980 resultados para Exponential function
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Foraminiferal data were obtained from 66 samples of box cores on the southeastern Brazilian upper margin (between 23.8A degrees-25.9A degrees S and 42.8A degrees-46.13A degrees W) to evaluate the benthic foraminiferal fauna distribution and its relation to some selected abiotic parameters. We focused on areas with different primary production regimes on the southern Brazilian margin, which is generally considered as an oligotrophic region. The total density (D), richness (R), mean diversity (H) over bar`, average living depth (ALD(X) ) and percentages of specimens of different microhabitats (epifauna, shallow infauna, intermediate infauna and deep infauna) were analyzed. The dominant species identified were Uvigerina spp., Globocassidulina subglobosa, Bulimina marginata, Adercotryma wrighti, Islandiella norcrossi, Rhizammina spp. and Brizalina sp.. We also established a set of mathematical functions for analyzing the vertical foraminiferal distribution patterns, providing a quantitative tool that allows correlating the microfaunal density distributions with abiotic factors. In general, the cores that fit with pure exponential decaying functions were related to the oligotrophic conditions prevalent on the Brazilian margin and to the flow of the Brazilian Current (BC). Different foraminiferal responses were identified in cores located in higher productivity zones, such as the northern and the southern region of the study area, where high percentages of infauna were encountered in these cores, and the functions used to fit these profiles differ appreciably from a pure exponential function, as a response of the significant living fauna in deeper layers of the sediment. One of the main factors supporting the different foraminiferal assemblage responses may be related to the differences in primary productivity of the water column and, consequently, in the estimated carbon flux to the sea floor. Nevertheless, also bottom water velocities, substrate type and water depth need to be considered.
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The synthesis, characterization and formation of Langmuir-Blodgett (LB)films for the luminescent [(C12H25)(2)(CH3)(2)N][Eu(tta)(4)] complex, where [(C12H25)(2)(CH3)(2)](N+) is didodecyldimethylammonium and the tta ligand is thenoyltrifluoroacetone, are reported. The coordination of tta ligands to the Eu3+ ion was confirmed by FTIR spectroscopy and the emission spectrum comprised bands corresponding to D-5(0) -> F-7(0-4) transitions. The lifetime (tau) from the emission state (D-5(0))was 0.41 ms, measured by monitoring the hypersensitive D-5(0) -> F-7(2) transition, with the curve being fitted with a first-order exponential function. The surface pressure-area isotherm indicated that the anionic complex may form condensed structures at the air-water interface due to the amphiphilic properties of the counter ion and the beta-diketone ligand. Y-type LB films of [(C12H25)(2)(CH3)(2)N][Eu(tta)(4)] were deposited on quartz substrates, with preserved luminescence and a band assigned to the D-5(0) -> F-7(2) transition. The molecular arrangement at the air/water interface and the preserved luminescence in LB films are consistent with theoretical predictions using a semi-empirical Sparkle/AM1 calculation method for the molecule in vacuum. These tools were used for the first time to predict the behavior of organized films.
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Motorische Bewegungen werden über die visuelle Rückmeldung auf ihre Genauigkeit kontrolliert und ggf. korrigiert. Über einen technischen Eingriff, wie beispielsweise einer Prismenbrille, kann man eine Differenz zwischen optisch wahrgenommener und haptisch erlebter Umwelt erzeugen, um die Fähigkeiten des visuomotorischen Systems zu testen. In dieser Arbeit wurde eine computergestützte Methode entwickelt, eine solche visuomotorische Differenz zu simulieren. Die Versuchspersonen führen eine ballistische Bewegung mit Arm und Hand aus in der Absicht, ein vorgegebenes Ziel zu treffen. Die Trefferpunkte werden durch einen Computer mit Hilfe eines Digitalisierungstablettes aufgenommen. Die visuelle Umwelt, welche den Versuchspersonen präsentiert wird, ist auf einem Monitor dargestellt. Das Monitorabbild – ein Kreuz auf weißem Hintergrund – betrachten die Testpersonen über einen Spiegel. Dieser ist in einem entsprechenden Winkel zwischen Monitor und Digitalisierungstablett angebracht, so dass das Zielbild auf dem Digitalisierungstablett projiziert wird. Die Testpersonen nehmen das Zielkreuz auf dem Digitalisierungstablett liegend wahr. Führt die Versuchsperson eine Zielbewegung aus, können die aufgenommenen Koordinaten als Punkte auf dem Monitor dargestellt werden und die Testperson erhält über diese Punktanzeige ein visuelles Feedback ihrer Bewegung. Der Arbeitsbereich des Digitalisierungstabletts kann über den Computer eingerichtet und so motorische Verschiebungen simuliert werden. Die verschiedenartigen Möglichkeiten dieses Aufbaus wurden zum Teil in Vorversuchen getestet um Fragestellungen, Methodik und technische Einrichtungen aufeinander abzustimmen. Den Hauptversuchen galt besonderes Interesse an der zeitlichen Verzögerung des visuellen Feedbacks sowie dem intermanuellen Transfer. Hierbei ergaben sich folgende Ergebnisse: ● Die Versuchspersonen adaptieren an eine räumlich verschobene Umwelt. Der Adaptationsverlauf lässt sich mit einer Exponentialfunktion mathematisch berechnen und darstellen. ● Dieser Verlauf ist unabhängig von der Art des visuellen Feedbacks. Die Beobachtung der Handbewegung während der Adaptation zeigt die gleiche Zielabfolge wie eine einfache Punktprojektion, die den Trefferort der Bewegung darstellt. ● Der exponentielle Verlauf der Adaptationsbewegung ist unabhängig von den getesteten zeitlichen Verzögerungen des visuellen Feedbacks. ● Die Ergebnisse des Folgeeffektes zeigen, dass bei zunehmender zeitlicher Verzögerung des visuellen Feedbacks während der Adaptationsphase, die Größe des Folgeeffektwertes geringer wird, d.h. die anhaltende Anpassungsleistung an eine visuomotorische Differenz sinkt. ● Die Folgeeffekte weisen individuelle Eigenheiten auf. Die Testpersonen adaptieren verschieden stark an eine simulierte Verschiebung. Ein Vergleich mit den visuomotorischen Herausforderungen im Vorleben der Versuchspersonen ließ vermuten, dass das visuomotorische System des Menschen trainierbar ist und sich - je nach Trainingszustand – unterschiedlich an wahrgenommene Differenzen anpasst. ● Der intermanuelle Transfer konnte unter verschiedenen Bedingungen nachgewiesen werden. ● Ein deutlich stärkerer Folgeeffekt kann beobachtet werden, wenn die wahrgenommene visuomotorische Differenz zwischen Ziel und Trefferpunkt in eine Gehirnhälfte projiziert wird und der Folgeeffekt mit der Hand erfolgt, welche von dieser Hirnhemisphäre gesteuert wird. Der intermanuelle Transfer wird demnach begünstigt, wenn die visuelle Projektion der Fehlerbeobachtung in die Gehirnhälfte erfolgt, die während der Adaptationsphase motorisch passiv ist.
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Grundlage für die hier gezeigte Arbeit stellt die Eigenschaft von amphiphilen Blockcopolymeren dar immer den Block mit der niedrigsten Grenzflächenenergie zum angrenzenden Medium an die Oberfläche zu bringen. Durch einen Austausch des Mediums an der Grenzfläche zum Blockcopolymer kann eine Reorientierung erzwungen werden, wenn die Grenzflächenenergie des anderen Blocks nun die niedrigere Grenzflächenenergie besitzt. Dieses Verhalten von dünnen amphiphilen Blockcopolymerfilmen wurde zur Strukturierung von Oberflächen ausgenutzt und in nachfolgenden Synthesen weiter verstärkt. Um dies zu erreichen wurde das zur Strukturierung erforderliche Poly(4-Octylstyrol)block(4-hydroxystyrol) durch kontrollierte radikalische Polymerisationsmethode mit dem Tempo Unimer (2,2,6,6-Tetramethyl-1-1(1-phenyl-ethoxy)-piperidin) synthetisiert. Für die geplanten Reorientierungen und Modifizierungen von Oberflächen wurden dünne Filme durch Schleuderbeschichtung auf verschiedenen Substraten (Siliziumwafern, Glassubstraten und Goldoberflächen) hergestellt. Das Verhalten der Oberflächen von diesen Filmen wurde durch Kontaktwinkelmessungen untersucht. Auf diese Weise konnte gezeigt werden, dass die Oberfläche von Polymerfilmen nach der Präparation aus dem hydrophoben Block des Polymers gebildet wird. Durch Kontakt des Polymerfilms mit Wasser kann dieser zur Reorientierung gebracht werden, so dass der hydrophile Block des Polymers an der Oberfläche erscheint. Dieses Verhalten wurde zur Strukturierung mit softlithographischen Techniken genutzt. Dazu wurden hydrophil/hydrophob strukturierte Oberflächen durch Aufsetzen von hydrophoben PDMS-Stempeln, die Teile der Oberfläche selektiv abdeckten, und Einbringen von Wasser in die dabei entstehenden Kapillaren hergestellt. Dies ermöglichte es die Oberfläche selektiv im Größenbereich von 500nm bis zu 50µm zu strukturieren und an den reaktiven Bereichen Materialien, wie z.B. Kupfer, Titandioxid, Polyelektrolyte, photonische Kristalle und angegraftete Polymere, mit verschiedenen Methoden selektiv auf die Oberfläche aufzubringen. Um den Reorganisationsprozess der Oberfläche genauer zu studieren, wurde ein für diese Aufgabe besser geeignetes Polymer (Poly(Styrol)-block-poly(essigsäure-2-(2-(4-vinyl-phenoxy)-ethoxy)ethylester)) synthetisiert. Aus diesem Blockcopolymer wurden wieder dünne Filme durch Spincoaten hergestellt. Die Reorientierung dieses Polymers in 70°C warmen Wasser konnte durch Kontaktwinkelmessungen und NEXAFS Spektroskopie nachgewiesen werden. Mit Hilfe der NEXAFS Spektroskopie konnte festgestellt werden, dass die Geschwindigkeit der Reorientierung durch eine exponentielle Funktion beschrieben werden kann. Eine Auswertung der Geschwindigkeitskonstante für die Reorientierung einer hydrophilen zu einer hydrophoben Oberfläche des Polymers bei 60°C führt zu =75min. Aufgrund des exponentiellen Charakters der Reorientierung macht es den Anschein, dass die Reorientierung bei verschiedenen Reorientierungstemperaturen bis zu einem gewissen Grad erfolgt und dann stoppt. Eine weitere Reorientierung scheint erst wieder bei einer Temperaturerhöhung zu beginnen. Aus AFM Messungen ist ein Beginnen der Reorientierung durch Bildung kleiner Löcher in der Polymeroberfläche zu erkennen, die sich zu runden Erhöhungen und Vertiefungen vergrößern, um letztendlich in ein spinodales Entmischungsmuster über zu gehen. Dieses heilt dann im Laufe der Zeit langsam durch Verschwinden der hydrophilen Bereiche langsam aus. Der Beginn des zuvor beschriebenen Reorientierungsprozesses einer hydrophilen Oberfläche in eine hydrophobe konnte sowohl in den AFM, als auch in den NEXAFS-Messungen zu ca. 50°C bestimmt werden.
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BACKGROUND Understanding the composition and dynamics of the upper respiratory tract microbiota in healthy infants is a prerequisite to investigate the role of the microbiota in patients with respiratory diseases. This is especially true in early life, when the immune system is in development. OBJECTIVE We sought to describe the dynamics of the upper respiratory tract microbiota in healthy infants within the first year of life. METHODS After exclusion of low-quality samples, microbiota characterization was performed by using 16S rDNA pyrosequencing of 872 nasal swabs collected biweekly from 47 unselected infants. RESULTS Bacterial density increased and diversity decreased within the first year of life (R(2) = 0.95 and 0.73, respectively). A distinct profile for the first 3 months of life was found with increased relative abundances of Staphlyococcaceae and Corynebacteriaceae (exponential decay: R(2) = 0.94 and 0.96, respectively). In addition, relative bacterial abundance and composition differed significantly from summer to winter months. The individual composition of the microbiota changed with increasing time intervals between samples and was best modeled by an exponential function (R(2) = 0.97). Within-subject dissimilarity in a 2-week time interval was consistently lower than that between subjects, indicating a personalized microbiota. CONCLUSION This study reveals age and seasonality as major factors driving the composition of the nasal microbiota within the first year of life. A subject's microbiota is personalized but dynamic throughout the first year. These data are indispensable to interpretation of cross-sectional studies and investigation of the role of the microbiota in both healthy subjects and patients with respiratory diseases. They might also serve as a baseline for future intervention studies.
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High-energy e(-) and pi(-) were measured by the multichannel plate (MCP) detector at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute, Villigen, Switzerland. The measurements provide the absolute detection efficiencies for these particles: 5.8% +/- 0.5% for electrons in the beam momenta range 17.5-300 MeV/c and 6.0% +/- 1.3% for pions in the beam momenta range 172-345 MeV/c. The pulse height distribution determined from the measurements is close to an exponential function with negative exponent, indicating that the particles penetrated the MCP material before producing the signal somewhere inside the channel. Low charge extraction and nominal gains of the MCP detector observed in this study are consistent with the proposed mechanism of the signal formation by penetrating radiation. A very similar MCP ion detector will be used in the Neutral Ion Mass (NIM) spectrometer designed for the JUICE mission of European Space Agency (ESA) to the Jupiter system, to perform measurements of the chemical composition of the Galilean moon exospheres. The detection efficiency for penetrating radiation determined in the present studies is important for the optimisation of the radiation shielding of the NIM detector against the high-rate and high-energy electrons trapped in Jupiter's magnetic field. Furthermore, the current studies indicate that MCP detectors can be useful to measure high-energy particle beams at high temporal resolution. (C) 2015 AIP Publishing LLC.
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Mesoscale iron enrichment experiments have revealed that additional iron affects the phytoplankton productivity and carbon cycle. However, the role of initial size of fertilized patch in determining the patch evolution is poorly quantified due to the limited observational capability and complex of physical processes. Using a three-dimensional ocean circulation model, we simulated different sizes of inert tracer patches that were only regulated by physical circulation and diffusion. Model results showed that during the first few days since release of inert tracer, the calculated dilution rate was found to be a linear function with time, which was sensitive to the initial patch size with steeper slope for smaller size patch. After the initial phase of rapid decay, the relationship between dilution rate and time became an exponential function, which was also size dependent. Therefore, larger initial size patches can usually last longer and ultimately affect biogeochemical processes much stronger than smaller patches.
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The jumbo flying squid, Dosidicus gigas, support an important squid fishery off the Exclusive Economic Zone of Chilean waters. However, we only have limited information about their biology. In this study, age, growth and population structure of D. gigas were studied using statoliths from 333 specimens (386 females and 147 males) randomly sampled in the Chinese squid jigging surveys from 2007 to 2008 off the Exclusive Economic Zone of Chile. Mantle lengths (MLs) of the sample ranged from 206 to 702 mm, and their ages were estimated from 150 to 307 days for females and from 127 to 302 days for males. At least two spawning groups were identified, the main spawning peak tended to occur between August and November (austral spring group), and the secondary peak appeared during March to June (austral autumn group). The ML-age relationship was best modelled by a linear function for the austral spring group and a power function for the austral autumn group, and the body weight (BW)-age relationship was best described by an exponential function for both the groups. Instantaneous relative growth rates and absolute growth rates for ML and BW did not differ significantly between the two groups. The growth rate of D. gigas tended to be high at young stages, and then decreased after the sub-adult stage (>180 days old). This study suggests large spatial and temporal variability in key life history parameters of D. gigas, calling for the collection of more data with fine spatial and temporal scales to further improve our understanding of the fishery biology of D. gigas.
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The datasets present measurements of cDOM absorption of lakes located in Antarctic oasis during the summer periods from 2013 to 2016. In summer season of 2013 water samples were collected on Fildes Peninsula (King George Island, West Antarctica) - Bellingshausen Station, Russia. Investigated lakes on Fides Peninsula were completely or partly free from ice cover during water sampling. In summer seasons of 2014-2016 water samples were collected on Vestfold Hills, Reuer Island and Larsemann Hills Oasis (East Antarctica) - Progress station, Russia. During 2014-2016 summer season part of lakes on Larsemann Hills Oasis were free from ice cover, some of the lakes were completely covered by ice and were drilled before sampling. Part of the water samples from Progress Station (2015) has not been filtered. cDOM is operationally defined by the chosen filter pore size. Samples have been consistently filtrated through 0.7 µm pore size glas fibre filters. cDOM filtrates have been stored in darkness and have been measured after the expedition using the dual-beam Specord200 laboratory spectrometer (Jena Analytik) at the Otto Schmidt Laboratory OSL, Arctic and Antarctic Research Institute, St. Petersburg, Russia. The OSL cDOM protocol (Heim and Roessler, 2016) prescribes 3 Absorbance (A) measurements per sample from UV to 750 nm against ultra-pure water. The absorption coefficient, a, is calculated by a = 2.303A/L, where L is the pathlength of the cuvette [m], and the factor 2.303 converts log10 to loge. The output of the calculation is a continuous spectrum of a. The cDOM a spectra are used to determine the exponential slope value for specific wavelength ranges, S by fitting the data between min and max wavelength to an exponential function. We provide cDOM absorption coefficients for the wavelengths 254, 260, 350, 375, 400, 412, 440, 443 nm [1/m] and Slope values for three different UV, VIS, wavelength ranges: 275 to 295 nm, 350 to 400 nm, 300 to 500 nm [1/nm]. All data were carried out by scientists from Arctic and Antarctic Research Institute and Saint Petersburg State University of Russia during Russian Antarctic Expedition in 2013-2016.
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The datasets present measurements of cDOM absorption in lakes, rivers and streams of Yamal and Gydan Peninsula area during the summer periods from 2012-2014 and 2016. In summer seasons of 2012 - 2013 water samples was collected during "Yamal-Arctic" Expedition. All of the research areas were located near the coastline of Yamal, Yavay, and Gydan Peninsula and Bely Island. In 2012 water samples from rivers, lakes and streams were taken near New Port, Cape Kamenny and Tambey settlements and in basins (water catchments) of the Sabetta, Seyakha, Yuribey (Baydaratskaya Bay, Gydan Peninsula) and Mongocheyakha rivers. In 2013 water samples from rivers, lakes and streams were taken in the Yavai Peninsula, Yayne Vong bay and in the basins (water catchments) of the Sabetta, Mongocheyakha and Yuribey (Gydan Peninsula) rivers. In 2014 lakes were sampled in the Erkuta River basin, south of Yamal Peninsula. In 2016 lakes and rivers were sampled it the Erkuta River basin and Polar Ural area. cDOM is operationally defined by the chosen filter pore size. Samples have been consistently filtrated through 0.7 µm pore size glas fibre filters. cDOM filtrates have been stored in darkness and have been measured after the expedition using the dual-beam Specord200 laboratory spectrometer (Jena Analytik) at the Otto Schmidt Laboratory OSL, Arctic and Antarctic Research Institute, St. Petersburg, Russia. The OSL cDOM protocol (Heim and Roessler, 2016) prescribes 3 Absorbance (A) measurements per sample from UV to 750 nm against ultra-pure water. The absorption coefficient, a, is calculated by a = 2.303A/L, where L is the pathlength of the cuvette [m], and the factor 2.303 converts log10 to loge. The output of the calculation is a continuous spectrum of a. The cDOM a spectra are used to determine the exponential slope value for specific wavelength ranges, S by fitting the data between min and max wavelength to an exponential function. We provide cDOM absorption coefficients for the wavelengths 254, 260, 350, 375, 400, 412, 440, 443 nm [1/m] and Slope values for three different UV, VIS, wavelength ranges: 275 to 295 nm, 350 to 400 nm, 300 to 500 nm [1/m]. All data were carried out by scientists from Arctic and Antarctic Research Institute and Saint Petersburg State University of Russia during "Yamal-Arctic" expeditions in 2012-2013, RFBR project No 14-04-10065 in 2014, No 14-05-00787 in 2016.
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The extent to which new technological knowledge flows across institutional and national boundaries is a question of great importance for public policy and the modeling of economic growth. In this paper we develop a model of the process generating subsequent citations to patents as a lens for viewing knowledge diffusion. We find that the probability of patent citation over time after a patent is granted fits well to a double-exponential function that can be interpreted as the mixture of diffusion and obsolescense functions. The results indicate that diffusion is geographically localized. Controlling for other factors, within-country citations are more numerous and come more quickly than those that cross country boundaries.
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We demonstrate here that the growth increment variability in the shell of the long-lived bivalve mollusc Arctica islandica can be interpreted as an indicator of marine environmental change in the climatically important North Atlantic shelf seas. Multi-centennial (up to 489-year) chronologies were constructed using five detrending techniques and their characteristics compared. The strength of the common environmental signal expressed in the chronologies was found to be fully comparable with equivalent statistics for tree-ring chronologies. The negative exponential function using truncated increment-width series from which the first thirty years have been removed was chosen as the optimal detrending technique. Chronology indices were compared with the Central England Temperature record and with seawater temperature records from stations close to the study site in the Irish Sea. Statistically significant correlations were found between the chronology indices and (a) mean air temperature for the 14-month period beginning in the January preceding the year of growth, (b) mean seawater temperatures for February-October in the year preceding the year of growth (c) late summer and autumn air temperatures and sea surface temperatures for the year of growth and (d) the timing of the autumn decline in SST. Changes through time in the correlations with air and seawater temperatures and changes towards a deeper water origin for the shells in the chronology were interpreted as an indication that shell growth may respond to stratification dynamics.