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1.
Cogn Emot ; 37(1): 18-33, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36331080

RESUMO

A meta-analytic review of studies that experimentally elicited awe and compared the emotion to other conditions (84; 487 effects; 17,801 participants) examined the degree to which experimentally elicited awe (1) affects outcomes relative to other positive emotions (2) affects experience, judgment, behaviour, and physiology, and (3) differs in its effects if the awe state was elicited through positive or threatening contexts. The efficacy of methods that have been used to experimentally elicit awe and the possibility of assessing changes in the state of the self with experimental awe elicitations were also examined. Meta-analyses with robust variance estimation revealed that awe affected outcomes compared to other positive emotions and control conditions; affected experience, judgment, and behaviour; and had similar effects if elicited through positive or threatening contexts. The ability to compare awe to negative emotion states and its effects on physiology was limited by a small number of available effects. Images, videos, autobiographical recall, and naturalistic exposure were effective in eliciting awe. Exploratory analyses suggested that some processes involved in changes in the self can be related to experimental awe elicitations. These findings suggest awe is a discrete emotion and identifies areas for future investigation.


Assuntos
Emoções , Julgamento , Humanos , Emoções/fisiologia
2.
Molecules ; 28(17)2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37687162

RESUMO

Visualization of the chemical space is useful in many aspects of chemistry, including compound library design, diversity analysis, and exploring structure-property relationships, to name a few. Examples of notable research areas where the visualization of chemical space has strong applications are drug discovery and natural product research. However, the sheer volume of even comparatively small sub-sections of chemical space implies that we need to use approximations at the time of navigating through chemical space. ChemMaps is a visualization methodology that approximates the distribution of compounds in large datasets based on the selection of satellite compounds that yield a similar mapping of the whole dataset when principal component analysis on a similarity matrix is performed. Here, we show how the recently proposed extended similarity indices can help find regions that are relevant to sample satellites and reduce the amount of high-dimensional data needed to describe a library's chemical space.

3.
J Public Health Manag Pract ; 29(6): 775-779, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37738595

RESUMO

People experiencing homelessness are disproportionately affected by infectious diseases and often face barriers to receiving appropriate medical treatment. Responding to the needs of people experiencing homelessness requires state and local health departments to integrate information sources and coordinate multisector efforts. From 2021 to 2023, the CDC Foundation, in cooperation with the Centers for Disease Control and Prevention, established pilot Centers of Excellence in Public Health and Homelessness in Seattle, Washington; San Francisco, California; and the state of Minnesota. These centers strengthened their capacity to address the needs of people experiencing homelessness by supporting cross-sector partnerships, assessing the interoperability of data systems, prioritizing infectious disease needs, and identifying health disparities. These programs demonstrated that health departments are heterogeneous entities with differing resources and priorities. They also showed the importance of employing dedicated public health staff focused on homelessness, establishing diverse partnerships and the need for support from local leaders to address homelessness.


Assuntos
Doenças Transmissíveis , Pessoas Mal Alojadas , Humanos , Saúde Pública , Problemas Sociais , Washington
4.
Nicotine Tob Res ; 23(1): 63-70, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-32123908

RESUMO

INTRODUCTION: Smoke-free homes (SFHs), the voluntary adoption of home smoking restrictions, are associated with reduced secondhand smoke exposure. However, SFHs are uncommon in permanent supportive housing (PSH) for formerly homeless adults, who have fivefold higher smoking rates than the general population. We pilot-tested a brief intervention to increase voluntary adoption of SFHs among PSH residents in the San Francisco Bay Area. AIMS AND METHODS: We pilot-tested a brief intervention to increase voluntary adoption of SFHs among PSH residents in the San Francisco Bay Area. Rest of the methods, PSH residents (n = 100) and staff (n = 62) from 15 PSH sites participated in the intervention between October 2017 and February 2018. Research staff provided counseling to PSH residents on how to adopt an SFH and trained PSH staff on how to counsel residents on smoking cessation. The primary outcome was self-reported voluntary adoption of an SFH for ≥90 days, and the secondary outcome was carbon monoxide-verified PPA at 6-month follow-up. PSH staff completed the Smoking Knowledge, Attitudes, and Practices survey at baseline and 3-month follow-up. RESULTS: At 6 months, 31.3% of PSH residents had adopted an SFH (vs. 13.0% at baseline) and 16.9% reported carbon monoxide-verified PPA. A positive attitude toward an SFH policy was associated with increased odds of SFH adoption (adjusted odds ratio = 8.68, 95% confidence interval: 2.42, 31.17). Voluntary SFH adoption was associated with increased PPA (adjusted odds ratio = 26.27, 95% confidence interval: 3.43, 201.30). PSH staff reported improved attitudes toward and self-efficacy in delivering cessation care, and decreased barriers to discussing smoking cessation among PSH residents between baseline and 3-month follow-up. CONCLUSIONS: In this single-arm study, a brief intervention increased SFH adoption and PPA among PSH residents. IMPLICATIONS: To date, few interventions have addressed SFHs and their association with tobacco use among PSH residents. A "ground-up" approach that relies on buy-in from residents and that promotes voluntary SFHs is an innovative way to increase smoke-free living environments in PSH. This approach could pave a pathway for smoke-free policy implementation in these sites. PSH can play a role in reducing the burden of tobacco use by empowering its residents to adopt voluntary SFHs, which could increase smoking cessation among residents.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Habitação Popular/estatística & dados numéricos , Política Antifumo/legislação & jurisprudência , Abandono do Hábito de Fumar/psicologia , Poluição por Fumaça de Tabaco/prevenção & controle , Uso de Tabaco/epidemiologia , Idoso , Intervenção Médica Precoce , Emigrantes e Imigrantes/psicologia , Feminino , Pessoas Mal Alojadas/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , São Francisco/epidemiologia , Inquéritos e Questionários , Poluição por Fumaça de Tabaco/estatística & dados numéricos
5.
Memory ; 28(1): 128-140, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31762377

RESUMO

People rely on predicted and remembered emotion to guide important decisions. But how much can they trust their mental representations of emotion to be accurate, and how much do they trust them? In this investigation, participants (N = 957) reported their predicted, experienced, and remembered emotional response to the outcome of the 2016 U.S. presidential election. They also reported how accurate and vivid they perceived their predictions and memories to be, and the importance of the election. Participants remembered their emotional responses more accurately than they predicted them. But, strikingly, they perceived their predictions to be more accurate than their memories. This perception was explained by the greater importance and vividness of anticipated versus remembered experience. We also assessed whether individuals with Highly Superior Autobiographical Memory for personal and public events (N = 33) showed superior ability to predict or remember their emotional responses to events. They did not and, even for this group, predicting emotion was a more intense experience than remembering emotion. These findings reveal asymmetries in the phenomenological experience of predicting and remembering emotion. The vividness of predicted emotion serves as a powerful subjective signal of accuracy even when predictions turn out to be wrong.


Assuntos
Emoções/fisiologia , Memória Episódica , Rememoração Mental/fisiologia , Confiança , Adulto , Feminino , Humanos , Masculino , Política , Inquéritos e Questionários
6.
Behav Brain Sci ; 40: e242, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-29122016

RESUMO

Contempt shares its features with other emotions, indicating that there is no justification for creating "sentiment" as a new category of feelings. Scientific categories must be created or updated on the basis of evidence. Building a new category on the currently limited contempt literature would be akin to building a house on sand - likely to fall at any moment.


Assuntos
Asco , Emoções , Atitude
7.
bioRxiv ; 2024 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-39149242

RESUMO

The widespread use of Machine Learning (ML) techniques in chemical applications has come with the pressing need to analyze extremely large molecular libraries. In particular, clustering remains one of the most common tools to dissect the chemical space. Unfortunately, most current approaches present unfavorable time and memory scaling, which makes them unsuitable to handle million- and billion-sized sets. Here, we propose to bypass these problems with a time- and memory-efficient clustering algorithm, BitBIRCH. This method uses a tree structure similar to the one found in the Balanced Iterative Reducing and Clustering using Hierarchies (BIRCH) algorithm to ensure O N time scaling. BitBIRCH leverages the instant similarity (iSIM) formalism to process binary fingerprints, allowing the use of Tanimoto similarity, and reducing memory requirements. Our tests show that BitBIRCH is already > 1,000 times faster than standard implementations of the Taylor-Butina clustering for libraries with 1,500,000 molecules. BitBIRCH increases efficiency without compromising the quality of the resulting clusters. We explore strategies to handle large sets, which we applied in the clustering of one billion molecules under 5 hours using a parallel/iterative BitBIRCH approximation.

8.
BMJ Open ; 14(9): e088303, 2024 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-39266319

RESUMO

OBJECTIVES: Cancer is a leading cause of death in unhoused adults. We sought to examine the association between housing status, stage at diagnosis and all-cause survival following cancer diagnosis at a public hospital. DESIGN: Retrospective cohort study examining new cancer diagnoses between 1 July 2011 and 30 June 2021. SETTING: A public hospital in San Francisco. EXPOSURE: Housing status (housed, formerly unhoused, unhoused) was ascertained via a county-wide integrated dataset that tracks both observed and reported homelessness. METHODS: We reported univariate analyses to investigate differences in demographic and clinical characteristics by housing group. We then constructed Kaplan-Meier curves stratified by housing group to examine unadjusted all-cause mortality. Finally, we used multivariable Cox proportional hazards models to compare the hazard rate of mortality for each housing status group, adjusting for demographic and clinical factors. RESULTS: Our cohort included 5123 patients with new cancer diagnoses, with 4062 (79%) in housed patients, 623 (12%) in formerly unhoused patients and 438 (9%) in unhoused patients. Unhoused and formerly unhoused patients were more commonly diagnosed with stage 4 disease (28% and 27% of the time, respectively, vs 22% of housed patients). After adjusting for demographic and clinical characteristics, unhoused patients with stage 0-3 disease had a 50% increased hazard of death (adjusted HR (aHR) 1.5, 95% CI 1.1 to 1.9; p<0.004) as did formerly unhoused patients (aHR 1.5, 95% CI 1.2 to 1.9; p=0.001) compared with housed individuals 3 months after diagnosis. CONCLUSIONS: Unhoused and formerly unhoused patients diagnosed with non-metastatic cancer had substantially increased hazards of death compared with housed patients cared for in a public hospital setting. Current or former lack of housing could contribute to poor outcomes following cancer diagnoses via multiple mechanisms.


Assuntos
Hospitais Públicos , Habitação , Pessoas Mal Alojadas , Neoplasias , Humanos , Feminino , Masculino , Estudos Retrospectivos , Neoplasias/diagnóstico , Neoplasias/mortalidade , Neoplasias/terapia , Pessoa de Meia-Idade , Hospitais Públicos/estatística & dados numéricos , São Francisco/epidemiologia , Pessoas Mal Alojadas/estatística & dados numéricos , Idoso , Adulto , Modelos de Riscos Proporcionais , Estimativa de Kaplan-Meier
9.
Digit Discov ; 3(6): 1160-1171, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38873032

RESUMO

The quantification of molecular similarity has been present since the beginning of cheminformatics. Although several similarity indices and molecular representations have been reported, all of them ultimately reduce to the calculation of molecular similarities of only two objects at a time. Hence, to obtain the average similarity of a set of molecules, all the pairwise comparisons need to be computed, which demands a quadratic scaling in the number of computational resources. Here we propose an exact alternative to this problem: iSIM (instant similarity). iSIM performs comparisons of multiple molecules at the same time and yields the same value as the average pairwise comparisons of molecules represented by binary fingerprints and real-value descriptors. In this work, we introduce the mathematical framework and several applications of iSIM in chemical sampling, visualization, diversity selection, and clustering.

10.
JAMA Netw Open ; 5(10): e2239076, 2022 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-36306131

RESUMO

Importance: Although the general US population had fewer emergency department (ED) visits during the COVID-19 pandemic, patterns of use among high users are unknown. Objectives: To examine natural trends in ED visits among high users of health and social services during an extended period and assess whether these trends differed during COVID-19. Design, Setting, and Participants: This retrospective cohort study combined data from 9 unique cohorts, 1 for each fiscal year (July 1 to June 30) from 2012 to 2021, and used mixed-effects, negative binomial regression to model ED visits over time and assess ED use among the top 5% of high users of multiple systems during COVID-19. Data were obtained from the Coordinated Care Management System, a San Francisco Department of Public Health platform that integrates medical and social information with service use. Exposures: Fiscal year 2020 was defined as the COVID-19 year. Main Outcomes and Measures: Measured variables were age, gender, language, race and ethnicity, homelessness, insurance status, jail health encounters, mental health and substance use diagnoses, and mortality. The main outcome was annual mean ED visit counts. Incidence rate ratios (IRRs) were used to describe changes in ED visit rates both over time and in COVID-19 vs non-COVID-19 years. Results: Of the 8967 participants, 3289 (36.7%) identified as White, 3005 (33.5%) as Black, and 1513 (16.9%) as Latinx; and 7932 (88.5%) preferred English. The mean (SD) age was 46.7 (14.2) years, 6071 (67.7%) identified as men, and 7042 (78.5%) had experienced homelessness. A statistically significant decrease was found in annual mean ED visits among high users for every year of follow-up until year 8, with the largest decrease occurring in the first year of follow-up (IRR, 0.41; 95% CI, 0.40-0.43). However, during the pandemic, ED visits decreased 25% beyond the mean reduction seen in prepandemic years (IRR, 0.75; 95% CI, 0.72-0.79). Conclusions and Relevance: In this study, multiple cohorts of the top 5% of high users of multiple health care systems in San Francisco had sustained annual decreases in ED visits from 2012 to 2021, with significantly greater decreases during COVID-19. Further research is needed to elucidate pandemic-specific factors associated with these findings and understand how this change in use was associated with health outcomes.


Assuntos
COVID-19 , Masculino , Humanos , Pessoa de Meia-Idade , COVID-19/epidemiologia , Pandemias , Estudos Retrospectivos , Serviço Hospitalar de Emergência , Atenção à Saúde , Serviço Social
11.
Emotion ; 21(6): 1213-1223, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33646801

RESUMO

The present investigation examined the potential benefits and costs of optimistic expectations about future events through the lens of error management theory (EMT). Decades of evidence have shown that optimism about the likelihood of future events is pervasive and difficult to correct. From an EMT perspective, this perpetuation of inaccurate beliefs is possible because optimism offers benefits greater than the costs. The present investigation examined this possibility for controllable important life events with a known time at which they would occur. College students taking their first exam (n = 1,061) and medical students being matched with residency placements (n = 182) reported their expectations and emotions weeks before the event and their responses after they knew the outcome of the event. Optimistic expectations predicted the quality of effort investment before an event occurred-students were more satisfied with their studying, medical students were more satisfied with their decision making, and optimism predicted better performance. Optimistic expectations also predicted less emotional distress before the event. There was no evidence that optimistic expectations related to longer-term greater distress when participants experienced an unexpected negative outcome; the valence of the outcome itself predicted distress. These results are consistent with the EMT-derived hypothesis that optimistic expectations have benefits for effort and emotion before an event occurs, with little cost after the outcome occurs. (PsycInfo Database Record (c) 2021 APA, all rights reserved).


Assuntos
Emoções , Motivação , Humanos , Otimismo , Satisfação Pessoal , Estudantes
12.
J Pers Soc Psychol ; 116(5): 724-742, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30604985

RESUMO

People try to make decisions that will improve their lives and make them happy, and to do so, they rely on affective forecasts-predictions about how future outcomes will make them feel. Decades of research suggest that people are poor at predicting how they will feel and that they commonly overestimate the impact that future events will have on their emotions. Recent work reveals considerable variability in forecasting accuracy. This investigation tested a model of affective forecasting that captures this variability in bias by differentiating emotional intensity, emotional frequency, and mood. Two field studies examined affective forecasting in college students receiving grades on a midterm exam (Study 1, N = 643), and U.S. citizens after the outcome of the 2016 presidential election (Study 2, N = 706). Consistent with the proposed model, participants were more accurate in forecasting the intensity of their emotion and less accurate in forecasting emotion frequency and mood. Overestimation of the effect of the event on mood increased over time since the event. Three experimental studies examined mechanisms that contribute to differential forecasting accuracy. Biases in forecasting intensity were caused by changes in perceived event importance; biases in forecasting frequency of emotion were caused by changes in the frequency of thinking about the event. This is the first direct evidence mapping out strengths and weaknesses for different types of affective forecasts and the factors that contribute to this pattern. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Tomada de Decisões , Emoções , Política , Estudantes/psicologia , Adolescente , Adulto , Afeto , Feminino , Felicidade , Humanos , Masculino , Estados Unidos , Adulto Jovem
13.
Emotion ; 19(1): 1-9, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29494200

RESUMO

This investigation examined predictors of changes over time in subjective well-being (SWB) after the 2016 United States presidential election. Two indicators of SWB-general happiness and life satisfaction-were assessed three weeks before the election, the week of the election, three weeks later, and six months later. Partisanship predicted both indicators of SWB, with Trump supporters experiencing improved SWB after the election, Clinton supporters experiencing worsened SWB after the election, and those who viewed both candidates as bad also experiencing worsened SWB after the election. The impact of the election on SWB decreased over time, with all participants returning to baseline life satisfaction six months after the election. Trump supporters and those who viewed both candidates as bad for the country also returned to baseline general happiness six months after the election. Clinton supporters, in contrast, remained below baseline levels of general happiness six months after the election. Moral and political values, and exposure to media inconsistent with those values, predicted lasting change in subjective well-being. National events can affect how people perceive the overall quality of their lives and these effects are exacerbated when moral and political values are involved. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Emoções , Política , Feminino , Felicidade , História do Século XXI , Humanos , Masculino , Estados Unidos
14.
Salud UNINORTE ; 39(1)abr. 2023.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1536831

RESUMO

COVID-19 has changed educational opportunities for students around the world, and, in the process, affected their lifestyle, happiness, and engagement. The present research is part of a project from six universities in different countries across Latin America to examine the impact of COVID-19 on university students. Objectives: The purpose of this study was to assess and compare the impact of COVID-19 on lifestyle changes, orientations to happiness, and student engagement among a sample of college students in Mexico, El Salvador, Colombia, the Dominican Republic, Peru, and the US. Methods: Participants were 1764 students from the six previously identified countries. Data were collected using the Student Health Behavior Inventory, the Orientations to Happiness Scale, and the University Student Engagement Inventory. Results: Student respondents were mostly female, with a median age of 22. Most reported no changes in academic performance and statistically significant changes in some lifestyle behaviors such as nutrition and physical activity. Conclusions: The global pandemic led to behavioral changes among college students in Latin America, and it affected their orientations to happiness and engagement. Institutions of higher learning are called to create opportunities for their students to reintegrate into an in-person learning environment to facilitate positive lifestyle changes for their students.


El COVID-19 ha cambiado las oportunidades educativas para los estudiantes de todo el mundo y en el proceso afectó su estilo de vida, felicidad y compromiso. La presente investigación es parte de un proyecto de seis universidades en diferentes países de América Latina para determinar el impacto de COVID-19 en estudiantes universitarios. Objetivos: El propósito de este estudio fue evaluar y comparar el impacto del COVID-19 en los cambios de estilo de vida, las orientaciones hacia la felicidad y el compromiso de los estudiantes entre una muestra de estudiantes universitarios en México, El Salvador, Colombia, República Dominicana, Perú y Estados Unidos. Métodos: Los participantes fueron 1764 estudiantes de los seis países previamente identificados. Los datos se recolectaron utilizando el Inventario de Conducta de Salud del Estudiante, la Escala de Orientaciones a la Felicidad y el Inventario de Participación de los Estudiantes Universitarios. Resultados. Los estudiantes encuestados eran en su mayoría mujeres con una edad promedio de 22 años. La mayoría informó que no hubo cambios en el rendimiento académico y cambios estadísticamente significativos en algunos comportamientos de estilo de vida, como la nutrición y la actividad física. Conclusiones: La pandemia global provocó cambios de comportamiento entre los estudiantes universitarios de América Latina y afectó sus orientaciones hacia la felicidad y su compromiso. Las instituciones de educación superior están llamadas a crear oportunidades para que sus estudiantes se reintegren en un entorno de aprendizaje en persona para facilitar cambios positivos en el estilo de vida de sus estudiantes.

15.
Environ Toxicol Chem ; 36(2): 449-462, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27442751

RESUMO

Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was impaired. Second, the presence of source, stressor, and effect were established. Then linkages between source, stressor, and effect were developed. This allows identification of probable stressors adversely affecting the waterbody. Three pollutant categories were assessed: chemicals, nutrients, and suspended sediments. This weight of evidence approach indicated that Greenwich Bay was primarily impacted by eutrophication-related stressors. The sediments of Greenwich Bay were carbon enriched and low dissolved oxygen concentrations were commonly seen, especially in the western portions of Greenwich Bay. The benthic community was depauperate, as would be expected under oxygen stress. Although our analysis indicated that contaminant loads in Greenwich Bay were at concentrations where adverse effects might be expected, no toxicity was observed, as a result of high levels of organic carbon in these sediments reducing contaminant bioavailability. Our analysis also indicated that suspended sediment impacts were likely nonexistent for much of the Bay. This analysis demonstrates that the diagnostic procedure was useful to organize and assess the potential stressors impacting the ecological well-being of Greenwich Bay. This diagnostic procedure is useful for management of waterbodies impacted by multiple stressors. Environ Toxicol Chem 2017;36:449-462. © 2016 SETAC.


Assuntos
Baías/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Invertebrados/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Eutrofização , Sedimentos Geológicos/análise , Rhode Island , Urbanização , Poluentes Químicos da Água/análise
16.
Neumol. pediátr. (En línea) ; 15(1): 267-269, Mar. 2020. ilus
Artigo em Inglês | LILACS | ID: biblio-1088095

RESUMO

Presenting the case of a previously healthy eleven-year-old girl, diagnosed with septic arthritis of the left knee as a result of stabbing trauma, which subsequently develops respiratory distress and fever. Septic pulmonary embolism is diagnosed radiologically and by pathological study. Receive adequate antibiotic treatment, recovering completely. Septic pulmonary embolism, although frequently described in the adult population, is a condition rarely described in pediatric literature.


Se presenta el caso de una niña de once años previamente sana, con diagnóstico de artritis séptica de rodilla izquierda como resultado de un traumatismo punzante, que posteriormente desarrolla dificultad respiratoria y fiebre. Se diagnostica embolia pulmonar séptica documentada radiológicamente y por estudio anatomopatológico. Recibe tratamiento antibiótico adecuado, recuperándose completamente. La embolia pulmonar séptica, aunque frecuentemente descrita en población adulta, es una condición raramente descrita en la literatura pediátrica.


Assuntos
Humanos , Feminino , Criança , Embolia Pulmonar/etiologia , Artrite Infecciosa/complicações , Embolia Pulmonar/tratamento farmacológico , Embolia Pulmonar/diagnóstico por imagem , Radiografia Torácica , Tomografia Computadorizada por Raios X , Sepse , Antibacterianos/uso terapêutico
17.
Ecol Appl ; 1(3): 237-248, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27755773

RESUMO

Three different sizes of marine microcosms were used to study the influence of two features of spatial scale on the chemical fate and ecological effects of the pesticide Kepone. Increasing the size of microcosms reduced the ratio of wall surface area to volume of contained sea water, but increased the number of benthic species due to increasing sample size. Other features of spatial scale, such as water turbulence, water turnover, etc., were held constant. Intact water-column and benthic communities from a north-temperate marine system were coupled together in 9.1-, 35.0-, and 140.O-L containers. Kepone at 20.4 nmol/L was added to these microcosm systems over a 30-d period. A 3 x 2 factorial design was used to discern the effects of size and Kepone. In the absence of Kepone the phytoplankton community exhibited excessive growth relative to the field system for all system sizes. Growth was directly related to the size of microcosms. In addition, the time required to achieve maximum algal biomass was also directly related to size. Release of a growth-stimulating compound(s) from fouling organisms settling on the microcosm walls and size-dependent increases in benthic species provided the best explanation for the observed phytoplankton dynamics. Addition of Kepone indirectly increased phytoplankton densities by reducing through toxic effects, the grazing pressure of zooplankton. Because this effect and mechanism was dependent upon the size of the system, the sensitivity of future perturbation studies may be enhanced by producing similar or related variations in system size. The concentration of Kepone in surficial sediments was also size dependent. Since the average concentrations of Kepone in all water columns were statistically equivalent, these findings were the result of sediment bioturbation coupled with preferential partitioning of Kepone from liquid to the solid, organic phase of sediments. Ecological risk assessments based upon data derived from these systems are therefore dependent upon size. Furthermore, the smaller the size, the greater the underestimate in sediment exposure and the ecological risks of Kepone.

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