Correction factors for oxygen and flow-rate effects on neonatal Fleisch and Lilly pneumotachometers

Objective: To assess the effects of different oxygen concentrations and flow rates on the measurement errors of neonatal pneumotachometers in heated and unheated situations and to develop correction factors to correct for these effects. Design: Prospective laboratory study. Setting: Outpatient clinic with equipment in a standardized setting. Subjects: Neonatal pneumotachometers. Interventions: In standardized conditions, the tested pneumotachometer was calibrated at a flow rate of 3 L/min with 60% oxygen and was set in series with a closed spirometer system being used as a reference. Different air-flow levels (1-9 L/min) and oxygen concentrations (21-100%) were infused into the closed system with the pneumotachometer and spirometer. Measurements and Main Results: The pneumotachometers were significantly affected by changing oxygen concentrations (p < .01) and increasing flow rates (p < .01), increasing the actually measured flow rate. Correction factors, developed by multiple regression analysis, significantly reduced the overall maximum errors of the pneumotachometers from -1.1 to 0.6 L/min to -0.5 to 0.4 L/min. Conclusions: The effects of changes in oxygen concentrations and flow rates on neonatal pneumotachometers could be considerably decreased by the use of correction factors such as were calculated in this study. This will preclude frequent calibration procedures with actual flow and oxygen levels during changes in experimental settings. Copyrigh

Stripe-hexagon competition in forced pattern forming systems with broken up-down symmetry

We investigate the response of two-dimensional pattern forming systems with a broken up-down symmetry, such as chemical reactions, to spatially resonant forcing and propose related experiments. The nonlinear behavior immediately above threshold is analyzed in terms of amplitude equations suggested for a $1:2$ and $1:1$ ratio between the wavelength of the spatial periodic forcing and the wavelength of the pattern of the respective system. Both sets of coupled amplitude equations are derived by a perturbative method from the Lengyel-Epstein model describing a chemical reaction showing Turing patterns, which gives us the opportunity to relate the generic response scenarios to a specific pattern forming system. The nonlinear competition between stripe patterns and distorted hexagons is explored and their range of existence, stability and coexistence is determined. Whereas without modulations hexagonal patterns are always preferred near onset of pattern formation, single mode solutions (stripes) are favored close to threshold for modulation amplitudes beyond some critical value. Hence distorted hexagons only occur in a finite range of the control parameter and their interval of existence shrinks to zero with increasing values of the modulation amplitude. Furthermore depending on the modulation amplitude the transition between stripes and distorted hexagons is either sub- or supercritical.Comment: 10 pages, 12 figures, submitted to Physical Review

Dynamics of gelling liquids: a short survey

The dynamics of randomly crosslinked liquids is addressed via a Rouse- and a Zimm-type model with crosslink statistics taken either from bond percolation or Erdoes-Renyi random graphs. While the Rouse-type model isolates the effects of the random connectivity on the dynamics of molecular clusters, the Zimm-type model also accounts for hydrodynamic interactions on a preaveraged level. The incoherent intermediate scattering function is computed in thermal equilibrium, its critical behaviour near the sol-gel transition is analysed and related to the scaling of cluster diffusion constants at the critical point. Second, non-equilibrium dynamics is studied by looking at stress relaxation in a simple shear flow. Anomalous stress relaxation and critical rheological properties are derived. Some of the results contradict long-standing scaling arguments, which are shown to be flawed by inconsistencies.Comment: 21 pages, 3 figures; Dedicated to Lothar Schaefer on the occasion of his 60th birthday; Changes: added comments on the gel phase and some reference

Health Literacy and Change in Health-Related Quality of Life in Dialysed Patients

Health-related quality of life (HRQoL) is likely to deteriorate with the progression of chronic kidney disease (CKD). This change may be worsened by low health literacy (HL). We performed a longitudinal study at over 20 dialysis clinics in Slovakia (n = 413; mean age = 64.8 years; males = 58.4%). We assessed the association of three HL groups with a change in HRQoL over two years using binary logistic regression adjusted for type of vascular access, dialysis effectiveness, comorbidity, age and gender. We found that patients with low HL had poorer HRQoL at baseline in comparison to high-HL patients. We did not find significant associations of lower HL with the deterioration of mental or physical HRQoL after two years. In the adjusted model, patients with lower HL were not more likely to have deteriorated physical (low-HL patients: odds ratio/95% confidence interval: 0.99/0.53–1.84; moderate-HL patients: 0.97/0.55–1.73) or mental HRQoL (low-HL patients: 1.00/0.53–1.87; moderate-HL patients: 0.95/0.53–1.70) in comparison to high-HL patients. The HRQoL of lower-HL patients is worse at baseline but develops similarly to that of high-HL patients during dialysis treatment. Their relative HRQoL, thus, does not worsen further, but it does not improve either. Tailoring care to their needs may help to decrease the burden of low HL in dialysed patients

Health-Related Quality of Life Profiles in Dialyzed Patients With Varying Health Literacy. A Cross-Sectional Study on Slovak Haemodialyzed Population

Objectives: Chronic kidney disease (CKD) strongly affects patients' health-related quality of life (HRQoL), mostly in the advanced stages of CKD. Health literacy (HL) may affect this association, in particular for some aspects of HRQoL. The aim of this study is to compare the profiles of HRQoL in dialyzed patients with varying HL. Methods: We obtained data on HL using the Health Literacy Questionnaire (HLQ) and on HRQoL using the Kidney Disease Quality of Life - Short Form (KDQoL-SF 1.3) in a multicentre cross-sectional study in 20 dialysis clinics in Slovakia (n = 542; mean age = 63.6 years; males: 60.7%). We compared HRQoL for three HL groups using ANOVA and the Kruskal-Wallis test. Results: Patients with low HL reported worse HRQoL than patients with moderate and high HL. The greatest differences between HL groups were found in the scales Effect of kidney disease, Cognitive function, Quality of social interaction, Social support, Dialysis staff encouragement, Patient satisfaction, Physical functioning, Pain, Emotional well-being and Social function. p-values in all cases were Conclusion: Patients with low HL have a worse HRQoL in several domains than patients with a higher HL. Increasing HL capacities and better supporting patients with low HL should thus be given priority to support their HRQoL and at least maintain its level

Does Depression and Anxiety Mediate the Relation between Limited Health Literacy and Diet Non-Adherence?

Limited health literacy (HL), depression and anxiety are common in dialyzed patients and affect health outcomes and self-management. We explored whether depression and anxiety mediate the association of HL with diet non-adherence (DN-A) in dialyzed patients. We performed a cross-sectional study in 20 dialysis clinics in Slovakia (n = 452; mean age: 63.6 years; males: 60.7%). Hierarchical cluster analysis was performed to create three HL groups. Logistic regression adjusted for age, gender and education was used to explore whether depression and anxiety mediate the association of HL with DN-A. Patients in the moderate HL group were more likely to be non-adherent to diet (OR (Odds Ratio)/95% CI: 2.19/1.21&ndash;3.99) than patients in the high HL group. Patients in the low HL and moderate HL group more likely reported depression or anxiety. Patients reporting depression (OR/95% CI: 1.94/1.26&ndash;2.98) or anxiety (OR/95% CI: 1.81/1.22&ndash;2.69) were more likely to be non-adherent with diet. Adjustment for depression reduced the association between moderate HL and DN-A by 19.5%. Adjustment for anxiety reduced the association between moderate HL and DN-A by 11.8%. Anxiety and depression partly mediated the association of HL with DN-A. More attention should be paid to treating patients&rsquo; psychological distress to ensure adequate adherence with recommended diet

Low Health Literacy Is Associated with Poorer Physical and Mental Health-Related Quality of Life in Dialysed Patients

Health-related quality of life (HRQoL) is an important health indicator in chronic diseases like kidney diseases. Health literacy (HL) may strongly affect HRQoL, but evidence is scarce. Therefore, we assessed the associations of HL with HRQoL in dialysed patients. We performed a cross-sectional study in 20 dialysis clinics across Slovakia (n = 542 patients, mean age = 63.6 years, males = 60.7%). We assessed the association of categorised HL (low, moderate, high) with the SF36 physical component score (PCS) and mental component score (MCS) using generalised linear models adjusted for age, gender, education, and comorbidity (Charlson Comorbidity Index, CCI). We found significant associations of HL with PCS and MCS in dialysed patients, adjusted for age, gender, education, and CCI. Low-HL patients had a lower PCS (B = −3.27, 95%-confidence interval, CI: −5.76/−0.79) and MCS (B = −6.05, 95%-CI: −8.82/−3.29) than high-HL patients. Moderate-HL patients had a lower MCS (B = −4.26, 95%-CI: −6.83/−1.69) than high-HL patients. HL is associated with physical and mental HRQoL; this indicates that dialysed patients with lower HL deserve specific attention and tailored care to have their HRQoL increased

Critical behaviour of the Rouse model for gelling polymers

It is shown that the traditionally accepted "Rouse values" for the critical exponents at the gelation transition do not arise from the Rouse model for gelling polymers. The true critical behaviour of the Rouse model for gelling polymers is obtained from spectral properties of the connectivity matrix of the fractal clusters that are formed by the molecules. The required spectral properties are related to the return probability of a "blind ant"-random walk on the critical percolating cluster. The resulting scaling relations express the critical exponents of the shear-stress-relaxation function, and hence those of the shear viscosity and of the first normal stress coefficient, in terms of the spectral dimension $d_{s}$ of the critical percolating cluster and the exponents $\sigma$ and $\tau$ of the cluster-size distribution.Comment: 9 pages, slightly extended version, to appear in J. Phys.