212,932 research outputs found
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Ambystoma opacum
Number of Pages: 2Integrative BiologyGeological Science
Phase detector assembly Patent
Detector assembly for discriminating first signal with respect to presence or absence of second signal at time of occurrence of first signa
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Dicamptodon and D. ensatus
Number of Pages: 2Integrative BiologyGeological Science
A method for calculating the effects of design errors and measurement errors on pump performance
Technique has been developed for calculating effects of design errors and measurement errors on pump performance. Error equations and charts are utilized to relate amount of error in given performance parameter to amount of error in given design or measured variable. Error equations were derived primarily for axial flow pumps, but are not limited to axial flow
Systematics of the North American menhadens: molecular evolutionary reconstructions in the genus Brevoortia (Clupeiformes: Clupeidae)
Evolutionary associations among the four North American species of menhadens (Brevoortia spp.) have not been thoroughly investigated. In the present study, classifications separating the four species into small-scaled and large-scaled groups were evaluated by using DNA data, and genetic associations within these groups were explored. Specifically, data from the nuclear genome (microsatellites) and the mitochondrial genome (mtDNA sequences) were used to elicit patterns of recent and historical evolutionary associations. Nuclear DNA data indicated limited contemporary gene flow among the species, and also indicated higher relatedness within the small-scaled and large-scaled menhadens than between these groups. Mitochondrial DNA sequences of the large-scaled menhadens indicated the presence of two ancestral lineages, one of which contained members of both species. This result may indicate genetic diver-gence (reproductive isolation) followed by secondary contact (hybridization) between these species. In contrast, a single ancestral lineage indicated incomplete genetic divergence between the small-scaled menhaden. These results are discussed in the context of the biology and demographics of each species
The ground state and the long-time evolution in the CMC Einstein flow
Let (g,K)(k) be a CMC (vacuum) Einstein flow over a compact three-manifold M
with non-positive Yamabe invariant (Y(M)). As noted by Fischer and Moncrief,
the reduced volume V(k)=(-k/3)^{3}Vol_{g(k)}(M) is monotonically decreasing in
the expanding direction and bounded below by V_{\inf}=(-1/6)Y(M))^{3/2}.
Inspired by this fact we define the ground state of the manifold M as "the
limit" of any sequence of CMC states {(g_{i},K_{i})} satisfying: i. k_{i}=-3,
ii. V_{i} --> V_{inf}, iii. Q_{0}((g_{i},K_{i}))< L where Q_{0} is the
Bel-Robinson energy and L is any arbitrary positive constant. We prove that (as
a geometric state) the ground state is equivalent to the Thurston
geometrization of M. Ground states classify naturally into three types. We
provide examples for each class, including a new ground state (the Double Cusp)
that we analyze in detail. Finally consider a long time and cosmologically
normalized flow (\g,\K)(s)=((-k/3)^{2}g,(-k/3))K) where s=-ln(-k) is in
[a,\infty). We prove that if E_{1}=E_{1}((\g,\K))< L (where E_{1}=Q_{0}+Q_{1},
is the sum of the zero and first order Bel-Robinson energies) the flow
(\g,\K)(s) persistently geometrizes the three-manifold M and the geometrization
is the ground state if V --> V_{inf}.Comment: 40 pages. This article is an improved version of the second part of
the First Version of arXiv:0705.307
Reaching DEEP in Math (Developing Educational Excellence and Proficiency in Mathematics)
This paper describes the DEEP in Math Program developed in the academic year 1998-1999 from a collaborative effort of the Louisiana Systemic lnitiative Program (LaSlP) and the Louisiana Department of Education (LDE). It includes evidence of impressive results in low achieving schools and in high-poverty districts targeted by the effort. The plan was for LaSlP to give intensive content and leadership training in Summer 1999 and academic year 1999-2000 to carefully selected. well-qualified math leaders. These leaders were then employed full-time in the 1999-2000 academic year and beyond by their local education authorities to work with all math teachers in a few designated schools at some cohesive subset of grades 3-8
Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly
Analysis of the radio-metric tracking data from the Pioneer 10/11 spacecraft
at distances between 20--70 astronomical units (AU) from the Sun has
consistently indicated the presence of an anomalous, small, constant Doppler
frequency drift. The drift is a blue-shift, uniformly changing with rate a_t =
(2.92 +/- 0.44) x 10^(-18) s/s^2. It can also be interpreted as a constant
acceleration of a_P = (8.74 +/- 1.33) x 10^(-8) cm/s^2 directed towards the
Sun. Although it is suspected that there is a systematic origin to the effect,
none has been found. As a result, the nature of this anomaly has become of
growing interest. Here we discuss the details of our recent investigation
focusing on the effects both external to and internal to the spacecraft, as
well as those due to modeling and computational techniques. We review some of
the mechanisms proposed to explain the anomaly and show their inability to
account for the observed behavior of the anomaly. We also present lessons
learned from this investigation for a potential deep-space experiment that will
reveal the origin of the discovered anomaly and also will characterize its
properties with an accuracy of at least two orders of magnitude below the
anomaly's size. A number of critical requirements and design considerations for
such a mission are outlined and addressed.Comment: 11 pages, invited talk given at ``35th COSPAR Scientific Assebly,''
July 18-24, 2004, Paris, Franc
Effects of equivalence ratio and dwell time on exhaust emissions from an experimental premixing prevaporizing burner
A flame-tube study was performed to determine the effects of equivalence ratio and residence time on exhaust emissions with premixed, prevaporized propane fuel. Nitrogen oxides emissions as low as .3 g NO2/kg fuel were measured with greater than 99% combustion efficiency at 800 K inlet temperature and an equivalence ratio of .4. For a constant combustion efficiency, lower nitrogen oxides emissions were obtained by burning very lean with relatively long residence times than by using somewhat higher equivalence ratios with shorter times
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