763 research outputs found
Host and Habitat Use by Parasitoids (Hymenoptera: Pteromalidae) of House Fly and Stable Fly (Diptera: Muscidae) Pupae
House fly and stable fly pupae were collected during the summer from a dairy farm in northern Illinois. Spalangia nigroaenea accounted for most of the parasitoids recovered from house flies. Spalangia nigra, S. endius, Muscidifurax spp., and S. nigroaenea accounted for most of the parasitoids from stable flies. The majority of flies were house flies late in the summer and stable flies early in the summer. Higher percentages of house flies tended to be in samples containing lower substrate moisture and higher substrate temperature. Parasitism of stable flies started earlier and peaked weeks before that of house flies, with overall parasitism highest from mid-to late-summer. Parasitism of house flies, but not stable flies, differed significantly among habitats, being greater in calf hutches than in edge samples. Hymenopterous parasitoids from house flies tended to include a greater percentage of S. nigroaenea (and a lower percentage of Muscidifurax spp.) in calf hutches versus drainage or edge habitats and in sub- strates consisting of mostly wood shavings versus mostly manure. Within samples, differential parasitism of fly species was not detected for S. nigroaenea, S. endius, or Muscidifurax spp.; but S. nigra preferentially parasitized stable flies
A Three-Flavor Chiral Effective Model with Four Baryonic Multiplets within the Mirror Assignment
In the case of three quark flavors, (pseudo)scalar diquarks transform as
antiquarks under chiral transformations. We construct four spin-1/2 baryonic
multiplets from left- and right-handed quarks as well as left- and right-handed
diquarks. The fact that two of these multiplets transform in a "mirror" way
allows for chirally invariant mass terms. We then embed these baryonic
multiplets into the Lagrangian of the so-called extended Linear Sigma Model,
which features (pseudo)scalar and (axial-)vector mesons, as well as glueballs.
Reducing the Lagrangian to the two-flavor case, we obtain four doublets of
nucleonic states. These mix to produce four experimentally observed states with
definite parity: the positive-parity nucleon and Roper resonance
, as well as the negative-parity resonances and .
We determine the parameters of the nucleonic part of the Lagrangian from a fit
to masses and decay properties of the aforementioned states. Studying the limit
of vanishing quark condensate, we conclude that and , as well
as and form pairs of chiral partners.Comment: 19 pages, 3 figure
Host and Habitat Use by Parasitoids (Hymenoptera: Pteromalidae) of House Fly and Stable Fly (Diptera: Muscidae) Pupae
House fly and stable fly pupae were collected during the summer from a dairy farm in northern Illinois. Spalangia nigroaenea accounted for most of the parasitoids recovered from house flies. Spalangia nigra, S. endius, Muscidifurax spp., and S. nigroaenea accounted for most of the parasitoids from stable flies. The majority of flies were house flies late in the summer and stable flies early in the summer. Higher percentages of house flies tended to be in samples containing lower substrate moisture and higher substrate temperature. Parasitism of stable flies started earlier and peaked weeks before that of house flies, with overall parasitism highest from mid-to late-summer. Parasitism of house flies, but not stable flies, differed significantly among habitats, being greater in calf hutches than in edge samples. Hymenopterous parasitoids from house flies tended to include a greater percentage of S. nigroaenea (and a lower percentage of Muscidifurax spp.) in calf hutches versus drainage or edge habitats and in sub- strates consisting of mostly wood shavings versus mostly manure. Within samples, differential parasitism of fly species was not detected for S. nigroaenea, S. endius, or Muscidifurax spp.; but S. nigra preferentially parasitized stable flies
Chaos or Noise - Difficulties of a Distinction
In experiments, the dynamical behavior of systems is reflected in time
series. Due to the finiteness of the observational data set it is not possible
to reconstruct the invariant measure up to arbitrary fine resolution and
arbitrary high embedding dimension. These restrictions limit our ability to
distinguish between signals generated by different systems, such as regular,
chaotic or stochastic ones, when analyzed from a time series point of view. We
propose to classify the signal behavior, without referring to any specific
model, as stochastic or deterministic on a certain scale of the resolution
, according to the dependence of the -entropy,
, and of the finite size Lyapunov exponent,
, on .Comment: 24 pages RevTeX, 9 eps figures included, two references added, minor
corrections, one section has been split in two (submitted to PRE
Room temperature high frequency transport of Dirac fermions in epitaxially grown Sb_2Te_3 based topological insulators
We report on the observation of photogalvanic effects in epitaxially grown
Sb_2Te_3 three-dimensional (3D) topological insulators (TI). We show that
asymmetric scattering of Dirac electrons driven back and forth by the terahertz
electric field results in a dc electric current. Due to the "symmetry
filtration" the dc current is generated in the surface electrons only and
provides an opto-electronic access to probe the electric transport in TI,
surface domains orientation and details of electron scattering even in 3D TI at
room temperature where conventional surface electron transport is usually
hindered by the high carrier density in the bulk
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