Model Checking for ROC Regression Analysis

The Receiver Operating Characteristic (ROC) curve is a prominent tool for characterizing the accuracy of continuous diagnostic test. To account for factors that might invluence the test accuracy, various ROC regression methods have been proposed. However, as in any regression analysis, when the assumed models do not fit the data well, these methods may render invalid and misleading results. To date practical model checking techniques suitable for validating existing ROC regression models are not yet available. In this paper, we develop cumulative residual based procedures to graphically and numerically assess the goodness-of-fit for some commonly used ROC regression models, and show how specific components of these models can be examined within this framework. We derive asymptotic null distributions for the residual process and discuss resampling procedures to approximate these distributions in practice. We illustrate our methods with a dataset from the Cystic Fibrosis registry.

Methacholine responsiveness in mice from 2 to 8 wk of age

Many chronic human lung diseases have their origin in early childhood, yet most murine models used to study them utilize adult mice. An important component of the asthma phenotype is exaggerated airway responses, frequently modelled by methacholine (MCh) challenge. The present study was undertaken to characterize MCh responses in mice from 2 to 8 wk of age measuring absolute lung volume and volume-corrected respiratory mechanics as outcome variables. Female BALB/c mice aged 2, 3, 4, 6, and 8 wk were studied during cumulative intravenous MCh challenge. Following each MCh dose, absolute lung volume was measured plethysmographically at functional residual volume and during a slow inflation to 20-hPa transrespiratory pressure. Respiratory system impedance was measured continuously during the inflation maneuver and partitioned into airway and constant-phase parenchymal components by model fitting. Volume-corrected (specific) estimates of respiratory mechanics were calculated. Intravenous MCh challenge induced a predominantly airway response with no evidence of airway closure in any age group. No changes in functional residual volume were seen in mice of any age during the MCh challenge. The specific airway resistance MCh dose response curves did not show significant differences between the age groups. The results from the present study do not show systematic differences in MCh responsiveness in mice from 2 to 8 wk of age.

„Pulverbettbasiertes Strahlschmelzen – neue Forschungserkenntnisse“

Auf dem Weg vom Rapid Prototyping zum Rapid Manufacturing ist erhöhte Prozesssicherheit sowie die Beherrschung verfahrensspezifischer Phänomene notwendig, um die immer weiter steigenden und konkreteren Bauteilanforderungen zu erfüllen. Dazu wurden diverse im SLM-Prozess auftretende Effekte untersucht. Basis der vorgestellten Entwicklungen sind grundlegende Erkenntnisse zur Oberflächenqualität von SLM-Bauteilen und Einflussgrößen auf Dichte und mechanische Eigenschaften der Bauteile verschiedener Werkstoffe. Ergebnis sind verschiedene Weiterentwicklungen der Standardbelichtungsstrategie, wodurch etwa Eigenspannungseffekte und Spritzerbildung positiv beeinflusst werden können.

Campylobacter monitoring in German broiler flocks: an explorative time series analysis

Campylobacter, a major zoonotic pathogen, displays seasonality in poultry and in humans. In order to identify temporal patterns in the prevalence of thermophilic Campylobacter spp. in a voluntary monitoring programme in broiler flocks in Germany and in the reported human incidence, time series methods were used. The data originated between May 2004 and June 2007. By the use of seasonal decomposition, autocorrelation and cross-correlation functions, it could be shown that an annual seasonality is present. However, the peak month differs between sample submission, prevalence in broilers and human incidence. Strikingly, the peak in human campylobacterioses preceded the peak in broiler prevalence in Lower Saxony rather than occurring after it. Significant cross-correlations between monthly temperature and prevalence in broilers as well as between human incidence, monthly temperature, rainfall and wind-force were identified. The results highlight the necessity to quantify the transmission of Campylobacter from broiler to humans and to include climatic factors in order to gain further insight into the epidemiology of this zoonotic disease.

Tools & Techniques - Statistics: Propensity score techniques.

Propensity score (PS) techniques are useful if the number of potential confounding pretreatment variables is large and the number of analysed outcome events is rather small so that conventional multivariable adjustment is hardly feasible. Only pretreatment characteristics should be chosen to derive PS, and only when they are probably associated with outcome. A careful visual inspection of PS will help to identify areas of no or minimal overlap, which suggests residual confounding, and trimming of the data according to the distribution of PS will help to minimise residual confounding. Standardised differences in pretreatment characteristics provide a useful check of the success of the PS technique employed. As with conventional multivariable adjustment, PS techniques cannot account for confounding variables that are not or are only imperfectly measured, and no PS technique is a substitute for an adequately designed randomised trial.

The anisotropic λ -deformed SU(2) model is integrable

The all-loop anisotropic Thirring model interpolates between the WZW model and the non-Abelian T-dual of the anisotropic principal chiral model. We focus on the SU(2) case and we prove that it is classically integrable by providing its Lax pair formulation. We derive its underlying symmetry current algebra and use it to show that the Poisson brackets of the spatial part of the Lax pair, assume the Maillet form. In this way we procure the corresponding r and s matrices which provide non-trivial solutions to the modified Yang–Baxter equation.

Can urethrolysis resolve outlet obstruction related symptoms after Burch colposuspension for stress urinary incontinence?

OBJECTIVE Bladder outlet obstruction may occur after any incontinence surgery and may present as OAB, hesitancy and or the feeling of incomplete emptying. Aim of this study was to analyze the clinical and urodynamical outcome after urethrolysis in patients presenting with various clinical symptoms after Burch colposuspension for stress urinary incontinence. STUDY DESIGN Between January 2005 and December 2014, all patients who presented with symptoms and with bladder outlet obstruction were included. All patients had undergone Burch or Cowan colposuspension for stress urinary incontinence previously. Primary endpoint was the visual analogue scale (VAS) as measurement of patient perceived disease impact. Secondary endpoints were the various domains of the King's Health Questionnaire, urodynamic parameters as detrusor pressure at maximum flow, residual urine and sonographic bladder wall thickness before and six months after intervention. RESULTS Seventy-two female patients were included in this study whereof 42 suffered from urgency and urge incontinence, 20 from hesitancy and/or slow stream, seven from residual urine of more than 100ml and three from a combination of urgency and residual urine. VAS improved significantly (p<0.0001). Quality of life as determined by the King's Health Questionnaire improved for the domains general health, role limitations, emotions, physical limitations, personal limitations and incontinence impact significantly. Micturition pressure dropped significantly from 43cmH2O (95% CI 19-59cmH2O) to 18cmH2O (95% CI 16-23.5 H2O). Residual urine changed from 110ml (range 20-380ml) to 32ml (20-115ml). Bladder wall thickness decreased from 7mm (95% CI 6.235-7.152) to 5mm (95% CI 5.037-5.607; p<0.01). CONCLUSION Urethrolysis may resolve patients' symptoms and lower micturition pressure but irritative symptoms may persist.

Surgical Treatment of Recurrent Endometrial Cancer: Time for a Paradigm Shift.

BACKGROUND Although surgery represents the cornerstone treatment of endometrial cancer at initial diagnosis, scarce data are available in recurrent setting. The purpose of this study was to review the outcome of surgery in these patients. METHODS Medical records of all patients undergoing surgery for recurrent endometrial cancer at NCI Milano between January 2003 and January 2014 were reviewed. Survival was determined from the time of surgery for recurrence to last follow-up. Survival was estimated using Kaplan-Meier methods. Differences in survival were analyzed using the log-rank test. The Fisher's exact test was used to compare optimal versus suboptimal cytoreduction against possible predictive factors. RESULTS Sixty-four patients were identified. Median age was 66 years. Recurrences were multiple in 38 % of the cases. Optimal cytoreduction was achieved in 65.6 %. Median OR time was 165 min, median postoperative hemoglobin drop was 2.4 g/dl, and median length hospital stay was 5.5 days. Eleven patients developed postoperative complications, but only four required surgical management. Estimated 5-year progression-free survival (PFS) was 42 and 19 % in optimally and suboptimally cytoreduced patients, respectively. At multivariate analysis, only residual disease was associated with PFS. Estimated 5-year overall survival (OS) was 60 and 30 % in optimally and suboptimally cytoreduced patients, respectively. At multivariate analysis, residual disease and histotype were associated with OS. At multivariate analysis, only performance status was associated with optimal cytoreduction. CONCLUSIONS Secondary cytoreduction in endometrial cancer is associated with long PFS and OS. The only factors associated with improved long-term outcome are the absence of residual disease at the end of surgical resection and histotype.

The Great Moderation Flattens Fat Tails: Disappearing Leptokurtosis

Recently, Fagiolo et al. (2008) find fat tails of economic growth rates after adjusting outliers, autocorrelation and heteroskedasticity. This paper employs US quarterly real output growth, showing that this finding of fat tails may reflect the Great Moderation. That is, leptokurtosis disappears after GARCH adjustment once we incorporate the break in the variance equation.

Malaria prevention in Kenyan women of childbearing age

The objective of this program is to reduce malaria incidence in Kenya. Malaria poses a large public health challenge in Kenya, and although public health efforts have traditionally been focused on treatment of infected patients, due to increased drug resistance and lack of drug-adherence, prevention strategies are needed. This program targets Kenyan women, the likely caretakers in the home, and promotes malaria prevention behaviors through health education. ^ A planning group will be assembled and a needs assessment will be performed, verifying risk factors and conditions associated with malaria, as well as personal and external determinants. Behavioral and environmental outcomes will be determined, and performance objectives for each outcome will be established. Matrices of change objectives will be created, and detailed methods and strategies will be linked to each change objective. Program elements include media, education, and incentives. All materials used in this program will be subjected to pre-test to ensure cultural relevance and fidelity. Matrices of change objectives will be created for program adopters and implementers, as well as correlating methods and strategies associated with each change objective. Performance objectives will also be compiled for program maintainers. A program evaluation plan will follow "Pre-Post Comparison Group" design. Outcome evaluation and process evaluation will be conducted. The sample population will be screened based on age and gender so as to maintain comparability to the target population. Measurements will be taken before the program to establish baseline, directly following the program to determine short-term effects, and three months after the program is completed to determine long-term effects. ^ One limitation of this program is selection bias, due to the nature of quasi-experimental studies. Thorough screening prior to sample selection will minimize selection bias and ensure group homogeneity. Another limitation is attrition, and this will be minimized where possible through the use of incentives. In cases where loss to follow-up is not avoidable, such as death or natural disasters, the attrition effect will be estimated using structural equation modeling after reviewing the sample size, differential attrition and total attrition. ^ This intervention is based heavily on health promotion theories, but it is important to remember that in the field, the program plan will likely include only the necessary practical strategies. The target population, Kenyan women of childbearing age, will be significant in decreasing the malaria disease burden in Kenya.^

The role of plasmacytoid dendritic cells in the regulation of adaptive immunity

Plasmacytoid dendritic cells (pDCs) selectively express TLR7 which allows them to respond to RNA viruses and TLR9 which allows them to respond to DNA viruses and CpG oligonucleotides. Upon exposure to virus pDCs produce vast amounts of type I interferon (IFN) directly inhibiting viral replication and contributing to the activation of other immune cells. The ability of pDCs to promote B and T cell differentiation through type I IFN has been well documented although the role of additional factors including tumor necrosis factor (TNF) family members has not been thoroughly addressed. Here the expression of selected TNF family members in pDCs was examined and the role of TNF receptor-ligand interactions in the regulation of B and T lymphocyte growth and differentiation by pDCs was investigated. Upon stimulation with CpG-B, pDCs exhibit strong and stable expression of CD70, a TNF family ligand that binds to its receptor CD27 on memory B cells and promotes plasma cell differentiation and Ig secretion. Using an in vitro pDC/B cell co-culture system, it was determined that CpG-B-stimulated pDCs induce the proliferation of CD40L-activated human peripheral B cells and Ig secretion. This occurs independently of IFN and residual CpG, and requires physical contact between pDCs and B cells. CpG-stimulated pDCs induce the proliferation of both naive and memory B cells although Ig secretion is restricted to the memory subset. Blocking the interaction of CD70 with CD27 using an antagonist anti-CD70 antibody reduces the induction of B cell proliferation and IgG secretion by CpG-B-stimulated pDCs. Published studies have also indicated an important role for CD70 in promoting the expansion of CD4+ and CD8+ T cells and the development of effector function. CpG-B-stimulated pDCs induce naïve CD4+ T cell proliferation and production of multiple cytokines including IFN-γ, TNF-α, IL-10, IL-4, IL-5 and IL-13. Blocking the function of CD70 with an antagonist anti-CD70 antibody significantly reduced the induction of naïve CD4+ T cell proliferation by CpG-B-stimulated pDCs and the production of IL-4 and IL-13. Collectively these data indicate an important role for CD70 in the regulation of B and T lymphocyte growth and differentiation by pDCs. ^

El empleo informal y la estructura del mercado laboral en las regiones argentinas

El proceso de informalización del sector formal que se ha observado en América Latina durante los últimos años implica la coexistencia de trabajadores formales e informales que desarrollan sus actividades bajo diferentes condiciones laborales en el mismo sector. Sin embargo, la literatura, tanto empírica como teórica, le asignó tradicionalmente una estructura homogénea. No obstante, la segmentación del mercado laboral, particularmente del sector formal, tiene importantes consecuencias para el ingreso de los trabajadores y la movilidad ocupacional. El objetivo de este estudio es explorar, desde una perspectiva dinámica, el impacto de la informalidad en la estructura del mercado laboral argentino, investigando especialmente la hipótesis de segmentación del sector formal en las distintas regiones del país. Con ese fin, a partir de microdatos obtenidos de la Encuesta Permanente de Hogares (EPH), se estiman brechas salariales individuales y matrices de transición que permiten analizar los movimientos entre categorías ocupacionales definidas a partir de la condición de informalidad del trabajador y del sector en el que se desempeña. El resultado más relevante es la evidencia encontrada a favor de la segmentación del sector formal. La importancia de este hallazgo radica en sus implicaciones respecto de un grupo de trabajadores 'los asalariados no registrados' que no solo sufren una penalización en términos salariales sino que permanecen bajo condiciones laborales desfavorables asociadas con la informalidad

'Todo por los chicos' o las disputas en torno de los sentidos de la política : Nociones legitimadoras, planes de empleo y proyecto colectivo en un espacio de sociabilidad local

Cuando en 2002 la política de planes de empleo se masificó, la asistencia social pasó de tener un papel residual a constituir parte explícita de las políticas de Estado. Este proceso promovió que diversos actores pugnaran por los modos de distribución y gestión de los recursos 'planes', así como por legitimar su lugar en la trama de vínculos que este modo de intervención estatal comporta. De esta manera, se configuraron experiencias de organización locales que incorporaron, a las ya múltiples temporalidades de sus dinámicas organizativas, el ritmo de la política social. En este contexto, nos proponemos indagar los modos de politicidad que emergen en una forma social específica, una copa de leche que gestiona planes sociales, en tanto espacio de interacción que condensa diferentes formas de presencia estatal, conflictos en torno de la definición de las necesidades locales y la posibilidad de imbricar criterios individuales de participación en el marco de un proyecto colectivo, que se articula en un horizonte polisémico compartido : 'Todo por los chicos'

El empleo informal y la estructura del mercado laboral en las regiones argentinas

El proceso de informalización del sector formal que se ha observado en América Latina durante los últimos años implica la coexistencia de trabajadores formales e informales que desarrollan sus actividades bajo diferentes condiciones laborales en el mismo sector. Sin embargo, la literatura, tanto empírica como teórica, le asignó tradicionalmente una estructura homogénea. No obstante, la segmentación del mercado laboral, particularmente del sector formal, tiene importantes consecuencias para el ingreso de los trabajadores y la movilidad ocupacional. El objetivo de este estudio es explorar, desde una perspectiva dinámica, el impacto de la informalidad en la estructura del mercado laboral argentino, investigando especialmente la hipótesis de segmentación del sector formal en las distintas regiones del país. Con ese fin, a partir de microdatos obtenidos de la Encuesta Permanente de Hogares (EPH), se estiman brechas salariales individuales y matrices de transición que permiten analizar los movimientos entre categorías ocupacionales definidas a partir de la condición de informalidad del trabajador y del sector en el que se desempeña. El resultado más relevante es la evidencia encontrada a favor de la segmentación del sector formal. La importancia de este hallazgo radica en sus implicaciones respecto de un grupo de trabajadores 'los asalariados no registrados' que no solo sufren una penalización en términos salariales sino que permanecen bajo condiciones laborales desfavorables asociadas con la informalidad

'Todo por los chicos' o las disputas en torno de los sentidos de la política : Nociones legitimadoras, planes de empleo y proyecto colectivo en un espacio de sociabilidad local

Cuando en 2002 la política de planes de empleo se masificó, la asistencia social pasó de tener un papel residual a constituir parte explícita de las políticas de Estado. Este proceso promovió que diversos actores pugnaran por los modos de distribución y gestión de los recursos 'planes', así como por legitimar su lugar en la trama de vínculos que este modo de intervención estatal comporta. De esta manera, se configuraron experiencias de organización locales que incorporaron, a las ya múltiples temporalidades de sus dinámicas organizativas, el ritmo de la política social. En este contexto, nos proponemos indagar los modos de politicidad que emergen en una forma social específica, una copa de leche que gestiona planes sociales, en tanto espacio de interacción que condensa diferentes formas de presencia estatal, conflictos en torno de la definición de las necesidades locales y la posibilidad de imbricar criterios individuales de participación en el marco de un proyecto colectivo, que se articula en un horizonte polisémico compartido : 'Todo por los chicos'