Does shell shape variation play a role in conservation of the long‐lived freshwater bivalve Diplodon chilensis (Bivalvia, Hyriidae)?

Freshwater bivalves of the order Unionoida display an uncommon phenotypic plasticity with high interpopulation and intrapopulation morphological variability, which could be advantageous for coping with habitat modifications. However, unionoids have suffered a marked population decline in different parts of the world in the last decades. A decline in some populations of the South American long‐lived freshwater mussel Diplodon chilensis as a consequence of habitat deterioration has recently been recorded. Ontogenetic allometry and shape variation in shells of D. chilensis from 2 different sites, Paimun lake and Chimehuin river, North Patagonia, Argentina, have been studied. For these purposes, geometric morphometric methods were used. Shell shape shows differences between sites, which the shells from Chimehuin river show less intrapopulation variability; are more elongated, with the anterior part extended upwards and the posterior part downwards; and show a steeper anterior curvature at the umbo compared to those from Paimún lake. These characteristics make shell shape more streamlined to withstand river current. Furthermore, the extended posterior‐ventral part in river shells coincides with higher foot weight that would improve anchoring to the river rocky–sandy substrate. River shells present a bounded eco‐morphotype whereas the higher variability of lake shells includes the “river eco‐morphotype.” Growth is allometric throughout life in both sites and is not sex‐dependent. The success of river repopulation programmes using mussels from lake populations may be increased by transplanting selected individuals that show “river eco‐morphotype.

Method effects associated with negatively and positively worded items on the 12-item General Health Questionnaire (GHQ-12) : results from a cross-sectional survey with a representative sample of Catalonian workers

This study focused on the examination of the latent structure underlying the responses to the GHQ-12, considering the role of method effects associated with both, PW and NW items, and using two alternative parameterisations of the CFA measurement models. What should first be noted is that the studies that have included method effects in the measurement model of the GHQ-12 have been more the exception than the rule in previous research into the factor structure of this questionnaire. According to the results of the present study, we conclude that the GHQ-12 factor structure is best characterised by introducing latent method factors that capture both the method effects associated with NW and PW items (model 7). These results support the conclusion from previous research that the good fit obtained by multidimensional models (mainly the two-factor model and the three-factor Graetz's model) could simply be explained by the artificial grouping of PW and NW items. However, the interpretation of the latent (method) factors as purely integrating method bias due to wording is not straightforward. It is obvious that NW and PW items share the wording. It is also clear that this three bifactor model (one trait and two method factors) fitted the data best. And finally, there is a lot of empirical evidence on these wording effects. However, it is also relevant to discuss the large loadings of many items on the method factors, being these loadings sometimes larger than their loadings in the trait factor. The general factor explains a 52% of the shared variance, but there are some items that deserve careful attention. For example, items 3 ('playing useful part in things') and 4 ('capable of making decisions') had very low loadings on the trait factor. If we understand PW method factor as the only method bias, then it follows that these two items are purely method effects, but surely they must share some trait variance. In the same vein, items 10 ('losing confidence in yourself') and 11 ('thinking of yourself as a worthless person') load very high in the NW method factor and, as a reviewer pointed out, a likely (post-hoc) explanation is that wording bias are still confounded with a confidence/self-image factor. Therefore, the interpretation of these effects as purely method and, accordingly, the interpretation of an overall score for the scale difficult may be compromised. The second aim of this study was to examine the relationship between the method factors associated with both NW and PW items and three demographic variables, namely sex, age and educational level of the respondents. Regarding the sex, we found a statistically significant, but weak, relationship between PW and sex, so that men were more likely than women to endorse PW items. These results are in line with previous works that, in the context of RSES, have found sex differences in wording effects. 56 57 As for the explanatory role of age on method effects, we found that the relationship between age and the NW effect was not statistically significant, which supports previous research using other questionnaires (eg, self-esteem scales, 50 Hospital Anxiety & Depression Scale 64). Moreover, our results give support to previous studies which had stated that, in older adults, the strongest method effects would be associated with PW items, rather than NW items. 55 58 As to the educational level, we found that there was not a significant correlation of this variable on the two method factors. This result supports and extends the evidence obtained in Tomás et al 50 who found that the educational level of the respondents had no effect on the negative method factor using self-esteem questionnaires. This results contradicts previous research on the relationship of the NW factor and the educational level/verbal ability with different questionnaires and samples. 41 64-69 Overall, the significant effects of sex and age on trait and method factors point out that women have a worse well-being, but this effect is partly modified by a method effect on the PW items, whereas the results for age suggest that older respondents have worse well-being and this effect is magnified by a method effect on the PW factor. The results on the individual differences related to the demographic variables considered in this study cannot only help to understand the presence of wording method effects but also to identify respondents who are prone to answering PW and NW items differently. In this sense, the relationship that appears as more evident is for the age and sex variables. Another practical consequence of our study concerns the relationship between the intended measure of the GHQ-12 (ie, the GPH factor) and other constructs of interest. Several studies have shown that method effects can inflate, deflate or have no effect at all on estimates of the relationship between two constructs (see Podsakoff et al 70 for a further review of the effects that method biases have on individual measures and on the covariation between different constructs). Thus, it is desirable that both the constructs of interest as well as the effects of method factors, like PW and NW, are considered in SEM models as a means of controlling these systematic sources of bias, and thus avoiding the drawing of inaccurate conclusions about the relationship between the substantive factors. Previous research on the GHQ-12 31 36 has outlined the asymmetry in the participants' responses as a function of the wording of the items, as well as the different responses scales for the PW and NW items. This asymmetry in the participants' responses as a function of the wording of the items is consistent with results from previous research into wording effects for contrastive survey questions. 71 The extent to which the presence of method effects is linked to the asymmetric pattern of responses and/or to the different response scales for the PW and NW items in the GHQ-12 should be examined in future research. Comparing the current work with previous studies into the factorial structure of the GHQ-12, to our knowledge, this is the first study that tests a comprehensive set of models including method effects associated with both PW and NW items and also explores some demographic correlates of these method effects. Another strength of this work was the fact that it used a large representative sample of workers, but the results might not be generalised to other specific populations, for example, adolescents and elderly retired people. Twitter @jmlosilla, @VivesJ_Research Contributors All authors meet the criteria recommended by the International Committee of Medical Journal Editors (ICMJE). All authors made substantial contributions to conception and design, acquisition of data or analysis and interpretation of data. MFR and JGM: drafted the article. JV and JML: critically revised the draft for important intellectual content. JMT: worked in the statistical analysis and interpretation of data. All authors agreed on the final version. Funding This work was supported by the Grant PGC2018-100675-B-I00, Spanish Ministry of Science, Innovation and Universities (Spain). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. Disclaimer All authors have agreed to authorship in the indicated order. All authors declare that this paper is an original unpublished work and it is not being submitted elsewhere. All authors do not have any financial interests that might be interpreted as influencing the research, and APA ethical standard were followed in the conduct of the study. Competing interests None declared. Patient consent for publication Not required. Ethics approval The research was not submitted to approval by an institutional review board since this is not a requirement at our universities for this type of study. Ethics approval was not sought for this study since this was a secondary analysis of anonymised data. Provenance and peer review Not commissioned; externally peer reviewed. Data availability statement Data are available upon reasonable request.Objective Recent studies into the factorial structure of the 12-item version of the General Health Questionnaire (GHQ-12) have shown that it was best represented by a single substantive factor when method effects associated with negatively worded (NW) items are considered. The purpose of the present study was to examine the presence of method effects, and their relationships with demographic covariates, associated with positively worded (PW) and/or NW items. Design A cross-sectional, observational study to compare a comprehensive set of confirmatory factor models, including method effects associated with PW and/or NW items with GHQ-12 responses. Setting Representative sample of all employees living in Catalonia (Spain). Participants 3050 participants (44.6% women) who responded the Second Catalonian Survey of Working Conditions. Results A confirmatory factor analysis showed that the best fitting model was a unidimensional model with two additional uncorrelated method factors associated with PW and NW items. Furthermore, structural equation modelling (SEM) revealed that method effects were differentially related to both the sex and age of the respondents. Conclusion Individual differences related to sex and age can help to identify respondents who are prone to answering PW and NW items differently. Consequently, it is desirable that both the constructs of interest as well as the effects of method factors are considered in SEM models as a means of avoiding the drawing of inaccurate conclusions about the relationships between the substantive factors

Wastewater treatment using microalgae: how realistic a contribution might it be to significant urban wastewater treatment?

Microalgae have been proposed as an option for wastewater treatment since the 1960’s but still this technology has not been expanded to an industrial scale. In this paper, the major factors limiting the performance of these systems are analysed. The composition of the wastewater is highly relevant, and especially the presence of pollutants such as heavy metals and emerging compounds. Biological and engineering aspects are also critical and have to be improved to at least approximate the performance of conventional systems, not just in terms of capacity and efficiency but also in terms of robustness. Finally, the harvesting of the biomass and its processing into valuable products poses a challenge; yet at the same time, an opportunity exists to increase economic profitability. Land requirement is a major bottleneck that can be ameliorated by improving the system’s photosynthetic efficiency. Land requirement has a significant impact on the economic balance but the profits from the biomass produced can enhance these systems’ reliability, especially in small cities

Human Exposure to Endocrine-Disrupting Chemicals and Prenatal Risk Factors for Cryptorchidism and Hypospadias: A Nested Case–Control Study

BACKGROUND: Exposure to xenoestrogens during pregnancy may disturb the development and function of male sexual organs. OBJECTIVE: In this study we aimed to determine whether the combined effect of environmental estrogens measured as total effective xenoestrogen burden (TEXB) is a risk factor for male urogenital malformations. METHODS: In a case-control study, nested in a mother-child cohort (n = 702) established at Granada University Hospital, we compared 50 newborns with diagnosis of cryptorchidism and/or hypospadias with 114 boys without malformations matched by gestational age, date of birth, and parity. Controls did not differ from the total cohort in confounding variables. TEXB and levels of 16 organochlorine pesticides were measured in placenta tissues. Characteristics of parents, pregnancy, and birth were gathered by questionnaire. We used conditional and unconditional regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: TEXB from organohalogenated compounds was detectable in 72% and 54% of case and control placentas, respectively. Compared with controls, cases had an OR for detectable versus non-detectable TEXB of 2.82 (95% CI, 1.10-7.24). More pesticides were detected in cases than in controls (9.34 +/- 3.19 vs. 6.97 +/- 3.93). ORs for cases with detectable levels of pesticides, after adjusting for potential confounders in the conditional regression analysis, were o,p'-DDT (OR = 2.25; 95% CI, 1.03-4.89), p,p'-DDT (OR = 2.63; 95% CI, 1.21-5.72), lindane (OR = 3.38; 95% CI, 1.36-8.38), mirex (OR = 2.85; 95% CI, 1.22-6.66), and endosulfan alpha (OR = 2.19; 95% CI, 0.99-4.82). Engagement of mothers in agriculture (OR = 3.47; 95% CI, 1.33-9.03), fathers' occupational exposure to xenoestrogens (OR = 2.98; 95% CI, 1.11-8.01), and history of previous stillbirths (OR = 4.20; 95% CI, 1.11-16.66) were also associated with risk of malformations. CONCLUSIONS: We found an increased risk for male urogenital malformations related to the combined effect of environmental estrogens in placenta

Abdominal tuberculosis in Ecuador, a problem that is still not solved

Tuberculosis (TB) in the gastrointestinal tract or peritoneum is an uncommon condition in clinical practice. Its rarity, combined with its nonspecific presentations, makes this kind of extrapulmonary tuberculosis difficult to diagnose as it can mimic other inflammatory or malignant conditions. Delays in treatment and frequent misdiagnosis can lead to hazardous complications. In countries like Ecuador where the disease is endemic, TB should always be considered in the differential diagnosis of a patients who present with nonspecific abdominal symptoms. In these scenarios, laparoscopy can be an invaluable tool when used with sufficiently high clinical awareness and adequate training. Case presentation: We present the case of a 37-year-old female patient from Ecuador with a 1-year history of abdominal pain, nausea, intermittent vomits, night sweats, and weight loss. After clinical evaluation and a laparoscopic intervention, abdominal TB was detected and promptly treated. Antituberculosis chemotherapy was initiated, and the patient successfully recovered. Conclusions: High clinical awareness is imperative when approaching abdominal TB due to its wide spectrum of clinical symptoms and its rarity. Early detection and prompt treatment are critical to minimize the possibility of hazardous complications