Dynamic Regressions with Variables Observed at Different Frequencies

We consider the problem of formulating and estimating dynamic regression models with variables observed at different frequencies. The strategy adopted is to define the dynamics of the model in terms of the highest available frequency, and to apply certain lag polynomials to transform the dynamics so that the model is expressed solely in terms of observed variables. A general solution is provided for models with monthly and quarterly observations. We also show how the methods can be extended to models with quarterly and annual observations, and models combining monthly and annual observations.

Determining Alpha-Helix Correspondence for Protein Structure Prediction from Cryo-EM Density Maps, Master\u27s Thesis, May 2007

Determining protein structure is an important problem for structural biologists, which has received a significant amount of attention in the recent years. In this thesis, we describe a novel, shape-modeling approach as an intermediate step towards recovering 3D protein structures from volumetric images. The input to our method is a sequence of alpha-helices that make up a protein, and a low-resolution volumetric image of the protein where possible locations of alpha-helices have been detected. Our task is to identify the correspondence between the two sets of helices, which will shed light on how the protein folds in space. The central theme of our approach is to cast the correspondence problem as that of shape matching between the 3D volume and the 1D sequence. We model both the shapes as attributed relational graphs, and formulate a constrained inexact graph matching problem. To compute the matching, we developed an optimal algorithm based on the A*-search with several choices of heuristic functions. As demonstrated in a suite of real protein data, the shape-modeling approach is capable of correctly identifying helix correspondences in noise-abundant volumes with minimal or no user intervention

‘Good’ evidence for improved policy making: from hierarchies to appropriateness

Within the field of public health, and increasingly across other areas of social policy, there are widespread calls to increase or improve the use of evidence for policy making. Often these calls rest on an assumption that improved evidence utilisation will be a more efficient or effective means of achieving social goals. Yet, a clear elucidation of what can be considered ‘good evidence’ for policy use is rarely articulated. Many of the current discussions of best practice in the health policy sector derive from the evidence-based medicine (EBM) movement, embracing the ‘hierarchy of evidence’ in framing the selection of evidence – a hierarchy that places experimental trials as preeminent in terms of methodological quality. However, there are a number of difficulties associated with applying EBM methods of grading evidence onto policy making. Numerous public health authors have noted that the hierarchy of evidence is a judgement of quality specifically developed for measuring intervention effectiveness, and as such it cannot address other important health policy considerations such as affordability, salience, or public acceptability (Petticrew and Roberts, 2003). Social scientists and philosophers of knowledge have illustrated other problems in the direct application of the hierarchy of evidence to guide policy. Complex or structural interventions are often not conducive to experimental methods, and as such, a focus on evidence derived from randomised trials may shift policy attention away from broader structural issues (such as addressing the social determinants of health (Solar and Irwin, 2007)), to disease treatment or single element interventions. Social and behavioural interventions also present external validity problems to experimental methods and meta-analyses, as the mechanisms by which an intervention works in one social context may be very different or produce different results elsewhere (Cartwright, 2011). In these cases, policy makers may be better advised to look for evidence about the mechanism of effect, and evidence of local contextual features (Pawson et al., 2005). We argue that rather than adhering to a single hierarchy of evidence to judge what constitutes ‘good’ evidence for policy, it is more useful to examine evidence through the lens of appropriateness. It is important to utilise evidence to improve policy outcomes, yet the form of that evidence should vary depending on the multiple decision criteria at stake. Policy makers must therefore start by articulating their decision criteria in relation to a given problem or policy, so that the appropriate forms of evidence can be drawn on – from both epidemiological and clinical experiments (e.g. for questions of treatment effect), as well as from social scientific, social epidemiological, and multidisciplinary sources (e.g. for questions of complex causality, acceptability, human rights, etc.). Following this selection of types of evidence on the basis of appropriateness, the rigour and quality of the research can be assessed according to the evidentiary best practice standards of the discipline within which the evidence was produced. This approach speaks to calls to improve the use of evidence through ensuring rigour and methodological quality, yet recognises that good evidence is dictated by specific public health or social policy goals

The effect of light intensity and temperature on berry growth and sugar accumulation in Vitis vinifera 'Shiraz' under vineyard conditions

Temperature and light are key climatic factors which affect grapevine physiology in the growing season. Our aim was to investigate the interactive effects of temperature and light intensity on reproductive growth responses of 'Shiraz' vines in vineyard conditions. Well-watered vines were covered with no shade, light, medium and heavy shade covers in a vineyard over three consecutive seasons. Several heat events, i.e., air temperatures exceeding 40 °C for several days, occurred in two of the seasons. Heavy shade reduced canopy temperatures by 3.2-6 °C in the cooler season and by 4-6 °C in the warmer seasons, relative to air temperature and compared with the open canopy. The onset of berry growth was delayed by the heavy shade but the rate of sugar accumulation was not affected. During the season with the most severe heat events, berry dry matter accumulation was significantly higher in the shaded treatments compared to the unshaded vines. The hypothesis was confirmed that medium and heavy shade conferred high levels of protection on the berry ripening process from high summer temperatures and the concurrent exposure to light intensities

Impact of Fluidic Chevrons on Jet Noise

The impact of alternating fluidic core chevrons on the production of jet noise is investigated. Core nozzles for a representative 1/9th scale, bypass ratio 5 model system were manufactured with slots cut near the trailing edges to allow for air injection into the core and fan streams. The injectors followed an alternating pattern around the nozzle perimeter so that the injection alternated between injection into the core stream and injection into the fan stream. For the takeoff condition and a forward flight Mach number of 0.10, the overall sound pressure levels at the peak jet noise angle decrease with increasing injection pressure. Sound pressure levels increase for observation angles less than 110o at higher injection pressures due to increases in high frequency noise. Greater increases in high frequency noise are observed when the number of injectors increases from 8 to 12. When the forward flight Mach number is increased to 0.28, jet noise reduction (relative to the baseline) is observed at aft angles for increasing injection pressure while significant increases in jet noise are observed at forward observation angles due to substantial acoustic radiation at high frequencies. A comparison between inflow and alternating injectors shows that, for equal mass injection rates, the inflow nozzle produces greater low frequency noise reduction (relative to the baseline) than the alternating injectors at 90o and aft observation angles and a forward flight Mach number of 0.28. Preliminary computational fluid dynamic simulations indicate that the spatial decay rate of the hot potential core flow is less for the inflow nozzle than for the alternating nozzles which indicates that gentle mixing may be preferred over sever mixing when fluidic chevrons are used for jet noise reduction

Economic Factors and Physical Properties of Finger Joint Timber Product to Promote Effective Utilization of Natural Resources

Finger joint (FJ) is one of the most sustainable, eco-friendly and economically valuable concept. It ensures the sustainable utilization of small wood cut pieces which removed as waste. Wood pieces are jointed together using glued box comb finger joint cut. It is a new concept for Sri Lankan furniture industry. Therefore, it is necessary to analyze about economic parameters and physical properties of FJ product to ensure the sustainable utilization of FJ timber products. This study attempted to compare strength, appearance and economic variables such as prices, cost of production and profit of FJ products. Comparison of FJ product (Model: STC B-FJ 0019) with the similar size normal timber products (Model:STC B-132) was done to achieve the objective of the study. Three point bending test was done to evaluate Modulus of Elasticity, Modulus of Rupture and maximum force by using UTM. Timber cooperation laboratory was utilized to evaluate strength properties. According to the results of the statistical analysis, strength reduction for FJ products was significantly high. Strength also varied with timber species. Eucalyptus grandis and Pinus showed the highest strength properties while Teak showed the lowst value. MOE values did not show significant difference (0.224) between Jak, Kumbuk, Teak, Mahogany, Pinus, and E. grandis. Strength on vertical and horizontal FJ cuts did not show significant differences although vertical cut was slightly higher. Timber cost for FJ product showed the lowest because of small cut pieces but finishing material, labour, machinery and factory overheads costs were higher than common furniture. Unit production cost for FJ was Rs.171.91 which is higher compared to the cost of normal furniture of Rs. 147.88. FJ furniture showed the higher price most of the time. Therefore, profitability of FJ furniture was significantly higher than common furniture. The uniqueness and high demand help to increase market price and gain more income for producers. On this context FJ product can be promoted to ensure sustainable utilization of timber. Further, this subject is open for further researchers.Keywords: Finger joint, Strength properties, Satisfactio

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship

IMPACT OF LAND USE CHANGES THE CATCHMENT ON THE QUALITY AND QUANT1TY OF WATER IN THE RAJANGANA RESERVOIR

The condition of the watershed plays an important role in the quality and quantity of thewater of reservoirs. Among the factors, which affect the health of a watershed, areclimate, geology and land use management. Rajangana watershed drains water to theRajangana reservoir, which irrigates about 5520 ha in the dry zone.In the present study, total monthly inflows to the reservoir were calculated through awater balance study and water inflows from the catchments were obtained through asensitivity analysis using past records. Land use changes were studied by using existingland use maps (1: 50,000) using GIS software. Some water quality parameters in thereservoir waters were analysed. These parameters were compared with the ones takenduring the past 10 years from past records of the MASL in order to identify any trendswith the changes of rainfall, temperature, land use etc.The results showed that the annual total water inflow and also the inflow during the dryseason decreased with time. These trends correlated with the increase in built up areas,reduction of forest cover. Further, there was a marked increase of the pH and alkalinity inthe waters with time

STIMULANT LEVELS TO BE USED WITH TWO LOW INTENSITY HARVESTING (LIH) SYSTEMS OF RUBBER UNDER WET AND INTERMEDIATE ZONES OF SRI LANKA

Low frequency harvesting (LFH) systems of rubber (Hevea brasiliensis) result in reduction in labour use and cost. However, yield stimulants (viz. Ethephon) are to be applied to enhance the yield in each harvest as a compromise for the yield reduction due to less number of harvesting days. A system of harvesting the tree once in four days (S/2 d4) has recently been introduced and a weekly harvesting system (S/2 d7) is presently under investigation. In S/2 d4 and S/2 d7, the required doze of Ethephon has exactly not known and that would vary with the climatic condition. Therefore, the present study was aimed to identify the suitable concentrations of Ethephon required for S/2 d4 and S/2 d7 systems under two climatic regions, wet and intermediate zones of Sri Lanka.Ethephon was applied in four concentrations (i.e. 2%, 3%, 4% and 5%) and yield performance in each system was evaluated against that of the traditional harvesting systems of S/2 d2 (tapping the tree once in two days). In the Intermediate zone, S/2 d4 and S/2 d7 systems showed a yield increase of 7 and 14 grams per harvest per 1% increase in Ethephon concentration, respectively.  In the Wet zone, respective increases were recorded as 4 and 7 grams. The S/2 d4 system required ca. 3.7 % and 3.2 % concentrations of Ethephon in the Intermediate and Wet zones, respectively, to achieve the yields given by S/2 d2 system. In S/2 d7, 5% Ethephon was sufficient for both zones. Ethephon concentrations tested had no adverse effects on tree health. Needs for commercial scale studies with financial analyses are discussed