Virtual audio reproduced in a headrest

When virtual audio reproduction is simultaneously required in many seats, such as in aircraft or cinemas, it may be convenient to use loudspeakers mounted inside each seat's headrest. In this preliminary study, the feasibility of virtual audio reproduction in the headrest of a single seat is explored using an inversion technique to compensate for crosstalk and the synthesis of head related transfer functions. Although large changes in the magnitude of the signals reproduced at the listener's ears are observed as the listener moves their head within the headrest, informal listening tests indicate that the reproduced acoustic images are surprisingly stable in about an eighth of an arc either side of the loudspeaker positions. Not surprisingly, frontal images are more difficult to reproduce with headrest loudspeakers

First-occurrence time of high-level crossings in a continuous random process

Statistical probability distribution of first occurrence and first recurrence times of given level crossing in continuous random proces

Effect of spacewise variations in a random load field on the response of a linear system

Effect of spacewise variations in random load field on response of linear system - statistical mechanic

Information flow through a model of the C. elegans klinotaxis circuit

Understanding how information about external stimuli is transformed into behavior is one of the central goals of neuroscience. Here we characterize the information flow through a complete sensorimotor circuit: from stimulus, to sensory neurons, to interneurons, to motor neurons, to muscles, to motion. Specifically, we apply a recently developed framework for quantifying information flow to a previously published ensemble of models of salt klinotaxis in the nematode worm C. elegans. The models are grounded in the neuroanatomy and currently known neurophysiology of the worm. The unknown model parameters were optimized to reproduce the worm's behavior. Information flow analysis reveals several key principles underlying how the models operate: (1) Interneuron class AIY is responsible for integrating information about positive and negative changes in concentration, and exhibits a strong left/right information asymmetry. (2) Gap junctions play a crucial role in the transfer of information responsible for the information symmetry observed in interneuron class AIZ. (3) Neck motor neuron class SMB implements an information gating mechanism that underlies the circuit's state-dependent response. (4) The neck carries non-uniform distribution about changes in concentration. Thus, not all directions of movement are equally informative. Each of these findings corresponds to an experimental prediction that could be tested in the worm to greatly refine our understanding of the neural circuit underlying klinotaxis. Information flow analysis also allows us to explore how information flow relates to underlying electrophysiology. Despite large variations in the neural parameters of individual circuits, the overall information flow architecture circuit is remarkably consistent across the ensemble, suggesting that information flow analysis captures general principles of operation for the klinotaxis circuit

Names of fungal species with the same epithet applied to different morphs: how to treat them

The abolition of the separate naming of different morphs of the same fungal species in 2011 will inevitably result in many name changes in some genera. The working practices commended here are intended to minimize one category of these changes, that which can arise as a consequence of an author using the epithet of an asexual morph when describing the sexual morph of the same species. We consider that name proposed for the sexual morph in such cases should be treated as a formal error for a new combination and not as a new species, and so be corrected. This is interpreted as applying even where the author indicated that a new species was being described and designated a type. We argue that those formalities were a result of the requirements of the rules then in force, as the author recognized that a morph of a named species was being described, and not a new hitherto unnamed species was being reported - but was barred from making a new combination so used the same epithet for the new morph name instead. Where a type with the sexual morph was designated for the sexual morph, under this interpretation that no longer has nomenclatural status, the type being that of the basionym. The material for the sexual morph indicated as a type, would be available for designation as an epitype, though a modern sequenced sample with both sexual and asexual morphs would be more informative as an epitype in many cases. A proposal to regularize the working practice commended here, and also the converse situation where the sexual morph typified name is the earlier, will be made to the 2017 Shenzhen Congress

The hyaluronan-binding serine protease from human plasma cleaves HMW and LMW kininogen and releases bradykinin

The influence of the hyaluronanbinding protease (PHBSP), a plasma enzyme with FVII- and pro-urokinase-activating potency, on components of the contact phase (kallikrein/kinin) system was investigated. No activation or cleavage of the proenzymes involved in the contact phase system was observed. The procofactor high molecular weight kininogen (HK), however, was cleaved in vitro by PHBSP in the absence of any charged surface, releasing the activated cofactor and the vasoactive nonapeptide bradykinin. Glycosoaminoglycans strongly enhanced the reaction. The cleavage was comparable to that of plasma kallikrein, but clearly different from that of coagulation factor FXIa. Upon extended incubation with PHBSP, the light chain was further processed, partially removing about 60 amino acid residues from the Nterminus of domain D5 of the light chain. These cleavage site(s) were distinct from plasma kallikrein or FXIa cleavage sites. PHBSP and, more interestingly, also plasma kallikrein could cleave low molecular weight kininogen in vitro, indicating that domains D5(H) and D6(H) are no prerequisite for kininogen cleavage. PHBSP was also able to release bradykinin from HK in plasma where the pro-cofactor circulates predominantly in complex with plasma kallikrein or FXI. In conclusion, PHBSP represents a novel kininogen-cleaving and bradykinin-releasing enzyme in plasma that shares significant catalytic similarities with plasma kallikrein. Since they are structurally unrelated in their heavy chains (propeptide), their similar in vivo catalytic activities might be directed at distinct sites where PHBSP could induce processes that are related to the kallikrein/kinin system

Structure and function of natural sulphide-oxidizing microbial mats under dynamic input of light and chemical energy

We studied the interaction between phototrophic and chemolithoautotrophic sulphide-oxidizing microorganisms in natural microbial mats forming in sulphidic streams. The structure of these mats varied between two end-members: one characterized by a layer dominated by large sulphur-oxidizing bacteria (SOB; mostly Beggiatoa-like) on top of a cyanobacterial layer (B/C mats) and the other with an inverted structure (C/B mats). C/B mats formed where the availability of oxygen from the water column was limited (<5 mu M). Aerobic chemolithotrophic activity of the SOB depended entirely on oxygen produced locally by cyanobacteria during high light conditions. In contrast, B/C mats formed at locations where oxygen in the water column was comparatively abundant (445 mu M) and continuously present. Here SOB were independent of the photosynthetic activity of cyanobacteria and outcompeted the cyanobacteria in the uppermost layer of the mat where energy sources for both functional groups were concentrated. Outcompetition of photosynthetic microbes in the presence of light was facilitated by the decoupling of aerobic chemolithotrophy and oxygenic phototrophy. Remarkably, the B/C mats conserved much less energy than the C/B mats, although similar amounts of light and chemical energy were available. Thus ecosystems do not necessarily develop towards optimal energy usage. Our data suggest that, when two independent sources of energy are available, the structure and activity of microbial communities is primarily determined by the continuous rather than the intermittent energy source, even if the time-integrated energy flux of the intermittent energy source is greater