Further comments-Waihi Terrace and Hamilton Ash Ages

The authors of the previous paper (Selby et al. 1971) kindly allowed us to see their manuscript, prior to publication. They have made a significant contribution to Bay of Plenty late Quaternary stratigraphy in recognising established ash beds in the coastal terrace sequence at Waihi Beach (Kear & Waterhouse, 1961). This brief note acknowledges their work, and uses their data to produce an alternative age interpretation, that implies broad dates for the formation of each of the coastal terraces and for the Hamilton Ash

Locus ceruleus regulates sensory encoding by neurons and networks in waking animals

Substantial evidence indicates that the locus ceruleus (LC)–norepinephrine (NE) projection system regulates behavioral state and state-dependent processing of sensory information. Tonic LC discharge (0.1–5.0 Hz) is correlated with levels of arousal and demonstrates an optimal firing rate during good performance in a sustained attention task. In addition, studies have shown that locally applied NE or LC stimulation can modulate the responsiveness of neurons, including those in the thalamus, to nonmonoaminergic synaptic inputs. Many recent investigations further indicate that within sensory relay circuits of the thalamus both general and specific features of sensory information are represented within the collective firing patterns of like-modality neurons. However, no studies have examined the impact of NE or LC output on the discharge properties of ensembles of functionally related cells in intact, conscious animals. Here, we provide evidence linking LC neuronal discharge and NE efflux with LC-mediated modulation of single-neuron and neuronal ensemble representations of sensory stimuli in the ventral posteriomedial thalamus of waking rats. As such, the current study provides evidence that output from the LC across a physiologic range modulates single thalamic neuron responsiveness to synaptic input and representation of sensory information across ensembles of thalamic neurons in a manner that is consistent with the well documented actions of LC output on cognition

Search for high-performance probe-fed stacked patches using optimization

High-performance circular probe-fed stacked patch antenna designs are explored through the use of numerical optimization. New trends are sought to aid understanding and to suggest novel solutions. We describe the optimization technique, present a new design trend relating efficiency and bandwidth to the choice of substrate dielectric, and propose and demonstrate a novel, optimized antenna achieving 33% bandwidth whilst maintaining greater than 80% surface wave efficiency

Fruiting Phenologies of Rainforest Plants in the Illawarra Region, New South Wales, 1988-1992

Phenological patterns of fruit production have an important influence on the ecology of frugivores, and vice versa. A longitudinal study of fruiting cycles in rainforest plants was carried out in the Illawarra region between 1988 and 1992 as part of an investigation on food resources for frugivorous birds. A total of 82 species of fruit-producing plants were recorded, and seasonal availability of fruiting plants was examined by the mean number of species in crop production per month. Fruiting plants were available year round, with peaks occurring in autumn and early winter. The crop periods of most species were subject to substantial variability from year to year. There were no positive correlations between the monthly numbers of trees, and vines and climbers in fruit and climatic variables such as rainfall and temperature. Rainforests in southeastern Australia have lower botanical diversity than those of lower latitudes, attributing to substantial geographical variation in frugivore-plant relationships. Core crop periods were determined in 23 species of trees, three species of shrubs, six species of vines and climbers. Fruiting patterns in the remaining species were sporadic. Data presented in this paper provide baseline data for further studies, with important implications for natural resource and conservation management

Archaeal abundance in post-mortem ruminal digesta may help predict methane emissions from beef cattle

The Rowett Institute of Nutrition and Health and SRUC are funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government. The project was supported by DEFRA and DA funded Agricultural Greenhouse Gas Inventory Research Platform. Our thanks are due to the excellent support staff at the SRUC Beef Research Centre, Edinburgh, also to Graham Horgan of BioSS, Aberdeen, for conducting multivariate analysis.Peer reviewedPublisher PD

Differential Sensitivity to Psychostimulants Across Prefrontal Cognitive Tasks: Differential Involvement of Noradrenergic α1- and α2-Receptors

BACKGROUND: Psychostimulants improve a variety of cognitive and behavioral processes in patients with attention-deficit/hyperactivity disorder (ADHD). Limited observations suggest a potentially different dose-sensitivity of prefrontal cortex (PFC)-dependent function (narrow inverted-U-shaped dose-response curves) versus classroom/overt behavior (broad inverted U) in children with ADHD. Recent work in rodents demonstrates that methylphenidate (MPH; Ritalin) elicits a narrow inverted-U-shaped improvement in performance in PFC-dependent tests of working memory. The current studies first tested the hypothesis that PFC-dependent tasks, in general, display narrow dose sensitivity to the beneficial actions of MPH. METHODS: The effects of varying doses of MPH were examined on performance of rats in two tests of PFC-dependent cognition, sustained attention and attentional set shifting. Additionally, the effect of pretreatment with the α₁-antagonist prazosin (.5 mg/kg) on MPH-induced improvement in sustained attention was examined. RESULTS: MPH produced a broad inverted-U-shaped facilitation of sustained attention and attentional set shifting. Prior research indicates α₁-receptors impair, whereas α₂-receptors improve, working memory. In contrast, attentional set shifting is improved with α₁-receptor activation, whereas α₂-receptors exert minimal effects in this task. Given the similar dose sensitivity of sustained attention and attentional set-shifting tasks, additional studies examined whether α₁-receptors promote sustained attention, similar to attentional set shifting. In these studies, MPH-induced improvement in sustained attention was abolished by α₁-receptor blockade. CONCLUSIONS: PFC-dependent processes display differential sensitivity to the cognition-enhancing actions of psychostimulants that are linked to the differential involvement of α₁- versus α₂-receptors in these processes. These observations have significant preclinical and clinical implications

Variational approximation for mixtures of linear mixed models

Mixtures of linear mixed models (MLMMs) are useful for clustering grouped data and can be estimated by likelihood maximization through the EM algorithm. The conventional approach to determining a suitable number of components is to compare different mixture models using penalized log-likelihood criteria such as BIC.We propose fitting MLMMs with variational methods which can perform parameter estimation and model selection simultaneously. A variational approximation is described where the variational lower bound and parameter updates are in closed form, allowing fast evaluation. A new variational greedy algorithm is developed for model selection and learning of the mixture components. This approach allows an automatic initialization of the algorithm and returns a plausible number of mixture components automatically. In cases of weak identifiability of certain model parameters, we use hierarchical centering to reparametrize the model and show empirically that there is a gain in efficiency by variational algorithms similar to that in MCMC algorithms. Related to this, we prove that the approximate rate of convergence of variational algorithms by Gaussian approximation is equal to that of the corresponding Gibbs sampler which suggests that reparametrizations can lead to improved convergence in variational algorithms as well.Comment: 36 pages, 5 figures, 2 tables, submitted to JCG

Intra-individual effects of food upon the pharmacokinetics of rifampicin and isoniazid

Background: Poor response to TB therapy might be attributable to subtherapeutic levels in drug-compliant patients. Pharmacokinetic parameters can be affected by comorbidities or the interaction of drugs with food. Objectives: This study aimed to determine the effect of food intake upon pharmacokinetics of rifampicin and isoniazid in a Peruvian population with TB. Methods: Rifampicin and isoniazid levels were analysed at 2, 4 and 6 h after drug intake in both fasting and non-fasting states using LC-MS methods. Results: Sixty patients participated in the study. The median rifampicin Cmax and AUC0–6 were higher during fasting than non-fasting: 7.02 versus 6.59 mg/L (P = 0.054) and 28.64 versus 24.31 mg·h/L (P = 0.002). There was a statistically significant delay overall of non-fasting Tmax compared with the fasting state Tmax (P = 0.005). In the multivariate analysis, besides the effect of fasting, Cmax for females was 20% higher than for males (P = 0.03). Concerning isoniazid, there were significant differences in the Cmax during non-fasting (median = 3.51 mg/L) compared with fasting (4.54 mg/L). The isoniazid dose received had an effect upon the isoniazid levels (1.26, P = 0.038). In the multivariate analysis, isoniazid exposure during fasting was found to be 14% higher than during non-fasting (CI = 1.02–1.28, P < 0.001). Neither radiological extent of the disease nor consumption of food with drug intake nor pharmacokinetics of rifampicin or isoniazid was associated with a poorer treatment outcome. Conclusions: Rifampicin in particular and isoniazid pharmacokinetics were significantly affected by the intake of the drug with food between and within individuals