The Fa,b,c conjecture, I

In 1977 a five-part conjecture was made about a family of groups related to trivalent graphs and one part of the conjecture was proved. The conjecture completely determines all finite members of the family. Here we prove another part of the conjecture and foreshadow a paper which completes the proof of the other three parts.

The Fa,b,c conjecture is true, II

In 1977 a five-part conjecture was made about a family of groups related to trivalent graphs and subsequently two parts of the conjecture were proved. The conjecture completely determines all finite members of the family. Here we complete the proof of the conjecture by giving proofs for the remaining three parts. (c) 2006 Elsevier Inc. All rights reserved.

A role for protein kinase B beta/Akt2 in insulin-stimulated GLUT4 translocation in adipocytes

Insulin stimulates glucose uptake into muscle and fat cells by promoting the translocation of glucose transporter 4 (GLUT4) to the cell surface. Phosphatidylinositide 3-kinase (PI3K) has been implicated in this process. However, the involvement of protein kinase B (PKB)/Akt, a downstream target of PI3K in regulation of GLUT4 translocation, has been controversial. Here we report that microinjection of a PKB substrate peptide or an antibody to PKB inhibited insulin-stimulated GLUT4 translocation to the plasma membrane by 66 or 56%, respectively. We further examined the activation of PKB isoforms following treatment of cells with insulin or platelet-derived growth factor (PDGF) and found that PKB beta is preferentially expressed in both rat and 3T3-L1 adipocytes, whereas PKB alpha expression is down-regulated in 3T3-L1 adipocytes. A switch in growth factor response was also observed when 3T3-L1 fibroblasts were differentiated into adipocytes. While PDGF was more efficacious than insulin in stimulating PKB phosphorylation in fibroblasts, PDGF did not stimulate PKB beta phosphorylation to any significant extent in adipocytes, as assessed by several methods. Moreover, insulin, but not PDGF, stimulated the translocation of PKB beta to the plasma membrane and high-density microsome fractions of 3T3-L1 adipocytes. These results support a role for PKB beta in insulin-stimulated glucose transport in adipocytes.

Exploring through cover - the integrated interpretation of high resolution aeromagnetic, airborne electromagnetic and ground gravity data from the Grant's Patch area, Eastern Goldfields Province, Archaean Yigarn Craton Part B; Gravity inversion as a

The cost and risk associated with mineral exploration in Australia increases significantly as companies move into deeper regolith-covered terrain. The ability to map the bedrock and the depth of weathering within an area has the potential to decrease this risk and increase the effectiveness of exploration programs. This paper is the second in a trilogy concerning the Grant's Patch area of the Eastern Goldfields. The recent development of the VPmg potential field inversion program in conjunction with the acquisition of high-resolution gravity data over an area with extensive drilling provided an opportunity to evaluate three-dimensional gravity inversion as a bedrock and regolith mapping tool. An apparent density model of the study area was constructed, with the ground represented as adjoining 200 m by 200 m vertical rectangular prisms. During inversion VPmg incrementally adjusted the density of each prism until the free-air gravity response of the model replicated the observed data. For the Grant's Patch study area, this image of the apparent density values proved easier to interpret than the Bouguer gravity image. A regolith layer was introduced into the model and realistic fresh-rock densities assigned to each basement prism according to its interpreted lithology. With the basement and regolith densities fixed, the VPmg inversion algorithm adjusted the depth to fresh basement until the misfit between the calculated and observed gravity response was minimised. The resulting geometry of the bedrock/regolith contact largely replicated the base of weathering indicated by drilling with predicted depth of weathering values from gravity inversion typically within 15% of those logged during RAB and RC drilling.

A Nonstationary Model of Newborn EEG

The detection of seizure in the newborn is a critical aspect of neurological research. Current automatic detection techniques are difficult to assess due to the problems associated with acquiring and labelling newborn electroencephalogram (EEG) data. A realistic model for newborn EEG would allow confident development, assessment and comparison of these detection techniques. This paper presents a model for newborn EEG that accounts for its self-similar and non-stationary nature. The model consists of background and seizure sub-models. The newborn EEG background model is based on the short-time power spectrum with a time-varying power law. The relationship between the fractal dimension and the power law of a power spectrum is utilized for accurate estimation of the short-time power law exponent. The newborn EEG seizure model is based on a well-known time-frequency signal model. This model addresses all significant time-frequency characteristics of newborn EEG seizure which include; multiple components or harmonics, piecewise linear instantaneous frequency laws and harmonic amplitude modulation. Estimates of the parameters of both models are shown to be random and are modelled using the data from a total of 500 background epochs and 204 seizure epochs. The newborn EEG background and seizure models are validated against real newborn EEG data using the correlation coefficient. The results show that the output of the proposed models has a higher correlation with real newborn EEG than currently accepted models (a 10% and 38% improvement for background and seizure models, respectively).

Measurement Function Design for Visual Tracking Applications

Extracting human postural information from video sequences has proved a difficult research question. The most successful approaches to date have been based on particle filtering, whereby the underlying probability distribution is approximated by a set of particles. The shape of the underlying observational probability distribution plays a significant role in determining the success, both accuracy and efficiency, of any visual tracker. In this paper we compare approaches used by other authors and present a cost path approach which is commonly used in image segmentation problems, however is currently not widely used in tracking applications.

The effect of repeated prepulse and reflex stimulus presentations on startle prepulse inhibition

The magnitude of a startle reflex is inhibited if the reflex-eliciting stimuli is preceded by a prepulse stimulus at a short lead interval. Previous research in humans has shown that the extent of prepulse inhibition decreases over repeated presentations of reflex stimuli and prepulse-reflex stimulus pairings. The present study (N=70) investigated the effect of repeated presentations of prepulse stimuli, reflex stimuli, or prepulse-reflex stimulus pairings on prepulse inhibition. Five groups of subjects were presented during habituation training with either (a) reflex stimuli, (b) prepulse-reflex stimulus pairings, (c) a random sequence of prepulse and reflex stimuli, (d) prepulse stimuli, or (e) experimentally irrelevant light stimuli. Prepulse inhibition was reduced if startle stimuli were presented during habituation ((a), (b), (c)), but not after repeated presentation of the prepulse or the light stimulus ((d), (e)). The reduction in prepulse inhibition was abolished after dishabituation of the startle reflex. The present results indicate that habituation of the startle reflex can result in a reduction of prepulse inhibition. (C) 1998 Elsevier Science B.V.

An evaluation of selective Helicoverpa armigera control options in sweet corn

Helicoverpa armigera is a serious insect pest of sweet corn in Australia and is becoming increasingly difficult to manage with conventional chemical insecticides due to resistance problems. A number of alternative H. armigera control options were evaluated in sweet corn and compared with deltamethrin and no action (control). The alternative tactics evaluated were: heliothis nuclear polyhedrosis virus plus Trichogramma nr. brassicae releases; Bacillus thuringiensis; and Trichogramma alone. The H. tea nuclear polyhedrosis virus + Trichogramma plots had the lowest cob damage (6.0%), followed by the B. thuringiensis plots (12.0%), Trichogramma alone plots (20.2%), control plots (23.2%) and deltamethrin plots (53.5%). There was no evidence to suggest that the Trichogramma nr. brassicae releases had any impact on H. armigera egg mortality. However, there was a large natural population of Trichogramma pretiosum in all plots. The application of deltamethrin reduced the action of these wasps and predators, resulting in higher larval infestation and significantly more cob damage. The findings indicate that the pathogens heliothis nuclear polyhedrosis virus and B. thuringiensis can effectively control H. armigera when their action complements high natural levels of egg parasitism, and that they have potential for use in integrated pest management programs in sweet corn.

Transient evoked otoacoustic emissions in two-month-old infants: A normative study

Researchers have recently reported the effects of age, sex, ear asymmetry, and subject's activity status on transient evoked otoacoustic emissions (TEOAEs). The present study aimed to expand upon such reports by describing the characteristics of TEOAE spectra obtained from a cohort of 607 two-month-old infants in community child health clinics. Results indicated significant sex, ear and activity state effects on the signal:noise ratio, response. whole wave and band reproducibility values. These findings suggest the need for TEOAE normative data to be expressed as a function of sex, ear, and activity state of infants. These characteristics of TEOAE spectra may shape future investigations into appropriate pass-fail criteria for two-month-old infants.

Identification of residues involved in binding of IL5 to beta(com) using beta(IL3) and beta(com) chimeras

In mice there are two forms of the beta chain used in the IL3 receptor system, beta(com) and beta(IL3). beta(com) is used by the IL3, ILS and GM-CSF receptors whereas Pns is only used in the IL3 receptor. In this work an assay was developed to identify residues of beta(IL3) that restrict IL5 activity. It was found that such residues reside within the 2nd CRM of the molecule. Furthermore, when residues in the beta(IL3) B'-C' loop were replaced with beta(com) sequence a form of beta(IL3) was produced that was able to respond to IL5. This region is also responsible for IL3 binding to beta(IL3) in the absence of alpha chain. It is therefore an important structural motif of beta(com) and beta(IL3) responsible for both ligand interaction and specificity. (C) 1999 Federation of European Biochemical Societies.