A Socio-Ecological Approach to Wildlife Disease Risk

Many Eastern moose (Alces alces, Linnaeus; 1758) populations along the southern edge of their North American range are declining, including those in Minnesota, Vermont, and New Hampshire. More recently, in Maine, winter ticks (Dermacentor albipictus; Packard 1869) are suspected to also be influencing the population through periodic widespread mortality of calves. While metabolic stress from heavy winter tick parasitism has been implicated in these moose population declines, little is known about the relative effects of tick-borne diseases, which may compound metabolic stress. Tick-borne pathogens known to infect cervid species include Anaplasma species, a group of bacteria that cause a disease known as anaplasmosis. Furthermore, the decline of moose and emergence of ticks in Maine could influence outdoor recreation behavior, cultural practices, nature-based tourism businesses, and wildlife management. Perceived risk in regards to a decline in the moose population, the effects of winter ticks on moose, and the impacts that these may have on human systems could potentially influence people’s behaviors and management decision-making. To address both biological and social concerns, I applied an interdisciplinary approach with the following three goals: (G1) determine the prevalence and distribution of Anaplasma species infections in Maine’s moose and winter tick populations, and genetically characterized the species through sequencing and phylogenetic analyses, (G2) investigate whether fitness (in terms of calf survival through the winter) is predicted by its Anaplasma-infection status, tick load, and/or related health indices, and (G3) identify which factors (e.g. the experiences a person has had with the moose/winter tick system) determine Penobscot Nation citizens’ risk perceptions in regards to moose health, and the impacts of winter tick moose infestation on human systems. In addressing G1, I tested for the presence or absence of Anaplasma species DNA in moose and winter ticks by amplifying a 16S rRNA gene locus, capable of genus-level taxonomic specification. These data revealed that a large proportion (~54%) of moose calves in Maine are infected with an uncharacterized Anaplasma species, with a significant difference in Anaplasma prevalence between northern and western study sites as well as between sexes. Anaplasma was also detected in winter ticks, but only in a single pooled sample

Bone-to-bone and implant-to-bone impingement : a novel graphical representation for hip replacement planning

Bone-to-bone impingement (BTBI) and implant-to-bone impingement (ITBI) risk assessment is generally performed intra-operatively by surgeons, which is entirely subjective and qualitative, and therefore, lead to sub-optimal results and recurrent dislocation in some cases. Therefore, a method was developed for identifying subject-specific BTBI and ITBI, and subsequently, visualising the impingement area on native bone anatomy to highlight where prominent bone should be resected. Activity definitions and subject-specific bone geometries, with planned implants were used as inputs for the method. The ITBI and BTBI boundary and area were automatically identified using ray intersection and region growing algorithm respectively to retain the same ‘conical clearance angle’ obtained to avoid prosthetic impingement (PI). The ITBI and BTBI area was then presented with different colours to highlight the risk of impingement, and importance of resection. A clinical study with five patients after 2 years of THA was performed to validate the method. The results supported the study hypothesis, in that the predicted highest risk area (red coloured zone) was completely/majorly resected during the surgery. Therefore, this method could potentially be used to examine the effect of different pre-operative plans and hip motions on BTBI, ITBI, and PI, and to guide bony resection during THA surgery

Invariance of experimental observables with respect to coarse-graining in standard and many-body dissipative particle dynamics.

Dissipative particle dynamics (DPD) is a well-established mesoscale simulation method. However, there have been long-standing ambiguities regarding the dependence of its (purely repulsive) force field parameter on temperature as well as the variation of the resulting experimental observables, such as diffusivity or surface tension, with coarse-graining (CG) degree. Here, we rederive the temperature dependence of DPD interaction parameter and revisit the role of the CG degree in standard DPD simulations. Consequently, we derive a scaling of the input variables that renders the system properties invariant with respect to CG degree and illustrate the versatility of the method by computing the surface tensions of binary solvent mixtures. We then extend this procedure to many-body dissipative particle dynamics and, by computing surface tensions of the same mixtures at a range of CG degrees, demonstrate that this newer method, which has not been widely applied so far, is also capable of simulating complex fluids of practical interest.P.V. and J.A.E. acknowledge support of EPSRC and Johnson Matthey. P.V. acknowledges financial support from a Sir Colin Corness Bursar

Enhanced ordering reduces electric susceptibility of liquids confined to graphene slit pores.

The behaviours of a range of polar and non-polar organic liquids (acetone, ethanol, methanol, N-methyl-2-pyrrolidone (NMP), carbon tetrachloride and water) confined to 2D graphene nanochannels with thicknesses in the range of 4.5 Å to 40 Å were studied using classical molecular dynamics and hybrid density functional theory. All liquids were found to organise spontaneously into ordered layers parallel to the confining surfaces, with those containing polar molecules having their electric dipoles aligned parallel to such surfaces. In particular, monolayers of NMP showed remarkable in-plane ordering and low molecular mobility, suggesting the existence of a previously unknown 2D solid-like phase. Calculations for polar liquids showed dramatically reduced static permittivities normal to the confining surfaces; these changes are expected to improve electron tunnelling across the liquid films, modifying the DC electrical properties of immersed assemblies of carbon nanomaterials.Mexican Council for Science and Technology (CONACyT)This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2740

The electro-structural behaviour of yarn-like carbon nanotube fibres immersed in organic liquids.

Yarn-like carbon nanotube (CNT) fibres are a hierarchically-structured material with a variety of promising applications such as high performance composites, sensors and actuators, smart textiles, and energy storage and transmission. However, in order to fully realize these possibilities, a more detailed understanding of their interactions with the environment is required. In this work, we describe a simplified representation of the hierarchical structure of the fibres from which several mathematical models are constructed to explain electro-structural interactions of fibres with organic liquids. A balance between the elastic and surface energies of the CNT bundle network in different media allows the determination of the maximum lengths that open junctions can sustain before collapsing to minimize the surface energy. This characteristic length correlates well with the increase of fibre resistance upon immersion in organic liquids. We also study the effect of charge accumulation in open interbundle junctions and derive expressions to describe experimental data on the non-ohmic electrical behaviour of fibres immersed in polar liquids. Our analyses suggest that the non-ohmic behaviour is caused by progressively shorter junctions collapsing as the voltage is increased. Since our models are not based on any property unique to carbon nanotubes, they should also be useful to describe other hierarchical structures