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1.
Although microorganisms are the primary drivers of biogeochemical cycles, the structure and functioning of microbial food webs are poorly studied. This is the case in Sphagnum peatlands, where microbial communities play a key role in the global carbon cycle. Here, we explored the structure of the microbial food web from a Sphagnum peatland by analyzing (1) the density and biomass of different microbial functional groups, (2) the natural stable isotope (δ 13C and δ 15N) signatures of key microbial consumers (testate amoebae), and (3) the digestive vacuole contents of Hyalosphenia papilio, the dominant testate amoeba species in our system. Our results showed that the feeding type of testate amoeba species (bacterivory, algivory, or both) translates into their trophic position as assessed by isotopic signatures. Our study further demonstrates, for H. papilio, the energetic benefits of mixotrophy when the density of its preferential prey is low. Overall, our results show that testate amoebae occupy different trophic levels within the microbial food web, depending on their feeding behavior, the density of their food resources, and their metabolism (i.e., mixotrophy vs. heterotrophy). Combined analyses of predation, community structure, and stable isotopes now allow the structure of microbial food webs to be more completely described, which should lead to improved models of microbial community function.  相似文献   

2.
The present work provides evidence that people assume a priori that Blacks feel less pain than do Whites. It also demonstrates that this bias is rooted in perceptions of status and the privilege (or hardship) status confers, not race per se. Archival data from the National Football League injury reports reveal that, relative to injured White players, injured Black players are deemed more likely to play in a subsequent game, possibly because people assume they feel less pain. Experiments 1–4 show that White and Black Americans–including registered nurses and nursing students–assume that Black people feel less pain than do White people. Finally, Experiments 5 and 6 provide evidence that this bias is rooted in perceptions of status, not race per se. Taken together, these data have important implications for understanding race-related biases and healthcare disparities.  相似文献   

3.
In January 2008, 10 people from three families living in Chiba and Hyogo Prefectures in Japan were found to be poisoned after eating frozen dumplings that had been imported from Tianjin, China. This incident had a big influence in the short term on Japanese consumers’ consumption choice of imported food from China as well as the willingness to pay (WTP) for food with higher safety guarantees. Using data from a Web-survey of 1500 respondents covering the whole of Japan, two regression models show that firstly, after the incident, consumers intending to buy Chinese food products reduced from 92.5% to 27.6%, and the change of purchase decision is mostly affected by consumers’ prior risk perception and attitude about Chinese products and presents a regional difference. Secondly, Japanese consumers are willing to pay 64,300 yen per year for safer food on average after the incident, and those whose purchase decision is influenced by the incident have a higher WTP of 54,000 yen than those who are not influenced. The most significant factor to decide the WTP is the framing of questions in the survey. The influence of demographic factors is less important and inconsistent in the two models.  相似文献   

4.
Farmers’ maintenance of agrobiodiversity is fundamental to global food security, particularly in a world increasingly affected by climate change. Biodiversity helps to buffer agroecosystems from stresses like climatic variability, and the crop genetic diversity conserved with biodiverse agroecosystems is critical for plant breeding both locally and globally. Yet, despite these benefits, few studies have directly assessed the implications of household–level agrobiodiversity maintenance on household food security. Drawing on survey data collected in Sri Lanka’s Hambantota District, we evaluated the plant diversity maintained by small–scale farming households in both homegardens and crop fields and determined the relationships between this diversity and their households’ food security. We also considered how a suite of additional demographic, household, community, and farm characteristics relate to both the plant diversity maintained by a household and their food security. Similar to previous studies, the age of the agricultural decision-maker and the age and size of households’ homegardens positively correlated with the overall species richness of farming systems. Older homegardens were also identified to be more evenly distributed in their species abundance, and market–oriented households had significantly higher species richness but lower Shannon Indices. Most notably, household socioeconomic status and material wealth were important to both agrobiodiversity maintenance and household food security, while no significant relationships between species richness and food security measures were detected. These findings suggest that effort aiming to increase the food security of small–scale farming households in Sri Lanka, and elsewhere, should target those farming households with a paucity of socioeconomic assets, as these households lack both agroecological and economic resources to overcome shocks, such as those associated with climate change.  相似文献   

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Sugar, salt and alum grains between 15 and 55 mg were deposited at different sites in the foraging ground of the ants Anoplolepis gracilipes and Paratrechina longicornis to study the examination processes the ants applied prior to carry these grains to the nest or refused at the site. It is revealed that, of the supplied 10 grains of these three substances A. gracilipes and P. longicornis examined only one sugar grain in most cases and two grains in few cases prior to carry a grain to the nest. Under similar situation an ant irrespective of species examined in most cases only one salt grain though few individuals examined 2 or 3 or 4 grains prior to have a decision either to carry one to the nest or to move elsewhere refusing the same at the site. Interestingly, an ant individual only in few cases examined only one alum grain but in most cases it examined 2, 3, 4 even up to all the 10 supplied alum grains scrupulously prior to refuse the same. Of the offered grain the ants procured 100 % sugar grains and 60 % salt grains from the sites to the nest while 100 % alum grains were refused at the sites following careful examination. As sugar, salt and alum grains look almost alike examination of all the alum grains was performed by the ants with a hope to get sugar grains, if any, from amongst these visually similar kinds of grains. This may be due to lack of food examination system at a precision level.  相似文献   

7.
Cities are a key system in anthropogenic phosphorus (P) cycling because they concentrate both P demand and waste production. Urban agriculture (UA) has been proposed as a means to improve P management by recycling cities’ P-rich waste back into local food production. However, we have a limited understanding of the role UA currently plays in the P cycle of cities or its potential to recycle local P waste. Using existing data combined with surveys of local UA practitioners, we quantified the role of UA in the P cycle of Montreal, Canada to explore the potential for UA to recycle local P waste. We also used existing data to complete a substance flow analysis of P flows in the overall food system of Montreal. In 2012, Montreal imported 3.5 Gg of P in food, of which 2.63 Gg ultimately accumulated in landfills, 0.36 Gg were discharged to local waters, and only 0.09 Gg were recycled through composting. We found that UA is only a small sub-system in the overall P cycle of the city, contributing just 0.44% of the P consumed as food in the city. However, within the UA system, the rate of recycling is high: 73% of inputs applied to soil were from recycled sources. While a Quebec mandate to recycle 100% of all organic waste by 2020 might increase the role of UA in P recycling, the area of land in UA is too small to accommodate all P waste produced on the island. UA may, however, be a valuable pathway to improve urban P sustainability by acting as an activity that changes residents’ relationship to, and understanding of, the food system and increases their acceptance of composting.  相似文献   

8.
Reducing non-core food advertising to children is an important priority in strategies to address childhood obesity. Public health researchers argue for government intervention on the basis that food industry self-regulation is ineffective; however, the industry contends that the existing voluntary scheme adequately addresses community concerns. This paper examines the operation of two self-regulatory initiatives governing food advertising to children in Australia, in order to determine whether these regulatory processes foster transparent and accountable self-regulation. The paper concludes that while both codes appear to establish transparency and accountability mechanisms, they do not provide for meaningful stakeholder participation in the self-regulatory scheme. Accordingly, food industry self-regulation is unlikely to reflect public health concerns or to be perceived as a legitimate form of governance by external stakeholders. If industry regulation is to remain a feasible alternative to statutory regulation, there is a strong argument for strengthening government oversight and implementing a co-regulatory scheme.  相似文献   

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10.
Wijas  Baptiste J.  Finlayson  Graeme  Letnic  Mike 《Ecosystems》2023,26(5):969-982
Ecosystems - Food webs can be conceptualized as being powered by energy derived from living and dead vegetation, respectively. Most food web research has focused on “green food webs”...  相似文献   

11.
Decision-making in socioscientific issues (SSI) constitutes a real challenge for both biology teachers and learners. The assessment of students’ performances in SSIs constitutes a problem, especially for biology teachers. The study at hand was conducted in Germany and uses a qualitative approach following the research procedures of grounded theory to focus on teachers’ concepts and, especially, coping strategies in assessment concerning students’ decision-making in SSIs. Semi-structured interviews with six teachers, in combination with video-vignettes, were used for data generation. The results show predominantly defensive strategies when teachers are confronted with the assessment of students’ performances in SSIs. These results and implications for teacher education and teacher training are discussed.  相似文献   

12.
This article measures the impact of fostering on children’s outcomes in Niger. We estimate a simultaneous equations model with three outcomes for children (school attendance, hours of market work and hours of domestic work) and a treatment variable (fostering). Nonlinearity provides identification by functional form of the causal effect of fostering. We further use information on the historical level of community integration of the child’s ethnicity and the relative importance of the ethnicity in the neighborhood to build a plausibly exogenous exclusion restriction in order to correct for the potential endogeneity of fostering. Our results sustain the overall conclusion that fostering has a positive impact on children’s school attendance and hours of domestic work. However, while foster boys and girls are both engaged in longer hours of domestic labor, only foster boys are advantaged in terms of schooling.  相似文献   

13.
The aim of the study was to describe, categorise and analyse students’ (aged 14–16) processes of scientific inquiry in biology and chemistry education. Therefore, a theoretical structure for scientific inquiry for both biology and chemistry, the VerE model, was developed. This model consists of nine epistemological acts, which combine processes of scientific thinking and inquiry methods. Based on the theoretical structure, a paper-and-pencil test was developed to investigate the students’ abilities in the acts of scientific inquiry. Each of the nine acts was operationalised to generate multiple-choice items. For each act, ten items were constructed. In total, ninety items per subject were tested in a field study to evaluate their psychometric quality. The article focuses on the outcomes for testing in biology. In biology, 537 students were tested with a paper-and-pencil test, following a multi-matrix design in which each student solved twenty-seven items. Data from 260 students have been analysed so far. Seventy-five items showed satisfactory item characteristics. The distribution of the items’ difficulties fits the students’ abilities appropriately. We conclude that theory-driven epistemological acts can be operationalised in tasks that assess students’ abilities in scientific inquiry.  相似文献   

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Animals typically must make a number of successive choices to achieve a goal: e.g., eating multiple food items before becoming satiated. However, it is unclear whether choosing the best first or saving the best for last represents the best choice strategy to maximize overall reward. Specifically, since outcomes can be evaluated prospectively (with future rewards discounted and more immediate rewards preferred) or retrospectively (with prior rewards discounted and more recent rewards preferred), the conditions under which each are used remains unclear. On the one hand, humans and non-human animals clearly discount future reward, preferring immediate rewards to delayed ones, suggesting prospective evaluation; on the other hand, it has also been shown that a sequence that ends well, i.e., with the best event or item last, is often preferred, suggesting retrospective evaluation. Here we hypothesized that when individuals are allowed to build the sequence themselves they are more likely to evaluate each item individually and therefore build a sequence using prospective evaluation. We examined the relationship between self-generated choice order and preference in rhesus monkeys in two experiments in which the distinctiveness of options were relatively high and low, respectively. We observed a positive linear relationship between choice order and preference among highly distinct options, indicating that the rhesus monkeys chose their preferred food first: i.e., a peak-first order preference. Overall, choice order depended on the degree of relative preference among alternatives and a peak-first bias, providing evidence for prospective evaluation when choice order is self-generated.  相似文献   

16.

Background

Lifestyle, dietary patterns and nutritional status of organic food consumers have rarely been described, while interest for a sustainable diet is markedly increasing.

Methods

Consumer attitude and frequency of use of 18 organic products were assessed in 54,311 adult participants in the Nutrinet-Santé cohort. Cluster analysis was performed to identify behaviors associated with organic product consumption. Socio-demographic characteristics, food consumption and nutrient intake across clusters are provided. Cross-sectional association with overweight/obesity was estimated using polytomous logistic regression.

Results

Five clusters were identified: 3 clusters of non-consumers whose reasons differed, occasional (OCOP, 51%) and regular (RCOP, 14%) organic product consumers. RCOP were more highly educated and physically active than other clusters. They also exhibited dietary patterns that included more plant foods and less sweet and alcoholic beverages, processed meat or milk. Their nutrient intake profiles (fatty acids, most minerals and vitamins, fibers) were healthier and they more closely adhered to dietary guidelines. In multivariate models (after accounting for confounders, including level of adherence to nutritional guidelines), compared to those not interested in organic products, RCOP participants showed a markedly lower probability of overweight (excluding obesity) (25≤body mass index<30) and obesity (body mass index ≥30): −36% and −62% in men and −42% and −48% in women, respectively (P<0.0001). OCOP participants (%) generally showed intermediate figures.

Conclusions

Regular consumers of organic products, a sizeable group in our sample, exhibit specific socio-demographic characteristics, and an overall healthy profile which should be accounted for in further studies analyzing organic food intake and health markers.  相似文献   

17.
The problem of providing mandated medical care has become commonplace as correctional systems in the United States struggle to manage unprecedented increases in its aging prison population. This study explores older incarcerated women’s perceptions of prison health care policies and their day-to-day survival experiences. Aggregate data obtained from a sample of 327 older women (mean age?=?56) residing in prison facilities in five Southern states were used to identify a baseline of health conditions and needs for this vulnerable group. With an average of 4.2 chronic health conditions, frequently histories of victimization, and high rates of mental health issues, the women’s experiences of negotiating health care was particularly challenging. By incorporating the voices of older women, we expose the contradictions, dilemmas, and obstacles they experience in their attempts to obtain health care. It is clear from the personal accounts shared that, despite court mandates, penal harm practices such as delaying or denying medical treatment as well as occasional staff indifferences are common in women’s prisons. With older women having the greatest need for health care, an age- and gender-sensitive approach is recommended.  相似文献   

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This article analyzes Dutch consumers’ willingness to pay (WTP) for the welfare of broiler chickens and the consequences for nonhuman animal welfare policies. Using data from a discrete-choice experiment and a random parameter logit model, this study showed that consumers particularly value opportunities for outdoor access and the method used for anesthesia before slaughter. The WTP was also positively related to the number of consumers buying the same product, indicating that they experience the public-good dilemma. Moreover, the WTP was higher if consumers knew that animal welfare practices were subject to public or collective supervision. Women, people with more education, those with higher income, and nonreligious people had relatively high WTP values. For 87.5% of the respondents, the WTP exceeded the price difference between a broiler with a higher level of animal welfare and a regular chicken. The findings suggest that the Dutch market for broiler chickens can be improved by raising consumer confidence in the labeling system.  相似文献   

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