A radio transient with unusually slow periodic emission.

The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has, so far, been quiet beyond the Galactic pulsar population and the long-term scintillation of active galactic nuclei. The low-frequency band, however, is sensitive to exotic coherent and polarized radio-emission processes, such as electron-cyclotron maser emission from flaring M dwarfs1, stellar magnetospheric plasma interactions with exoplanets2 and a population of steep-spectrum pulsars3, making Galactic-plane searches a prospect for blind-transient discovery. Here we report an analysis of archival low-frequency radio data that reveals a periodic, low-frequency radio transient. We find that the source pulses every 18.18 min, an unusual periodicity that has, to our knowledge, not been observed previously. The emission is highly linearly polarized, bright, persists for 30-60 s on each occurrence and is visible across a broad frequency range. At times, the pulses comprise short-duration (<0.5 s) bursts; at others, a smoother profile is observed. These profiles evolve on timescales of hours. By measuring the dispersion of the radio pulses with respect to frequency, we have localized the source to within our own Galaxy and suggest that it could be an ultra-long-period magnetar.

GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) I: Survey Description and Initial Data Release.

We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72-231MHz and Declinations south of +30° have been performed with the Murchison Widefield Array "extended" Phase I I configuration over 2018-2020 and will be processed to form data products including continuum and polarisation images and mosaics, multi-frequency catalogues, transient search data, and ionospheric measurements. From a pilot field described in this work, we publish an initial data release covering 1,447 deg2 over 4 h≤ RA≤ 13 h, -32.7° ≤ Dec ≤ -20.7°. We process twenty frequency bands sampling 72-231 MHz, with a resolution of 2'-45″, and produce a wideband source-finding image across 170-231MHz with a root-mean-square noise of 1.27 ± 0.15 mJy beam-1. Source-finding yields 79,124 components, of which 71,320 are fitted spectrally. The catalogue has a completeness of 98% at ~ 50 mJy, and a reliability of 98.2% at 5σ rising to 99.7% at 7σ. A catalogue is available from Vizier; images are made available on the GLEAM-X VO server and SkyView. This is the first in a series of data releases from the GLEAM-X survey.

Children with autism spectrum disorder (ASD) attend typically to faces and objects presented within their picture communication systems.

BACKGROUND: Children with autism spectrum disorder (ASD) may require interventions for communication difficulties. One type of intervention is picture communication symbols which are proposed to improve comprehension of linguistic input for children with ASD. However, atypical attention to faces and objects is widely reported across the autism spectrum for several types of stimuli. METHOD: In this study we used eye-tracking methodology to explore fixation duration and time taken to fixate on the object and face areas within picture communication symbols. Twenty-one children with ASD were compared with typically developing matched groups. RESULTS: Children with ASD were shown to have similar fixation patterns on face and object areas compared with typically developing matched groups. CONCLUSIONS: It is proposed that children with ASD attend to the images in a manner that does not differentiate them from typically developing individuals. Therefore children with and without autism have the same opportunity to encode the available information. We discuss what this may imply for interventions using picture symbols.

Registered Replication Report: Schooler and Engstler-Schooler (1990).

Trying to remember something now typically improves your ability to remember it later. However, after watching a video of a simulated bank robbery, participants who verbally described the robber were 25% worse at identifying the robber in a lineup than were participants who instead listed U.S. states and capitals-this has been termed the "verbal overshadowing" effect (Schooler & Engstler-Schooler, 1990). More recent studies suggested that this effect might be substantially smaller than first reported. Given uncertainty about the effect size, the influence of this finding in the memory literature, and its practical importance for police procedures, we conducted two collections of preregistered direct replications (RRR1 and RRR2) that differed only in the order of the description task and a filler task. In RRR1, when the description task immediately followed the robbery, participants who provided a description were 4% less likely to select the robber than were those in the control condition. In RRR2, when the description was delayed by 20 min, they were 16% less likely to select the robber. These findings reveal a robust verbal overshadowing effect that is strongly influenced by the relative timing of the tasks. The discussion considers further implications of these replications for our understanding of verbal overshadowing.

Groundwater Ecosystems Vary with Land Use across a Mixed Agricultural Landscape.

Changes in surface land use may threaten groundwater quality and ecosystem integrity, particularly in shallow aquifers where links between groundwater and surface activities are most intimate. In this study we examine the response of groundwater ecosystem to agricultural land uses in the shallow alluvial aquifer of the Gwydir River valley, New South Wales, Australia. We compared groundwater quality and microbial and stygofauna assemblages among sites under irrigated cropping, non-irrigated cropping and grazing land uses. Stygofauna abundance and richness was greatest at irrigated sites, with the composition of the assemblage suggestive of disturbance. Microbial assemblages and water quality also varied with land use. Our study demonstrates significant differences in the composition of groundwater ecosystems in areas with different surface land use, and highlights the utility of groundwater biota for biomonitoring, particularly in agricultural landscapes.

Differences in eye-movement patterns between anorexic and control observers when judging body size and attractiveness.

Attentional biases may influence the eye-movements made when judging bodies and so alter the visual information sampled when making a judgment. This may lead to an overestimation of body size. We measured the eye-movements made by 16 anorexic observers and 16 age-matched controls when judging body size and attractiveness. We combined behavioural data with a novel eye-movement analysis technique that allowed us to apply spatial statistical techniques to make fine spatial discriminations in the pattern of eye-movements between our observer groups. Our behavioural results show that anorexic observers overestimate body size relative to controls and find bodies with lower body mass indexes more attractive. For both judgments, the controls' fixations centre on the stomach, but the anorexic observers show a much wider fixation pattern extending to encompass additional features such as the prominence of the hip and collar bones. This additional visual information may serve to alter their behavioural judgments towards an overestimation of body size and shift their ideal body size towards a significantly lower value.

Looking at movies and cartoons: eye-tracking evidence from Williams syndrome and autism.

BACKGROUND: Autism and Williams syndrome (WS) are neuro-developmental disorders associated with distinct social phenotypes. While individuals with autism show a lack of interest in socially important cues, individuals with WS often show increased interest in socially relevant information. METHODS: The current eye-tracking study explores how individuals with WS and autism preferentially attend to social scenes and movie extracts containing human actors and cartoon characters. The proportion of gaze time spent fixating on faces, bodies and the scene background was investigated. RESULTS: While individuals with autism preferentially attended to characters' faces for less time than was typical, individuals with WS attended to the same regions for longer than typical. For individuals with autism atypical gaze behaviours extended across human actor and cartoon images or movies but for WS atypicalities were restricted to human actors. CONCLUSIONS: The reported gaze behaviours provide experimental evidence of the divergent social interests associated with autism and WS.

Segregation by onset asynchrony.

We describe a simple psychophysical paradigm for studying figure-ground segregation by onset asynchrony. Two pseudorandom arrays of Gabor patches are displayed, to left and right of fixation. Within one array, a subset of elements form a figure, such as a randomly curving path, that can only be reliably detected when their onset is not synchronized with that of the background elements. Several findings are reported. First, for most participants, segregation required an onset asynchrony of 20-40 ms. Second, detection was no better when the figure was presented first, and thus by itself, than when the background elements were presented first, even though in the latter case the figure could not be detected in either of the two successive displays alone. Third, asynchrony segregated subsets of randomly oriented elements equally well. Fourth, asynchronous onsets aligned with the path could be discriminated from those lying on the path but not aligned with it. Fifth, both transient and sustained neural activity contribute to detection. We argue that these findings are compatible with neural signaling by synchronized rate codes. Finally, schizophrenic disorganization is associated with reduced sensitivity. Thus, in addition to bearing upon basic theoretical issues, this paradigm may have clinical utility.

An evaluation of U.S. systems for facial composite production.

Witness and victims of serious crime are normally requested to construct a facial composite of a suspect's face. While modern systems for constructing composites have been evaluated extensively in the U.K., this is not the case in the U.S. In the current work, two popular computerized systems in the US, FACES and Identikit 2000, were evaluated against a 'reference' system, PRO-fit, where performance is established. In experiment 1, witnesses constructed a composite with both PRO-fit and FACES using a realistic procedure. The resulting composites were very poorly named, but the PRO-fit emerged best in 'cued' naming and two supplementary measures: composite sorting; and likeness ratings. In experiment 2, PRO-fit was compared with Identikit 2000, a sketch-like feature system. Spontaneous naming was again very poor, but both cued naming and sorting suggested that the systems were similar. The results support previous findings that modern systems do not produce identifiable composites.

Pop-out from abrupt visual onsets.

We report a novel psychophysical paradigm that distinguishes the information present in abrupt stimulus onset from that in the following display. The task is to pick the one odd item from a set added to a pre-existing background of similar items. When all new items are added simultaneously, observers are impaired even at distinguishing one red item amongst several green ones. An asynchrony of about 40 ms between target and distracter items restores performance, with evidence that it is cortical, rather than stimulus timing difference that is significant. The results are consistent with a role for neural synchrony in dynamic grouping.

Human and automatic face recognition: a comparison across image formats.

Human subjects perform poorly at matching different images of unfamiliar faces. When images are taken by different capture devices (cameras), matching is difficult for human perceivers and also for automatic systems. We test an automatic face recognition system based on principal components analysis (PCA) and compare its performance with that of human subjects tested on the same set of images. A number of variants of the PCA system are compared, using different matching metrics and different numbers of components. PCA performance critically depends on the choice of distance metric, with a Mahalanobis metric consistently outperforming a Euclidean metric. Under optimal conditions, the automatic PCA system exceeds human performance on the same images. We hypothesise that unfamiliar face recognition may be mediated by processes corresponding to rather simple functions of the inputs.

The crystal structure of human protein farnesyltransferase reveals the basis for inhibition by CaaX tetrapeptides and their mimetics.

Protein farnesyltransferase (FTase) catalyzes the attachment of a farnesyl lipid group to the cysteine residue located in the C-terminal tetrapeptide of many essential signal transduction proteins, including members of the Ras superfamily. Farnesylation is essential both for normal functioning of these proteins, and for the transforming activity of oncogenic mutants. Consequently FTase is an important target for anti-cancer therapeutics. Several FTase inhibitors are currently undergoing clinical trials for cancer treatment. Here, we present the crystal structure of human FTase, as well as ternary complexes with the TKCVFM hexapeptide substrate, CVFM non-substrate tetrapeptide, and L-739,750 peptidomimetic with either farnesyl diphosphate (FPP), or a nonreactive analogue. These structures reveal the structural mechanism of FTase inhibition. Some CaaX tetrapeptide inhibitors are not farnesylated, and are more effective inhibitors than farnesylated CaaX tetrapeptides. CVFM and L-739,750 are not farnesylated, because these inhibitors bind in a conformation that is distinct from the TKCVFM hexapeptide substrate. This non-substrate binding mode is stabilized by an ion pair between the peptide N terminus and the alpha-phosphate of the FPP substrate. Conformational mapping calculations reveal the basis for the sequence specificity in the third position of the CaaX motif that determines whether a tetrapeptide is a substrate or non-substrate. The presence of beta-branched amino acids in this position prevents formation of the non-substrate conformation; all other aliphatic amino acids in this position are predicted to form the non-substrate conformation, provided their N terminus is available to bind to the FPP alpha-phosphate. These results may facilitate further development of FTase inhibitors.

Evolving faces from principal components.

A system that uses an underlying genetic algorithm to evolve faces in response to user selection is described. The descriptions of faces used by the system are derived from a statistical analysis of a set of faces. The faces used for generation are transformed to an average shape by defining locations around each face and morphing. The shape-free images and shape vectors are then separately subjected to principal components analysis. Novel faces are generated by recombining the image components (eigenfaces) and then morphing their shape according to the principal components of the shape vectors (eigenshapes). The prototype system indicates that such a statistical analysis of a set of faces can produce plausible, randomly generated photographic images.

Effects of dizocilpine (MK 801) on noradrenaline, serotonin and dopamine release and uptake.

In the present study, we examined the actions of the NMDA antagonist dizocilpine (MK801) on electrically evoked release and uptake of noradrenaline (NA) in the locus coeruleus (LC), serotonin (5-HT) in the dorsal raphe nucleus (DRN) and dopamine (DA) in the nucleus accumbens (NAc), measured by fast cyclic voltammetry (FCV) in rat brain slices. Dizocilpine (10 microM) significantly increased NA (to 248 +/- 15%) and 5-HT release (to 184 +/- 29%) and slowed monoamine uptake in the LC (t1/2 = 853 +/- 129%) and the DRN (t1/2 = 387 +/- 70%), respectively. However, dizocilpine had no effect on DA release or uptake in NAc. Actions on monoamines are thus likely and should be considered in the interpretation of data regarding dizocilpine.

Stereospecific effects of ketamine on dopamine efflux and uptake in the rat nucleus accumbens.

In addition to being a general anaesthetic, ketamine is a recognized drug of abuse. Many, if not all, drugs of abuse have been shown to increase dopamine efflux in the nucleus accumbens (NAc). As ketamine is optically active, we examined if its actions on dopamine efflux in the NAc were stereoselective. Slices of rat NAc were superfused with artificial CSF at 32 degrees C. Dopamine efflux was evoked by electrical stimulation (1 or 20 pulses, 100 Hz) and measured using fast cyclic voltammetry. (+/-)-Ketamine 100 mumol litre-1 increased dopamine efflux (to mean 174 (SEM 17)% of control, P < 0.05) and slowed dopamine uptake half-time (T1/2) to 164 (17)% of control, as did (+)-ketamine 100 mumol litre-1 (efflux 236 (16)% (P < 0.001); uptake T1/2 177 (25)% (P < 0.05)). The (-)-isomer was inactive. The effect of (+)-ketamine on dopamine efflux did not correlate with its action on dopamine uptake. (+)-Ketamine increased dopamine efflux on single pulse stimulation but to a lesser extent than on 20 pulse trains (P < 0.05). (+)-Ketamine was unable to block the inhibitory effect of quinpirole on single pulse dopamine efflux. Neither MK 801 10 mumol litre-1 nor metoclopramide 1 mumol litre-1 had any effect on dopamine release after short train stimuli (20 pulses, 100 Hz). We conclude that the (+)-isomer is the active form of ketamine and increases NAc dopamine efflux not by block of dopamine uptake; autoreceptors or NMDA receptors, but by mobilization of the dopamine storage pool to releasable sites.

A comparison of two computer-based face identification systems with human perceptions of faces.

The performance of two different computer systems for representing faces was compared with human ratings of similarity and distinctiveness, and human memory performance, on a specific set of face images. The systems compared were a graph-matching system (Lades M, Vorbrüggen JC, Buhmann J, Lage J, von der Malsburg C, Würtz RP, Konen W. IEEE., Trans Comput 1993;42:300-311.) and coding based on principal components analysis (PCA) of image pixels (Turk M, Pentland A. J Cognitive Neurosci 1991;3:71-86.). Replicating other work, the PCA-based system produced very much better performance at recognising faces, and higher correlations with human performance with the same images, when the images were initially standardised using a morphing procedure and separate analysis of 'shape' and 'shape-free' components then combined. Both the graph-matching and (shape + shape-free) PCA systems were equally able to recognise faces shown with changed expressions, both provided reasonable correlations with human ratings and memory data, and there were also correlations between the facial similarities recorded by each of the computer models. However, comparisons with human similarity ratings of faces with and without the hair visible, and prediction of memory performance with and without alteration in face expressions, suggested that the graph-matching system was better at capturing aspects of the appearance of the face, while the PCA-based system seemed better at capturing aspects of the appearance of specific images of faces.

Face processing: human perception and principal components analysis.

Principal components analysis (PCA) of face images is here related to subjects' performance on the same images. In two experiments subjects were shown a set of faces and asked to rate them for distinctiveness. They were subsequently shown a superset of faces and asked to identify those that had appeared originally. Replicating previous work, we found that hits and false positives (FPs) did not correlate: Those faces easy to identify as being "seen" were unrelated to those faces easy to reject as being "unseen." PCA was performed on three data sets: (1) face images with eye position standardized, (2) face images morphed to a standard template to remove shape information, and (3) the shape information from faces only. Analyses based on PCA of shape-free faces gave high predictions of FPs, whereas shape information itself contributed only to hits. Furthermore, whereas FPs were generally predictable from components early in the PCA, hits appeared to be accounted for by later components. We conclude that shape and "texture" (the image-based information remaining after morphing) may be used separately by the human face processing system, and that PCA of images offers a useful tool for understanding this system.

A statistical analysis of natural images matches psychophysically derived orientation tuning curves.

A neural net method is used to extract principal components from real-world images. The initial components are a Gaussian followed by horizontal and vertical operators, starting with the first derivative and moving to successively higher orders. Two of the components are 'bar-detectors'. Their measured orientation selectivity is similar to that suggested by Foster & Ward (Proc. R. Soc. Lond. B 243, 75 (1991] to account for brief-exposure psychophysical data. In tests with noise images, the ratio of sensitivity between the two components is controlled by the degree of anisotropy in the image.

Physiologic and biochemical effects of ritodrine therapy on the mother and perinate.

The materno-fetal and neonatal effects of ritodrine were studied in 37 women treated for premature labor with intravenous (i.v.) ritodrine. Marked cardiovascular, respiratory, and biochemical side effects of therapy were seen in the mothers and tachycardia was noted in the fetuses. The neonates of 18 women in whom ritodrine successfully postponed delivery were delivered with good Apgar scores and their admission vital signs and nursery courses were benign. Ritodrine failed to delay delivery more than a week in 19 mothers. There were no differences between their newborns and 20 control neonates in admission vital signs, blood gases, blood chemistries, complete blood counts, platelet counts, peak bilirubin, or duration of oxygen therapy. This study revealed no deleterious effects on neonates delivered after maternal ritodrine therapy despite significant maternal and fetal effects.