The effect of inlet velocity profile on the bifurcation COPD airway flow

The effect of inlet velocity profile on the flow features in obstructed airways is investigated in this study. In reality, the inlet velocity distributions on such models, which are extracted from medial branches of natural human lung, should be neither uniform, nor symmetric parabolic, but skewed-parabolic due to having been skewed by the upper carina ridges. Four different three-dimensional three-generation models based on the 23 generations model of Weibel have been considered, respectively. The fully three-dimensional incompressible laminar Navier-Stokes equations and continuity equation have been solved using CFD solver on unstructured tetrahedral meshes. To reduce the complexity of the simulations, only one Reynolds number of 900 was used in this calculation. Four types of inlet boundary conditions, namely uniform, parabolic, positive-skewed parabolic (skewed to the positive x-direction), and negative-skewed parabolic, were imposed on the obstructed airway models, which were considered to be obstructed at either the second generation or the third generation airways, respectively. The results show that the inlet velocity profile has significant influence on the flow patterns, mass distributions, and pressure drops in either the symmetric model, or the three obstructed models. The three generation airways may not be enough to study the bifurcation flow in chronic obstructive pulmonary disease (COPD) airways, and a four-generation or more airway model is necessary to get better predictive results.     

Presymptomatic atrophy in autosomal dominant Alzheimer's disease: A serial magnetic resonance imaging study

Introduction

Identifying at what point atrophy rates first change in Alzheimer's disease is important for informing design of presymptomatic trials.

A boundary element model of the human eye undergoing laser thermokeratoplasty

In the present paper, a three-dimensional radially symmetric boundary element model of the human eye is proposed for simulating changes in corneal temperature during treatment of laser thermokeratoplasty. Energy absorption inside the cornea is modeled using the Beer-Lambert law. Heat transfer inside the eye is assumed to be governed by the classical heat diffusion equation. The resulting initial-boundary value problem is solved numerically using a time-stepping boundary element method. The temperature field is calculated for heating by both the pulsed laser and the continuous wave laser. The results obtained are compared with those from other models found in the literature.     

A new approach to the study of detail perception in Autism Spectrum Disorder (ASD): investigating visual feedforward, horizontal and feedback processing

Enhanced detail processing is a characteristic of ASD. However, previous studies could not yet provide a neural explanation of this trait. Since the balance between visual feedforward and feedback processing is probably essential for the character of visual perception, we conjectured that this balance is disturbed in ASD. Using a new texture discrimination task, where surface segregation was varied independently from orientation boundaries, we showed that subjects with ASD scored lower than controls, probably caused by enhanced feedback. Interestingly, performance improved in the ASD group when repeating the task two additional times, indicating a compensation for the imbalance between feedforward and feedback processing.     

Domoic Acid and Pseudo-nitzschia spp. Connected to Coastal Upwelling along Coastal Inhambane Province,Mozambique: A New Area of Concern

Harmful algal blooms (HABs) are increasing globally in frequency, persistence, and geographic extent, posing a threat to ecosystem and human health. To date, no occurrences of marine phycotoxins have been recorded in Mozambique, which may be due to absence of a monitoring program and general awareness of potential threats. This study is the first documentation of neurotoxin, domoic acid (DA), produced by the diatom Pseudo-nitzschia along the east coast of Africa. Coastal Inhambane Province is a biodiversity hotspot where year-round Rhincodon typus (whale shark) sightings are among the highest globally and support an emerging ecotourism industry. Links between primary productivity and biodiversity in this area have not previously been considered or reported. During a pilot study, from January 2017 to April 2018, DA was identified year-round, peaking during Austral winter. During an intense study between May and August 2018, our research focused on identifying environmental factors influencing coastal productivity and DA concentration. Phytoplankton assemblage was diatom-dominated, with high abundances of Pseudo-nitzschia spp. Data suggest the system was influenced by nutrient pulses resulting from coastal upwelling. Continued and comprehensive monitoring along southern Mozambique would provide critical information to assess ecosystem and human health threats from marine toxins under challenges posed by global change.     

基于磁共振图像的人眼晶状体轮廓特征提取的方法研究

目的：提出人眼晶状体轮廓特征提取的方法。方法：使用基于Perona—Malik模型的平滑算法以及数学形态学方法做预处理，使用Canny算子做边缘检测。结果：有效地提取出晶状体的轮廓。结论：所提出的方法在工程上具有可行性。     

Effect of Intensity of Unconditional Stimulus on Reconsolidation of Contextual Fear Memory

Memory reconsolidation is ubiquitous across species and various memory tasks. It is a dynamic process in which memory is modified and/or updated. In experimental conditions, memory reconsolidation is usually characterized by the fact that the consolidated memory is disrupted by a combination of memory reactivation and inhibition of protein synthesis. However, under some experimental conditions, the reactivated memory is not disrupted by inhibition of protein synthesis. This so called "boundary condition" of reconsolidation may be related to memory strength. In Pavlovian fear conditioning, the intensity of unconditional stimulus (US) determines the strength of the fear memory. In this study, we examined the effect of the intensity of US on the reconsolidation of contextual fear memory. Strong contextual fear memory, which is conditioned with strong US, is not disrupted by inhibition of protein synthesis after its reactivation; however, a weak fear memory is often disrupted. This suggests that a US of strong intensity can inhibit reconsolidation of contextual fear memory.     

Visualization of HIFU-induced lesion boundaries by axial-shear strain elastography: a feasibility study

In this paper, we report on a study that investigated the feasibility of reliably visualizing high-intensity focused ultrasound (HIFU) lesion boundaries using axial-shear strain elastograms (ASSE). The HIFU-induced lesion cases used in the present work were selected from data acquired in a previous study. The samples consisted of excised canine livers with thermal lesions produced by a magnetic resonance-compatible HIFU system (GE Medical System, Milwaukee, WI, USA) and were cast in a gelatin block for the elastographic experiment. Both single and multiple HIFU-lesion samples were investigated. For each of the single-lesion samples, the lesion boundaries were determined independently from the axial strain elastogram (ASE) and ASSE at various iso-intensity contour thresholds (from -2 dB to -6 dB), and the area of the enclosed lesion was computed. For samples with multiple lesions, the corresponding ASSE was analyzed for identifying any unique axial-shear strain zones of interest. We further performed finite element modeling (FEM) of simple two-inclusion cases to verify whether the in vitro ASSE obtained were reasonable. The results show that the estimation of the lesion area using ASSE is less sensitive to iso-intensity threshold selection, making this method more robust compared with the ASE-based method. For multiple lesion cases, it was shown that ASSE enables high-contrast visualization of a “thin” untreated region in between multiple fully-treated HIFU-lesions. This contrast visualization was also noticed in the FEM predictions. In summary, the results demonstrate that it is feasible to reliably visualize HIFU lesion boundaries using ASSE. (E-mail: Arun.K.Thittai@uth.tmc.edu)     

中医药信息学与图书馆学的交叉与分界研究

随着信息化时代的到来以及国内外对中医药相关知识研究的不断增多,利用先进的图书馆学理念服务于中医药信息科学就显得尤为必要。本文通过对中医药信息科学与图书馆学之间的辩证关系、区别和差异的研究,探讨两门学科相互促进发展的完善策略。     

The chromosome 22q11.2 deletion: From the unification of biomedical fields to a new kind of genetic condition

How can genetics reshape nosology? This paper examines the way knowledge about a genetic mutation – the microdeletion at chromosomal locus 22q11.2 – transformed our understanding of several rare clinical syndromes and designated a qualitatively new population of patients. Taking the 1400 papers about the 22q11.2 deletion and the clinical conditions with which it was associated, we generate a network of papers tied by citations for each of the last 35 years. Using a modularity algorithm, we identify communities and evaluate their salience for the networks' overall structure. This analysis, supplemented by historical research and fieldwork with relevant experts and the advocates of affected children conducted during 2011–12, reveals that the 22q11.2 deletion acted as a ‘boundary object’ that unified clinical literatures and led to the emergence of a new kind of medical condition: 22q11.2 Deletion Syndrome (DS). The case of 22q11.2DS extends our understanding of ‘genomic designation’ – the delineation and diagnosis of clinically diffuse conditions according to characteristics of the genome – and demonstrates that observations from genetics can reconfigure existing categories of biomedical research and lead to the emergence of qualitatively new diagnostic categories.