A Simulation of High Latitude F-Layer Instabilities in the Presence of Magnetosphere-Ionosphere Coupling

A magnetic-field-line-integrated model of plasma interchange instabilities is developed for the high latitude ionosphere including magnetospheric coupling effects. We show that primary magnetosphere-ionosphere coupling effect is to incorporate the inertia of the magnetospheric plasma in the analysis. As a specific example, we present the first simulation of the E x B instability in the inertial regime, i.e., nu sub i omega where nu sub i is the ion-neutral collision frequency and omega is the wave frequency. We find that the inertial E x B instability develops in a fundamentally different manner than in the collisional case ni sub i omega. Our results show that striations produced in the inertial regime are spread and retarded by ion inertial effects, and result in more isotropic irregularities than those seen in the collisional case

Factores biomecânicos e bioenergéticos limitativos do rendimento em natação pura desportiva

Um dos objectivos prioritários da Biomecânica do Desporto é o de, num primeiro momento, caracterizar um determinado padrão motor e, num segundo momento, intervir no sentido de incrementar a efi ciência motora. Esse incremento da efi ciência do gesto tem como fi nalidade última permitir que o seu executante aceda a níveis superiores de rendimento desportivo. Do exposto, emerge a ideia que a Biofísica encontrase numa linha fronteira entre a Mecânica Clássica e a Fisiologia. Neste contexto, a Natação Pura Desportiva é uma das modalidades mais profícuas no estudo das implicações bioenergéticas e das repercussões em termos de efi ciência dos diferentes modelos de locomoção. Foi objectivo do presente trabalho efectuar uma revisão do actual “estado da arte” sobre a relação que se estabelece entre o rendimento desportivo, as características bioenergéticas e biomecânicas em Natação Pura Desportiv

Swimming bioenergetics: integrating biomechanical and physiological data into a coherent biophysical model for performance and training

The purpose of the present paper is to synthesise a number of scientific contributions of our research group, into a coherent corpus of knowledge related to swimming biophysics, specially centred on the availability and use of energy in swimming. After an introductory part that intends to underline the relevance of this approach base on the conceptualization of the swimmer, and swimming action itself, as a thermodynamic system and its mechanical output, we will survey a number of studies and respective contributions for a more advanced understanding of swimming performance, that can be transferred into training and enhancement of swimmers’ working capacity. Most of the studies referred were conducted over samples of swimmers of both genders and of different types, from university/participative swimmers to Portuguese elite swimmers, crossing the large population of trained national level swimmers. Those swimmers were studied in the four different competitive swimming strokes, accomplishing progressive protocols based over distances of 200 m. Physiologic parameters like VO2 (and associated ventilatory and respiratory parameters), post exercise capillary blood [La-] peaks, and heart rate, were directly measured. Kinematical parameters were also measured in the different studies, ranging from simple semi-quantitative parameters, like stroke length (SL), and stroke frequency (SF), to more elaborated biomechanical data, like intracyclic speed fluctuations and propulsive segments kinematics. The focus of interest ranged from swimming economy of different strokes and genders (and of different technical alternatives of the same stroke), to the effects over energy cost of intracyclic speed fluctuations. Energetic input determinant factors, like swimming VO2 kinetics, including VO2 slow component, and VO2 time limit, and its determinants, will also be analysed

The influence of stroke mechanics into energy cost of elite swimmers

The purpose of this study was to analyze the relationships between energy cost (C), swimming velocity (v), stroke frequency (SF) and stroke length (SL) in toplevel swimmers. Eighteen elite swimmers (four freestylers, five backstrokers, five breaststrokers and four butterflyers) performed an intermittent set of n 9 200 m swims (n B 8) with increasing velocity. The oxygen consumption was measured breath-by-breath by a portable metabolic cart (K4 b2, Cosmed, Rome, Italy). A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and collect expiratory gases. Blood samples were taken from the ear lobe before and after each swim to analyze the blood lactate concentration (YSI 1500L, Yellow Springs, OH, USA). At Backstroke, Breaststroke and Butterfly strokes, increases of SF were associated to increases of C, even when controlling the v. The increases in SL only promoted significant decreases in the C in Breaststroke. There was a significant and polynomial relationship between v and SF for all competitive swimming techniques. The polynomial relationship between v and SL was significant only in Freestyle and Butterfly stroke. Partial correlations between v and SF controlling the effect of SL and between v and SL controlling the effect of SF, were positive and significant for all techniques. It is concluded that manipulation of stroke mechanics variables (SF and SL) may be one of the factors through which C in competitive swimming can be altered for a given v

Size-selected agglomerates of SnO₂ nanoparticles as gas sensors

The effect of nanoparticle structure on gas sensing performance is investigated. Size-selected nanostructured SnO₂ agglomerate particles for gas sensors were made by scalable flame spray pyrolysis. These particles were polydisperse (up to 12μm in diameter) and consisted of primary particles of 10nm in grain and crystal size as measured by transmission electron microscopy, x-ray diffraction, and Berner low pressure impactor (BLPI). The effect of agglomerate size on thermal stability and sensing of ethanol vapor (4–100ppm) and CO (4–50ppm) was investigated by selecting nearly monodisperse fractions of these agglomerates by the BLPI. Sensor layers made with these size-fractionated agglomerates exhibited higher thermal stability and dramatically enhanced sensitivity for both analytes than layers made with polydisperse agglomerates. This is attributed to their aggregate (or hard agglomerate) structure exhibiting small sinter necks between their constituent primary particles of tin dioxide that had also a narrow size distribution as expected for particles generated in flames. Upon further sintering of these optimally sized, nanostructured agglomerates, grain and neck growth degraded their superior sensitivity, supporting the proposed mechanism of their enhanced sensitivity: optimal primary particle necking.Financial support was provided by ETH Zurich FEL-04 08-3, Finnish Academy, Tekes The Finnish National Technology Agency, and Nanoprim

Estudo piloto da resposta bioenergética a diferentes ritmos respiratórios na técnica de mariposa

Introdução e objectivos: O objectivo do presente trabalho foi o de efectuar um estudo piloto, comparando a resposta bioenergética à adopção de diferentes ritmos respiratórios na técnica de Mariposa. Material e métodos: Foram estudadas duas nadadoras e um nadador de nível nacional (17.0±3.6 anos de idade, 159.0±12.0cm de estatura, 56.9±10.3Kg de massa corporal e 18.0±8.9% de massa gorda). Cada nadador efectuou, numa piscina de 25m, 3 repetições de 200m, a uma velocidade tão próxima quanto possível da máxima. De forma aleatória, em cada repetição, os nadadores realizaram inspirações frontais em todos os ciclo gestuais (1:1F), uma inspiração frontal em cada dois ciclos gestuais (1:2F) e ciclo gestuais inspirando pelo tubo de condução de gases, mas sem a emersão da face (0:0). Avaliaram-se as trocas gasosas e os parâmetros cardiorespiratórios através de um oxímetro breath-by-breath (K4 b2, Cosmed, Itália). Uma válvula de baixa resistência hidrodinâmica encontrava-se ligada ao oxímetro, permitindo a recolha das amostras de gases a analisar (Toussaint et al., 1987; Keskinen et al. 2003). Foram retiradas amostras de sangue capilar da orelha antes, imediatamente após cada 200m e 1, 3, 5 e 7 minutos depois do fim do protocolo, para a avaliação da concentração sérica de lactato (YSI ASPECTOS BIOLÓGICOS DO DESPORTO E DO EXERCÍCIO Revista Portuguesa de Ciências do Desporto, 2004, vol. 4, nº 2 (suplemento) [237–274] 241 1500L, Yellow Springs, EUA). Foi utilizado um cardiofrequencímetro para medição da frequência cardíaca (Vantage NV, POLAR, Finlândia). Foi avaliado o consumo máximo de oxigénio relativo (VO2-max), o consumo líquido de oxigénio (VO2- net=VO2-max-VO2-repouso), a concentração máxima de lactato (La-max), a concentração líquida de lactato (La-net= Lamax- La-repouso), o quociente respiratórios (R), o volume ventilatório (VV) e a frequência cardíaca (FC). Também foram avaliados o dispêndio energético total (Etot) calculado com base no VO2-net e na La-net, transformada em equivalentes de VO2 através da constante de 2.7 ml.kg.-1.mmol-1 (di Prampero et al., 1978) e o custo energético (CE= Etot .velocidade-1). Principais resultados e conclusões: O VO2-max foi 26.0% superior utilizando o ritmo de 1:1F do que o ritmo de 0:0 e 7.25% superior do que o ritmo de 1:2F. O VO2-net foi respectivamente 27.3% e 9.94% superior adoptando o ritmo 1:1F do que os ritmos de 0:0 e de 1:2F. O ritmo que exigiu um menor Etot foi o de 0:0, com menos 19.24% do que o 1:1F e menos 9.44% do que o 1:2F. O CE foi substancialmente superior usando o ritmo de 1:1F do que o ritmo de 0:0, com uma variação média de 23.8%. O VV foi superior usando o 1:1F do que o 1:2F ou o 0:0 em respectivamente, 14.57% e 3.19%. Em conclusão, a adopção de diferentes ritmos respiratórios induzirá alterações na resposta bioenergética ao nadar a técnica de Mariposa. Contudo, sugere-se um estudo com uma amostra mais alargada, procurando aferir se as tendências manifestadas no presente estudo revelam robustez do ponto de vista estatístico. Mesmo assim, parece que a diminuição do número de actos inspiratórios promove uma redução dramática do Etot e do CE. Logo, em contextos competitivos, os mariposistas terão algumas vantagens em reduzir, tanto quant

Bending reliability of screen-printed vias for a flexible energy module

The future of printed electronics involves advancements not only related to full system integration, but also lean process manufacturing. A critical aspect of this progress is developed in this study, which evaluates a highly flexible screen printed through-hole-via using silver microparticle inks, for applications in energy harvesting and storage modules. The printed vias’ fabrication and durability are evaluated by means of a double sided screen-printing method and repetitive (cyclic) bending tests. Vias, through 125-µm-thick PET foil, were laser cut (nominally 50, 100, 150, and 200 µm diameters) then filled, and simultaneously connected to adjacent vias by screen printing. To investigate the use of the printed via in a monolithic energy module, the vias were used for the fabrication of a flexible printed supercapacitor containing aqueous electrolyte and carbon electrodes. The results indicate that the lower viscosity silver ink (DuPont 5064H) fills the via less effectively than the higher viscosity ink (Asahi LS411AW), and as the via size increases (≥150 µm diameter) via walls are coated rather than filled. Conversely, the more viscous ink fills the via thoroughly and exhibited a 100% yield (1010 vias; 100 µm nominal via diameter) with the two-step direct screen-printing method. The 10-mm radius bending test showed no signs of via specific breakdown after 30,000 cycles. The results indicate that this via filling process is likely roll-to-roll compatible to enable multi-layered printed electronic devices.publishedVersionPeer reviewe

Estudo da relação entre o custo energético e a mecânica gestual mariposa

Introdução e objectivos: Foi objectivo do presente estudo identificar a relação entre variáveis bioenergéticas (gasto energético e custo energético) e biomecânicas (parâmetros do ciclo gestual) ao longo de um leque de velocidades na técnica de Mariposa. Material e métodos: Três nadadores e uma nadadora de nível internacional foram submetidos a um protocolo incremental de 200m a Mariposa. A velocidade inicial foi de 1.18 m.s-1 para os nadadores e de 1.03 m.s-1 para a nadadora. A cada 200m a velocidade apresentava um incremento de 0.05.s-1 até o nadador atingir a exaustão. Avaliaram-se as trocas gasosas e os parâmetros cardiorespiratórios através de um oxímetro breathby- breath (K4 b2, Cosmed, Itália). Uma válvula de baixa resistência hidrodinâmica encontrava-se ligada ao oxímetro, permitindo a recolha das amostras de gases a analisar (Toussaint et al., 1987; Keskinen et al. 2003). Foram colhidas amostras de sangue capilar da orelha antes, imediatamente após cada 200m e 1, 3, 5 e 7 minutos depois do fim do protocolo, para a avaliação da concentração sérica de lactato (YSI 1500L, Yellow Springs, EUA). Foi calculado o dispêndio energético total (Etot), o custo energético (CE), a frequência gestual (FG), a distância de ciclo (DC), a velocidade média de deslocamento (V) e o índice de braçada (IB) para cada percurso, e calculado o valor médio para cada patamar de 200m. Foram calculadas rectas de regressão individuais, assim como os respectivos coeficientes de determinação e de correlação entre as variáveis bioenergéticas e as variáveis biomecânicas em estudo (p£ 0.05). Principais resultados e conclusões: Os coeficientes de correlação entre o Etot e a V, entre o CE e a FG e entre o CE e o IB apresentaram significado estatístico em todos os nadadores. Da relação entre o CE e a DC, apenas uma equação de regressão apresentou o coeficiente de correlação com significado estatístico. A relação entre a FG e a V, bem como, a relação entre o IB e a V foram significativas em todos os nadadores. Apenas duas equações de regressão apresentaram coeficientes de correlação significativos entre a V e a DC. Em conclusão, a amostra apresentou uma elevada variação inter-individual na relação entre as variáveis bioenergéticas e as variáveis biomecânicas em estudo, a Mariposa. Assim, sugere-se a análise individual da relação entre a V, a FG e a DC, com o intuito de identificar o ponto de deflexão da DC em função da V. Desta forma, será possível determinar as intensidades de treino adequadas com o objectivo de melhorar o custo energético específico de transporte

Korkeakouluopiskelijoiden mentaaliharjoittelun strategiat pianon- ja kitaransoitossa

Tiivistelmä. Mentaaliharjoittelua käytetään musiikin opetuksessa vain vähän, vaikka esimerkiksi urheilun valmennuksessa mentaaliharjoittelua on hyödynnetty jo pitkään. Kokemuksemme mukaan mentaaliharjoittelulla on merkittävät mahdollisuudet musiikin harjoittelun tukena. Musiikin opetuksessa mentaaliharjoittelu ei ole tullut juurikaan vastaan, vaikka monesti paljon matkustavan muusikon työnkuvaan se sopisi erinomaisesti. Mentaaliharjoittelu mahdollistaisi musiikillisten taitojen opettelun myös kotona, vaikka instrumentteja ei olisikaan käytettävissä. Tutkimuksessamme tarkastelimme mentaaliharjoittelua ja siinä käytettyjä strategioita. Käytimme työssämme eksploratiivista menetelmää ja avointa haastattelua aineistonkeruussa. Tutkittavat soittivat neljä eri kappaletta: kaksi pianolla ja kaksi kitaralla. Molemmilla soittimilla soitettiin kappale harjoitellen perinteisellä tavalla (soittimen kanssa) sekä kappale harjoitellen mentaalisesti (ilman soitinta). Soittotilanteet videoitiin, jonka jälkeen tutkittavat haastateltiin stimulated recall -tyylisesti. Kappaleet sävellettiin tutkimusta varten, jotta ne olisivat tutkittaville entuudestaan tuntemattomia. Aineistomme koostuu soittosuoritusten videomateriaalista sekä avoimen haastattelun litteroidusta tekstistä, joka on analysoitu sisällönanalyysin avulla. Tutkittavat käyttivät mentaaliharjoittelun strategioina musiikillisten taitojen hyödyntämistä sekä yleisten kognitiivisten taitojen hyödyntämistä. Esiin nousseita musiikillisia strategioita olivat esimerkiksi auditiivisuus, kinesteettisyys sekä visualisuus. Yleisiä kognitiivisia taitoja tässä tutkimuksessa ovat esimerkiksi mieleen painaminen ilman musiikillista kontekstia sekä ulkoa opettelu. Harjoittelustrategiat eivät juuri eronneet kitaran ja pianon välillä — tosin pääinstrumenteillaan soittaessaan tutkittavat suoriutuivat tehtävistä paremmin. Verrattaessa mentaaliharjoittelua perinteiseen soittoharjoitteluun harjoittelustrategiat olivat hyvin samankaltaisia, mutta käytetyt musiikilliset strategiat erosivat hieman toisistaan. Tutkimus osoitti, että tutkittavista parhaisiin mentaaliharjoittelun tuloksiin pääsivät he, jotka pystyivät käyttämään harjoittelun strategioina musiikillisia strategioita. Myös he, jotka pystyivät ”niputtamaan” työmuistinsa rajallista kapasiteettia musiikin kokonaisvaltaisen ymmärtämisen avulla, suoriutuivat vahvasti mentaaliharjoittelusta. Heikommin tehtävistä suoriutui, mikäli harjoittelu jäi yleisten kognitiivisten taitojen varaan. Tällöin ajattelua ei liitetty ollenkaan musiikkiin, vaan kappaleet opeteltiin enemmänkin lyhytkestoisen ja pienikapasiteettisen työmuistin rajoissa.Strategies for university students’ mental training in playing the piano and the guitar. Abstract. Mental training is seldom used in teaching music, although it has long been used for instance in sports coaching. Our experience shows that mental training has a significant potential to support music training. In music teaching, mental training has hardly been encountered, even though it would be perfect for musicians who are often travelling. Mental training would also allow learning musical skills at home, even when no instruments are available. In our study, we examined mental training and strategies used in it. Our research used an exploratory method and an open interview in data collection. The subjects played four different musical pieces: two on the piano and two on the guitar. Both instruments were used to play a song that had been practised in the traditional way (with the instrument) and a song that had been practised mentally (without the instrument). The playing situations were recorded on video, and the subjects were interviewed in a stimulated recall style. The musical pieces were composed for the research, so they were unknown to the subjects. Our material consists of the video material of the playing performances and the transcript of the open interview, which has been analysed using content analysis. The subjects used exploitation of musical skills and exploitation of general cognitive skills as strategies for mental training. The musical skills that emerged were, for example, audacity, kinesthetics, and visualization. Common cognitive skills in this study included for example memorizing without musical context and committing to memory. Training strategies did not differ to any great extent between the guitar and the piano — although the subjects performed better when playing their main instrument. Training strategies were very similar when mental training was compared to traditional practice, but the musical strategies used differed slightly. The study showed that the subjects who obtained the best results from mental training were those who were able to use musical strategies as training strategies. Also, those subjects performed strongly on mental training who were able to “bundle” the limited capacity of their working memory through comprehensive understanding of music. Weaker performance was observed by those who used just general cognitive skills for training. In this case, thinking was not connected to music at all, instead the songs were learned more within the limits of short-term and low-capacity working memory