The use of freeze-dried, irradiated fascia lata for suburethral sling procedures was associated with a material failure rate of >/=20%. We caution against its use in this setting.

The traditional formulation of the attrition problem in econometrics treats it as a special case of the partial-population section bias model in which selection (attrition) is based on model unobservables. This paper considers instead the treatment of attrition as a special case of selection on observables. The analysis compares and contrasts the identification assumptions and estimation procedures for this case with those of the usual case of selection on unobservables. Selection on observables case has rarely been considered in the econometric literature on the problem and hence the framing of the problem in these terms, as presented here, is apparently new. The selection on observables problem is made nontrivial by the assumption that selection occurs on endogenous observables; leading examples are lagged dependent variables from earlier periods in the panel. Among other things, it is shown in the paper that (i) weighted least squares using estimated attrition equations to construct the weights is one method of consistent estimation in this case; (ii) simply conditioning on the observables does not, by itself, generate consistent estimates; and (iii) that the model is closely related to the choice-based sampling model. Attrition dans les données de panel: le rôle de la sélection à partir des observablesRÉSUMÉ. -L'approche traditionnelle du problème d'attrition en économétrie le traite comme un cas particulier des modèles à biais de sélection d'une population partielle dans lequel la sélection (l'attrition) repose sur des variables non observables. Ce papier considère en revanche le traitement de l'attrition comme un cas spécial de sélection à partir des observables. L'analyse compare et oppose les hypothèses d'identification et les méthodes d'estimation dans ce cas avec celles du cas usuel de sélection sur des variables non observables. La sélection à partir des observables a été rarement considérée dans la littérature économétrique, si bien que la présentation du problème dans les termes choisis ici semble nouvelle. Le problème de la sélection à partir des observables est rendu non trivial par l'hypothèse que la sélection repose sur des variables endogènes : Ies exemples principaux correspondent à des variables dépendantes retardées issues de périodes précédantes dans le panel. Parmi d'autres résultats, il est montré dans cet article que (i) les moindres carrés pondérés utilisant des équations d'attrition estimées pour construire les poids donnent une estimation convergente, (ii) conditionner simplement sur les observables ne produit pas des estimations convergentes et (iii) le modèle est étroitement lié au modèle dont l'échantillonnage repose sur les valeurs de la variable dépendante.

Twelve strains of bifidobacteria were identified which exhibited a broad spectrum of antagonistic activity against both Gram-positive and Gram-negative indicators, especially Pseudomonas species, using deferred antagonism spot plate assays. Inhibitory action was shown to be unrelated to hydrogen peroxide production and not solely dependent on acidity. However, attempts to detect inhibitory activity in cell-free supernatant fluids from these strains were unsuccessful. The production of inhibitory compound(s) by Bifidobacterium infantis NCFB 2255 was shown to be an unstable trait resulting in phenotypic alternation between production and non-production. Results from food trials using commercial cottage cheese which was inoculated with the inhibitor-producing strains of Bif. infantis NCFB 2255 and Bif. breve NCFB 2258 indicated that levels of Pseudomonas were reduced, but this observation was species-dependent. The viability of bifidobacteria themselves during storage in cottage cheese at refrigeration temperature was found to be a strain variable trait.

This study serves as an example of strategies used to increase the phage resistance of an important Irish Cheddar cheese starter, Lactococcus lactis DPC4268. It describes the emergence and persistence of a lytic bacteriophage, 4268, that has a relatively large burst size and exhibits no homology to the most common phage types encountered in Irish cheese plants. Inherent difficulties were encountered that prevented the effective introduction of conjugative phage‐resistance plasmids pNP40 and pMRC01 to strain DPC4268. In fact, pNP40‐associated Abi systems were naturally present in six of 19 starters. Control of phage 4268 was eventually achieved by generating a mutant of DPC4268, which was subsequently used for cheese manufacture.

The feasibility of using atoxigenic strains of Pithomyces chartarum for the biological control of toxigenic strains of P. chartarum was examined. Pasture, treated with atoxigenic strains of P. chartarum, contained up to 80% less sporidesmin than found in untreated pasture. Maximum sporidesmin levels of 26 ng g-1 grass in treated pasture and 113 ng g-1 grass in untreated pasture (means of 24 and four plots, respectively) were recorded 14 weeks after treatment, when spore numbers had reached a maximum of 80,000 spores g-1 grass in the untreated plots and 50,000 spores g-1 grass in the treated plots. This trial demonstrated that sporidesmin-producing spores of P. chartarum could be successfully reduced in pasture by the addition of atoxigenic strains, thereby reducing the risk of facial eczema in livestock.