It has been suggested that stock exchanges may be tested for market efficiency by using tests for assessing random number generators. This paper uses such a test to assess the efficiency of small, ...mid and large cap indices on the Johannesburg Stock Exchange, while making adjustments for thin trading which occurs during the sample period. The efficiency of these indices is examined using individual share level data as well as index level data over a stable period and a period containing the 2008 financial crisis. This study finds evidence suggesting that small cap stocks exhibit a high degree of non-randomness in price movements. Some inefficiencies also appear to be present in mid and large cap stocks, however to a much lesser extent, with large cap stocks exhibiting higher levels of efficiency. Many of the stocks investigated appear to exhibit lower levels of efficiency during the crisis period. This may be a result of increased irrationality during periods of uncertainty.
To retrospectively determine the incidence of potentially serious adverse events associated with computed tomographic (CT) colonography performed in patients with symptoms of colorectal cancer.
...Ethical approval and informed consent were waived, since the study was deemed a clinical audit and patients would not be approached. With a national survey in the United Kingdom, all departments offering CT colonography in everyday practice were identified. The lead gastrointestinal radiologist from all responding departments was interviewed, and the frequency of potentially serious adverse events associated with CT colonography performed in patients with symptoms of colorectal cancer, the total number of examinations performed, and technical factors possibly related to perforation were determined. Where a potentially serious adverse event was encountered, it was explored in detail. Responses were collated, and raw frequencies were determined. Fisher exact test was used to determine differences in event rates between groups.
At 50 centers, 17 067 CT colonographic examinations (mean number per center, 359; range, 10-3000) were performed. No deaths were reported. Thirteen patients (one 0.08% of 1313) had had a potentially serious adverse event related to the procedure. There were nine perforations: Four (44%) were asymptomatic and five (56%) were symptomatic, and perforation had an attributable cause, with a symptomatic perforation rate of 0.03% (one in 3413 patients). One patient required laparotomy. An inflated rectal balloon was used to perform 9378 examinations. There was no significant difference between the proportion of perforations associated with rectal balloon inflation (n = 6) and the proportion of those that were not (n = 2) (P = .3).
Potentially serious adverse events related to CT colonography occurred in 0.08% of symptomatic patients.
OBJECTIVES
To report the frequency of renal symptoms and complications of patients with tuberous sclerosis complex (TSC), to describe the ultrasonographic appearance of the kidneys in a ...population‐based sample, and to investigate the relationship between a history of renal haemorrhage and renal lesions identified by ultrasonography.
PATIENTS AND METHODS
As part of an epidemiological study, 179 patients with TSC were identified as living in the Wessex Region in the South of England. Patients were interviewed and examined in their homes, to elicit the presence of renal symptoms or a history of renal complications. Renal ultrasonography was used in consenting patients in their homes.
RESULTS
There was a history of renal complications in 16 (9%) patients; 149 consented to interview and examination, and 19 gave a history of renal symptoms in the previous year; 124 had renal ultrasonography; 86 (69%) had renal angiomyolipomas and 37 (30%) had renal cysts. Large lesions (>3 cm in diameter) were strongly associated with a history of symptomatic bleeding, although significant haemorrhage occurred in a 6‐year‐old child with small angiomyolipomas.
CONCLUSIONS
The formation of angiomyolipoma in TSC is common. Polycystic kidney disease, renal carcinoma and renal failure, although rare, occur in TSC. Most patients with angiomyolipomas have neither complications nor symptoms. There was no appreciable difference between the sexes in the risk of developing these lesions. Although less commonly seen in the very young, there is no identifiable relationship after adolescence between age and the risk of having a renal angiomyolipoma. Bleeding tends to occur from large lesions (>3 cm) but most such patients have remained asymptomatic to date.
Purpose. The purpose of this study was to identify the relationship between the presence of reasonable, developmentally appropriate, active and self-contained, consistent, progressive discipline ...plans with consequences, guidance, start again time, and rewards on student academic performance in California public elementary schools. Methods. A Cronbach’s alpha test assessed the uniformity across similar items within a Likert-type survey. Item responses for each individual principal aligned with the independent variables (reinforcement, guidance, delayed gratification, start again time, and moral development) were compared with standardized academic growth, the dependent variable. Analyses were performed to ensure assumptions for the selected inferential tests of significance were met. The obtained values from a multiple regression analysis and Pearson correlations were compared with a normal probability distribution curve to determine whether or not they were deviant to a degree of significance at which the null hypotheses could be rejected. Findings. The reliability of the rating scale (α = 0.896), the multiple correlation coefficient (R = 0.844) along with the coefficient of determination value (R 2 = 0.712), an F ratio of 53.928, p < .0005, and the high correlations between progressive discipline components and API bands and API growth target performance were important findings. The relationships between each progressive discipline component and performance were statistically significant (p < .0005). Relationships between each API band and performance were positive. Bands 1-4 were statistically significant (p < .0005), and Band 5 was significant ( p < .001) to a slightly lesser degree. Conclusions. It seems logical to attempt to systematically improve the implementation of processes having a strong association with desirable outcomes. Developing reinforcement, positive guidance, delayed gratification, start again time, and moral development can advance academic achievement on a standardized measure, especially in schools performing in Bands 1-4. Recommendations. A triangulated version is necessary for future study based upon the preliminary confirmation of a relationship between the variables. Although subject-matter experts concluded that both the survey and design were appropriate, the researcher believes the eventual statistical analyses of the internal structure of the test are necessary to assess and develop its (construct) validity evidence. The suspected presence of collinearity also requires exploration.
Polycystic disease has an early onset clinically and is the result of large contiguous deletions on chromosome 16 affecting both the TSC2 gene and the gene for adult onset polycystic kidney disease. ...2 Tuberous sclerosis complex exhibits genetic heterogeneity. 3 Mutations in two recently identified genes, TSC1 at 9q34 andTSC2 at 16p13, each result in an apparently similar phenotype, although recent work has suggested that mutations inTSC2 may be associated with more severe disease. 4 Both genes are tumour suppressor genes, the strongest evidence for this being the loss of heterozygosity around the normal gene at 9q34 or 16p13 in hamartomata from tuberous sclerosis patients. 5 6 There is evidence that the severity of learning difficulties in tuberous sclerosis complex is related to the number of hamartomata in the brain. 7 Until now, no one has reported on a correlation between the severity of the phenotype in two or more organs.
The message-driven processor (MDP), a 36-b, 1.1-million transistor, VLSI microcomputer, specialized to operate efficiently in a multicomputer, is described. The MDP chip includes a processor, a ...4096-word by 36-b memory, and a network port. An on-chip memory controller with error checking and correction (ECC) permits local memory to be expanded to one million words by adding external DRAM chips. The MDP incorporates primitive mechanisms for communication, synchronization, and naming which support most proposed parallel programming models. The MDP system architecture, instruction set architecture, network architecture, implementation, and software are discussed.< >
It has been suggested that the Kalman filter technique may be used to improve the quality of hedge fund replication, compared to existing replication techniques. This study uses the Kalman filter ...technique, along with three variations of the rolling-window regression technique, to create clones which attempt to replicate the returns of various categories of hedge fund indices. These clones are created over several scenarios and are used to compare the ability of the Kalman filter and rolling-window regression techniques. The clones are constructed using South African specific asset class and investment style factors. This study finds that the Kalman filter does not provide the expected improvement in replication ability over the rolling-window regression, for the hedge fund indices analysed. The competing techniques appear to each be better suited to replicating different hedge fund index strategies and may, therefore, be used in combination. While some of the hedge fund clones offer desirable risk characteristics, they offer lower mean returns and underperform their indices in most periods. As such, the hedge fund clones constructed in this study require further refinement and are not yet equipped for use in practice.
Retrospective: the J-machine Dally, William J.; Chien, Andrew; Fiske, Stuart ...
25 years of the international symposia on Computer architecture (selected papers),
08/1998
Conference Proceeding
The J-machine multicomputer Noakes, Michael D.; Wallach, Deborah A.; Dally, William J.
Computer architecture news,
05/1993, Letnik:
21, Številka:
2
Journal Article
The MIT J-Machine multicomputer has been constructed to study the role of a set of primitive mechanisms in providing efficient support for parallel computing. Each J-Machine node consists of an ...integrated multicomputer component, the Message-Driven Processor (MDP), and 1 MByte of DRAM. The MDP provides mechanisms to support efficient communication, synchronization, and naming. A 512 node J-Machine is operational and is due to be expanded to 1024 nodes in March 1993. In this paper we discuss the design of the J-Machine and evaluate the effectiveness of the mechanisms incorporated into the MDP. We measure the performance of the communication and synchronization mechanisms directly and investigate the behavior of four complete applications.
Run for your life Noakes, Timothy; Spedding, Michael
Nature (London),
07/2012, Letnik:
487, Številka:
7407
Journal Article
Recenzirano
Odprti dostop
Humans evolved to run. This helps to explain our athletic capacity and our susceptibility to modern diseases, argue Timothy Noakes and Michael Spedding.
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