2,838 research outputs found
Brazilian elections: voting for a scaling democracy
The proportional elections held in Brazil in 1998 and 2002 display identical
statistical signatures. In particular, the distribution of votes among
candidates includes a power-law regimen. We suggest that the rationale behind
this robust scaling invariance is a multiplicative process in which the voter's
choice for a candidate is governed by a product of probabilities.Comment: 4 pages, 2 figure
Detailed Chemical Abundances of Globular Clusters in Local Group Dwarf Galaxies
We present detailed chemical abundances of Fe, Ca and Ba for 17 globular
clusters (GCs) in 5 Local Group dwarf galaxies: NGC 205, NGC 6822, WLM, the SMC
and LMC. These abundances are part of a larger sample of over 20 individual
elements measured in GCs in these galaxies using a new analysis method for high
resolution, integrated light spectra. Our analysis also provides age and
stellar population constraints. The existence of GCs in dwarf galaxies with a
range of ages implies that there were episodes of rapid star formation
throughout the history of these galaxies; the abundance ratios of these
clusters suggest that the duration of these burst varied considerably from
galaxy to galaxy. We find evolution of Fe, Ca, and Ba with age in the LMC, SMC,
and NGC 6822 that is consistent with extended, lower-efficiency SF between
bursts, with an increasing contribution of low-metallicity AGB ejecta at late
times. Our sample of GCs in NGC 205 and WLM are predominantly old and
metal-poor with high [Ca/Fe] ratios, implying that the early history of these
galaxies was marked by consistently high SF rates.Comment: 2 pages, To appear in the proceedings of the conference "A Universe
of Dwarf Galaxies" (Lyon, June 14-18, 2010
Estimating the trunk transverse surface area to assess swimmer's drag force based on their competitive level
The aim of this study was to compute and validate trunk transverse surface area (TTSA) estimation
equations to be used assessing the swimmer’s drag force according to competitive level by gender. One
group of 130 swimmers (54 females and 76 males) was used to compute the TTSA estimation equations and
another group of 132 swimmers (56 females and 76 males) were used for its validations. Swimmers were
photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The
TTSA was measured from the swimmer’s photo with specific software. It was also measured the height,
body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first
group of swimmers it was computed the TTSA estimation equations based on stepwise multiple regression
models from the selected anthropometrical variables. The TTSA prediction equations were significant and
with a prediction level qualitatively considered as moderate. All equations included only the CP and the
CSD in the final models. In all prediction models there were no significant differences between assessed and
estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and
estimated TTSA were moderate and significant. More than 80% of the plots were within the 95% interval
confidence for the Bland-Altman analysis in both genders. So, TTSA estimation equations that are easy to be
computed by coached and researchers were developed. All equations accomplished the validation criteria
adopted
Validação de equações preditivas da área de secção
O objectivo do estudo foi desenvolver e validar equações para estimar a área de secção
transversa do tronco (ASTT), em ambos os sexos, de acordo com o nível competitivo, que
habitualmente são usadas para avaliar o arrasto hidrodinâmico.
Para o sexo feminino, na condição de experts, foi utilizado um grupo de 33 sujeitos para estimar a
equação e um grupo de 38 sujeitos para validar a equação, na condição de não experts foi utilizado
um grupo de 23 sujeitos para estimar a equação e um grupo de 18 sujeitos para validar a mesma.
No caso do sexo masculino, na condição de experts, foi utilizado um grupo de 28 sujeitos para
estimar a equação e um grupo de 32 sujeitos para a validar, na condição de não experts, foi
utilizado um grupo de 48 sujeitos para estimar a equação e um grupo de 44 sujeitos para validar a
equação. Os sujeitos foram fotografados (DSC-T7, Sony, Tóquio, Japão) num plano superior
transversal, no meio terrestre, simulando a posição hidrodinâmica. A ASTT foi medida através da
foto digital do sujeito com um software específico (Universal Desktop Ruler, v3.3.3268, AVPSoft,
E.U.A.). Foram ainda medidas as variáveis antropométricas massa corporal (SECA, 884,
Hamburgo, Alemanha), a estatura (SECA, 242, Hamburgo, Alemanha), os diâmetros bi-acromial
(DBC) e tóraco-sagital (DTS) com um clip antropométrico (Campbell, 20, RossCraft, Canadá),
assim como, o perímetro peitoral (PP) com fita métrica (RossCraft, Canadá). Para sexo feminino
experts ASTT=16,498*DTS+10,875*PP-504,705 (R2=0,28; Ra=0,24; p<0,01). Para sexo feminino
não experts ASTT=14,836*PP-26,825*DTS-33,149 (R2=0,28; Ra=0,21; p<0,01). Para sexo
masculino experts ASTT=19,216*DTS+10,505*PP-575,496 (R2=0,33; Ra=0,27; p<0,01). Para
sexo masculino não experts ASTT=30,453*DTS+5,030*PP-371,404 (R2=0,48; Ra=0,45; p<0,01).
Em todas as condições, por sexo e nível competitivo, não se verificaram diferenças estatisticamente
significativas entre a média da ASTT medida e da estimada. Os coeficientes de determinação,
calculados através da análise de regressão linear, entre a ASTT medida e estimada foram
moderados. Para todas as condições, por sexo e nível competitivo, mais de 80% dos plots, na análise de Bland-Altman, encontram-se dentro dos 95% do intervalo de confiança
Validação de equações preditivas da área de secção transversa do tronco
O objectivo do estudo foi desenvolver e validar equações preditivas da área de secção transversa do tronco humano, Os modelos foram desenvolvidos para o sexo masculino e de acordo com o nível competitivo, A amostra foi composta por 152 sujeitos, todos praticantes de Natação Pura desportiva, com idades entre os 10 e os 32 anos de idade. Para o desenvolvimento dos modelos foi utilizado um grupo de sujeitos para estimar a equação e um outro para validar. Foram avaliadas as seguintes características antropométricas: (i) massa corporal; (ii) estatura; (iii) diâmetro bi-acromial; (iv) diâmetro tóraco-sagital; (v) perímetro peitoral e (vi) área de secção transversal do tronco. Os modelos preditivos foram desenvolvidos através de análise de regressão linear múltipla passo-a-passo e num dos casos, com recurso ao nível competitivo enquanto variável dummy. Todos os modelos desenvolvidos incluíram como variáveis independentes o diâmetro tóraco-sagital e o perímetro peitoral (0,32 ≤ R2 ≤ 0,48; P 0,05), as regressões lineares simples foram moderadas (0,23 ≤ R2 ≤ 0,39; 0,01 ≤ P ≤ 0,001) e o critério de Bland Altman foi em todos os casos cumprido. Pode concluir-se que os modelos desenvolvidos para nadadores masculinos, e de acordo com o nível competitivo, predizem com validade a área de secção transversa do tronco de nadadores
Morphometric study for estimation and validation of trunk transverse surface area to assess human drag force on water
The aim of this study was to compute and validate estimation equations for the trunk transverse surface area (TTSA) to be used in assessing the swimmer's drag force in both genders. One group of 133 swimmers (56 females, 77 males) was used to compute the estimation equations and another group of 131 swimmers (56 females, 75 males) was used for its validations. Swimmers were photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The TTSA was measured from the swimmer's photo with specific software. Also measured was the height, body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first group of swimmers, it was computed the TTSA estimation equations based on stepwise multiple regression models from the selected anthropometrical variables. For males TTSA=6.662*CP+17.019*CSD-210.708 (R2=0.32; Ra2=0.30; P<0.01) and for females TTSA=7.002*CP+15.382*CSD-255.70 (R2=0.34; Ra2=0.31; P<0.01). For both genders there were no significant differences between assessed and estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and estimated TTSA were R2=0.39 for males and R2=0.55 for females. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders
The evaluation of student-centredness of teaching and learning: a new mixed-methods approach.
OBJECTIVE: The aim of the study was to develop and consider the usefulness of a new mixed-methods approach to evaluate the student-centredness of teaching and learning on undergraduate medical courses. An essential paradigm for the evaluation was the coherence between how teachers conceptualise their practice (espoused theories) and their actual practice (theories-in-use). METHODS: The context was a module within an integrated basic sciences course in an undergraduate medical degree programme. The programme had an explicit intention of providing a student-centred curriculum. A content analysis framework based on Weimer's dimensions of student-centred teaching was used to analyze data collected from individual interviews with seven teachers to identify espoused theories and 34h of classroom observations and one student focus group to identify theories-in-use. The interviewees were identified by purposeful sampling. The findings from the three methods were triangulated to evaluate the student-centredness of teaching and learning on the course. RESULTS: Different, but complementary, perspectives of the student-centredness of teaching and learning were identified by each method. The triangulation of the findings revealed coherence between the teachers' espoused theories and theories-in-use. CONCLUSIONS: A mixed-methods approach that combined classroom observations with interviews from a purposeful sample of teachers and students offered a useful evaluation of the extent of student-centredness of teaching and learning of this basic science course. Our case study suggests that this new approach is applicable to other courses in medical education
Texturing methods of abrasive grinding wheels: a systematic review
Creating textures on abrasive wheels is a strategy that allows a significant improvement in grinding operations. The reduction of the internal stresses in the workpiece and the temperature during the grinding operation generates an increase in the dimensional accuracy of the workpiece and a longer tool life. Textured abrasive wheels can be produced in many different ways. Depending on the processing method, the dimensional accuracy of the tool and its applicability is changed. Some methods can produce tools with three-dimensional grooves; there are also methods that are employed for the re-texturing of grooves after the grooved zone wears out. In the literature, the benefits of textured grinding wheels over traditional wheels have been extensively discussed. However, information on the particularities of texturing methods is still lacking. To clarify the advantages, limitations, and main advances regarding each of the groove production methods, the authors of this article carried out a systematic review. The objective of this work is to establish the factors that are affected by groove production methods and the technological advances in this area. The benefits and drawbacks of various grooving techniques are then reviewed, and potential study areas are indicated.This research was funded by FCT national funds, under the national support to R&D
units grant, through the reference projects UIDB/04436/2020, UIDP/04436/2020, UIDB/00690/2020,
UIDP/00690/2020, and SusTEC (LA/P/0007/2020). This work is within the scope of the Sharlane
Costa Ph.D. degree in progress, financially supported by the Portuguese Foundation for Science and
Technology (FCT) through the PhD grant reference 2021.07352.BDinfo:eu-repo/semantics/publishedVersio
Changes in classical kinematics and non‐linear parameters after a maximal 100‐m front‐crawl bout
In a linear system there is proportionality
between input and output. Under this framework it is
expected that the amount of change in sports
performance must be proportional to variations in the
inputs.info:eu-repo/semantics/publishedVersio
Changes in classical kinematics and non-linear parameters after a maximal 100-m front-crawl bout
In a linear system there is proportionality between input and output. Under this framework it is expected that the amount of change in sports performance must be proportional to variations in the inputs. However, as far as elite performance goes, this is not a straightforward assumption. Sometimes the variables selected are not sensitive enough. Hence, there is the need of having non-linear concepts underpinning such analysis. The aim was to compare classical kinematics and non-linear parameters after a maximal 100-m front-crawl bout. Twenty-four subjects (12 males and 12 females; 22.38±1.68-y) were invited to perform a 100-m freestyle race at maximal pace. Before (pre-test, i.e. rested) and immediately after (post-test, i.e. under fatigue) the maximal bout, they performed two maximal 25m swims at freestyle with push-off start. A speedo-meter cord (Swim speedo-meter, Swimsportec, Hildesheim, Germany) was attached to the swimmer’s hip (Barbosa et al., 2015) in the two 25m trials collecting the instantaneous speed. It was computed the speed fluctuation (dv; Barbosa et al., 2015), approximate entropy (ApEn; Barbosa et al., 2015) and fractal dimension (FD; Higuchi, 1988). Repeated measures ANOVAs (pre-test vs. post-test; P≤0.05), effect sizes (eta squared) and 95% of confidence intervals (95CI) were computed. The speed was 1.44±0.24 and 1.28±0.23m/s in the pre- and post/test, respectively (F=55.136, P<0.001)info:eu-repo/semantics/publishedVersio
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