Biodegradation and flushing of MBT wastes.

Mechanical-biological treatment (MBT) processes are increasingly being adopted as a means of diverting biodegradable municipal waste (BMW) from landfill, for example to comply with the EU Landfill Directive. However, there is considerable uncertainty concerning the residual pollution potential of such wastes. This paper presents the results of laboratory experiments on two different MBT waste residues, carried out to investigate the remaining potential for the generation of greenhouse gases and the flushing of contaminants from these materials when landfilled. The potential for gas generation was found to be between 8% and 20% of that for raw MSW. Pretreatment of the waste reduced the potential for the release of organic carbon, ammoniacal nitrogen, and heavy metal contents into the leachate; and reduced the residual carbon remaining in the waste after final degradation from ∼320g/kg dry matter for raw MSW to between 183 and 195g/kg dry matter for the MBT wastes.

Quantifying the effect of settlement and gas on solute flow and transport through treated municipal solid waste.

The effect of degradation and settlement on transport properties of mechanically and biologically treated (MBT) waste was examined by applying three different tracers to two waste columns (~0.5 m diameter) in a series of closed-loop experiments. One column was allowed to biodegrade and the other was bio-suppressed. Permeability and drainable porosity were reduced by settlement, in line with previous results. A dual-porosity model performed well against the data and suggested that more preferential flow occurred early on in the un-degraded column. Diffusion timescales were found to be between 0.8 and 6 days. Volumetric water contents of the mobile region were found to be small in the bio-suppressed cell (~0.01) and even smaller values were found in the degrading waste, possibly due to displacement by gas. Once either settlement or gas production had disrupted this pattern into a more even flow, subsequent compression made little difference to the diffusion time-scale. This may indicate that transport was thereafter dominated by other aspects of the waste structure such as the distribution of low-permeability objects. The presence of gas in the degrading waste reduced the volumetric water content through displacement. The model indicated that the gas was primarily located in the more mobile porosity fraction. Primary compression of the degrading waste tended to squeeze this gas out of the waste in preference to water.

Investigations into the landfill behaviour of pretreated wastes.

Mechanical-biological treatment of municipal solid waste has become popular throughout the UK and other parts of Europe to enable compliance with the Landfill Directive. Pretreatment will have a major influence on the degradation and settlement characteristics of the waste in landfills owing to the changes in the composition and properties of the wastes. This paper presents and compares the results of long term landfill behaviour of the UK and German MBT wastes pretreated to different standards. The gas generating potential, leachate quality and settlement characteristics are highlighted. The results reveal that it is possible to achieve stabilisation of MBT waste within a year and the biogas yield and leachate strength of German MBT waste was significantly reduced compared with the UK MBT waste. The settlement resulting from mechanical creep is more significant than the biodegradation induced settlement in both cases.

Oclusiones arteriales de la retina. Enfoque clínico y seguimiento / Arterial occlusions of the retina. Clinical approach and follow-up

Occlusion of the central retinal artery or from one of its branches is most commonly caused by atherosclerosis or emboli. Central retinal vein occlusions are observed usually in the elderly and as a frequent cause of visual loss, and clinicians should determine firts whether the conditions is due to hypertension, diabetes or atherosclerosis. The aim of this report is to inform to general physcians clear and updated concepts about this disorder, in orden to receive information refered to prevention, diagnosis and treatment of the disease

Oclusiones arteriales de la retina. Enfoque clínico y seguimiento / Arterial occlusions of the retina. Clinical approach and follow-up

Occlusion of the central retinal artery or from one of its branches is most commonly caused by atherosclerosis or emboli. Central retinal vein occlusions are observed usually in the elderly and as a frequent cause of visual loss, and clinicians should determine firts whether the conditions is due to hypertension, diabetes or atherosclerosis. The aim of this report is to inform to general physcians clear and updated concepts about this disorder, in orden to receive information refered to prevention, diagnosis and treatment of the disease

Sustained phosphorylation of cytosolic phospholipase A2 accompanies cycloheximide- and adenovirus-induced susceptibility to TNF.

In this report we examine the phosphorylation state of cytosolic phospholipase A2 (cPLA2) in C3HA fibroblasts that have been treated with TNF, cycloheximide (CHI), or a combination of both compounds. Our experiments show that TNF and CHI, when used independently, caused the rapid phosphorylation of cPLA2 (within 10 min). In both cases, cPLA2 was subsequently dephosphorylated to pretreatment levels by 40 min. In addition, under these conditions [3H]arachidonic acid was not released, and we could not detect a change in the activity of cPLA2 in vitro. In contrast, in cells treated with a combination of TNF and CHI, we found that the dephosphorylation of cPLA2 was inhibited, and cPLA2 remained phosphorylated for up to 2 h. In vitro we found that sustained phosphorylation of cPLA2 was accompanied by a 60 to 80% increase in the activity of cPLA2. The sustained phosphorylation of cPLA2 also occurred in cells infected with the adenovirus mutant dl309, suggesting that sustained phosphorylation may be a general requirement for the activation of cPLA2 in apoptotic cells. We also found that sustained phosphorylation of phosphoproteins is not a general consequence of apoptotic death, since the phosphorylation of p42 mitogen-activated protein kinase was not sustained. Finally, we show that the phosphatase inhibitor orthovanadate acts as does CHI to render cells susceptible to TNF, suggesting that resistance to TNF may depend on TNF's ability to induce the expression of tyrosine or dual specificity phosphatase(s).

Narrative case analysis of HIV infection in a battered woman.

The narrative case analysis of HIV infection in a battered woman, taken from a qualitative study of women's experiences living with HIV/AIDS, conveys unusual insights into the context of violence that surrounded this woman's exposure to HIV. In her narrative, she describes the complex web of abuse she lived with day-to-day and the road she travels with AIDS as a result. Her abuse perpetrator infected her with HIV, and the whole atmosphere of violence, annihilation of self-worth, and oppressive restrictions likely contributed to the late-stage identification and treatment of her HIV-related disease. The discussion explores how domestic violence may place battered women at increased risk of becoming HIV infected. Clinical recommendations suggest that efforts to stop the battering of women and to prevent the spread of HIV in women must be combined to offer effective protection for women.

Nutritional products as drugs or food implications for development.

It is currently recognized that food, other than supplying calories, produces profound effects on bodily function. Consumers and patients receive information regarding whole foods, individual ingredients, and diets from many sources, most of which are unverified for efficacy and safety. No satisfactory mechanism exists for the production of this data, and its regulatory oversight is made more difficult, since many of the products are in everyday commerce and readily available to the consumer. The differences between the methods by which consumer-patient behavior is modified, are discussed. A framework is suggested by which research and development investment over time could be created and maintained, so as to provide well-documented data on safety and medical benefits. Patent and regulatory issues are important elements of the proprietary position essential to sustain an intensive, extended research and development effort in this area.

Results of Buck screw fusion in grade I spondylolisthesis.

The results of posterolateral screw fixation using the Buck technique performed on 24 patients with painful isthmic spondylolysis and up to grade I spondylolisthesis in the lumbar spine are reported. The average age at operation was 29 years and average follow-up was 5 years with a range of 13 months to 12 years. Operations were performed for persistent disabling low back pain. At review 21 patients were either free of pain or complained of only occasional backache and discomfort. All but two patients were satisfied with the operation and rated the result as excellent or good. It is concluded that Buck screw fixation is a safe and reliable method of treatment for painful Grade I spondylolisthesis due to isthmic spondylolysis in the young active adult with a low complication rate.

Anoxic-oxic activated-sludge of cyanides and phenols.

The anoxic-oxic activated-sludge process has been evaluated in a laboratory investigation as a means for effective treatment of cyanide-laden wastewaters, with phenols used as the organic carbon sources for denitrification reactions. The performance of the process was evaluated at different levels of feed cyanide concentration and mean cell residence time (MCRT). The results obtained indicate that the phenolic compounds used can be effectively used as the organic carbon sources to promote denitrification reactions. The effects of cyanide inhibition on overall TOC removal can be alleviated at longer MCRTs. Between 1.2 and 2.2 g TOC can be utilized per gram NO(2) + NO(3) (-) -N removed in the anoxic chamber depending on the prevailing MCRT. Microbial oxidation of cyanide and thiocyanate which yields ammonia is the main mechanism responsible for the removal of cyanide and thiocyanate observed in the anoxic-oxic activated-sludge process. Excellent removal efficiencies have been observed with feed concentrations up to 60 mg CN(-)/L and 100 mg SCN(-)/L Frequent exposure of autotrophic and aerobic cyanideutilizing microbes does not impede their activities in the oxic environment. Good nitrification and denitrification efficiencies are attainable in the anoxic-oxic activated-sludge process in the presence of high feed cyanide and thiocyanate concentrations, provided that MCRT is maintained at a desirable level. As a result, the microbial degradation of cyanide and thiocyanate in conjunction with nitrification and denitrification to produce innocuous nitrogen gas is feasible in the anoxic-oxic activated-sludge process.