The effects of manipulation of sedimentary iron and organic matter on sediment biogeochemistry and seagrasses in a subtropical carbonate environment

The microbial metabolism of organic matter (OM) in seagrass beds can create sulfidic conditions detrimental to seagrass growth; iron (Fe) potentially has ameliorating effects through titration of the sulfides and the precipitation of iron-sulfide minerals into the sediment. In this study, the biogeochemical effects of Fe availability and its interplay with sulfur and OM on sulfide toxicity, phosphorous (P) availability, seagrass growth and community structure were tested. The availability of Fe and OM was manipulated in a 2 × 2 factorial experiment arranged in a Latin square, with four replicates per treatment. The treatments included the addition of Fe, the addition of OM, the addition of both Fe and OM as well as no addition. The experiment was conducted in an oligotrophic, iron-deficient seagrass bed. Fe had an 84.5% retention efficiency in the sediments with the concentration of Fe increasing in the seagrass leaves over the course of the experiment. Porewater chemistry was significantly altered with a dramatic decrease in sulfide levels in Fe addition plots while sulfide levels increased in the OM addition treatments. Phosphorus increased in seagrass leaves collected in the Fe addition plots. Decreased sulfide stress was evidenced by heavier δ34S in leaves and rhizomes from plots to which Fe was added. The OM addition negatively affected seagrass growth but increased P availability; the reduced sulfide stress in Fe added plots resulted in elevated productivity. Fe availability may be an important determinant of the impact that OM has on seagrass vitality in carbonate sediments vegetated with seagrasses.

Nutrient cycling in Alaskan tundra in response to experimental manipulation of growing season length and soil temperature : a climate change scenario

Climate change in the Arctic is predicted to increase plant productivity through decomposition-related enhanced nutrient availability. However, the extent of the increase will depend on whether the increased nutrient availability can be sustained. To address this uncertainty, I assessed the response of plant tissue nutrients, litter decomposition rates, and soil nutrient availability to experimental climate warming manipulations, extended growing season and soil warming, over a 7 year period. Overall, the most consistent effect was the year-to-year variability in measured parameters, probably a result of large differences in weather and time of snowmelt. The results of this study emphasize that although plants of arctic environments are specifically adapted to low nutrient availability, they also posses a suite of traits that help to reduce nutrient losses such as slow growth, low tissue concentrations, and low tissue turnover that result in subtle responses to environmental changes.

Acoustic Manipulation and Alignment of Particles for Applications in Separation, Micro-Templating, and Device Fabrication

This dissertation studies the manipulation of particles using acoustic stimulation for applications in microfluidics and templating of devices. The term particle is used here to denote any solid, liquid or gaseous material that has properties, which are distinct from the fluid in which it is suspended. Manipulation means to take over the movements of the particles and to position them in specified locations. Using devices, microfabricated out of silicon, the behavior of particles under the acoustic stimulation was studied with the main purpose of aligning the particles at either low-pressure zones, known as the nodes or high-pressure zones, known as anti-nodes. By aligning particles at the nodes in a flow system, these particles can be focused at the center or walls of a microchannel in order to ultimately separate them. These separations are of high scientific importance, especially in the biomedical domain, since acoustopheresis provides a unique approach to separate based on density and compressibility, unparalleled by other techniques. The study of controlling and aligning the particles in various geometries and configurations was successfully achieved by controlling the acoustic waves. Apart from their use in flow systems, a stationary suspended-particle device was developed to provide controllable light transmittance based on acoustic stimuli. Using a glass compartment and a carbon-particle suspension in an organic solvent, the device responded to acoustic stimulation by aligning the particles. The alignment of light-absorbing carbon particles afforded an increase in visible light transmittance as high as 84.5%, and it was controlled by adjusting the frequency and amplitude of the acoustic wave. The device also demonstrated alignment memory rendering it energy-efficient. A similar device for suspended-particles in a monomer enabled the development of electrically conductive films. These films were based on networks of conductive particles. Elastomers doped with conductive metal particles were rendered surface conductive at particle loadings as low as 1% by weight using acoustic focusing. The resulting films were flexible and had transparencies exceeding 80% in the visible spectrum (400-800 nm) These films had electrical bulk conductivities exceeding 50 S/cm.

Waveguide microgripper for identification, sensing and manipulation

A Waveguide Microgripper utilizes flexible optical waveguides as gripping arms, which provide the physical means for grasping a microobject, while simultaneously enabling light to be delivered and collected. This unique capability allows extensive optical characterization of the structure being held such as transmission, reflection or fluorescence. One of the simplest capabilities of the waveguide microgripper is to be able to detect the presence of a microobject between the microgripper facets by monitoring the transmitted intensity of light coupled through the facets. The intensity of coupled light is expected to drop when there is an object obstructing the path of light. The optical sensing and characterization function of the microgripper is a strong function of the optical power incident on the structure of interest. Hence it is important to understand the factors affecting the power distribution across the facet. The microgripper is also capable of detecting the fluorescence. This capability of microgripper is expected to have applications in medical, bio-medical and related fields.

Direct In Vivo Manipulation and Imaging of Calcium Transients in Neutrophils Identify a Critical Role for Leading-Edge Calcium Flux.

Calcium signaling has long been associated with key events of immunity, including chemotaxis, phagocytosis, and activation. However, imaging and manipulation of calcium flux in motile immune cells in live animals remain challenging. Using light-sheet microscopy for in vivo calcium imaging in zebrafish, we observe characteristic patterns of calcium flux triggered by distinct events, including phagocytosis of pathogenic bacteria and migration of neutrophils toward inflammatory stimuli. In contrast to findings from ex vivo studies, we observe enriched calcium influx at the leading edge of migrating neutrophils. To directly manipulate calcium dynamics in vivo, we have developed transgenic lines with cell-specific expression of the mammalian TRPV1 channel, enabling ligand-gated, reversible, and spatiotemporal control of calcium influx. We find that controlled calcium influx can function to help define the neutrophil's leading edge. Cell-specific TRPV1 expression may have broad utility for precise control of calcium dynamics in other immune cell types and organisms.

Sparse Sample Detection Using Magnetic Bead Manipulation on a Digital Microfluidic Device

This thesis demonstrates a new way to achieve sparse biological sample detection, which uses magnetic bead manipulation on a digital microfluidic device. Sparse sample detection was made possible through two steps: sparse sample capture and fluorescent signal detection. For the first step, the immunological reaction between antibody and antigen enables the binding between target cells and antibody-­‐‑ coated magnetic beads, hence achieving sample capture. For the second step, fluorescent detection is achieved via fluorescent signal measurement and magnetic bead manipulation. In those two steps, a total of three functions need to work together, namely magnetic beads manipulation, fluorescent signal measurement and immunological binding. The first function is magnetic bead manipulation, and it uses the structure of current-­‐‑carrying wires embedded in the actuation electrode of an electrowetting-­‐‑on-­‐‑dielectric (EWD) device. The current wire structure serves as a microelectromagnet, which is capable of segregating and separating magnetic beads. The device can achieve high segregation efficiency when the wire spacing is 50µμm, and it is also capable of separating two kinds of magnetic beads within a 65µμm distance. The device ensures that the magnetic bead manipulation and the EWD function can be operated simultaneously without introducing additional steps in the fabrication process. Half circle shaped current wires were designed in later devices to concentrate magnetic beads in order to increase the SNR of sample detection. The second function is immunological binding. Immunological reaction kits were selected in order to ensure the compatibility of target cells, magnetic bead function and EWD function. The magnetic bead choice ensures the binding efficiency and survivability of target cells. The magnetic bead selection and binding mechanism used in this work can be applied to a wide variety of samples with a simple switch of the type of antibody. The last function is fluorescent measurement. Fluorescent measurement of sparse samples is made possible of using fluorescent stains and a method to increase SNR. The improved SNR is achieved by target cell concentration and reduced sensing area. Theoretical limitations of the entire sparse sample detection system is as low as 1 Colony Forming Unit/mL (CFU/mL).

A Micro-Opto-Electro-Mechanical System (MOEMS) for Microstructure Manipulation

Microstructure manipulation is a fundamental process to the study of biology and medicine, as well as to advance micro- and nano-system applications. Manipulation of microstructures has been achieved through various microgripper devices developed recently, which lead to advances in micromachine assembly, and single cell manipulation, among others. Only two kinds of integrated feedback have been demonstrated so far, force sensing and optical binary feedback. As a result, the physical, mechanical, optical, and chemical information about the microstructure under study must be extracted from macroscopic instrumentation, such as confocal fluorescence microscopy and Raman spectroscopy. In this research work, novel Micro-Opto-Electro-Mechanical-System (MOEMS) microgrippers are presented. These devices utilize flexible optical waveguides as gripping arms, which provide the physical means for grasping a microobject, while simultaneously enabling light to be delivered and collected. This unique capability allows extensive optical characterization of the structure being held such as transmission, reflection, or fluorescence. The microgrippers require external actuation which was accomplished by two methods: initially with a micrometer screw, and later with a piezoelectric actuator. Thanks to a novel actuation mechanism, the “fishbone”, the gripping facets remain parallel within 1 degree. The design, simulation, fabrication, and characterization are systematically presented. The devices mechanical operation was verified by means of 3D finite element analysis simulations. Also, the optical performance and losses were simulated by the 3D-to-2D effective index (finite difference time domain FDTD) method as well as 3D Beam Propagation Method (3D-BPM). The microgrippers were designed to manipulate structures from submicron dimensions up to approximately 100 µm. The devices were implemented in SU-8 due to its suitable optical and mechanical properties. This work demonstrates two practical applications: the manipulation of single SKOV-3 human ovarian carcinoma cells, and the detection and identification of microparts tagged with a fluorescent “barcode” implemented with quantum dots. The novel devices presented open up new possibilities in the field of micromanipulation at the microscale, scalable to the nano-domain.

THE DARK PERSONALITY AND JOB SUCCESS IN THE UNITED STATES ARMY: USE OF INTERPERSONAL MANIPULATION IN THE WORKPLACE

This dissertation relates job desires and outcomes to the Dark Personality (Psychopathy, Machiavellianism, Narcissism, Low Agreeableness, Low Honesty-Humility) in the United States Army. It purports that individuals high on the Dark Personality desire more power, money, and status, and that they obtain jobs that afford them these luxuries by using manipulation at work. Two pilot studies used samples of United States Army members to create and test index variables: Dark Personality, Total Manipulation in the workplace, Desire for Job Success, and Total Job Success in the Army. Individual personality traits, manipulation tactics, and job desires were examined in secondary analyses. Using a sample of 468 United States Army Members, central analyses indicated that Army members high on the Dark Personality desired Job Success. Likewise, army members higher on the Dark Personality used more Manipulation tactics at work, including the egregious tactics. Yet, using more Manipulation tactics at work predicted lower levels of Job Success in the Army. Most manipulation tactics had a negative impact on Job Success, with the exception of soft tactics like Reason and Responsibility Invocation. Together, these results indicate that selective use of soft manipulation predicted Job Success, but use of more manipulation tactics predicted less Job Success in the Army. Curvilinear results indicated that being either very low or very high on the Dark Personality predicted more Job Success in the Army, whereas having intermediate levels of the Dark Personality predicted less Job Success. Finally, possessing the Dark Personality and using more Manipulation tactics at work, together, predicted less Job Success in the Army. Collectively, the results indicate that army members with intermediate levels of the Dark Personality want more powerful and high paying jobs, yet their strategy of manipulating their coworkers to move up the job ladder does not result in higher ranking, higher paying Army positions. However, Army members highest on the Dark Personality achieved job success, defying the maladaptive influence that antisocial personality traits and manipulative behaviour had on job success for most Army members. Therefore, this dissertation indicates that successful corporate scoundrels exist in the Army, but there are few of them.

Completion strategy or emphasis manipulation? Task support for teaching information problem solving

While most students seem to solve information problems effortlessly, research shows that the cognitive skills for effective information problem solving are often underdeveloped. Students manage to find information and formulate solutions, but the quality of their process and product is questionable. It is therefore important to develop instruction for fostering these skills. In this research, a 2-h online intervention was presented to first-year university students with the goal to improve their information problem solving skills while investigating effects of different types of built-in task support. A training design containing completion tasks was compared to a design using emphasis manipulation. A third variant of the training combined both approaches. In two experiments, these conditions were compared to a control condition receiving conventional tasks without built-in task support. Results of both experiments show that students' information problem solving skills are underdeveloped, which underlines the necessity for formal training. While the intervention improved students’ skills, no differences were found between conditions. The authors hypothesize that the effective presentation of supportive information in the form of a modeling example at the start of the training caused a strong learning effect, which masked effects of task support. Limitations and directions for future research are presented.

Företags potentiella manipulation av tillväxttakt i goodwillnedskrivningstestet : En kvantitativ studie av svenska och finska börsnoterade företag

Bakgrund och problem: I och med den nya standarden IAS 36 ska företagen göra uppskattningar angående den långsiktiga tillväxttakten i goodwillnedskrivningstestet. Detta innebär en möjlighet att manipulera tillväxttakten för att på så vis undvika eller framkalla nedskrivning av goodwill. Problemformulering: Hur påverkar utvalda variabler företags potentiella manipulation av angiven tillväxttakt? Syfte: Syftet med studien är att bidra med förklaringar till vad som påverkar att företag redovisar för höga respektive för låga tillväxttakter i goodwillnedskrivningstestet. Metod: Denna studie bygger på en kvantitativ metod där urvalet består av samtliga svenska och finska börsnoterade företag med redovisad goodwill. Utifrån existerade kunskap formuleras fyra hypoteser som testas mot empirin. Resultat och slutsats: Resultatet av denna studie visar inga signifikanta samband mellan den beroende variabeln manipulation och de oberoende variablerna storlek, skuldsättningsgrad, bransch och redovisningstillsyn. Den deskriptiva statistiken visar att i stort sett hälften av företagen manipulerar tillväxttakten.

Manipulation in U.S. REIT Investment Performance Evaluation: Empirical Evidence

We investigate whether Real Estate Investment Trust (REIT) managers actively manipulate performance measures in spite of the strict regulation under the REIT regime. We provide empirical evidence that is consistent with this hypothesis. Specifically, manipulation strategies may rely on the opportunistic use of leverage. However, manipulation does not appear to be uniform across REIT sectors and seems to become more common as the level of competition in the underlying property sector increases. We employ a set of commonly used traditional performance measures and a recently developed manipulation-proof measure (MPPM, Goetzmann, Ingersoll, Spiegel, and Welch (2007)) to evaluate the performance of 147 REITs from seven different property sectors over the period 1991-2009. Our findings suggest that the existing REIT regulation may fail to mitigate a substantial agency conflict and that investors can benefit from evaluating return information carefully in order to avoid potentially manipulative funds.

La manipulation des ressources alimentaires et du risque de prédation afin d’augmenter la vulnérabilité du cerf de Virginie à la chasse

L’utilisation de l’espace par une proie herbivore est souvent modulée par le compromis entre l’acquisition de fourrage et l’évitement de la prédation. Nous avons testé l’effet de la manipulation de la disponibilité de fourrage et du ratio couvert forestier/ouverture sur l’utilisation de l’espace par le cerf de Virginie (Odocoileus virginianus) et sa vulnérabilité à la chasse sportive sur l’île d’Anticosti. Nos résultats ont démontré que l’utilisation de l’espace par le cerf et sa vulnérabilité à la chasse peuvent être modifiées par différentes composantes structurales de l’habitat. L’augmentation de la disponibilité de fourrage a entrainé une plus grande utilisation des prairies fertilisées par le cerf, tandis que la diminution du ratio couvert forestier/ouverture a augmenté sa vulnérabilité à la chasse. Ces résultats procurent des pistes de solutions pour les gestionnaires fauniques qui doivent à la fois réduire les dommages causés par les hautes densités de cerfs et satisfaire les chasseurs en maintenant un nombre élevé d’observation de cerfs.

Apicomplexans pulling the strings: manipulation of the host cell cytoskeleton dynamics

Invasive stages of apicomplexan parasites require a host cell to survive, proliferate and advance to the next life cycle stage. Once invasion is achieved, apicomplexans interact closely with the host cell cytoskeleton, but in many cases the different species have evolved distinct mechanisms and pathways to modulate the structural organization of cytoskeletal filaments. The host cell cytoskeleton is a complex network, largely, but not exclusively, composed of microtubules, actin microfilaments and intermediate filaments, all of which are modulated by associated proteins, and it is involved in diverse functions including maintenance of cell morphology and mechanical support, migration, signal transduction, nutrient uptake, membrane and organelle trafficking and cell division. The ability of apicomplexans to modulate the cytoskeleton to their own advantage is clearly beneficial. We here review different aspects of the interactions of apicomplexans with the three main cytoskeletal filament types, provide information on the currently known parasite effector proteins and respective host cell targets involved, and how these interactions modulate the host cell physiology. Some of these findings could provide novel targets that could be exploited for the development of preventive and/or therapeutic strategies.

A Study of pH Manipulation on Tumor Proliferation and the CTL Response

Adoptive Cell Transfer (ACT) Therapy is a cancer treatment that enhances and utilizes the body’s own immune system. However, this treatment has had limited success in clinical trials. We hypothesized that this is due to the immunosuppressive, acidic microenvironment of cancer tumors. We tested the effects of acidic, neutral, and basic environments in vitro on cytotoxic T lymphocyte (CTL) survival, activation, migration and killing ability and on cancer cell survival. We found that CTLs have most optimum survival, activation, and migration in a neutral environment, while the optimal extracellular conditions for EG-7 lymphoma are slightly acidic and B16-OVA melanoma survives best in physiological conditions. Future research should further study the killing ability of T cells in the three different environments and look to move to in vivo experiments.

Genetic manipulation of Anopheles stephensi immunity to increase plasmodium falciparum salivary gland sporozoite infection levels

Human malaria is responsible for over 700,000 deaths a year. To stay abreast of the threat posed by the parasite, a constant stream of new drugs and vector control methods are required. This study focuses on a vaccine that has the potential to protect against parasite infection, but has been hindered by developmental challenges. In malaria prevention, live, attenuated, aseptic, Plasmodium falciparum sporozoites (PfSPZ) can be administered as a highly protective vaccine. PfSPZ are produced using adult female Anopheles stephensi mosquitoes as bioreactors. Production volume and cost of a PfSPZ vaccine for malaria are expected to be directly correlated with Plasmodium falciparum infection intensity in the salivary glands. The sporogonic development of Plasmodium falciparum in A. stephensi to fully infected salivary gland stage sporozoites is dictated by the activities of several known components of the mosquito’s innate immune system. Here I report on the use of genetic technologies that have been rarely, if ever, used in Anopheles stephensi Sda500 to increase the yield of sporozoites per mosquito and enhance vaccine production. By combining the Gal4/UAS bipartite system with in vivo expression of shRNA gene silencing, activity of the IMD signaling pathway downstream effector LRIM1, an antagonist to Plasmodium development, was reduced in the midgut, fat body, and salivary glands of A. stephensi. In infection studies using P. berghei and P. falciparum these transgenic mosquitoes consistently produced significantly more salivary gland stage sporozoites than wildtype controls, with increases in P. falciparum ranging from 2.5 to 10 fold. Using Plasmodium infection assays and qRT-PCR, two novel findings were identified. First, it was shown that 14 days post Plasmodium infection, transcript abundance of the IMD immune effector genes LRIM1, TEP1 and APL1c are elevated, in the salivary glands of A. stephensi, suggesting the salivary glands may play a role in post midgut defense against the parasite. Second, a non-pathogenic IMD signaling pathway response was observed which could suggest an alternative pathway for IMD activation. The information gained from these studies has significantly increased our knowledge of Plasmodium defense in A. stephensi and moreover could significantly improve vaccine production.