforzado con fibras de acero presenta simultáneamente las ventajas de los hormigones autocompactantes y de los reforzados con fibras. Se consigue un material de altas prestaciones con mayor tenacidad y ductilidad. En este trabajo se ha estudiado el comportamiento mecánico de un hormigón autocompactante reforzado con fibras de acero. Se han realizado ensayos a compresión, tracción y flexión a distintas edades; así como ensayos no destructivos (medida de la velocidad de ultrasonidos e índice esclerométrico). Los resultados muestran la variación de la respuesta del hormigón con el tiempo y la diferencia existente con hormigones tradicionales
Data Sources as a Driver for Market‑Oriented Tourism Organizations: a Bibliometric Perspective
This paper presents a conceptual framework that accurately represents the current
and future perspectives of data-driven companies in tourism by means of an analysis
of the data sources used in the data-driven tourism research literature, as well as the
research topics to which they are applied. For this purpose, a bibliometric analysis
of data-driven tourism research is carried out. The framework of the study is all
tourism-related publications whose research was based on data sources during the
period 1982–2020. The results show some of the basic bibliometric performance
indicators and the maps of science. The main themes of research interest are identified,
and the conceptual evolution is obtained based on these maps. Three major
thematic areas are identified: tourism research topics, information sources, and data
analysis techniques. Based on these three thematic areas, the conceptual model of
data architecture and processes of a data-driven organization in the tourism sector
are obtained. An additional qualitative analysis of the three thematic areas is
performedCRUE-CSIC agreement with Springer Natur
Sulbactam pivoxil powder attributes and compatibility study with excipients
Background: Sulbactam pivoxil is an irreversible β-lactamase inhibitor that can be used with β-lactam antibiotics to improve antibacterial therapy by the oral route. Relevant properties of this drug for pharmaceutical manufacturing are not available in the open literature. In this work, a solid-state characterization of sulbactam pivoxil at the molecular, particle, and bulk levels was performed. Results: Particles exhibited a mean diameter of about 350 μm, irregular shape crystals, and good flow properties. This work presents for the first time the crystal structure of this β-lactamase inhibitor obtained by X-ray diffraction analysis. Fourier-transform infrared results showed the characteristic bands of aliphatic hydrocarbons and ester groups. The differential scanning calorimetry curve exhibited a sharp endothermic peak at 109 °C corresponding to sulbactam pivoxil melting. The thermogravimetric curve revealed a mass loss at 184 °C associated with a decomposition process. This powder showed a moisture content of 0.34% and a water activity of 0.463. Potential interactions between sulbactam pivoxil and common pharmaceutical excipients were evaluated by thermal analysis. The endothermic peak and the enthalpies of melting were preserved in almost all the analyzed mixtures. Conclusion: The powder was constituted by micro-sized crystals of sulbactam pivoxil that had suitable physicochemical properties for processing in controlled humidity environments. Thermal analyses suggested that sulbactam pivoxil is compatible with most of the evaluated excipients. The information obtained in the present study is relevant for the development, manufacturing, and storage of formulations that include sulbactam pivoxil.Fil: Gallo, Loreana Carolina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: González Vidal, Noelia Luján. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Ferreira, Fabio F.. Universidad Federal do Abc; BrasilFil: Ramírez Rigo, María Veronica. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin
Evaluación de forjados de madera reforzados con recrecidos de hormigones ligeros estructurales
El refuerzo de forjados existentes de madera incrementando su capacidad resistente y/o su rigidez es una intervención estructural muy extendida. El refuerzo mediante recrecidos de hormigón unidos solidariamente a las viguetas de madera mediante conexiones metálicas presenta las siguientes ventajas: Incremento de la resistencia y rigidez del forjado inicial; el forjado se transforma en un diafragma rígido frente a las acciones horizontales y, cuando es posible ejecutar el refuerzo sin necesidad de apuntalar, puede mantenerse el uso de la zona inferior al forjado que se está reforzando. El principal inconveniente de la técnica radica en la carga añadida por el peso del hormigón. El empleo de hormigones ligeros estructurales (HLE) constituye una alternativa atractiva frente a los hormigones convencionales (HC), al aunar todas las ventajas de la técnica y disminuir considerablemente los inconvenientes debido al menor peso del hormigón ligero. Se han comparado los resultados obtenidos en la evaluación de forjados de madera de distintas luces, secciones y sobrecargas, reforzados con recrecidos de HC y de HLE. En concreto se han estudiado 3 luces (4.0, 4.5 y 5.0m) y 2 sobrecargas de uso (2kN/m2 y 3kN/m2). En todos los casos la sección de la madera se ha obtenido con criterios antiguos de dimensionamiento, utilizando las luces y acciones de los forjados a evaluar
Method effects associated with negatively and positively worded items on the 12-item General Health Questionnaire (GHQ-12) : results from a cross-sectional survey with a representative sample of Catalonian workers
This study focused on the examination of the latent structure underlying the responses to the GHQ-12, considering the role of method effects associated with both, PW and NW items, and using two alternative parameterisations of the CFA measurement models. What should first be noted is that the studies that have included method effects in the measurement model of the GHQ-12 have been more the exception than the rule in previous research into the factor structure of this questionnaire. According to the results of the present study, we conclude that the GHQ-12 factor structure is best characterised by introducing latent method factors that capture both the method effects associated with NW and PW items (model 7). These results support the conclusion from previous research that the good fit obtained by multidimensional models (mainly the two-factor model and the three-factor Graetz's model) could simply be explained by the artificial grouping of PW and NW items. However, the interpretation of the latent (method) factors as purely integrating method bias due to wording is not straightforward. It is obvious that NW and PW items share the wording. It is also clear that this three bifactor model (one trait and two method factors) fitted the data best. And finally, there is a lot of empirical evidence on these wording effects. However, it is also relevant to discuss the large loadings of many items on the method factors, being these loadings sometimes larger than their loadings in the trait factor. The general factor explains a 52% of the shared variance, but there are some items that deserve careful attention. For example, items 3 ('playing useful part in things') and 4 ('capable of making decisions') had very low loadings on the trait factor. If we understand PW method factor as the only method bias, then it follows that these two items are purely method effects, but surely they must share some trait variance. In the same vein, items 10 ('losing confidence in yourself') and 11 ('thinking of yourself as a worthless person') load very high in the NW method factor and, as a reviewer pointed out, a likely (post-hoc) explanation is that wording bias are still confounded with a confidence/self-image factor. Therefore, the interpretation of these effects as purely method and, accordingly, the interpretation of an overall score for the scale difficult may be compromised. The second aim of this study was to examine the relationship between the method factors associated with both NW and PW items and three demographic variables, namely sex, age and educational level of the respondents. Regarding the sex, we found a statistically significant, but weak, relationship between PW and sex, so that men were more likely than women to endorse PW items. These results are in line with previous works that, in the context of RSES, have found sex differences in wording effects. 56 57 As for the explanatory role of age on method effects, we found that the relationship between age and the NW effect was not statistically significant, which supports previous research using other questionnaires (eg, self-esteem scales, 50 Hospital Anxiety & Depression Scale 64). Moreover, our results give support to previous studies which had stated that, in older adults, the strongest method effects would be associated with PW items, rather than NW items. 55 58 As to the educational level, we found that there was not a significant correlation of this variable on the two method factors. This result supports and extends the evidence obtained in Tomás et al 50 who found that the educational level of the respondents had no effect on the negative method factor using self-esteem questionnaires. This results contradicts previous research on the relationship of the NW factor and the educational level/verbal ability with different questionnaires and samples. 41 64-69 Overall, the significant effects of sex and age on trait and method factors point out that women have a worse well-being, but this effect is partly modified by a method effect on the PW items, whereas the results for age suggest that older respondents have worse well-being and this effect is magnified by a method effect on the PW factor. The results on the individual differences related to the demographic variables considered in this study cannot only help to understand the presence of wording method effects but also to identify respondents who are prone to answering PW and NW items differently. In this sense, the relationship that appears as more evident is for the age and sex variables. Another practical consequence of our study concerns the relationship between the intended measure of the GHQ-12 (ie, the GPH factor) and other constructs of interest. Several studies have shown that method effects can inflate, deflate or have no effect at all on estimates of the relationship between two constructs (see Podsakoff et al 70 for a further review of the effects that method biases have on individual measures and on the covariation between different constructs). Thus, it is desirable that both the constructs of interest as well as the effects of method factors, like PW and NW, are considered in SEM models as a means of controlling these systematic sources of bias, and thus avoiding the drawing of inaccurate conclusions about the relationship between the substantive factors. Previous research on the GHQ-12 31 36 has outlined the asymmetry in the participants' responses as a function of the wording of the items, as well as the different responses scales for the PW and NW items. This asymmetry in the participants' responses as a function of the wording of the items is consistent with results from previous research into wording effects for contrastive survey questions. 71 The extent to which the presence of method effects is linked to the asymmetric pattern of responses and/or to the different response scales for the PW and NW items in the GHQ-12 should be examined in future research. Comparing the current work with previous studies into the factorial structure of the GHQ-12, to our knowledge, this is the first study that tests a comprehensive set of models including method effects associated with both PW and NW items and also explores some demographic correlates of these method effects. Another strength of this work was the fact that it used a large representative sample of workers, but the results might not be generalised to other specific populations, for example, adolescents and elderly retired people. Twitter @jmlosilla, @VivesJ_Research Contributors All authors meet the criteria recommended by the International Committee of Medical Journal Editors (ICMJE). All authors made substantial contributions to conception and design, acquisition of data or analysis and interpretation of data. MFR and JGM: drafted the article. JV and JML: critically revised the draft for important intellectual content. JMT: worked in the statistical analysis and interpretation of data. All authors agreed on the final version. Funding This work was supported by the Grant PGC2018-100675-B-I00, Spanish Ministry of Science, Innovation and Universities (Spain). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. Disclaimer All authors have agreed to authorship in the indicated order. All authors declare that this paper is an original unpublished work and it is not being submitted elsewhere. All authors do not have any financial interests that might be interpreted as influencing the research, and APA ethical standard were followed in the conduct of the study. Competing interests None declared. Patient consent for publication Not required. Ethics approval The research was not submitted to approval by an institutional review board since this is not a requirement at our universities for this type of study. Ethics approval was not sought for this study since this was a secondary analysis of anonymised data. Provenance and peer review Not commissioned; externally peer reviewed. Data availability statement Data are available upon reasonable request.Objective Recent studies into the factorial structure of the 12-item version of the General Health Questionnaire (GHQ-12) have shown that it was best represented by a single substantive factor when method effects associated with negatively worded (NW) items are considered. The purpose of the present study was to examine the presence of method effects, and their relationships with demographic covariates, associated with positively worded (PW) and/or NW items. Design A cross-sectional, observational study to compare a comprehensive set of confirmatory factor models, including method effects associated with PW and/or NW items with GHQ-12 responses. Setting Representative sample of all employees living in Catalonia (Spain). Participants 3050 participants (44.6% women) who responded the Second Catalonian Survey of Working Conditions. Results A confirmatory factor analysis showed that the best fitting model was a unidimensional model with two additional uncorrelated method factors associated with PW and NW items. Furthermore, structural equation modelling (SEM) revealed that method effects were differentially related to both the sex and age of the respondents. Conclusion Individual differences related to sex and age can help to identify respondents who are prone to answering PW and NW items differently. Consequently, it is desirable that both the constructs of interest as well as the effects of method factors are considered in SEM models as a means of avoiding the drawing of inaccurate conclusions about the relationships between the substantive factors
Optimization of a laccase-mediator stage for TCF bleaching of flax pulp
7 p.-3 fig.-3 tab.Flax pulp obtained by anthraquinone-soda pulping, resulting in a kappa number of 11.1, a viscosity of 950 ml/g and 36.7% ISO brightness, was bleached in a totally chlorine-free sequence using the enzyme laccase from the fungus Pycnoporus cinnabarinus and 1-hydroxybenzotriazole (HBT) as redox mediator (stage L), followed by a hydrogen peroxide stage (P). The laccase treatment was optimized using a three-variable sequential statistical plan over the following ranges: 1–20 U/g o.d.p. (oven-dried pulp) laccase dose, 0.5–7.5% o.d.p. HBT dose and 1–24 h reaction time. The influence of these variables on several pulp properties after the P stage of the LP sequence was examined.The models defined from the results obtained predicted variations in ISO brightness, viscosity and kappa number of 57.6–74.8%, 590–955 ml/g and 0–6.2, respectively. The variables most strongly influencing these pulp properties were found to be the reaction time and the enzyme dose. A compromise was adopted as regards the operating conditions in order to ensure optimum results. The study was completed by conducting a biobleaching assay in a pressurized reactor (590 kPa) to assess the effect of oxygen pressure. The high pressure level resulted in improved pulp properties by the laccase-mediator system.This work was supported by Spanish CICyT (Project PPQ2000–1068-C02-02, and FEDER Project 2FD97-0896-C02) and Comunidad Autónoma de Madrid, the EU Commission (QLK3-99-590) and the Spanish grant 2002FI 00556.Peer reviewe
Bioavailability, mobility and leaching of phosphorus in a Mediterranean agricultural soil (ne Spain) amended with different doses of biosolids
The precipitation of sparingly soluble
calcium phosphate in calcareous soils decreases the
bioavailability of macronutrients, which makes their
addition by way of fertilisers necessary. Sludge
resulting from treating urban wastewater does not
only provide significant amounts of phosphorus, but
also helps lower the pH, thus increasing its bioavailability.
The loss of part of soil nutrients due to
irrigation or rain can contaminate groundwater. In
order to assess the movement of phosphorus, a
experiment was conducted on percolation columns,
to which different doses of wastes were applied. The
pH decreased by as much as 0.89 units, as well as the
assimilable and soluble P, in intervals of 20 cm of
depth, obtaining maximum values of 254 mg P kg-1
and 1455 lg P kg-1 respectively, and the P present in
the leached water collected, which did not surpass
95 lg PL-1. The intent was to learn which was the
majoritarian inorganic formed crystalline phase that
immobilised the movement of phosphorus through the
percolation column. The results obtained by the
diffraction of X-rays are not conclusive, although
they point to the formation of octacalcium phosphate.
The diffractograms of the studied samples have
similar diffraction lines to those of apatites
Adrenal cortex stimulation with hCG in spayed female dogs with Cushing’s syndrome: Is the LH-dependent variant possible?
Background: The expression and overexpression of luteinizing hormone (LH) receptors in the canine adrenal gland cortex have been reported. Therefore, it was hypothesized that a LH-dependent form of Cushing’s syndrome (CS) could exist in dogs.Aim: To assess whether the adrenal gland post-ovariectomy (OVx) exhibits a greater response to adrenocorticotrophin (ACTH) stimulation; to evaluate whether the adrenal gland responds to human chorionic gonadotropin (hCG) stimulation by increasing the release of cortisol; and to consider whether hCG stimulus testing would be useful as a diagnosis for possible cases of LH-dependent CS.Methods: Cortisol concentrations were measured from healthy female dogs (n=16) at baseline and following ACTH stimulation before and 2 months after gonadectomy (OVx). Cortisol concentrations were also measured for female dogs with CS (n = 14) following administration of hCG (5000 IU). A post-hCG cortisol concentration greater than 140 nmol/l was used to define dogs with LH-dependent Cushing’s syndrome.Results: In normal female dogs, both pre- and post-stimulation cortisol concentrations increased following OVx (p = 0.002 and p = 0.0003, respectively). In female dogs with CS, cortisol concentrations increased following stimulation with hCG in 57% (8/14; p = 0.002). Age at the time of OVx was associated (p = 0.015) with the cortisol response to hCG [8 (5–9) years vs. 3.5 (2–6) years, p = 0.0013).Conclusion: Based on these results, an LH-dependent form of CS occurs in spayed female dogs, and that it is more likely to occur when female dogs are spayed later in life
Left ventricular thrombus mimicking primary cardiac tumor in a patient with primary antiphospholipid syndrome and recurrent systemic embolism
Primary antiphospholipid syndrome (APS) is a well-defined entity characterized by spontaneous
and recurrent abortion, thrombocytopenia and recurrent vascular thromboses (arterial
and venous). Left ventricular thrombus mimicking primary cardiac tumor with recurrent
systemic embolism has not been previously reported.
In this report we describe a 39 year-old man admitted to hospital presenting with left hemiparesis
and a peripheral embolism. He had no history of thrombotic events. Transthoracic
echocardiography showed a large, polypoid and mobile mass (4.0 × 1.2 cm) attached to the
apex of the left ventricle, highly suggestive of primary cardiac tumor. The patient subsequently
underwent open heart surgery. The histological examination showed an older thrombus and
a fresh thrombus. Post-operative laboratory tests showed lupus anticoagulant activity, confirming
the primary APS diagnosis. The patient initiated treatment with oral anticoagulation
(INR levels between 2 and 3) and was discharged 29 days after surgery. At ten month follow-up, he was symptom-free with long-term anticoagulation therapy. No evidence of intracardiac
mass recurrence on two-dimensional echocardiography was seen.
Intracardiac thrombus has been rarely reported as a complication of primary APS. Left ventricular
mass mimicking primary cardiac tumor with recurrent systemic embolism has not
been previously reported. Pre-operative investigations could not distinguish such a thrombus
from a cardiac tumor and the diagnosis was made post-operatively
Fast-timing study of the l-forbidden 1/2+→3/2+ M1 transition in Sn129
R. Lică et al. ; 7 págs.; 5 figs.; 3 tabs. ; Open Access funded by Creative Commons Atribution Licence 3.0The levels in Sn129 populated from the β- decay of In129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 12+ state and the 32+ ground state in Sn129 are expected to have configurations dominated by the neutron s12 (l=0) and d32 (l=2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we have measured the half-life of the 12+ 315.3-keV state, T12= 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T12 value by the renormalization of the M1 effective operator for neutron holes.This work was partially supported by the Spanish MINECO through Projects
No. FPA2012-32443, No. FPA2013-41267-P, and CPAN
Consolider (Project No. CSD-2007-00042), and by Romanian
IFA Grant CERN/ISOLDE. It was also partly funded by
the NuPNET network FATIMA (PRI-PIMNUP-2011-1338),
by FWO-Vlaanderen (Belgium), by GOA/2010/010 (BOF
KU Leuven), and by the Interuniversity Attraction Poles
Programme initiated by the Belgian Science PolicyOffice
(BriX network P7/12). Support from Grupo de Física Nuclear
(GFN-UCM), Programmi di Ricerca Scientifica di Rilevante
Interesse Nazionale (PRIN) Grant No. 2001024324 01302,
German BMBF under Contracts No. 05P12PKFNE and No.
05P15PKCIA, the U.K. Science and Technology Facilities
Council, and the European Union Seventh Framework through
ENSAR (Contract No. 262010) is also acknowledged. Fasttiming
electronics were provided by the Fast Timing Collaboration,
the ISOLDE Decay Station collaboration, and MASTICON.Peer Reviewe
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