Reduced organic sulfur: Analysis and interaction with mercury in the aquatic environment

Reduced organic sulfur (ROS) compounds are environmentally ubiquitous and play an important role in sulfur cycling as well as in biogeochemical cycles of toxic metals, in particular mercury. Development of effective methods for analysis of ROS in environmental samples and investigations on the interactions of ROS with mercury are critical for understanding the role of ROS in mercury cycling, yet both of which are poorly studied. Covalent affinity chromatography-based methods were attempted for analysis of ROS in environmental water samples. A method was developed for analysis of environmental thiols, by preconcentration using affinity covalent chromatographic column or solid phase extraction, followed by releasing of thiols from the thiopropyl sepharose gel using TCEP and analysis using HPLC-UV or HPLC-FL. Under the optimized conditions, the detection limits of the method using HPLC-FL detection were 0.45 and 0.36 nM for Cys and GSH, respectively. Our results suggest that covalent affinity methods are efficient for thiol enrichment and interference elimination, demonstrating their promising applications in developing a sensitive, reliable, and useful technique for thiol analysis in environmental water samples. The dissolution of mercury sulfide (HgS) in the presence of ROS and dissolved organic matter (DOM) was investigated, by quantifying the effects of ROS on HgS dissolution and determining the speciation of the mercury released from ROS-induced HgS dissolution. It was observed that the presence of small ROS (e.g., Cys and GSH) and large molecule DOM, in particular at high concentrations, could significantly enhance the dissolution of HgS. The dissolved Hg during HgS dissolution determined using the conventional 0.22 μm cutoff method could include colloidal Hg (e.g., HgS colloids) and truly dissolved Hg (e.g., Hg-ROS complexes). A centrifugal filtration method (with 3 kDa MWCO) was employed to characterize the speciation and reactivity of the Hg released during ROS-enhanced HgS dissolution. The presence of small ROS could produce a considerable fraction (about 40% of total mercury in the solution) of truly dissolved mercury (< 3 kDa), probably due to the formation of Hg-Cys or Hg-GSH complexes. The truly dissolved Hg formed during GSH- or Cys-enhanced HgS dissolution was directly reducible (100% for GSH and 40% for Cys) by stannous chloride, demonstrating its potential role in Hg transformation and bioaccumulation.

Factors associated with social work student satisfaction with field placements in child welfare by Diane Elias Alperin.

This study was conducted during the 1994-1995 academic year. Seven social work education programs in the state of Florida, all accredited by the Council on Social Work Education, participated in this study. Graduate and undergraduate social work students in child welfare field placements, and their field instructors, were surveyed during the Spring 1995 semester to assess their satisfaction with field placements ii this area and the relationship of this satisfaction to employment interests and field placement recommendations. The majority of social work students responding to this survey were generally satisfied with several aspects of their field placements--the learning, field work program, field instructor, child welfare agency, and overall field experience. The field instructors were generally more satisfied than the students, but only statistically different from the students in the areas of satisfaction with the field work program and the child welfare agency. Multiple regression analysis revealed that learning assignment opportunities, field instructor relationship characteristics, placement preference, and pre-placement interview contributed to the prediction of student satisfaction. Student satisfaction in field placement was significantly related to the acceptance of employment, if offered, and the recommendation of the field placement to other students. Logistic regression analysis revealed that satisfaction with the child welfare agency was the greatest contributor to the prediction of acceptance of employment, and satisfaction with the field work program was the greatest contributor to the prediction of field placement recommendation.

beta-Arrestin1 modulates lymphoid enhancer factor transcriptional activity through interaction with phosphorylated dishevelled proteins.

One aspect of the function of the beta-arrestins is to serve as scaffold or adapter molecules coupling G-protein coupled receptors (GPCRs) to signal transduction pathways distinct from traditional second messenger pathways. Here we report the identification of Dishevelled 1 and Dishevelled 2 (Dvl1 and Dvl2) as beta-arrestin1 (betaarr1) interacting proteins. Dvl proteins participate as key intermediates in signal transmission from the seven membrane-spanning Frizzled receptors leading to inhibition of glycogen synthase kinase-3beta (GSK-3beta), stabilization of beta-catenin, and activation of the lymphoid enhancer factor (LEF) transcription factor. We find that phosphorylation of Dvl strongly enhances its interaction with betaarr1, suggesting that regulation of Dvl phosphorylation and subsequent interaction with betaarr1 may play a key role in the activation of the LEF transcription pathway. Because coexpression of the Dvl kinases, CK1epsilon and PAR-1, with Dvl synergistically activates LEF reporter gene activity, we reasoned that coexpression of betaarr1 with Dvl might also affect LEF-dependent gene activation. Interestingly, whereas betaarr1 or Dvl alone leads to low-level stimulation of LEF (2- to 5-fold), coexpression of betaarr1 with either Dvl1 or Dvl2 leads to a synergistic activation of LEF (up to 16-fold). Additional experiments with LiCl as an inhibitor of GSK-3beta kinase activity indicate that the step affected by betaarr1 is upstream of GSK-3beta and most likely at the level of Dvl. These results identify betaarr1 as a regulator of Dvl-dependent LEF transcription and suggest that betaarr1 might serve as an adapter molecule that can couple Frizzled receptors and perhaps other GPCRs to these important transcription pathways.

A New Method for Modeling Free Surface Flows and Fluid-structure Interaction with Ocean Applications

The computational modeling of ocean waves and ocean-faring devices poses numerous challenges. Among these are the need to stably and accurately represent both the fluid-fluid interface between water and air as well as the fluid-structure interfaces arising between solid devices and one or more fluids. As techniques are developed to stably and accurately balance the interactions between fluid and structural solvers at these boundaries, a similarly pressing challenge is the development of algorithms that are massively scalable and capable of performing large-scale three-dimensional simulations on reasonable time scales. This dissertation introduces two separate methods for approaching this problem, with the first focusing on the development of sophisticated fluid-fluid interface representations and the second focusing primarily on scalability and extensibility to higher-order methods.

We begin by introducing the narrow-band gradient-augmented level set method (GALSM) for incompressible multiphase Navier-Stokes flow. This is the first use of the high-order GALSM for a fluid flow application, and its reliability and accuracy in modeling ocean environments is tested extensively. The method demonstrates numerous advantages over the traditional level set method, among these a heightened conservation of fluid volume and the representation of subgrid structures.

Next, we present a finite-volume algorithm for solving the incompressible Euler equations in two and three dimensions in the presence of a flow-driven free surface and a dynamic rigid body. In this development, the chief concerns are efficiency, scalability, and extensibility (to higher-order and truly conservative methods). These priorities informed a number of important choices: The air phase is substituted by a pressure boundary condition in order to greatly reduce the size of the computational domain, a cut-cell finite-volume approach is chosen in order to minimize fluid volume loss and open the door to higher-order methods, and adaptive mesh refinement (AMR) is employed to focus computational effort and make large-scale 3D simulations possible. This algorithm is shown to produce robust and accurate results that are well-suited for the study of ocean waves and the development of wave energy conversion (WEC) devices.

Integrase mutants defective for interaction with LEDGF/p75 are impaired in chromosome tethering and HIV-1 replication

The insertion of a DNA copy of its RNA genome into a chromosome of the host cell is mediated by the viral integrase with the help of mostly uncharacterized cellular cofactors. We have recently described that the transcriptional co-activator LEDGF/p75 strongly interacts with HIV-1 integrase. Here we show that interaction of HIV-1 integrase with LEDGF/p75 is important for viral replication. Using multiple approaches including two-hybrid interaction studies, random and directed mutagenesis, we could demonstrate that HIV-1 virus harboring a single mutation that disrupts integrase-LEDGF/p75 interaction, resulted in defective HIV-1 replication. Furthermore, we found that LEDGF/p75 tethers HIV-1 integrase to chromosomes and that this interaction may be important for the integration process and the replication of HIV-1.

Docking of HIV-1 Vpr to the nuclear envelope is mediated by the interaction with the nucleoporin hCG1

The HIV-1 genome contains several genes coding for auxiliary proteins, including the small Vpr protein. Vpr affects the integrity of the nuclear envelope and participates in the nuclear translocation of the preintegration complex containing the viral DNA. Here, we show by photobleaching experiments performed on living cells expressing a Vpr-green fluorescent protein fusion that the protein shuttles between the nucleus and the cytoplasm, but a significant fraction is concentrated at the nuclear envelope, supporting the hypothesis that Vpr interacts with components of the nuclear pore complex. An interaction between HIV-1 Vpr and the human nucleoporin CG1 (hCG1) was revealed in the yeast two-hybrid system, and then confirmed both in vitro and in transfected cells. This interaction does not involve the FG repeat domain of hCG1 but rather the N-terminal region of the protein. Using a nuclear import assay based on digitonin-permeabilized cells, we demonstrate that hCG1 participates in the docking of Vpr at the nuclear envelope. This association of Vpr with a component of the nuclear pore complex may contribute to the disruption of the nuclear envelope and to the nuclear import of the viral DNA.

EMR Interaction with Water

Resources created at the University of Southampton for the module Remote Sensing for Earth Observation

EMR Interaction with Water

Resources created at the University of Southampton for the module Remote Sensing for Earth Observation

Effects of copper on the photosynthesis of intact chloroplasts: interaction with manganese

Highly purified, intact chloroplasts were prepared from pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) following an identical procedure, and were used to investigate the cupric cation inhibition on the photosynthetic activity. In both species, copper inhibition showed a similar inhibitor concentration that decreases the enzyme activity by 50% (IC(50) approximately 1.8 microM) and did not depend on the internal or external phosphate (Pi) concentration, indicating that copper did not interact with the Pi translocator. Fluorescence analysis suggested that the presence of copper did not facilitate photoinhibition, because there were no changes in maximal fluorescence (F(m)) nor in basal fluorescence (F(o)) of copper-treated samples. The electron transport through the photosystem II (PSII) was also not affected (operating efficiency of PSII-F'v/F'm similar in all conditions). Yet, under Cu(2+) stress, the proportion of open PSII reaction centers was dramatically decreased, and the first quinone acceptor (Q(A)) reoxidation was fully inhibited, as demonstrated by the constant photochemical quenching (q(P)) along experiment time. The quantum yield of PSII electron transport (Phi(PSII)) was also clearly affected by copper, and therefore reduced the photochemistry efficiency. Manganese, when added simultaneously with copper, delayed the inhibition, as measured by oxygen evolution and chlorophyll fluorescence, but neither reversed the copper effect when added to copper-inhibited plastids, nor prevented the inhibition of the Hill activity of isolated copper-treated thylakoids. Our results suggest that manganese competed with copper to penetrate the chloroplast envelope. This competition seems to be specific because other divalent cations e.g. magnesium and calcium, did not interfere with the copper action in intact chloroplasts. All results do suggest that, under these conditions, the stroma proteins, such as the Calvin-Benson cycle enzymes or others are the most probable first target for the Cu(2+) action, resulting in the total inhibition of chloroplast photosynthesis and in the consequent unbalanced rate of production and consumption of the reducing power.

Impact of Cryptosporidium spp. interaction with co-occurring microorganisms on moderate-to-severe diarrhea in the developing world

Diarrheal illness is responsible for over a quarter of all deaths in children under 5 years of age in sub-Saharan Africa and South Asia. Recent findings have identified the parasite Cryptosporidium as a contributor to enteric disease. We examined 9,348 cases and 13,128 controls from the Global Enteric Multicenter Study to assess whether Cryptosporidium interacted with co-occurring pathogens based on adjusted odds of moderate-to-severe diarrhea (MSD). Cryptosporidium was found to interact negatively with Shigella spp., with multiplicative interaction score of 0.16 (95% CI: 0.07 to 0.37, p-value=0.000), and an additive interaction score of -9.81 (95% CI: -13.61 to -6.01, p-value=0.000). Cryptosporidium also interacted negatively with Aeromonas spp., Adenovirus, Norovirus, and Astrovirus with marginal significance. Odds of MSD for Cryptosporidium co-infection with Shigella spp., Aeromonas spp., Adenovirus, Norovirus, or Astrovirus are lower than odds of MSD with either organism alone. This may reduce the efficacy of intervention strategies targeted at Cryptosporidium.

The Emergence of Spanish Impressionism and its Interaction with French Impressionism in Music at the Turn of the Twentieth Century: selections from the solo and collaborative piano repertoire

French Impressionism is a term which is often used in discussing music originating in France towards the end of the nineteenth century. The term Spanish Impressionism could also be used when discussing Spanish music written by the Spanish composers who studied and worked in Paris at the same time as their French counterparts. After all, Spanish music written during this time exhibits many of the same characteristics and aesthetics as French music of the same era. This dissertation will focus on the French and Spanish composers writing during that exciting time. Musical impressionism emphasizes harmonic effects and rhythmic fluidity in the pursuit of evocative moods, sound pictures of nature or places over the formalism of structure and thematic concerns. The music of this time is highly virtuosic as well as musically demanding, since many of the composers were brilliant pianists. My three dissertation recitals concentrated on works which exhibited the many facets of impressionism as well as the technical and musical challenges. The repertoire included selections by Spanish composers Manuel de Falla, Isaac Albéniz, Enrique Granados, Joaquín Turina, and Joaquín Rodrigo and French composers Claude Debussy and Maurice Ravel. The recitals were on April 30, 2013, February 23, 2014 and October 11, 2015. They included solo piano works by Granados and Albéniz, vocal works by Debussy, Ravel, de Falla, Turina and Rodrigo, piano trios by Granados and Turina, instrumental duos by Debussy, Ravel and de Falla, and a two-piano work of Debussy transcribed by Ravel. All three recitals were held in Gildenhorn Recital Hall at the University of Maryland and copies of this dissertation and recordings of each recital may be found through the Digital Repository at the University of Maryland (DRUM).

An evaluation of a sketching interface for interaction with concatenative sound synthesis.

This paper presents the evaluation of morpheme a sketching interface for the control of sound synthesis. We explain the task that was designed in order to assess the effectiveness of the interface, detect usability issues and gather participants’ responses regarding cognitive, experiential and expressive aspects of the interaction. The evaluation comprises a design task, where partici-pants were asked to design two soundscapes using the morpheme interface for two video footages. Responses were gathered using a series of likert type and open-ended questions. The analysis of the data gathered revealed a number of usability issues, however the performance of morpheme was satisfactory and participants recognised the creative potential of the interface and the synthesis methods for sound design applications.

Intelligent system for interaction with virtual characters based on volumetric sensors

Dissertação de Mestrado, Engenharia Elétrica e Eletrónica, Instituto Superior de Engenharia, Universidade do Algarve, 2015

Enhancing student learning with case-based teaching and audience response systems in an interdisciplinary Food Science course

A growing body of research in higher education suggests that teachers should move away from traditional lecturing towards more active and student-focus education approaches. Several classroom techniques are available to engage students and achieve more effective teaching and better learning experiences. The purpose of this paper is to share an example of how two of them – case-based teaching, and the use of response technologies – were implemented into a graduate-level food science course. The paper focuses in particular on teaching sensory science and sensometrics, including several concrete examples used during the course, and discussing in each case some of the observed outcomes. Overall, it was observed that the particular initiatives were effective in engaging student participation and promoting a more active way of learning. Case-base teaching provided students with the opportunity to apply their knowledge and their analytical skills to complex, real-life scenarios relevant to the subject matter. The use of audience response systems further facilitated class discussion, and was extremely well received by the students, providing a more enjoyable classroom experience.

MEF2C: expression, regulation and interaction with target genes in health and diseases

Tese de doutoramento, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015