Statistical Signal Extraction and Filtering: Notes for the Ercim Tutorial, December 9th 2010

These notes have been written to accompany a tutorial session held at the London School of Economics as a prelude to the ERCIM conference of December 2010.

The Discrete–Continuous Correspondence for Frequency-Limited Arma Models and the Hazards of Oversampling

Discrete-time ARMA processes can be placed in a one-to-one correspondence with a set of continuous-time processes that are bounded in frequency by the Nyquist value of ? radians per sample period. It is well known that, if data are sampled from a continuous process of which the maximum frequency exceeds the Nyquist value, then there will be a problem of aliasing. However, if the sampling is too rapid, then other problems will arise that will cause the ARMA estimates to be severely biased. The paper reveals the nature of these problems and it shows how they may be overcome. It is argued that the estimation of macroeconomic processes may be compromised by a failure to take account of their limits in frequency.Stochastic Differential Equations; Band-Limited Stochastic Processes; Oversampling

Alternative Methods of Seasonal Adjustment

Alternative methods for the seasonal adjustment of economic data are described that operate in the time domain and in the frequency domain. The time-domain method, which employs a classical comb filter, mimics the effects of the model-based procedures of the SEATS–TRAMO and STAMP programs. The frequency-domain method eliminates the sinusoidal elements of which, in the judgment of the user, the seasonal component is composed. It is proposed that, in some circumstances, seasonal adjustment is best achieved by eliminating all elements in excess of the frequency that marks the upper limit of the trend-cycle component of the data. It is argued that the choice of the method seasonal adjustment is liable to affect the determination of the turning points of the business cycle.Wiener–Kolmogorov Filtering; Frequency-Domain Methods; The Trend-Cycle Component

Bolt Bearing Behavior of Engineered Wood Composites

The goal of this research was to gain a better understanding of the bolt bearing behavior of engineered wood composites made from yellow poplar lumber. Lumber specimens included in this study were laminated veneer lumber, strandbased lumber, yellow poplar lumber, and Douglas-fir larch lumber. Testing followed the half-hole and full-hole configuration as set forth in ASTM Standard D5764 (1998). In a previous study by Wilkinson (1991), a strong correlation was shown between bearing strength perpendicular to grain and bolt diameter. This study supports Wilkinson\u27s finding for bearing strength perpendicular-to-grain based on the half hole test configuration. Other findings in this study indicate there may be a correlation between bolt diameter and bearing strength parallel-to-grain for the half-hole test configuration as well as a correlation between bolt diameter and bearing strength both perpendicular- and parallel-to-grain for the full-hole test configuration. In general, half-hole tests resulted in a greater dowel-bearing strength than full-hole tests, especially for 12.7mm (1/2 in) diameter bolts. Also, engineered wood composites generally provided equivalent or greater dowel-bearing strength in the half-hole configuration and greater dowel-bearing strength in the full-hole configuration when compared to lumber from the same species

Healthcare resource utilisation and related costs of patients with CKD from the UK: a report from the DISCOVER CKD retrospective cohort

Background Chronic kidney disease (CKD) is widely reported to decrease quality of life, increase morbidity and mortality and cause increased healthcare resource utilisation (HCRU) as the disease progresses. However, there is a relative paucity of accurate and recent estimates of HCRU in this patient population. Our aim was to address this evidence gap by reporting HCRU and related costs in patients with CKD from the UK primary and secondary care settings. Methods HCRU and cost estimates of CKD were derived for UK patients included in the DISCOVER CKD cohort study using clinical records from the Clinical Practice Research Datalink linked to external databases. Patients with a history of transplant or undergoing dialysis were not included. HCRU and costs were stratified by CKD severity using the urinary albumin:creatinine ratio (UACR) and estimated glomerular filtration rate. Results Hospitalisation rates more than tripled between low (A1) and high (A3) UACR categories and the mean annual per-patient costs ranged from £4966 (A1) to £9196 (A3) and from £4997 (G2) to £7595 (G5), demonstrating that a large healthcare burden can be attributed to a relatively small number of patients with later stage CKD, including those with kidney failure and/or albuminuria. Conclusions HCRU and costs associated with CKD impose a substantial burden on the healthcare system, particularly in the more advanced stages of CKD. New interventions that can delay the progression of CKD to kidney failure may not only prolong the patient’s life, but would also provide significant resource and cost savings to healthcare providers

Copper Complexes as Influenza Antivirals: Reduced Zebrafish Toxicity

Copper complexes have previously been developed to target His37 in influenza M2 and are effective blockers of both the wild type (WT) and the amantadine-resistant M2S31N. Here, we report that the complexes were much less toxic to zebrafish than CuCl2. In addition, we characterized albumin binding, mutagenicity, and virus resistance formation of these metal complexes, and employed steered molecular dynamics simulations to explore whether the complexes would fit in M2. We also examined their anti-viral efficacy in a multi-generation cell culture assay to extend the previous work with an initial-infection assay, discovering that this is complicated by cell culture medium components. The number of copper ions binding to bovine serum albumin (BSA) correlates well with the number of surface histidines and BSA binding affinity is low compared to M2. No mutagenicity of the complexes was observed when compared to sodium azide. After 10 passages of virus in MDCK culture, the EC50 was unchanged for each of the complexes, i.e. resistance did not develop. The simulations revealed that the compounds fit well in the M2 channel, much like amantadine

A multi-organ transcriptome resource for the Burmese Python (Python molurus bivittatus)

<p>Abstract</p> <p>Background</p> <p>Snakes provide a unique vertebrate system for studying a diversity of extreme adaptations, including those related to development, metabolism, physiology, and venom. Despite their importance as research models, genomic resources for snakes are few. Among snakes, the Burmese python is the premier model for studying extremes of metabolic fluctuation and physiological remodelling. In this species, the consumption of large infrequent meals can induce a 40-fold increase in metabolic rate and more than a doubling in size of some organs. To provide a foundation for research utilizing the python, our aim was to assemble and annotate a transcriptome reference from the heart and liver. To accomplish this aim, we used the 454-FLX sequencing platform to collect sequence data from multiple cDNA libraries.</p> <p>Results</p> <p>We collected nearly 1 million 454 sequence reads, and assembled these into 37,245 contigs with a combined length of 13,409,006 bp. To identify known genes, these contigs were compared to chicken and lizard gene sets, and to all Genbank sequences. A total of 13,286 of these contigs were annotated based on similarity to known genes or Genbank sequences. We used gene ontology (GO) assignments to characterize the types of genes in this transcriptome resource. The raw data, transcript contig assembly, and transcript annotations are made available online for use by the broader research community.</p> <p>Conclusion</p> <p>These data should facilitate future studies using pythons and snakes in general, helping to further contribute to the utilization of snakes as a model evolutionary and physiological system. This sequence collection represents a major genomic resource for the Burmese python, and the large number of transcript sequences characterized should contribute to future research in this and other snake species.</p