The Atacama Cosmology Telescope: A Catalog of >4000 Sunyaev–Zel’dovich Galaxy Clusters

We present a catalog of 4195 optically confirmed Sunyaev–Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio >4 in 13,211 deg2 of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ signal versus mass-scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M500c > 3.8 × 1014 M⊙, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio >5 in maps filtered at an angular scale of 2farcm4. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ signal mass-scaling relation, such as the Dark Energy Survey (4566 deg2), the Hyper Suprime-Cam Subaru Strategic Program (469 deg2), and the Kilo Degree Survey (825 deg2). We highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr

Aberrant driving behaviour: errors and violations

The present study was a replication of the research of Reason et al. (1990). Its aim was to confirm the distinction between driving errors and violations in a Western Australian driving population. Sixty-one male drivers and 74 female drivers completed a questionnaire containing items on driver demographics, driving penalties incurred, driving convictions and accident history and driver behavioural aberrations drawn from the Driver Behaviour Questionnaire (DBQ). In agreement with Reason et al. factor analysis revealed three factors; in the present study these were general errors, dangerous errors, and dangerous violations. Young drivers committed more dangerous errors and dangerous violations than older drivers. Females reported more dangerous errors than males. Males reported more dangerous violations than females. Drivers who reported a high level of road exposure and those who reported having been convicted for speeding reported more dangerous violations. Differences in the results of the two studies can largely by accounted for by differences in the representation of age and gender in the two populations studied

Scopolamine and the control of attention in humans

Recent work with humans and animals has suggested that the cholinergic system plays an important role in the active control of attention. This study was designed to investigate the effects of scopolamine upon subjects' ability to utilize knowledge of the spatial probability bias in a display in the detection of briefly-presented target letters. Results showed a significant interaction between drug condition (scopolamine 0.9 mg versus Placebo) and target location probability, which indicated that detection of targets in high probability locations decreased under the drug, while detection in low probability locations increased. These results offer support for the notion that scopolamine reduces the efficiency of information encoding because it impairs the optimal utilization of attentional resources

The effects of caffeine and expectancy on attention and memory

The present study contrasted caffeine's effects on individuals who expect caffeine to stimulate them and those who do not. Secondly, whether a message that caffeine rather than placebo was administered would also affect these two groups of subjects differently was investigated. The study was conducted single-blind in a 2 × 2 × 2 mixed design. The between subjects factor was whether they expected caffeine to stimulate them (E+) or not (E-) according to their self reports obtained before the experiment began. The within subjects factors were message (told caffeine vs told placebo) and beverage type (given caffeine vs placebo). Sixteen subjects in each group (n = 32) performed on signal detection, memory scanning and delayed free recall tasks following ingestion of either caffeinated or decaffeinated coffee on two sessions each, a total of four experimental sessions. On each session, subjects were given a message regarding their drink (told caffeine vs told placebo). However, on two sessions there was a mismatch between the message and drink given. For signal detection, performance under caffeine was better than placebo in the E+ but not the E- group. However, subjects in the E+ group did not benefit more than the E- group in either message condition. On memory scanning, detections and false alarms did not differ for either beverage, nor was there a differential finding in the E+ and E- groups. However, reaction time under caffeine condition was shorter. No effects of message were found. Caffeine and message also did not have any effect on performance on the delayed free recall task. The hypothesis that caffeine and message would affect E+ and E- subjects differentially was partly supported

Measuring reaction time and controlling the video display in experiments on an IBM PC

The problems of using the IBM PC XT/AT or their clones in experiments are recognized because of the slow, inadequate and awkward timing procedures of these microcomputers. Some specific solutions to these problems are described, including a compiled BASIC approach using real time procedures accurate to 1 millisecond (although resolution to 1 microsecond can be achieved) and synchronization of the video display with the program

Patterns of stimulant drug use on Western Australian heavy transport routes

In July 1997, 236 truck drivers were interviewed at three truck stops in Western Australia. The interviews collected information on driver fatigue and stimulant drug taking as a fatigue countermeasure. Drivers have become more aware of fatigue as a problem within the industry over the past two years, however, 27% of drivers reported using stimulant drugs to combat driver fatigue. Interstate drivers use more prescription and illicit stimulant drugs to keep awake while intrastate drivers use more over the counter stimulants. Over the counter stimulants are not perceived as drugs by intrastate drivers because they are easily and legally obtainable and this is reflected within many of their responses. The most frequent way that drivers obtained stimulant drugs was through a doctor, a chemist or illegal prescription. Anecdotal evidence from the drivers suggests that increasing pressure from the public and the media to eliminate illegally prescribed stimulant use by drivers has made them harder to obtain. Therefore, without fatigue issues within the industry being addressed, an increase in street purchases of illicit stimulants may occur. Prohibition of stimulant drug use without changing industry practices eliminates a fatigue countermeasure and could lead to a serious increase in fatigue-related crashes. The results of this study will help to identify “at risk” groups of drivers who can be targeted for education on fatigue and drug issues

Effects of chlorpromazine on lateralization, cued reaction time, and dichotic listening

In a double-blind cross-over design sixteen subjects took 50 mg of chlorpromazine or placebo in tablet form 2 hours prior to completing a dichotic listening and simple reaction time task with and without warnings. In the simple reaction time task, blocks of 80 stimuli were presented to each ear with and without warning cue under drug and placebo conditions. On the dichotic listening task the expected right ear advantage for reporting digits was obtained. While the drug had no main effect on the number of errors, there were more trials on which an ear advantage was present than in the placebo condition. In the reaction time task there were main effects of drug, warning cue and foreperiod: warnings facilitated reaction; chlorpromazine retarded reaction; and reaction times were most facilitated by warning foreperiods in excess of 1200ms. Several findings were of interest: On uncued trials, with placebo, right ear responses were faster than those for stimuli presented to the left ear. Drug also interacted with foreperiod duration. These results were interpreted in the light of Tucker and Williamson's (1984) review of the role of Pribram and McGuinness's Arousal and Activation sytems in lateralized behavior

The effects of scopolamine upon verbal memory: evidence for an attentional hypothesis

Immediate and delayed free recall and recognition of dichotically presented lists of nouns were assessed in a group of normal female volunteers following oral administration of either a placebo or 0.6 mg scopolamine hydrobromide. Results show that, while there was no drug effect upon total (i.e., attended plus unattended) recall, there was a significant drug by attention interaction, in that recall for attended words was impaired while unattended recall was facilitated. There were no drug effects upon recognition performance. It was concluded that scopolamine acts to modulate selective attention rather than memory consolidation processes, and it is suggested that the cholinergic system may be centrally involved in the control of effortful or intentional processing in memory

Effect or alcohol on a sentence-picture verification task

The Clark and Chase (1972) sentence verification task was given to selected volunteers following either a placebo or a dose of alcohol measured to take blood alcohol up to 005mg/100ml. Results showed the alcohol had severe effects on the verbal strategy when employed, but assisted the spatial strategy in verification. The results are contrasted with the effects of noise in the same task and the importance of the results for qualifying the effects of alcohol discussed

Stress, violations and accidents

Sources of stress among Western Australian car and truck drivers were investigated using an extended version of the Driver Behaviour Inventory (DBI) developed by Gulian et al. The associations between reported stress and drivers' accident or violation records were also examined. The DBI was mailed to two groups each of 500 truck drivers with 'high' or 'low' traffic violation involvements and to two similar groups of car drivers, producing an overall response rate of 38%. Factor analyses related truck drivers' stress more to occupational demands and to 'imperturbability', whereas car drivers' stress was related more to psychological health, age, experience and aggression. Such factors predicted 30-40% of the variance in accident or violation reports