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A biogeographic study of submerged aquatic vegetation (SAV) in the Pontchartrain Basin of southeastern Louisiana was conducted. These plants provide numerous essential ecosystem services. Eighteen species occurred in different salinity [...]

The fate of microzooplankton production, whether it is channeled to mesozooplankton or recycled within the microbial food web, has major implications for the oceanic carbon cycle. The aim of this study was to estimate internal predation within naturally occurring microzooplankton communities. a dilution series based on the Landry and Hasset technique was created by mixing 200-µm-screened water (used as whole water) with 5-µm-screened seawater due to the dominance of pico- and small nanoplankton at our study site. This modification of the original technique allows for gradual reduction in microzooplankton abundance and thus internal predation while maintaining sufficient phytoplankton prey levels for microzooplankton growth in diluted treatments. Microzooplankton growth and mortality rates were calculated based on the changes in abundance during 24-h incubation. In the diluted treatments, microzooplankton growth rates were significantly higher (1.21 ± 0.20 [day.sup.-1] for ciliates and 0.88 ± 0.05 [day.sup.-1] for heterotrophic dinoflagellates) compared to those in whole seawater where microzooplankton abundance remained unchanged or even declined over time. Approximately 79 % of microzooplankton production was consumed within the microzooplankton, with aloricate ciliates being the most vulnerable to predation. These findings support the assumption that trophic interactions between microzooplankton can be an important factor controlling their production and, thus, energy transfer in picoplankton-dominated pelagic ecosystems., Introduction The microbial loop conceptual model (Pomeroy 1974; Azam et al. 1983) started a debate in the scientific community on the role of microorganisms within the pelagic food web. The [...]

Author(s): Elias H. Barriga [1, 2]; Kristian Franze [3]; Guillaume Charras [1, 2]; Roberto Mayor (corresponding author) [1] Collective cell migration is essential for morphogenesis, tissue remodelling and cancer invasion [...]

Although biological cells are mostly transparent, they are phase objects that differ in shape and refractive index. Any image that is projected through layers of randomly oriented cells will normally be distorted by refraction, reflection, and scattering. Counterintuitively, the retina of the vertebrate eye is inverted with respect to its optical function and light must pass through several tissue layers before reaching the light-detecting photoreceptor cells. Here we report on the specific optical properties of glial cells present in the retina, which might contribute to optimize this apparently unfavorable situation. We investigated intact retinal tissue and individual MOiler cells, which are radial glial cells spanning the entire retinal thickness. Muller cells have an extended funnel shape, a higher refractive index than their surrounding tissue, and are oriented along the direction of light propagation. Transmission and reflection confocal microscopy of retinal tissue in vitro and in vivo showed that these cells provide a low-scattering passage for light from the retinal surface to the photoreceptor cells. Using a modified dual-beam laser trap we could also demonstrate that individual Muller cells act as optical fibers. Furthermore, their parallel array in the retina is reminiscent of fiberoptic plates used for low-distortion image transfer. Thus, Muller cells seem to mediate the image transfer through the vertebrate retina with minimal distortion and low loss. This finding elucidates a fundamental feature of the inverted retina as an optical system and ascribes a new function to glial cells. fiberoptic plate | glial cells | refractive index | light guides | optical trap

One hundred fifty years ago glial cells were discovered as a second, non-neuronal, cell type in the central nervous system. To ascribe a function to these new, enigmatic cells, it was suggested that they either glue the neurons together (the Greek word '[TEXT NOT REPRODUCIBLE IN ASCII] ' means 'glue') or provide a robust scaffold for them ('support cells'). Although both speculations are still widely accepted, they would actually require quite different mechanical cell properties, and neither one has ever been confirmed experimentally. We investigated the biomechanics of CNS tissue and acutely isolated individual neurons and glial cells from mammalian brain (hippocampus) and retina. Scanning force microscopy, bulk rheology, and optically induced deformation were used to determine their viscoelastic characteristics. We found that (i) in all CNS cells the elastic behavior dominates over the viscous behavior, (ii) in distinct cell compartments, such as soma and cell processes, the mechanical properties differ, most likely because of the unequal local distribution of cell organelles, (iii) in comparison to most other eukaryotic cells, both neurons and glial cells are very soft ('rubber elastic'), and (iv) intriguingly, glial cells are even softer than their neighboring neurons. Our results indicate that glial cells can neither serve as structural support cells (as they are too soft) nor as glue (because restoring forces are dominant) for neurons. Nevertheless, from a structural perspective they might act as soft, compliant embedding for neurons, protecting them in case of mechanical trauma, and also as a soft substrate required for neurite growth and facilitating neuronal plasticity. biomechanics | elasticity | viscosity | retina | hippocampus

In this paper, we present a discrete-time predictive control strategy for the supervision of networked dynamic systems subject to coordination constraints. Such a network paradigm is characterized by a set of spatially distributed systems, possibly dynamically coupled and connected via communication links, which need to be controlled and coordinated in order to accomplish their overall objective. The network latency is modeled abstractly as a time-varying time-delay, which is allowed to become unbounded for taking into account data-loss. The method can be specialized to deal more efficiently either with random, possibly unbounded, time-delays, such as the case over the Internet, or constant/bounded time-delays, typically encountered in space and underwater applications. An example of coordination of two autonomous vehicles under input-saturation and formation accuracy constraints is presented. Index Terms--Command governors, distributed systems, large-scale systems, networked control systems, supervision and coordination.

Cluster analyses using the Almost Perfect Scale--Revised (APS-R; R. B. Slaney, M. Mobley, J. Trippi, J. Ashby, & D. G. Johnson, 1996) yielded 3 clusters that represented adaptive perfectionists, maladaptive perfectionists, and nonperfectionists. Maladaptive perfectionist scores were strongly correlated with self-critical depression, but not dependent depression. Adaptive perfectionist scores were correlated with higher self-esteem and greater satisfaction with grade point average (GPA). It was hypothesized that satisfaction with GPA would moderate the relationship between cluster membership and GPA, and that participant gender would moderate the relationship between cluster membership and self-esteem. Neither hypothesis was supported. A comparison of the cluster groups from this sample with those in 2 previous samples (K. G. Rice & R. B. Slaney, 2002) indicated similar scores between clusters. Clinical implications and directions for future research are discussed.

A novel closed-loop model-based predictive control (MPC) strategy for input-saturated polytopic linear parameter varying (LPV) discrete-time systems is proposed. It is postulated that the plant belongs to a polytopic family of linear systems, each member of which being parameterized by the value that a parameter vector assumes in the unit simplex. Such a parameter can be measured online and used for feedback while a bound on its rate of change is known and exploited for predictions. The contribution of this note is to extend the MPC scheme presented in [5] for the restricting case of 1-step long control horizons to the general case of control horizons of arbitrary length N. This is done by suitably modifying the robust MPC scheme presented in [7] for uncertain polytopic systems. Feasibility and closed-loop stability of this strategy are proved and a numerical example is also presented in order to show how the freedom of extending the control horizon and the knowledge of the parameter is significant in order to improve the performance of the control strategy. Index Terms--Linear matrix inequalities (LMIs), linear parameter varying (LPV) systems, model predictive control (MPC), scheduling controller.

This paper proposes a novel and simple local neural classifier for the recognition of mental tasks from on-line spontaneous EEG signals. The proposed neural classifier recognizes three mental tasks from on-line spontaneous EEG signals. Correct recognition is around 70%. This modest rate is largely compensated by two properties, namely low percentage of wrong decisions (below 5%) and rapid responses (every 1/2 s). Interestingly, the neural classifier achieves this performance with a few units, normally just one per mental task. Also, since the subject and his/her personal interface learn simultaneously from each other, subjects master it rapidly (in a few days of moderate training). Finally, analysis of learned EEG patterns confirms that for a subject to operate satisfactorily a brain interface, the latter must fit the individual features of the former. Index Terms--Brain-computer interface, local neural classifier, spontaneous EEG activity.

Author(s): Marco Sciacovelli; Emanuel Gonalves; Timothy Isaac Johnson; Vincent Roberto Zecchini; Ana Sofia Henriques da Costa; Edoardo Gaude; Alizee Vercauteren Drubbel; Sebastian Julian Theobald; Sandra Riekje Abbo; Maxine Gia Binh [...]

Author(s): Marco Sciacovelli [1]; Emanuel Gonalves [2]; Timothy Isaac Johnson [1]; Vincent Roberto Zecchini [1]; Ana Sofia Henriques da Costa [1]; Edoardo Gaude [1]; Alizee Vercauteren Drubbel [1]; Sebastian Julian [...]

We outline a novel method for determining the shape of an object by use of temporal Fourier-transform analysis in dual-beam illumination speckle interferometry. The object whose shape is to be determined is rotated about an axis, and a number of frames of the image of the object motion are acquired. Temporal in-plane displacement that is due to the object rotation is related to the shape of the object and is retrieved from this large set of data by Fourier transformation. With this method one can determine the absolute height of the object with variable resolution, thereby allowing shapes of objects with large and small slopes to be determined. The theory of the method along with experimental results is presented.

We propose a new method for measuring large-object deformations by using temporal evolution of the speckles in speckle interferometry. The principle of the method is that by deforming the object continuously, one obtains fluctuations in the intensity of the speckle. A large number of flames of the object motion are collected to be analyzed later. The phase data for whole-object deformation are then retrieved by inverse Fourier transformation of a filtered spectrum obtained by Fourier transformation of the signal. With this method one is capable of measuring deformations of more than 100 [[micro]meter], which is not possible using conventional electronic speckle pattern interferometry. We discuss the underlying principle of the method and the results of the experiments. Some nondestructive testing results are also presented.

In this paper we discuss an oblique incidence and observation electronic speckle-pattern interferometer, in which we use an anamorphic prism in front of the object. A collimated beam traveling through the prism is partly reflected at the base of the prism. The reflected light is the reference beam and the transmitted light illuminates the diffuse object, thereby generating the object beam. In this scheme the object and the reference beams are collinear. A new scheme that uses two prisms and permits phase stepping is also presented. Key words: Speckle interferometry, electronic speckle-pattern interferometer.

Family adaptation to type 2 diabetes management after nutrition education was studied as part of a 2.5-year ethnography. Data analysis included descriptive data (observations, transcribed audio recordings, written field notes) [...]