353 research outputs found

    The Nesting Ecology of Bumblebees

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    Bumblebees have undergone dramatic declines both in Britain and further afield during the last century. Bumblebees provide a crucial pollination service to both crops and wild flowers. For these reasons, they have received a great deal of research attention over the years. However, the ecology of wild bumblebee nests and the interactions between nests and other species, particularly vertebrates has been somewhat understudied. This is largely due to the difficulty in finding sufficient nests for well replicated study and a lack of appropriate methods of observation. Here, methods for locating bumblebee nests were trialled. It was found that a specially trained bumblebee nest detection dog did not discover nests any faster than people who had received minimal instruction. Numbers of nest site searching queens provide a reliable indication of suitable nesting habitat (i.e. places where nests are more likely to be found). In order to investigate aspects of bumblebee nesting ecology wild nests were observed by filming or regular observations by either researchers or members of the public. Some buff-tailed bumblebee (Bombus terrestris) nests were collected and all the bumblebees were genotyped to identify any foreign individuals. A review of British mammalian dietary literature was conducted to identify those that predate bumblebees. Great tits (Parus major) were filmed predating bumblebees at nests and it was clear from the literature and observations that badger (Meles meles), pine martens (Martes martes) and hedgehogs (Erinaceus europaeus) predate bumblebee nests, as well as the wax moth (Aphomia sociella). No evidence for predation by any other vertebrate species was found. Behaviours recorded included parasitism by Psithyrus, apparent nectar theft and possible usurpation by true bumblebees, egg-dumping by foreign queens and drifting and drifter reproduction by foreign workers. These events may cause harm to colonies (for example, through horizontal transmission of pathogens, or exploitation of the host nest’s resources). Alternatively where for example, usurpation by true bumblebees, egg-dumping or drifting is successful, these alternative reproductive strategies may increase the effective population size by enabling a single nest to produce reproductives of more than one breeding female. These data found that wild buff-tailed bumblebees (B. terrestris) nests with a greater proportion of workers infected with Crithidia bombi were less likely to produce gynes than those with fewer infected workers. Gyne production also varied dramatically between years. There is a growing body of evidence that a class of frequently used insecticides called neonicotinoids are negatively impacting bumblebees. An experiment was conducted using commercial colonies of buff-tailed bumblebees (B. terrestris) which were fed pollen and nectar which had been treated with the neonicotinoid imidacloprid at field realistic, sub-lethal levels. Treated colonies, produced 85-90% fewer gynes than control colonies. If this trend is representative of natural nests feeding on treated crops, for example, oilseed rape and field beans or garden flowers, then this would be expected to cause dramatic population declines. In this thesis methods for locating bumblebee nests have been tested, new behaviours have been identified (for example, egg-dumping by queens and predation by great tits) and estimations for rates of fecundity and destruction by various factors have been provided. Doubt has been cast over the status of some mammals as predators of bumblebee nests and estimates for gyne production, nest longevity, etc, have been given. More work is needed, especially observations of incipient nests as this is when the greatest losses are thought to occur

    Understanding Sexual Consent Among Adolescents

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    Background: Sexual consent remains one of the most important tools in the prevention of sexual violence, for which adolescents are an especially vulnerable group. However, it is unclear how sexual consent processes are defined and used by this population. To bridge this gap in knowledge, we present a protocol for a forthcoming scoping review that will identify and synthesize the available empirical research findings on sexual consent conceptualizations and processes among adolescents. Methods/Design: Using the framework by Arksey and O’Malley (2005), a systematic search of six academic databases (Education Source, ERIC, Gender Studies Database, PsycINFO, Social Services Abstracts, and Sociological Abstracts) will be conducted; this range has been selected due to the multi-disciplinary nature of sexual consent research. Following two levels of screening, data from the full-text articles will be charted and subjected to qualitative thematic analysis. Discussion: These collated results will provide a map of key concepts and establish gaps in the extant literature in order to guide future research on this topic. The findings will advance our knowledge of sexual consent as it is understood by the adolescent population; they may also inform the content and delivery of sexual education programs to ensure that they are relevant to their target audience and assist in the prevention of sexual violence

    Micro-Ramp Flow Control for Oblique Shock Interactions: Comparisons of Computational and Experimental Data

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    Computational fluid dynamics was used to study the effectiveness of micro-ramp vortex generators to control oblique shock boundary layer interactions. Simulations were based on experiments previously conducted in the 15- by 15-cm supersonic wind tunnel at the NASA Glenn Research Center. Four micro-ramp geometries were tested at Mach 2.0 varying the height, chord length, and spanwise spacing between micro-ramps. The overall flow field was examined. Additionally, key parameters such as boundary-layer displacement thickness, momentum thickness and incompressible shape factor were also examined. The computational results predicted the effects of the microramps well, including the trends for the impact that the devices had on the shock boundary layer interaction. However, computing the shock boundary layer interaction itself proved to be problematic since the calculations predicted more pronounced adverse effects on the boundary layer due to the shock than were seen in the experiment

    Case Report: An MRI Traumatic Brain Injury Longitudinal Case Study at 7 Tesla: Pre- and Post-injury Structural Network and Volumetric Reorganization and Recovery.

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    Importance: A significant limitation of many neuroimaging studies examining mild traumatic brain injury (mTBI) is the unavailability of pre-injury data. Objective: We therefore aimed to utilize pre-injury ultra-high field brain MRI and compare a collection of neuroimaging metrics pre- and post-injury to determine mTBI related changes and evaluate the enhanced sensitivity of high-resolution MRI. Design: In the present case study, we leveraged multi-modal 7 Tesla MRI data acquired at two timepoints prior to mTBI (23 and 12 months prior to injury), and at two timepoints post-injury (2 weeks and 8 months after injury) to examine how a right parietal bone impact affects gross brain structure, subcortical volumetrics, microstructural order, and connectivity. Setting: This research was carried out as a case investigation at a single primary care site. Participants: The case participant was a 38-year-old female selected for inclusion based on a mTBI where a right parietal impact was sustained. Main outcomes: The main outcome measurements of this investigation were high spatial resolution structural brain metrics including volumetric assessment and connection density of the white matter connectome. Results: At the first scan timepoint post-injury, the cortical gray matter and cerebral white matter in both hemispheres appeared to be volumetrically reduced compared to the pre-injury and subsequent post-injury scans. Connectomes produced from whole-brain diffusion-weighted probabilistic tractography showed a widespread decrease in connectivity after trauma when comparing mean post-injury and mean pre-injury connection densities. Findings of reduced fractional anisotropy in the cerebral white matter of both hemispheres at post-injury time point 1 supports reduced connection density at a microstructural level. Trauma-related alterations to whole-brain connection density were markedly reduced at the final scan timepoint, consistent with symptom resolution. Conclusions and Relevance: This case study investigates the structural effects of traumatic brain injury for the first time using pre-injury and post-injury 7 Tesla MRI longitudinal data. We report findings of initial volumetric changes, decreased structural connectivity and reduced microstructural order that appear to return to baseline 8 months post-injury, demonstrating in-depth metrics of physiological recovery. Default mode, salience, occipital, and executive function network alterations reflect patient-reported hypersomnolence, reduced cognitive processing speed and dizziness

    Decolonizing Data Visualization: A History and Future of Indigenous Data Visualization

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    On the whole, the field of data visualization is white. Contemporary views of historical data visualization tend to trace back to a few iconic visuals tied to European wars and conquests. The modern explosion of the field has been centered around the ideas of white men, as if they invented data visualization. Yet, Indigenous populations world-wide have been incorporating data visualization into their record keeping for centuries before anyone had heard of Edward Tufte. In this article, three Indigenous evaluators (Mohican/Munsee, Cherokee, and Tlingit) along with a non-Indigenous co-conspirator, will discuss their journeys creating space to weave together Western notions of data visualization best practices and Indigenous ways of knowing and storytelling. The authors focus their evaluative work on the support of Indigenous communities and will reflect on what has worked in communicating data, what hasn't, and how far data visualization has to go in all four directions

    Prior history of traumatic brain injury among persons in the Traumatic Brain Injury Model Systems National Database

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    OBJECTIVE: To determine the association between demographic, psychosocial, and injury-related characteristics and traumatic brain injury (TBI) occurring prior to a moderate or severe TBI requiring rehabilitation. DESIGN: Secondary data analysis. SETTING: TBI Model System inpatient rehabilitation facilities. PARTICIPANTS: Persons (N=4464) 1, 2, 5, 10, 15, or 20 years after TBI resulting in participation in the TBI Model System National Database. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: History of TBI prior to the TBI Model System Index injury, pre-Index injury demographic and behavioral characteristics, Index injury characteristics, post-Index injury behavioral health and global outcome. RESULTS: Twenty percent of the cohort experienced TBIs preceding the TBI Model System Index injury-80% of these were mild and 40% occurred before age 16. Pre- and post-Index injury behavioral issues, especially substance abuse, were highly associated with having had a prior TBI. Greater severity of the pre-Index injury as well as occurrence before age 6 often showed stronger associations. Unexpectedly, pre-Index TBI was associated with less severe Index injuries and better functioning on admission and discharge from rehabilitation. CONCLUSIONS: Findings suggest that earlier life TBI may have important implications for rehabilitation after subsequent TBI, especially for anticipating behavioral health issues in the chronic stage of recovery. Results provide additional evidence for the potential consequences of early life TBI, even if mild

    Bone marrow stromal cells from multiple myeloma patients uniquely induce bortezomib resistant NF-κB activity in myeloma cells

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    <p>Abstract</p> <p>Background</p> <p>Components of the microenvironment such as bone marrow stromal cells (BMSCs) are well known to support multiple myeloma (MM) disease progression and resistance to chemotherapy including the proteasome inhibitor bortezomib. However, functional distinctions between BMSCs in MM patients and those in disease-free marrow are not completely understood. We and other investigators have recently reported that NF-κB activity in primary MM cells is largely resistant to the proteasome inhibitor bortezomib, and that further enhancement of NF-κB by BMSCs is similarly resistant to bortezomib and may mediate resistance to this therapy. The mediating factor(s) of this bortezomib-resistant NF-κB activity is induced by BMSCs is not currently understood.</p> <p>Results</p> <p>Here we report that BMSCs specifically derived from MM patients are capable of further activating bortezomib-resistant NF-κB activity in MM cells. This induced activity is mediated by soluble proteinaceous factors secreted by MM BMSCs. Among the multiple factors evaluated, interleukin-8 was secreted by BMSCs from MM patients at significantly higher levels compared to those from non-MM sources, and we found that IL-8 contributes to BMSC-induced NF-κB activity.</p> <p>Conclusions</p> <p>BMSCs from MM patients uniquely enhance constitutive NF-κB activity in MM cells via a proteinaceous secreted factor in part in conjunction with IL-8. Since NF-κB is known to potentiate MM cell survival and confer resistance to drugs including bortezomib, further identification of the NF-κB activating factors produced specifically by MM-derived BMSCs may provide a novel biomarker and/or drug target for the treatment of this commonly fatal disease.</p

    Inhibition of striatal dopamine release by the L-type calcium channel inhibitor isradipine co-varies with risk factors for Parkinson's

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    Ca2+ entry into nigrostriatal dopamine (DA) neurons and axons via L-type voltage-gated Ca2+ channels (LTCCs) contributes, respectively, to pacemaker activity and DA release and has long been thought to contribute to vulnerability to degeneration in Parkinson's disease. LTCC function is greater in DA axons and neurons from substantia nigra pars compacta than from ventral tegmental area, but this is not explained by channel expression level. We tested the hypothesis that LTCC control of DA release is governed rather by local mechanisms, focussing on candidate biological factors known to operate differently between types of DA neurons and/or be associated with their differing vulnerability to parkinsonism, including biological sex, α-synuclein, DA transporters (DATs) and calbindin-D28k (Calb1). We detected evoked DA release ex vivo in mouse striatal slices using fast-scan cyclic voltammetry and assessed LTCC support of DA release by detecting the inhibition of DA release by the LTCC inhibitors isradipine or CP8. Using genetic knockouts or pharmacological manipulations, we identified that striatal LTCC support of DA release depended on multiple intersecting factors, in a regionally and sexually divergent manner. LTCC function was promoted by factors associated with Parkinsonian risk, including male sex, α-synuclein, DAT and a dorsolateral co-ordinate, but limited by factors associated with protection, that is, female sex, glucocerebrosidase activity, Calb1 and ventromedial co-ordinate. Together, these data show that LTCC function in DA axons and isradipine effect are locally governed and suggest they vary in a manner that in turn might impact on, or reflect, the cellular stress that leads to parkinsonian degeneration
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