The Limits of In-Run Calibration of MEMS Inertial Sensors and Sensor Arrays

MEMS accelerometers and gyroscope triads now cost less than $10, potentially opening up many new applications. However, these sensors require calibration prior to navigation use. This paper determines the maximum tolerable sensor errors for in-run calibration techniques using a basic Kalman filter by developing criteria for filter failure and performing Monte Carlo simulations for a range of different sensor specifications, and both car and UAV motion-profiles. Gyroscope bias is found to be the most significant with the maximum tolerable value of its SD varying between 0.75 and 2.6 deg/s depending on the value of the specification of the other sensor sources. The paper shows that pre-calibration and smart array techniques could potentially enable in-run calibration to be applied to lower-quality sensors. However, the estimation of scale-factor cross-coupling and gyroscope g-dependent errors could potentially be critical. Armed with this knowledge, designers can avoid both unnecessary design complexity and computational load of over-engineering and the poor navigation performance of inadequate filters

Context Detection for Advanced Self-Aware Navigation using Smartphone Sensors

Navigation and positioning systems dependent on both the operating environment and the behaviour of the host vehicle or user. The environment determines the type and quality of radio signals available for positioning and the behaviour can contribute additional information to the navigation solution. In order to operate across different contexts, a context-adaptive navigation solution introduces an element of self-awareness by detecting the operating context and configuring the positioning system accordingly. This paper presents the detection of both environmental and behavioural contexts as a whole, building the foundation of a context-adaptive navigation system. Behavioural contexts are classified using measurements from accelerometers, gyroscopes, magnetometers and the barometer by supervised machine learning algorithms, yielding an overall 95% classification accuracy. A connectivity dependent filter is then implemented to improve the behavioural detection results. Environmental contexts are detected from GNSS measurements. They are classified into indoor, intermediate and outdoor categories using a probabilistic support vector machine (SVM), followed by a hidden Markov model (HMM) used for time-domain filtering. As there will never be completely reliable context detection, the paper also shows how environment and behaviour association can contribute to reducing the chances of the context determination algorithms selecting an incorrect context. Finally, the proposed contextdetermination algorithms are tested in a series of multi-context scenarios

Haemophilus influenzae type b serology in childhood leukaemia: A case–control study

Antibody to Haemophilus influenzae type b (Hib) polysaccharide (PRP) was measured in 42 children with acute lymphoblastic leukaemia (ALL) and 42 non-leukaemic hospital controls. Modelling anti-PRP concentrations as a function of age revealed that the slopes of the trend lines differed significantly between cases and controls (P = 0.05); anti-PRP concentrations were lower among younger cases, and higher among older cases, than among controls of the same ages. © 2001 Cancer Research Campaign http://www.bjcancer.co

Cohomological finiteness conditions for a class of metabelian groups

We consider a class of metabelian groups first studied by Baumslag and Stammbach and we show that these groups are consistent with the Bieri-Groves conjecture which relates cohomological finiteness conditions to the Bieri-Neumann-Strebel sigma invariant.Comment: 10 pages Accepted for publication in the Bulletin of the London Mathematical Societ

An original interferometric study of NGC 1068 with VISIR BURST mode images

We present 12.8 microns images of the core of NGC 1068 obtained with the BURST mode of the VLT/VISIR. We trace structures under the diffraction limit of one UT and we investigate the link between dust in the vicinity of the central engine of NGC 1068, recently resolved by interferometry with MIDI, and more extended structures. This step is mandatory for a multi-scale understanding of the sources of mid-infrared emission in AGNs. A speckle processing of VISIR BURST mode images was performed to extract very low spatial-frequency visibilities, first considering the full field of VISIR BURST mode images and then limiting it to the mask used for the acquisition of MIDI data. Extracted visibilities are reproduced with a multi-component model. We identify two major sources of emission: one compact < 85 mas, associated with the dusty torus, and an elliptical one, (< 140) mas x 1187 mas at P.A.=-4 degrees from N to E. This is consistent with previous deconvolution processes. The combination with MIDI data reveals the close environment of the dusty torus to contribute to about 83 percent of the MIR flux seen by MIDI. This strong contribution has to be considered in modeling long baseline interferometric data. It must be related to the NS elongated component which is thought to originate from individually unresolved dusty clouds and is located inside the ionization cone. Low temperatures of the dusty torus are not challenged, emphasizing the scenarios of clumpy torus.Comment: 10 pages, 7 figures, accepted for publication in A&

Examiner training: A study of examiners making sense of norm-referenced feedback

PURPOSE: Examiner training has an inconsistent impact on subsequent performance. To understand this variation, we explored how examiners think about changing the way they assess. METHOD: We provided comparative data to 17 experienced examiners about their assessments, captured their sense-making processes using a modified think-aloud protocol, and identified patterns by inductive thematic analysis. RESULTS: We observed five sense-making processes: (1) testing personal relevance (2) interpretation (3) attribution (4) considering the need for change, and (5) considering the nature of change. Three observed meta-themes describe the manner of examiners' thinking: Guarded curiosity - where examiners expressed curiosity over how their judgments compared with others', but they also expressed guardedness about the relevance of the comparisons; Dysfunctional assimilation - where examiners' interpretation and attribution exhibited cognitive anchoring, personalization, and affective bias; Moderated conservatism - where examiners expressed openness to change, but also loyalty to their judgment-framing values and aphorisms. CONCLUSIONS: Our examiners engaged in complex processes as they considered changing their assessments. The 'stabilising' mechanisms some used resembled learners assimilating educational feedback. If these are typical examiner responses, they may well explain the variable impact of examiner training, and have significant implications for the pursuit of meaningful and defensible judgment-based assessment

Adult vitamin D deficiency leads to behavioural and brain neurochemical alterations in C57BL/6J and BALB/c mice

Epidemiological evidence suggests that low levels of vitamin D may predispose people to develop depression and cognitive impairment. While rodent studies have demonstrated that prenatal vitamin D deficiency is associated with altered brain development, there is a lack of research examining adult vitamin D (AVD) deficiency. The aim of this study was to examine the impact of AVD deficiency on behaviour and brain function in the mouse. Ten-week old male C57BL/6J and BALB/c mice were fed a control or vitamin D deficient diet for 10 weeks prior to, and during behavioural testing. We assessed a broad range of behavioural domains, excitatory and inhibitory neurotransmission in brain tissue, and, in separate groups of mice, locomotor response to d-amphetamine and MK-801. Overall, AVD deficiency resulted in hyperlocomotion in a novel open field and reduced GAD65/67 levels in brain tissue. AVD-deficient BALB/c mice had altered behaviour on the elevated plus maze, altered responses to heat, sound and shock, and decreased levels of glutamate and glutamine, and increased levels of GABA and glycine. By contrast C57BL/6J mice had a more subtle phenotype with no further behavioural changes but significant elevations in serine, homovanillic acid and 5-hydroxyindoleacetic acid. Although the behavioural phenotype of AVD did not seem to model a specific disorder, the overall reduction in GAD65/67 levels associated with AVD deficiency may be relevant to a number of neuropsychiatric conditions. This is the first study to show an association between AVD deficiency and prominent changes in behaviour and brain neurochemistry in the mouse

Gas fraction and depletion time of massive star forming galaxies at z~3.2: no change in global star formation process out to z>3

The observed evolution of the gas fraction and its associated depletion time in main sequence (MS) galaxies provides insights on how star formation proceeds over cosmic time. We report ALMA detections of the rest-frame ∼300µm continuum observed at 240 GHz for 45 massive (hlog(M⋆(M⊙))i = 10.7), normal star forming (hlog(sSFR(yr−1 ))i = −8.6), i.e. MS, galaxies at z ≈ 3.2 in the COSMOS field. From an empirical calibration between cold neutral, i.e. molecular and atomic, gas mass Mgas and monochromatic (rest-frame) infrared luminosity, the gas mass for this sample is derived. Combined with stellar mass M⋆ and star formation rate (SFR) estimates (from MagPhys fits) we obtain a median gas fraction of µgas = Mgas/M⋆ = 1.65+0.18 −0.19 and a median gas depletion time tdepl.(Gyr) = Mgas/SFR = 0.68+0.07 −0.08; correction for the location on the MS will only slightly change the values. The reported uncertainties are the 1σ error on the median. Our results are fully consistent with the expected flattening of the redshift evolution from the 2-SFM (2 star formation mode) framework that empirically prescribes the evolution assuming a universal, log-linear relation between SFR and gas mass coupled to the redshift evolution of the specific star formation rate (sSFR) of main sequence galaxies. While tdepl. shows only a mild dependence on location within the MS, a clear trend of increasing µgas across the MS is observed (as known from previous studies). Further we comment on trends within the MS and (in)consistencies with other studies

A cortical potential reflecting cardiac function

Emotional trauma and psychological stress can precipitate cardiac arrhythmia and sudden death through arrhythmogenic effects of efferent sympathetic drive. Patients with preexisting heart disease are particularly at risk. Moreover, generation of proarrhythmic activity patterns within cerebral autonomic centers may be amplified by afferent feedback from a dysfunctional myocardium. An electrocortical potential reflecting afferent cardiac information has been described, reflecting individual differences in interoceptive sensitivity (awareness of one's own heartbeats). To inform our understanding of mechanisms underlying arrhythmogenesis, we extended this approach, identifying electrocortical potentials corresponding to the cortical expression of afferent information about the integrity of myocardial function during stress. We measured changes in cardiac response simultaneously with electroencephalography in patients with established ventricular dysfunction. Experimentally induced mental stress enhanced cardiovascular indices of sympathetic activity (systolic blood pressure, heart rate, ventricular ejection fraction, and skin conductance) across all patients. However, the functional response of the myocardium varied; some patients increased, whereas others decreased, cardiac output during stress. Across patients, heartbeat-evoked potential amplitude at left temporal and lateral frontal electrode locations correlated with stress-induced changes in cardiac output, consistent with an afferent cortical representation of myocardial function during stress. Moreover, the amplitude of the heartbeat-evoked potential in the left temporal region reflected the proarrhythmic status of the heart (inhomogeneity of left ventricular repolarization). These observations delineate a cortical representation of cardiac function predictive of proarrhythmic abnormalities in cardiac repolarization. Our findings highlight the dynamic interaction of heart and brain in stress-induced cardiovascular morbidity

Frequent range visits further from the shed relate positively to free-range broiler chicken welfare

Little is known about the implications of accessing an outdoor range for broiler chicken welfare, particularly in relation to the distance ranged from the shed. Therefore, we monitored individual ranging behaviour of commercial free-range broiler chickens and identified relationships with welfare indicators. The individual ranging behaviour of 305 mixed-sex Ross 308 broiler chickens was tracked on a commercial farm from the second day of range access to slaughter age (from 16 to 42 days of age) by radio frequency identification (RFID) technology. The radio frequency identification antennas were placed at pop-holes and on the range at 2.7 and 11.2 m from the home shed to determine the total number of range visits and the distance ranged from the shed. Chickens were categorised into close-ranging (CR) or distant-ranging (DR) categories based on the frequency of visits less than or greater than 2.7 m from the home shed, respectively. Half of the tracked chickens (n=153) were weighed at 7 days of age, and from 14 days of age their body weight, foot pad dermatitis (FPD), hock burn (HB) and gait scores were assessed weekly. The remaining tracked chickens (n=152) were assessed for fear and stress responses before (12 days of age) and after range access was provided (45 days of age) by quantifying their plasma corticosterone response to capture and 12 min confinement in a transport crate followed by behavioural fear responses to a tonic immobility (TI) test. Distant-ranging chickens could be predicted based on lighter BW at 7 and 14 days of age (P=0.05), that is before range access was first provided. After range access was provided, DR chickens weighed less every week (P=0.001), had better gait scores (P=0.01) and reduced corticosterone response to handling and confinement (P