Spatial distribution of bednet coverage under routine distribution through the public health sector in a rural district in Kenya.

Insecticide-treated nets (ITNs) are one of the most important and cost-effective tools for malaria control. Maximizing individual and community benefit from ITNs requires high population-based coverage. Several mechanisms are used to distribute ITNs, including health facility-based targeted distribution to high-risk groups; community-based mass distribution; social marketing with or without private sector subsidies; and integrating ITN delivery with other public health interventions. The objective of this analysis is to describe bednet coverage in a district in western Kenya where the primary mechanism for distribution is to pregnant women and infants who attend antenatal and immunization clinics. We use data from a population-based census to examine the extent of, and factors correlated with, ownership of bednets. We use both multivariable logistic regression and spatial techniques to explore the relationship between household bednet ownership and sociodemographic and geographic variables. We show that only 21% of households own any bednets, far lower than the national average, and that ownership is not significantly higher amongst pregnant women attending antenatal clinic. We also show that coverage is spatially heterogeneous with less than 2% of the population residing in zones with adequate coverage to experience indirect effects of ITN protection.

Functional parcellation of attentional control regions of the brain.

Recently, a number of investigators have examined the neural loci of psychological processes enabling the control of visual spatial attention using cued-attention paradigms in combination with event-related functional magnetic resonance imaging. Findings from these studies have provided strong evidence for the involvement of a fronto-parietal network in attentional control. In the present study, we build upon this previous work to further investigate these attentional control systems. In particular, we employed additional controls for nonattentional sensory and interpretative aspects of cue processing to determine whether distinct regions in the fronto-parietal network are involved in different aspects of cue processing, such as cue-symbol interpretation and attentional orienting. In addition, we used shorter cue-target intervals that were closer to those used in the behavioral and event-related potential cueing literatures. Twenty participants performed a cued spatial attention task while brain activity was recorded with functional magnetic resonance imaging. We found functional specialization for different aspects of cue processing in the lateral and medial subregions of the frontal and parietal cortex. In particular, the medial subregions were more specific to the orienting of visual spatial attention, while the lateral subregions were associated with more general aspects of cue processing, such as cue-symbol interpretation. Additional cue-related effects included differential activations in midline frontal regions and pretarget enhancements in the thalamus and early visual cortical areas.

Nutritional Control of L1 Arrest and Recovery in Caenorhabditis elegans by Insulin-like Peptides and Signaling

Animals must coordinate development with fluctuating nutrient availability. Nutrient availability governs post-embryonic development in Caenorhabditis elegans: larvae that hatch in the absence of food do not initiate post-embryonic development but enter "L1 arrest" (or "L1 diapause") and can survive starvation for weeks, while rapidly resume normal development once get fed. Insulin-like signaling (IIS) has been shown to be a key regulator of L1 arrest and recovery. However, the C. elegans genome encodes 40 insulin-like peptides (ILPs), and it is unknown which peptides participate in nutritional control of L1 arrest and recovery. Work in other contexts has identified putative receptor agonists and antagonists, but the extent of specificity versus redundancy is unclear beyond this distinction.

We measured mRNA expression dynamics with high temporal resolution for all 40 insulin-like genes during entry into and recovery from L1 arrest. Nutrient availability influences expression of the majority of insulin-like genes, with variable dynamics suggesting complex regulation. We identified 13 candidate agonists and 8 candidate antagonists based on expression in response to nutrient availability. We selected ten candidate agonists (daf-28, ins-3, ins-4, ins-5, ins-6, ins-7, ins-9, ins-26, ins-33 and ins-35) for further characterization in L1 stage larvae. We used destabilized reporter genes to determine spatial expression patterns. Expression of candidate agonists was largely overlapping in L1 stage larvae, suggesting a role of the intestine, chemosensory neurons ASI and ASJ, and the interneuron PVT in systemic control of L1 development. Transcriptional regulation of candidate agonists was most significant in the intestine, as if nutrient uptake was a more important influence on transcription than sensory perception. Scanning in the 5' upstream promoter region of these 40 ILPs, We found that transcription factor PQM-1 and GATA putative binding sites are depleted in the promoter region of antagonists. A novel motif was also found to be over-represented in ILPs.

Phenotypic analysis of single and compound deletion mutants did not reveal effects on L1 recovery/developmental dynamics, though simultaneous disruption of ins-4 and daf-28 extended survival of L1 arrest without enhancing thermal tolerance, while overexpression of ins-4, ins-6 or daf-28 shortened L1 survival. Simultaneous disruption of several ILPs showed a temperature independent, transient dauer phenotype. These results revealed the relative redundancy and specificity among agonistic ILPs.

TGF- β and steroid hormone (SH) signaling have been reported to control the dauer formation along with IIS. Our preliminary results suggest they may also mediate the IIS control of L1 arrest and recovery, as the expression of several key components of TGF-β and SH signaling pathway genes are negatively regulated by DAF-16, and loss-of-function of these genes partially represses daf-16 null phenotype in L1 arrest, and causes a retardation in L1 development.

In summary, my dissertation study focused on the IIS, characterized the dynamics and sites of ILPs expression in response to nutrient availability, revealed the function of specific agonistic ILPs in L1 arrest, and suggested potential cross-regulation among IIS, TGF-β signaling and SH signaling in controlling L1 arrest and recovery. These findings provide insights into how post-embryonic development is governed by insulin-like signaling and nutrient availability.

Nitrogen cycle feedbacks as a control on euxinia in the mid-Proterozoic ocean

Geochemical evidence invokes anoxic deep oceans until the terminal Neoproterozoic similar to 0.55 Ma, despite oxygenation of Earth's atmosphere nearly 2 Gyr earlier. Marine sediments from the intervening period suggest predominantly ferruginous (anoxic Fe(II)-rich) waters, interspersed with euxinia (anoxic H2S-rich conditions) along productive continental margins. Today, sustained biotic H2S production requires NO3- depletion because denitrifiers outcompete sulphate reducers. Thus, euxinia is rare, only occurring concurrently with (steady state) organic carbon availability when N-2-fixers dominate the production in the photic zone. Here we use a simple box model of a generic Proterozoic coastal upwelling zone to show how these feedbacks caused the mid-Proterozoic ocean to exhibit a spatial/temporal separation between two states: photic zone NO3- with denitrification in lower anoxic waters, and N-2-fixation- driven production overlying euxinia. Interchange between these states likely explains the varying H2S concentration implied by existing data, which persisted until the Neoproterozoic oxygenation event gave rise to modern marine biogeochemistry.

Spatial and inter-decadal variability in plankton abundance and composition in the Northwest Atlantic (1958-2006)

The results of Continuous Plankton Recorder sampling in the NW Atlantic between 1958 and 2006 are presented for 11 plankton taxa in eight shelf and deep ocean regions. For shelf regions, phytoplankton abundances increased in the early 1990s, mainly in winter, as the contribution of Arctic-derived freshwater to the Newfoundland (NLS) and Scotian shelves (SS) increased. Farther east, in the sub-polar gyre, phytoplankton levels increased with rising temperatures during the 1990s and 2000s. In both areas, the changes can be explained by increased stratification. The increased influx of arctic water to the NLS in the 1990s was also probably directly responsible for the increased abundances of two arctic Calanus species (C. glacialis and C. hyperboreus) and indirectly responsible for the decreased abundance of Calanus I–IV (mainly C. finmarchicus), perhaps via changes in food composition. On the SS the arctic Calanus species increased in abundance in the 2000s, likely as the result of increased transport from the Arctic via the Gulf of St Lawrence. In the deep ocean, plankton seasonal cycles changed little over the decades and increasing phytoplankton levels in the 2000s were accompanied by increases in zooplankton abundance, suggesting bottom-up control. In shelf regions, phytoplankton increases in the 1990s were in winter and Calanus I–IV appeared earlier in spring than in previous decades. Zooplankton levels generally did not change overall however, perhaps because the species examined were mainly inactive during winter.

Spatial variability of the plankton trophic interaction in the North Sea: a new feature after the early 1970s

Traditionally, marine ecosystem structure was thought to be bottom-up controlled. In recent years, a number of studies have highlighted the importance of top-down regulation. Evidence is accumulating that the type of trophic forcing varies temporally and spatially, and an integrated view – considering the interplay of both types of control – is emerging. Correlations between time series spanning several decades of the abundances of adjacent trophic levels are conventionally used to assess the type of control: bottom-up if positive or top-down if this is negative. This approach implies averaging periods which might show time-varying dynamics and therefore can hide part of this temporal variability. Using spatially referenced plankton information extracted from the Continuous Plankton Recorder, this study addresses the potential dynamic character of the trophic structure at the planktonic level in the North Sea by assessing its variation over both temporal and spatial scales. Our results show that until the early-1970s a bottom-up control characterized the base of the food web across the whole North Sea, with diatoms having a positive and homogeneous effect on zooplankton filter-feeders. Afterwards, different regional trophic dynamics were observed, in particular a negative relationship between total phytoplankton and zooplankton was detected off the west coast of Norway and the Skagerrak as opposed to a positive one in the southern reaches. Our results suggest that after the early 1970s diatoms remained the main food source for zooplankton filter-feeders east of Orkney–Shetland and off Scotland, while in the east, from the Norwegian Trench to the German Bight, filter-feeders were mainly sustained by dinoflagellates.

Nutrient regimes control phytoplankton ecophysiology in the South Atlantic

Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton photophysiology from an across-basin South Atlantic cruise (as part of the GEOTRACES programme) characterised two dominant ecophysiological regimes which were interpreted on the basis of nutrient limitation. South of the South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters are characterised by elevated chlorophyll concentrations, a dominance by larger phytoplankton cells, and low apparent photochemical efficiency (F-v/F-m). Shipboard 24 h iron (Fe) addition incubation experiments confirmed that Fe stress was primarily responsible for the low F-v/F-m, with Fe addition to these waters, either within the artificial bottle additions or naturally occurring downstream enrichment from Gough Island, significantly increasing F-v/F-m values. To the north of the SSTC at the southern boundary of the South Atlantic Gyre, phytoplankton are characterised by high values of F-v/F-m which, coupled with the low macronutrient concentrations and increased presence of picocyanobacteria, are interpreted as conditions of Fe replete, balanced macronutrient-limited growth. Spatial correlation was found between F-v/F-m and Fe: nitrate ratios, supporting the suggestion that the relative supply ratios of these two nutrients can control patterns of limitation and consequently the ecophysiology of phytoplankton in subtropical gyre and ACC regimes.

Data processing of remotely sensed airborne hyperspectral data using the Airborne Processing Library (APL): Geocorrection algorithm descriptions and spatial accuracy assessment

Remote sensing airborne hyperspectral data are routinely used for applications including algorithm development for satellite sensors, environmental monitoring and atmospheric studies. Single flight lines of airborne hyperspectral data are often in the region of tens of gigabytes in size. This means that a single aircraft can collect terabytes of remotely sensed hyperspectral data during a single year. Before these data can be used for scientific analyses, they need to be radiometrically calibrated, synchronised with the aircraft's position and attitude and then geocorrected. To enable efficient processing of these large datasets the UK Airborne Research and Survey Facility has recently developed a software suite, the Airborne Processing Library (APL), for processing airborne hyperspectral data acquired from the Specim AISA Eagle and Hawk instruments. The APL toolbox allows users to radiometrically calibrate, geocorrect, reproject and resample airborne data. Each stage of the toolbox outputs data in the common Band Interleaved Lines (BILs) format, which allows its integration with other standard remote sensing software packages. APL was developed to be user-friendly and suitable for use on a workstation PC as well as for the automated processing of the facility; to this end APL can be used under both Windows and Linux environments on a single desktop machine or through a Grid engine. A graphical user interface also exists. In this paper we describe the Airborne Processing Library software, its algorithms and approach. We present example results from using APL with an AISA Eagle sensor and we assess its spatial accuracy using data from multiple flight lines collected during a campaign in 2008 together with in situ surveyed ground control points.

Data processing of remotely sensed airborne hyperspectral data using the Airborne Processing Library (APL): Geocorrection algorithm descriptions and spatial accuracy assessment

Remote sensing airborne hyperspectral data are routinely used for applications including algorithm development for satellite sensors, environmental monitoring and atmospheric studies. Single flight lines of airborne hyperspectral data are often in the region of tens of gigabytes in size. This means that a single aircraft can collect terabytes of remotely sensed hyperspectral data during a single year. Before these data can be used for scientific analyses, they need to be radiometrically calibrated, synchronised with the aircraft's position and attitude and then geocorrected. To enable efficient processing of these large datasets the UK Airborne Research and Survey Facility has recently developed a software suite, the Airborne Processing Library (APL), for processing airborne hyperspectral data acquired from the Specim AISA Eagle and Hawk instruments. The APL toolbox allows users to radiometrically calibrate, geocorrect, reproject and resample airborne data. Each stage of the toolbox outputs data in the common Band Interleaved Lines (BILs) format, which allows its integration with other standard remote sensing software packages. APL was developed to be user-friendly and suitable for use on a workstation PC as well as for the automated processing of the facility; to this end APL can be used under both Windows and Linux environments on a single desktop machine or through a Grid engine. A graphical user interface also exists. In this paper we describe the Airborne Processing Library software, its algorithms and approach. We present example results from using APL with an AISA Eagle sensor and we assess its spatial accuracy using data from multiple flight lines collected during a campaign in 2008 together with in situ surveyed ground control points.

Neurobiological model of visuo-spatial cognition in young Williams Syndrome children: measures of dorsal-stream and frontal function

We examine hypotheses for the neural basis of the profile of visual cognition in young children with Williams syndrome (WS). These are: (a) that it is a consequence of anomalies in sensory visual processing; (b) that it is a deficit of the dorsal relative to the ventral cortical stream; (c) that it reflects deficit of frontal function, in particular of fronto-parietal interaction; (d) that it is related to impaired function in the right hemisphere relative to the left. The tests reported here are particularly relevant to (b) and (c). They form part of a more extensive programme of investigating visual, visuospatial, and cognitive function in large group of children with WS children, aged 8 months to 15 years. To compare performance across tests, avoiding floor and ceiling effects, we have measured performance in children with WS in terms of the ‘age equivalence’ for typically developing children. In this paper the relation between dorsal and ventral function was tested by motion and form coherence thresholds respectively. We confirm the presence of a subgroup of children with WS who perform particularly poorly on the motion (dorsal) task. However, such performance is also characteristic of normally developingchildren up to 5 years: thus the WS performance may reflect an overall persisting immaturity of visuospatial processing which is particularly evident in the dorsal stream. Looking at the performance on the global coherence tasks of the entire WS group, we find that there is also a subgroup who have both high form and motion coherence thresholds, relative to the performance of children of the same chronological age and verbal age on the BPVS, suggesting a more general global processing deficit. Frontal function was tested by a counterpointing task, ability to retrieve a ball from a ‘detour box’, and the Stroop-like ‘day-night’ task, all of which require inhibition of a familiar response. When considered in relation to overall development as indexed by vocabulary, the day-night task shows little specific impairment, the detour box shows a significant delay relative to controls, and the counterpointing task shows a marked and persistent deficit in many children. We conclude that frontal control processes show most impairment in WS when they are associated with spatially directed responses, reflecting a deficit of fronto-parietal processing. However, children with WS may successfully reduce the effect of this impairment by verbally mediated strategies. On all these tasks we find a range of difficulties across individual children and a small subset of WS who show very good performance, equivalent to chronological age norms of typically developing children. Neurobiological models of visuo-spatial cognition in children with WS p.4 Overall, we conclude that children with WS have specific processing difficulties with tasks involving frontoparietal circuits within the spatial domain. However, some children with WS can achieve similar performance to typically developing children on some tasks involving the dorsal stream, although the strategies and processing may be different in the two groups.

Effect of chronic angiotensin converting enzyme inhibition on spatial memory and anxiety-like behavours in rats

Angiotensin converting enzyme inhibitors (ACEis) are widely used anti-hypertensive agents that are also reported to have positive effects on mood and cognition. The present study examined the influence of the ACEi, perindopril, on cognitive performance and anxiety measures in rats. Two groups of rats were treated orally for one week with the ACEi, perindopril, at doses of 0.1 and 1.0mg/kg/day. Learning was assessed by the reference memory task in the water maze, comparing treated to control rats. Over five training days both perindopril-treated groups learnt the location of the submerged platform in the water maze task significantly faster than control rats. A 60s probe trial on day 6 showed that the 1.0mg/kg/day group spent significantly longer time in the training quadrant than control rats. This improved performance in the swim maze task was not due to the effect of perindopril on motor activity or the anxiety levels of the rats as perindopril-treated and control animals behaved similarly in activity boxes and on the elevated+maze. These results confirm the anecdotal human studies that ACEis have a positive influence on cognition and provide possibilities for ACEis to be developed into therapies for memory loss.

Recent applications of Chemical Imaging to pharmaceutical process monitoring and quality control

Chemical Imaging (CI) is an emerging platform technology that integrates conventional imaging and spectroscopy to attain both spatial and spectral information from an object. Vibrational spectroscopic methods, such as Near Infrared (NIR) and Raman spectroscopy, combined with imaging are particularly useful for analysis of biological/pharmaceutical forms. The rapid, non-destructive and non-invasive features of CI mark its potential suitability as a process analytical tool for the pharmaceutical industry, for both process monitoring and quality control in the many stages of drug production. This paper provides an overview of CI principles, instrumentation and analysis. Recent applications of Raman and NIR-CI to pharmaceutical quality and process control are presented; challenges facing Cl implementation and likely future developments in the technology are also discussed. (C) 2007 Elsevier B.V. All rights reserved.

Design and evaluation of tinnitus synthesis methods: From spectral to spatial matching

Purpose
This study was designed to investigate methods to help patients suffering from unilateral tinnitus synthesizing an auditory replica of their tinnitus.

Materials and methods
Two semi-automatic methods (A and B) derived from the auditory threshold of the patient and a method (C) combining a pure tone and a narrow band-pass noise centred on an adjustable frequency were devised and rated on their likeness over two test sessions. A third test evaluated the stability over time of the synthesized tinnitus replica built with method C, and its proneness to merge with the patient's tinnitus. Patients were then asked to try and control the lateralisation of this single percept through the adjustment of the tinnitus replica level.

Results
The first two tests showed that seven out of ten patients chose the tinnitus replica built with method C as their preferred one. The third test, performed on twelve patients, revealed pitch tuning was rather stable over a week interval. It showed that eight patients were able to consistently match the central frequency of the synthesized tinnitus (presented to the contralateral ear) to their own tinnitus, which leaded to a unique tinnitus percept. The lateralisation displacement was consistent across patients and revealed an average range of 29dB to obtain a full lateral shift from the ipsilateral to the contralateral side.

Conclusions
Although spectrally simpler than the semi-automatic methods, method C could replicate patients' tinnitus, to some extent. When a unique percept between synthesized tinnitus and patients' tinnitus arose, lateralisation of this percept was achieved.

Timekeeping strategies operate independently from spatial and accuracy demands in beat-interception movements

The prevailing paradigm for researching sensorimotor synchronisation in humans involves finger tapping and temporal accuracy measures. However, many successful sensorimotor synchronisation actions require not only to be 'in time', but also to be in a predefined spatial position. Reaching this spatial position in many everyday actions often exceeds the average amplitude of a finger movement. The aim of this study is to address how people coordinate their movement to be in the right place at the right time when the scale of the movement varies. Does the scale of the movement and accuracy demands of the movement change the ability to accurately synchronise? To address these questions, a sensorimotor synchronisation task with three different inter-beat intervals, two different movement amplitudes and two different target widths was used. Our experiment demonstrated that people use different timing strategies-employing either a movement strategy (varying movement time) or a waiting strategy (keeping movement time constant) for large-scale movements. Those two strategies were found to be equally successful in terms of temporal accuracy and variability (spread of errors). With longer interval durations (2.5 and 3.5 s), variability of sensorimotor synchronisation performance increased (measured as the spread of errors). Analysing the data using the Vorberg and Wing (Handbook of perception and action. Academic Press, New York, pp 181-262, 1996) model shows a need to develop further existing timing models of sensorimotor synchronisation so that they could apply to large-scale movements, where different movement strategies naturally emerge.

Spatial updating across saccades during manual interception

We studied the effect of intervening saccades on the manual interception of a moving target. Previous studies suggest that stationary reach goals are coded and updated across saccades in gaze-centered coordinates, but whether this generalizes to interception is unknown. Subjects (n = 9) reached to manually intercept a moving target after it was rendered invisible. Subjects either fixated throughout the trial or made a saccade before reaching (both fixation points were in the range of -10° to 10°). Consistent with previous findings and our control experiment with stationary targets, the interception errors depended on the direction of the remembered moving goal relative to the new eye position, as if the target is coded and updated across the saccade in gaze-centered coordinates. However, our results were also more variable in that the interception errors for more than half of our subjects also depended on the goal direction relative to the initial gaze direction. This suggests that the feedforward transformations for interception differ from those for stationary targets. Our analyses show that the interception errors reflect a combination of biases in the (gaze-centered) representation of target motion and in the transformation of goal information into body-centered coordinates for action.