22,209 research outputs found
Nuclear k_T in d+Au Collisions from Multiparticle Jet Reconstruction at STAR
This paper presents the most recent nuclear k_T measurements from STAR
derived from multiparticle jet reconstruction of d+Au and p+p collisions at
sqrt(s)=200 GeV. Since jets reconstructed from multiple particles are
relatively free of fragmentation biases, nuclear k_T can be measured with
greater certainty in this way than with traditional di-hadron correlations.
Multi-particle jet reconstruction can also be used for a direct measurement of
the fragmentation function.Comment: 4 pages, 3 figures, QM2005 Conference poster proceedings published in
Acta Physica Hungarica
Dr. J. E. McPherson, Educator and Researcher Extraordinaire: Biographical Sketch and List of Publications
(excerpt)
Like many outstanding naturalists, John E. (“Jay”) McPherson grew up with a strong interest in the natural world, especially insects. This innate curiosity led him to enroll as a zoology major at San Diego State University in 1959. Upon completion of his undergraduate degree, he continued on to pursue his interest in insect biology, completing a Master’s thesis on the life history and morphology of a poorly known species of Notonectidae. Shortly thereafter, a teaching assistantship enabled him to pursue a Ph.D. at Michigan State University in East Lansing, where his research involved distinguishing two closely related species of bark beetles. During this period, Jay also worked on various pest species, including the cereal leaf beetle, pine tip beetle, and pine cone beetle
The Ecology and Evolution of Ant- Aphid Interactions
The evolution of species interactions is a fascinating subject, and one of vital
importance if we are to understand how biological communities change over time.
This thesis considers the interaction between aphids (Homoptera) and ants
(Formicidae). Ants tend aphids for sugary honeydew and in return provide a variety of
protective services. A literature review in Chapter 1 introduces the subject and
provides background information. Chapter 2 considers ant- aphid interactions in a
community setting. Specifically, I consider the fitness effects of the ant- aphid
interaction on host plants. Net benefits or costs to plants depend on the densities of
ants and aphids; these densities may themselves change depending on context
dependent factors. Chapters 3 and 4 consider how semiochemicals can allow species
to respectively maintain or avoid synchrony in space and time with mutualists or
antagonists. Chapter 3 shows ladybirds avoid prey patches guarded by ants by
reducing oviposition in response to ant semiochemicals. Chapter 4 shows that aphid
walking dispersal can be limited by ant semiochemicals. This may be adaptive for
aphids to remain in areas of enemy- free space. Alternatively, if levels of kin
competition are high limited dispersal could be costly to aphids. In Chapter 5 I
consider interactions between invasive and native ants. Ecological dominance in ants
may be mediated by the ability to monopolise honeydew- producing resources.
Chapter 6 explores ants’ decisions whether to tend or prey upon aphids. Predation of
aphids depends on colony demand (e.g. through cues from the presence of larvae) as
well as the quality or quantity of supply (e.g. increased predation of unproductive
aphids). Finally, Chapter 7 deals with macroevolutionary patterns in the interaction
between ants and aphids. Specifically, I identify ecological traits that characterise
aphid- tending ants. A final discussion chapter summarises how ant-aphid interactions
fit into existing mutualism theory
Model-Independent Bounds on
We present a model-independent bound on . This bound is constructed by constraining the form
factors through a combination of dispersive relations, heavy-quark relations at
zero-recoil, and the limited existing determinations from lattice QCD. The
resulting 95\% confidence-level bound, , agrees
with the recent LHCb result at , and rules out some previously
suggested model form factors.Comment: 19 pages, 4 figures, JHEP format, revised to match published versio
Tropidosteptes forestierae (Hemiptera: Heteroptera: Miridae: Mirinae): a new species of Plant Bug injuring ornamental Florida Swampprivet, Forestiera segregata (Oleaceae), in South Florida
The mirine plant bug Tropidosteptes forestierae, new species (Hemiptera: Miridae) is described from
Collier County, Florida, where it was found causing serious injury to an extensive ornamental hedge of Florida swampprivet, Forestiera segregata (Jacq.) Krug and Urb. (Oleaceae). Adult male and female, fifth instar, and egg are described. Color images of the adults, nymph, egg, and injury; scanning photomicrographs of selected adult structures; and illustrations of male genitalia are provided. A key to help distinguish the 16 species of Tropidosteptes known to occur in the southeastern United States is given
Good approximate quantum LDPC codes from spacetime circuit Hamiltonians
We study approximate quantum low-density parity-check (QLDPC) codes, which
are approximate quantum error-correcting codes specified as the ground space of
a frustration-free local Hamiltonian, whose terms do not necessarily commute.
Such codes generalize stabilizer QLDPC codes, which are exact quantum
error-correcting codes with sparse, low-weight stabilizer generators (i.e. each
stabilizer generator acts on a few qubits, and each qubit participates in a few
stabilizer generators). Our investigation is motivated by an important question
in Hamiltonian complexity and quantum coding theory: do stabilizer QLDPC codes
with constant rate, linear distance, and constant-weight stabilizers exist?
We show that obtaining such optimal scaling of parameters (modulo
polylogarithmic corrections) is possible if we go beyond stabilizer codes: we
prove the existence of a family of approximate QLDPC
codes that encode logical qubits into physical
qubits with distance and approximation infidelity
. The code space is
stabilized by a set of 10-local noncommuting projectors, with each physical
qubit only participating in projectors. We
prove the existence of an efficient encoding map, and we show that arbitrary
Pauli errors can be locally detected by circuits of polylogarithmic depth.
Finally, we show that the spectral gap of the code Hamiltonian is
by analyzing a spacetime circuit-to-Hamiltonian
construction for a bitonic sorting network architecture that is spatially local
in dimensions.Comment: 51 pages, 13 figure
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