NON-GAUSSIAN STATISTICS OF OIL PRICING TIME-SERIES: A CASE STUDY

The stochastic nature of oil price fluctuations is investigated over a twelve-year period, borrowing feedback from an existing database (USA Energy Information Administration database, available online). We evaluate the scaling exponents of the fluctuations by employing different statistical analysis methods, namely rescaled range analysis (R/S), scale windowed variance analysis (SWV) and the generalized Hurst exponent (GH) method. Relying on the scaling exponents obtained, we apply a rescaling procedure to investigate the complex characteristics of the probability density functions (PDFs) dominating oil price fluctuations. It is found that PDFs exhibit scale invariance, and in fact collapse onto a single curve when increments are measured over microscales (typically less than 30 days). The time evolution of the distributions is well fitted by a Levy-type stable distribution. The relevance of a Levy distribution is made plausible by a simple model of nonlinear transfer. Our results also exhibit a degree of multifractality as the PDFs change and converge toward to a Gaussian distribution at the macroscales.

Ultra-fast processing of gigapixel Tissue MicroArray images using high performance computing.

BACKGROUND:
tissue MicroArrays (TMAs) are a valuable platform for tissue based translational research and the discovery of tissue biomarkers. The digitised TMA slides or TMA Virtual Slides, are ultra-large digital images, and can contain several hundred samples. The processing of such slides is time-consuming, bottlenecking a potentially high throughput platform.
METHODS:
a High Performance Computing (HPC) platform for the rapid analysis of TMA virtual slides is presented in this study. Using an HP high performance cluster and a centralised dynamic load balancing approach, the simultaneous analysis of multiple tissue-cores were established. This was evaluated on Non-Small Cell Lung Cancer TMAs for complex analysis of tissue pattern and immunohistochemical positivity.
RESULTS:
the automated processing of a single TMA virtual slide containing 230 patient samples can be significantly speeded up by a factor of circa 22, bringing the analysis time to one minute. Over 90 TMAs could also be analysed simultaneously, speeding up multiplex biomarker experiments enormously.
CONCLUSIONS:
the methodologies developed in this paper provide for the first time a genuine high throughput analysis platform for TMA biomarker discovery that will significantly enhance the reliability and speed for biomarker research. This will have widespread implications in translational tissue based research.

Finite difference time domain modeling of phase grating diffusion

In this paper, a method for modeling diffusion caused by non-smooth boundary surfaces in simulations of room acoustics using finite difference time domain (FDTD) technique is investigated. The proposed approach adopts the well-known theory of phase grating diffusers to efficiently model sound scattering from rough surfaces. The variation of diffuser well-depths is attained by nesting allpass filters within the reflection filters from which the digital impedance filters used in the boundary implementation are obtained. The presented technique is appropriate for modeling diffusion at high frequencies caused by small surface roughness and generally diffusers that have narrow wells and infinitely thin separators. The diffusion coefficient was measured with numerical experiments for a range of fractional Brownian diffusers.

The Many Directions of Time

Event duration perception is fundamental to cognitive functioning. Recent research has shown that localized sensory adaptation compresses perceived duration of brief visual events in the adapted location; however, there is disagreement on whether the source of these temporal distortions is cortical or pre-cortical. The current study reveals that spatially localized duration compression can also be direction contingent, in that duration compression is induced when adapting and test stimuli move in the same direction but not when they move in opposite directions. Because of its direction-contingent nature, the induced duration compression reported here is likely to be cortical in origin. A second experiment shows that the adaptation processes driving duration compression can occur at or beyond human cortical area MT+, a specialised motion centre located upstream from primary visual cortex. The direction-specificity of these temporal mechanisms, in conjunction with earlier reports of pre-cortical temporal mechanisms driving duration perception, suggests that our encoding of subsecond event duration is driven by activity at multiple levels of processing.

Applying an XC6200 to real-time image processing

This implementation of a two-dimensional discrete cosine transform demonstrates the development of a suitable architectural style for a specific technology-in this case, the Xilinx XC6200 FPGA series. The design exploits distributed arithmetic, parallelism, and pipelining to achieve a high-performance custom-computing implementation.

Joint complex diversity coding and channel coding over space, time and frequency

This study provides a general diversity analysis for joint complex diversity coding (CDC) and channel coding-based space-time-frequency codeing is provided. The mapping designs from channel coding to CDC are crucial for efficient exploitation of the diversity potential. This study provides and proves a sufficient condition of full diversity construction with joint three-dimensional CDC and channel coding, bit-interleaved coded complex diversity coding and symbol-interleaved coded complex diversity coding. Both non-iterative and iterative detections of joint channel code and CDC transmission are investigated. The proposed minimum mean-square error-based iterative soft decoding achieves the performance of the soft sphere decoding with reduced complexity.

Trends in childhood type 1 diabetes incidence in Europe during 1989-2008: evidence of non-uniformity over time in rates of increase

AIMS/HYPOTHESIS:

The aim of the study was to describe 20-year incidence trends for childhood type 1 diabetes in 23 EURODIAB centres and compare rates of increase in the first (1989-1998) and second (1999-2008) halves of the period.

METHODS:

All registers operate in geographically defined regions and are based on a clinical diagnosis. Completeness of registration is assessed by capture-recapture methodology. Twenty-three centres in 19 countries registered 49,969 new cases of type 1 diabetes in individuals diagnosed before their 15th birthday during the period studied.

RESULTS:

Ascertainment exceeded 90% in most registers. During the 20-year period, all but one register showed statistically significant changes in incidence, with rates universally increasing. When estimated separately for the first and second halves of the period, the median rates of increase were similar: 3.4% per annum and 3.3% per annum, respectively. However, rates of increase differed significantly between the first half and the second half for nine of the 21 registers with adequate coverage of both periods; five registers showed significantly higher rates of increase in the first half, and four significantly higher rates in the second half.

CONCLUSIONS/INTERPRETATION:

The incidence rate of childhood type 1 diabetes continues to rise across Europe by an average of approximately 3-4% per annum, but the increase is not necessarily uniform, showing periods of less rapid and more rapid increase in incidence in some registers. This pattern of change suggests that important risk exposures differ over time in different European countries. Further time trend analysis and comparison of the patterns in defined regions is warranted.

Cognitive functioning in subjects with recent-onset psychosis from a low-middle-income environment: Multiple-domain deficits and longitudinal evaluation

Cognitive deficits are a key feature of recent-onset psychosis, but there is no consensus on whether such deficits are generalized or confined to specific domains. Besides, it is unclear whether cognitive deficits: a) are found in psychotic patients in samples from outside high-income countries; and b) whether they progress uniformly over time in schizophrenia and affective psychoses. We applied 12 tests organized into eight cognitive domains, comparing psychosis patients (n = 56, time from initial contact = 677.95+/-183.27 days) versus healthy controls (n = 70) recruited from the same area of Sao Paulo, Brazil. Longitudinal comparisons (digit span and verbal fluency) were conducted between a previous assessment of the subjects carried out at their psychosis onset, and the current follow-up evaluation. Psychosis patients differed significantly from controls on five domains, most prominently on verbal memory. Cognitive deficits remained detectable in separate comparisons of the schizophrenia subgroup and, to a lesser extent, the affective psychosis subjects against controls. Longitudinal comparisons indicated significant improvement in schizophrenia, affective psychoses, and control subjects, with no significant group-by-time interactions. Our results reinforce the view that there are generalized cognitive deficits in association with recent-onset psychoses, particularly of non-affective nature, which persist over time. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Subarachnoid haemorrhage (SAH):long-term cognitive outcome in patients treated with surgical clipping or endovascular coiling

Purpose: To compare long-term cognitive outcomes of patients treated with surgical clipping or endovascular coiling after subarachnoid haemorrhage (SAH). Method: Retrospective matched cohort study assessed neuropsychological functioning at least 12 months after aneurysmal SAH treatment. Fourteen patients treated by endovascular coiling and nine patients treated by surgical clipping participated. After gaining written consent, a comprehensive neuropsychological battery was completed. Standardised tests were employed to assess pre-morbid and current intellectual functioning (IQ), attention, speed of information processing, memory and executive function as well as psychosocial functioning and affect. Results: Treatment groups were not significantly different in terms of age, pre-morbid IQ, time from injury to treatment or time since injury. A significant effect of treatment on full-scale IQ score (p = 0.025), performance IQ (p = 0.045) and verbal IQ score (p = 0.029), all favouring the coiled group was observed. A medium effect size between groups difference in immediate memory (p = 0.19, partial ?(2) = 0.08) was also observed. No significant between group differences on attention, executive functioning and speed of information processing measures or mood and psychosocial functioning were noted. Both groups reported increased anxiety and memory, attention and speed of information processing deficits relative to normative data. Conclusions: Study findings indicate fewer cognitive deficits following endovascular coiling. Cognitive deficits in the clipped group may be due in part to the invasive nature of neurosurgical clipping. Further prospective research with regard to long-term cognitive and emotional outcomes is warranted. [Box: see text].