Assessment of the impact of some common weed management methods on the growth and yield of pineapples in Ghana

A 5X5 Latin Square experiment was conducted in a farmer’s field in the Ga East Municipality of the Greater Accra Region to evaluate the efficacies of different weed management systems and their effect on pineapple production. The different weed management systems evaluated were T1 - weedy check, T2- manual weed control (hoeing) only, T3- synthetic herbicide alone, T4- manual weed control and plastic mulch and T5- herbicide and plastic mulch. Treatments were replicated five times. Suckers were planted at a spacing of 90cm X 60cm X 25cm on 27 August 2010. Appropriate cultural practices were done at the right times. The results indicated that in all the growth parameters, the two plastic mulched treatments showed the greatest effect, followed by the herbicide-applied only treatment over that of the manual weeding treatment. Weed reemergence was almost nil on the plastic mulched plots. Fruit weight of the two plastic mulched treatments was similar, but was significantly higher than all other treatment effects. However, percentage exportable fruits were similar among the synthetic and plastic mulch treatments. The results showed that farmers are better off if they add plastic mulch to the application of herbicides for more effective weed control and quality fruit yield. Keywords: Weed management, pineapple, plastic mulch, herbicide, forcin

Fluids in cosmology

We review the role of fluids in cosmology by first introducing them in General Relativity and then by applying them to a FRW Universe's model. We describe how relativistic and non-relativistic components evolve in the background dynamics. We also introduce scalar fields to show that they are able to yield an inflationary dynamics at very early times (inflation) and late times (quintessence). Then, we proceed to study the thermodynamical properties of the fluids and, lastly, its perturbed kinematics. We make emphasis in the constrictions of parameters by recent cosmological probes.Comment: 34 pages, 4 figures, version accepted as invited review to the book "Computational and Experimental Fluid Mechanics with Applications to Physics, Engineering and the Environment". Version 2: typos corrected and references expande

A mixed inventory structure for German concatenative synthesis

In speech synthesis by unit concatenation a major point is the definition of the unit inventory. Diphone or demisyllable inventories are widely used but both unit types have their drawbacks. This paper describes a mixed inventory structure which is syllable oriented but does not demand a definite decision about the position of a syllable boundary. In the definition process of the inventory the results of a comprehensive investigation of coarticulatory phenomena at syllable boundaries were used as well as a machine readable pronunciation dictionary. An evaluation comparing the mixed inventory with a demisyllable and a diphone inventory confirms that speech generated with the mixed inventory is superior regarding general acceptance. A segmental intelligibility test shows the high intelligibility of the synthetic speech

Dispelling urban myths about default uncertainty factors in chemical risk assessment - Sufficient protection against mixture effects?

© 2013 Martin et al.; licensee BioMed Central LtdThis article has been made available through the Brunel Open Access Publishing Fund.Assessing the detrimental health effects of chemicals requires the extrapolation of experimental data in animals to human populations. This is achieved by applying a default uncertainty factor of 100 to doses not found to be associated with observable effects in laboratory animals. It is commonly assumed that the toxicokinetic and toxicodynamic sub-components of this default uncertainty factor represent worst-case scenarios and that the multiplication of those components yields conservative estimates of safe levels for humans. It is sometimes claimed that this conservatism also offers adequate protection from mixture effects. By analysing the evolution of uncertainty factors from a historical perspective, we expose that the default factor and its sub-components are intended to represent adequate rather than worst-case scenarios. The intention of using assessment factors for mixture effects was abandoned thirty years ago. It is also often ignored that the conservatism (or otherwise) of uncertainty factors can only be considered in relation to a defined level of protection. A protection equivalent to an effect magnitude of 0.001-0.0001% over background incidence is generally considered acceptable. However, it is impossible to say whether this level of protection is in fact realised with the tolerable doses that are derived by employing uncertainty factors. Accordingly, it is difficult to assess whether uncertainty factors overestimate or underestimate the sensitivity differences in human populations. It is also often not appreciated that the outcome of probabilistic approaches to the multiplication of sub-factors is dependent on the choice of probability distributions. Therefore, the idea that default uncertainty factors are overly conservative worst-case scenarios which can account both for the lack of statistical power in animal experiments and protect against potential mixture effects is ill-founded. We contend that precautionary regulation should provide an incentive to generate better data and recommend adopting a pragmatic, but scientifically better founded approach to mixture risk assessment. © 2013 Martin et al.; licensee BioMed Central Ltd.Oak Foundatio

A Copine family member, Cpne8, is a candidate quantitative trait gene for prion disease incubation time in mouse

Prion disease incubation time in mice is determined by many factors including genetic background. The prion gene itself plays a major role in incubation time; however, other genes are also known to be important. Whilst quantitative trait loci (QTL) studies have identified multiple loci across the genome, these regions are often large, and with the exception of Hectd2 on Mmu19, no quantitative trait genes or nucleotides for prion disease incubation time have been demonstrated. In this study, we use the Northport heterogeneous stock of mice to reduce the size of a previously identified QTL on Mmu15 from approximately 25 to 1.2 cM. We further characterised the genes in this region and identify Cpne8, a member of the copine family, as the most promising candidate gene. We also show that Cpne8 mRNA is upregulated at the terminal stage of disease, supporting a role in prion disease. Applying these techniques to other loci will facilitate the identification of key pathways in prion disease pathogenesis

Structure-Function Analysis of Human TYW2 Enzyme Required for the Biosynthesis of a Highly Modified Wybutosine (yW) Base in Phenylalanine-tRNA

Posttranscriptional modifications are critical for structure and function of tRNAs. Wybutosine (yW) and its derivatives are hyper-modified guanosines found at the position 37 of eukaryotic and archaeal tRNAPhe. TYW2 is an enzyme that catalyzes α-amino-α-carboxypropyl transfer activity at the third step of yW biogenesis. Using complementation of a ΔTYW2 strain, we demonstrate here that human TYW2 (hTYW2) is active in yeast and can synthesize the yW of yeast tRNAPhe. Structure-guided analysis identified several conserved residues in hTYW2 that interact with S-adenosyl-methionine (AdoMet), and mutation studies revealed that K225 and E265 are critical residues for the enzymatic activity. We previously reported that the human TYW2 is overexpressed in breast cancer. However, no difference in the tRNAPhe modification status was observed in either normal mouse tissue or a mouse tumor model that overexpresses Tyw2, indicating that hTYW2 may have a role in tumorigenesis unrelated to yW biogenesis

Searching for Exoplanets Using a Microresonator Astrocomb

Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial velocity shifts at levels required for detection of Earth analogs. A new chip-based device, the Kerr soliton microcomb, has properties ideal for ubiquitous application outside the lab and even in future space-borne instruments. Moreover, microcomb spectra are ideally suited for astronomical spectrograph calibration and eliminate filtering steps required by conventional mode-locked-laser frequency combs. Here, for the calibration of astronomical spectrographs, we demonstrate an atomic/molecular line-referenced, near-infrared soliton microcomb. Efforts to search for the known exoplanet HD 187123b were conducted at the Keck-II telescope as a first in-the-field demonstration of microcombs

PAMELA results on the cosmic-ray antiproton flux from 60 MeV to 180 GeV in kinetic energy

The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the galaxy. More precise secondary production models are required for a complete interpretation of the results.Comment: 11 pages, 3 figures, 1 table. Accepted for publication in Physical Review Letter

Does home neighbourhood supportiveness influence the location more than volume of adolescent's physical activity? An observational study using Global Positioning Systems

Background: Environmental characteristics of home neighbourhoods are hypothesised to be associated with residents’ physical activity levels, yet many studies report only weak or equivocal associations. We theorise that this may be because neighbourhood characteristics influence the location of activity more than the volume. Using a sample of UK adolescents, we examine the role of home neighbourhood supportiveness for physical activity, both in terms of volume of activity undertaken and a measure of proximity to home at which activity takes place. Methods: Data were analysed from 967 adolescents living in and around the city of Bristol, UK. Each participant wore an accelerometer and a GPS device for seven days during school term time. These data were integrated into a Geographical Information System containing information on the participants’ home neighbourhoods and measures of environmental supportiveness. We then identified the amount of out-of-school activity of different intensities that adolescents undertook inside their home neighbourhood and examined how this related to home neighbourhood supportiveness. Results: We found that living in a less supportive neighbourhood did not negatively impact the volume of physical activity that adolescents undertook. Indeed these participants recorded similar amounts of activity (e.g. 20.5 mins per day of moderate activity at weekends) as those in more supportive neighbourhoods (18.6 mins per day). However, the amount of activity adolescents undertook inside their home neighbourhood did differ according to supportiveness; those living in less supportive locations had lower odds of recording activity inside their home neighbourhood. This was observed across all intensities of activity including sedentary, light, moderate, and vigorous. Conclusions: Our findings suggest that the supportiveness of the neighbourhood around home may have a greater influence on the location of physical activity than the volume undertaken. This finding is at odds with the premise of the socio-ecological models of physical activity that have driven this research field for the last two decades, and has implications for future research, as by simply measuring volumes of activity we may be underestimating the impact of the environment on physical activity behaviours

Allelic spectrum of the natural variation in CRP

With the recent completion of the International HapMap Project, many tools are in hand for genetic association studies seeking to test the common variant/common disease hypothesis. In contrast, very few tools and resources are in place for genotype–phenotype studies hypothesizing that rare variation has a large impact on the phenotype of interest. To create these tools for rare variant/common disease studies, much interest is being generated towards investing in re-sequencing either large sample sizes of random chromosomes or smaller sample sizes of patients with extreme phenotypes. As a case study for rare variant discovery in random chromosomes, we have re-sequenced ~1,000 chromosomes representing diverse populations for the gene C-reactive protein (CRP). CRP is an important gene in the fields of cardiovascular and inflammation genetics, and its size (~2 kb) makes it particularly amenable medical or deep re-sequencing. With these data, we explore several issues related to the present-day candidate gene association study including the benefits of complete SNP discovery, the effects of tagSNP selection across diverse populations, and completeness of dbSNP for CRP. Also, we show that while deep re-sequencing uncovers potentially medically relevant coding SNPs, these SNPs are fleetingly rare when genotyped in a population-based survey of 7,000 Americans (NHANES III). Collectively, these data suggest that several different types re-sequencing and genotyping approaches may be required to fully understand the complete spectrum of alleles that impact human phenotypes. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at http://dx.doi.org/10.1007/s00439-006-0160-y and is accessible for authorized users