Extracting gravity wave parameters during the September 2002 Southern Hemisphere major sudden stratospheric warming using a SANAE imaging riometer

Using absorption data measured by imaging riometer for ionospheric studies (IRIS) located at the South Africa National Antarctic Expedition (SANAE), Antarctica (72° S, 3° W), we extracted the parameters of gravity waves (GW) of periods between 40 and 50 min during late winter/spring of the year 2002, a period of the unprecedented major sudden stratospheric warming (SSW) in the Southern Hemisphere middle atmosphere. During this period, an unprecedented substantial increase of temperature by about 25–30 K throughout the stratosphere was observed. During the period of the occurrence of the major stratospheric warming, there was a reduction of both the GW horizontal phase speeds and the horizontal wavelengths at 90 km. The GW phase speeds and horizontal wavelengths were observed to reach minimum values of about 7 m s⁻¹ and 19 km, respectively, while during the quiet period the average value of the phase speed and horizontal wavelength was approximately 23 m s⁻¹ and 62 km, respectively. The observed event is discussed in terms of momentum flux and also a potential interaction of gravity waves, planetary waves and mean circulation

Zygotic embryo in vitro culture of Cocos nucifera L. (sv. East African Tall variety) in the coastal lowlands of Kenya

In vitro embryo culture of Cocos nucifera L. was carried out with the aim of determining whether it can be applied as an alternative coconut propagation tool to address the lack of planting materials in Kenya. Zygotic embryos excised from mature healthy pyrenes of high yielding Cocos nucifera L. (sv. East African Tall, a coconut variety from Kenya) were cultured using Murashige and Skoog (MS) culture medium supplemented with plant growth regulators (PGRs) namely 6-benzyl aminopurine (BAP) (0.5 mg/l), naphthalene acetic acid (NAA) (0.5 mg/l), 2,4 dichlorophenoxyacetic acid (2,4-D) (1.7 mg/l) and indole butyric acid (IBA) (1.7 mg/l). Germination of 84 and 27% embryos were recorded in liquid and semi-solid MS medium, respectively. Embryo cultured in liquid medium and incubated in darkness during the initial four weeks resulted in a germination percentage of 80% while incubation in light resulted in only 30% germination. MS medium was also supplemented with 100, 25, 15 and 0% (v/v) coconut water (CW). Embryo germination was 60% in medium supplemented with 15% (v/v) coconut water although 0% (v/v) gave the highest germination rate at 67%. Medium supplementation by 1.7 mg/l 2,4-D PGR resulted in germination of 30% when plant growth regulator was co-autoclaved and 84% when plant growth regulator was sterilized by microfiltration. The results presented in this study indicate that in vitro micropropagation of the Kenyan variety of Cocos nucifera L. is a feasible alternative.Keywords: Cocos nucifera L., in vitro embryo culture, east African tall (EAT) Kenyan variety, zygotic embryoAfrican Journal of Biotechnology Vol. 12(22), pp. 3435-344

Role of Microbial Biopesticides as an Alternative to Insecticides in Integrated Pest Management of Cotton Pests

Cotton (Gossypium hirsutum L.) is the most produced natural fibre worldwide, and it contributes significantly to the economy of almost 80 cotton-producing countries. Given the high pest infestation, huge amounts of insecticides have been used in cotton production. However, this has resulted in the development of resistance from primary cotton pests and contamination of the environment. Furthermore, the reduction of beneficial insects and outbreaks of secondary pests have been observed. Many arthropod pests are associated with cotton, most of which belong to the orders Lepidoptera, Thysanoptera, and Hemiptera. Biocontrol agents play a critical role in preventing pests in most cotton-growing areas globally. Biological control of cotton pests forms part of integrated pest management as most of these pests have developed resistance against synthetic pesticides. This chapter focuses on the effects of some of the biopesticides, on cotton insect pests. It examines the control of cotton pests using microbial-based products Bacillus thuringiensis, Beauveria bassiana, Helicoverpa armigera nucleopolyhedrovirus and Metarhizium rileyi. Furthermore, the chapter summarizes the application of microbial biopesticides as well as the advantages and disadvantages of using these biocontrol agents in agriculture

Modelling to inform next-generation medical interventions for malaria prevention and treatment

Global progress against malaria has stagnated and novel medical interventions to prevent malaria are needed to fill gaps in existing tools and improve protection against infection and disease. Candidate selection for next-generation interventions should be supported by the best available evidence. Target product profiles and preferred product characteristics play a key role in setting selection criteria requirements and early endorsement by health authorities. While clinical evidence and expert opinion often inform product development decisions, integrating modelling evidence early and iteratively into this process provides an opportunity to link product characteristics with expected public health outcomes. Population models of malaria transmission can provide a better understanding of which, and at what magnitude, key intervention characteristics drive public health impact, and provide quantitative evidence to support selection of use-cases, transmission settings, and deployment strategies. We describe how modelling evidence can guide and accelerate development of new malaria vaccines, monoclonal antibodies, and chemoprevention

HAUSGARTEN: Multidisciplinary investigations at a deep-sea, long-term observatory in the Arctic Ocean

The marine Arctic has played an essential role in the history of our planet over the past 130 million years and contributes considerably to the present functioning of Earth and its life. The global cycles of a variety of materials fundamental to atmospheric conditions and thus to life depend to a signifi cant extent on Arctic marine processes (Aargaard et al., 1999). The past decades have seen remarkable changes in key Arctic variables. The decrease of sea-ice extent and sea-ice thickness in the past decade is statistically signifi - cant (Cavalieri et al., 1997; Parkinson et al., 1999; Walsh and Chapman, 2001; Partington et al., 2003; Johannessen et al., 2004). There have also been large changes in the upper and intermediate layers of the ocean, which have environmental implications. For instance, the deep Greenland Sea has continued its decadal trend towards warmer and saltier conditions, with a corresponding decrease in oxygen content, refl ecting the lack of effective local convection and ventilation (Dickson et al., 1996; Boenisch et al., 1997). Changes in temperature and salinity and associated shifts in nutrient distributions will directly affect the marine biota on multiple scales from communities and populations to individuals, consequently altering food-web structures and ecosystem functioning (Benson and Trites, 2002; Moore, 2003; Schumacher et al., 2003; Wiltshire and Manly, 2004; Perry et al., 2005). Today, we do not know whether the severe alterations in abiotic parameters represent perturbations due to human impacts, natural long-term trends, or new equilibriums (Bengtson et al., 2004). Because Arctic organisms are highly adapted to extreme environmental conditions with strong seasonal forcing, the accelerating rate of recent climate change challenges the resilience of Arctic life (Hassol, 2004). The entire system is likely to be severely affected by changing ice and water conditions, varying primary production and food availability to faunal communities, an increase in contaminants, and possibly increased UV irradiance. The stability of a number of Arctic populations and ecosystems is probably not strong enough to withstand the sum of these factors, which might lead to a collapse of subsystems. To detect and track the impact of large-scale environmental changes in the transition zone between the northern North Atlantic and the central Arctic Ocean, and to determine experimentally the factors controlling deep-sea biodiversity, the German Alfred Wegener Institute for Polar and Marine Research (AWI) established the deepsea, long-term observatory HAUSGARTEN, representing the fi rst, and by now only, open-ocean, long-term station in a polar region

The views of patients with spinal cord injuries on their rehabilitation experience

Background and Purpose: Spinal rehabilitation programs seek to enhance the residual functional abilities of people who have an acquired disabling impairment because of SCI. Very little has been published on how patients experience rehabilitation, and what the implication of their experience is on rehabilitation outcomes. The aim of this pilot study was to explore the views of patients with SCI regarding their experience of rehabilitation while in hospital. Materials and Methods: A qualitative exploratory study using semi-structured interviews was employed. Twelve patients constituted the sample of convenience. Qualitative techniques were used to analyze the data. Results: The study revealed a variety of psycho-emotional issues related to the patients’ experience of rehabilitation. Positive issues included being treated humanly, being told the truth about their condition early on, family involvement in rehabilitation and being allowed to contribute to decision making regarding their rehabilitation. Negative issues were mainly their lack of insight into their health condition. Conclusion: The study highlighted important psycho-emotional issues related to the patients’ experience of rehabilitation. Rehabilitation personnel must consider these issues when working with patients with spinal cord injury, to ensure effective rehabilitation outcomes

Bridging the gap: a standards-based approach to OR/MS distributed simulation

Pre-print version. Final version published in ACM Transactions on Modeling and Computer Simulation (TOMACS); available online at http://tomacs.acm.org/In Operations Research and Management Science (OR/MS), Discrete Event Simulation (DES) models are typically created using commercial simulation packages such as Simul8™ and SLX™. A DES model represents the processes associated with a system of interest; but, in cases where the underlying system is large and/or logically divided, the system may be conceptualized as several sub-systems. These sub-systems may belong to multiple stakeholders, and creating an all-encompassing DES model may be difficult for reasons such as, concerns among the intra- and inter-organizational stakeholders with regard to data/information sharing (e.g., security and privacy). Furthermore, issues such as model composability, data transfer/access problems and execution speed may also make a single model approach problematic. A potential solution could be to create/reuse well-defined DES models, each modeling the processes associated with one sub-system, and using distributed simulation technique to execute the models as a unified whole. Although this approach holds great promise, there are technical barriers. One such barrier is the lack of common ground between distributed simulation developers and simulation practitioners. In an attempt to bridge this gap, this paper reports on the outcome of an international standardization effort, the SISO-STD-006-2010 Standard for Commercial-Off-The-Shelf Simulation Package Interoperability References Models (IRMs). This facilitates the capture of interoperability requirements at a modeling level rather than a technical level and enables simulation practitioners and vendors to properly specify the interoperability requirements of a distributed simulation in their terms. Two distributed simulation examples are given to illustrate the use of IRMs

Global-scale tidal variability during the PSMOS campaign of June-August 1999: Interaction with planetary waves

During the PSMOS Global-scale tidal variability experiment campaign of June 1-August 31, 1999, a network of radars made measurements of winds, waves and tides in the mesosphere/lower-thermosphere region over a wide range of latitudes. Clear evidence was found that fluctuations in tidal amplitudes occur on a global scale in both hemispheres, and that at least some of these fluctuations are periodic in nature. Modulation of the amplitude of the 12 h tide was particularly evident at periods of 10 and 16 days, suggesting a non-linear interaction with planetary waves of those periods to be responsible. In selected cases, the secondary waves predicted from non-linear theory could be identified and their zonal wave numbers determined. In some, but not all, cases the longitudinal structure of the secondary waves supports the theory of planetary-wave/tidal interaction being responsible for the observed tidal modulation. It was noted also that beating between a 12.4-lunar and the solar tide could produce a near 16-day modulation of the 12 h tide amplitude that is frequently observed in late summer. © 2002 Elsevier Science Ltd. All rights reserved

Composite polyester membranes with embedded dendrimer hosts and bimetallic Fe/Ni nanoparticles: synthesis, characterisation and application to water treatment

This study describes the preparation, characterization and evaluation of new composite membranes with embedded dendrimer hosts and Fe/Ni nanoparticles. These new reactive membranes consist of films of cyclodextrin–poly(propyleneimine) dendrimers (β-CD–PPI) that are deposited onto commercial polysulfone microporous supports and crosslinked with trimesoyl chloride (TMC). The membranes were subsequently loaded with Fe/Ni nanoparticles and evaluated as separation/reactive media in aqueous solutions using 2,4,6-trichlorophenol as model pollutant. The morphology and physicochemical properties of the composite membranes were characterised using high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy and measurements of contact angle, water intake, porosity and water permeability. The sorption capacity and catalytic activity of the membranes were evaluated using ion chromatography, atmospheric pressure chemical ionisation-mass spectrometry and UV–Vis spectroscopy (UV–Vis). The sizes of the embedded Fe/Ni nanoparticles in the membranes ranged from 40 to 66 nm as confirmed by HR-TEM. The reaction rates for the dechlorination of 2,4,6-trichlorophenol ranged from 0.00148 to 0.00250 min−1. In all cases, we found that the reaction by-products consisted of chloride ions and mixtures of compounds including phenol (m/z = 93), 2,4-dichlorophenol (m/z = 163) and 4-chlorophenol (m/z = 128). The overall results of this study suggest that β-CD–PPI dendrimers are promising building blocks for the synthesis of composite and reactive membranes for the efficient removal of chlorinated organic pollutants from water