2,927 research outputs found
Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes
Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. para-Substituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta[b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo- and thieno-[2,3e]pyridines respectively. Sequential E- to Z-benzylidene group isomerisation and six [pi]-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone O-allyloxime, singlet excited states are involved in both steps
Nova Sagittarii 1994 #1 (V4332 Sagittarii): The Discovery and Evolution of an Unusual Luminous Red Variable Star
We report photometry and spectroscopy of the evolution of Nova Sagittarii
1994 #1 (V4332 Sagittarii) during outburst. We compare the photometric and
spectral evolution of this outburst to known classes of outbursts -- including
classical novae and outbursts occurring on symbiotic stars -- and find this
object does NOT conform to any known class of outburst. The closest match to
the behavior of this unusual object is M31 RV, an extremely luminous and red
variable object discovered in the bulge of M31 in 1988. However, the temporal
behavior and maximum luminosity of the two events differ by several orders of
magnitude, requiring substantial intrinsic variation if these two events are
members the same type of outburst.
Our model of the spectroscopic evolution of this outburst shows that the
effective temperature cooled from 4400 K to 2300 K over the three month span of
our observations. In combination with line diagnostics in our later spectra,
including [OI] lambda 5577 and the dramatic increase in the Halpha to Hbeta
ratio, we infer the existence of a cool, dense (N_e ~ 10^{8-9} cm^{-3})
envelope that is optically thick in the Hydrogen Balmer recombination lines
(case C). We suggest that a nuclear event in a single star, in which a slow
shock drove the photosphere outwards, can power the observed luminosity
evolution and the emission spectrum.Comment: Accepted for publication in AJ. 24 pages including 8 embedded
postscript figures. Also available at
http://www.astronomy.ohio-state.edu/~martini/pub
Associations between body mass index and suicide in the veterans affairs health system
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102714/1/oby20422.pd
Predictors of injury-related and non-injury-related mortality among veterans with alcohol use disorders
To describe the association between alcohol use disorders (AUDs) and mortality and to examine risk factors for and all-cause, injury-related and non-injury-related mortality among those diagnosed with an AUD.Department of Veterans Affairs, Veterans Health Administration (VHA).A cohort of individuals who received health care in VHA during the fiscal year (FY) 2001 ( n = 3 944 778), followed from the beginning of FY02 through the end of FY06.Demographics and medical diagnoses were obtained from VHA records. Data on mortality were obtained from the National Death Index.Controlling for age, gender and race and compared to those without AUDs, individuals with AUDs were more likely to die by all causes [hazard ratio (HR) = 2.30], by injury-related (HR = 3.29) and by non-injury-related causes (HR = 2.21). Patients with AUDs died 15 years earlier than individuals without AUDs on average. Among those with AUDs, Caucasian ethnicity and all mental illness diagnoses that were assessed were associated more strongly with injury-related than non-injury-related mortality. Also among those with AUDs, individuals with medical comorbidity and older age were at higher risk for non-injury related compared to injury-related mortality.In users of a large health-care system, a diagnosis of an AUD is associated significantly with increased likelihood of dying by injury and non-injury causes. Patients with a diagnosis of an AUD who die from injury differ significantly from those who die from other medical conditions. Prevention and intervention programs could focus separately upon selected groups with increased risk for injury or non-injury-related death.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79146/1/j.1360-0443.2010.03024.x.pd
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Session B1: Lessons Learned from Tropical Storm Irene 2.0: How Flood Resiliency Benefits of Stream Simulation Designs Are Changing Policy within the U.S.
Abstract
Stream simulation design is a geomorphic, engineering, and ecologically-based approach to designing road-stream crossings that creates a natural and dynamic channel through the crossing structure similar in dimensions and characteristics to the adjacent, natural channel, allowing for unimpeded passage of aquatic organisms, debris, and water during various flow conditions, including floods. A retrospective case study of the survival and failure of road-stream crossings was conducted in the upper White River watershed and the Green Mountain National Forest in Vermont following record flooding from Tropical Storm Irene in August 2011. Damage was largely avoided at two road-stream crossings where stream simulation design was implemented, and extensive at multiple road-stream crossings constructed using traditional undersized, hydraulic designs. Cost analyses suggest that relatively modest increases in initial investment to implement stream simulation designs yield substantial societal and economic benefits. Numerous other examples across the country of stream simulation designs surviving large flood events underscore these benefits. Four years after the historic Irene flood event, policy changes at state and federal levels across the U.S. suggest that the flood resiliency of culverts is gaining momentum as a policy driver amid growing public sensitivity to climate change risks and the importance of restoring ecological connectivity and protecting investments in transportation infrastructure
Detection of Lyman-Alpha Emission From a Triple Imaged z=6.85 Galaxy Behind MACS J2129.4-0741
We report the detection of Ly emission at \AA{} in the
Keck/DEIMOS and \HST WFC3 G102 grism data from a triply-imaged galaxy at
behind galaxy cluster MACS J2129.40741. Combining the
emission line wavelength with broadband photometry, line ratio upper limits,
and lens modeling, we rule out the scenario that this emission line is \oii at
. After accounting for magnification, we calculate the weighted average
of the intrinsic Ly luminosity to be
and Ly equivalent
width to be \AA{}. Its intrinsic UV absolute magnitude at 1600\AA{} is
mag and stellar mass , making
it one of the faintest (intrinsic ) galaxies with
Ly detection at to date. Its stellar mass is in the typical
range for the galaxies thought to dominate the reionization photon budget at
; the inferred Ly escape fraction is high (\%),
which could be common for sub- galaxies with Ly
emission. This galaxy offers a glimpse of the galaxy population that is thought
to drive reionization, and it shows that gravitational lensing is an important
avenue to probe the sub- galaxy population.Comment: Accepted by ApJ Letter
The social lives of isolates (and small language families):The case of the Northwest Amazon
The Americas are home to patches of extraordinary linguistic (genealogical) diversity. These high-diversity areas are particularly unexpected given the recent population of the Americas. In this paper, we zoom in on one such area, the Northwest Amazon, and address the question of how the diversity in this area has persisted to the present. We contrast two hypotheses that claim opposite mechanisms for the maintenance of diversity: the isolation hypothesis suggests that isolation facilitates the preservation of diversity, while the integration hypothesis proposes that conscious identity preservation in combination with contact drives diversity maintenance. We test predictions for both hypotheses across four disciplines: biogeography, cultural anthropology, population genetics and linguistics. Our results show signs of both isolation and integration, but they mainly suggest considerable diversity in how groups of speakers have interacted with their surroundings
Galileons as Wess-Zumino Terms
We show that the galileons can be thought of as Wess-Zumino terms for the
spontaneous breaking of space-time symmetries. Wess-Zumino terms are terms
which are not captured by the coset construction for phenomenological
Lagrangians with broken symmetries. Rather they are, in d space-time
dimensions, d-form potentials for (d+1)-forms which are non-trivial co-cycles
in Lie algebra cohomology of the full symmetry group relative to the unbroken
symmetry group. We introduce the galileon algebras and construct the
non-trivial (d+1)-form co-cycles, showing that the presence of galileons and
multi-galileons in all dimensions is counted by the dimensions of particular
Lie algebra cohomology groups. We also discuss the DBI and conformal galileons
from this point of view, showing that they are not Wess-Zumino terms, with one
exception in each case.Comment: 49 pages. v2 minor changes, version appearing in JHE
Discovery of a Mid-L Dwarf Companion to the L 262-74 System
We present the discovery of CWISE J151044.74524923.5, a wide low-mass
companion to the nearby (24.7 pc) system L 262-74, which was identified
through the Backyard Worlds: Planet 9 citizen science project. We detail the
properties of the system, and we assess that this companion is a mid-L dwarf,
which will need to be verified spectroscopically. With an angular separation of
74\farcs3, we estimate a projected physical separation of 1837 au from
the central system
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