1,756 research outputs found
Temperature-dependent mutational specificity of an Escherichia coli mutator, dnaQ49, defective in 3\u27---\u3e 5\u27 exonuclease (proofreading) activity
At the Edge of Objectivity: The Missouri Court of Appeals’ Deference to a Seemingly Subjective Assessment of Prejudice Under Strickland
Strickland v. Washington is often heralded as one of the most important criminal procedure cases of the last century. The opinion created a two-prong framework for analyzing a post-conviction relief claim of ineffective assistance of counsel: performance and prejudice. The focus of this Note is the prejudice prong, specifically when the post-conviction court is the same court that presided over a defendant’s trial or sentencing
Exotic Species and Overgrazing Can Drive Declines in Grassland Biodiversity and Productivity
Plant species diversity has declined rapidly in grasslands, and it is poorly known how to establish and maintain diverse mixtures containing grasses, forbs, and legumes. Each of these groups can be important. For example, grasses and forbs can produce forage and increase resistance to weeds, and legumes can produce forage and maintain high fertility by fixing nitrogen. There is some evidence that exotic (introduced) plant species and changes in land use are contributing to declines in diversity. Exotic species could be causing declines in diversity in situations where they differ from native plant species in growth rates and other plant traits. However, previous studies were based on correlative data, and we have a poor understanding of whether exotic species themselves are causing direct declines in diversity, or if associated land use changes are causing the declines in diversity
The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 Kiloparsec
We present Atacama Large Millimeter/submillimeter Array (ALMA) 870um
observations of 29 bright Herschel sources near high-redshift QSOs. The
observations confirm that 20 of the Herschel sources are submillimeter-bright
galaxies (SMGs) and identify 16 new SMG-QSO pairs that are useful to studies of
the circumgalactic medium (CGM) of SMGs. Eight out of the 20 SMGs are blends of
multiple 870um sources. The angular separations for six of the Herschel-QSO
pairs are less than 10", comparable to the sizes of the Herschel beam and the
ALMA primary beam. We find that four of these six "pairs" are actually QSOs
hosted by SMGs. No additional submillimeter companions are detected around
these QSOs and the rest-frame ultraviolet spectra of the QSOs show no evidence
of significant reddening. Black hole accretion and star formation contribute
almost equally in bolometric luminosity in these galaxies. The SMGs hosting
QSOs show similar source sizes, dust surface densities, and SFR surface
densities as other SMGs in the sample. We find that the black holes are growing
3 faster than the galaxies when compared to the present-day
black-hole-galaxy mass ratio, suggesting a QSO duty cycle of 30% in
SMGs at z ~ 3. The remaining two Herschel-detected QSOs are undetected at 870um
but each has an SMG "companion" only 9" and 12" away (71 and 95 kpc at z = 3).
They could be either merging or projected pairs. If the former, they would
represent a rare class of "wet-dry" mergers. If the latter, the QSOs would, for
the first time, probe the CGM of SMGs at impact parameters below 100 kpc.Comment: ApJ accepte
Material Properties Measurements for Selected Materials
Hugoniot equation of state measurements were made on Coconino sandstone, Vacaville basalt, Kaibab limestone, Mono Crater, pumice and Zelux (a polycarbonate resin) for pressures to 2 Mb. A single data point was obtained for fused quartz at 1.6 Mb. In addition to the hugoniot studies, the uniaxial compressive stress behavior of Vacaville basalt and Zelux was investigated at strain rates from about 10(exp -5)/sec to 10(exp 3)/second. The data presented include the stress - strain relations as a function of strain rate for these two materials
On covers of cyclic acts over monoids
In (Bull. Lond. Math. Soc. 33:385–390, 2001) Bican, Bashir and Enochs finally solved a long standing conjecture in module theory that all modules over a unitary ring have a flat cover. The only substantial work on covers of acts over monoids seems to be that of Isbell (Semigroup Forum 2:95–118, 1971), Fountain (Proc. Edinb. Math. Soc. (2) 20:87–93, 1976) and Kilp (Semigroup Forum 53:225–229, 1996) who only consider projective covers. To our knowledge the situation for flat covers of acts has not been addressed and this paper is an attempt to initiate such a study. We consider almost exclusively covers of cyclic acts and restrict our attention to strongly flat and condition (P) covers. We give a necessary and sufficient condition for the existence of such covers and for a monoid to have the property that all its cyclic right acts have a strongly flat cover (resp. (P)-cover). We give numerous classes of monoids that satisfy these conditions and we also show that there are monoids that do not satisfy this condition in the strongly flat case. We give a new necessary and sufficient condition for a cyclic act to have a projective cover and provide a new proof of one of Isbell’s classic results concerning projective covers. We show also that condition (P) covers are not unique, unlike the situation for projective covers
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