In this study, a structural health monitoring (SHM) method is proposed for damage localization with incomplete observations, which combines a substructuring approach and connectivity analysis of a substructure. The substructuring approach aims to isolate and monitor several substructures individually. The connectivity among the substructural degree-of-freedom (DOFs) was calculated based on the multivariate and conditional Granger causality analysis, and the health of the substructure was determined by analyzing connectivity variations. This method determines whether the substructure is damaged, and it also allows the location of damage within the substructure. It is not necessary to have a dynamic model of the structure; it only requires the use of accelerometers. The proposed method was evaluated numerically and experimentally using a three-dimensional truss structure.

A novel SHM method is proposed for damage localisation and quantification combining the substructuring approach and Vector Auto-Regressive with Exogenous input (VARX) models .The substructuring approach aims to divide the monitored structure into several isolated substructures. Each individual substructure is modelled as a VARX model, and the health of each substructure is determined analysing the variation of the VARX model ’s coefficients. The method allows determining whether the isolated substructure is damaged, and besides allows locating and quantifying the damage within the substructure. It is not necessary to have a physics-based model of the structure and only vibration data of the substructures are required to estimate their VARX models. The proposed method is validated by simulations and experimentally in a five-story structure.

A SHM method is proposed that minimises the required number of sensors for detecting damage. The damage detection method consists of two steps. In an initial characterization step, substructuring approach is applied to the healthy structure in order to isolate the substructures of interest and later, each substructure is identified by a Vector Auto Regressive with eXogenous inputs (VARX) model measuring all DOFs. Then, pairwise conditional Granger causality analysis is carried out with data measured from substructural DOFs to evaluate the information loss when measurements from all DOFs are not available. This analysis allows selecting those accelerometers that can be suppressed minimising the information loss. In the evaluation phase, vibration data from the reduced set of sensors is compared to the estimated data obtained from the healthy substructure's VARX model, and as a result a damage indicator is computed. The proposed detection method is validated by finite element simulations in a lattice structure model.

A novel damage localization method is proposed, which is based on a substructuring approach and makes use of Vector Auto-Regressive with eXogenous input (VARX) models. The substructuring approach aims to divide the monitored structure into several multi-DOF isolated substructures. Later, each individual substructure is modelled as a VARX model, and the health of each substructure is determined analyzing the variation of the VARX model. The method allows to detect whether the isolated substructure is damaged, and besides allows to locate and quantify the damage within the substructure. It is not necessary to have a theoretical model of the structure and only the measured displacement data is required to estimate the isolated substructure's VARX model. The proposed method is validated by simulations of a two-dimensional lattice structure.

A novel damage localization method is proposed, which is based on a substructuring approach and makes use of Vector Auto-Regressive with eXogenous input (VARX) models. The substructuring approach aims to divide the monitored structure into several multi-DOF isolated substructures. Later, each individual substructure is modeled by a VARX model, and the health of each substructure is determined analyzing the variation of the VARX model. The method allows to detect whether the isolated substructure is damaged, and besides allows to locate the damage within the substructure. Only measured displacement data is required to estimate the isolated substructure's VARX model. Moreover, it is not necessary to have a priori knowledge of the structural model. The proposed method is validated by simulations of an eight-storey shear building.

The final step in the secretory pathway, which is the fusion event between secretory vesicles and the plasma membrane, was reconstructed using highly purified secretory vesicles and cytoplasmic-side-out plasma membrane vesicles from the yeast Saccharomyces cerevisiae. Both organelle preparations were obtained from a sec 6-4 temperature-sensitive mutant. Fusion was monitored by means of a fluorescence assay based on the dequenching of the lipophilic fluorescent probe octadecylrhodamine B-chloride (R18). The probe was incorporated into the membrane of secretory vesicles, and it diluted in unlabelled cytoplasmic-side-out plasma membrane vesicles as the fusion process took place. The obtained experimental dequenching curves were found by mathematical analysis to consist of two independent but simultaneous processes. Whereas one of them reflected the fusion process between both vesicle populations as confirmed by its dependence on the assay conditions, the other represented a non-specific transfer of the probe. The fusion process may now be examined in detail using the preparation, validation and analytical methods developed in this study.

Asexual spores or conidia are dispersive propagules produced as an alternative to vegetative growth by a diverse group of filamentous fungi. The cellular development programmes which govern conidiation have been intensely studied in the last few decades, although important gaps stand in the way of our understanding of this phenomenon, namely in the areas of the environmental sensing mechanisms and signal transduction pathways. The aim of this review is to summarize the current advances in conidiation induction in the genus Penicillium, and to put them into context with the state of our knowledge stemming from work in widely studied fungal model systems.

ABSTRACT The filamentous fungus Penicillium cyclopium conidiates in the presence of calcium ions in submerged culture without nutrient limitation according to a precisely timed program. Conidiation could be prematurely induced in a nutritionally sufficient medium which had previously supported growth, suggesting that a metabolite which influenced the process was produced. A diterpenoid with conidiation-inducing activity, conidiogenone, was purified from the culture medium, along with conidiogenol, a putative derivative with delayed activity. Contrary to previous thought, the presence of calcium was demonstrated to only decrease the threshold concentration of conidiogenone required for the induction to proceed. In light of these results, a mechanism of conidiation induction is presented according to which the mycelium produces a conidiation inducer (conidiogenone) that accumulates extracellularly. When a threshold concentration is reached, induction likely takes place by interaction with a specific cellular receptor. The results indicate that conidiogenone is both sufficient and necessary to induce conidiation.

The amount of acid or base consumed in yeast cultures has been recently assigned to the pathway of nitrogen assimilation under respiratory conditions with no contribution by carbon metabolism (Castrillo et al., 1995). In this investigation, experiments under respirofermentative conditions have shown that production or consumption of ethanol does not contribute significantly to the specific rate of proton production (qH+), thus extending the previously obtained relationships for all aerobic conditions in which other major acid/base contributions are not involved. Tests in batch and chemostat culture confirm the validity of qH+ as a formal control parameter in aerobic fermentations. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:445-450, 1998.

Whey proteins were hydrolyzed in a membrane recycle reactor (MRR) in the presence of Alcalase 0.6L under varying enzyme to substrate ratios and residence times. Substrate conversion was directly dependent on these two parameters, and at a fixed enzyme-substrate ratio of 10%, conversion levels could be controlled through residence time, resulting in peptide permeates with homogeneous molecular and functional properties. In addition, recycling of the enzyme and elimination of peptide products resulted in much improved enzyme yields and process productivity levels. However, the process was only operational for 7 h, given membrane fouling and enzyme inactivation phenomena whose contribution occurred in a time-dependent manner. Changes in process design leading to increased reactor stability were examined, and the system is considered to provide a suitable basis for the production of peptides with specific functional and nutritional properties at the industrial level in the future.

Highly purified plasma membrane vesicles were prepared from yeast protoplasts by a combination of osmotic lysis, differential centrifugation, and separation in an aqueous dextran/polyethylene glycol two-phase system. The vesicles were predominantly (85-90%) of cytoplasmic side-out orientation and displayed large ATP-dependent proton pumping activity which was inhibited by vanadate (100 μM) but not by bafilomycin or nitrate. The preparation presented a distinct polypeptide profile with respect to the total membrane fraction and was enriched in the 110-kDa polypeptide corresponding to the plasma membrane H+-ATPase. This preparation of native plasma membranes vesicles is especially suitable for functional studies in vitro.

A whey protein hydrolysate was prepared by incubation of reconstituted whey or a whey protein concentrate with Alcalase 0.6L. The proteolytic degradation of alpha-lactalbumin and beta-lactoglobulin initially resulted in 6-kDa and, later, 2.5-kDa degradation products, quickly followed by the appearance of multiple peptides of 1 kDa or smaller. The hydrolysate showed a steady increase in solubility and a biphasic change in foaming characteristics with decreasing peptide size. At the highest degree of hydrolysis achieved (22%), the majority of the peptides were smaller than 1 kDa and could be efficiently assimilated by the yeast Kluyveromyces marxianus growing in a defined medium.