299 research outputs found
Protest attitudes and stated preferences: Evidence on scale usage heterogeneity
We contribute to the stated preference literature by addressing scale usage
heterogeneity regarding how individuals answer attitudinal questions capturing
lack of trust in institutions and fairness issues. Using a latent class model, we
conduct a contingent valuation study to elicit the willingness-to-pay to preserve
a recreational site. We find evidence that respondents within the same class, that
is, with similar preferences and attitudes, interpret the Likert scale differently
when answering the attitudinal questions. We identify different patterns of
scale usage heterogeneity within and across classes and associate them with
individual characteristics. Our approach contributes to better a understanding
of individual behavior in the presence of protest attitudes
Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized study
BACKGROUND:
Mechanical ventilation is a well-known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation.
METHODS:
A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy.
RESULTS:
All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis.
CONCLUSIONS:
Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.The authors would like to thank Centro Hospitalar do Porto for funding
regarding the purchase of animals, animal food, and other husbandry
expenses. No funding was used to reimburse any of the authors, nor any of
the persons who helped and are herein thanked.
Funding for open access publication was supported by the Anesthesia
Department at Centro Hospitalar do Port
Boosting Adaptive Immunity: A New Role for PAFR Antagonists.
We have previously shown that the Platelet-Activating Factor Receptor (PAFR) engagement in murine macrophages and dendritic cells (DCs) promotes a tolerogenic phenotype reversed by PAFR-antagonists treatment in vitro. Here, we investigated whether a PAFR antagonist would modulate the immune response in vivo. Mice were subcutaneously injected with OVA or OVA with PAFR-antagonist WEB2170 on days 0 and 7. On day 14, OVA-specific IgG2a and IgG1 were measured in the serum. The presence of WEB2170 during immunization significantly increased IgG2a without affecting IgG1 levels. When WEB2170 was added to OVA in complete Freund's adjuvant, enhanced IgG2a but not IgG1 production was also observed, and CD4+ FoxP3+ T cell frequency in the spleen was reduced compared to mice immunized without the antagonist. Similar results were observed in PAFR-deficient mice, along with increased Tbet mRNA expression in the spleen. Additionally, bone marrow-derived DCs loaded with OVA were transferred into naïve mice and their splenocytes were co-cultured with fresh OVA-loaded DCs. CD4(+) T cell proliferation was higher in the group transferred with DCs treated with the PAFR-antagonist. We propose that the activation of PAFR by ligands present in the site of immunization is able to fine-tune the adaptive immune response
Redesign of machine component in polymeric matrix composite towards increased productivity
This work is focused in the maximization of the acceleration a 2D Industrial Laser Cutting Machine (ILCM). The changes to be implemented are centered in the replacement of a metallic critical component: the gantry. This component largely influences precision and maximum acceleration. Finite Elements Analysis was performed to the current metallic part. From this analysis the maximum allowed deformations were established. A replacement composite component capable of an equally valid behavior was designed in carbon fiber.
To establish the maximum increase in acceleration that does not lead to precision losses, the working conditions were simulated and the acceleration to which the component was subjected to was varied. The variation of the thickness of layers with different orientations and locations in the part allowed for the understanding of how the mass varies along with the maximum possible acceleration. This analysis, asides with considering the maximum force allowed by the linear motor that is responsible by the gantry motion, establishes the limit in terms of maximum acceleration of the machine. An increase of 22% in the maximum acceleration while maintaining the precision is possible due to the higher specific rigidity of composite materials and the use of an optimization heuristic
Redesign of an industrial laser cutting machine’s gantry in composite material
This work is focused in the design stage of a composite structure intended to replace a metallic critical component in a 2D Industrial Laser Cutting Machine (ILCM). The component is the gantry, largely responsible for most of the ILCM’s characteristics. These include precision and maximum acceleration, which are critical. The dimensioning of the component is initially performed based on analytical models, but latter stages use the numerical capabilities of Finite Elements Method. In the end it is possible to take advantage of the higher specific rigidity of composite materials to increase the maximum acceleration that the machine allows for while maintaining the precision.(undefined
Protesting or justifying? A latent class model for contingent valuation with attitudinal data
This article develops a latent class model for estimating willingness-to-pay for
public goods using simultaneously contingent valuation (CV) and attitudinal
data capturing protest attitudes related to the lack of trust in public institutions
providing those goods. A measure of the social cost associated with protest
responses and the consequent loss in potential contributions for providing the
public good is proposed. The presence of potential justification biases is further
considered, that is, the possibility that for psychological reasons the response
to the CV question affects the answers to the attitudinal questions. The results
from our empirical application suggest that psychological factors should not be
ignored in CV estimation for policy purposes, allowing for a correct identification
of protest responses
Oxygen Increases Lung Inflammatory Response in Spontaneous One-Lung Ventilation in Rabbits: A Prospective Randomized Experimental Study
Study objective: The purpose of this study was to investigate if oxygen supplementation would increase lung
inflammatory response in a spontaneous one-lung ventilation animal model, when compared to room-air oxygen
fraction.
Design: In vivo prospective randomized animal study
Setting: University research laboratory
Subjects: New Zealand rabbits
Interventions: Rabbits (n=20) were randomly assigned to 2 groups (n=10 each group). Groups (OS – Oxygen
Supplemented, and NOS – Non-Oxygen Supplemented) were submitted to spontaneous One-Lung Ventilation
(OLV) during 60 minutes; OS group had a 2-liter/minute oxygen supplement, and NOS group was kept on roomair. Ketamine/xylazine was administered for induction and maintenance of anesthesia. One-lung ventilation was
achieved by administration of air into interpleural space, and left lung collapse was visually confirmed through the
center of diaphragm. Clinical monitoring and arterial blood gas analyses were performed in all rabbits.
Measurements: Lung histology plates were observed under light microscopy for quantification of inflammatory
response (light, moderate and severe).
Main results: All subjects had at least light inflammatory response. However, rabbits submitted to oxygen
supplementation had a statistically significant value for the occurrence of moderate inflammation (p<0.001). The
inflammatory cells found were mainly eosinophils and neutrophils in an average proportion of 80/20. Oxygen partial
pressure increased in both groups with a higher proportion in OS group (p<0.001).
Conclusion: In this spontaneous OLV model, the use of oxygen supplementation was associated with a greater
inflammatory response.info:eu-repo/semantics/publishedVersio
Identifying Nonrational Behavior in Recreation Demand Models
In the context of an estimated RPL (Random Parameters Logit) choice model of recreational demand for the game reserves of the KwaZulu-Natal province in South Africa, a test on the existence of an underlying rational preference structure is presented. The proposed procedure allows to identify nonrational behavior in the sample. Using two different data sets extracted from the original data base, we show that by improving the data, apparent nonrationality can be eliminated and welfare analysis may be safely conducted.N/
Combining Averting Behavior and Contingent Valuation Data: an Application to Drinking Water Treatment
This paper is an empirical application that combines averting behavior with contingent valuation data. Consistency tests are performed incorporating alternative heteroscedastic structures in the bivariate probit models by taking advantage of the different information content that characterizes each data source. We look at three covariates not yet examined in the literature when combining stated and revealed preferred data to explain the variance in the models: income, the bid in the contingent valuation questionnaire, and the distance between the bid and the averting expenditures with drinking water. The models estimated include between and within data sources heteroscedasticity. The results obtained allow the combination of the two data sources under a common preference structure.N/
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