β-pyrophosphate: A potential biomaterial for dental applications

Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped β-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of β-pyrophosphate pellets (sintered at 1000 °C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the β-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of β-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped β-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped β-pyrophosphate may be a promising material for restoring acid eroded and worn enamel

Sensitivity of planetary cruise navigation to earth orientation calibration errors

A detailed analysis was conducted to determine the sensitivity of spacecraft navigation errors to the accuracy and timeliness of Earth orientation calibrations. Analyses based on simulated X-band (8.4-GHz) Doppler and ranging measurements acquired during the interplanetary cruise segment of the Mars Pathfinder heliocentric trajectory were completed for the nominal trajectory design and for an alternative trajectory with a longer transit time. Several error models were developed to characterize the effect of Earth orientation on navigational accuracy based on current and anticipated Deep Space Network calibration strategies. The navigational sensitivity of Mars Pathfinder to calibration errors in Earth orientation was computed for each candidate calibration strategy with the Earth orientation parameters included as estimated parameters in the navigation solution. In these cases, the calibration errors contributed 23 to 58% of the total navigation error budget, depending on the calibration strategy being assessed. Navigation sensitivity calculations were also performed for cases in which Earth orientation calibration errors were not adjusted in the navigation solution. In these cases, Earth orientation calibration errors contributed from 26 to as much as 227% of the total navigation error budget. The final analysis suggests that, not only is the method used to calibrate Earth orientation vitally important for precision navigation of Mars Pathfinder, but perhaps equally important is the method for inclusion of the calibration errors in the navigation solutions

The Pioneer Anomaly

Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of the Newton's gravitational inverse-square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living Reviews in Relativit

Understanding the Impact on Healthcare Professionals of Viewing Digital Stories of Adults with Cancer: A Hermeneutic Study

The purpose of this study was to understand the effects on oncology healthcare providers (HCPs), both personally and professionally, of watching digital stories made by adults with cancer (past and present), and what HCPs envisioned for the uses of digital stories. Seven healthcare professionals from various disciplines volunteered for this study. This research took place in a large urban center in Western Canada and was done in the tradition of philosophical hermeneutics. A 90-minute focus group was used for data collection, where participants watched eight digital stories (batched in four groups of two stories) that had been created by individuals with cancer (past or present). Data was analyzed using an interpretive qualitative methodology. Findings revealed that watching digital stories made by adults with cancer was emotionally compelling, provided context, incited deep introspection, and may offer a protective effect with respect to HCP burnout

Places of Practice: Learning to Think Narratively

In the lived practices of narrative inquiry, we honour our relational ontological commitments and responsibilities as narrative inquirers. In this paper, we link these ontological commitments with our practice, which is often tension-filled because the knowledge landscape on which we live as researchers is shaped by paradigmatic rather than narrative knowledge. It is easy to get swept into thinking paradigmatically and to sustain ourselves as narrative inquirers amidst knowledge landscapes that cast narrative inquirers as not knowing when seen from within dominant plotlines. We see that not to fall into these dominant plotlines requires wakefulness to shaping places where we can practice thinking narratively

Study of heavy metal concentration and partitioning in the Estrela River: implications for the pollution in Guanabara Bay - SE Brazil

In this study, the geochemical analysis of ten sediment samples collected along the fluvial system of the Estrela River, which flows into the northern portion of Guanabara Bay, shows the presence of anthropogenic impacts in this area. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni obtained were slightly higher, when compared with values found innatural environments. The particle size and organic matter content in most of the analyzed stations showed featuresnot conducive to the accumulation of pollutants due to the low organic matter content and the strong presence ofsand fraction. There was also the fractionation of heavy metals in sediments and it was found the prominence ofresidual and reducible phase, besides the significant occurrence of organic fractions in some analyzed stations. Thesefactors, thus, highlight the potential risks of contamination, where the metals associated with the organic phase canbecome bioavailable in processes of dissolution, provided by physico-chemical changes that can occur in this aquaticenvironment.</jats:p

Hemocolecisto primitivo con hemobilia por colecistitis hemorrágica

The authors refer to a case of primitive hemocholecyst with hemobile due to hemorrhagic cholecystitis. The case is discussed- with reference to diagnosis and treatment of this rare complication of cholelithiasis.Presentación de un caso de hemocolecisto primitivo con hemobilis por colecistitis hemorrágica. Apropósito de la observación se realizan consideraciones, de diagnóstico y tratamiento de esta rara complicación de la litiasis vesicular

Middle school effects of the Dating Matters (R) comprehensive teen dating violence prevention model on physical violence, bullying, and cyberbullying:A cluster-randomized controlled trial

Few comprehensive primary prevention approaches for youth have been evaluated for effects on multiple types of violence. Dating Matters®: Strategies to Promote Healthy Teen Relationships (Dating Matters) is a comprehensive teen dating violence (TDV) prevention model designed by the Centers for Disease Control and Prevention and evaluated using a longitudinal stratified cluster-randomized controlled trial to determine effectiveness for preventing TDV and promoting healthy relationship behaviors among middle school students. In this study, we examine the prevention effects on secondary outcomes, including victimization and perpetration of physical violence, bullying, and cyberbullying. This study examined the effectiveness of Dating Matters compared to a standard-of-care TDV prevention program in 46 middle schools in four high-risk urban communities across the USA. The analytic sample (N = 3301; 53% female; 50% Black, non-Hispanic; and 31% Hispanic) consisted of 6th–8th grade students who had an opportunity for exposure to Dating Matters in all three grades or the standard-of-care in 8th grade only. Results demonstrated that both male and female students attending schools implementing Dating Matters reported 11% less bullying perpetration and 11% less physical violence perpetration than students in comparison schools. Female Dating Matters students reported 9% less cyberbullying victimization and 10% less cyberbullying perpetration relative to the standard-of-care. When compared to an existing evidence-based intervention for TDV, Dating Matters demonstrated protective effects on physical violence, bullying, and cyberbullying for most groups of students. The Dating Matters comprehensive prevention model holds promise for reducing multiple forms of violence among middle school-aged youth

Effects of the Dating Matters® comprehensive prevention model on health- and delinquency-related risk behaviors in middle school youth:A cluster-randomized controlled trial

Teen dating violence (TDV) is associated with a variety of delinquent behaviors, such as theft, and health- and delinquency-related risk behaviors, including alcohol use, substance abuse, and weapon carrying. These behaviors may co-occur due to shared risk factors. Thus, comprehensive TDV-focused prevention programs may also impact these other risk behaviors. This study examined the effectiveness of CDC's Dating Matters (R): Strategies to Promote Healthy Teen Relationships (Dating Matters) comprehensive TDV prevention model compared to a standard-of-care condition on health- and delinquency-related risk behaviors among middle school students. Students (N = 3301; 53% female; 50% black, non-Hispanic; and 31% Hispanic) in 46 middle schools in four sites across the USA were surveyed twice yearly in 6th, 7th, and 8th grades. A structural equation modeling framework with multiple imputation to account for missing data was utilized. On average over time, students receiving Dating Matters scored 9% lower on a measure of weapon carrying, 9% lower on a measure of alcohol and substance abuse, and 8% lower on a measure of delinquency by the end of middle school than students receiving an evidence-based standard-of-care TDV prevention program. Dating Matters demonstrated protective effects for most groups of students through the end of middle school. These results suggest that this comprehensive model is successful at preventing risk behaviors associated with TDV. clinicaltrials.gov Identifier: NCT01672541

An RCT of dating matters:Effects on teen dating violence and relationship behaviors

Introduction Teen dating violence is a serious public health problem with few effective prevention strategies. This study examines whether the Dating Matters comprehensive prevention model, compared with a standard of care intervention, prevented negative relationship behaviors and promoted positive relationship behaviors. Study design This longitudinal, cluster-RCT compared the effectiveness of Dating Matters with standard of care across middle school. Standard of care was an evidence-based teen dating violence prevention curriculum (Safe Dates) implemented in eighth grade. Setting/participants Forty-six middle schools in high-risk urban neighborhoods in four U.S. cities were randomized. Schools lost to follow-up were replaced with new schools, which were independently randomized (71% school retention). Students were surveyed in fall and spring of sixth, seventh, and eighth grades (2012–2016). The analysis sample includes students from schools implementing Dating Matters or standard of care for >2 years who started sixth grade in the fall of 2012 or 2013 and had dated (N=2,349 students, mean age 12 years, 49% female, and 55% black, non-Hispanic, 28% Hispanic, 17% other). Intervention Dating Matters is a comprehensive, multicomponent prevention model including classroom-delivered programs for sixth to eighth graders, training for parents of sixth to eighth graders, educator training, a youth communications program, and local health department activities to assess capacity and track teen dating violence–related policy and data. Main outcome measures Self-reported teen dating violence perpetration and victimization, use of negative conflict resolution strategies, and positive relationship skills were examined as outcomes. Imputation and analyses were conducted in 2017. Results Latent panel models demonstrated significant program effects for three of four outcomes; Dating Matters students reported 8.43% lower teen dating violence perpetration, 9.78% lower teen dating violence victimization, and 5.52% lower use of negative conflict resolution strategies, on average across time points and cohorts, than standard of care students. There were no significant effects on positive relationship behaviors. Conclusions Dating Matters demonstrates comparative effectiveness, through middle school, for reducing unhealthy relationship behaviors, such as teen dating violence and use of negative conflict resolution strategies, relative to the standard of care intervention