INTEGRATED ASSESSMENT OF ANTHROPOGENIC, CLIMATE, AND POLICY INDUCED CHANGES OF PHOSPHORUS EXPORT IN THE UNITED STATES LAURENTIAN GREAT LAKES WATERSHEDS

Anthropogenic activities have increased phosphorus (P) loading in tributaries to the Laurentian Great Lakes resulting in eutrophication in small bays to most notably, Lake Erie. Changes to surface water quality from P loading have resulted in billions of dollars in damage and threaten the health of the world’s largest freshwater resource. To understand the factors affecting P delivery with projected increasing urban lands and biofuels expansion, two spatially explicit models were coupled. The coupled models predict that the majority of the basin will experience a significant increase in urban area P sources while the agriculture intensity and forest sources of P will decrease. Changes in P loading across the basin will be highly variable spatially. Additionally, the impacts of climate change on high precipitation events across the Great Lakes were examined. Using historical regression relationships on phosphorus concentrations, key Great Lakes tributaries were found to have future changes including decreasing total loads and increases to high-flow loading events. The urbanized Cuyahoga watersheds exhibits the most vulnerability to these climate-induced changes with increases in total loading and storm loading , while the forested Au Sable watershed exhibits greater resilience. Finally, the monitoring network currently in place for sampling the amount of phosphorus entering the U.S. Great Lakes was examined with a focus on the challenges to monitoring. Based on these interviews, the research identified three issues that policy makers interested in maintaining an effective phosphorus monitoring network in the Great Lakes should consider: first, that the policy objectives driving different monitoring programs vary, which results in different patterns of sampling design and frequency; second, that these differences complicate efforts to encourage collaboration; and third, that methods of funding sampling programs vary from agency to agency, further complicating efforts to generate sufficient long-term data to improve our understanding of phosphorus into the Great Lakes. The dissertation combines these three areas of research to present the potential future impacts of P loading in the Great Lakes as anthropogenic activities, climate and monitoring changes. These manuscripts report new experimental data for future sources, loading and climate impacts on phosphorus.

Central venous catheter integrity during mechanical power injection of iodinated contrast medium

PURPOSE: To evaluate a widely used nontunneled triple-lumen central venous catheter in order to determine whether the largest of the three lumina (16 gauge) can tolerate high flow rates, such as those required for computed tomographic angiography. MATERIALS AND METHODS: Forty-two catheters were tested in vitro, including 10 new and 32 used catheters (median indwelling time, 5 days). Injection pressures were continuously monitored at the site of the 16-gauge central venous catheter hub. Catheters were injected with 300 and 370 mg of iodine per milliliter of iopamidol by using a mechanical injector at increasing flow rates until the catheter failed. The infusion rate, hub pressure, and location were documented for each failure event. The catheter pressures generated during hand injection by five operators were also analyzed. Mean flow rates and pressures at failure were compared by means of two-tailed Student t test, with differences considered significant at P < .05. RESULTS: Injections of iopamidol with 370 mg of iodine per milliliter generate more pressure than injections of iopamidol with 300 mg of iodine per milliliter at the same injection rate. All catheters failed in the tubing external to the patient. The lowest flow rate at which catheter failure occurred was 9 mL/sec. The lowest hub pressure at failure was 262 pounds per square inch gauge (psig) for new and 213 psig for used catheters. Hand injection of iopamidol with 300 mg of iodine per milliliter generated peak hub pressures ranging from 35 to 72 psig, corresponding to flow rates ranging from 2.5 to 5.0 mL/sec. CONCLUSION: Indwelling use has an effect on catheter material property, but even for used catheters there is a substantial safety margin for power injection with the particular triple-lumen central venous catheter tested in this study, as the manufacturer's recommendation for maximum pressure is 15 psig.

Performance analysis of a miniature turbine generator for intracorporeal energy harvesting

Replacement intervals of implantable medical devices are commonly dictated by battery life. Therefore, intracorporeal energy harvesting has the potential to reduce the number of surgical interventions by extending the life cycle of active devices. Given the accumulated experience with intravascular devices such as stents, heart valves, and cardiac assist devices, the idea to harvest a small fraction of the hydraulic energy available in the cardiovascular circulation is revisited. The aim of this article is to explore the technical feasibility of harvesting 1 mW electric power using a miniature hydrodynamic turbine powered by about 1% of the cardiac output flow in a peripheral artery. To this end, numerical modelling of the fluid mechanics and experimental verification of the overall performance of a 1:1 scale friction turbine are performed in vitro. The numerical flow model is validated for a range of turbine configurations and flow conditions (up to 250 mL/min) in terms of hydromechanic efficiency; up to 15% could be achieved with the nonoptimized configurations of the study. Although this article does not entail the clinical feasibility of intravascular turbines in terms of hemocompatibility and impact on the circulatory system, the numerical model does provide first estimates of the mechanical shear forces relevant to blood trauma and platelet activation. It is concluded that the time-integrated shear stress exposure is significantly lower than in cardiac assist devices due to lower flow velocities and predominantly laminar flow.

The brain’s default state interacts with working memory processes in a complex and load-dependent manner

Recently, many studies about a network active during rest and deactivated during tasks emerged in the literature: the default mode network (DMN). Spatial and temporal DMN features are important markers for psychiatric diseases. Another prominent indicator of cognitive functioning, yielding information about the mental condition in health and disease, is working memory (WM) processing. In EEG studies, frontal-midline theta power has been shown to increase with load during WM retention in healthy subjects. From these findings, the conclusion can be drawn that an increase in resting state DMN activity may go along with an increase in theta power in high-load WM conditions. We followed this hypothesis in a study on 17 healthy subjects performing a visual Sternberg WM task. The DMN was obtained by a BOLD-ICA approach and its dynamics represented by the percent-strength during pre-stimulus periods. DMN dynamics were temporally correlated with EEG theta spectral power from retention intervals. This so-called covariance mapping yielded the spatial distribution of the theta EEG fluctuations associated with the dynamics of the DMN. In line with previous findings, theta power was increased at frontal-midline electrodes in high- versus low-load conditions during early WM retention. However, load-dependent correlations of DMN with theta power resulted in primarily positive correlations in low-load conditions, while during high-load conditions negative correlations of DMN activity and theta power were observed at frontal-midline electrodes. This DMN-dependent load effect reached significance during later retention. Our results show a complex and load-dependent interaction of pre-stimulus DMN activity and theta power during retention, varying over the course of the retention period. Since both, WM performance and DMN activity, are markers of mental health, our results could be important for further investigations of psychiatric populations.

The brain’s pre-stimulus default state interacts with working memory in a load-dependent manner

Recently, multiple studies showed that spatial and temporal features of a task-negative default mode network (DMN) (Greicius et al., 2003) are important markers for psychiatric diseases (Balsters et al., 2013). Another prominent indicator of cognitive functioning, yielding information about the mental condition in health and disease, is working memory (WM) processing. In EEG and MEG studies, frontal-midline theta power has been shown to increase with load during WM retention in healthy subjects (Brookes et al., 2011). Negative correlations between DMN activity and theta amplitude have been found during resting state (Jann et al., 2010) as well as during WM (Michels et al., 2010). Likewise, WM training resulted in higher resting state theta power as well as increased small-worldness of the resting brain (Langer et al., 2013). Further, increased fMRI connectivity between nodes of the DMN correlated with better WM performance (Hampson et al., 2006). Hence, the brain’s default state might influence it’s functioning during task. We therefore hypothesized correlations between pre-stimulus DMN activity and EEG-theta power during WM maintenance, depending on the WM load. 17 healthy subjects performed a Sternberg WM task while being measured simultaneously with EEG and fMRI. Data was recorded within a multicenter-study: 12 subjects were measured in Zurich with a 64-channels MR-compatible system (Brain Products) in a 3T Philips scanner, 5 subjects with a 96-channel MR-compatible system (Brain Products) in a 3T Siemens Scanner in Bern. The DMN components was obtained by a group BOLD-ICA approach over the full task duration (figure 1). The subject-wise dynamics were obtained by back-reconstructed onto each subject’s fMRI data and normalized to percent signal change values. The single trial pre-stimulus-DMN activation was then temporally correlated with the single trial EEG-theta (3-8 Hz) spectral power during retention intervals. This so-called covariance mapping (Jann et al., 2010) yielded the spatial distribution of the theta EEG fluctuations during retention associated with the dynamics of the pre-stimulus DMN. In line with previous findings, theta power was increased at frontal-midline electrodes in high- versus low-load conditions during early WM retention (figure 2). However, correlations of DMN with theta power resulted in primarily positive correlations in low-load conditions, while during high-load conditions negative correlations of DMN activity and theta power were observed at frontal-midline electrodes. This DMN-dependent load effect reached significance in the middle of the retention period (TANOVA, p<0.05) (figure 3). Our results show a complex and load-dependent interaction of pre-stimulus DMN activity and theta power during retention, varying over time. While at a more global, load-independent view pre-stimulus DMN activity correlated positively with theta power during retention, the correlation was inversed during certain time windows in high-load trials, meaning that in trials with enhanced pre-stimulus DMN activity theta power decreases during retention. Since both WM performance and DMN activity are markers of mental health our results could be important for further investigations of psychiatric populations.

ISVI-IUA consensus document - diagnostic guidelines on vascular anomalies: vascular malformations and hemangiomas.

The diagnostic approach to vascular anomalies should include the distinction between vascular tumors (i.e. hemangiomas) and congential vascular malformations (CVMs). This step is based more on history and clinical examination rather than on instrumental evaluation. In children Duplex ultrasound and histology can be helpful to separate hypervasularized tumors from CVMs. Appropriate record of objective measures as size or flow volume is required in order to evaluate the progress of the pathology and/or to assess the results of adopted therapeutic interventions. The anatomic, pathological and hemodynamic characteristics, the secondary effects on the surrounding tissues and the systemic manifestations should be defined. Basic diagnostic tools are Duplex sonography followed by MRI or CT scanning. The definition of the vascular anomaly should be according to the Hamburg classification and should separate vascular tumors from vacular malformations followed by separation of high flow from low flow CVMs. Diagnostic investigations are best undertaken at centers where subsequent therapeutic interventions will be performed.

Autonomy as a protective factor against the detrimental effects of ego depletion on tennis serve accuracy under pressure

It has been repeatedly demonstrated that athletes in a state of ego depletion do not perform up to their capabilities. We assume that autonomous self-control exertion, in contrast to forced self-control exertion, can serve as a buffer against ego depletion effects and can help individuals to show superior performance. In the present study, we applied a between-subjects design to test the assumption that autonomously exerted self-control is less detrimental for subsequent self-control performance in sports than is forced self-control exertion. In a primary self-control task, the level of autonomy was manipulated through specific instructions, resulting in three experimental conditions (autonomy-supportive: n = 19; neutral: n = 19; controlling: n = 19). As a secondary self-control task, participants executed a series of tennis serves under high-pressure conditions, and performance accuracy served as our dependent variable. As expected, a one-way between-groups ANOVA revealed that participants from the autonomy-supportive condition performed significantly better under pressure than did participants from the controlling condition. These results further highlight the importance of autonomy-supportive instructions in order to enable athletes to show superior achievements in high-pressure situations. Practical implications for the coach–athlete relationship are discussed.

Laminar and turbulent nozzle-jet flows and their acoustic near-field

We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re D = 18 100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

Extreme River Floods in Western Switzerland and the Lake of Constance Region in the Period Prior to Instrumental Measurements

The floods that occurred on the Aare and Rhine rivers in May 2015 and the mostly successful handling of this event in terms of flood protection measures are a good reminder of how important it is to comprehend the causes and processes involved in such natural hazards. While the needed data series of gauge measurements and peak discharge calculations reach back to the 19th century, historical records dating further back in time can provide additional and useful information to help understanding extreme flood events and to evaluate prevention measures such as river dams and corrections undertaken prior to instrumental measurements. In my PhD project I will use a wide range of historical sources to assess and quantify past extreme flood events. It is part of the SNF-funded project “Reconstruction of the Genesis, Process and Impact of Major Pre-instrumental Flood Events of Major Swiss Rivers Including a Peak Discharge Quantification” and will cover the research locations Fribourg (Saane R.), Burgdorf (Emme R.), Thun, Bern (both Aare R.), and the Lake of Constance at the locations Lindau, Constance and Rorschach. My main goals are to provide a long time series of quantitative data for extreme flood events, to discuss the occurring changes in these data, and to evaluate the impact of the aforementioned human influences on the drainage system. Extracting information given in account books from the towns of Basel and Solothurn may also enable me to assess the frequency and seasonality of less severe river floods. Finally, historical information will be used for remodeling the historical hydrological regime to homogenize the historical data series to modern day conditions and thus make it comparable to the data provided by instrumental measurements. The method I will apply for processing all information provided by historical sources such as chronicles, newspapers, institutional records, as well as flood marks, paintings and archeological evidence has been developed and successfully applied to the site of Basel by Wetter et al. (2011). They have also shown that data homogenization is possible by reconstructing previous stream flow conditions using historical river profiles and by carefully observing and re-constructing human changes of the river bed and its surroundings. Taken all information into account, peak discharges for past extreme flood events will be calculated with a one-dimensional hydrological model.

Tomographic PIV behind a prosthetic heart valve

The instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry (PIV). Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis.

Rotating dust particles in the coma of comet 67P/Churyumov-Gerasimenko

Context. During September and October 2014, the OSIRIS cameras onboard the ESA Rosetta mission detected millions of single particles. Many of these dust particles appear as long tracks (due to both the dust proper motion and the spacecraft motion during the exposure time) with a clear brightness periodicity. Aims. We interpret the observed periodic features as a rotational and translational motion of aspherical dust grains. Methods. By counting the peaks of each track, we obtained statistics of a rotation frequency. We compared these results with the rotational frequency predicted by a model of aspherical dust grain dynamics in a model gas flow. By testing many possible sets of physical conditions and grain characteristics, we constrained the rotational properties of dust grains. Results. We analyzed on the motion of rotating aspherical dust grains with different cross sections in flow conditions corresponding to the coma of 67P/Churyumov-Gerasimenko qualitatively and quantitatively. Based on the OSIRIS observations, we constrain the possible physical parameters of the grains.

Environmental correlates of species rank − abundance distributions in global drylands

Theoretical models predict lognormal species abundance distributions (SADs) in stable and productive environments, with log-series SADs in less stable, dispersal driven communities. We studied patterns of relative species abundances of perennial vascular plants in global dryland communities to: (i) assess the influence of climatic and soil characteristics on the observed SADs, (ii) infer how environmental variability influences relative abundances, and (iii) evaluate how colonisation dynamics and environmental filters shape abundance distributions. We fitted lognormal and log-series SADs to 91 sites containing at least 15 species of perennial vascular plants. The dependence of species relative abundances on soil and climate variables was assessed using general linear models. Irrespective of habitat type and latitude, the majority of the SADs (70.3%) were best described by a lognormal distribution. Lognormal SADs were associated with low annual precipitation, higher aridity, high soil carbon content, and higher variability of climate variables and soil nitrate. Our results do not corroborate models predicting the prevalence of log-series SADs in dryland communities. As lognormal SADs were particularly associated with sites with drier conditions and a higher environmental variability, we reject models linking lognormality to environmental stability and high productivity conditions. Instead our results point to the prevalence of lognormal SADs in heterogeneous environments, allowing for more evenly distributed plant communities, or in stressful ecosystems, which are generally shaped by strong habitat filters and limited colonisation. This suggests that drylands may be resilient to environmental changes because the many species with intermediate relative abundances could take over ecosystem functioning if the environment becomes suboptimal for dominant species.

An extracytoplasmic function sigma factor operon regulates Myxococcus xanthus developmental gene expression

Myxococcus xanthus is a Gram-negative soil bacterium that undergoes multicellular development when high-density cells are starved on a solid surface. Expression of the 4445 gene, predicted to encode a periplasmic protein, commences 1.5 h after the initiation of development and requires starvation and high density conditions. Addition of crude or boiled supernatant from starving high-density cells restored 4445 expression to starving low-density cells. Addition of L-threonine or L-isoleucine to starving low-density cells also restored 4445 expression, indicating that the high-density signaling activity present in the supernatant might be composed of extracellular amino acids or small peptides. To investigate the circuitry integrating these starvation and high-density signals, the cis- and trans-acting elements controlling 4445 expression were identified. The 4445 transcription start site was determined by primer extension analysis to be 58 by upstream of the predicted translation start site. The promoter region contained a consensus sequence characteristic of e&barbelow;xtrac&barbelow;ytoplasmic f&barbelow;unction (ECF) sigma factor-dependent promoters, suggesting that 4445 expression might be regulated by an ECF sigma factor-dependent pathway, which are known to respond to envelope stresses. The small size of the minimum regulatory region, identified by 5′-end deletion analysis as being only 66 by upstream of the transcription start site, suggests that RNA polymerase could be the sole direct regulator of 4445 expression. To identify trans-acting negative regulators of 4445 expression, a strain containing a 4445-lacZ was mutagenized using the Himar1-tet transposon. The four transposon insertions characterized mapped to an operon encoding a putative ECF sigma factor, ecfA; an anti-sigma factor, reaA; and a negative regulator, reaB. The reaA and the reaB mutants expressed 4445 during growth and development at levels almost 100-fold higher than wild type, indicating that these genes encode negative regulators. The ecfA mutant expressed 4445-lacZ at basal levels, indicating that ecfA is a positive regulator. High Mg2+ concentrations over-stimulated this ecfA pathway possibly due to the depletion of exopolysaccharides and assembled type IV pili. These data indicate that the ecfA operon encodes a new regulatory stress pathway that integrates and transduces starvation and cell density cues during early development and is also responsive to cell-surface alterations.^

Diversity in T cell costimulation by alpha4beta1 integrin

T cell activation requires antigen-specific T cell receptor signals that spatially and temporally coincide with a second costimulatory signal. CD28 and α4β1 integrin both function as T cell costimulators, but their individual mechanisms remain elusive. By directly comparing CD3-dependent functions and signaling pathways employed by these two costimulatory receptors, aspects of their individual signaling mechanisms are explored. We determined that CD28 and α4β1 integrins both use Src-family kinase Lck and MAPK Erk, but to different extents and functional ends. After identifying functional differences between CD28 and integrin costimulatory pathways, the focus of the study turned to integrin signaling in naïve and memory T cell subsets. CD45RO T cells are fully co-activated by natural β1 integrin ligands fibronectin (FN) and VCAM-1, β1 monoclonal antibody 33B6, as well as α4β1 monoclonal antibody 19H8 which binds a combinatorial epitope of the α4β1 heterodimer. While CD28 fully costimulates CD45RA T cells, the degree of activation from integrin ligands varies. FN costimulates CD3-dependent proliferation, IL-2 secretion, and early activation markers CD25 and CD69. However, β1 antibody 33B6, which binds to the same T cell integrins (α4β1 and α5β1) as natural ligand FN, failed to costimulate proliferation or IL-2 in the CD45RA subset, but retained the ability to regulate CD25 and CD69. Unique aspects of 19H8 signaling involve early Erk activation and IL-2 independent proliferation. Signaling defects through 33B6 ligation correlates with poor adhesion under fluid flow conditions, suggesting a cytoskeletal basis for signaling. All together, these data provide evidence for a mechanism of α4β1 integrin signaling and describe functional differences between naïve and memory T cells. ^

Organization and function of platelet glycoprotein Ib-IX complex

Glycoprotein (GP) Ib-IX complex, the second most abundant receptor expressed on the platelet surface, plays critical roles in haemostasis and thrombosis by binding to its ligand, von Willebrand factor (vWF). Defect or malfunction of the complex leads to severe bleeding disorders, heart attack or stroke. Comprised of three type I transmembrane subunits—GPIbα, GPIbβ and GPIX, efficient expression of the GPIb-IX complex requires all three subunits, as evident from genetic mutations identified in the patients and reproduced in transfected Chinese hamster ovary (CHO) cells. However, how the subunits are assembled together and how the complex function is regulated is not fully clear. By probing the interactions among the three subunits in transfected cells, we have demonstrated that the transmembrane domains of the three subunits interact with one another, facilitating formation of the two membrane-proximal disulfide bonds between GPIbα and GPIbβ. We have also identified the interface between extracellular domains of GPIbβ and GPIX, and provided evidence suggesting a direct interaction between extracellular domains of GPIbα and GPIX. All of these interactions are not only critical for correct assembly and consequently efficient expression of the GPIb-IX complex on the cell surface, but also for its function, such as the proper ligand binding, since removing the two inter-subunit disulfide bonds significantly hampers vWF binding to the complex under both static and physiological flow conditions. The two inter-subunit disulfide bonds are also critical for regulating the ectodomain shedding of GPIbα by the GPIbβ cytoplasmic domain. Mutations in the juxtamembrane region of the GPIbβ cytoplasmic domain deregulate GPIbα shedding, and such deregulation is further enhanced when the two inter-subunit disulfide bonds are removed. In summary, we have established the overall organization of the GPIb-IX complex, and the importance of proper organization on its function. ^