Detection in fixed and random noise in foveal and parafoveal vision explained by template learning

Foveal and parafoveal contrast detection thresholds for Gabor and checkerboard targets were measured in white noise by means of a two-interval forced-choice paradigm. Two white-noise conditions were used: fixed and twin. In the fixed noise condition a single noise sample was presented in both intervals of all the trials. In the twin noise condition the same noise sample was used in the two intervals of a trial, but a new sample was generated for each trial. Fixed noise conditions usually resulted in lower thresholds than twin noise. Template learning models are presented that attribute this advantage of fixed over twin noise either to fixed memory templates' reducing uncertainty by incorporation of the noise or to the introduction, by the learning process itself, of more variability in the twin noise condition. Quantitative predictions of the template learning process show that it contributes to the accelerating nonlinear increase in performance with signal amplitude at low signal-to-noise ratios.     

Shielded gradients. And the general solution to the near field problem of electromagnet design

The development of actively shielded gradients introduced the concept of surface distributed conductors for the production of electromagnetic fields. This represented the most significant step in electromagnetic coil design since the discovery of the electromagnetic field equations a century earlier. Further, the associated recognition of the Biot-Savart equation as the convolution of the current distribution function with the inverse square spatial dispersion, permits a solution of the general near field problem with implications for other scientific fields that have yet to be explored.     

Quantatitive assessment of enzyme immobilization capacity in porous silicon

Immobilized enzyme systems are important in a broad range of applications, from biological sensing to the industrial-scale biocatalytic synthesis of chiral products. We demonstrate the ability to systematically vary and quantitatively assess the immobilization capacity of porous silicon thin films for the enzyme glutathione-S-transferase in a manner predicted by a simple geometric model of the porous silicon matrix. We find that the immobilization capacity quantatitively correlates with systematic changes in the device thickness. These results are significant since, despite the wide range over which porous silicon morphology and surface area can be varied, few attempts have been made to systematically characterize surface binding capacity. Our findings suggest that porous silicon can be an ideal matrix, where immobilization of a predictable quantity of biological material is desired.     

Aqueous oxidation of dimethyl phthalate in a Fe(VI)-TiO(2)-UV reaction system

The application of a combined ferrate-photocatalysis process for the aqueous degradation of dimethyl phthalate (DMP) has been studied. The behaviour of the Fe(VI)-TiO(2)-UV process at pH 9 in the presence and absence of dissolved oxygen (DO) has been compared and significant differences have been found. In comparative tests under N(2) and O(2) bubbling, the chemical reduction rate of ferrate as conduction band electron acceptor was similar, but the resulting degradation of DMP was substantially lower in the presence of oxygen. It is speculated that the presence of oxygen leads to the formation of Fe-O-(organic) complex species that adsorb to, and deactivate, the surface of the photocatalyst. The presence of surface-adsorbed complex species was indicated by FTIR spectroscopy and a reduced TiO(2) adsorption capacity for DMP. In the presence of typical environmental levels of DO ( approximately 9mgL(-1)), the Fe(VI)-TiO(2)-UV process achieved a modest degree of DMP degradation (40% in 120min).     

Quantification of heart fatty acid binding protein as a biomarker for drug-induced cardiac and musculoskeletal necroses

Heart fatty acid binding protein (Fabp3) is a cytosolic protein expressed primarily in heart, and to a lesser extent in skeletal muscle, brain, and kidney. During myocardial injury, the Fabp3 level in serum is elevated rapidly, making it an ideal early marker for myocardial infarction. In this study, an MS‐based selected reaction monitoring method (LC‐SRM) was developed for quantifying Fabp3 in rat serum. Fabp3 was enriched first through an immobilized antibody, and the protein was digested on beads directly. A marker peptide of Fabp3 was quantified using LC‐SRM with a stable isotope‐labeled peptide standard. For six quality control samples with Fabp3 ranging from 0.256 to 25 ng, the average recovery following the procedure was about 73%, and the precision (%CV) between replicates was less than 7%. The Fabp3 concentrations in rat serum peaked 1 h after isoproterenol treatment, and returned to baseline levels 24 h after the dose. Elevated Fabp3 levels were also detected in rats administered with a PPAR α/δ agonist, which has shown to cause skeletal muscle necrosis. Fabp3 can be used as a biomarker for both cardiac and skeletal necroses. The cross‐validation of the LC‐SRM method with an existing ELISA method is described.     

钻石之恋——ANC奥尼摄像头

近日,ANC奥尼推出了人体工学钛金软管的钻石之恋摄像头。在此,笔者将这款名为“钻石之恋”的摄像头深入剖析给摄像头爱好者们。ANC奥尼钻石之恋摄像头具有5     

WinXP透明体验

“你跟着我已经有些年头了，天天见你这一成不变的容貌，就算是天仙，也难免审美疲劳了。既然你的娘家——微软，不步给你置办点行头，就休怪我要‘辣手摧花’”。半个月前某天的晚上8点，我面对WinXP数年来毫无变化的界面主题，一咬牙按下了WindowBlinds的安装键。     

Redistribution of synaptic efficacy supports stable pattern learning in neural networks

Markram and Tsodyks, by showing that the elevated synaptic efficacy observed with single-pulse long-term potentiation (LTP) measurements disappears with higher-frequency test pulses, have critically challenged the conventional assumption that LTP reflects a general gain increase. This observed change in frequency dependence during synaptic potentiation is called redistribution of synaptic efficacy (RSE). RSE is here seen as the local realization of a global design principle in a neural network for pattern coding. The underlying computational model posits an adaptive threshold rather than a multiplicative weight as the elementary unit of long-term memory. A distributed instar learning law allows thresholds to increase only monotonically, but adaptation has a bidirectional effect on the model postsynaptic potential. At each synapse, threshold increases implement pattern selectivity via a frequency-dependent signal component, while a complementary frequency-independent component nonspecifically strengthens the path. This synaptic balance produces changes in frequency dependence that are robustly similar to those observed by Markram and Tsodyks. The network design therefore suggests a functional purpose for RSE, which, by helping to bound total memory change, supports a distributed coding scheme that is stable with fast as well as slow learning. Multiplicative weights have served as a cornerstone for models of physiological data and neural systems for decades. Although the model discussed here does not implement detailed physiology of synaptic transmission, its new learning laws operate in a network architecture that suggests how recently discovered synaptic computations such as RSE may help produce new network capabilities such as learning that is fast, stable, and distributed.     

时尚轻薄的酷睿2——海尔W12

海尔做为知名家电企业,进入笔记本市场已经很长时间了。从其陆续推出的产品来看,主要集中在时尚方面,今天我们要说的这款海尔W12,走的就是轻薄时尚路线。