bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Lateral Ligament Augmentation Using Suture-Tape on Functional Ankle Instability
Authors: Cho Byung-Ki , Hong Seok-Hyun , Jeon Jae-Hyeon
Published: January 2019

Background:

Although lateral ligament augmentation using suture-tape has been effective for restoration of mechanical ankle stability, few data are available regarding changes of peroneal strength, proprioception, and postural control. The aim of this study was to determine effects of suture-tape augmentation on functional ankle instability (FAI).

Methods:

Twenty-four patients who underwent suture-tape augmentation were eligible and were followed more than 2 years postoperatively. Functional outcomes were evaluated with the Cumberland Ankle Instability Tool (CAIT), Foot and Ankle Ability Measure (FAAM). Changes of peroneal strength, proprioception and postural control were analyzed with an isokinetic dynamometer and a modified Romberg test.

Results:

CAIT and FAAM (average of daily and sports activity scores) significantly improved to average 27.2 points and 86.7 points, respectively, at final follow-up. Peak torque for eversion in 60 degrees/s angular velocity significantly improved to 10.6 Nm at final follow-up. Deficit ratio of peak torque for eversion significantly improved from mean 39.5% to 20.9%, and significant side-to-side difference was revealed ( P < .001). There were no significant differences in joint position sense. A significant improvement in balance retention time was revealed at final follow-up, and the relative deficit ratio compared to the unaffected side was 30.9%.

Conclusions:

Patient-reported functional outcomes significantly improved after lateral ligament augmentation using suture-tape. Although this procedure demonstrated significant effects on FAI based on improvement of isokinetic peroneal strength and postural control, recovery rates compared to the unaffected side were not significant at the intermediate-term follow-up. In addition, there was no positive effect on proprioception of the ankle.

Level of Evidence:

Level IV, prospective case series.
Predictive Validity of the Static-99 and Static-99R in Switzerland
Authors: Gonçalves Leonel C. , Gerth Juliane , Rossegger Astrid , Noll Thomas , Endrass Jérôme
Published: January 2019

This study evaluated the validity of the Static-99 and Static-99R in assessing sexual recidivism in Switzerland, based on a sample of 142 male sex offenders. Both tools showed predictive validity, but the Static-99R had better discrimination (OR = 1.82, AUC = .81) and calibration (Brier = .078, P/E = 0.96) than the Static-99. A cut score of four on the Static-99R maximized sensitivity (92.9%) and specificity (60.2%). However, although most offenders (98.7%) with a score < 4 did not commit sexual offenses in the 5-year follow-up period, only one in five (20.3%) offenders with a score ≥ 4 actually recidivated. Furthermore, the predicted number of recidivists in the well above average risk category (Static-99R ≥ 6) was 24% higher than expected in routine samples. The results suggest that the Static-99R may be a useful screening tool to identify low-risk individuals but offenders with scores ≥ 4 should be subjected to a more thorough assessment.
Intravitreal bevacizumab treatment for neovascular age-related macular degeneration and thromboembolic events
Authors: Weinstein Orly , Abu Tailakh Muhammad , Lifshitz Tova , Novack Victor , Levy Jaime
Published: January 2019

Background:

Systemic complications of intravitreal anti-vascular endothelial growth factor agents are relatively uncommon but highly significant.

Objectives:

Primary objective: To assess the risk for thromboembolic events following intravitreal bevacizumab injection in neovascular age-related macular degeneration patients by a large population-based study. Secondary objective: To analyze the association between injection frequency and the risk for thromboembolic events, the time interval between the injection and the thromboembolic events, and the influence of chronic diseases on complications rate.

Design:

A retrospective cohort study.

Methods:

Consecutive neovascular age-related macular degeneration patients receiving intravitreal bevacizumab at Soroka University Medical Center from December 2005 to December 2013 were included. Thromboembolic events analyzed included acute coronary syndrome, acute myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. The thromboembolic event rate was compared 2 years prior and 2 years after the initial intravitreal bevacizumab injection.

Results:

A total of 2102 patients were included. Acute coronary syndrome and stroke rate were higher 2 years after intravitreal bevacizumab (p = 0.03 and p = 0.01, respectively). No statistical significant difference was found for the rest of thromboembolic events. Patients older than 80 years and patients receiving less than six intravitreal bevacizumab injections were more likely to experience stroke. Patients with known cardiovascular risk factors before starting injections did not develop significant more thromboembolic events.

Conclusion:

In our study population, patients treated with intravitreal bevacizumab were significantly more likely to experience stroke during 2 years after first injection.
Use of a temporary shunt to preserve the patency of a hemodialysis graft while performing ipsilateral axillo-femoral bypass
Authors: Argyriou Christos , Schoretsanitis Nikolaos , Kantartzi Konstantia , Panagoutsos Stylianos , Souftas Vasileios D , Lazarides Miltos K , Georgiadis George S
Published: January 2019

Increased blood flow in the subclavian artery feeding a vascular access for hemodialysis can rarely induce steal phenomena in the vertebral and internal mammary artery leading to potentially life-threatening conditions. On the contrary, transient interruption of blood flow in the subclavian artery feeding a dialysis arteriovenous fistula can theoretically induce access thrombosis. Here, we describe a technical maneuver preserving continuous ipsilateral upper arm access flow when constructing a unilateral axillo-femoral polytetrafluoroethylene bypass operation for critical limb ischemia in a hemodialysis patient.
Community, Aesthetics, and Authenticity: The Retail Curatorship of a Rapidly Gentrifying Australian Streetscape
Authors: Molnar Lena , Walters Peter
Published: January 2019

While change to the retail landscape is a vital component of the gentrification narrative, most literature engages with the gentrification of retail from an objective position. In this article, we explore the process of rapid gentrification of Boundary Street, West End in Brisbane, Australia through the eyes of retailers themselves using photo elicitation. Retailers to varying degrees see themselves as custodians of the street and a disappearing public realm. We explore their narratives of change and authenticity in a rapidly changing spatial environment, driven by top-down capital-led gentrification. We use the perspective of retailers as newcomers, “voyeurs”; or more longstanding players, “curators,” to argue that the transformation of retail in a gentrifying neighborhood can be used to signify moments in the shift of the “authentic” from community to aestheticization and then to outright commodification.
Lower total cerebral arterial flow contributes to cognitive performance in multiple sclerosis patients
Authors: Jakimovski Dejan , Benedict Ralph HB , Marr Karen , Gandhi Sirin , Bergsland Niels , Weinstock-Guttman Bianca , Zivadinov Robert
Published: January 2019

Background:

The cognitive performance in multiple sclerosis (MS) patients declines with aging, longer disease duration, and possibly cardiovascular comorbidities.

Objectives:

We investigated whether lower total cerebral arterial blood flow (CABF) measured at the level of the carotid and vertebral arteries may contribute to worse cognitive performance in 132 MS patients and 47 healthy controls.

Methods:

Total CABF was evaluated with extracranial Doppler, whereas structural T2-lesion volume (LV) and gray matter volume (GMV) were measured on 3T MRI. The cognitive performance was assessed by Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test—Revised (BVMT-R), and California Verbal Learning Test—Second Edition (CVLT-II). Analysis of covariance, partial correlation, and regression models were used to test the differences between study groups and cognition/CABF correlations. False discovery rate (FDR)-corrected (Benjamini–Hochberg) p-values (i.e. q-values) less than 0.05 were considered significant.

Results:

Association between lower total CABF and the lower cognitive performance was observed only in MS patients ( r = 0.318, q < 0.001 and r = 0.244, q = 0.012 for SDMT and BVMT-R, respectively). Lower GMV, higher T2-LV, and CABF were significantly associated with poorer performance on the processing speed measure of SDMT (adjusted R2 = 0.295, t-statistics = 2.538, standardized β = 0.203, and q = 0.020), but not with memory tests. Cognitively impaired MS patients had lower total CABF compared to cognitively preserved (884.5 vs 1020.2 mL/min, q = 0.008).

Conclusion:

Cognitively impaired MS patients presented with lower total CABF. Altered CABF may be a result of reduced metabolic rate and might contribute to abnormal cognitive aging in MS.
Structural connectivity in multiple sclerosis and modeling of disconnection
Authors: Pagani Elisabetta , Rocca Maria A , De Meo Ermelinda , Horsfield Mark A , Colombo Bruno , Rodegher Mariaemma , Comi Giancarlo , Filippi Massimo
Published: January 2019

Background:

Multiple sclerosis (MS) is characterized by focal white matter damage, and when the brain is modeled as a network, lesions can be treated as disconnection events.

Objective:

To evaluate whether modeling disconnection caused by lesions helps explain motor and cognitive impairment in MS.

Methods:

Pathways connecting 116 cortical regions were reconstructed with magnetic resonance imaging (MRI) tractography from diffusion tensors averaged across healthy controls (HCs); maps of pathways were applied to 227 relapse-onset MS patients and 50 HCs to derive structural connectivity. Then, the likelihood of individual connections passing through lesions was used to model disconnection. Patients were grouped according to clinical phenotype (113 relapsing-remitting multiple sclerosis (RRMS), 69 secondary progressive multiple sclerosis (SPMS), 45 benign MS), and then network metrics were compared between groups (analysis of variance (ANOVA)) and correlated with motor and cognitive scores (linear regression).

Results:

Global metrics differentiated RRMS from SPMS and benign MS patients, but not benign from SPMS patients. Nodal connectivity strength replicated global results. After disconnection, few nodes were significantly different between benign MS and RRMS patients. Correlations revealed nodes pertinent to motor and cognitive dysfunctions; these became slightly stronger after disconnection.

Conclusion:

Connectivity did not change greatly after modeled disconnection, suggesting that the brain network is robust against damage caused by MS lesions.
Heightened intensity: Reflecting on player experiences in Wayfinder Live
Authors: Innocent Troy , Leorke Dale
Published: January 2019

Location-based games use smartphones and other location-aware devices to incorporate their players’ actions in everyday, physical spaces – the streets and public spaces of the city – into the virtual world of the game. Scholars and designers of these games often claim that they reconfigure their players’ relationship with the people and environment around them. They argue these games either engage and immerse players more deeply in the spaces of the game or distance and detach them from the physical environment through the screen interface. To date, however, relatively few detailed empirical studies of these games have been undertaken to test out and critique these claims. This article presents a study of the 2017 iteration of the location-based augmented reality game Wayfinder Live, in which players use their phones to search for and scan urban codes hidden across Melbourne’s laneways, alleys, and public spaces. Players of the game were interviewed and invited to reflect on their experience. This article relates these experiences to the design and development of the game, particularly to five play design principles that characterize its approach to haptic play in urban space. We begin by outlining these principles and the motivations behind them. Then, drawing on an analysis of the player interviews, we evaluate the impact of the game on their perception of the city.
Preferential pay protection: Does UK law provide poorer protection to those discriminated against on grounds of protected characteristics other than gender?
Authors: Downie Margaret
Published: January 2019

UK law treats equal pay claims based on gender (brought under the equal pay provisions of Part 5 Chapter 3 of the Equality Act 2010) differently from equal pay claims based on other protected characteristics of age, disability, gender reassignment, marriage and civil partnership, pregnancy and maternity, race, religion or belief, and sexual orientation (brought under the general discrimination provisions in Chapter 2 of that Act). This article considers the impact of the differences on each group of claimants. It concludes that the separate system of equal pay for the protected characteristic of sex ignores other inequalities of pay and that the inconsistent way the United Kingdom treats these issues leads to inequality among disadvantaged groups. It recommends that the United Kingdom should take a more consistent approach to pay gaps.
Disclosure of caregiver-fabricated illness to a child: A team-based approach to communicating with pediatric patients
Authors: Cardona Laurie , Asnes Andrea G
Published: January 2019

Clinical practice guidelines for informing children they have been subjected to caregiver-fabricated illness are highly limited in the current literature. This article addresses this issue by offering an ethically informed, psychological approach to the disclosure of this form of abuse to school-aged children and adolescents who have been significantly harmed. A multidisciplinary, staged model of communication which illustrates that truthful communication with children and their families is a necessary component of the recovery process is proposed.
Dispositional mindfulness mediates the relations between neuroticism and posttraumatic stress disorder and depression in Chinese adolescents after a tornado
Authors: An Yuanyuan , Fu Gan , Yuan Guangzhe , Zhang Qian , Xu Wei
Published: January 2019

Previous studies have shown that neuroticism is associated with higher levels of posttraumatic stress disorder (PTSD) and depression in individuals who have experienced traumatic events. This study investigated dispositional mindfulness as one pathway in which neuroticism is related to PTSD and depression symptoms among Chinese adolescents who have experienced trauma by considering the role of dispositional mindfulness. Participants were 443 Chinese adolescents who had experienced a severe tornado a year prior to this study. The results showed that our model fitted the data well ( χ2 /df = 2.113, comparative fit index (CFI) = 0.981, Tucker–Lewis index (TLI) = 0.969, root mean square error of approximation (RMSEA) (90% confidence interval (CI)) = 0.061 [0.047, 0.080]) and revealed that dispositional mindfulness partially mediated the relationship between neuroticism and PTSD and depression symptoms. The clinical implications and limitations of our research and recommendations for future research are discussed in this article.
Including and involving young people (under 18’s) in hate research without the consent of parents
Authors: Pickles James
Published: January 2019

This article provides a reflection on the ethical challenges faced when seeking ethical approval to include young people in a research project examining LGBT+ ‘hate’ experiences. I outline the ethical parameters constructed when attempting to recruit under 18’s into the project and justify the rationale for doing so. I detail how ethical approval was gained and reflect on the safeguards put in place to protect young participants. The methodological position adopted took a youth affirmative outlook, premised on enabling and championing the autonomy and agency of young people. Traditional ethical guidelines maintain that parental consent is required to include young people within sensitive research. Seeking parental consent placed young participants in a position of greater risk than what would occur during participation. Parental consent was not sought for young people to participate, nor were they informed about the involvement of their children in the project. This article provides justifications on rejecting the notion that parental consent is the only means for youth inclusion, and details how young people were empowered during participation. I argue that young people should not be instinctively excluded from sensitive research but should be actively enabled by minimising but not eradicating possible and potential risk.
Bayesian semiparametric latent variable model with DP prior for joint analysis: Implementation with nimble
Authors: Ma Zhihua , Chen Guanghui
Published: January 2019

Multiple responses of mixed types are naturally encountered in a variety of data analysis problems, which should be jointly analysed to achieve higher efficiency gains. As an efficient approach for joint modelling, the latent variable model induces dependence among the mixed outcomes through a shared latent variable. Generally, the latent variable is assumed to be normal, which is not that flexible and realistic in practice. This tutorial article demonstrates how to jointly analyse mixed continuous and ordinal responses using a semiparametric latent variable model by allowing the latent variable to follow a Dirichlet process (DP) prior, and illustrates how to implement Bayesian inference through a powerful R package nimble. Two model comparison criteria, deviance information criterion (DIC) and logarithm of the pseudo-marginal likelihood (LPML), are employed for model selection. Simulated data and data from a social survey study are used for illustrating the proposed method with nimble. An extension of DP prior to DP mixtures prior is introduced as well.
Falls prevention for people with dementia: a knowledge translation intervention
Authors: Meyer Claudia , Hill Keith D , Hill Sophie , Dow Briony
Published: January 2019

Purpose

Strong evidence exists for falls prevention, yet uptake of strategies can be fragmented and limited. For people with dementia, adoption of strategies may be impacted by changes in memory and planning. This paper describes the findings of a knowledge translation intervention for adoption of falls prevention strategies for people with dementia.

Methods

Twenty-five dyads (people with dementia and their caregivers) participated in this mixed method intervention. The Knowledge to Action framework guided: collation of existing evidence into a useable format; identification of individual issues; understanding context; and evaluation of change over time. Demographic details, functional status, dementia severity, activity level, self-efficacy, falls risk and readiness to change behaviour were collected at baseline, 6 and 12 months. Goal setting and action planning using a discussion tool drove implementation.

Results

Falls rates were 5.4 falls per 1000 days for the 12-month period, with no significant change in functional capacity or self-efficacy. There was a non-significant trend towards reduced falls risk. Readiness to change behaviour for falls risk increased from 84% to 96% by 6 months, with most moving from contemplation into action ( n = 16), or preparation into action ( n = 36), with adoption of strategies high (82%).

Conclusion

Engagement with the person with dementia and their caregiver, through identification of their needs and preferences, and enabling choice resulted in high adoption of falls prevention strategies.
Comparative international testing of early childhood education: The democratic deficit and the case of Portugal
Authors: Sousa Diana , Grey Sue , Oxley Laura
Published: January 2019

The Organisation for Economic Co-operation and Development (OECD) has a key role in driving educational discourse and global educational governance. Its comparative ‘Programme of International School Assessment’ (PISA) has explicitly linked the knowledge and skills of young people with the economic potential of countries. Through the International Early Learning and Child Well-Being Study (IELS), the OECD plans to extend its reach to early childhood education (ECE) by developing metrics to measure ‘quality’ in ECE. This focus gives weight to discourses centred around ideas of ‘what works’. The rhetoric derives from the principles that standards of learning and well-being can be improved by emulating notions of ‘best practice’ identified through comparative data.

 This article uses the case of Portugal to illustrate the significant disconnect between the aims and pedagogies of ECE and the increasingly influential de-contextualised discourses concerning ranking, performance and outcomes, as espoused by the OECD IELS project. Using evidence from three diverse Portuguese ECE settings, we illustrate how conceptual understandings of democracy in each school closely reflected the individual school philosophies. We discuss how the dampening of localised realities, for example, through standardisation and de-contextualisation, could lead to a democratic deficit enabled by discourses which displace the purpose, complexity and subjectivity of ECE policy and practice.
Factors relating to teachers’ intention to change school: A multilevel perspective
Authors: Qin Lixia
Published: January 2019

The high turnover rates in public schools, especially in those hard-to-staff schools, remains a growing problem and has become the largest component of teacher supply problems in the US school system. The purpose of the study was to examine the individual and school organizational factors that were associated with teachers’ intentions to change school by using the dataset of the US TALIS 2013 administrated by the Organisation for Economic Co-operation and Development. The results of the multilevel models showed that although the variance in teacher turnover intentions was, to a substantial degree, explained by the individual variables, the school organizational-specific effects have notably contributed to the outcome as well. Additionally, the analysis of the cross-level interaction has detected both direct and indirect effects of disadvantaged schools on teacher transfer intention. The implications for teacher retention policies have been discussed as well.
Variation of Poisson’s ratio of fabrics woven with helical composite auxetic weft yarns in relation to fabric structural parameters
Authors: Lolaki Asal , Shanbeh Mohsen
Published: January 2019

Auxetic textiles are defined as textiles with negative Poisson’s ratio. These textiles possess unique properties that render them suitable for special applications. This work aims to investigate the effect of fabric structural parameters such as thread densities, weave design and warp yarn count. Thus, 30 fabric samples were woven at 3 weft and 2 warp densities, respectively. Two warp counts and three weave designs of plain, basket 3/3 and weft-backed satin 6 were used. The samples were uniaxially loaded in weft direction and dimensional changes at various strains levels were evaluated. The evaluation was carried out using the image processing technique based on MATLAB software. The weft yarns used were found to exhibit auxetic behavior at the whole spectrum of the strain level used. The least weft yarn Poisson’s ratio was found to be −0.9. It was established that in general the fabric samples exhibit auxetic effect within the stated range of strain. Additionally, it was concluded that while fabric thread densities together with warp count influence the minimum fabric Poisson's ratio, auxetic behavior of the samples is not dependent on weave design alone. Rather, it was illustrated that the combined effect of weave design in association with stated structural parameters on auxetic feature cannot be ignored.
Evaluation and Clinical Application of a Commercially Available Iterative Reconstruction Algorithm for CBCT-Based IGRT
Authors: Mao Weihua , Liu Chang , Gardner Stephen J. , Siddiqui Farzan , Snyder Karen C. , Kumarasiri Akila , Zhao Bo , Kim Joshua , Wen Ning Winston , Movsas Benjamin , Chetty Indrin J.
Published: January 2019

Purpose:

We have quantitatively evaluated the image quality of a new commercially available iterative cone-beam computed tomography reconstruction algorithm over standard cone-beam computed tomography image reconstruction results.

Methods:

This iterative cone-beam computed tomography reconstruction pipeline uses a finite element solver (AcurosCTS)-based scatter correction and a statistical (iterative) reconstruction in addition to a standard kernel-based correction followed by filtered back-projection-based Feldkamp-Davis-Kress cone-beam computed tomography reconstruction. Standard full-fan half-rotation Head, half-fan full-rotation Head, and standard Pelvis cone-beam computed tomography protocols have been investigated to scan a quality assurance phantom via the following image quality metrics: uniformity, HU constancy, spatial resolution, low contrast detection, noise level, and contrast-to-noise ratio. An anthropomorphic head phantom was scanned for verification of noise reduction. Clinical patient image data sets for 5 head/neck patients and 5 prostate patients were qualitatively evaluated.

Results:

Quality assurance phantom study results showed that relative to filtered back-projection-based cone-beam computed tomography, noise was reduced from 28.8 ± 0.3 HU to a range between 18.3 ± 0.2 and 5.9 ± 0.2 HU for Full-Fan Head scans, from 14.4 ± 0.2 HU to a range between 12.8 ± 0.3 and 5.2 ± 0.3 HU for Half-Fan Head scans, and from 6.2 ± 0.1 HU to a range between 3.8 ± 0.1 and 2.0 ± 0.2 HU for Pelvis scans, with the iterative cone-beam computed tomography algorithm. Spatial resolution was marginally improved while results for uniformity and HU constancy were similar. For the head phantom study, noise was reduced from 43.6 HU to a range between 24.8 and 13.0 HU for a Full-Fan Head and from 35.1 HU to a range between 22.9 and 14.0 HU for a Half-Fan Head scan. The patient data study showed that artifacts due to photon starvation and streak artifacts were all reduced, and image noise in specified target regions were reduced to 62% ± 15% for 10 patients.

Conclusion:

Noise and contrast-to-noise ratio image quality characteristics were significantly improved using the iterative cone-beam computed tomography reconstruction algorithm relative to the filtered back-projection-based cone-beam computed tomography method. These improvements will enhance the accuracy of cone-beam computed tomography-based image-guided applications.
Variance Estimation for the Instrumental Variables Approach to Measurement Error in Generalized Linear Models
Authors: Hardin James W. , Carroll Raymond J.
Published: January 2019

This paper derives and gives explicit formulas for a derived sandwich variance estimate. This variance estimate is appropriate for generalized linear additive measurement error models fitted using instrumental variables. We also generalize the known results for linear regression. As such, this article explains the theoretical justification for the sandwich estimate of variance utilized in the software for measurement error developed under the Small Business Innovation Research Grant (SBIR) by StataCorp. The results admit estimation of variance matrices for measurement error models where there is an instrument for the unknown covariate.
Maximum Likelihood Estimation of Generalized Linear Models with Covariate Measurement Error
Authors: Rabe-Hesketh Sophia , Skrondal Anders , Pickles Andrew
Published: January 2019

Generalized linear models with covariate measurement error can be estimated by maximum likelihood using gllamm, a program that fits a large class of multilevel latent variable models (Rabe-Hesketh, Skrondal, and Pickles 2004). The program uses adaptive quadrature to evaluate the log likelihood, producing more reliable results than many other methods (Rabe-Hesketh, Skrondal, and Pickles 2002). For a single covariate measured with error (assuming a classical measurement model), we describe a “wrapper” command, cme, that calls gllamm to estimate the model. The wrapper makes life easy for the user by accepting a simple syntax and data structure and producing extended and easily interpretable output. The commands for preparing the data and running gllamm can also be obtained from cme. We first discuss the case where several measurements are available and subsequently consider estimation when the measurement error variance is instead assumed known. The latter approach is useful for sensitivity analysis assessing the impact of assuming perfectly measured covariates in generalized linear models. An advantage of using gllamm directly is that the classical covariate measurement error model can be extended in various ways. For instance, we can use nonparametric maximum likelihood estimation (NPMLE) to relax the normality assumption for the true covariate. We can also specify a congeneric measurement model which relaxes the assumption that the measurements for a unit are exchangeable replicates by allowing for different measurement scales and error variances.
Multiple Imputation of Missing Values: Further Update of Ice, with an Emphasis on Interval Censoring
Authors: Royston Patrick
Published: January 2019

Multiple imputation of missing data continues to be a topic of considerable interest and importance to applied researchers. In this article, the ice package for multiple imputation is further updated. Special attention in this article is paid to imputing interval-censored observations, and a suggestion to use imputation of right-censored survival data to elucidate covariate effects graphically.
A Generic Function Evaluator Implemented in Mata
Authors: Støvring Henrik
Published: January 2019

Background

When implementing new statistical procedures, there is often a need for simple—and yet computationally efficient—ways of numerically evaluating composite distribution functions. If the statistical procedure must support calculations for censored and noncensored cases, those calculations should be carried out using efficient computational implementations of both definite and indefinite integrals (e.g., calculation of tail areas of distribution functions).

Method

We developed a generic function evaluator such that users may specify a function using reverse Polish notation. As its argument the function evaluator takes a matrix of pointers and then applies the rows of this matrix to its internally defined stack of pointers. Accordingly, each row of the argument matrix defines a single operation such as evaluating a function on the current element of the stack, applying an algebraic operation to the two top elements of the stack, or manipulating the stack itself. Defining new composite distribution functions from other (atomic) distribution functions then corresponds to joining two or more function-defining matrices vertically. This approach can further be used to obtain integrals of any defined function. As an example we show how the density and distribution function for the minimum of two Weibull distributed random variables can be numerically evaluated and integrated.

Results

The procedure provides a flexible and extensible framework for implementing numerical evaluation of general, composite distributions. The procedure is numerically relatively efficient, although not optimal.
Mata Matters: Structures
Authors: Gould William
Published: January 2019

Mata is Stata's matrix language. In the Mata Matters column, we show how Mata can be used interactively to solve problems and as a programming language to add new features to Stata. Structures are the subject of this column. Structures are an advanced programming technique that can greatly simplify complicated code.
Variable Selection in Linear Regression
Authors: Lindsey Charles , Sheather Simon
Published: January 2019

We present a new Stata program, vselect, that helps users perform variable selection after performing a linear regression. Options for stepwise methods such as forward selection and backward elimination are provided. The user may specify Mallows's Cp, Akaike's information criterion, Akaike's corrected information criterion, Bayesian information criterion, or R2 adjusted as the information criterion for the selection. When the user specifies the best subset option, the leaps-and-bounds algorithm (Furnival and Wilson, Technometrics 16: 499–511) is used to determine the best subsets of each predictor size. All the previously mentioned information criteria are reported for each of these subsets. We also provide options for doing variable selection only on certain predictors (as in [R] nestreg) and support for weighted linear regression. All options are demonstrated on real datasets with varying numbers of predictors.
Speaking Stata: Graphing Subsets
Authors: Cox Nicholas J.
Published: January 2019

Graphical comparison of results for two or more groups or subsets can be accomplished by way of subdivision, superimposition, or juxtaposition. The choice between superimposition (several groups in one panel) and juxtaposition (several groups in several panels) can require fine discrimination: while juxtaposition increases clarity, it requires mental superimposition to be most effective. Discussion of this dilemma leads to exploration of a compromise design in which each subset is plotted in a separate panel, with the rest of the data as a backdrop. Univariate and bivariate examples are given, and associated Stata coding tips and tricks are commented on in detail.
Treatment Interactions with Nonexperimental Data in Stata
Authors: Brown Graham K. , Mergoupis Thanos
Published: January 2019

Treatment effects may vary with the observed characteristics of the treated, often with important implications. In the context of experimental data, a growing literature deals with the problem of specifying treatment interaction terms that most effectively capture this variation. Some results of this literature are now implemented in Stata. With nonexperimental (observational) data, and in particular when selection into treatment depends on unmeasured factors, treatment effects can be estimated using Stata's treatreg command. Though not originally designed for this purpose, treatreg can be used to consistently estimate treatment interaction parameters. With interactions, however, adjustments are required to generate predicted values and estimate the average treatment effect. In this article, we introduce commands that perform this adjustment for multiplicative interactions, and we show the required adjustment for more complicated interactions.
Implementing Tests for Forecast Evaluation in the Presence of Instabilities
Authors: Rossi Barbara , Soupre Matthieu
Published: January 2019

In this article, we review methodologies to fix the size distortions of tests for forecast evaluation in the presence of instabilities. The methodologies implement tests for relative and absolute forecast evaluation that are robust to instabilities. We also introduce the giacross and rosssekh commands, which implement these procedures in Stata.
Demand-aware traffic cooperation for self-organizing cognitive small-cell networks
Authors: Yao Changhua , Zhu Lei , Jia Yongxing , Wang Lei
Published: January 2019

This article investigates the problem of efficient spectrum access for traffic demands of self-organizing cognitive small-cell networks, using the coalitional game approach. In particular, we propose a novel spectrum and time two-dimensional Traffic Cooperation Coalitional Game model which aims to improve the network throughput. The main motivation is to complete the data traffics of users, and the main idea is to make use of spectrum resource efficiently by reducing mutual interference in the spectrum dimension and considering cooperative data transmission in the time dimension at the same time. With the approach of coalition formation, compared with the traditional binary order in most existing coalition formation algorithms, the proposed functional order indicates a more flexibly preferring action which is a functional value determined by the environment information. To solve the distributed self-organizing traffic cooperation coalition formation problem, we propose three coalition formation algorithms: the first one is the Binary Preferring Traffic Cooperation Coalition Formation Algorithm based on the traditional Binary Preferring order; the second one is the Best Selection Traffic Cooperation Coalition Formation Algorithm based on the functional Best Selection order to improve the converging speed; and the third one is the Probabilistic Decision Traffic Cooperation Coalition Formation Algorithm based on the functional Probabilistic Decision order to improve the performance of the formed coalition. The proposed three algorithms are proved to converge to Nash-stable coalition structure. Simulation results verify the theoretic analysis and the proposed approaches.
Deformation and failure of thin plate structures under blast loading
Authors: Xu Zixi , Liu Yan , Huang Fenglei
Published: January 2019

The blast behavior and response of thin aluminum plates were investigated experimentally in this article and the results subjected to large-scale explosions in varied masses were presented. A device designed for measuring permanent deformation was used in the tests. Three types of failure were observed. The outcome was that all plates exhibited a counterintuitive behavior with distinct plastic deformation. Beyond that, some panels torn out from the boundaries. It is shown that the plates in field scale with lower blasting loading deformed similarly to those uniformly loaded in lab scale, but performed a deformation mode as localized loaded in small scale with the charge mass increased. Following that, results from experiments were used to verify the empirical formula derived before, where the yield stress of material was replaced by a novel parameter. Reasonable agreement between the predictions and the actual deflections of plates with lower impulsive loading was observed. In addition, a fitted prediction was given, which could be used to evaluate the permanent deflection in engineering calculation. The results obtained from experiments are helpful to give an insight into the differences on blast behavior between the field and lab scales.
Numerical investigation for the flexible stretch-stamp forming process of sheet metal
Authors: Wang You , Liu De-Zheng , Li Rui
Published: January 2019

Flexible stretch-stamp forming is a sheet metal forming method derived from flexible stretch forming and multi-point forming, aimed at solving wrinkling defects of large skin parts especially with complex curvatures, prone to occur in the later type of forming processes. To help understand the forming principle and forming characteristics of flexible stretch-stamp forming, a large sheet metal part with wavelike surface was selected as the study object and extensive numerical simulations have been conducted using a general commercial finite element software. The main processing parameters of pre-stretching force and wrapping force, respectively, exerted by horizontal and sloping cylinders on forming quality were investigated in detail. Finally, experiments were conducted to estimate the forming performances of flexible stretch-stamp forming.
Spontaneous isolated superior mesenteric artery dissection: Systematic review and meta-analysis
Authors: Karaolanis Georgios , Antonopoulos Constantine , Tsilimigras Diamantis I , Moris Dimitrios , Moulakakis Konstantinos
Published: January 2019

Objectives

Spontaneous isolated superior mesenteric artery dissection (SISMAD) is a rare disease with an incidence of 0.06%. The purpose of the meta-analysis was to identify the outcomes associated with the various treatment options in the management of asymptomatic and symptomatic patients with SISMAD.

Methods

Eligible studies were selected by searching PubMed, EMBASE, and Cochrane Library. Endpoints were outcome of asymptomatic patients treated conservatively, resolution of symptoms according to the treatment approach, rate of symptomatic patients switched from conservative to the endovascular and/or open repair, characteristics of the dissected lesion, and findings regarding the remodeling of superior mesenteric artery.

Results

We identified 30 studies including 729 patients. Among them, 608 (83.4%) were symptomatic and were managed with conservative (438/72%), and/or endovascular (139/22.8%) and/or open treatment (31/5%). The remaining were asymptomatic and they were treated solely conservatively. A high rate of resolution of symptoms (92.8%) was noted for patients treated conservatively. Conversion from conservative treatment to either endovascular or open procedure was required in 12.3% and 4.4%, respectively. Resolution of symptoms was observed in 100% for those treated with open procedure and 88.8% for those treated endovascularly. The pooled rate of bowel ischemia in patients treated conservatively was 3.75% (95% confidence interval = 1.15–7.27). Complete remodeling was achieved in 32% and partial in 26% of those who were treated conservatively.

Conclusions

The majority of symptomatic patients with SISAMD were treated conservatively and showed an uncomplicated course and only a small percentage required conversion to endovascular or open repair. This might highlight the benign course of the disease.
xCT knockdown in human breast cancer cells delays onset of cancer-induced bone pain
Authors: Ungard Robert G , Linher-Melville Katja , Nashed Mina G. , Sharma Manu , Wen Jianping , Singh Gurmit
Published: January 2019

Cancers in the bone produce a number of severe symptoms including pain that compromises patient functional status, quality of life, and survival. The source of this pain is multifaceted and includes factors secreted from tumor cells. Malignant cells release the neurotransmitter and cell-signaling molecule glutamate via the oxidative stress-related cystine/glutamate antiporter, system xC−, which reciprocally imports cystine for synthesis of glutathione and the cystine/cysteine redox cycle. Pharmacological inhibition of system xC− has shown success in reducing and delaying the onset of cancer pain-related behavior in mouse models. This investigation describes the development of a stable siRNA-induced knockdown of the functional trans-membrane system xC− subunit xCT ( SLC7A11) in the human breast cancer cell line MDA-MB-231. Clones were verified for xCT knockdown at the transcript, protein, and functional levels. RNAseq was performed on a representative clone to comprehensively examine the transcriptional cellular signature in response to xCT knockdown, identifying multiple differentially regulated factors relevant to cancer pain including nerve growth factor, interleukin-1, and colony-stimulating factor-1. Mice were inoculated intrafemorally and recordings of pain-related behaviors including weight bearing, mechanical withdrawal, and limb use were performed. Animals implanted with xCT knockdown cancer cells displayed a delay until the onset of nociceptive behaviors relative to control cells. These results add to the body of evidence suggesting that a reduction in glutamate release from cancers in bone by inhibition of the system xC− transporter may decrease the severe and intractable pain associated with bone metastases.
Anatomical, surgical and technical factors influencing continence after radical prostatectomy
Authors: Arroyo Carlos , Martini Alberto , Wang Joanna , Tewari Ashutosh K.
Published: January 2019

Radical prostatectomy (RP) is the most frequent treatment with curative intent performed for prostate cancer to date. Different surgical approaches (perineal, transperitoneal, and extraperitoneal) and techniques (laparoscopic and robot assisted) have been described to increase the efficiency and potentially diminish the postoperative complications of this procedure.

The aim of this narrative review is to investigate and define the factors that influence postprostatectomy urinary continence. We highlighted the anatomical landmarks and the modifications of surgical techniques aimed at improving the continence rates and thus, patient quality of life.

After RP, the long-term continence rates range from 84% to 97%. In order to achieve good continence rates, a careful dissection along with meticulous anatomical reconstruction is required. To this end, a detailed knowledge of the periprostatic anatomy is mandatory.
Comparative Accuracy Evaluation of a Blood Glucose Meter With Novel Hematocrit Correction Technology, With Three Currently Used Commercially Available Blood Glucose Monitoring Systems
Authors: Dunseath Gareth J. , Bright Dominic , Luzio Stephen D.
Published: January 2019

Hematocrit is known to influence glucose values obtained on some blood glucose meters, with bias observed especially at low and high hematocrit levels. We evaluated the performance of a meter with hematocrit correction technology alongside 3 other commercially available meters. Capillary blood samples from 100 subjects were analyzed in duplicate and compared to the plasma values obtained by reference laboratory analyzer. Bias, error grid, and sensitivity to hematocrit analyses were performed for each meter. Average percentage bias was similar for all meters, however the evaluated meter performed best with respect to error grid analysis, with 100% of values falling within the “no effect on clinical action” and “no risk” categories and did not display any hematocrit associated bias.
Heterospecific Tree Density and Environmental Factors Affect Afzelia africana Sm. Population Structure in the Pendjari Biosphere Reserve, West Africa: Implications for Management and Restoration
Authors: Atanasso Justin A. , Mensah Sylvanus , Azihou Akomian F. , Djossa Bruno A. , Glèlè Kakaï Romain , Assogbadjo Achille E.
Published: January 2019

Information on how abiotic and biotic factors affect species population structures and regeneration are critical for understanding plant growth in natural habitats. Here, we used the data from three spatially distinct populations of Afzelia africana Sm. in the Pendjari Biosphere Reserve in Benin, to determine how the species population structures respond to abiotic and biotic factors. Afzelia africana population structures were studied using several parameters including basal area, tree height, density of successive diameter classes, and size class slope. We tested for individual effects of abiotic (mound density, soil type, and terrain slope) and biotic (heterospecific tree density) factors on the species population structure. We also tested for similarity of species composition among studied A. africana population stands. Results revealed a tree density structure with mature individuals, and size class distribution indicating a recruitment bottleneck at the juvenile stage (10–20 cm diameter), possibly due to mammal browsing, natural and artificial fires. Heterospecific tree density was positively associated with A. africana adult density but negatively related to the species growth parameters (mean diameter, basal area, and tree height). These results indicate some degrees of niche overlap between A. africana and coexisting species but also partly reflect A. africana tolerance and adaptation to limited resources environment. Soil type significantly influenced both basal area and regeneration density, greater values being observed on silt-sand-rocky soils. Basal area was higher on steeper slope, probably a result of species conservative strategies. These findings were discussed in line with management and restoration action needs in the Pendjari Biosphere Reserve.