1,399 research outputs found
A New Species of Hisonotus (Siluriformes, Loricariidae) of the Upper RÃo Uruguay Basin
A new species of the hypoptopomatine genus Hisonotus (Loricariidae) is described from a small tributary of the upper rı´o Uruguay basin near the border between Uruguay and Brazil. The new species can be distinguished from all other congeners by the following combination of characters: (1) presence of serrae along distal two thirds of posterior margin of pectoral-fin spine (versus serrae absent, posterior margin smooth); (2) odontodes along anterior margin of snout biserially arranged, dorsad and ventrad series separated by narrow odontode-free area covered by pad of soft tissue; (3) caudal peduncle short (27–34% SL, versus . 34% SL) and deep (13–15 % SL, versus , 13% SL); (4) eye large (15–19% HL, versus , 13% HL); and (5) caudal-fin pigmentation, when well defined, dark brown with a pair of whitish blotches on upper and lower lobes. The significance of the distribution of the new species is discussed relative to the degree of endemism of other fish groups in the Uruguay basin.Fil: Aquino, Adriana E.. American Museum of Natural History; Estados UnidosFil: Schaefer, Scott A.. American Museum of Natural History; Estados UnidosFil: Miquelarena, Amalia Maria. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto de LimnologÃa ; Argentin
Polaris: Mass and Multiplicity
Polaris, the nearest and brightest classical Cepheid, is a member of at least
a triple system. It has a wide () physical companion, the F-type dwarf
Polaris B. Polaris itself is a single-lined spectroscopic binary with an
orbital period of 30 years (Kamper, 1996, JRASC, 90, 140). By combining {\it
Hipparcos} measurements of the instantaneous proper motion with long-term
measurements and the Kamper radial-velocity orbit, Wielen et al. (2000, A&A,
360, 399) have predicted the astrometric orbit of the close companion. Using
the {\it Hubble Space Telescope} and the Advanced Camera for Surveys'
High-Resolution Channel with an ultraviolet (F220W) filter, we have now
directly detected the close companion. Based on the Wielen et al. orbit, the
{\it Hipparcos} parallax, and our measurement of the separation (
), we find a preliminary mass of 5.0 1.5 M for
the Cepheid and 1.38 0.61 M for the close companion. These
values will be refined by additional {\it HST} observations scheduled for the
next 3 years.
We have also obtained a {\it Chandra} ACIS-I image of the Polaris field. Two
distant companions C and D are not X-rays sources and hence are not young
enough to be physical companions of the Cepheid. There is one additional
stellar X-ray source in the field, located from Polaris A, which is a
possible companion. Further investigation of such a distant companion is
valuable to confirm the full extent of the system.Comment: submitted to Conference Proceedings of IAU Symp. 24
Genus Hypoptopoma.
110 p. : ill., maps ; 26 cm.
"Issued June 3, 2010."
Includes bibliographical references (p. 104-108).The systematics of Hypoptopoma Günther ‪(‬1868a‪)‬ is revised based on comprehensive evaluation of specimen collections and a phylogenetic analysis of the species. The genus Hypoptopoma comprises a distinctive assemblage of loricariid catfishes distributed in the lowland drainages of tropical, subtropical, and temperate latitudes of South America to the east of the Andes. Hypoptopoma is uniquely diagnosed among genera of the Loricariidae on the basis of the presence of a laterally expanded nuchal plate. Members of the genus can be further distinguished from all other loricariids, except the hypoptopomatin genus Oxyropsis, by the depressed head with eyes placed ventrolateral and visible from below. Hypoptopoma is further distinguished from all other Hypoptopomatini, including Oxyropsis, by the caudal peduncle posterior to the base of the anal fin ovoid in cross section and deeper in the dorsoventral axis. All species of Hypoptopoma, except H. spectabile, can be further distinguished among loricariids by the presence in adult stages of a column of variably enlarged and flattened odontodes positioned along the posterior margin of the trunk plates. Individuals of several Hypoptopoma species attain the largest body size for the subfamily Hypoptopomatinae, with standard length reaching 105 mm. Species of Hypoptopoma typically occur in streams of slow to moderate current and muddy to sandy bottom with marginal emergent vegetation. Based on verified specimen records, the species is distributed in the RÃo Amazonas basin, including the Ucayali, Madeira, and Tapajos rivers, as well as in the rivers east to the Ilha Marajo drainage ‪(‬Para, Brazil‪)‬, in the Tocantins and smaller coastal river drainages in northeastern Brazil ‪(‬Mearim‪)‬, the upper RÃo Orinoco basin, the Essequibo and Nickerie river basins of the Guiana Shield, and in the rÃos Paraguay and lower Paraná. There are no records of Hypoptopoma in the RÃo Uruguay, the Atlantic coastal drainages of Uruguay and Brazil south of Rio Mearim ‪(‬Maranão‪)‬, the upper Paraná, and Rio São Francisco systems. Fifteen species are recognized in Hypoptopoma, seven of which are newly described herein. Phylogenetic analysis of Hypoptopoma species, based on analysis of 26 characters drawn from aspects of external morphology and internal osteology, recovered a well-supported but incompletely resolved nested set of clade relationships that suggests a widespread ancestral distribution for the group in central Amazonia, plus at least four instances of divergence of a species having a peripheral distribution from an Amazonian sister group. Relationships at the basal node were unresolved. There was insufficient evidence to resolve the relationships among H. baileyi, n. sp., of the Madeira river basin, an unresolved clade comprised of H. guianense Boesemann, 1974, of the Essequibo and Nickerie basins in Guyana and Surinam; H. psilogaster Fowler, 1915, of the upper Amazon basin in Brazil and Peru; and H. thoracatum Günther, 1868a, of the upper and middle Amazon basin; and a well-supported clade that includes all other Hypoptopoma species. The latter clade was supported by four synapomorphies and includes H. brevirostratum, n. sp., of the upper Amazon basin in Brazil and Peru, H. muzuspi, n. sp., of the Tocantins basin, and a more restricted clade supported by six character-state changes comprising the remainder of the subfamily. Two species, H. spectabile ‪(‬Eigenmann, 1914‪)‬ of the upland Amazon and upper Orinoco river basins of Venezuela, Colombia, Ecuador, and Peru and H. sternoptychum ‪(‬Schaefer, 1996a‪)‬ of the lowland reaches of the Amazon River, formerly placed in the genus Nannoptopoma Schaefer, 1996, represent a clade most closely related to a nested subset of Hypoptopoma species. These former Nannoptopoma species are reassigned to Hypoptopoma, thus rendering the former generic name a subjective junior synonym of Hypoptopoma. Hypoptopoma bianale, n. sp., of the upper Amazon River basin in Brazil and Peru represents the sister group to a largely unresolved clade comprised of H. inexspectatum ‪(‬Holmberg, 1893a‪)‬ of the Paraguay-Paraná basin, H. steindachneri Boulenger, 1895, of the upper Amazon basin in Brazil and Peru, H. gulare Cope, 1878, of the upper Amazon basin, H. machadoi, n. sp., of the Orinoco basin, and a clade comprised of H. elongatum, n. sp., of the lower Tapajos and lower Trombetas rivers plus H. incognitum, n. sp., of the middle Amazon basin, Tocantins, and Mearim rivers. A key to the species of Hypoptopoma is provided
Prospectus, November 28, 1984
SPEAKING COBRAS NAMED COMMUNITY COLLEGE TEAM OF THE YEAR; Central Illinois Vietnam Veterans; Security reports thefts; Parkland election survey told; \u27There are 25 crucified saviors\u27; PC Happenings; Board of Trustees re-elect officers; Who\u27s Who Award nominations listed; Parkland Choral Union to perform \u27Messiah\u27; \u27Messiah\u27 comes again; Life Science Division has open house; Classifieds; Scott advocates negotiation versus doomsday; Creative Corner...especially for you!; Doom Story...The Final Conflict; Through another man\u27s eyes; and that is all; affair; your last veil; living together; Jesus Face; Jesus Died; This Isn\u27t It; wanting; being in love; On Being Forced to Play Backgammon After a Week in the Wilderness; only one; Searls Scouts; Talent scouts looking for fresh talent to work at Busch Gardens in 1985; King\u27s newest not his best; Parkland Community Band performs; Prompters cheer IRT; Cotton releases new solo; Original theatre production at Parkland Written, directed and produced by Lu Snyder; Carol sing is Sunday at UI; High School Quiz Bowl to be broadcast; Howard Player of the Week; Parkland loses on last-second shot; High School Notes; Cobras shoot past Illinois Central, 75-69; Lady Cobras want to schore in \u2784; Koebele plays the leadhttps://spark.parkland.edu/prospectus_1984/1002/thumbnail.jp
Polygenic scores for smoking and educational attainment have independent influences on academic success and adjustment in adolescence and educational attainment in adulthood
Sufficient conditions for bang-bang control in Hilbert space
Sufficient conditions for bang-bang and singular optimal control are established in the case of linear operator equations with cost functionals which are the sum of linear and quadratic terms, that is, Ax = u , J ( u )=( r,x )+β( x,x ), β>0. For example, if A is a bounded operator with a bounded inverse from a Hilbert space H into itself and the control set U is the unit ball in H , then an optimal control is bang-bang (has norm l) if 0⩽β1/2∥ A −1 * r ∥·∥ A ∥ 2 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45225/1/10957_2004_Article_BF00928120.pd
Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction
We present photospheric-phase observations of LSQ12gdj, a slowly-declining,
UV-bright Type Ia supernova. Classified well before maximum light, LSQ12gdj has
extinction-corrected absolute magnitude , and pre-maximum
spectroscopic evolution similar to SN 1991T and the super-Chandrasekhar-mass SN
2007if. We use ultraviolet photometry from Swift, ground-based optical
photometry, and corrections from a near-infrared photometric template to
construct the bolometric (1600-23800 \AA) light curve out to 45 days past
-band maximum light. We estimate that LSQ12gdj produced
of Ni, with an ejected mass near or slightly above the
Chandrasekhar mass. As much as 27% of the flux at the earliest observed phases,
and 17% at maximum light, is emitted bluewards of 3300 \AA. The absence of
excess luminosity at late times, the cutoff of the spectral energy distribution
bluewards of 3000 \AA, and the absence of narrow line emission and strong Na I
D absorption all argue against a significant contribution from ongoing shock
interaction. However, up to 10% of LSQ12gdj's luminosity near maximum light
could be produced by the release of trapped radiation, including kinetic energy
thermalized during a brief interaction with a compact, hydrogen-poor envelope
(radius cm) shortly after explosion; such an envelope arises
generically in double-degenerate merger scenarios.Comment: 18 pages, 10 figures, accepted to MNRAS; v2 accepted version. Spectra
available on WISEReP (http://www.weizmann.ac.il/astrophysics/wiserep/).
Natural-system photometry and bolometric light curve available as online
tables in MNRAS versio
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