High-Resolution Dynamics of Hydrogen Peroxide on the Surface of Scleractinian Corals in Relation to Photosynthesis and Feeding

We developed and used a microsensor to measure fast (<1 s) dynamics of hydrogen peroxide (H2O2) on the polyp tissue of two scleractinian coral species (Stylophora pistillata and Pocillopora damicornis) under manipulations of illumination, photosynthesis, and feeding activity. Our real-time tracking of H2O2 concentrations on the coral tissue revealed rapid changes with peaks of up to 60 mu M. We observed bursts of H2O2 release, lasting seconds to minutes, with rapid increase and decrease of surficial H2O2 levels at rates up to 15 mu M s(-1). We found that the H2O2 levels on the polyp surface are enhanced by oxygenic photosynthesis and feeding, whereas H2O2 bursts occurred randomly, independently from photosynthesis. Feeding resulted in a threefold increase of baseline H2O2 levels and was accompanied by H2O2 bursts, suggesting that the coral host is the source of the bursts. Our study reveals that H2O2 levels at the surface of coral polyps are much higher and more dynamic than previously reported, and that bursts are a regular feature of the H2O2 dynamics in the coral holobiont

A Killing Disease Epidemic Among Displaced Sudanese Population Identified as Visceral Leishmaniasis.

A fatal disease epidemic affected the Bentiu area in southern Sudan and led to a mass migration of the Nuer tribe searching for treatment. The initially available information revealed a high mortality rate due to a possible occurrence of tuberculosis, malaria, enteric fever or visceral leishmaniasis (VL). Serological screening of 53 of the most severely affected patients in an enzyme-linked immunosorbent assay (ELISA) or an improved direct agglutination test (DAT) revealed positivity for VL. In 39 of those patients, diagnosis was confirmed by identification of Leishmania donovani amastigotes in lymph node or bone-marrow aspirates. In a total of 2714 patients observed, 1195 (44.0%) had clinical symptoms suggesting VL: DAT positive titers (1:3200-greater than or equal to 1:12800) were obtained in 654 (24.1%), of whom 325 were confirmed parasitologically. Forty-two VL cases died before or during treatment, giving a mortality rate of 6.4%. Among the intercurrent infections diagnosed in the VL population (654), respiratory involvements (31.7%) and malaria (10.7%) were most prevalent. With the exception of four (0.6%), all other VL patients (509) responded readily to sodium stibogluconate. The factors initiating the outbreak are discussed. Malnutrition and nomadic movements to potential VL endemic areas appeared to be the most important. HIV infection as a possible predisposition seemed remote considering the clinical and epidemiological similarity to VL occurring in East Africa, adequate humoral response in DAT, and immediate positive response to specific anti-Leishmania chemotherapy

On mercury vapor lamps and their effect on the smart-grid PLC channel

Abstract: The mercury vapor lamp is the oldest high intensity discharge technology lamp that uses an electric arc, and comes in different shapes and designs. It creates a very bright light by using an arc through vaporized mercury in a high pressure tube. This lamp can cause unwanted interference to the smart-grid network or power line communications channel when connected to the channel’s wiring system. In this paper we investigate the negative effects that the mercury vapor lamps with electric ballast have on the smart-grid PLC channel. This can have a strong and negative effect when using the smart-grid PLC network to control the automatic switching of lamps in public places. The narrowband and broadband channels are investigated where the interference level from mercury vapor lamps is significantly below the allowed maximum PLC signal levels on the band: (3 kHz – 150 kHz), and competes with Electromagnetic Compatibility (EMC) levels on the 150 kHz – 30 MHz band. The mercury vapor lamp uses an electric ballast to connect to the powerline system. This connection is explained in detail

The influence of high pressure sodium lamps on the power line communications channel

Abstract: The high pressure sodium lamp is a high energy outdoor light source that belongs to the high intensity discharge lamp family. It comes in different shapes and requires a ballast to start it. The high pressure sodium lamp is a source of interference to the power line communications channel as it injects noise when connected to the 220V mains. This paper investigates the influence of the high pressure sodium lamp on the narrowband and broadband power line communications channel. It is shown that the frequency band: 3kHz – 150kHz is not highly infected whereas in the band: 150kHz – 30MHz, PLC signals compete with Electromagnetic Compatibility (EMC) levels

The influence of fluorescent lamps with electronic ballast on the low voltage PLC network

The fluorescent lamps or fluorescent tubes are low pressure mercury-vapor gas-discharge lamps that use fluorescence to produce visible light. These lamps inject noise into the power-line communications channel. This can have a detrimental effect on the power-line communication system. In this paper we investigate the effects when the fluorescent lamps with electronic ballasts are seen as noise sources on the powerline channel. It is shown that in the CENELEC band: (3kHz – 150kHz) the interference level from fluorescent lamps is significantly below the allowed maximum PLC signal levels. In the band 150kHz – 30MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational method of the electronic ballast inside the fluorescent lamp is explained

Noise generated by modern lamps and the influence on the smart-grid communication network

Abstract: The metal halide lamp is a high energy electric lamp that produces visible light by an electric arc tube and it is a type of high-intensity discharge (HID) that contains a fused quartz and mixture of gases. These lamps inject noise into the smart-grid power line communications (PLC) network. This can have a strong and negative effect when using the PLC system to control the automatic switching of lamps in public places. In this paper we investigate the effects when the metal halide lamps with electronic or electromagnetic ballasts are seen as noise sources on the smart-grid power line network. It is shown that in the CENELEC band: (3 kHz – 150 kHz) the interference level from metal halide lamps is significantly below the allowed maximum PLC signal levels. In the band 150 kHz – 30 MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational methods of the electronic and electromagnetic ballasts when connected to the metal halide lamps are explained

Influence of LED tubes on the throughput of an indoor broadband PLC channel

Abstract: This paper shows how Light Emitting Diode (LED) Tubes negatively influence the data rate throughput of an indoor broadband Power Line Communications (PLC) channel. This negative influence on the data rate is due to noise being generated by the lamps. Differential Mode measurements were done with two PLC modems communicating and then introducing LED lamps that add noise to the channel. Drops in data throughput rates were measured and compared to a clean (no noise) channel. A significant decrease (up to 50%) in throughput was observed which can have important implications for applications of PLC in the presence of LED Tubes

Additive manufacturing interventions during the covid-19 pandemic: South Africa

Additive manufacturing (AM), also known as 3D printing, is considered a renaissance of the manufacturing industry. Its unique capability of manufacturing 3D objects with intricate geometrical configurations has been used to produce hospital equipment and personal protective equipment (PPE) in an attempt to curb the spread of the COVID-19 pandemic in South Africa. The technology has been used by different research units to produce ventilators, respirator face masks, oscillating respiratory devices, oxygen connectors, oxygen splitters, non-invasive ventilation helmets, reusable clinician PPE, visor frames for face shields, etc. Despite the efforts of the AM community in South Africa, COVID-19 infections have continued to increase in the country. It came to light that technological interventions (including AM) alone cannot prevent the spread of the virus without the corresponding adaptive behavioural changes, such as adhering to COVID-19 prevention protocols (washing of hands, social distancing, etc.). It could be postulated that the spread of COVID-19 can only be prevented by inter-marrying the technological interventions (AM) with adaptive behavioural changes

Endocytosis of Extracellular Vesicles and Release of Their Cargo from Endosomes

Extracellular vesicles (EVs), such as exosomes, can mediate long-distance communication between cells by delivering biomolecular cargo. It is speculated that EVs undergo back-fusion at multivesicular bodies (MVBs) in recipient cells to release their functional cargo. However, direct evidence is lacking. Tracing the cellular uptake of EVs with high resolution as well as acquiring direct evidence for the release of EV cargo is challenging mainly because of technical limitations. Here, we developed an analytical methodology, combining state-of-theart molecular tools and correlative light and electron microscopy, to identify the intracellular site for EV cargo release. GFP was loaded inside EVs through the expression of GFP-CD63, a fusion of GFP to the cytosolic tail of CD63, in EV producer cells. In addition, we genetically engineered a cell line which expresses anti-GFP fluobody that specifically recognizes the EV cargo (GFP). Incubation of anti-GFP fluobody- expressing cells with GFP-CD63 EVs resulted in the formation of fluobody punctae, designating cytosolic exposure of GFP. Endosomal damage was not observed in EV acceptor cells. Ultrastructural analysis of the underlying structures at GFP/ fluobody double-positive punctae demonstrated that EV cargo release occurs from endosomes/lysosomes. Finally, we show that neutralization of endosomal pH and cholesterol accumulation in endosomes leads to blockage of EV cargo exposure. In conclusion, we report that a fraction of internalized EVs fuse with the limiting membrane of endosomes/lysosomes in an acidification-dependent manner, which results in EV cargo exposure to the cell cytosol

An overview of colour LED & CFL lighting interference on the low voltage PLC network

Abstract: Light sources are being competitive in the current market. Several types of these products have been widely used in the last two decades. They play a major role on the low voltage network as they produce and inject undesired noise onto the transmission lines of the PLC channel. This noise can be of a serious and negative effect when using the power line communications system to control the automatic switching of lamps in residential areas and public places. The main colour low-energy indoor light sources that exist in the market, such as, LEDs and CFLs have been tested for the noise generation on the PLC channel and the results are analyzed and shown in this study. A mathematical analysis of LED bridge rectifier is introduced in this study