1,951 research outputs found
Testing for variation in Leptasterias spp. prey preference across different populations and microhabitats
Sea star wasting disease (SSWD) has affected many asteroid populations on the Pacific Northwest coast in recent years. Because sea stars are keystone predators, the absence of them can severely alter the structure of intertidal communities. As populations diminish, it is important to understand what the preferred prey of sea stars is and how prey preference may affect distribution and abundance of sea stars. This laboratory study examined the prey preference of Leptasterias populations from Friday Harbor, Washington, Humboldt County, California, and Pigeon Point, California. The purpose of the study was to 1) determine if sea stars have a preferred prey type, 2) determine if there is a difference in prey preference across different populations, and 3) determine if there is a difference in prey preference between sea stars of different microhabitats (i.e. in pools or attached to rocks within the intertidal). To assess this, multiple binary choice trials were conducted in which sea stars were offered different prey types of equal accessibility. Preference was determined by calculating the average position of sea stars in an experimental tank. Preliminary observations suggest that there is a difference in prey preference between stars of different populations and microhabitats, however statistical analyses are needed at this time. Future studies are necessary that include larger sample sizes, a more controlled laboratory environment, and field-based experiments and observations
Ethics in Archaeological Lidar
Airborne laser scanning or lidar has now been used by archaeologists for twenty years, with many of the first applications relying on data acquired by public agencies seeking to establish baseline elevation maps, mainly in Europe and North America. More recently, several wide-area acquisitions have been designed and commissioned by archaeologists, the most extensive of which cover tropical forest environments in the Americas and Southeast Asia. In these regions, the ability of lidar to map microtopographic relief and reveal anthropogenic traces on the Earth’s surface, even beneath dense vegetation, has been welcomed by many as a transformational breakthrough in our field of research. Nevertheless, applications of the method have attracted a measure of criticism and controversy, and the impact and significance of lidar are still debated. Now that wide-area, high-density laser scanning is becoming a standard part of many archaeologists’ toolkits, it is an opportune moment to reflect on its position in contemporary archaeological practice and to move towards a code of ethics that is vital for scientific research. The papers in this Special Collection draw on experiences with using lidar in archaeological research programs, not only to highlight the new insights that derive from it but also to cast a critical eye on past practices and to assess what challenges and opportunities remain for developing codes of ethics. Using examples from a range of countries and environments, contributions revolve around three key themes: data management and access; the role of stakeholders; and public education. We draw on our collective experiences to propose a range of improvements in how we collect, use, and share lidar data, and we argue that as lidar acquisitions mature we are well positioned to produce ethical, impactful, and reproducible research using the technique
Do Complexity Measures of Frontal EEG Distinguish Loss of Consciousness in Geriatric Patients Under Anesthesia?
While geriatric patients have a high likelihood of requiring anesthesia, they carry an increased risk for adverse cognitive outcomes from its use. Previous work suggests this could be mitigated by better intraoperative monitoring using indexes defined by several processed electroencephalogram (EEG) measures. Unfortunately, inconsistencies between patients and anesthetic agents in current analysis techniques have limited the adoption of EEG as standard of care. In attempts to identify new analyses that discriminate clinically-relevant anesthesia timepoints, we tested 1/f frequency scaling as well as measures of complexity from nonlinear dynamics. Specifically, we tested whether analyses that characterize time-delayed embeddings, correlation dimension (CD), phase-space geometric analysis, and multiscale entropy (MSE) capture loss-of-consciousness changes in EEG activity. We performed these analyses on EEG activity collected from a traditionally hard-to-monitor patient population: geriatric patients on beta-adrenergic blockade who were anesthetized using a combination of fentanyl and propofol. We compared these analyses to traditional frequency-derived measures to test how well they discriminated EEG states before and after loss of response to verbal stimuli. We found spectral changes similar to those reported previously during loss of response. We also found significant changes in 1/f frequency scaling. Additionally, we found that our phase-space geometric characterization of time-delayed embeddings showed significant differences before and after loss of response, as did measures of MSE. Our results suggest that our new spectral and complexity measures are capable of capturing subtle differences in EEG activity with anesthesia administration-differences which future work may reveal to improve geriatric patient monitoring
Do adults with high functioning autism or Asperger Syndrome differ in empathy and emotion recognition?
The present study examined whether adults with high functioning autism (HFA) showed greater difficulties in (i) their self-reported ability to empathise with others and/or (ii) their ability to read mental states in others’ eyes than adults with Asperger syndrome (AS). The Empathy Quotient (EQ) and ‘Reading the Mind in the Eyes’ Test (Eyes Test) were compared in 43 adults with AS and 43 adults with HFA. No significant difference was observed on EQ score between groups, while adults with AS performed significantly better on the Eyes Test than those with HFA. This suggests that adults with HFA may need more support, particularly in mentalizing and complex emotion recognition, and raises questions about the existence of subgroups within autism spectrum conditions
Lipid Droplet and Peroxisome Biogenesis: Do They Go Hand-in-Hand?
All eukaryotic cells contain membrane bound structures called organelles. Each organelle has specific composition and function. Some of the organelles are generated de novo in a cell. The endoplasmic reticulum (ER) is a major contributor of proteins and membranes for most of the organelles. In this mini review, we discuss de novo biogenesis of two such organelles, peroxisomes and lipid droplets (LDs), that are formed in the ER membrane. LDs and peroxisomes are highly conserved ubiquitously present membrane-bound organelles. Both these organelles play vital roles in lipid metabolism and human health. Here, we discuss the current understanding of de novo biogenesis of LDs and peroxisomes, recent advances on how biogenesis of both the organelles might be linked, physical interaction between LDs and peroxisomes and other organelles, and their physiological importance
Brief report: how adolescents with ASD process social information in complex scenes. Combining evidence from eye movements and verbal descriptions
We investigated attention, encoding and processing of social aspects of complex photographic scenes. Twenty-four high-functioning adolescents (aged 11–16) with ASD and 24 typically developing matched control participants viewed and then described a series of scenes, each containing a person. Analyses of eye movements and verbal descriptions provided converging evidence that both groups displayed general interest in the person in each scene but the salience of the person was reduced for the ASD participants. Nevertheless, the verbal descriptions revealed that participants with ASD frequently processed the observed person’s emotion or mental state without prompting. They also often mentioned eye-gaze direction, and there was evidence from eye movements and verbal descriptions that gaze was followed accurately. The combination of evidence from eye movements and verbal descriptions provides a rich insight into the way stimuli are processed overall. The merits of using these methods within the same paradigm are discussed
Vegetation Controls on Weathering Intensity During the Last Deglacial Transition in Southeast Africa
Tropical climate is rapidly changing, but the effects of these changes on the geosphere are unknown, despite a likelihood of climatically-induced changes on weathering and erosion. The lack of long, continuous paleo-records prevents an examination of terrestrial responses to climate change with sufficient detail to answer questions about how systems behaved in the past and may alter in the future. We use high-resolution records of pollen, clay mineralogy, and particle size from a drill core from Lake Malawi, southeast Africa, to examine atmosphere-biosphere-geosphere interactions during the last deglaciation (~ 18-9 ka), a period of dramatic temperature and hydrologic changes. The results demonstrate that climatic controls on Lake Malawi vegetation are critically important to weathering processes and erosion patterns during the deglaciation. At 18 ka, afromontane forests dominated but were progressively replaced by tropical seasonal forest, as summer rainfall increased. Despite indication of decreased rainfall, drought-intolerant forest persisted through the Younger Dryas (YD) resulting from a shorter dry season. Following the YD, an intensified summer monsoon and increased rainfall seasonality were coeval with forest decline and expansion of drought-tolerant miombo woodland. Clay minerals closely track the vegetation record, with high ratios of kaolinite to smectite (K/S) indicating heavy leaching when forest predominates, despite variable rainfall. In the early Holocene, when rainfall and temperature increased (effective moisture remained low), open woodlands expansion resulted in decreased K/S, suggesting a reduction in chemical weathering intensity. Terrigenous sediment mass accumulation rates also increased, suggesting critical linkages among open vegetation and erosion during intervals of enhanced summer rainfall. This study shows a strong, direct influence of vegetation composition on weathering intensity in the tropics. As climate change will likely impact this interplay between the biosphere and geosphere, tropical landscape change could lead to deleterious effects on soil and water quality in regions with little infrastructure for mitigation
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Sedentary and Physically Active Behavior Patterns Among Low-Income African-American and White Adults Living in the Southeastern United States
Increased sedentary behavior and lack of physical activity are associated with increased risk for many chronic diseases. Differences in leisure-time physical activity between African American and white adults have been suggested to partially explain racial disparities in chronic disease outcomes, but expanding the definition of physical activity to include household and occupational activities may reduce or even eliminate racial differences in total physical activity. The objective of this study was to describe patterns of active and sedentary behaviors in black and white adults and to examine these behaviors across demographic measures. Sedentary and physically active behaviors were obtained from a validated physical activity questionnaire in 23,021 black men, 9,899 white men, 32,214 black women, and 15,425 white women (age 40–79) at enrollment into the Southern Community Cohort Study. Descriptive statistics for sedentary time; light, moderate, and vigorous household/occupational activity; sports/exercise; total activity; and meeting current physical activity recommendations via sports/exercise were examined for each race-sex group. Adjusted means were calculated using multiple linear regression models across demographic measures. Study participants spent approximately 60% of waking time in sedentary behaviors. Blacks reported more television viewing time than whites (45 minutes for females, 15 minutes for males), but when sitting time was expressed as a proportion of overall awake time, minimal racial differences were found. Patterns of light, moderate, and vigorous household/occupational activity were similar in all race/sex groups. 2008 Physical Activity Guidelines for Americans were followed by 16% of women and 25% of men independent of race. Overall, black and white men and women in this study spent the majority of their daily time in sedentary behaviors and less than one-fourth followed current guidelines for physical activity. These results indicate that public health campaigns should focus on both reducing sedentary behavior and increasing physical activity in all adult US populations
Trends in Availability and Prices of Subsidized ACT over the First Year of the AMFm: Evidence from Remote Regions of Tanzania
Background: The Affordable Medicines Facility for malaria (AMFm) is a pilot supra-national subsidy program that aims to increase access and affordability of artemisinin combination therapy (ACT) in public sector clinics and private retail shops. It is unclear to what extent the AMFm model will translate into wide scale availability and price reductions in ACT, particularly for rural, remote areas where disparities in access to medicines often exist. This study is the first to rigorously examine the availability and price of subsidized ACT during the first year of the AMFm, measured through retail audits in remote regions of Tanzania. Methods: Periodic retail audits of Accredited Drug Dispensing Outlets (ADDOs) were conducted in two remote regions of Tanzania (Mtwara and Rukwa). Temporal and spatial variation in ACT availability and pricing were explored. A composite measure of ADDO remoteness, using variables, such as distance to suppliers and towns, altitude and population density, was used to explore whether ACT availability and price vary systematically with remoteness. Results: Between February 2011 and January 2012, the fraction of ADDOs stocking AMFm-ACT increased from 25% to 88% in Mtwara and from 3% to 62% in Rukwa. Availability was widespread, though diffusion throughout the region was achieved more quickly in Mtwara. No significant relationship was found between ACT availability and remoteness. Adult doses of AMFm-ACT were much more widely available than any other age/weight band. Average prices fell from 1529 TZS (1.03 USD) to 1272 TZS (0.81 USD) over the study period, with prices in Rukwa higher than Mtwara. The government recommended retail price for AMFm- ACT is 1,000 TZS ($0.64 USD). The median retail ACT price in the final round of data collection was 1,000 TZS. Conclusions: The AMFm led to large increases in availability of low priced ACT in Tanzania, with no significant variation in availability based on remoteness. Availability did remain lower and prices remained higher in Rukwa, which is a more remote region overall. Low availability of child and adolescent ACT doses could be due in part to lower quantities of non-adult packs imported into Tanzania. Future research will explore whether increased availability and affordability persists and whether it translates into higher ACT use in Tanzania
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