696 research outputs found
Growth enhancement of benthic diatoms for industrial applications
Este resumo faz parte de: Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010. A versão completa do livro de atas está disponível em: http://hdl.handle.net/1822/1096
Assessment of aquatic toxicity with Tetrahymena pyriformis : alternatives to the growth impairment assays
The negative effects of failed service recoveries
Research has shown that more than half of attempted recovery efforts fail, producing a "double deviation" effect. Surprisingly, these double deviation effects have received little attention in marketing literature. This paper examines what happens after these critical encounters, which behavior or set of behaviors the customers are prone to follow and how customers' perceptions of the firm's recovery efforts influence these behaviors. For the analysis of choice of the type of response (complaining, exit, complaining and exit, and no-switching), we estimate multinomial Logit models with random coefficients (RCL). The results of our study show that magnitude of service failure, explanations, apologies, perceived justice, angry and frustration felt by the customer, and satisfaction with service recovery have a significant effect on customers' choice of the type of response. Implications from the findings are offered. La investigación ha mostrado que más de la mitad de los intentos de recuperación tras el fallo de un servicio fracasan, lo que produce un efecto de "desviación doble". Sorprendentemente, estos efectos de desviación doble han recibido muy poca atención en la literatura de marketing. Este trabajo analiza qué ocurre tras estos encuentros críticos, ¿qué comportamiento o conjunto de comportamientos tienden a seguir lo clientes? y ¿cómo afectan a estos comportamientos las percepciones de los clientes acerca del problema y de los esfuerzos de recuperación de la empresa?. Para el análisis del tipo de respuesta (queja, abandono, queja y abandono, y no cambiar de entidad), estimamos modelos Logit multinomiales con coeficientes aleatorios (RCL). Los resultados de nuestro estudio muestran que la magnitud del fallo inicial, las explicaciones y disculpas recibidas tras el mismo, la justicia percibida en la gestión de la queja, la frustración y el enfado que siente el cliente y la satisfacción con el proceso de recuperación, tienen un efecto significativo en la elección de los clientes del tipo de respuesta de queja. Finalmente, se ofrecen implicaciones para la gestión.desviación doble, comportamiento de queja del consumidor, modelos Logit multinomiales con coeficientes aleatorios (RCL), recuperación del servicio. Double deviations, consumer complaining behavior (CCB), multinomial logit models with random coefficients (RCL), service recovery.
Physiological responses of Tetrahymena pyriformis to copper, zinc, cycloheximide and Triton X-100
Protozoa, and particularly ciliates, are essential in aerobic purification processes of wastewaters and have proved to be very
sensitive to environmental changes. The physiological response of the ciliate Tetrahymena pyriformis was assessed in terms of
mortality, growth and grazing capacity after exposure to four toxicants: copper, zinc, cycloheximide and Triton X-100. In the
ranges of concentrations used, mortality, inhibition of growth and inhibition of grazing were observed with all toxicants
employed, but in different ways. Copper and zinc showed lower toxicity than observed in other studies with protozoa, though
some of the present results are in accordance with those reported by other authors. This supports the importance of the
organism tested and the experimental conditions of the bioassays.Instituto de Biotecnologia e Química Fina (IBQF).Fundação para a Ciência e a Tecnologia (FCT) - Praxis XXI - 2/2.1/BIO/1118/95, Praxis XXI - grant BD/5080/95
Prevalência da violência contra as pessoas idosas: uma revisão crítica da literatura
Os estudos de prevalência sobre a violência contra as pessoas idosas, em contexto familiar, desenvolvidos nas três últimas décadas, especialmente na Europa e países anglo-saxónicos, não são suficientemente esclarecedores, por insuficiências na definição dos modelos teóricos e nos conceitos operatórios. Neste artigo de revisão sistemática da literatura identifica-se a diversidade de definições e desenhos de investigação, com impacto inevitável nas variações das estimativas. Também a perceção da opinião pública europeia sobre o problema colide com os baixos valores estimados. Procurar-se-á refletir sobre as razões subjacentes a essas representações e refletir criticamente sobre as estimativas dos estudos de prevalência de base populacional.Fundação para a Ciência e Tecnologi
Tracking relations among bacterial and protozoan communities in wastewater treatment plants
Background: Understanding the interactions between prokaryotic and eukaryotic populations in complex environments can be challenging. Particularly, there is a recognized difficulty in establishing how the interactions between the bacterial and the protozoan populations can affect the performance of wastewater treatment plants (WWTP).
Objectives: In order to determine the relationships between microbial communities (protozoa, metazoa and filamentous bacteria) and abiotic parameters (physical-chemical and operational), thirty seven WWTP with activated sludge process were studied in Portugal, during two years, in a trimestral sampling strategy.
Methods: Samples were collected to enable a molecular characterization of the microbiota. In order to ensure the diversity of microorganisms, 100 samples were selected based on their geographic localization and time-spaced to track relationships within bacteria and protozoa. A 16S rRNA gene PCR-DGGE approach was carried out for bacterial community fingerprinting. The resulting profiles were analysed together with the results obtained from the survey of the protozoa populations. Finally, the study of the correlations between the physical-chemical and operational parameters and the microbial communities was also investigated.
Conclusions: The study of these interactions constitutes a strategy for the understanding of how the different metabolic groups of prokaryotic and protozoa are affected by the relations between this populations, allowing a better prediction of the overall community dynamics. This will allow setting the conditions that better contribute to improve the wastewater treatment while increasing the knowledge of overall communities networking in complex environments
Profiling of pathogenic bacteria by colony morphology – identification of potential biofilm resistance and virulence determinants
Colony morphology changes may be an indicator of the phenotypic variations associated to
the pathogenecity, virulence and antimicrobial resistance of infection-causing
microorganisms. Particularly, phenotypic changes derived from biofilm growth and in
response to environmental stressors. For instance, in patients with cystic fibrosis, P.
aeruginosa colony morphology undergoes a conversion from non- to mucoid form
augmenting bacteria resistance to antibiotics considerably. However, the specific correlation
between some colony traits and the biological impact is unknown.
This study was thus designed to inspect the colony associated phenotypic alterations,
particularly the putative virulence determinants of biofilm-colonies, via morphological
observation and whole cell MALDI MS proteomics. The annotation of colony morphology
features was supported by a novel, in-house developed ontology, named colony morphology
ontology (CMO), and annotations are available at the MorphoColDB framework [1]. The
considerable diversity of the morphotypes observed within and across species, with diferente
biofilm-forming abilities and susceptibilities [2], led to the application of this method in support
of the identification of virulent morphotypes as primary therapeutic candidates. Further
results on the protein expression of P. aeruginosa and S. aureus colonies confirmed
important differences between intra-species morphotypes and has promoted investigation of
the role of stress-regulated proteins.
Although preliminary, these results confirm the potential of using a combination of
highthroughput screening of pathogenic bacteria proteome with susceptibility tests and
expert inputs to reach a comprehensive understanding of the persistence and antimicrobial
resistance of pathogenic bacteria, as well as to design new therapeutic strategies
Interactions between eukaryotic and prokaryotic microorganisms in activated sludge: a molecular approach to improve wastewater treatment
Wastewater treatment is one of the most important
biotechnological processes which are used worldwide to
treat municipal and industrial sewage. Activated-sludge
processes aim to achieve a maximal reduction of the
Biological Oxygen Demand (BOD) of wastewater with
a minimal production of biological solids. Even though
many microbiological methods are available to study
the activated sludge communities, many recent
questions on the role of certain microorganisms are kept
unanswered. A crucial addressed by the present work is
to know if the presence of different groups of bacteria
and protozoa lead to significant consequences on the
process performance. Focusing on the importance of the
interactions between the prokaryotic and the eukaryotic
populations, the work will contribute to the knowledge
of how microbial communities are established in a
complex environment as the activated sludge processes
Trends in the use of protozoa in the assessment of wastewater treatment
Increasing environmental pollution and the continuous development of new chemicals and drugs has led to
ever growing concern about the potential effects of these compounds directly or indirectly on human health. As concerns
water pollution, protozoa seem to be an excellent tool to assess both toxicity and pollution: they are regarded as biological
indicators of pollution when their presence or absence can be related to particular environmental conditions, and they
are considered test organisms when a species or population is used to evaluate the toxicity of relevant toxic compounds.
Thus, an integrated approach is being developed to assess how toxic compounds affect the different biological levels of
organisation – from the community level to the species level – of ciliated protozoa. The present paper reports and discusses
the current state of the art of this approach.Instituto de Biotecnologia e Química Fina (IBQF).
Fundação para a Ciência e a Tecnologia - PRAXIS XXI-2/2.1/BIO/1118/95, PRAXIS XXI/BD/5080/95, PRAXIS XXI/BD/20328/99
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