Science.gov

Sample records for leaky buildings isolation

  1. Isolating The Building Thermal Envelope

    NASA Astrophysics Data System (ADS)

    Harrje, D. T.; Dutt, G. S.; Gadsby, K. J.

    1981-01-01

    The evaluation of the thermal integrity of building envelopes by infrared scanning tech-niques is often hampered in mild weather because temperature differentials across the envelope are small. Combining the infrared scanning with positive or negative building pressures, induced by a "blower door" or the building ventilation system, considerably extends the periods during which meaningful diagnostics can be conducted. Although missing or poorly installed insulation may lead to a substantial energy penalty, it is the search for air leakage sites that often has the largest potential for energy savings. Infrared inspection of the attic floor with air forced from the occupied space through ceiling by-passes, and inspecting the interior of the building when outside air is being sucked through the envelope reveals unexpected leakage sites. Portability of the diagnostic equipment is essential in these surveys which may include access into some tight spaces. A catalog of bypass heat losses that have been detected in residential housing using the combined infrared pressure differential technique is included to point out the wide variety of leakage sites which may compromise the benefits of thermal insulation and allow excessive air infiltration. Detection and suppression of such leaks should be key items in any building energy audit program. Where a calibrated blower door is used to pressurize or evacuate the house, the leakage rate can be quantified and an excessively tight house recognized. Houses that are too tight may be improved with a minimal energy penalty by forced ventilation,preferably with a heat recuperator and/or by providing combustion air directly to the furnace.

  2. Optimization Criteria In Design Of Seismic Isolated Building

    SciTech Connect

    Clemente, Paolo; Buffarini, Giacomo

    2008-07-08

    Use of new anti-seismic techniques is certainly suitable for buildings of strategic importance and, in general, in the case of very high risk. For ordinary buildings, instead, the cost of base isolation system should be balanced by an equivalent saving in the structure. The comparison criteria have been first defined, then a large numerical investigation has been carried out to analyze the effectiveness and the economic suitability of seismic isolation in concrete buildings.

  3. Recent developments in seismically isolated buildings in Japan

    NASA Astrophysics Data System (ADS)

    Okamoto, Shin; Kani, Nagahide; Higashino, Masahiko; Koshika, Norihide; Kimizuka, Masayuki; Midorikawa, Mitsumasa; Iiba, Masanori

    2002-12-01

    The Building Standard Law of Japan and related Enforcement Order and Notifications have been substantially revised since the year 2000 to introduce a performance-based regulatory and deregulation system for building control systems. Up to then, time-history analyses were mandatory for isolated buildings and had to be specially approved by the Minster of the Ministry of Construction (MOC). Simplified design procedures based on the equivalent linear method for seismically isolated buildings have been issued as “Notification 2009 — Structural calculation procedure for buildings with seismic isolation” from MOC, and are now integrated into the Ministry of Land, Infrastructure, and Transportation (MLIT). Along with Notification 2009, “Notification 1446 of year 2000 — Standard for specifications and test methods for seismic isolation devices” was also issued. Buildings with heights equal to or less than 60m and that are designed according to these Notifications, including base isolated buildings, only need approval from local building officials, and no longer require the special approval of the Minister of MLIT. This paper summarizes: 1) some statistics related to buildings with seismic isolation completed up to the end of 2001; 2) simplified design procedures required by Notification 2009 of year 2000; and 3) performance of seismic isolation devices required by Notification 1446 of year 2000.

  4. Combating isolation: Building mutual mentoring networks

    NASA Astrophysics Data System (ADS)

    Cox, Anne J.

    2015-12-01

    Women physicists can often feel isolated at work. Support from a grant through the ADVANCE program of the National Science Foundation (U.S. government funding) created mutual mentoring networks aimed at combating isolation specifically for women faculty at undergraduate-only institutions. This paper will discuss the organization of one such network, what contributed to its success, some of the outcomes, and how it might be implemented in other contexts.

  5. Diseases associated with leaky hemichannels

    PubMed Central

    Retamal, Mauricio A.; Reyes, Edison P.; García, Isaac E.; Pinto, Bernardo; Martínez, Agustín D.; González, Carlos

    2015-01-01

    Hemichannels (HCs) and gap junction channels (GJCs) formed by protein subunits called connexins (Cxs) are major pathways for intercellular communication. While HCs connect the intracellular compartment with the extracellular milieu, GJCs allow the interchange of molecules between cytoplasm of two contacting cells. Under physiological conditions, HCs are mostly closed, but they can open under certain stimuli allowing the release of autocrine and paracrine molecules. Moreover, some pathological conditions, like ischemia or other inflammation conditions, significantly increase HCs activity. In addition, some mutations in Cx genes associated with human diseases, such as deafness or cataracts, lead to the formation of more active HCs or “leaky HCs.” In this article we will revise cellular and molecular mechanisms underlying the appearance of leaky HCs, and the consequences of their expression in different cellular systems and animal models, in seeking a common pattern or pathological mechanism of disease. PMID:26283912

  6. Numerical simulation of seismic response of a base isolated building with low shear modulus rubber isolators

    SciTech Connect

    Wang, C.Y.

    1993-01-01

    This paper describes seismic-response simulations of a base-isolated building subjected to actual earthquakes using the 3-D computer program, SISEC, developed at Argonne National Laboratory. The isolation system consists of six medium shape factor, high damping, and low shear modulus rubber bearings. To ensure the accuracy of analytical simulation, recorded data of full-size reinforced concrete structures located in Sendai, Japan are used as the benchmarks for comparisons of numerical simulations with observations. Results obtained from both analytical simulations and earthquake observations indicate that the advantage of base isolation in mitigating the acceleration of superstructure is very pronounced. For the two representative earthquakes, one had the strongest ground motion and the other one had similar magnitudes as the rest of the earthquakes recorded at the test site, the simulated accelerations at the roof level of the isolated building are about 20% to 30% of the ordinary building accelerations. Also, results reveal that for both ordinary and base-isolated buildings the computed accelerations agree reasonably well with those recorded.

  7. Numerical simulation of seismic response of a base isolated building with low shear modulus rubber isolators

    SciTech Connect

    Wang, C.Y.

    1993-06-01

    This paper describes seismic-response simulations of a base-isolated building subjected to actual earthquakes using the 3-D computer program, SISEC, developed at Argonne National Laboratory. The isolation system consists of six medium shape factor, high damping, and low shear modulus rubber bearings. To ensure the accuracy of analytical simulation, recorded data of full-size reinforced concrete structures located in Sendai, Japan are used as the benchmarks for comparisons of numerical simulations with observations. Results obtained from both analytical simulations and earthquake observations indicate that the advantage of base isolation in mitigating the acceleration of superstructure is very pronounced. For the two representative earthquakes, one had the strongest ground motion and the other one had similar magnitudes as the rest of the earthquakes recorded at the test site, the simulated accelerations at the roof level of the isolated building are about 20% to 30% of the ordinary building accelerations. Also, results reveal that for both ordinary and base-isolated buildings the computed accelerations agree reasonably well with those recorded.

  8. Secondary metabolites from Penicillium corylophilum isolated from damp buildings.

    PubMed

    McMullin, David R; Nsiama, Tienabe K; Miller, J David

    2014-01-01

    Indoor exposure to the spores and mycelial fragments of fungi that grow on damp building materials can result in increased non-atopic asthma and upper respiratory disease. The mechanism appears to involve exposure to low doses of fungal metabolites. Penicillium corylophilum is surprisingly common in damp buildings in USA, Canada and western Europe. We examined isolates of P. corylophilum geographically distributed across Canada in the first comprehensive study of secondary metabolites of this fungus. The sesquiterpene phomenone, the meroterpenoids citreohybridonol and andrastin A, koninginin A, E and G, three new alpha pyrones and four new isochromans were identified from extracts of culture filtrates. This is the first report of koninginins, meroterpenoids and alpha pyrones from P. corylophilum. These secondary metabolite data support the removal of P. corylophilum from Penicillium section Citrina and suggest that further taxonomic studies are required on this species. PMID:24891425

  9. Retrofitting Heritage Buildings by Strengthening or Using Seismic Isolation

    SciTech Connect

    Danieli, Moshe; Bloch, Jacob; Ribakov, Yuri

    2008-07-08

    Many heritage buildings in the Mediterranean area include stone domes as a structural and architectural element. Present stage of these buildings often requires strengthening or retrofitting in order to increase their seismic resistance. Strengthening is possible by casting above existing dome a thin reinforced concrete shell with a support ring. It yields reduction of stresses and strains in the dome. This paper deals with examples of actual restoration and strengthening of three structures in Georgia, two of them damaged by an earthquake in 1991, (a temple in Nikortzminda and a synagogue in Oni, built in 11{sup th} and 19{sup r} century, respectively) and a mosque in Akhaltzikhe, built in 18th century. Retrofitting of these structures was aimed at preservation of initial geometry and appearance by creating composite (stone--reinforced concrete, or stone--shotcrete) structures, which were partially or fully hidden. Further improving of seismic response may be achieved by using hybrid seismic isolation decreasing the seismic forces and adding damping. A brief description of the design procedure for such cases is presented.

  10. Retrofitting Heritage Buildings by Strengthening or Using Seismic Isolation

    NASA Astrophysics Data System (ADS)

    Danieli, Moshe; Bloch, Jacob; Ribakov, Yuri

    2008-07-01

    Many heritage buildings in the Mediterranean area include stone domes as a structural and architectural element. Present stage of these buildings often requires strengthening or retrofitting in order to increase their seismic resistance. Strengthening is possible by casting above existing dome a thin reinforced concrete shell with a support ring. It yields reduction of stresses and strains in the dome. This paper deals with examples of actual restoration and strengthening of three structures in Georgia, two of them damaged by an earthquake in 1991, (a temple in Nikortzminda and a synagogue in Oni, built in 11th and 19r century, respectively) and a mosque in Akhaltzikhe, built in 18th century. Retrofitting of these structures was aimed at preservation of initial geometry and appearance by creating composite (stone—reinforced concrete, or stone—shotcrete) structures, which were partially or fully hidden. Further improving of seismic response may be achieved by using hybrid seismic isolation decreasing the seismic forces and adding damping. A brief description of the design procedure for such cases is presented.

  11. Automatic generation of smart earthquake-resistant building system: Hybrid system of base-isolation and building-connection.

    PubMed

    Kasagi, M; Fujita, K; Tsuji, M; Takewaki, I

    2016-02-01

    A base-isolated building may sometimes exhibit an undesirable large response to a long-duration, long-period earthquake ground motion and a connected building system without base-isolation may show a large response to a near-fault (rather high-frequency) earthquake ground motion. To overcome both deficiencies, a new hybrid control system of base-isolation and building-connection is proposed and investigated. In this new hybrid building system, a base-isolated building is connected to a stiffer free wall with oil dampers. It has been demonstrated in a preliminary research that the proposed hybrid system is effective both for near-fault (rather high-frequency) and long-duration, long-period earthquake ground motions and has sufficient redundancy and robustness for a broad range of earthquake ground motions.An automatic generation algorithm of this kind of smart structures of base-isolation and building-connection hybrid systems is presented in this paper. It is shown that, while the proposed algorithm does not work well in a building without the connecting-damper system, it works well in the proposed smart hybrid system with the connecting damper system. PMID:27441248

  12. Analysis of the seismic performance of isolated buildings according to life-cycle cost.

    PubMed

    Dang, Yu; Han, Jian-Ping; Li, Yong-Tao

    2015-01-01

    This paper proposes an indicator of seismic performance based on life-cycle cost of a building. It is expressed as a ratio of lifetime damage loss to life-cycle cost and determines the seismic performance of isolated buildings. Major factors are considered, including uncertainty in hazard demand and structural capacity, initial costs, and expected loss during earthquakes. Thus, a high indicator value indicates poor building seismic performance. Moreover, random vibration analysis is conducted to measure structural reliability and evaluate the expected loss and life-cycle cost of isolated buildings. The expected loss of an actual, seven-story isolated hospital building is only 37% of that of a fixed-base building. Furthermore, the indicator of the structural seismic performance of the isolated building is much lower in value than that of the structural seismic performance of the fixed-base building. Therefore, isolated buildings are safer and less risky than fixed-base buildings. The indicator based on life-cycle cost assists owners and engineers in making investment decisions in consideration of structural design, construction, and expected loss. It also helps optimize the balance between building reliability and building investment. PMID:25653677

  13. Analysis of the Seismic Performance of Isolated Buildings according to Life-Cycle Cost

    PubMed Central

    Dang, Yu; Han, Jian-ping; Li, Yong-tao

    2015-01-01

    This paper proposes an indicator of seismic performance based on life-cycle cost of a building. It is expressed as a ratio of lifetime damage loss to life-cycle cost and determines the seismic performance of isolated buildings. Major factors are considered, including uncertainty in hazard demand and structural capacity, initial costs, and expected loss during earthquakes. Thus, a high indicator value indicates poor building seismic performance. Moreover, random vibration analysis is conducted to measure structural reliability and evaluate the expected loss and life-cycle cost of isolated buildings. The expected loss of an actual, seven-story isolated hospital building is only 37% of that of a fixed-base building. Furthermore, the indicator of the structural seismic performance of the isolated building is much lower in value than that of the structural seismic performance of the fixed-base building. Therefore, isolated buildings are safer and less risky than fixed-base buildings. The indicator based on life-cycle cost assists owners and engineers in making investment decisions in consideration of structural design, construction, and expected loss. It also helps optimize the balance between building reliability and building investment. PMID:25653677

  14. Successful performance of a base-isolated hospital building during the 17 January 1994 northridge earthquake

    USGS Publications Warehouse

    Celebi, M.

    1996-01-01

    The purpose of this paper is to examine the response records and thereby the performance of the base-isolated University of Southern California (USC) hospital building during the Ms = 6-8 Northridge (California) earthquake of 17 January 1994. The data retrieved from the building is the first set of data from any base-isolated building that (a) was tested to acceleration levels at the free-field similar to the zero period acceleration (ZPA) level postulated in the seismic design criteria of the building and (b) exhibits levels of relative displacement excursions which puts the isolators into the nonlinear range. The variation of the fundamental frequency as a function of changing instantaneous stiffness of the isolators is identifiable. During the shaking, the isolators (a) performed well and, having attained up to 10% hysteretic damping, effectively dissipated the incoming energy of motions and (b) reduced the drift ratios of the superstructure of the building to a maximum of 10% of the allowable, which should explain the fact that there was no damage to the structure or its contents. The primary conclusion of this study is that this base-isolated building performed well during the Northridge earthquake of 17 January 1994 when only approximately 10% of the displacement capability of the isolators were utilized. Therefore, there is every reason to believe that the building will perform well during future earthquakes in the region.

  15. Joint US/Japanese program of full-size building tests for base seismic isolation

    SciTech Connect

    Kuroda, T. . Nuclear Power Div.); Chang, Y.W.; Seidensticker, R.W. )

    1990-01-01

    Shimizu Corporation of Japan and Argonne National Laboratory of the USA initiated a joint research program on base seismic isolation. The program is centered on testing and analyzing isolation systems in a full-size building and to obtain data on relative response between isolated and nonisolated structures under earthquake conditions. The test facility consists of two identical full-size three-story buildings built side by side, located at Tohoku University in Sendai, Japan. Since April 1989, after the installation of bearings, over 20 earthquake data have been recorded at Sendai test facility. This paper describes the test facility, isolation bearings, observed earthquake records, and responses of isolated and nonisolated buildings under earthquake loads. 3 refs., 15 figs.

  16. Effects Of Leaky Sewers On Groundwater Quality

    NASA Astrophysics Data System (ADS)

    Leschik, S.; Musolff, A.; Reinstorf, F.; Strauch, G.; Oswald, S. E.; Schirmer, M.

    2007-12-01

    The impact of urban areas on groundwater quality has become an emerging research field in hydrogeology. Urban subsurface infrastructures like sewer networks are often leaky, so untreated wastewater may enter the urban aquifer. The transport of wastewater into the groundwater is still not well understood under field conditions. In the research platform WASSER Leipzig (Water And Sewershed Study of Environmental Risk in Leipzig- Germany) the effects of leaky sewers on the groundwater quality are investigated. The research is focused on the occurrence and transport of so-called "xenobiotics" such as pharmaceuticals and personal care product additives. Xenobiotics may pose a threat on human health, but can also be considered a marker for an urban impact on water resources. A new test site was established in Leipzig to quantify mass fluxes of xenobiotics into the groundwater from a leaky sewer. Corresponding to the leaks which were detected by closed circuit television inspections, monitoring wells were installed up- and downstream of the sewer. Concentrations of eight xenobiotics (technical-nonylphenol, bisphenol-a, caffeine, galaxolide, tonalide, carbamazepine, phenazone, ethinylestradiol) obtained from first sampling programmes were found to be highly heterogeneous, but a relation between the position of the sampling points and the sewer could not be clearly identified. However, concentrations of sodium, chloride, potassium and nitrate increased significantly downstream of the sewer which may be due to wastewater exfiltration, since no other source is known on the water flowpath from the upstream to the downstream wells. Because of the highly heterogeneous spatial distribution of xenobiotics at the test site, a monitoring concept was developed comprising both high-resolution sampling and an integral approach to obtain representative average concentrations. Direct-push techniques were used to gain insight into the fine-scale spatial distribution of the target compounds

  17. Leaky wave lenses for spoof plasmon collimation.

    PubMed

    Panaretos, Anastasios H; Werner, Douglas H

    2016-06-27

    We theoretically demonstrate the feasibility of collimating radiating spoof plasmons using a leaky wave lens approach. Spoof plasmons are surface waves excited along reactance surfaces realized through metallic corrugations. By employing a periodic perturbation to the geometric profile of this type of reactance surface, it becomes feasible to convert the excited spoof plasmons into free-space radiating leaky wave modes. It is demonstrated that by structurally modifying such a corrugated surface through the introduction of a non-uniform sinusoidally modulated reactance profile, then a tapered wavenumber, with a real part less than that of free space, can be established along the surface. In this way the radiating properties of the structure (amplitude and phase) can be locally controlled thereby creating a radiating effect similar to that of a non-uniform current distribution. By properly engineering the space dependent wavenumber along the corrugated surface, different regions of the structure will emit spoof plasmon energy at different angles with varying intensity. The combined effect is the emission of an electromagnetic wave exhibiting a converging wave-front that eventually collimates spoof plasmon energy at some desired focal point. PMID:27410618

  18. Nitric oxide protects endothelium from cadmium mediated leakiness.

    PubMed

    Nagarajan, Shunmugam; Rajendran, Saranya; Saran, Uttara; Priya, M Krishna; Swaminathan, Akila; Siamwala, Jamila H; Sinha, Swaraj; Veeriah, Vimal; Sonar, Punam; Jadhav, Vivek; Jaffar Ali, B M; Chatterjee, Suvro

    2013-05-01

    Cadmium targets the vascular endothelium causing endothelial dysfunction and leakiness of endothelial barrier. Nitric oxide plays a major role in mediating endothelial functions including angiogenesis, migration and permeability. The present study investigates the nitric oxide effects on cadmium induced endothelial leakiness. Results of ex vivo and in vitro permeability assays showed that even a sub-lethal dose of cadmium chloride (1 µM) was sufficient to induce leakiness of endothelial cells. Cadmium drastically altered the actin polymerisation pattern and membrane tension of these cells compared to controls. Addition of nitric oxide donor Spermine NONOate (SP) significantly blunted cadmium-mediated effects and recover endothelial cells integrity. Cadmium-induced cytoskeletal rearrangements and membrane leakiness are associated with the low nitric oxide availability and high reactive oxygen species generation. In brief, we show the protective role of nitric oxide against cadmium-mediated endothelial leakiness. PMID:23404577

  19. Leaky domino-modes in regular arrays of substantially thick metal nanostrips

    NASA Astrophysics Data System (ADS)

    Voroshilov, Pavel M.; Simovski, Constantin R.

    2016-07-01

    In previous works, an efficient light trapping performed by arrays of metal nanoantennas whose building block was a slightly tapered (trapezoidal) substantially thick nanostrip was revealed. This light trapping implied a broad spectrum of solar light concentrated in a subwavelength depth of the semiconductor substrate. This is a very advantageous feature allowing our structure to enhance thin-film solar cells. However, the physics of the broadband resonant absorption in the substrate was not investigated. In the present paper, we show that our arrays support so-called leaky domino-modes, responsible for such the light trapping. These modes are multipole oscillations of the array of substantially thick nanostrips. In this work we have thoroughly studied these leaky modes relating them to resonances of high-order multipole moments and to broadband light-trapping effect.

  20. Use of a viscoelastic model for the seismic response of base-isolated buildings

    SciTech Connect

    Uras, R.A.

    1994-06-01

    Due to recent developments in elastomer technology, seismic isolation using elastomer bearings is rapidly becoming an acceptable design tool to enhance structural seismic margins and to protect people and equipment from earthquake damage. With proper design of isolators, high-energy seismic input motions are transformed into low-frequency, low energy harmonic motions and the accelerations acting on the isolated building are significantly reduced. Several alternatives exist for the modeling of the isolators. This study is concerned with the use of a viscoelastic model to predict the seismic response of base-isolated buildings. The in-house finite element computer code has been modified to incorporate a viscoelastic spring element, and several simulations are performed. Then, the computed results have been compared with the corresponding observed data recorded at the test facility.

  1. Modeling the behavior of an earthquake base-isolated building.

    SciTech Connect

    Coveney, V. A.; Jamil, S.; Johnson, D. E.; Kulak, R. F.; Uras, R. A.

    1997-11-26

    Protecting a structure against earthquake excitation by supporting it on laminated elastomeric bearings has become a widely accepted practice. The ability to perform accurate simulation of the system, including FEA of the bearings, would be desirable--especially for key installations. In this paper attempts to model the behavior of elastomeric earthquake bearings are outlined. Attention is focused on modeling highly-filled, low-modulus, high-damping elastomeric isolator systems; comparisons are made between standard triboelastic solid model predictions and test results.

  2. Groundwater intrusion into leaky sewer systems.

    PubMed

    Wittenberg, H; Aksoy, H

    2010-01-01

    Vast volumes of groundwater are drained by urban sewer systems. This unwanted flow component intrudes into sewer systems through leaky joints or connected house drains. However, unlike urban storm drainage, it has a high seasonal variation corresponding to groundwater storage and long slow recessions similar to baseflow in rivers also fed by shallow groundwater exfiltrating into the surface waters. By applying the nonlinear reservoir algorithm as used for baseflow separation from total flow in a river, groundwater flow is separated from daily measured influents to treatment plants in Lower Saxony and Baden-Württemberg, Germany and in the Terkos Lake watershed near Istanbul, Turkey. While waste water flows vary only moderately within a year, separated intruded groundwater flows show recessions and seasonal variations correlated to baseflow in neighbouring rivers. It is possible to conclude that recession characteristics of treatment plant influents allow quantification and prediction of groundwater intrusion into sewer systems. PMID:20595758

  3. Leaky Dyakonov surface plasmon polaritons for birefringent crystals

    NASA Astrophysics Data System (ADS)

    Loot, Ardi; Hizhnyakov, Vladimir

    2016-04-01

    The surface waves propagating at the interface of a metal-birefringent crystal, usually called Dyakonov surface plasmon polaritons (DSPPs), have been theoretically investigated. It was shown that at special conditions the extraordinarily polarized component of DSPPs could become leaky. The properties of such half-leaky waves were theoretically investigated, and it was shown that these surface waves could be excited without any prism or grating. This is especially beneficial in the experiments of nonlinear optics where a field enhancement is required.

  4. Simulation of the response of base-isolated buildings under earthquake excitations considering soil flexibility

    NASA Astrophysics Data System (ADS)

    Mahmoud, Sayed; Austrell, Per-Erik; Jankowski, Robert

    2012-09-01

    The accurate analysis of the seismic response of isolated structures requires incorporation of the flexibility of supporting soil. However, it is often customary to idealize the soil as rigid during the analysis of such structures. In this paper, seismic response time history analyses of base-isolated buildings modelled as linear single degree-of-freedom (SDOF) and multi degree-of-freedom (MDOF) systems with linear and nonlinear base models considering and ignoring the flexibility of supporting soil are conducted. The flexibility of supporting soil is modelled through a lumped parameter model consisting of swaying and rocking spring-dashpots. In the analysis, a large number of parametric studies for different earthquake excitations with three different peak ground acceleration (PGA) levels, different natural periods of the building models, and different shear wave velocities in the soil are considered. For the isolation system, laminated rubber bearings (LRBs) as well as high damping rubber bearings (HDRBs) are used. Responses of the isolated buildings with and without SSI are compared under different ground motions leading to the following conclusions: (1) soil flexibility may considerably influence the stiff superstructure response and may only slightly influence the response of the flexible structures; (2) the use of HDRBs for the isolation system induces higher structural peak responses with SSI compared to the system with LRBs; (3) although the peak response is affected by the incorporation of soil flexibility, it appears insensitive to the variation of shear wave velocity in the soil; (4) the response amplifications of the SDOF system become closer to unit with the increase in the natural period of the building, indicating an inverse relationship between SSI effects and natural periods for all the considered ground motions, base isolations and shear wave velocities; (5) the incorporation of SSI increases the number of significant cycles of large amplitude

  5. Development of a novel multi-layer MRE isolator for suppression of building vibrations under seismic events

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Sun, Shuaishuai; Tian, Tongfei; Li, Weihua; Du, Haiping; Alici, Gursel; Nakano, Masami

    2016-03-01

    Protecting civil engineering structures from uncontrollable events such as earthquakes while maintaining their structural integrity and serviceability is very important; this paper describes the performance of a stiffness softening magnetorheological elastomer (MRE) isolator in a scaled three storey building. In order to construct a closed-loop system, a scaled three storey building was designed and built according to the scaling laws, and then four MRE isolator prototypes were fabricated and utilised to isolate the building from the motion induced by a scaled El Centro earthquake. Fuzzy logic was used to output the current signals to the isolators, based on the real-time responses of the building floors, and then a simulation was used to evaluate the feasibility of this closed loop control system before carrying out an experimental test. The simulation and experimental results showed that the stiffness softening MRE isolator controlled by fuzzy logic could suppress structural vibration well.

  6. Surface plasmons leaky radiation of the flat metal

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Hu, Dejiao; Pang, Lin

    2015-08-01

    Surface plasmons have been widely investigated in many fields due to the unique property. ATR (attenuated totalreflection) is the common method to excite surface plasmons. We derive the Fano-type analysis to present the reflection spectrum of ATR configuration derived from the three-layer Fresnel reflection equation, which are asymmetric curves resulted from interference between direct reflectance and surface plasmons leaky radiation. In the fitting progress, we obtain the relationship between surface plasmons leaky radiation and metal thickness. When the metal thickness is greater than 25nm, surface plasmons leaky radiation rate is less than 0.07. We also compare the ATR and grating coupler excitement mechanism, which provide a reference to evaluate their application.

  7. Displacement response analysis of base-isolated buildings subjected to near-fault ground motions with velocity pulse

    NASA Astrophysics Data System (ADS)

    He, Qiumei; Li, Xiaojun; Yang, Yu; Liu, Aiwen; Li, Yaqi

    2016-04-01

    In order to study the influence of the velocity pulse to seismic displacement response of base-isolated buildings and the differences of the influent of the two types of near-fault ground motions with velocity pulse to seismic response of base-isolated buildings, the seismic responses are analyzed by three dimensional finite element models for three base-isolated buildings, 4 stories, 9 stories and 14 stories. In this study, comparative analyses were done for the seismic displacement responses of the base-isolated structures under 6 near-fault ground motion records with velocity pulse and no velocity pulse, in which, 6 artificial ground motion time histories with same elastic response spectrum as the 6 near-fault ground motion records are used as the ground motion with no velocity pulse. This study indicates that under the ground motions with velocity pulse the seismic displacement response of base-isolated buildings is significantly increased than the ground motions with no velocity pulse. To the median-low base-isolated buildings, the impact of forward directivity pulses is bigger than fling-step pulses. To the high base-isolated buildings, the impact of fling-step pulses is bigger than forward directivity pulses. The fling-step pulses lead to large displacement response in the lower stories. This work has been supported by the National Natural Science Foundation of China (Grant No.51408560)

  8. Middle School Girls and the "Leaky Pipeline" to Leadership

    ERIC Educational Resources Information Center

    Shapiro, Mary; Grossman, Diane; Carter, Suzanne; Martin, Karyn; Deyton, Patricia; Hammer, Diane

    2015-01-01

    Why do girls perform so well academically yet lose ground as professional women? This diminishing number of women up the leadership hierarchy is often referred to as the "leaky pipeline," and attributed to many factors: external ones such as work environments not conducive to work/life balance, and internal ones such as women's own…

  9. Design of isolated buildings with S-FBI system subjected to near-fault earthquakes using NSGA-II algorithm

    NASA Astrophysics Data System (ADS)

    Ozbulut, O. E.; Silwal, B.

    2014-04-01

    This study investigates the optimum design parameters of a superelastic friction base isolator (S-FBI) system through a multi-objective genetic algorithm and performance-based evaluation approach. The S-FBI system consists of a flat steel- PTFE sliding bearing and a superelastic NiTi shape memory alloy (SMA) device. Sliding bearing limits the transfer of shear across the isolation interface and provides damping from sliding friction. SMA device provides restoring force capability to the isolation system together with additional damping characteristics. A three-story building is modeled with S-FBI isolation system. Multiple-objective numerical optimization that simultaneously minimizes isolation-level displacements and superstructure response is carried out with a genetic algorithm (GA) in order to optimize S-FBI system. Nonlinear time history analyses of the building with S-FBI system are performed. A set of 20 near-field ground motion records are used in numerical simulations. Results show that S-FBI system successfully control response of the buildings against near-fault earthquakes without sacrificing in isolation efficacy and producing large isolation-level deformations.

  10. Impedance-matching analysis in IR leaky-wave antennas

    NASA Astrophysics Data System (ADS)

    Premkumar, Navaneeth; Xu, Yuancheng; Lail, Brian A.

    2015-08-01

    Planar leaky-wave antennas (LWA) that are capable of full-space scanning have long since been the pursuit for applications including, but not limited to, integration onto vehicles and into cameras for wide-angle of view beam-steering. Such a leaky-wave surface (LWS) was designed for long-wave infrared frequencies with frequency scanning capability. The LWS is based on a microstrip patch array design of a leaky-wave impedance surface and is made up of gold microstrip patches on a grounded zinc sulphide substrate. A 1D composite right/left-handed (CRLH) metamaterial made by periodically stacking a unit cell of the LWS in the longitudinal direction to form a LWA was designed. This paper deals with loading the LWA with a nickel bolometer to collect leaky-wave signals. The LWA radiates a backward leaking wave at 30 degrees at 28.3THz and scans through broadside for frequencies 20THz through 40THz. The paper deals with effectively placing the bolometer in order for the collected signal to exhibit the designed frequency regime. An effective way to maximize the power coupling into the load from the antenna is also explored. The benefit of such a metamaterial/holographic antennacoupled detector is its ability to provide appreciable capture cross-sections while delivering smart signals to subwavelength sized detectors. Due to their high-gain, low-profile, fast response time of the detector and ease of fabrication, this IR LWA-coupled bolometer harbors great potential in the areas of high resolution, uncooled, infrared imaging.

  11. Aqueous dispersions of DMPG in low salt contain leaky vesicles.

    PubMed

    Barroso, Rafael P; Perez, Katia Regina; Cuccovia, Iolanda M; Teresa Lamy, M

    2012-02-01

    Aqueous dispersions of dimyristoyl phosphatidylglycerol (DMPG), at low ionic strength, display uncommon thermal behavior. Models for such behavior need to assign a form to the lipid aggregate. Although most studies accept the presence of lipid vesicles in the lipid gel and fluid phases, this is still controversial. With electron spin resonance (ESR) spectra of spin labels incorporated into DMPG aggregates, quantification of [(14)C]sucrose entrapped by the aggregates, and viscosity measurements, we demonstrate the existence of leaky vesicles in dispersions of DMPG at low ionic strength, in both gel and fluid phases of the lipid. As a control system, the ubiquitous lipid dimyristoyl phosphatidylcholine (DMPC) was used. For DMPG in the gel phase, spin labeling only indicated the presence of lipid bilayers, strongly suggesting that DMPG molecules are organized as vesicles and not micelles or bilayer fragments (bicelles), as the latter has a non-bilayer structure at the edges. Quantification of [(14)C]sucrose entrapping by DMPG aggregates revealed the presence of highly leaky vesicles. Due to the short hydrocarbon chains ((14)C atoms), DMPC vesicles were also found to be partially permeable to sucrose, but not as much as DMPG vesicles. Viscosity measurements, with the calculation of the intrinsic viscosity of the lipid aggregate, showed that DMPG vesicles are rather similar in the gel and fluid phases, and quite different from aggregates observed along the gel-fluid transition. Taken together, our data strongly supports that DMPG forms leaky vesicles at both gel and fluid phases. PMID:22209922

  12. Holographic leaky-wave metasurfaces for dual-sensor imaging

    NASA Astrophysics Data System (ADS)

    Li, Yun Bo; Li, Lian Lin; Cai, Ben Geng; Cheng, Qiang; Cui, Tie Jun

    2015-12-01

    Metasurfaces have huge potentials to develop new type imaging systems due to their abilities of controlling electromagnetic waves. Here, we propose a new method for dual-sensor imaging based on cross-like holographic leaky-wave metasurfaces which are composed of hybrid isotropic and anisotropic surface impedance textures. The holographic leaky-wave radiations are generated by special impedance modulations of surface waves excited by the sensor ports. For one independent sensor, the main leaky-wave radiation beam can be scanned by frequency in one-dimensional space, while the frequency scanning in the orthogonal spatial dimension is accomplished by the other sensor. Thus, for a probed object, the imaging plane can be illuminated adequately to obtain the two-dimensional backward scattered fields by the dual-sensor for reconstructing the object. The relativity of beams under different frequencies is very low due to the frequency-scanning beam performance rather than the random beam radiations operated by frequency, and the multi-illuminations with low relativity are very appropriate for multi-mode imaging method with high resolution and anti- noise. Good reconstruction results are given to validate the proposed imaging method.

  13. Holographic leaky-wave metasurfaces for dual-sensor imaging.

    PubMed

    Li, Yun Bo; Li, Lian Lin; Cai, Ben Geng; Cheng, Qiang; Cui, Tie Jun

    2015-01-01

    Metasurfaces have huge potentials to develop new type imaging systems due to their abilities of controlling electromagnetic waves. Here, we propose a new method for dual-sensor imaging based on cross-like holographic leaky-wave metasurfaces which are composed of hybrid isotropic and anisotropic surface impedance textures. The holographic leaky-wave radiations are generated by special impedance modulations of surface waves excited by the sensor ports. For one independent sensor, the main leaky-wave radiation beam can be scanned by frequency in one-dimensional space, while the frequency scanning in the orthogonal spatial dimension is accomplished by the other sensor. Thus, for a probed object, the imaging plane can be illuminated adequately to obtain the two-dimensional backward scattered fields by the dual-sensor for reconstructing the object. The relativity of beams under different frequencies is very low due to the frequency-scanning beam performance rather than the random beam radiations operated by frequency, and the multi-illuminations with low relativity are very appropriate for multi-mode imaging method with high resolution and anti- noise. Good reconstruction results are given to validate the proposed imaging method. PMID:26658471

  14. Holographic leaky-wave metasurfaces for dual-sensor imaging

    PubMed Central

    Li, Yun Bo; Li, Lian Lin; Cai, Ben Geng; Cheng, Qiang; Cui, Tie Jun

    2015-01-01

    Metasurfaces have huge potentials to develop new type imaging systems due to their abilities of controlling electromagnetic waves. Here, we propose a new method for dual-sensor imaging based on cross-like holographic leaky-wave metasurfaces which are composed of hybrid isotropic and anisotropic surface impedance textures. The holographic leaky-wave radiations are generated by special impedance modulations of surface waves excited by the sensor ports. For one independent sensor, the main leaky-wave radiation beam can be scanned by frequency in one-dimensional space, while the frequency scanning in the orthogonal spatial dimension is accomplished by the other sensor. Thus, for a probed object, the imaging plane can be illuminated adequately to obtain the two-dimensional backward scattered fields by the dual-sensor for reconstructing the object. The relativity of beams under different frequencies is very low due to the frequency-scanning beam performance rather than the random beam radiations operated by frequency, and the multi-illuminations with low relativity are very appropriate for multi-mode imaging method with high resolution and anti- noise. Good reconstruction results are given to validate the proposed imaging method. PMID:26658471

  15. Scenario development for the Waste Isolation Pilot Plant: Building confidence in the assessment

    SciTech Connect

    Galson, D.A.; Swift, P.N.

    1994-03-01

    Scenario developments is part of the iterative performance assessment (PA) process for the Waste Isolation Pilot Plant (WIPP). Scenario development for the WIPP has been the subject of intense external review, and is certain to be the subject of continued scrutiny as the project proceeds toward regulatory compliance. The principal means of increasing confidence is this aspect of the PA will be through the use of a systematic and thorough procedure toward developing the scenarios and conceptual models on which the assessment is to be based. Early and ongoing interaction with project reviewers can assist with confidence building. Quality of argument and clarity of presentation in PA will be of key concern. Appropriate tools are required for documenting and tracking assumptions, through a single assessment phase, and between iterative assessment phases. Risks associated with future human actions are of particular concern to the WIPP project, and international consensus on the principles for incorporation of future human actions in assessments would be valuable.

  16. Characterization of leaky faults: Study of water flow in aquifer-fault-aquifer systems

    NASA Astrophysics Data System (ADS)

    Shan, Chao; Javandel, Iraj; Witherspoon, Paul A.

    Leaky faults provide important flow paths for fluids to move underground. It is often necessary to characterize such faults in engineering projects such as deep well injection of waste liquids, underground natural gas storage, and radioactive waste isolation. To provide this characterization, analytical solutions are presented for groundwater flow through saturated aquifer-fault-aquifer systems assuming that both the aquifers and the fault are homogeneous and that the fault has an insignificant effect on aquifer hydraulic properties. Three different conditions are considered: (1) drawdown in the unpumped aquifer is negligibly small; (2) drawdown in the unpumped aquifer is significant, and the two aquifers have the same diffusivity; and (3) drawdown in the unpumped aquifer is significant, and the two aquifers have different diffusivities. Methods are presented to determine the fault transmissivity from pumping test data.

  17. Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals

    PubMed Central

    Tapiolas, Dianne; Motti, Cherie A.; Foret, Sylvain; Tebben, Jan; Willis, Bette L.; Bourne, David G.

    2016-01-01

    Bacterial communities associated with healthy corals produce antimicrobial compounds that inhibit the colonization and growth of invasive microbes and potential pathogens. To date, however, bacteria-derived antimicrobial molecules have not been identified in reef-building corals. Here, we report the isolation of an antimicrobial compound produced by Pseudovibrio sp. P12, a common and abundant coral-associated bacterium. This strain was capable of metabolizing dimethylsulfoniopropionate (DMSP), a sulfur molecule produced in high concentrations by reef-building corals and playing a role in structuring their bacterial communities. Bioassay-guided fractionation coupled with nuclear magnetic resonance (NMR) and mass spectrometry (MS), identified the antimicrobial as tropodithietic acid (TDA), a sulfur-containing compound likely derived from DMSP catabolism. TDA was produced in large quantities by Pseudovibrio sp., and prevented the growth of two previously identified coral pathogens, Vibrio coralliilyticus and V. owensii, at very low concentrations (0.5 μg/mL) in agar diffusion assays. Genome sequencing of Pseudovibrio sp. P12 identified gene homologs likely involved in the metabolism of DMSP and production of TDA. These results provide additional evidence for the integral role of DMSP in structuring coral-associated bacterial communities and underline the potential of these DMSP-metabolizing microbes to contribute to coral disease prevention. PMID:27602265

  18. Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals.

    PubMed

    Raina, Jean-Baptiste; Tapiolas, Dianne; Motti, Cherie A; Foret, Sylvain; Seemann, Torsten; Tebben, Jan; Willis, Bette L; Bourne, David G

    2016-01-01

    Bacterial communities associated with healthy corals produce antimicrobial compounds that inhibit the colonization and growth of invasive microbes and potential pathogens. To date, however, bacteria-derived antimicrobial molecules have not been identified in reef-building corals. Here, we report the isolation of an antimicrobial compound produced by Pseudovibrio sp. P12, a common and abundant coral-associated bacterium. This strain was capable of metabolizing dimethylsulfoniopropionate (DMSP), a sulfur molecule produced in high concentrations by reef-building corals and playing a role in structuring their bacterial communities. Bioassay-guided fractionation coupled with nuclear magnetic resonance (NMR) and mass spectrometry (MS), identified the antimicrobial as tropodithietic acid (TDA), a sulfur-containing compound likely derived from DMSP catabolism. TDA was produced in large quantities by Pseudovibrio sp., and prevented the growth of two previously identified coral pathogens, Vibrio coralliilyticus and V. owensii, at very low concentrations (0.5 μg/mL) in agar diffusion assays. Genome sequencing of Pseudovibrio sp. P12 identified gene homologs likely involved in the metabolism of DMSP and production of TDA. These results provide additional evidence for the integral role of DMSP in structuring coral-associated bacterial communities and underline the potential of these DMSP-metabolizing microbes to contribute to coral disease prevention. PMID:27602265

  19. Earthquake Resilient Tall Reinforced Concrete Buildings at Near-Fault Sites Using Base Isolation and Rocking Core Walls

    NASA Astrophysics Data System (ADS)

    Calugaru, Vladimir

    This dissertation pursues three main objectives: (1) to investigate the seismic response of tall reinforced concrete core wall buildings, designed following current building codes, subjected to pulse type near-fault ground motion, with special focus on the relation between the characteristics of the ground motion and the higher-modes of response; (2) to determine the characteristics of a base isolation system that results in nominally elastic response of the superstructure of a tall reinforced concrete core wall building at the maximum considered earthquake level of shaking; and (3) to demonstrate that the seismic performance, cost, and constructability of a base-isolated tall reinforced concrete core wall building can be significantly improved by incorporating a rocking core-wall in the design. First, this dissertation investigates the seismic response of tall cantilever wall buildings subjected to pulse type ground motion, with special focus on the relation between the characteristics of ground motion and the higher-modes of response. Buildings 10, 20, and 40 stories high were designed such that inelastic deformation was concentrated at a single flexural plastic hinge at their base. Using nonlinear response history analysis, the buildings were subjected to near-fault seismic ground motions as well as simple close-form pulses, which represented distinct pulses within the ground motions. Euler-Bernoulli beam models with lumped mass and lumped plasticity were used to model the buildings. Next, this dissertation investigates numerically the seismic response of six seismically base-isolated (BI) 20-story reinforced concrete buildings and compares their response to that of a fixed-base (FB) building with a similar structural system above ground. Located in Berkeley, California, 2 km from the Hayward fault, the buildings are designed with a core wall that provides most of the lateral force resistance above ground. For the BI buildings, the following are investigated

  20. Isotope effects accompanying evaporation of water from leaky containers.

    PubMed

    Rozanski, Kazimierz; Chmura, Lukasz

    2008-03-01

    Laboratory experiments aimed at quantifying isotope effects associated with partial evaporation of water from leaky containers have been performed under three different settings: (i) evaporation into dry atmosphere, performed in a dynamic mode, (ii) evaporation into dry atmosphere, performed in a static mode, and (iii) evaporation into free laboratory atmosphere. The results demonstrate that evaporative enrichment of water stored in leaky containers can be properly described in the framework of the Craig-Gordon evaporation model. The key parameter controlling the degree of isotope enrichment is the remaining fraction of water in the leaking containers. Other factors such as temperature, relative humidity, or extent of kinetic fractionation play only minor roles. Satisfactory agreement between observed and predicted isotope enrichments for both (18)O and (2)H in experiments for the case of evaporation into dry atmosphere could be obtained only when molecular diffusivity ratios of isotope water molecules as suggested recently by Cappa et al. [J. Geophys. Res., 108, 4525-4535, (2003).] were adopted. However, the observed and modelled isotope enrichments for (2)H and (18)O could be reconciled also for the ratios of molecular diffusivities obtained by Merlivat [J. Chem. Phys., 69, 2864-2871 (1978).], if non-negligible transport resistance in the viscous liquid sub-layer adjacent to the evaporating surface is considered. The evaporation experiments revealed that the loss of mass of water stored in leaky containers in the order of 1%, will lead to an increase of the heavy isotope content in this water by ca. 0.35 and 1.1 per thousand, for delta (18)O and delta (2)H, respectively. PMID:18320427

  1. Feasibility of graphene CRLH metamaterial waveguides and leaky wave antennas

    NASA Astrophysics Data System (ADS)

    Chu, Derrick A.; Hon, Philip W. C.; Itoh, Tatsuo; Williams, Benjamin S.

    2016-07-01

    The feasibility of composite right/left-handed (CRLH) metamaterial waveguides based upon graphene plasmons is demonstrated via numerical simulation. Designs are presented that operate in the terahertz frequency range along with their various dimensions. Dispersion relations, radiative and free-carrier losses, and free-carrier based tunability are characterized. Finally, the radiative characteristics are evaluated, along with its feasibility for use as a leaky-wave antenna. While CRLH waveguides are feasible in the terahertz range, their ultimate utility will require precise nanofabrication, and excellent quality graphene to mitigate free-carrier losses.

  2. DISPERSION OF ROOF-TOP EMISSIONS FROM ISOLATED BUILDINGS. A WIND TUNNEL STUDY

    EPA Science Inventory

    A fluid modeling study of the dispersion of roof-top emissions from rectangular buildings was performed in the meteorological wind tunnel of the EPA Fluid Modeling Facility. The basic building shape was a 0.18 meter cube. Variations included a building twice as wide and buildings...

  3. Ultrasonic Lateral Displacement Sensor for Health Monitoring in Seismically Isolated Buildings

    PubMed Central

    Matsuya, Iwao; Matsumoto, Fumiya; Ihara, Ikuo

    2015-01-01

    An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a receiver and several transmitters. The transmitters are immobilized at a fixed point, whereas the receiver set-up is separately arranged on the opposite side. In order to improve measurement accuracy, a correction method that utilizes polynomial approximation is introduced. The difference between the corrected lateral displacement and the reference displacement is estimated to be 0.2 mm at maximum for the two transmitters system. A good responsiveness is demonstrated by conducting a dynamic response experiment. When five transmitters are arranged, their measurement range is easily extended up to ±60 mm with an accuracy of 0.7 mm. In both cases, the fluctuations to the measurement ranges show less than 1%. These results indicate that the developed sensor system is useful for measuring relative lateral displacement of a seismically isolated building in the field of structural health monitoring. PMID:26184220

  4. Ultrasonic Lateral Displacement Sensor for Health Monitoring in Seismically Isolated Buildings.

    PubMed

    Matsuya, Iwao; Matsumoto, Fumiya; Ihara, Ikuo

    2015-01-01

    An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a receiver and several transmitters. The transmitters are immobilized at a fixed point, whereas the receiver set-up is separately arranged on the opposite side. In order to improve measurement accuracy, a correction method that utilizes polynomial approximation is introduced. The difference between the corrected lateral displacement and the reference displacement is estimated to be 0.2 mm at maximum for the two transmitters system. A good responsiveness is demonstrated by conducting a dynamic response experiment. When five transmitters are arranged, their measurement range is easily extended up to ±60 mm with an accuracy of 0.7 mm. In both cases, the fluctuations to the measurement ranges show less than 1%. These results indicate that the developed sensor system is useful for measuring relative lateral displacement of a seismically isolated building in the field of structural health monitoring. PMID:26184220

  5. Response of high-rise and base-isolated buildings to a hypothetical M w 7.0 blind thrust earthquake

    USGS Publications Warehouse

    Heaton, T.H.; Hall, J.F.; Wald, D.J.; Halling, M.W.

    1995-01-01

    High-rise flexible-frame buildings are commonly considered to be resistant to shaking from the largest earthquakes. In addition, base isolation has become increasingly popular for critical buildings that should still function after an earthquake. How will these two types of buildings perform if a large earthquake occurs beneath a metropolitan area? To answer this question, we simulated the near-source ground motions of a Mw 7.0 thrust earthquake and then mathematically modeled the response of a 20-story steel-frame building and a 3-story base-isolated building. The synthesized ground motions were characterized by large displacement pulses (up to 2 meters) and large ground velocities. These ground motions caused large deformation and possible collapse of the frame building, and they required exceptional measures in the design of the base-isolated building if it was to remain functional.

  6. Performance-based semi-active control algorithm for protecting base isolated buildings from near-fault earthquakes

    NASA Astrophysics Data System (ADS)

    Mehrparvar, Behnam; Khoshnoudian, Taramarz

    2012-03-01

    Base isolated structures have been found to be at risk in near-fault regions as a result of long period pulses that may exist in near-source ground motions. Various control strategies, including passive, active and semi-active control systems, have been investigated to overcome this problem. This study focuses on the development of a semi-active control algorithm based on several performance levels anticipated from an isolated building during different levels of ground shaking corresponding to various earthquake hazard levels. The proposed performance-based algorithm is based on a modified version of the well-known semi-active skyhook control algorithm. The proposed control algorithm changes the control gain depending on the level of shaking imposed on the structure. The proposed control system has been evaluated using a series of analyses performed on a base isolated benchmark building subjected to seven pairs of scaled ground motion records. Simulation results show that the newly proposed algorithm is effective in improving the structural and nonstructural performance of the building for selected earthquakes.

  7. Periodically forced leaky integrate-and-fire model.

    PubMed

    Pakdaman, K

    2001-04-01

    The discharge pattern of periodically forced leaky integrate-and-fire models is studied. While previous analyses have been mainly concerned with the response of this model to sinusoidal stimulation, our results hold for arbitrary periodic inputs. It is shown that, for any periodic input, the map representing the relation between input phases at consecutive discharge times can be restricted to a piecewise continuous, orientation preserving circle map. This implies that (i) the rotation number is well defined and independent of the initial condition, and (ii) in the same way as for sinusoidal forcing, other forms of periodic stimuli can evoke only one of four types of response, namely, phase locking, quasiperiodic discharges, nonchaotic aperiodic firing, and termination of the discharge after a finite number of firings. PMID:11308877

  8. In-situ Mechanical Manipulation of Wellbore Cements as a Solution to Leaky Wells

    NASA Astrophysics Data System (ADS)

    Kupresan, D.; Radonjic, M.; Heathman, J.

    2013-12-01

    Wellbore cement provides casing support, zonal isolation, and casing protection from corrosive fluids, which are essential for wellbore integrity. Cements can undergo one or more forms of failure such as debonding at cement/formation and cement/casing interface, fracturing and defects within cement matrix. Failures and defects within cement will ultimately lead to fluids migration, resulting in inter-zonal fluid migration and premature well abandonment. There are over 27,000 abandoned oil and gas wells only in The Gulf of Mexico (some of them dating from the late 1940s) with no gas leakage monitoring. Cement degradation linked with carbon sequestration can potentially lead to contamination of fresh water aquifers with CO2. Gas leaks can particularly be observed in deviated wells used for hydraulic fracking (60% leakage rate as they age) as high pressure fracturing increases the potential for migration pathways. Experimental method utilized in this study enables formation of impermeable seals at interfaces present in a wellbore by mechanically manipulating wellbore cement. Preliminary measurements obtained in bench scale experiments demonstrate that an impermeable cement/formation and cement/casing interface can be obtained. In post-modified cement, nitrogen gas flow-through experiments showed complete zonal isolation and no permeability in samples with pre-engineered microannulus. Material characterization experiments of modified cement revealed altered microstructural properties of cement as well as changes in mineralogical composition. Calcium-silicate-hydrate (CSH), the dominant mineral in hydrated cement which provides low permeability of cement, was modified as a result of cement pore water displacement, resulting in more dense structures. Calcium hydroxide (CH), which is associated with low resistance of cement to acidic fluids and therefore detrimental in most wellbore cements, was almost completely displaced and/or integrated in CSH as a result of

  9. Optimal Performance of Buildings Isolated By Shape-Memory-Alloy-Rubber-Bearing (SMARB) Under Random Earthquakes

    NASA Astrophysics Data System (ADS)

    Das, Sumanta; Mishra, Sudib K.

    2014-05-01

    Shape Memory Alloy (SMA)-based bearing has been proposed recently for improved base isolation by optimal choice of its transformation strength. Presently, superior performances of the Shape-Memory-Alloy-Rubber-Bearing (SMARB) over the elastomeric bearing are established in mitigating seismic vibration under constraint on maximum isolator displacement. The optimal transformation strengths are proposed through constrained optimization based on stochastic responses. Numerical simulation reveals that Lead Rubber Bearings (LRB) either fails to provide feasible parameters or leads to large floor acceleration, compromising the isolation efficiency. Contrarily, optimal SMARB can efficiently enforce such constraint without greatly affecting the isolation efficiency. Evidence of robustness of SMARB over LRB is also established.

  10. Modeling of general 1-D periodic leaky-wave antennas in layered media using EIGER.

    SciTech Connect

    Wilton, Donald R.; Basilio, Lorena I.; Celepcikay, Ferhat T.; Johnson, William Arthur; Baccarelli, Paolo; Valerio, Guido; Paulotto, Simone; Langston, William L.; Jackson, David R.

    2010-09-01

    This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER{trademark} code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case.

  11. Modeling of general 1-D periodic leaky-wave antennas in layered media with EIGER.

    SciTech Connect

    Wilton, Donald R.; Basilio, Lorena I.; Celepcikay, F. T.; Johnson, William Arthur; Baccarelli, Paolo; Valerio, G.; Paulotto, Simone; Langston, William L.; Jackson, David R.

    2010-06-01

    This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER{trademark} code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case.

  12. Bringing It to the Teachers: Building a Professional Network among Teachers in Isolated Schools

    ERIC Educational Resources Information Center

    McLean, Fiona M.; Dixon, Roselyn M.; Verenikina, Irina

    2014-01-01

    Teachers in isolated schools are often under-resourced and overwhelmed with additional pressures. Teaching in an isolated community can sometimes challenge teachers' skills and knowledge, particularly when additional pressures such as behavioural issues associated with students with Oppositional Defiant Disorder (ODD) like behaviours are present.…

  13. Mechanical expansion of steel tubing as a solution to leaky wellbores.

    PubMed

    Radonjic, Mileva; Kupresan, Darko

    2014-01-01

    Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe (casing), and protects metal components from corrosive fluids. These are essential for uncompromised wellbore integrity. Cements can undergo multiple forms of failure, such as debonding at the cement/rock and cement/metal interfaces, fracturing, and defects within the cement matrix. Failures and defects within the cement will ultimately lead to fluid migration, resulting in inter-zonal fluid migration and premature well abandonment. Currently, there are over 1.8 million operating wells worldwide and over one third of these wells have leak related problems defined as Sustained Casing Pressure (SCP). The focus of this research was to develop an experimental setup at bench-scale to explore the effect of mechanical manipulation of wellbore casing-cement composite samples as a potential technology for the remediation of gas leaks. The experimental methodology utilized in this study enabled formation of an impermeable seal at the pipe/cement interface in a simulated wellbore system. Successful nitrogen gas flow-through measurements demonstrated that an existing microannulus was sealed at laboratory experimental conditions and fluid flow prevented by mechanical manipulation of the metal/cement composite sample. Furthermore, this methodology can be applied not only for the remediation of leaky wellbores, but also in plugging and abandonment procedures as well as wellbore completions technology, and potentially preventing negative impacts of wellbores on subsurface and surface environments. PMID:25490436

  14. Final report on LDRD project :leaky-mode VCSELs for photonic logic circuits.

    SciTech Connect

    Hargett, Terry W.; Hadley, G. Ronald; Serkland, Darwin Keith; Blansett, Ethan L.; Geib, Kent Martin; Sullivan, Charles Thomas; Keeler, Gordon Arthur; Bauer, Thomas; Ongstand, Andrea; Medrano, Melissa R.; Peake, Gregory Merwin; Montano, Victoria A.

    2005-11-01

    This report describes the research accomplishments achieved under the LDRD Project ''Leaky-mode VCSELs for photonic logic circuits''. Leaky-mode vertical-cavity surface-emitting lasers (VCSELs) offer new possibilities for integration of microcavity lasers to create optical microsystems. A leaky-mode VCSEL output-couples light laterally, in the plane of the semiconductor wafer, which allows the light to interact with adjacent lasers, modulators, and detectors on the same wafer. The fabrication of leaky-mode VCSELs based on effective index modification was proposed and demonstrated at Sandia in 1999 but was not adequately developed for use in applications. The aim of this LDRD has been to advance the design and fabrication of leaky-mode VCSELs to the point where initial applications can be attempted. In the first and second years of this LDRD we concentrated on overcoming previous difficulties in the epitaxial growth and fabrication of these advanced VCSELs. In the third year, we focused on applications of leaky-mode VCSELs, such as all-optical processing circuits based on gain quenching.

  15. Analysis and suppression of side radiation in leaky SAW resonators.

    PubMed

    Inoue, Shogo; Tsutsumi, Jun; Matsuda, Takashi; Ueda, Masanori; Ikata, Osamu; Satoh, Yoshio

    2007-08-01

    This paper discusses side acoustic radiation in leaky surface acoustic wave (LSAW) resonators on rotated Y-cut lithium tantalite substrates. The mechanism behind side radiation, which causes a large insertion loss, is analyzed by using the scalar potential theory. This analysis reveals that side radiation occurs when the guiding condition is not satisfied, and the LSAW most strongly radiates at the frequency in which the LSAW velocities in the grating and busbar regions approximately correspond to each other. Based on these results, we propose a "narrow finger structure," which satisfies the guiding condition and drastically suppresses the side radiation. Experiments show that the resonance Q of the proposed structure drastically improves to over 1000 by suppressing the side radiation, which is three times higher than for a conventional structure. Applying the proposed resonators to the ladder-type SAW filters, ultra-low-loss and steep cut-off characteristics are achieved in the range of 800 MHz and 1.9 GHz. PMID:17703674

  16. Information transfer by leaky, heterogeneous, protein kinase signaling systems

    PubMed Central

    Voliotis, Margaritis; Perrett, Rebecca M.; McWilliams, Chris; McArdle, Craig A.; Bowsher, Clive G.

    2014-01-01

    Cells must sense extracellular signals and transfer the information contained about their environment reliably to make appropriate decisions. To perform these tasks, cells use signal transduction networks that are subject to various sources of noise. Here, we study the effects on information transfer of two particular types of noise: basal (leaky) network activity and cell-to-cell variability in the componentry of the network. Basal activity is the propensity for activation of the network output in the absence of the signal of interest. We show, using theoretical models of protein kinase signaling, that the combined effect of the two types of noise makes information transfer by such networks highly vulnerable to the loss of negative feedback. In an experimental study of ERK signaling by single cells with heterogeneous ERK expression levels, we verify our theoretical prediction: In the presence of basal network activity, negative feedback substantially increases information transfer to the nucleus by both preventing a near-flat average response curve and reducing sensitivity to variation in substrate expression levels. The interplay between basal network activity, heterogeneity in network componentry, and feedback is thus critical for the effectiveness of protein kinase signaling. Basal activity is widespread in signaling systems under physiological conditions, has phenotypic consequences, and is often raised in disease. Our results reveal an important role for negative feedback mechanisms in protecting the information transfer function of saturable, heterogeneous cell signaling systems from basal activity. PMID:24395805

  17. Semi-active seismic response control of base-isolated building with MR damper

    NASA Astrophysics Data System (ADS)

    Soda, Satsuya; Kusumoto, Haruhide; Chatani, Ryosuke; Iwata, Norio; Fujitani, Hideo; Shiozaki, Yoichi; Hiwatashi, Takeshi

    2003-07-01

    This study deals with a shake table test on a three-story base-isolated steel frame. The frame rests on four roller bearings for isolation and is equipped with four laminated rubbers as shear spring. An MR damper is used in the test to perform semi-active seismic response control. The basic control algorithm applied in the study is to simulate the load-deflection of an origin-restoring friction damper (ORFD) which is a sort of friction damper that looses its resistance when it moves toward the origin, making sure for the base-isolated system to minimize residual displacement even after an extremely strong ground motion. Also attempted is a hybrid type control that superposes viscous damping on the ORFD when the damper moves from the peak displacement toward the origin.

  18. Isolation of halimedatrial: chemical defense adaptation in the calcareous reef-building alga halimeda.

    PubMed

    Paul, V J; Fenical, W

    1983-08-19

    Halimedatrial, a structurally unprecedented diterpenoid trialdehyde, has been identified as the major secondary metabolite in six species of the calcareous reef-building alga Halimeda. In laboratory bioassays, halimedatrial is toxic toward reef fishes, significantly reduces feeding in herbivorous fishes, and has cytotoxic and antimicrobial activities. The widespread occurrence of halimedatrial and its potent biological activities suggest that this metabolite represents a chemical defense adaptation in this pantropical marine alga. PMID:17829534

  19. Simulating soil atmosphere above a leaky CCS deposit

    NASA Astrophysics Data System (ADS)

    Schack-Kirchner, Helmer; Maier, Martin

    2015-04-01

    The escape of CO2 at the surface above a leaky geological deposit of carbon dioxide can be a fumarole-like point source or a subsurface plume distributing the gas over a larger area. In the latter case the lost CO2 from the deposit is added to the soil respiration as a quasi one-dimensional non-equimolar gas flux. Whether such an additional flux leads to inhibitory high levels of soil CO2 combined with a rather complete advective displacement of O2 or simply changes the diffusion characteristics in a more or less normal soil atmosphere depends for a given gas diffusivity and permeability on the ratio between the equimolar (respiratory) and the non-equimolar (leak based) flux of CO2. We tested the effecs by parametrization of a conceptual soil model consisting of capillaries filled either with soil air or water joining the soil air and the above-ground atmosphere. Soil atmosphere was simulated by combining a numerical solution of the Dusty-Gas model and a simple gas diffusion model in the water filled capillaries in an iterative process until Argon as noble gas is stagnant. The results show that in soils with high gas permeability even non-equimolar CO2 fluxes more than twice the soil respiration can be transferred to the surface without spectacular changes in soil-air pressure or O2 displacement. However, even low extra CO2 fluxes change significantly the gradient ratio of O2 and CO2 and stress soil aeration which is for many forest ecosystems a limiting factor of root growth.

  20. Coupled Particle Transport and Pattern Formation in a Nonlinear Leaky-Box Model

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.; El-Nemr, K. W.; Baird, J. K.

    2009-01-01

    Effects of particle-particle coupling on particle characteristics in nonlinear leaky-box type descriptions of the acceleration and transport of energetic particles in space plasmas are examined in the framework of a simple two-particle model based on the Fokker-Planck equation in momentum space. In this model, the two particles are assumed coupled via a common nonlinear source term. In analogy with a prototypical mathematical system of diffusion-driven instability, this work demonstrates that steady-state patterns with strong dependence on the magnetic turbulence but a rather weak one on the coupled particles attributes can emerge in solutions of a nonlinearly coupled leaky-box model. The insight gained from this simple model may be of wider use and significance to nonlinearly coupled leaky-box type descriptions in general.

  1. Continuous leaky-wave scanning using periodically modulated spoof plasmonic waveguide

    NASA Astrophysics Data System (ADS)

    Kong, Gu Sheng; Ma, Hui Feng; Cai, Ben Geng; Cui, Tie Jun

    2016-07-01

    The plasmonic waveguide made of uniform corrugated metallic strip can support and guide spoof surface plasmon polaritons (SSPPs) with high confinements. Here, we propose periodically-modulated plasmonic waveguide composed of non-uniform corrugated metallic strip to convert SSPPs to radiating waves, in which the main beam of radiations can steer continuously as the frequency changes. To increase the radiation efficiency of the periodically-modulated plasmonic waveguide at the broadside, an asymmetrical plasmonic waveguide is further presented to reduce the reflections and realize continuous leaky-wave scanning. Both numerical simulations and experimental results show that the radiation efficiency can be improved greatly and the main beam of leaky-wave radiations can steer from the backward quadrant to the forward quadrant, passing through the broadside direction, which generally is difficult to be realized by the common leaky-wave antennas.

  2. Improvement in the quality factors for photonic crystal nanocavities via visualization of the leaky components.

    PubMed

    Nakamura, Tatsuya; Takahashi, Yasushi; Tanaka, Yoshinori; Asano, Takashi; Noda, Susumu

    2016-05-01

    A method that simply improves the quality (Q) factors of two-dimensional photonic crystal nanocavities using a three-dimensional finite-difference time domain calculation is described. The leaky area for a high-Q nanocavity mode is visualized in a real cavity structure by extracting the leaky components within a light cone in momentum space and by transferring them back into real space using an inverse Fourier transformation. The Q factor is remarkably improved by appropriately shifting the positions of air holes at the leaky area. We design three-missing-air-hole and zero-cell-defect nanocavities with Q factors of 5,000,000 and 1,700,000, respectively, for demonstration. PMID:27137567

  3. Analytical model for the excitation of leaky surface plasmon polaritons in the attenuated total reflection configuration

    NASA Astrophysics Data System (ADS)

    Jia, Hongwei; Xie, Yunya; Liu, Haitao; Zhong, Ying

    2016-05-01

    We propose a fully-analytical model for the excitation of leaky surface plasmon polariton (SPP) in the attenuated total reflection (ATR) configuration under illumination by a finite-width beam of electromagnetic wave. The model is built up on the basis of the general unconjugated-form reciprocity theorem and is able to predict the excitation amplitude and phase of the leaky SPP at a quantitative level. The validity of the model is carefully supported through a comparison with the numerical results obtained with the mode orthogonality. With the model a physical understanding of the resonant excitation of the leaky SPP is achieved and the optimal parameters such as the incidence angle and the beam width to ensure an efficient SPP excitation are demonstrated for design tasks.

  4. Continuous leaky-wave scanning using periodically modulated spoof plasmonic waveguide

    PubMed Central

    Kong, Gu Sheng; Ma, Hui Feng; Cai, Ben Geng; Cui, Tie Jun

    2016-01-01

    The plasmonic waveguide made of uniform corrugated metallic strip can support and guide spoof surface plasmon polaritons (SSPPs) with high confinements. Here, we propose periodically-modulated plasmonic waveguide composed of non-uniform corrugated metallic strip to convert SSPPs to radiating waves, in which the main beam of radiations can steer continuously as the frequency changes. To increase the radiation efficiency of the periodically-modulated plasmonic waveguide at the broadside, an asymmetrical plasmonic waveguide is further presented to reduce the reflections and realize continuous leaky-wave scanning. Both numerical simulations and experimental results show that the radiation efficiency can be improved greatly and the main beam of leaky-wave radiations can steer from the backward quadrant to the forward quadrant, passing through the broadside direction, which generally is difficult to be realized by the common leaky-wave antennas. PMID:27404740

  5. Non-universal behavior of leaky surface waves in a one dimensional asymmetric plasmonic grating

    NASA Astrophysics Data System (ADS)

    Vempati, Sesha; Iqbal, Tahir; Afsheen, Sumera

    2015-07-01

    We report on a non-universal behavior of leaky surface plasmon waves on asymmetric (Si/Au/analyte of different height) 1D grating through numerical modelling. The occurrence of the leaky surface wave was maximized (suppressing the Fabry-Perot cavity mode), which can be identified in a reflection spectrum through characteristic minimum. Beyond a specific analyte height (h), new sets of surface waves emerge, each bearing a unique reflection minimum. Furthermore, all of these minima depicted a red-shift before saturating at higher h values. This saturation is found to be non-universal despite the close association with their origin (being leaky surface waves). This behavior is attributed to the fundamental nature and the origin of the each set. Additionally, all of the surface wave modes co-exit at relatively higher h values.

  6. Analysis and Synthesis of Leaky-Wave Devices in Planar Technology

    NASA Astrophysics Data System (ADS)

    Martinez Ros, Alejandro Javier

    The work developed along this doctoral thesis has been focused on the analysis and synthesis of microwave devices in planar technology. In particular, several types of devices based on the radiation mechanism of leaky waves have been studied. Typically, the radiation properties in leaky-wave devices are determined by the complex propagation constant of the leaky mode, wherein the phase constant is responsible for the pointing angle and the leakage rate for the intensity of the radiated fields. In this manner, by controlling both amplitude and phase of the leaky mode, an effective control over the device's radiation diagram can be obtained. Moreover, with the purpose of efficiently obtaining the leaky mode's radiation properties as function of the main geometrical parameters of the structure, several modal tools based on the transverse resonance analysis of the structure have been performed. In order to demonstrate this simultaneous control over the complex propagation constant in planar technology, several types of leaky-wave devices, including antennas (LWAs), multiplexors and near-field focusing systems, have been designed and manufactured in the technology of substrate integrated waveguide (SIW). This recently proposed technology, allows the design of devices based on classical waveguide technology with standard manufacturing techniques used for printed circuit board (PCB) designs. In this way, most of the parts that form a communication system can be integrated into a single substrate, thus reducing its cost and providing a more robust and compact device, which has less losses compared to other planar technologies such as the microstrip. El trabajo llevado a cabo durante la realizacion de esta tesis doctoral, se ha centrado en el analisis y sintesis de dispositivos de microondas en tecnologia planar. En concreto, se han estudiado diferentes tipos de dispositivos basados en radiacion por ondas de fuga "leaky waves", en los cuales las propiedades de radiacion

  7. Continuous leaky-wave scanning using periodically modulated spoof plasmonic waveguide.

    PubMed

    Kong, Gu Sheng; Ma, Hui Feng; Cai, Ben Geng; Cui, Tie Jun

    2016-01-01

    The plasmonic waveguide made of uniform corrugated metallic strip can support and guide spoof surface plasmon polaritons (SSPPs) with high confinements. Here, we propose periodically-modulated plasmonic waveguide composed of non-uniform corrugated metallic strip to convert SSPPs to radiating waves, in which the main beam of radiations can steer continuously as the frequency changes. To increase the radiation efficiency of the periodically-modulated plasmonic waveguide at the broadside, an asymmetrical plasmonic waveguide is further presented to reduce the reflections and realize continuous leaky-wave scanning. Both numerical simulations and experimental results show that the radiation efficiency can be improved greatly and the main beam of leaky-wave radiations can steer from the backward quadrant to the forward quadrant, passing through the broadside direction, which generally is difficult to be realized by the common leaky-wave antennas. PMID:27404740

  8. Nanoporous leaky waveguide based chemical and biological sensors with broadband spectroscopy

    NASA Astrophysics Data System (ADS)

    Qi, Zhi-Mei; Honma, Itaru; Zhou, Haoshen

    2007-01-01

    Here the authors demonstrate spectral optical chemical and biological sensors based on a nanoporous thin-film leaky waveguide that were fabricated by dip coating the gold-layer-covered glass substrate from the colloidal TiO2 solution. The sensor operates by interrogating the resonance wavelengths for the leaky modes in a broad bandwidth using the Kretschmann configuration. Sensitivities of the sensor to refractive index of liquid and protein adsorption were investigated and compared with the spectral surface plasmon resonance sensors. The best fitting to the experimental data was carried out with the Fresnel equations, and thickness and porosity of the nanoporous waveguiding layer were determined.

  9. Mycobacterium terrae isolated from indoor air of a moisture-damaged building induces sustained biphasic inflammatory response in mouse lungs.

    PubMed Central

    Jussila, Juha; Komulainen, Hannu; Huttunen, Kati; Roponen, Marjut; Iivanainen, Eila; Torkko, Pirjo; Kosma, Veli-Matti; Pelkonen, Jukka; Hirvonen, Maija-Riitta

    2002-01-01

    Occupants in moisture-damaged buildings suffer frequently from respiratory symptoms. This may be partly due to the presence of abnormal microbial growth or the altered microbial flora in the damaged buildings. However, the specific effects of the microbes on respiratory health and the way they provoke clinical manifestations are poorly understood. In the present study, we exposed mice via intratracheal instillation to a single dose of Mycobacterium terrae isolated from the indoor air of a moisture-damaged building (1 X 10(7), 5 X 10(7), or 1 X 10(8) microbes). Inflammation and toxicity in lungs were evaluated 2 hr later. The time course of the effects was assessed with the dose of 1 X 10(8) bacterial cells for up to 28 days. M. terrae caused a sustained biphasic inflammation in mouse lungs. The characteristic features for the first phase, which lasted from 6 hr to 3 days, were elevated proinflammatory cytokine [i.e., tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6)] levels in the bronchoalveolar lavage fluid (BALF). TNF-alpha was produced in the lungs more intensively than was IL-6. Neutrophils were the most abundant cells in the airways during the first phase, although their numbers in BALF remained elevated up to 21 days. The characteristics of the second phase, which lasted from 7 to 28 days, were elevated TNF-alpha levels in BALF, expression of inducible nitric oxide synthase in BAL cells, and recruitment of mononuclear cells such as lymphocytes and macrophages into the airways. Moreover, total protein, albumin, and lactate dehydrogenase concentrations were elevated in both phases in BALF. The bacteria were detected in lungs up to 28 days. In summary, these observations indicate that M. terrae is capable of provoking a sustained, biphasic inflammation in mouse lungs and can cause a moderate degree of cytotoxicity. Thus, M. terrae can be considered a species with potential to adversely affect the health of the occupants of moisture

  10. Seismic Response of a Full-scale 5-story Steel Frame Building Isolated by Triple Pendulum Bearings under Three-Dimensional Excitations

    NASA Astrophysics Data System (ADS)

    Dao, Nhan Dinh

    A full-scale shake table test of a 5-story steel moment frame building was carried out as part of a collaborative NEES/E-Defense research program. The building was tested in three configurations: isolated with triple pendulum bearings (TPB), isolated with lead rubber bearings combined with cross linear sliders (which is not discussed in this dissertation), and fixed base. The test provided full-scale response data of both the isolation system and the isolated structure and demonstrated the efficiency of the isolation system in reducing the demands in the isolated structure. A 3-dimensional TPB element with a general friction model that accounts for the variation of friction coefficients on both velocity and vertical force was developed to predict the response of individual TPB and the overall isolation system. The element accounts for both vertical-horizontal coupling behavior and bidirectional coupling of TPB. The horizontal behavior of the element is based on a series combination of bidirectional elastic-plastic springs and the circular gap elements. The new TPB element was verified by the full scale test data and has been implemented in OpenSees so that it is available for general use. The analytical model of the specimen building was also developed and validated by the test data from both the isolated base and fixed base tests. The following modeling assumption were shown to best present the response characteristics of the tested structure: (1) beam were modeled as nonlinear elements with resultant composite sections, (2) moment connection were modeled using a Krawinkler panel zone model, and (3) energy dissipation was represented by Rayleigh damping calibrated to include higher mode effects observed in the test data, along with additional interstory dampers. The vertical component of the excitation was shown to amplify the horizontal response of both the fixed base and isolated base structures. This coupling effect was small in the tested fixed base

  11. Linking the "Leaky Edges" of the Outside with the Individual Inside

    ERIC Educational Resources Information Center

    Carlson, David Lee

    2007-01-01

    Throughout seven years of teaching in urban schools, the author discovered that the most effective ways to teach difficult literary texts was to refer to students' out-of-school activities. In other words, to connect the "leaky edges of the "social outside"" with the "individual inside" is to create a curriculum of "embodied relationships." This…

  12. Spontaneous symmetry breaking of self-trapped and leaky modes in quasi-double-well potentials

    NASA Astrophysics Data System (ADS)

    Zegadlo, Krzysztof B.; Dror, Nir; Trippenbach, Marek; Karpierz, Miroslaw A.; Malomed, Boris A.

    2016-02-01

    We investigate competition between two phase transitions of the second kind induced by the self-attractive nonlinearity, viz., self-trapping of the leaky modes, and spontaneous symmetry breaking (SSB) of both fully trapped and leaky states. We use a one-dimensional mean-field model, which combines the cubic nonlinearity and a double-well-potential (DWP) structure with an elevated floor, which supports leaky modes (quasi-bound states) in the linear limit. The setting can be implemented in nonlinear optics and Bose-Einstein condensates. The order in which the SSB and self-trapping transitions take place with the growth of the nonlinearity strength depends on the height of the central barrier of the DWP: the SSB happens first if the barrier is relatively high, while self-trapping comes first if the barrier is lower. The SSB of the leaky modes is characterized by specific asymmetry of their radiation tails, which, in addition, feature a resonant dependence on the relation between the total size of the system and radiation wavelength. As a result of the SSB, the instability of symmetric modes initiates spontaneous Josephson oscillations. Collisions of freely moving solitons with the DWP structure admit trapping of an incident soliton into a state of persistent shuttle motion, due to emission of radiation. The study is carried out numerically, and basic results are explained by means of analytical considerations.

  13. How to Say "No" to a Nonword: A Leaky Competing Accumulator Model of Lexical Decision

    ERIC Educational Resources Information Center

    Dufau, Stephane; Grainger, Jonathan; Ziegler, Johannes C.

    2012-01-01

    We describe a leaky competing accumulator (LCA) model of the lexical decision task that can be used as a response/decision module for any computational model of word recognition. The LCA model uses evidence for a word, operationalized as some measure of lexical activity, as input to the "YES" decision node. Input to the "NO" decision node is…

  14. Leaky surface electromagnetic waves on a high-index dielectric grating.

    PubMed

    Maradudin, A A; Simonsen, I; Zierau, W

    2016-05-15

    We show theoretically that the periodically corrugated surface of a high-index dielectric medium can support a leaky surface electromagnetic wave. This wave is bound to the surface in the vacuum, but radiates into the dielectric. Despite this radiative damping, the surface wave can have a long lifetime. PMID:27176969

  15. SOLUTIONS APPROXIMATING SOLUTE TRANSPORT IN A LEAKY AQUIFER RECEIVING WASTEWATER INJECTION

    EPA Science Inventory

    A mathematical model amenable to analytical solution techniques is developed for the investigation of contaminant transport from an injection well into a leaky aquifer system, which comprises a pumped and an unpumped aquifer connected to each other by an aquitard. A steady state ...

  16. SOLUTIONS APPROXIMATING SOLUTE TRANSPORT IN A LEAKY AQUIFER RECEIVING WASTEWATER INJECTION

    EPA Science Inventory

    A mathematical model amenable to analytical solution techniques is developed for the investigation of contaminant transport from an injection well into a leaky aquifer system, which comprises a pumped and an unpumped aquifer connected to each other by an aquitard. teady state gro...

  17. A modeling investigation of the impact of street and building configurations on personal air pollutant exposure in isolated deep urban canyons.

    PubMed

    Ng, Wai-Yin; Chau, Chi-Kwan

    2014-01-15

    This study evaluated the effectiveness of different configurations for two building design elements, namely building permeability and setback, proposed for mitigating air pollutant exposure problems in isolated deep canyons by using an indirect exposure approach. The indirect approach predicted the exposures of three different population subgroups (i.e. pedestrians, shop vendors and residents) by multiplying the pollutant concentrations with the duration of exposure within a specific micro-environment. In this study, the pollutant concentrations for different configurations were predicted using a computational fluid dynamics model. The model was constructed based on the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence model. Fifty-one canyon configurations with aspect ratios of 2, 4, 6 and different building permeability values (ratio of building spacing to the building façade length) or different types of building setback (recess of a high building from the road) were examined. The findings indicated that personal exposures of shop vendors were extremely high if they were present inside a canyon without any setback or separation between buildings and when the prevailing wind was perpendicular to the canyon axis. Building separation and building setbacks were effective in reducing personal air exposures in canyons with perpendicular wind, although their effectiveness varied with different configurations. Increasing the permeability value from 0 to 10% significantly lowered the personal exposures on the different population subgroups. Likewise, the personal exposures could also be reduced by the introduction of building setbacks despite their effects being strongly influenced by the aspect ratio of a canyon. Equivalent findings were observed if the reduction in the total development floor area (the total floor area permitted to be developed within a particular site area) was also considered. These findings were employed to

  18. A Review of the Ginzburg-Syrovatskii's Galactic Cosmic-Ray Propagation Model and its Leaky-Box Limit

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2012-01-01

    Phenomenological models of galactic cosmic-ray propagation are based on a diffusion equation known as the Ginzburg-Syrovatskii s equation, or variants (or limits) of this equation. Its one-dimensional limit in a homogeneous volume, known as the leaky-box limit or model, is sketched here. The justification, utility, limitations, and a typical numerical implementation of the leaky-box model are examined in some detail.

  19. Dirac leaky-wave antennas for continuous beam scanning from photonic crystals

    NASA Astrophysics Data System (ADS)

    Memarian, Mohammad; Eleftheriades, George V.

    2015-01-01

    Leaky-Wave Antennas (LWAs) enable directive and scannable radiation patterns, which are highly desirable attributes at terahertz, infrared and optical frequencies. However, a LWA is generally incapable of continuous beam scanning through broadside, due to an open stopband in its dispersion characteristic. This issue is yet to be addressed at frequencies beyond microwaves, mainly as existing microwave solutions (for example, transmission line metamaterials) are unavailable at these higher frequencies. Here we report leaky-wave radiation from the interface of a photonic crystal (PC) with a Dirac-type dispersion and air. The resulting Dirac LWA (DLWA) can radiate at broadside, chiefly owing to the closed Γ-point bandgap of the Dirac PC. Thus, the DLWA can continuously scan a directive beam over a wide range of angles by varying the frequency. These DLWAs can be designed at microwave as well as terahertz to optical frequencies, with feasible dimensions and low losses.

  20. Integration of Leaky Waveguide Detection with Electrowetting on Dielectric Digital Microfluidic Devices

    NASA Astrophysics Data System (ADS)

    Gupta, Ruchi; Goddard, Nick

    2013-06-01

    Typically, Electrowetting on dielectric (EWOD) digital microfluidic devices consist of an array of metal electrodes covered with a continuous hydrophobic dielectric layer. The monitoring of droplet position and detection in EWOD is usually achieved via microscopy, thereby resulting in increasing the size and complexity of the instrumentation associated with such devices. This work for the first time demonstrates that metal clad leaky waveguide (MCLW) is suitable for detection in EWOD devices. MCLW devices typically consist of a metal layer covered with a dielectric layer in which the leaky waveguide mode propagates. The two structures are fundamentally compatible provided the metal and dielectric layer thicknesses and refractive indices can be optimised to permit both electrowetting and waveguiding. In this work, it has been shown that titanium electrodes covered with a fluoropolymer layer can be used to perform MCLW detection of droplets on EWOD platforms.

  1. Dirac leaky-wave antennas for continuous beam scanning from photonic crystals.

    PubMed

    Memarian, Mohammad; Eleftheriades, George V

    2015-01-01

    Leaky-Wave Antennas (LWAs) enable directive and scannable radiation patterns, which are highly desirable attributes at terahertz, infrared and optical frequencies. However, a LWA is generally incapable of continuous beam scanning through broadside, due to an open stopband in its dispersion characteristic. This issue is yet to be addressed at frequencies beyond microwaves, mainly as existing microwave solutions (for example, transmission line metamaterials) are unavailable at these higher frequencies. Here we report leaky-wave radiation from the interface of a photonic crystal (PC) with a Dirac-type dispersion and air. The resulting Dirac LWA (DLWA) can radiate at broadside, chiefly owing to the closed Γ-point bandgap of the Dirac PC. Thus, the DLWA can continuously scan a directive beam over a wide range of angles by varying the frequency. These DLWAs can be designed at microwave as well as terahertz to optical frequencies, with feasible dimensions and low losses. PMID:25556705

  2. Visualization of guided and leaky wave behaviors in an indium tin oxide metallic slab waveguide.

    PubMed

    Teo, Stephanie M; Werley, Christopher A; Wang, Congshun; Fan, Kebin; Ofori-Okai, Benjamin K; Zhang, Xin; Averitt, Richard D; Nelson, Keith A

    2015-06-01

    We explored the use of the optically transparent semiconductor indium tin oxide (ITO) as an alternative to optically opaque metals for the fabrication of photonic structures in terahertz (THz) near-field studies. Using the polaritonics platform, we confirmed the ability to clearly image both bound and leaky electric fields underneath an ITO layer. We observed good agreement between measured waveguide dispersion and analytical theory of an asymmetric metal-clad planar waveguide with TE and TM polarizations. Further characterization of the ITO revealed that even moderately conductive samples provided sufficiently high quality factors for studying guided and leaky wave behaviors in individual transparent THz resonant structures such as antennas or split ring resonators. However, without higher conductive ITO, the limited reflection efficiency and high radiation damping measured here both diminish the applicability of ITO for high-reflecting, arrayed, or long path-length elements. PMID:26072845

  3. Robust sound onset detection using leaky integrate-and-fire neurons with depressing synapses.

    PubMed

    Smith, Leslie S; Fraser, Dagmar S

    2004-09-01

    A biologically inspired technique for detecting onsets in sound is presented. Outputs from a cochlea-like filter are spike coded, in a way similar to the auditory nerve (AN). These AN-like spikes are presented to a leaky integrate-and-fire neuron through a depressing synapse. Onsets are detected with essentially zero latency relative to these AN spikes. Onset detection results for a tone burst, musical sounds and the DARPA/NIST TIMIT speech corpus are presented. PMID:15484889

  4. Spreading of Thin Droplets of Perfect and Leaky Dielectric Liquids on Inclined Surfaces.

    PubMed

    Corbett, Andrew; Kumar, Satish

    2016-07-01

    The spreading of droplets may be influenced by electric fields, a situation that is relevant to applications such as coating, printing, and microfluidics. In this work we study the effects of an electric field on the gravity-driven spreading of two-dimensional droplets down an inclined plane. We consider both perfect and leaky dielectric liquids, as well as perfectly and partially wetting systems. In addition to the effects of electric fields, we examine the use of thermocapillary forces to suppress the growth of the capillary ridge near the droplet front. Lubrication theory is applied to generate a set of coupled partial differential equations for interfacial height and charge, which are then solved numerically with a finite-difference method. Electric fields increase the height of the capillary ridge in both perfect and leaky dielectric droplets due to electrostatic pressure gradients that drive liquid into the ridge. In leaky dielectrics, large interfacial charge gradients in the contact-line region create shear stresses that also enhance ridge growth and the formation of trailing minor ridges. The coalescence of these ridges can significantly affect the long-time thinning rate of leaky dielectric droplets. In partially wetting liquids, electric fields promote the splitting of smaller droplets from the primary droplet near the receding contact line due to the interplay between electrostatic forces and disjoining pressure. Cooling from below and heating from above generates thermocapillary forces that counteract the effects of electric fields and suppress the growth of the capillary ridge. The results of this work have important implications for manipulating the spreading of droplets down inclined surfaces. PMID:27247998

  5. Nonlinear electrohydrodynamics of leaky dielectric drops in the Quincke regime: Numerical simulations

    NASA Astrophysics Data System (ADS)

    Das, Debasish; Saintillan, David

    2015-11-01

    The deformation of leaky dielectric drops in a dielectric fluid medium when subject to a uniform electric field is a classic electrohydrodynamic phenomenon best described by the well-known Melcher-Taylor leaky dielectric model. In this work, we develop a three-dimensional boundary element method for the full leaky dielectric model to systematically study the deformation and dynamics of liquid drops in strong electric fields. We compare our results with existing numerical studies, most of which have been constrained to axisymmetric drops or have neglected interfacial charge convection by the flow. The leading effect of convection is to enhance deformation of prolate drops and suppress deformation of oblate drops, as previously observed in the axisymmetric case. The inclusion of charge convection also enables us to investigate the dynamics in the Quincke regime, in which experiments exhibit a symmetry-breaking bifurcation leading to a tank-treading regime. Our simulations confirm the existence of this bifurcation for highly viscous drops, and also reveal the development of sharp interfacial charge gradients driven by convection near the drop's equator. American Chemical Society, Petroleum Research Fund.

  6. Leaky modes and the first arrivals in cased boreholes with poorly bonded conditions

    NASA Astrophysics Data System (ADS)

    Zhang, XiuMei; Wang, XiuMing; Zhang, HaiLan

    2016-02-01

    The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the dispersion features, excitation spectra and contributions of modes excited in the cased boreholes with different cementing types are studied. The phase velocity dispersion studies of leaky modes show that high-order modes form "plateau" regions with one approximate velocity denoted by v separated by their cutoff frequencies, in which the phase velocity changes little with a considerable frequency range, while the group velocity keeps a relatively constant high value. Usually, the operation frequency range of a specific cementing evaluation acoustic logging tool is covered by such a "plateau" region. Mode excitation and contribution analyses show that the first arrivals in the cased boreholes for the poorly bonded conditions are the contributions from leaky modes, where the traveling velocity of the first arrivals processed by slowness time coherence (STC) method is equal to the approximated velocity v. Analyses on generation of leaky modes in the cased boreholes supplement the understanding of the generation mechanism of the first arrivals.

  7. Leaky RyR2 channels unleash a brainstem spreading depolarization mechanism of sudden cardiac death.

    PubMed

    Aiba, Isamu; Wehrens, Xander H T; Noebels, Jeffrey L

    2016-08-16

    Cardiorespiratory failure is the most common cause of sudden unexplained death in epilepsy (SUDEP). Genetic autopsies have detected "leaky" gain-of-function mutations in the ryanodine receptor-2 (RyR2) gene in both SUDEP and sudden cardiac death cases linked to catecholaminergic polymorphic ventricular tachycardia that feature lethal cardiac arrhythmias without structural abnormality. Here we find that a human leaky RyR2 mutation, R176Q (RQ), alters neurotransmitter release probability in mice and significantly lowers the threshold for spreading depolarization (SD) in dorsal medulla, leading to cardiorespiratory collapse. Rare episodes of sinus bradycardia, spontaneous seizure, and sudden death were detected in RQ/+ mutant mice in vivo; however, when provoked, cortical seizures frequently led to apneas, brainstem SD, cardiorespiratory failure, and death. In vitro studies revealed that the RQ mutation selectively strengthened excitatory, but not inhibitory, synapses and facilitated SD in both the neocortex as well as brainstem dorsal medulla autonomic microcircuits. These data link defects in neuronal intracellular calcium homeostasis to the vulnerability of central autonomic brainstem pathways to hypoxic stress and implicate brainstem SD as a previously unrecognized site and mechanism contributing to premature death in individuals with leaky RYR2 mutations. PMID:27482086

  8. A Novel Computational Method to Reduce Leaky Reaction in DNA Strand Displacement

    PubMed Central

    Li, Xin; Wang, Xun; Song, Tao; Lu, Wei; Chen, Zhihua; Shi, Xiaolong

    2015-01-01

    DNA strand displacement technique is widely used in DNA programming, DNA biosensors, and gene analysis. In DNA strand displacement, leaky reactions can cause DNA signals decay and detecting DNA signals fails. The mostly used method to avoid leakage is cleaning up after upstream leaky reactions, and it remains a challenge to develop reliable DNA strand displacement technique with low leakage. In this work, we address the challenge by experimentally evaluating the basic factors, including reaction time, ratio of reactants, and ion concentration to the leakage in DNA strand displacement. Specifically, fluorescent probes and a hairpin structure reporting DNA strand are designed to detect the output of DNA strand displacement, and thus can evaluate the leakage of DNA strand displacement reactions with different reaction time, ratios of reactants, and ion concentrations. From the obtained data, mathematical models for evaluating leakage are achieved by curve derivation. As a result, it is obtained that long time incubation, high concentration of fuel strand, and inappropriate amount of ion concentration can weaken leaky reactions. This contributes to a method to set proper reaction conditions to reduce leakage in DNA strand displacement. PMID:26491602

  9. Numerical simulation of the leaky dielectric microdroplet generation in electric fields

    NASA Astrophysics Data System (ADS)

    Kamali, Reza; Manshadi, Mohammad Karim Dehghan

    2016-07-01

    Microdroplet generation has a vast range of applications in the chemical, biomedical, and biological sciences. Several devices are applied to produce microdroplets, such as Co-flow, T-junction and Flow-focusing. The important point in the producing process is controlling the separated fluid volume in these devices. On the other hand, a large number of liquids, especially aqueous one, are influenced by electric or magnetic fields. As a consequence, an electric field could be used in order to affect the separated fluid volume. In this study, effects of an electric field on the microdroplet generation in a Co-flow device are investigated numerically. Furthermore, effects of some electrical properties such as permittivity on the separating process of microdroplets are studied. Leaky dielectric and perfect dielectric models are used in this investigation. According to the results, in the microdroplet generating process, leaky dielectric fluids show different behaviors, when an electric field is applied to the device. In other words, in a constant electric field strength, the volume of generated microdroplets can increase or decrease, in comparison with the condition without the electric field. However, for perfect dielectric fluids, droplet volume always decreases with increasing the electric field strength. In order to validate the numerical method of this study, deformation of a leaky dielectric droplet in an electric field is investigated. Results are compared with Taylor theoretical model.

  10. Properties of Transmission and Leaky Modes in a Plasmonic Waveguide Constructed by Periodic Subwavelength Metallic Hollow Blocks.

    PubMed

    Wu, Jin Jei; Wu, Chien Jang; Shen, Jian Qi; Hou, Da Jun; Lo, Wen Chen

    2015-01-01

    Based on the concept of low-frequency spoof surface plasmon polaritons (spoof SPPs), a kind of leaky mode is proposed in a waveguide made of a subwavelength metal-block array with open slots. Numerical results reveal that a new transmission mode is found in the periodic subwavelength metal open blocks. This modal field is located inside the interior of a hollow block compared with that in a solid metal block array. The dispersion curve shows that such a new SPPs mode has a negative slope, crossing the light line, and then going into a zone of leaky mode at higher frequencies. The leaky mode has a wider frequency bandwidth, and this can lead to a radiation scanning angle of 53° together with high radiation efficiency. Based on the individual characteristics exhibited by a frequency-dependent radiation pattern for the present leaky mode, the waveguide structure can have potential applications such as frequency dividers and demultiplexers. Experimental verification of such a leaky mode at microwave has been performed, and the experimental results are found to be consistent with the theoretical analysis. PMID:26403387

  11. NF-κB promotes leaky expression of adenovirus genes in a replication-incompetent adenovirus vector

    PubMed Central

    Machitani, M.; Sakurai, F.; Wakabayashi, K.; Nakatani, K.; Shimizu, K.; Tachibana, M.; Mizuguchi, H.

    2016-01-01

    The replication-incompetent adenovirus (Ad) vector is one of the most promising vectors for gene therapy; however, systemic administration of Ad vectors results in severe hepatotoxicities, partly due to the leaky expression of Ad genes in the liver. Here we show that nuclear factor-kappa B (NF-κB) mediates the leaky expression of Ad genes from the Ad vector genome, and that the inhibition of NF-κB leads to the suppression of Ad gene expression and hepatotoxicities following transduction with Ad vectors. Activation of NF-κB by recombinant tumor necrosis factor (TNF)-α significantly enhanced the leaky expression of Ad genes. More than 50% suppression of the Ad gene expression was found by inhibitors of NF-κB signaling and siRNA-mediated knockdown of NF-κB. Similar results were found when cells were infected with wild-type Ad. Compared with a conventional Ad vector, an Ad vector expressing a dominant-negative IκBα (Adv-CADNIκBα), which is a negative regulator of NF-κB, mediated approximately 70% suppression of the leaky expression of Ad genes in the liver. Adv-CADNIκBα did not induce apparent hepatotoxicities. These results indicate that inhibition of NF-κB leads to suppression of Ad vector-mediated tissue damages via not only suppression of inflammatory responses but also reduction in the leaky expression of Ad genes. PMID:26814140

  12. Properties of Transmission and Leaky Modes in a Plasmonic Waveguide Constructed by Periodic Subwavelength Metallic Hollow Blocks

    PubMed Central

    Jei Wu, Jin; Jang Wu, Chien; Qi Shen, Jian; Hou, Da Jun; Chen Lo, Wen

    2015-01-01

    Based on the concept of low-frequency spoof surface plasmon polaritons (spoof SPPs), a kind of leaky mode is proposed in a waveguide made of a subwavelength metal-block array with open slots. Numerical results reveal that a new transmission mode is found in the periodic subwavelength metal open blocks. This modal field is located inside the interior of a hollow block compared with that in a solid metal block array. The dispersion curve shows that such a new SPPs mode has a negative slope, crossing the light line, and then going into a zone of leaky mode at higher frequencies. The leaky mode has a wider frequency bandwidth, and this can lead to a radiation scanning angle of 53° together with high radiation efficiency. Based on the individual characteristics exhibited by a frequency-dependent radiation pattern for the present leaky mode, the waveguide structure can have potential applications such as frequency dividers and demultiplexers. Experimental verification of such a leaky mode at microwave has been performed, and the experimental results are found to be consistent with the theoretical analysis. PMID:26403387

  13. Experimental evaluation of leaky least-mean-square algorithms for active noise reduction in communication headsets

    NASA Astrophysics Data System (ADS)

    Cartes, David A.; Ray, Laura R.; Collier, Robert D.

    2002-04-01

    An adaptive leaky normalized least-mean-square (NLMS) algorithm has been developed to optimize stability and performance of active noise cancellation systems. The research addresses LMS filter performance issues related to insufficient excitation, nonstationary noise fields, and time-varying signal-to-noise ratio. The adaptive leaky NLMS algorithm is based on a Lyapunov tuning approach in which three candidate algorithms, each of which is a function of the instantaneous measured reference input, measurement noise variance, and filter length, are shown to provide varying degrees of tradeoff between stability and noise reduction performance. Each algorithm is evaluated experimentally for reduction of low frequency noise in communication headsets, and stability and noise reduction performance are compared with that of traditional NLMS and fixed-leakage NLMS algorithms. Acoustic measurements are made in a specially designed acoustic test cell which is based on the original work of Ryan et al. [``Enclosure for low frequency assessment of active noise reducing circumaural headsets and hearing protection,'' Can. Acoust. 21, 19-20 (1993)] and which provides a highly controlled and uniform acoustic environment. The stability and performance of the active noise reduction system, including a prototype communication headset, are investigated for a variety of noise sources ranging from stationary tonal noise to highly nonstationary measured F-16 aircraft noise over a 20 dB dynamic range. Results demonstrate significant improvements in stability of Lyapunov-tuned LMS algorithms over traditional leaky or nonleaky normalized algorithms, while providing noise reduction performance equivalent to that of the NLMS algorithm for idealized noise fields.

  14. Semi-analytical solution of groundwater flow in a leaky aquifer system subject to bending effect

    NASA Astrophysics Data System (ADS)

    Yu, Chia-Chi; Yang, Shaw-Yang; Yeh, Hund-Der

    2013-04-01

    SummaryThe bending of aquitard like a plate due to aquifer pumping and compression is often encountered in many practical problems of subsurface flow. This reaction will have large influence on the release of the volume of water from the aquifer, which is essential for the planning and management of groundwater resources in aquifers. However, the groundwater flow induced by pumping in a leaky aquifer system is often assumed that the total stress of aquifer maintains constant all the time and the mechanical behavior of the aquitard formation is negligible. Therefore, this paper devotes to the investigation of the effect of aquitard bending on the drawdown distribution in a leaky aquifer system, which is obviously of interest in groundwater hydrology. Based on the work of Wang et al. (2004) this study develops a mathematical model for investigating the impacts of aquitard bending and leakage rate on the drawdown of the confined aquifer due to a constant-rate pumping in the leaky aquifer system. This model contains three equations; two flow equations delineate the transient drawdown distributions in the aquitard and the confined aquifer, while the other describes the vertical displacement in response to the aquitard bending. For the case of no aquitard bending, this new solution can reduce to the Hantush Laplace-domain solution (Hantush, 1960). On the other hand, this solution without the leakage effect can reduce to the time domain solution of Wang et al. (2004). The results show that the aquifer drawdown is influenced by the bending effect at early time and by the leakage effect at late time. The results of sensitivity analysis indicate that the aquifer compaction is sensitive only at early time, causing less amount of water released from the pumped aquifer than that predicted by the traditional groundwater theory. The dimensionless drawdown is rather sensitive to aquitard's hydraulic conductivity at late time. Additionally, both the hydraulic conductivity and

  15. EEG-based event detection using optimized echo state networks with leaky integrator neurons.

    PubMed

    Ayyagari, Sudhanshu S D P; Jones, Richard D; Weddell, Stephen J

    2014-01-01

    This study investigates the classification ability of linear and nonlinear classifiers on biological signals using the electroencephalogram (EEG) and examines the impact of architectural changes within the classifier in order to enhance the classification. Consequently, artificial events were used to validate a prototype EEG-based microsleep detection system based around an echo state network (ESN) and a linear discriminant analysis (LDA) classifier. The artificial events comprised infrequent 2-s long bursts of 15 Hz sinusoids superimposed on prerecorded 16-channel EEG data which provided a means of determining and optimizing the accuracy of overall classifier on `gold standard' events. The performance of this system was tested on different signal-to-noise amplitude ratios (SNRs) ranging from 16 down to 0.03. Results from several feature selection/reduction and pattern classification modules indicated that training the classifier using a leaky-integrator neuron ESN structure yielded highest classification accuracy. For datasets with a low SNR of 0.3, training the leaky-neuron ESN using only those features which directly correspond to the underlying event, resulted in a phi correlation of 0.92 compared to 0.37 that employed principal component analysis (PCA). On the same datasets, other classifiers such as LDA and simple ESNs using PCA performed weakly with a correlation of 0.05 and 0 respectively. These results suggest that ESNs with leaky neuron architectures have superior pattern recognition properties. This, in turn, may reflect their superior ability to exploit differences in state dynamics and, hence, provide superior temporal characteristics in learning. PMID:25571328

  16. Experimental evaluation of leaky least-mean-square algorithms for active noise reduction in communication headsets.

    PubMed

    Cartes, David A; Ray, Laura R; Collier, Robert D

    2002-04-01

    An adaptive leaky normalized least-mean-square (NLMS) algorithm has been developed to optimize stability and performance of active noise cancellation systems. The research addresses LMS filter performance issues related to insufficient excitation, nonstationary noise fields, and time-varying signal-to-noise ratio. The adaptive leaky NLMS algorithm is based on a Lyapunov tuning approach in which three candidate algorithms, each of which is a function of the instantaneous measured reference input, measurement noise variance, and filter length, are shown to provide varying degrees of tradeoff between stability and noise reduction performance. Each algorithm is evaluated experimentally for reduction of low frequency noise in communication headsets, and stability and noise reduction performance are compared with that of traditional NLMS and fixed-leakage NLMS algorithms. Acoustic measurements are made in a specially designed acoustic test cell which is based on the original work of Ryan et al. ["Enclosure for low frequency assessment of active noise reducing circumaural headsets and hearing protection," Can. Acoust. 21, 19-20 (1993)] and which provides a highly controlled and uniform acoustic environment. The stability and performance of the active noise reduction system, including a prototype communication headset, are investigated for a variety of noise sources ranging from stationary tonal noise to highly nonstationary measured F-16 aircraft noise over a 20 dB dynamic range. Results demonstrate significant improvements in stability of Lyapunov-tuned LMS algorithms over traditional leaky or nonleaky normalized algorithms, while providing noise reduction performance equivalent to that of the NLMS algorithm for idealized noise fields. PMID:12002860

  17. Flow in horizontally anisotropic multilayered aquifer systems with leaky wells and aquitards

    NASA Astrophysics Data System (ADS)

    Cihan, Abdullah; Zhou, Quanlin; Birkholzer, Jens T.; Kraemer, Stephen R.

    2014-01-01

    Flow problems in an anisotropic domain can be transformed into ones in an equivalent isotropic domain by coordinate transformations. Once analytical solutions are obtained for the equivalent isotropic domain, they can be back transformed to the original anisotropic domain. The existing solutions presented by Cihan et al. (2011) for isotropic multilayered aquifer systems with alternating aquitards and multiple injection/pumping wells and leaky wells were modified to account for horizontal anisotropy in aquifers. The modified solutions for pressure buildup distribution and leakage rates through leaky wells can be used when the anisotropy direction and ratio (Kx/Ky) are assumed to be identical for all aquifers alternating with aquitards. However, for multilayered aquifers alternating with aquicludes, both the principal direction of the anisotropic horizontal conductivity and the anisotropy ratio can be different in each aquifer. With coordinate transformation, a circular well with finite radius becomes an ellipse, and thus in the transformed domain the head contours in the immediate vicinity of the well have elliptical shapes. Through a radial flow approximation around the finite radius wells, the elliptical well boundaries in the transformed domain are approximated by an effective well radius expression. The analytical solutions with the effective radius approximations were compared with exact solutions as well as a numerical solution for elliptic flow. The effective well radius approximation is sufficiently accurate to predict the head buildup at the well bore of the injection/pumping wells for moderately anisotropic systems (Kx/Ky≤25). The effective radius approximation gives satisfactory results for predicting head buildup at observation points and leakage through leaky wells away from the injection/pumping wells even for highly anisotropic aquifer systems >(Kx/Ky≤1000>).

  18. A General Solution for Groundwater Flow in Estuarine Leaky Aquifer System with Considering Aquifer Anisotropy

    NASA Astrophysics Data System (ADS)

    Chen, Po-Chia; Chuang, Mo-Hsiung; Tan, Yih-Chi

    2014-05-01

    In recent years the urban and industrial developments near the coastal area are rapid and therefore the associated population grows dramatically. More and more water demand for human activities, agriculture irrigation, and aquaculture relies on heavy pumping in coastal area. The decline of groundwater table may result in the problems of seawater intrusion and/or land subsidence. Since the 1950s, numerous studies focused on the effect of tidal fluctuation on the groundwater flow in the coastal area. Many studies concentrated on the developments of one-dimensional (1D) and two-dimensional (2D) analytical solutions describing the tide-induced head fluctuations. For example, Jacob (1950) derived an analytical solution of 1D groundwater flow in a confined aquifer with a boundary condition subject to sinusoidal oscillation. Jiao and Tang (1999) derived a 1D analytical solution of a leaky confined aquifer by considered a constant groundwater head in the overlying unconfined aquifer. Jeng et al. (2002) studied the tidal propagation in a coupled unconfined and confined costal aquifer system. Sun (1997) presented a 2D solution for groundwater response to tidal loading in an estuary. Tang and Jiao (2001) derived a 2D analytical solution in a leaky confined aquifer system near open tidal water. This study aims at developing a general analytical solution describing the head fluctuations in a 2D estuarine aquifer system consisted of an unconfined aquifer, a confined aquifer, and an aquitard between them. Both the confined and unconfined aquifers are considered to be anisotropic. The predicted head fluctuations from this solution will compare with the simulation results from the MODFLOW program. In addition, the solutions mentioned above will be shown to be special cases of the present solution. Some hypothetical cases regarding the head fluctuation in costal aquifers will be made to investigate the dynamic effects of water table fluctuation, hydrogeological conditions, and

  19. A generalized Leaky Integrate-and-Fire neuron model with fast implementation method.

    PubMed

    Wang, Zhenzhong; Guo, Lilin; Adjouadi, Malek

    2014-08-01

    This study introduces a new Generalized Leaky Integrate-and-Fire (GLIF) neuron model with variable leaking resistor and bias current in order to reproduce accurately the membrane voltage dynamics of a biological neuron. The accuracy of this model is ensured by adjusting its parameters to the statistical properties of the Hodgkin-Huxley model outputs; while the speed is enhanced by introducing a Generalized Exponential Moving Average method that converts the parameterized kernel functions into pre-calculated lookup tables based on an analytic solution of the dynamic equations of the GLIF model. PMID:24875788

  20. Maximizing spike train coherence or incoherence in the leaky integrate-and-fire model

    NASA Astrophysics Data System (ADS)

    Lindner, Benjamin; Schimansky-Geier, Lutz; Longtin, André

    2002-09-01

    We study noise-induced resonance effects in the leaky integrate-and-fire neuron model with absolute refractory period, driven by a Gaussian white noise. It is demonstrated that a finite noise level may either maximize or minimize the regularity of the spike train. We also partition the parameter space into regimes where either or both of these effects occur. It is shown that the coherence minimization at moderate noise results in a flat spectral response with respect to periodic stimulation in contrast to sharp resonances that are observed for both small and large noise intensities.

  1. Improved Integral Equation Solution for the First Passage Time of Leaky Integrate-and-Fire Neurons

    PubMed Central

    Dong, `Yi; Mihalas, Stefan; Niebur, Ernst

    2011-01-01

    An accurate calculation of the first passage time probability density (FPTPD) is essential for computing the likelihood of solutions of the stochastic leaky integrate-and-fire model. The previously proposed numerical calculation of the FPTPD based on the integral equation method discretizes the probability current of the voltage crossing the threshold. While the method is accurate for high noise levels, we show that it results in large numerical errors for small noise. The problem is solved by analytically computing, in each time bin, the mean probability current. Efficiency is further improved by identifying and ignoring time bins with negligible mean probability current. PMID:21105825

  2. Leaky unstable modes and electromagnetic radiation amplification by an anisotropic plasma slab

    SciTech Connect

    Vagin, K. Yu. Uryupin, S. A.

    2015-09-15

    The interaction between electromagnetic radiation and a photoionized plasma slab with an anisotropic electron velocity distribution is studied. It is shown that the fields of leaky modes are amplified due to the development of aperiodic instability in the slab, which leads to an increase in both the reflected and transmitted fields. The transmitted field can significantly increase only if the slab thickness does not exceed the ratio of the speed of light to the electron plasma frequency, whereas there is no upper bound on the slab thickness for the reflected signal to be amplified.

  3. Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

    SciTech Connect

    Fountaine, Katherine T.; Whitney, William S.; Atwater, Harry A.

    2014-10-21

    We present a unified framework for resonant absorption in periodic arrays of high index semiconductor nanowires that combines a leaky waveguide theory perspective and that of photonic crystals supporting Bloch modes, as array density transitions from sparse to dense. Full dispersion relations are calculated for each mode at varying illumination angles using the eigenvalue equation for leaky waveguide modes of an infinite dielectric cylinder. The dispersion relations along with symmetry arguments explain the selectivity of mode excitation and spectral red-shifting of absorption for illumination parallel to the nanowire axis in comparison to perpendicular illumination. Analysis of photonic crystal band dispersion for varying array density illustrates that the modes responsible for resonant nanowire absorption emerge from the leaky waveguide modes.

  4. Evaluation of layer thickness in human teeth using higher-order-mode leaky Lamb wave interdigital transducers

    SciTech Connect

    Toda, Shinji; Fujita, Takeshi; Arakawa, Hirohisa; Toda, Kohji

    2005-03-01

    An ultrasonic nondestructive evaluation technique of the layer thickness in human teeth is proposed using a leaky Lamb wave device with two arch-shaped interdigital transducers, operating at a plate/water interface. The use of a higher-order-mode leaky Lamb wave with a phase velocity higher than the longitudinal wave velocity in the human tooth is essential to detect reflected ultrasound beams from the tooth section The layer thickness of dentin, estimated from the measured time interval between two reflected echoes, is in good agreement with the optically measured data.

  5. Silicon-based optical leaky wave antenna with narrow beam radiation.

    PubMed

    Song, Qi; Campione, Salvatore; Boyraz, Ozdal; Capolino, Filippo

    2011-04-25

    We propose a design of a dielectric (silicon nitride) optical leaky wave antenna (OLWA) with periodic semiconductor (silicon) corrugations, capable of producing narrow beam radiation. The optical antenna radiates a narrow beam because a leaky wave (LW) with low attenuation constant is excited at one end of the corrugated dielectric waveguide. We show that pointing angle, beam-width, and operational frequency are all related to the LW complex wavenumber, whose value depends on the amount of silicon perturbations in the waveguide. In this paper, the propagation constant and the attenuation coefficient of the LW in the periodic structure are extracted from full-wave simulations. The far-field radiation patterns in both glass and air environments predicted by LW theory agree well with the ones obtained by full-wave simulations. We achieve a directive radiation pattern in glass environment with about 17.5 dB directivity and 1.05 degree beam-width at the operative free space wavelength of 1.55 μm, pointing at a direction orthogonal to the waveguide (broadside direction). We also show that the use of semiconductor corrugations facilitate electronic tuning of the radiation pattern via carrier injection. PMID:21643126

  6. Nonreciprocal and magnetically scanned miniaturized leaky-wave antennas using coupled transmission lines

    NASA Astrophysics Data System (ADS)

    Apaydin, Nil; Sertel, Kubilay; Volakis, John L.

    2014-06-01

    This paper presents a new class of magnetically scanned leaky wave antennas (LWAs), incorporating ferrite (or possibly magnetoelectric composite), for wide angle beamsteering. Using the ferrite's tunable permeability beamsteering is achieved by controlling the external bias field. This is unlike most leaky-wave antennas requiring frequency modulation to steer the beam. Our first design is based on coupled microstrip lines on a biased ferrite substrate with nonreciprocal radiation properties, specifically a 5 dB contrast between the measured transmit and receive gain in the E-plane was achieved. However, it was found that inhomogeneities in the bias field limited its scanning performance. To alleviate this issue, a new class of miniaturized metamaterial based LWA was considered and presented here. This new design is based on coupled composite right left handed (CRLH) transmission lines (TLs) and has a unit-cell length of only λ0/20. For validation, a 15-unit-cell prototype was manufactured and its TX/RX beams were scanned in the E-plane 80° by changing the bias field within a range of ±50 Oe. We found that the associated antenna gain varied between 3.5 dB and 5 dB at 1.79 GHz as the beam was scanned. In the above design, scanning was realized by changing the distance between the bias source and the LWA. Thus, future work will be focused on LWAs tuned by biasing a magnetodielectric layer placed below the ferrite substrate.

  7. A leaky aquifer below Champlain Sea clay: closed-form solutions for natural seepage.

    PubMed

    Chapuis, Robert P; Saucier, Antoine

    2013-01-01

    Closed-form solutions are proposed for natural seepage in semiconfined (leaky) aquifers such as those existing below the massive Champlain Sea clay layers in the Saint-Lawrence River Valley. The solutions are for an ideal horizontal leaky aquifer below an ideal aquitard that may have either a constant thickness and a constant hydraulic head at its surface, or a variable thickness and a variable hydraulic head at its surface. A few simplifying assumptions were needed to obtain the closed-form solutions. These have been verified using a finite element method, which did not make any of the assumptions but gave an excellent agreement for hydraulic heads and groundwater velocities. For example, the difference between the two solutions was smaller than 1 mm for variations in the 5 to 8 m range for the hydraulic head in the semiconfined aquifer. Note that fitting the hydraulic head data of monitoring wells to the theoretical solutions gives only the ratio of the aquifer and aquitard hydraulic conductivities, a clear case of multiple solutions for an inverse problem. Consequently, field permeability tests in the aquitard and the aquifer, and pumping tests in the aquifer, are still needed to determine the hydraulic conductivity values. PMID:23441962

  8. Black Queen evolution: the role of leakiness in structuring microbial communities.

    PubMed

    Morris, J Jeffrey

    2015-08-01

    Black Queen (BQ) functions are biological processes that yield neither purely private nor purely public products. This partitioning of benefits, also called 'leakiness', can produce negative frequency dependence of fitness in microbial communities, allowing coexistence between function-performing helpers and function-requiring beneficiaries. The ubiquity of leakiness favors a 'race to the bottom' as members of a community lose the ability to perform functions whose products are available from the environment. Rather than being social altruists, helpers are merely those populations that lost this race and got stuck in their role as function performers. Here I discuss many such BQ functions and the microbial communities that evolve around them. I also compile evidence from laboratory evolution experiments as well as phylogenetic reconstructions that show that organisms gain greater fitness increases from gene/function loss events than is commonly expected. Finally, I consider possible consequences of long-term BQ-stabilized coexistence, including sympatric speciation and the evolution of true mutualisms. PMID:26078099

  9. Optimized echo state networks with leaky integrator neurons for EEG-based microsleep detection.

    PubMed

    Ayyagari, Sudhanshu S D P; Jones, Richard D; Weddell, Stephen J

    2015-08-01

    The performance of a microsleep detection system was calculated in terms of its ability to detect the behavioural microsleep state (1-s epochs) from spectral features derived from 16-channel EEG sampled at 256 Hz. Best performance from a single classifier model was achieved using leaky integrator neurons on an echo state network (ESN) classifier with a mean phi correlation (φ) of 0.38 and accuracy of 67.3%. A single classifier model of ESN with sigmoidal inputs achieved φ of 0.20 and accuracy of 48.5% and a single classifier model of linear discriminant analysis (LDA) achieved φ of 0.31 and accuracy of 53.6%. However, combining the output of several single classifier models (ensemble learning) via stacked generalization of the ESN with leaky integrator neurons approach led to a substantial increase in detection performance of φ of 0.51 and accuracy of 81.2%. This is a substantial improvement of our previous best result of φ = 0.39 on this data with LDA and stacked generalization. PMID:26737115

  10. Experimental observation on a frequency spectrum of a plate mode of a predominantly leaky nature

    PubMed

    Durinck; Thys; Rembert; Izbicki

    1999-06-01

    The problem of normal propagation modes of a plate submerged in a fluid is usually treated by considering continuous leaky Lamb waves or by considering transient waves. Angular plate resonances are associated with modes obtained by the first approach, whereas frequency plate resonances are associated with modes obtained using the second method. The dispersion curves for these two kinds of mode are almost identical, except for certain modes at large phase speed. In an experiment one is never dealing with one of these extreme situations because the applied signal is never infinitely long and the beam used to insonify the plate is never infinitely wide. In this paper we report on the manifestation in the transmission frequency spectrum, of a plate mode of a predominantly leaky nature. The extra mode, which has never been reported on, is observed between the cutoff frequencies of the symmetrical transient modes S1 and S2 of a submerged aluminium plate. The modes are identified by means of an Argand diagram. PMID:10499808

  11. Cell-Penetrating Peptide Induces Leaky Fusion of Liposomes Containing Late Endosome-Specific Anionic Lipid

    PubMed Central

    Yang, Sung-Tae; Zaitseva, Elena; Chernomordik, Leonid V.; Melikov, Kamran

    2010-01-01

    Cationic cell-penetrating peptides (CPPs) are a promising vehicle for the delivery of macromolecular drugs. Although many studies have indicated that CPPs enter cells by endocytosis, the mechanisms by which they cross endosomal membranes remain elusive. On the basis of experiments with liposomes, we propose that CPP escape into the cytosol is based on leaky fusion (i.e., fusion associated with the permeabilization of membranes) of the bis(monoacylglycero)phosphate (BMP)-enriched membranes of late endosomes. In our experiments, prototypic CPP HIV-1 TAT peptide did not interact with liposomes mimicking the outer leaflet of the plasma membrane, but it did induce lipid mixing and membrane leakage as it translocated into liposomes mimicking the lipid composition of late endosome. Both membrane leakage and lipid mixing depended on the BMP content and were promoted at acidic pH, which is characteristic of late endosomes. Substitution of BMP with its structural isomer, phosphatidylglycerol (PG), significantly reduced both leakage of the aqueous probe from liposomes and lipid mixing between liposomes. Although affinity of binding to TAT was similar for BMP and PG, BMP exhibited a higher tendency to support the inverted hexagonal phase than PG. Finally, membrane leakage and peptide translocation were both inhibited by inhibitors of lipid mixing, further substantiating the hypothesis that cationic peptides cross BMP-enriched membranes by inducing leaky fusion between them. PMID:20959093

  12. Analysis of microwave leaky modes propagating through laser plasma filaments column waveguide

    SciTech Connect

    Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan

    2012-12-15

    A plasma column waveguide formed by a bundle of closely spaced plasma filaments induced by the propagation of ultrafast laser pulses in air and revived by a longer infrared laser pulse is shown to support microwave radiation. We consider values of both the plasma electron density and microwave frequency for which the refractive index of plasma is lower than the refractive index of air; therefore, a leaky plasma waveguide can be realized in extremely high frequency band. The guiding mechanism does not require high conductance of the plasma and can be easily excited by using commercial femtosecond laser sources. A theoretical study of leaky mode characteristics of isotropic and homogeneous plasma column waveguides is investigated with several values of plasma and waveguide structure parameters. The microwave transmission loss was found to be mainly caused by the microwave leakage through the air-plasma interface and is weakly dependent on the plasma absorption. In spite of losses of microwaves caused by leakage and plasma absorption, it is shown to be much lower than both that accompanying to surface waves attaching to single conducting plasma wire and the free space propagation over distances in the order of the filament length, which opens exciting perspectives for short distance point to point wireless transmission of pulsed-modulated microwaves.

  13. Analysis of microwave leaky modes propagating through laser plasma filaments column waveguide

    NASA Astrophysics Data System (ADS)

    Alshershby, Mostafa; Hao, Zuoqiang; Lin, Jingquan

    2012-12-01

    A plasma column waveguide formed by a bundle of closely spaced plasma filaments induced by the propagation of ultrafast laser pulses in air and revived by a longer infrared laser pulse is shown to support microwave radiation. We consider values of both the plasma electron density and microwave frequency for which the refractive index of plasma is lower than the refractive index of air; therefore, a leaky plasma waveguide can be realized in extremely high frequency band. The guiding mechanism does not require high conductance of the plasma and can be easily excited by using commercial femtosecond laser sources. A theoretical study of leaky mode characteristics of isotropic and homogeneous plasma column waveguides is investigated with several values of plasma and waveguide structure parameters. The microwave transmission loss was found to be mainly caused by the microwave leakage through the air-plasma interface and is weakly dependent on the plasma absorption. In spite of losses of microwaves caused by leakage and plasma absorption, it is shown to be much lower than both that accompanying to surface waves attaching to single conducting plasma wire and the free space propagation over distances in the order of the filament length, which opens exciting perspectives for short distance point to point wireless transmission of pulsed-modulated microwaves.

  14. Leaky Landfills.

    ERIC Educational Resources Information Center

    Jones, Linda L. Cronin

    1992-01-01

    Provides background information on landfills and describes an activity where students learn how a modern landfill is constructed and develop an understanding of the reasons for several regulations regarding modern landfill construction. Students design and construct working models of three types of landfills. (PR)

  15. CFD simulation of pollutant dispersion around isolated buildings: on the role of convective and turbulent mass fluxes in the prediction accuracy.

    PubMed

    Gousseau, P; Blocken, B; van Heijst, G J F

    2011-10-30

    Computational Fluid Dynamics (CFD) is increasingly used to predict wind flow and pollutant dispersion around buildings. The two most frequently used approaches are solving the Reynolds-averaged Navier-Stokes (RANS) equations and Large-Eddy Simulation (LES). In the present study, we compare the convective and turbulent mass fluxes predicted by these two approaches for two configurations of isolated buildings with distinctive features. We use this analysis to clarify the role of these two components of mass transport on the prediction accuracy of RANS and LES in terms of mean concentration. It is shown that the proper simulation of the convective fluxes is essential to predict an accurate concentration field. In addition, appropriate parameterization of the turbulent fluxes is needed with RANS models, while only the subgrid-scale effects are modeled with LES. Therefore, when the source is located outside of recirculation regions (case 1), both RANS and LES can provide accurate results. When the influence of the building is higher (case 2), RANS models predict erroneous convective fluxes and are largely outperformed by LES in terms of prediction accuracy of mean concentration. These conclusions suggest that the choice of the appropriate turbulence model depends on the configuration of the dispersion problem under study. It is also shown that for both cases LES predicts a counter-gradient mechanism of the streamwise turbulent mass transport, which is not reproduced by the gradient-diffusion hypothesis that is generally used with RANS models. PMID:21880420

  16. Communication with extraterrestrial intelligences - Possibilities, chances, and perspectives with special attention given to the leaky-embargo hypothesis

    NASA Astrophysics Data System (ADS)

    Fiebag, Johannes

    1989-12-01

    Present SETI projects are described, emphasizing search methods alternative to investigations in the radio range. The possibility that the human race is being studied by alien presences within the solar system is addressed in the context of the 'zoo hypothesis' and the 'leaky embargo' hypothesis. In the former, the aliens prevent any contact with humans, while in the latter occasional contact is permitted.

  17. Large-core tube-leaky waveguide for delivery of high-powered Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Kobayashi, S.; Katagiri, T.; Matsuura, Y.

    2014-02-01

    A tube-leaky fiber that consists of only dielectric thin-film tubing for delivery of Er:YAG laser light is presented. The tube-leaky fiber confines light in the airy core when the film thickness is properly chosen for target wavelength. Transmission properties of the fibers are derived by using a ray optic method and designed the optimum wall thickness for the Er:YAG laser wavelength of 2.94 micron. In fabrication of the tube leaky fiber, we use a microstructural tube made of glass to enhance mechanical strength. The central bore and surrounding glass thin layer that is held by the microstructure function as a tube-leaky fiber. We fabricate a large-core fiber for delivery of high-power medical lasers by stack-and-draw method and we use borosilicate-glass as a fiber material for low cost fabrication. Fabricated fibers have a diameter over 400 μm and from the loss measurements for Er:YAG laser, and the fibers deliver laser light with a transmission loss of 0.85 dB/m that is comparable to 0.7 dB/m of conventional hollow-optical fibers. The fibers withstand transmission of laser pulses with energy higher than 120 mJ. We confirm that these energies are enough to ablate biological tissues in surgical operations.

  18. Exploiting the leaky-wave properties of transmission-line metamaterials for single-microphone direction finding.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Hervé; Mosig, Juan R

    2016-06-01

    A transmission-line acoustic metamaterial is an engineered, periodic arrangement of relatively small unit-cells, the acoustic properties of which can be manipulated to achieve anomalous physical behaviours. These exotic properties open the door to practical applications, such as an acoustic leaky-wave antenna, through the implementation of radiating channels along the metamaterial. In the transmitting mode, such a leaky-wave antenna is capable of steering sound waves in frequency-dependent directions. Used in reverse, the antenna presents a well defined direction-frequency behaviour. In this paper, an acoustic leaky-wave structure is presented in the receiving mode. It is shown that it behaves as a sound source direction-finding device using only one sensor. After a general introduction of the acoustic leaky-wave antenna concept, its radiation pattern and radiation efficiency are expressed in closed form. Then, numerical simulations and experimental assessments of the proposed transmission-line based structure, implementing only one sensor at one termination, are presented. It is shown that such a structure is capable of finding the direction of an incoming sound wave, from backward to forward, based on received sound power spectra. This introduces the concept of sound source localization without resorting to beam-steering techniques based on multiple sensors. PMID:27369150

  19. The effects of air gap reflections during air-coupled leaky Lamb wave inspection of thin plates.

    PubMed

    Fan, Zichuan; Jiang, Wentao; Cai, Maolin; Wright, William M D

    2016-02-01

    Air-coupled ultrasonic inspection using leaky Lamb waves offers attractive possibilities for non-contact testing of plate materials and structures. A common method uses an air-coupled pitch-catch configuration, which comprises a transmitter and a receiver positioned at oblique angles to a thin plate. It is well known that the angle of incidence of the ultrasonic bulk wave in the air can be used to preferentially generate specific Lamb wave modes in the plate in a non-contact manner, depending on the plate dimensions and material properties. Multiple reflections of the ultrasonic waves in the air gap between the transmitter and the plate can produce additional delayed waves entering the plate at angles of incidence that are different to those of the original bulk wave source. Similarly, multiple reflections of the leaky Lamb waves in the air gap between the plate and an inclined receiver may then have different angles of incidence and propagation delays when arriving at the receiver and hence the signal analysis may become complex, potentially leading to confusion in the identification of the wave modes. To obtain a better understanding of the generation, propagation and detection of leaky Lamb waves and the effects of reflected waves within the air gaps, a multiphysics model using finite element methods was established. This model facilitated the visualisation of the propagation of the reflected waves between the transducers and the plate, the subsequent generation of additional Lamb wave signals within the plate itself, their leakage into the adjacent air, and the reflections of the leaky waves in the air gap between the plate and receiver. Multiple simulations were performed to evaluate the propagation and reflection of signals produced at different transducer incidence angles. Experimental measurements in air were in good agreement with simulation, which verified that the multiphysics model can provide a convenient and accurate way to interpret the signals in

  20. Gut-liver axis in liver cirrhosis: How to manage leaky gut and endotoxemia

    PubMed Central

    Fukui, Hiroshi

    2015-01-01

    A “leaky gut” may be the cutting edge for the passage of toxins, antigens or bacteria into the body, and may play a pathogenic role in advanced liver cirrhosis and its complications. Plasma endotoxin levels have been admitted as a surrogate marker of bacterial translocation and close relations of endotoxemia to hyperdynamic circulation, portal hypertension, renal, cardiac, pulmonary and coagulation disturbances have been reported. Bacterial overgrowth, increased intestinal permeability, failure to inactivate endotoxin, activated innate immunity are all likely to play a role in the pathological states of bacterial translocation. Therapeutic approach by management of the gut-liver axis by antibiotics, probiotics, synbiotics, prebiotics and their combinations may improve the clinical course of cirrhotic patients. Special concern should be paid on anti-endotoxin treatment. Adequate management of the gut-liver axis may be effective for prevention of liver cirrhosis itself by inhibiting the progression of fibrosis. PMID:25848468

  1. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures.

    PubMed

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-01-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design. PMID:27035269

  2. A leaky-wave antenna using double-layered metamaterial transmission line

    NASA Astrophysics Data System (ADS)

    Xu, He-Xiu; Wang, Guang-Ming; Qi, Mei-Qing

    2013-05-01

    A novel leaky-wave antenna (LWA) is proposed using a double-layered resonant-type metamaterial (MTM) transmission line (TL). The MTM TL is composed of periodically arranged complementary split ring resonators (CSRRs), capacitive gaps, and metal caps. By introducing the extra metal cap in additional layer of the basic artificial MTM TL element, an increased left handed capacitor by 36 % with respect to that using none cap is engineered, which is necessary to implement a balanced condition, and thus a continuous beam steering property of the resultant LWA in terms of providing phase constants from negative to positive values. For verification, a 20-cells LWA sample is fabricated and measured. Consistent numerical and experimental results have both validated the continuous frequency-scanning capabilities of the antenna from backward -29° to forward 72° (including the broadside). The proposed prescription opens a way toward new types of MTM LWAs with easily engineered broadside radiation.

  3. Leaky-mode assisted fluorescence extraction: application to fluorescence enhancement biosensors.

    PubMed

    Ganesh, Nikhil; Block, Ian D; Mathias, Patrick C; Zhang, Wei; Chow, Edmond; Malyarchuk, Viktor; Cunningham, Brian T

    2008-12-22

    Efficient recovery of light emitted by fluorescent molecules by employing photonic structures can result in high signal-to-noise ratio detection for biological applications including DNA microarrays, fluorescence microscopy and single molecule detection. By employing a model system comprised of colloidal quantum dots, we consider the physical basis of the extraction effect as provided by photonic crystals. Devices with different lattice symmetry are fabricated ensuring spectral and spatial coupling of quantum dot emission with leaky eigenmodes and the emission characteristics are studied using angle-resolved and angle-integrated measurements. Comparison with numerical calculations and lifetime measurements reveals that the enhancement occurs via resonant redirection of the emitted radiation. Comparison of various lattices reveals differences in the enhancement factor with a maximum enhancement factor approaching 220. We also demonstrate the first enhanced extraction biosensor that allows for over 20-fold enhancement of the fluorescence signal in detection of the cytokine TNF-alpha by a fluorescence sandwich immunoassay. PMID:19104594

  4. Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

    SciTech Connect

    Qiao, B.; Zepf, M.; Borghesi, M.; Dromey, B.; Geissler, M.; Karmakar, A.; Gibbon, P.

    2010-10-08

    A new ion radiation-pressure acceleration regime, the 'leaky light sail', is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10{sup 19} W/cm{sup 2}. 100 MeV proton beams are obtained by increasing the intensities to 2x10{sup 20} W/cm{sup 2}.

  5. Efficient calculation of 1-D periodic Green's functions for leaky-wave applications.

    SciTech Connect

    Baccarelli, Paolo; Johnson, William Arthur; Paulotto, Simone; Jackson, David R.; Wilton, Donald R.; Galli, A.; Valero, G.; Celepcikay, F. T.

    2010-08-01

    In this paper an approach is described for the efficient computation of the mixed-potential scalar and dyadic Green's functions for a one-dimensional periodic (periodic along x direction) array of point sources embedded in a planar stratified structure. Suitable asymptotic extractions are performed on the slowly converging spectral series. The extracted terms are summed back through the Ewald method, modified and optimized to efficiently deal with all the different terms. The accelerated Green's functions allow for complex wavenumbers, and are thus suitable for application to leaky-wave antennas analysis. Suitable choices of the spectral integration paths are made in order to account for leakage effects and the proper/improper nature of the various space harmonics that form the 1-D periodic Green's function.

  6. Gut-liver axis in liver cirrhosis: How to manage leaky gut and endotoxemia.

    PubMed

    Fukui, Hiroshi

    2015-03-27

    A "leaky gut" may be the cutting edge for the passage of toxins, antigens or bacteria into the body, and may play a pathogenic role in advanced liver cirrhosis and its complications. Plasma endotoxin levels have been admitted as a surrogate marker of bacterial translocation and close relations of endotoxemia to hyperdynamic circulation, portal hypertension, renal, cardiac, pulmonary and coagulation disturbances have been reported. Bacterial overgrowth, increased intestinal permeability, failure to inactivate endotoxin, activated innate immunity are all likely to play a role in the pathological states of bacterial translocation. Therapeutic approach by management of the gut-liver axis by antibiotics, probiotics, synbiotics, prebiotics and their combinations may improve the clinical course of cirrhotic patients. Special concern should be paid on anti-endotoxin treatment. Adequate management of the gut-liver axis may be effective for prevention of liver cirrhosis itself by inhibiting the progression of fibrosis. PMID:25848468

  7. Statistics of a leaky integrate-and-fire model of neurons driven by dichotomous noise

    NASA Astrophysics Data System (ADS)

    Mankin, Romi; Lumi, Neeme

    2016-05-01

    The behavior of a stochastic leaky integrate-and-fire model of neurons is considered. The effect of temporally correlated random neuronal input is modeled as a colored two-level (dichotomous) Markovian noise. Relying on the Riemann method, exact expressions for the output interspike interval density and for the serial correlation coefficient are derived, and their dependence on noise parameters (such as correlation time and amplitude) is analyzed. Particularly, noise-induced sign reversal and a resonancelike amplification of the kurtosis of the interspike interval distribution are established. The features of spike statistics, analytically revealed in our study, are compared with recently obtained results for a perfect integrate-and-fire neuron model.

  8. Analysis and design of a leaky-wave EMC dipole array

    NASA Astrophysics Data System (ADS)

    Potharazu, Pavan K.; Jackson, David R.

    1992-08-01

    An analysis of an electromagnetically coupled (EMC) dipole array is presented, in which a microstrip line is coupled to an infinite periodic linear array of microstrip dipoles, arranged perpendicular to the line. The spectral-domain immitance method is used to obtain the periodic Green's function for the two-layered structure, and the method of moments with a Galerkin testing procedure is then used to enforce the electric field integral equation (EFIE) on the line and the dipole within a unit cell of the structure to obtain the determinantal equation for the unknown leaky-wave propagation constant. One of the interesting features of this analysis is the path of integration in the complex plane used to compute the moment method reactions, which must be partly on the improper sheet for the m = -1 space harmonic when it radiates in the forward direction. Measured radiation patterns for a 10-element EMC dipole array are presented and compared with the corresponding theoretical ones.

  9. Simultaneous confidence intervals for a steady-state leaky aquifer groundwater flow model

    USGS Publications Warehouse

    Christensen, S.; Cooley, R.L.

    1996-01-01

    Using the optimization method of Vecchia & Cooley (1987), nonlinear Scheffe??-type confidence intervals were calculated tor the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence intervals are compared to corresponding linear intervals. As suggested by the significant nonlinearity of the regression model, linear confidence intervals are often not accurate. The commonly made assumption that widths of linear confidence intervals always underestimate the actual (nonlinear widths was not correct for the head intervals. Results show that nonlinear effects can cause the nonlinear intervals to be offset from, and either larger or smaller than, the linear approximations. Prior information on some transmissivities helps reduce and stabilize the confidence intervals, with the most notable effects occurring for the parameters on which there is prior information and for head values in parameter zones for which there is prior information on the parameters.

  10. Claudin-2 as a mediator of leaky gut barrier during intestinal inflammation.

    PubMed

    Luettig, J; Rosenthal, R; Barmeyer, C; Schulzke, J D

    2015-01-01

    The epithelial tight junction determines the paracellular water and ion movement in the intestine and also prevents uptake of larger molecules, including antigens, in an uncontrolled manner. Claudin-2, one of the 27 mammalian claudins regulating that barrier function, forms a paracellular channel for small cations and water. It is typically expressed in leaky epithelia like proximal nephron and small intestine and provides a major pathway for the paracellular transport of sodium, potassium, and fluid. In intestinal inflammation (Crohn's disease, ulcerative colitis), immune-mediated diseases (celiac disease), and infections (HIV enteropathy), claudin-2 is upregulated in small and large intestine and contributes to diarrhea via a leak flux mechanism. In parallel to that upregulation, other epithelial and tight junctional features are altered and the luminal uptake of antigenic macromolecules is enhanced, for which claudin-2 may be partially responsible through induction of tight junction strand discontinuities. PMID:25838982

  11. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures

    PubMed Central

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-01-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design. PMID:27035269

  12. The relaxation of a prolate leaky dielectric drop in a uniform DC electric field

    NASA Astrophysics Data System (ADS)

    Khair, Aditya; Lanauze, Javier; Walker, Lynn

    2015-11-01

    We quantify the relaxation of a prolate leaky dielectric drop upon removal of a uniform DC electric field. Experiments consisting of a castor oil drop suspended in a silicone oil are compared against boundary integral simulations that account for transient charging of the interface. Charge relaxation causes a marked asymmetry in the drop evolution during deformation and relaxation. In particular, during relaxation a prolate to oblate shape transition is observed before the drop recovers its equilibrium spherical shape. Furthermore, the high field strengths utilized in the experiments yield a fast drop relaxation in comparison with the transient development towards the steady deformation. The storage and release of capacitive energy and capillary energy is then quantified during deformation and relaxation, respectively. Finally, we present computational results for a drop that does not relax back to its initial spherical shape upon removal of the field; rather, the drop breaks up.

  13. Ultrasonic Waveguide Sensor Using a Leaky Lamb Wave for Under-Sodium Viewing

    NASA Astrophysics Data System (ADS)

    Joo, Young-Sang; Lee, Jae-Han

    2010-02-01

    A plate-type ultrasonic waveguide sensor using a leaky Lamb wave has been developed for the under-sodium viewing of a reactor core and in-vessel structures of a sodium-cooled fast reactor (SFR). An A0 Lamb wave mode is utilized in the waveguide sensor for the single mode generation and the effective radiation capability in a fluid. A radiation beam steering technique is presented which is achieved by the frequency tuning of the excitation pulse in the frequency range of the A0 Lamb wave mode which the group velocity is not dispersive and the phase velocity is dispersive. The long distance propagation ability and C-scan imaging performance have been demonstrated successfully by experimental feasibility tests of the waveguide sensor.

  14. On the processing of leaky guided waves propagating in immersed plates

    NASA Astrophysics Data System (ADS)

    Bagheri, Abdollah; Rizzo, Piervincenzo; Pistone, Elisabetta

    2014-03-01

    We present a non-destructive inspection method for the structural health monitoring of underwater structures. A laser operating at 532 nm is used to excite leaky guided waves on an aluminum plate immersed in water. The plate has a few artificial defects namely vertical notch, horizontal notch, corrosion, and small hole. An array of five immersion transducers arranged in half-circle is used to detect the propagating waves. A signal processing technique is implemented to assess the presence of damage; the method is based on continuous wavelet transform to extract a few damagesensitive features fed to an artificial neural network for damage classification. The experimental results show that the proposed system can be employed for the inspection of underwater plates.

  15. Evaluation of the resolution of a metamaterial acoustic leaky wave antenna.

    PubMed

    Naify, Christina J; Rogers, Jeffery S; Guild, Matthew D; Rohde, Charles A; Orris, Gregory J

    2016-06-01

    Acoustic antennas have long been utilized to directionally steer acoustic waves in both air and water. Typically, these antennas are comprised of arrays of active acoustic elements, which are electronically phased to steer the acoustic profile in the desired direction. A new technology, known as an acoustic leaky wave antenna (LWA), has recently been shown to achieve directional steering of acoustic waves using a single active transducer coupled to a transmission line passive aperture. The LWA steers acoustic energy by preferential coupling to an input frequency and can be designed to steer from backfire to endfire, including broadside. This paper provides an analysis of resolution as a function of both input frequency and antenna length. Additionally, the resolution is compared to that achieved using an array of active acoustic elements. PMID:27369149

  16. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures

    NASA Astrophysics Data System (ADS)

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-04-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design.

  17. Neuronal Spike Timing Adaptation Described with a Fractional Leaky Integrate-and-Fire Model

    PubMed Central

    Teka, Wondimu; Marinov, Toma M.; Santamaria, Fidel

    2014-01-01

    The voltage trace of neuronal activities can follow multiple timescale dynamics that arise from correlated membrane conductances. Such processes can result in power-law behavior in which the membrane voltage cannot be characterized with a single time constant. The emergent effect of these membrane correlations is a non-Markovian process that can be modeled with a fractional derivative. A fractional derivative is a non-local process in which the value of the variable is determined by integrating a temporal weighted voltage trace, also called the memory trace. Here we developed and analyzed a fractional leaky integrate-and-fire model in which the exponent of the fractional derivative can vary from 0 to 1, with 1 representing the normal derivative. As the exponent of the fractional derivative decreases, the weights of the voltage trace increase. Thus, the value of the voltage is increasingly correlated with the trajectory of the voltage in the past. By varying only the fractional exponent, our model can reproduce upward and downward spike adaptations found experimentally in neocortical pyramidal cells and tectal neurons in vitro. The model also produces spikes with longer first-spike latency and high inter-spike variability with power-law distribution. We further analyze spike adaptation and the responses to noisy and oscillatory input. The fractional model generates reliable spike patterns in response to noisy input. Overall, the spiking activity of the fractional leaky integrate-and-fire model deviates from the spiking activity of the Markovian model and reflects the temporal accumulated intrinsic membrane dynamics that affect the response of the neuron to external stimulation. PMID:24675903

  18. Fluid transport across leaky epithelia: central role of the tight junction and supporting role of aquaporins.

    PubMed

    Fischbarg, Jorge

    2010-10-01

    The mechanism of epithelial fluid transport remains unsolved, which is partly due to inherent experimental difficulties. However, a preparation with which our laboratory works, the corneal endothelium, is a simple leaky secretory epithelium in which we have made some experimental and theoretical headway. As we have reported, transendothelial fluid movements can be generated by electrical currents as long as there is tight junction integrity. The direction of the fluid movement can be reversed by current reversal or by changing junctional electrical charges by polylysine. Residual endothelial fluid transport persists even when no anions (hence no salt) are being transported by the tissue and is only eliminated when all local recirculating electrical currents are. Aquaporin (AQP) 1 is the only AQP present in these cells, and its deletion in AQP1 null mice significantly affects cell osmotic permeability (by ∼40%) but fluid transport much less (∼20%), which militates against the presence of sizable water movements across the cell. In contrast, AQP1 null mice cells have reduced regulatory volume decrease (only 60% of control), which suggests a possible involvement of AQP1 in either the function or the expression of volume-sensitive membrane channels/transporters. A mathematical model of corneal endothelium we have developed correctly predicts experimental results only when paracellular electro-osmosis is assumed rather than transcellular local osmosis. Our evidence therefore suggests that the fluid is transported across this layer via the paracellular route by a mechanism that we attribute to electro-osmotic coupling at the junctions. From our findings we have developed a novel paradigm for this preparation that includes 1) paracellular fluid flow; 2) a crucial role for the junctions; 3) hypotonicity of the primary secretion; and 4) an AQP role in regulation rather than as a significant water pathway. These elements are remarkably similar to those proposed by the

  19. Salmonella Infection Upregulates the Leaky Protein Claudin-2 in Intestinal Epithelial Cells

    PubMed Central

    Zhang, Yong-guo; Wu, Shaoping; Xia, Yinglin; Sun, Jun

    2013-01-01

    Background Tight junctions seal the space between adjacent epithelial cells. Mounting evidence suggests that tight junction proteins play a key role in the pathogenesis of human disease. Claudin is a member of the tight junction protein family, which has 24 members in humans. To regulate cellular function, claudins interact structurally and functionally with membrane and scaffolding proteins via their cytoplasmic domain. In particular, claudin-2 is known to be a leaky protein that contributes to inflammatory bowel disease and colon cancer. However, the involvement of claudin-2 in bacterial infection in the intestine remains unknown. Methods/Principal Findings We hypothesized that Salmonella elevates the leaky protein claudin-2 for its own benefit to facilitate bacterial invasion in the colon. Using a Salmonella-colitis mouse model and cultured colonic epithelial cells, we found that pathogenic Salmonella colonization significantly increases the levels of claudin-2 protein and mRNA in the intestine, but not that of claudin-3 or claudin-7 in the colon, in a time-dependent manner. Immunostaining studies showed that the claudin-2 expression along the crypt-villous axis postinfection. In vitro, Salmonella stimulated claudin-2 expression in the human intestinal epithelial cell lines SKCO15 and HT29C19A. Further analysis by siRNA knockdown revealed that claudin-2 is associated with the Salmonella-induced elevation of cell permeability. Epithelial cells with claudin-2 knockdown had significantly less internalized Salmonella than control cells with normal claudin-2 expression. Inhibitor assays demonstrated that this regulation is mediated through activation of the EGFR pathway and the downstream protein JNK. Conclusion/Significance We have shown that Salmonella targets the tight junction protein claudin-2 to facilitate bacterial invasion. We speculate that this disruption of barrier function contributes to a new mechanism by which bacteria interact with their host cells and

  20. Indoor-Outdoor Air Leakage of Apartments and Commercial Buildings

    SciTech Connect

    Price, P.N.; Shehabi, A.; Chan, R.W.; Gadgil, A.J.

    2006-06-01

    We compiled and analyzed available data concerning indoor-outdoor air leakage rates and building leakiness parameters for commercial buildings and apartments. We analyzed the data, and reviewed the related literature, to determine the current state of knowledge of the statistical distribution of air exchange rates and related parameters for California buildings, and to identify significant gaps in the current knowledge and data. Very few data were found from California buildings, so we compiled data from other states and some other countries. Even when data from other developed countries were included, data were sparse and few conclusive statements were possible. Little systematic variation in building leakage with construction type, building activity type, height, size, or location within the u.s. was observed. Commercial buildings and apartments seem to be about twice as leaky as single-family houses, per unit of building envelope area. Although further work collecting and analyzing leakage data might be useful, we suggest that a more important issue may be the transport of pollutants between units in apartments and mixed-use buildings, an under-studied phenomenon that may expose occupants to high levels of pollutants such as tobacco smoke or dry cleaning fumes.

  1. Automated Comparison of Building Energy Simulation Engines (Presentation)

    SciTech Connect

    Polly, B.; Horowitz, S.; Booten, B.; Kruis, N.; Christensen, C.

    2012-08-01

    This presentation describes the BEopt comparative test suite, which is a tool that facilitates the automated comparison of building energy simulation engines. It also demonstrates how the test suite is improving the accuracy of building energy simulation programs. Building energy simulation programs inform energy efficient design for new homes and energy efficient upgrades for existing homes. Stakeholders rely on accurate predictions from simulation programs. Previous research indicates that software tends to over-predict energy usage for poorly-insulated leaky homes. NREL is identifying, investigating, and resolving software inaccuracy issues. Comparative software testing is one method of many that NREL uses to identify potential software issues.

  2. Hybrid method for the precise calculation of the general dyadic Greens functions for SAW and leaky wave substrates.

    SciTech Connect

    Branch, Darren W.

    2008-05-01

    Recently, the generalized method for calculation of the 16-element Green's function for analysis of surface acoustic waves has proven crucial to develop more sophisticated transducers. The generalized Green's function provides a precise relationship between the acoustic stresses and electric displacement on the three mechanical displacements and electric potential. This generalized method is able to account for mass loading effects which is absent in the effective permittivity approach. However, the calculation is numerically intensive and may lead to numerical instabilities when solving for both the eigenvalues and eigenvectors simultaneously. In this work, the general eigenvalue problem was modified to eliminate the numerical instabilities in the solving procedure. An algorithm is also presented to select the proper eigenvalues rapidly to facilitate analysis for all types of acoustic propagation. The 4 x 4 Green's functions and effective permittivities were calculated for materials supporting Rayleigh, leaky, and leaky longitudinal waves as demonstration of the method.

  3. An inter- and intra-chip optical interconnect using a hybrid plasmonic leaky-wave nano-antenna

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Vahid; Yousefi, Leila; Mohammad-Tahri, Mahmoud

    2014-05-01

    In this paper, a new method is proposed to provide an inter- and intra-chip optical interconnect at the standard telecommunication wavelength of 1550 nm. The proposed optical interconnect consists of two optical leaky- wave nano-antennas as transmitter and receiver. The leaky-wave antennas are fed through a hybrid plasmonic waveguide with low propagation loss. Since the propagation length of plasmonic waveguides is not so long, each plasmonic waveguide is coupled to a silicon waveguide through an optical coupler. In comparison with previously proposed method of optical interconnect, the most important advantage of our method is its planar structure which makes it fully integrable with the photonic integrated circuits (PIC). The Fluguet theorem and the theory of surface plasmons are used to obtain an analytical model for design purposes, and the accuracy of the proposed method is verified by a 3-dimensional full-wave numerical analysis.

  4. Evaluation of confidence intervals for a steady-state leaky aquifer model

    USGS Publications Warehouse

    Christensen, S.; Cooley, R.L.

    1999-01-01

    The fact that dependent variables of groundwater models are generally nonlinear functions of model parameters is shown to be a potentially significant factor in calculating accurate confidence intervals for both model parameters and functions of the parameters, such as the values of dependent variables calculated by the model. The Lagrangian method of Vecchia and Cooley [Vecchia, A.V. and Cooley, R.L., Water Resources Research, 1987, 23(7), 1237-1250] was used to calculate nonlinear Scheffe-type confidence intervals for the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence intervals are compared to corresponding linear intervals. As suggested by the significant nonlinearity of the regression model, linear confidence intervals are often not accurate. The commonly made assumption that widths of linear confidence intervals always underestimate the actual (nonlinear) widths was not correct. Results show that nonlinear effects can cause the nonlinear intervals to be asymmetric and either larger or smaller than the linear approximations. Prior information on transmissivities helps reduce the size of the confidence intervals, with the most notable effects occurring for the parameters on which there is prior information and for head values in parameter zones for which there is prior information on the parameters.The fact that dependent variables of groundwater models are generally nonlinear functions of model parameters is shown to be a potentially significant factor in calculating accurate confidence intervals for both model parameters and functions of the parameters, such as the values of dependent variables calculated by the model. The Lagrangian method of Vecchia and Cooley was used to calculate nonlinear Scheffe-type confidence intervals for the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence

  5. Design and analysis of trench-assisted leaky channel waveguide for high power applications

    NASA Astrophysics Data System (ADS)

    Pandey, Himanshu; Saini, Than Singh; Kumar, Ajeet

    2016-05-01

    We purpose a leaky channel waveguide design that supports a single guided mode. The waveguide works on the principle of higher-order mode discrimination. The cladding of waveguide is formed by alternate low and high index regions, which helps to leak out of higher-order modes while retaining the fundamental mode over the entire length of the waveguide. The Structure is analysed by the finite element method 'Comsol Multiphysics' and the leakage losses of the modes along with effective mode area have been calculated. We show that a waveguide formed in silica with core width 6 µm can be designed to exhibit single mode operation at 1550 nm wavelength. The Fundamental loss E11 = 0.076 dB/mm and the higher order loss E21 = 11.4 dB/mm with the rectangular core area as large as 50 µm2. Such large-core-area waveguide structure efficiently suppresses unwanted non-linear optical effects and is suitable for high power devices such as high power Waveguide Laser and Amplifier.

  6. Loss reduction of leaky surface acoustic wave by loading with high-velocity thin film

    NASA Astrophysics Data System (ADS)

    Kakio, Shoji; Hosaka, Keiko

    2016-07-01

    The propagation properties of a leaky surface acoustic wave (LSAW) on rotated Y-cut X-propagating lithium niobate (YX-LN) substrates loaded with an aluminum nitride (AlN) thin film with a higher phase velocity than that of the substrate were investigated theoretically and experimentally. From the theoretical calculation, it was found that the minimum attenuation can be obtained at a certain thickness of the AlN thin film for a cut angle ranging from 0 to 60° because the cut angle giving the minimum attenuation shifts toward a smaller cut angle as the film thickness is increased. The propagation properties of an LSAW on several rotated YX-LN substrates were measured by using an interdigital transducer (IDT) pair with a wavelength λ of 8 µm, and the predicted shifts of the minimum attenuation toward a smaller cut angle were demonstrated experimentally. For 0° and 10°YX-LN samples, the measured insertion loss and propagation loss were markedly reduced by loading with the AlN thin film. A larger electromechanical coupling factor (16.9%) than that at the cut angle giving zero attenuation without a film and a propagation loss less of 0.02 dB/λ were obtained simultaneously at a film thickness of 0.125 λ for the 10°YX-LN sample.

  7. Interflow Moving over Leaky Impeding Layers: How Far Can We Expect It to Go?

    NASA Astrophysics Data System (ADS)

    Jackson, C. R.; Hopp, L.; McDonnell, J.; Bitew, M. M.; Du, E.; Klaus, J.; Griffiths, N.

    2014-12-01

    Interflow can occur in any slope where higher conductivity topsoils are underlain by a low conductivity impeding layer which could include B horizons, till layers, hardpans, C horizons and bedrock of various permeabilities. Impeding layers of essentially impermeable bedrock seem to be a rarity, as studies that have evaluated interflow on slopes underlain by apparently solid crystalline rock have still found leakage into the rock. Hewlett's concrete soil trough studies thus comprise an endpoint of interflow boundary conditions. In many hillslope environments, downslope interflow necessarily includes a normal flow component into the leaky impeding layer. By making a simplifying assumption of zero pressure at the base of the impeding layer (for perched conditions), the downslope travel distance as interflow of a parcel of water can be estimated from the ratio of the hydraulic conductivities, the ratio of the downslope and normal hydraulic gradients, and the thickness of the saturated zone above the impeding layer. For many hillslopes, downslope travel distances imply that only the slope segments adjacent to the riparian valley can be expected to deliver interflow to the valley during a storm. Over most of the hillslope, interflow acts only to redistribute recharge downslope from the point of infiltration. Therefore, continuous perching of water moving as interflow from the ridge to the valley does not imply continuous connectivity. In terms of stormflow contributions, only the lower slopes within the range of the downslope travel distance may be connected to stream valleys.

  8. Leaky-mode waveguide modulators with high deflection angle for use in holographic video displays.

    PubMed

    Qaderi, Kamran; Smalley, Daniel E

    2016-09-01

    Film display holograms typically diffract light over a wide enough view-angle to be viewed, directly, without intervening optics. However, all holographic video displays (with the exception of eye-tracked systems) must use optics beyond the hologram surface to overcome the challenges of small display extent and low diffraction angle by using some form of demagnification and derotation (i.e. angle magnification and optical multiplexing). We report a leaky mode waveguide spatial light modulator with sufficiently high angular diffraction to obviate the need for demagnification in scanned aperture systems. This high angle was achieved by performing a number of experiments to determine the depth of the annealed, proton-exchanged waveguide which corresponded to a maximized diffracted angle. Diffraction sweeps were recorded in excess of 19.5° (corresponding to only 70 MHz of input bandwidth) for 632.8 nm light which is above the 15° required for direct view display. Device geometries are proposed which might achieve greater than 20° of total angular sweep for red, green, and blue light. PMID:27607687

  9. Leaky Integrate-and-Fire Neuron Circuit Based on Floating-Gate Integrator.

    PubMed

    Kornijcuk, Vladimir; Lim, Hyungkwang; Seok, Jun Yeong; Kim, Guhyun; Kim, Seong Keun; Kim, Inho; Choi, Byung Joon; Jeong, Doo Seok

    2016-01-01

    The artificial spiking neural network (SNN) is promising and has been brought to the notice of the theoretical neuroscience and neuromorphic engineering research communities. In this light, we propose a new type of artificial spiking neuron based on leaky integrate-and-fire (LIF) behavior. A distinctive feature of the proposed FG-LIF neuron is the use of a floating-gate (FG) integrator rather than a capacitor-based one. The relaxation time of the charge on the FG relies mainly on the tunnel barrier profile, e.g., barrier height and thickness (rather than the area). This opens up the possibility of large-scale integration of neurons. The circuit simulation results offered biologically plausible spiking activity (<100 Hz) with a capacitor of merely 6 fF, which is hosted in an FG metal-oxide-semiconductor field-effect transistor. The FG-LIF neuron also has the advantage of low operation power (<30 pW/spike). Finally, the proposed circuit was subject to possible types of noise, e.g., thermal noise and burst noise. The simulation results indicated remarkable distributional features of interspike intervals that are fitted to Gamma distribution functions, similar to biological neurons in the neocortex. PMID:27242416

  10. Leaky Integrate-and-Fire Neuron Circuit Based on Floating-Gate Integrator

    PubMed Central

    Kornijcuk, Vladimir; Lim, Hyungkwang; Seok, Jun Yeong; Kim, Guhyun; Kim, Seong Keun; Kim, Inho; Choi, Byung Joon; Jeong, Doo Seok

    2016-01-01

    The artificial spiking neural network (SNN) is promising and has been brought to the notice of the theoretical neuroscience and neuromorphic engineering research communities. In this light, we propose a new type of artificial spiking neuron based on leaky integrate-and-fire (LIF) behavior. A distinctive feature of the proposed FG-LIF neuron is the use of a floating-gate (FG) integrator rather than a capacitor-based one. The relaxation time of the charge on the FG relies mainly on the tunnel barrier profile, e.g., barrier height and thickness (rather than the area). This opens up the possibility of large-scale integration of neurons. The circuit simulation results offered biologically plausible spiking activity (<100 Hz) with a capacitor of merely 6 fF, which is hosted in an FG metal-oxide-semiconductor field-effect transistor. The FG-LIF neuron also has the advantage of low operation power (<30 pW/spike). Finally, the proposed circuit was subject to possible types of noise, e.g., thermal noise and burst noise. The simulation results indicated remarkable distributional features of interspike intervals that are fitted to Gamma distribution functions, similar to biological neurons in the neocortex. PMID:27242416

  11. Associative memory of phase-coded spatiotemporal patterns in leaky Integrate and Fire networks.

    PubMed

    Scarpetta, Silvia; Giacco, Ferdinando

    2013-04-01

    We study the collective dynamics of a Leaky Integrate and Fire network in which precise relative phase relationship of spikes among neurons are stored, as attractors of the dynamics, and selectively replayed at different time scales. Using an STDP-based learning process, we store in the connectivity several phase-coded spike patterns, and we find that, depending on the excitability of the network, different working regimes are possible, with transient or persistent replay activity induced by a brief signal. We introduce an order parameter to evaluate the similarity between stored and recalled phase-coded pattern, and measure the storage capacity. Modulation of spiking thresholds during replay changes the frequency of the collective oscillation or the number of spikes per cycle, keeping preserved the phases relationship. This allows a coding scheme in which phase, rate and frequency are dissociable. Robustness with respect to noise and heterogeneity of neurons parameters is studied, showing that, since dynamics is a retrieval process, neurons preserve stable precise phase relationship among units, keeping a unique frequency of oscillation, even in noisy conditions and with heterogeneity of internal parameters of the units. PMID:23053861

  12. Frequency-division multiplexing in the terahertz range using a leaky-wave antenna

    NASA Astrophysics Data System (ADS)

    Karl, Nicholas J.; McKinney, Robert W.; Monnai, Yasuaki; Mendis, Rajind; Mittleman, Daniel M.

    2015-11-01

    The idea of using radiation in the 0.1-1.0 THz range as carrier waves for free-space wireless communications has attracted growing interest in recent years, due to the promise of the large available bandwidth. Recent research has focused on system demonstrations, as well as the exploration of new components for modulation, beam steering and polarization control. However, the multiplexing and demultiplexing of terahertz signals remains an unaddressed challenge, despite the importance of such capabilities for broadband networks. Using a leaky-wave antenna based on a metal parallel-plate waveguide, we demonstrate frequency-division multiplexing and demultiplexing over more than one octave of bandwidth. We show that this device architecture offers a unique method for controlling the spectrum allocation, by variation of the waveguide plate separation. This strategy, which is distinct from those previously employed in either the microwave or optical regimes, enables independent control of both the centre frequency and bandwidth of multiplexed terahertz channels.

  13. Computational architecture for full-color holographic displays based on anisotropic leaky-mode modulators

    NASA Astrophysics Data System (ADS)

    Jolly, Sundeep; Smalley, Daniel; Barabas, James; Bove, V. Michael

    2014-02-01

    The MIT Mark IV holographic display system employs a novel anisotropic leaky-mode spatial light modulator that allows for the simultaneous and superimposed modulation of red, green, and blue light via wavelength-division multiplexing. This WDM-based scheme for full-color display requires that incoming video signals containing holographic fringe information are comprised of non-overlapping spectral bands that fall within the available 200 MHz output bandwidth of commercial GPUs. These bands correspond to independent color channels in the display output and are appropriately band-limited and centered to match the multiplexed passbands and center frequencies in the frequency response of the mode-coupling device. The computational architecture presented in this paper involves the computation of holographic fringe patterns for each color channel and their summation in generating a single video signal for input to the display. In composite, 18 such input signals, each containing holographic fringe information for 26 horizontal-parallax only holographic lines, are generated via three dual-head GPUs for a total of 468 holographic lines in the display output. We present a general scheme for full-color CGH computation for input to Mark IV and furthermore depict the adaptation of the diffraction specific coherent panoramagram approach to fringe computation for the Mark IV architecture.

  14. Leaky-Surface-Acoustic-Wave Properties on Reverse-Proton-Exchanged LiNbO3

    NASA Astrophysics Data System (ADS)

    Kakio, Shoji; Shimizu, Hidenori; Nakagawa, Yasuhiko

    2009-07-01

    A proton-exchanged (PE) layer with an elastically soft property can be buried into a substrate by a reverse proton exchange (RPE) process. It is expected that an RPE layer with a property similar to that of bulk LiNbO3 will prevent the degradation of coupling factor, and that the buried PE layer will change the anisotropy of the substrate effectively and reduce the leaky surface acoustic wave (LSAW) attenuation as compared with bulk LN. In this study, first, a layered structure of air/bulk LN/softened LN was assumed for rotated Y-X LN and LSAW attenuation was calculated. By controlling the elastic constant of the softened LN, the rotation angle from the Y-axis giving zero attenuation shifted from 64 to 5° for a metallized surface, and the rotation angle at which the attenuation decreases as compared with bulk LN was drastically changed for a free surface. Next, the LSAW propagation loss PL was measured on 41° Y-X LN. The PL for the metallized surface was decreased by carrying out the RPE process from 0.036 dB/λ of a virgin sample to 0.015 dB/λ. The decrease in PL for the free surface was also observed.

  15. Composite Materials NDE Using Enhanced Leaky Lamb Wave Dispersion Data Acquisition Method

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Mal, Ajit; Lih, Shyh-Shiuh; Chang, Zensheu

    1999-01-01

    The leaky Lamb wave (LLW) technique is approaching a maturity level that is making it an attractive quantitative NDE tool for composites and bonded joints. Since it was first observed in 1982, the phenomenon has been studied extensively, particularly in composite materials. The wave is induced by oblique insonification using a pitch-catch arrangement and the plate wave modes are detected by identifying minima in the reflected spectra to obtain the dispersion data. The wave behavior in multi-orientation laminates has been well documented and corroborated experimentally with high accuracy. The sensitivity of the wave to the elastic constants of the material and to the boundary conditions led to the capability to measure the elastic properties of bonded joints. Recently, the authors significantly enhanced the LLW method's capability by increasing the speed of the data acquisition, the number of modes that can be identified and the accuracy of the data inversion. In spite of the theoretical and experimental progress, methods that employ oblique insonification of composites are still not being applied as standard industrial NDE methods. The authors investigated the issues that are hampering the transition of the LLW to industrial applications and identified 4 key issues. The current capability of the method and the nature of these issues are described in this paper.

  16. Concentration history during pumping from a leaky aquifer with stratified initial concentration

    USGS Publications Warehouse

    Goode, Daniel J.; Hsieh, Paul A.; Shapiro, Allen M.; Wood, Warren W.; Kraemer, Thomas F.

    1993-01-01

    Analytical and numerical solutions are employed to examine the concentration history of a dissolved substance in water pumped from a leaky aquifer. Many aquifer systems are characterized by stratification, for example, a sandy layer overlain by a clay layer. To obtain information about separate hydrogeologic units, aquifer pumping tests are often conducted with a well penetrating only one of the layers. When the initial concentration distribution is also stratified (the concentration varies with elevation only), the concentration breakthrough in the pumped well may be interpreted to provide information on aquifer hydraulic and transport properties. To facilitate this interpretation, we present some simple analytical and numerical solutions for limiting cases and illustrate their application to a fractured bedrock/glacial drift aquifer system where the solute of interest is dissolved radon gas. In addition to qualitative information on water source, this method may yield estimates of effective porosity and saturated thickness (or fracture transport aperture) from a single-hole test. Little information about dispersivity is obtained because the measured concentration is not significantly affected by dispersion in the aquifer.

  17. A hybrid base isolation system

    SciTech Connect

    Hart, G.C.; Lobo, R.F.; Srinivasan, M.; Asher, J.W.

    1995-12-01

    This paper proposes a new analysis procedure for hybrid base isolation buildings when considering the displacement response of a base isolated building to wind loads. The system is considered hybrid because of the presence of viscous dampers in the building above the isolator level. The proposed analysis approach incorporates a detailed site specific wind study combined with a dynamic nonlinear analysis of the building response.

  18. The imbalance of new and export production in the western Antarctic Peninsula, a potentially "leaky" ecosystem

    NASA Astrophysics Data System (ADS)

    Stukel, Michael R.; Asher, Elizabeth; Couto, Nicole; Schofield, Oscar; Strebel, Stefanie; Tortell, Philippe; Ducklow, Hugh W.

    2015-09-01

    To quantify the balance between new production and vertical nitrogen export of sinking particles, we measured nitrate uptake, net nitrate drawdown, ΔO2/Ar-based net community production, sediment trap flux, and 234Th export at a coastal site near Palmer Station, Antarctica, during the phytoplankton growing season from October 2012 to March 2013. We also measured nitrate uptake and 234Th export throughout the northern western Antarctic Peninsula (WAP) region on a cruise in January 2013. We used a nonsteady state 234Th equation with temporally varying upwelling rates and an irradiance-based phytoplankton production model to correct our export and new production estimates in the complex coastal site near Palmer Station. Results unequivocally showed that nitrate uptake and net community production were significantly greater than the sinking particle export on region-wide spatial scales and season-long temporal scales. At our coastal site, new production (105 ± 17.4 mg N m-2 d-1, mean ± standard error) was 5.3 times greater than vertical nitrogen export (20.4 ± 2.4 mg N m-2 d-1). On the January cruise in the northern WAP, new production (47.9 ± 14.4 mg N m-2 d-1) was 2.4 times greater than export (19.9 ± 1.4 mg N m-2 d-1). Much of this imbalance can be attributed to diffusive losses of particulate nitrogen from the surface ocean due to diapycnal mixing, indicative of a "leaky" WAP ecosystem. If these diffusive losses are common in other systems where new production exceeds export, it may be necessary to revise current estimates of the ocean's biological pump.

  19. Leaky RAG Deficiency in Adult Patients with Impaired Antibody Production against Bacterial Polysaccharide Antigens

    PubMed Central

    Geier, Christoph B.; Piller, Alexander; Linder, Angela; Sauerwein, Kai M. T.; Eibl, Martha M.; Wolf, Hermann M.

    2015-01-01

    Loss of function mutations in the recombination activating genes RAG1 and RAG2 have been reported to cause a T-B-NK+ type of severe combined immunodeficiency. In addition identification of hypomorphic mutations in RAG1 and RAG2 has led to an expansion of the spectrum of disease to include Omenn syndrome, early onset autoimmunity, granuloma, chronic cytomegalovirus- or EBV-infection with expansion of gamma/delta T-cells, idiophatic CD4 lymphopenia and a phenotype resembling common variable immunodeficiency. Herein we describe a novel presentation of leaky RAG1 and RAG2 deficiency in two unrelated adult patients with impaired antibody production against bacterial polysaccharide antigens. Clinical manifestation included recurrent pneumonia, sinusitis, otitis media and in one patient recurrent cutaneous vasculitis. Both patients harbored a combination of a null mutation on one allele with a novel hypomorphic RAG1/2 mutation on the other allele. One of these novel mutations affected the start codon of RAG1 and resulted in an aberrant gene and protein expression. The second novel RAG2 mutation leads to a truncated RAG2 protein, lacking the C-terminus with intact core RAG2 and reduced VDJ recombination capacity as previously described in a mouse model. Both patients presented with severely decreased numbers of naïve CD4+ T cells and defective T independent IgG responses to bacterial polysaccharide antigens, while T cell-dependent IgG antibody formation e.g. after tetanus or TBEV vaccination was intact. In conclusion, hypomorphic mutations in genes responsible for SCID should be considered in adults with predominantly antibody deficiency. PMID:26186701

  20. Spike Train Probability Models for Stimulus-Driven Leaky Integrate-and-Fire Neurons

    PubMed Central

    Koyama, Shinsuke; Kass, Robert E.

    2009-01-01

    Mathematical models of neurons are widely used to improve understanding of neuronal spiking behavior. These models can produce artificial spike trains that resemble actual spike train data in important ways, but they are not very easy to apply to the analysis of spike train data. Instead, statistical methods based on point process models of spike trains provide a wide range of data-analytical techniques. Two simplified point process models have been introduced in the literature: the time-rescaled renewal process (TRRP) and the multiplicative inhomogeneous Markov interval (m-IMI) model. In this letter we investigate the extent to which the TRRP and m-IMI models are able to fit spike trains produced by stimulus-driven leaky integrate-and-fire (LIF) neurons. With a constant stimulus, the LIF spike train is a renewal process, and the m-IMI and TRRP models will describe accurately the LIF spike train variability. With a time-varying stimulus, the probability of spiking under all three of these models depends on both the experimental clock time relative to the stimulus and the time since the previous spike, but it does so differently for the LIF, m-IMI, and TRRP models. We assessed the distance between the LIF model and each of the two empirical models in the presence of a time-varying stimulus. We found that while lack of fit of a Poisson model to LIF spike train data can be evident even in small samples, the m-IMI and TRRP models tend to fit well, and much larger samples are required before there is statistical evidence of lack of fit of the m-IMI or TRRP models. We also found that when the mean of the stimulus varies across time, the m-IMI model provides a better fit to the LIF data than the TRRP, and when the variance of the stimulus varies across time, the TRRP provides the better fit. PMID:18336078

  1. Understanding the leaky engineering pipeline: Motivation and job adaptability of female engineers

    NASA Astrophysics Data System (ADS)

    Saraswathiamma, Manjusha Thekkedathu

    This dissertation is a mixed-method study conducted using qualitative grounded theory and quantitative survey and correlation approaches. This study aims to explore the motivation and adaptability of females in the engineering profession and to develop a theoretical framework for both motivation and adaptability issues. As a result, this study endeavors to design solutions for the low enrollment and attenuation of female engineers in the engineering profession, often referred to as the "leaky female engineering pipeline." Profiles of 123 female engineers were studied for the qualitative approach, and 98 completed survey responses were analyzed for the quantitative approach. The qualitative, grounded-theory approach applied the constant comparison method; open, axial, and selective coding was used to classify the information in categories, sub-categories, and themes for both motivation and adaptability. The emergent themes for decisions motivating female enrollment include cognitive, emotional, and environmental factors. The themes identified for adaptability include the seven job adaptability factors: job satisfaction, risk- taking attitude, career/skill development, family, gender stereotyping, interpersonal skills, and personal benefit, as well as the self-perceived job adaptability factor. Illeris' Three-dimensional Learning Theory was modified as a model for decisions motivating female enrollment. This study suggests a firsthand conceptual parallelism of McClusky's Theory of Margin for the adaptability of female engineers in the profession. Also, this study attempted to design a survey instrument to measure job adaptability of female engineers. The study identifies two factors that are significantly related to job adaptability: interpersonal skills (< p = 0.01) and family (< p = 0.05); gender stereotyping and personal benefit are other factors that are also significantly (< p = 0.1) related.

  2. Novel Composite Right/Left-Handed Metamaterial-Based Leaky-Wave Transmission-Lines

    NASA Astrophysics Data System (ADS)

    Hashemi, Mohammed Reza Mahmoodi

    The focus of this dissertation is on the design procedure as well as analysis of a very interesting category of metamaterial-based structures namely composite right/left-handed (CRLH) Leaky-wave (LW) transmission-lines (TL). As a result several unique CRLH-TLs are designed and presented. Each of the discussed CRLH LW-TLs has exceptional and beneficial characteristics, which is only realizable due to their composite right/left-handed nature and dispersion characteristics. The operation mechanism of CRLH-TL is explained in the first chapter by the overview of the theory behind the CRLH concept. The dispersion diagram of a CRLH unit-cell shows that the phase constant (beta) is a non-linear function of frequency with a beta = 0 point at a non-zero frequency. Furthermore, a CRLH-TL supports left-handed slow-wave (guided-wave) and fast-wave (leaky-wave) modes, where the phase velocity and the group velocity are anti-parallel and phase advanced is achievable, as well as right-handed slow-wave and fast-wave modes, where the two velocities are parallel and phase delay can be observed. The subject of the second chapter is conformal CRLH LW-TLs. The effect of conformation of a planar uniform CRLH LW-TL on a convex and a concave surface are investigated. It is shown when the CRLH LW-TL is operating in the fast-wave region the conformation affects its radiation characteristics and the radiation pattern becomes wider in both convex and concave cases. A dispersion engineering method is introduced to modify the conformal structure such that it provides comparable performance to that of the planar version in terms of radiation characteristics. Then taking advantage of the proposed modification method a multifunctional electronically controlled conformal CRLH LW-TL is introduced in a later part of this chapter. Varactor diodes are introduced in the unit-cells to electronically control its guided and radiation characteristics. This CRLH-TL has the ability to operate partially in the

  3. Flexible or leaky attention in creative people? Distinct patterns of attention for different types of creative thinking.

    PubMed

    Zabelina, Darya; Saporta, Arielle; Beeman, Mark

    2016-04-01

    Creativity has been putatively linked to distinct forms of attention, but which aspects of creativity and which components of attention remains unclear. Two experiments examined how divergent thinking and creative achievement relate to visual attention. In both experiments, participants identified target letters (S or H) within hierarchical stimuli (global letters made of local letters), after being cued to either the local or global level. In Experiment 1, participants identified the targets more quickly following valid cues (80% of trials) than following invalid cues. However, this smaller validity effect was associated with higher divergent thinking, suggesting that divergent thinking was related to quicker overcoming of invalid cues, and thus to flexible attention. Creative achievement was unrelated to the validity effect. Experiment 2 examined whether divergent thinking (or creative achievement) is related to "leaky attention," so that when cued to one level of a stimulus, some information is still processed, or leaks in, from the non-cued level. In this case, the cued stimulus level always contained a target, and the non-cued level was congruent, neutral, or incongruent with the target. Divergent thinking did not relate to stimulus congruency. In contrast, high creative achievement was related to quicker responses to the congruent than to the incongruent stimuli, suggesting that real-world creative achievement is indeed associated with leaky attention, whereas standard laboratory tests of divergent thinking are not. Together, these results elucidate distinct patterns of attention for different measures of creativity. Specifically, creative achievers may have leaky attention, as suggested by previous literature, whereas divergent thinkers have selective yet flexible attention. PMID:26527210

  4. Demonstration of a directional sonic prism in two dimensions using an air-acoustic leaky wave antenna

    SciTech Connect

    Naify, Christina J. Rohde, Charles A.; Calvo, David C.; Orris, Gregory J.; Guild, Matthew D.

    2015-09-28

    Analysis and experimental demonstration of a two-dimensional acoustic leaky wave antenna is presented for use in air. The antenna is comprised of a two-dimensional waveguide patterned with radiating acoustic shunts. When excited using a single acoustic source within the waveguide, the antenna acts as a sonic prism that exhibits frequency steering. This design allows for control of acoustic steering angle using only a single source transducer and a patterned aperture. Aperture design was determined using transmission line analysis and finite element methods. The designed antenna was fabricated and the steering angle measured. The performance of the measured aperture was within 9% of predicted angle magnitudes over all examined frequencies.

  5. Demonstration of a directional sonic prism in two dimensions using an air-acoustic leaky wave antenna

    NASA Astrophysics Data System (ADS)

    Naify, Christina J.; Guild, Matthew D.; Rohde, Charles A.; Calvo, David C.; Orris, Gregory J.

    2015-09-01

    Analysis and experimental demonstration of a two-dimensional acoustic leaky wave antenna is presented for use in air. The antenna is comprised of a two-dimensional waveguide patterned with radiating acoustic shunts. When excited using a single acoustic source within the waveguide, the antenna acts as a sonic prism that exhibits frequency steering. This design allows for control of acoustic steering angle using only a single source transducer and a patterned aperture. Aperture design was determined using transmission line analysis and finite element methods. The designed antenna was fabricated and the steering angle measured. The performance of the measured aperture was within 9% of predicted angle magnitudes over all examined frequencies.

  6. Leaky rivers: Implications of the loss of longitudinal fluvial disconnectivity in headwater streams

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen; Beckman, Natalie D.

    2014-01-01

    critical component of disconnectivity at all spatial scales examined. Land uses such as timber harvest, flow regulation, and placer mining that result in reduced wood recruitment or removal of instream wood appear to create an alternative stable state in which channels are unable to retain wood because of reduced debris roughness. The net effect of reduced longitudinal disconnectivity is increased transport of fine sediment and organic matter and reduced biological uptake of nutrients. The altered headwater streams become leaky with respect to fine sediments and nutrients.

  7. Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

    NASA Astrophysics Data System (ADS)

    Kostin, V. A.; Vvedenskii, N. V.

    2015-03-01

    We present a way for generating coherent tunable electromagnetic radiation through dc to ac field conversion by an ionization front. The conversion is caused by the excitation of leaky waves behind the transversely limited ionization front propagating in a uniform electrostatic field. This differs significantly from the well-known dc-to-ac-radiation-converter models which consider Doppler-like frequency conversion by a transversely unlimited ionization front propagating in a spatially periodic electric field. We explore the dispersion properties and excitation of these leaky waves radiated through the transverse plasma boundary at the Cherenkov angle to the direction of propagation of a superluminal ionization front as dependent on the parameters of the plasma produced and on the speed of the ionization front. It is shown that not only the center frequency but also the duration and waveform of the generated pulse may significantly depend on the speed of the ionization front. The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned.

  8. Creativity and sensory gating indexed by the P50: selective versus leaky sensory gating in divergent thinkers and creative achievers.

    PubMed

    Zabelina, Darya L; O'Leary, Daniel; Pornpattananangkul, Narun; Nusslock, Robin; Beeman, Mark

    2015-03-01

    Creativity has previously been linked with atypical attention, but it is not clear what aspects of attention, or what types of creativity are associated. Here we investigated specific neural markers of a very early form of attention, namely sensory gating, indexed by the P50 ERP, and how it relates to two measures of creativity: divergent thinking and real-world creative achievement. Data from 84 participants revealed that divergent thinking (assessed with the Torrance Test of Creative Thinking) was associated with selective sensory gating, whereas real-world creative achievement was associated with "leaky" sensory gating, both in zero-order correlations and when controlling for academic test scores in a regression. Thus both creativity measures related to sensory gating, but in opposite directions. Additionally, divergent thinking and real-world creative achievement did not interact in predicting P50 sensory gating, suggesting that these two creativity measures orthogonally relate to P50 sensory gating. Finally, the ERP effect was specific to the P50 - neither divergent thinking nor creative achievement were related to later components, such as the N100 and P200. Overall results suggest that leaky sensory gating may help people integrate ideas that are outside of focus of attention, leading to creativity in the real world; whereas divergent thinking, measured by divergent thinking tests which emphasize numerous responses within a limited time, may require selective sensory processing more than previously thought. PMID:25623426

  9. Improvement of the reverse tetracycline transactivator by single amino acid substitutions that reduce leaky target gene expression to undetectable levels.

    PubMed

    Roney, Ian J; Rudner, Adam D; Couture, Jean-François; Kærn, Mads

    2016-01-01

    Conditional gene expression systems that enable inducible and reversible transcriptional control are essential research tools and have broad applications in biomedicine and biotechnology. The reverse tetracycline transcriptional activator is a canonical system for engineered gene expression control that enables graded and gratuitous modulation of target gene transcription in eukaryotes from yeast to human cell lines and transgenic animals. However, the system has a tendency to activate transcription even in the absence of tetracycline and this leaky target gene expression impedes its use. Here, we identify single amino-acid substitutions that greatly enhance the dynamic range of the system in yeast by reducing leaky transcription to undetectable levels while retaining high expression capacity in the presence of inducer. While the mutations increase the inducer concentration required for full induction, additional sensitivity-enhancing mutations can compensate for this effect and confer a high degree of robustness to the system. The novel transactivator variants will be useful in applications where tight and tunable regulation of gene expression is paramount. PMID:27323850

  10. Improvement of the reverse tetracycline transactivator by single amino acid substitutions that reduce leaky target gene expression to undetectable levels

    PubMed Central

    Roney, Ian J.; Rudner, Adam D.; Couture, Jean-François; Kærn, Mads

    2016-01-01

    Conditional gene expression systems that enable inducible and reversible transcriptional control are essential research tools and have broad applications in biomedicine and biotechnology. The reverse tetracycline transcriptional activator is a canonical system for engineered gene expression control that enables graded and gratuitous modulation of target gene transcription in eukaryotes from yeast to human cell lines and transgenic animals. However, the system has a tendency to activate transcription even in the absence of tetracycline and this leaky target gene expression impedes its use. Here, we identify single amino-acid substitutions that greatly enhance the dynamic range of the system in yeast by reducing leaky transcription to undetectable levels while retaining high expression capacity in the presence of inducer. While the mutations increase the inducer concentration required for full induction, additional sensitivity-enhancing mutations can compensate for this effect and confer a high degree of robustness to the system. The novel transactivator variants will be useful in applications where tight and tunable regulation of gene expression is paramount. PMID:27323850

  11. Combined X-Ray and fully leaky guided mode studies of the smectic layer and optic tensor configuration in a ferroelectric liquid-crystal cell.

    PubMed

    Hodder, B; Sambles, J R; Jenkins, S; Richardson, R M

    2000-10-01

    X-ray scattering together with optical characterization using fully leaky guided modes have been used for the first time to study the same ferroelectric liquid-crystal cell. This enables direct calculation of an accurate cone and chevron description of the liquid-crystal director profile since the layer structure and optic tensor configuration are both well known. PMID:11019296

  12. A leaky splicing mutation in NFU1 is associated with a particular biochemical phenotype. Consequences for the diagnosis.

    PubMed

    Ferrer-Cortès, Xènia; Narbona, Juan; Bujan, Núria; Matalonga, Leslie; Del Toro, Mireia; Arranz, José Antonio; Riudor, Encarnació; Garcia-Cazorla, Angels; Jou, Cristina; O'Callaghan, Mar; Pineda, Mercé; Montero, Raquel; Arias, Angela; García-Villoria, Judit; Alston, Charlotte L; Taylor, Robert W; Briones, Paz; Ribes, Antonia; Tort, Frederic

    2016-01-01

    Mutations in NFU1 were recently identified in patients with fatal encephalopathy. NFU1 is an iron-sulfur cluster protein necessary for the activity of the mitochondrial respiratory chain complexes I-II and the synthesis of lipoic acid. We report two NFU1 compound heterozygous individuals with normal complex I and lipoic acid-dependent enzymatic activities and low, but detectable, levels of lipoylated proteins. We demonstrated a leaky splicing regulation due to a splice site mutation (c.545+5G>A) that produces small amounts of wild type NFU1 mRNA that might result in enough protein to partially lipoylate and restore the activity of lipoic acid-dependent enzymes and the assembly and activity of complex I. These results allowed us to gain insights into the molecular basis underlying this disease and should be considered for the diagnosis of NFU1 patients. PMID:26688339

  13. Responses of Leaky Integrate-and-Fire Neurons to a Plurality of Stimuli in Their Receptive Fields.

    PubMed

    Li, Kang; Bundesen, Claus; Ditlevsen, Susanne

    2016-12-01

    A fundamental question concerning the way the visual world is represented in our brain is how a cortical cell responds when its classical receptive field contains a plurality of stimuli. Two opposing models have been proposed. In the response-averaging model, the neuron responds with a weighted average of all individual stimuli. By contrast, in the probability-mixing model, the cell responds to a plurality of stimuli as if only one of the stimuli were present. Here we apply the probability-mixing and the response-averaging model to leaky integrate-and-fire neurons, to describe neuronal behavior based on observed spike trains. We first estimate the parameters of either model using numerical methods, and then test which model is most likely to have generated the observed data. Results show that the parameters can be successfully estimated and the two models are distinguishable using model selection. PMID:27215548

  14. A new type of magnetoresistance oscillations: Interaction of a two-dimensional electron gas with leaky interface phonons

    SciTech Connect

    ZUDOV,M.A.; PONOMAREV,I.V.; EFROS,A.L.; DU,R.R.; SIMMONS,JERRY A.; RENO,JOHN L.

    2000-05-11

    The authors report a new type of oscillations in magnetoresistance observed in high-mobility two-dimensional electron gas (2DEG), in GaAs-AIGaAs heterostructures. Being periodic in 1/B these oscillations appear in weak magnetic field (B < 0.3 T) and only in a narrow temperature range (3 K < T < 7 K). Remarkably, these oscillations can be understood in terms of magneto-phonon resonance originating from the interaction of 2DEG and leaky interface-acoustic phonon modes. The existence of such modes on the GaAs:AIGaAs interface is demonstrated theoretically and their velocities are calculated. It is shown that the electron-phonon scattering matrix element exhibits a peak for the phonons carrying momentum q = 2k{sub F} (k{sub F} is the Fermi wave-vector of 2DEG).

  15. Reliability of neuronal information conveyed by unreliable neuristor-based leaky integrate-and-fire neurons: a model study

    PubMed Central

    Lim, Hyungkwang; Kornijcuk, Vladimir; Seok, Jun Yeong; Kim, Seong Keun; Kim, Inho; Hwang, Cheol Seong; Jeong, Doo Seok

    2015-01-01

    We conducted simulations on the neuronal behavior of neuristor-based leaky integrate-and-fire (NLIF) neurons. The phase-plane analysis on the NLIF neuron highlights its spiking dynamics – determined by two nullclines conditional on the variables on the plane. Particular emphasis was placed on the operational noise arising from the variability of the threshold switching behavior in the neuron on each switching event. As a consequence, we found that the NLIF neuron exhibits a Poisson-like noise in spiking, delimiting the reliability of the information conveyed by individual NLIF neurons. To highlight neuronal information coding at a higher level, a population of noisy NLIF neurons was analyzed in regard to probability of successful information decoding given the Poisson-like noise of each neuron. The result demonstrates highly probable success in decoding in spite of large variability – due to the variability of the threshold switching behavior – of individual neurons. PMID:25966658

  16. Demonstration of enhanced broadband unidirectional electromagnetic radiation enabled by a subwavelength profile leaky anisotropic zero-index metamaterial coating

    NASA Astrophysics Data System (ADS)

    Jiang, Zhi Hao; Wu, Qi; Werner, Douglas H.

    2012-09-01

    In this paper, we report a technique for creating broadband unidirectional electromagnetic radiation with a grounded nonmagnetic anisotropic zero-index metamaterial coating. We demonstrate that the leaky modes supported by the finite sized coating structure can be exploited to create a unidirectional radiation device with a subwavelength thickness of only 0.12λ. Numerical simulations and experimental characterization of the metamaterial-enabled radiator confirm the physical mechanisms governing its performance, showing a stable directive beam with an over fivefold radiation power enhancement at broadside. Due to the resulting nonmagnetic material properties, this approach provides a new path to highly efficient, small footprint, low profile, and broadband directive radiation devices for microwave and potentially even optical wavelength applications.

  17. Auto- and Crosscorrelograms for the Spike Response of Leaky Integrate-and-Fire Neurons with Slow Synapses

    NASA Astrophysics Data System (ADS)

    Moreno-Bote, Rubén; Parga, Néstor

    2006-01-01

    An analytical description of the response properties of simple but realistic neuron models in the presence of noise is still lacking. We determine completely up to the second order the firing statistics of a single and a pair of leaky integrate-and-fire neurons receiving some common slowly filtered white noise. In particular, the auto- and cross-correlation functions of the output spike trains of pairs of cells are obtained from an improvement of the adiabatic approximation introduced previously by Moreno-Bote and Parga [Phys. Rev. Lett.PRLTAO0031-9007 92, 028102 (2004)10.1103/PhysRevLett.92.028102]. These two functions define the firing variability and firing synchronization between neurons, and are of much importance for understanding neuron communication.

  18. Increased Sensitivity to Binge Alcohol-Induced Gut Leakiness and Inflammatory Liver Disease in HIV Transgenic Rats

    PubMed Central

    Banerjee, Atrayee; Abdelmegeed, Mohamed A.; Jang, Sehwan; Song, Byoung-Joon

    2015-01-01

    The mechanisms of alcohol-mediated advanced liver injury in HIV-infected individuals are poorly understood. Thus, this study was aimed to investigate the effect of binge alcohol on the inflammatory liver disease in HIV transgenic rats as a model for simulating human conditions. Female wild-type (WT) or HIV transgenic rats were treated with three consecutive doses of binge ethanol (EtOH) (3.5 g/kg/dose oral gavages at 12-h intervals) or dextrose (Control). Blood and liver tissues were collected at 1 or 6-h following the last dose of ethanol or dextrose for the measurements of serum endotoxin and liver pathology, respectively. Compared to the WT, the HIV rats showed increased sensitivity to alcohol-mediated gut leakiness, hepatic steatosis and inflammation, as evidenced with the significantly elevated levels of serum endotoxin, hepatic triglycerides, histological fat accumulation and F4/80 staining. Real-time PCR analysis revealed that hepatic levels of toll-like receptor-4 (TLR4), leptin and the downstream target monocyte chemoattractant protein-1 (MCP-1) were significantly up-regulated in the HIV-EtOH rats, compared to all other groups. Subsequent experiments with primary cultured cells showed that both hepatocytes and hepatic Kupffer cells were the sources of the elevated MCP-1 in HIV-EtOH rats. Further, TLR4 and MCP-1 were found to be upregulated by leptin. Collectively, these results show that HIV rats, similar to HIV-infected people being treated with the highly active anti-retroviral therapy (HAART), are more susceptible to binge alcohol-induced gut leakiness and inflammatory liver disease than the corresponding WT, possibly due to additive or synergistic interaction between binge alcohol exposure and HIV infection. Based on these results, HIV transgenic rats can be used as a surrogate model to study the molecular mechanisms of many disease states caused by heavy alcohol intake in HIV-infected people on HAART. PMID:26484872

  19. Onset of the Electronic Absorption Spectra of Isolated and π-Stacked Oligomers of 5,6-Dihydroxyindole: An Ab Initio Study of the Building Blocks of Eumelanin.

    PubMed

    Tuna, Deniz; Udvarhelyi, Anikó; Sobolewski, Andrzej L; Domcke, Wolfgang; Domratcheva, Tatiana

    2016-04-14

    Eumelanin is a naturally occurring skin pigment which is responsible for developing a suntan. The complex structure of eumelanin consists of π-stacked oligomers of various indole derivatives, such as the monomeric building block 5,6-dihydroxyindole (DHI). In this work, we present an ab initio wave-function study of the absorption behavior of DHI oligomers and of doubly and triply π-stacked species of these oligomers. We have simulated the onset of the electronic absorption spectra by employing the MP2 and the linear-response CC2 methods. Our results demonstrate the effect of an increasing degree of oligomerization of DHI and of an increasing degree of π-stacking of DHI oligomers on the onset of the absorption spectra and on the degree of red-shift toward the visible region of the spectrum. We find that π-stacking of DHI and its oligomers substantially red-shifts the onset of the absorption spectra. Our results also suggest that the optical properties of biological eumelanin cannot be simulated by considering the DHI building blocks alone, but instead the building blocks indole-semiquinone and indole-quinone have to be considered as well. This study contributes to advancing the understanding of the complex photophysics of the eumelanin biopolymer. PMID:27005558

  20. The "window of susceptibility" for inflammation in the immature central nervous system is characterized by a leaky blood-brain barrier and the local expression of inflammatory chemokines.

    PubMed

    Schoderboeck, Lucia; Adzemovic, Milena; Nicolussi, Eva-Maria; Crupinschi, Claudia; Hochmeister, Sonja; Fischer, Marie-Therese; Lassmann, Hans; Bradl, Monika

    2009-09-01

    Early in postnatal development, the immature central nervous system (CNS) is more susceptible to inflammation than its adult counterpart. We show here that this "window of susceptibility" is characterized by the presence of leaky vessels in the CNS, and by a global chemokine expression profile which is clearly distinct from the one observed in the adult CNS and has three important characteristics. First, it contains chemokines with known roles in the differentiation and maturation of glia and neurons. Secondly, these chemokines have been described before in inflammatory lesions of the CNS, where they are important for the recruitment of monocytes and T cells. Lastly, the chemokine profile is shaped by pathological changes like oligodendrocyte stress and attempts of myelin repair. Changes in the chemokine expression profile along with a leaky blood-brain barrier pave the ground for an accelerated development of CNS inflammation. PMID:19520164

  1. Analysis on the Radiation Property of the Bounded Modes of Periodic Leaky-Wave Structure with Finite-Length Using a Hybrid Method

    PubMed Central

    Li, Zheng; Wang, Junhong; Duan, Jianjie; Zhang, Zhan; Chen, Meie

    2016-01-01

    In this paper the radiation property of the one-dimensional periodic leaky-wave structure is analysed using a new hybrid method, which involves the mode expansion method for expanding the periodic aperture field in terms of spatial harmonics and the method of effective radiation sections for transforming the expanded fields into far fields. Using this method, the radiation of each spatial harmonic can be achieved, and the contributions of the harmonics (especially the bounded modes) to the total radiation of the periodic leaky-wave structure can be calculated. The main findings in this paper demonstrate that the bounded modes in a finite length structure have obvious contribution to the far-field radiation, which was considered to be non-radiative and always ignored in the conventional researches. PMID:26987698

  2. A Non Leaky Artemis-Deficient Mouse that Accurately Models the Human SCID Phenotype Including Resistance to Hematopoietic Stem Cell Transplantation

    PubMed Central

    Xiao, Zheng; Dunn, Elizabeth; Singh, Kanal; Khan, Imran S.; Yannone, Steven M.; Cowan, Morton J.

    2009-01-01

    Two Artemis-deficient (mArt-/-) mouse models, independently generated on 129/SvJ backgrounds have the expected T-B-NK+SCID phenotype. However, they fail to mimic the human disease due to CD4+ T-cell leakiness. Moreover, immune reconstitution in these leaky mouse models following hematopoietic stem cell transplantation (HSCT) is more easily achieved than that seen in Artemis-deficient humans. To develop a more clinically relevant animal model we backcrossed the mArt-/- mutation onto the C57Bl/6 (B6) background (99.9%) resulting in virtually no CD4+ T-cell leakiness compared to 129/SvJ mArt-/- mice (0.3±0.25% vs 19.5±15.1%, p<0.001). The non-leaky mouse was also uniquely resistant to engraftment using allogeneic mismatched HSC, comparable to what is seen with human Artemis deficiency. The genetic background also influenced Artemis-associated radiation sensitivity with differing degrees of x-ray hypersensitivity evident in 129/SvJ and B6 backgrounds with both the mArt-/- and mArt-/+ genotypes. Our results indicate that immunogenic and DNA repair phenotypes associated with Artemis deficiency are significantly altered by genetic background, which has important implications for SCID diagnosis and treatment. Moreover, the B6 mArt-/- mouse is a more accurate model for the human disease, and a more appropriate system for studying human Artemis-deficiency and for developing improved transplant and gene therapy regimens for the treatment of SCID children. PMID:19135937

  3. Suppression of leaky expression of adenovirus genes by insertion of microRNA-targeted sequences in the replication-incompetent adenovirus vector genome.

    PubMed

    Shimizu, Kahori; Sakurai, Fuminori; Tomita, Kyoko; Nagamoto, Yasuhito; Nakamura, Shin-Ichiro; Katayama, Kazufumi; Tachibana, Masashi; Kawabata, Kenji; Mizuguchi, Hiroyuki

    2014-01-01

    Leaky expression of adenovirus (Ad) genes occurs following transduction with a conventional replication-incompetent Ad vector, leading to an induction of cellular immunity against Ad proteins and Ad protein-induced toxicity, especially in the late phase following administration. To suppress the leaky expression of Ad genes, we developed novel Ad vectors by incorporating four tandem copies of sequences with perfect complementarity to miR-122a or miR-142-3p into the 3'-untranslated region (UTR) of the E2A, E4, or pIX gene, which were mainly expressed from the Ad vector genome after transduction. These Ad vectors easily grew to high titers comparable to those of a conventional Ad vector in conventional 293 cells. The leaky expression of these Ad genes in mouse organs was significantly suppressed by 2- to 100-fold, compared with a conventional Ad vector, by insertion of the miRNA-targeted sequences. Notably, the Ad vector carrying the miR-122a-targeted sequences into the 3'-UTR of the E4 gene expressed higher and longer-term transgene expression and more than 20-fold lower levels of all the Ad early and late genes examined in the liver than a conventional Ad vector. miR-122a-mediated suppression of the E4 gene expression in the liver significantly reduced the hepatotoxicity which an Ad vector causes via both adaptive and non-adaptive immune responses. PMID:26015975

  4. Visual attractiveness is leaky: the asymmetrical relationship between face and hair

    PubMed Central

    Saegusa, Chihiro; Intoy, Janis; Shimojo, Shinsuke

    2015-01-01

    Predicting personality is crucial when communicating with people. It has been revealed that the perceived attractiveness or beauty of the face is a cue. As shown in the well-known “what is beautiful is good” stereotype, perceived attractiveness is often associated with desirable personality. Although such research on attractiveness used mainly the face isolated from other body parts, the face is not always seen in isolation in the real world. Rather, it is surrounded by one’s hairstyle, and is perceived as a part of total presence. In human vision, perceptual organization/integration occurs mostly in a bottom up, task-irrelevant fashion. This raises an intriguing possibility that task-irrelevant stimulus that is perceptually integrated with a target may influence our affective evaluation. In such a case, there should be a mutual influence between attractiveness perception of the face and surrounding hair, since they are assumed to share strong and unique perceptual organization. In the current study, we examined the influence of a task-irrelevant stimulus on our attractiveness evaluation, using face and hair as stimuli. The results revealed asymmetrical influences in the evaluation of one while ignoring the other. When hair was task-irrelevant, it still affected attractiveness of the face, but only if the hair itself had never been evaluated by the same evaluator. On the other hand, the face affected the hair regardless of whether the face itself was evaluated before. This has intriguing implications on the asymmetry between face and hair, and perceptual integration between them in general. Together with data from a post hoc questionnaire, it is suggested that both implicit non-selective and explicit selective processes contribute to attractiveness evaluation. The findings provide an understanding of attractiveness perception in real-life situations, as well as a new paradigm to reveal unknown implicit aspects of information integration for emotional judgment

  5. A two-dimensional analytical model describing groundwater level fluctuations in an anisotropic and bending leaky aquifer system near estuary

    NASA Astrophysics Data System (ADS)

    Yeh, Hund-Der; Chuang, Mo-Hsiung

    2014-05-01

    Tide-induced head fluctuation in a two-dimensional estuarine aquifer system is complicated and rather important in dealing with many groundwater management or remediation problems. The conceptual model of the aquifer system we considered is anisotropic, multi-layered with a bending estuarine bank, and subject to the tidal fluctuation effects from both the sea shore and estuarine river. The solution of the model describing the groundwater head distribution in such a coastal aquifer system is developed based on the method of separation of variables and a coordinate transformation applied to the river boundary at the bend with an angle of arbitrary degree to the line perpendicular to the sea shore. The solutions by Sun (Sun H. A two-dimensional analytical solution of groundwater response to tidal loading in an estuary, Water Resour. Res. 1997; 33:1429-35) as well as Tang and Jiao (Tang Z. and J. J. Jiao, A two-dimensional analytical solution for groundwater flow in a leaky confined aquifer system near open tidal water, Hydrological Processes, 2001; 15: 573-585) can be shown to be special cases of the present solution if the degree of the bending angle is zero. On the basis of the analytical solution, the groundwater head distribution in response to estuarine boundary is examined and the influences of anisotropy, leakage, hydraulic parameters, and bending angle on the groundwater head fluctuation are investigated and discussed.

  6. Guided-Mode-Leaky-Mode-Guided-Mode Fiber Interferometer and Its High Sensitivity Refractive Index Sensing Technology.

    PubMed

    Wang, Qi; Li, Chunyue; Zhao, Chengwu; Li, Weizheng

    2016-01-01

    A cascaded symmetrical dual-taper Mach-Zehnder interferometer structure based on guided-mode and leaky-mode interference is proposed in this paper. Firstly, the interference spectrum characteristics of interferometer has been analyzed by the Finite Difference-Beam Propagation Method (FD-BPM). When the diameter of taper waist is 20 μm-30 μm, dual-taper length is 1 mm and taper distance is 4 cm-6 cm, the spectral contrast is higher, which is suitable for sensing. Secondly, experimental research on refractive index sensitivity is carried out. A refractive index sensitivity of 62.78 nm/RIU (refractive index unit) can achieved in the RI range of 1.3333-1.3792 (0%~25% NaCl solution), when the sensor structure parameters meet the following conditions: diameter of taper waist is 24 μm, dual-taper length is 837 μm and taper distance is 5.5 cm. The spectrum contrast is 0.8 and measurement resolution is 1.6 × 10(-5) RIU. The simulation analysis is highly consistent with experimental results. Research shows that the sensor has promising application in low RI fields where high-precision measurement is required due to its high sensitivity and stability. PMID:27258281

  7. Leaky wave antenna with amplitude controlled beam steering based on composite right/left-handed transmission lines

    NASA Astrophysics Data System (ADS)

    Eberspächer, M. A.; Eibert, T. F.

    2010-09-01

    An antenna comprising two different composite right/left-handed transmission line structures is proposed which enables easy beam steering at an operation frequency of 10 GHz. The composite right/left-handed transmission lines are based on planar, periodically arranged via free unit cells, implemented in microstrip technology. Both transmission lines exhibit the infinite wavelength phenomenon which occurs at 9.72 GHz and 9.89 GHz, respectively. Thus, operating the different leaky wave structures at 10 GHz, radiation with azimuth angles of ±8° and ±17° can be achieved depending on the selected input port. In order to obtain a tunable main beam direction, the radiation patterns of both structures are superimposed by feeding them simultaneously. The influence of each guiding structure, and hence the direction of the main beam, can be controlled via the feeding amplitude. As a result of this, the beam can be steered between ±17° with a gain of up to 10 dBi. The guiding structures are arranged in parallel with a clearance of a=12.2 mm which is less than half of the wavelength in free space. This allows in a further step the attachment of additional guiding structures in order to increase the tunable angle range or creating an antenna array with a small beamwidth in the elevation plane without the occurrence of grating lobes. An antenna prototype was fabricated and validated by measurements.

  8. Linear MHD Wave Propagation in Time-Dependent Flux Tube. III. Leaky Waves in Zero-Beta Plasma

    NASA Astrophysics Data System (ADS)

    Williamson, A.; Erdélyi, R.

    2016-01-01

    In this article, we evaluate the time-dependent wave properties and the damping rate of propagating fast magneto-hydrodynamic (MHD) waves when energy leakage into a magnetised atmosphere is considered. By considering a cold plasma, initial investigations into the evolution of MHD wave damping through this energy leakage will take place. The time-dependent governing equations have been derived previously in Williamson and Erdélyi (2014a, Solar Phys. 289, 899 - 909) and are now solved when the assumption of evanescent wave propagation in the outside of the waveguide is relaxed. The dispersion relation for leaky waves applicable to a straight magnetic field is determined in both an arbitrary tube and a thin-tube approximation. By analytically solving the dispersion relation in the thin-tube approximation, the explicit expressions for the temporal evolution of the dynamic frequency and wavenumber are determined. The damping rate is, then, obtained from the dispersion relation and is shown to decrease as the density ratio increases. By comparing the decrease in damping rate to the increase in damping for a stationary system, as shown, we aim to point out that energy leakage may not be as efficient a damping mechanism as previously thought.

  9. From Leaky Pipeline to Irrigation System: Minority Education through the Lens of Community-Based Participatory Research

    PubMed Central

    James, Rosalina; Starks, Helene; Segrest, Valerie; Burke, Wylie

    2014-01-01

    Background Higher education has long made efforts to increase underrepresented minority participation in biomedical research and health fields. However, relatively few minority trainees complete advanced degrees or proceed to independent research careers, a loss referred to as the “leaky pipeline.” Minority trainees may take alternate pathways to climbing the academic ladder, exiting to pursue multiple disciplinary or community-serving roles. Objective The authors propose a model for understanding minority departures from the education pipeline as a basis for nurturing careers that support community goals for health. Methods Concepts of the traditional pipeline training model are compared with a model that aligns with CBPR principles and practices. The article describes an irrigation model that incorporates informal learning from academic and community knowledge bases to prepare trainees for CBPR and interdisciplinary research. Students serve as agents that foster individual, institutional and social change needed to address health problems while attending to root causes of disparities. Conclusions Viewing minority students as agents for community engagement allows institutions to reassess the role training can play in diversifying participation in higher education and research. An irrigation model supports development of an infrastructure that optimizes success at all post-secondary levels, and enhances CBPR capacity wherever trainees live, work, and learn. Linking formal education to informal learning in context of community-based participatory research experiences can also reduce community mistrust of research while nurturing productive research partnerships with communities to address health disparities. PMID:23221293

  10. Leaky guided waves in generic bars: Numerical prediction and experimental validation by means of ultrasonic underwater testing

    SciTech Connect

    Mazzotti, Matteo; Bartoli, Ivan; Marzani, Alessandro

    2014-02-18

    Guided Ultrasonic Waves (GUWs) are used in several industrial and civil applications for the non-destructive tests and inspection of mechanical waveguides immersed in fluids. As well known, the impedance mismatch at the fluid-structure interface causes the bulk waves traveling inside the waveguide to be partially refracted in the surrounding fluid. The leakage of bulk waves involves continuous energy radiation along the propagation direction, resulting in high attenuation rates and, consequently, reduced inspection ranges. In this work, the dispersion behaviour of leaky guided waves that propagate in immersed waveguides of general cross-section is investigated. To this end, a Semi-Analytical Finite Element (SAFE) method coupled with a 2.5D Boundary Element method (BEM) is used to extract the wave dispersion equation. The proposed formulation avoids the well known limitations of analytical methods in treating complex geometries as well as those of Finite Element-based methods in representing propagation processes in unbounded domains. Numerical and experimental results are presented, in which the dispersion curves are extracted for different bars of arbitrary shape immersed in water. The results obtained in this paper can be useful for the design of testing conditions in practical applications and to tune experimental set up.

  11. Abnormalities of Thymic Stroma may Contribute to Immune Dysregulation in Murine Models of Leaky Severe Combined Immunodeficiency

    PubMed Central

    Rucci, Francesca; Poliani, Pietro Luigi; Caraffi, Stefano; Paganini, Tiziana; Fontana, Elena; Giliani, Silvia; Alt, Frederick W.; Notarangelo, Luigi Daniele

    2011-01-01

    Lymphostromal cross-talk in the thymus is essential to allow generation of a diversified repertoire of T lymphocytes and to prevent autoimmunity by self-reactive T cells. Hypomorphic mutations in genes that control T cell development have been associated with immunodeficiency and immune dysregulation both in humans and in mice. We have studied T cell development and thymic stroma architecture and maturation in two mouse models of leaky severe combined immune deficiency, carrying hypomorphic mutations in rag1 and lig4 genes. Defective T cell development was associated with abnormalities of thymic architecture that predominantly affect the thymic medulla, with reduction of the pool of mature medullary thymic epithelial cells (mTECs). While the ability of mTECs to express autoimmune regulator (Aire) is preserved in mutant mice, the frequency of mature mTECs expressing Aire and tissue-specific antigens is severely reduced. Similarly, the ability of CD4+ T cells to differentiate into Foxp3+ natural regulatory T cells is preserved in rag1 and lig4 mutant mice, but their number is greatly reduced. These data indicate that hypomorphic defects in T cell development may cause defective lymphostromal cross-talk and impinge on thymic stromal cells maturation, and thus favor immune dysregulation. PMID:21822418

  12. Spectral Intensities of Antiprotons and the Nested Leaky-box Model for Cosmic Rays in the Galaxy

    NASA Astrophysics Data System (ADS)

    Cowsik, R.; Madziwa-Nussinov, T.

    2016-08-01

    In this paper we note that the spectral intensities of antiprotons observed in Galactic cosmic rays in the energy range ˜1–300 GeV by BESS, PAMELA, and AMS instruments display nearly the same spectral shape as that generated by primary cosmic rays through their interaction with matter in the interstellar medium, without any significant modifications. More importantly, a constant residence time of ˜2.3 ± 0.7 million years in the Galactic volume, independent of the energy of cosmic rays, matches the observed intensities. A small additional component of secondary antiprotons in the energy range below 10 GeV, generated in cocoon-like regions surrounding the cosmic-ray sources, seems to be present. We discuss this result in the context of observations of other secondary components such as positrons and boron, and the bounds on anisotropy of cosmic rays. In the nested leaky-box model the spectral intensities of antiprotons and positrons can be interpreted as secondary products of cosmic-ray interactions.

  13. Spectral Intensities of Antiprotons and the Nested Leaky-box Model for Cosmic Rays in the Galaxy

    NASA Astrophysics Data System (ADS)

    Cowsik, R.; Madziwa-Nussinov, T.

    2016-08-01

    In this paper we note that the spectral intensities of antiprotons observed in Galactic cosmic rays in the energy range ∼1–300 GeV by BESS, PAMELA, and AMS instruments display nearly the same spectral shape as that generated by primary cosmic rays through their interaction with matter in the interstellar medium, without any significant modifications. More importantly, a constant residence time of ∼2.3 ± 0.7 million years in the Galactic volume, independent of the energy of cosmic rays, matches the observed intensities. A small additional component of secondary antiprotons in the energy range below 10 GeV, generated in cocoon-like regions surrounding the cosmic-ray sources, seems to be present. We discuss this result in the context of observations of other secondary components such as positrons and boron, and the bounds on anisotropy of cosmic rays. In the nested leaky-box model the spectral intensities of antiprotons and positrons can be interpreted as secondary products of cosmic-ray interactions.

  14. Planarized process for resonant leaky-wave coupled phase-locked arrays of mid-IR quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chang, C.-C.; Kirch, J. D.; Boyle, C.; Sigler, C.; Mawst, L. J.; Botez, D.; Zutter, B.; Buelow, P.; Schulte, K.; Kuech, T.; Earles, T.

    2015-03-01

    On-chip resonant leaky-wave coupling of quantum cascade lasers (QCLs) emitting at 8.36 μm has been realized by selective regrowth of interelement layers in curved trenches, defined by dry and wet etching. The fabricated structure provides large index steps (Δn = 0.10) between antiguided-array element and interelement regions. In-phase-mode operation to 5.5 W front-facet emitted power in a near-diffraction-limited far-field beam pattern, with 4.5 W in the main lobe, is demonstrated. A refined fabrication process has been developed to produce phased-locked antiguided arrays of QCLs with planar geometry. The main fabrication steps in this process include non-selective regrowth of Fe:InP in interelement trenches, defined by inductive-coupled plasma (ICP) etching, a chemical polishing (CP) step to planarize the surface, non-selective regrowth of interelement layers, ICP selective etching of interelement layers, and non-selective regrowth of InP cladding layer followed by another CP step to form the element regions. This new process results in planar InGaAs/InP interelement regions, which allows for significantly improved control over the array geometry and the dimensions of element and interelement regions. Such a planar process is highly desirable to realize shorter emitting wavelength (4.6 μm) arrays, where fabrication tolerance for single-mode operation are tighter compared to 8 μm-emitting devices.

  15. Guided-Mode-Leaky-Mode-Guided-Mode Fiber Interferometer and Its High Sensitivity Refractive Index Sensing Technology

    PubMed Central

    Wang, Qi; Li, Chunyue; Zhao, Chengwu; Li, Weizheng

    2016-01-01

    A cascaded symmetrical dual-taper Mach-Zehnder interferometer structure based on guided-mode and leaky-mode interference is proposed in this paper. Firstly, the interference spectrum characteristics of interferometer has been analyzed by the Finite Difference-Beam Propagation Method (FD-BPM). When the diameter of taper waist is 20 μm–30 μm, dual-taper length is 1 mm and taper distance is 4 cm–6 cm, the spectral contrast is higher, which is suitable for sensing. Secondly, experimental research on refractive index sensitivity is carried out. A refractive index sensitivity of 62.78 nm/RIU (refractive index unit) can achieved in the RI range of 1.3333–1.3792 (0%~25% NaCl solution), when the sensor structure parameters meet the following conditions: diameter of taper waist is 24 μm, dual-taper length is 837 μm and taper distance is 5.5 cm. The spectrum contrast is 0.8 and measurement resolution is 1.6 × 10−5 RIU. The simulation analysis is highly consistent with experimental results. Research shows that the sensor has promising application in low RI fields where high-precision measurement is required due to its high sensitivity and stability. PMID:27258281

  16. Analytical solutions of three-dimensional groundwater flow to a well in a leaky sloping fault-zone aquifer

    NASA Astrophysics Data System (ADS)

    Zhao, Yuqing; Zhang, You-Kuan; Liang, Xiuyu

    2016-08-01

    A semi-analytical solution was presented for groundwater flow due to pumping in a leaky sloping fault-zone aquifer surrounded by permeable matrices. The flow in the aquifer was descried by a three-dimensional flow equation, and the flow in the upper and lower matrix blocks are described by a one-dimensional flow equation. A first-order free-water surface equation at the outcrop of the fault-zone aquifer was used to describe the water table condition. The Laplace domain solution was derived using Laplace transform and finite Fourier transform techniques and the semi-analytical solutions in the real time domain were evaluated using the numerical inverse Laplace transform method. The solution was in excellent agreement with Theis solution combined with superposition principle as well as the solution of Huang et al. (2014). It was found that the drawdown increases as the sloping angle of the aquifer increases in early time and the impact of the angle is insignificant after pumping for a long time. The free-water surface boundary as additional source recharges the fault aquifer and significantly affect the drawdown at later time. The surrounding permeable matrices have a strong influence on drawdown but this influence can be neglected when the ratio of the specific storage and the ratio of the hydraulic conductivity of the matrices to those of the fault aquifer are less than 0.001.

  17. Translation of the shallot virus X TGB3 gene depends on non-AUG initiation and leaky scanning.

    PubMed

    Lezzhov, Alexander A; Gushchin, Vladimir A; Lazareva, Ekaterina A; Vishnichenko, Valery K; Morozov, Sergey Y; Solovyev, Andrey G

    2015-10-01

    Triple gene block (TGB), a conserved gene module found in the genomes of many filamentous and rod-shaped plant viruses, encodes three proteins, TGB1, TGB2 and TGB3, required for viral cell-to-cell movement through plasmodesmata and systemic transport via the phloem. The genome of Shallot virus X, the type species of the genus Allexivirus, includes TGB1 and TGB2 genes, but contains no canonical ORF for TGB3 protein. However, a TGB3-like protein-encoding sequence lacking an AUG initiator codon has been found in the shallot virus X (ShVX) genome in a position typical for TGB3 genes. This putative TGB3 gene is conserved in all allexiviruses. Here, we carried out sequence analysis to predict possible non-AUG initiator codons in the ShVX TGB3-encoding sequence. We further used an agroinfiltration assay in Nicotiana benthamiana to confirm this prediction. Site-directed mutagenesis was used to demonstrate that the ShVX TGB3 could be translated on a bicistronic mRNA template via a leaky scanning mechanism. PMID:26296665

  18. An efficient hexagonal switched beam antenna structure based on Fabry-Perot cavity leaky-wave antenna

    NASA Astrophysics Data System (ADS)

    Aymen El Cafsi, Mohamed; Nedil, Mourad; Osman, Lotfi; Gharsallah, Ali

    2015-11-01

    A novel design of switched beam antenna (SBA) system based on Fabry-Perot cavity leaky-wave antenna (FPC LWA) is designed and fabricated for base station operating in the unlicensed ISM central frequency band at 5.8 GHz of the wireless local area network (WLAN) standard. The proposed SBA is designed with hexagonal shape of FPC LWA Arrays in order to get 360° of coverage. The single element of FPC LWA array is composed of a patch antenna and covered by a Partially Reflective Surface (PRS), which is composed of a Metal Strip Grating and printed on a high permittivity Superstrate. First, the Transmission Line Model of FPC LWA is introduced to analyse and calculate the far-field components in E- and H planes by using the Transverse Equivalent Network. This approach is then compared with other full wave's commercial software such as Ansoft HFSS and CST Microwave Studio. Second, a parametric study is performed to evaluate the effect of the angle formed by the two successive FPC LWA on the radiation efficiency of the activate sector. To examine the performance of the proposed SBA, experimental prototype was fabricated and measured. As a result, multiple orthogonal beams (six beams) of 10 dBi of gain with low Side Lobes Level and 360° of coverage are produced. This SBA structure is suitable for WLAN communication systems.

  19. Are isolated wetlands isolated?

    USGS Publications Warehouse

    Smith, Loren M.; Euliss, Ned H.; Haukos, David A.

    2011-01-01

    While federal regulations during the past 10 years have treated isolated wetlands as unconnected to aquatic resources protected by the Clean Water Act, they provide critical ecosystem services to society that extend well beyond their wetland boundaries. The authors offer well-documented examples from the scientific literature on some of the ecosystem services provided by isolated wetlands to society and other ecosystems.

  20. Evolution of mammalian endothermic metabolism: leaky membranes as a source of heat

    SciTech Connect

    Else, P.L.; Hulbert, A.J.

    1987-07-01

    O/sub 2/ consumption was measured at 37/degrees/C in tissue slices of liver, kidney, and brain from Amphilbolurus vitticeps and Rattus norvegicus (a reptile and mammal with same weight and body temperature) both in the presence and absence of ouabain. O/sub 2/ consumption of the mammalian tissues was two to four times that of the reptilian tissues and the mammalian tissues used three to six times the energy for Na/sup +/-K/sup +/ transport than the reptilian tissues. Passive permeability to /sup 42/K/sup +/ was measured at 37/degrees/C in liver and kidney slices, and passive permeability to /sup 22/Na/sup +/ was measured at 37/degrees/C in isolated and cultured liver cells from each species. The mammalian cell membrane was severalfold leakier to both these ions than was the reptilian cell membrane, and thus the membrane pumps must use more energy to maintain the transmembrane ion gradients. It is postulated that this is a general difference between the cells of ectotherms and endotherms and thus partly explains the much higher levels of metabolism found in endothermic mammals.

  1. Building Awareness.

    ERIC Educational Resources Information Center

    Meilach, Dona Z.

    2001-01-01

    Discusses the importance of developing students' building awareness by exploring logos, or buildings that symbolize a country, to learn about architecture and the cultures in different countries. Explores categories of buildings. Includes examples of logos from around the world. (CMK)

  2. Experimental demonstration of directive Si3N4 optical leaky wave antennas with semiconductor perturbations at near infrared frequencies

    NASA Astrophysics Data System (ADS)

    Zhao, Qiancheng; Guclu, Caner; Huang, Yuwang; Campione, Salvatore; Capolino, Filippo; Boyraz, Ozdal

    2015-02-01

    Directive optical leaky wave antennas (OLWAs) with tunable radiation pattern are promising integrated optical modulation and scanning devices. OLWAs fabricated using CMOS-compatible semiconductor planar waveguide technology have the potential of providing high directivity with electrical tunability for modulation and switching capabilities. We experimentally demonstrate directive radiation from a silicon nitride (Si3N4) waveguide-based OLWA. The OLWA design comprises 50 crystalline Si perturbations buried inside the waveguide, with a period of 1 μm, each with a length of 260 nm and a height of 150 nm, leading to a directive radiation pattern at telecom wavelengths. The measured far-field radiation pattern at the wavelength of 1540 nm is very directive, with the maximum intensity at the angle of 84.4° relative to the waveguide axis and a half-power beam width around 6.2°, which is consistent with our theoretical predictions. The use of semiconductor perturbations facilitates electronic radiation control thanks to the refractive index variation induced by a carrier density change in the perturbations. To assess the electrical modulation capability, we study carrier injection and depletion in Si perturbations, and investigate the Franz-Keldysh effect in germanium as an alternative way. We theoretically show that the silicon wire modulator has a -3 dB modulation bandwidth of 75 GHz with refractive index change of 3×10-4 in depletion mode, and 350 MHz bandwidth with refractive index change of 1.5×10-2 in injection mode. The Franz-Keldysh effect has the potential to generate very fast modulation in radiation control at telecom wavelengths.

  3. Bundle Sheath Leakiness and Light Limitation during C4 Leaf and Canopy CO2 Uptake1[W][OA

    PubMed Central

    Kromdijk, Johannes; Schepers, Hans E.; Albanito, Fabrizio; Fitton, Nuala; Carroll, Faye; Jones, Michael B.; Finnan, John; Lanigan, Gary J.; Griffiths, Howard

    2008-01-01

    Perennial species with the C4 pathway hold promise for biomass-based energy sources. We have explored the extent that CO2 uptake of such species may be limited by light in a temperate climate. One energetic cost of the C4 pathway is the leakiness (φ) of bundle sheath tissues, whereby a variable proportion of the CO2, concentrated in bundle sheath cells, retrodiffuses back to the mesophyll. In this study, we scale φ from leaf to canopy level of a Miscanthus crop (Miscanthus × giganteus hybrid) under field conditions and model the likely limitations to CO2 fixation. At the leaf level, measurements of photosynthesis coupled to online carbon isotope discrimination showed that leaves within a 3.3-m canopy (leaf area index = 8.3) show a progressive increase in both carbon isotope discrimination and φ as light decreases. A similar increase was observed at the ecosystem scale when we used eddy covariance net ecosystem CO2 fluxes, together with isotopic profiles, to partition photosynthetic and respiratory isotopic flux densities (isofluxes) and derive canopy carbon isotope discrimination as an integrated proxy for φ at the canopy level. Modeled values of canopy CO2 fixation using leaf-level measurements of φ suggest that around 32% of potential photosynthetic carbon gain is lost due to light limitation, whereas using φ determined independently from isofluxes at the canopy level the reduction in canopy CO2 uptake is estimated at 14%. Based on these results, we identify φ as an important limitation to CO2 uptake of crops with the C4 pathway. PMID:18971428

  4. ESTABLISHING DIAGNOSTIC CRITERIA FOR SCID, LEAKY SCID, AND OMENN SYNDROME: THE PRIMARY IMMUNE DEFICIENCY TREATMENT CONSORTIUM EXPERIENCE

    PubMed Central

    Shearer, William T.; Dunn, Elizabeth; Notarangelo, Luigi D.; Dvorak, Christopher C.; Puck, Jennifer M.; Logan, Brent R.; Griffith, Linda M.; Kohn, Donald B.; O’Reilly, Richard J.; Fleisher, Thomas A.; Pai, Sung-Yun; Martinez, Caridad A.; Buckley, Rebecca H.; Cowan, Morton J.

    2014-01-01

    Background The approach to the diagnosis of Severe Combined Immunodeficiency Disease (SCID) and related disorders varies among institutions and countries. Objectives The Primary Immune Deficiency Treatment Consortium (PIDTC) attempted to develop a uniform set of criteria for diagnosing SCID and related disorders, and has evaluated the results as part of a retrospective study of SCID in North America. Methods Clinical records from 2000 through 2009 at 27 centers in North America were collected on 332 children treated with hematopoietic cell transplant (HCT), enzyme replacement therapy (ERT) or gene therapy (GT) for SCID and related disorders. Eligibility for inclusion in the study and classification into disease groups were established by set criteria and applied by an expert review group. Result Two hundred eighty-five (86%) of the patients were determined to be eligible and 47 (14%) were not eligible. Of the 285 eligible patients, 84% were classified as typical SCID; 13% were classified as leaky SCID, Omenn syndrome, or reticular dysgenesis; and 3% had a history of enzyme replacement or gene therapy. Detection of a genotype predicting a SCID phenotype was accepted for eligibility. Reasons for non-eligibility were failure to demonstrate either impaired lymphocyte proliferation or maternal T cell engraftment. Overall (n = 332) rates of testing were: proliferation to PHA 77%, maternal engraftment 35%, and genotype 79% (mutation identified in 62%). Conclusion Lack of complete laboratory evaluation of patients prior to HCT presents a significant barrier to definitive diagnosis of SCID and related disorders and prevented inclusion of individuals in our observational HCT study. This lesson is critical for patient care as well as the design of future, prospective treatment studies for such children, since a well-defined and consistent study population is important for precision in outcomes analysis. PMID:24290292

  5. Design challenges of EO polymer based leaky waveguide deflector for 40 Gs/s all-optical analog-to-digital converters

    NASA Astrophysics Data System (ADS)

    Hadjloum, Massinissa; El Gibari, Mohammed; Li, Hongwu; Daryoush, Afshin S.

    2016-08-01

    Design challenges and performance optimization of an all-optical analog-to-digital converter (AOADC) is presented here. The paper addresses both microwave and optical design of a leaky waveguide optical deflector using electro-optic (E-O) polymer. The optical deflector converts magnitude variation of the applied RF voltage into variation of deflection angle out of a leaky waveguide optical beam using the linear E-O effect (Pockels effect) as part of the E-O polymer based optical waveguide. This variation of deflection angle as result of the applied RF signal is then quantized using optical windows followed by an array of high-speed photodetectors. We optimized the leakage coefficient of the leaky waveguide and its physical length to achieve the best trade-off between bandwidth and the deflected optical beam resolution, by improving the phase velocity matching between lightwave and microwave on one hand and using pre-emphasis technique to compensate for the RF signal attenuation on the other hand. In addition, for ease of access from both optical and RF perspective, a via-hole less broad bandwidth transition is designed between coplanar pads and coupled microstrip (CPW-CMS) driving electrodes. With the best reported E-O coefficient of 350 pm/V, the designed E-O deflector should allow an AOADC operating over 44 giga-samples-per-seconds with an estimated effective resolution of 6.5 bits on RF signals with Nyquist bandwidth of 22 GHz. The overall DC power consumption of all components used in this AOADC is of order of 4 W and is dominated by power consumption in the power amplifier to generate a 20 V RF voltage in 50 Ohm system. A higher sampling rate can be achieved at similar bits of resolution by interleaving a number of this elementary AOADC at the expense of a higher power consumption.

  6. Stream filtration induced by pumping in a confined, unconfined or leaky aquifer bounded by two parallel streams or by a stream and an impervious stratum

    NASA Astrophysics Data System (ADS)

    Huang, Ching-Sheng; Lin, Wen-Sheng; Yeh, Hund-Der

    2014-05-01

    A mathematical model is developed for describing three-dimensional groundwater flow induced by a fully-penetrating vertical well in aquifers between two parallel streams. A general equation is adopted to represent the top boundary condition which is applicable to either a confined, unconfined or leaky aquifer. The Robin (third-type) boundary condition is employed to represent the low-permeability streambeds. The Laplace-domain head solution of the model is derived by the double-integral and Laplace transforms. The Laplace-domain solution for a stream depletion rate (SDR) describing filtration from the streams is developed based on Darcy’s law and the head solution and inverted to the time-domain result by the Crump method. In addition, the time-domain solution of SDR for the confined aquifer is developed analytically after taking the inverse Laplace transform and the time-domain solutions of SDR for the leaky and unconfined aquifers are developed using the Padé approximation. Both approximate solutions of SDR are expressed in terms of simple series and give fairly good match with the Laplace-domain SDR solution and measured data from a field experiment in New Zealand. The uncertainties in SDR predictions for the aquifers are assessed by performing the sensitivity analysis and Monte Carlo simulation. With the aid of the time-domain solutions, we have found that the effect of the vertical groundwater flow on the temporal SDR for a leaky aquifer is dominated by two lumped parameters: κ=Kvx02/(KhD2) and κ‧ = K‧D/(B‧Kv) where D is the aquifer thickness, x0 is a distance between the well and nearer stream, Kh and Kv are the aquifer horizontal and vertical hydraulic conductivities, respectively, and K‧ and B‧ are the aquitard hydraulic conductivity and thickness, respectively. When κ < 10, neglecting the vertical flow underestimates the SDR. When κ⩾10, the effect of vertical flow is negligible. When κ‧⩽10-4, the aquitard can be regarded as

  7. Conceptual design study of JSFR reactor building

    SciTech Connect

    Yamamoto, T.; Katoh, A.; Chikazawa, Y.; Ohya, T.; Iwasaki, M.; Hara, H.; Akiyama, Y.

    2012-07-01

    Japan Sodium-cooled Fast Reactor (JSFR) is planning to adopt the new concepts of reactor building. One is that the steel plate reinforced concrete is adopted for containment vessel and reactor building. The other is the advanced seismic isolation system. This paper describes the detail of new concepts for JSFR reactor building and engineering evaluation of the new concepts. (authors)

  8. Building America

    SciTech Connect

    Brad Oberg

    2010-12-31

    IBACOS researched the constructability and viability issues of using high performance windows as one component of a larger approach to building houses that achieve the Building America 70% energy savings target.

  9. Intelligent buildings

    SciTech Connect

    Atkin, B.

    1989-01-01

    The term intelligent buildings refers to today's sophisticated living environments that must support communication, energy, fire and security protection systems. This book examines a variety of topics including building automation, information technology, and systems and facilities management.

  10. Healthy Buildings?

    ERIC Educational Resources Information Center

    Grubb, Deborah

    Health problems related to school buildings can be categorized in five major areas: sick-building syndrome; health-threatening building materials; environmental hazards such as radon gas and asbestos; lead poisoning; and poor indoor air quality due to smoke, chemicals, and other pollutants. This paper provides an overview of these areas,…

  11. Field investigation of duct system performance in California light commercial buildings

    SciTech Connect

    Delp, W.W.; Matson, N.E.; Tschudy, E.

    1997-12-09

    This paper discusses field measurements of duct system performance in fifteen systems located in eight northern California buildings. Light commercial buildings, one- and two-story with package roof-top HVAC units, make up approximately 50% of the non-residential building stock in the U.S. Despite this fact little is known about the performance of these package roof-top units and their associated ductwork. These simple systems use similar duct materials and construction techniques as residential systems (which are known to be quite leaky). This paper discusses a study to characterize the buildings, quantify the duct leakage, and analyze the performance of the ductwork in these types of buildings. The study tested fifteen systems in eight different buildings located in northern California. All of these buildings had the ducts located in the cavity between the drop ceiling and the roof deck. In 50% of these buildings, this cavity was functionally outside the building`s air and thermal barriers. The effective leakage area of the ducts in this study was approximately 2.6 times that in residential buildings. This paper looks at the thermal analysis of the ducts, from the viewpoint of efficiency and thermal comfort. This includes the length of a cycle, and whether the fan is always on or if it cycles with the cooling equipment. 66% of the systems had frequent on cycles of less than 10 minutes, resulting in non-steady-state operation.

  12. Stably stratified building wakes

    SciTech Connect

    Kothari, K.M.; Peterka, J.A.; Meroney, R.N.

    1980-01-01

    The velocity and temperature wake behind an isolated building placed in a stably stratified turbulent boundary layer has been investigated utilizing wind tunnel tests and mathematical analysis. The mean velocity and mean temperature decrease but turbulence intensity and temperature fluctuation intensity increase as a result of the momentum wake. However, the vortex wake increases mean velocity and mean temperature, and decreases turbulence intensity and temperature fluctuation intensity along the centerline of the wake.

  13. Laboratory Building.

    SciTech Connect

    Herrera, Joshua M.

    2015-03-01

    This report is an analysis of the means of egress and life safety requirements for the laboratory building. The building is located at Sandia National Laboratories (SNL) in Albuquerque, NM. The report includes a prescriptive-based analysis as well as a performance-based analysis. Following the analysis are appendices which contain maps of the laboratory building used throughout the analysis. The top of all the maps is assumed to be north.

  14. Lactobacillus GG treatment ameliorates alcohol-induced intestinal oxidative stress, gut leakiness, and liver injury in a rat model of alcoholic steatohepatitis.

    PubMed

    Forsyth, Christopher B; Farhadi, Ashkan; Jakate, Shriram M; Tang, Yueming; Shaikh, Maliha; Keshavarzian, Ali

    2009-03-01

    Because only 30% of alcoholics develop alcoholic liver disease (ALD), a factor other than heavy alcohol consumption must be involved in the development of alcohol-induced liver injury. Animal and human studies suggest that bacterial products, such as endotoxins, are the second key co-factors, and oxidant-mediated gut leakiness is one of the sources of endotoxemia. Probiotics have been used to prevent and treat diseases associated with gut-derived bacterial products and disorders associated with gut leakiness. Indeed, "probiotic"Lactobacillus rhamnosus has been successfully used to treat alcohol-induced liver injury in rats. However, the mechanism of action involved in the potential beneficial effects of L. rhamnosus in alcohol liver injury is not known. We hypothesized that probiotics could preserve normal barrier function in an animal model of ALD by preventing alcohol-induced oxidative stress and thus prevent the development of hyperpermeability and subsequent alcoholic steatohepatitis (ASH). Male Sprague-Dawley rats were gavaged with alcohol twice daily (8 gm/kg) for 10 weeks. In addition, alcoholic rats were also treated with once daily gavage of either 2.5 x 10(7) live L. rhamnosus Gorbach-Goldin (LGG) or vehicle (V). Intestinal permeability (baseline and at 10 weeks) was determined using a sugar bolus and GC analysis of urinary sugars. Intestinal and liver tissues were analyzed for markers of oxidative stress and inflammation. In addition, livers were assessed histologically for severity of ASH and total fat (steatosis). Alcohol+LGG (ALC+LGG)-fed rats had significantly (P< or =.05) less severe ASH than ALC+V-fed rats. L. rhamnosus Gorbach-Goldin also reduced alcohol-induced gut leakiness and significantly blunted alcohol-induced oxidative stress and inflammation in both intestine and the liver. L. rhamnosus Gorbach-Goldin probiotic gavage significantly ameliorated ASH in rats. This improvement was associated with reduced markers of intestinal and liver

  15. Vibration isolation

    NASA Technical Reports Server (NTRS)

    Bastin, Paul

    1990-01-01

    Viewgraphs on vibration isolation are presented. Techniques to control and isolate centrifuge disturbances were identified. Topics covered include: disturbance sources in the microgravity environment; microgravity assessment criteria; life sciences centrifuge; flight support equipment for launch; active vibration isolation system; active balancing system; and fuzzy logic control.

  16. Summation of spatiotemporal input patterns in leaky integrate-and-fire neurons: application to neurons in the cochlear nucleus receiving converging auditory nerve fiber input.

    PubMed

    Kuhlmann, Levin; Burkitt, Anthony N; Paolini, Antonio; Clark, Graeme M

    2002-01-01

    The response of leaky integrate-and-fire neurons is analyzed for periodic inputs whose phases vary with their spatial location. The model gives the relationship between the spatial summation distance and the degree of phase locking of the output spikes (i.e., locking to the periodic stochastic inputs, measured by the synchronization index). The synaptic inputs are modeled as an inhomogeneous Poisson process, and the analysis is carried out in the Gaussian approximation. The model has been applied to globular bushy cells of the cochlear nucleus, which receive converging inputs from auditory nerve fibers that originate at neighboring sites in the cochlea. The model elucidates the roles played by spatial summation and coincidence detection, showing how synchronization decreases with an increase in both frequency and spatial spread of inputs. It also shows under what conditions an enhancement of synchronization of the output relative to the input takes place. PMID:11932560

  17. Determination of the flexoelectric coefficient (e1-e3) in nematic liquid crystal by using fully leaky optical-guided mode

    NASA Astrophysics Data System (ADS)

    Zheng, Guili; Zhang, Hui; Ye, Wenjiang; Zhang, Zhidong; Song, Hong-wei; Xuan, Li

    2016-02-01

    Fully leaky optical-guided mode was employed to determine the difference in the splay and bend flexoelectric coefficient (e1-e3) in negative nematic liquid crystal MS-N01300-000. The experimental curves of reflectivity versus internal angle (angle of incident light to the liquid crystal) were obtained when a laser beam passed through the hybrid-aligned nematic in-plane switching liquid crystal cell; the cell was embedded in pyramid-coupled waveguide with different alternating current (AC) and direct current (DC) voltages. The curves of the applied DC with voltage similar to that of AC shift to the left or the right. Experimental results were then compared with theoretical results derived from elastic continuum theory and multi-layer optical theory of liquid crystals. The approximate value of the flexoelectric coefficient (e1-e3) of MS-N01300-000 is 9.0 × 10-11 C/m.

  18. Effectiveness of duct sealing and duct insulation in multi-family buildings. Final report

    SciTech Connect

    Karins, N.H.; Tuluca, A.; Modera, M.

    1997-07-01

    This research investigated the cost-effectiveness of sealing and insulating the accessible portions of duct systems exposed to unconditioned areas in multifamily housing. Airflow and temperature measurements were performed in 25 apartments served by 10 systems a 9 multi-family properties. The measurements were performed before and after each retrofit, and included apartment airflow (supply and return), duct system temperatures, system fan flow and duct leakage area. The costs for each retrofit were recorded. The data were analyzed and used to develop a prototypical multifamily house. This prototype was used in energy simulations (DOE-2.1E) and air infiltration simulations (COMIS 2.1). The simulations were performed for two climates: New York City and Albany. In each climate, one simulation was performed assuming the basement was tight, and another assuming the basement was leaky. Simulation results and average retrofit costs were used to calculate cost-effectiveness. The results of the analysis indicate that sealing leaks of the accessible ductwork is cost-effective under all conditions simulated (simple payback was between 3 and 4 years). Insulating the accessible ductwork, however, is only cost-effective for buildings with leaky basement, in both climates (simple paybacks were less than 5 years). The simple payback period for insulating the ducts in buildings with tight basements was greater than 10 years, the threshold of cost-effectiveness for this research. 13 refs., 5 figs., 27 tabs.

  19. [Development and Characterization of a Novel Adenovirus Vector Exhibiting MicroRNA-mediated Suppression of the Leaky Expression of Adenovirus Genes].

    PubMed

    Shimizu, Kahori

    2015-01-01

    Replication-incompetent adenovirus (Ad) vectors have gained attention as gene delivery vehicles. Theoretically, no Ad genes should be expressed following transduction; however, Ad genes are expressed from the vector genome, leading to induction of cellular immunity against Ad proteins and Ad protein-induced toxicity. To suppress the leaky expression of Ad genes, a microRNA (miRNA)-regulated gene expression system was utilized. We developed novel Ad vectors by incorporating targeted sequences of miR-122a or miR-142-3p, which exhibit liver- or spleen-specific expression, respectively, in the 3'-untranslated region (UTR) of the E2A, E4, or pIX genes. These Ad vectors easily grew to high titers comparable to those of a conventional Ad vector in conventional human embryonic kidney 293 cells. The leaky expression of these Ad genes in mouse organs was significantly suppressed by 2- to 100-fold in an miRNA-dependent manner, compared with a conventional Ad vector, by the insertion of the miRNA-targeted sequences. Notably, the Ad vector carrying the miR-122a-targeted sequences into the 3'-UTR of the E4 gene (Ad-E4-122aT) expressed 1.5- to 34-fold higher and longer-term transgene expression and more than 20-fold lower levels of all the Ad early and late genes examined in the liver compared with a conventional Ad vector. miR-122a-mediated suppression of E4 gene expression in the liver significantly reduced the hepatotoxicity that an Ad vector causes via both adaptive and non-adaptive immune responses. Ad-E4-122aT would be a promising framework for efficient gene delivery due to its ability to mediate higher and longer-term transgene expression and lower hepatotoxicity than a conventional Ad vector. PMID:26632150

  20. Building Change into New Buildings.

    ERIC Educational Resources Information Center

    DeJong, William S.

    1997-01-01

    Whether renovating or constructing a school building, planners must give serious thought to how a building might accommodate different instructional approaches and avoid traffic or supervision nightmares. Planners must also consider aesthetics, community-school partnerships, and educational technology's role. A sidebar by James Fox and Kay Psencik…

  1. Building Portfolio

    ERIC Educational Resources Information Center

    College Management, 1974

    1974-01-01

    The combination of a prefabricated building system and a clustered terrace design has resulted in economical and aesthetically pleasing housing for students at Vassar College in Poughkeepsie, New York. (Author)

  2. Frequency response characteristics and response spectra of base-isolated and un-isolated structures

    SciTech Connect

    Mok, G.C.; Namba, H.

    1995-07-06

    The transmissibility of seismic loads through a linear base-isolation system is analyzed using an impedance method. The results show that the system acts like a {open_quotes}low-pass{close_quotes} filter. It attenuates high-frequency loads but passes through low-frequency ones. The filtering effect depends on the vibration frequencies and damping of the isolated structure and the isolation system. This paper demonstrates the benefits and design principles of base isolation by comparing the transmissibilities and response spectra of isolated and un-isolated structures. Parameters of typical isolated buildings and ground motions of the 1994 Northridge earthquake are used for the demonstration.

  3. Building a More Powerful Brain.

    ERIC Educational Resources Information Center

    Erland, Jan

    Technically speaking, brain building is called cognitive skill development and has been in the psychology domain since the early 1960s. Historically, cognitive skill improvement was isolated within progressive coastal school districts and psychologists' private offices. Cognitive skill improvement was used successfully as a treatment in these…

  4. To build capacity, build confidence

    NASA Astrophysics Data System (ADS)

    Hewitson, Bruce

    2015-07-01

    The history of attempts to spread scientific know-how beyond western centres of excellence is littered with failures. Capacity building needs long-term commitment, a critical mass of trainees, and a supportive home environment.

  5. Passive earthquake-resistance through base isolation

    SciTech Connect

    Wu, Ting-Shu; Seidensticker, R.W.

    1990-04-01

    Base isolation is an effective approach in mitigating the seismic forces transmitted to the superstructure. It is able to provide reliable protection for the superstructure, its contents and occupants. With base isolation, dynamic characteristics of the superstructure and its contents become more predictable and controllable. In recent years, different base isolation systems have been installed in various new and existing buildings, including office buildings, computer centers, buildings for high technology industries, emergency and communication centers, buildings for high technology industries, emergency and communication centers. The concept of seismic isolation is also under active investigation for nuclear power plants, where safety and reliability of these systems are of utmost importance. One such system uses laminated high-damping rubber and steel shim plates vulcanized into a solid bearing. Under a joint program between Shimizu of Japan and Argonne National Laboratory of the United States, such high-damping rubber bearings were installed in the spring of 1989 in a three-story full size test building at the Tohoku University, Sendai, Japan. Within a period of six months after their installation, this test building and the bearings have experienced more than fifteen earthquakes. Valuable information on the performance of the isolation bearings and the building has been (and is continuing to be) gathered and analyzed. Simulation studies of the effects of these earthquakes using lumped mass systems have been conducted, and are in close agreement with the actual observed responses. 3 refs., 11 figs.

  6. Team building

    SciTech Connect

    Kane, C.

    1993-04-01

    Power plants are particularly complicated projects with abundant opportunities for disputes. Efforts are beginning in the power industry to change the way the industry does business. Key elements of a comprehensive team-building approach include partnering, constructability, use of incentives, and the disputes review board.

  7. Building Community.

    ERIC Educational Resources Information Center

    Schwartz, Edward

    The purpose of this eight-unit course is to explore the values and issues of modern urban neighborhoods. It focuses on how community leaders can apply the broad principle of justice to problems of security, reciprocity, and fellowship that face most neighborhoods today. The course is intended for use by community leaders in building community…

  8. Building Trust.

    ERIC Educational Resources Information Center

    Ambler, Marjane

    1994-01-01

    Describes how an initial $1,500 grant helped build a desperately needed health clinic on the Pine Ridge Reservation. Provides the history of the clinic, from its beginning as a small grant to its ultimate development into a $400,000 solar-heated health clinic with a staff of 9 people, including a full-time physician. (MAB)

  9. Building Sinusoids

    ERIC Educational Resources Information Center

    Landers, Mara G.

    2013-01-01

    In this article, the author describes the development and implementation of a measurement-based group activity designed to support students in understanding the connection between angle magnitude and the shape of the sine function. She explains that the benefit of this activity is that it allows students to build their trigonometric knowledge…

  10. Laboratory Buildings.

    ERIC Educational Resources Information Center

    Barnett, Jonathan

    The need for flexibility in science research facilities is discussed, with emphasis on the effect of that need on the design of laboratories. The relationship of office space, bench space, and special equipment areas, and the location and distribution of piping and air conditioning, are considered particularly important. This building type study…

  11. Building Trades.

    ERIC Educational Resources Information Center

    Gudzak, Raymond

    This curriculum guide provides materials for a competency-based course in building trades at the secondary level. The curriculum design uses the curriculum infused model for the teaching of basic skills as part of vocational education and demonstrates the relationship of vocationally related skills to communication, mathematics, and science…

  12. Reactor building assembly and method of operation

    SciTech Connect

    Fennern, L.E.; Caraway, H.A.; Hsu, Li C.

    1993-06-01

    A reactor building assembly is described comprising: a reactor pressure vessel containing a reactor core for generating heat in the form of steam; a containment vessel enclosing said pressure vessel; a first enclosure surrounding said containment vessel and spaced laterally therefrom to define a first chamber there between, and having a top and a bottom; a second enclosure surrounding said first enclosure and spaced laterally therefrom to define a second chamber there between, and having a top and a bottom; a building inlet for receiving into said second chamber fresh air from outside said second enclosure; a building outlet for discharging stale air from said first chamber; a transfer duct disposed through said first enclosure selectively joining in flow communication said first and second chambers; said building inlet being disposed at said second enclosure top, said building outlet being disposed at said first enclosure top, and said transfer duct being disposed adjacent said first enclosure bottom for allowing said fresh air to flow downwardly by gravity through said second chamber and through said transfer duct into said first chamber for cooling said first chamber, said stale air flowing upwardly by natural buoyancy for discharger from said first chamber through said building outlet; an exhaust stack disposed above said building outlet and in flow communication therewith for channeling upwardly said stale air from said first chamber for discharge into the surrounding environs; and a passive first driving means for increasing flow of said stale air from said building outlet comprising: an isolation pool containing isolation water; an isolation condenser disposed in said isolation pool, and joined in flow communication with said reactor pressure vessel for receiving primary steam therefrom, said primary steam being cooled in said isolation condenser for heating said isolation water to generate secondary steam.

  13. Building Specifications

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The building in the top photo is the new home of the National Permanent Savings Bank in Washington, D.C., designed by Hartman-Cox Architects. Its construction was based on a money-saving method of preparing building specifications which derived from NASA technology developed to obtain quality construction while holding down cost of launch facilities, test centers and other structures. Written technical specifications spell out materials and components to be used on construction projects and identify the quality tests each item must pass. Specifications can have major impact on construction costs. Poorly formulated specifications can lead to unacceptable construction which must be replaced, unnecessarily high materials costs, safety hazards, disputes and often additional costs due to delays and litigation. NASA's Langley Research Center developed a novel approach to providing accurate, uniform, cost-effective specifications which can be readily updated to incorporate new building technologies. Called SPECSINTACT, it is a computerized - system accessible to all NASA centers involved in construction programs. The system contains a comprehensive catalog of master specifications applicable to many types of construction. It enables designers of any structure to call out relevant sections from computer storage and modify them to fit the needs of the project at hand. Architects and engineers can save time by concentrating their efforts on needed modifications rather than developing all specifications from scratch. Successful use of SPECSINTACT has led to a number of spinoff systems. One of the first was MASTERSPEC, developed from NASA's experience by Production Systems for Architects and Engineers, Inc., an organization established by the American Institute of Architects. MASTERSPEC, used in construction of the bank building pictured, follows the same basic format as SPECSINTACT and can be used in either automated or manual modes. The striking appearance of the bank

  14. On the aquitard-aquifer interface flow and the drawdown sensitivity with a partially penetrating pumping well in an anisotropic leaky confined aquifer

    NASA Astrophysics Data System (ADS)

    Feng, Qinggao; Zhan, Hongbin

    2015-02-01

    A mathematical model for describing groundwater flow to a partially penetrating pumping well of a finite diameter in an anisotropic leaky confined aquifer is developed. The model accounts for the jointed effects of aquitard storage, aquifer anisotropy, and wellbore storage by treating the aquitard leakage as a boundary condition at the aquitard-aquifer interface rather than a volumetric source/sink term in the governing equation, which has never developed before. A new semi-analytical solution for the model is obtained by the Laplace transform in conjunction with separation of variables. Specific attention was paid on the flow across the aquitard-aquifer interface, which is of concern if aquitard and aquifer have different pore water chemistry. Moreover, Laplace-domain and steady-state solutions are obtained to calculate the rate and volume of (total) leakage through the aquitard-aquifer interface due to pump in a partially penetrating well, which is also useful for engineers to manager water resources. The sensitivity analyses for the drawdown illustrate that the drawdown is most sensitive to the well partial penetration. It is apparently sensitive to the aquifer anisotropic ratio over the entire time of pumping. It is moderately sensitive to the aquitard/aquifer specific storage ratio at the intermediate times only. It is moderately sensitive to the aquitard/aquifer vertical hydraulic conductivity ratio and the aquitard/aquifer thickness ratio with the identical influence at late times.

  15. Building Buildings with Triangular Numbers

    ERIC Educational Resources Information Center

    Pagni, David L.

    2006-01-01

    Triangular numbers are used to unravel a new sequence of natural numbers here-to-fore not appearing on the Encyclopedia of Integer Sequences website. Insight is provided on the construction of the sequence using "buildings" as a viewable model of the sequence entries. A step-by-step analysis of the sequence pattern reveals a method for generating…

  16. Tumour exosomes display differential mechanical and complement activation properties dependent on malignant state: implications in endothelial leakiness

    PubMed Central

    Whitehead, Bradley; Wu, LinPing; Hvam, Michael Lykke; Aslan, Husnu; Dong, Mingdong; Dyrskjøt, Lars; Ostenfeld, Marie Stampe; Moghimi, Seyed Moein; Howard, Kenneth Alan

    2015-01-01

    Background Exosomes have been implicated in tumour progression and metastatic spread. Little is known of the effect of mechanical and innate immune interactions of malignant cell-derived exosomes on endothelial integrity, which may relate to increased extravasation of circulating tumour cells and, therefore, increased metastatic spread. Methods Exosomes isolated from non-malignant immortalized HCV-29 and isogenic malignant non-metastatic T24 and malignant metastatic FL3 bladder cells were characterized by nanoparticle tracking analysis and quantitative nanomechanical mapping atomic force microscopy (QNM AFM) to determine size and nanomechanical properties. Effect of HCV-29, T24 and FL3 exosomes on human umbilical vein endothelial cell (HUVEC) monolayer integrity was determined by transendothelial electrical resistance (TEER) measurements and transport was determined by flow cytometry. Complement activation studies in human serum of malignant and non-malignant cell-derived exosomes were performed. Results FL3, T24 and HCV-29 cells produced exosomes at similar concentration per cell (6.64, 6.61 and 6.46×104 exosomes per cell for FL3, T24 and HCV-29 cells, respectively) and of similar size (120.2 nm for FL3, 127.6 nm for T24 and 117.9 nm for HCV-29, respectively). T24 and FL3 cell-derived exosomes exhibited a markedly reduced stiffness, 95 MPa and 280 MPa, respectively, compared with 1,527 MPa with non-malignant HCV-29 cell-derived exosomes determined by QNM AFM. FL3 and T24 exosomes induced endothelial disruption as measured by a decrease in TEER in HUVEC monolayers, whereas no effect was observed for HCV-29 derived exosomes. FL3 and T24 exosomes traffic more readily (11.6 and 21.4% of applied exosomes, respectively) across HUVEC monolayers than HCV-29 derived exosomes (7.2% of applied exosomes). Malignant cell-derived exosomes activated complement through calcium-sensitive pathways in a concentration-dependent manner. Conclusions Malignant (metastatic and non

  17. Spectroscopy of semiconductor meta-device building blocks (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Butakov, Nikita A.; Schuller, Jon A.

    2015-09-01

    Inspired by the potential of designing highly efficient nanophotonic optical elements, numerous researchers are currently exploring the use of dielectric resonators in constructing meta-devices. A wide range of optical components have been demonstrated, including metasurfaces that act as two-dimensional lenses, gratings, and axicons. At the core of these devices is a dielectric building block, typically a Silicon nano-disk or nano-rod, that supports Mie-like leaky mode excitations with a geometrically tunable amplitude and phase response. Here we present a comprehensive experimental characterization of these building blocks. We elucidate their multipolar mode structure, and explain the dependence on the underlying substrate. We find that fundamentally new buried magnetic modes emerge in high-index substrates, and that Fabry-Perot effects in silicon-on-insulator platforms can be utilized to enhance or suppress specific modes. When individual resonators are arranged into arrays with sub-wavelength periodicities, inter-particle coupling leads to a shift in the resonant response. When the periodicities are on the same order as the operating wavelength, the localized resonances may couple with the global diffraction modes, leading to the possible formation of distinct high-quality-factor surface-lattice-resonant modes, similar to those encountered in plasmonic gratings. We conclude by exploring the behavior of resonators constructed out of active materials, such as polar materials that support phonon-polariton excitations, and phase-change materials with tunable dielectric constants.

  18. Response of an emulsion of leaky dielectric drops immersed in a simple shear flow: Drops more conductive than the suspending fluid

    NASA Astrophysics Data System (ADS)

    Fernández, Arturo

    2008-04-01

    Direct numerical simulation is used to examine the rheological properties of an emulsion of leaky dielectric fluids when an electric field is applied to the system. The emulsion consisting of neutrally buoyant drops is immersed in a simple shear flow where an electric potential difference is applied between the plates. It is assumed that drops are more conductive than the suspending fluid and that the electrical conductivity ratio between the drops and the suspending fluid, R =σi/σo, is larger than the dielectric permittivity ratio, S =ɛo/ɛi. If a single leaky dielectric drop is immersed in an electric field, this combination of properties leads to a viscous fluid motion from the equator to the poles. The response of an emulsion depends on the competition between the electrical forces and the fluid shear. This relation is quantified by the Mason number, Mn =(3λ+2)μγ˙/6(λ+1)ɛ0β2E∞2. The significance of drop deformability is measured through the electric capillary number, Ce=ɛ0β2E∞2a/γ. The microstructure and properties of an emulsion depend mainly on Mn, Ce, and R. An emulsion immersed in an electric field exhibits three different regimes for increasing Mn. When the electrical forces are substantially larger than the fluid shear, Mn <0.02, the drops aggregate in structures oriented parallel to the electric field that dictate the response of the system. At intermediate shear rates, 0.020.2, the aggregated structures are broken up, and the effect of the electrical interaction weakens. The application of an electric field leads electrorheological emulsions to exhibit an increase in their effective viscosity for the range of properties examined here, 0.001

  19. Label-free and high-sensitive detection of human breast cancer cells by aptamer-based leaky surface acoustic wave biosensor array.

    PubMed

    Chang, Kai; Pi, Yan; Lu, Weiping; Wang, Feng; Pan, Feng; Li, Fake; Jia, Shuangrong; Shi, Jianfeng; Deng, Shaoli; Chen, Ming

    2014-10-15

    A label-free and high-sensitive sensing technology for tumor cell recognition and detection was developed based on a novel 2 × 3 model of leaky surface acoustic wave (LSAW) aptasensor array. In this methodology, every resonator crystal unit of the LSAW aptasensor array had an individual oscillator circuit to work without mutual interference, and could oscillate independently with the phase shift stability of ± 0.15° in air phase and ± 0.3° in liquid phase. The aptamer was firstly assembled to the gold electrode surface of 100 MHz LiTaO3 piezoelectric crystal, which could effectively captured target cells (MCF-7 cells) based on the specific interaction between aptamer and the overexpression of MUC1 protein on tumor cell surface. The aptamer-cell complexes increased the mass loading of LSAW aptasensor and led to phase shifts of LSAW. The plot of phase shift against the logarithm of concentration of MCF-7 cells was linear over the range from 1 × 10(2) cells mL(-1) to 1 × 10(7) cells mL(-1) with a correlation coefficient of 0.994. The detection limit as low as 32 cells mL(-1) was achieved for MCF-7 cells. The LSAW aptasensor also exhibited excellent specificity and stability. In addition, this aptasensor could be regenerated for ten times without irreversible loss of activity. Therefore, the LSAW aptasensor may offer a promising approach for tumor cell detection and have great potential in clinical applications. PMID:24836014

  20. A coupled SAFE-2.5D BEM approach for the dispersion analysis of damped leaky guided waves in embedded waveguides of arbitrary cross-section.

    PubMed

    Mazzotti, M; Bartoli, I; Marzani, A; Viola, E

    2013-09-01

    The paper presents a Semi-Analytical Finite Element (SAFE) formulation coupled with a 2.5D Boundary Element Method (BEM) for the computation of the dispersion properties of viscoelastic waveguides with arbitrary cross-section and embedded in unbounded isotropic viscoelastic media. Attenuation of guided modes is described through the imaginary component of the axial wavenumber, which accounts for material damping, introduced via linear viscoelastic constitutive relations, as well as energy loss due to radiation of bulk waves in the surrounding media. Energy radiation is accounted in the SAFE model by introducing an equivalent dynamic stiffness matrix for the surrounding medium, which is derived from a regularized 2.5D boundary element formulation. The resulting dispersive wave equation is configured as a nonlinear eigenvalue problem in the complex axial wavenumber. The eigenvalue problem is reduced to a linear one inside a chosen contour in the complex plane of the axial wavenumber by using a contour integral method. Poles of leaky and evanescent modes are obtained by choosing appropriately the phase of the wavenumbers normal to the interface in compliance with the nature of the waves in the surrounding medium. Finally, the obtained eigensolutions are post-processed to compute the energy velocity and the radiated wavefield in the surrounding domain. The reliability of the method is first validated on existing results for waveguides of circular cross sections embedded in elastic and viscoelastic media. Next, the potential of the proposed numerical framework is shown by computing the dispersion properties for a square steel bar embedded in grout and for an H-shaped steel pile embedded in soil. PMID:23642317

  1. Evidence for changes in stratospheric transport and mixing over the past three decades based on multiple data sets and tropical leaky pipe analysis

    NASA Astrophysics Data System (ADS)

    Ray, Eric A.; Moore, Fred L.; Rosenlof, Karen H.; Davis, Sean M.; Boenisch, Harald; Morgenstern, Olaf; Smale, Dan; Rozanov, Eugene; Hegglin, Michaela; Pitari, Gianni; Mancini, Eva; Braesicke, Peter; Butchart, Neal; Hardiman, Steven; Li, Feng; Shibata, Kiyotaka; Plummer, David A.

    2010-11-01

    Variability in the strength of the stratospheric Lagrangian mean meridional or Brewer-Dobson circulation and horizontal mixing into the tropics over the past three decades are examined using observations of stratospheric mean age of air and ozone. We use a simple representation of the stratosphere, the tropical leaky pipe (TLP) model, guided by mean meridional circulation and horizontal mixing changes in several reanalyses data sets and chemistry climate model (CCM) simulations, to help elucidate reasons for the observed changes in stratospheric mean age and ozone. We find that the TLP model is able to accurately simulate multiyear variability in ozone following recent major volcanic eruptions and the early 2000s sea surface temperature changes, as well as the lasting impact on mean age of relatively short-term circulation perturbations. We also find that the best quantitative agreement with the observed mean age and ozone trends over the past three decades is found assuming a small strengthening of the mean circulation in the lower stratosphere, a moderate weakening of the mean circulation in the middle and upper stratosphere, and a moderate increase in the horizontal mixing into the tropics. The mean age trends are strongly sensitive to trends in the horizontal mixing into the tropics, and the uncertainty in the mixing trends causes uncertainty in the mean circulation trends. Comparisons of the mean circulation and mixing changes suggested by the measurements with those from a recent suite of CCM runs reveal significant differences that may have important implications on the accurate simulation of future stratospheric climate.

  2. 2. View northwest of main hospital building complex, hospital building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View northwest of main hospital building complex, hospital building (Building 90), administration and clinical hospital building (Building 88), and hospital building (Building 91) - National Home for Disabled Volunteer Soldiers Western Branch, 4101 South Fourth Street, Leavenworth, Leavenworth County, KS

  3. Commercial Buildings Energy Consumption Survey - Office Buildings

    EIA Publications

    2010-01-01

    Provides an in-depth look at this building type as reported in the 2003 Commercial Buildings Energy Consumption Survey. Office buildings are the most common type of commercial building and they consumed more than 17% of all energy in the commercial buildings sector in 2003. This special report provides characteristics and energy consumption data by type of office building (e.g. administrative office, government office, medical office) and information on some of the types of equipment found in office buildings: heating and cooling equipment, computers, servers, printers, and photocopiers.

  4. Building energy analysis tool

    DOEpatents

    Brackney, Larry; Parker, Andrew; Long, Nicholas; Metzger, Ian; Dean, Jesse; Lisell, Lars

    2016-04-12

    A building energy analysis system includes a building component library configured to store a plurality of building components, a modeling tool configured to access the building component library and create a building model of a building under analysis using building spatial data and using selected building components of the plurality of building components stored in the building component library, a building analysis engine configured to operate the building model and generate a baseline energy model of the building under analysis and further configured to apply one or more energy conservation measures to the baseline energy model in order to generate one or more corresponding optimized energy models, and a recommendation tool configured to assess the one or more optimized energy models against the baseline energy model and generate recommendations for substitute building components or modifications.

  5. PHYSICAL MODELING OF CONCENTRATION DISTRIBUTIONS AROUND TWIN HIGH-RISE BUILDINGS WITH A DISTRICT HEATING PLANT

    EPA Science Inventory

    A wind tunnel experiment was conducted to investigate the effects of three high-rise building configurations on the diffusion of emissions released near the downstream base of the buildings. he building configurations included an isolated high-rise building, two high-rise buildin...

  6. Building America

    SciTech Connect

    Brad Oberg

    2010-12-31

    Builders generally use a 'spec and purchase' business management system (BMS) when implementing energy efficiency. A BMS is the overall operational and organizational systems and strategies that a builder uses to set up and run its company. This type of BMS treats building performance as a simple technology swap (e.g. a tank water heater to a tankless water heater) and typically compartmentalizes energy efficiency within one or two groups in the organization (e.g. purchasing and construction). While certain tools, such as details, checklists, and scopes of work, can assist builders in managing the quality of the construction of higher performance homes, they do nothing to address the underlying operational strategies and issues related to change management that builders face when they make high performance homes a core part of their mission. To achieve the systems integration necessary for attaining 40% + levels of energy efficiency, while capturing the cost tradeoffs, builders must use a 'systems approach' BMS, rather than a 'spec and purchase' BMS. The following attributes are inherent in a systems approach BMS; they are also generally seen in quality management systems (QMS), such as the National Housing Quality Certification program: Cultural and corporate alignment, Clear intent for quality and performance, Increased collaboration across internal and external teams, Better communication practices and systems, Disciplined approach to quality control, Measurement and verification of performance, Continuous feedback and improvement, and Whole house integrated design and specification.

  7. East side. Building 517 is to the right. Building 511 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    East side. Building 517 is to the right. Building 511 is to the left. - Fitzsimons General Hospital, Central Service Building, North of Building No. 511, East of corridor connecting Building 511 to Building 515, Aurora, Adams County, CO

  8. Wind interference effect on an octagonal plan shaped tall building due to square plan shaped tall buildings

    NASA Astrophysics Data System (ADS)

    Kar, Rony; Dalui, Sujit Kumar

    2016-03-01

    The variation of pressure at the faces of the octagonal plan shaped tall building due to interference of three square plan shaped tall building of same height is analysed by computational fluid dynamics module, namely ANSYS CFX for 0° wind incidence angle only. All the buildings are closely spaced (distance between two buildings varies from 0.4 h to 2 h, where h is the height of the building). Different cases depending upon the various positions of the square plan shaped buildings are analysed and compared with the octagonal plan shaped building in isolated condition. The comparison is presented in the form of interference factors (IF) and IF contours. Abnormal pressure distribution is observed in some cases. Shielding and channelling effect on the octagonal plan shaped building due to the presence of the interfering buildings are also noted. In the interfering condition the pressure distribution at the faces of the octagonal plan shaped building is not predictable. As the distance between the principal octagonal plan shaped building and the third square plan shaped interfering building increases the behaviour of faces becomes more systematic. The coefficient of pressure (C p) for each face of the octagonal plan shaped building in each interfering case can be easily found if we multiply the IF with the C p in the isolated case.

  9. BUILDING 341 Seismic Evaluation

    SciTech Connect

    Halle, J.

    2015-06-15

    The Seismic Evaluation of Building 341 located at Lawrence Livermore National Laboratory in Livermore, California has been completed. The subject building consists of a main building, Increment 1, and two smaller additions; Increments 2 and 3.

  10. Building 1100--NASA

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Building 1100 is the NASA administrative building. Services located in this building include two banks, a post office, barber shop, cafeteria, snack bar, travel agency, dry cleaners, the NASA Exchange retail store and medical facilities for employees.