Portable HEPA filtration successfully augments natural-ventilation-mediated airborne particle clearance in a legacy design hospital ward.

As the severe acute respiratory syndrome coronavirus-2 pandemic has proceeded, ventilation has been recognized increasingly as an important tool in infection control. Many hospitals in Ireland and the UK do not have mechanical ventilation and depend on natural ventilation. The effectiveness of natural ventilation varies with atmospheric conditions and building design. In a challenge test of a legacy design ward, this study showed that portable air filtration significantly increased the clearance of pollutant aerosols of respirable size compared with natural ventilation, and reduced spatial variation in particle persistence. A combination of natural ventilation and portable air filtration is significantly more effective for particle clearance than either intervention alone.

Earthworm-Collembola interactions affecting water-soluble nutrients, fauna and physiochemistry in a mesocosm manure-straw composting experiment.

A mesocosm fermentation experiment was undertaken to investigate interactions between Eisenia fetida and Collembola affecting composting processes. Earthworms, Collembola, respiration, water soluble nutrients and compost characteristics (near infrared spectra - NIRS) were monitored on four occasions over 136 days. Earthworms were the main drivers of early changes in composts, increasing the general abundance of Collembola, although responses varied with species. Earthworms accelerated substrate mineralisation and release of soluble nutrients whilst also changing compost characteristics. Collembola alone had little direct effect on soluble nutrient concentrations or respiration; they did however alter compost characteristics (NIR spectra). Earthworm-Collembola interactions affecting respiration and soluble nutrients were mainly antagonistic in the early stages of composting but synergistic in later stages. In the later stages of composting, the higher abundance of Collembola when combined with earthworms resulted in greater concentrations of soluble nitrate and phosphate. These findings emphasise the importance in vermicomposting practice of different invertebrate groups having access to feedstock at appropriate stages of the process. The high concentrations of soluble nutrients released during vermicomposting indicate the need for control measures to avoid off-site pollution and loss of this resource.

Vacuum packing: a model system for laboratory-scale silage fermentations.

AIMS: To determine the utility of vacuum-packed polythene bags as a convenient, flexible and cost-effective alternative to fixed volume glass vessels for lab-scale silage studies. METHODS AND RESULTS: Using perennial ryegrass or red clover forage, similar fermentations (as assessed by pH measurement) occurred in glass tube and vacuum-packed silos over a 35-day period. As vacuum-packing devices allow modification of initial packing density, the effect of four different settings (initial packing densities of 0.397, 0.435, 0.492 and 0.534 g cm(-3)) on the silage fermentation over 16 days was examined. Significant differences in pH decline and lactate accumulation were observed at different vacuum settings. Gas accumulation was apparent within all bags and changes in bag volume with time was observed to vary according to initial packing density. CONCLUSIONS: Vacuum-packed silos do provide a realistic model system for lab-scale silage fermentations. SIGNIFICANCE AND IMPACT OF THE STUDY: Use of vacuum-packed silos holds potential for lab-scale evaluations of silage fermentations, allowing higher throughput of samples, more consistent packing as well as the possibility of investigating the effects of different initial packing densities and use of different wrapping materials.

Hematological changes during short-term tidal flow extracorporeal life support.

Various methods exist in the clinical practice of long-term venovenous (VV) extracorporeal life support (ECLS). Among the clinical techniques used are single venous access with a dual-lumen catheter, and cannulation of the jugular and femoral veins. Tidal flow VV ECLS uses a single-lumen catheter to achieve both venous drainage and arterialized reinfusion through a series of tubing occluders that are automated by a pump. A single venous occluder tidal flow system with a 15 Fr single-lumen cannula (n = 6) and passive filling M pump was compared to a conventional 14 Fr dual-lumen cannula (n = 7) and roller pump for four hours of VV ECLS. The changes in platelet count and plasma-free hemoglobin (pHgb) were compared. The results showed a decline in platelet counts typical of ECLS in both groups that were not significantly different from each other. A small elevation in pHgb did not rise above normal clinical levels of 15 mg/dL in either group after four hours of ECLS. Some recirculation was observed and needs to be addressed in future studies. Single occluder tidal flow ECLS may be feasible and efficacious for long-term application once recirculation is resolved and the system evaluated for long-term support.

Efficient improvement of silage additives by using genetic algorithms.

The enormous variety of substances which may be added to forage in order to manipulate and improve the ensilage process presents an empirical, combinatorial optimization problem of great complexity. To investigate the utility of genetic algorithms for designing effective silage additive combinations, a series of small-scale proof of principle silage experiments were performed with fresh ryegrass. Having established that significant biochemical changes occur over an ensilage period as short as 2 days, we performed a series of experiments in which we used 50 silage additive combinations (prepared by using eight bacterial and other additives, each of which was added at six different levels, including zero [i.e. , no additive]). The decrease in pH, the increase in lactate concentration, and the free amino acid concentration were measured after 2 days and used to calculate a "fitness" value that indicated the quality of the silage (compared to a control silage made without additives). This analysis also included a "cost" element to account for different total additive levels. In the initial experiment additive levels were selected randomly, but subsequently a genetic algorithm program was used to suggest new additive combinations based on the fitness values determined in the preceding experiments. The result was very efficient selection for silages in which large decreases in pH and high levels of lactate occurred along with low levels of free amino acids. During the series of five experiments, each of which comprised 50 treatments, there was a steady increase in the amount of lactate that accumulated; the best treatment combination was that used in the last experiment, which produced 4.6 times more lactate than the untreated silage. The additive combinations that were found to yield the highest fitness values in the final (fifth) experiment were assessed to determine a range of biochemical and microbiological quality parameters during full-term silage fermentation. We found that these combinations compared favorably both with uninoculated silage and with a commercial silage additive. The evolutionary computing methods described here are a convenient and efficient approach for designing silage additives.

Wild-type and mutant alleles of the Aspergillus nidulans developmental regulator gene brlA: correlation of variant sites with protein function.

The DNA sequences of two wild-type and eleven mutant alleles of the developmental regulator gene brlA from Aspergillus nidulans, which encodes a zinc-finger protein, were characterized. Variant sites were located on rescued plasmids or PCR products based either on their meiotic map position or the use of denaturing gradient gel electrophoresis. Mutations in three null mutants, one of which is partially suppressible, encode premature stop codons. Two environmentally sensitive mutants were characterised by substitution of leucines required for stabilisation of alpha-helices in each of the two putative zinc-finger domains. A third zinc-finger substitution is predicted to disrupt recognition of a guanine residue in the DNA target. The mutations in four other leaky mutants map C-terminal to the zinc fingers; one minimally leaky mutant has a premature stop codon, which results in the removal of the last 38 residues of the protein product.

Enhanced access to rare brain cDNAs by prescreening libraries: 207 new mouse brain ESTs.

To use single-pass cDNA sequencing to characterize low-frequency cDNA clones from a region of the brain that includes the primary site of neurodegeneration in human Parkinson disease, we have developed a prescreening procedure using single brain region first-strand cDNA probes. Selection of cDNA clones giving low hybridization signals allowed the elimination of clones resulting from abundant messages and enrichment for clones corresponding to low-copy messages. Comparative sequencing of standard and prescreened cDNA libraries (191 and 124 clones, respectively) showed that this procedure raised the frequency of novel sequences encountered from 54 to 81%. The increased proportion of novel ESTs justifies the labor of prescreening. Automation of this procedure will accelerate the molecular description of genes expressed in any brain region, or any tissue, and represents a way to maximize access to cDNA sequences for human and mouse genome characterization. In total, the comparative sequencing experiments generated 207 new mouse and 11 new rat brain ESTs.

Homology at the amino acid level between plant phytochromes and a regulator of asexual sporulation in Emericella (= Aspergillus) nidulans.

Protein sequence comparison between the N-terminal regions of the BRLA (bristle A) protein of the ascomycete fungus Aspergillus nidulans and a number of plant phytochromes has demonstrated a moderate level of sequence similarity. The region of similarity corresponds to the phytochrome domains believed to be responsible for photoreception and which undergo light-induced conformational changes, although a putative chromophore-binding site is not evident. Over 22% of residues are conserved and 24% conservatively substituted between residues 1 and 272 of BRLA and the N-terminal domains of Type 1 phytochromes from dicotyledonous species. A lower level of similarity, but over the same region, is observed in comparison with a wider range of phytochromes. Given the known role of BRLA as a transcriptional activator involved in conidiation, and the red/far-red reversible photoregulation of this developmental process, the similarity with phytochromes may be significant.

Spatial distribution of mycelia of the liana (L-) biotype of the agaric Crinipellis perniciosa (Stahel) Singer in tropical forest.

A detailed investigation of the Liana biotype (L-biotype) of Crinipellis perniciosa (Stahel) Sing, was conducted in Ecuador. Basidiocarps of the L-biotype were consistently found in association with stems or debris of the liana Arrabidaea verrucosa (Standl) A. Gentry, although no symptoms associated with witches'broom disease, were observed. Debris colonized by the L-biotype were often connected via pseudosclerotial pads to living sterns of A. verrucosa. Pairings between 87 isolates obtained from basidiocarp stipe tissues or liana bark cores from three sites permitted 37 somatic compatibility groupings (SCGs) to be defined. In all cases these were found to be very restricted in geographical distribution, a situation which contrasts markedly with the distribution of SCGs in the pathogenic and non-outercrossing eocoa biotype. Mating pairings between single basidiospore isolates confirmed chat the outercrossing mechanism of the L-biotype is muitialletic and that no significant biological barriers to gene flow exist between coastal and Amazonian populations. Several lines of evidence suggested that mycelia belonging to the same SCG (= genet) were isogenic. Correlations between field observations and the distributions of both SCGs and mating type factors art- discussed in relation to patterns of dispersal, establishment and spread of this fungus.

Fluoridation and cancer mortality in Anglesey.

Mortality in Anglesey from cancer (all sites), cancer of trachea, bronchus, and lung, cancer of stomach, and cancer of all other sites has been compared with mortality in England and Wales at two periods; 1949-53 (before fluoridation) and 1979-83 (after 20 years and more of fluoridation). No evidence has been found to support the hypothesis that water fluoridation affects cancer mortality.

Cancer surveillance with particular reference to the uses of mortality data.

Cancer surveillance serves several purposes related to prevention, control and treatment. Morbidity information from cancer registration and mortality data based on death certification complement each other and both are necessary for surveillance. In many respects mortality data are sufficiently accurate and specific to reveal major differences and trends. The importance of recognizing even small aggregations of rare tumours is stressed.

Influenza and infant mortality.

Early neonatal mortality in England and Wales in the second quarter of 1970 after a major influenza epidemic was slightly but significantly higher than in the corresponding quarter of the previous year. An increase was also noted in the first quarter of 1970. Analysis of infant mortality and an index of influenza prevalence over the past quarter-century indicates that similar increases occurred in relation to four of the other five major influenza epidemics during the period, the exception being the "Asian 'flu" epidemic of the autumn of 1957. It is suggested that the increased mortality in 1970 was the consequence of an increase in the prematurity rate, but we have no evidence to indicate whether the effect is specifically due to the virus or is nonspecific in nature.