English: Clostridium difficile is an emerging anaerobic, spore forming pathogen, recognized as the etiological agent of ~ 30% of antibiotic associated diarrheas. Clinical symptoms can fluctuate from mild to moderate diarrhea, pseudomembranous colitis and toxic megacolon. The incidence of C. difficile associated infections (CDAI) is ~ 1% of total hospitalized...
The most frequent cause of pseudomembranous colitis is Clostridium difficile (C. difficile) infection. This type of colitis is characterized by an endoscopic pattern of numerous small, yellowish or whitish plaques diffusely distributed, which typically compromises the rectum extending to proximal colon. Occasionally, the pseudomembranes compromise only the transverse or right...
The increased severity of Clostridium difficile infection is primarily attributed to the appearance of an epidemic strain characterized as PCR ribotype 027. The only report that identified epidemic C. difficile ribotype 027 in an American country outside of North America comes from Costa Rica, raising the possibility that strains 027...
Anthropogenic modification watersheds and climate change have altered export from fluvial systems causing changes to the carbonate chemistry of river-influenced near shore environments. To determine the possible effects of riverine discharges on the mussel Perumytilus purpuratus, we performed in situ transplant experiments between river-influenced and open coastal habitats with contrasting...
Knowledge about the genetic underpinnings of invasions—a theme addressed by invasion genetics as a discipline—is still scarce amid well documented ecological impacts of non-native species on ecosystems of Patagonia in South America. One of the most invasive species in Patagonia’s freshwater systems and elsewhere is rainbow trout (Oncorhynchus mykiss). This...
Freshwater discharge affects the biogeochemistry of river-influenced nearshore environments by contributing with carbon and nutrients. An increase in human activities in river basins may alter the natural riverine nutrients and carbon export to coastal ecosystems. Along a wide latitudinal range (32° 55'S-40° 10'S), this study explores the role of climate...
The following dissertation consists of six sections: a general introduction, three manuscripts, a general conclusion, and an overall bibliography. The three manuscripts report on: (1) identifying genetic interactions in diverse germplasm developed during introgression of a major gene conferring resistance to stem rust (Puccinia graminis f. sp. tritici), (2) mapping...
Fluorescent proteins (FPs) are luminescent biomolecules that emit characteristic hues upon irradiation. A group of calmodulin (CaM)-green FP (GFP) chimeras have been previously engineered to enable the optical detection of calcium ions (Ca²⁺). We investigate one of these genetically encoded Ca²⁺ biosensors for optical imaging (GECOs), GEM-GECO1, which fluoresces green...
Analysis of observations on sequential events over time is common in real life. Sequential measurements over time describing the behavior of systems are usually called time series data, which have been collected in a wide range of disciplines. Over the years there have been multiple research areas in studying stochastic...
The dissertation focuses on the engineering of light-matter interaction using plasmonic nanoparticles and metamaterials to achieve enhanced luminescence and based on which to improve the performance of biosensing and light-emitting technologies. We designed and fabricated a spectrum of nanostructures to exhibit particular dispersion relations capable of controlling the spontaneous emission...
Biological invasions create complex ecological
and societal issues worldwide. Most of the
knowledge about invasions comes only from successful
invaders, but less is known about which processes
determine the differential success of invasions. In this
review, we develop a framework to identify the main
dimensions driving the success and failure...
Real-world datasets are dirty and contain many errors. Examples of these issues are violations of integrity constraints, duplicates, and inconsistencies in representing data values and entities. Applying machine learning on dirty databases may lead to inaccurate results. Users have to spend a lot of time and effort repairing data errors...
Femtosecond stimulated Raman spectroscopy (FSRS) is a powerful ultrafast technique which can track photoinduced excited state structural events on femtosecond (fs) to picosecond (ps) timescales. In addition to high temporal and spectral resolutions, FSRS provides a broad spectral window from ca. 100—2000 cm-1 for detection, enabling the direct mapping of...
Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast vibrational technique which allows rapid collection of Raman spectra with simultaneously high temporal and spectral resolution. With the recent development of FSRS methodology, three FSRS techniques (conventional, tunable, and anti-Stokes) have been implemented in our laboratory to dissect the excited state structural...
Three analytical methods for determination of aroma compounds in alcoholic beverages were developed and validated. These methods are sensitive and reliable that can be applied to analyze volatile phenols, stale aldehydes as well as some highly volatile aromas in alcoholic beverages. In the first study, an ethylene glycol (EG) polydimethylsiloxane...
Photoactivated biomedical tools like fluorescent biosensors and optogenetic proteins have increased in popularity due to the precision targeting and activation used for in vivo applications. In nature, the initially discovered parent proteins exhibit properties such as fluorescence quantum yield (FQY), fluorescence color, and photoswitching dynamics that are unfavorable in mammalian...
Fungi from the genus Chlorociboria are known for their production of the blue-green quinonic pigment xylindein. Extracted xylindein has been the subject of investigations ranging from fabric dying to use a coloring agent in paint, and shows potential as an organic semiconductor in organic photovoltaics (OPVs) and other technologies. However,...
In the wake of the ``third wave'' of democratization, scholars and practitioners were optimistic regarding the ease with which countries could adopt democratic norms and institutions. However, after four decades of democracy, many competitive regimes have not improved government probity or developed strong forms of accountability. Levels of economic and...
Hop (Humulus lupulus L. var. lupulus) is a diploid, dioecious plant with an extensive history of cultivation and use in brewing, as a textile, and for its therapeutic properties. Hop is prized for its ability to produce a variety of aromatic and flavor compounds, as well as compounds with anti-microbial...
Learning novel concepts from relational databases is an important problem with applications in several disciplines, such as data management, natural language processing, and bioinformatics. For a learning algorithm to be effective, the input data should be clean and in some desired representation. However, real-world data is usually heterogeneous – the...