Personal And Real Property—Referendum Unnecessary for Acquisition of Property Pursuant to Local Finance Law

Matter of Town Bd. of Town of Islip, 12 N.Y.2d 321, 189 N.E.2d 808, 239 N.Y.S.2d 541 (1963)

Invariance of Structure in an Aging Colloidal Glass

We study concentrated colloidal suspensions, a model system which has a glass transition. The non-equilibrium nature of the glassy state is most clearly highlighted by aging -- the dependence of the system's properties on the time elapsed since vitrification. Fast laser scanning confocal microscopy allows us to image a colloidal glass and track the particles in three dimensions. We analyze the static structure in terms of tetrahedral packing. We find that while the aging of the suspension clearly affects its dynamics, none of the geometrical quantities associated with tetrahedra change with age.Comment: Submitted to the proceedings of "The 3rd International Workshop on Complex Systems" in Sendai, Japa

Self-Organized Criticality Below The Glass Transition

We obtain evidence that the dynamics of glassy systems below the glass transition is characterized by self-organized criticality. Using molecular dynamics simulations of a model glass-former we identify clusters of cooperatively jumping particles. We find string-like clusters whose size is power-law distributed not only close to T_c but for ALL temperatures below T_c, indicating self-organized criticality which we interpret as a freezing in of critical behavior.Comment: 4 pages, 3 figure

Correlations of Structure and Dynamics in an Aging Colloidal Glass

We study concentrated colloidal suspensions, a model system which has a glass transition. Samples in the glassy state show aging, in that the motion of the colloidal particles slows as the sample ages from an initial state. We study the relationship between the static structure and the slowing dynamics, using confocal microscopy to follow the three-dimensional motion of the particles. The structure is quantified by considering tetrahedra formed by quadruplets of neighboring particles. We find that while the sample clearly slows down during aging, the static properties as measured by tetrahedral quantities do not vary. However, a weak correlation between tetrahedron shape and mobility is observed, suggesting that the structure facilitates the motion responsible for the sample aging.Comment: Submitted to Solid State Communication

Forced motion of a probe particle near the colloidal glass transition

We use confocal microscopy to study the motion of a magnetic bead in a dense colloidal suspension, near the colloidal glass transition volume fraction $\phi_g$. For dense liquid-like samples near $\phi_g$, below a threshold force the magnetic bead exhibits only localized caged motion. Above this force, the bead is pulled with a fluctuating velocity. The relationship between force and velocity becomes increasingly nonlinear as $\phi_g$ is approached. The threshold force and nonlinear drag force vary strongly with the volume fraction, while the velocity fluctuations do not change near the transition.Comment: 7 pages, 4 figures revised version, accepted for publication in Europhysics Letter

Predictors of Patient-reported Outcomes after TKR not Included in Risk Models Based on Administrative Data

Introduction: Because total knee replacement (TKR) surgery is performed to relieve pain and improve physical function in patients with advanced arthritis, patient-reported outcomes (PROs) are important to assess TKR effectiveness. The UK and others require PROs. Understanding pre-existing clinical factors that influence PROs after surgery is needed before comparing PROs across providers. We evaluated the roles of medical and musculoskeletal comorbidities in explaining variation in 6 month post-TKR pain relief and functional gain in a national cohort of TKR patients. Materials & methods: FORCE-TJR, funded by the Agency for Healthcare Research and Quality (AHRQ), is a national consortium in which 100% patients, surgeons and hospitals submit data: patients demographics (age, gender, BMI, race), complete medical and musculoskeletal comorbidities, PROs including SF-36 Physical Component Score (PCS), Knee injury and Osteoarthritis Outcome Score (KOOS), clinically refined adverse events and implant data. Predictors of change in pre-to-6 month post-TKR pain and function were examined using linear mixed models adjusting for clustering within site. Results: TKR patients had a mean age of 67 years, mean BMI of 31.2, were 63% female and 4.5% black, 9% with Charlson Comorbidity Index (CCI) of 2-5, 15% with CCI of 6, 7% moderate/severe pain in 2-3 knee/hip joints, 27% moderate/severe lumbar pain. After adjusting for socio-demographic factors, significant predictors of poorer 6 month post-TKR pain included poorer emotional health, higher CCI, 1-2 nonsurgical hip/knee joints with moderate/severe pain, any lumbar pain at time of TKR. These same factors also predicted poorer 6 month function. Conclusion: Before adopting PROs as a standard measure of TKR outcome, a complete understanding of pre-existing clinical factors associated with poorer pain relief and functional gain is needed. Greater musculoskeletal, and medical, comorbid conditions were associated with post-operative PROs and should be included in risk-adjustment models before cross-hospital comparisons can be made

Aging in Dense Colloids as Diffusion in the Logarithm of Time

The far-from-equilibrium dynamics of glassy systems share important phenomenological traits. A transition is generally observed from a time-homogeneous dynamical regime to an aging regime where physical changes occur intermittently and, on average, at a decreasing rate. It has been suggested that a global change of the independent time variable to its logarithm may render the aging dynamics homogeneous: for colloids, this entails diffusion but on a logarithmic time scale. Our novel analysis of experimental colloid data confirms that the mean square displacement grows linearly in time at low densities and shows that it grows linearly in the logarithm of time at high densities. Correspondingly, pairs of particles initially in close contact survive as pairs with a probability which decays exponentially in either time or its logarithm. The form of the Probability Density Function of the displacements shows that long-ranged spatial correlations are very long-lived in dense colloids. A phenomenological stochastic model is then introduced which relies on the growth and collapse of strongly correlated clusters ("dynamic heterogeneity"), and which reproduces the full spectrum of observed colloidal behaviors depending on the form assumed for the probability that a cluster collapses during a Monte Carlo update. In the limit where large clusters dominate, the collapse rate is ~1/t, implying a homogeneous, log-Poissonian process that qualitatively reproduces the experimental results for dense colloids. Finally an analytical toy-model is discussed to elucidate the strong dependence of the simulation results on the integrability (or lack thereof) of the cluster collapse probability function.Comment: 6 pages, extensively revised, final version; for related work, see http://www.physics.emory.edu/faculty/boettcher/ or http://www.fysik.sdu.dk/staff/staff-vip/pas-personal.htm

The Validity of Patient-Reported Short-Term Complications following Total Hip and Knee Arthroplasty

Introduction: Given the lack of national data on outcomes of on patients who undergo total joint arthroplasty (TJA) and the limitations of hospital databases to capture information on patients who seek post-TJA care elsewhere, there is growing interest in using patient self-report to identify possible complications following surgery. We examined the concordance between patients self-report of potential short-term complications with review of available medical records as well as the location of the reported post-operative care. Material & Methods: Patients undergoing primary hip or knee arthroplasty from 7/1/11 through 12/3/12 participating in a tertiary care center were identified. Patients completed a 6-month post-operative survey regarding needing evaluation at an emergency department, day surgery or hospitalization for possible medical or mechanical complications and the location of care. We reviewed available inpatient and outpatient medical records to identify the location of postoperative care as well as the validity of patient self-report (sensitivity, specificity, positive predictive values and negative predictive values). Results: There were 413 patients who had 431 surgeries and completed the 6-month questionnaire. Patients reported 40 medical encounters including emergency department, day surgery or inpatient care resulting in a 9% reported complication rate, of which 20% occurred at outside hospitals Overall patient self-report of emergency department, day surgery and inpatient care for possible complications was both sensitive (82%) and specific (100%). The positive predictive value was 100% and negative predictive value 98%. Conclusion: Given the prevalence of events requiring care at outlying hospitals and the accuracy of self-report, methods that directly engage patients can augment current surveillance procedures

Direct visualization of aging in colloidal glasses

We use confocal microscopy to directly visualize the dynamics of aging colloidal glasses. We prepare a colloidal suspension at high density, a simple model system which shares many properties with other glasses, and initiate experiments by stirring the sample. We follow the motion of several thousand colloidal particles after the stirring and observe that their motion significantly slows as the sample ages. The aging is both spatially and temporally heterogeneous. Furthermore, while the characteristic relaxation time scale grows with the age of the sample, nontrivial particle motions continue to occur on all time scales.Comment: submitted to proceedings for Liquid Matter Conference 200