2,190 research outputs found
High Precision Abundances in the 16 Cyg Binary System: A Signature of the Rocky Core in the Giant Planet
Get PDFWe study the stars of the binary system 16 Cygni to determine with high precision their chemical composition. Knowing that the component B has a detected planet of at least 1.5 Jupiter masses, we investigate if there are chemical peculiarities that could be attributed to planet Formation around this star. We perform a differential abundance analysis using high resolution (R = 81,000) and high S/N (similar to 700) CFHT/ESPaDOnS spectra of the 16 Cygni stars and the Sun; the latter was obtained from light reflected of asteroids. We determine differential abundances of the binary components relative to the Sun and between components A and B as well. We achieve a precision of sigma less than or similar to 0.005 dex and a total error similar to 0.01 dex for most elements. The effective temperatures and surface gravities found for 16 Cyg A and B are T-eff = 5830 +/- 7 K, log g = 4.30 +/- 0.02 dex, and T-eff = 5751 +/- 6K, log g = 4.35 +/- 0.02 dex, respectively. The component 16 Cyg A has ametallicity ([Fe/H]) higher by 0.047 +/- 0.005 dex than 16 Cyg B, as well as a microturbulence velocity higher by 0.08 km s(-1). All elements show abundance differences between the binary components, but while the volatile difference is about 0.03 dex, the refractories differ by more and show a trend with condensation temperature, which could be interpreted as the signature of the rocky accretion core of the giant planet 16 Cyg Bb. We estimate a mass of about 1.5-6 M-circle times for this rocky core, in good agreement with estimates of Jupiter's core.CAPESFAPESP 2012/24392-2CNPqMcDonald Observator
Colors 1981
No full textCONTENTS
Untitled, John I. C. Ramirez 2;
Love will fly, Tim Furness 3;
Untitled, Palmer Hoovestal 4;
The wave, Jerome Lightbourne 6;
The land*lord, R. Lea 7;
Song of the newborn, Heidi Muller 8;
Untitled, Mary Ostervold 9;
Good crops, Gina Larson 10;
Come, challenge the sea, Paula Schafer 12;
Untitled, Pat Dooris 14;
Untitled, Eric Peterson 16;
A flight of fancy, Tony Schaan 17;
Ode upon a london tube, Kit Warfield 18;
Sponge, Debbie Court 19;
Untitled, Debbie Court 20;
Untitled, John I. C. Ramirez 21;
Untitled, Joyce Lowry 21;
Untitled, Mary Taft 22;
Thank you, Lord [unidentified author] 23;
From generation to generation, Denise Marsh 24;
Untitled, S. M. 25;
Untitled, M. F. 26;
Brain Cramp, Francine Bergeron 27;
Untitled, Pat Dooris 28;
Untitled, Tom Mertes 30;
Untitled, John I. C. Ramirez 31;
Untitled, Dolores Bock 31;
Untitled, Christopher Perez 32;
Untitled, Pat Dooris 33;
Echoes of Innocence, Kelly Cosgrove 35;
Beloved, M. Bowen 36;
Untitled, Mary Ostervold 36
Lithium Abundances In Nearby FGK Dwarf And Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, And Exoplanets
Get PDFWe derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (T-eff) versus lithium abundance (A(Li)) plane is observed such that no stars with T-eff similar or equal to 6075 K and A(Li) similar or equal to 1.8 are found. We speculate that most of the stars on the low ALi side of the desert have experienced a short-lived period of severe surface lithium destruction as main-sequence or subgiant stars. Next, we search for differences in the lithium content of thin-disk and thick-disk stars, but we find that internal processes have erased from the stellar photospheres their possibly different histories of lithium enrichment. Nevertheless, we note that the maximum lithium abundance of thick-disk stars is nearly constant from [Fe/H] = -1.0 to -0.1, at a value that is similar to that measured in very metal-poor halo stars (A(Li) similar or equal to 2.2). Finally, differences in the lithium abundance distribution of known planet-host stars relative to otherwise ordinary stars appear when restricting the samples to narrow ranges of T-eff or mass, but they are fully explained by age and metallicity biases. We confirm the lack of a connection between low lithium abundance and planets. However, we find that no low A(Li) planet-hosts are found in the desert T-eff window. Provided that subtle sample biases are not responsible for this observation, this suggests that the presence of gas giant planets inhibit the mechanism responsible for the lithium desert.California Institute of Technology (Caltech)NASA through Sagan Fellowship ProgramCarnegie-Princeton graduate student programRobert A. Welch Foundation of Houston, Texas F-634McDonald Observator
Allele-Specific Reprogramming of Cancer Metabolism by the Long Non-coding RNA CCAT2
No full textRedis, R.S., Vela, L.E., Lu, W., Ferreira de Oliveira, J., Ivan, C., Rodriguez-Aguayo, C., Adamoski, D., Pasculli, B., Taguchi, A., Chen, Y., Fernandez, A.F., Valledor, L., Van Roosbroeck, K., Chang, S., Shah, M., Kinnebrew, G., Han, L., Atlasi, Y., Cheung, L.H., Huang, G.Y., Monroig, P., Ramirez, M.S., Catela Ivkovic, T., Van, L., Ling, H., Gafà, R., Kapitanovic, S., Lanza, G., Bankson, J.A., Huang, P., Lai, S.Y., Bast, R.C., Rosenblum, M.G., Radovich, M., Ivan, M., Bartholomeusz, G., Liang, H., Fraga, M.F., Widger, W.R., Hanash, S., Berindan-Neagoe, I., Lopez-Berestein, G., Ambrosio, A.L.B., Gomes Dias, S.M., Calin, G.A
Biodiversity and biogeography of hydrothermal vent species: thirty years of discovery and investigations
Get PDFAuthor Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 1 (2007): 30-41.The discovery of hydrothermal vents and the unique, often endemic
fauna that inhabit them represents one of the most extraordinary
scientific discoveries of the latter twentieth century. Not surprisingly,
after just 30 years of study of these remarkable—and extremely
remote—systems, advances in understanding the animals and microbial
communities living around hydrothermal vents seem to
occur with every fresh expedition to the seafloor. On average, two
new species are described each month—a rate of discovery that has
been sustained over the past 25–30 years. Furthermore, the physical, geological, and
geochemical features of each part of the ridge system and its associated
hydrothermal-vent structures appear to dictate which novel
biological species can live where. Only 10 percent of the ridge
system has been explored for hydrothermal activity to date (Baker
and German, 2004), yet we find different diversity patterns in that
small fraction. While it is well known that species composition varies
along discrete segments of the global ridge system, this “biogeographic
puzzle” has more pieces missing than pieces in place.E. Ramirez-Llodra is supported by
the ChEss-Census of Marine Life program
(A.P. Sloan Foundation), which
is kindly acknowledged. C.R. German
also acknowledges support from ChEss-
Census of Marine Life and further support
from the Natural Environment
Research Council (UK) and from the
US National Science Foundation (NSF)
and National Oceanic and Atmospheric
Administration (NOAA). T. Shank
acknowledges support from NSF, the US
National Aeronautic and Space Administration
Astrobiology Program, NOAA-Ocean
Exploration, and the Deep-Ocean
Exploration Institute at the Woods Hole
Oceanographic Institution
Soil Biological and Chemical Properties in Restored Perennial Grassland in California
No full textRestoration of California native perennial grassland is often initiated with cultivation to reduce the density and cover of non-native annual grasses before seeding with native perennials. Tillage is known to adversely impact agriculturally cultivated land; thus changes in soil biological functions, as indicated by carbon (C) turnover and C retention, may also be negatively affected by these restoration techniques. We investigated a restored perennial grassland in the fourth year after planting Nassella pulchra, Elymus glaucus, and Hordeum brachyantherum ssp. californicum for total soil C and nitrogen (N), microbial biomass C, microbial respiration, CO2 concentrations in the soil atmosphere, surface efflux of CO2, and root distribution (0- to 15-, 15- to 30-, 30- to 60-, and 60- to 80-cm depths). A comparison was made between untreated annual grassland and plots without plant cover still maintained by tillage and herbicide. In the uppermost layer (0- to 15-cm depth), total C, microbial biomass C, and respiration were lower in the tilled, bare soil than in the grassland soils, as was CO2 efflux from the soil surface. Root length near perennial bunchgrasses was lower at the surface and greater at lower depths than in the annual grass-dominated areas; a similar but less pronounced trend was observed for root biomass. Few differences in soil biological or chemical properties occurred below 15-cm depth, except that at lower depths, the CO2 concentration in the soil atmosphere was lower in the plots without vegetation, possibly from reduced production of CO2 due to the lack of root respiration. Similar microbiological properties in soil layers below 15-cm depth suggest that deeper microbiota rely on more recalcitrant C sources and are less affected by plant removal than in the surface layer, even after 6 years. Without primary production, restoration procedures with extended periods of tillage and herbicide applications led to net losses of C during the plant-free periods. However, at 4 years after planting native grasses, soil microbial biomass and activity were nearly the same as the former conditions represented by annual grassland, suggesting high resilience to the temporary disturbance caused by tillage
High precision abundances of the old solar twin HIP 102152: insights on Li depletion from the oldest sun
Get PDFWe present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex (<= 1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 +/- 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratios examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log epsilon (Li) = 0.48 +/- 0.07, 1.62 +/- 0.02, and 1.07 +/- 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.FAPESP 2010/19810-4, 2012/24392-2NASAMcDonald Observator
18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging
Get PDFWe study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800–1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are Teff = 5823 ± 6 K and log g = 4.45 ± 0.02 dex, i.e., 18 Sco is 46 ± 6 K hotter than the Sun and log g is 0.01 ± 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 ± 0.005 dex, and its microturbulence velocity is +0.02 ± 0.01 km s−1 higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02M and that it is ∼1.6 Gyr younger than the Sun.We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories in 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (∼0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general
Save Our Science: How to Inspire a New Generation of Scientists
No full textIn Save Our Science: How to Inspire a New Generation of Scientists, long time Yale professor Ainissa Ramirez makes an impassioned call for a recommitment to improve science, technology, engineering, and math (STEM) education in our schools and throughout our society. She describes what habits we need to change to make STEM fun again, as well as a plan for how to increase every child's participation in these disciplines. The 21st century requires a new kind of learner -- not someone who can simply churn out answers by rote, as has been done in the past, but a student who can think expansively and solve problems resourcefully. In order to solve the complex problems of tomorrow, the traditional academic skills of reading, 'riting, and 'rithmetic must be replaced with creativity, curiosity, critical thinking, problem solving, and collaboration skills -- skills inherent in scientific research.
About the Author
Ainissa Ramirez, Ph.D., (@blkgrlphd) is a science evangelist who is passionate about getting the general public excited about science. Before taking on this calling, she was an associate professor of mechanical engineering and materials science at Yale University. Technology Review, the magazine of the Massachusetts Institute of Technology (MIT), named her as one of the world's 100 Top Young Innovators for her contributions in transforming technology. She has been profiled by the New York Times, Discover and, Fortune magazines, ESPN, CNN, and numerous scientific magazines (Scientific American, R&D Magazine, Materials Today, and Chemical & Engineering News).
Ramirez received her training in materials science and engineering from Brown University (Sc.B.) and Stanford University (Ph.D.). Prior to working at Yale, she was a research scientist at Bell Laboratories, Lucent Technologies, in Murray Hill, N.J., where she did award-winning research. She has lectured at the California Institute of Technology (Caltech), MIT, and Harvard, Columbia, Cornell, Princeton, Northwestern, and Stanford universities.
A staunch advocate for improving the public's understanding of science, her talk at TED on the importance of science, technology, engineering, and math (STEM) education generated widespread enthusiasm. At Yale, she was the director of the award-winning science lecture series for children called Science Saturdays, and she hosts two popular-science video series called Material Marvels and Science Xplained.
She speaks nationally on the importance of making science fun and has served as a science advisor to the American Film Institute, WGBH's Nova, and several science museums. She has written as a science correspondent for Time magazine's Washington, D.C., bureau. Currently, she is co-authoring a book with Allen St. John on the science behind football, called Newton's Football, for Random House
Adenovirus humano tipo 5 modifica la fucosilación celular en un modelo in vitro de epitelio pulmonar humano
Get PDFRESUMEN
Se ha reportado que la infección con CMV (citomegalovirus), HCV (virus de la hepatitis
C), HSV-1 (herpes virus simple- 1) y VZV (virus de varicela Zoster) incrementan la
expresión de antígenos fucosilados, incluyendo sLex (Siaa2-3Galb1-4(Fuca1-
3)GlcNAcb1-R) y Ley (Fuca1-2Galb1-4(Fuca1-3)GlcNAcb1-R), lo cual es mediado por la
sobreexpresión de distintas fucosiltransferasas (FUTs) celulares. La modificación del
glicocálix con estos antígenos, podría favorecer la diseminación de progenie viral y
alterar las distintas funciones biológicas asociadas a dichos antígenos.
El adenovirus humano tipo 5 (HAd5) es un conocido agente infeccioso y vector con
distintas aplicaciones biomédicas y biotecnológicas. No obstante que los adenovirus han
sido ampliamente estudiados desde que fueron aislados en 1953, no existían reportes
en la literatura que describieran algún efecto de la infección con HAd5 u otro adenovirus,
sobre la glicosilación de las células infectadas y por lo tanto se desconocía la
participación de la glicosilación celular en la patogénesis de esta infección. El objetivo
del presente trabajo fue determinar si la infección con HAd5 provoca cambios en el perfil
de glicosilación, particularmente la fucosilación y la sialilación, de la línea celular A549,
la cual fue utilizada como modelo de epitelio pulmonar, blanco natural de la infección con
HAd5. Los resultados obtenidos mediante marcaje metabólico y unión de lectinas
mostraron que la infección con HAd5 causa un incremento significativo en la fucosilación
de novo y particularmente del enlace Fuc a1-2. Esto se respaldó por datos adicionales
obtenidos por PCR tiempo real, que mostraron que la infección con HAd5 causa una
sobreexpresión de los genes que codifican para las a1-2 fucosiltransferasas FUT1 y
FUT2. Debido a que se ha reportado que otras infecciones virales causan un aumento
de la expresión del antígeno bi-fucosilado Ley, se procedió a determinar mediante
Western Blot si la infección con HAd5 modifica su expresión. Se mostró que la infección
causa una modificación heterogénea en la expresión de este antígeno, indicando su
participación potencial en el incremento de la proliferación celular e inhibición de
apoptosis asociadas a la infección con HAd5.ABSTRACT
It has been reported that the infection with CMV, HCV, HSV-1 or VZV, through the
overexpression of host fucosyltransferases (FUT) increases the expression of
fucosylated antigens in the host cell, including sLex (Siaa2-3Galb1-4(Fuca1-3)GlcNAcb1-
R) and Ley (Fuca1-2Galb1-4(Fuca1-3)GlcNAcb1-R). The modifications of the glycocalyx
with these antigens could favor viral dissemination, but also modulate biological functions
associated to these antigens, including proliferation and apoptosis.
Human adenovirus type 5 (HAd5) is a known infectious agent and vector with different
biomedical and biotechnological applications. Although adenoviruses have been widely
studied since their first isolation in 1953, no reports are available regarding the effect of
these viruses on the glycosylation of the host cell or the potential implications of
glycosylation modulation in the pathogenesis of adenovirus infection.
The aim of this work was to determine whether HAd5 infection causes changes in the
glycosylation profile of human infected cells, particularly sialylation and fucosylation. We
used the A549 cell line as a model of respiratory epithelium, the natural target of Ad5.
The results obtained using metabolic labeling and lectin binding showed that HAd5
infection causes a significative increment in the de novo fucosylation, particularly of
Fuca1-2. This was further supported by the finding that HAd5 infection increases
expression of the genes coding for the a1-2 fucosyltransferases FUT1 and FUT2. In view
of these findings and also that other viral infections have been reported to cause an
increased expression of the bi-fucosylated antigen Ley, we proceeded to determine
through Western Blot whether HAd5 caused changes in the expression of this antigen in
infected A549 cells. It was shown that HAd5 infection causes a heterogeneous change in
Ley expression, pointing out to a potential role of this antigen in viral mechanisms that
favor proliferation and inhibit apoptosis
- …
