基于Hilbert曲线的数字图像置乱方法研究

研究了基于Hilbert曲线的数字图像置乱方法 ,引入二个概念 :“重合度”和“Hilbert曲线的平移” ,利用Hilbert曲线平移 ,获得了更多新的置乱路径 ,并根据重合度变化图探讨了置乱变换的规律 ,以测试置乱变换的周期和拟周期。然后把基于Hilbert曲线的置乱方法推广到任意大小的图像。实验结果表明 :利用Hilbert路径进行置乱不仅具有非常大的置乱路径选择空间 ,而且具有很好的置乱效果和极大的置乱周期 ,具有较大的实用性。     

睡眠剥夺对大鼠学习和行为的影响

目的 研究不同时间的睡眠剥夺（ＳＤ）及部分睡眠剥夺（ＰＳＤ）对大鼠行为和学习的影响。方法 采用小平台水环境对照,ＳＤ组有１２,２４,４８,７２,９６ｈ及ＰＳＤ,每组例数为６只,ＣＣ组为５只,测量ＳＤ后动物学会Ｙ型迷宫的总次数、时间。后体质量的变化。结果 ＴＣ组学习成绩、正确反应率优于其他各组,２４ｈ和４８ｈＳＤ组学习成绩 于ＣＣ,其他各组学习成绩不如ＣＣ,随ＳＤ时间的延长,正确反应率下降,同ＣＣ和     

生命1号健脑强身及促骨生长的实验研究

采用水迷宫法、穿梭箱法、避暗法、跳台法观察了生命1号对小鼠学习、记忆、巩固的影响。灌胃给生命1号可改善东莨菪碱、樟柳碱致小鼠记忆获得障碍。生命1号能明显提高单核细胞吞噬功能，显著增加小鼠血清溶血素的含量，促进T淋巴细胞的转化。除此之外，还能明显地增加阳虚大鼠股骨的重量、长度、直径及皮质厚度；提高血清钙、磷水平；降低血清碱性磷酸酶的含量，具有促进骨骼生长的作用。     

Optometry and WebCT: a student survey of the value of web‐based learning environments in optometric education

Purpose : Improvements in information and communication technology and the need for off‐campus delivery have led to the increased use of web‐based learning tools in optometry schools around the world. This study compared student‐reported preferences for traditional lecture‐based learning with their preferences when using a web‐based learning tool. Methods : One hundred and thirteen second and third year students from the School of Optometry and Vision Science at the University of New South Wales were surveyed. All students had worked with WebCT for at least two years. Students were asked to rank a range of learning tools in perceived usefulness and also to state how often they used the particular learning tools. Results : The students rated notes (lecture or WebCT delivered) and clinical laboratory sessions as their most useful learning tools. The use of specific learning tools was more diverse, with students reporting that they often used notes (lecture or WebCT delivered), the WebCT calendar tool and the WebCT discussion tool. This result highlights the valuable contribution of the communication aspect of WebCT to fostering learning communities. The least used learning tools were textbooks, websites mentioned in lectures and library print resources. Interestingly, the purchase of textbooks was high with 77 per cent of students on average reporting they had bought the recommended textbooks. Conclusion : Notes were the preferred learning tool of the optometry students at UNSW, suggesting that passive learning of content was the preferred learning style. It is hoped that the introduction of web‐based learning environments may allow students and staff to reflect on their preferred teaching and learning styles. Web‐based learning tools, such as WebCT, provide a powerful method to facilitate independent deeper learning in students with active learning styles. The current encouragement of student‐based active learning methods should see increased use of independent learning platforms, such as WebCT, in optometry schools.     

Mechanisms of motor learning in the cerebellum

How the elaborate neuronal circuit in the cerebellum operates and is involved in motor learning is a question addressed in earnest in studies on the cerebellum. During the past four decades, experimental studies have revealed circuit and module structures of the cerebellum, established long-term depression (LTD) as a unique and characteristic type of synaptic plasticity in the cerebellum, and analysed signal contents of activates of cerebellar neurons related to motor learning. In the 1990s, these studies were developed to detailed analyses of the signal transduction underlying LTD, and to uncovering the involvement of the cerebellum in cognitive function. On the other hand, theoretical studies yielded epochal Marr-Albus network models of the cerebellum around 1970, and introduced control system principles explaining the essential roles of the cerebellum in motor learning as providing internal models, both forward and inverse. The author maintains the hypothesis that reorganisation of the neuronal circuit by error-driven induction of LTD constitutes the major memory and learning mechanisms of the cerebellum. In this article, we examine the validity of the hypothesis in light of currently available data in recent studies of the cerebellum.     

Phospholipid composition and levels are altered in Down syndrome brain

Individuals chronically exposed to low levels of organophosphate insecticides may present with subtle impairments in cognition. In addition, low level diisopropylflurophosphate (DFP) exposure (0.25 mg/kg per day for 2 weeks) in rats resulted in protracted working memory impairment [29]. The current studies attempt to show a temporal relationship between the DFP-induced impairment in performance of a spatial memory task and the protracted decrease in the expression of cholinergic receptors and acetylcholinesterase in specific brain regions. Cholinergic receptors labeled with the ligands [(3)H]epibatidine and [(3)H]AFDX-384 were affected to a much greater extent and for a longer period of time than were both acetylcholinesterase activities and cholinergic receptors labeled with [(3)H]QNB. Pre-testing administration of nicotine was shown to completely reverse this DFP-induced impairment in memory-related task performance. Additionally, prophylaxis with pyridostigmine bromide (PB) caused DFP-treated animals to exhibit near normal levels of memory-related task performance. These results are consistent with the development of a protracted phase of learning impairment to sub-acute DFP exposure, which may involve the loss of hippocampal nicotinic receptors, and may be prevented or reversed by PB or nicotine, respectively.     

Antioxidant-rich diets improve cerebellar physiology and motor learning in aged rats

The free radical theory of aging predicts that reactive oxygen species are involved in the decline in function associated with aging. The present paper reports that diets supplemented with either spinach, strawberries or blueberries, nutritional sources of antioxidants, reverse age-induced declines in beta-adrenergic receptor function in cerebellar Purkinje neurons measured using electrophysiological techniques. In addition the spinach diet improved learning on a runway motor task, previously shown to be modulated by cerebellar norepinephrine. Motor learning is important for adaptation to changes in the environment and is thus critical for rehabilitation following stroke, spinal cord injury, and the onset of some neurodegenerative diseases. These data are the first to indicate that age-related deficits in motor learning and memory can be reversed with nutritional interventions.     

热性惊厥对大鼠情感行为及学习记忆的影响

【目的】　探讨热性惊厥对大鼠情感行为及学习记忆能力的影响。　【方法】　 3 6只雄性SD (Spraque Dawley)大鼠随机分为热性惊厥组 (febrileseizuresgroup ,FS) ,发热对照组 (febrilecontrolgroup ,FG)及正常对照组 (nor malcontrolgroup ,NG)。观察各组大鼠在旷场试验 (openfieldtest ,OFT)、避暗试验 (passiveavoidancetest,PAT)以及在Morris水迷宫 (Morriswatermaze ,MWM )试验中情感行为及学习记忆能力的改变。　【结果】　FS组大鼠与NG、FG组相比 :在OFT中穿格得分分值 ( 3 7.48± 7.0 9)降低 ,后肢性站立的次数 ( 12 .11± 4.41)减少 ,排出粪便粒数 ( 10 .62±2 .3 2 )增多 ,差异有非常显著性 (P <0 .0 1) ;在PAT中 ,FS组大鼠犯错次数 ( 4 .0 2± 1.2 9)增加 ,且记忆潜伏期 [( 169.71± 10 3 .2 2 )秒 ]缩短 ,差异有非常显著性 (P <0 .0 1) ;在Morris水迷宫试验中 ,FS组大鼠搜寻站台的逃逸潜伏期明显延长 ,差异有非常显著性 (P <0 .0 1)。　【结论】　多次热性惊厥发作可使大鼠的情感行为和学习记忆能力受损     

正常眼压性青光眼确诊时各指标间病变程度的关系

目的　考察正常眼压性青光眼 (normalpressureglaucoma ,NPG)患者确诊时的临床表现 ,探讨各指标间病变程度的关系。方法　 10 5例NPG患者 ,分析眼压曲线的平均状态、波动幅度和双眼对称性 ,观察视野和眼底C/D垂直径比值、盘沿缩窄和视网膜神经纤维层 (RNFL)改变。结果　眼压曲线双眼对称 ,总体波动水平位于 16mmHg上下 ,最高值在 10AM ,最低值在 10PM ,但10PM最低值高于年龄可比的正常人群的平均眼压 (P <0 0 1)。单值眼压分布位于 10～ 2 1mmHg ,峰值与谷值相差约 4mmHg。视野在 5 5例患者为单眼损害 ,在 14 9眼的视野损害中 ,绝大多数损害形态和部位与眼压升高的原发性开角型青光眼 (hp -POAG)相符合 ,但旁中心损害侵入中心固视区者约占 2 2 % ,而在轻度损害中约占 1/3。眼底C/D值右眼为 0 77± 0 15 ,左眼为 0 71± 0 16,二者均大于一般群体上限和早期hp -POAG患者的C/D值 (P <0 0 1) ,但在不同程度损害的视野中差异不显著 (P >0 10 ) ,盘沿缩窄和RNFL缺损的发生率分别为 5 0 %以上和 60 %以上 ,二者差异不显著 (P>0 0 5 )。结论　NPG患者的眼压在绝对值、波动幅度和双眼对称性上均与正常眼压各指标相一致 ,对诊断无定性价值。确诊时眼底C/D值大于早期hp -POAG的C/D值 ,盘沿缩窄和RNFL缺损的     

Is normal β-hCG regression curve helpful in the diagnosis of persistent trophoblastic disease?

OBJECTIVE: The aim of this study was to evaluate the probable usefulness of normal beta-human chorionic gonadotropin (beta-hCG) regression curve in the diagnosis of persistent trophoblastic disease (PTD). METHODS: A log-value regression curve was developed from the means and 95% confidence limits of serial weekly serum beta-hCG titers of 43 patients with uneventful complete hydatidiform moles and 14 patients, who were previously confirmed as PTD. RESULTS: All 14 PTD patients (100%) had abnormal values, beyond normal range, within 4 weeks. beta-hCG was in its upper values, compared to normal regression curve at 2.29 +/- 0.19 weeks. This was earlier than plateau or rise detection at 4.21 +/- 0.33 weeks (P < 0.001). Within 3 weeks of evacuation, 13 of 14 (92.86%) PTD patients' beta-hCG values exceeded the normal range, whereas only six of 14 (42%) showed a rise or plateau. CONCLUSION: Our finding indicates that the normal beta-hCG regression curve may be useful for quicker detection of PTD than the plateau or rise of level.