An artificial moth: Chemical source localization using a robot based neuronal model of moth optomotor anemotactic search

Robots have been used to model nature, while nature in turn can contribute to the real-world artifacts we construct. One particular domain of interest is chemical search where a number of efforts are underway to construct mobile chemical search and localization systems. We report on a project that aims at constructing such a system based on our understanding of the pheromone communication system of the moth. Based on an overview of the peripheral processing of chemical cues by the moth and its role in the organization of behavior we emphasize the multimodal aspects of chemical search, i.e. optomotor anemotactic chemical search. We present a model of this behavior that we test in combination with a novel thin metal oxide sensor and custom build mobile robots. We show that the sensor is able to detect the odor cue, ethanol, under varying flow conditions. Subsequently we show that the standard model of insect chemical search, consisting of a surge and cast phases, provides for robust search and localization performance. The same holds when it is augmented with an optomotor collision avoidance model based on the Lobula Giant Movement Detector (LGMD) neuron of the locust. We compare our results to others who have used the moth as inspiration for the construction of odor robots.     

Tunable MEMS capacitors using vertical carbon nanotube arrays grown on metal lines

In this work, tunable MEMS capacitors are realized using a vertically grown carbon nanotube array. The vertical CNT array forms an effective CNT membrane, which can be electrostatically actuated like the conventional metal plates used in MEMS capacitors. The CNT membrane is grown on titanium nitride metal lines, with a Al/Fe bi-layer as buffer layer and catalyst material respectively, using chemical vapor deposition process. Two different anchor configurations are investigated. A maximum capacitance of 400 fF and maximum tunability of 5.8% is extracted from the S-parameter measurements. Using the tunable MEMS vertical array capacitor a voltage controlled oscillator (VCO) is demonstrated showing promise for integrating CNTs for communications applications.     

Alternating chemotherapy in advanced non-small cell lung cancer: a phase II study

Fifty-three patients with advanced non-small cell lung cancer (NSCLC) were treated with alternating two-drug schedules cisplatin/vindesine and ifosfamide/mitomycin. Objective response (complete and partial response) was obtained in 31% (confidence limits 18.6-44%) of patients. The median duration of response was 26 weeks. The median survival was 25 weeks, with 24% of patients alive at 1 year. The toxicity was acceptable. The still poor antitumor activity of the chemotherapy schedules used and the lack of non-cross-resistance are factors that could explain the low antitumor activity of alternating chemotherapy.     

Selective enrichment with alpha 1A- and alpha 1B-adrenoceptor subtypes in rat brain cortical membranes

In this controlled, prospective and partially blind study two groups of patients with temporal lobe epilepsy were evaluated, respectively with good and bad prognosis. Measurements of epileptogenesis were based on frequency of seizures, and on epiletogenic electroencephalographic abnormalities obtained from scalp electrodes over the temporal lobes. The results were analysed by non-parametric analysis of variance, comparison of groups and analysis of correlation. The results indicated the temporal lobe groups were similar to at least one of the control groups in age, sex, educational and social level, therapeutic regime, age at onset and length of history of epilepsy. The quantitative measurements showed a global difference between the group of temporal lobe with bad and good prognosis, reaching statistical significance in clinical epileptogenesis, and a trend towards greater epileptogenesis on the electroencephalogram, in the same group of patients. The results indicate the experimental usefulness of some of the original measurements used in the study, but also their problems. A review of the literature is carried out.     

High strength microduplex Cu-Ni-Zn alloys

High ambient temperature tensile and fatigue strengths have been obtained in two-phase α-β Cu-Ni-Zn alloys (nickel silvers) by controlled thermomechanical working. The thermomechanical working operation involves cold working of solution annealed stock, followed by annealing in the two-phase region. This results in simultaneous recrystallization and precipitation yielding a fine-grained two phase microstructure termed “microduplex”. The high mechanical properties obtained are attributed to the fine-grained two-phase microduplex microstructure. Compositional variations studied included 10 to 40 pct Ni, 35 to 40 pct Zn, balance Cu. On the basis of ease of processing and mechanical properties, a particularly attractive composition is Cu-15Ni-37.5Zn, designated IN-836. Typical room temperature properties of IN-836 in the microduplex condition include 100 ksi (690 MN/m²) yield strength with 25 pct elongation and 40 ksi (275 MN/m²) fatigue limit (10⁷ cycles). Finally, superplastic behavior has been observed in IN-836. F. J. ANSUINI was formerly with The International Nickel Company, Inc., Paul D. Merica Laboratory, Sterling Forest, Suffern, N. Y. 10901.     

Structural analysis of populations : new statistical approach to the problem of age in Squilla mantis (Crustacea Stomatopoda)

Thirty-three male length-frequency samples are analysed first by a multivariate procedure. The evolutionary cycles are pointed out by the interpretation of the first two components. The simulation model is built up on the basis of factorial analysis. The assessment of age classes parameters (mean, standard deviation, percentage) is then carried out by the simulation of data. Their configuration with respect to the two components points out the proximity of the observed and generated samples and shows the value of the statistical model.     

Enhanced balancing Neumann–Neumann preconditioning in computational fluid and solid mechanics

In this work, we propose an enhanced implementation of balancing Neumann–Neumann (BNN) preconditioning together with a detailed numerical comparison against the balancing domain decomposition by constraints (BDDC) preconditioner. As model problems, we consider the Poisson and linear elasticity problems. On one hand, we propose a novel way to deal with singular matrices and pseudo‐inverses appearing in local solvers. It is based on a kernel identification strategy that allows us to efficiently compute the action of the pseudo‐inverse via local indefinite solvers. We further show how, identifying a minimum set of degrees of freedom to be fixed, an equivalent definite system can be solved instead, even in the elastic case. On the other hand, we propose a simple implementation of the algorithm that reduces the number of Dirichlet solvers to only one per iteration, leading to similar computational cost as additive methods. After these improvements of the BNN preconditioned conjugate gradient algorithm, we compare its performance against that of the BDDC preconditioners on a pair of large‐scale distributed‐memory platforms. The enhanced BNN method is a competitive preconditioner for three‐dimensional Poisson and elasticity problems and outperforms the BDDC method in many cases. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental validation of a hybrid computational model for selective stimulation using transverse intrafascicular multichannel electrodes

Recently a hybrid model based on the finite element method and on a compartmental biophysical representation of peripheral nerve fibers and intraneural electrodes was developed founded on experimental physiological and histological data. The model appeared to be robust when dealing with uncertainties in parameter selection. However, an experimental validation of the findings provided by the model is required to fully characterize the potential of this approach. The recruitment properties of selective nerve stimulation using transverse intrafascicular multichannel electrodes (TIME) were investigated in this work in experiments with rats and were compared to model predictions. Animal experiments were performed using the same stimulation protocol as in the computer simulations in order to rigorously validate the model predictions and understand its limitations. Two different selectivity indexes were used, and new indexes for measuring electrode performance are proposed. The model predictions are in decent agreement with experimental results both in terms of recruitment curves and selectivity values. Results show that these models can be used for extensive studies targeting electrode shape design, active sites shape, and multipolar stimulation paradigms. From a neurophysiological point of view, the topographic organization of the rat sciatic nerve, on which the model was based, has been confirmed.     

A General Interference-Aware Framework for Joint Routing and Link Scheduling in Wireless Mesh Networks

Joint design and optimization of traditionally independent problems such as routing and link scheduling have recently become one of the leading research trends in wireless mesh networks. Although technically challenging, cross-layering is, in fact, expected to bring significant benefits from the network resource exploitation standpoint to achieve high system utilization. In this article we propose a versatile framework for joint design of routing and link scheduling, introducing the notion of link activation constraints, which are related to the transceiver capability and the broadcast nature of the wireless medium. To this end, we introduce a taxonomy of wireless interference models to harmonize existing approaches presented in the literature. Finally, we evaluate the impact on network capacity of the various interference models when optimal joint routing and link scheduling are employed.     

ServiceSs: An Interoperable Programming Framework for the Cloud

The rise of virtualized and distributed infrastructures has led to new challenges to accomplish the effective use of compute resources through the design and orchestration of distributed applications. As legacy, monolithic applications are replaced with service-oriented applications, questions arise about the steps to be taken in order to maximize the usefulness of the infrastructures and to provide users with tools for the development and execution of distributed applications. One of the issues to be solved is the existence of multiple cloud solutions that are not interoperable, which forces the user to be locked to a specific provider or to continuously adapt applications. With the objective of simplifying the programmers challenges, ServiceSs provides a straightforward programming model and an execution framework that helps on abstracting applications from the actual execution environment. This paper presents how ServiceSs transparently interoperates with multiple providers implementing the appropriate interfaces to execute scientific applications on federated clouds.