The feeding behaviour and Plasmodium infection of Anopheles mosquitoes in southern Ethiopia in relation to use of insecticide-treated livestock for malaria control.

Anopheles arabiensis and An. quadriannulatus species B mosquitoes were collected at sites of human and livestock housing and analysed for blood feeding patterns and infection with malaria sporozoites. A low percentage of human blood meals at some sites suggested that zooprophylaxis could be effective in reducing challenge from Plasmodium falciparum

Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica

In the Ross Sea, there are two major phytoplankton functional groups: diatoms and prymnesiophytes (dominated by Phaeocystis antarctica). Phaeocystis antarctica often occurs in colonial form, but also as solitary cells, and the two forms have distinct ecological roles. A comparison of the growth characteristics of solitary and colonial forms of Phaeocystis sp. is essential to understanding the differential impact each has on biogeochemical and ecological processes, and to allow parameterization of each form in numerical models. We measured the biomass and photosynthetic responses of two size fractions (\u3e 20 and \u3c 20 mu m), representing colonies and solitary cells, at locations dominated by P. antarctica to assess the relative photosynthetic potential of the two forms. While the relative contribution of each form to total P. antarctica biomass differed among years, there were no significant differences between maximum photosynthetic rates of colonial and solitary forms within years. Substantial interannual variations in biomass and maximum photosynthetic rates normalized to chlorophyll a (PmB) and initial light-limited rates of photosynthesis (alpha) were observed among years for the colonial fractions; however, interannual variations in maximum rates of photosynthesis or alpha of solitary cells were not observed. A laboratory experiment with P. antarctica, together with field data, showed that growth stage of colonies strongly affected the maximum photosynthetic rates. Under nutrient-replete conditions and exponential growth, colonial cells had higher maximum photosynthetic rates than solitary cells, but as growth rate declined and senescence began, the solitary cells\u27 rates became greater. This may be a reason for the high abundance of colonies that is often found in the Ross Sea during austral spring. Our results suggest that photosynthetic rates may influence the composition of the morphotypes of Phaeocystis, but do not appear to be the sole factor in regulating this critical biological variable

Comparative cost-based analysis of a novel plug-in hybrid electric vehicle with conventional and hybrid electric vehicles

© 2015 Universiti Malaysia Pahang. Hybrid electric vehicles provide higher fuel efficiency and lower emissions through the combination of the conventional internal combustion engine with electric machines. This paper analyzes and compares two types of hybrid electric powertrain with a conventional vehicle powertrain to study the lifetime costs of these vehicles. The novelty of the University of Technology Sydney plug-in hybrid electric vehicle (UTS PHEV) arises through a special power-splitting device and energy management strategy. The UTS PHEV and comparative powertrains are studied through numerical simulations to determine fuel consumption for the proposed low and high congestion drive cycles. Satisfactory results are achieved in terms of fuel economy, the all-electric range and electrical energy consumption for the UTS PHEV powertrain, providing significant improvement over the alternative powertrains. The analysis of these vehicles is extended to include a cost-based analysis of each powertrain in order to estimate the total lifetime costs at different fuel prices. The results obtained from this analysis demonstrate that whilst the conventional powertrain is cheaper in terms of purchase and maintenance costs, both alternative configurations are more cost-effective overall as the average price of fuel increases

Survival and recovery of Phaeocystis antarctica (Prymnesiophyceae) from prolonged darkness and freezing

The colony-forming haptophyte Phaeocystis antarctica is an important primary producer in the Ross Sea, and must survive long periods of darkness and freezing temperature in this extreme environment. We conducted experiments on the responses of P. antarctica-dominated phytoplankton assemblages to prolonged periods of darkness and freezing. Chlorophyll and photosynthetic capacity of the alga declined nonlinearly and independently of each other in the dark, and darkness alone would potentially reduce photosynthetic capacity by only 60 per cent over 150 days (approximately the length of the Antarctic winter in the southern Ross Sea). The estimated reduction of colonial mucous carbon is higher than that of colonial cell carbon, suggesting metabolism of the colonial matrix in the dark. The alga quickly resumed growth upon return to light. Phaeocystis antarctica also survived freezing, although longer freezing durations lengthened the lag before growth resumption. Particulate dimethylsulfoniopropionate relative to chlorophyll increased upon freezing and decreased upon darkness. Taken together, the abilities of P. antarctica to survive freezing and initiate growth quickly after darkness may provide it with the capability to survive in both the ice and the water column, and help explain its repeated dominance in austral spring blooms in the Ross Sea and elsewhere in the Southern Ocean

Severe transient left ventricular dysfunction induced by thyrotoxicosis

We report on a 44-year-old woman presenting with chest pain and dyspnoea without previous stress-related events. By means of echocardiography severe left ventricular dysfunction and wall motion abnormalities resembling stress-induced cardiomyopathy (Tako Tsubo) were seen. Laboratory investigation revealed thyrotoxicosis and elevated cardiac markers. Six days after starting medical treatment, complete restoration of the left ventricular function was observed. The transient left ventricular dysfunction was induced by thyrotoxicosis resembling stress-induced cardiomyopathy that resolved completely after medical treatment

Globular Cluster Distance Determinations

The present status of the distance scale to Galactic globular clusters is reviewed. Six distance determination techniques which are deemed to be most reliable are discussed in depth. These different techniques are used to calibrate the absolute magnitude of the RR Lyrae stars. The various calibrations fall into three groups. Main sequence fitting using Hipparcos parallaxes, theoretical HB models and the RR Lyrae in the LMC all favor a bright calibration, implying a `long' globular cluster distance scale. White dwarf fitting and the astrometric distances yield a somewhat fainter RR Lyrae calibration, while the statistical parallax solution yields faint RR Lyrae stars implying a `short' distance scale to globular clusters. Various secondary distance indicators discussed all favor the long distance scale. The `long' and `short' distance scales differ by (0.31+/-0.16) mag. Averaging together all of the different distance determinations yields Mv(RR) = (0.23+/-0.04)([Fe/H] + 1.6) + (0.56+/-0.12) mag.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in pres

Salient employability skills for youth with intellectual and developmental disabilities in Singapore: the perspectives of job developers

Objective: In order to increase employment opportunities for individuals with intellectual and developmental disabilities (IDDs), professionals are tasked with designing and implementing job training services to youth preparing to enter the job market. Having a better understanding of desirable employability skills aids in allowing professionals to develop programs that will target the needs of those who make decisions relating to human resources. Methods: This study features a qualitative research design to identify employability skills that individuals with IDDs in Singapore should possess to be successful in the workplace. Job developers were interviewed to identify and explore desirable employability skills. Results: Results from interviews suggest that soft skills, such as attitude, dependability, stamina, flexibility, and communication are valued over skills that are more job-specific technical skills. Conclusion: These findings highlight the importance including instruction in these skill areas when training youth with IDDs to find and maintain employment

Characteristics of C-4 photosynthesis in stems and petioles of C-3 flowering plants

Most plants are known as C-3 plants because the first product of photosynthetic CO2 fixation is a three-carbon compound. C-4 plants, which use an alternative pathway in which the first product is a four-carbon compound, have evolved independently many times and are found in at least 18 families. In addition to differences in their biochemistry, photosynthetic organs of C-4 plants show alterations in their anatomy and ultrastructure. Little is known about whether the biochemical or anatomical characteristics of C-4 photosynthesis evolved first. Here we report that tobacco, a typical C-3 plant, shows characteristics of C-4 photosynthesis in cells of stems and petioles that surround the xylem and phloem, and that these cells are supplied with carbon for photosynthesis from the vascular system and not from stomata. These photosynthetic cells possess high activities of enzymes characteristic of C-4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis. These biochemical characteristics of C-4 photosynthesis in cells around the vascular bundles of stems of C-3 plants might explain why C-4 photosynthesis has evolved independently many times

Fluctuating selection models and Mcdonald-Kreitman type analyses

It is likely that the strength of selection acting upon a mutation varies through time due to changes in the environment. However, most population genetic theory assumes that the strength of selection remains constant. Here we investigate the consequences of fluctuating selection pressures on the quantification of adaptive evolution using McDonald-Kreitman (MK) style approaches. In agreement with previous work, we show that fluctuating selection can generate evidence of adaptive evolution even when the expected strength of selection on a mutation is zero. However, we also find that the mutations, which contribute to both polymorphism and divergence tend, on average, to be positively selected during their lifetime, under fluctuating selection models. This is because mutations that fluctuate, by chance, to positive selected values, tend to reach higher frequencies in the population than those that fluctuate towards negative values. Hence the evidence of positive adaptive evolution detected under a fluctuating selection model by MK type approaches is genuine since fixed mutations tend to be advantageous on average during their lifetime. Never-the-less we show that methods tend to underestimate the rate of adaptive evolution when selection fluctuates