122,656 research outputs found

    George Higoumenakis (1895-1983): Greek dermatologist

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    This paper describes the Higoumenakis sign, enlargement of the sternal end of the clavicle in patients with late congenital syphilis and the dermatologist after whom it is named. Several professors and doctors from the Medical School of the University of Athens opposed his actions especially at the University in Greece. His persistence led him to productive scientific activity in syphilis, leishmaniasis and psoriasis. fie became a member of the Greek Parliament from 1964 to 1967 and eventually Minister of Hygiene - even though this may have been an imprudent political choice, due to the unstable socio-political status of that period. He died on 27 December 1983 at the age of 88

    An R library for compositional data analysis in archaeometry

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    Compositional data naturally arises from the scientific analysis of the chemical composition of archaeological material such as ceramic and glass artefacts. Data of this type can be explored using a variety of techniques, from standard multivariate methods such as principal components analysis and cluster analysis, to methods based upon the use of log-ratios. The general aim is to identify groups of chemically similar artefacts that could potentially be used to answer questions of provenance. This paper will demonstrate work in progress on the development of a documented library of methods, implemented using the statistical package R, for the analysis of compositional data. R is an open source package that makes available very powerful statistical facilities at no cost. We aim to show how, with the aid of statistical software such as R, traditional exploratory multivariate analysis can easily be used alongside, or in combination with, specialist techniques of compositional data analysis. The library has been developed from a core of basic R functionality, together with purpose-written routines arising from our own research (for example that reported at CoDaWork'03). In addition, we have included other appropriate publicly available techniques and libraries that have been implemented in R by other authors. Available functions range from standard multivariate techniques through to various approaches to log-ratio analysis and zero replacement. We also discuss and demonstrate a small selection of relatively new techniques that have hitherto been little-used in archaeometric applications involving compositional data. The application of the library to the analysis of data arising in archaeometry will be demonstrated; results from different analyses will be compared; and the utility of the various methods discussedGeologische Vereinigung; Institut d’Estadística de Catalunya; International Association for Mathematical Geology; Patronat de l’Escola Politècnica Superior de la Universitat de Girona; Fundació privada: Girona, Universitat i Futur; Càtedra Lluís Santaló d’Aplicacions de la Matemàtica; Consell Social de la Universitat de Girona; Ministerio de Ciencia i Tecnología

    Evaluating the perception of thermal environment in naturally ventilated schools in a warm and humid climate in Nigeria

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    Field study was conducted in naturally ventilated primary school buildings in a warm and humid environment in Imo State, Nigeria to determine the thermal comfort perception of young children (aged 7–12 years) and to understand the thermal conditions in the classrooms. The comfort temperature was investigated in two types of classroom buildings during the rainy and dry seasons from October 2017 to May 2018. Approximately 7050 completed valid questionnaires were collected from 330 young children repeatedly surveyed twice a day. The children answered comfort questions at the same time the indoor and outdoor thermal variables were being measured. Results indicated that the combined ‘open-space’ classrooms produced a neutral temperature of 28.8°C with comfort range, 25.2–32.3°C. The neutral temperature of the combined ‘enclosed-plan’ classrooms is 28.1°C with 25.8–30.5°C as the comfort range. The differences in the comfort perceptions may be attributed to the differences in the architectural characteristics of both categories of classroom buildings. High temperature tolerance was shown by the participating children in the study area. This article, therefore, suggests that installing air conditioning in primary schools in the warm humid environment in Nigeria may not be necessary as it could lead to unnecessary energy consumption and carbon emission

    Compositional analysis of archaeological glasses

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    At CoDaWork'03 we presented work on the analysis of archaeological glass composi- tional data. Such data typically consist of geochemical compositions involving 10-12 variables and approximates completely compositional data if the main component, sil- ica, is included. We suggested that what has been termed `crude' principal component analysis (PCA) of standardized data often identi ed interpretable pattern in the data more readily than analyses based on log-ratio transformed data (LRA). The funda- mental problem is that, in LRA, minor oxides with high relative variation, that may not be structure carrying, can dominate an analysis and obscure pattern associated with variables present at higher absolute levels. We investigate this further using sub- compositional data relating to archaeological glasses found on Israeli sites. A simple model for glass-making is that it is based on a `recipe' consisting of two `ingredients', sand and a source of soda. Our analysis focuses on the sub-composition of components associated with the sand source. A `crude' PCA of standardized data shows two clear compositional groups that can be interpreted in terms of di erent recipes being used at di erent periods, re ected in absolute di erences in the composition. LRA analysis can be undertaken either by normalizing the data or de ning a `residual'. In either case, after some `tuning', these groups are recovered. The results from the normalized LRA are di erently interpreted as showing that the source of sand used to make the glass di ered. These results are complementary. One relates to the recipe used. The other relates to the composition (and presumed sources) of one of the ingredients. It seems to be axiomatic in some expositions of LRA that statistical analysis of compositional data should focus on relative variation via the use of ratios. Our analysis suggests that absolute di erences can also be informativeGeologische Vereinigung; Institut d’Estadística de Catalunya; International Association for Mathematical Geology; Patronat de l’Escola Politècnica Superior de la Universitat de Girona; Fundació privada: Girona, Universitat i Futur; Càtedra Lluís Santaló d’Aplicacions de la Matemàtica; Consell Social de la Universitat de Girona; Ministerio de Ciencia i Tecnología

    Internet Addiction among Greek University Students: Demographic Associations with the Phenomenon, Using the Greek Version of Young's Internet Addiction Test

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    Internet addiction (IA) is a new disorder described in 1996 by the psychologist Kimberly Young. The aim of this paper is to estimate the percentage of IA among Greek university students. Results of a sample survey among 1876 Greek university students, 18-27 years old, are presented. The questionnaire consisted of eight questions from Young’s Diagnostic Test for Internet Addiction (YDTIA) as well as an inventory including demographic factors and questions about academic performance, computer and Internet use. YDTIA had a good reliability and diagnostic accuracy, tested with Cronbach’s alpha (0.71) and sensitivity analysis. Results show that the percentage of IA (5-8 YDTIA criteria) is 11.6%, while problematic Internet users were (3-8 YDTIA criteria) 34.7%. Men were more likely to be addicted to the Internet than women, and Internet addicted students were associated with poorer academic performance. Multiple logistic regression showed that significant predictors of IA included increased hours of daily Internet use, increased hours visiting chat rooms, sex pages and blogs, male gender, divorced status, poor grades, and accessing the Internet outside of the home. The results of this study will allow health officials to recognise students who are Internet addicted or on the verge of becoming addicted and stress risk factors indicating a need for intervention in order to prevent the appearance of IA

    Interaction of aluminium hydrolytic species with biomolecules

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    In this contribution the formation of bioinorganic assemblies between the basic globular protein lysozyme and aqueous aluminium species including Al 13 -mer, Al 30 -mer and colloidal aluminium hydroxide have been explored and comparison made to previous interaction studies performed with bovine serum albumin (BSA). Specific charge-stabilised bioinorganic assemblies involving aluminium species and lysozyme were observed to form in contrast to the gel like structures formed on interaction of BSA with aluminium species. As demonstrated by infrared spectroscopy (structural assignment, 2D correlation spectroscopy), interactions mostly involve acidic surface groups of the proteins (Asp, Glu), with strong complexation and deprotonation in the case of BSA interacting with Al 13 and Al 30 and through hydrogen bonding for lysozyme interacting with the same species and aluminium hydroxide particles interacting with both biomolecules

    MINDtouch: Embodied mobile media ephemeral transference

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    Copyright @ 2013 ISAST.This article reviews discoveries that emerged from the author's MINDtouch media research project, in which a mobile device was repurposed for visual and non-verbal communication through gestural and visual mobile expressivity. The work revealed new insights from emerging mobile media and participatory performance practices. The author contextualizes her media research on mobile video and networked performance alongside relevant discourse on presence and the embodiment of technology. From the research, an intimate, phenomenological and visual form of mobile expression has emerged. This form has reconfigured the communication device from voice and text/SMS only to a visual and synesthetic mode for deeper expression

    Streaming potentials in hydrocarbon reservoir conditions

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