Measuring beliefs about orthodontic treatment: a questionnaire approach

OBJECTIVES: Few studies have examined what parents and orthodontists expect from and value about orthodontic treatment. In this study, we designed and tested a questionnaire to outline what drives consumer demand for children's orthodontic care. Further, we present data from the questionnaire to illustrate how expectations and values pertaining to orthodontic treatment relate to sociodemographic variables. METHODS: Subjects were 220 Pennsylvania orthodontists and 220 parents at a university orthodontic clinic who were administered a questionnaire designed to assess what parents and orthodontists value about and expect from orthodontic treatment. Items for the questionnaire were developed via a qualitative, telephone interview process. Data were analyzed using factor analysis and reliability analysis for scale development, and analysis of variance for preliminary validity assessment. RESULTS: Through factor analysis, the questionnaire was reduced from 84 to 52 items, and eight scales were examined: expected treatment benefits, expected treatment risks (short- and long-term), expected treatment inconveniences, value of treatment benefits, value of risks (short- and long-term), and value of treatment inconveniences. For parents, the reliability for all scales was in the acceptable range. For orthodontists, only the "short-term risks" scale failed to attain an acceptable reliability. Preliminary validity was assessed through examining relationships between demographic variables and subscale scores. For parents, income, father's education level, and sex of respondent were related to treatment expectations and values. For orthodontists, age, sex, and patient volume were related to treatment values. CONCLUSIONS: The questionnaire developed in the present study was found to be practical and reliable for use with providers and consumers of orthodontic care and can be used to explore factors affecting the demand for orthodontic care. Implications of possible unrealistic treatment expectations on the part of orthodontists and parents also are discussed.     

Immune stimulation--a class effect of phosphorothioate oligodeoxynucleotides in rodents

Respiratory support of newborn infants has changed in the last 25 years, because of new knowledge of patho-physiology, controlled studies of respiratory therapy and the realisation of perinatal centers. Respiratory support has changed from the "blow in--suck out" approach, inevitably leading to severe atelectasis, high morbidity and mortality to a now very sophisticated therapy with reduced mortality and morbidity also in very-low-birth-weight infants, who were hopeless patients 25 years ago. Major milestones of this development were the introduction of continuous distending pressure to surfactant deficient lungs, the high-frequency positive pressure ventilation with fine tuning of inspiratory and expiratory times, adjusted to individual time constants and the substitution of artificial surfactant. Techniques for the future, like HFO, NO-inhalation, proportional assist ventilation and liquid ventilation are presently investigated.     

Understanding the Role of Grain Boundaries on Charge-Carrier and Ion Transport in Cs2AgBiBr6 Thin Films

Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air, and recent demonstrations of long charge-carrier lifetimes that can exceed 1 µs. In particular, Cs₂AgBiBr₆ is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs₂AgBiBr₆ thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field-effect transistor and temperature-dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs₂AgBiBr₆ single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single-crystal properties.     

Software engineering practices and Simulink: bridging the gap

International Journal on Software Tools for Technology Transfer - Although widely used in embedded systems design, Matlab/Simulink is not considered a state-of-the-art design environment by the...     

Generalized radial‐return mapping algorithm for anisotropic von Mises plasticity framed in material eigenspace

A computationally efficient integration algorithm for anisotropic plasticity is proposed, which is identified as a generalization of the radial‐return mapping algorithm to anisotropy. The algorithm is based upon formulation within the eigenspace of a material anisotropy tensor associated with anisotropic quadratic von Mises (J₂) plasticity (also called Hill plasticity), for which it is shown to ensure that the flow rule remains associative, ie, the normality condition is satisfied. Extension of the algorithm to include anisotropic elasticity (anisotropic elastoplasticity) is further provided, made possible by the identification of a certain fourth‐order material tensor dependent on both the elastic and plastic anisotropy. The derivation of the fully elastoplastically anisotropic algorithm involves further complexity, but the resulting algorithm is shown to closely resemble the purely plastically anisotropic one once the appropriate eigenspace is identified. The proposed generalized radial‐return algorithm is compared to a classical closest‐point projection algorithm, for which it is shown to provide considerable advantage in computational cost. The efficiency, accuracy, and robustness of the algorithm are demonstrated through various illustrative test cases and in the finite element simulation of Taylor impact tests on tantalum.     

Histomorphometric and histologic evaluation of titanium–zirconium (<Emphasis Type="Italic">a</Emphasis>TiZr) implants with anodized surfaces

The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing dl-α-glycerophosphate and calcium acetate at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, atomic force microscopy and goniometry. Forty implant discs with thickness of 1.5 and 10 mm diameter (10 of each-titanium, titanium–zirconium, anodized titanium and anodized titanium–zirconium) were placed in the femoral condyles of 10 sheep. Histomorphometric and histologic analysis were performed 4 weeks after implantation. The anodized implants displayed hydrophilic, porous, nano-to-micrometer scale roughened surfaces. Energy dispersive spectroscopy analysis revealed calcium and phosphorous incorporation into the surface of both titanium and titanium–zirconium after anodization. Histologically there was new bone apposition on all implanted discs, slightly more pronounced on anodised discs. The percentage bone-to-implant contact measurements of anodized implants were higher than machined/unmodified implants but there was no significant difference between the two groups with anodized surfaces (P > 0.05, n = 10). The present histomorphometric and histological findings confirm that surface modification of titanium–zirconium by anodization is similar to anodised titanium enhances early osseointegration compared to machined implant surfaces.     

Accumulation rates,focusing factors,and chronologies from depth profiles of 210Pb and 137Cs in sediments of the Laurentian Great Lakes

Sediment cores from 41 sites were collected from the Laurentian Great Lakes during 2010–2014, sectioned into 0.5–2.0?cm intervals, and the activities of ²¹⁰Pb, ¹³⁷Cs, and ²²⁶Ra were measured in the upper 25 to 40?cm of the sediment column by gamma spectrometry. Sediment mass accumulation rates (dry mass) calculated from ²¹⁰Pb profiles range from 0.006?±?0.001 to 0.59?±?0.06?g?cm^?2?yr ^?1 and are similar to those reported in previous Great Lakes sediment studies. Sediment mass accumulation rates decreased with increasing water depth. ²¹⁰Pb-based models in cores exhibiting favorable characteristics (i.e., those having the highest unsupported-²¹⁰Pb activity at the sediment-water interface, exponential decrease of unsupported-²¹⁰Pb with increasing depth in sediment cores, and a clear peak in ¹³⁷Cs activity at some depth below the sediment-water interface) give calendar date profiles that are largely concordant with the maximum ¹³⁷Cs peak activity at 1963. Sediment focusing factors derived from unsupported-²¹⁰Pb inventories range from 0.09 to >5.34, and are well correlated with those derived from ¹³⁷Cs inventories that range from 0.07 to 4.04, demonstrating the ubiquitous occurrence of horizontal sediment transport processes within the lakes. This more recent survey provides a Great Lakes-wide chronological framework for comparing the depositional histories and inventories of a wide variety of persistent, bioaccumulative and toxic pollutants that have been measured in the same sediment cores. This information will be useful for resolving scientific and practical issues pertaining to the environmental quality and management of contaminated sediments in the Laurentian Great Lakes ecosystem.     

Temporal and spatial differences in deposition of organic matter and black carbon in Lake Michigan sediments over the period 1850–2010

Inorganic carbon (IC), total organic carbon (OC), and black carbon (BC) were analyzed in eight sediment cores obtained from deep water (>30 m) sediments in the Chippewa and south Chippewa basins, as well as Green Bay in Lake Michigan. These cores were segmented at high resolution and radio-dated to reconstruct a detailed history of deposition to the lake both spatially and temporally since ca. 1850 CE. To help interpret the depositional record, cores were also characterized for stable isotopes (¹³C and ¹⁵N), as well as particle size distribution, density, organic matter (OM), and other parameters. Fine (silt and clay) sediment particles contained OM of primarily lacustrine algal biomass origin. Sedimentation fluxes showed large increases in OM and OC fluxes through much of the lake during the onset of industrialization and the period of rapid industrialization to onset of Great Lakes environmental legislation. In contrast, fluxes and loading of BC increased dramatically in the southern basin until the 1930's, then decreased substantially after the 1940's. This observation was due largely to results from site M009 nearest the steel mills and industrial zones of Chicago and northern Indiana. Together, whole lake loadings of OM and BC provide evidence that changing industrial activity and legislation intended to curb air pollution in the Great Lakes region have had a fairly rapid and dramatic impact. In contrast, legislation intended to decrease eutrophication through reductions in nutrient loading to the lake have not had a similar impact on sedimentation of OM in the lake.     

On the use of secret sharing as a secure multi-use pad

Secret sharing (SS) is a cryptographic method proposed independently by Adi Shamir and George Blakley in 1979 to encode the keys of public-key cryptography by splitting them into maximally entropic shares that are distributed to participants, only revealing the secret when combined. Each new sharing instance, even of the same key, produces a different set of shares to distribute anew. This paper investigates SS as an independent cipher to secure confidential messages between a limited set of trusted participants by eliminating the need to redistribute shares. A participant’s master share is permanently fixed and unlimited temporary shares are created and combined with it to reveal new messages. Security is argued against specific and general attacks.