829 research outputs found

    Numerical study of the aerodynamic performance of NACA 0012 in the presence of an unsteady heat source

    Get PDF
    The objective of this paper is to study the effect of an unsteady moving heat source on the aerodynamic performance of an NACA 0012 airfoil section, with particular focus on the lift and drag coefficients. The compressible Navier–Stokes equations are solved using a finite volume method as well as Spalart-Allmaras Model for turbulence simulation. The heat source periodically moves over the lower surface of the airfoil in the downstream direction. The numerical results show how the drag and lift coefficient strongly depend upon the velocity of the source. For a constant source power, a progressive improvement in the mean values of lift and drag coefficients is observed as velocity increases

    Discriminación de bosques de Araucaria araucana en el Parque Nacional Conguillío, centro-sur de Chile, mediante datos Landsat TM

    Get PDF
    Martin, JS (San Martin, Jose). Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, ChileAraucaria forests (Araucaria araucana) have a tremendous ecological relevance; however, the information concerning their spatial distribution is still insufficient. They have only been classified according to small management scales, using satellite photos and images processed through conventional methods. The present study had as its objective to discriminate and characterize types of A. araucana forests in the Conguillio National Park, located in the Southern-Center Chile, through data derived from the Landsat-5 TM satellite and geographic information systems. The normalized difference vegetation index (NDVI) was satisfactorily related with variables corresponding to crown coverage and the diameter at breast height; thus, these index values were incorporated to the classification process. Using the digital elevation model and the NDVI, the effect provoked by the shadow was minimized. Seven types of forests, between dense and semi-dense-open, were discriminated in accordance with the accompanying species. The global reliability of the classification was 83.8 %. The greatest reliability for the producer was for the medium crown density forest of A. araucana - N. dombeyi (B1) (87.5 %); and for the consumer, for the high crown density forests of A. araucana - N. dombeyi (B1) and also for those of medium density (B2) (93 %). It is concluded that incorporating NDVI values and data derived from the digital elevation model to the satellite classification process, it is possible to discriminate araucaria forests with satisfactory reliability in areas of rough relief, which is very useful information for the management of these forestry ecosystems

    Remarks on the determination of the Landau gauge OPE for the Asymmetric three gluon vertex

    Get PDF
    We compute a compact OPE formula describing power corrections to the perturbative expression for the asymmetric MOM~\widetilde{MOM}-renormalized running coupling constant up to the leading logarithm. By the use of the phenomelogical hypothesis leading to the factorization of the condensates through a perturbative vacuum insertion, the only relevant condensate in the game is . The validity of the OPE formula is tested by searching for a good-quality coherent description of previous lattice evaluations of MOM~\widetilde{MOM}-renormalized gluon propagator and running coupling.Comment: 12 pages, 3 figures (2 generated by the macro: axodraw.sty

    Non-negative Wigner functions in prime dimensions

    Get PDF
    According to a classical result due to Hudson, the Wigner function of a pure, continuous variable quantum state is non-negative if and only if the state is Gaussian. We have proven an analogous statement for finite-dimensional quantum systems. In this context, the role of Gaussian states is taken on by stabilizer states. The general results have been published in [D. Gross, J. Math. Phys. 47, 122107 (2006)]. For the case of systems of odd prime dimension, a greatly simplified proof can be employed which still exhibits the main ideas. The present paper gives a self-contained account of these methods.Comment: 5 pages. Special case of a result proved in quant-ph/0602001. The proof is greatly simplified, making the general case more accessible. To appear in Appl. Phys. B as part of the proceedings of the 2006 DPG Spring Meeting (Quantum Optics and Photonics section

    Association between Birth Plan Use and Maternal and Neonatal Outcomes in Southern Spain: A Case-Control Study

    Get PDF
    Background: Birth plans are used for pregnant women to express their wishes and expectations about childbirth. The aim of this study was to compare obstetric and neonatal outcomes between women with and without birth plans. Methods: A multicentre, retrospective case–control study at tertiary hospitals in southern Spain between 2009 and 2013 was conducted. A total of 457 pregnant women were included, 178 with and 279 without birth plans. Women with low-risk gestation, at full-term and having been in labour were included. Sociodemographic, obstetric and neonatal variables were analysed and comparisons were established. Results: Women with birth plans were older, more educated and more commonly primiparous. Caesarean sections were less common in primiparous women with birth plans (18% vs. 29%, p = 0.027); however, no significant differences were found in instrumented births, 3rd–4th-degree tears or episiotomy rates. Newborns of primiparous women with birth plans obtained better results on 1 min Apgar scores, umbilical cord pH and advanced neonatal resuscitation. No significant differences were found on 5 min Apgar scores or other variables for multiparous women. Conclusions: Birth plans were related to less intervention, a more natural process of birth and better outcomes for mothers and newborns. Birth plans can improve the welfare of the mother and newborn, leading to birth in a more natural way

    Google Trends on Obesity, Smoking and Alcoholism: Global and Country-Specific Interest

    Get PDF
    Unhealthy habits or lifestyles, such as obesity, smoking, and alcohol consumption, are involved in the development of non-communicable diseases. The aim of this study was to analyze different communities’ interest in seeking obesity, smoking, and alcohol-related terms through relative search volumes (RSVs) of Google Trends (GT). Internet search query data on obesity, smoking, and alcohol-related terms were obtained from GT from the period between 2010 and 2020. Comparisons and correlations between different topics were calculated considering both global searches and English-, Spanish-, and Italian-speaking areas. Globally, the RSVs for obesity and alcohol-related terms were similar (mean RSVs: 76% and 77%), but they were lower for smoking (65%). High RSVs were found in winter for obesity and smoking-related terms. Worldwide, a negative correlation was found between alcohol and smoking terms (r = −0.72, p < 0.01). In Italy, the correlation was positive (r = 0.58). The correlation between obesity and alcohol was positive in all the cases considered. The interest of global citizens in obesity, smoking, and alcohol was high. The RSVs for obesity were globally higher and correlated with alcohol. Alcohol and smoking terms were related depending on the area considered

    Prevalence of infection with high-risk human papillomavirus in women in Colombia

    Get PDF
    AbstractThe prevalence of human papillomavirus (HPV) infections in 2109 females inhabiting five cities of Colombia was determined. Of the 49.2% with an HPV infection, 59.8% were infected with more than one viral type. Species 7 (of the the genus Alphapapillomavirus) was associated with multiple infections. Analysis of the socio-demographic data revealed a statistically significant protective effect associated with the status of civil union (civil recognition of cohabitation without marriage), and indigenous ethnicity proved to be a risk factor for HPV infection. This is the first study comparing HPV infection among women from geographical regions of Colombia with different socio-cultural structures

    Brillouin optical time-domain analysis over a 240 km-long fiber loop with no repeater

    Get PDF
    22nd International Conference on Optical Fiber Sensors (OFS2012), Beijing, China, October 14, 2012In this paper we combine the use of optical pulse coding and seeded second-order Raman amplification to extend the\ud sensing distance of Brillouin optical time-domain analysis (BOTDA) sensors. Using 255-bit Simplex coding, the power\ud levels of the Raman pumps and the Brillouin pump and probe signals were adjusted in order to extend the real physical\ud sensing distance of a BOTDA sensor up to 120 km away from the sensor interrogation unit, employing a 240-km long\ud loop of standard single-mode fiber (SSMF) with no repeater. To the best of our knowledge, this is the first time that\ud distributed measurements are carried out over such a long distance with no active device inserted into the entire sensing\ud loop, constituting a considerable breakthrough in the field

    Levels of Physical Activity, Obesity and Related Factors in Young Adults Aged 18–30 During 2009–2017

    Get PDF
    The objective of this study was to analyze the temporal trend of physical activity and body mass index in young adults aged 18–30 in Spain and to ascertain their relationship with sociodemographic and psychosocial variables in the period of 2009–2017. Methods: A descriptive study with a sample of 10,061 young adults aged 18–30 years was performed. The data were obtained from the European Health Survey in Spain in 2009 and 2014 and the National Health Survey in 2011/2012 and 2017. The chi-square test was used for qualitative variables, and multiple linear regression analysis was performed for physical activity. Results: Sedentary levels had decreased in 2017 as compared to 2011/2012 (p < 0.001); smokers were more sedentary than non-smokers (p < 0.001); men were more active than women (p < 0.001); and the year with the highest physical activity was 2014. Body mass index in the total sample increased from 2009 to 2017 (p < 0.01), showing a significant increase in obesity in women (p < 0.05) and no difference in men (p ≥ 0.05). Conclusions: In the period 2011/2012–2017, the sedentary lifestyle of young adults was reduced and physical activity was increased, with men being more active than women
    corecore