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Experimental System (experimental + system)
Kinds of Experimental System Selected AbstractsNavigation Aided Image Processing in UAV Surveillance: Preliminary Results and Design of an Airborne Experimental SystemJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 2 2004Jonas Nygårds This paper describes an airborne reconfigurable measurement system being developed at Swedish Defence Research Agency (FOI), Sensor Technology, Sweden. An image processing oriented sensor management architecture for UAV (unmanned aerial vehicles) IR/EO-surveillance is presented. Some preliminary results of navigation aided image processing in UAV applications are demonstrated, such as SLAM (simultaneous localization and mapping), structure from motion and geolocation, target tracking, and detection of moving objects. The design goal of the measurement system is to emulate a UAV-mounted sensor gimbal using a stand-alone system. The minimal configuration of the system consists of a gyro-stabilized gimbal with IR and CCD sensors and an integrated high-performance navigation system. The navigation system combines dGPS real-time kinematics (RTK) data with data from an inertial measurement unit (IMU) mounted with reference to the optical sensors. The gimbal is to be used as an experimental georeferenced sensor platform, using a choice of carriers, to produce military relevant image sequences for studies of image processing and sensor control on moving surveillance and reconnaissance platforms. Furthermore, a high resolution synthetic environment, developed for sensor simulations in the visual and infrared wavelengths, is presented. © 2004 Wiley Periodicals, Inc. [source] Particulate Matter Removal from Diesel Exhaust Gases by a Combination of Corona Discharge and Water or Oil BathPLASMA PROCESSES AND POLYMERS, Issue 9 2006Yoshio Yoshioka Abstract Summary: As an efficient PM removal method from diesel exhausts, we developed a new method using a combination of a DC corona discharge and oil or water trays. The PM removal device generates DC corona discharges on oil or water filled in trays, thereby creating charges on the PMs, which can then be accelerated by an electric field towards the oil or water bath. The amount of PM absorbed in oil is determined by measuring light transmission. The discharge current on water is higher than that on oil. The difference of these discharge currents is considered to be due to the difference in ion mobility of the two liquids. An equation for PM removal characteristics is proposed. Using the equation, the PM removal by our device is estimated to be more than 85%. Experimental system for PM removal from diesel engine exhaust gas. [source] Symmetry-breaking in mammalian cell cohort migration during tissue pattern formation: Role of random-walk persistenceCYTOSKELETON, Issue 4 2005S. Huang Abstract Coordinated, cohort cell migration plays an important role in the morphogenesis of tissue patterns in metazoa. However, individual cells intrinsically move in a random walk-like fashion when studied in vitro. Hence, in the absence of an external orchestrating influence or template, the emergence of cohort cell migration must involve a symmetry-breaking event. To study this process, we used a novel experimental system in which multiple capillary endothelial cells exhibit spontaneous and robust cohort migration in the absence of chemical gradients when cultured on micrometer-scale extracellular matrix islands fabricated using microcontact printing. A computational model suggested that directional persistence of random-walk and dynamic mechanical coupling of adjacent cells are the critical control parameters for this symmetry-breaking behavior that is induced in spatially-constrained cell ensembles. The model predicted our finding that fibroblasts, which exhibit a much shorter motility persistence time than endothelial cells, failed to undergo symmetry breaking or produce cohort migration on the matrix islands. These findings suggest that cells have intrinsic motility characteristics that are tuned to match their role in tissue patterning. Our results underscore the importance of studying cell motility in the context of cell populations, and the need to address emergent features in multicellular organisms that arise not only from cell-cell and cell-matrix interactions, but also from properties that are intrinsic to individual cells. Cell Motil. Cytoskeleton 61:201,213, 2005. © 2005 Wiley-Liss, Inc. [source] Efficient transposition of a single Minos transposon copy in the genome of the ascidian Ciona intestinalis with a transgenic line expressing transposase in eggsDEVELOPMENTAL DYNAMICS, Issue 4 2010Akiko Hozumi Abstract Transgenesis with transposons is an important technique for studying genetic functions. In the ascidian Ciona intestinalis, methods for germline transformation with the Tc1/mariner transposon Minos have been established. A system to remobilize a single Minos copy in the genome is needed to refine this transgenic technique. In this study, such an experimental system was established with a transgenic line expressing Minos transposase in eggs. In the eggs of a double transgenic animal from a cross between the egg transposase line and a transgenic line having a single Minos insertion, the transposon was transposed into new positions of the Ciona genome, thus creating new insertions. Some of the new insertions caused enhancer detection. The majority of the new insertion sites were mapped on different chromosomes from that of the transposon donor. This characteristic of Minos is in contrast to that of the Sleeping Beauty transposon, which causes frequent intrachromosomal transposition. Developmental Dynamics 239:1076,1088, 2010. © 2010 Wiley-Liss, Inc. [source] Integration and differentiation of human embryonic stem cells transplanted to the chick embryoDEVELOPMENTAL DYNAMICS, Issue 1 2002Ronald S. Goldstein Abstract Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein,expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by ,-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells. © 2002 Wiley-Liss, Inc. [source] Two distinct P2Y receptors are involved in purine- and pyrimidine-evoked Ca2+ elevation in mammalian brain astrocytic culturesDRUG DEVELOPMENT RESEARCH, Issue 1-2 2001Chiara Bolego Abstract ATP and 2-methyl-thio-ATP (2-Me-SATP) increase cytosolic calcium concentrations ([Ca2+]i) in rat striatal astrocytes (Centemeri et al. [1997] Br J Pharmacol 121:1700,1706). The aim of the present study was to: (1) characterize pyrimidine-induced [Ca2+]i increases in the same experimental system, and (2) try to identify the multiple P2Y receptor subtypes mediating Ca2+ mobilization. UDP and UTP triggered a concentration-dependent [Ca2+]i elevation (EC50s = 0.58 ,M ± 0.4 and 31 ,M ± 6, respectively). Pyrimidine-evoked [Ca2+]i elevation was solely due to mobilization from intracellular stores, because: (1) removing calcium from extracellular medium or (2) blocking its influx with Ni2+ did not modify UTP responses; (3) the store-depleting agent thapsigargin completely abolished UTP-evoked [Ca2+]i increments. Guanosine-5,-O-(2-thiodiphosphate) partially inhibited the UTP response, whereas pertussis toxin (PTx) had no effect. The phospholipase C inhibitor U-73122 significantly reduced the UTP-evoked [Ca2+]i rise. Computer-assisted analysis indicated that the UTP and UDP responses are mediated by a single receptor, while ATP and 2-Me-SATP interact with two distinct receptors. The selective P2Y1 receptor antagonist MRS2179 abolished the ATP higher potency component. Sequential challenges with the same nucleotides resulted in almost complete homologous desensitization. Pre-exposure to UTP lowered the subsequent responses to either ATP or 2-Me-SATP. Maximally active concentrations of UTP and ATP were not additive. In conclusion, [Ca2+]i elevation in astrocytes by purines and pyrimidines is mediated by two distinct P2Y receptors, likely the P2Y1 and P2Y6 subtypes. Drug Dev. Res. 52:122,132, 2001. © 2001 Wiley-Liss, Inc. [source] A Web page that provides map-based interfaces for VRML/X3D contentELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 2 2009Yoshihiro Miyake Abstract The electronic map is very useful for navigation in the VRML/X3D virtual environments. So far various map-based interfaces have been developed. But they are lacking for generality because they have been separately developed for individual VRML/X3D contents, and users must use different interfaces for different contents. Therefore, we have developed a Web page that provides a common map-based interface for VRML/X3D contents on the Web. Users access VRML/X3D contents via the Web page. The Web page automatically generates a simplified map by analyzing the scene graph of downloaded contents, and embeds the mechanism to link the virtual world and the map. An avatar is automatically created and added to the map, and both a user and its avatar are bidirectionally linked together. In the simplified map, obstructive objects are removed and the other objects are replaced by base boxes. This paper proposes the architecture of the Web page and the method to generate simplified maps. Finally, an experimental system is developed in order to show the improvement of frame rates by simplifying the map. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(2): 28,37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10017 [source] Bioconcentration of persistent organic pollutants in four species of marine phytoplanktonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2005Antje Gerofke Abstract The uptake of polychlorinated biphenyls (PCBs) was studied in four species of marine algae. A novel experimental system to establish and maintain constant dissolved concentrations of PCBs was employed. Headspace sampling was used to verify that the freely dissolved concentrations remained constant with time. The headspace analysis also allowed sorption to dissolved organic carbon (DOC) to be quantified for all but the most lipophilic PCB congeners. Equilibration with the dissolved phase was rapid for three of the four algae species (<1 d for the majority of congeners). Organic carbon,normalized algae/water partition coefficients (KAlgW) were similar for three of the four species, but were lower by a factor of 10 to 20 for Phaeodactylum tricornutum. The KAlgW values of the first three species were similar to the octanol/water partition coefficient (KOW) for those PCB congeners for which DOC sorption could be quantified. These KAlgW values also agreed well with organic carbon,normalized bioconcentration factors for PCBs in suspended particulate matter (BCFSPM) sampled in Baltic Sea surface water during the summer. [source] Importance of maternal transfer of the photoreactive polycyclic aromatic hydrocarbon fluoranthene from benthic adult bivalves to their pelagic larvaeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Marguerite C. Pelletier Abstract Laboratory experiments were conducted to determine if maternal transfer of polycyclicaromatichydrocarbons (P AH) from benthic adult bivalves could result in phototoxicity to their pelagic larvae when exposed to ultraviolet light (UV). In these experiments, adult bivalves were exposed to water or sediments amended with the model photoreactive PAH, fluoranthene. Elevated adult fluoranthene tissue concentrations were correlated with embryo concentrations. Embryonic mortality was enhanced by exposure to ultraviolet light when adult tissue fluoranthene levels were greater than 5,000 ,g/g lipid. While the exposure concentrations used in this experimental system were high, ultraviolet light exposure levels were low. Also, some of the PAHs are more potent than the model compound used in this study. These results indicate that maternal transfer of photoactive PAHs from organisms living in contaminated sediments may represent a significant adverse effect to populations of benthic bivalves. [source] In vivo production of catalase containing haem analoguesFEBS JOURNAL, Issue 12 2010Myriam Brugna Haem (protohaem IX) analogues are toxic compounds and have been considered for use as antibacterial agents, but the primary mechanism behind their toxicity has not been demonstrated. Using the haem protein catalase in the Gram-positive bacterium Enterococcus faecalis as an experimental system, we show that a variety of haem analogues can be taken up by bacterial cells and incorporated into haem-dependent enzymes. The resulting cofactor-substituted proteins are dysfunctional, generally resulting in arrested cell growth or death. This largely explains the cell toxicity of haem analogues. In contrast to many other organisms, E. faecalis does not depend on haem for growth, and therefore resists the toxicity of many haem analogues. We have exploited this feature to establish a bacterial in vivo system for the production of cofactor-substituted haem protein variants. As a pilot study, we produced, isolated and analysed novel catalase variants in which the iron atom of the haem prosthetic group is replaced by other metals, i.e. cobalt, gallium, tin, and zinc, and also variants containing meso-protoheme IX, ruthenium meso-protoporphyrin IX and (metal-free) protoporphyrin IX. Engineered haem proteins of this type are of potential use within basic research and the biotechnical industry. Structured digital abstract ,,MINT-7722358, MINT-7722368: katA (uniprotkb:Q834P5) and katA (uniprotkb:Q834P5) physically interact (MI:0915) by copurification (MI:0025) [source] Dynamic changes in the epigenomic state and nuclear organization of differentiating mouse embryonic stem cellsGENES TO CELLS, Issue 4 2007Satoru Kobayakawa Changes in nuclear organization and the epigenetic state of the genome are important driving forces for developmental gene expression. However, a strategy that allows simultaneous visualization of the dynamics of the epigenomic state and nuclear structure has been lacking to date. We established an experimental system to observe global DNA methylation in living mouse embryonic stem (ES) cells. The methylated DNA binding domain (MBD) and the nuclear localization signal (nls) sequence coding for human methyl CpG-binding domain protein 1 (MBD1) were fused to the enhanced green fluorescent protein (EGFP) reporter gene, and ES cell lines carrying the construct (EGFP-MBD-nls) were established. The EGFP-MBD-nls protein was used to follow DNA methylation in situ under physiological conditions. We also monitored the formation and rearrangement of methylated heterochromatin using EGFP-MBD-nls. Pluripotent mouse ES cells showed unique nuclear organization in that methylated centromeric heterochromatin coalesced to form large clusters around the nucleoli. Upon differentiation, the organization of these heterochromatin clusters changed dramatically. Time-lapse microscopy successfully captured a moment of dramatic change in chromosome positioning during the transition between two differentiation stages. Thus, this experimental system should facilitate studies focusing on relationships between nuclear organization, epigenetic status and cell differentiation. [source] Where temperate meets tropical: multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh communityGLOBAL CHANGE BIOLOGY, Issue 5 2008KAREN L. McKEE Abstract Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2 - and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. [source] Use of multi-platform, multi-temporal remote-sensing data for calibration of a distributed hydrological model: an application in the Arno basin, ItalyHYDROLOGICAL PROCESSES, Issue 13 2006Lorenzo Campo Abstract Images from satellite platforms are a valid aid in order to obtain distributed information about hydrological surface states and parameters needed in calibration and validation of the water balance and flood forecasting. Remotely sensed data are easily available on large areas and with a frequency compatible with land cover changes. In this paper, remotely sensed images from different types of sensor have been utilized as a support to the calibration of the distributed hydrological model MOBIDIC, currently used in the experimental system of flood forecasting of the Arno River Basin Authority. Six radar images from ERS-2 synthetic aperture radar (SAR) sensors (three for summer 2002 and three for spring,summer 2003) have been utilized and a relationship between soil saturation indexes and backscatter coefficient from SAR images has been investigated. Analysis has been performed only on pixels with meagre or no vegetation cover, in order to legitimize the assumption that water content of the soil is the main variable that influences the backscatter coefficient. Such pixels have been obtained by considering vegetation indexes (NDVI) and land cover maps produced by optical sensors (Landsat-ETM). In order to calibrate the soil moisture model based on information provided by SAR images, an optimization algorithm has been utilized to minimize the regression error between saturation indexes from model and SAR data and error between measured and modelled discharge flows. Utilizing this procedure, model parameters that rule soil moisture fluxes have been calibrated, obtaining not only a good match with remotely sensed data, but also an enhancement of model performance in flow prediction with respect to a previous calibration with river discharge data only. Copyright © 2006 John Wiley & Sons, Ltd. [source] Establishment and recall of CD8+ T-cell memory in a model of localized transient infectionIMMUNOLOGICAL REVIEWS, Issue 1 2006Katherine Kedzierska Summary:, The influenza A virus model of localized, transient respiratory infection provides a well-defined experimental system for dissecting the induction and maintenance of CD8+ T-cell memory. This review focuses on quantitative and qualitative aspects of the prominent DbNP366 - and DbPA224 -specific CD8+ T-cell responses in virus-infected B6 mice. The different virus-specific effector and memory sets are compared by phenotypic [CD62L, interleukin-7 receptor-, (IL-7R,), and IL-15R, expression] and functional [interferon-, (IFN-,), tumor necrosis factor-, (TNF-,), and IL-2 production] analyses. Most clonotypes [defined by T-cell receptor (TCR) CDR3, sequence] generated during the acute phase of infection survive into memory, with those expressing the more consensus ,canonical' TCRs being the major contributors to the recall response. The extent of clonal expansion and the size of memory CD8+ T-cell populations has been characterized for mice challenged with either wildtype or mutant viruses, where broadly equivalent DbNP366 and DbPA224 expression was achieved by disabling the peptides in their native configuration, then expressing them in the viral neuraminidase protein. Combining the clonotypic and antigen dose analyses led to a somewhat mechanistic conclusion that the magnitude of any virus-specific CD8+ T-cell response will be a direct function of antigen dose and the size of the naïve or memory CD8+ T-cell precursor pool. [source] Correlation between clinical success and apical dye penetrationINTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2001C. M. Oliver Abstract Aim This study was undertaken to examine whether a correlation exists between apical dye penetration and the clinical performance of root fillings. Methodology Apical dye penetration into 116 roots of human teeth that had been root-filled at least 6 months prior to extraction was tested in vitro using a vacuum technique and by measuring the length of dye penetration. Endodontic treatment was classified as clinically successful or unsuccessful and results for these groups were compared using analysis of variance and the Student's t -test. Positive and negative controls were used to test the experimental system. Results All controls performed as expected. Dye penetrated significantly further in unsuccessful cases although the raw data suggested little difference. Overall, dye penetrated 99.5% of the specimens, indicating that the presence of dye in the canal is a poor indicator of whether the technique or material will succeed. However, the extent of dye penetration may be related to the clinical outcome. Conclusions Clinically placed root canal fillings do not provide an apical seal that prevents fluid penetration. The outcome of treatment cannot be predicted from the results of apical dye leakage studies. [source] Reproductive stem cell research and its application to urologyINTERNATIONAL JOURNAL OF UROLOGY, Issue 2 2008Takehiko Ogawa Abstract: Germ cells are defined by their innate potential to transmit genetic information to the next generation through fertilization. Males produce numerous sperm for long periods to maximize chances of fertilization. Key to the continuous production of large numbers of sperm are germline stem cells and their immediate daughter cells, functioning as transit amplifying cells. Recently, it has become possible to expand germline stem cells of rodents in vitro. In addition, multipotent stem cells, which are functionally the same as embryonic stem cells, have been established from neonatal mouse testes. These stem cells derived from the testis should contribute to biological research and technologies. On the other hand, the nature of human spermatogenesis is largely unknown due to the lack of an appropriate experimental system. However, the prevailing testicular sperm extraction procedure unraveled hitherto unknown facets of human spermatogenesis. The establishment of a culturing method for human spermatogonial stem cells in hopefully the near future would be a great benefit for achieving further insight into human spermatogenesis and should lead to more sophisticated diagnostic and therapeutic clinical measures for male infertility. [source] On Selection of the Perturbation Amplitude Required to Avoid Nonlinear Effects in Impedance MeasurementsISRAEL JOURNAL OF CHEMISTRY, Issue 3-4 2008Bryan Hirschorn Numerical simulations of electrochemical systems were used to explore the influence of large-amplitude potential perturbations on the measured impedance response. The amplitude of the input potential perturbation used for impedance measurements, normally fixed at a value of 10 mV for all systems, should instead be adjusted for each experimental system. Guidelines are developed for selection of appropriate perturbation amplitudes. A characteristic transition frequency is defined that can be used to tailor a frequency-dependent input signal to optimize signal-to-noise levels while maintaining a linear response. [source] The role of trout in stream food webs: integrating evidence from field surveys and experimentsJOURNAL OF ANIMAL ECOLOGY, Issue 2 2006KRISTIAN MEISSNER Summary 1We evaluated the effects of brown trout on boreal stream food webs using field surveys and enclosure/exclosure experiments. Experimental results were related to prey preference of uncaged trout in the same stream, as well as to a survey of macroinvertebrate densities in streams with vs. without trout. Finally, we assessed the generality of our findings by examining salmonid predation on three groups of macroinvertebrate prey (chironomid midges, epibenthic grazers, invertebrate predators) in a meta-analysis. 2In a preliminary experiment, invertebrate predators showed a strong negative response to trout, whereas chironomids benefited from trout presence. In the main experiment, trout impact increased with prey size. Trout had the strongest effect on invertebrate predators and cased caddis larvae, whereas Baetis mayfly and chironomid larvae were unaffected. Trout impact on the largest prey seemed mainly consumptive, because prey emigration rates were low and independent of fish presence. Despite strong effects on macroinvertebrates, trout did not induce a trophic cascade on periphyton. Uncaged trout showed a strong preference for the largest prey items (predatory invertebrates and aerial prey), whereas Baetis mayflies and chironomids were avoided by trout. 3Densities of invertebrate predators were significantly higher in troutless streams. Baetis mayflies also were less abundant in trout streams, whereas densities of chironomids were positively, although non-significantly, related to trout presence. Meta-analysis showed a strong negative impact of trout on invertebrate predators, a negative but variable impact on mobile grazers (mainly mayfly larvae) and a slightly positive impact on chironomid larvae. 4Being size-selective predators, salmonid fishes have a strong impact on the largest prey types available, and this effect spans several domains of scale. Discrepancies between our experimental findings and those from the field survey and meta-analysis show, however, that for most lotic prey, small-scale experiments do not reflect fish impact reliably at stream-wide scales. 5Our findings suggest that small-scale experiments will be useful only if the experimental results are evaluated carefully against natural history information about the experimental system and interacting species across a wide array of spatial scales. [source] Testing the assumptions of the ideal despotic distribution with an unpredictable food supply: experiments in juvenile salmonJOURNAL OF ANIMAL ECOLOGY, Issue 2 2005AMANDA MACLEAN Summary 1Models linking the behaviours of individual animals, their positions within socially complex groups and spatio-temporal variation in resource distribution offer a promising base for predicting population responses to changing environments. The ideal free and despotic distributions and their derivatives are particularly influential in this regard. 2Due to the difficulties of conducting work in the wild, for some groups of animals such models are often based on observations of animals in small-scale systems under conditions that are well controlled, but unnaturally simple. 3Using an experimental system based on field observations of home range size and variation in food availability, the present study tested whether models derived using small-scale laboratory observations are valid for juvenile Atlantic salmon in more natural conditions. 4Contrary to predictions, we found no differences in behaviour between the control fish (which experienced consistently rich feeding patches) and the experimental fish (which experienced unpredictable 10-fold changes in patch quality). 5Also contrary to predictions, in the variable condition, salmon used high quality patches (which were an order of magnitude better than low quality patches) only marginally (5%) more than would be expected if they were to forage at random. There was significant variation in foraging strategies between individual fish, with 28% of the population making non-random use of foraging patches. 6The only apparent systematic relationship between social rank and use of foraging patches was that fish that were both dominant and made many moves between feeding locations tended to leave rich patches less frequently than they left poor patches. 7Despite the low correlation between patch quality and movement, there was substantial movement of fish among patches. Forty-four per cent of moves followed aggressive interactions and most others were spontaneous, with no obvious motivating factor apparent. 8The study exposes a discrepancy between expectations derived from the basic concepts of patch choice theory and the behaviour of Atlantic salmon in the conditions pertaining in the present study. 9It is suggested that this discrepancy may arise both from the fact that applicability of patch choice models may be very sensitive to the stability of differences in patch quality and from uncertainties about the costs of habitat sampling. [source] Effect of thermochemical sludge pretreatment on sludge reduction and on performances of anoxic-aerobic membrane bioreactor treating low strength domestic wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2009Khac-Uan Do Abstract BACKGROUND: Reduction of excess sludge production has become an urgent issue. An investigation into the influence of thermochemical sludge pretreatment on sludge reduction in a bench-scale anoxic-aerobic membrane bioreactor was performed. Two systems were operated. In one system, part of the mixed liquid (1.5% of the influent flow rate) was pretreated thermochemically (at 80 °C, pH 11 and 3 h) and returned to the bioreactor. This study examined and evaluated the effect of thermochemical sludge pretreatment on the reduction of excess sludge and on the performance of the system. RESULTS: The average solubilization efficiency of the pretreated sludge was found to be about 0.2. The sludge production rate of the experimental system (E-MBR) was less than that of the control (C-MBR) by about 33%. The total phosphorus was removed mainly by normal cell synthesis, with removal efficiencies of 38,40% and 40,42% for the E-MBR and C-MBR, respectively. The total nitrogen removal in the E-MBR was slightly higher than in the C-MBR due to supply of soluble chemical oxygen demand (SCOD) from the digested sludge solution as an external carbon source. The mixed liquor volatile suspended solids (MLVSS) and mixed liquor suspended solids (MLSS) ratios for the two systems were almost identical, in the range 74,77%, indicating that the inorganics from the disintegrated cells do not accumulate as particulates in the reactor. The TMP was maintained at less than 6 cmHg for 180 days without membrane cleaning. CONCLUSION: Thermochemical sludge pretreatment can play an important role in reducing sludge production. The qualities of the effluent water were not significantly affected during 6 months of operation. Copyright © 2009 Society of Chemical Industry [source] The role of genotypic diversity in determining grassland community structure under constant environmental conditionsJOURNAL OF ECOLOGY, Issue 5 2007RAJ WHITLOCK Summary 1A recent experiment varied the genetic diversity of model grassland communities under standardized soil and management conditions and at constant initial species diversity. After 5 years' growth, genetically diverse communities retained more species diversity and became more similar in species composition than genetically impoverished communities. 2Here we present the results of further investigation within this experimental system. We proposed that two mechanisms , the first invoking genetically determined and constant differences in plant phenotypes and the second invoking genotype,environment interactions , could each underpin these results. This mechanistic framework was used as a tool to interpret our findings. 3We used inter-simple sequence repeat (ISSR) DNA markers to confirm which of the individuals of six study species initially included in the model communities were unique genotypes. We then used the molecular markers to assess the survival and abundance of each genotype at the end of the 5-year experimental period. 4The DNA marker data were used to create, for the first time, a genotype abundance hierarchy describing the structure of a community at the level of genotypes. This abundance hierarchy revealed wide variation in the abundance of genotypes within species, and large overlaps in the performance of the genotypes of different species. 5Each genotype achieved a consistent level of abundance within genetically diverse communities, which differed from that attained by other genotypes of the same species. The abundance hierarchy of genotypes within species also showed consistency across communities differing in their initial level of genetic diversity, such that species abundance in genetically impoverished communities could be predicted, in part, by genotypic identity. 6Three species (including two canopy-dominants) experienced shifts in their community-level genotype abundance hierarchies that were consistent with an increased influence of genotype,environment interactions in genetically impoverished communities. 7Our results indicate that under relatively constant environmental conditions the species abundance structure of plant communities can in part be predicted from the genotypic composition of their component populations. Genotype,environment interactions also appear to shape the structure of communities under such conditions, although further experiments are needed to clarify the magnitude and mechanism of these effects. [source] Detection of Pretreated Fingerprint Fluorescence Using an LED-based Excitation SystemJOURNAL OF FORENSIC SCIENCES, Issue 4 2008Masahisa Takatsu Ph.D. Abstract:, Optimization of a light emitting diode (LED)-based excitation system for the detection of pretreated fingerprint fluorescence is described. Fluorescent ridges can usually be excited by irradiation with forensic light sources such as xenon arc lamps or quartz-halogen lamps with high-power output and suitable filters. However, they are too expensive for many crime laboratories in smaller organizations. We concentrated on LEDs which have advantages over conventional light sources in that they are simpler and of lower cost, but the power output and quality of each individual LED unit is not sufficient for the detection of weak fluorescent ridges. To resolve this subject, blue and green LED arrays composed of ninety LED units were adopted and suitable low pass filters for them were designed. An experimental system, consisting of blue and green LED arrays with the suitable low pass filters for illumination, high pass filters for viewing, a digital camera and a computer, was tested. The fluorescent images of cyanoacrylate ester fumed/rhodamine 6G stained fingerprint on white polyethylene sheet and weak fluorescent ridges of ninhydrin/indium chloride treated fingerprint on white paper were successfully detected and photographed. It was shown that the improvement of LED beam in intensity and quality can compensate the disadvantages, resulting in well-contrasted images. [source] Interpretation of the temperature dependence of equilibrium and rate constantsJOURNAL OF MOLECULAR RECOGNITION, Issue 5 2006Donald J. Winzor Abstract The objective of this review is to draw attention to potential pitfalls in attempts to glean mechanistic information from the magnitudes of standard enthalpies and entropies derived from the temperature dependence of equilibrium and rate constants for protein interactions. Problems arise because the minimalist model that suffices to describe the energy differences between initial and final states usually comprises a set of linked equilibria, each of which is characterized by its own energetics. For example, because the overall standard enthalpy is a composite of those individual values, a positive magnitude for ,Ho can still arise despite all reactions within the subset being characterized by negative enthalpy changes: designation of the reaction as being entropy driven is thus equivocal. An experimenter must always bear in mind the fact that any mechanistic interpretation of the magnitudes of thermodynamic parameters refers to the reaction model rather than the experimental system For the same reason there is little point in subjecting the temperature dependence of rate constants for protein interactions to transition-state analysis. If comparisons with reported values of standard enthalpy and entropy of activation are needed, they are readily calculated from the empirical Arrhenius parameters. Copyright © 2006 John Wiley & Sons, Ltd. [source] Glutamate Receptor Subunit ,2 Is Highly Expressed in a Novel Population of Glial-Like Cells in Rat Pineal Glands in CultureJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Shouki Yatsushiro Abstract: The mammalian pineal gland uses L-glutamate as an intercellular chemical transmitter to regulate negatively melatonin synthesis. To receive glutamate signals, pinealocytes express at least three kinds of glutamate receptors: metabotropic receptor types 3 and 5 and an ionotropic receptor, GluR1. In this study, we examined whether or not the fourth class of ionotropic receptor, ,, which is known for its nondefinitive molecular function and its unique expression pattern in brain, is expressed in pineal gland. RT-PCR analyses with specific probes indicated the expression of mRNA of ,2 but not that of ,1 in pineal gland and cultured pineal cells. Western blotting analysis with polyclonal antibodies specific to the carboxyl-terminal region of the ,2 receptor recognized a single 110-kDa polypeptide of cerebellar membranes and specifically immunostained Purkinje cells. The ,2 antibodies recognized a 110-kDa polypeptide of pineal membranes and specifically immunostained huge glial-like cells with the occasional presence of several long, branching processes in a pineal cell culture. ,2 is not uniformly distributed throughout the cells and is relatively abundant at the periphery of the cell bodies and long processes, where the terminals of synaptophysin-positive processes of pinealocytes, a site for glutamate secretion, are frequently present. The ,2-positive cells constitute a very minor population among total pineal cells (,0.03%). Double immunolabeling with ,2 antibodies and antibodies against marker proteins for pineal interstitial cells clearly distinguishes ,2-positive pineal cells and other known interstitial cells, including glial fibrillary acidic protein- or vimentin-positive glial-like cells. These results indicated that the ,2 glutamate receptor is expressed in a novel subpopulation of pineal glial-like cells in culture and suggest the presence of a glutamate-mediated intercellular signal transduction mechanism between pinealocytes and ,2-expressing cells. The pineal cells may provide a good experimental system for studies on the function of glutamate receptor ,2. [source] A ceramic microfiltration tube membrane dispersion extractorAICHE JOURNAL, Issue 2 2004G. G. Chen Abstract Although the phase-free membrane extraction process has shown many advantages over the traditional extraction, the process is still at the experimental stage. On the other hand, in a new extractor a microfiltration membrane is used as a dispersion medium. The mass-transfer performance of the new extractor was tested with 30% TBP (in kerosene),nitric acid,H2O as an experimental system. The overall mass-transfer coefficient and the equipment efficiency were calculated with the concentrations of the inlet and outlet. The extractor was designed and constructed with two special inner elements for improving the performance further. The effects of the transmembrane pressure, the continuous-phase flow rate, and the geometric parameters of the inner elements on the mass-transfer performance, as well as on the flux of the dispersion phase, are discussed. The experimental results showed that very higher efficiency was reached. The inner elements could improve the mass-transfer performance greatly by changing the two-phase contact status. The results suggested that the mass-transfer process could be completed quickly while the drop size was in the range of micrometers. In addition, the flux of the dispersed phase was mainly influenced by the transmembrane pressure, not by the equipment structures, inner elements, and the continuous-phase flow rate. The new extractor can be operated with very higher efficiency and higher flux, and the efficiency can be predicted with a cubic polynomial. © 2004 American Institute of Chemical Engineers AIChE J, 50: 382,387, 2004 [source] Bioconversion of naltrexone and its 3-O-alkyl-ester prodrugs in a human skin equivalentJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2005Dana C. Hammell Abstract The purpose of this study was to compare the percutaneous absorption and bioconversion of naltrexone (NTX), naltrexone-3-O-valerate (VAL), and naltrexone-3-O-(2,-ethylbutyrate) (ETBUT) in a human skin equivalent model (EpiDermÔ) and in fresh human skin in vitro. NTX diffusion and metabolism to 6-,-naltrexol (NTXol) were quantitated and compared in the EpiDermÔ and in excised fresh human skin. VAL and ETBUT diffusion and bioconversion studies were also completed in EpiDermÔ. Naltrexone bioconverted to levels of 3,±,2% NTXol in the EpiDermÔ and 1,±,0.5% in fresh human skin. VAL hydrolyzed rapidly in the EpiDermÔ and mainly (93,±,4%) NTX was found in the receiver compartment, similar to human skin. More intact ETBUT permeated the EpiDermÔ tissue compared to VAL, and only 15,±,11% NTX was found in the receiver. Significantly higher fluxes of NTX and the prodrugs were observed with the EpiDermÔ compared to human skin. A similar flux enhancement level was observed for VAL, compared to NTX base, in the EpiDermÔ and the human skin. Metabolically active human epidermal models like EpiDermÔ are useful as an alternative experimental system to human skin for prediction of topical/transdermal drug/prodrug bioconversion. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:828,836, 2005 [source] Measurement of Horizontal and Vertical Movement of Ralstonia solanacearum in SoilJOURNAL OF PHYTOPATHOLOGY, Issue 10 2006M. Satou Abstract Two model systems were constructed to measure horizontal and vertical movement of bacteria in soil. These systems were applied to measuring movement of Ralstonia solanacearum (race 1, biovar 3), a causal agent of bacterial wilt of tomato, in andosol and sand at 28°C. The first system was used to measure horizontal movement of the bacteria in soil packed in a narrow horizontal frame. Suspension of the pathogen was applied to soil at one end of the frame, and bacterial number per gram of soil was measured over distance from the inoculation point after 4 days. Horizontal movement of R. solanacearum in supersaturated soil, but without flow, was possibly due to diffusion and the front advanced at 2.2 cm/day in andosol, and at 8.1 cm/day in sand. Using the same experimental system, but applying water inflow to one end of the frame only, the bacterium was detected at the front of water in andosol and sand. The front of the distribution advanced at 20.4 cm/h in andosol and 66.3 cm/h in sand. In the second experimental system, a cylinder of soil packed in a short tube was soaked with water, and soil at the top of the tube was inoculated with bacterial suspension. Immediately, soil cylinders were turned upward, and the bacterial number per gram of soil was measured along vertical distance from the inoculation point after 7 days. Using the system with andosol, the capillary water front rose to 32.5 cm over 7 days after inoculation, and R. solanacearum reached to 18.8 cm height. In sand, capillary water rose to 20.0 cm and the bacteria reached to 16.3 cm height. [source] Effects of inductive coupling on parallel MR image reconstructionsMAGNETIC RESONANCE IN MEDICINE, Issue 3 2004Michael A. Ohliger Abstract Theoretical arguments and experimental results are presented that characterize the impact of inductive coupling on the performance of parallel MRI reconstructions. A simple model of MR signal and noise reception suggests that the intrinsic amount of spatial information available from a given coil array is unchanged in the presence of inductive coupling, as long as the sample remains the dominant source of noise for the coupled array. Any loss of distinctness in the measured coil sensitivities is compensated by information stored in the measured noise correlations. Adjustments to the theory are described to account for preamplifier noise contributions. Results are presented from an experimental system in which preamplifier input impedances are systematically adjusted in order to vary the level of coupling between array elements. Parallel image reconstructions using an array with four different levels of coupling and an acceleration factor up to six show average SNR changes of ,7.6% to +7.5%. The modest changes in overall SNR are accompanied by similarly small changes in g-factor. These initial results suggest that moderate amounts of inductive coupling should not have a prohibitive effect on the use of a given coil array for parallel MRI. Magn Reson Med 52:628,639, 2004. © 2004 Wiley-Liss, Inc. [source] 2D EIT for biomedical imaging: Design, measurement, simulation, and image reconstructionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2007Kim Hwa Lim Abstract A 2D electrical impedance tomography (EIT) system has been developed at Duke University as an experimental system to test the forward and inverse algorithms for EIT application. The forward model is based on the 2nd-order finite element method (FEM), while the image reconstruction is based on the distorted Born iterative method (DBIM). The major contributions of this work are the application of the higher-order FEM as a forward solver, and the DBIM as an inverse solver to the integrated EIT system. The forward model has been validated with the measured data to within 0.5% accuracy. Excellent images have been reconstructed with these collected EIT data sets. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2989,2998, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22938 [source] Extracytoplasmic prosthetic group ligation to apoproteins: maturation of c -type cytochromesMOLECULAR MICROBIOLOGY, Issue 3 2006Serdar Turkarslan Summary In all organisms, haem is post-translationally and covalently attached to c apocytochromes to produce c holocytochromes via a process called c -type cytochromes maturation, which involves numerous components. In bacteria it was not clear which of these components catalyses the extracytoplasmic haem,apocytochrome ligation per se. In this issue of Molecular Microbiology, Feissner and colleagues report that a single polypeptide from Helicobacter pylori, corresponding to the fusion of two proteins found in other organisms, performs haem ligation to a coexpressed Bordetella pertussis apocytochrome c in an Escherichia coli mutant lacking its own cytochrome c maturation proteins. This simple experimental system pinpoints the components catalysing extracytoplasmic covalent haem ligation and raises intriguing issues about the requirements for delivery of haem and apocytochrome c substrates to produce c holocytochromes. [source] | ||||||||||||||||||||||||||||||||||||||||||||||