Assessment and management of urethrocutaneous fistula developing after hypospadias repair

Background/Purpose To highlight and assess the different factors related to the development of urethrocutaneous fistulae (UCFs) after hypospadias repair, and the outcome of their repair using two different techniques.Patients and methods In the period June 2009 to October 2010, all patients presenting to the Pediatric Surgery Unit at the Cairo University Pediatric Hospital with fistulae after hypospadias repair were divided into three groups. The first group included the patients with distal small fistula (less than 2mm in size). The second group included the patients with more proximal and larger fistulae (2–4mm in size). The third group included the patients with multiple fistulae or recurrent persistent fistulae (more than 4mm in size). Risk factors related to the development of UCF were assessed, and the outcome of fistula closure was analyzed. The followup periods ranged from 6 to 12 months. The mean follow-up period was 8 months. The protocol of the study was approved by the Ethics Committee of the Cairo University.Results Sixty-seven patients with posthypospadias repair fistulae were included in this study; 52 patients (77.6%) had fistula repair for the first time and 15 patients (22.3%) had fistula repair for recurrent fistula. Twenty-one patients (31.3%) had anterior penile fistulae, whereas 13 patients (19.4%) had coronal fistulae and nine patients (13.4%) had midpenile fistulae. Eight patients (11.9%) had acquired penoscrotal fistulae. Sixteen patients (23.8%) had multiple and/or branching fistulae. Ten patients (14.9%) had direct closure of the fistula, whereas 57 patients (85.1%) had fistula closure with dartos flap coverage. Successful fistula repair was achieved in 56 patients (83.5%), whereas fistula recurrence occurred in 11 patients (16.5%).Conclusion There is no single, universally applicable technique for repairing all types of UCF after hypospadias. The repair depends on the size and site of fistula, the complexity of previous operations performed for closure of fistula, the original hypospadias technique for repair of hypospadias, and the condition of the nearby skin. Primary repair of UCF and covering the repair with dartos flap give excellent results. It is suitable for repair of a wide variety of fistulae and is easier to perform by junior surgeons.Keywords: hypospadias, urethra, urethrocutaneous fistul

Influence of trace erythromycin and eryhthromycin-H2O on carbon and nutrients removal and on resistance selection in sequencing batch reactors (SBRs).

Three sequencing batch reactors (SBRs) were operated in parallel to study the effects of trace erythromycin (ERY) and ERY-H2O on the treatment of a synthetic wastewater. Through monitoring (1) daily effluents and (2) concentrations of nitrogen (N) and phosphorous (P) in certain batch cycles of the three reactors operated from transient to steady states, the removal of carbon, N, and P was affected negligibly by ERY (100 microg/L) or ERY-H2O (50 microg/L) when compared with the control reactor. However, through analyzing microbial communities of the three steady state SBRs on high-density microarrays (Phylo-Chip), ERY, and ERY-H2O had pronounced effects on the community composition of bacteria related to N and P removal, leading to diversity loss and abundance change. The above observations indicated that resistant bacteria were selected upon exposure to ERY or ERY-H2O. Shortterm batch experiments further proved the resistance and demonstrated that ammonium oxidation (56-95%) was inhibited more significantly than nitrite oxidation (18-61%) in the presence of ERY (100, 400, or 800 microg/L). Therefore, the presence of ERY or ERY-H2O (at microg/L levels) shifted the microbial community and selected resistant bacteria, which may account for the negligible influence of the antibiotic ERY or its derivative ERY-H2O (at microg/L levels) on carbon, N, and P removal in the SBRs

Bayesian hydrograph separation in a minimally gauged alpine volcanic watershed in central Chile

This study examines the question of how much information one can extract from a tracer-based hydrograph separation in a remote and minimally gaged alpine catchment in Chile. We combine PCA-based endmember mixing analysis to identify the sources of flow contribution to the Diguillín River with a hierarchical Bayesian mixing model to integrate spatial and temporal variability in endmember concentration and quantify the source contributions to streamflow over time. The PCA-analysis shows that precipitation isotopes do not vary by elevation (e.g. snow and rainfall had identical signatures) but vary significantly by season, and that a third endmember is necessary to bound streamflow variability at the basin outlet, which was not captured by our field sampling. One of the main advantages of Bayesian methods is the quasi-machine learning capabilities, where we treated the third endmember as a parameter from which the mixing model could both estimate proportional contributions as well as posterior estimates for the tracer concentrations. The two tracer, three endmember hydrograph separation revealed groundwater to be the largest and precipitation (rain and snow) to be the smallest contributor, on average, to streamflow with the third unknown endmember contributing around 40% of streamflow during the Winter wet season. We hypothesize that interflow is occurring as the third endmember in the Alto Diguillín subwatershed, based on inferred tracer values and the presence of alluvium atop impermeable bedrock along certain reaches. More work is necessary to observe and sample these flowpaths, which was not possible during this study. The results of this work have implications for water resource management, since groundwater sustains the majority of streamflow in the Diguillín, and climate change will impact the timing and quantity of baseflow and interflow. Overall, we demonstrate the utility of combining PCA with Bayesian statistical modeling and inference to extract maximum information from a limited field dataset in a remote alpine catchment. The findings of this work can guide future water management in the Diguillín, but also provide clear questions for future research

Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic features and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Furthermore, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies

Simulation of indoor harmful gas dispersion and airflow using three-dimensional lattice Boltzmann method based large-eddy simulation

ABSTRACT The lattice Boltzmann method (LBM) and large-eddy simulation (LES) are combined with a scalar subgrid-scale model to simulate the indoor air velocity field and harmful gas dispersion. The LBM-LES model is validated by comparing its results with published experimental and numerical simulation results. Taking a simplified chemical building as the scenario, the relative ventilation efficiency is evaluated based on the maximum harmful gas concentration, and configurations with centralized and distributed harmful gas sources with both mixing ventilation (MV) and displacement ventilation (DV) systems are considered. According to the results, if the density of the harmful gas is less than the air density, the DV system is more efficient than the MV system. The DV system is more stable than the MV system under fluctuating relative ventilation efficiency due to changes in the distance between the ventilation vents and in the distance between the centralized gas sources and the exhaust air vent

Lattice Boltzmann methods for multiphase flow and phase-change heat transfer

Over the past few decades, tremendous progress has been made in the development of particle-based discrete simulation methods versus the conventional continuum-based methods. In particular, the lattice Boltzmann (LB) method has evolved from a theoretical novelty to a ubiquitous, versatile and powerful computational methodology for both fundamental research and engineering applications. It is a kinetic-based mesoscopic approach that bridges the microscales and macroscales, which offers distinctive advantages in simulation fidelity and computational efficiency. Applications of the LB method are now found in a wide range of disciplines including physics, chemistry, materials, biomedicine and various branches of engineering. The present work provides a comprehensive review of the LB method for thermofluids and energy applications, focusing on multiphase flows, thermal flows and thermal multiphase flows with phase change. The review first covers the theoretical framework of the LB method, revealing certain inconsistencies and defects as well as common features of multiphase and thermal LB models. Recent developments in improving the thermodynamic and hydrodynamic consistency, reducing spurious currents, enhancing the numerical stability, etc., are highlighted. These efforts have put the LB method on a firmer theoretical foundation with enhanced LB models that can achieve larger liquid-gas density ratio, higher Reynolds number and flexible surface tension. Examples of applications are provided in fuel cells and batteries, droplet collision, boiling heat transfer and evaporation, and energy storage. Finally, further developments and future prospect of the LB method are outlined for thermofluids and energy applications

Disease burden of influenza in three tropic and sub-tropic cities in Asia

Powerpoint PresentationSession 2 - Disease burden and transmission dynamics of inter-pandemic influenzaThe impact of influenza on mortality in sub-tropical and tropical countries is poorly quantified. The obstacle is mainly from assessing the disease burden among irregular seasonality of influenza activities in the warm climates. In this study we applied statistical modeling methods to three metropolitan cities in East and Southeast Asia: Guangzhou, Hong Kong, and Singapore, all of which have standardized influenza surveillance networks for years 2004-2006. We applied the method of Generalized Additive Modeling (GAM) to evaluate the effect of influenza circulation in the community on all-cause mortality and on mortality with an underlying cause of cardio-respiratory diseases. The strength of GAM lies on its capability in adjusting for the seasonality of health outcomes in the investigation for their association with influenza activity, particularly in the subtropics and tropics. Our findings indicated that influenza was associated with 12.4 (95% confidence interval (CI): 1.2, 23.0), 13.9 (95% CI: 6.4, 20.9) and 8.7 (95% CI: 3.0, 13.9) deaths for all causes per 100,000 population in Guangzhou, Hong Kong, and Singapore, respectively. For the cardio-respiratory mortality, influenza was associated with 11.2 (95% CI: 2.4, 19.6), 9.1 (95% CI: 4.3, 13.6) and 5.5 (95% CI: 1.6, 9.4) deaths per 100,000 population in the three cites. These results showed that the disease burdens in the two subtropical cities Guangzhou and Hong Kong were similar and slightly higher than those in the tropical city, Singapore. In the future, a cross region study involving temperate, subtropical, and tropical climates could provide more information about the health effects of influenza in Asia.postprin

Impact of the 2009 H1N1 Pandemic on Age-Specific Epidemic Curves of Other Respiratory Viruses: A Comparison of Pre-Pandemic, Pandemic and Post-Pandemic Periods in a Subtropical City

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