460 research outputs found
Trace-strength and source-monitoring accounts of accuracy and metacognitive resolution in the misinformation paradigm
No full textTwo experiments are reported that investigate the impact of misinformation on memory accuracy and metacognitive resolution. In Experiment 1, participants viewed a series of photographs depicting a crime scene, were exposed to misinformation that contradicted details in the slides, and later took a recognition memory test. For each answer, participants were required to indicate whether they were willing to testify (report) their answer to the Court and to rate confidence. Misinformation impaired memory accuracy but it had no effect on resolution, regardless of whether resolution was indexed with confidence-rating measures (gamma correlation and mean confidence) or a report-option measure (type-2 discrimination: d’). In Experiment 2, a similar accuracy-confidence dissociation was found, and the misinformation effect occurred mostly with fine-grained responses, suggesting that responding was based on recollected details. We argue that the results support source-monitoring accounts of accuracy and resolution rather than accounts based on trace strength
Global subjective memorability and the strength-based mirror effect
No full textBetween-list manipulations of memory strength through repetition commonly generate a mirror effect, with more hits, and fewer false alarms for strengthened items. However, this pattern is rarely seen with within-list manipulations of strength. Three experiments investigated the conditions under which a within-list mirror effect of strength (items presented once or thrice) is observed. In Experiments 1 and 2, we indirectly manipulated the overall subjective memorability of the studied lists by varying the proportion of non-words. A within-list mirror effect was observed only in Experiment 2, where a higher proportion of non-words was presented in the study list. In Experiment 3, the presentation duration for each item (0.5 s versus 3 s) was manipulated between groups with the purpose of affecting subjective memorability: A within-list mirror effect was observed only for the short-presentation durations. Thus, across three experiments, we found the within-list mirror effect only under conditions of poor overall subjective memorability. We propose that when the overall subjective memorability is low, people switch their response strategy on an item-by-item basis, and that this generates the observed mirror effect. <br/
National Air Traffic Services
No full textNational Air Traffic Services (NATS) are concerned with ensuring low probabilities of errors in determining aircraft positions. In general, error probabilities depend on the tails of some probability distributions for which there has been no theoretical model. Analysis of radar performance is regularly undertaken by NATS to ensure radar performance is within safety limits, with the maximum range being dependent on the declared separation between aircraft. NATS brought two questions to the Study Group, involving the horizontal (azimuthal) errors in radar data and the vertical errors in altimetry system data. In both cases, NATS asked the Study Group to analyse the data and assess whether the probability distributions that are currently used are good models for the errors
Structures and ammonia synthesis activity of hexagonal ruthenium iron nitride phases
No full textA series of ruthenium iron nitride phases with Ru:Fe ratios of ca. 1:3 were synthesised by ammonolysis. When the ammonolysis temperature was above 500 °C, the obtained RuxFe3Ny materials had a ε-Fe3N (P6322) structure, while two similar phases were present when the ammonolysis was lower than 500 °C. Powder neutron diffraction identified one phase as relating to the ε-Fe3N structure, whilst the other had a disordered NiAs-type (P63/mmc) structure. These ternary metal nitrides show ammonia synthesis activity at low temperature (200-300 °C) and ambient pressure which can be related to the loss of lattice nitrogen. Steady state catalytic performance at 400 °C is associated with ruthenium-iron alloy. Additionally, density functional theory calculations were performed using an approximate model for the disordered hexagonal phase, revealing that this phase is more stable than a cubic anti-perovskite phase which has been previously investigated computationally, and corroborating the experimental findings of the present work
[Rezension von:] Higham, robert; Barker Philip; Higham, Robert: Hen Domen : a timber castle in the English-Welsh border ; a final report. - University of Exeter Press, 2000
No full textDiary of a Disaster: British Aid to Greece, 1940-1941
No full textOn October 28, 1940, the Italian army under Benito Mussolini invaded Greece. The British had insisted on guaranteeing Greek and Turkish neutrality, despite the fact that Greece was never more than a limited campaign in an unlimited war as far as they were concerned. The British, however, were never quite sure that Greece was not their last foothold in Europe, and they harbored dreams of holding on to this last bastion of civilization and of protecting it with a diplomatic and military alliance—a Balkan bloc. These dreams bore little relation to military and economic realities, and so the stage was set for tragedy.
In Diary of a Disaster, Robin Higham details the unfolding events from the invasion, though the Italian defeat and the subsequent German invasion, until the British evacuation at the end of April 1941. The Greek army, while tough, was small and based largely upon reserves. They were also largely equipped with obsolete French, Polish, and Czech arms for which there was now no other source than captured Italian materiel. Transportation was also lacking as Greece lacked all-weather roads over much of the country, had no all-weather airport, and only one rail line connecting Athens with Salonika and Florina in the north.
Added to the woes of the Greek military, the British commander-in-chief for the Middle East, Sir Archibald Wavell, faced huge logistical challenges as well. Based in Cairo, he was responsible for a huge theatre of operation, from hostile Vichy French forces in Syria to the Boers in South Africa nearly six thousand miles away. His air force was comprised of only a handful of modern aircraft with biplanes and outdated, early monoplanes making up the bulk of his force. Radar was also unavailable to him. His navy was woefully short on destroyers and often incommunicado while at sea. While Wavell had roughly 500,000 men under his command, he was severely limited in how he could use them. The South Africans could only be deployed in East Africa and the Austrians and New Zealanders could not be employed without the consent of their home governments. In short, Churchill had instructed Wavell to offer support that he did not really have and could not afford to give to the Greeks.
Higham walks readers through these events as they unfold like a modern Greek tragedy. Using the format of a diary, he recounts day-by-day the British efforts though the failure of Operation Lustre, which no one outside of London thought had any chance of stemming the Nazi tide in Greece.
Robin Higham, professor of history emeritus at Kansas State University, is the author and editor of many books, including Why Air Forces Fail: The Anatomy of Defeat and The Influence of Air Power Upon History: Statesmanship, Diplomacy, and Foreign Policy since 1903.https://uknowledge.uky.edu/upk_military_history/1008/thumbnail.jp
Portfolio Theory
No full text(This is a condensed version of http://eprints.soton.ac.uk/id/eprint/369944
Optimal solution of the nearest correlation matrix problem by minimization of the maximum norm
No full textThe nearest correlation matrix problem is to find a valid (positive semidefinite) correlation matrix, R(m,m), that is nearest to a given invalid (negative semidefinite) or pseudo-correlation matrix, Q(m,m); m larger than 2. In the literature on this problem, 'nearest' is invariably defined in the sense of the least Frobenius norm. Research works of Rebonato and Jaeckel (1999), Higham (2002), Anjos et al. (2003), Grubisic and Pietersz (2004), Pietersz, and Groenen (2004), etc. use Frobenius norm explicitly or implicitly. However, it is not necessary to define 'nearest' in this conventional sense. The thrust of this paper is to define 'nearest' in the sense of the least maximum norm (LMN) of the deviation matrix (R-Q), and to obtain R nearest to Q. The LMN provides the overall minimum range of deviation of the elements of R from those of Q. We also append a computer program (source codes in FORTRAN) to find the LMN R from a given Q. Presently we use the random walk search method for optimization. However, we suggest that more efficient methods based on the Genetic algorithms may replace the random walk algorithm of optimization.Nearest correlation matrix problem; Frobenius norm; maximum norm; LMN correlation matrix; positive semidefinite; negative semidefinite; positive definite; random walk algorithm; Genetic algorithm; computer program; source codes; FORTRAN; simulation
Sensor technologies for measuring coastal hydrodynamics and morphological change
No full textThis research has focused on development of cost-effective sea-level and wave measuring technologies for implementation alongside X-band radar monitoring programmes. These data are important for two reasons: firstly, sea-level data are required for deriving the morphological maps from the X-band radar images; these maps can inform coastal managers of critical lowering of beach levels that might compromise sea-defences, or high beach levels that might exacerbate run-up and overtopping hazard, and secondly, sea-level and wave data can be used to understand the role of tides, storm surges and waves in shaping beaches and tidal flats. While there are numerous commercial devices capable of measuring sea level and waves, many are not suitable for the intertidal zone and those that can are generally too expensive to deploy for long durations or to implement at scale as part of a near-real time system. This research is based upon taking ideas and developed products from other sectors and transferring these advances to create low-cost devices. This research has successfully produced and evaluated two devices with field experiments; a low-cost GNSS buoy capable of deployment from a small boat or from the beach at low water, and an Internet of Things (IoT) tide gauge capable of scaling up to provide a network of near/real time devices. A comparison of tidal heights between the GNSS buoy and a reference tide gauge at Holyhead harbour (located 1.5 km away) produced a mean difference of -1.1cm and a RMSE of 1.4 cm, indicating its suitability for sea level measurement. Likewise, a comparison between the IoT tide gauge and a reference tide at Gladstone Lock, Liverpool (located 2.6 km upstream), produced a mean difference of 0.2 cm and a RMSE 3.5 cm, showing that acceptable data can also be obtained using low-cost pressure sensors.
The research also sets out to develop a method of using temporal X-band derived Digital Elevation Models (DEMs) (which contain spatial elevation errors), alongside more accurate annual LiDAR data, to characterise morphological changes of a tide flat. Analysis of DEMs over a three-year period shows the importance of regular monitoring of beach morphology over annual surveys. The results indicate the presence and shoreward movement of small sand ridges situated between the mean-sea-level and mean-low-water-springs. There are also regular cycles of erosion and deposition and these appear to be related to both the tidal height and stormy periods. The two-week X-band radar composite maps of the intertidal zone are not at a resolution capable of analysing the effect of individual storm events, or to separate parts of the tidal cycle e.g., neap tides over seven days. Future surveys with the X-band radar would benefit from the instrumentation developed as part of this research. This would improve the data quality, allow for increased temporal output i.e., more maps, and thus provide the additional data necessary to solve some of the issues encountered with analysis of the historical data
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