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.

Computing sparse multiples of polynomials

We consider the problem of finding a sparse multiple of a polynomial. Given f in F[x] of degree d over a field F, and a desired sparsity t, our goal is to determine if there exists a multiple h in F[x] of f such that h has at most t non-zero terms, and if so, to find such an h. When F=Q and t is constant, we give a polynomial-time algorithm in d and the size of coefficients in h. When F is a finite field, we show that the problem is at least as hard as determining the multiplicative order of elements in an extension field of F (a problem thought to have complexity similar to that of factoring integers), and this lower bound is tight when t=2.Comment: Extended abstract appears in Proc. ISAAC 2010, pp. 266-278, LNCS 650

Harnessing Marine Renewable Energy from Poole Harbour: Case Study

Global warming and its impact on our environment, society, economies and security is one of the fundamental concerns of our time. In response, the United Kingdom government has put in place a legally binding target of an 80% reduction in greenhouse gas emissions on 1990 levels by 2050. The United Kingdom will need to achieve a tenfold expansion of energy supply from renewable sources by 2020 to meet its share of the European Union renewable energy target. The marine and coastal environment’s renewable energy potential in Britain is high. It is estimated that it has 50% of the tidal energy, 35% of wave and 40% of wind resources in the European Union. Use of geothermal resources using heat pump technology is the least evolved sector, but in 2010 contributed to 0.7 TWh of energy and it is believed that non domestic heat pumps could contribute up to 22 TWh by 2020. In the Southwest of England, Poole Harbour has been recognised as a potential, highly predictable source of tidal and heat energy. Local groups are embarking on a feasibility study for harnessing this energy for the benefit of the community. The purpose of this article is to examine the potential conflict of interest between the laudable aims of promoting the use of renewable energy and of safeguarding ecosystems and their biodiversity. Using Poole Harbour as a case study, it will consider the environmental and economic costs and benefits of a Community Renewable Energy project (the Poole Tidal Energy Partnership) in the context of an area subject to a number of statutory and non-statutory designations to protect nationally and internationally important habitats and species. The paper identifies key environmental legislation, including spatial planning law and policy, which will facilitate exploring whether there is potential for reconciling what may be perceived as competing objectives for sustainable development

Genotype dependent response to Azospirillum treatment in yield and nitrogenase activity in Brassica juncea L.

Twelve advanced lines of mustard (Brassica juncea L.) were evaluated for response to treatment with Azospirillum brasilense in yield and a few components. Two lines gave yield increases with concomitant increases in nitrogenase activity and Azospirillum population. In general, there were desirable and significant correlations between plot yield, nitrogenase activity and log, (Azospirillum population). The results point to the possibility of utilizing genotype-dependent response to Azospirillum in breeding programmes and also for exploring new avenues of Azospirillum-based cultural practices in sustaining improved productivity

Effective Selection Criteria for Predicting Thermotolerance in Wheat under Field Conditions

A field experiment was conducted at the experimental area of the Punjab Agricultural University, Ludhiana during Rabi season. Five Wheat cultivars (PBW-343, WH-542, PBW-502, PBW-509 and PBW-3765) sown on six dates of sowing starting from 31st October at weekly intervals up to 5th December to find suitable thermotolerance traits and genotypes. Amongst eleven traits recorded at different growth stages showed that the largest variability was observed in crop growth rate (CGR), Leaf area index (LAI) grain spike weight ratio (GSPWR), spike growth duration (SGD), cumulative growing degree days (GDD) accumulated during vegetative and reproductive phenophases and grain attributes and grain yield at maturity. The highest grain yield was recorded in cultivars PBW-343, WH-542 and PBW-502. The maximum grain yield was correlated with longer filling duration, higher crop growth rate and grain spike weight ratio at anthesis phase. The results revealed that the cumulative growing degree-days (GDD) accumulated more during the reproductive phases as compared with the vegetative phases of wheat cultivars. The GDD is the effective selection criteria for screening thermotolerance in wheat cultivars

Overview of Primitive Object Volatile Explorer (PrOVE) CubeSat or Smallsat Concept

Here we describe the Primitive Object Volatile Explorer (PrOVE), a smallsat mission concept to study the surface structure and volatile inventory of comets in their perihelion passage phase when volatile activity is near peak. CubeSat infrastructure imposes limits on propulsion systems, which are compounded by sensitivity to the spacecraft disposal state from the launch platform and potential launch delays. We propose circumventing launch platform complications by using waypoints in space to park a deep space SmallSat or CubeSat while awaiting the opportunity to enter a trajectory to flyby a suitable target. In our Planetary Science Deep Space SmallSat Studies (PSDS3) project, we investigated scientific goals, waypoint options, potential concept of operations (ConOps) for periodic and new comets, spacecraft bus infrastructure requirements, launch platforms, and mission operations and phases. Our payload would include two low-risk instruments: a visible image (VisCAM) for 5-10 m resolution surface maps; and a highly versatile multispectral Comet CAMera (ComCAM) will measure 1) H2O, CO2, CO, and organics non-thermal fluorescence signatures in the 2-5 m MWIR, and 2) 7-10 and 8-14 m thermal (LWIR) emission. This payload would return unique data not obtainable from ground-based telescopes and complement data from Earth-orbiting observatories. Thus, the PrOVE mission would (1) acquire visible surface maps, (2) investigate chemical heterogeneity of a comet nucleus by quantifying volatile species abundance and changes with solar insolation, (3) map the spatial distribution of volatiles and determine any variations, and (4) determine the frequency and distribution of outbursts

A comparative study of antihyperglycemic effect of Gymnema sylvestre and metformin in streptozotocin induced diabetic rats

Background: Diabetes mellitus (DM) is a metabolic disorder that has the phenotype of hyperglycemia. According to World Health Organization (WHO) there were 65.1 million diabetics in India in 2013, International Diabetes Federation estimates this to increase to 190 million by 2035. Although a number of drugs are available for treatment of DM, their cost and safety profile are major concern. Medicinal plants are used by clinicians for treatment of diabetes. Gymnema sylvestre (GS) extract has been reported to increase insulin levels in diabetic rats. This study was designed to compare the antihyperglycemic effect of Gymnema sylvestre with metformin.Methods: Diabetes was induced in Sprague-Dawley rats using streptozotocin 45mg/kg. Methanolic extract of Gymnema sylvestre 120mg/kg p.o. prepared using Soxhlet apparatus.Results: GS extract reduced blood glucose levels but not statistically significant. GS extract increased HDL and triglycerides, reduced both serum ALT and AST but no statistical significance seen. Metformin significantly increased serum urea, which was not seen in GS extract group. GS extract showed regenerative changes in pancreas, liver and kidney.Conclusions: The study investigation demonstrates that methanolic extract of GS possesses antihyperglycemic and hypolipidaemic activity and so it can be considered as a promising natural remedy in a prediabetic state and in mild hyperlipidaemia to prevent its progression. Increase in β cell regeneration activity could be a probable mechanism of action. However, further long term clinical studies are recommended to define its possible role in diabetes mellitus and hyperlipidaemia. Role of GS as a potential hepatoprotective agent also needs further evaluation