The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform

Olav Vadstein - One of the best experts on this subject based on the ideXlab platform.

  • Food size selectivity of Artemia franciscana at three developmental stages
    Journal of Plankton Research, 1999
    Co-Authors: Pavlos Makridis, Olav Vadstein
    Abstract:

    Food size selectivity was examined in Artemia franciscana metanauplii at three different developmental stages. Clearance rates were determined in short-term experiments either by measuring the decrease in concentration of live particles and plastic beads, or by measuring the radioactivity accumulated in animals that grazed 14 C-labelled live particles. The Maximum Clearance rate of A.franciscana metanauplii increased during development and was measured at 50-63 µl ind. -1 h -1 , 254 µl ind. -1 h -1 and 1.48-2.10 ml ind. -1 h -1 in 2-, 4- and 7-day-old metanauplii, respectively. A preference for particles with a diameter of 4-8 µm was observed at all three developmental stages. The ability of A.franciscana metanauplii to graze bacterial particles was also demonstrated, although the efficiency in grazing such small particles was low compared to microalgae (28, 20 and 9% of the Maximum Clearance rate in 2-, 4- and 7-day-old metanauplii, respectively). Electron microscopy showed that the inter-setular distance in antennae and thoracopods was 0.20 ± 0.07, 0.16 ± 0.05 and 0.18 ± 0.04 µm in 2-, 4- and 7-day-old metanauplii, respectively, and accordingly independent of stage.

Karel Šimek - One of the best experts on this subject based on the ideXlab platform.

  • Functional response and particle size selection of Halteria cf. grandinella, a common freshwater oligotrichous ciliate
    Aquatic Microbial Ecology, 2000
    Co-Authors: Klaus Jürgens, Karel Šimek
    Abstract:

    In laboratory experiments, we studied the growth and feeding characteristics of Halte- ria cf. grandinella, a common and widespread oligotrichous ciliate in freshwater plankton. Particle- size-dependent feeding rates were measured with fluorescent latex micropheres (0.22 to 4.23 µm diameter) and natural food organisms (bacteria, Synechococcus sp., Chlorella minutissima) in short- term feeding experiments. H. cf. grandinella ingested all but the smallest (0.22 µm) particles offered and demonstrated a concentration dependent type-2 functional response. Maximum Clearance rates were obtained with 2.76 µm latex beads (0.6 µl h -1 ). Clearance rates declined for smaller and larger particle sizes but even with the suboptimal size classes, 0.47 and 1 µm, high maximal ingestion rates were measured (19 and 13 beads ciliate -1 min -1 , respectively). The Maximum Clearance rates for bac- teria and algae were close to those of similar sized latex beads, and no discrimination of particles based on properties other than size could be detected. The physiological state of the ciliates did not seem to have an impact on the relative pattern of the particle-size-dependent functional response curves, but the absolute feeding rates decreased nearly 10-fold after prolonged starvation. The experiments demonstrated that this small filter-feeding ciliate is an omnivorous species which is able to efficiently exploit the planktonic prey size spectrum from 0.5 to 5 µm, covering heterotrophic and autotrophic pico- and nanoplankton in the diet.

B.k. Sapra - One of the best experts on this subject based on the ideXlab platform.

  • a walk in type calibration chamber facility for 222rn measuring devices and inter comparison exercises
    Radiation Protection Dosimetry, 2019
    Co-Authors: S. Trilochana, H. M. Somashekarappa, M.p. Mohan, Srinivas S. Kamath, B. K. Sahoo, J.j. Gaware, Sudeep K Kumara, Rashmi S Nayak, Renita Shiny Dsouza, B.k. Sapra
    Abstract:

    A walk-in type 222Rn calibration chamber of volume 22.7 m3, which has traceability to international standards, is established at the Centre for Advanced Research in Environmental Radioactivity, Mangalore University, India. It has a human-machine interface communication system, a programmable logic controller and sensor feedback circuit for controlling and data acquisition of relative humidity (RH) and temperature (T). An innovative method for the generation of desired 222Rn concentration (a few hundred Bq m-3 up to about 36 kBq m-3) using soil gas as a source was adopted. Leak rates of 222Rn from the chamber for the mixing fan ON and OFF conditions were determined to be 0.0011 and 0.00018 h-1 respectively. With the exhaust system fully turned on, the Maximum Clearance rate of the chamber was 0.58 ± 0.07 h-1. Excellent spatial uniformity in 222Rn concentration in the chamber was confirmed (with a mean value of relative standard deviation < 12%) through measurements at 23 locations using CR-39 film-based passive devices. Demonstration of calibration applications was performed using charcoal canister and PicoRad vials as the 222Rn adsorption devices. The study shows that gamma spectrometry is a convenient alternative approach to liquid scintillation analysis of PicoRad vials for 222Rn measurement.

  • A WALK-IN TYPE CALIBRATION CHAMBER FACILITY FOR 222Rn MEASURING DEVICES AND INTER-COMPARISON EXERCISES
    Radiation protection dosimetry, 2019
    Co-Authors: S. Trilochana, H. M. Somashekarappa, K. Sudeep Kumara, M.p. Mohan, S. Rashmi Nayak, Renita Shiny D’souza, Srinivas S. Kamath, B. K. Sahoo, J.j. Gaware, B.k. Sapra
    Abstract:

    A walk-in type 222Rn calibration chamber of volume 22.7 m3, which has traceability to international standards, is established at the Centre for Advanced Research in Environmental Radioactivity, Mangalore University, India. It has a human-machine interface communication system, a programmable logic controller and sensor feedback circuit for controlling and data acquisition of relative humidity (RH) and temperature (T). An innovative method for the generation of desired 222Rn concentration (a few hundred Bq m-3 up to about 36 kBq m-3) using soil gas as a source was adopted. Leak rates of 222Rn from the chamber for the mixing fan ON and OFF conditions were determined to be 0.0011 and 0.00018 h-1 respectively. With the exhaust system fully turned on, the Maximum Clearance rate of the chamber was 0.58 ± 0.07 h-1. Excellent spatial uniformity in 222Rn concentration in the chamber was confirmed (with a mean value of relative standard deviation

Wael Suleiman - One of the best experts on this subject based on the ideXlab platform.

  • On Bisection Continuous Collision Checking Method: Spherical Joints and Minimum Distance to Obstacles
    2018
    Co-Authors: Sonny Tarbouriech, Wael Suleiman
    Abstract:

    — In this paper, we adapt the Continuous Collision Detection (CCD) method proposed in [1] to efficiently handle the case of spherical and two revolute joints, this kind of joints is very common in modern robotic systems. The new formulations provide more tight motion bounds, thus increase the success rate of checking collision-free paths. We also propose an extension to get the minimum distance to obstacles along a path, this information is primordial as it allows sampling-based motion planning techniques to sort collision-free paths according to their minimum Clearance. We have integrated our implementation into a sampling-based motion planning technique and validated it through simulation and on the real Baxter research robot. The experiments revealed that the method not only does not miss any collision between the robot and the obstacles, but also the minimum distance extension provides the path with the Maximum Clearance at no additional computational cost.

  • ICRA - On Bisection Continuous Collision Checking Method: Spherical Joints and Minimum Distance to Obstacles
    2018 IEEE International Conference on Robotics and Automation (ICRA), 2018
    Co-Authors: Sonny Tarbouriech, Wael Suleiman
    Abstract:

    In this paper, we adapt the Continuous Collision Detection (CCD) method proposed in [1] to efficiently handle the case of spherical and two revolute joints, this kind of joints is very common in modern robotic systems. The new formulations provide more tight motion bounds, thus increase the success rate of checking collision-free paths. We also propose an extension to get the minimum distance to obstacles along a path, this information is primordial as it allows sampling-based motion planning techniques to sort collision-free paths according to their minimum Clearance. We have integrated our implementation into a sampling-based motion planning technique and validated it through simulation and on the real Baxter research robot. The experiments revealed that the method not only does not miss any collision between the robot and the obstacles, but also the minimum distance extension provides the path with the Maximum Clearance at no additional computational cost.

P. Nagaraj - One of the best experts on this subject based on the ideXlab platform.

  • Determine the Properties of Objects to Maximum Clearance
    Data mining and knowledge engineering, 2010
    Co-Authors: K. Venkatesh Sharma, K.hanumanth Rao, P. Nagaraj
    Abstract:

    In recent years, there has been significant interest in the development of ranking functions and efficient top-k retrieval algorithms to help users in ad hoc search and retrieval in databases (e.g., buyers searching for products in a catalog). We introduce a complementary problem: How to guide a seller in selecting the best attributes of a new tuple (e.g., a new product) to highlight so that it stands out in the crowd of existing competitive products and is widely visible to the pool of potential buyers. We develop several formulations of this problem. Although the problems are NP-complete, we give several exact and approximation algorithms that work well in practice. One type of exact algorithms is based on Integer Programming (IP) formulations of the problems. Another class of exact methods is based on maximal frequent item set mining algorithms. The approximation algorithms are based on greedy heuristics. A detailed performance study illustrates the benefits of our methods on real and synthetic data.