Nuclear magnetic resonance studies of macroscopic morphology and dynamics

Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques

Quantum description of the orientational degrees of freedom in a biaxial nematic liquid

The quantum mechanical version of a classical model for studying the orientational degrees of freedom corresponding to a nematic liquid composed of biaxial molecules is presented. The effective degrees of freedom are described by operators carrying an SU(3) representation, which allows the explicit calculation of the partition function in the mean field approximation. The algebraic consistency conditions are solved numerically and the equilibrium phases of the system are determined. In particular, the entropy, the specific heat and the order parameters are presented for different choices of the constituent biaxial molecules. Our results reproduce the classical calculation in the limit of high temperatures and high quantum numbers.Comment: 33 pages, Latex, 11 figure

Submicroscopic malaria infection is not associated with fever in cross-sectional studies in Malawi

Submicroscopic Plasmodium falciparum infections are widespread in many areas. However, the contribution of these infections to symptomatic malaria is not well understood. This study evaluated whether participants with submicroscopic P. falciparum infections have higher prevalence of fever than uninfected participants in southern Malawi. A total of 16,650 children and adults were enrolled in the course of six cross-sectional surveys during the dry season (October–November) and after the rainy season (April–May) between 2012 and 2014 in three districts in southern Malawi. Demographic and socioeconomic data were collected in conjunction with data on clinical histories, use of malaria preventive measures, and anti-malarial medication taken within 2 weeks of the survey. Axillary temperatures were measured, and blood samples were collected for P. falciparum detection by microscopy and PCR. Participants without malaria parasites detected on microscopy but with a positive PCR for P. falciparum were defined as having submicroscopic infection. Fever was defined as having any one of: reported fever in the past 2 weeks, reported fever in the past 48 h, or a temperature of ≥ 37.5 °C measured at the time of interview. Submicroscopic P. falciparum infections and fever were both detected in 9% of the study population. In the final analysis adjusted for clustering within household and enumeration area, having submicroscopic P. falciparum infection was associated with reduced odds of fever in the dry season (odds ratio = 0.52; 95% CI 0.33–0.82); the association in the rainy season did not achieve statistical significance (odds ratio = 1.20; 95% CI 0.91–1.59). The association between submicroscopic infection and fever was consistent across all age groups. When the definition of fever was limited to temperature of ≥ 37.5 °C measured at the time of interview, the association was not statistically significant in either the rainy or dry season. In this series of cross-sectional studies in southern Malawi, submicroscopic P. falciparum infection was not associated with increased risk of fever. Submicroscopic detection of the malaria parasite is important in efforts to decrease transmission but is not essential for the clinical recognition of malaria disease.https://doi.org/10.1186/s12936-020-03296-

The epidemiology of enterococci

The enterococci are emerging as a significant cause of nosocomial infections, accounting for approximately 10 % of hospital acquired infections. They are found as normal inhabitants of the human gastrointestinal tract, but may also colonize the oropharynx, vagina, perineal region and soft tissue wounds of asymtomatic patients. Until recently, evidence indicated that most enterococcal infections arose from patients' own endogenous flora. Recent studies, however, suggest that exogeneous acquisition may occur and that person-to-person spread, probably on the hands of medical personnel, may be a significant mode of transmission of resistant enterococci within the hospital. The use of broad-spectrum antibiotics, especially cephalosporins, is another major factor in the increasing incidence of enterococcal infections. These findings suggest that barrier precautions, as applied with other resistant nosocomial pathogens, along with more judicial use of antibiotics may be beneficial in preventing nosocomial spread of resistant enterococci.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47899/1/10096_2005_Article_BF01963631.pd

ReKAP of the COVID-19 Pandemic: Knowledge, Attitudes, and Practices among Healthcare Workers with Varying Ebola History in the Democratic Republic of the Congo, August 2020 to August 2021

Mounting an effective response to an emergent pathogen, such as SARS-CoV-2, can be particularly challenging for public health systems that are overburdened and under resourced, like that in the Democratic Republic of the Congo (DRC). Conversely, the DRC has an extensive history combatting infectious diseases, and perhaps, one of the most practiced health workforces, globally, in the prevention and control of emergent diseases, such as Ebola virus disease (EVD). However, the extent of knowledge, attitudes, and practice (KAP) among HCWs in DRC during the COVID-19 pandemic is not well understood. This dissertation utilizes repeated measures of KAP collected via 25 phone interviews among four cohorts of Congolese HCWs (N=545) from communities with varied EVD history throughout a year of the pandemic (August 2020 to August 2021) to enhance awareness of fluctuations in KAP over time and between cohorts in this population. Chapter 1 summarizes the epidemiology and prevention and control strategies for COVID-19 and EVD, both generally and in the context of DRC. Chapter 2 assesses potential and perceived COVID-19 risk reported by the sample; the probability of providing care to a patient with COVID-19 symptoms increased modestly in each cohort throughout the study, while perceptions of risk remained comparatively stable over time but differed by cohort. Chapter 3 assesses perceptions of efficacy of six COVID-19 prevention behaviors and compliance with those same behaviors; most of the sample consistently reported the efficacy of each behavior throughout the study, but fluctuations in compliance with mask wearing, avoiding gathering, and socially distancing were observed over time as well as differences between cohorts. Chapter 4 assesses workplace safety measures specifically during periods of concurrent EVD outbreaks in Mbandaka and Beni. Perceptions of workplace safety remained relatively stable during the study regardless of EVD outbreaks, but cohort differences were observed. Fluctuations in access to cloth and surgical face masks over time and consistently low access to N95 face masks were also found. This dissertation establishes a reference for KAP among a sample of HCWs in DRC during a major infectious disease event and indicates that longitudinal and subnational analyses are warranted to adequately identify potential barriers to future outbreak response

ReKAP of the COVID-19 Pandemic: Knowledge, Attitudes, and Practices among Healthcare Workers with Varying Ebola History in the Democratic Republic of the Congo, August 2020 to August 2021

Mounting an effective response to an emergent pathogen, such as SARS-CoV-2, can be particularly challenging for public health systems that are overburdened and under resourced, like that in the Democratic Republic of the Congo (DRC). Conversely, the DRC has an extensive history combatting infectious diseases, and perhaps, one of the most practiced health workforces, globally, in the prevention and control of emergent diseases, such as Ebola virus disease (EVD). However, the extent of knowledge, attitudes, and practice (KAP) among HCWs in DRC during the COVID-19 pandemic is not well understood. This dissertation utilizes repeated measures of KAP collected via 25 phone interviews among four cohorts of Congolese HCWs (N=545) from communities with varied EVD history throughout a year of the pandemic (August 2020 to August 2021) to enhance awareness of fluctuations in KAP over time and between cohorts in this population. Chapter 1 summarizes the epidemiology and prevention and control strategies for COVID-19 and EVD, both generally and in the context of DRC. Chapter 2 assesses potential and perceived COVID-19 risk reported by the sample; the probability of providing care to a patient with COVID-19 symptoms increased modestly in each cohort throughout the study, while perceptions of risk remained comparatively stable over time but differed by cohort. Chapter 3 assesses perceptions of efficacy of six COVID-19 prevention behaviors and compliance with those same behaviors; most of the sample consistently reported the efficacy of each behavior throughout the study, but fluctuations in compliance with mask wearing, avoiding gathering, and socially distancing were observed over time as well as differences between cohorts. Chapter 4 assesses workplace safety measures specifically during periods of concurrent EVD outbreaks in Mbandaka and Beni. Perceptions of workplace safety remained relatively stable during the study regardless of EVD outbreaks, but cohort differences were observed. Fluctuations in access to cloth and surgical face masks over time and consistently low access to N95 face masks were also found. This dissertation establishes a reference for KAP among a sample of HCWs in DRC during a major infectious disease event and indicates that longitudinal and subnational analyses are warranted to adequately identify potential barriers to future outbreak response