1,687 research outputs found
Transient lateral photovoltaic effect in patterned metal-oxide-semiconductor films
The time dependent transient lateral photovoltaic effect has been studied
with us time resolution and with chopping frequencies in the kHz range, in
lithographically patterned 21 nm thick, 5, 10 and 20 um wide and 1500 um long
Co lines grown over naturally passivated p-type Si (100). We have observed a
nearly linear dependence of the transitorial response with the laser spot
position. A transitorial response with a sign change in the laser-off stage has
been corroborated by numerical simulations. A qualitative explanation suggests
a modification of the drift-diffusion model by including the in uence of a
local inductance. Our findings indicate that the microstructuring of position
sensitive detectors could improve their space-time resolution.Comment: 4 pages, 4 figure
Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates III: Accurate Radius and Period for OGLE-TR-111-b
We present accurate V-band photometry for a planetary transit of OGLE-TR-111
acquired with VIMOS at the ESO Very Large Telescope. The measurement of this
transit allows to refine the planetary radius, obtaining R_p= 1.01 +/- 0.06
R_J. Given the mass of M_p = 0.53 M_J previously measured from radial
velocities, we confirm that the density is rho_p= 0.6 +/- 0.2 g/cm^3. We also
revise the ephemeris for OGLE-TR-111-b, obtaining an accurate orbital period P=
4.014484 +/- 0.000014 days, and predicting that the next observable transits
would occur around December 2006, and after that only in mid-2008. Even though
this period is different from previously published values, we cannot yet rule
out a constant period.Comment: 16 pages (including figures), 5 figures, 1 table. Accepted for
publication in the Astrophysical Journa
Analysis of spatio-temporal changes in annual and seasonal precipitation variability in South America-Chile and related ocean–atmosphere circulation patterns
Establishing relationships between coupled ocean–atmospheric patterns and precipitation accumulation is important to describe and predict spatio-temporal variability on annual or seasonal scales, and also to evaluate how this variability is influenced by global warming. The objective of this study was to examine the leading modes of interannual and seasonal (summer, autumn, winter, and spring) precipitation variability in South America-Chile, and their significant relationship to seasonally aggregated gridded data and climatic indices. Applying exhaustive data quality control measures to data from 238 rain gauges with different lengths of records between 1893 and 2013, a new data set was created with the objective of obtaining reliable records for further analysis. A comprehensive analysis through empirical orthogonal functions (EOF) allowed for determination of the leading modes of annual and seasonal precipitation and their main spatial patterns for the whole country. The percentage of explained variance in the relationship between seasonally aggregated indices and the leading modes of precipitation confirmed that most of the interannual and winter precipitation variability in Chile is linked to the seasonal aggregation of El Nino Southern Oscillation (ENSO). The leading modes of summer, autumn, and spring precipitation were mostly linked to seasonal aggregations of the Madden and Julian Oscillation (MJO), and the Antarctic Oscillation (AAO)
Kepler-413b: a slightly misaligned, Neptune-size transiting circumbinary planet
We report the discovery of a transiting, Rp = 4.347+/-0.099REarth,
circumbinary planet (CBP) orbiting the Kepler K+M Eclipsing Binary (EB) system
KIC 12351927 (Kepler-413) every ~66 days on an eccentric orbit with ap =
0.355+/-0.002AU, ep = 0.118+/-0.002. The two stars, with MA =
0.820+/-0.015MSun, RA = 0.776+/-0.009RSun and MB = 0.542+/-0.008MSun, RB =
0.484+/-0.024RSun respectively revolve around each other every
10.11615+/-0.00001 days on a nearly circular (eEB = 0.037+/-0.002) orbit. The
orbital plane of the EB is slightly inclined to the line of sight (iEB =
87.33+/-0.06 degrees) while that of the planet is inclined by ~2.5 degrees to
the binary plane at the reference epoch. Orbital precession with a period of
~11 years causes the inclination of the latter to the sky plane to continuously
change. As a result, the planet often fails to transit the primary star at
inferior conjunction, causing stretches of hundreds of days with no transits
(corresponding to multiple planetary orbital periods). We predict that the next
transit will not occur until 2020. The orbital configuration of the system
places the planet slightly closer to its host stars than the inner edge of the
extended habitable zone. Additionally, the orbital configuration of the system
is such that the CBP may experience Cassini-States dynamics under the influence
of the EB, in which the planet's obliquity precesses with a rate comparable to
its orbital precession. Depending on the angular precession frequency of the
CBP, it could potentially undergo obliquity fluctuations of dozens of degrees
(and complex seasonal cycles) on precession timescales.Comment: 48 pages, 13 figure
The origin of the Acheulean: the 1.7 million-year-old site of FLK West, Olduvai Gorge (Tanzania)
The appearance of the Acheulean is one of the hallmarks of human evolution. It represents the
emergence of a complex behavior, expressed in the recurrent manufacture of large-sized tools, with
standardized forms, implying more advance forethought and planning by hominins than those required
by the precedent Oldowan technology. The earliest known evidence of this technology dates back to
c. 1.7 Ma. and is limited to two sites (Kokiselei [Kenya] and Konso [Ethiopia]), both of which lack fauna.
The functionality of these earliest Acheulean assemblages remains unknown. Here we present the
discovery of another early Acheulean site also dating to c. 1.7 Ma from Olduvai Gorge. This site provides
evidence of the earliest steps in developing the Acheulean technology and is the oldest Acheulean site in
which stone tools occur spatially and functionally associated with the exploitation of fauna. Simple and
elaborate large-cutting tools (LCT) and handaxes co-exist at FLK West, showing that complex cognition
was present from the earliest stages of the Acheulean. Here we provide a detailed technological study
and evidence of the use of these tools on the butchery and consumption of fauna, probably by early
Homo erectus sensu lato
Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates IV: The Puzzle of the Extremely Red OGLE-TR-82 Primary Solved
We present precise new V, I, and K-band photometry for the planetary transit
candidate star OGLE-TR-82. Good seeing V-band images acquired with VIMOS
instrument at ESO VLT allowed us to measure V=20.6+-0.03 mag star in spite of
the presence of a brighter neighbour about 1" away. This faint magnitude
answers the question why it has not been possible to measure radial velocities
for this object. One transit of this star has been observed with GMOS-S
instrument of GEMINI-South telescope in i and g-bands. The measurement of the
transit allows us to verify that this is not a false positive, to confirm the
transit amplitude measured by OGLE, and to improve the ephemeris. The transit
is well defined in i-band light curve, with a depth of A_i=0.034 mag. It is
however, less well defined, but deeper (A_g=0.1 mag) in the g-band, in which
the star is significantly fainter. The near-infrared photometry obtained with
SofI array at the ESO-NTT yields K=12.2+-0.1 and V-K=8.4+-0.1, so red that it
is unlike any other transit candidate studied before. Due to the extreme nature
of this object, we have not yet been able to measure velocities for this star,
but based on the new data we consider two different possible configurations:(1)
a nearby M7V star, or (2) a blend with a very reddened distant red giant. The
nearby M7V dwarf hypothesis would give a radius for the companion of
R_p=0.3+-0.1 R_J, i.e. the size of Neptune. Quantitative analysis of near-IR
spectroscopy finally shows that OGLE-TR-82 is a distant, reddened metal poor
early K giant. This result is confirmed by direct comparison with stellar
templates that gives the best match for a K3III star. Therefore, we discard the
planetary nature of the companion. Based on all the new data, we conclude that
this system is a main-sequence binary blended with a background red giant.Comment: 26 pages, 9 figures, ApJ accepte
Revascularization of the Periodontium After Tooth Grafting in Monkeys
In replanted and homo transplanted teeth a vascular network developed in the blood clot between the two parts of the torn periodontium, which allowed the grafted ligament to regain its vascularity. When dentoalveolar ankylosis developed, the periodontal vasculature was split into a number of vascular clusters. In homotransplants, a definite cellular immunologic response by the host was absent. An acrylic radicular obturator was used.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67229/2/10.1177_00220345710500025101.pd
Gemini-GRACES high-quality spectra of Kepler evolved stars with transiting planets: I. Detailed characterization of multi-planet systems Kepler-278 and Kepler-391
Aims. Kepler-278 and Kepler-391 are two of the three evolved stars known to date on the red giant branch (RGB) to host multiple short-period transiting planets. Moreover, the planets orbiting Kepler-278 and Kepler-391 are among the smallest discovered around RGB stars. Here we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES for Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances for 25 elements. Nine of these elements and the carbon isotopic ratios, 12C∕ 13C, had not previously been measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is ~15% less massive than previously reported. The abundances of C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, and Ce, in both stars, are consistent with those of nearby evolved thin disk stars. Kepler-391 presents a relatively high abundance of lithium (A(Li)NLTE = 1.29 ± 0.09 dex), which is likely a remnant from the main-sequence phase. The precise spectroscopic parameters of Kepler-278 and Kepler-391, along with their high 12C∕ 13C ratios, show that both stars are just starting their ascent on the RGB. The planets Kepler-278b, Kepler-278c, and Kepler-391c are warm sub-Neptunes, whilst Kepler-391b is a hot sub-Neptune that falls in the hot super-Earth desert and, therefore, it might be undergoing photoevaporation of its outer envelope. The high-precision obtained in the transit times allowed us not only to confirm Kepler-278c's TTV signal, but also to find evidence of a previously undetected TTV signal for the inner planet Kepler-278b. From the presence of gravitational interaction between these bodies we constrain, for the first time, the mass of Kepler-278b (Mp = 56 -13+37 M⊕ ) and Kepler-278c (Mp = 35 -21+9.9 M⊕ ). The mass limits, coupled with our precise determinations of the planetary radii, suggest that their bulk compositions are consistent with a significant amount of water content and the presence of H2 gaseous envelopes. Finally, our photodynamical analysis also shows that the orbits of both planets around Kepler-278 are highly eccentric (e ~ 0.7) and, surprisingly, coplanar. Further observations (e.g., precise radial velocities) of this system are needed to confirm the eccentricity values presented here.Fil: Jofré, Edgardo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Almenara, J.M.. Universidad de Ginebra; SuizaFil: Petrucci, Romina Paola. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Diaz, Rodrigo Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gómez Maqueo Chew, Y.. Universidad Nacional Autónoma de México; MéxicoFil: Martioli, E.. Laboratorio Nacional de Astrofísica; BrasilFil: Ramírez, I.. Tacoma Community College; Estados UnidosFil: García, Luciano Héctor. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Saffe, Carlos. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Canul, E. F.. Universidad Nacional Autónoma de México; MéxicoFil: Buccino, Andrea Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gómez, Marcos Javier. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Moreno Hilario, E.. Universidad Nacional Autónoma de México; Méxic
Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates: II. Transits of OGLE-TR-113-b in the Optical and Near-IR
We present precise V and Ks-band transit photometry for the planetary host
star OGLE-TR-113. Using the Ks-band photometry, we confirm the dwarf nature of
OGLE-TR-113, and obtain new estimates for its effective temperature, distance
and reddening. We employ the V-band photometry to obtain planetary and orbit
parameters from the transit fit, a= (0.0232 \pm 0.0038) AU, orbital period P=
(1.4324752 \pm 0.0000015) days, i= 86.7 - 90, R_p= (1.09 \pm 0.09) R_J. These
values are in excellent agreement with previous works. Assuming a mass M_p=
(1.32 \pm 0.19) M_J for the planet we obtain its mean density \rho= (1.26 \pm
0.50) g cm^{-3}, also in agreement with previous works. The transit observed in
the Ks-band has a larger scatter and we find its amplitude to be consistent
with that in the V-band. In this way, we find an independent confirmation of
the planetary nature of OGLE-TR-113b.Comment: 26 pages, 10 figures, 1 table. Accepted for publication in the
Astrophysical Journa
Flavour Violation in SUSY SU(5) GUT at Large tan beta
We study flavour violation in the minimal SUSY SU(5) GUT assuming all the
third generation Yukawa couplings to be due to the renormalizable physics above
GUT scale. At large as suggested by Yukawa unification in SU(5),
sizable flavour violation in the left (right) slepton (down squark) sector is
induced due to renormalization effects of down type Yukawa couplings between
GUT and Planck scales in addition to the flavour violation in the right slepton
sector. The new flavour physics contribution to mixing
is small but might be of phenomenological interest in the case of The sign of the latter contribution is the same as the sign of the
dominant chargino contribution, thus making the constraints on SUSY scale
coming from somewhat more restrictive. The most important
feature of the considered scenario is the large rate of lepton flavour
violation. Given the present experimental constraints, the and
conversion branching ratios are above the sensitivity of the planned
experiments unless the SUSY scale is pushed above one TeV.Comment: 22 pages, 7 figure
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