8,826 research outputs found
Recent Detections of a Rare Native Lady Beetle, \u3ci\u3eCoccinella Novemnotata\u3c/i\u3e (Coleoptera: Coccinellidae), in Minnesota
Coccinella novemnotata Herbst (Coleoptera: Coccinellidae) was once widespread and commonly collected in North America; however, its abundance and distribution decreased over the 1970s and 1980s. It has not been collected by recent surveys in some areas and in other areas is only rarely collected. Museum records were examined and a survey of Minnesota soybean fields was conducted via sweep-net sampling in July and August 2011. Results suggest that C. novemnotata is absent from or below the detection threshold in the majority of the state of Minnesota. However, there appears to be an area in east central Minnesota with at least sustained low, but detectable populations of C. novemnotata and it is active in agricultural crops
Geometric ergodicity for some space-time max-stable Markov chains
Max-stable processes are central models for spatial extremes. In this paper,
we focus on some space-time max-stable models introduced in Embrechts et al.
(2016). The processes considered induce discrete-time Markov chains taking
values in the space of continuous functions from the unit sphere of
to . We show that these Markov chains are
geometrically ergodic. An interesting feature lies in the fact that the state
space is not locally compact, making the classical methodology inapplicable.
Instead, we use the fact that the state space is Polish and apply results
presented in Hairer (2010)
From Gauss Graphs to Giants
We identify the operators in super Yang-Mills theory that
correspond to -BPS giant gravitons in AdSS. Our
evidence for the identification comes from (1) counting these operators and
showing agreement with independent counts of the number of giant graviton
states, and (2) by demonstrating a correspondence between correlation functions
of the super Yang-Mills operators and overlaps of the giant graviton wave
functions.Comment: 16 pages; v2: matches published versio
CFT4 as SO(4,2)-invariant TFT2
We show that correlators of local operators in four dimensional free scalar
field theory can be expressed in terms of amplitudes in a two dimensional
topological field theory (TFT2). We describe the state space of the TFT2, which
has as a global symmetry, and includes both positive and negative
energy representations. Invariant amplitudes in the TFT2 correspond to surfaces
interpolating from multiple circles to the vacuum. They are constructed from
SO(4,2) invariant linear maps from the tensor product of the state spaces to
complex numbers. When appropriate states labeled by 4D-spacetime coordinates
are inserted at the circles, the TFT2 amplitudes become correlators of the
four-dimensional CFT4. The TFT2 structure includes an associative algebra,
related to crossing in the 4D-CFT, with a non-degenerate pairing related to the
CFT inner product in the CFT4. In the free-field case, the TFT2/CFT4
correspondence can largely be understood as realization of free quantum field
theory as a categorified form of classical invariant theory for appropriate
SO(4,2) representations. We discuss the prospects of going beyond free fields
in this framework.Comment: 54 pages, 7 figures; version 2: Published version - extended
discussion of CFT4/TFT2 in terms of emergent space-time; refs added; typos
correcte
- …