A high-wavenumber boundary-element method for an acoustic scattering problem

In this paper we show stability and convergence for a novel Galerkin boundary element method approach to the impedance boundary value problem for the Helmholtz equation in a half-plane with piecewise constant boundary data. This problem models, for example, outdoor sound propagation over inhomogeneous flat terrain. To achieve a good approximation with a relatively low number of degrees of freedom we employ a graded mesh with smaller elements adjacent to discontinuities in impedance, and a special set of basis functions for the Galerkin method so that, on each element, the approximation space consists of polynomials (of degree $\nu$) multiplied by traces of plane waves on the boundary. In the case where the impedance is constant outside an interval $[a,b]$, which only requires the discretization of $[a,b]$, we show theoretically and experimentally that the $L_2$ error in computing the acoustic field on $[a,b]$ is ${\cal O}(\log^{\nu+3/2}|k(b-a)| M^{-(\nu+1)})$, where $M$ is the number of degrees of freedom and $k$ is the wavenumber. This indicates that the proposed method is especially commendable for large intervals or a high wavenumber. In a final section we sketch how the same methodology extends to more general scattering problems

A Galerkin boundary element method for high frequency scattering by convex polygons

In this paper we consider the problem of time-harmonic acoustic scattering in two dimensions by convex polygons. Standard boundary or finite element methods for acoustic scattering problems have a computational cost that grows at least linearly as a function of the frequency of the incident wave. Here we present a novel Galerkin boundary element method, which uses an approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh, with smaller elements closer to the corners of the polygon. We prove that the best approximation from the approximation space requires a number of degrees of freedom to achieve a prescribed level of accuracy that grows only logarithmically as a function of the frequency. Numerical results demonstrate the same logarithmic dependence on the frequency for the Galerkin method solution. Our boundary element method is a discretization of a well-known second kind combined-layer-potential integral equation. We provide a proof that this equation and its adjoint are well-posed and equivalent to the boundary value problem in a Sobolev space setting for general Lipschitz domains

Computational evidence for an early, amplified systemic inflammation program in polytrauma patients with severe extremity injuries

Extremity and soft tissue injuries contribute significantly to inflammation and adverse in-hospital outcomes for trauma survivors; accordingly, we examined the complex association between clinical outcomes inflammatory responses in this setting using in silico tools. Two stringently propensity-matched, moderately/severely injured (Injury Severity Score > 16) patient sub-cohorts of ~30 patients each were derived retrospectively from a cohort of 472 blunt trauma survivors and segregated based on their degree of extremity injury severity (above or below 3 on the Abbreviated Injury Scale). Serial blood samples were analyzed for 31 plasma inflammatory mediators. In addition to standard statistical analyses, Dynamic Network Analysis (DyNA) and Principal Component Analysis (PCA) were used to model systemic inflammation following trauma. Patients in the severe extremity injury sub-cohort experienced longer intensive care unit length of stay (LOS), total LOS, and days on a mechanical ventilator, with higher Marshall Multiple Organ Dysfunction (MOD) Scores over the first 7 days post-injury as compared to the mild/moderate extremity injury sub-cohort. The higher severity cohort had statistically significant elevated lactate, base deficit, and creatine phosphokinase on first blood draw, along with significant changes in multiple circulating inflammatory mediators. DyNA pointed to a sustained role for type 17 immunity in both sub-cohorts, along with IFN-γ in the severe extremity injury group. DyNA network complexity increased over 7 days post-injury in the severe injury group, while generally decreasing over this same time period in the mild/moderate injury group. PCA suggested a more robust activation of multiple pathways in the severe extremity injury group as compared to the mild/moderate injury group. These studies thus point to the possibility of self-sustaining inflammation following severe extremity injury vs. resolving inflammation following less severe extremity injury

p16INK4A expression is frequently increased in periorbital and ocular squamous lesions

Backgroundp16 expression is a well established biomarker of cervical dysplasia and carcinoma arising from high risk human papilloma virus infection. Increased p16 expression is also seen in squamous neoplasms arising at other sites, including head, neck, and oropharyngeal tract. Squamous lesions are also frequently encountered at ocular surface and peri-orbital skin sites, but the prevalence of increased p16 expression in these lesions has been poorly studied.MethodsWe retrospectively surveyed 13 ocular surface and 16 orbital squamous lesions biopsied at UC San Diego Healthcare System and VA San Diego Healthcare System for p16 expression by immunohistochemistry. These cases included ocular surface lesions with diagnoses of conjunctival intraepithelial neoplasm (CIN) and squamous cell carcinoma in situ. Peri-orbital eyelid biopsies included lesions with diagnoses of SCCis and invasive squamous cell carcinoma. We performed multivariate logistic regression, followed by student's T-test or Fisher's exact test to determine if there were statistically significant associations between p16 immunoreactivity and patient age, gender, diagnosis, and ethnicity. Statistical significance was defined as p < 0.05.ResultsWe found an unexpectedly large prevalence of strong nuclear and cytoplasmic p16 immunoreactivity in our cases. Almost all of the ocular surface squamous lesions were diffusely positive for p16 expression (12/13). All of the periorbital lesions showed diffuse p16 immunoreactivity (16/16). Altogether, 28/29 lesions tested showed strong and diffuse p16 expression. We found no statistically significant correlation between p16 expression and patient age, gender, ethnicity, or diagnosis. In 6 of the peri-orbital biopsies, we had sufficient tissue to assess high-risk HPV expression by in situ hybridization. Interestingly, all of these cases were negative for HPV, despite strong p16 expression.ConclusionStrong p16 expression was observed in virtually all of the ocular surface and peri-orbital squamous neoplasms in our study. The relationship between p16 expression and HPV infection in ocular surface and peri-orbital sites requires further investigation

Automatic detection of the end-diastolic and end-systolic from 4D echocardiographics images

Accurate detection of the End-Diastolic (ED) and End-Systolic (ES) frames of a cardiac cycle are significant factors that may affect the accuracy of abnormality assessment of a ventricle. This process is a routine step of the ventricle assessment procedure as most of the time in clinical reports many parameters are measured in these two frames to help in diagnosing and dissection making. According to the previous works the process of detecting the ED and ES remains a challenge in that the ED and ES frames for the cavity are usually determined manually by review of individual image phases of the cavity and/or tracking the tricuspid valve. The proposed algorithm aims to automatically determine the ED and ES frames from the four Dimensional Echocardiographic images (4DE) of the Right Ventricle (RV) from one cardiac cycle. By computing the area of three slices along one cardiac cycle and selecting the maximum area as the ED frame and the minimum area as the ES frame. This method gives an accurate determination for the ED and ES frames, hence avoid the need for time consuming, expert contributions during the process of computing the cavity stroke volume

Assessment of HCC response to Yttrium-90 radioembolization with gadoxetate disodium MRI: correlation with histopathology.

Transarterial <sup>90</sup> Y radioembolization (TARE) is increasingly being used for hepatocellular carcinoma (HCC) treatment. However, tumor response assessment after TARE may be challenging. We aimed to assess the diagnostic performance of gadoxetate disodium MRI for predicting complete pathologic necrosis (CPN) of HCC treated with TARE, using histopathology as the reference standard. This retrospective study included 48 patients (M/F: 36/12, mean age: 62 years) with HCC treated by TARE followed by surgery with gadoxetate disodium MRI within 90 days of surgery. Two radiologists evaluated tumor response using RECIST1.1, mRECIST, EASL, and LI-RADS-TR criteria and evaluated the percentage of necrosis on subtraction during late arterial, portal venous, and hepatobiliary phases (AP/PVP/HBP). Statistical analysis included inter-reader agreement, correlation between radiologic and pathologic percentage of necrosis, and prediction of CPN using logistic regression and ROC analyses. Histopathology demonstrated 71 HCCs (2.8 ± 1.7 cm, range: 0.5-7.5 cm) including 42 with CPN, 22 with partial necrosis, and 7 without necrosis. EASL and percentage of tumor necrosis on subtraction at the AP/PVP were independent predictors of CPN (p = 0.02-0.03). Percentage of necrosis, mRECIST, EASL, and LI-RADS-TR had fair to good performance for diagnosing CPN (AUCs: 0.78 - 0.83), with a significant difference between subtraction and LI-RADS-TR for reader 2, and in specificity between subtraction and other criteria for both readers (p-range: 0.01-0.04). Radiologic percentage of necrosis was significantly correlated to histopathologic degree of tumor necrosis (r = 0.66 - 0.8, p < 0.001). Percentage of tumor necrosis on subtraction and EASL criteria were significant independent predictors of CPN in HCC treated with TARE. Image subtraction should be considered for assessing HCC response to TARE when using MRI. • Percentage of tumor necrosis on image subtraction and EASL criteria are significant independent predictors of complete pathologic necrosis in hepatocellular carcinoma treated with <sup>90</sup> Y radioembolization. • Subtraction, mRECIST, EASL, and LI-RADS-TR have fair to good performance for diagnosing complete pathologic necrosis in hepatocellular carcinoma treated with <sup>90</sup> Y radioembolization

A utilização do ELISA empregando antígenos homólogos e heterólogos para a detecção de IgG e subclasses (IgG1 e IgG2) no diagnóstico de Leishmaniose visceral canina

Indirect immunofluorescence is the method recommended for the diagnosis of visceral leishmanisis in dogs, however, the accuracy of this technique is low and its use on a large scale is limited. Since ELISA does not present these limitations, this technique might be an option for the detection of IgG or specific IgG1 and IgG2 subclasses. Canine ehrlichiosis is an important differential diagnosis of American Visceral Leishmaniasis (AVL). The present study compared ELISA using Leishmania chagasi and Leishmania braziliensis antigen for the detection of anti-Leishmania IgG and subclasses in serum samples from 37 dogs naturally infected with L. chagasi (AVL) and in samples from four dogs co-infected with L. braziliensis and L. chagasi (CI). The occurrence of cross-reactivity was investigated in control serum samples of 17 healthy dogs (HC) and 35 infected with Ehrlichia canis (EC). The mean optical density obtained for the detection of IgG was significantly higher when L. chagasi antigen was used, and was also higher in subgroup VLs (symptomatic) compared to subgroup Vla (asymptomatic). The correlation between IgG and IgG1 was low. The present results suggest that IgG ELISA using homologous antigen yields the best results, permitting the diagnosis of asymptomatic L. chagasi infection and the discrimination between cases of AVL and ehrlichiosis in dogs.A imunofluorescência indireta é o método recomendado para o diagnóstico de leishmaniose visceral em cães, entretanto, a acurácia dessa técnica é baixa e seu uso em grande escala é limitado. Uma vez que o ELISA não apresenta essas limitações, essa técnica poderia ser uma opção para a detecção de IgG ou subclasses IgG1 e IgG2 específicas. A ehrlichiose canina é um importante diagnóstico diferencial de Leishmaniose Visceral Americana (LVA). O presente estudo comparou o ELISA usando antígenos de Leishmania chagasi e Leishmania braziliensis para a detecção de IgG e subclasses anti-Leishmania em amostras de soro de 37 cães naturalmente infectados com L. chagasi (LVA) e em amostras de quatro cães co-infectados (CI). A ocorrência de reatividade cruzada foi investigada em amostras de soro controle de 17 animais saudáveis (HC) e 35 de infectados por Ehrlichia canis (EC). A média de densidade óptica obtida para a detecção de IgG foi significantemente maior quando o antígeno de L. chagasi foi usado e também mais elevada no subgrupo LVs (sintomático) quando comparado ao subgrupo LVa (assintomático). A correlação entre IgG e IgG1 foi baixa. O presente resultado sugere que ELISA IgG empregando antígeno homólogo, produz os melhores resultados, permitindo o diagnóstico de infecção assintomática por L. chagasi e a discriminação entre casos de LVA e ehrlichiose em cães