Computational Fluid Dynamics Analysis of Arteriovenous Graft Configurations

Hemodialysis is a process of external blood filtration that becomes necessary in the event of end stage renal disease. The most common method of the treatment is the creation of an arteriovenous fistula, which is a surgically created connection between a vein and an artery. For patients who are unable to have an arteriovenous fistula, an arteriovenous graft is required. This graft serves to provide an access site for the removal on unfiltered blood and the return of filtered blood. The design and placement of this graft has not yet been optimized based upon mechanical principles. The aim of this thesis is to evaluate how factors that a surgeon can adjust affect several key parameters that lead to arteriovenous graft failure

Inundative pest control: How risky is it? A case study using entomopathogenic nematodes in a forest ecosystem

Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. Their widespread use makes environmental risk assessment important, but very few comprehensive post-application risk assessments have been conducted for EPN. We apply a rigorous risk analysis procedure to the use of EPN applied in a forest ecosystem to suppress the large pine weevil (Hylobius abietis). In this synthesis, we provide a quantitative evaluation of five risk categories: (a) establishment, (b) dispersal, (c) host range, (d) direct non-target effects and (e) indirect non-target effects. A low level of risk was identified (35–51 out of a possible total of 125). Species exotic to the clear-fell forest ecosystem (Steinernema carpocapsae and Heterorhabditis downesi) were accorded a lower overall risk status than native species and strains (Steinernema feltiae), largely as a result of their shorter persistence in the target environment. We conclude that EPN are a low risk viable alternative control for pine weevil compared to the higher risk conventional control using pyrethroid or neonicotinoid insecticides

Crossed: Strength in Unity and Connection

It is only through the strength of bonds that we can overcome evil. In Crossed, these bonds are tested as Calum and Dmitri are forced to duel for their lives. The film explores the themes of indoctrination, belief, the power of friendship, and never giving up on the people you care about. The accompanying paper explores how these themes are integral to who we are. I then explore the process of producing animation utilizing cutting-edge mediums and how these mediums can allow us to create animation in an entirely new way

Tailoring of arteriovenous graft‑to‑vein anastomosis angle to attenuate pathological flow fields

Abstract Arteriovenous grafts are routinely placed to facilitate hemodialysis in patients with end stage renal disease. These grafts are conduits between higher pressure arteries and lower pressure veins. The connection on the vein end of the graft, known as the graft-to-vein anastomosis, fails frequently and chronically due to high rates of stenosis and thrombosis. These failures are widely believed to be associated with pathologically high and low flow shear strain rates at the graft-to-vein anastomosis. We hypothesized that consistent with pipe flow dynamics and prior work exploring vein-to-artery anastomosis angles in arteriovenous fistulas, altering the graft-to-vein anastomosis angle can reduce the incidence of pathological shear rate fields. We tested this via computational fluid dynamic simulations of idealized arteriovenous grafts, using the Bird-Carreau constitutive law for blood. We observed that low graft-to-vein anastomosis angles ( $$40^{\circ }$$ > 40 ∘ ) led to increased incidence of pathologically high shear rates. Optimizations predicted that an intermediate  ( $$\sim 30^\circ$$ ∼ 30 ∘ ) graft-to-anastomosis angle was optimal. Our study demonstrates that graft-to-vein anastomosis angles can significantly impact pathological flow fields, and can be optimized to substantially improve arteriovenous graft patency rates

Environmental safety of entomopathogenic nematodes – Effects on abundance, diversity and community structure of non-target beetles in a forest ecosystem

The large pine weevil, Hylobius abietis, is a serious threat to reforestation in Europe that necessitates routine use of chemical insecticides. Application of entomopathogenic nematodes (EPN) to the coniferous tree stumps in which weevils breed has the potential to reduce the use of chemical pesticides. During field trials to assess the efficacy of nematodes against pine weevil, non-target beetles were also identified and quantified on 10 sites (14 trials). Nematodes were applied to stumps between June and July. Emergence traps captured beetles exiting from nematode-treated and untreated control stumps. Four trials were monitored in the months immediately following nematode application and ten were monitored the year after nematode application. A total of 65 species of non-target beetles were recovered, including 11 saproxylic species. We found no evidence of an effect of applied EPN on non-target beetle species richness, abundance, species richness per individual collected, or Shannon’s entropy (H’) either immediately or a year after nematode application, when more wood-specialists were recorded. As expected, there were marked differences between sites and/or tree species in the populations of non-target beetles recovered. These results indicate that when EPN are applied in a forest ecosystem to suppress H. abietis populations, the risk to non-target coleopteran populations must be considered negligible

Suicide Screening in Primary Care: Use of an Electronic Screener to Assess Suicidality and Improve Provider Follow-Up for Adolescents

Purpose The purpose of this study was to assess the feasibility of using an existing computer decision support system to screen adolescent patients for suicidality and provide follow-up guidance to clinicians in a primary care setting. Predictors of patient endorsement of suicidality and provider documentation of follow-up were examined. Methods A prospective cohort study was conducted to examine the implementation of a CDSS that screened adolescent patients for suicidality and provided follow-up recommendations to providers. The intervention was implemented for patients aged 12–20 years in two primary care clinics in Indianapolis, Indiana. Results The sample included 2,134 adolescent patients (51% female; 60% black; mean age = 14.6 years [standard deviation = 2.1]). Just over 6% of patients screened positive for suicidality. A positive endorsement of suicidality was more common among patients who were female, depressed, and seen by an adolescent−medicine board-certified provider as opposed to general pediatric provider. Providers documented follow-up action for 83% of patients who screened positive for suicidality. Documentation of follow-up action was correlated with clinic site and Hispanic race. The majority of patients who endorsed suicidality (71%) were deemed not actively suicidal after assessment by their provider. Conclusions Incorporating adolescent suicide screening and provider follow-up guidance into an existing computer decision support system in primary care is feasible and well utilized by providers. Female gender and depressive symptoms are consistently associated with suicidality among adolescents, although not all suicidal adolescents are depressed. Universal use of a multi-item suicide screener that assesses recency might more effectively identify suicidal adolescents

Stump-harvesting for bioenergy probably has transient impacts on abundance, richness and community structure of beetle assemblages

Harvesting of tree stumps for bioenergy is popular and, although the environmental impact has been considered with respect to ecosystem processes, there have been fewer studies on the impact of stump-harvesting on biodiversity. We carried out pitfall-trap surveys of beetle communities at eight plots across four sites (four plots were clear-fells where stumps remained and four were clear-fells where stumps were harvested). Initially, we recovered 7743 beetles when stumps were extracted but still on site (Year 1). All beetles were identified to family level and ground beetles and wood-associated beetles to species level. One year after stumps were extracted, the survey was repeated. In this collection, 2898 individual beetles were recovered. In Year 1, stump-harvesting had a negative impact on beetle abundance and richness. However, 1year after stumps were removed, there were no significant differences in these variables at any site. At the community level, stump-harvesting weakly but significantly, affected carabid composition. Oneyear after stumps were removed, stump-harvesting had no effect on community composition. Stump-harvesting initially negatively affects beetle abundance, family-richness and carabid species richness, as well as community structure, although any effects are not large, are site-specific and are probably not persistent. © 2017 The Royal Entomological Societ

High Antioxidant Load Impairs Cutaneous Microvascular Function in Healthy Young Women

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H2 in the interstitial channels of nanotube bundles

The equation of state of H2 adsorbed in the interstitial channels of a carbon nanotube bundle has been calculated using the diffusion Monte Carlo method. The possibility of a lattice dilation, induced by H2 adsorption, has been analyzed by modeling the cohesion energy of the bundle. The influence of factors like the interatomic potentials, the nanotube radius and the geometry of the channel on the bundle swelling is systematically analyzed. The most critical input is proved to be the C-H2 potential. Using the same model than in planar graphite, which is expected to be also accurate in nanotubes, the dilation is observed to be smaller than in previous estimations or even inexistent. H2 is highly unidimensional near the equilibrium density, the radial degree of freedom appearing progressively at higher densities.Comment: Accepted for publication in PR