Syed Ashraf Ali

Identification of biofilms in post-tympanostomy tube otorrhea

Otitis media is a common problem in the pediatric population. Despite antibiotic therapy, post‐tympanostomy otorrhea can be difficult to treat. Biofilms have been shown to play a role in chronic and recurrent otitis media and are implicated in otorrhea. This study investigated both the microbial composition and the presence of biofilm fragments rich in extracellular DNA (eDNA) and the bacterial DNA‐binding protein, integration host factor (IHF), in post‐tympanostomy tube otorrhea.

Initial experience from a multidisciplinary pediatric salivary gland disorder clinic.

OBJECTIVE This study is the first in the literature to characterize and detail the clinical and surgical experience of one of the few multidisciplinary salivary gland disorder clinics in North America. METHODS This is a retrospective chart review of a descriptive nature, including patient information from February 2013 to August 2014. The Salivary Gland Disorder Clinic (SGDC) is located at Nationwide Childrens Hospital, a public academic hospital. All patients seen at the SGDC were included in this study, 54 in total. Patients were seen for any salivary gland disorder presentation, ranging from sialorrhea to glandular masses. RESULTS A total of 70.4% of patients presented to the SGDC with a chief complaint of sialorrhea. Nearly 28% had previously experienced documented aspiration, and drooling severity and frequency was 4.06 and 3.3 on the Thomas-Stonell and Greenberg Drooling Rating Scales. 50% of patients presented with neurologic comorbidities and 25.9% with aerodigestive tract anatomic defects. Over 35% of patients had previously attempted medical treatment and 31.5% had no prior treatment attempts. 87% of all patients were offered further treatment options, including interventional, surgical, medical, and conservative measures. CONCLUSIONS Pediatric salivary gland disorders, especially sialorrhea, can profoundly impact overall health and quality of life. Appropriate management of this symptom requires expert training and knowledge of the upper aerodigestive tract anatomy and appropriate treatment modalities. Our study demonstrates that there is community need for a centralized salivary gland disorder clinic given the complex comorbidities and social challenges that face this population. Many patients present with great risk for aspiration-related complications and the vast majority are offered new treatment options.

Effect of adjuvant radiotherapy treatment center volume on overall survival

OBJECTIVES to examine the impact of radiotherapy center volume on overall survival in patients with oral cavity and oropharyngeal squamous cell carcinoma getting adjuvant radiation therapy after receiving surgery at a high-volume center. MATERIALS AND METHODS a retrospective study was conducted on patients with oral cavity squamous cell carcinoma or oropharyngeal squamous cell carcinoma treated surgically at a tertiary institution from 2000 to 2012 who received adjuvant radiotherapy. The outcome variable was overall survival and the independent variable was location of adjuvant radiation therapy: high-volume center (HVC) versus low-volume center (LVC). Cox proportional hazards models were used to assess associations between predictors of death. Variables that were found to be significant at the α = 0.10 were included in a multivariable model. RESULTS 336 patients met inclusion criteria. One-hundred thirty-nine patients received adjuvant radiation therapy at HVC and 197 patients received adjuvant radiation therapy at LVC. A univariate Cox proportional hazards model identified the variables location, age, marital status, subsite, T stage, extracapsular extension, and smoking status to include in a multivariable model. Age, subsite, T stage, and extracapsular extension were independent predictors of overall survival (p < .05). Location (p = .55), marital status (p = .29), and smoking status (p = .22) were not statistically significant predictors of survival. CONCLUSION After surgery at a HVC, the volume of adjuvant radiation therapy center was not significantly associated with overall survival. Significant predictors of survival included age, subsite, T stage, and extracapsular extension.

Prediction of Non-Equilibrium Heat Conduction Using Parallel Computation of the Phonon Boltzmann Transport Equation

Non-equilibrium heat conduction, as occurring in modern-day sub-micron semiconductor devices, can be predicted effectively using the Boltzmann Transport Equation (BTE) for phonons. In this article, strategies and algorithms for large-scale parallel computation of the phonon BTE are presented. An unstructured finite volume method for spatial discretization is coupled with the control angle discrete ordinates method for angular discretization. The single-time relaxation approximation is used to treat phonon-phonon scattering. Both dispersion and polarization of the phonons are accounted for. Three different parallelization strategies are explored: (a) band-based, (b) direction-based, and (c) hybrid band/cell-based. Subsequent to validation studies in which silicon thin-film thermal conductivity was successfully predicted, transient simulations of non-equilibrium thermal transport were conducted in a three-dimensional device-like silicon structure, discretized using 604,054 tetrahedral cells. The angular space was discretized using 400 angles, and the spectral space was discretized into 40 spectral intervals (bands). This resulted in ∼9.7×109 unknowns, which are approximately 3 orders of magnitude larger than previously reported computations in this area. Studies showed that direction-based and hybrid band/cell-based parallelization strategies resulted in similar total computational time. However, the parallel efficiency of the hybrid band/cell-based strategy — about 88% — was found to be superior to that of the direction-based strategy, and is recommended as the preferred strategy for even larger scale computations.Copyright

Computational Modeling of Transverse Peltier Coolers

Transverse thermoelectric effect can be produced artificially by stacking at an angle layers of a thermoelectric material with another material that may or may not be a thermoelectric material. In this exploratory computational study, a new metamaterial, comprised of tilted alternating layers of an n-type thermoelectric alloy and a metal, is investigated to gain an understanding of how much cooling can be produced by transverse thermoelectric effect and the conditions under which maximum cooling is attainable. The governing conservation equations of energy and electric current, with the inclusion of thermoelectric effects, are solved on an unstructured mesh using the finite-volume method to simulate a transverse Peltier cooler under various operating conditions. First, the code is validated against experimental data for a n-Bi2Te3-Pb metamaterial, and subsequently explored. It is found that intermediate applied currents produce maximum temperature depression (ΔT). Optimum values of the geometric design parameters such as tilt angle and device aspect ratio are also established through parametric studies. Finally, it is shown that the ΔT can be amplified by constricting the phonon (heat) transport cross-section while keeping the electron (current) transport cross-section unchanged — a strategy that cannot be employed in conventional thermoelectric devices where electrons and phonons follow the same path. This makes transverse Peltier coolers particularly attractive for generating large ΔT without multi-stage cascading.Copyright