Understanding of the concept of numerically "less" by bottlenose dolphins (Tursiops truncatus).

In 2 experiments, bottlenose dolphins (Tursiops truncatus) judged the ordinal relationship between novel numerosities. The dolphins were first trained to choose the exemplar with the fewer number of items when presented with just a few specific comparisons (e.g., 2 vs. 6, 1 vs. 3, and 3 vs. 7). Generalization of this rule was then tested by presenting the dolphins with all possible pairwise comparisons between 1 and 8. The dolphins chose the exemplar with the fewer number of items at levels far above chance, showing that they could recognize and represent numerosities on an ordinal scale. Their pattern of errors was consistent with the idea of an underlying analog magnitude representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

如何使转换器不再需要散热器

本文探讨为何以同步整流器为基础的DC／DC转换器不带散热器还比传统的以肖特基二极管为基础的转换器带散热器能产生更多有用的输出功率。文章首先分析当DC／DC转换器的散热器被拆除后会损失多少“散热”能力。然后阐述较之低效率的传统转换器而言，以同步整流器为基础的转换器需要散发的热量少了多少。最后，文章比较两种转换器的功率降额曲线(derating curves)，以说明同步整流转换器因为高效率的所得胜过因为拆除散热器而受到的损失。     

Hypothalamus-pituitary-adrenal activity during human sleep: a coordinating role for the limbic hippocampal system

It is well known that deglycosylation of gonadotropins by enzymatic or chemical procedures or by deletion of sites for N-linked glycosylation produces antagonistic analogs which are able to interact strongly with the receptor and to inhibit binding of the wild-type hormone. In the present study, we analyzed the antagonistic properties of a naturally occurring basic follicle-stimulating hormone (FSH) charge isoform obtained after high-resolution chromatofocusing of human anterior pituitary glycoprotein extracts. Coincubation of increasing amounts of this isoform with a highly purified human pituitary FSH preparation or with recombinant human FSH at doses equivalent to their corresponding ED50 for estradiol and tissue-type plasminogen activator (tPA) production, inhibited FSH-induced estrogen production and tPA enzyme activity by cultured rat granulosa cells in a dose-dependent manner. These inhibitory effects were apparently exerted at steps following 3',5'-cyclic adenosine monophosphate (cAMP) formation and did not involve activation of the protein kinase C pathway since: (a) at low doses, this basic FSH isoform moderately increased FSH-induced cAMP production by cultured rat granulosa cells; (b) coincubation of the antagonist isoform with dibutyryl cAMP completely inhibited the effects of this cAMP analog on estrogen and tPA production; (c) the isoform was able to stimulate production of cAMP in a human fetal cell line expressing the recombinant human FSH receptor, and (d) the inhibitory effects of the isoform were not affected by staurosporine, a protein kinase C inhibitor. The effects of this isoform upon dibutyryl cAMP-induced estrogen and tPA production were blocked by the addition of a highly specific antibody directed against human FSH, further demonstrating that the antagonistic effects observed were due to FSH-like molecules. In contrast to the inhibitory effects exhibited by this basic FSH isoform, a more acidic FSH charge variant consistently acted as an agonist of pituitary and recombinant FSH on both estrogen production and induction of tPA enzyme activity. These results indicate that the anterior pituitary gland normally produces FSH isoforms which act as either agonists or antagonists of FSH at the target cell level.     

Altered hippocampal kainate-receptor mRNA levels in temporal lobe epilepsy patients

This study determined whether hippocampal kainate (KA) receptor mRNA levels were increased or decreased in temporal lobe epilepsy patients compared with nonseizure autopsies. Hippocampal sclerosis (HS; n = 17), nonsclerosis (non-HS; n = 11), and autopsy hippocampi (n = 9) were studied for KA1-2 and GluR5-7 mRNA levels using semiquantitative in situ hybridization techniques, along with neuron densities. Compared with autopsy hippocampi, HS and non-HS cases showed decreased GluR5 and GluR6 hybridization densities per CA2 and/or CA3 pyramid. Furthermore, HS patients demonstrated increased KA2 and GluR5 hybridization densities per granule cell compared with autopsy hippocampi. These findings indicate that chronic temporal lobe seizures were associated with differential changes in hippocampal KA1-2 and GluR5-7 hybridization densities that vary by subfield and pathology group. In temporal lobe epilepsy patients, these results support the hypothesis that pyramidal cell GluR5 and GluR6 mRNA levels are decreased as a consequence of seizures, and in HS patients granule cell KA2 and GluR5 mRNA levels are increased in association with aberrant fascia dentata mossy fiber sprouting and/or hippocampal neuronal loss.     

Hormonal secretion during nighttime sleep indicating stress of daytime exercise

We tested the hypothesis that long-duration exercise (LDE) of moderate intensity, but not LDE of low intensity, during the daytime changes the typical temporal patterns of hormone release during subsequent nocturnal sleep. Ten trained healthy men participated in a balanced crossover study including three conditions: 1) no exercise, 2) LDE of low intensity (biking 40 km; 1800-2030), and 3) LDE of moderate intensity (biking 120-150 km; 1600-2030). During the subsequent night (2300-0700), somnopolygraphic sleep recordings were obtained, and concentrations of cortisol, growth hormone (GH), and testosterone were measured every 15 min. During the no exercise nights, the typical secretory patterns were present with peak concentrations of GH but nadir concentrations of cortisol during the first half of sleep but increased cortisol levels and minimum GH levels during the second part of sleep. Testosterone concentrations increased during the second half of sleep. LDE of moderate intensity reduced rapid-eye-movement sleep [13.9 vs. 16.9% (no exercise); P < 0.01]. Levels of testosterone decreased with increasing intensity of daytime exercise (P < 0.05). Moderate-, but not low-intensity, LDE decreased GH levels in the first half (P < 0.05) and increased GH levels in the second half (P < 0.005) of sleep. Also, LDE of moderate intensity but not LDE of low intensity increased cortisol levels during the first half (P < 0.005) and decreased cortisol secretion during the second half (P < 0.05) of sleep. Results suggest that nocturnal profiles of GH and cortisol concentrations may serve to indicate the disturbance of normal anabolic functions of sleep due to daytime exercise.     

基于时空特性以及需求响应的DG和EV充电站多目标优化配置

针对可再生分布式电源(DG)及电动汽车(EV)大规模接入给配电网带来的用电量增长以及电压波动问题,提出一种基于时空特性以及需求响应的DG和EV充电站多目标协调优化配置方法.通过提取城市路网的拓扑结构,监测路网流量,基于交通规划软件TransCAD进行起讫点(OD)矩阵反推,构建出行概率矩阵以描述用户的出行特性;基于蒙特卡洛方法模拟EV的时空分布特性,考虑EV、DG与常规负荷的时序特性,并基于改进K-means算法构建风-光-负荷的典型运行场景;兼顾电网侧与用户侧,以综合效益、系统负荷波动以及充电耗时成本为目标,构建DG和EV充电站的多目标联合配置模型,并采用改进粒子群优化算法进行求解.结合IEEE 33节点配电网与某城区主干道路网模型进行仿真分析,结果验证了所建模型的有效性与可行性.     

计算机内存的优化及管理浅析

信息总量、网络浏览人数以及人们对网络享受需求的增加,促使着信息制作水平的提高,制作水平的提高在给人们带来了更好的视觉和听觉享受的同时,也对计算机的硬件系统提出了巨大的考验.计算机内存作为计算机硬件系统的重要组成部分,能否对内存做好合理的划分,对计算机的体验具有重要的意义.     

基于关键词设置的P2P信息检索

在分析以往结构化P2P基于单关键词分割的信息检索基础上,结合利用用户频繁出现的请求关键词的特点,提出结构化P2P中的一个基于请求关键词设置的索引框架KS-PIR。采用通过关键词联合的新特征项设置来扩充索引特征,并删节与特征项相关的索引记录表至恒定长度的方法,在检索质量提高的同时,又保证了可接受的带宽消耗,系统具有很好的扩展性。     

CuI Encapsulated within Single-Walled Carbon Nanotube Networks with High Current Carrying Capacity and Excellent Conductivity

High current carrying capacity and high conductivity are two important indicators for materials used in microscale electronics and inverters. However, it is challenging to obtain high conductivity and high current carrying capacity at the same time since high conductivity requires a weakly bonded system to provide free electrons, while high current carrying capacity requires a strongly bonded system. In this paper, CuI@SWCNT networks by filling the single-walled carbon nanotubes (SWCNTs) with CuI is ingeniously prepared. CuI@SWCNT shows good stability due to the confinement protection of SWCNTs. Through the host-guest hybridization, CuI@SWCNT networks exhibit a current carrying capacity of 2.04 × 10⁷ A cm⁻² and a conductivity of 31.67 kS m⁻¹. Their current carrying capacity and conductivity are significantly improved compared with SWCNT. The Kelvin probe force microscopy measurements show a drop of surface potential energy after SWCNT filled with CuI, indicating that the CuI guest molecules regulate the position of the Fermi level of SWCNTs, increasing carrier concentration, achieving high conductivity and high current carrying capacity. This study offers ideas and solutions for the regulation of high-performance carbon tube networks, which hold great promise for future applications in carbon-based electronic devices.