人眼追踪远距离裸眼立体视觉检测系统的研制和测试

目的应用人眼追踪技术研制裸眼随机点立体视觉检查系统（glasses-free random dot stereo-test-system,GFRDSS）,检测正常视力男性青年的5 m距离立体视锐度。方法在不同照度环境下检测230名正常视力、正常眼位男性青年的立体视锐度。观察组采用GFRDSS检测方法;对照组采用Distance Randot（DR）检测方法。结果GFRDSS可以检测视差范围40″~800″的5 m远距离立体视锐度。100~300 cd/m2照度下,与对照组[41.3%(95/230)]比较,观察组有83.91%（193/230)受检者立体视锐度达到正常水平（40″~60″）,差异有统计学意义(Z=-9.569,P<0.05)。350~600 cd/m2照度下,与对照组[75.22%(173/230)]比较,观察组有84.78%（195/230)受检者立体视锐度达到60″,差异有统计学意义(Z=-4.048,P<0.05)。结论采用人眼追踪技术GFRDSS可以实现5 m距离无辅助立体视锐度检测,正常人群测试结果显示GFRDSS敏感性高于DR,且可以有效避免环境照度对检测的干扰。     

Analysis of the gas exchange system dynamics during high-frequency ventilation

High-frequency ventilation (HFV) as a form of artificial respiration has attracted interest in recent years as a means of reducing the risk of barotrauma in clinical applications. This paper explores the high-grequency dynamics of the gas exchange system in order to obtain mathematical models that allow optimization studies aimed at answering the question: What is the optimum ventilatory waveform that secures a certain level of gas exchange while minimizing the resulting fluctuations in pleural or alveolar pressure? Two classes of input are considered: sinusoids and band-limited white noise. A model for the dynamic relation between tracheal flow and CO₂ tension is obtained from experimental data which, in combination with existing models relating tracheal flow to pleural or alveolar pressure, allows optimization of the input flow waveform for a given level of CO₂ elimination rate. The developed relation between CO₂ elimination rate and input was verified by experimentally measured arterial CO₂ tension.     

Development of Random Forest Algorithm Based Prediction Model of Alzheimer’s Disease Using Neurodegeneration Pattern

Objective Alzheimer’s disease (AD) is the most common type of dementia and the prevalence rapidly increased as the elderly population increased worldwide. In the contemporary model of AD, it is regarded as a disease continuum involving preclinical stage to severe dementia. For accurate diagnosis and disease monitoring, objective index reflecting structural change of brain is needed to correctly assess a patient’s severity of neurodegeneration independent from the patient’s clinical symptoms. The main aim of this paper is to develop a random forest (RF) algorithm-based prediction model of AD using structural magnetic resonance imaging (MRI). Methods We evaluated diagnostic accuracy and performance of our RF based prediction model using newly developed brain segmentation method compared with the Freesurfer’s which is a commonly used segmentation software. Results Our RF model showed high diagnostic accuracy for differentiating healthy controls from AD and mild cognitive impairment (MCI) using structural MRI, patient characteristics, and cognitive function (HC vs. AD 93.5%, AUC 0.99; HC vs. MCI 80.8%, AUC 0.88). Moreover, segmentation processing time of our algorithm (<5 minutes) was much shorter than of Freesurfer’s (6–8 hours). Conclusion Our RF model might be an effective automatic brain segmentation tool which can be easily applied in real clinical practice.     

Relationship of parental bonding styles with gray matter volume of dorsolateral prefrontal cortex in young adults

Previous epidemiologic studies using the parental bonding instrument (PBI), a self-report scale to rate attitudes of parents during the first 16 years, have suggested that a lower parental care score or higher parental overprotection score could lead to an increased risk of several psychiatric disorders, including schizophrenia and mood disorder. However, neuroimaging studies of an association between PBI scores and brain developmental abnormalities are still limited. In this region-of-interest analysis study using a cross-sectional design, we examined 50 normal young adults, in terms of relationships of parental bonding styles during the first 16 years measured by PBI with regional gray matter (GM) volume in the dorsolateral prefrontal cortex (DLPFC). Our study showed that paternal care score positively correlated with the GM volume in the left DLPFC, and paternal and maternal overprotection score negatively correlated with the GM volume in the left DLPFC. In conclusion, our results suggest that in normal young adults, lower paternal care and higher parental overprotection scores correlated with the GM volume reduction in the DLPFC     

Outcrossing in the homothallic oomycete,Pythium ultimum,detected with molecular markers

The oomycete Pythium ultimum is homothallic, thus a single isolate completes the sexual stage in pure culture. It has been generally assumed that homothallic oomycetes are predominantly inbreeding. In P. ultimum, antheridia occasionally develop from hyphae not directly connected to the oogonium and appear to participate in fertilization, suggesting a possible mechanism for outcrossing. We have used molecular markers to confirm that outcrossing can occur between isolates of P. ultimum. Genetic markers based on randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLP) were used to distinguish isolates in a collection of P. ultimum. Two isolates displaying a high level of polymorphism were mixed and placed on media which allows the development of the sexual stage. RAPD markers were used to screen single oospore progeny to identify potential hybrids between the two parental isolates. Subsequent self-fertilization of one putative F₁ yielded a F₂ population which demonstrated segregation and independent assortment of RAPD and RFLP markers. A similar strategy was used to show that an isolate which is incapable of producing oospores in pure culture can outcross when mixed with a homothallic isolate. These results suggest that other homothallic oomycetes may be capable of outcrossing, and sexual reproduction may, therefore, play an important role in the generation of variation in homothallic oomycetes.     

任意引物聚合酶链反应对致病性地霉株间分型的鉴定

目的采用任意引物聚合酶链反应(AP-PCR)对部分致病性地霉进行分子生物学方面的鉴定。方法用E.Z.N.A.YeastDNA Kit提取地霉菌基因组DNA,采用任意引物S034(5′-TCTGTGCTGG-3′),S040(5′-GTTGCGATCC-3′),S167(5′-CAGCGACAAG-3′),S368(5′-GAACACTGGG-3′)对临床上致病性白地霉、林生地霉皮损株和血液株的基因组DNA进行扩增,对各病原菌的DNA指纹的特征进行分析。结果扩增产物电泳分析发现不同种真菌的DNA经扩增后显示不同的DNA带型,尤其是使用引物S040,S167和S368扩增产生的DNA带型种间差异较明显;分离自不同感染部位的同种不同株真菌的DNA经扩增后显示的主要DNA带型也有明显差异,如使用引物S040和S368扩增产生的DNA带型种内差异较明显。结论以任意引物S034,S040,S167,S368为基础的AP-PCR技术可作为临床上致病性地霉的种间及种内鉴定的简单、快速、可靠的方法。     

脂肪基质血管成分移植促进随意皮瓣成活的实验研究

目的探讨脂肪基质血管成分(Stromal vascular fraction,SVF)移植是否可以促进随意皮瓣成活,及其作用的相关机制。方法分离4周龄Wistar大鼠脂肪中的SVF及骨髓中的单个核细胞(BM-MNCs),RT-PCR检测VEGF和bFGF在两种细胞中的表达。根据移植细胞的不同,将24只Wistar大鼠分成3组,分别为对照组、BM-MNCs组和SVF组。在大鼠背部设计一个10 cm×3 cm大小的矩形皮瓣,分别将含有5×107个SVF及BM-MNCs的混悬液各1 mL均匀注射至皮下组织层,对照组单纯注射1 mL PBS。2 d后,皮瓣掀开原位缝合,术后7 d统计皮瓣的成活率。取各组皮瓣相同部位的组织,实时定量PCR检测组织中VEGF和bFGF基因的表达。结果 SVF和BM-MNCs细胞中VEGF和bFGF的表达无明显差别(P>0.05)。皮瓣原位缝合后7 d,SVF组和BM-MNCs组皮瓣的成活率分别为(72.2±2.0)%和(76.4±3.1)%,均明显高于对照组的(56.8±4.6)%(P<0.05)。实时定量PCR检测发现SVF组和BM-MNCs组皮瓣组织中VEGF和bFGF基因的表达明显升高。结论 SVF移植入皮瓣后可以通过旁分泌生长因子如VEGF和bFGF等增加皮瓣的成活面积。     

Measured attenuation correction methods

Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4–5 in brain studies to 50–100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide⁶⁸Ge/⁶⁸Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible.This article was presented at the 1st EEC workshop on accuracy determination in PET, January 19–20th. 1989 Pisa, Italy (COMAC-BME Concerted Project Characterization and Standardization of PET Instrumentation)     

Radiomics for classification of bone mineral loss: A machine learning study

PurposeThe purpose of this study was to develop predictive models to classify osteoporosis, osteopenia and normal patients using radiomics and machine learning approaches.Materials and methodsA total of 147 patients were included in this retrospective single-center study. There were 12 men and 135 women with a mean age of 56.88 ± 10.6 (SD) years (range: 28–87 years). For each patient, seven regions including four lumbar and three femoral including trochanteric, intertrochanteric and neck were segmented on bone mineral densitometry images and 54 texture features were extracted from the regions. The performance of four feature selection methods, including classifier attribute evaluation (CLAE), one rule attribute evaluation (ORAE), gain ratio attribute evaluation (GRAE) and principal components analysis (PRCA) along with four classification methods, including random forest (RF), random committee (RC), K-nearest neighbor (KN) and logit-boost (LB) were evaluated. Four classification categories, including osteopenia vs. normal, osteoporosis vs. normal, osteopenia vs. osteoporosis and osteoporosis + osteopenia vs. osteoporosis were examined for the defined seven regions. The classification model performances were evaluated using the area under the receiver operator characteristic curve (AUC).ResultsThe AUC values ranged from 0.50 to 0.78. The combination of methods RF + CLAE, RF + ORAE and RC + ORAE yielded highest performance (AUC = 0.78) in discriminating between osteoporosis and normal state in the trochanteric region. The combinations of RF + PRCA and LB + PRCA had the highest performance (AUC = 0.76) in discriminating between osteoporosis and normal state in the neck region.ConclusionThe machine learning radiomic approach can be considered as a new method for bone mineral deficiency disease classification using bone mineral densitometry image features.     

Unravelling animal exposure profiles of human Q fever cases in Queensland,Australia, using natural language processing

Q fever, caused by the zoonotic bacterium Coxiella burnetii, is a globally distributed emerging infectious disease. Livestock are the most important zoonotic transmission sources, yet infection in people without livestock exposure is common. Identifying potential exposure pathways is necessary to design effective interventions and aid outbreak prevention. We used natural language processing and graphical network methods to provide insights into how Q fever notifications are associated with variation in patient occupations or lifestyles. Using an 18‐year time‐series of Q fever notifications in Queensland, Australia, we used topic models to test whether compositions of patient answers to follow‐up exposure questionnaires varied between demographic groups or across geographical areas. To determine heterogeneity in possible zoonotic exposures, we explored patterns of livestock and game animal co‐exposures using Markov Random Fields models. Finally, to identify possible correlates of Q fever case severity, we modelled patient probabilities of being hospitalized as a function of particular exposures. Different demographic groups consistently reported distinct sets of exposure terms and were concentrated in different areas of the state, suggesting the presence of multiple transmission pathways. Macropod exposure was commonly reported among Q fever cases, even when exposure to cattle, sheep or goats was absent. Males, older patients and those that reported macropod exposure were more likely to be hospitalized due to Q fever infection. Our study indicates that follow‐up surveillance combined with text modelling is useful for unravelling exposure pathways in the battle to reduce Q fever incidence and associated morbidity.