With Mexican Americans constituting a large and growing segment of U.S. society, their assimilation trajectory has become a constant source of debate. Some believe Mexican Americans are following the ...path of European immigrants toward full assimilation into whiteness, while others argue that they remain racialized as nonwhite. Drawing on extensive interviews with Mexican Americans and Mexican immigrants in Texas, Dowling's research challenges common assumptions about what informs racial labeling for this population. Her interviews demonstrate that for Mexican Americans, racial ideology is key to how they assert their identities as either in or outside the bounds of whiteness. Emphasizing the link between racial ideology and racial identification, Dowling offers an insightful narrative that highlights the complex and highly contingent nature of racial identity.
This paper describes an experimental investigation of acoustically forced lean premixed turbulent bluff-body-stabilised flames in an enclosure short enough so that no coupling of the combustor ...downstream acoustics occurred for the frequencies studied here, which allows an unambiguous examination of the flame response to inlet velocity fluctuations. Special emphasis was placed on the amplitude dependence of this response. Measurements of the heat release rate were performed with OH
∗ and CH
∗ chemiluminescence, planar laser-induced fluorescence (PLIF) of OH from which the flame surface density (FSD) was computed, and simultaneous CH
2O and OH PLIF imaging from which the local heat release rate (RX) was estimated. The global heat release measured with chemiluminescence and that integrated from the local FSD measurements were in close agreement, while a comparison between FSD and high-resolution RX imaging also showed good agreement. This suggests that estimates of the flame area are sufficient to determine heat release rate for this flow. The heat release response became nonlinear after inlet velocity amplitudes of around 15% of the bulk velocity. This value depended on the forcing frequency and the equivalence ratio. The nonlinearity was found to occur when the shear layers rolled up into vortices. The vortices induced by the inlet velocity fluctuations not only generated flame area when the flame wrapped around them, but also caused cusps and even large-scale flame annihilation events, as observed in time-resolved OH PLIF images. Such events occurred when parts of the flame stabilised on the inner shear layer close to the recirculation zone collapsed on parts of the flame stabilised on the outer recirculation zone, a phenomenon that was made more prominent with increasing forcing amplitude. A further nonlinearity occurred at high amplitudes and at some equivalence ratios, where a significant leakage of energy to higher harmonics was observed, but the origin of this is not yet clarified. The present results suggest that the flame sheet kinematics play a major role in the saturation mechanism of lean premixed flame response, hence extending previous experimental and analytical results from laminar to turbulent flames. Heat release fluctuations due to local fluctuations of strain rate and curvature were less significant, while no localised extinction has been observed even at large forcing amplitudes.
This systematic review aimed to identify early risk and protective factors (in childhood, adolescence or young adulthood) longitudinally associated with the subsequent development of gambling ...problems. A systematic search of peer-reviewed and grey literature from 1990 to 2015 identified 15 studies published in 23 articles. Meta-analyses quantified the effect size of 13 individual risk factors (alcohol use frequency, antisocial behaviours, depression, male gender, cannabis use, illicit drug use, impulsivity, number of gambling activities, problem gambling severity, sensation seeking, tobacco use, violence, undercontrolled temperament), one relationship risk factor (peer antisocial behaviours), one community risk factor (poor academic performance), one individual protective factor (socio-economic status) and two relationship protective factors (parent supervision, social problems). Effect sizes were on average small to medium and sensitivity analyses revealed that the results were generally robust to the quality of methodological approaches of the included articles. These findings highlight the need for global prevention efforts that reduce risk factors and screen young people with high-risk profiles. There is insufficient investigation of protective factors to adequately guide prevention initiatives. Future longitudinal research is required to identify additional risk and protective factors associated with problem gambling, particularly within the relationship, community, and societal levels of the socio-ecological model.
•First systematic review of risk and protective factors for problem gambling•Strongest risk factors were gambling severity, male gender, poor school performance•Protective factors included parental supervision and high socio-economic status•Results were generally robust to the quality of methodological approaches•Need for future research to explore relationship, community, and societal factors
Objective:
The aim of this paper was to systematically review and meta-analyse the prevalence of co-morbid psychiatric disorders (DSM-IV Axis I disorders) among treatment-seeking problem gamblers.
...Methods:
A systematic search was conducted for peer-reviewed studies that provided prevalence estimates of Axis I psychiatric disorders in individuals seeking psychological or pharmacological treatment for problem gambling (including pathological gambling). Meta-analytic techniques were performed to estimate the weighted mean effect size and heterogeneity across studies.
Results:
Results from 36 studies identified high rates of co-morbid current (74.8%, 95% CI 36.5–93.9) and lifetime (75.5%, 95% CI 46.5–91.8) Axis I disorders. There were high rates of current mood disorders (23.1%, 95% CI 14.9–34.0), alcohol use disorders (21.2%, 95% CI 15.6–28.1), anxiety disorders (17.6%, 95% CI 10.8–27.3) and substance (non-alcohol) use disorders (7.0%, 95% CI 1.7–24.9). Specifically, the highest mean prevalence of current psychiatric disorders was for nicotine dependence (56.4%, 95% CI 35.7–75.2) and major depressive disorder (29.9%, 95% CI 20.5–41.3), with smaller estimates for alcohol abuse (18.2%, 95% CI 13.4–24.2), alcohol dependence (15.2%, 95% CI 10.2–22.0), social phobia (14.9%, 95% CI 2.0–59.8), generalised anxiety disorder (14.4%, 95% CI 3.9–40.8), panic disorder (13.7%, 95% CI 6.7–26.0), post-traumatic stress disorder (12.3%, 95% CI 3.4–35.7), cannabis use disorder (11.5%, 95% CI 4.8–25.0), attention-deficit hyperactivity disorder (9.3%, 95% CI 4.1–19.6), adjustment disorder (9.2%, 95% CI 4.8–17.2), bipolar disorder (8.8%, 95% CI 4.4–17.1) and obsessive-compulsive disorder (8.2%, 95% CI 3.4–18.6). There were no consistent patterns according to gambling problem severity, type of treatment facility and study jurisdiction. Although these estimates were robust to the inclusion of studies with non-representative sampling biases, they should be interpreted with caution as they were highly variable across studies.
Conclusions:
The findings highlight the need for gambling treatment services to undertake routine screening and assessment of psychiatric co-morbidity and provide treatment approaches that adequately manage these co-morbid disorders. Further research is required to explore the reasons for the variability observed in the prevalence estimates.
Purpose
Magnetic resonance imaging (MRI)‐guided radiation therapy (RT) treatment planning is limited by the fact that the electron density distribution required for dose calculation is not readily ...provided by MR imaging. We compare a selection of novel synthetic CT generation algorithms recently reported in the literature, including segmentation‐based, atlas‐based and machine learning techniques, using the same cohort of patients and quantitative evaluation metrics.
Methods
Six MRI‐guided synthetic CT generation algorithms were evaluated: one segmentation technique into a single tissue class (water‐only), four atlas‐based techniques, namely, median value of atlas images (ALMedian), atlas‐based local weighted voting (ALWV), bone enhanced atlas‐based local weighted voting (ALWV‐Bone), iterative atlas‐based local weighted voting (ALWV‐Iter), and a machine learning technique using deep convolution neural network (DCNN).
Results
Organ auto‐contouring from MR images was evaluated for bladder, rectum, bones, and body boundary. Overall, DCNN exhibited higher segmentation accuracy resulting in Dice indices (DSC) of 0.93 ± 0.17, 0.90 ± 0.04, and 0.93 ± 0.02 for bladder, rectum, and bones, respectively. On the other hand, ALMedian showed the lowest accuracy with DSC of 0.82 ± 0.20, 0.81 ± 0.08, and 0.88 ± 0.04, respectively. DCNN reached the best performance in terms of accurate derivation of synthetic CT values within each organ, with a mean absolute error within the body contour of 32.7 ± 7.9 HU, followed by the advanced atlas‐based methods (ALWV: 40.5 ± 8.2 HU, ALWV‐Iter: 42.4 ± 8.1 HU, ALWV‐Bone: 44.0 ± 8.9 HU). ALMedian led to the highest error (52.1 ± 11.1 HU). Considering the dosimetric evaluation results, ALWV‐Iter, ALWV, DCNN and ALWV‐Bone led to similar mean dose estimation within each organ at risk and target volume with less than 1% dose discrepancy. However, the two‐dimensional gamma analysis demonstrated higher pass rates for ALWV‐Bone, DCNN, ALMedian and ALWV‐Iter at 1%/1 mm criterion with 94.99 ± 5.15%, 94.59 ± 5.65%, 93.68 ± 5.53% and 93.10 ± 5.99% success, respectively, while ALWV and water‐only resulted in 86.91 ± 13.50% and 80.77 ± 12.10%, respectively.
Conclusions
Overall, machine learning and advanced atlas‐based methods exhibited promising performance by achieving reliable organ segmentation and synthetic CT generation. DCNN appears to have slightly better performance by achieving accurate automated organ segmentation and relatively small dosimetric errors (followed closely by advanced atlas‐based methods, which in some cases achieved similar performance). However, the DCNN approach showed higher vulnerability to anatomical variation, where a greater number of outliers was observed with this method. Considering the dosimetric results obtained from the evaluated methods, the challenge of electron density estimation from MR images can be resolved with a clinically tolerable error.
Personalized Normative Feedback (PNF) may help address addictive disorders. PNF highlights discrepancies between perceived and actual peer norms, juxtaposed against self-reported behavior. PNF can be ...self-directed and cost-efficient. Our study estimates the efficacy of PNF alone, and in combination with other self-directed interventions, to address frequency and symptom severity of hazardous alcohol use, problem gambling, illicit drug and tobacco use. We searched electronic databases, grey literature, and reference lists of included articles, for randomized controlled trials published in English (January 2000-August 2019). We assessed study quality using the Cochrane Risk of Bias tool. Thirty-four studies met inclusion criteria (k = 28 alcohol, k = 3 gambling, k = 3 cannabis, k = 0 tobacco). Thirty studies provided suitable data for meta-analyses. PNF alone, and with additional interventions, reduced short-term alcohol frequency and symptom severity. PNF with additional interventions reduced short-term gambling symptom severity. Effect sizes were small. PNF did not alter illicit drug use. Findings highlight the efficacy of PNF to address alcohol frequency and symptom severity. The limited number of studies suggest further research is needed to ascertain the efficacy of PNF for gambling and illicit drug use. Cost-effectiveness analyses are required to determine the scale of PNF needed to justify its use in various settings.
Prediction of installed jet noise Lyu, B.; Dowling, A. P.; Naqavi, I.
Journal of fluid mechanics,
01/2017, Volume:
811
Journal Article
Peer reviewed
Open access
A semianalytical model for installed jet noise is proposed in this paper. We argue and conclude that there exist two distinct sound source mechanisms for installed jet noise, and the model is ...therefore composed of two parts to account for these different sound source mechanisms. Lighthill’s acoustic analogy and a fourth-order space–time correlation model for the Lighthill stress tensor are used to model the sound induced by the equivalent turbulent quadrupole sources, while the trailing-edge scattering of near-field evanescent instability waves is modelled using Amiet’s approach. A non-zero ambient mean flow is taken into account. It is found that, when the rigid surface is not so close to the jet as to affect the turbulent flow field, the trailing-edge scattering of near-field evanescent waves dominates the low-frequency amplification of installed jet noise in the far-field. The high-frequency noise enhancement on the reflected side is due to the surface reflection effect. The model agrees well with experimental results at different observer angles, apart from deviations caused by the mean-flow refraction effect at high frequencies at low observer angles.
Prostate radiation therapy dose planning directly on magnetic resonance imaging (MRI) scans would reduce costs and uncertainties due to multimodality image registration. Adaptive planning using a ...combined MRI-linear accelerator approach will also require dose calculations to be performed using MRI data. The aim of this work was to develop an atlas-based method to map realistic electron densities to MRI scans for dose calculations and digitally reconstructed radiograph (DRR) generation.
Whole-pelvis MRI and CT scan data were collected from 39 prostate patients. Scans from 2 patients showed significantly different anatomy from that of the remaining patient population, and these patients were excluded. A whole-pelvis MRI atlas was generated based on the manually delineated MRI scans. In addition, a conjugate electron-density atlas was generated from the coregistered computed tomography (CT)-MRI scans. Pseudo-CT scans for each patient were automatically generated by global and nonrigid registration of the MRI atlas to the patient MRI scan, followed by application of the same transformations to the electron-density atlas. Comparisons were made between organ segmentations by using the Dice similarity coefficient (DSC) and point dose calculations for 26 patients on planning CT and pseudo-CT scans.
The agreement between pseudo-CT and planning CT was quantified by differences in the point dose at isocenter and distance to agreement in corresponding voxels. Dose differences were found to be less than 2%. Chi-squared values indicated that the planning CT and pseudo-CT dose distributions were equivalent. No significant differences (p > 0.9) were found between CT and pseudo-CT Hounsfield units for organs of interest. Mean ± standard deviation DSC scores for the atlas-based segmentation of the pelvic bones were 0.79 ± 0.12, 0.70 ± 0.14 for the prostate, 0.64 ± 0.16 for the bladder, and 0.63 ± 0.16 for the rectum.
The electron-density atlas method provides the ability to automatically define organs and map realistic electron densities to MRI scans for radiotherapy dose planning and DRR generation. This method provides the necessary tools for MRI-alone treatment planning and adaptive MRI-based prostate radiation therapy.
To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weighted (T2w) magnetic resonance (MR) pelvic scans for MR-Sim prostate treatment planning.
A Siemens ...Skyra 3T MR imaging (MRI) scanner with laser bridge, flat couch, and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole-pelvis MRI scan (1.6 mm 3-dimensional isotropic T2w SPACE Sampling Perfection with Application optimized Contrasts using different flip angle Evolution sequence) was acquired. Three additional small field of view scans were acquired: T2w, T2*w, and T1w flip angle 80° for gold fiducials. Patients received a routine planning CT scan. Manual contouring of the prostate, rectum, bladder, and bones was performed independently on the CT and MR scans. Three experienced observers contoured each organ on MRI, allowing interobserver quantification. To generate a training database, each patient CT scan was coregistered to their whole-pelvis T2w using symmetric rigid registration and structure-guided deformable registration. A new multi-atlas local weighted voting method was used to generate automatic contours and sCT results.
The mean error in Hounsfield units between the sCT and corresponding patient CT (within the body contour) was 0.6 ± 14.7 (mean ± 1 SD), with a mean absolute error of 40.5 ± 8.2 Hounsfield units. Automatic contouring results were very close to the expert interobserver level (Dice similarity coefficient): prostate 0.80 ± 0.08, bladder 0.86 ± 0.12, rectum 0.84 ± 0.06, bones 0.91 ± 0.03, and body 1.00 ± 0.003. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same dose prescription was found to be 0.3% ± 0.8%. The 3-dimensional γ pass rate was 1.00 ± 0.00 (2 mm/2%).
The MR-Sim setup and automatic sCT generation methods using standard MR sequences generates realistic contours and electron densities for prostate cancer radiation therapy dose planning and digitally reconstructed radiograph generation.
Abstract Objectives To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases. Methods ...Twenty-four sound upper premolar teeth with Class II cavities were allocated to three groups ( n = 8). Restoration of the teeth involved the placement of an RBC (GrandioSO) in eight oblique increments (Group A) or Groups B and C were restored to within 2 mm of the palatal cusp in a single increment with bulk-fill flowable RBC bases (SDR and x-tra base) before the two occlusal cavity increments were placed with GrandioSO. Buccal and palatal cusp deflections were recorded postirradiation using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in 0.2% basic fuchsin dye for 24 h, sectioned and examined for cervical microleakage. Results The mean total cuspal deflection for the oblique incremental restoration technique was 11.26 (2.56) μm (Group A) and 4.63 (1.19) μm (Group B) and 4.73 (0.99) μm (Group C) for the bulk-fill flowable RBC bases. A significant increase in the mean total cuspal deflection for the incrementally filled GrandioSO compared with the SDR ( P = 0.007) and x-tra base ( P = 0.005) restored teeth was evident. No significant difference in the cervical microleakage scores was recorded between groups AC ( P > 0.05). Conclusions The bulk-fill flowable RBC bases significantly reduced cuspal deflection compared with a conventional RBC restored in an oblique incremental filling technique with no associated change in cervical microleakage recorded.
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