Common-reflection-surface imaging of shallow and ultrashallow reflectors

We analyzed the feasibility of the common-reflection-surface (CRS) stack for near-surface surveys as an alternative to the conventional common midpoint (CMP) stacking procedure. The data-driven, less user-interactive CRS method could be more cost efficient for shallow surveys, where the high sensitivity to velocity analysis makes data processing a critical step. We compared the results for two field data sets collected to image shallow and ultrashallow reflectors: an example of shallow Pwave reflection for targets in the first few hundred meters, and an example of SH-wave reflection for targets in the first 10 m. By processing the shallow P-wave records using the CMP method, we imaged several nearly horizontal reflectors with onsets from 60 to about 250 ms. The CRS stack produced a stacked section more suited for a subsurface interpretation, without any preliminary formal and time-consuming velocity analysis, because the imaged reflectors possessed greater coherency and lateral continuity. With CMP processing of the SHwave records, we imaged a dipping bedrock interface below four horizontal reflectors in unconsolidated, very low velocity sediments. The vertical and lateral resolution was very high, despite the very shallow depth: the image showed the pinchout of two layers at less than 10 m depth. The numerous traces used by the CRS stack improved the continuity of the shallowest reflector, but the deepest overburden reflectors appear unresolved, with not well-imaged pinchouts. Using the kinematic wavefield attributes determined for each stacking operation, we retrieved velocity fields fitting the stacking velocities we had estimated in the CMP processing. The use of CRS stack could be a significant step ahead to increase the acceptance of the seismic reflection method as a routine investigation method in shallow and ultrashallow seismics

Can You Hear Me Now? Assessing Students\u27 Classroom Communication Preferences via a Telephone Conference Activity

Telephone conference presentation delivery was compared to face-to-face classroom delivery in an undergraduate business course setting to assess whether concern over presenting in front of the class and/or gender impacted presentation mode preference. After completing a classroom exercise, students (n=102) were surveyed and asked to compare delivery methods from two courses, one requiring a telephone conference and the other requiring a face-to-face classroom presentation, in terms of perceived effectiveness, feedback, teamwork, instructor cues, preparation time, and overall comfort. Independent sample t-test results indicated respondents who worried about presenting in front of the class believed the telephone conference format required more attention to verbal presentation quality, and they also worried more about presenting in the telephone conference format than respondents who did not worry about presenting in front of the class. In terms of gender, female respondents indicated more attention to visual aid was required during the teleconference format, believed the teleconference presentation format allowed for the same opportunity for feedback from the instructor as the formal presentation, were more likely to indicate they were concerned about speaking in front of the classroom during formal presentations, and were also more concerned about speaking during the teleconference than male respondents. Overall, results indicated the teleconference activity was perceived to be a practical alternative to the traditional face-to-face delivery method; however, females’ perceptions of discomfort across both delivery formats warrant further study

Head injuries in early childhood in the UK; is there a social gradient?

Objectives To examine if there is a social gradient in early childhood head injuries among UK children. Methods Cross-sectional study, using data from the UK Millennium Cohort Study (MCS). The second, third and fourth sweeps of the MCS were analysed separately, when children were 3, 5 and 7 years old. Logistic regression models were used to explore the associations between head injuries and family socioeconomic position (social class, household income, maternal education and area deprivation). Results The unadjusted analyses showed different associations with socioeconomic indicators at different ages. At age 3 and 5 years, head injuries were associated with higher area deprivation, lower household income and parents not being in work or in the routine social class. At age 5 years head injuries were also associated with lower maternal education. At age 7 years only associations with area deprivation and maternal education were found. In adjusted analyses (mutually adjusted for all four socioeconomic indicators, maternal age, child age and child sex), the following associations were observed: at ages 3 and 5 years, higher levels of area deprivation were related to higher odds of head injuries. At age 3 years only, lower levels of maternal education were related to lower odds of head injuries. No social gradients were observed. At age 7 years, there were no significant associations between head injuries and any of the SEP measures. Conclusion We observed no social gradients in early childhood head injuries. However, at ages 3 and 5 years, head injuries were more frequently reported for children living in more deprived areas

Traumatic dental injuries and socioeconomic position – findings from the Children's Dental Health Survey 2013

OBJECTIVES: The aim of this study was to assess whether traumatic dental injuries (TDI) were socially graded among children and adolescents in England, Wales and Northern Ireland, using nationally representative data from the Children's Dental Health Survey (CDHS) 2013. METHODS: This cross-sectional study used data from the Children's Dental Health Survey 2013 which was conducted among a nationally representative sample of schoolchildren in England, Wales and Northern Ireland. Children's family socioeconomic position (SEP) was measured through free school meal eligibility and relative area deprivation using the Indices of Multiple Deprivation. The analytical sample included 6707 schoolchildren aged 8, 12 and 15. Multiple logistic regression was used to model the associations between experience of TDI and the two markers of SEP, after adjusting for sex and age. RESULTS: The overall prevalence of traumatic dental injuries to permanent incisors was 9% (n = 590). There were no statistically significant associations between TDI and either SEP measure. Further subgroup analyses (n = 2650) showed also no significant associations between TDI and additional SEP markers (parental education and social class). The odds of having sustained a traumatic dental injury were higher for boys than for girls and were greater in older age groups. CONCLUSIONS: This study found no significant relationships between the experience of traumatic dental injuries and two markers of family socioeconomic position among children living in England, Wales and Northern Ireland. This implies that rather than specifically targeting the more deprived sectors of society, TDI prevention policies should use upstream public health strategies incorporating a whole-population approach

DNA-DSB in CHO-K1 cells induced by heavy-ions: Break rejoining and residual damage (GSI)

DNA double strand breaks (DSB's) are the critical lesions involved in cellular effects of ionizing radiation. Therefore, the evaluation of DSB induction in mammalian cells after heavy ion irradiation is an essential task for the assessment of high-LET radiation risk in space. Of particular interest has been the question of how the biological efficiency for the cellular inactivation endpoint relates to the initial lesions (DSBs) at varying LETs. For cell killing, an increased Relative Biological Efficiency (RBE) has been determined for highLET radiation around 100-200 keV/mu m. At higher LET, the RBE's decrease again to values below one for the very heavy particles. At GSI, DSB-induction was measured in CHO-K1 cells following irradiation with accelerated particles covering a wide LET range. The electrophoretic elution of fragmented DNA out of agarose plugs in a constant electrical field was applied for the detection of DSB's. The fraction of DNA retained was determined considering the relative intensities of ethidium bromide fluorescence in the well and in the gel lane. Dose-effect curves were established, from which the RBE for DSB induction was calculated at a fraction of 0.7 of DNA retained In summary, these rejoining studies are in line with an enhanced severity of the DNA DSB's at higher LET's, resulting in a decreased repairability of the induced lesions. However, no information concerning the fidelity of strand breaks rejoining is provided in these studies. To assess correct rejoining of DNA fragments an experimental system involving individual DNA hybridization bands has been set up. In preliminary experiments Sal I generated DNA fragments of 0.9 Mbp were irradiated with xrays and incubated for repair However, restitution of the original signals was not observed, probably due to the high radiation dose necessary for breakage of a fragment of this size. A banding pattern with NotI hybridization signals in a higher MW range (3Mbp) has been obtained by varying the electrophoretic conditions and correct rejoining studies will be further developed in this system

Cross cultural adaptation and psychometric properties of the Bengali version of the Scale of Oral Health Outcomes for 5-year-old children (SOHO-5)

BACKGROUND: The oral health related quality of life (OHRQoL) of children in Bangladesh has not yet been measured, as there is no validated OHRQoL measure for that population. The aim of this study was to cross-culturally adapt the child self-report and parental proxy report versions of the Scale of Oral Health Outcomes for 5-year-old children (SOHO-5) into Bengali and test their psychometric properties: face validity, construct validity (convergent and discriminant validity) and reliability (internal consistency and test-retest reliability), among 5-9-year-old children and their parents in Bangladesh and assess associations between dental caries/sepsis and OHRQoL in this population. METHODS: The forward-backward translated Bengali SOHO-5 was piloted among 272 children and their parents to test its face validity. The questionnaire was administered to 788 children and their parents to evaluate its psychometric properties. Internal consistency of Bengali SOHO-5 was assessed using Cronbach's alpha, and test-retest reliability was assessed using Kappa. Convergent and discriminant validity were assessed through nonparametric tests. The calculation of effect sizes and standard error of measurement facilitated the assessment of minimally important difference (MID) for SOHO-5. The associations of reporting an oral impact with caries and sepsis were assessed via logistic regression models. RESULTS: Both child self-report and parental proxy report questionnaires showed good face validity. Cronbach's alpha scores were 0.79 and 0.87 for child and parental questionnaire, respectively. A weighted Kappa score of 0.85 demonstrated test-retest reliability of child questionnaire. SOHO-5 scores were significantly associated with subjective oral health outcomes and discriminated clearly between different caries severity and sepsis groups. These differences were considerably higher than the MID. After adjusting for child's age, sex, setting, maternal education and family income, the odds of reporting an oral impact were 2.25 (95% CI 1.98-2.56) and 4.44 (95% CI 3.14-6.28) times higher for each additional tooth with caries and sepsis, respectively. CONCLUSION: This study provided strong evidence supporting the validity and reliability of both versions of Bengali SOHO-5 as OHRQoL measures. Dental caries and sepsis were associated with poor OHRQoL in this population. The Bengali SOHO-5 is expected to be a useful outcome measure for research and clinical purposes in Bengali speaking child populations

The role of oral health-related quality of life in the association between dental caries and height, weight and BMI among children in Bangladesh

Objectives: To examine whether oral health-related quality of life (OHRQoL) explained the negative associations between dental caries and anthropometric measures of child growth among a sample of 5- to 9-year-old children in Dhaka, Bangladesh, while taking potential confounding factors (maternal education, family income, study setting, child's birth weight and childhood diseases) into account. In addition, to test whether specific oral impacts had a role in explaining these associations. Methods: Data collection was conducted via a cross-sectional survey among children and their parents from both hospital and school settings in Dhaka. Dental caries and severe consequences of dental caries (defined here as dental sepsis) were the exposure variables, and age- and sex-adjusted height-z-scores (HAZ), weight-z-scores (WAZ) and BMI-z-scores (BAZ) were the outcome variables. OHRQoL was measured using the Bengali version of the Scale of Oral Health Outcomes for 5-year-old children (SOHO-5). First, associations between oral impacts (prevalence of overall impacts and specific items of the SOHO-5) and outcome measures were assessed. Multiple linear regression was used to assess associations between caries and anthropometric measures, adjusted for potential confounders. Oral impacts were then added to test whether their inclusion attenuated the associations between exposures and outcomes. To further investigate potential mediating role of oral impacts, structural equation modelling (SEM) was used to test the hypothesis that dental caries and sepsis were associated with the outcomes directly and also indirectly via oral impacts in general. A similar approach was used to investigate mediation by specific SOHO-5 items. Results: The sample consisted of 715 children, 73.1% of whom had dental caries, 37.5% presented with sepsis, and 57.3% reported at least one oral impact (SOHO-5 score ≥1). Prevalence of overall oral impacts and also the impact on ‘eating difficulty’ (a specific item of SOHO-5) were negatively associated with all three outcomes. Dental caries and sepsis was associated with lower HAZ, WAZ and BAZ, and adjustment for overall oral impacts considerably attenuated the associations between ‘severe dental caries’ and outcomes, and dental sepsis and outcomes. Using SEM, we found significant indirect associations between caries and sepsis and anthropometric measures via oral impacts (except for dental caries and HAZ). Considering specific oral impacts, eating difficulties explained about 44% and 65% of the associations between caries and anthropometric outcomes, and dental sepsis and anthropometric outcomes, respectively. Conclusions: Oral impacts, in particular eating difficulties, appear to mediate associations between caries and markers of child growth among this population

Overriding Intrinsic Reactivity in Aliphatic C−H Oxidation: Preferential C3/C4 Oxidation of Aliphatic Ammonium Substrates

The site-selective C−H oxidation of unactivated positions in aliphatic ammonium chains poses a tremendous synthetic challenge, for which a solution has not yet been found. Here, we report the preferential oxidation of the strongly deactivated C3/C4 positions of aliphatic ammonium substrates by employing a novel supramolecular catalyst. This chimeric catalyst was synthesized by linking the well-explored catalytic moiety Fe(pdp) to an alkyl ammonium binding molecular tweezer. The results highlight the vast potential of overriding the intrinsic reactivity in chemical reactions by guiding catalysis using supramolecular host structures that enable a precise orientation of the substrates

Failure of Mean Field Theory at Large N

We study strongly coupled lattice QCD with $N$ colors of staggered fermions in 3+1 dimensions. While mean field theory describes the low temperature behavior of this theory at large $N$, it fails in the scaling region close to the finite temperature second order chiral phase transition. The universal critical region close to the phase transition belongs to the 3d XY universality class even when $N$ becomes large. This is in contrast to Gross-Neveu models where the critical region shrinks as $N$ (the number of flavors) increases and mean field theory is expected to describe the phase transition exactly in the limit of infinite $N$. Our work demonstrates that close to second order phase transitions infrared fluctuations can sometimes be important even when $N$ is strictly infinite.Comment: 4 pages, 3 figure

Does water fluoridation influence ethnic inequalities in caries in Brazilian children and adolescents?

Objectives: This study aimed to investigate the influence of community water fluoridation on ethnic inequalities in untreated dental caries among children and adolescents in Brazil while taking the human development context into account. / Methods: Data from a nationwide Brazilian epidemiological population oral health survey were used (SB Brazil 2010). Outcomes were caries prevalence measured by the proportion of individuals with one or more untreated decayed teeth and caries severity defined by the mean number of untreated decayed teeth (DT). Three different contexts were considered: 1—cities with no water fluoridation; 2—cities with water fluoridation and low Human Development Index (HDI); and 3—cities with water fluoridation and high HDI. The exposure was ethnic/racial group (White, Pardo, Black) and covariates were age, sex and household income. Multilevel logistic and negative binomial regressions were performed with 6696 children (aged 5 years) and 11 585 adolescents (aged 12 and 15-19 years). / Results: For both children and adolescents, ethnic differences in caries prevalence and mean DT were found in the nonfluoridated cities with low HDI and also in cities with high HDI, most of which were fluoridated. For example in nonfluoridated cities with low HDI, 5-year-old Pardo children were more likely to have untreated decay (OR = 1.22; 95% CI: 1.02, 1.46) and had more decayed teeth (RR = 1.18; 95% CI: 1.04, 1.34) than their White counterparts after adjusting for sex and household income. No statistically significant differences were observed in fluoridated cities with low HDI. / Conclusion: Water fluoridation appears to be associated with reduced ethnic inequalities in dental caries prevalence and mean DT among children and adolescents in more disadvantaged settings