Invasive plants can alter pollination dynamics in invaded communities by disrupting patterns of pollinator visitation, pollen transfer dynamics (conspecific [CP] and heterospecific [HP]), and reproductive success. The direction of invasive effects (competitive, neutral, and facilitative) may be partially determined by spatial scale and species’ floral traits. Here, we investigated pollinator visitation, CP and HP receipt, and pollen tube growth for species in a C. arvense present community and non-present community at two scales. At the community-level, the effect of C. arvense on pollinator visitation varied among species. Floral symmetry seemed to explain this variation. At the floral neighborhood-level, we found competitive effects for pollinator visits and mixed effects on CP deposition. The overall structure of plant-plant HP deposition networks was slightly altered. We observed lower average centrality across shared species in the C. arvense present community suggesting C. arvense had subverted their roles as pollen donors.

Oxbow lakes are highly productive waterbodies that host multiple life stages of many freshwater aquatic species. Oxbow lakes also provide habitat to Silver Carp (Hypophthalmichthys molitrix), which has enabled populations to grow and expand within the United States. Silver Carp are undesirable because they can compete for resources with native fishes. My goal was to identify patterns of distribution and dispersion of Silver Carp in Moon Lake, Mississippi, to assist and inform precise harvesting of fish. I implanted thirty-five adult Silver Carp with acoustic tags that I released into Moon Lake. I observed that Silver Carp were disproportionately found in locations where water depths ranged from 2.0-5.9 m during all seasons, despite the availability of locations with shallower and deeper water. Silver Carp did aggregate in the wintertime (December-February) in comparison to all other seasons. This information about depth distributions and seasonal aggregations can inform removal programs.

Although it is well documented how introduced species can negatively affect native species, we only poorly understand how they may alter ecosystem functions. We investigated how an invasive fish affected the flux of aquatic insects to terrestrial food webs using mesocosms in a desert spring ecosystem. We compared aquatic insect emergence between alternative community states with monocultures and polycultures of two native species of fish, least chub (Iotichthys phlegethontis) and Utah chub (Gila atraria) plus, introduced western mosquitofish (Gambusia affinis). We tested three hypotheses: (1) aquatic insect biomass will be greater than terrestrial insect biomass and thus, constitute a vital source of energy for terrestrial consumers (2) invasive mosquitofish will negatively impact the biomass of emerging aquatic insects, and (3) terrestrial consumers will negatively respond to decreased emerging aquatic insect biomass. Aquatic insects represented 79% of the flying insect community, and treatments with mosquitofish significantly reduced emergent aquatic insect biomass by 60% relative to the control without mosquitofish. Behavioral traits of invasive species are important, because mosquitofish most heavily affected insects that emerged during the day. Also, spiders that build horizontal webs were negatively correlated with decreasing aquatic insect biomass. Invasive mosquitofish can achieve very dense populations because of their high intrinsic rate of population increase, which can significantly disrupt the flow of energy between aquatic and terrestrial ecosystems, thereby reducing the energy available for terrestrial consumers.

This thesis includes two studies: The first examined patterns of neutral genetic diversity within Bromus tectorum L. across the IMW region, and uses patterns of microsatellite (SSR) genotype distribution to make inferences about the respective roles of adaptively significant genetic variation, adaptive phenotypic plasticity, and facultative outcrossing in the ongoing invasion and recent range expansion of B. tectorum. It has been previously demonstrated that, due to extremely low outcrossing rates, it is possible to characterize individual genotypes of this species using four SSR loci. We sampled 20 individuals from each of 96 B. tectorum populations (classified by region and habitat) from throughout the IMW and used these SSR markers to characterize each individual. We found 131 four-locus SSR genotypes; however, the 14 most common genotypes collectively accounted for 79.2% of the individuals sampled. Individuals with certain SSR genotypes sorted strongly into warm or salt desert habitats (stringent habitats) and flowered earlier than individuals with genotypes from more mesic habitats, providing evidence of adaptively significant genetic variation associated with these genotypes. Other SSR genotypes were found across a wide range of habitats though they tended to be less prevalent in stringent habitats, providing evidence that adaptive phenotypic plasticity may be important for the distribution of some common genotypes. We observed very few heterozygous individuals, consistent with the highly inbreeding reproductive strategy of B. tectorum. Because specialist genotypes dominating recently invaded areas within the IMW region contained unique alleles, they are not likely to have resulted from recombination, leading us to doubt the role of facultative outcrossing as a significant mechanism facilitating the current range expansion of B. tectorum in the IMW.Previous research investigating the population and ecological genetics of Bromus tectorum L. in the North American invaded range has relied on either allozyme or microsatellite (SSR) genetic analyses, both of which have proven to have shortcomings. In order to overcome the issues associated with these other marker types, in the second study of this thesis we developed single nucleotide polymorphism (SNP) markers for B. tectorum by 1) obtaining normalized cDNA, 2) sequencing normalized cDNA using 454 sequencing, 3) aligning resultant contigs and looking for SNPs, 4) designing assays for SNP validation and genotyping using KASPar, 5) converting working KASPar assays for use with the Fluidigm EP1 platform using the 96.96 Dynamic ArrayTM IFC. Sequencing resulted in 1258041 reads, which assembled into 65486 contigs (20782 large contigs exceeding 500 base pairs). Using selection criteria of at least 10x coverage and 30% of the minor allele, 3333 putative SNPs were identified. We developed KASP assays for 255 putative SNPs, which resulted in 101 working polymorphic assays. Ninety-six assays were then successfully converted for use with KASP on the Fluidigm EP1 genotyping platform using 96.96 dynamic arrays.

Non-invasive blood analysis devices that can measure characteristics less prominent than the oxygenation of hemoglobin are of interest in the medical community. An important step in creating these devices is to model the interaction of photons with human tissue in increasingly greater physiological detail. We have modeled, using a Monte Carlo technique, the interaction of photons through epidermis, blood and water arranged both in layers and in a homogeneous mixture. We confirm the expected linear relation between photon attenuation and material volumetric percentage in our two-layer models. We discovered that this relationship becomes non-linear in the homogeneously mixed models where volumetric percentage must be replaced with interaction volume percentage. These nonlinearities become significant when the values of the interaction coefficient, µt, differ by an order of magnitude or more and could prove crucial in accurately reading oxygenation or other constituents in the blood and also in modeling radiation delivered to a patient in photodynamic therapy.

Observations of Bromus tectorum L. (cheatgrass or downy brome) monocultures have shown that populations are susceptible to stand die-off or replacement failures. Die-offs, where the seed bank from the previous year fails to emerge, occurs in cheatgrass stands and it is unclear the trigger or cause. The fungus Fusarium has been identified in plant and seed samples from die-offs and may drive die-off activity through pathogenicity. Die-off recovery may take several years but cheatgrass populations eventually reestablish. The purpose of our study was to determine whether Fusarium is a potential player in a die-off, and understand how die-offs recover after multiple years of stand failure. Our objectives were to determine: 1- litter and water effects on die-off activity; 2- if fungal pathogens, such as Fusarium, decrease the proportion of cheatgrass emergence in a die-off; and 3- whether direct or broadcast seeding, water, and litter treatments increase establishment in recovering die-offs. Litter absent plots had significantly (P < 0.0001 and P < 0.001) more emergence at 49.2% and 41% compared to litter present plots 21.3% and 23.7%. The litter absent plots significantly (P = 0.0003 and P = 0.001) increased survival (82% and 52%) compared to litter present plots (70% and 41%). Direct planted versus broadcast seeding had significantly (P < 0.0001) more emergence, 36% to 11.9%. The addition of Fusarium inoculum to field plots did not effectively replicate anticipated disease levels. The fungicide treatment did not have a significant influence at either site. The results from the study indicate that nothing inhibits cheatgrass from establishing following a persistent die-off disturbance. A unique window may be available for land managers to revegetate natives in invasive populations as large quantities of cheatgrass seeds fail to emerge during die-off events.

Complete or partial obstruction of the duodenum by the superior mesenteric artery (SMA) is a rare cause of bowel obstruction. SMA syndrome results from the compression of the 3rd part of the duodenum between the superior mesenteric artery and the abdominal aorta. Causes include anatomical variation in the superior mesenteric artery, trauma, burns, surgeries, malignancy, and rapid weight loss. Diagnosis of SMA syndrome in patients may be difficult, as the clinical findings often resemble other forms of small bowel obstructions. This syndrome was first described in the literature by Carl Freiherr von Rokitansky in 1861. Subsequently, David Wilke provided a comprehensive description of the disease in a series of 75 patients. There has been skepticism about the existence of SMA syndrome due to scant literature reports and non-specific symptomatology. However, modern cross-sectional imaging has confirmed the existence of this rare syndrome. Here we present the case of a 50-year-old female with longstanding symptoms of gastrointestinal discomfort, weight loss, nausea, and vomiting. She underwent an exhaustive gastrointestinal workup until a diagnosis of SMA syndrome was made. We elected to proceed with a minimally invasive three-port laparoscopic, trans-mesenteric side-to-side duodenojejunostomy. The patient was discharged on postoperative day one after tolerating a regular diet. On one month follow-up, our patient reported improvement in symptoms with no postprandial pain or nausea and normal bowel movements. In conclusion, we report a case of superior mesenteric artery syndrome in a patient with recurrent abdominal pain and nausea. CT scan has the highest sensitivity for the diagnosis of SMA syndrome, findings suggestive of the diagnosis include an abnormal aortomesenteric angle and distance. While supplemental tube feeds and gastric drainage may resolve the condition without the need for surgery, this often takes many weeks to months to be effective. Minimally invasive surgical bypass is an attractive option because of the rapidity of symptom resolution, lack of need for long-term invasive tubes, short inpatient length of stay, and high success rate.

<p>Non-invasive electromagnetic brain stimulation uses electrodes and/or coils to modulate brain activity via the induced E-fields. E-field dosimetry solvers have improved non-invasive electromagnetic brain stimulation protocol and our understanding of neuroscience. However, E-field dosimetry techniques are incomplete in that the contributions of non-linear neuron activity are left unaccounted for. To better understand the neurological effects of non-invasive electromagnetic stimulation, we introduce an integral equation formulation for modeling the non-linear behavior of neurons due to an incident E-field generated by electrode and coil sources. We formulate the new integral equation using a boundary element approach. We compare the boundary element solver accuracy with an established finite element solver and multi-scale cable equation approaches. Unlike previous approaches, this new boundary integral formulation avoids multi-scaling challenges from meshing while retaining the accuracy and the robust spatial support of integral equation-based methods. The memory savings from switching to surface meshes makes simulations with more complex morphologies computationally tractable. Additionally, we examine the ability of neurons to couple to one another via the local extracellular fields. Examples of simulations with both transcranial electric and magnetic stimulation results for simple geometries are used to illustrate the capabilities of a boundary integral approach. This boundary integral method will aid the development of better neurological understanding, delineate the mechanisms by which electromagnetic stimulation engenders neuronal activity, and aid in modeling local E-field coupling.</p>

Invasive species are a threat to biodiversity, economy and human health. The distribution and spread of invasive species needs to be studied to make good management plans. Invasive plant species mostly came to Sweden as ornamental plants and later spread into the local fauna. This study aimed to investigate if observations of invasive plant species were still mainly near residental gardens, and if they were observed in a specific land use type. The analysis was made on four different invasive species (L. polyphyllus, I. glandulifera, H. mantegazzianum and R. japonica) in Blekinge County, Sweden. Species observations were obtained from the Swedish Agricultural University’s (SLU) species database “artportalen” on SLU:s “artdatabanken”. ArcGIS was used to measure the distance between species observations and the nearest buildings and identify the land use type for each point. Randomized points within Blekinge County were used as a comparison. The result showed a statistically significant difference in distance between the observed- and randomized points for all four species. (L. polyphyllus observed mean distance 10.7 meters, randomized mean distance 46.7 meters. I. glandulifera observed mean distance 9.1 meters, randomized mean distance 47 meters. H. mantegazzianum observed mean distance 7.1 meters, randomized mean distance 44.5 meters. R. japonica observed mean distance 5.8 meters, randomized mean distance 46.8 meters.). There was also a statistically significant difference in land use type distribution between the invasive species and the randomized points. The most common land use type occupied by the invasive plants studied was open landscapes. This could also explain the proximity to buildings, since the species spread from gardens into open landscapes such as roadsides. It is also likely that soil that contained seeds and/or rhizomes was used in constructions, keeping the species close to buildings. In conclusion, it seems that invasive plant species are often found close to buildings and in open landscapes, which means observations and management should focus on these areas. / Invasiva arter är ett hot mot biologisk mångfald, ekonomi och människors hälsa. För att kunna skapa fungerande åtgärdsplaner behövs kunskap kring var de invasiva arterna finns och hur de sprider sig. Invasiva växter importerades främst till Sverige för att dekorera trädgårdar där de sedan spred sig ut i naturen. Syftet med den här studien var att se om invasiva växter fortfarande observeras i närheten av trädgårdar och om de hittas något speciellt habitat. Studien gjordes på fyra arter (L. polyphyllus, I. glandulifera, H. mantegazzianum and R. japonica) i Blekinge län. Data över observationer för de olika arterna hämtades hos Sveriges lantbruksuniversitet (SLU) via artportalen i deras artdatabank. För att mäta distansen mellan observationspunkterna och närmaste byggnad och för att se i vilket habitat de hittades användes ArcGIS. Som kontroll skapades slumpvisa punkter inom länet som användes som jämförelse. Resultatet visade att det fanns statistiskt signifikant skillnad i avståndet mellan de observerade punkterna och de slumpvisa punkterna hos alla fyra arterna. (L. polyphyllus observerade medeldistans 10,7 meter, randomiserade medeldistans 46,7 meter. I. glandulifera observerade medeldistans 9,1 meter, randomiserade medeldistans 47 meter. H. mantegazzianum observerade medeldistans 7,1 meter, randomiserade medeldistans 44,5 meter. R. japonica observerade medeldistans 5,8 meter, randomiserade medeldistans 46,8 meter.) Det var även en statistiskt signifikant skillnad i fördelningen av habitat mellan de fyra arterna och de slumpartade punkterna. Det vanligaste habitatet var öppna landskap vilket kan förklara att de fortfarande hittas i närheten av byggnader då de spred sig från trädgårdar i öppna landskap som diken. Frön och rhizomer kan också följa med jord som grävs upp för att användas vid nybyggnation och då växer nya plantor upp nära byggnader. Slutsatsen är att invasiva växter finns i närheten av byggnader och i öppna landskap och därför bör vidare observationer och åtgärdsplaner göras i dessa områden.

The ability to measure flow in pipes often introduces expensive and difficult installations due to existing flow-meters being invasive. To solve this a non-invasive solution has been found by testing and evaluating different mechanical and electrical methods using ultrasonic piezo-crystals and time-of-flight calculations. The solution consists of an impedance matched circuit with a boosting circuit. Using ultrasound in an non-invasive way comes with a decreased accuracy which can be increased using various software methods. The results from tests at different water-flows shows that there is no significant statistical difference between the developed flow-meter and an existing mechanical one. It also shows that calibration has a major impact on the measured values. This hints at that with the right calibration of the ultrasonic flow-meter it should be possible to close the performance gap between the two flow-meters. / Möjligheten att mäta flöde i rör involverar ofta dyra och svåra installationer på grund av att existerande flödesmätare sitter i röret. För att lösa detta har en optimal icke-invasiv lösning hittats genom att testa och utvärdera olika mekaniska och elektriska metoder som använder piezo-kristaller och signalflygtid. Lösningen består av en impedansmatchningskrets och en boostkrets. Att använda ultraljud på ett icke invasisvt sätt kommer med en minskad precision som kan ökas genom att använda olika mjukvarulösningar. Resultaten från tester vid olika flödeshastigheter visar att det inte finns någon statistisk signifikans mellan den utvecklade flödesmätaren och en existerande mekanisk. Det visade också att kalibrering har en stor betydelse för mätvärderna. Det här visar på att man med rätt kalibrering borde kunna minska skillnaden i precision mellan de två mätarna.