Scan Science and Technology

Contact Leading Edge Experts & Companies

14,000,000 Leading Edge Experts on the ideXlab platform

14,000,000

Leading Edge Experts

on the ideXlab platform

Model System

The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Model System - Free Register to Access Experts & Abstracts

Eleftherios Mylonakis - One of the best experts on this subject based on the ideXlab platform.

  • Galleria mellonella as a Model System to studyAcinetobacter baumanniipathogenesis and therapeutics.
    Antimicrob Agents Chemother, 2009
    Co-Authors: Anton Y. Peleg, Solange Jara, D Monga, George M Eliopoulos, Robert C Moellering, Eleftherios Mylonakis
    Abstract:

    Nonmammalian Model Systems of infection such as Galleria mellonella (caterpillars of the greater wax moth) have significant logistical and ethical advantages over mammalian Models. In this study, we utilize G. mellonella caterpillars to study host-pathogen interactions with the gram-negative organism Acinetobacter baumannii and determine the utility of this infection Model to study antibacterial efficacy. After infecting G. mellonella caterpillars with a reference A. baumannii strain, we observed that the rate of G. mellonella killing was dependent on the infection inoculum and the incubation temperature postinfection, with greater killing at 37 degrees C than at 30 degrees C (P = 0.01). A. baumannii strains caused greater killing than the less-pathogenic species Acinetobacter baylyi and Acinetobacter lwoffii (P < 0.001). Community-acquired A. baumannii caused greater killing than a reference hospital-acquired strain (P < 0.01). Reduced levels of production of the quorum-sensing molecule 3-hydroxy-C(12)-homoserine lactone caused no change in A. baumannii virulence against G. mellonella. Treatment of a lethal A. baumannii infection with antibiotics that had in vitro activity against the infecting A. baumannii strain significantly prolonged the survival of G. mellonella caterpillars compared with treatment with antibiotics to which the bacteria were resistant. G. mellonella is a relatively simple, nonmammalian Model System that can be used to facilitate the in vivo study of host-pathogen interactions in A. baumannii and the efficacy of antibacterial agents.

  • Galleria mellonella as a Model System to study Cryptococcus neoformans pathogenesis
    Infection and Immunity, 2005
    Co-Authors: Eleftherios Mylonakis, Roberto Moreno, Joseph B. El Khoury, Alexander Idnurm, Frederick M Ausubel, Joseph Heitman, Stephen B Calderwood, Andrew Diener
    Abstract:

    Evaluation of Cryptococcus neoformans virulence in a number of nonmammalian hosts suggests that C. neoformans is a nonspecific pathogen. We used the killing of Galleria mellonella (the greater wax moth) caterpillar by C. neoformans to develop an invertebrate host Model System that can be used to study cryptococcal virulence, host immune responses to infection, and the effects of antifungal compounds. All varieties of C. neoformans killed G. mellonella. After injection into the insect hemocoel, C. neoformans proliferated and, despite successful phagocytosis by host hemocytes, killed caterpillars both at 37 degrees C and 30 degrees C. The rate and extent of killing depended on the cryptococcal strain and the number of fungal cells injected. The sequenced C. neoformans clinical strain H99 was the most virulent of the strains tested and killed caterpillars with inocula as low as 20 CFU/caterpillar. Several C. neoformans genes previously shown to be involved in mammalian virulence (CAP59, GPA1, RAS1, and PKA1) also played a role in G. mellonella killing. Combination antifungal therapy (amphotericin B plus flucytosine) administered before or after inoculation was more effective than monotherapy in prolonging survival and in decreasing the tissue burden of cryptococci in the hemocoel. The G. mellonella-C. neoformans pathogenicity Model may be a substitute for mammalian Models of infection with C. neoformans and may facilitate the in vivo study of fungal virulence and efficacy of antifungal therapies.

John L. Bowman - One of the best experts on this subject based on the ideXlab platform.

  • Development and Application of the SACSIM Activity-Based Model System
    2020
    Co-Authors: Mark Bradley, John L. Bowman, Bruce Griesenbeck
    Abstract:

    This paper presents the latest information about the activity-based regional travel forecasting Model System being implemented for the Sacramento, California, Council of Governments. The SACSIM Model System represents travel in the context of an integrated disaggregate econometric Model of each resident’s full-day activity and travel schedule. Sensitivity to neighborhood scale is enhanced through disaggregation of the Modeled outcomes in three key dimensions: purpose, time, and space. Each activity episode is associated with one of seven specific purposes, and with a particular parcel location at which it occurs. The beginning and ending times of all activity and travel episodes are identified within a specific 30-minute time period. The Model System has been calibrated and tested for a base year of 2000 and for forecasts to the years 2005 and 2032. The paper summarizes the Model System structure, explains the integration with the traffic assignment Model, and discusses issues with preparing input data for such a Model System.

  • activity based disaggregate travel demand Model System with activity schedules
    Transportation Research Part A-policy and Practice, 2001
    Co-Authors: John L. Bowman, Moshe Benakiva
    Abstract:

    We present an integrated activity-based discrete choice Model System of an individual's activity and travel schedule, for forecasting urban passenger travel demand. A prototype demonstrates the System concept using a 1991 Boston travel survey and transportation System level of service data. The Model System represents a person's choice of activities and associated travel as an activity pattern overarching a set of tours. A tour is defined as the travel from home to one or more activity locations and back home again. The activity pattern consists of important decisions that provide overall structure for the day's activities and travel. In the prototype the activity pattern includes (a) the primary - most important - activity of the day, with one alternative being to remain at home for all the day's activities; (b) the type of tour for the primary activity, including the number, purpose and sequence of activity stops; and (c) the number and purpose of secondary - additional - tours. Tour Models include the choice of time of day, destination and mode of travel, and are conditioned by the choice of activity pattern. The choice of activity pattern is influenced by the expected maximum utility derived from the available tour alternatives.

  • Travel demand Model System for the information era
    Transportation, 1996
    Co-Authors: Moshe Ben-akivai, John L. Bowman, Dinesh Gopinath
    Abstract:

    The emergence of new information technologies and recent advances in existing technologies have provided new dimensions for travel demand decisions. In this paper we propose a comprehensive travel demand Modeling framework to identify and Model the urban development decisions of firms and developers and the mobility, activity and travel decisions of individuals and households, and to develop a System of Models that can be used by decision makers and planners to evaluate the effects of changes in the transportation System and development of information technologies (e.g. various tele-commuting, tele-services and Intelligent Transportation Systems). The implementation of an operational Model System based on this framework is envisioned as an incremental process starting with the current “best practice” of disaggregate travel demand Model Systems. To this end, we present an activity-based Model System as the first stage in the development of an operational Model System.

Moshe Benakiva - One of the best experts on this subject based on the ideXlab platform.

  • activity based disaggregate travel demand Model System with activity schedules
    Transportation Research Part A-policy and Practice, 2001
    Co-Authors: John L. Bowman, Moshe Benakiva
    Abstract:

    We present an integrated activity-based discrete choice Model System of an individual's activity and travel schedule, for forecasting urban passenger travel demand. A prototype demonstrates the System concept using a 1991 Boston travel survey and transportation System level of service data. The Model System represents a person's choice of activities and associated travel as an activity pattern overarching a set of tours. A tour is defined as the travel from home to one or more activity locations and back home again. The activity pattern consists of important decisions that provide overall structure for the day's activities and travel. In the prototype the activity pattern includes (a) the primary - most important - activity of the day, with one alternative being to remain at home for all the day's activities; (b) the type of tour for the primary activity, including the number, purpose and sequence of activity stops; and (c) the number and purpose of secondary - additional - tours. Tour Models include the choice of time of day, destination and mode of travel, and are conditioned by the choice of activity pattern. The choice of activity pattern is influenced by the expected maximum utility derived from the available tour alternatives.

W. Satoh - One of the best experts on this subject based on the ideXlab platform.

  • Transmission loss of prospective power transmission Model System integrated under superconducting environment
    IEEE Transactions on Applied Superconductivity, 1997
    Co-Authors: Hirotaka Shimizu, Toshiro Matsumura, Yue Jin Tang, Yukio Kito, Takeyoshi Kato, Yasunobu Yokomizu, K. Satoh, W. Satoh
    Abstract:

    The authors have developed a "prospective power transmission Model System integrated under superconducting environment", abbreviated to PROMISE, with a transmission capability of 6 kV-1000 kVA. The PROMISE consists of a superconducting transformer (SE-Tr), a superconducting fault current limiter (SC-FCL) and a superconducting power cable (SC-power cable). These components are cooled down at liquid helium (LHe) temperature, 4.2 K, in a cryostat with a volume of 854 l. The paper indicates a computing procedure of a total heat leak 4.2 K into the cryostat and discusses transmission losses of the superconducting electric power System, which evaporate the LHe. P/sub leak/, core loss P/sub core/ of the SC-Tr and AC loss P/sub ac/ in the superconductor were measured in the PROMISE to be 43 W, 180 W and 50 W, respectively. The measured P/sub leak/ agreed with the theoretical one. In the superconducting power transmission System, the power to operate the refrigerator for liquefying the evaporated helium must be taken as the transmission loss. If the penalty factor was 500, the transmission loss was estimated to be 137 kW and took 13.7% of the transmission capability in the PROMISE.

  • Development of the prospective power transmission Model System integrated under superconducting environment-PROMISE
    IEEE Transactions on Applied Superconductivity, 1995
    Co-Authors: Yue Jin Tang, Toshiro Matsumura, Yukio Kito, Naoki Hayakawa, Hitoshi Okubo, Takeyoshi Kato, Yasunobu Yokomizu, K. Miyake, T. Kumano, W. Satoh
    Abstract:

    A "prospective power transmission Model System integrated under superconducting environment", abbreviated to PROMISE, has been constructed to verify the technical possibility of superconducting power transmission for the next generation. PROMISE is composed of a superconducting transformer, a superconducting fault current limiter and superconducting power cable of length 5 m. These three superconducting apparatus are enclosed together in a long scale cryostat to be kept at the liquid helium temperature of 4.2 K. The major insulation is provided by liquid helium. PROMISE withstands an AC voltage of 6 kV for 2 minutes with quite low partial discharge. A voltage-current synthetic test has proved that PROMISE has a transmission capability of 6,000 V-1,000 kVA. The fault current limiter actually limits overcurrent and prevents the other apparatus from quenching. Quench current level coordination is actually realized in PROMISE.

Trinad Chakraborty - One of the best experts on this subject based on the ideXlab platform.

  • Galleria mellonella as a Model System for studying Listeria pathogenesis
    Applied and Environmental Microbiology, 2010
    Co-Authors: Krishnendu Mukherjee, Torsten Hain, Eugen Domann, Andreas Vilcinskas, Boran Altincicek, Trinad Chakraborty
    Abstract:

    Essential aspects of the innate immune response to microbial infection are conserved between insects and mammals. This has generated interest in using insects as Model organisms to study host-microbe interactions. We used the greater wax moth Galleria mellonella, which can be reared at 37°C, as a Model host for examining the virulence potential of Listeria spp. Here we report that Galleria is an excellent surrogate Model of listerial septic infection, capable of clearly distinguishing between pathogenic and nonpathogenic Listeria strains and even between virulent and attenuated Listeria monocytogenes strains. Virulence required listerial genes hitherto implicated in the mouse infection Model and was linked to strong antimicrobial activities in both hemolymph and hemocytes of infected larvae. Following Listeria infection, the expression of immune defense genes such as those for lysozyme, galiomycin, gallerimycin, and insect metalloproteinase inhibitor (IMPI) was sequentially induced. Preinduction of antimicrobial activity by treatment of larvae with lipopolysaccharide (LPS) signifi-cantly improved survival against subsequent L. monocytogenes challenge and strong antilisterial activity was detected in the hemolymph of LPS pretreated larvae. We conclude that the severity of septic infection with L. monocytogenes is modulated primarily by innate immune responses, and we suggest the use of Galleria as a relatively simple, nonmammalian Model System that can be used to assess the virulence of strains of Listeria spp. isolated from a wide variety of settings from both the clinic and the environment.