Hatchling marine turtles exhibit a positive phototaxis by crawling toward the lowest and brightest horizon when they emerge from nests on the beach at night, which should lead them to the ocean (“seafinding”). Previous research with cheloniid (loggerhead and green turtle) hatchlings demonstrated that the perceptual spectral sensitivities are well below the light available on the beach regardless of lunar phase. The goal of this research was to determine the perceptual spectral sensitivities of leatherback hatchlings, the most distantly related of all extant sea turtle species. This study revealed that, like cheloniids, leatherbacks are most sensitive to shorter wavelengths (< 500 nm). However, leatherbacks were 10 – 100x less sensitive than cheloniids at all tested wavelengths. This difference in sensitivity corresponds with increased crawl duration and circling behavior under new moon conditions when light levels are lowest and the difference in radiance between the landward and seaward direction is small. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Today three species are recognized in the genus: C. freundii, C. amalonaticus, and C, diversus. C. freundii is known to occur as three varieties: C. freundii H2S +, IND -, C. freundii H2S +, IND +, and C. freundii H2S -, IND -. The role of Citrobacter in disease has not been investigated thoroughly. The organism is a normal inhabitant of the human intestine, being as common as Escherichia coli in infants. With age, the child's intestine begins to show a greater ratio of E. coli to Citrobacter (Nahhas, personal communication). Citrobacter has been reported as a cause of urinary and respiratory tract infections, especially in children. Hodges et at (1978), however, believe that in most cases, Citrobacter is found in a commensalistic relationship with the organism(s) causing the infection. Most patients from whom Citrobacter was cultured and underlying diseases or factors predisposing them to infection. outbreaks of neonatal meningitis in hospital maternity wards and nurseries have been attributed to contamination of nurses' hands and equipment by C. diversus (Anderson et al, 1981; Enzenauer et al, 1982). Osteomyelitis, neonatal diarrhea, neonatal septicemia, and brain abscesses caused by Citrobacter have also been reported (Barton and Walentik, 1982). In January 1983, I began a study of this group with two objectives in mind: to study the biochemical and antibiogram characteristics of Citrobacter isolates from Stockton, California, and, if possible, to expand and update information on the biology of the genus.

Loop-mediated isothermal DNA amplification (LAMP) are currently used as standalone diagnostic test for C. difficile infection (CDI). We assessed the diagnostic accuracy of LAMP for the diagnosis of CDI. We searched 5 databases to identify studies that compared LAMP with culture cytotoxicity neutralization assay or anaerobic toxigenic culture (TC) of C. difficile. We used the random-effects model to calculate pooled sensitivities, specificities, diagnostic odds ratios and their 95% confidence intervals (CIs). The search of the databases yielded 16 studies (6,979 samples) that met inclusion criteria. When TC was used as the gold standard (6,572 samples), bivariate analysis yielded a mean sensitivity of 0.95 (95%CI, 0.93-0.97; I2 = 67.4) and a mean specificity of 0.99 (95%CI, 0.96-1.00; I2 = 97.0). LAMP is a useful diagnostic tool with high sensitivity and specificity for detecting CDI. The results should however be interpreted only in the presence of clinical suspicion and symptoms of CDI. / Revisión por pares

archives@tulane.edu / 1 / Harley Hanes

Although Essential Tremor (ET) is the most common type of tremor, many patients are left without satisfactory treatment options. One potential alternative treatment to medication or surgery is a wearable tremor-suppressing device. However, optimizing the effectiveness of such a device requires knowledge of which muscles/joints are most responsible for tremor. To answer this question, current efforts simulate tremor propagation using a model of the neuromusculoskeletal dynamics of the upper limb. To guide efforts to identify realistic model parameters and use the model to determine the mechanical origin of tremor, we performed preliminary parameter estimation work and a thorough sensitivity analysis of this tremor propagation model. The tremor propagation model included muscle activation inputs to the 15 major superficial muscles and joint displacement outputs in the 7 main degrees of freedom (DOF) from the shoulder to the wrist, resulting in 105 input-output relationships. We calculated the mean normalized sensitivities of all outputs to all 107 model parameters over the tremor band (4 to 8 Hz), resulting in approximately 12,000 sensitivities. We found that sensitivities were relatively constant in the tremor band, except for shoulder adduction-abduction, which exhibited a large peak in sensitivity between 4 and 5 Hz. Averaged across the tremor band, the system was most sensitive to select elements of inertia, muscle force, muscle moment arm, damping, muscle time constants, and stiffness (in that order). The 19 highest all-input-excitation sensitivities were between 1.2 and 4.57, meaning a 100% change in parameter value produces 120-457% change in tremor. Conversely, the model includes many parameters to which the outputs are relatively insensitive. For example, the sensitivities to almost one third of the 107 parameters are below 0.1, meaning a 100% change in parameter value produces only a 10% change in tremor. To gain additional insight, we compared the sensitivities of the full model to those of a simpler model including only two inputs and two outputs. Analyzing the two-input two-output model revealed patterns in sensitivity which persist in the full model. The sensitivities of the full model were further compared to past studies that performed rudimentary sensitivity analyses and were found to match while adding significantly more parameter-specific sensitivity information. Future work will extend this sensitivity analysis to tremor at the hand, where it matters most.

Prior knowledge about the possible characteristics of demand and supply is vital in the planning and operation of economically sustainable isolated rural power systems. System modelling and simulation is one of the tools that can be used in planning and assessing the performance of these systems. This thesis is presenting a Monte Carlo simulation methodology for modelling, simulating and analysing the performance of isolated rural electricity markets applicable in developing countries. The definitions of possible power system operators managing these markets are introduced based on different economic objectives of operating the systems. The two system operators considered in the thesis are: altruistic and profit maximising operators. The concept used to define types of isolated rural electricity markets is combining the definitions of operators and the possible combinations of power supply options (purely thermal or hybrid system). It is anticipated that the rural electricity markets under consideration comprise of uncertainties in demand and supply (both demand and generation are modelled as random variables from assumed or estimated probability distributions). Demand is price sensitive and modelled as a product of two random variables, relative demand and peak demand. The price sensitivity of demand is shown by representing peak demand using an economic price-demand function. The parameters (price sensitivity and demand factor) of this function are modelled as random variables which reflect the randomness of consumers’ preferences. The simulation algorithm is based on the theory of correlated sampling, in order to compare the performance of systems under different operators. The thesis introduces the concept of nested Monte Carlo simulation to be able manage the simulation of different operators subjected to the same market conditions. The performance of electricity markets is assessed by analysing three parameters (tariffs, profit and reliability), which are random variables presented using probability distributions in form of duration curves. The methodology is tested on a theoretical case study system using load data obtained from a rural community in Africa.  The case study illustrates how to use the model, preparation of the input variables and how to use the output to estimate and assess the possible performance of isolated rural power systems under different power system operators. It is anticipated that the proposed methodology can be used by researchers, planners and academia as a tool for planning, estimating and assessing the performance of rural power systems in isolated areas of developing countries

The use of the nomination stage as the first step in the identification process is pervasive across the field of gifted education. In many cases, nominations are used to limit the number of students who will need to be evaluated using costly and time-consuming assessments for the purpose of gifted program identification and placement. This study evaluated the effect of the nomination stage on the overall efficacy of a gifted identification system. Results showed that in nearly all conditions, identification systems that require a nomination before testing result in a large proportion of gifted students being missed. Under commonly implemented conditions, the nomination stage can cause the false negative rate to easily exceed 60%. Changes to identification practices are urgently needed in order to ensure that larger numbers of gifted students receive appropriate educational placement and to maintain the integrity of gifted education services.

The zebrafish (Danio rerio) has been used as a model for studying vertebrate development in the cardiovascular system. In order to monitor heart contraction and cytosolic calcium oscillations, fish were either embedded in methylcellulose or anesthetized with tricaine. Using high-resolution differential interference contrast and calcium imaging microscopy, we here show that dopamine and verapamil alter calcium signaling and muscle contraction in anesthetized zebrafish, but not in embedded zebrafish. In anesthetized fish, dopamine increases the amplitude of cytosolic calcium oscillation with a subsequent increase in heart contraction, whereas verapamil decreases the frequency of calcium oscillation and heart rate. Interestingly, verapamil also increases myocardial contraction. Our data further indicate that verapamil can increase myocardial calcium sensitivity in anesthetized fish. Taken together, our data reinforce in vivo cardiac responses to dopamine and verapamil. Furthermore, effects of dopamine and verapamil on myocardial calcium and contraction are greater in anesthetized than embedded fish. We suggest that while the zebrafish is an excellent model for a cardiovascular imaging study, the cardio-pharmacological profiles are very different between anesthetized and embedded fish.

Aims and Objectives: To compare three risk assessment scales with respect to predictive validity Background: In paediatrics there are several competing scales and at least ten published paediatric pressure ulcer risk assessment scales have been identified. However there are few studies exploring the validity of such scales, and none identified that compares paediatric risk assessment scales. Design: Cross sectional study Methods: Three risk assessment scales, Braden Q, Garvin and Glamorgan, were compared. The total scores and sub-scores were tested to determine if children with pressure ulcers were significantly different from those with no pressure ulcer. Logistic regression was conducted to determine if the probability of developing a pressure ulcer was a better predictor of development of pressure ulcer compared with the total score of each scale. Receiver operating characteristic curves were computed and the area under the curve used to compare the performance of the risk assessment scales. Results: Data from 236 children were collected. 71 were from children in eleven hospitals who were asked to provide data on children with pressure ulcers (although seventeen did not have a pressure ulcer) of whom five were deep (grade 4). A sample of 165 were from one hospital, of which seven had a pressure ulcer, none grade four. The Glamorgan risk assessment scale had a higher predictive ability than either the Braden Q or Garvin. The mobility sub-score of each of the risk assessment scales was the most predictive in each case. Conclusions: The Glamorgan scale is the most valid of the three paediatric risk assessment scales studied in this population. Mobility alone may be as effective as employing the more complex risk assessment scale. Relevance to clinical practice: If a paediatric risk assessment scale is employed to predict risk, then unless it is valid, it may identify children who are not at risk and waste resources, or fail to identify children at risk possibly resulting in adverse health outcomes.

Clinical relevance: Mobility and fall risk may be important considerations in choosing between intraocular lenses. Background: Fall risk in older adults increases when wearing multifocal spectacles, but little is known about mobility among individuals with different types of intraocular lenses. This study compared visual function, fall risk and balance control following bilateral implantation of monofocal or multifocal intraocular lenses. Methods: This was a non-randomised, cross-sectional study involving adults with bilateral intraocular lenses. Participants completed questionnaires concerning physical functioning, fall history and balance-related confidence. Binocular visual acuity, contrast sensitivity (Pelli-Robson chart and computerized testing), depth perception and glare sensitivity were assessed. Physical performance measures included the Sensory Organization Test, preferred gait speed, Dynamic Gait Index and wayfinding in a virtual environment. Results: Fifteen participants (mean ± standard deviation, 67.1 ± 6.8 years) had monofocal intraocular lenses and 14 participants (68.1 ± 6.1 years) had multifocal intraocular lenses. Contrast sensitivity in the monofocal group was significantly better than that in the multifocal group (p = 0.02) at intermediate and high spatial frequencies. Contrast sensitivity of the monofocal group also was less affected by glare than the contrast sensitivity of the multifocal group, at an intermediate spatial frequency (p = 0.02). However, the multifocal group had significantly better Dynamic Gait Index scores (p = 0.04), even after controlling for perceived physical function. Conclusions: The participants with monofocal intraocular lenses generally had better contrast sensitivity than did those with multifocal intraocular lenses. However, the scores on a mobility test that is associated with fall risk were worse for those with monofocal lenses.