Leaky System Research Articles

LowTempGAL: a highly responsive low temperature-inducible GAL system in Saccharomyces cerevisiae.

Temperature is an important control factor for biologics biomanufacturing in precision fermentation. Here, we explored a highly responsive low temperature-inducible genetic system (LowTempGAL) in the model yeast Saccharomyces cerevisiae. Two temperature biosensors, a heat-inducible degron and a heat-inducible protein aggregation domain, were used to regulate the GAL activator Gal4p, rendering the leaky LowTempGAL systems. Boolean-type induction was achieved by implementing a second-layer control through low-temperature-mediated repression on GAL repressor gene GAL80, but suffered delayed response to low-temperature triggers and a weak response at 30°C. Application potentials were validated for protein and small molecule production. Proteomics analysis suggested that residual Gal80p and Gal4p insufficiency caused suboptimal induction. 'Turbo' mechanisms were engineered through incorporating a basal Gal4p expression and a galactose-independent Gal80p-supressing Gal3p mutant (Gal3Cp). Varying Gal3Cp configurations, we deployed the LowTempGAL systems capable for a rapid stringent high-level induction upon the shift from a high temperature (37-33°C) to a low temperature (≤30°C). Overall, we present a synthetic biology procedure that leverages 'leaky' biosensors to deploy highly responsive Boolean-type genetic circuits. The key lies in optimisation of the intricate layout of the multi-factor system. The LowTempGAL systems may be applicable in non-conventional yeast platforms for precision biomanufacturing.

Formulation of Generalized Hillslope Leakage-Dependent Model for Groundwater Flow in N-Aquifer System within a Sedimentary Basin

In this study, the recently derived Hillslope Leakage-dependent (HL-D) models for groundwater flow in leaky three-aquifer system have been generalized to obtain Generalized Hillslope Leakage-dependent, GHL-D equation that model groundwater flow in leaky n-aquifer system. This generalization extends the capability of Hillslope Leakage-dependent (HL-D) equations to modeling groundwater flow in any number of aquifers (n-aquifer system) of all configurations within a sedimentary basin. The formulated GHL-D Model was tested on some aquifer types and the results have shown that it can be used to obtain groundwater flow models for both hillslope (sloping) and horizontal single aquifer (unconfined and confined) as well as for multi-aquifer system containing any number of aquifers within a sedimentary basin. This unique feature of GHL-D equation to model most aquifers types and configurations makes it a more elegant groundwater flow modeling tool with potentials for wider applications than most of the existing groundwater flow models. The GHL-D Model, when use for simulations of groundwater flow in single or multi-aquifer system, will have the capability of giving better understanding of the groundwater flow dynamics in such systems. This is important because most of the sedimentary basins of the world are multi-aquifer in nature and accurate knowledge of groundwater flow within them is important to geoscientists in determining long time yield and water sustainability in such geological structures

Climate controls on nitrate dynamics and gross nitrogen cycling response to nitrogen deposition in global forest soils

Understanding the patterns and controls regulating nitrogen (N) transformation and its response to N enrichment is critical to re-evaluating soil N limitation or availability and its environmental consequences. Nevertheless, how climatic conditions affect nitrate dynamics and the response of gross N cycling rates to N enrichment in forest soils is still only rudimentarily known. Through collecting and analyzing 4426-single and 769-paired observations from 231 15N labeling studies, we found that nitrification capacity [the ratio of gross autotrophic nitrification (GAN) to gross N mineralization (GNM)] was significantly lower in tropical/subtropical (19%) than in temperate (68%) forest soils, mainly due to the higher GNM and lower GAN in tropical/subtropical regions resulting from low C/N ratio and high precipitation, respectively. However, nitrate retention capacity [the ratio of dissimilatory nitrate reduction to ammonium (DNRA) plus gross nitrate immobilization (INO3) to gross nitrification] was significantly higher in tropical/subtropical (86%) than in temperate (54%) forest soils, mainly due to the higher precipitation and GNM of tropical/subtropical regions, which stimulated DNRA and INO3. As a result, the ratio of GAN to ammonium immobilization (INH4) was significantly higher in temperate than in tropical/subtropical soils. Climatic rather than edaphic factors control heterotrophic nitrification rate (GHN) in forest soils. GHN significantly increased with increasing temperature in temperate regions and with decreasing precipitation in tropical/subtropical regions. In temperate forest soils, gross N transformation rates were insensitive to N enrichment. In tropical/subtropical forests, however, N enrichment significantly stimulated GNM, GAN and GAN to INH4 ratio, but inhibited INH4 and INO3 due to reduced microbial biomass and pH. We propose that temperate forest soils have higher nitrification capacity and lower nitrate retention capacity, implying a higher potential risk of N losses. However, tropical/subtropical forest systems shift from a conservative to a leaky N-cycling system in response to N enrichment.

A Self-Calibration of Leaky VNA System for In-Fixture Measurements

A Self-Calibration of Leaky VNA System for In-Fixture Measurements

Occurrence and sources of residues of drugs of abuse in an urban aquifer: Chemical analysis and solute transport modelling

This study investigated the occurrence and potential sources of residues of drugs of abuse in an urban aquifer beneath the City of Ljubljana using water analysis and a solute transport model designed to predict nitrogen distribution. Samples were collected from three sources: 28 wastewater samples (24-h composites), 4 aquifer-recharging river samples (grab), and 22 groundwater samples. The samples were analysed for residues of commonly (ab)used licit drugs (nicotine and alcohol), medications of abuse (morphine, methadone, codeine, and ketamine), and illicit drugs (tetrahydrocannabinol – THC, cocaine, amphetamines, and heroin) using liquid-liquid (alcohol residue) and solid-phase extraction, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, we used solute transport modelling to predict the spatial distribution of drug residues in the aquifer and their potential sources. Nicotine (up to 45,7 ng/L), cotinine (up to 5.86 ng/L), trans-3′-hydroxycotinine (up to 0.528 ng/L) and benzoylecgonine (up to 0.572 ng/L) were the most commonly detected drug residues in groundwater, followed by cocaine (<LOQ). In comparison, methadone (0.054 ng/L) was detected only once. A higher prevalence of residues of drugs of abuse was observed in samples obtained at the south-eastern edge of the aquifer, downgradient from the main zone of urbanisation, agreeing with model predictions. Although drug residues were detected in river water, modelling suggests that the city's leaky sewer system is the primary source of drug residues.

Impact of urban geology on model simulations of shallow groundwater levels and flow paths

Abstract. This study examines the impact of urban geology and spatial discretization on the simulation of shallow groundwater levels and flow paths at the city scale. The study uses an integrated hydrological model based on the MIKE SHE code that couples surface water and 3D groundwater simulations with a leaky sewer system. The effect of the geological configuration was analyzed by applying three geological models to an otherwise identical hydrological model. The effect of spatial discretization was examined by using two different horizontal discretizations for the hydrological models of 50 and 10 m, respectively. The impact of the geological configuration and spatial discretization was analyzed based on model calibration, simulations of high water levels, and particle tracking. The results show that a representation of the subsurface infrastructure, and near-terrain soil types, in the geological model impacts the simulation of the high water levels when the hydrological model is simulated in a 10 m discretization. This was detectable even though the difference between the geological models only occurs in 7 % of the volume of the geological models. When the hydrological model was run in a 50 m horizontal discretization, the impact of the urban geology on the high water levels was smoothed out. Results from particle tracking show that representing the subsurface infrastructure in the hydrological model changed the particles' flow paths and travel time to sinks in both the 50 and 10 m horizontal discretization of the hydrological model. It caused less recharge to deeper aquifers and increased the percentage of particles flowing to saturated-zone drains and leaky sewer pipes. In conclusion, the results indicate that even though the subsurface infrastructure and fill material only occupy a small fraction of the shallow geology, it affects the simulation of local water levels and substantially alters the flow paths. The comparison of the spatial discretization demonstrates that, to simulate this effect, the spatial discretization needs to be of a scale that represents the local variability in the shallow urban geology.

Multilayer dripping handrail: Modeling accretion disk dynamics with cellular automaton leaky faucet model

We study the behavior of a Multilayer Dripping Handrail model of the accretion disk, which is based upon a cellular automaton approach inspired by Yonehara et al. (1997). In combination with the Mass–Spring model of a leaky faucet system first proposed by Shaw (1984) and later modified by Kiyono and Fuchikami (1999). Mass–Spring model serves the purpose of critical condition for the dripping mechanism redistributing accreting mass into lower disk annuli. As falling matter loses energy, we model the accretion disk’s temperature distribution and radiative output. Our primary focus is on modeling the temperature distribution changes, of which the main manifestation is the flickering in extracted synthetic light curves.

1-D convolution neural network based leak detection, location and size estimation in smart water grid

ABSTRACT Water is one of the essential natural resources for survival, but the water transportation system faces significant challenges because of huge water loss due to leaky pipeline systems. An IoT based novel SWG prototype has been developed and reported in this work. The SWG comprises sensors and devices that can continuously and remotely monitor the pressure, temperature, flow, pH, turbidity, etc., of the water being transported. Moreover, a novel 1-D CNN model has been developed by creating an artificial leak on the pipeline that takes input data points as a chunk of 5-minute time series to the network and gives output in leak detection, location and size estimation simultaneously. Further, the developed model is compared with other state of the art machine learning techniques and the proposed model is found better in terms of accuracy which is 94.32%, 91.91% and 89.85% for leak detection, size estimation and location respectively.

A review of physical experiments for leak detection in water pipes through transient tests for addressing future research

ABSTRACT Since the 1990s, pressure waves propagating in pressurized pipes during a transient event have been re-evaluated both in the laboratory and in real systems as a way to obtain information about location and size of leaks. However, a systematic analysis of the obtained results has not been offered yet in the literature. In this paper, a review of the available experimental data concerning the use of transient tests for leak identification in pressurized pipe systems is presented. The selected data are examined with regard to the main features (categories) influencing the transient response of a leaky pipe system: layout, modality of transient generation, material, diameter, pre-transient pressure and flow condition, inserted pressure wave, and leak characteristics. Moreover, for each of such categories, possible specific issues to address for future research are proposed.

Spatiotemporal Analysis of Electromagnetic Field Coherence in Complex Media

We study the coherence in time and space of electromagnetic fields propagated through complex media. Whether for localization, imaging, or telecommunication, the development of dedicated numerical techniques is generally based on the exploitation of simplified models considering either coherent or diffuse fields. The optimization of such applications in conditions of partial coherence can therefore be particularly challenging, requiring the development of hybrid algorithms adaptable to prior knowledge on the processed fields. The objective of this work is to provide numerical techniques for decomposing an electromagnetic field into subspaces that can then be filtered according to their level of spatial and temporal coherence. In contrast to the studies carried out on space-space transfer matrices notably used for the calculation of Wigner-Smith operators, these decompositions are carried out on space-time matrices in order to facilitate the study of temporal dispersion. The theory is developed for illustrative purposes using experimental results from a leaky resonant system, but seem to be applicable to any scattering and reverberating media capable of transforming localized and coherent excitations into complex and diffuse distributions. To conclude this work, the proposed technique is exploited to improve image reconstruction in a millimeter-wave computational imaging demonstration. In the studied context and from a more general perspective, we propose a technique to select the most suitable subspaces for each application operating under conditions of partial coherence, whether these correspond in the most extreme cases to ballistic paths or to diffuse fields.

Stormwater runoff reduction benefits of distributed curbside infiltration devices in an urban catchment

Distributed infiltration systems can benefit downstream water bodies by reducing the runoff flowrate and volume discharges from the catchment. Investigating their runoff flowrate and volume reduction potential at the catchment scale will inform decision makers regarding their efficacy for managing catchment outflows. To this end, we conducted field investigations at the residential catchment scale for three years. The study monitored the catchment for one year before the installation of leaky well systems (preinstallation) and two years after installation (postinstallation). The hydrological model, calibrated to preinstallation catchment outflows, acted as a virtual control tool. Runoff flow outputs from the control model and two years of monitored runoff flow data from the postinstallation period were analysed using statistical methods. The statistical tests showed a significant 13% reduction in average flowrates in storms with a corresponding runoff flowrate of up to 50 L/s. The study further reported the ability of infiltration systems to reduce runoff volume in the catchment by 9%. This reduction was not significant, however, as per the results of the statistical analysis. We then fitted the generalized linear model (GLM) to the monitored and simulated runoff volume data. This enabled us to break down the effect of curbside infiltration systems on runoff volume according to corresponding peak flowrates during the storm. The results of the two-way ANOVA performed to detect significant differences in the regression slopes of the GLM indicated that curbside infiltration systems significantly reduced runoff volume for storms when the runoff flowrates remained below 100 L/s.

Understanding the leaky pipeline system: behavioural ecological approach to the social marketing of women thriving in STEM careers

PurposeThis paper aims to explore the complexity of the “leaky pipeline” of women in science, technology, engineering and maths (STEM) in the intriguing contexts where there are a high number of STEM graduates but a low number of women working in these fields.Design/methodology/approachThe authors conducted in-depth interviews with eight STEM “leavers” and eight “persisters” in Turkey to understand the multi-level influences on their career paths.FindingsThe behavioural ecological model is applied to enrich the understanding of women’s attrition from STEM. The authors found a complex system of actors, relationships and influences that impact the negotiations of women’s felt misfit/love of their STEM career and changing self-actualisation.Practical implicationsThe authors highlight that social marketers should consider the complex influences on even the most individualistic-looking decisions to produce systemic change.Originality/valueThis paper deepens the use of the behavioural ecological model in the ways that the layers of motivator and demotivator influences interact with women’s internal negotiations of career choice. The paper integrates classic theories (self-actualisation (Maslow, 1943) and two-factor model (Herzberg et al., 1959)) within systems social marketing.

Reactive-transport modelling of Enterococcus faecalis JH2-2 passage through water saturated sediment columns

The reuse of treated wastewater (e.g. for irrigation) is a common practice to combat water scarcity problems world-wide. However, the potential spread of opportunistic pathogens and fecal contaminants like Enterococci within the subsoil could pose serious health hazards. Additional sources (e.g., leaky sewer systems, livestock farming) aggravate this situation. This study contributes to an understanding of pathogen spread in the environment, using a combined modelling and experimental approach. The impact of quartz sediment and certain wastewater characteristics on the dissemination of Enterococcus faecalis JH2–2 is investigated.The transport processes of advection-dispersion and straining were studied by injecting conservative saline tracer and fluorescent microspheres through sediment packed columns, and evaluating resulting breakthrough curves using models. Similarly, simultaneously occurring reactive processes of microbial attachment, decay, respiration and growth were studied by injecting Enterococcus faecalis JH2–2 suspended in water with or without dissolved oxygen (DO) and nutrients through sediment, and evaluating resulting inlet and outlet concentration curves. The processes of straining, microbial decay and growth, were important when DO was absent. Irreversible attachment was important when DO was present. Sensitivity analysis of each parameter was conducted, and field scale behavior of the processes was predicted, to facilitate future work.

Concepts on Train-to-Ground Wireless Communication System for Hyperloop: Channel, Network Architecture, and Resource Management

Hyperloop is envisioned as a novel transportation way with merits of ultra-high velocity and great traveling comforts. In this paper, we present some concepts on the key technologies dedicated to the train-to-ground communication system based on some prevailing fifth-generation communication (5G) technologies from three aspects: wireless channel, network architecture, and resource management. First, we characterize the wireless channel of the distributed antenna system (DAS) using the propagation-graph channel modelling theory. Simulation reveals that a drastic Doppler shift variation appears when crossing the trackside antenna. Hence, the leaky waveguide system is a promising way to provide a stable receiving signal. In this regard, the radio coverage is briefly estimated. Second, a cloud architecture is utilized to integrate several successive trackside leaky waveguides into a logical cell to reduce the handover frequency. Moreover, based on a many-to-many mapping relationship between distributed units (DUs) and centralized units (CUs), a novel access network architecture is proposed to reduce the inevitable handover cost by using the graph theory. Simulation results show that this scheme can yield a low handover cost. Then, with regards to the ultra-reliable and low latency communication (uRLLC) traffic, a physical resource block (PRB) multiplexing scheme considering the latency requirements of each traffic type is exploited. Simulation presents that this scheme can maximize the throughput of non-critical mission communication services while guaranteeing the requirements of uRLLC traffic. Finally, in terms of the non-critical mission communication services, two cache-based resource management strategies are proposed to boost the throughput and reduce the midhaul link burden by pre-fetching and post-uploading schemes. Simulation demonstrates that the cache-based schemes can boost the throughput dramatically.

Suspension Jams in a Leaky Microfluidic Channel.

Inspired by the jamming in leaky systems that arises in many physiological and industrial settings, we study the propagation of clogs in a leaky microfluidic channel. By driving a colloidal suspension through such a channel with a fluid-permeable wall adjoining a gutter, we follow the formation and propagation of jams and show that they move at a steady speed, in contrast with jams in channels that have impermeable walls. Furthermore, by varying the ratio of the resistance from the leaky wall and that of the gutter, we show that it is possible to control the shape of the propagating jam, which is typically wedge shaped. We complement our experiments with numerical simulations, where we implement an Euler-Lagrangian framework for the simultaneous evolution of both immersed colloidal particles and the carrier fluid. Finally, we show that the particle ordering in the clog can be tuned by adjusting the geometry of the leaky wall. Altogether, the leaky channel serves both as a filter and a shunt with the potential for a range of uses.

Nitrogen Mass Balance and Pressure Impact Model Applied to an Urban Aquifer

The assurance of drinking water supply is one of the biggest emerging global challenges, especially in urban areas. In this respect, groundwater and its management in the urban environment are gaining importance. This paper presents the modeling of nitrogen load from the leaky sewer system and from agriculture and the impact of this pressure on the groundwater quality (nitrate concentration) in the urban aquifer located beneath the City of Ljubljana. The estimated total nitrogen load in the model area of 58 km2 is 334 ton/year, 38% arising from the leaky sewer system and 62% from agriculture. This load was used as input into the groundwater solute transport model to simulate the distribution of nitrate concentration in the aquifer. The modeled nitrate concentrations at the observation locations were found to be on average slightly lower (2.7 mg/L) than observed, and in general reflected the observed contamination pattern. The ability of the presented model to relate and quantify the impact of pressures from different contamination sources on groundwater quality can be beneficially used for the planning and optimization of groundwater management measures for the improvement of groundwater quality.

A field and laboratory investigation of kerb side inlet pits using four media types

Kerb side inlets with adjacent leaky wells are an emerging tool to harvest stormwater and to reduce runoff volumes and peak flow rates. This is achieved by collecting the first flush runoff into kerb side storages and infiltrating this water into the surrounding soil, thereby also reducing stormwater pollutant loadings. The hydraulic performance of the kerb side inlet, filter media and surrounding soil are key factors in the performance of these systems. However, no field or laboratory data are currently available for the hydraulic performance of a kerb side tree inlet pit. In this study, 12 tree inlet pits were constructed and filled with various media types including gravel, water treatment solids (a recycled waste product), sandy loam and clay to examine (1) leaky well infiltration rates (2) emptying times of the wells and (3) the well capacity (runoff storage volume) before and after runoff filtering through the wells. Using a laboratory model, the water harvesting performance of the kerb side inlet plate was also examined for various road longitudinal slopes. Using the field and laboratory data, simulation of the well performance was undertaken using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) to assess the capacity of these systems to reduce runoff volumes at the residential street scale. It was hypothesised that the type of filter media used in leaky well systems has a significant impact on the infiltration rate, regardless of the native soil type through which the stormwater eventually infiltrates. The results showed that the infiltration rates of systems filled with gravel were significantly higher than for the other media types, and this was followed by water treatment solids, sandy loam and clay. The results of the MUSIC modelling indicated that 2.8% of the mean annual runoff volume in the catchment could be harvested by the systems at the case study site. It was found that selection of high infiltration rate media and regular maintenance are the key factors for maintaining long-term performance of these systems.

Understanding the role of physicians within the managerial structure of Russian hospitals

This article examines the role of physicians within the managerial structure of Russian hospitals. A comparative qualitative methodology with a structured assessment framework is used to conduct case studies that allow for international comparison. The research is exploratory in nature and comprises 63 individual interviews and 49 focus groups with key informants in 15 hospitals, complemented by document analysis. The material was collected between February and April 2017 in five different regions of the Russian Federation. The results reveal three major problems of hospital management in the Russian Federation. First, hospitals exhibit a leaky system of coordination with a lack of structures for horizontal exchange of information within the hospitals (meso-level). Second, at the macro-level, the governance system includes implementation gaps, lacking mechanisms for coordination between hospitals that may reinforce existing inequalities in service provision. Third, there is little evidence of a learning culture, and consequently, a risk that the same mistakes could be made repeatedly. We argue for a new approach to governing hospitals that can guide implementation of structures and processes that allow systematic and coherent coordination within and among Russian hospitals, based on modern approaches to accountability and organisational learning.

Completeness and divergence-free behavior of the quasi-normal modes using causality principle

A fundamental feature of the quasi-normal modes (QNMs), which describe light interaction with open (leaky) systems like nanoparticles, lies in the question of the completeness of the QNMs representation and in the divergence of their field profile due to their leaky behavior and complex eigenfrequency. In this article, the QNMs expansion is obtained by taking into consideration the frequency dispersion and the causality principle. The derivation based on the complex analysis ensures the completeness of the QNMs expansion and prevents from any divergence of the field profile. The general derivation is tested in the case of a one-dimensional open resonator made of a homogeneous absorptive medium with frequency dispersion given by the Lorentz model. For a harmonic excitation, the result of the QNMs expansion perfectly matches the exact formula for the field distribution outside as well as inside the resonator.

Performance of a kerb side inlet to irrigate street trees and to improve road runoff water quality: a comparison of four media types.

The TREENET inlet is an emerging water-sensitive urban design technology that consists of a novel kerb side inlet coupled with a leaky well infiltration system. The inlets have been retrofitted to existing roads since 2006; however, there is currently little information available on the effectiveness of these inlet and leaky well systems. This study investigated the performance of the kerb side inlets and leaky well system for water quality improvement prior to infiltration to native soil. The leaky wells included four filter media types, namely gravel, water treatment solids, sandy loam and clay. To compare the performance of the four filter media types, batch and column studies were performed in the laboratory. The best performance was observed using the sandy loam as a filter media, followed by clay, water treatment solids and then gravel. The selection of effective media for removal of heavy metals is important as each media type has different pollutant removal capacity, infiltration and clogging performance.