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• Factors influencing model updating results by Douglas-Reid method are analyzed. • Performance of continuous model updating algorithms are assessed. • Robustness to the influence of varying environmental conditions is checked. • Encouraging results are obtained for integration with Structural Health Monitoring. The opportunities of Operational Modal Analysis and Finite Element model updating for non-destructive structural assessment have attracted significant research interest in recent years. In order to keep the computational efforts associated with model updating as low as possible, different strategies have been proposed over the years to approximate the model response. Among them, response surface models and the Douglas-Reid method are the most popular. However, systematic investigations about the factors affecting their model updating performance in view of Structural Health Monitoring applications are currently very limited. The present paper focuses the attention on the Douglas-Reid method, and analyzes the influence of different factors on the accuracy and reliability of model updating results. Comparisons with different updating approaches, such as grid search and the Inverse Eigensensitivity method, are also reported. The final objective is assessing the performance of the Douglas-Reid method for indirect monitoring of selected updating variables in the context of Structural Health Monitoring applications. Robustness and accuracy of model updating results under varying environmental conditions are evaluated to this aim, highlighting the interesting applicative perspectives of the method in the context of vibration-based Structural Health Monitoring, in spite of the very limited number of similar applications reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract: Size spectra show common patterns of variation among ecosystem types, functional guilds and taxonomic groups, as well as predictable responses to pressures. Here, we extend the size spectra approach to macroinvertebrate ecological status assessment in transitional waters, by developing, testing and validating a multi-metric index of size spectra sensitivity (ISS), which integrates size structure metrics with metrics describing the sensitivity of size classes to anthropogenic disturbance and species richness measures. The ability of different theoretical models of size spectra sensitivity to discriminate between undisturbed and disturbed ecosystems and levels of environmental stress was evaluated. We have used data on benthic macroinvertebrates within 12 Mediterranean and Black Sea transitional water bodies (i.e. coastal lagoons) from Italy, Albania, Greece, Bulgaria and Romania and compared the models’ efficiency through their pressure-impact response along organic load and enrichment gradients. Data from a thirteenth Mediterranean lagoon was used for validation purposes. Asymmetric models of size class sensitivity, assuming higher sensitivity of larger body size classes, were found to be more effective than symmetric models, with higher sensitivity of less common size classes, in distinguishing undisturbed from disturbed lagoons and lagoon stations. The ISS based on the asymmetric sensitivity model that was most efficient in identifying the anthropogenic impacts also showed significant dose–response relationships along environmental parameters describing the organic load and enrichment gradients. A scheme for the classification of Ecological Quality Status based on the macroinvertebrate ISS is proposed and validated. The validation procedure found that ISS is an effective and sensitive monitoring tool, easy to apply and to inter-calibrate among laboratories. Moreover, the tests performed here over a very large ecoregional area have proved the spatial robustness of the new index. [Copyright &y& Elsevier]

Abstract: The cryopreservation of oocytes is an open problem as a result of their structural sensitivity to the freezing process. This study examined (i) the survival and meiotic competence of ovine oocytes vitrified at the GV stage with or without cumulus cells; (ii) the viability and functional status of cumulus cells after cryopreservation; (iii) the effect of cytochalasin B treatment before vitrification; (iv) chromatin and spindle organization; (v) the maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) activity of vitrified oocytes after in vitro maturation. Sheep oocytes were vitrified at different times during in vitro maturation (0, 2, and 6h) with (COCs) or without cumulus cells (DOs). After warming and in vitro maturation, oocytes denuded at 0h culture showed a significantly higher survival and meiotic maturation rate compared to the other groups. Hoechst 33342/propidium iodide double staining of COCs and microinjection of Lucifer Yellow revealed extensive cumulus cell membrane damage and reduced oocyte–cumulus cell communications after vitrification. Cytochalasin B treatment of COCs before vitrification exerted a negative effect on oocyte survival. After in vitro maturation, the number of vitrified oocytes with abnormal spindle and chromatin configuration was significantly higher compared to control oocytes, independently of the presence or absence of cumulus cells. The removal of cumulus cells combined with vitrification significantly decreased the MPF and MAPK levels. This study provides evidence that the removal of cumulus cells before vitrification enhances oocyte survival and meiotic competence, while impairing the activity of important proteins that could affect the developmental competence of oocytes. [Copyright &y& Elsevier]

Abstract: In the present study we characterize the developmental potential of prepubertal and adult ovine oocytes, analyzing the developmental speed to two-cell and blastocyst stages and its relationship with hatching from the zona pellucida, development after vitrification and the number and allocation of inner mass and trophoblastic cells. Prepubertal and adult ovine oocytes were matured and fertilized in vitro and first cleavage rates at 22, 26 and 32h were recorded. Cleaved oocytes were cultured and blastocyst production was assessed at 6–9 days post-fertilization (dpf). Blastocysts from the two sources obtained on different days were divided into two groups: the first was vitrified, warmed and cultured in vitro to evaluate re-expansion of the blastocoelic cavity; blastocysts of the second were cultured separately to allow for hatching and count of trophoblastic and inner mass cells of hatched blastocysts by differential staining. We observed a significantly lower rate (P <0.01) of cleaved prepubertal oocytes at 22 and 26h after fertilization while it was higher (P <0.01) at 32h than in the adult ones. Adult blastocyst production was significantly lower (P <0.01) in prepubertal than in adult groups and began on the seventh dpf, later (P <0.01) than in the adult group, where they appeared on the sixth dpf. Prepubertal blastocysts hatched at a lower rate than the adult ones (P <0.01) and in both experimental groups faster blastocysts showed a higher (P <0.01) hatching rate. Similarly, prepubertal derived blastocysts showed lower viability after vitrification (P <0.01) compared to the adult counterparts, and in particular slower embryos had reduced viability after vitrification compared to the fastest (P <0.01). Cell number was not different between blastocysts of both groups obtained at 6 and 7dpf, which were higher (P <0.01) than those obtained at 8 and 9dpf. The ICM/trophoblast cell ratio was similar in 6- and 7-day obtained blastocyst and increased (P <0.01) in those obtained 1 or 2 days later. These findings show that differences in kinetic development between prepubertal and adult derived embryos reflect differences in developmental capacity of the oocytes from which they derive and could be indicative of embryo quality. [Copyright &y& Elsevier]

Abstract: This report offers the results of two experiments developed to test possible benefitial effects of the presence of corpus luteum (CL) on in vivo and in vitro sheep embryo production; using two different breeds treated with two different protocols by two different teams at two different centres. In the first trial, estrus was synchronized in 11 ewes with two doses of cloprostenol, 10 days apart. On day 1 after estimated ovulation, sheep were treated with progestagen sponges and superovulated with eight decreasing doses (26.4 units NIH-FSH-S1×3, 22.0 units×2, and 17.6 units×3) of ovine FSH injected twice daily. Ovulation rate and number of embryos obtained in vivo were compared to those from 12 control ewes without cloprostenol treatment. Presence of a CL improves the number of transferable embryos (7.4±0.6 versus 4.1±0.6 in control ewes, P &#60;0.05). The second trial investigated the effects of the presence of CL on embryos produced in vitro from six ewes bearing CL and six ewes without CL at start a superovulatory treatment consisting of 96 units of ovine FSH administered in four equal doses given every 12h. There were not detected effects of the CL on the number and size of follicles or in the number, morphology and ability to resume meiosis of their oocytes. However, oocytes from ewes with CL showed higher rates of fertilization (73.5 versus 45.5%, P &#60;0.005), higher development to blastocyst (35.8 versus 19.3%, P &#60;0.01) and higher hatching rates after vitrification (80.0 versus 25.0%, P &#60;0.05). [Copyright &y& Elsevier]

The objective of the present study was to compare the developmental capacity of sheep oocytes obtained by OPU after two different ovarian stimulations, and cryotolerance to vitrification procedures of in vitro derived embryos after in vitro maturation, fertilisation and culture of these oocytes. Sheep were divided into three groups: (A) no treatment (control); (B) constant doses of FSH (FSH-c); (C) decreasing doses of FSH (FSH-d). Ovine groups FSH-c and FSH-d were synchronised by the insertion of intravaginal sponges left in situ for 7 days; FSH (total dose: 96 IU) was administered in four doses given every 12 h starting on Day 5. Twelve hours after the last FSH administration oocytes were collected by OPU technique. The control group showed a significantly lower number (P<0.05) of follicles (166) than FSH-c (294) and FSH-d (317) groups, while the number of follicles >5 mm was significantly higher (P<0.01) in FSH-d group, showing that this protocol stimulates the growth of a different follicle population compared to FSH-c group. The control group showed a higher number of <2 mm follicles (P<0.01). We did not find any difference in oocyte quality between the three groups and therefore the percentage of discarded oocytes was similar. No significant differences were found between control, FSH-c and FSH-d groups in terms of maturation (90.9, 85.7 and 87.7%, respectively) and fertilisation rates (75.2, 80.9 and 83.7%, respectively) while a significantly higher (P<0.01) blastocyst rate was observed in the FSH-c group than in the FSH-d and control groups (20.4% versus 11.8 and 13.7%, respectively). After vitrification, warming and 72 h in vitro culture, the hatching rate was significantly higher (P<0.01) in the control (87.5%) and FSH-c (90.5%) groups than in the FSH-d group (66.7%). Control and FSH-c groups showed a significantly higher (P<0.001) number of total cells than FSH-d group (217.6±26.5 and 203.0±33.2 versus 147.5±20.2), while no differences were observed in ICM cell rates in the control (35.6±3.8), FSH-c (37.1±4.6) and FSH-d (36.6±6.7) groups.These results indicate that donor sheep stimulated with FSH-c produced better quality oocytes and blastocysts showing better cryotolerance than ewes given the decreasing doses treatment. [Copyright &y& Elsevier]