Crashes as Critical Points

We study a rational expectation model of bubbles and crashes. The model has two components : (1) our key assumption is that a crash may be caused by local self-reinforcing imitation between noise traders. If the tendency for noise traders to imitate their nearest neighbors increases up to a certain point called the ``critical'' point, all noise traders may place the same order (sell) at the same time, thus causing a crash. The interplay between the progressive strengthening of imitation and the ubiquity of noise is characterized by the hazard rate, i.e. the probability per unit time that the crash will happen in the next instant if it has not happened yet. (2) Since the crash is not a certain deterministic outcome of the bubble, it remains rational for traders to remain invested provided they are compensated by a higher rate of growth of the bubble for taking the risk of a crash. Our model distinguishes between the end of the bubble and the time of the crash,: the rational expectation constraint has the specific implication that the date of the crash must be random. The theoretical death of the bubble is not the time of the crash because the crash could happen at any time before, even though this is not very likely. The death of the bubble is the most probable time for the crash. There also exists a finite probability of attaining the end of the bubble without crash. Our model has specific predictions about the presence of certain critical log-periodic patterns in pre-crash prices, associated with the deterministic components of the bubble mechanism. We provide empirical evidence showing that these patterns were indeed present before the crashes of 1929, 1962 and 1987 on Wall Street and the 1997 crash on the Hong Kong Stock Exchange. These results are compared with statistical tests on synthetic data.Comment: A total of 40 pages including 9 figures and 6 table

Effect of tranexamic acid in traumatic brain injury: a nested randomised, placebo controlled trial (CRASH-2 Intracranial Bleeding Study).

OBJECTIVE: To assess the effect of tranexamic acid (which reduces bleeding in surgical patients and reduces mortality due to bleeding in trauma patients) on intracranial haemorrhage in patients with traumatic brain injury. METHODS: A nested, randomised, placebo controlled trial. All investigators were masked to treatment allocation. All analyses were by intention to treat. Patients 270 adult trauma patients with, or at risk of, significant extracranial bleeding within 8 hours of injury, who also had traumatic brain injury. INTERVENTIONS: Patients randomly allocated to tranexamic acid (loading dose 1 g over 10 minutes, then infusion of 1 g over 8 hours) or matching placebo. MAIN OUTCOME MEASURES: Intracranial haemorrhage growth (measured by computed tomography) between hospital admission and then 24-48 hours later, with adjustment for Glasgow coma score, age, time from injury to the scans, and initial haemorrhage volume. RESULTS: Of the 133 patients allocated to tranexamic acid and 137 allocated to placebo, 123 (92%) and 126 (92%) respectively provided information on the primary outcome. All patients provided information on clinical outcomes. The mean total haemorrhage growth was 5.9 ml (SD 26.8) and 8.1 mL (SD 29.2) in the tranexamic acid and placebo groups respectively (adjusted difference -3.8 mL (95% confidence interval -11.5 to 3.9)). New focal cerebral ischaemic lesions occurred in 6 (5%) patients in the tranexamic acid group versus 12 (9%) in the placebo group (adjusted odds ratio 0.51 (95% confidence interval 0.18 to 1.44)). There were 14 (11%) deaths in the tranexamic acid group and 24 (18%) in the placebo group (adjusted odds ratio 0.47 (0.21 to 1.04)). CONCLUSIONS: This trial shows that neither moderate benefits nor moderate harmful effects of tranexamic acid in patients with traumatic brain injury can be excluded. However, the analysis provides grounds for further clinical trials evaluating the effect of tranexamic acid in this population. Trial registration ISRCTN86750102

In-depth research into rural road crashes

This report was produced under an agreement between Transport SA and the Road Accident Research Unit formed in the late 1990s. Due to various delays in the publication of this report, Transport SA has since become the Department for Transport, Energy and Infrastructure and the Road Accident Research Unit has become the Centre for Automotive Safety Research. The report describes a series of 236 rural road crashes investigated between 1 March 1998 and 29 February 2000 in South Australia. Investigations began with immediate attendance at the scene of the crash. The information collected for each crash included: photographs of the crash scene and vehicles involved, video record of the crash scene and vehicles in selected cases, examination of the road environment, a site plan of the crash scene and vehicle movements in the crash, examination and measurements of the vehicles involved, interviews with crash participants, interviews with witnesses, interviews with police, information on the official police report, information from Coroner’s reports, and injury data for the injured crash participants. The report provides an overall statistical summary of the sample of crashes investigated, followed by a detailed examination of the road infrastructure issues contributing to the crashes. This is done on the basis of crash type, with separate sections concerned with single vehicle crashes, midblock crashes and crashes at intersections. A section is also provided that examines the role of roadside hazards in the crashes.Baldock MRJ, Kloeden CN and McLean A

The Flash Crash: An Examination of Shareholder Wealth and Market Quality

We investigate stock returns, market quality, and options market activity around the flash crash of May 6, 2010. Abnormal returns are negative on the day of and the day after the flash crash for stocks that had trades that executed during the crash subsequently cancelled by either Nasdaq or NYSE Arca. Consistent with studies that suggest that other sources of liquidity withdrew from the markets during the flash crash, we find that the fraction of trades executed by the NYSE increases during this volatile period. Market quality deteriorates following the flash crash as bid-ask spreads increase and quote depths decrease. Evidence from the options markets indicates that investor uncertainty increased around the time of the crash and remained elevated for several days

CRASH - Corticosteroid Randomisation after Significant Head Injury

A large simple placebo controlled trial, among adults with head injury and impaired consciousness, of the effects of a 48-hour infusion of corticosteroids on death and neurological disability. CRASH was a randomised, controlled, double-blind trial undertaken in 239 hospitals in 49 countries. A total of 10008 adults with head injury and a Glasgow Coma Score (GCS) of 14 or less within 8 hours of injury were randomly allocated 48 hour infusion of corticosteroids (methylprednisolone) or placebo. Primary outcomes were death within 2 weeks of injury or disability at 6 months. Prespecified subgroup analyses were based on injury severity (GCS) at randomisation and on time from injury to randomisation and analysis was by intention to treat. Access to this dataset is available via https://freebird.lshtm.ac.uk/

Aircraft-crash-locating transmitter features design improvements

Crash locater is automatically ejected from aircraft at time of crash and begins transmitting at emergency radio frequencies monitored by all airports and airport control towers. Advantages are smaller size, simpler design and installation, extended transmitting range and life, greater deployment reliability and increased crash resistance

Blackspot analysis of road traffic crashes in Surabaya - Manyar Toll Road, East Java

Traffic crashes are one of the problems that cannot be prevented, especially on toll roads. Knowing the crash element, including crash number, type, factor, and fatality, could lead the investigation to set crash solving and prevention by finding the blackspot point. Surabaya-Manyar toll roads were reported as crash-prone locations, with 149 crashes from 2014-2018. This research concerns the impact on a specific period obtained by PT. Margabumi Matrajaya was ranging from 2014-2018 at Surabaya-Manyar toll road. The objectives aim to analyze the crash element using submitted data from PT. Margabumi Matrajaya to find the blackspot at each line. The collected data were the primary data from field observation and documentation and secondary data, consisting of crash data, road length, time of the crash, what types of vehicles were involved in the crash, and wound victim data. The locations of crash-prone points (Blackspots) on the Surabaya - Manyar Toll road are as follows: The locations of crash-prone points (Blackspots) on the Surabaya Toll road - Manyar line mostly occurred at Km 9 + 925 - 16 + 400 mostly in 2018, on the Romokalisari - Kebomas section, and for Manyar - Surabaya line, occurred at Km 3 + 500 - 0 + 000 mostly in 2016, on the Tandes - Dupak section. Therefore, to decrease the crash number in Surabaya - Manyar toll road, PT. Margabumi Matrajaya should add traffic sign as blackspot area, speed trap, warning sign like slippery road ahead warning, crossroad, and merging traffic