Relationship of leaf calcium content to fire blight Erwinia amylovora in selected apple cultivars

Call number: LD2668 .T4 1965 S623Master of Scienc

Femtosecond photoelectron and photoion spectrometer with vacuum ultraviolet probe pulses

We describe a setup to study ultrafast dynamics in gas-phase molecules using time-resolved photoelectron and photoion spectroscopy. The vacuum ultraviolet (VUV) probe pulses are generated via strong field high-order harmonic generation from infrared femtosecond laser pulses. The band pass characteristic in transmission of thin indium (In) metal foil is exploited to isolate the $9^{\text{th}}$ harmonic of the 800 nm fundamental (H9, 14 eV, 89 nm) from all other high harmonics. The $9^{\text{th}}$ harmonic is obtained with high conversion efficiencies and has sufficient photon energy to access the complete set of valence electron levels in most molecules. The setup also allows for direct comparison of VUV single-photon probe with 800 nm multi-photon probe without influencing the delay of excitation and probe pulse or the beam geometry. We use a magnetic bottle spectrometer with high collection efficiency for electrons, serving at the same time as a time of flight spectrometer for ions. Characterization measurements on Xe reveal the spectral width of H9 to be $190\pm60$ meV and a photon flux of $\sim1\cdot10^{7}$ photons/pulse after spectral filtering. As a first application, we investigate the S$_1$ excitation of perylene using time-resolved ion spectra obtained with multi-photon probing and time-resolved electron spectra from VUV single-photon probing. The time resolution extracted from cross-correlation measurements is $65\pm10$ fs for both probing schemes and the pulse duration of H9 is found to be $35\pm8$ fs

Characterization of hair-follicle side population cells in mouse epidermis and skin tumors.

A subset of cells, termed side-population (SP), which have the ability to efflux Hoeschst 33342, have previously been demonstrated to act as a potential method to isolate stem cells. Numerous stem/progenitor cells have been localized in different regions of the mouse hair follicle (HF). The present study identified a SP in the mouse HF expressing the ABCG2 transporter and MTS24 surface marker. These cells are restricted to the upper isthmus of the HF and have previously been described as progenitor cells. Consistent with their SP characteristic, they demonstrated elevated expression of ABCG2 transporter, which participates in the dye efflux. Analysis of tumor epidermal cell lines revealed a correlation between the number of SP keratinocytes and the grade of malignancy, suggesting that the SP may play a role in malignant progression. Consistent with this idea, the present study observed an increased number of cells expressing ABCG2 and MTS24 in chemically induced skin tumors and skin tumor cell lines. This SP does not express the CD34 surface marker detected in the multipotent stem cells of the bulge region of the HF, which have been defined as tumor initiation cells. The present study concluded that a SP with properties of progenitor cells is localized in the upper isthmus of the HF and is important in mouse skin tumor progression

Inelastic scattering of broadband electron wave packets driven by an intense mid-infrared laser field

Intense, 100 fs laser pulses at 3.2 and 3.6 um are used to generate, by multi-photon ionization, broadband wave packets with up to 400 eV of kinetic energy and charge states up to Xe+6. The multiple ionization pathways are well described by a white electron wave packet and field-free inelastic cross sections, averaged over the intensity-dependent energy distribution for (e,ne) electron impact ionization. The analysis also suggests a contribution from a 4d core excitation in xenon

The Effect of Trauma on the Mental Health of Forensic Scientists

The purpose of this thesis was to determine the existence of any correlation between forensic scientists experiencing trauma and levels of mental health disorders, such as anxiety, depression, and PTSD. A survey created in Qualtrics with demographic questions and measurement questionnaires for each mental health disorder was utilized for this study. While there was little statistical analysis due to a small sample size, results showed a correlation between experiencing anxiety and PTSD. Research also illustrated that there were no respondents that reported having no level of the mental health disorders listed. Keywords: forensic scientist, trauma, mental health, anxiety, depression, PTS

Examination of the enterotoxigenic Escherichia coli population structure during human infection

Enterotoxigenic E. coli (ETEC) can cause severe diarrhea and death in children in developing countries; however, bacterial diversity in natural infection is uncharacterized. In this study, we explored the natural population variation of ETEC from individuals with cholera-like diarrhea. Genomic sequencing and comparative analysis of multiple ETEC isolates from twelve cases of severe diarrhea demonstrated clonal populations in the majority of subjects (10/12). In contrast, a minority of individuals (2/12) yielded phylogenomically divergent ETEC isolates. Detailed examination revealed that isolates also differed in virulence factor content. These genomic data suggest that severe, cholera-like ETEC infections are largely caused by a clonal population of organisms within individual patients. Additionally, the isolation of similar clones from geographically and temporally dispersed cases with similar clinical presentations suggests that some isolates are particularly suited for virulence. The identification of multiple genomically diverse isolates with variable virulence factor profiles from a single subject highlights the dynamic nature of ETEC, as well as a potential weakness in the examination of cultures obtained from a single colony in clinical settings. These findings have implications for vaccine design and provide a framework for the study of population variation in other human pathogens

Hit Me with your Best Shot: A Critical Analysis of the Resistance to Vaccine Utilization

Vaccines have provided humans protection from infectious diseases for centuries, yet the vaccination rate in the United States fails to come near one-hundred percent, allowing vaccine-preventable diseases to re-emerge in communities across the nation. Vaccines have proven to be a safe and effective method in preventing the spread of infectious disease, but vaccine resistance remains high due to false information perpetuated by anti-vaxxers, greatly impacting the vaccination rate in our country. This thesis, by means of a literature review, provides a critical analysis the resistance to vaccine utilization in the United States to determine what policy recommendations and interventions can be made to reduce the resistance to vaccines and increase the vaccination rate in our country. Vaccine hesitancy has been around ever since the creation of the first vaccine and as the years went on, the modern anti-vaxx movement gained ground, voicing concerns over the ingredients in vaccines, the number of vaccines children receive in their first year, and the belief of the myth that vaccines cause autism. Even after medical science and years of research have validated the safety of vaccines and have shown no link to autism, vaccine hesitancy is still an issue as anti-vaxxers push to receive exemptions for medical, religious or philosophical reasons. Several states offer these types of exemptions, furthering the low vaccination rates in the United States and putting citizens’ health and safety at risk. The findings of the critical analysis were comparable to the literature review: compulsory vaccine laws have proven to be a successful solution to increase vaccination rates; however, these laws are left up to the states, allowing many individuals to go unvaccinated as only Mississippi, West Virginia, and California do not allow religious and philosophical exemptions. In order to address the low vaccination rates in the United States, policy interventions must be made through the states, the federal government, health care providers, and community and government-based organizations to increase the vaccination rate in our country through measures intended to increase vaccine compliance. Without these policy interventions, our nation and our world will never be free from the threat of vaccine-preventable infectious diseases

Enterotoxigenic Escherichia coli secretes a highly conserved mucin-degrading metalloprotease to effectively engage intestinal epithelial cells

Enterotoxigenic Escherichia coli (ETEC) is a leading cause of death due to diarrheal illness among young children in developing countries, and there is currently no effective vaccine. Many elements of ETEC pathogenesis are still poorly defined. Here we demonstrate that YghJ, a secreted ETEC antigen identified in immunoproteomic studies using convalescent patient sera, is required for efficient access to small intestinal enterocytes and for the optimal delivery of heat-labile toxin (LT). Furthermore, YghJ is a highly conserved metalloprotease that influences intestinal colonization of ETEC by degrading the major mucins in the small intestine, MUC2 and MUC3. Genes encoding YghJ and its cognate type II secretion system (T2SS), which also secretes LT, are highly conserved in ETEC and exist in other enteric pathogens, including other diarrheagenic E. coli and Vibrio cholerae bacteria, suggesting that this mucin-degrading enzyme may represent a shared virulence feature of these important pathogens