52 research outputs found
Studies of the reproductive biology and of the structure, composition and physiology of the egg of Graphognathus leocoloma Boheman (Coleoptera : Curculionidae): a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
The published information regarding the biology and pest status of Graphognathus leucoloma Boheman is summarized. A study was made of egg development at temperatures ranging from 4 to 37.8°C and relative humidities ranging from 40 to 100%. Egg hatch was frequently very low and showed considerable variability. Median duration of development ranged from about 14 days at 31.5°C to 95-97 days at 15°C, with the developmental-hatching threshold between 12.1 and 13.5°C. Sub-threshold temperatures were lethal. Virtually no hatching occurred below 100% RH but the eggs could withstand considerable dessication and would hatch when moistened. Possible effects of humidity on the duration of development and of parental age on egg viability are also discussed. Some reasons for the very low egg viability are suggested, along with modifications to the experimental design to eliminate them. Studies were made of adult and pupal size, and of longevity, pre-oviposition period and reproductive output. Some reasons for unexpectedly low fecundity and long pre-oviposition period are discussed. The structure of the egg envelopes and the cement in which the eggs are laid was studied, using scanning and transmission electron microscopy, and Nomarski differential interference microscopy. A histo-chemical study of these structures, supplemented by some simple chemical tests, was also made, to elucidate in part their composition. The chorion is thick and composed entirely of protein; some 250,000 aeropyles are scattered over the surface, and its structure is such that it could probably act as a plastron when the egg is submerged. There is no micropyle. Disulphide linkages are probably important in the structure of the chorion, as in many other species, but unlike other beetles so far studied, no crystalline proteins were found. The vitelline membrane was found to be a three-layered structure 0.3-O.5μm thick composed of protein and acid mucopolysaccharides, and to be highly resistant to chemical attack. Waterproofing is probably provided by a layer of lipid on the outer surface of the vitelline membrane. The cement was found to be a complex, variable and heterogeneous mixture of protein and up to five acid mucopolysaccharides, which is unlike that of any other species reported. Some possible functions of the cement and the significance of its composition are suggested. A note on the citation of publications, and the referral to species and their systematic status. Any publication by three joint authors is cited in full the first time it is referred to and thereafter is abbreviated to the form: senior author et al. Publications with more than three joint authors are cited in the form: senior author et al. each time they are cited, including the first. The specific name of any organism is given in full only on the first time it is referred to, and the names of insect species and genera and their taxonomic status are listed in Appendix Five
A Global Fit to Extended Oblique Parameters
The STU formalism of Peskin and Takeuchi is an elegant method for encoding
the measurable effects of new physics which couples to light fermions
dominantly through its effects on electroweak boson propagation. However, this
formalism cannot handle the case where the scale of new physics is not much
larger than the weak scale. In this case three new parameters (V, W and X) are
required. We perform a global fit to precision electroweak data for these six
parameters. Our results differ from what is found for just STU. In particular
we find that the preference for S < 0 is not maintained.Comment: Plain TeX, 11 pages, one figure (ps file enclosed), (replaced version
corrects minor TeX problem, text unchanged) UdeM-LPN-TH-93-166, McGill-93/24,
OCIP/C-93-
The diversity of microfungi associated with grasses in the Sporobolus indicus complex in Queensland, Australia
There are five closely related Sporobolus species, collectively known as weedy Sporobolus grasses (WSG) or the rat’s tail grasses. They are fast growing, highly competitive, unpalatable weeds of pastures, roadsides and woodlands. An effective biological control agent would be a welcomed alternative to successive herbicide application and manual removal methods. This study describes the initial exploratory phase of isolating and identifying native Australian microfungi associated with WSG, prior to evaluating their efficacy as inundative biological control agents. Accurate species-level identification of plant-pathogenic microfungi associated with WSG is an essential first step in the evaluation and prioritisation of pathogenicity bioassays. Starting with more than 79 unique fungal morphotypes isolated from diseased Sporobolus grasses in Queensland, Australia, we employed multi-locus phylogenetic analyses to classify these isolates into 54 fungal taxa. These taxa belong to 22 Ascomycete families (12 orders), of which the majority fall within the Pleosporales (>24 taxa in 7 families). In the next phase of the study, the putative species identities of these taxa will allow us to prioritise those which are likely to be pathogenic based on existing literature and their known ecological roles. This study represents the first step in a systematic, high-throughput approach to finding potential plant pathogenic biological control agents
Little Higgses from an Antisymmetric Condensate
We construct an SU(6)/Sp(6) non-linear sigma model in which the Higgses arise
as pseudo-Goldstone bosons. There are two Higgs doublets whose masses have no
one-loop quadratic sensitivity to the cutoff of the effective theory, which can
be at around 10 TeV. The Higgs potential is generated by gauge and Yukawa
interactions, and is distinctly different from that of the minimal
supersymmetric standard model. At the TeV scale, the new bosonic degrees of
freedom are a single neutral complex scalar and a second copy of SU(2)xU(1)
gauge bosons. Additional vector-like pairs of colored fermions are also
present.Comment: 13 page
Bounds on 4D Conformal and Superconformal Field Theories
We derive general bounds on operator dimensions, central charges, and OPE
coefficients in 4D conformal and N=1 superconformal field theories. In any CFT
containing a scalar primary phi of dimension d we show that crossing symmetry
of implies a completely general lower bound on the central
charge c >= f_c(d). Similarly, in CFTs containing a complex scalar charged
under global symmetries, we bound a combination of symmetry current two-point
function coefficients tau^{IJ} and flavor charges. We extend these bounds to
N=1 superconformal theories by deriving the superconformal block expansions for
four-point functions of a chiral superfield Phi and its conjugate. In this case
we derive bounds on the OPE coefficients of scalar operators appearing in the
Phi x Phi* OPE, and show that there is an upper bound on the dimension of Phi*
Phi when dim(Phi) is close to 1. We also present even more stringent bounds on
c and tau^{IJ}. In supersymmetric gauge theories believed to flow to
superconformal fixed points one can use anomaly matching to explicitly check
whether these bounds are satisfied.Comment: 47 pages, 9 figures; V2: small corrections and clarification
Light Composite Vector Bosons
In gauge theories with slowly-running coupling constants, it may be possible
for four-fermion operators to be nearly marginal. Such operators can possess
asymptotically weak couplings, and can plausibly give rise to light composite
vector mesons.Comment: 16 pages (TeX w/epsf), 4 figures (uuencoded) included,
CERN-TH.6767/9
Uses and Abuses of Effective Lagrangians
Motivated by past and recent analyses we critically re-examine the use of
effective lagrangians in the literature to constrain new physics and to
determine the `physics reach' of future experiments. We demonstrate that many
calculations, such as those involving anomalous trilinear gauge-boson
couplings, either considerably overestimate loop-induced effects, or give
ambiguous answers. The source of these problems is the use of cutoffs to
evaluate the size of such operators in loop diagrams. In contrast to other
critics of these loop estimates, we prove that the inclusion of
nonlinearly-realized gauge invariance into the low-energy lagrangian is
irrelevant to this conclusion. We use an explicit example using known
multi-Higgs physics above the weak scale to underline these points. We show how
to draw conclusions regarding the nature of the unknown high-energy physics
without making reference to low-energy cutoffs.Comment: 36 page
Model-Independent Global Constraints on New Physics
Using effective-lagrangian techniques we perform a systematic survey of the
lowest-dimension effective interactions through which heavy physics might
manifest itself in present experiments. We do not restrict ourselves to special
classes of effective interactions (such as `oblique' corrections). We compute
the effects of these operators on all currently well-measured electroweak
observables, both at low energies and at the resonance, and perform a
global fit to their coefficients. Despite the fact that a great many operators
arise in our survey, we find that most are quite strongly bounded by the
current data. We use our survey to systematically identify those effective
interactions which are {\it not} well-bounded by the data -- these could very
well include large new-physics contributions. Our results may also be used to
efficiently confront specific models for new physics with the data, as we
illustrate with an example.Comment: plain TeX, 68 pages, 2 figures (postscript files appended),
McGill-93/12, NEIPH-93-008, OCIP/C-93-6, UQAM-PHE-93/08, UdeM-LPN-TH-93-15
Low-Energy Signals from Kinetic Mixing with a Warped Abelian Hidden Sector
We investigate the detailed phenomenology of a light Abelian hidden sector in
the Randall-Sundrum framework. Relative to other works with light hidden
sectors, the main new feature is a tower of hidden Kaluza-Klein vectors that
kinetically mix with the Standard Model photon and Z. We investigate the decay
properties of the hidden sector fields in some detail, and develop an approach
for calculating processes initiated on the ultraviolet brane of a warped space
with large injection momentum relative to the infrared scale. Using these
results, we determine the detailed bounds on the light warped hidden sector
from precision electroweak measurements and low-energy experiments. We find
viable regions of parameter space that lead to significant production rates for
several of the hidden Kaluza-Klein vectors in meson factories and fixed-target
experiments. This offers the possibility of exploring the structure of an extra
spacetime dimension with lower-energy probes.Comment: (1+32) Pages, 13 Figures. v2: JHEP version (minor modifications,
results unchanged
Low-Energy Probes of a Warped Extra Dimension
We investigate a natural realization of a light Abelian hidden sector in an
extended Randall-Sundrum (RS) model. In addition to the usual RS bulk we
consider a second warped space containing a bulk U(1)_x gauge theory with a
characteristic IR scale of order a GeV. This Abelian hidden sector can couple
to the standard model via gauge kinetic mixing on a common UV brane. We show
that if such a coupling induces significant mixing between the lightest U(1)_x
gauge mode and the standard model photon and Z, it can also induce significant
mixing with the heavier U(1)_x Kaluza-Klein (KK) modes. As a result it might be
possible to probe several KK modes in upcoming fixed-target experiments and
meson factories, thereby offering a new way to investigate the structure of an
extra spacetime dimension.Comment: 26 pages, 1 figure, added references, corrected minor typos, same as
journal versio
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