PhD

dissertationThe effect of pretreatment with penicillin on para-aminohippurate (PAH) transport by kidney of the immature rat was evaluated in vivo. After 3 days of penicillin administration, the renal clearances of inulin (CIN), PAH(CPAH), and N-methylnicotinamide (CNMN) and the rental tubular transport maximum (Tm) for PAH were measured in rats as young as 17 days of age. The CPAH by 19- to 21-day old rats pretreated with procaine penicillin was 46% greater than that of there litter-mate controls. Similarly, CPAH of rats that received sodium penicillin was 27% greater than control. CIN was not increased after penicillin pretreatment. Pretreatment with penicillin of rats older than 24 days of age did not change CIN or CPAH. The Tm for PAH of 17-day-old rats pretreated with sodium penicillin was 51% greater than that of control rats. Sodium penicillin-pretreated rats had a lower CNMN that did control rats. These results are in contrast with the normal pattern of renal maturation in which CIN, CPAH, and PAH Tm all increase with age. It was concluded that pretreatment with penicillin stimulates the renal secretion of organic anions by the immature rat

Mortgage Terminations: The Role of Conditional Volatility

This article is the winner of the Real Estate Finance manuscript prize (sponsored by Fannie Mae Foundation) presented at the 2001 American Real Estate Society Annual Meeting. Studies of mortgage termination decisions typically rely on a competing risks framework comparing defaults and prepayments. While useful tools have been developed to approximate the values of these competing default and prepayment options, the available metrics do not adequately account for the role of the conditional volatility of interest rates and housing prices in option valuation. Using a sample of 1,428 mortgage loan payment histories, this study finds that exponential GARCH estimates of the conditional volatility of housing prices and interest rates influence mortgage termination decisions in a predictable manner. Specifically, increased housing price volatility is shown to enhance default option values, while increased interest rate volatility is shown to enhance prepayment option values. Therefore, it would appear that conditional volatility represents a more refined input into the competing risks option framework.

Shared and Unique Features of Epistemic Emotions:Awe, Surprise, Curiosity, Interest, Confusion, and Boredom

Epistemic emotions arise when information is complex, unexpected, or in another way not understood. They are responsible for important outcomes related to learning, openness, or exploration. Epistemic emotions are hardly ever studied together, making it difficult to predict what features are shared versus unique to each emotion. To address this, we conducted two autobiographical recall experiments. We compared awe, surprise, curiosity, interest, confusion, and boredom in terms of elicitors, subjective experience components, and actions tendencies. Ratings were analyzed using network analyses, to describe the central components for the whole group of epistemic emotions. In addition, ratings were compared per emotion, to identify key features for each individual emotion. Results showed that valence, arousal, coping potential, and avoidance are central features of all epistemic emotions. Awe, surprise, and interest were relatively positive emotions, which together with curiosity, were associated with arousal, high coping potential, and approach. Confusion and boredom were relatively negative emotions, which were associated with low arousal, low coping potential, and avoidance. Further analyses revealed unique features of (groups of) emotions. For example, awe was associated with exceeded expectancies, while surprise was associated with both exceeded and disconfirmed expectancies. Moreover, curiosity and confusion were associated with having (too) little information, while awe and interest were associated with having sufficient information. All emotions except boredom were associated with exploration, but this was particularly high for curiosity and interest

Evaluation "Angels and Demons" (WP-116)

One way to generate the money needed for sustainable innovation is by consumer choosing freely for sustainable products. This way, consumer choice pays for the innovative production method. This requires consumer willingness to buy these products. Willingness to buy is however not so easily measured as the intentions to buy may only partially predict actual purchase behaviour. There is a gap between what consumer say they want, and what they do in practice. For the specific case of sustainable production, consumers often say they are very positive about sustainable products (angelic opinion), yet in their daily behaviour they frequently tend to choose convenient and cheap products (demonic behaviour)

The dynamics of surprise and curiosity

This dissertation shows that the subjective experience of surprise and curiosity depends on where people are in their process of making sense. Part 1 focusses on surprise. It shows that to study surprise it is key to take the temporal dynamics of sense-making into account and to distinguish surprise (i.e., the response to the unexpectedness of an event) from the state that follows it after sense-making (i.e., the response to the valence of the event). Part 2 focusses on curiosity. It shows that anticipation is a key factor for how it feels to be curious. The closer people are to the resolution, the more they anticipate discovering new information, the more negative feelings of deprivation are reduced. Moreover, the more people anticipate that they can deal with complex novel things, the more curious they will become. Taken together, the findings in this dissertation show that people first need to master a situation of "not knowing" before they can appreciate it.UBL - phd migration 201

Exploring a Putative Promoter Region in Mycobacteriophage JacoRen57

Phages are abundant particles that infect bacteria. For the SEA-PHAGES program, students discover phages and annotate their genomes. Throughout the annotation process, genes are identified based on bioinformatics evidence; however, little is known about mycobacteriophage promoters as they are not annotated. Promoters are necessary for gene expression, and in mycobacteriophages, a promoter typically precedes a series of genes that are expressed as a single transcript from which multiple proteins are translated. JacoRen57 is a singleton mycobacteriophage with a siphoviridae morphotype that possesses forward and reverse genes with gaps located at the transitions from forward to reverse genes. We hypothesized that these gaps contain promoters. We used BPROM and PePPER, prokaryotic promoter predictor software, which yielded matches to promoter consensus sequences in one of the gap regions. We cloned the putative promoter region into pLO86, a vector containing the mCherry reporter gene, to determine if the cloned region functions as a promoter by inducing mCherryexpression in Mycobacterium smegmatis. The putative promoter region did not function as a promoter in vivo under standard M. smegmatisgrowth conditions

Support for those affected by scientific misconduct is crucial

Cases of scientifc misconduct can have a massive impact on scholars (especially junior scholars), and repercussions may last years. They need support, writes Marret K. Noordewier.Social decision makin

Discovering Gene Functions in Mycobacteriophage Sbash Using a Genetic Screen

Sbash is a temperate bacteriophage, which was isolated on the host, Mycobacterium smegmatis mc2 155 from soil collected in South Africa. It is classified as cluster I and sub-cluster I2. Its genome consists of 55,832 base pairs and 89 protein-coding genes of which only 25 genes were assigned a function by bioinformatic analysis. We are using a genetic screen to uncover the functions of phage genes for which function is unknown. To begin to uncover the functions of the protein products of the genes in Sbash’s genome, we cloned each gene into the pExTra plasmid and assayed each phage gene for two phenotypes: cytotoxicity, the ability to interfere with host cell growth, and defense, the ability to protect the host cell from infection by other phages. In total, we successfully cloned approximately half of the genes in Sbash’s genome with sizes ranging from 90 bp to nearly 1500 bp. We identified two Sbash genes that defend host cells from infection by other mycobacteriophages. We identified six genes that reduced the growth of host cells when expressed. Here, we report our progress on this project. We have also analyzed genes in Mycobacteriophage Island3, a cluster I1 phage, for cytotoxicity and defense to complete the screen of this phage started by students in previous research groups

Exploring a Transcriptional Regulatory Region in Mycobacteriophage JacoRen57

Mycobacteriophages are infectious particles that infect mycobacteria, and little is known about cis-regulatory elements that control their gene expression. In phage genomes, cis-regulatory elements commonly precede a series of genes that are expressed as an operon. JacoRen57 is a cluster AB mycobacteriophage that possesses forward and reverse genes with non-coding gaps interspersed throughout its genome. We assayed one of the gap regions of JacoRen57 (40644-40974 bps) for regulatory activity in the downstream direction when present in its host, Mycobacterium smegmatis, by cloning the region into pLO86, a vector containing the mCherry reporter gene. The putative regulatory region induced the expression of mCherry in vivo, indicating the presence of a promoter in this region of the JacoRen57 genome. Utilizing 5’ deletions analysis, we identified promoter and repressor elements within this regulatory region. We are conducting further experiments to understand the characteristics of the repressor region and which sigma factor/s binds to this promoter