Macrostate Data Clustering

We develop an effective nonhierarchical data clustering method using an analogy to the dynamic coarse graining of a stochastic system. Analyzing the eigensystem of an interitem transition matrix identifies fuzzy clusters corresponding to the metastable macroscopic states (macrostates) of a diffusive system. A "minimum uncertainty criterion" determines the linear transformation from eigenvectors to cluster-defining window functions. Eigenspectrum gap and cluster certainty conditions identify the proper number of clusters. The physically motivated fuzzy representation and associated uncertainty analysis distinguishes macrostate clustering from spectral partitioning methods. Macrostate data clustering solves a variety of test cases that challenge other methods.Comment: keywords: cluster analysis, clustering, pattern recognition, spectral graph theory, dynamic eigenvectors, machine learning, macrostates, classificatio

Clinically small tonsils are typically not obstructive in children during drug-induced sleep endoscopy

OBJECTIVE: To determine whether the degree of lateral pharyngeal wall (LPW) obstruction on pediatric drug-induced sleep endoscopy (DISE) correlates with preprocedure tonsillar hypertrophy score on physical examination, and to determine if clinically small tonsils are obstructive. METHODS: Retrospective review of 154 patients who underwent DISE at a single pediatric tertiary care center over a 4-year period. Inclusion criteria were documentation of Brodsky tonsil score on preoperative physical examination. Exclusion criteria were previous tonsillectomy, adenoidectomy, or adenotonsillectomy. Lateral pharyngeal wall obstruction was graded for each patient from 0 (no obstruction) to 3 (severe obstruction) using a validated pediatric DISE scoring system known as the Chan-Parikh scoring system (C-P). Data were analyzed using multivariate linear regression controlling for age at time of DISE and presence of comorbid conditions. RESULTS: One hundred fifteen patients met criteria for analysis. Median age at DISE was 5.1 years. A moderate positive correlation was calculated between Brodsky score and DISE score, Spearman correlation coefficient 0.55, P = 50% obstruction); and six (9%) had a score of 3 (100% obstruction). CONCLUSION: There is a positive correlation between Brodsky Score and DISE LPW score. The majority of children with sleep-disordered breathing with a Brodsky score of 1 did not demonstrate LPW obstruction. These children may benefit from DISE for identification of alternative sites of upper airway obstructio

Workforce Characteristics, Perceptions, Stress, and Satisfaction among Staff in Green House and Other Nursing Homes

OBJECTIVE: To compare workforce characteristics and staff perceptions of safety, satisfaction, and stress between Green House (GH) and comparison nursing homes (CNHs). DATA SOURCES/STUDY SETTING: Primary data on staff perceptions of safety, stress, and satisfaction from 13 GHs and 8 comparison NHs in 11 states; secondary data from human resources records on workforce characteristics, turnover, and staffing from 01/01/2011-06/30/2012. STUDY DESIGN: Observational study. DATA COLLECTION METHODS: Workforce data were from human resources offices; staff perceptions were from surveys. PRINCIPAL FINDINGS: Few significant differences were found between GH and CNHs. Exceptions were GH direct caregivers were older, provided twice the normalized hours per week budgeted per resident than CNAs in CNHs or Legacy NHs, and trended toward lower turnover. CONCLUSIONS: GH environment may promote staff longevity and does not negatively affect worker's stress, safety perceptions, or satisfaction. Larger studies are needed to confirm findings

Treatment and outcomes of invasive fusariosis: review of 65 cases from the PATH Alliance ® registry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109347/1/myc12212.pd

University Woodwind Quintet

Centennial Lecture Hall November 25, 1968 8:15p.m

Uncovering the effects of heterogeneity and parameter sensitivity on within‑host dynamics of disease : malaria as a case study

CITATION: Horn, S., Snoep, J. L. & Van Niekerk, D. D. 2021. Uncovering the effects of heterogeneity and parameter sensitivity on within‑host dynamics of disease: malaria as a case study. BMC Bioinformatics, 22:384, doi:10.1186/s12859-021-04289-z.The original publication is available at https://bmcbioinformatics.biomedcentral.comPublication of this article was funded by the Stellenbosch University Open Access FundBackground: The fidelity and reliability of disease model predictions depend on accurate and precise descriptions of processes and determination of parameters. Various models exist to describe within-host dynamics during malaria infection but there is a shortage of clinical data that can be used to quantitatively validate them and establish confidence in their predictions. In addition, model parameters often contain a degree of uncertainty and show variations between individuals, potentially undermining the reliability of model predictions. In this study models were reproduced and analysed by means of robustness, uncertainty, local sensitivity and local sensitivity robustness analysis to establish confidence in their predictions. Results: Components of the immune system are responsible for the most uncertainty in model outputs, while disease associated variables showed the greatest sensitivity for these components. All models showed a comparable degree of robustness but displayed different ranges in their predictions. In these different ranges, sensitivities were well-preserved in three of the four models. Conclusion: Analyses of the effects of parameter variations in models can provide a comparative tool for the evaluation of model predictions. In addition, it can assist in uncovering model weak points and, in the case of disease models, be used to identify possible points for therapeutic intervention.https://bmcbioinformatics.biomedcentral.com/articles/10.1186/s12859-021-04289-zPublisher's versio

The University Woodwind Quintet

Centennial Lecture Hall April 17, 1969 8:15p.m

A Statistical Mechanical Problem in Schwarzschild Spacetime

We use Fermi coordinates to calculate the canonical partition function for an ideal gas in a circular geodesic orbit in Schwarzschild spacetime. To test the validity of the results we prove theorems for limiting cases. We recover the Newtonian gas law subject only to tidal forces in the Newtonian limit. Additionally we recover the special relativistic gas law as the radius of the orbit increases to infinity. We also discuss how the method can be extended to the non ideal gas case.Comment: Corrected an equation misprint, added four references, and brief comments on the system's center of mass and the thermodynamic limi

Effects of Field Size and Landscape Composition on Grassland Birds in South-Central Iowa

Many species of grassland birds have been shown to avoid smaller fields. The avoidance of smaller fields, however, has not been consistently reported; avoidance may occur in one study, but not in another. To examine one possible reason for these inconsistencies, we examined how landscape composition influenced the relations between occurrence or abundance and field size. The study took place during the 1998 breeding season on 44 Conservation Reserve Program (CRP) fields located in Adair, Ringgold, and Union counties. The relations between occurrence, abundance, and field size were not influenced by landscape composition for any species. Grasshopper Sparrow, Ammodramus savannarum, Bobolink, Dolichonyx oryzivorus, and Eastern Meadowlark, Sturnella magna, were more likely to occur or were more abundant in larger fields. Field Sparrow, Spize!la pusilla, Western Meadowlark, Sturnella neglecta, Brown-headed Cowbird, Molothrus ater, and American Goldfinch, Carduelis tristis, were less likely to occur or were less abundant in larger fields. Field size is an important factor influencing the occurrence and/or abundance of grassland songbirds in fields. Future studies that investigate the effects of landscape composition on area sensitivity should use landscapes that have similar habitat compositions other than the habitat being varied, and use similar sized fields in each landscape

Electron-Phonon Coupling in Highly-Screened Graphene

Photoemission studies of graphene have resulted in a long-standing controversy concerning the strength of the experimental electron-phonon interaction in comparison with theoretical calculations. Using high-resolution angle-resolved photoemission spectroscopy we study graphene grown on a copper substrate, where the metallic screening of the substrate substantially reduces the electron-electron interaction, simplifying the comparison of the electron-phonon interaction between theory and experiment. By taking the nonlinear bare bandstructure into account, we are able to show that the strength of the electron-phonon interaction does indeed agree with theoretical calculations. In addition, we observe a significant bandgap at the Dirac point of graphene.Comment: Submitted to Phys. Rev. Lett. on July 20, 201