Discovery of novel intermediate forms redefines the fungal tree of life

Fungi are the principal degraders of biomass in terrestrial ecosystems and establish important interactions with plants and animals. However, our current understanding of fungal evolutionary diversity is incomplete and is based upon species amenable to growth in culture. These culturable fungi are typically yeast or filamentous forms, bound by a rigid cell wall rich in chitin. Evolution of this body plan was thought critical for the success of the Fungi, enabling them to adapt to heterogeneous habitats and live by osmotrophy: extracellular digestion followed by nutrient uptake. Here we investigate the ecology and cell biology of a previously undescribed and highly diverse form of eukaryotic life that branches with the Fungi, using environmental DNA analyses combined with fluorescent detection via DNA probes. This clade is present in numerous ecosystems including soil, freshwater and aquatic sediments. Phylogenetic analyses using multiple ribosomal RNA genes place this clade with Rozella, the putative primary branch of the fungal kingdom. Tyramide signal amplification coupled with group-specific fluorescence in situ hybridization reveals that the target cells are small eukaryotes of 3-5?μm in length, capable of forming a microtubule-based flagellum. Co-staining with cell wall markers demonstrates that representatives from the clade do not produce a chitin-rich cell wall during any of the life cycle stages observed and therefore do not conform to the standard fungal body plan. We name this highly diverse clade the cryptomycota in anticipation of formal classification.     

Using neural networks for recognizing matching among terms

Some experiments have been carried out in order to identify a class of neural networks that would receive as inputs (n+1) terms {T_l,…T_n.T} and would suggest which T_is are matched by a subterm of T, with varying n. A particular net was found that is able to solve the problem for n=1 with a good degree of accuracy. It is shown that the performance of the net is relatively independent of the size of the training set while it is strongly related to the length of the term T. This net was then used as building block for larger nets that were applied to solve the problem for higher values of n. Results of testing such nets are presented.     

Miniature eye movements enhance fine spatial detail

Our eyes are constantly in motion. Even during visual fixation, small eye movements continually jitter the location of gaze. It is known that visual percepts tend to fade when retinal image motion is eliminated in the laboratory. However, it has long been debated whether, during natural viewing, fixational eye movements have functions in addition to preventing the visual scene from fading. In this study, we analysed the influence in humans of fixational eye movements on the discrimination of gratings masked by noise that has a power spectrum similar to that of natural images. Using a new method of retinal image stabilization, we selectively eliminated the motion of the retinal image that normally occurs during the intersaccadic intervals of visual fixation. Here we show that fixational eye movements improve discrimination of high spatial frequency stimuli, but not of low spatial frequency stimuli. This improvement originates from the temporal modulations introduced by fixational eye movements in the visual input to the retina, which emphasize the high spatial frequency harmonics of the stimulus. In a natural visual world dominated by low spatial frequencies, fixational eye movements appear to constitute an effective sampling strategy by which the visual system enhances the processing of spatial detail.     

Bipolar supercurrent in graphene

Graphene--a recently discovered form of graphite only one atomic layer thick--constitutes a new model system in condensed matter physics, because it is the first material in which charge carriers behave as massless chiral relativistic particles. The anomalous quantization of the Hall conductance, which is now understood theoretically, is one of the experimental signatures of the peculiar transport properties of relativistic electrons in graphene. Other unusual phenomena, like the finite conductivity of order 4e(2)/h (where e is the electron charge and h is Planck's constant) at the charge neutrality (or Dirac) point, have come as a surprise and remain to be explained. Here we experimentally study the Josephson effect in mesoscopic junctions consisting of a graphene layer contacted by two closely spaced superconducting electrodes. The charge density in the graphene layer can be controlled by means of a gate electrode. We observe a supercurrent that, depending on the gate voltage, is carried by either electrons in the conduction band or by holes in the valence band. More importantly, we find that not only the normal state conductance of graphene is finite, but also a finite supercurrent can flow at zero charge density. Our observations shed light on the special role of time reversal symmetry in graphene, and demonstrate phase coherent electronic transport at the Dirac point.     

一种高灵敏性钢包下渣检测装置的研究与应用

在钢水浇铸过程中,需要严格控制钢包到中间包的钢渣量.通过对国外多种下渣检测技术的调研分析及国内多个钢厂的现场试验,提出了一种高灵敏性的钢包下渣检测装置,从硬件上改变了传统采集的单一检测方式,同时在软件上简化了下渣特征提取的算法.通过在现场使用,取得了较好的检测效果,有效控制了进入中间包内的钢渣量,提高了钢厂的经济效益.