Ethylene Emission in the Aftermath of Saturn’s 2010 Northern Storm

NASA Astrophysics Data System (ADS)

Hesman, Brigette E.; Bjoraker, G. L.; Sada, P. V.; Achterberg, R. K.; Jennings, D. E.; Lunsford, A. W.; Romani, P. N.; Fletcher, L. N.; Boyle, R. J.; Kerr, T.; Sinclair, J. A.; Nixon, C. A.; Davis, G. R.; Irwin, P. G. J.

2012-10-01

The massive eruption at 40N (planetographic latitude) in December 2010 has produced significant and long-lived changes in temperature and species abundances in Saturn’s northern hemisphere (Fletcher et al. 2011). The northern storm region has been observed on many occasions between January 2011 and June of 2012 by Cassini’s Composite Infrared Spectrometer (CIRS). In this time period, temperatures in regions referred to as “beacons” (warm regions in the stratosphere at certain longitudes in the storm latitude) became significantly warmer than pre-storm values of 140K. A significant finding in the beacon region has been ethylene emission; a molecule that has been challenging to detect on Saturn but is an important species in Saturn’s photochemistry. The derived ethylene profile from the CIRS data gives a C2H4 mole fraction of 5.9 ± 4.5x10-7 at 0.5 mbar. Ground-based observations were performed using the high-resolution spectrometer Celeste to study ethylene’s spectral signatures at higher spectral resolution than available with CIRS. Analysis of the May 2011 Celeste data finds a C2H4 mole fraction of 2.7 ± 0.45x10-6 at 0.1 mbar. The ethylene abundances derived from CIRS and Celeste observations are two orders of magnitude higher than predicted by photochemical models, indicating that perhaps another production mechanism is required or a loss mechanism is being inhibited. To investigate the source of ethylene in the beacon region the temporal evolution of this molecule will be presented based on data collected by CIRS, between January 2011 and June 2012, together with ground-based Celeste observations from the McMath-Pierce Telescope (May 2011), the United Kingdom Infrared Telescope (July 2011), and the NASA Infrared Telescope Facility (April 2012). References: Fletcher, L. N. et al., 2011. Thermal Structure and Dynamics of Saturn’s Northern Springtime Disturbance. Science 332, 1413-1417.

Basic Color Terms (BCTs) and Categories (BCCs) in Three Dialects of the Spanish Language: Interaction Between Cultural and Universal Factors.

PubMed

Lillo, Julio; González-Perilli, Fernando; Prado-León, Lilia; Melnikova, Anna; Álvaro, Leticia; Collado, José A; Moreira, Humberto

2018-01-01

Two experiments were performed to identify and compare the Basic Color Terms (BCTs) and the Basic Color Categories (BCCs) included in three dialects (Castilian, Mexican, and Uruguayan) of the Spanish language. Monolexemic Elicited lists were used in the first experiment to identify the BCTs of each dialect. Eleven BCTs appeared for the Spanish and the Mexican, and twelve did so for the Uruguayan. The six primary BCTs ( rojo "red," verde "green," amarillo "yellow," azul "blue," negro "black," and blanco "white") appeared in the three dialects. This occurred for only three derived BCTs ( gris "gray," naranja "orange," and rosa "pink") but not for the other five derived BCTs ( celeste "sky blue," marrón "brown," café "brown," morado "purple," and violeta "purple"). Color transitions were used in the second experiment for two different tasks. Extremes naming task was used to determine the relation between two different dialects' BCTs: equality, equivalence or difference. The results provided the first evidence for marrón "brown" and café "brown" being equivalent terms for the same BCC (brown in English) as is the case of morado "purple" and violeta "purple." Uruguayan celeste "sky blue" had no equivalent BCT in the other two dialects. Boundary delimitation task required the selection of the color in the boundary between two categories. The task was used to reasonably estimate the volume occupied by each BCC in the color space considering its chromatic area and lightness range. Excluding sky blue ( celeste "sky blue") and blue ( azul "blue"), the other BCCs color volumes were similar across the three dialects. Uruguayan sky blue and blue volumes conjointly occupied the portion of the color space corresponding to the Castilian and Mexican blue BCC. The fact that the BCT celeste "sky blue" only appeared in Uruguayan very probably derived from specific cultural factors (the use of the color in the flags and the arrival of an important number of Italian immigrants

Basic Color Terms (BCTs) and Categories (BCCs) in Three Dialects of the Spanish Language: Interaction Between Cultural and Universal Factors

PubMed Central

Lillo, Julio; González-Perilli, Fernando; Prado-León, Lilia; Melnikova, Anna; Álvaro, Leticia; Collado, José A.; Moreira, Humberto

2018-01-01

Two experiments were performed to identify and compare the Basic Color Terms (BCTs) and the Basic Color Categories (BCCs) included in three dialects (Castilian, Mexican, and Uruguayan) of the Spanish language. Monolexemic Elicited lists were used in the first experiment to identify the BCTs of each dialect. Eleven BCTs appeared for the Spanish and the Mexican, and twelve did so for the Uruguayan. The six primary BCTs (rojo “red,” verde “green,” amarillo “yellow,” azul “blue,” negro “black,” and blanco “white”) appeared in the three dialects. This occurred for only three derived BCTs (gris “gray,” naranja “orange,” and rosa “pink”) but not for the other five derived BCTs (celeste “sky blue,” marrón “brown,” café “brown,” morado “purple,” and violeta “purple”). Color transitions were used in the second experiment for two different tasks. Extremes naming task was used to determine the relation between two different dialects' BCTs: equality, equivalence or difference. The results provided the first evidence for marrón “brown” and café “brown” being equivalent terms for the same BCC (brown in English) as is the case of morado “purple” and violeta “purple.” Uruguayan celeste “sky blue” had no equivalent BCT in the other two dialects. Boundary delimitation task required the selection of the color in the boundary between two categories. The task was used to reasonably estimate the volume occupied by each BCC in the color space considering its chromatic area and lightness range. Excluding sky blue (celeste “sky blue”) and blue (azul “blue”), the other BCCs color volumes were similar across the three dialects. Uruguayan sky blue and blue volumes conjointly occupied the portion of the color space corresponding to the Castilian and Mexican blue BCC. The fact that the BCT celeste “sky blue” only appeared in Uruguayan very probably derived from specific cultural factors (the use of the

Hands-On Science Mysteries for Grades 3-6: Standards-Based Inquiry Investigations

ERIC Educational Resources Information Center

Taris, James Robert; Taris, Louis James

2006-01-01

In "Hands-On Science Mysteries for Grades 3-6," the authors connect science to real-world situations by investigating actual mysteries and phenomena, such as the strange heads on Easter Island, the ghost ship "Mary Celeste," and the "Dancing Stones" of Death Valley. The labs are designed to encourage the development…

Ohio State University Symposium (45th) on Molecular Spectroscopy Held in Columbus, Ohio on 11-15 Jun 1990

DTIC Science & Technology

1990-06-15

Atmospheric Administration, Boulder, CO 80303. Address of Ortigoso and Escribano: Instituto de Estructura de al Materia, Consejo Superior de investigaciones ...10 min.(1:42) J. M. GUILMOT anO M. HERMAN, Laboratoire de Chimie Physique Moleculaire, tjniversit’c Libre de ...CANY-PEYRET, Laboratoire de Physique Mole’*u’ai:e et Atmospherique, Universite Pierre et Marie Curie et CNRS, 75252 Paris, France. MF4. FIR LASER STARK

National Association for Physical Education in Higher Education Annual Conference Proceedings (San Diego, CA, January 8-10, 1982). Volume III.

ERIC Educational Resources Information Center

Gedvilas, Leo L., Ed.; And Others

This book contains 26 papers delivered at the National Association for Physical Education in Higher Education (NAPEHE) Annual Conference (1982). Section 1, "NAPEHE's Image," contains two papers, one by Don Hellison, the other by Celeste Ulrich. "The Splintering of Physical Education" is the topic of the next section, and it contains papers by…

Secondary resonances and the boundary of effective stability of Trojan motions

NASA Astrophysics Data System (ADS)

Páez, Rocío Isabel; Efthymiopoulos, Christos

2018-02-01

One of the most interesting features in the libration domain of co-orbital motions is the existence of secondary resonances. For some combinations of physical parameters, these resonances occupy a large fraction of the domain of stability and rule the dynamics within the stable tadpole region. In this work, we present an application of a recently introduced `basic Hamiltonian model' H_b for Trojan dynamics (Páez and Efthymiopoulos in Celest Mech Dyn Astron 121(2):139, 2015; Páez et al. in Celest Mech Dyn Astron 126:519, 2016): we show that the inner border of the secondary resonance of lowermost order, as defined by H_b, provides a good estimation of the region in phase space for which the orbits remain regular regardless of the orbital parameters of the system. The computation of this boundary is straightforward by combining a resonant normal form calculation in conjunction with an `asymmetric expansion' of the Hamiltonian around the libration points, which speeds up convergence. Applications to the determination of the effective stability domain for exoplanetary Trojans (planet-sized objects or asteroids) which may accompany giant exoplanets are discussed.

Identification and Validation of Established and Novel Biomarkers for Infections in Burns

DTIC Science & Technology

2016-10-01

INVESTIGATOR: Celeste C. Finnerty, PhD RECIPIENT: The University of Texas Medical Branch at Galveston Galveston, TX 77555 REPORT DATE: October 2016...TYPE OF REPORT: Annual PREPARED FOR: U.S. Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT...Boulevard Galveston, TX 77555-5302 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) U.S. Army Medical

The Vietnam Cauldron: Defense Intelligence in the War for Southeast Asia

DTIC Science & Technology

2012-01-01

For the Patriots. Major Robert P. Perry, USA Celeste M. Brown Vivienne A. Clark Dorothy M. Curtiss Joan K. Pray Doris J. Watkins Colonel Charles R. Ray...USA Chief Warrant Officer Robert W. Prescott, USA Chief Warrant Officer Kenneth D. Welch, USA Petty Officer First Class Michael R. Wagner, USN...Marshall Karl W. Teepe Patricia E. Mickley Robert J. Hymel Rosa M. Chapa Sandra N. Foster Charles E. Sabin i Defense Intelligence Historical Perspectives

Blazar Astronomy above 50 GeV

NASA Astrophysics Data System (ADS)

Smith, D. A.

This contribution is dedicated to the memory of Chaman L. Bhat, an atmospheric Cherenkov pioneer and a leader of the Indian gamma-ray community, who died in a road accident on Mt. Abu on December 17, just after the workshop. While few blazars have been detected beyond EGRET energies, these extreme cases may be the ones that 'make or break' some models describing blazars in particular, and therefore AGNs in general. This paper first reviews the status of the various atmospheric Cherenkov gamma-ray telescopes. We then describe the most recent results from these instruments, paying particular attention to the recent detection of 1ES 1426+428 by the Whipple, CAT, and HEGRA imagers. We illustrate the dilemma of target selection using the example of W Com. We then discuss the consequences of the first measurements of Mrk 421 below 100 GeV by the solar heliostat arrays CELESTE and STACEE. This first foray into the energy range linking EGRET with the current imagers requires us to start using functional forms for the spectral energy distributions that are more physical than the simple power laws (or parabolas) used up to now to describe the imager or satellite results. We can hope that HESS, followed by MAGIC and VERITAS, as well as CELESTE and STACEE, will make this a recurring problem in 2002 and 2003.

Elusive Ethylene Detected in Saturns Northern Storm Region

NASA Technical Reports Server (NTRS)

Hesman, B. E.; Bjoraker, G. L.; Sada, P. V.; Achterberg, R. K.; Jennings, D. E.; Romani, P. N.; Lunsford, A. W.; Fletcher, L. N.; Boyle, R. J.; Simon-Miller, A. A.;

Methane fluxes from tropical coastal lagoons surrounded by mangroves, Yucatán, Mexico

NASA Astrophysics Data System (ADS)

Chuang, P.-C.; Young, M. B.; Dale, A. W.; Miller, L. G.; Herrera-Silveira, J. A.; Paytan, A.

2017-05-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m-2 d-1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Methane fluxes from tropical coastal lagoons surrounded bymangroves, Yucatán, Mexico

USGS Publications Warehouse

Chuang, Pei-Chuan; Young, Megan B.; Dale, Andrew W.; Miller, Laurence G.; Herrera-Silveira, Jorge A; Paytan, Adina

2017-01-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m−2 d−1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Metazoan parasites of fishes from the Celestun coastal lagoon, Yucatan, Mexico.

PubMed

Sosa-Medina, Trinidad; Vidal-Martínez, Víctor M; Aguirre-Macedo, M Leopoldina

2015-08-31

The aims of this study were to produce a checklist of the metazoan parasites of fishes from the Celestun coastal lagoon and to determine the degree of faunal similarity among the fishes based on the metazoan parasites they share. A checklist was prepared including all available records (1996-2014) of parasites of marine, brackish water and freshwater fishes of the area. All of these data were included in a presence/absence database and used to determine similarity via Jaccard's index. The results indicate the presence of 62 metazoan parasite species infecting 22 fish species. The number of metazoan parasite species found in the fishes from the Celestún lagoon is apparently the highest reported worldwide for a tropical coastal lagoon. The parasites included 12 species of adult digeneans, 27 digeneans in the metacercarial stage, 6 monogeneans, 3 metacestodes, 9 nematodes, 2 acanthocephalans, 2 crustaceans and 1 annelid. Forty parasite species were autogenic and 23 were allogenic and 1 unknown. The overall similarity among all of the species of fish with respect to the metazoan parasites they share was low (0.08 ± 0.12), with few similarity values above 0.4 being obtained. This low similarity was due primarily to the presence of suites of parasites exclusive to specific species of fish. The autogenic component of the parasite fauna (40 species) dominated the allogenic component (21 species). The most likely explanation for the large number of fish parasites found at Celestún is the good environmental condition of the lagoon, which allows the completion of parasite life cycles and free circulation of euryhaline fishes from the marine environment bringing marine parasites into the lagoon.

GEISA-97 spectroscopic database system related information resources: current status and perspectives

NASA Astrophysics Data System (ADS)

Chursin, Alexei A.; Jacquinet-Husson, N.; Lefevre, G.; Scott, Noelle A.; Chedin, Alain

2000-01-01

This paper presents the recently developed information content diffusion facilities, e.g. the WWW-server of GEISA, MS DOS, WINDOWS-95/NT, and UNIX software packages, associated with the 1997 version of the GEISA-(Gestion et Etude des Informations Spectroscopiques Atmospheriques; word translation: Management and Study of Atmospheric Spectroscopic Information) infrared spectroscopic databank developed at LMD (Laboratoire de Meteorologie Dynamique, France). GEISA-97 individual lines file involves 42 molecules (96 isotopic species) and contains 1,346,266 entries, between 0 and 22,656 cm-1. GEISA-97 also has a catalog of cross-sections at different temperatures and pressures for species (such as chlorofluorocarbons) with complex spectra. The current version of the GEISA-97 cross- section databank contains 4,716,743 entries related to 23 molecules between 555 and 1700 cm-1.

A Introdução de Astronomia Básica para Estudantes de 5 e 6 Séries do Ensino Fundamental

NASA Astrophysics Data System (ADS)

Gonzaga, E. P.; Voelzke, M. R.

2008-09-01

Com intuito de despertar o interesse pelo estudo da astronomia, desenvolveu-se entre 2003 e 2006 no Centro Educacional do Serviço Social da Indústria situado no município de Mauá, São Paulo, um trabalho com duração de 12 meses para turmas de 11 e 12 anos, sendo três turmas por período (2003 / 2004, 2004 / 2005 e 2005 / 2006). O trabalho realizado, objetivando a introdução da astronomia básica com observações de constelações e das fases da Lua, permitindo estender-se a outros corpos celestes, iniciou-se com visita ao planetário Mundo Estelar, localizado no Ipiranga, São Paulo levantou-se a questão da importância do estudo da astronomia e foi lançado aos estudantes um trabalho de observação, com a proposta de localizar as constelações e compreender as fases da Lua, para o registro de tais observações, foram distribuídos mapas celestes, pastas, planilhas de anotações com lacunas para, constelações, fases da Lua e relatos, onde os estudantes acrescentaram pesquisas e relatórios. Os resultados dos 346 estudantes foram que 86,7% (300) concluíram a etapa de observação, destes 300 estudantes 43,3% (130) pesquisaram sobre as constelações e 19,0% (57) localizaram até quatro constelações. Dos 346 estudantes, 44,2% (153) registraram as fases da Lua equivocadamente e 10,4% (36) anexaram reportagens sobre astronomia. Conclui-se que os estudantes se dividiram em pesquisadores, sendo os estudantes que registraram e anexaram informações e, os observadores que preencheram as planilhas de observações, além de desenvolverem habilidades e competências relacionadas ao estudo da astronomia.

Modeling the energy balance in Marseille: Sensitivity to roughness length parameterizations and thermal admittance

NASA Astrophysics Data System (ADS)

Demuzere, M.; De Ridder, K.; van Lipzig, N. P. M.

2008-08-01

During the ESCOMPTE campaign (Experience sur Site pour COntraindre les Modeles de Pollution atmospherique et de Transport d'Emissions), a 4-day intensive observation period was selected to evaluate the Advanced Regional Prediction System (ARPS), a nonhydrostatic meteorological mesoscale model that was optimized with a parameterization for thermal roughness length to better represent urban surfaces. The evaluation shows that the ARPS model is able to correctly reproduce temperature, wind speed, and direction for one urban and two rural measurements stations. Furthermore, simulated heat fluxes show good agreement compared to the observations, although simulated sensible heat fluxes were initially too low for the urban stations. In order to improve the latter, different roughness length parameterization schemes were tested, combined with various thermal admittance values. This sensitivity study showed that the Zilitinkevich scheme combined with and intermediate value of thermal admittance performs best.

Estructura orbital en el Problema Restringido Rectilíneo Isósceles

NASA Astrophysics Data System (ADS)

Orellana, R. B.

Para definir problemas en Mecánica Celeste se utilizan diferentes parámetros. El conocimiento de la dinámica del problema para valores particulares de estos parámetros nos permite entender el comportamiento en casos más generales. El Problema Restringido Rectilíneo Isósceles puede ser considerado como el caso límite del Problema de Sitnikov cuando la excentricidad tiende a uno o como el Problema Isósceles cuando la masa central tiende a cero. Se ha compactificado el espacio de fases y analizado la dinámica en el límite. Esto ha permitido separar el espacio de fases en diferentes regiones dependiendo de las clases de órbitas.

First aircraft experiment results with the wide-angle airborne laser ranging system

NASA Astrophysics Data System (ADS)

Bock, Olivier; Thom, Christian; Kasser, Michel

1999-12-01

The first aircraft experiment with the Wide-Angle Airborne Laser Ranging System has been conducted in May 1998 over an air base in France equipped with a network of 64 cub-corner retroreflectors. The ranging system was operated from the Avion de Recherche Atmospherique et de Teledetection of CNES/IGN/INSU. Data have been collected during two 4-hour flights. The paper describes the data processing methods and presents the first experimental results. The precision is of 2 cm on the difference of vertical coordinates from two sets of 3 X 103 distance measurements, which is consistent with simulations and a posteriori covariance. The precision is mainly limited by the smallness of the number of efficient measurements remaining after a drastic data sorting for outliers. Higher precision is expected for future experiments after some instrumental improvements (achieving higher link budget) and measurement of aircraft attitude during the flight.

Transverse magnetic field effects on the resonant tunneling current

NASA Astrophysics Data System (ADS)

Cury, L. A.; Celeste, A.; Goutiers, B.; Portal, J. C.; Sivco, D. L.; Cho, A. Y.

1991-04-01

Resonant tunneling process in an (InGa)As-(InAI)As symmetric double-barrier structure subjected to a transverse magnetic field B_{perp} (perpendicular to the current) is investigated. We particularly focus on the experimental behaviour of V_p, the voltage at the current peak position, as a function of the magnetic field B_{perp}. For strong magnetic fields a clear dependence on B_{perp}^2 is observed, as expected. However, an original result is obtained at small magnetic fields where a deviation from the parabolic behaviour is observed. The more complicated dependence on B_{perp} of V_p is obtained from a numerical fit. A qualitative discussion is proposed on the basis of a previous publication (L. A. Cury, A. Celeste, J. C. Portal, Solid-States Electron. 32 (1989) 1689) and the differences with the results of other authors are pointed out. Un système à double barrière à semiconducteurs basé sur les alliages (InGa)As(InAI)As est étudié sous un fort champ magnétique transverse B_{perp} (perpendiculaire au courant). On étudie plus particulièrement la variation expérimentale de la tension V_p associée au courant pic en fonction du champ magnétique B_{perp}. A très fort champ, le comportement attendu de V_p en B_{perp}^2 est observé. Dans le domaine des bas champs magnétiques une déviation du comportement quadratique est mise en évidence. Le comportement plus compliqué de V_p en fonction de B_{perp} est obtenu au travers d'un lissage numérique. Nous proposons une discussion qualitative, de ces résultats, fondée sur notre travail antérieur (L. A. Cury, A. Celeste, J. C. Portal, Solid-States Electron. 32 (1989) 1689) ainsi qu'une comparaison avec les résultats d'autres auteurs.

Análise sobre o Conhecimento de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo sobre Termos e Fenômenos Astronômicos do Cotidiano

NASA Astrophysics Data System (ADS)

de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

2007-08-01

Embora os Parâmetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as orientações complementares a esses Parâmetros (PCN+) apontem a importância de uma abordagem significativa de conceitos relacionados à astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano. Este trabalho tem por objetivo analisar os conhecimentos básicos em astronomia dos alunos de EM da escola estadual Batista Renzi, bem como investigar os meios através dos quais estes conhecimentos foram adquiridos. Para tanto foi elaborado um questionário de múltipla escolha aplicado a 310 alunos distribuídos entre as três séries do EM dos períodos matutino e noturno. Dessa forma, observou-se que apenas 34,5% relacionaram as estações do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influência gravitacional da Lua e do Sol como responsáveis pelo fenômeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distância e 34,2% reconheceram uma estrela cadente como meteoro. Em contrapartida, 67,1% compreendiam a sucessão entre dia e noite, 73,9% identificaram o Sol como estrela e 52,3% relacionaram o Big Bang à origem do Universo. Além disso, foram comparadas as respostas de alunos de diferentes séries e períodos, observando-se, dentre outras coisas, que os estudantes do terceiro ano apresentam um percentual de acertos semelhante ao dos alunos do primeiro, caracterizando que a abordagem de tópicos relacionados à astronomia no EM não tem contribuído para uma maior compreensão dos fenômenos e conceitos.

The Danger from the Outer Space. (Breton Title: O Perigo que Vem do Espaço.) El Peligro que Viene del Espacio

NASA Astrophysics Data System (ADS)

Bedaque, Paulo

2005-12-01

Among the several risks to which the terrestrial life is subject, there is a remote possibility of collision with minor astronomical bodies such as comets and asteroids, which can potentially cause consequences ranging from minor damages to large cataclysms with reflections for the whole Earth. The frequency of the collisions is smaller whenever the external bodies are bigger and more massive. It is possible to conduct simulations taking into account these factors and the velocities and angles of the collisions to estimate their probabilities, the consequences for our planet and the frequency of such events. The results of the simulations are presented graphically to facilitate the final analysis. Finally, we point out that there are several research centers in the world working in the surveillance of the sky to identify possible "aggressive" bodies and evaluate the actual risks for the planet.

Entre os muitos riscos que corre o ambiente terrestre, existe a possibilidade, ainda que remota, de choques com pequenos corpos celestes como cometas, asteróides e meteoróides que podem provocar desde pequenas colisões sem grandes conseqüências até cataclismos de enormes dimensões, com reflexos para toda a vida existente na Terra. A taxa das colisões, como era de se esperar, é tanto maior quanto menores forem as dimensões e a massa do corpo externo. É possível fazer simulações levando-se em conta o diâmetro médio do objeto celeste, sua densidade, a velocidade e o ângulo de colisão para estimar as conseqüências que trariam tais colisões. É possível também estimar ampère probabilidades dos choques e avaliar os reais riscos que nosso planeta corre e com que periodicidade podemos esperá-los. Os resultados dessas simulações aparecem em gráficos de modo a facilitar a analise final. Por fim, lembramos que existem centros de pesquisa em várias partes do mundo trabalhando no patrulhamento do céu na busca de

Infrared spectral imagery of a variety of selected areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chausson, P.; Bibring, J.P.; Erard, S.

1996-11-01

Selected regions in France, Spain, the Canary Islands and Morocco have been observed with an infrared imaging spectrometer, ISM, on board the French aircraft ARAT (Avion de Recherche Atmospherique et de Te1edetection). ISM has been developed for Mars observation during the Phobos mission, and was subsequently adapted to fly on the ARAT. Most of the results have been obtained by studying ratioed spectra. The most relevant parameters are related to the overall shape of the continuum, estimated through the ratios of four spectral bands. They make it possible to discriminate between minerals, vegetation, ocean, snow and clouds. The intensity ofmore » atmospheric water features centered at 0.94 and 1.14 {mu}m are used to determine surface altimetry with a relative accuracy of about 100 m. This method is also applied to the evaluation of the altitude of the top of clouds, with an accuracy of a few hundred meters. 9 refs., 6 figs., 2 tabs.« less

Controle d'attitude d'un lanceur en phase atmospherique approche par applications gardiennes

NASA Astrophysics Data System (ADS)

Dubanchet, Vincent

In a first phase, the modelling process underlines the presence of highly time varying parameters during the ascent, due to a fast mass variation along with propellant consumption. Linearizing the dynamical equations at six main flight instants yields linear time invariant models to be considered during control design. Each of them is to be stabilized by one control law, while respecting given specifications. The synthesis becomes even more complex when the bending modes are taken into account. Moreover, scheduling appears necessary to deal with the time variations. Indeed it is shown that no single gain setting is able to respect all the specifications along the trajectory. Furthermore, increasing complexity when modelling a whole launch vehicle pushes one to consider the model's errors and uncertainties. They represent a major issue in this study since it is asked to ensure the nominal performances in a robust fashion. Owing to their properties, guardian maps appear to be the most suitable tool to deal with such a problem of scheduling with robust performances. In light of this, the development of synthesis methods based on guardian maps is the main contribution of the project. It appears that actual state of the art in this field is focused on theoretical issues, whereas practical ones could be improved. Two approches are presented in the memoire. The first one is based on a graphical approach consisting in drawing the vanishing locus of guardian maps. A program using image analysis techniques is devised to check automatically which gain settings satisfy the constraints. The second one is based on an optimisation procedure involving guardian maps. Starting with the open loop system, the iterative process proposed ends up with a satisfactory gain setting for the closed-loop. These methods are tried and tested for the launch vehicle, with specifications from ASTRIUM-ST. Their practical application is motivated by the system complexity, the different kinds of constraints and the essential need for robustness. Many restrictions that finally bring about the interest and the efficiency of guardian maps for such a problem.

Infrared Lunar Laser Ranging at Calern : Impact on Lunar Dynamics

NASA Astrophysics Data System (ADS)

Viswanathan, Vishnu; Fienga, Agnes; Manche, Herve; Gastineau, Mickael; Courde, Clement; Torre, Jean Marie; Exertier, Pierre; Laskar, Jacques

2017-04-01

Introduction: Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [1]. Dataset: In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [2]. Data reduction: IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [3]. Constraints provided by GRAIL [4], on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. Earth orientation parameters from KEOF series have been used as per a recent study [5]. Results: New estimates on the dynamical parameters of the lunar core will be presented. Acknowledgements: We thank the lunar laser ranging observers at Observatoire de la Côte d'Azur, France, McDonald Observatory, Texas, Haleakala Observatory, Hawaii, and Apache Point Observatory in New Mexico for providing LLR observations that made this study possible. The research described in this abstract was carried out at Geoazur-CNRS, France, as a part of a PhD thesis funded by Observatoire de Paris and French Ministry of Education and Research. References: [1] Clement C. et al. (2016) submitted to A&A [2] Fienga A. et al. (2015) Celest Mech Dyn Astr, 123: 325. doi:10.1007/s10569-015-9639-y [3] Viswanathan V. et al. (2015) EGU, Abstract 18, 13995 [4] Konopliv A. S. et al. (2013) J. Geophys. Res. Planets, 118, 1415

Dinámica global en galaxias elípticas

NASA Astrophysics Data System (ADS)

Pérez, M. J.; Cincotta, P. M.; Giordano, C. M.

Con el propósito de determinar propiedades dinámicas globales en sistemas triaxiales no integrables, utilizamos una nueva herramienta conocida como ``Mean Exponential Growth factor of Nearby Orbits'' (MEGNO), introducida por Cincotta y Simó (2000). Esta técnica no sólo resulta eficiente para investigar ambas componentes del espacio fase, regular y caótica, sino que también, provee una medida de la hiperbolicidad en el dominio caótico que coincide con la dada por el Lyapunov Characteristic Number (LCN). Previamente este método ha sido aplicado al estudio de modelos simples, y últimamente en el campo de la Mecánica Celeste, al estudio de sistemas planetarios extrasolares. En esta presentación, ilustraremos algunas de las propiedades más importantes del MEGNO, aplic& acute;andolo al potencial tridimensional de Stäckel perturbado.

La trama celeste: por qué educar en astronomía. Una oportunidad de aprendizajes múltiples

NASA Astrophysics Data System (ADS)

García, B.

2016-08-01

Astronomy education at all levels has been an issue addressed by the International Astronomical Union as part of its 2010--2020 plan. The content on astronomical topics are in the curriculum at primary and secondary levels worldwide. Being a cross-discipline, astronomy is also a science that allows to introduce students to the study of the nature in a non-confrontational way: no one is indifferent to their concepts and discoveries. The International Astronomical Union, through its Commission on Education and Development of Astronomy, has implemented, sponsored and carried out over the past five years two special programs, one about didactics of astronomy for teachers of middle level and another one for the transmission of astronomical topics for the disabled. In this presentation, achievements and impact of these programs are shared.

Polymerisation par plasma a pression atmospherique: Caracterisation des depots et leurs applications en biotechnologies

NASA Astrophysics Data System (ADS)

Girard-Lauriault, Pierre-Luc

Nitrogen (N)-containing polymer surfaces are attractive in numerous technological contexts, for example in biomedical applications. Here, we have used an atmospheric-pressure dielectric barrier discharge (DBD) apparatus to deposit novel families of N-rich plasma polymers, designated PP:N, using mixtures of three different hydrocarbon precursors (methane, ethylene, and acetylene) in nitrogen at varying respective gas flow ratios, typically parts per thousand. In preparation for subsequent cell-surface interaction studies, the first part of this research focuses on the chemical mapping of those materials, with specific attention to (semi)- quantitative analyses of functional groups. Well-established and some lesser-known analytical techniques have been combined to provide the best possible chemical and structural characterisations of these three families of PP:N thin films; namely, X-ray photoelectron spectroscopy (XPS), Near-edge X-ray absorption fine structure (NEXAFS), Fourier transform infrared spectroscopy (FTIR), contact angle goniometry (CAG), and elemental analysis (EA). High, "tunable" total nitrogen content was measured by both XPS and EA (between 6% and 25% by EA, or between 10% and 40% by XPS, which cannot detect hydrogen). Chemical derivatisation with 4-trifluoromethylbenzaldehyde (TFBA) enabled measurements of primary amine concentrations, the functionality of greatest bio-technological interest, which were found to account for 5 % to 20 % of the total bound nitrogen. By combining the above-mentioned complementary methods, we were further able to determine the complete chemical formulae, the degrees of unsaturation, and other major chemical functionalities in PP:N film structures. Several of these features are believed to be without precedents in the literature on hydrocarbon plasma polymers, for example measurements of absolute compositions (including hydrogen), and of unsaturation. It was shown that besides amines, nitriles, isonitriles and imines are the main nitrogenated functional groups in those materials. In a second part of this work, we have studied the interraction of these well-characterised surfaces with living cells. We have first demonstrated the adhesion, on both uniformly coated and micro-patterned PP:N deposits on BOPP, of three different cell types, namely, growth plate and articular chondrocytes, as well as U937 monocytes, the latter of which do not adhere at all to synthetic polymers used in tissue culture. In an effort to gain insight into cell adhesion mechanisms, we conducted a series of experiments where we cultured U937 monocytes on PP:N, as well as on two other families of chemically well-characterised N-rich thin films, the latter deposited by low pressure RF plasma and by vacuum ultra-violet (VUV) photo-polymerisation ("PVP:N" films). It was first shown that there exist sharply-defined ("critical") surface-chemical conditions that are necessary to induce cell adhesion. By comparing the extensively-characterised film chemistries at the " critical " conditions, we have clearly demonstrated the dominant role of primary amines in the cell adhesion mechanism. In the final aspect of this work, quantitative real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) experiments were conducted using U937 cells that had been made to adhere on PP:N and PVP:N materials for up to 24h. We have shown that the adhesion of U937 monocytes to PP:N and PVP:N surfaces induced a transient expression of cytokines, markers of macrophage activation, as well as a sustained expression of PPARgamma and ICAM-I, implicated in the adhesion and retention of monocytes. Keywords: biomaterials; dielectric barrier discharges (DBD); deposition; plasma polymerisation; ESCA/XPS; NEXAFS; FTIR; primary amines; cell adhesion; gene expression.

Modelisation de la Propagation des Ondes Sonores dans un Environnement Naturel Complexe

NASA Astrophysics Data System (ADS)

L'Esperance, Andre

Ce travail est consacre a la propagation sonore a l'exterieur dans un environnement naturel complexe, i.e. en presence de conditions reelles de vent, de gradient de temperature et de turbulence atmospherique. Plus specifiquement ce travail comporte deux objectifs. D'une part, il vise a developper un modele heuristique de propagation sonore (MHP) permettant de prendre en consideration l'ensemble des phenomenes meteorologiques et acoustiques influencant la propagation du son a l'exterieur. D'autre part, il vise a identifier dans quelles circonstances et avec quelle importance les conditions meteorologiques interviennent sur la propagation sonore. Ce travail est divise en cinq parties. Apres une breve introduction identifiant les motivations de cette etude (chapitre 1), le chapitre 2 fait un rappel des travaux deja realises dans le domaine de la propagation du son a l'exterieur. Ce chapitre presente egalement les bases de l'acoustique geometrique a partir desquelles ont ete developpees la partie acoustique du modele heuristique de propagation. En outre, on y decrit comment les phenomenes de refraction et de turbulence atmospherique peuvent etre consideres dans la theorie des rayons. Le chapitre 3 presente le modele heuristique de propagation (MHP) developpe au cours de cet ouvrage. La premiere section de ce chapitre decrit le modele acoustique de propagation, modele qui fait l'hypothese d'un gradient de celerite lineaire et qui est base sur une solution hybride d'acoustique geometrique et de theorie des residus. La deuxieme section du chapitre 3 traite plus specifiquement de la modelisation des aspects meteorologiques et de la determination des profils de celerite et des index de fluctuation associes aux conditions meteorologiques. La section 3 de ce chapitre decrit comment les profils de celerite resultants sont linearises pour les calculs dans le modele acoustique, et finalement la section 4 donne les tendances generales obtenues par le modele. Le chapitre 4 decrit

The Hitomi (ASTRO-H) Soft X-ray Telescope (SXT): current status of calibration

NASA Astrophysics Data System (ADS)

Maeda, Yoshitomo; Kikuchi, Naomichi; Kurashima, Sho; Ishida, Manabu; Iizuka, Ryo; Hayashi, Takayuki; Okajima, Takashi; Matsumoto, Hironori; Mitsuishi, Ikuyuki; Saji, Shigetaka; Sato, Toshiki; Tachibana, Sasagu; Mori, Hideyuki; Christensen, Finn; Brejnholt, Nicolai; Nitta, Kiyofumi; Uruga, Tomoya

2017-08-01

We report the atomic scattering factor in the 11.2-15.4 keV for the ASTRO-H Soft X-ray Telescope (SXT)9 obtained in the ground based measurements. The large effective area of the SXT covers above 10 keV. In fact, the flight data show the spectra of the celestical objects in the hard X-ray band. In order to model the area, the reflectivity measurements in the 11.2-15.4 keV band with the energy pitch of 0.4 - 0.7 eV were made in the synchrotron beamline Spring-8 BL01B1. We obtained atomic scattering factors f1 and f2 by the curve fitting to the reflectivities of our witness sample. The edges associated with the gold' s L-I, II, and III transitions are identified, of which the depths are found to be roughly 60% shallower than those expected from the Henke's atomic scattering factor.

Reflectivity around the gold L-edges of x-ray reflector of the soft x-ray telescope onboard ASTRO-H

NASA Astrophysics Data System (ADS)

Maeda, Yoshitomo; Kikuchi, Naomichi; Kurashima, Sho; Ishida, Manabu; Iizuka, Ryo; Hayashi, Takayuki; Okajima, Takashi; Matsumoto, Hironori; Mitsuishi, Ikuyuki; Saji, Shigetaka; Sato, Toshiki; Tachibana, Sasagu; Mori, Hideyuki; Christensen, Finn; Brejnholt, Nicolai; Nitta, Kiyofumi; Uruga, Tomoya

2016-07-01

We report the atomic scattering factor in the 11.2{15.4 keV for the ASTRO-H Soft X-ray Telescope (SXT)9 obtained in the ground based measurements. The large effective area of the SXT covers above 10 keV. In fact, the flight data show the spectra of the celestical objects in the hard X-ray band. In order to model the area, the reflectivity measurements in the 11.2{15.4 keV band with the energy pitch of 0.4 { 0.7 eV were made in the synchrotron beamline Spring-8 BL01B1. We obtained atomic scattering factors f1 and f2 by the curve fitting to the reflectivities of our witness sample. The edges associated with the gold's L-I, II, and III transitions are identified, of which the depths are found to be roughly 60% shallower than those expected from the Henke's atomic scattering factor.

The Tranisiting Dust of Boyajian's Star

NASA Astrophysics Data System (ADS)

Bodman, Eva; Ellis, Tyler G.; Boyajian, Tabetha S.; Wright, Jason

2018-06-01

From May to October of 2017, Boyajian's Star displayed four days-long dips in observed flux, which are referred to as “Elsie,” “Celeste,” “Skara Brae,” and “Angkor” (Boyajian et al. 2018). This Elsie family dip event was monitored with the Las Cumbres Observatory in three bands, B, r', and i'. Looking at each dip individually, we analyze the multi-band photometry for wavelength dependency in dip depth to constrain properties of the transiting material. We find that all of the dips show non-grey extinction and are consistent with optically thin dust. Interpreting the dips as transiting dust clouds, we constrain the properties of the dust grains and find that the average grain radius is <1 micron, assuming silicate composition. This wavelength dependency and grain size is inconsistent with observed properties of the long-term “secular” dimming (Meng et al. 2017), suggesting that the dust causing the dips is from a separate population.

Reflectivity Around the Gold L-Edges of X-Ray Reflector of the Soft X-Ray Telescope Onboard ASTRO-H

NASA Technical Reports Server (NTRS)

Maeda, Yoshitomo; Kikuchi, Naomichi; Kurashima, Sho; Ishida, Manabu; Iizuka, Ryo; Hayashi, Takayuki; Okajima, Takashi; Matsumoto, Hironori; Mitsuishi, Ikuyuki; Saji, Shigetaka;

A new cryptogonimid (Digenea) from the Mayan cichlid, Cichlasoma urophthalmus (Osteichthyes: Cichlidae), in several localities of the Yucatán Peninsula, Mexico.

PubMed

Razo-Mendivil, Ulises; Rosas-Valdez, Rogelio; Pérez-Ponce de León, Gerardo

2008-12-01

Oligogonotylus mayae n.sp. is described from the intestine of the Mayan cichlid Cichlasoma urophthalmus (Günther) in Ría Lagartos, Ría Celestún, and Estero Progreso, Yucatán State. This is the second species described for Oligogonotylus Watson, 1976, the other being O.manteri Watson, 1976. The new species is readily distinguished from O. manteri by the anterior extension of the vitelline follicles. In O. Manteri, Vitelline follicles are found entirely in the hindbody, extending posteriorly to mid-testicular level. Vitelline follicles in the new species extend from teh anterior margin of posterior testis to the region between the bentral sucker and the pharynx. comparison of approximately 1,850 bases of ribosomal DNA (ITS1, ITS2, 5.8S, and 28S), and 400 bases of cytochrome c oxidase subunit I (cox1) strongly supports the status of O. mayae as a new species, as compared to O. manteri collected from cichlids in other localities of Mexico, Belize, and Guatemala.

Fast numerics for the spin orbit equation with realistic tidal dissipation and constant eccentricity

NASA Astrophysics Data System (ADS)

Bartuccelli, Michele; Deane, Jonathan; Gentile, Guido

2017-08-01

We present an algorithm for the rapid numerical integration of a time-periodic ODE with a small dissipation term that is C^1 in the velocity. Such an ODE arises as a model of spin-orbit coupling in a star/planet system, and the motivation for devising a fast algorithm for its solution comes from the desire to estimate probability of capture in various solutions, via Monte Carlo simulation: the integration times are very long, since we are interested in phenomena occurring on timescales of the order of 10^6-10^7 years. The proposed algorithm is based on the high-order Euler method which was described in Bartuccelli et al. (Celest Mech Dyn Astron 121(3):233-260, 2015), and it requires computer algebra to set up the code for its implementation. The payoff is an overall increase in speed by a factor of about 7.5 compared to standard numerical methods. Means for accelerating the purely numerical computation are also discussed.

Digitization and Position Measurement of Astronomical Plates of Saturnian Satellites

NASA Astrophysics Data System (ADS)

Yan, D.; Yu, Y.; Zhang, H. Y.; Qiao, R. C.

2014-05-01

Using the advanced commercial scanners to digitize astronomical plates may be a simple and effective way. In this paper, we discuss the method of digitizing and astrometrically reducing six astronomical plates of Saturnian satellites, which were taken from the 1 m RCC (Ritchey Chretien Coude) telescope of Yunnan Observatory in 1988, by using the 10000XL scanner of Epson. The digitized images of the astronomical plates of Saturnian satellites are re-reduced, and the positions of Saturnian satellites based on the UCAC2 (The Second US Naval Observatory CCD Astrograph Catalog) catalogue are given. A comparison of our measured positions with the IMCCE (Institut de Mecanique Celeste et de Calcul des Ephemerides) ephemeris of Saturnian satellites shows the high quality of our measurements, which have an accuracy of 106 mas in right ascension and 89 mas in declination. Moreover, our measurements appear to be consistent with this ephemeris within only about 56 mas in right ascension and 9 mas in declination.

A Reappraising of Cosmography: the Interface Between Astronomical and Geographic Studies. (Breton Title: Releitura do Conceito de Cosmografia: a Interface Entre os Estudos Astronômicos e Geográficos.) Una Relectura del Concepto de Cosmografía: la Interfase Entre los Estudios Astronómicos y Geográficos

NASA Astrophysics Data System (ADS)

Azevedo Sobreira, Paulo Henrique

2012-12-01

The concept of "Cosmography" is in disuse since the 80s of the last century, but the astronomical themes previously discussed in the school subjects of Geography and Cosmography remain in current textbooks. The use of term "Cosmography" was rescued in this research, and the study of its re-signification prompted the appearance of the term Geographic Cosmography. The Geographic Cosmography is a field of studies of the Geography, whose set of knowledge and skills is predominantly scholar. It studies the interface between terrestrial and celestial knowledge, and assigns a geographic significance to them. It examines human and natural relationships with Sidereal Space and its consequences for society and nature. O conceito de "Cosmografia" está em desuso desde os anos 80 do século XX, mas os temas astronômicos anteriormente abordados nas disciplinas escolares de Cosmografia e de Geografia permanecem nos atuais livros didáticos. O uso do termo "Cosmografia" foi resgatado nesta pesquisa e o estudo de sua ressignificação proporcionou o surgimento do termo Cosmografia Geográfica. A Cosmografia Geográfica é um campo de estudos da Geografia, cujo conjunto de conhecimentos e habilidades é predominantemente escolar. Estuda a interface entre os conhecimentos terrestres e os celestes e lhes atribui significância geográfica. Analisa as relações humanas e naturais com o Espaço Sideral e suas consequências para a sociedade e a natureza.

Aunque el concepto de "Cosmografía" no se usa desde la década de los '80 del siglo pasado, los temas astronómicos que se enseñaban anteriormente en las asignaturas escolares de Cosmografía y de Geografía permanecen en los actuales libros didácticos. El uso del término "Cosmografía" fue rescatado en esta investigación y el estudio de su resignificación proporcionó el surgimiento del término Cosmografía Geográfica. La Cosmografía Geográfica es un campo de estudio de la Geografía, donde

Evaluation of the MOCAGE Chemistry Transport Model during the ICARTT/ITOP Experiment

NASA Technical Reports Server (NTRS)

Bousserez, N.; Attie, J. L.; Peuch, V. H.; Michou, M.; Pfister, G.; Edwards, D.; Emmons, L.; Arnold, S.; Heckel, A.; Richter, A.;

A Visão do Universo Segundo a Concepção de um Grupo de Alunos do Ensino Médio de São Paulo

NASA Astrophysics Data System (ADS)

Araújo, M. A. A.; Elias, D. C. N.; Amaral, L. H.; Araújo, M. S. T.; Voelzke, M. R.

2005-12-01

Nesse trabalho foi identificada por meio de um questionário a visão de mundo sobre o Universo espaço e tempo entre 270 estudantes de Ensino Médio de três escolas de São Paulo. Constatou-se pouco conhecimento dos temas investigados sendo que apenas 20% dos alunos relacionaram as semanas com as fases da lua enquanto 28% associaram as estações do ano à inclinação do eixo de rotação da Terra e 23% tinham noções das distâncias entre objetos celestes próximos da Terra. Enquanto 56% conseguiram relacionar o Big Bang com a origem do Universo verificou-se que 37% reconheciam ano-luz como unidade de distância e 60% reconheciam o Sol como uma estrela. Apesar de 60% dos alunos indicarem a escola como principal fonte dos conhecimentos de astronomia seus conceitos ainda são inadequados havendo necessidade de aprimoramento da abordagem desses conteúdos pois apesar de popular a astronomia é veiculada de maneira pouco esclarecedora e com imprecissões.

Algorithms for Stellar Perturbation Computations on Oort Cloud Comets

NASA Astrophysics Data System (ADS)

Rickman, Hans; Fouchard, Marc; Valsecchi, Giovanni B.; Froeschlé, Christiane

2005-12-01

We investigate different approximate methods of computing the perturbations on the orbits of Oort cloud comets caused by passing stars, by checking them against an accurate numerical integration using Everhart’s RA15 code. The scenario under study is the one relevant for long-term simulations of the cloud’s response to a predefined set of stellar passages. Our sample of stellar encounters simulates those experienced by the Solar System currently, but extrapolated over a time of 1010 years. We measure the errors of perihelion distance perturbations for high-eccentricity orbits introduced by several estimators including the classical impulse approximation and Dybczyński’s (1994, Celest. Mech. Dynam. Astron. 58, 1330 1338) method and we study how they depend on the encounter parameters (approach distance and relative velocity). We introduce a sequential variant of Dybczyński’s approach, cutting the encounter into several steps whereby the heliocentric motion of the comet is taken into account. For the scenario at hand this is found to offer an efficient means to obtain accurate results for practically any domain of the parameter space.

Radioastronomía: Una Mirada Más Amplia

NASA Astrophysics Data System (ADS)

Bianchi, Viviana

2004-12-01

The existence of the celestial bodies is known due to the light they emit. But light is a small part of a bigger phenomenon known as electromagnetic radiation. The representation of all kinds of electromagnetic radiation as a function of its frequency is called the electromagnetic spectrum. If we only studied the visible part of the spectrum, we would ignore a great deal of information. The celestial bodies emit radiation in all the regions of the electromagnetic spectrum, with very different intensity. To capture these data, astronomers design new types of telescopes that capture radiation at different wavelengths, among them the radiotelescopes that, as the name indicates, detect radio waves. The radiotelescope can be compared to a regular radio set. A radio station sends information by means of radio waves. The radio set captures these waves by means of its antenna, processes it and reproduces the information (music, etc.) in audible form. In the field of radioastronomy, interesting observations can be carried out: radio emission from stars, nebulas, pulsars, distant galaxies and stars, radiogalaxies, the Milky Way, the Sun, Jupiter, etc. La presencia de los cuerpos celestes se conoce gracias a que emiten luz. Pero la luz constituye solo una pequeña parte de un fenómeno mucho mas amplio conocido como radiación electromagnética. La representación de todas las clases de radiación como función de su frecuencia se denomina espectro electromagnético. Si solo estudiáramos la parte visual del espectro ignoraríamos una gran cantidad de información. Los cuerpos celestes emiten radiación en todas las regiones del espectro electromagnético, aunque con muy distinta intensidad. Para captar estos datos, los astrónomos deben diseñar nuevos tipos de telescopios que puedan captar la radiación de distintas longitudes de ondas, entre ellos los radiotelescopios, qué como su nombre lo indica detectan ondas de radio. El radiotelescopio puede compararse a un aparato

Galactic Diffuse Gamma Ray Emission Is Greater than 10 Gev

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.; White, Nicholas E. (Technical Monitor)

2000-01-01

AGILE and Gamma-ray Large Area Telescope (GLAST) are the next high-energy gamma-ray telescopes to be flown in space. These instruments will have angular resolution about 5 times better than Energetic Gamma-Ray Experiment Telescope (EGRET) above 10 GeV and much larger field of view. The on-axis effective area of AGILE will be about half that of EGRET, whereas GLAST will have about 6 times greater effective area than EGRET. The capabilities of ground based very high-energy telescopes are also improving, e.g. Whipple, and new telescopes, e.g. Solar Tower Atmospheric Cerenkov Effect Experiment (STACEE), Cerenkov Low Energy Sampling and Timing Experiment (CELESTE), and Mars Advanced Greenhouse Integrated Complex (MAGIC) are expected to have low-energy thresholds and sensitivities that will overlap the GLAST sensitivity above approximately 10 GeV. In anticipation of the results from these new telescopes, our current understanding of the galactic diffuse gamma-ray emission, including the matter and cosmic ray distributions is reviewed. The outstanding questions are discussed and the potential of future observations with these new instruments to resolve these questions is examined.

Observations of CH4, C2H6, and C2H2 in the stratosphere of Jupiter

NASA Technical Reports Server (NTRS)

Sada, P. V.; Bjoraker, G. L.; Jennings, D. E.; McCabe, G. H.; Romani, P. N.

1998-01-01

We have performed high-resolution spectral observations at mid-infrared wavelengths of CH4 (8.14 micrometers), C2H6 (12.16 micrometers), and C2H2 (13.45 micrometers) on Jupiter. These emission features probe the stratosphere of the planet and provide information on the carbon-based photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer CELESTE, in conjunction with the McMath-Pierce 1.5-m solar telescope between November 1994 and February 1995. We used the methane observations to derive the temperature profile of the jovian atmosphere in the 1-10 mbar region of the stratosphere. This profile was then used in conjunction with height-dependent mixing ratios of each hydrocarbon to determine global abundances for ethane and acetylene. The resulting mixing ratios are 3.9(+1.9)(-1.3) x 10(-6) for C2H6 (5 mbar pressure level), and 2.3 +/- 0.5 x 10(-8) for C2H2 (8 mbar pressure level), where the quoted uncertainties are derived from model variations in the temperature profile which match the methane observation uncertainties. c1998 Academic Press.

DROMO Propagator Revisited

NASA Astrophysics Data System (ADS)

Urrutxua, H.; Sanjurjo-Rivo, M.; Peláez, J.

2013-12-01

In year 2000 a house-made orbital propagator was developed by the SDGUPM (former Grupo de Dinámica de Tethers) based in a set of redundant variables including Euler parameters. This propagator was called DROMO. and it was mainly used in numerical simulations of electrodynamic tethers. It was presented for the first time in the international meeting V Jornadas de Trabajo en Mecánica Celeste, held in Albarracín, Spain, in 2002 (see reference 1). The special perturbation method associated with DROMO can be consulted in the paper.2 In year 1975, Andre Deprit in reference 3 proposes a propagation scheme very similar to the one in which DROMO is based, by using the ideal frame concept of Hansen. The different approaches used in references 3 and 2 gave rise to a small controversy. In this paper we carried out a different deduction of the DROMO propagator, underlining its close relation with the Hansen ideal frame concept, and also the similarities and the differences with the theory carried out by Deprit in 3. Simultaneously we introduce some improvements in the formulation that leads to a more synthetic propagator.

Percepção astronómica de um grupo de alunos do ensino médio de uma escola da rede estadual de São Paulo

NASA Astrophysics Data System (ADS)

de Oliveria, E. F.; Voelzke, M. R.

2009-03-01

Sendo a Astronomia uma das cièncias mais antigas da humanidade, e considerando sua importáncia histórica e cultural, é de extrema releváncia que tópicos relacionados a ela sejam tratados nas escolas. Embora os Parámetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as Orientaçiacute;es Complementares aos Parámetros (PCN+) apontem a importáncia de uma abordagem significativa de conceitos relacionados à Astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano e sejam alvos da curiosidade natural dos jovens. Da observação dessa curiosidade em alunos de uma escola pública paulista, na cidade de Suzano, surgiu o interesse em investigar os conhecimentos básicos em Astronomia dos alunos do Ensino Médio desta escola, constituindo-se este como principal objetivo desta pesquisa. Para tanto foi elaborado um questionário de múltipla escolha aplicado inicialmente a 34 alunos do primeiro ano e, posteriormente, a mais 310, distribuídos entre as très séries do Ensino Médio dos períodos matutino e noturno. Dessa forma, observou-se que 73,9% dos estudantes identificaram o Sol como sendo uma estrela, 67,1% mostraram compreender a sucessão entre dia e noite e 52,3% relacionaram o Big Bang à origem do Universo. Em contrapartida, apenas 34,5% relacionaram as estaçíes do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influència gravitacional simultánea da Lua e do Sol como responsável pelo fenòmeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distáncia e 34,2% reconheceram as estrelas cadentes como meteoros, evidenciando-se assim o pequeno discernimento dos estudantes quanto aos fenòmenos e termos astronòmicos do cotidiano. Além disso, foram comparadas as respostas de alun! os de diferentes s

Annual Greenland Accumulation Rates (2009-2012) from Airborne Snow Radar

NASA Technical Reports Server (NTRS)

Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joseph R.;

Occupational exposures and asthma in 14,000 adults from the general population

PubMed Central

Le Moual, Nicole; Kennedy, Susan M.; Kauffmann, Francine

2004-01-01

The association of occupational exposures and asthma were studied in 14151 adults, aged 25–59 years, from the general population of the French PAARC (Pollution Atmospherique et Affections Respiratoires Chroniques, 1975) Survey. Associations of asthma to specific jobs such as personal care workers, waiters, stock clerks were observed, with age, sex, smoking adjusted odds ratios between 1.5 and 1.7. Exposures to 18 asthmagenic agents (low, high molecular weight and mixed environment) were estimated by an asthma-specific job exposure matrix. Risks associated with asthma increased when excluding subjects with imprecise estimates of exposure. Risks further increased when increasing specificity of the definition of asthma considering jobs or specific agents such as industrial cleaning agents, latex, flour, highly reactive chemicals, and textiles. For example, for industrial cleaning agents, odds ratios increased from 1.55 (95% CI: 1.08, 2.23) for ever asthma, to 2.51 (95% CI: 1.33, 4.75) for asthma with airflow limitation, to 2.17 (95% CI: 1.41, 3.34) for asthma onset after age 14, and to 2.35 (95% CI: 1.38, 4.00) for asthma onset after beginning of current job. Results underlined the importance of the specificity of exposure and asthma definitions and indicated a deleterious role of occupational exposure on asthma, especially for cleaning agents. PMID:15561990

Trematode communities in snails can indicate impact and recovery from hurricanes in a tropical coastal lagoon

USGS Publications Warehouse

Aguirre-Macedo, Maria Leopoldina; Vidal-Martinez, Victor M.; Lafferty, Kevin D.

2011-01-01

In September 2002, Hurricane Isidore devastated the Yucatán Peninsula, Mexico. To understand its effects on the parasites of aquatic organisms, we analyzed long-term monthly population data of the horn snail Cerithidea pliculosa and its trematode communities in Celestún, Yucatán, Mexico before and after the hurricane (February 2001 to December 2009). Five trematode species occurred in the snail population: Mesostephanus appendiculatoides, Euhaplorchis californiensis, two species of the genus Renicola and one Heterophyidae gen. sp. Because these parasites use snails as first intermediate hosts, fishes as second intermediate hosts and birds as final hosts, their presence in snails depends on food webs. No snails were present at the sampled sites for 6 months after the hurricane. After snails recolonised the site, no trematodes were found in snails until 14 months after the hurricane. It took several years for snail and trematode populations to recover. Our results suggest that the increase in the occurrence of hurricanes predicted due to climate change can impact upon parasites with complex life cycles. However, both the snail populations and their parasite communities eventually reached numbers of individuals and species similar to those before the hurricane. Thus, the trematode parasites of snails can be useful indicators of coastal lagoon ecosystem degradation and recovery.

Sitnikov problem in the square configuration: elliptic case

NASA Astrophysics Data System (ADS)

Shahbaz Ullah, M.

2016-05-01

This paper is extension to the classical Sitnikov problem, when the four primaries of equal masses lie at the vertices of a square for all time and moving in elliptic orbits around their center of mass of the system, the distances between the primaries vary with time but always in such a way that their mutual distances remain in the same ratio. First we have established averaged equation of motion of the Sitnikov five-body problem in the light of Jalali and Pourtakdoust (Celest. Mech. Dyn. Astron. 68:151-162, 1997), by applying the Van der Pol transformation and averaging technique of Guckenheimer and Holmes (Nonlinear oscillations, dynamical system bifurcations of vector fields, Springer, Berlin, 1983). Next the Hamiltonian equation of motion has been solved with the help of action angle variables I and φ. Finally the periodicity and stability of the Sitnikov five-body problem have been examined with the help of Poincare surfaces of section (PSS). It is shown that chaotic region emerging from the destroyed islands, can easily be seen by increasing the eccentricity of the primaries to e = 0.21. It is valid for bounded small amplitude solutions z_{max} ( z_{max} = 0.65 ) and 0 ≤ e < 0.3.

Post-storage cell wall metabolism in two sweet cherry (Prunus avium L.) cultivars displaying different postharvest performance.

PubMed

Belge, Burcu; Comabella, Eva; Graell, Jordi; Lara, Isabel

2015-09-01

The biochemical processes underlying firmness loss of sweet cherry (Prunus avium L.) fruit are poorly understood. Studies on cell wall metabolism of sweet cherry have been generally undertaken during on-tree development or at harvest maturity, while published reports on postharvest changes are scarce and fragmentary. In this work, cell wall modifications after storage at 0 ℃ were studied in two cherry cultivars ('Celeste' and 'Somerset') displaying different postharvest potential. Firmness was largely determined by the yields of the Na2CO3- and KOH-soluble fractions, enriched in covalently-bound pectins and in matrix glycans, respectively, and correlated well with ascorbic acid contents. The yields of these two cell wall fractions were correlated inversely with pectinmethylesterase and endo-1,4-β-d-glucanase activities, indicating a relevant role of these two enzymes in postharvest firmness changes in sweet cherry. The amount of solubilised cell wall materials was closely associated to the contents of dehydroascorbic acid, suggesting the possible involvement of oxidative mechanisms in cell wall disassembly. These data may help understanding the evolution of fruit quality during the marketing period, and give hints for the design of suitable management strategies to preserve key attributes. © The Author(s) 2014.

Observations of the Natural Planetary Satellites for Dynamical and Physical Purpose

NASA Astrophysics Data System (ADS)

Arlot, J. E.; Thuillot, W.; Fienga, A.; Bec-Borsenberger, A.; Baron, N.; Berthier, J.; Colas, F.; Descamps, P.

1999-12-01

At the Institut de mecanique celeste-Bureau des longitudes, we started several programs of observation of the natural planetary satellites. First, we took the opportunity of the transit of the Earth and the Sun in the equatorial plane of Jupiter to observe the mutual phenomena of the Galilean satellites. These observations provide astrometric data of high accuracy useful for dynamical studies of the motions of the satellites and photometric data allowing to characterize the surfaces of the satellites. A campaign was organized leading to 400 light curves made throughout the world in about 40 countries. Second, we started astrometric CCD observations of the faint satellites of Jupiter JVI to JXIII and of the satellite of Saturn Phoebe (SIX) for dynamical purpose at Observatoire de Haute Provence using the 120cm-telescope. PPM, Hipparcos and USNO A.2 catalogue were used for calibration in order to get absolute J2000 R.A. and declination of these objects. In August and December, 1998, CCD observations provided 43 absolute positions of JVI, 23 of JVII, 53 of JVIII, 35 of JIX, 29 of JX, 27 of JXI, 18 of JXII, 16 of JXIII and 135 of SIX (Phoebe). A campaign will also take place in 1999.

Trematode communities in snails can indicate impact and recovery from hurricanes in a tropical coastal lagoon.

PubMed

Aguirre-Macedo, María Leopoldina; Vidal-Martínez, Victor M; Lafferty, Kevin D

2011-11-01

In September 2002, Hurricane Isidore devastated the Yucatán Peninsula, Mexico. To understand its effects on the parasites of aquatic organisms, we analyzed long-term monthly population data of the horn snail Cerithidea pliculosa and its trematode communities in Celestún, Yucatán, Mexico before and after the hurricane (February 2001 to December 2009). Five trematode species occurred in the snail population: Mesostephanus appendiculatoides, Euhaplorchis californiensis, two species of the genus Renicola and one Heterophyidae gen. sp. Because these parasites use snails as first intermediate hosts, fishes as second intermediate hosts and birds as final hosts, their presence in snails depends on food webs. No snails were present at the sampled sites for 6 months after the hurricane. After snails recolonised the site, no trematodes were found in snails until 14 months after the hurricane. It took several years for snail and trematode populations to recover. Our results suggest that the increase in the occurrence of hurricanes predicted due to climate change can impact upon parasites with complex life cycles. However, both the snail populations and their parasite communities eventually reached numbers of individuals and species similar to those before the hurricane. Thus, the trematode parasites of snails can be useful indicators of coastal lagoon ecosystem degradation and recovery. Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.

Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatan, Mexico

USGS Publications Warehouse

Chuang, P. C.; Young, Megan B.; Dale, Andrew W.; Miller, Laurence G.; Herrera-Silveira, Jorge A.; Paytan, Adina

2016-01-01

Porewater profiles in sediment cores from mangrove-dominated coastal lagoons (Celestún and Chelem) on the Yucatán Peninsula, Mexico, reveal the widespread coexistence of dissolved methane and sulfate. This observation is interesting since dissolved methane in porewaters is typically oxidized anaerobically by sulfate. To explain the observations we used a numerical transport-reaction model that was constrained by the field observations. The model suggests that methane in the upper sediments is produced in the sulfate reduction zone at rates ranging between 0.012 and 31 mmol m−2 d−1, concurrent with sulfate reduction rates between 1.1 and 24 mmol SO42− m−2 d−1. These processes are supported by high organic matter content in the sediment and the use of non-competitive substrates by methanogenic microorganisms. Indeed sediment slurry incubation experiments show that non-competitive substrates such as trimethylamine (TMA) and methanol can be utilized for microbial methanogenesis at the study sites. The model also indicates that a significant fraction of methane is transported to the sulfate reduction zone from deeper zones within the sedimentary column by rising bubbles and gas dissolution. The shallow depths of methane production and the fast rising methane gas bubbles reduce the likelihood for oxidation, thereby allowing a large fraction of the methane formed in the sediments to escape to the overlying water column.

Secular resonances between bodies on close orbits II: prograde and retrograde orbits for irregular satellites

NASA Astrophysics Data System (ADS)

Li, Daohai; Christou, Apostolos A.

2017-09-01

In extending the analysis of the four secular resonances between close orbits in Li and Christou (Celest Mech Dyn Astron 125:133-160, 2016) (Paper I), we generalise the semianalytical model so that it applies to both prograde and retrograde orbits with a one-to-one map between the resonances in the two regimes. We propose the general form of the critical angle to be a linear combination of apsidal and nodal differences between the two orbits b_1 Δ π + b_2 Δ Ω, forming a collection of secular resonances in which the ones studied in Paper I are among the strongest. Test of the model in the orbital vicinity of massive satellites with physical and orbital parameters similar to those of the irregular satellites Himalia at Jupiter and Phoebe at Saturn shows that {>}20 and {>}40% of phase space is affected by these resonances, respectively. The survivability of the resonances is confirmed using numerical integration of the full Newtonian equations of motion. We observe that the lowest order resonances with b_1+|b_2|≤ 3 persist, while even higher-order resonances, up to b_1+|b_2|≥ 7, survive. Depending on the mass, between 10 and 60% of the integrated test particles are captured in these secular resonances, in agreement with the phase space analysis in the semianalytical model.

The First Post-Kepler Brightness Dips of KIC 8462852

NASA Astrophysics Data System (ADS)

Boyajian, Tabetha. S.; Alonso, Roi; Ammerman, Alex; Armstrong, David; Asensio Ramos, A.; Barkaoui, K.; Beatty, Thomas G.; Benkhaldoun, Z.; Benni, Paul; Bentley, Rory O.; Berdyugin, Andrei; Berdyugina, Svetlana; Bergeron, Serge; Bieryla, Allyson; Blain, Michaela G.; Capetillo Blanco, Alicia; Bodman, Eva H. L.; Boucher, Anne; Bradley, Mark; Brincat, Stephen M.; Brink, Thomas G.; Briol, John; Brown, David J. A.; Budaj, J.; Burdanov, A.; Cale, B.; Aznar Carbo, Miguel; Castillo García, R.; Clark, Wendy J.; Clayton, Geoffrey C.; Clem, James L.; Coker, Phillip H.; Cook, Evan M.; Copperwheat, Chris M.; Curtis, J. L.; Cutri, R. M.; Cseh, B.; Cynamon, C. H.; Daniels, Alex J.; Davenport, James R. A.; Deeg, Hans J.; De Lorenzo, Roberto; de Jaeger, Thomas; Desrosiers, Jean-Bruno; Dolan, John; Dowhos, D. J.; Dubois, Franky; Durkee, R.; Dvorak, Shawn; Easley, Lynn; Edwards, N.; Ellis, Tyler G.; Erdelyi, Emery; Ertel, Steve; Farfán, Rafael. G.; Farihi, J.; Filippenko, Alexei V.; Foxell, Emma; Gandolfi, Davide; Garcia, Faustino; Giddens, F.; Gillon, M.; González-Carballo, Juan-Luis; González-Fernández, C.; González Hernández, J. I.; Graham, Keith A.; Greene, Kenton A.; Gregorio, J.; Hallakoun, Na’ama; Hanyecz, Ottó; Harp, G. R.; Henry, Gregory W.; Herrero, E.; Hildbold, Caleb F.; Hinzel, D.; Holgado, G.; Ignácz, Bernadett; Ilyin, Ilya; Ivanov, Valentin D.; Jehin, E.; Jermak, Helen E.; Johnston, Steve; Kafka, S.; Kalup, Csilla; Kardasis, Emmanuel; Kaspi, Shai; Kennedy, Grant M.; Kiefer, F.; Kielty, C. L.; Kessler, Dennis; Kiiskinen, H.; Killestein, T. L.; King, Ronald A.; Kollar, V.; Korhonen, H.; Kotnik, C.; Könyves-Tóth, Réka; Kriskovics, Levente; Krumm, Nathan; Krushinsky, Vadim; Kundra, E.; Lachapelle, Francois-Rene; LaCourse, D.; Lake, P.; Lam, Kristine; Lamb, Gavin P.; Lane, Dave; Lau, Marie Wingyee; Lewin, Pablo; Lintott, Chris; Lisse, Carey; Logie, Ludwig; Longeard, Nicolas; Lopez Villanueva, M.; Whit Ludington, E.; Mainzer, A.; Malo, Lison; Maloney, Chris; Mann, A.; Mantero, A.; Marengo, Massimo; Marchant, Jon; Martínez González, M. J.; Masiero, Joseph R.; Mauerhan, Jon C.; McCormac, James; McNeely, Aaron; Meng, Huan Y. A.; Miller, Mike; Molnar, Lawrence A.; Morales, J. C.; Morris, Brett M.; Muterspaugh, Matthew W.; Nespral, David; Nugent, C. R.; Nugent, Katherine M.; Odasso, A.; O’Keeffe, Derek; Oksanen, A.; O’Meara, John M.; Ordasi, András; Osborn, Hugh; Ott, John J.; Parks, J. R.; Rodriguez Perez, Diego; Petriew, Vance; Pickard, R.; Pál, András; Plavchan, P.; Pollacco, Don; Pozo Nuñez, F.; Pozuelos, F. J.; Rau, Steve; Redfield, Seth; Relles, Howard; Ribas, Ignasi; Richards, Jon; Saario, Joonas L. O.; Safron, Emily J.; Sallai, J. Martin; Sárneczky, Krisztián; Schaefer, Bradley E.; Schumer, Clea F.; Schwartzendruber, Madison; Siegel, Michael H.; Siemion, Andrew P. V.; Simmons, Brooke D.; Simon, Joshua D.; Simón-Díaz, S.; Sitko, Michael L.; Socas-Navarro, Hector; Sódor, Á.; Starkey, Donn; Steele, Iain A.; Stone, Geoff; Strassmeier, Klaus G.; Street, R. A.; Sullivan, Tricia; Suomela, J.; Swift, J. J.; Szabó, Gyula M.; Szabó, Róbert; Szakáts, Róbert; Szalai, Tamás; Tanner, Angelle M.; Toledo-Padrón, B.; Tordai, Tamás; Triaud, Amaury H. M. J.; Turner, Jake D.; Ulowetz, Joseph H.; Urbanik, Marian; Vanaverbeke, Siegfried; Vanderburg, Andrew; Vida, Krisztián; Vietje, Brad P.; Vinkó, József; von Braun, K.; Waagen, Elizabeth O.; Walsh, Dan; Watson, Christopher A.; Weir, R. C.; Wenzel, Klaus; Westendorp Plaza, C.; Williamson, Michael W.; Wright, Jason T.; Wyatt, M. C.; Zheng, WeiKang; Zsidi, Gabriella

2018-01-01

We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%–2.5% dips, named “Elsie,” “Celeste,” “Skara Brae,” and “Angkor,” which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale ≪1 μm, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term “secular” dimming, which may be caused by independent processes, or probe different regimes of a single process.

Determination of Reference Catalogs for Meridian Observations Using Statistical Method

NASA Astrophysics Data System (ADS)

Li, Z. Y.

2014-09-01

The meridian observational data are useful for developing high-precision planetary ephemerides of the solar system. These historical data are provided by the jet propulsion laboratory (JPL) or the Institut De Mecanique Celeste Et De Calcul Des Ephemerides (IMCCE). However, we find that the reference systems (realized by the fundamental catalogs FK3 (Third Fundamental Catalogue), FK4 (Fourth Fundamental Catalogue), and FK5 (Fifth Fundamental Catalogue), or Hipparcos), to which the observations are referred, are not given explicitly for some sets of data. The incompleteness of information prevents us from eliminating the systematic effects due to the different fundamental catalogs. The purpose of this paper is to specify clearly the reference catalogs of these observations with the problems in their records by using the JPL DE421 ephemeris. The data for the corresponding planets in the geocentric celestial reference system (GCRS) obtained from the DE421 are transformed to the apparent places with different hypothesis regarding the reference catalogs. Then the validations of the hypothesis are tested by two kinds of statistical quantities which are used to indicate the significance of difference between the original and transformed data series. As a result, this method is proved to be effective for specifying the reference catalogs, and the missed information is determined unambiguously. Finally these meridian data are transformed to the GCRS for further applications in the development of planetary ephemerides.

Caracterisation, modelisation et validation du transfert radiatif d'atmospheres non standard; impact sur les corrections atmospheriques d'images de teledetection

NASA Astrophysics Data System (ADS)

Zidane, Shems

This study is based on data acquired with an airborne multi-altitude sensor on July 2004 during a nonstandard atmospheric event in the region of Saint-Jean-sur-Richelieu, Quebec. By non-standard atmospheric event we mean an aerosol atmosphere that does not obey the typical monotonic, scale height variation employed in virtually all atmospheric correction codes. The surfaces imaged during this field campaign included a diverse variety of targets : agricultural land, water bodies, urban areas and forests. The multi-altitude approach employed in this campaign allowed us to better understand the altitude dependent influence of the atmosphere over the array of ground targets and thus to better characterize the perturbation induced by a non-standard (smoke) plume. The transformation of the apparent radiance at 3 different altitudes into apparent reflectance and the insertion of the plume optics into an atmospheric correction model permitted an atmospheric correction of the apparent reflectance at the two higher altitudes. The results showed consistency with the apparent validation reflectances derived from the lowest altitude radiances. This approach effectively confirmed the accuracy of our non-standard atmospheric correction approach. This test was particularly relevant at the highest altitude of 3.17 km : the apparent reflectances at this altitude were above most of the plume and therefore represented a good test of our ability to adequately correct for the influence of the perturbation. Standard atmospheric disturbances are obviously taken into account in most atmospheric correction models, but these are based on monotonically decreasing aerosol variations with increasing altitude. When the atmospheric radiation is affected by a plume or a local, non-standard pollution event, one must adapt the existing models to the radiative transfer constraints of the local perturbation and to the reality of the measurable parameters available for ingestion into the model. The main inputs of this study were those normally used in an atmospheric correction : apparent at-sensor radiance and the aerosol optical depth (AOD) acquired using ground-based sunphotometry. The procedure we employed made use of a standard atmospheric correction code (CAM5S, for Canadian Modified 5S, which comes from the 5S radiative transfer model in the visible and near infrared) : however, we also used other parameters and data to adapt and correctly model the special atmospheric situation which affected the multi-altitude images acquired during the St. Jean field campaign. We then developed a modeling protocol for these atmospheric perturbations where auxiliary data was employed to complement our main data-set. This allowed for the development of a robust and simple methodology adapted to this atmospheric situation. The auxiliary data, i.e. meteorological data, LIDAR profiles, various satellite images and sun photometer retrievals of the scattering phase function, were sufficient to accurately model the observed plume in terms of a unusual, vertical distribution. This distribution was transformed into an aerosol optical depth profile that replaced the standard aerosol optical depth profile employed in the CAM5S atmospheric correction model. Based on this model, a comparison between the apparent ground reflectances obtained after atmospheric corrections and validation values of R*(0) obtained from the lowest altitude data showed that the error between the two was less than 0.01 rms. This correction was shown to be a significantly better estimation of the surface reflectance than that obtained using the atmospheric correction model. Significant differences were nevertheless observed in the non-standard solution : these were mainly caused by the difficulties brought about by the acquisition conditions, significant disparities attributable to inconsistencies in the co-sampling / co-registration of different targets from three different altitudes, and possibly modeling errors and / or calibration. There is accordingly room for improvement in our approach to dealing with such conditions. The modeling and forecasting of such a disturbance is explicitly described in this document: our goal in so doing is to permit the establishment of a better protocol for the acquisition of more suitable supporting data. The originality of this study stems from a new approach for incorporating a plume structure into an operational atmospheric correction model and then demonstrating that the approach was a significant improvement over an approach that ignored the perturbations in the vertical profile while employing the correct overall AOD. The profile model we employed was simple and robust but captured sufficient plume detail to achieve significant improvements in atmospheric correction accuracy. The overall process of addressing all the problems encountered in the analysis of our aerosol perturbation helped us to build an appropriate methodology for characterizing such events based on data availability, distributed freely and accessible to the scientific community. This makes our study adaptable and exportable to other types of non-standard atmospheric events. Keywords : non-standard atmospheric perturbation, multi-altitude apparent radiances, smoke plume, Gaussian plume modelization, radiance fit, AOD, CASI

Microphysics of Magnetic Reconnection: Experiments on RSX and Simulation

NASA Astrophysics Data System (ADS)

Intrator, T. P.; Furno, I. G.; Hsu, S. C.; Lapenta, G.; Ricci, P.

2003-12-01

Using a unique LANL laboratory facility, the Reconnection Scaling Experiment (RSX), and a state-of-the-art LANL numerical code, CELESTE3D, we are beginning an experimental and numerical study of the microphysics of 2D and 3D "fast magnetic reconnection". RSX at Los Alamos National Laboratory is already operational and producing research plasmas. In RSX, the radial boundaries and thus the reconnection geometry are not constrained to two dimensions. It is capable of investigating 3D magnetic reconnection occurring in a free-boundary 3D linear geometry during the coalescence of two parallel current plasma channels, which are produced by using plasma gun technology. RSX can also scale the guide field (ion gyroradius) independently of other reconnection parameters. Frontier reconnection research invokes (1) `anomalous' microinstability-induced resistivity, which enhances dissipation rates inside the reconnection layer and (2) terms of the two-fluid generalized Ohm's law which introduce whistler and kinetic Alfvén wave dynamics. The two-fluid approach predicts (a) a two-spatial-scale spatial structure of the reconnection layer, with outer (inner) thickness equal to the ion (electron) skin depth and (b) Hall currents in the reconnection plane and out-of-plane magnetic field on the electron scale. We will show spatially resolved RSX experimental measurements of the dynamics of the reconnection layer, and take advantage of our scaling capabilities to address the applicability of the two-fluid approach.

Astronomy in Brazilian music and poetry

NASA Astrophysics Data System (ADS)

de Freitas Mourão, Ronaldo Rogério

2011-06-01

The rôle of astronomy in the Brazilian cultural diversity -though little known world- has been enormous. Thus, the different forms of popular music and erudite, find musical compositions and lyrics inspired by the stars, the eclipses in rare phenomena such as the transit of Venus in front of the sun in 1882, the appearance of Halley's Comet in 1910, in the Big Bang theory. Even in the carnival parades of the blocks at the beginning of the century astronomy was present. More recently, the parade of 1997, the samba school Unidos do Viradouro, under the direction of Joãozinho Trinta, offered a new picture of the first moments of the creation of the universe to join in the white and dark in the components of their school, the idea of matter and anti-matter that reigned in the early moments of the creation of the universe in an explosion of joy. Examples in classical music include Dawn of Carlos Gomes and Carta Celeste by Almeida Prado. Unlike The Planets by Gustav Holst -who between 1914 and 1916 composed a symphonical tribute to the solar system based on astrology- Almeida Prado composed a symphony that is not limited to the world of planets, penetrating the deep cosmos of galaxies. Using various resources of the technique for the piano on the clusters and static movements, violent conflicts between the records of super acute and serious instrument, harpejos cross, etc . . .

L^1 -optimality conditions for the circular restricted three-body problem

NASA Astrophysics Data System (ADS)

Chen, Zheng

2016-11-01

In this paper, the L^1 -minimization for the translational motion of a spacecraft in the circular restricted three-body problem (CRTBP) is considered. Necessary conditions are derived by using the Pontryagin Maximum Principle (PMP), revealing the existence of bang-bang and singular controls. Singular extremals are analyzed, recalling the existence of the Fuller phenomenon according to the theories developed in (Marchal in J Optim Theory Appl 11(5):441-486, 1973; Zelikin and Borisov in Theory of Chattering Control with Applications to Astronautics, Robotics, Economics, and Engineering. Birkhäuser, Basal 1994; in J Math Sci 114(3):1227-1344, 2003). The sufficient optimality conditions for the L^1 -minimization problem with fixed endpoints have been developed in (Chen et al. in SIAM J Control Optim 54(3):1245-1265, 2016). In the current paper, we establish second-order conditions for optimal control problems with more general final conditions defined by a smooth submanifold target. In addition, the numerical implementation to check these optimality conditions is given. Finally, approximating the Earth-Moon-Spacecraft system by the CRTBP, an L^1 -minimization trajectory for the translational motion of a spacecraft is computed by combining a shooting method with a continuation method in (Caillau et al. in Celest Mech Dyn Astron 114:137-150, 2012; Caillau and Daoud in SIAM J Control Optim 50(6):3178-3202, 2012). The local optimality of the computed trajectory is asserted thanks to the second-order optimality conditions developed.

Profiles of environmental contaminants in hawksbill turtle egg yolks reflect local to distant pollution sources among nesting beaches in the Yucatán Peninsula, Mexico.

PubMed

Muñoz, Cynthia C; Vermeiren, Peter

2018-04-01

Knowledge of spatial variation in pollutant profiles among sea turtle nesting locations is limited. This poses challenges in identifying processes shaping this variability and sets constraints to the conservation management of sea turtles and their use as biomonitoring tools for environmental pollutants. We aimed to increase understanding of the spatial variation in polycyclic aromatic hydrocarbon (PAH), organochlorine pesticide (OCP) and polychlorinated biphenyl (PCB) compounds among nesting beaches. We link the spatial variation to turtle migration patterns and the persistence of these pollutants. Specifically, using gas chromatography, we confirmed maternal transfer of a large number of compounds (n = 68 out of 69) among 104 eggs collected from 21 nests across three nesting beaches within the Yucatán Peninsula, one of the world's most important rookeries for hawksbill turtles (Eretmochelys imbricata). High variation in PAH profiles was observed among beaches, using multivariate correspondence analysis and univariate Peto-Prentice tests, reflecting local acquisition during recent migration movements. Diagnostic PAH ratios reflected petrogenic origins in Celestún, the beach closest to petroleum industries in the Gulf of Mexico. By contrast, pollution profiles of OCPs and PCBs showed high similarity among beaches, reflecting the long-term accumulation of these pollutants at regional scales. Therefore, spatial planning of protected areas and the use of turtle eggs in biomonitoring needs to account for the spatial variation in pollution profiles among nesting beaches. Copyright © 2018 Elsevier Ltd. All rights reserved.

Resonances and Tides in Natural Satellites Systems. (Breton Title: Ressonâncias e Marés em Sistemas de Satélites Naturais.) Resonancias y Mareas en Sistemas de Satélites Naturales

NASA Astrophysics Data System (ADS)

Callegari, Nelson, Jr.

2006-12-01

In this work we describe some aspects of the dynamics of the mean-motion resonances. Emphasis to the case of resonances between regular satellites of the giant planets will be given, even so some aspects of the physics of the resonances in extra-solar planetary systems are also briefly treated. The role of the resonances in satellites systems is discussed through examples, showing how certain resonances, and its relations with the tidal dissipation effects, can be the key of the explanation of some phenomena still not explained in the Solar System. Amongst some examples we highlight the problem of the resurfacing of Enceladus, the existence of active volcanoes in Io, and the possible existence of the subsurface ocean in Europe. This work has as objective the divulgation of some topics in Celestial Mechanics and Planetary Sciences for an undergraduate public in exact sciences, as Astronomy and Physics, and not their detailed description. Neste trabalho descrevemos alguns aspectos da dinâmica de ressonâncias de movimentos médios. Será dada ênfase maior ao caso de ressonâncias entre satélites regulares dos planetas gigantes, embora alguns aspectos da física das ressonâncias em sistemas planetários extra-solares também sejam discutidos brevemente. A importância do estudo de ressonâncias em sistemas de satélites é discutida mais detalhadamente através de exemplos, mostrando como certas ressonâncias e suas relações com efeitos de dissipação de maré podem ser a chave de parte da explicação de alguns fenômenos ainda não explicados no Sistema Solar. Dentre vários exemplos destacamos o problema da remodelagem da superfície do satélite Enceladus, a existência de vulcões ativos em Io, e a possível existência do oceano subterrâneo em Europa. Este trabalho tem como objetivo a divulgação de alguns tópicos de Mecânica Celeste e Planetologia para um público de nível de graduação em disciplinas na área de exatas, em especial Astronomia e F�

Contraction et filamentation des decharges micro-ondes entretenues a la pression atmospherique: Application a la detoxication des gaz a effet de serre

NASA Astrophysics Data System (ADS)

Kabouzi, Yassine

The remediation of greenhouse gases, such as perfluorinated compounds (PFCs), constitutes a major environmental concern. Plasmas operating at atmospheric pressure offer an efficient technology for the control of toxic and greenhouse gas emission. The two main objectives of the thesis were to investigate the mechanisms of contraction and filamentation in atmospheric-pressure microwave discharges, and to examine their influence on the plasma abatement process of PFC gases in these discharges. The finite thermal conductivity of the gas discharge is responsible for the gas nonuniform heating leading to a contracted discharge column. The gas thermal conductivity and the penetration depth of the microwave electric field in the plasma are shown to set the value of the plasma radius. The degree of contraction and filamentation of microwave discharges can be controlled, and even reduced, by modulating adequately the incident microwave power. The relaxation times of heat conduction and heat release are actually observed to be of the same magnitude, and correspond to the modulation period for which the discharge shows less contraction. PFC molecules are eliminated through their fragmentation by inelastic collisions with electrons and the subsequent oxidation of these fragments. Reformation of PFC molecules is the main process limiting the abatement efficiency in atmospheric-pressure microwave discharges. As a result of discharge radial contraction, a relative "colder" space between the plasma filament and the discharge tube wall favors PFC reformation and, therefore, lowers the destruction efficiency. The PFC destruction efficiency is found to increase with absorbed microwave power. Surface-wave microwave discharges sustained at atmospheric pressure prove to be an efficient and ecological solution for emission reduction of greenhouse gases.

International Celestial Reference Frame (ICRF): mantenimiento y extensión

NASA Astrophysics Data System (ADS)

Ma, C.; Arias, E. F.; Eubanks, T.; Fey, A. L.; Gontier, A.-M.; Jacobs, C. S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.

A partir de enero de 1998 el sistema de referencia celeste convencional está representado por el International Celestial Reference System (ICRS) y materializado a través de las coordenadas VLBI del conjunto de radiofuentes extragalácticas que conforman el International Celestial Reference Frame (ICRF). La primera realización del ICRF, fue elaborada en 1995 por un grupo de expertos designado por la IAU, la que encomendó al International Earth Rotation Service el mantenimiento del ICRS, del ICRF y del vínculo con marcos de referencia en otras frecuencias. Una primera extensión del ICRF se realizó entre abril y junio de 1999, con el objetivo primario de proveer posiciones de radiofuentes extragalácticas observadas a partir de julio de 1995 y de mejorar las posiciones de las fuentes ``candidatas" con la inclusión de observaciones adicionales. Objetivos secundarios fueron monitorear a las radiofuentes para verificar que siguen siendo adecuadas para realizar al ICRF y mejorar las técnicas de análisis de datos. Como resultado del nuevo análisis se obtuvo una solución a partir de la cual se construyó la primera extensión del ICRF, denominada ICRF - Ext.1. Ella representa al ICRS, sus fuentes de definición se mantienen con las mismas posiciones y errores que en la primera realización del ICRF; las demás radiofuentes tienen coordenadas mejor determinadas que en ICRF; el marco de referencia se densificó con el agregado de 59 nuevas radiofuentes.

Impact of Surface Roughness and Soil Texture on Mineral Dust Emission Fluxes Modeling

NASA Technical Reports Server (NTRS)

Menut, Laurent; Perez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, Stephane

2013-01-01

Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

The General Laws of Chemical Elements Composition Dynamics in the Biosphere

NASA Astrophysics Data System (ADS)

Korzh, Vyacheslav D.

2013-04-01

The key point of investigation of the specificity of the biosphere elemental composition formation is determination of patterns of redistribution of elemental average concentrations among various phases, like solid - liquid ( the lithosphere - the hydrosphere), which occurs as a result of a global continuous processing of inert matter by living substances. Our task here is to investigate this process in the system "lithosphere - hydrosphere" in view of the integrated involvement of living material in it. This process is most active in biogeochemical barriers, i.e. in places of "the life condensation" and runs under a nonlinear regularity that has been unknown before. It is established that this process results in a general relative increase in concentrations of chemical elements in the solid phase in proportion as their prevalence in the environment is reduced. This process running in various natural systems has practically the same parameter of nonlinearity (v) approximately equal to 0.7. For proto-lithosphere -"living material" - soil v = 0.75. For river - "living material" - ocean v = 0.67. For the contemporary factual awareness level these estimations of nonlinearity indices are practically negligible. Hence, it is for the first time that the existence of a universal constant of nonlinearity of elemental composition evolution in the biosphere has been proved and its quantitative evaluation has been made. REFERENCES 1. Korzh V.D. 1974. Some general laws governing the turnover of substance within the ocean-atmosphere-continent-ocean cycle. // Journal de Recherches Atmospheriques. Vol. 8. P. 653-660. 2. Korzh V.D. 2008. The general laws in the formation of the elemental composition of the Hydrosphere and Biosphere.// J. Ecologica, Vol. XV, P. 13-21. 3. Korzh V.D. 2012. Determination of general laws of elemental composition in Hydrosphere // Water: chemistry & ecology, Journal of water science and its practical application. # 1, P.56-62.

Comparison of CALIPSO-Like, LaRC, and MODIS Retrievals of Ice Cloud Properties over SIRTA in France and Florida during CRYSTAL-FACE

NASA Technical Reports Server (NTRS)

Chiriaco, M.; Chepfer, H.; Haeffelin, M.; Minnis, P.; Noel, V.; Platnick, S.; McGill, M.; Baumgardner, D.; Dubuisson, P.; Pelon, J.;

Prevalence and Correlates of ‘Agua Celeste’ Use among Female Sex Workers who Inject Drugs in Ciudad Juarez, Mexico

PubMed Central

Morris, Meghan D.; Case, Patricia; Robertson, Angela M.; Lozada, Remedios; Vera, Alicia; Clapp, John D.; Medina-Mora, Maria Elena; Strathdee, Steffanie A.

2011-01-01

Background Agua celeste, or “heavenly water,” is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of Agua Celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Methods Between 2008 and 2010, baseline data from FSW-IDUs ≥ 18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Results Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14–23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8 hours per day, and younger age. Discussion We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. PMID:21441001

Volcanic/Tectonic Characteristics of First and Second Order Segments and Ridge Discontinuities `Under the Hot-spot Influence' - TOBI Imagery from the Central Indian Ridge (CIR) Adjacent to the Rodriguez System.

NASA Astrophysics Data System (ADS)

Parson, L.; Murton, B.; Sauter, D.; Curewitz, D.; Okino, K.; German, C.; Leven, J.

2001-12-01

Deeptow sidescan sonar data (TOBI, 30kHz) acquired over more than 200 km of the Central Indian Ridge during RRS Charles Darwin cruise CD127 reveal an abundance of neovolcanic activity throughout both spreading segments and ridge non-transform discontinuities alike. Imagery of the previously unsurveyed northern section of the CIR immediately south of the Marie Celeste Fracture Zone confirms the presence of a shallow, magmatically inflated second order segment that is only recently rifted, with a rift floor surfaced throughout by virtually untectonised planar sheet flow units. First and second order segments exhibit a significant component of sheeted extrusives, ponded or in lake form, abutting or overstepped by hummocky and mounded pillow constructs. Non-transform discontinuities are commonly cut by fresh axial volcanic ridges oblique to both axial trend and offset. The depths of segment centers range from 2600m to more than 3700m, and segment forms include robust, hour-glass and rifted/starved end-members - but their overall extrusive pattern is strikingly invariant. Fracture Zone offsets of up to 65 kilometres are tectonically dominated, but their intersections with the axis are often mantled by multiple sheet flows rather than the relatively low proportions of sediment cover. The largest offsets are marked by outcrops of multiple, subparallel displacement surfaces, actively eroding transverse ridges, and ridge transform intersections with classic propagation/recession fabrics - each suggesting some instability in regional plate kinematics. While it is tempting to speculate that the Rodrigues hotspot appears to have a regional effect, enhancing magmatic delivery to the adjacent ridge and offset system, the apparent breadth of influence from what is assumed to be a rather feeble mantle anomaly is problematic.

A Concepção de Universo entre Alunos do Ensino Médio de São Paulo e suas Fontes de Aquisição

NASA Astrophysics Data System (ADS)

Araújo, M. A. A.; Elias, D. C. N.; Amaral, L. H.; Araújo, M. S. T.; Voelzke, M. R.

2006-08-01

Nesse trabalho procurou-se identificar por meio de um questionário as concepções de Universo, de espaço e tempo que sustentam a visão de mundo de um grupo de 270 estudantes de Ensino Médio, pertencentes a três escolas de São Paulo. As questões relacionadas aos conhecimentos prévios dos estudantes permitiram constatar que há pouco conhecimento acerca dos temas investigados, destacando-se que apenas 20% dos alunos foram capazes de relacionar as semanas com as fases da lua, enquanto 28% associaram as estações do ano à inclinação do eixo de rotação da Terra e 23% tinham noções das distâncias entre objetos celestes próximos da Terra. Enquanto 56% conseguiram relacionar o Big Bang com a origem do Universo, verificou-se que 37% reconheciam ano-luz como unidade de distância e 60% concebiam o Sol como uma estrela. No que se refere às fontes de aquisição que proporcionaram esses conhecimentos, apesar de 60% dos alunos indicarem a escola como principal fonte dos conhecimentos de Ast! ronomia, verificou-se claramente que para a maioria dos alunos seus conceitos ainda são inadequados, havendo necessidade de aprimoramento da abordagem desses conteúdos, pois apesar de popular, a Astronomia ainda é veiculada de maneira pouco esclarecedora e com imprecisões. Nesse contexto, são discutidas algumas possíveis contribuições que podem ser dadas para o ensino de Astronomia pelo uso das ferramentas computacionais nas escolas.

Como os Alunos do Ensino Médio da Rede Estadual de São Paulo obtém Conhecimentos Astronômicos?

NASA Astrophysics Data System (ADS)

da Cunha, W. S.; Voelzke, M. R.; Amaral, L. H.

2005-08-01

Atualmente vivencia-se um mundo globalizado onde os computadores e a internet permitiram um acesso rápido e seguro a todo tipo de informação e conhecimento. O presente trabalho visa analisar a maneira pela qual alunos de segundo grau da rede estadual da cidade de São Paulo obtiveram, caso tenham, conhecimentos básicos de astronomia quanto aos fenômenos celestes que os rodeiam, tais como a sucessão dos dias e das estações do ano, além de questioná~los sobre fatos genéricos tais como: o que vem a ser o Sol, o Big Bang, o que ocasionou a extinção dos dinossauros. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, o qual foi aplicado no primeiro colegial diurno da Escola Estadual Guilherme de Almeida. Num espaço amostral de 44 alunos constatou-se que 41% dos alunos adquiriram seus conhecimentos astronômicos na escola e 59% através da mídia em geral. Neste mesmo espaço amostral apenas 11% dos alunos usaram computadores na escola, 41% na residência, 5% no trabalho e 43% não utilizaram. O presente estudo revelou também que para 50% dos alunos o professor jamais utilizou um programa de computador a respeito de astronomia ou fez alguma apresentação sobre o tema. Embora em sua fase inicial este estudo revela claramente que a maioria dos alunos não obtém na escola seus conhecimentos astronômicos, estes provém de fontes não especificamente didático-pedagógicas tais como filmes e revistas populares que não raramente geram conhecimentos incompletos e em muitos casos inclusive falhos.

An analysis of the convergence of Newton iterations for solving elliptic Kepler's equation

NASA Astrophysics Data System (ADS)

Elipe, A.; Montijano, J. I.; Rández, L.; Calvo, M.

2017-12-01

In this note a study of the convergence properties of some starters E_0 = E_0(e,M) in the eccentricity-mean anomaly variables for solving the elliptic Kepler's equation (KE) by Newton's method is presented. By using a Wang Xinghua's theorem (Xinghua in Math Comput 68(225):169-186, 1999) on best possible error bounds in the solution of nonlinear equations by Newton's method, we obtain for each starter E_0(e,M) a set of values (e,M) \\in [0, 1) × [0, π ] that lead to the q-convergence in the sense that Newton's sequence (E_n)_{n ≥ 0} generated from E_0 = E_0(e,M) is well defined, converges to the exact solution E^* = E^*(e,M) of KE and further \\vert E_n - E^* \\vert ≤ q^{2^n -1} \\vert E_0 - E^* \\vert holds for all n ≥ 0. This study completes in some sense the results derived by Avendaño et al. (Celest Mech Dyn Astron 119:27-44, 2014) by using Smale's α -test with q=1/2. Also since in KE the convergence rate of Newton's method tends to zero as e → 0, we show that the error estimates given in the Wang Xinghua's theorem for KE can also be used to determine sets of q-convergence with q = e^k \\widetilde{q} for all e \\in [0,1) and a fixed \\widetilde{q} ≤ 1. Some remarks on the use of this theorem to derive a priori estimates of the error \\vert E_n - E^* \\vert after n Kepler's iterations are given. Finally, a posteriori bounds of this error that can be used to a dynamical estimation of the error are also obtained.

Observations of Time Variable Magnitude Events of Phoebe, Ariel, and Titania

NASA Astrophysics Data System (ADS)

Miller, Charles; Chanover, N. J.; Holtzman, J. A.; Verbiscer, A. J.

2007-10-01

Visual observations of Saturn's moon Phoebe and Uranus' moons Ariel and Titania were made from the Apache Point Observatory (APO). Phoebe was observed with the APO 1 meter telescope over a two month period from 06 January to 04 March 2005, bracketing the zero-phase opposition on 13 January 2005. Phoebe was observed at Sun-Phoebe-Earth phase angles as low as 0.05 degrees on consecutive nights immediately before and after opposition in V, B, R, and I filters. Light curves of the opposition surge, the brightness increase that occurs as the phase angle drops below 0.10 degrees, are presented from this data. The data were processed using standard IRAF aperture photometry image processing techniques. The magnitude and duration of the opposition surge provide clues about the grain size of surface particles on Phoebe. Observations were also made of Uranian moons during mutual occultations in August 2007. Mutual satellite occultations are taking place throughout 2007 as Uranus passes through its equinox, which occurs once every 42 years. The timing and flux variation of satellite occultations provide a check on the accuracy of satellite orbital models. Light curves for Ariel and Titania in R and I filters as they are occulted by Umbriel are presented from data acquired with the APO 1 meter and 3.5 meter telescopes. Comparison is made to the predicted total flux reduction and event timing for each occultation as calculated by the Institut de Mecanique Celeste et de Calcul des Ephemerides (IMCCE) and implications of the results on determination of the relative orbital inclinations of Umbriel, Ariel, and Titania are discussed. This work was supported by an NMSU Space and Aerospace Research Cluster Graduate Fellowship .

Aerosol Transport Over Equatorial Africa

NASA Technical Reports Server (NTRS)

Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

1999-01-01

Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El

Carbon monoxide observations from ground stations in France and Europe and long trends in the free troposphere

NASA Astrophysics Data System (ADS)

Chevalier, A.; Gheusi, F.; Attié, J.-L.; Delmas, R.; Zbinden, R.; Athier, G.; Cousin, J.-M.

2008-02-01

Continuous CO measurements performed at 3 high-altitude stations in France are analyzed for the first time. Data are provided by the new PAES (Pollution Atmospherique à l'Echelle Synoptique) network since 2002 for the Puy de Dôme and 2004 for the Pic du Midi and the Donon. CO measurements of 5 another European stations have been analysed to put the PAES stations in an European perspective. The January 2002-April 2005 CO mean levels of surface stations capture the stratification revealed by climatological CO profiles from the airborne observation system MOZAIC (Measurement of OZone and water vapour by Airbus In-service Aircraft). The deviation between the free tropospheric reference MOZAIC and surface data above 2000 m is less than 10% and this deviation can be explained in term of spatial variability, as evidenced by MOPITT CO retrievals at 700 hPa. This suggests that, averaged at a seasonal time scale (4 months), surface data at stations above 2000 m are representative of background CO concentration. This paper focuses then on trends since the 1980s-1990s. The comparison between old (1982-1983) and recent CO mixing ratio (2005) at the Pic du Midi leads to a 10% decrease, consistent with the continuous data series at Zugspitze (ZSP) from 1991 to 2004. This decrease was found to be mainly due to a negative trend of January-April mean levels. The decrease in CO sources over France and Europe appears to be responsible for that trend. The stable values of June-September mean levels suggest that the summertime oxidizing capacity of the atmosphere related to OH radicals is important enough to counterbalance any CO inputs into the troposphere. Our study shows a recent change in CO evolution since 2000 over Western Europe, with a slowed down decrease in CO concentration. Studying specifically the interactions between CO, CH4 and OH turns out to be needed, however, to find definitive explanations to those observations.

Satellite Ocean-Color Validation Using Ships of Opportunity. Chapter 5

NASA Technical Reports Server (NTRS)

Frouin, Robert; Cutchin, David L.; Gross-Colzy, Lydwine; Poteau, Antoine; Deschamps, Pierre-Yves

2003-01-01

The investigation s main objective is to collect from platforms of opportunity (merchant ships, research vessels) concomitant normalized water-leaving radiance and aerosol optical thickness data over the world s oceans. A global, long-term data set of these variables is needed to verify whether satellite retrievals of normalized water-leaving radiance are within acceptable error limits and, eventually, to adjust atmospheric correction schemes. To achieve this objective, volunteer officers, technicians, and scientists onboard the selected ships collect data from portable SIMBAD and Advanced SIMBAD (SIMBADA) radiometers. These instruments are specifically designed for evaluation of satellite-derived ocean color. They measure radiance in spectral bands typical of ocean-color sensors. The SIMBAD version measures in 5 spectral bands centered at 443, 490, 560, 670, and 870 nm, and the Advanced SIMBAD version in 11 spectral bands centered at 350, 380, 412, 443, 490, 510, 565, 620, 670, 750, and 870 nm. Aerosol optical thickness is obtained by viewing the sun disk like a classic sun photometer. Normalized water-leaving radiance, or marine reflectance, is obtained by viewing the ocean surface through a vertical polarizer in a specific geometry (nadir angle of 45o and relative azimuth angle of 135deg) to minimize direct sun glint and reflected sky radiation. The SIMBAD and SIMBADA data, after proper quality control and processing, are delivered to the SIMBIOS project office for inclusion in the SeaBASS archive. They complement data collected in a similar way by the Laboratoire d'Optique Atmospherique of the University of Lille, France. The SIMBAD and SIMBADA data are used to check the radiometric calibration of satellite ocean-color sensors after launch and to evaluate derived ocean-color variables (i.e., normalized water-leaving radiance, aerosol optical thickness, and aerosol type). Analysis of the SIMBAD and SIMBADA data provides information on the accuracy of satellite

Laboratory estimate of the regional shortwave refractive index and single scattering albedo of mineral dust from major sources worldwide

NASA Astrophysics Data System (ADS)

Di Biagio, C.; Formenti, P.; Caponi, L.; Cazaunau, M.; Pangui, E.; Journet, E.; Nowak, S.; Caquineau, S.; Andreae, M. O.; Kandler, K.; Saeed, T.; Piketh, S.; Seibert, D.; Williams, E.; Balkanski, Y.; Doussin, J. F.

2017-12-01

Mineral dust is one of the most abundant aerosol species in the atmosphere and strongly contributes to the global and regional direct radiative effect. Still large uncertainties persist on the magnitude and overall sign of the dust direct effect, where indeed one of the main unknowns is how much mineral dust absorbs light in the shortwave (SW) spectral range. Aerosol absorption is represented both by the imaginary part (k) of the complex refractive index or the single scattering albedo (SSA, i.e. the ratio of the scattering to extinction coefficient). In this study we present a new dataset of SW complex refractive indices and SSA for mineral dust aerosols obtained from in situ measurements in the 4.2 m3 CESAM simulation chamber at LISA (Laboratoire Interuniversitaire des Systemes Atmospheriques) in Créteil, France. Investigated dust aerosol samples were issued from major desert sources worldwide, including the African Sahara and Sahel, Eastern Asia, the Middle East, Southern Africa, Australia, and the Americas, with differing iron oxides content. Results from the present study provide a regional mapping of the SW absorption by dust and show that the imaginary part of the refractive index largely varies (by up to a factor 6, 0.003-0.02 at 370 nm and 0.001-0.003 at 950 nm) for the different source areas due to the change in the particle iron oxide content. The SSA for dust varies between 0.75-0.90 at 370 nm and 0.95-0.99 at 950 nm, with the largest absorption observed for Sahelian and Australian dust aerosols. Our range of variability for k and SSA is well bracketed by already published literature estimates, but suggests that regional‒dependent values should be used in models. The possible relationship between k and the dust iron oxides content is investigated with the aim of providing a parameterization of the regional‒dependent dust absorption to include in climate models.

Etude de l'impact de la valorisation energetique de pneus hors d'usage, dans une cimenterie, sur les emissions gazeuses par modelisation de la dispersion atmospherique

NASA Astrophysics Data System (ADS)

Bredin, Nathalie

La génération incéssante de déchets nécessite le développement de nouvelles technologies, telle que la valorisation énergétique, pour en disposer. Une filière appropriée pour valoriser énergétiquement les déchets est le procédé cimentier. L'industrie du ciment est une des grandes consommatrices d'énergie. La température nécessaire à la préparation du ciment se situe aux environs de 1450°C pour faire réagir la matière première (cru) qui est sous forme poudreuse et constituée principalement de roches calcaires, argileuses, schisteuses,... Les gaz de combustion ont un long temps de résidence dans les fours. De plus, le mode de fonctionnement des fours est responsable d'un effet de lessivage des gaz acides par le cru alcalin. Ces propriétés font du procédé cimentier un bon candidat pour la valorisation énergétique des déchets. Les déchets interessants pour les cimenteries sont, entre autres, les huiles usées, les solvants usés et les pneus usés qui ont un pouvoir calorifique équivalent à celui du charbon. Les rejets à l'atmosphère des cimenteries sont principalement des émissions gazeuses. Ainsi, l'impact de la valorisation de pneus usés sur les émissions gazeuses de la cimenterie Saint-Laurent de Joliette a été étudié, à l'aide de l'outil qu'est la modélisation de la dispersion atmosphérique. Le modèle utilisé ISC-ST2, Industrial Source Complex-Short Term, est de type gaussien. L'analyse des concentrations maximales horaires et moyennes sur différentes périodes de temps (1 heure, 8 heures, ..., 1 an) des émissions gazeuses dans l'air ambiant montre que celles-ci sont en deçà des normes émises par le gouvernement québécois et par la Communauté Urbaine de Montréal. L'étude de la distribution géographique des polluants, d'après les concentrations annuelles, dans un rayon de 5 km autour de la cimenterie montre que le fait d'utiliser des pneus comme combustible de substitution n'a qu'un faible impact sur la concentration des contaminants au niveau du sol. L'étude du modèle gaussien de dispersion a permis de mettre au point un nouvel outil: la corrélation existant entre les concentrations latérales et verticales des polluants dans le panache. Cet outil utilisé pour étudier les schémas de dispersion atmosphérique de Turner en milieu rural, et de Briggs en milieux urbain et rural, montre que, en milieu rural, le schéma de dispersion proposé par Briggs présente une dispersion plus importante que celui de Turner pour les classes neutres et instables et moins importantes pour les classes stables. La comparaison des schémas de Briggs (rural et urbain) confirme que la dispersion en milieu urbain est plus importante qu'en milieu rural.

Apparent Motion of the Sun, Shadows of Objects and Measurement of Time in the View of Seventh Grade Students of Middle School. (Breton Title: Movimento Aparente do Sol, Sombras dos Objetos e Medição do Tempo na Visão de Alunos do Sétimo Ano do Ensino Fundamental.) Movimiento Aparente del Sol, Sombras de los Objetos y Medición del Tiempo en la Visión de Estudiantes del Séptimo Grado del Ciclo Pirmario

NASA Astrophysics Data System (ADS)

Iria Machado, Daniel

2013-07-01

The apparent motion of the Sun on the celestial sphere and the behavior of the shadows of objects over time are observable phenomena in everyday life. However, students often do not have a proper understanding of such occurrences, and can even display misconceptions about them. Therefore, we performed a research in order to know students' notions about these subjects and to evaluate the contribution to their understanding brought about by an activity performed with an interactive sundial in an informal learning environment. We investigated the ideas of 43 students from the seventh grade of middle school by applying a test with open questions before and after an activity with an analemmatic sundial, conducted by a monitor. A significant proportion of students were initially unaware of most of the phenomena treated. The intervention performed helped the students to assimilate new concepts, providing the contact with new phenomena and to a lesser degree, the development of explanations about them, indicating an educational potential of this action. However, the contribution to the understanding of some of the ideas explored was small, pointing to the need to make additional observations, studies and discussions. O movimento aparente do Sol na esfera celeste e o comportamento das sombras dos objetos com o passar do tempo são fenômenos observáveis no dia a dia. No entanto, muitas vezes os estudantes não possuem uma compreensão adequada de tais ocorrências, podendo inclusive exibir concepções alternativas a seu respeito. Por isso, efetuou-se uma pesquisa com o intuito de conhecer as noções dos alunos sobre esses temas e avaliar a contribuição para seu entendimento propiciada por uma atividade feita com um relógio de Sol interativo, em um ambiente de ensino informal. Foram investigadas as ideias de 43 alunos do sétimo ano do Ensino Fundamental mediante a aplicação de um teste com questões abertas antes e depois de uma atividade com um relógio de Sol

Improvement of a device for detection and characterization of certain atmospheric pollutants. Final report. Perfectionnement d'un appareillage de detection et de caracterisation de certains pollutants atmospheriques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesseyre, Y.

The study allowed development of an original measuring system for mobility, involving simultaneously a repulsive electrical field and a continuous gas flow. It made it possible to define a model to calculate ionic transparency of grates, taking into account electrical fields below and above them, ion mobility, speed of gas flow and geometric transparency. Calculation of the electrical field proceeded in a plane-plane system, taking into account the space load and diffusion; a graphic method was developed to determine the field, thus avoiding numerical integration of the diffusion equation. The tracings of the mobility spectra obtained in different gases mademore » it possible to determine characteristic discrete mobility values comparable to those observed by other more sophisticated systems for measuring mobilities, such as the flight time systems. Detection of pollutants in weak concentration in dry air was shown. However, the presence of water vapor in the air forms agglomerates around the ions formed, reducing resolution of the system and making it less applicable under normal atmospheric conditions.« less

Ground based Mid-IR Observations of Temporally Varying Ethylene Emission on Jupiter

NASA Astrophysics Data System (ADS)

Romani, P. N.; Jennings, D. E.; Bjoraker, G. L.; Sada, P. V.; Boyle, R.; McCabe, G.

2003-05-01

Ethylene (C2H4)is an important species in our understanding of hydrocarbon photochemistry in the atmospheres of the giant planets. It also provides a sensitive probe of conditions at the 10-microbar level in Jupiter's atmosphere, a region that is strongly influenced by aurora. We performed high-resolution spectral observations of C2H4 at 10.53 microns (949.5 cm-1) on Jupiter with Celeste, a Goddard-developed cryogenic echelle spectrometer, during October-November 1998 at the McMath-Pierce telescope of the National Solar Observatory at Kitt Peak and during June 2000 at the IRTF at Mt. Kea in Hawai'i. We observed C2H4 line emission in the equatorial region and enhanced emission in the auroral latitudes. We modeled the emission using photochemical model profiles and either multiplied the model profile by a constant factor, adjusted the temperature in the isothermal region of the atmosphere, or adjusted the pressure level where the large thermal gradient starts. Analysis of the southern and northern auroral region emission yielded similar results with the exception of one day (21 June 2000) in the northern hemisphere "hot spot: (LIII 180 degrees). On this day the C2H4 emission was exceptionally bright. To match the emission required either multiplying the photochemical model profile by 25, or increasing the isothermal region temperature from 168K to 261K, or lowering the start of the temperature gradient region to 0.055 mbar. Of these three possibilities the increase in C2H4 abundance profile provided the poorest fit. Since the C2H4 emission on either side of this day was lower, and similar to each other, whatever mechanism that caused the increase in emission had to "turn on and off" within 48 hours. Similar short term behavior has been seen with Cassini-CIRS (see abstract by Sada et al.) This work is supported by the NASA Planetary Astronomy Program.

Uma Visão do Universo Segundo um Grupo de Alunos do Ensino Médio de São Paulo

NASA Astrophysics Data System (ADS)

Elias, D. S.; Araújo, M.; Amaral, L. H.; Voelzke, M. R.; Araújo, M.

2005-08-01

A astronomia, embora seja uma ciência popular, com inúmeras descobertas de interesse público, ainda é apresentada desconsiderando-se os aspectos históricos e científicos relacionados ao seu desenvolvimento, sendo geralmente veiculada nos meios de comunicação de maneira pouco esclarecedora e não raro com imprecisões. Neste trabalho analisou-se a concepção de um grupo de estudantes de Ensino Médio sobre conceitos de astronomia, visando identificar sua visão de mundo a respeito do Universo, envolvendo idéias sobre espaço e tempo. Para issso, foi aplicado um questionário em três escolas da grande São Paulo em um espaço amostral de 270 alunos. Constatou-se que, embora o ensino de astronomia esteja previsto nos PCNEM, os resultados obtidos na pesquisa mostram que há grande deficiência no conhecimento dos temas investigados. Nesse sentido, verificou-se que apenas 20% dos alunos eram capazes de relacionar a sucessão das semanas com as fases da lua, enquanto 28% associaram as estações do ano à inclinação do eixo de rotação da Terra. Por outro lado, somente 23% dos alunos tinham noções das distâncias entre os objetos celestes próximos da Terra e 56% conseguiram relacionar o Big Bang com a origem do Universo. Finalmente, constatou-se que 37% reconheciam o ano-luz como uma unidade de distância e 60% reconheciam o Sol como sendo uma estrela. Apesar de 60% dos alunos indicarem que a escola é a principal fonte para aquisição dos conhecimentos de astronomia, conclui-se que seus conceitos nessa área ainda são inadequados, havendo necessidade de ampliação e aprimoramento da abordagem desses conteúdos nos ambientes escolares.

Accurate free and forced rotational motions of rigid Venus

NASA Astrophysics Data System (ADS)

Cottereau, L.; Souchay, J.; Aljbaae, S.

2010-06-01

Context. The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting because it can be compared with that of Earth for which such a modelling has already been achieved at the milli-arcsecond level. Aims: We aim to complete a previous study, by determining the polhody at the milli-arcsecond level, i.e. the torque-free motion of the angular momentum axis of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view. Methods: We use the same theoretical framework as Kinoshita (1977, Celest. Mech., 15, 277) did to determine the precession-nutation motion of a rigid Earth. It is based on a representation of the rotation of a rigid Venus, with the help of Andoyer variables and a set of canonical equations in Hamiltonian formalism. Results: In a first part we computed the polhody, we showed that this motion is highly elliptical, with a very long period of 525 cy compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we precisely computed the Oppolzer terms, which allow us to represent the motion in space of the third Venus figure axis with respect to the Venus angular momentum axis under the influence of the solar gravitational torque. We determined the corresponding tables of the nutation coefficients of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We showed that the nutation coefficients for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration, which revealed the indirect planetary effects.

Evidence for lateral mantle plume flow feeding the Central Indian Ridge

NASA Astrophysics Data System (ADS)

Murton, B. J.; Tindle, A. G.

2003-04-01

The Central Indian Ridge exhibits morphological and geochemical features indicating lateral flow of shallow plume asthenosphere from the Reunion hot-spot to the ridge axis. South of the Marie Celeste fracture zone, at 18.25°S, the Central Indian Ridge is bound by a southward closing, “V”-shaped region of shallow crust that extends for over 800 km. Over this distance, the ridge axis deepens to the south and is also affected by left-stepping offsets that bring it towards the west. The northern end of the ridge, which is closest to the island of La'Réunion, is shallowest and dominated by an inflated segment with associated sheet flows covering over 50 square kilometres. These morphological features are usually associated with ridge-hot-spot interaction. However, the nearest active hot-spot lies over 1100 km to the west beneath the island of La'Réunion. Geochemical trends for basalts erupted along the Central Indian Ridge demonstrate a gradient of northward decreasing MgO and increasing SiO2, indicating a relationship between shallower crust and increased magmatic fractional crystallisation. Superimposed on this gradient is an excess increase in incompatible element ratios, indicative of mantle enrichment to the north. The enrichment correlates with the spreading-parallel distance between the ridge axis and the edge of the "V"-shaped region of anomalously shallow crust. Locally, the enriched mantle component is found preferentially at third-order ridge offsets and adjacent to the rift walls demonstrating melting of a compositionally stratified, spinel-lherzolite mantle. These features are evidence for shallow, lateral flow of enriched hot-spot asthenosphere at a velocity of ~333 mm yr-1 and with a flux of at least 50 m3 s-1, through a mantle 'worm', towards the ridge axis where it migrates south at a rate of 54 - 67 mm per year. The trend of the geochemical enrichment points to mixing between deeper N-MORB and shallower Reunion hot-spot sources beneath the

Two Approaches in the Lunar Libration Theory: Analytical vs. Numerical Methods

NASA Astrophysics Data System (ADS)

Petrova, Natalia; Zagidullin, Arthur; Nefediev, Yurii; Kosulin, Valerii

2016-10-01

Observation of the physical libration of the Moon and the celestial bodies is one of the astronomical methods to remotely evaluate the internal structure of a celestial body without using expensive space experiments. Review of the results obtained due to the physical libration study, is presented in the report.The main emphasis is placed on the description of successful lunar laser ranging for libration determination and on the methods of simulating the physical libration. As a result, estimation of the viscoelastic and dissipative properties of the lunar body, of the lunar core parameters were done. The core's existence was confirmed by the recent reprocessing of seismic data Apollo missions. Attention is paid to the physical interpretation of the phenomenon of free libration and methods of its determination.A significant part of the report is devoted to describing the practical application of the most accurate to date the analytical tables of lunar libration built by comprehensive analytical processing of residual differences obtained when comparing the long-term series of laser observations with numerical ephemeris DE421 [1].In general, the basic outline of the report reflects the effectiveness of two approaches in the libration theory - numerical and analytical solution. It is shown that the two approaches complement each other for the study of the Moon in different aspects: numerical approach provides high accuracy of the theory necessary for adequate treatment of modern high-accurate observations and the analytic approach allows you to see the essence of the various kind manifestations in the lunar rotation, predict and interpret the new effects in observations of physical libration [2].[1] Rambaux, N., J. G. Williams, 2011, The Moon's physical librations and determination of their free modes, Celest. Mech. Dyn. Astron., 109, 85-100.[2] Petrova N., A. Zagidullin, Yu. Nefediev. Analysis of long-periodic variations of lunar libration parameters on the basis of

Analysis of the sources and dynamic processes leading to the increase of atmospheric CO2, black carbon and other trace species during recent urban pollution events in the Paris megacity region : a synergy of resources provided by the IPSL OCAPI platform.

NASA Astrophysics Data System (ADS)

Xueref-Remy, I.; Foret, G.; Beekmann, M.; Brégonzio-Rozier, L.; Favez, O.; Gros, V.; Moreau-Guigon, E.; Vogel, F. R.; Belviso, S.; Ghersi, V.; Dupont, J. C.; Bodichon, R.; Cailteau-Fischbach, C.; Baisnee, D.; Peinado, F.; Haeffelin, M.; DeCola, P.; Turnbull, J. C.; Chelin, P.; Te, Y. V.; Formenti, P.; Doussin, J. F.; Gratien, A.; Desboeufs, K. V.; Ramage, K.; Jeseck, P.; Delmotte, M.; Ramonet, M.; Michoud, V.; Ravetta, F.

2016-12-01

Nowadays, more than 50% of the global population leave in urban centers which activities generate large anthropogenic emissions of CO2 (more than 70% of fossil fuel CO2 comes from urbanized/industrialized areas) and reactive gases that endanger our climate, the health of human beings and surrounding ecosystems. The worst situations are encountered during urban pollution events that usually form under anticyclonic conditions. Analyzing the contribution of the local and regional sources of urban CO2 and co-emitted species vs the remote ones, as well as the nature of these sources and the dynamical processes that lead to the building of such events can provide interesting knowledge for helping urban policy makers to better identify the role of anthropogenic/biogenic sources on the urban air composition and to take proper decisions in matter of CO2 and pollutants sources mitigation. With 12 million of people, Paris (France) is the second megacity in Europe. In 2016, two pollution events occured in the Paris region during which the instrumental platform OCAPI (http://observations.ipsl.fr/composition-atmospherique-en-idf.html) from IPSL (Institut Pierre Simon Laplace) was mobilized in collaboration with air quality governing actors (AIRPARIF, INERIS) to collect a bunch of observations. Five sites located in the urban, peri-urban and rural areas of Paris were equiped with in-situ analyzers (CO2, CO, black carbon, 13CO2, COS) ; Fourier transform spectrometers for column measurements (XCO2, XCO, XCOS), particle filters (for aerosols size and content analysis) ; air samples (levoglucosan, 14CO2, VOCs) ; and Lidar profilers (boundary layer height ; wind profiles). These data, combined with a backtrajectories analysis, give information about the dynamical processes that lead to the formation of the pollution events and on the contribution of local, regional and remote sources. The analysis of the correlations between the trace species and of the isotopic content of carbon in

In situ airborne measurements of aerosol optical properties during photochemical pollution events

NASA Astrophysics Data System (ADS)

Mallet, M.; van Dingenen, R.; Roger, J. C.; Despiau, S.; Cachier, H.

2005-02-01

Dry aerosol optical properties (scattering, absorbing coefficients, and single scattering albedo) were derived from in situ airborne measurements during two photochemical pollution events (25 and 26 June) observed during the Experience sur Site pour Contraindre les Modeles de Pollution atmospherique et de Transport d'Emissions (ESCOMPTE) experiment. Two flights were carried out during daytime (one during the morning and one at noon) over a domain, allowing the investigation of how an air pollution event affects the particle optical properties. Both horizontal distribution and vertical profiles are presented. Results from the horizontal mapping show that plumes of enhanced scattering and absorption are formed in the planetary boundary layer (PBL) during the day in the sea breeze-driven outflow of the coastal urban-industrial area of Marseille-Fos de Berre. The domain-averaged scattering coefficient (at 550 nm) over land σs changes from 35 (28) Mm-1 during land breeze to 63 (43) Mm-1 during sea breeze on 25 June (26 June), with local maxima reaching > 100 Mm-1. The increase in the scattering coefficient is associated with new particle formation, indicative of secondary aerosol formation. Simultaneously, the domain-averaged absorption coefficient increases from 5.6 (3.4) Mm-1 to 9.3 (8.0) Mm-1. The pollution plume leads to strong gradients in the single scattering albedo ωo over the domain studied, with local values as low as 0.73 observed inside the pollution plume. The role of photochemistry and secondary aerosol formation during the 25 June case is shown to increase ωo and to make the aerosol more `reflecting' while the plume moves away from the sources. The lower photochemical activity, observed in the 26 June case, induces a relatively higher contribution of black carbon, making the aerosol more absorbing. Results from vertical profiles at a single near-urban location in the domain indicate that the changes in optical properties happen almost entirely within

3D Cloud Radiative Effects on Polarized Reflectances

NASA Astrophysics Data System (ADS)

Cornet, C.; Matar, C.; C-Labonnote, L.; Szczap, F.; Waquet, F.; Parol, F.; Riedi, J.

2017-12-01

As recognized in the last IPCC report, clouds have a major importance in the climate budget and need to be better characterized. Remote sensing observations are a way to obtain either global observations of cloud from satellites or a very fine description of clouds from airborne measurements. An increasing numbers of radiometers plan to measure polarized reflectances in addition to total reflectances, since this information is very helpful to obtain aerosol or cloud properties. In a near future, for example, the Multi-viewing, Multi-channel, Multi-polarization Imager (3MI) will be part the EPS-SG Eumetsat-ESA mission. It will achieve multi-angular polarimetric measurements from visible to shortwave infrared wavelengths. An airborne prototype, OSIRIS (Observing System Including Polarization in the Solar Infrared Spectrum), is also presently developed at the Laboratoire d'Optique Atmospherique and had already participated to several measurements campaigns. In order to analyze suitably the measured signal, it it necessary to have realistic and accurate models able to simulate polarized reflectances. The 3DCLOUD model (Szczap et al., 2014) was used to generate three-dimensional synthetic cloud and the 3D radiative transfer model, 3DMCPOL (Cornet et al., 2010) to compute realistic polarized reflectances. From these simulations, we investigate the effects of 3D cloud structures and heterogeneity on the polarized angular signature often used to retrieve cloud or aerosol properties. We show that 3D effects are weak for flat clouds but become quite significant for fractional clouds above ocean. The 3D effects are quite different according to the observation scale. For the airborne scale (few tens of meter), solar illumination effects can lead to polarized cloud reflectance values higher than the saturation limit predicted by the homogeneous cloud assumption. In the cloud gaps, corresponding to shadowed areas of the total reflectances, polarized signal can also be enhanced

Global scale variability of the mineral dust longwave refractive index from laboratory chamber experiments: re‒evaluation of its direct radiative effect

NASA Astrophysics Data System (ADS)

Di Biagio, C.; Formenti, P.; Balkanski, Y.; Caponi, L.; Cazaunau, M.; Pangui, E.; Journet, E.; Nowak, S.; Caquineau, S.; Andreae, M. O.; Kandler, K.; Saeed, T.; Piketh, S.; Seibert, D.; Williams, E.; Boucher, O.; Doussin, J. F.

2017-12-01

New measurements of the longwave complex refractive index (LW CRI) of mineral dust and its global variability were obtained in situ in the 4.2 m3CESAM simulation chamber at LISA (Laboratoire Interuniversitaire des Systemes Atmospheriques) in Créteil, France. Aerosols generated by mechanical shaking from nineteen natural soils with contrasted mineralogical composition were suspended in the chamber, where their LW extinction spectra (2-16 μm), size distribution, and mineralogical composition were measured. The CRI of the dust aerosol was obtained by optical calculations based upon the measured extinction spectrum and size distribution. Laboratory results indicate that the LW refractive index of dust strongly varies with the source region of emission in link with the changes of its mineralogy. In the 2-16 μm spectral range, the imaginary refractive index (k) is between 0.001 and 0.92, and the real part (n) in the range 0.84-1.94. The strength of the dust absorption at 7 and 11.4 µm depends on the amount of calcite within the samples, while the absorption between 8 and 14 µm is determined by the relative abundance of quartz and clays. A linear relationship between the magnitude of k at 7, 9.2, and 11.4 µm and the mass concentration of calcite and quartz absorbing at these wavelengths was found, which suggests that predictive rules could be established to estimate the LW refractive index of dust in specific bands based on an assumed or predicted mineralogical composition. Our observations also suggest that the LW CRI of dust does not change as a result of the loss of coarse particles by gravitational settling, so that a constant value can be assumed close to sources and following transport. This unprecedented dataset of refractive indices was used as input into the LMDZORINCA model coupled with the RRTM radiative transfer module in order to re‒evaluate the direct dust LW radiative effect. This represents a first attempt to use regional‒dependent values of the

The Shadow of a Gnomon Along a Year: Routine Observations and Teaching of Apparent Motion of the Sun and the Four Seasons. (Spanish Title: La Sombra de un Gnomon lo Largo de un Año: Observaciones de Rutina y la Enseñanza del Movimiento Aparente del Sol y Las Cuatro Estaciones.) A Sombra de um Gnômon ao Longo de um Ano: Observações Rotineiras e o Ensino do Movimento Aparente do Sol E das Quatro Estações

NASA Astrophysics Data System (ADS)

Trogello, Anderson Giovani; Danhoni Neves, Marcos Cesar; de Carvalho Rutz da Silva, Sani

2013-12-01

Many misconceptions are recognized among the various groups of students, especially in the elementary school. Among them, the apparent motion of the Sun, in spite of its daily occurrence, is subject to varied interpretations. Thus, the observation and recording of the motion of the stars in the celestial vault is a necessary task for astronomy education. The work presented here proposes the presentation of the results of observations of the apparent movement of the sun by marking the shadow of a vertical gnomon by the students in a class of sixth graders of elementary rural school of Paraná. The project itself was conducted in four stages, on dates near the March equinox, the June solstice, the September equinox and the December solstice. In addition, lectures were developed in the classroom. Such methods sought to build concepts around the apparent movement of the Sun and the alternation of the seasons. Given the results of the activities, an evaluation was applied and the data demonstrated a desired student learning such as: the recognition of the cardinal points, the description of the apparent solar motion and the occurrence of the seasons and their alternation from astronomical observations at naked eye. Muchos conceptos aternativos son conocidos entre los distintos grupos de alumnos, sobre todo en la educación básica. Entre ellos, el movimiento aparente del Sol, por más cotidiano que sea, se presta a interpretaciones variadas. Por lo tanto, observar y registrar el movimiento de las estrellas en la bóveda celeste se torna una tarea necesaria para la educación en astronomía. El trabajo que aquí se presenta propone la presentación de los resultados de la observación del movimiento aparente del sol a través de la marcación de la sombra del gnomon vertical a cargo de los estudiantes en una división de sexto grado de de la escuela primaria rural de Paraná. El proyecto en sí se llevó a cabo en cuatro etapas, en fechas cercanas al equinoccio de marzo

Astronomical Perception of the Secondary School's Students in São Paulo's State School in Suzano City. (Spanish Title: Percepción Astronómica de Alumnos de la Enseñanza Media de la Red Estatal de San Pablo en la Ciudad de Suzano.) Percepção Astronômica de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo da Cidade de Suzano

NASA Astrophysics Data System (ADS)

França de Oliveira, Edilene; Voelzke, Marcos Rincon; Amaral, Luis Henrique

2007-12-01

año y 20,6% tenían la idea de cuales son los objetos celestes más cercanos de la Tierra. En contraposición, 67,6% clasificaron correctamente el Sol como una estrella; 55,9% relacionaron el Big Bang al origen del Universo; solamente 20,6% identificaron un año-luz como unidad de distancia y 32,4% reconocieron una estrella fugaz como meteoro. El presente análisis fue expandido para otros grupos de la Enseñanza Media, no solamente del período nocturno, sino también diurno de la misma escuela. En esta primera fase se nota el pequeño conocimiento de los alumnos sobre eventos astronómicos y principalmente la gran confusión sobre el significado correcto de los términos astronómicos populares. Embora a Astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos do Ensino Médio da Rede Estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, aplicado no primeiro ano noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias; 20,6% explicaram corretamente as estações do ano e 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra. Em contraposição, 67,6% classificaram corretamente o Sol como estrela; 55,9% relacionaram o Big Bang à origem do Universo; apenas 20,6% identificaram um ano-luz como unidade de distância e 32,4% reconheceram uma estrela cadente como meteoro. A presente análise foi expandida para mais 310 alunos de outras classes de Ensino Médio, não somente do período noturno, mas também diurno da mesma escola. Nesta primeira fase nota-se o pequeno discernimento dos alunos sobre eventos astronômicos e

The Understanding of Astronomy Concepts by Students from Basic Education of a Public School. (Spanish Title: El Entendimiento de Conceptos de Aastronmía Por Los Alumnos de Educación Básica en Una Escuela Pública.) O Entendimento de Conceitos de Astronomia Por Alunos da Educação Básica: O Caso de Uma Escola Pública Brasileira

NASA Astrophysics Data System (ADS)

Iria Machado, Daniel; dos Santos, Carlos

2011-07-01

movimiento de la Luna, el movimiento aparente del Sol sobre la esfera celeste, los eclipses, las dimensiones y las distancias en el Universo, el brillo de las estrellas y su observación de la Tierra. Si bien ha habido un pequeño progreso en la proporción de respuestas aceptables científicamente cuando se cotejó el octavo grado de la enseñanza primaria con el quinto, y el último año de la enseñanza secundaria con el primero, se observó un predominio de las concepciones alternativas en relación a la mayoría de los temas explorados, que continuó hasta los últimos años de la educación básica. Una comparación con los datos encontrados en investigaciones realizadas en otros contextos socioculturales revelaron, en muchos aspectos, conceptos y dificultades similares expresadas por los estudiantes. Apresentam-se os resultados de uma investigação sobre a compreensão de conceitos astronômicos básicos, da qual participaram 561 estudantes da quinta série do Ensino Fundamental ao terceiro ano do Ensino Médio de uma escola pública da cidade de Foz do Iguaçu. Um teste com 20 questões de múltipla escolha foi aplicado para identificar as concepções mais comuns expressadas pelos alunos. Esse instrumento de coleta de dados foi elaborado com base na literatura sobre concepções alternativas e abordou os seguintes temas: o ciclo dia-noite; os fusos horários; as estações do ano; as fases da Lua; o movimento da Lua; o movimento aparente do Sol na esfera celeste; os eclipses; as dimensões e distâncias no Universo; o brilho das estrelas e sua observação da Terra. Embora se tenha verificado um pequeno progresso na proporção de respostas cientificamente aceitáveis ao se cotejar a oitava série do Ensino Fundamental com a quinta, e a terceira série do Ensino Médio com a primeira, houve o predomínio de concepções alternativas em relação à maior parte dos temas explorados, as quais persistiram até o último ano da Educação Básica. A comparação com

Remote Sensing of Volcanic Clouds: Sulfur Gases and Plume Top Topography

NASA Technical Reports Server (NTRS)

Crisp, Joy A.

1999-01-01

New absorption line parameters for H2S were published and submitted to the Gestion et Etude des Informations Spectroscopiques Atmospheriques (GEISA) and high resolution transmission molecular absorption (HITRAN) databases. These new absorption line parameters will make it possible to use observations from the future Tropospheric Emission Spectrometer (TES) instrument [Earth Observing System (EOS) Chemistry Mission (CHEM) platform] to make more accurate H2S measurements if it observes an H2S-rich volcanic cloud. H2S is the second most abundant volcanic sulfur gas, and like SO2, it also converts to H2SO4 aerosols and can have a climate impact. A paper on the Moderate-resolution Imaging-Spectroradiometer (MODIS) SO2 alert is being revised. New aspects in the revision include verification of the SO2 alert during the EOS mission; factors affecting SO2 detection at thermal infrared, ultraviolet, and microwave wavelengths; radiative transfer tests; more description of satellite instruments; and thermal surface alert installed for MODIS. Her research involves the use of remote sensing to generate maps of plume top altitude. This parameter is important for models of volcanic eruption, aircraft hazards, and climate impact. The topographic shape of the top surface of a volcanic plume can provide information necessary to understand the physics controlling the injection and dispersal of a volcanic plume in the atmosphere. Glaze et al. describe the application of a photoclinometric technique to volcanic plumes. The software algorithm has been improved to account for more general plume and illumination geometries and for easily extracting position information directly from Advanced Very High-Resolution Radiometer (AVHRR) level 1B data. Testing of the algorithm has focused on acquiring AVHRR data for a variety of volcanic plumes in an effort to identify problems with the software as well as model sensitivities. The plumes chosen were erupted from volcanoes at a variety of

The Darkening of the Greenland Ice Sheet: Trends, Drivers and Projections (1981-2100)

NASA Technical Reports Server (NTRS)

Tedesco, Marco; Doherty, Sarah; Fettweis, Xavier; Alexander, Patrick; Jeyaratnam, Jeyavinoth; Stroeve, Julienne

2016-01-01

The surface energy balance and meltwater production of the Greenland ice sheet (GrIS) are modulated by snow and ice albedo through the amount of absorbed solar radiation. Here we show, using space-borne multispectral data collected during the 3 decades from 1981 to 2012, that summertime surface albedo over the GrIS decreased at a statistically significant (99 %) rate of 0.02 decade(sup -1) between 1996 and 2012. Over the same period, albedo modelled by the Modele Atmospherique Regionale (MAR) also shows a decrease, though at a lower rate (approximately -0.01 decade(sup -1)) than that obtained from space-borne data. We suggest that the discrepancy between modelled and measured albedo trends can be explained by the absence in the model of processes associated with the presence of light-absorbing impurities. The negative trend in observed albedo is confined to the regions of the GrIS that undergo melting in summer, with the dry snow zone showing no trend. The period 1981-1996 also showed no statistically significant trend over the whole GrIS. Analysis of MAR outputs indicates that the observed albedo decrease is attributable to the combined effects of increased near-surface air temperatures, which enhanced melt and promoted growth in snow grain size and the expansion of bare ice areas, and to trends in light-absorbing impurities (LAI) on the snow and ice surfaces. Neither aerosol models nor in situ and remote sensing observations indicate increasing trends in LAI in the atmosphere over Greenland. Similarly, an analysis of the number of fires and BC emissions from fires points to the absence of trends for such quantities. This suggests that the apparent increase of LAI in snow and ice might be related to the exposure of a "dark band" of dirty ice and to increased consolidation of LAI at the surface with melt, not to increased aerosol deposition. Albedo projections through to the end of the century under different warming scenarios consistently point to continued

A Kalman Filter Integrated Navigation Design for the IAR Twin Otter Atmospheric Research Aircraft (Methode de Navigation Integree a Filtre de Kalman Destinee au Twin Otter de L’Ira Charge des Recherches Atmospheriques)

DTIC Science & Technology

1991-04-01

1Z I III i II1’I’ ,, iiII ll~ I! ’i tiNt $W"T" INSTITUTE FOR AEROSPACE RESEARCH SCIENTIFIC AND TECHNICAL PUBLICATIONS AERONAUTICAL REPORTS...Aeronautical Reports (LR): Scientific and technical information pertaining to aeronautics considered important, complete, and a lasting contribution to existing...knowledge. Mechanical Engineering Reports (MS): Scientific and technical information pertaining to investigations outside aeronautics considered

Percepção Astronômica de Alunos do Ensino Médio da Rede Estadual de São Paulo

NASA Astrophysics Data System (ADS)

de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

2005-08-01

Embora a astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, principalmente nesta época de alta globalização do conhecimento por intermédio de eficientes meios de comunicação e de obtenção da informação, notadamente através da internet, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos de Ensino Médio da rede estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam, tais como a sucessão dos dias e das estações do ano, além de questioná-los sobre fatos genéricos tais como: quais são os astros que se encontram mais próximos do planeta Terra, o que vem a ser o Sol, o Big Bang, um ano-luz, uma estrela cadente, a estrela de Bélem e o que ocasionou a extinção dos dinossauros. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, o qual foi aplicado no primeiro colegial noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias da semana, que apenas 20,6% explicaram corretamente as estações do ano, que apenas 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra, em contraposição 67,6% sabiam classificar corretamente o Sol como estrela, 55,9% relacionavam o Big Bang à origem do universo, apenas 20,6% identificavam um ano-luz como unidade de distância, 32,4% reconheciam uma estrela cadente como meteoro, 41,2% consideravam a estrela de Belém como um cometa e 50,0% explicaram corretamente a extinção dos dinossauros. A presente análise será expandida para as demais classes de primeiro colegial, não somente do período noturno, mas também do diurno da Escola Estadual Batista Renzi, bem como o formulário será devidamente ampliado. Já nesta primeira fase nota-se claramente o pequeno discernimento

Navigation d'un vehicule autonome autour d'un asteroide

NASA Astrophysics Data System (ADS)

Dionne, Karine

Les missions d'exploration planetaire utilisent des vehicules spatiaux pour acquerir les donnees scientifiques qui font avancer notre connaissance du systeme solaire. Depuis les annees 90, ces missions ciblent non seulement les planetes, mais aussi les corps celestes de plus petite taille comme les asteroides. Ces astres representent un defi particulier du point de vue des systemes de navigation, car leur environnement dynamique est complexe. Une sonde spatiale doit reagir rapidement face aux perturbations gravitationnelles en presence, sans quoi sa securite pourrait etre compromise. Les delais de communication avec la Terre pouvant souvent atteindre plusieurs dizaines de minutes, il est necessaire de developper des logiciels permettant une plus grande autonomie d'operation pour ce type de mission. Ce memoire presente un systeme de navigation autonome qui determine la position et la vitesse d'un satellite en orbite autour d'un asteroide. Il s'agit d'un filtre de Kalman etendu adaptatif a trois degres de liberte. Le systeme propose se base sur l'imagerie optique pour detecter des " points de reperes " qui ont ete prealablement cartographies. Il peut s'agir de crateres, de rochers ou de n'importe quel trait physique discernable a la camera. Les travaux de recherche realises se concentrent sur les techniques d'estimation d'etat propres a la navigation autonome. Ainsi, on suppose l'existence d'un logiciel approprie qui realise les fonctions de traitement d'image. La principale contribution de recherche consiste en l'inclusion, a chaque cycle d'estimation, d'une mesure de distance afin d'ameliorer les performances de navigation. Un estimateur d'etat de type adaptatif est necessaire pour le traitement de ces mesures, car leur precision varie dans le temps en raison de l'erreur de pointage. Les contributions secondaires de recherche sont liees a l'analyse de l'observabilite du systeme ainsi qu'a une analyse de sensibilite pour six parametres principaux de conception. Les

Results from a 14-month hydroacoustic monitoring of the three mid-oceanic ridges in the Indian Ocean

NASA Astrophysics Data System (ADS)

Royer, J.-Y.; Dziak, R. P.; Delatre, M.; Chateau, R.; Brachet, C.; Haxel, J. H.; Matsumoto, H.; Goslin, J.; Brandon, V.; Bohnenstielh, D. R.

2009-04-01

From October 2006 to January 2008, an hydroacoustic experiment in the Indian Ocean was carried out by the CNRS/University of Brest and NOAA/Oregon State University to monitor the low-level seismic activity associated with the three contrasting spreading ridges and deforming zones in the Indian Ocean. Three autonomous hydrophones were moored in the SOFAR channel by R/V Marion Dufresne for 14 months in the Madagascar Basin, and northeast and southwest of Amsterdam Island, complementing the two permanent hydroacoustic stations of the Comprehensive nuclear-Test-Ban Treaty Organization (CTBTO) located near Diego Garcia Island and off Cape Leeuwin. The three instruments successfully collected 14 month of continuous acoustic records. Combined with the records from the permanent stations, the array detected 1780 acoustic events consisting mostly of earthquake generated T-waves, but also of iceberg tremors from Wilkes Land, Antarctica. Within the triangle defined by the temporary array, the three ridges exhibit contrasting seismicity patterns. Along the Southeast Indian ridge (SEIR), the 272 acoustic events (vs 24 events in the NEIC catalog) occur predominantly along the transform faults ; only one ridge segment (76˚E) displays a continuous activity for 10 months. Along the Central Indian Ridge (CIR), seismicity is distributed along fracture zones and ridge segments (269 events vs 45 NEIC events), with two clusters of events near the triple junction (24-25S) and south of Marie-Celeste FZ (18.5S). Along the Southwest Indian Ridge (SWIR), the 222 events (vs 31 NEIC events) are distributed along the ridge segments with a larger number of events west of Melville FZ and a cluster at 58E. The immediate vicinity of the Rodrigues triple junction shows periods of quiescence and of intense activity. Some large earthquakes (Mb>5) near the triple junction (SEIR and CIR) seem to be preceded by several acoustic events that may be precursors. Finally, off-ridge seismicity is mostly

The Evolution of Hydrocarbon Compounds in Saturn's Stratosphere During the 2010 Northern Storm

NASA Astrophysics Data System (ADS)

Hesman, B. E.; Bjoraker, G. L.; Achterberg, R. K.; Sada, P. V.; Jennings, D. E.; Lunsford, A. W.; Sinclair, J.; Romani, P. N.; Boyle, R.; Fletcher, L. N.; Irwin, P.

2013-12-01

The massive eruption at 40N (planetographic latitude) in December 2010 has produced significant and long-lived changes in temperature and species abundances in Saturn's northern hemisphere (Hesman et al. 2012a, Fletcher et al. 2012). The northern storm region has been observed on many occasions between January 2011 and June of 2012 by Cassini's Composite Infrared Spectrometer (CIRS). In this time period, temperatures in regions referred to as 'beacons' (warm regions in the stratosphere at certain longitudes in the storm latitude) became significantly warmer than pre-storm values of 140K. In this period hydrocarbon emission greatly increased; however, this increased emission could not be attributed due to the temperature changes alone for many of these species (Hesman et al. 2012b, Bjoraker et al 2012). The unique nature of the stratospheric beacons also resulted in the detection of ethylene (C2H4) using CIRS. These beacon regions have also led to the identification of rare hydrocarbon species such as C4H2 and C3H4 in the stratosphere. These species are all expected from photochemical processes in the stratosphere, however high temperatures, unusual chemistry, or dynamics are enhancing these species. The exact cause of these enhancements is still under investigation. Ground-based observations were performed using the high-resolution spectrometer Celeste in May 2011 to confirm the CIRS detection of C2H4 and to study its spectral signatures at higher spectral resolution. In order to follow the evolution of its emission further observations were performed in July 2011 and March 2012. These observations are being used in conjunction with the CIRS observations to investigate the source of the approximately 100-fold increase of ethylene in the stratospheric beacon. The time evolution of hydrocarbon emission from C2H2, C2H4, C2H6, C3H4, and C4H2 in Saturn's Northern Storm beacon regions will be discussed. References: Bjoraker, G., B.E. Hesman, R.K. Achterberg, P.N. Romani

The System of Chemical Elements Distribution in the Hydrosphere

NASA Astrophysics Data System (ADS)

Korzh, Vyacheslav D.

2013-04-01

natural (unaffected by anthropogenic influence) mean concentrations of elements in the river runoff and using them as ecological reference data. Finally, due to the long response time of the ocean, the mean concentrations of elements and patterns of their distribution in the ocean can be used to determine pre-techno-generative concentrations of elements in the river runoff. In our presentation, we shall show several examples of implementation of the System for studying the sediments' transport by the rivers of the Arctic slope of Northern Eurasia. References 1. Korzh V.D. 1974: Some general laws governing the turnover of substance within the ocean-atmosphere-continent-ocean cycle. Journal de Recherches Atmospheriques, 8, 653-660. 2. Korzh V.D. 2008: The general laws in the formation of the element composition of the Hydrosphere and Biosphere. J. Ecologica, 15, 13-21. 3. Korzh V.D. 2012: Determination of general laws of the chemical element composition in Hydrosphere. Water: Chemistry & Ecology, Journal of Water Science and its Practical Application. No. 1, 56-62.

Taxocoenosis of epibenthic dinoflagellates in the coastal waters of the northern Yucatan Peninsula before and after the harmful algal bloom event in 2011-2012.

PubMed

Aguilar-Trujillo, Ana C; Okolodkov, Yuri B; Herrera-Silveira, Jorge A; Merino-Virgilio, Fany Del C; Galicia-García, Citlalli

2017-06-15

Eutrophication causes the major impact in the coastal waters of the state of Yucatan. In general, loss of water quality and biological communities and massive development of toxic microorganisms are some of the consequences of this phenomenon. To reveal changes in species composition and cell abundance of the taxocoenosis of epibenthic dinoflagellates before and after a harmful algal bloom event in the water column that lasted about 150days (August-December 2011) in the Dzilam - San Crisanto area (northern Yucatan Peninsula, southeastern Gulf of Mexico) were the main objectives of the present study. In August 2011 and September 2012, sampling along 20 transects perpendicular to the coastline along the entire northern Yucatan coast, starting from 20 sampling sites from El Cuyo in the east to Celestún in the west, at a distance of 50, 150 and 250m from the coast, was carried out. Physicochemical characteristics measured before and after the bloom were within the ranges previously reported in the study area. Salinity was the most stable characteristic, with mean values of 36.25 and 36.42 in 2011 and 2012, respectively. Phosphates were the only parameter that showed a wide range with higher values before the bloom (0.03-0.54μM/l). A total of 168 macrophyte (seaweeds and seagrasses), sponge and sediment samples (105 in 2011 and 63 in 2012) that included associated microphytobenthos were taken by snorkeling from 0.7 to 5m depth. Six substrate types were distinguished: Chlorophyta, Phaeophyceae, Rhodophyta, Angiospermae (seagrasses), Demospongiae (sponges) and sediment. Chlorophytes dominated the collected samples: 38 samples in 2011 and 23 in 2012. Avrainvillea longicaulis f. laxa predominated before the bloom and Udotea flabellum after it. In total, 25 epibenthic dinoflagellate species from 11 genera were found. The genus Prorocentrum was the most representative in terms of the number of species. The highest total dinoflagellate cell abundances were observed in the

Developpement D'un Modele Climatique Regional: Fizr Simulation des Conditions de Janvier de la Cote Ouest Nord Americaine

NASA Astrophysics Data System (ADS)

Goyette, Stephane

1995-11-01

. Cette nouvelle gamme de modeles-interpolateurs imbriques qualifies d'"intelligents" fait partie de la famille des modeles dits "pilotes". L'hypothese directrice de notre etude est fondee sur la supposition que le climat de fine echelle est souvent gouverne par des forcages provenant de la surface plutot que par des transports atmospheriques de grande echelle spatiale. La technique que nous proposons vise donc a guider FIZR par la Dynamique echantillonnee d'un MCG et de la forcer par la Physique du MCG ainsi que par un forcage orographique de meso-echelle, en chacun des noeuds de la grille fine de calculs. Afin de valider la robustesse et la justesse de notre modele climatique regional, nous avons choisi la region de la Cote Ouest du continent nord americain. Elle est notamment caracterisee par une distribution geographique des precipitations et des temperatures fortement influencee par le relief sous-jacent. Les resultats d'une simulation d'un mois de janvier avec FIZR demontrent que nous pouvons simuler des champs de precipitations et de temperatures au niveau de l'abri beaucoup plus pres des observations climatiques comparativement a ceux simules a partir d'un MCG. Ces performances sont manifestement attribuees au forcage orographique de meso-echelle de meme qu'aux caracteristiques de surface determinees a fine echelle. Un modele similaire a FIZR peut, en principe, etre implante sur l'importe quel MCG, donc, tout organisme de recherche implique en modelisation numerique mondiale de grande echelle pourra se doter d'un el outil de regionalisation.

VizieR Online Data Catalog: New standards in 18th century astrometry (Lequeux, 2014)

NASA Astrophysics Data System (ADS)

Lequeux, J.

2014-05-01

named lacaillefund.dat. La Caille's complete survey of the southern sky (lacaisur.dat): During his stay in Cape Town in 1751-1752, La Caille made the first systematic survey of the sky ever, in the modern sense. 244 stars over 9766. La Caille's catalogue of zodiacal stars (lacaizod.dat): When La Caille returned from his southern expedition in 1754, he undertook the construction of a catalogue of zodiacal stars. Mayer's zodiacal catalogue (mayer.dat): At exactly the same time as La Caille, Tobias Mayer (1723-1762) in Gottingen undertook a similar catalogue of zodiacal stars, using a 6-feet radius mural quadrant made by John Bird (1709-1776). 200 stars over 998. Bradley's stellar catalogue (bradley.dat): James Bradley (1693-1762) is famous for his discovery of aberration and nutation. From 1750 to his death in 1762, he built a large stellar catalogue, from observations first with an old mural sector and after 1753 with the Bird 8-ft mural sector located in Greenwich, where it 215 stars over 3220. Piazzi's stellar catalogue (piazzi.dat): Giuseppe Piazzi (1746-1846) built a large catalogue containing 7646 stars from 1792 to 1813, observed in Palermo with an altazimuthal circle of Jesse Ramsden (1735-1800) can still be seen. 202 stars over 7646. Lalande's stellar catalogue (lalande.dat): L'Histoire celeste francaise de Lalande (Lalande 1801), which contains the unreduced observations of approximately 40,000 stars, is the first very large stellar catalogue. 198 stars over ~45000. (10 data files).

The Meteoritical Quincentennial: The Stone of Ensisheim 1492-1992

NASA Astrophysics Data System (ADS)

Marvin, U. B.

1992-07-01

of God, because never before had such a thing been heard, or seen, or written about. Von der Muhll (1961) and others have asked how such statements could be made when Pliny the Elder wrote of fallen stones as early as the 1st century A.D., and Heynlin de Lapide, at nearby Basel, was translating Pliny's works at the time of the fall. However, expressions such as "never before heard, seen, or written about," spiced the reports of Medieval travelers struggling to describe the marvels of far-off lands. In this instance, the phrases described a marvel that burst upon the people of the upper Rhineland in the course of their daily routines. In truth, nothing ever written could have prepared them for the incandescent fireball, resounding explosion, and the black stone that plunged to Earth at Ensisheim. Unimaginative Eyewitnesses. A boy saw the stone fall and a crowd dug it out of a wheat field. In 1800, the chemist, Charles Barthold, rejected the eyewitness story and concluded that the stone was a common type of rock that could have washed down from a mountainside. In 1803, after meteorites, including the Ensisheim stone, had become accepted as authentic natural phenomena, Joseph Izarn wrote that the boy's testimony should be believed because ignorant persons like him have no imagination and could not possible invent tales about stones from the sky. Izarn's opinion was not eccentric; numerous writings show that it reflected a centuries-old tradition of placing special value on observations by unschooled witnesses. References: Brant S. (1492) Flugblatt, J. von Ople, Basel, 1 p. Izarn J. (1803) Lithologie Atmospherique, Delalain Fils, Paris, 422 pp. Marvin U. B. (1992) Meteoritics 27, 28-72. Newton H. A. (1891) Comptes Rendus Acad. Sci. 113, 234. Muhll Th. von der (1975) Donnerstein von Ensisheim, Birkhauser Verlag, Basel, 42 pp. Schedel H. (1493) Nuremberg Chronicle, A. Korberger, Nuremberg, 299 pp.

The non-serpentine phases in serpentinites from the Braszowice-Brzeźnica Massif (SW Poland) as traces of magmatic processes within oceanic mantle

NASA Astrophysics Data System (ADS)

Wojtulek, Piotr; Puziewicz, Jacek; Ntaflos, Theodoros

2016-04-01

primary mantle phases. Cpx I contains similar amount of the Al2O3, Cr2O3 and Na2O to primary diopsides described from the Marie Celeste FZ and Indomed FZ (Johnson et al., 1990). REE pattern of the Cpx I suggests depletion in mobile trace elements due to melt extraction. Cpx II has Al2O3, Cr2O3 and TiO2 contents similar to those of diopside originated from the melt-percolation reactions, olivine coexisting with Cpx II crystallized probably in the same event. The Cpx III has Al, Cr and Na contents typical for secondary, metamorphic clinopyroxene. Magnetite-bearing olivine is similar to olivine crystallized at expense of serpentine+magnetite precursors, thus is has secondary, metamorphic origin. This abstract was prepared as a part of the project of the National Science Centre of Poland ("Evolution of serpentinic members of the Lower Silesia ophiolites", DEC-2012/07/N/ST10/03934). References Dick, H.J.B., Bullen, T., 1984. Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contributions to Mineralogy and Petrology 86, 54-76. Johnson K.T.M., Dick H.J.B., Shimizu N., 1990. Melting in the Oceanic Upper Mantle - an ion microprobe study of Diopsides in Abyssal Peridotites. Journal of Geophysical Research 95, 2661-2678.

Of Rings and Volcanoes

NASA Astrophysics Data System (ADS)

2002-01-01

December 8, 2001 (UT). Two of these were made with an H-band filter (10 sec exposure each, wavelength 1.6 µm) and two with a K-band filter (12 sec each, 2.2 µm). The satellite Tethys (diameter 1070 km, orbiting Saturn at a distance of approx. 295,000 km) served as reference source for the Adaptive Optics corrections and the telescope was offset guided to compensate for the differential motion. The frames were reduced in the normal way with classical flats, dark and bias correction. No convolution was made before the two colours were combined to produce the image shown. At the time of the exposure, Saturn was 8.80 AU from the Earth. With a diameter of approx. 120,000 km, its disk subtended an angle of 20.6 arcsec. The nominal resolution of the NAOS-CONICA image, about 0.07 arcsec, thus corresponds to 410 km at Saturn. PR Photo 04b/02 is a reproduction based on a total exposure of 230 sec with VLT YEPUN and NAOS-CONICA on December 5, 2001, made through a Brackett-gamma filter centred at 2.166 µm. The resulting image resolution is 0.068 arcsec. At the moment of the exposure, the distance from the Earth to Io was about 641 million km (4.29 AU) and the image resolution therefore corresponds to approx. 210 km on the surface of the moon. PR Photo 04c/02 is based on a combination of the Brackett-gamma (here rendered as blue) with an L' frame (total exposure 4.2 sec; 3.800 µm; red), superposed with a coordinate grid and with some of the major surface features identified. The grid was produced with tools available at the website of the Institut de Mecanique Celeste et de Calcul des Ephemerides.