Resistance Fluctuations Research Articles

Cardiac output is not a significant source of low frequency mean arterial pressure variability

Spontaneous mean arterial pressure (MAP) variability may be mainly due to fluctuations in cardiac output (CO) and total peripheral resistance (TPR). While high frequency (HF ∼ 0.25 Hz) oscillations in MAP are ultimately driven by respiration, the source of low frequency (LF ∼ 0.1 Hz) fluctuations has not been fully elucidated. It is known that CO buffers these oscillations, but there is no evidence on its potential role in also generating them. The main goal was to determine whether CO is a source of LF variability in MAP. Six dogs were chronically instrumented to obtain beat-to-beat measurements of CO and MAP while the dogs were fully awake and at rest. A causal dynamic model was identified to relate the fluctuations in CO to MAP. The model was then used to predict the MAP fluctuations from the CO fluctuations. The CO fluctuations were able to predict about 70% of the MAP oscillations in the HF band but showed no predictive value in the LF band. Hence, respiration induces CO fluctuations in the HF band that, in turn, cause MAP oscillations, while TPR fluctuations appear to be the dominant mediator of LF fluctuations of MAP. CO is not a significant source of these oscillations, and it may only be responsible for dampening them, likely through the baroreflex.

Compression Pressure Dependence of 1/f Resistance Fluctuation in Single-Walled Carbon Nanotubes

Resistance and its fluctuation in single-walled carbon nanotubes (SWNTs) is measured using pressured powder samples. It is found that the 1/f resistance fluctuation increases exponentially with increasing compression pressure but the mean resistance is scarcely affected. Compression pressure changes the nonlinearity and phonon mode interaction in atomic vibration. These results proved that the origin of the 1/f resistance fluctuation in SWNTs is mainly the mobility fluctuation.

Nonlinear Conductivity Fluctuations in Fe-Chalcogenide Superconductors

Electric transport and voltage-noise measurements on FeTe0.5Se0.5 epitaxial thin films are reported. The films were grown by pulsed laser ablation deposition on lanthanum aluminate single crystal substrates, and subsequently patterned by ion beam etching. Several configurations, with different voltage contacts distances and different strip widths, have been measured. At low temperature and current bias, the measured low frequency 1/f noise behaves according to the standard resistance fluctuations model. Conversely, an excess unconventional 1/f noise is observed in the high-temperature region (T >; 70 K). The experimental results indicate the existence of an electric field threshold, above which nonlinear fluctuation processes are activated. The results of noise measurements correlate well with the already reported change in sign of the Hall resistance in the same temperature range. Possible correlation between the hole contribution to the electrical transport and nonlinear noise effects observed is discussed.

Switching operation improvement of phase change memory with nanoscale W plug structure by CMP process

To reduce the reset current for developing reliable high-density phase change random access memory, small bottom electrode contact (BEC) size formation is a critical process. One of the failure modes for the process is the corrosion of the tungsten (W) plug, which is caused by the W chemical mechanical polisher (CMP) process. An ultra-smooth surface of BEC nanoscale W plug structure was successfully fabricated by the CMP process, which reduced the W/phase change material (Ge 2 Sb 2 Te 5 , GST) contact resistance, and gained more homogeneous resistance distribution. Thus, the stability of the device was improved greatly by the acidic buff CMP process compared with that of the device with alkali buff owing to the reduction of W/GST connect resistance fluctuation.

Abstract 1458: Efficient isolation of circulating tumor cells in small cell lung cancer patients using size- and geometry-controlled microcavity array system.

Abstract Background: We have developed a microcavity array (MCA) system integrated with a miniaturized device for the isolation of circulating tumor cells (CTC) without relying on EpCAM expression. The MCA system allows the filtration of tumor cells from whole blood on the basis of differences in the size between tumor and blood cells. The previous study has shown that the MCA system is potentially superior to the conventional epithelial antigen-based method for detecting CTCs in non-small cell lung cancer. Recently, we further optimized the shape and porosity of MCA to efficiently isolate smaller tumor cells as in small cell lung cancer (SCLC). Here we report the results of clinical study in SCLC patients comparing MCA system to CellSearch system and exploratory study of novel rectangular-shaped MCA system. Methods: The MCA is made of nickel by electroforming and circular MCA is fabricated with 8-9 μm diameter pores. Meanwhile, novel rectangular-shaped MCA is fabricated with 5-9 μm-wide and 30-60 μm-long pores. NCI-H69 (12 μm in diameter) SCLC cells were used for spike-in experiments. CTCs were defined as cells with round to oval morphology, a visible nucleus, positive for cytokeratin and negative for CD45. For the clinical evaluation, paired peripheral blood samples were collected from 18 SCLC patients to compare the performance of the CellSearch system and the MCA system for CTC detection. Results: The recovery rate of spiked NCI-H69 cells with the rectangular-shaped MCA (80 ± 2%) was significantly higher than that with the circular MCA (67 ± 4%) (p=0.01, t-test). In addition, the carryover of leukocytes on the rectangular-shaped MCA was 7-fold lower than that on the circular MCA in the experiment using healthy donor blood. The fluctuation of flow resistance during filtration with the rectangular-shaped MCA (<1.5 kPa) was smaller than that with the circular MCA (2 kPa); the rectangular-shaped MCA enabled recovery of small tumor cells with high efficiency. In clinical study, compared to the CellSearch, the circular and rectangular-shaped MCA system identified significantly more SCLC patients (9 of 18 vs. 18 of 18 vs. 17 of 18, respectively) as CTC positive. No significant difference was observed in the CTC counts between the rectangular-shaped MCA (median 16, range 0-545 cells/7.5 mL) and the circular MCA (median 23, range 2-2329 cells/7.5 mL) (p=0.77, Wilcoxon test). In contrast, the number of captured leukocytes on the rectangular-shaped MCA was significantly lower than that on the circular MCA (p<0.0001, Wilcoxon test), suggesting that implementing the rectangular-shaped MCA diminishes a considerable number of carryover leukocytes. Conclusion: The MCA system has a potential as a tool for the efficient recovery of CTCs in small cell type tumors with high purity, while offering the additional advantages in cost, portability, and capacity to perform more detailed analyses of CTCs. Citation Format: Masahito Hosokawa, Hirotsugu Kenmotsu, Yasuhiro Koh, Tomoko Yoshino, Tsuyoshi Tanaka, Tateaki Naito, Toshiaki Takahashi, Haruyasu Murakami, Yukiko Nakamura, Asuka Tsuya, Takehito Shukuya, Akira Ono, Hiroaki Akamatsu, Reiko Watanabe, Sachiyo Ono, Hisashige Kanbara, Tadashi Matsunaga, Nobuyuki Yamamoto. Efficient isolation of circulating tumor cells in small cell lung cancer patients using size- and geometry-controlled microcavity array system. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1458. doi:10.1158/1538-7445.AM2013-1458

Low frequency resistance and critical current fluctuations in Al-based Josephson junctions

We present low-temperature measurements of the low-frequency 1/f noise arising from an ensemble of two-level fluctuators in the oxide barrier of Al/AlOx/Al Josephson junctions. The fractional noise power spectrum of the critical-current and normal-state resistance has similar magnitudes and scale linearly with temperature, implying an equivalence between the two. Compiling our results and published data, we deduce the area and temperature scaling of the noise for AlOx barrier junctions. We find that the density of two-level fluctuators in the junction barrier is similar to the typical value in glassy systems. We discuss the implications and consistency with recent qubit experiments.

Chemical Noise Produced by Equilibrium Adsorption/Desorption of Surface Pyridine at Au–Ag–Au Bimetallic Atom-Scale Junctions Studied by Fluctuation Spectroscopy

The chemical noise contained in conductance fluctuations resulting from adsorption and desorption of pyridine at Au-Ag-Au bimetallic atom-scale junctions (ASJs) exhibiting ballistic electron transport is studied using fluctuation spectroscopy. ASJs are fabricated by electrochemical Ag deposition in a Au nanogap to produce a high-conductance Ag quantum wire, followed by electromigration-induced thinning in pyridine solution to create stable ASJs. The conductance behavior of the resulting ASJs is analyzed by sequential autocorrelation and Fourier transform of the current-time data to yield the power spectral density (PSD). In these experiments the PSDs from Ag ASJs in pyridine exhibit two main frequency regions: 1/f noise originating from resistance fluctuations of the junction itself at low frequencies, and a Lorentzian noise component arising from molecular adsorption/desorption fluctuations at higher frequencies. The characteristic cutoff frequency of the Lorentzian noise component determines the relaxation time of molecular fluctuations, which, in turn, is sensitive to the kinetics of the adsorption/desorption process. The kinetics are found to depend on concentration and on the adsorption binding energy. The junction size (<5G0), on the other hand, does not affect the kinetics, as the cutoff frequency remains unchanged. Concentration-dependent adsorption free energies are interpreted as arising from a distribution of binding energies, N(E(b)), on the Ag ASJ. Other observations, such as long lifetime ASJs and two-level fluctuations in conductance, provide additional evidence for the integral role of the adsorbate in determining ASJ reorganization dynamics.

1/fPermittivity Fluctuation in Fullerene C60

The existence of 1=f fluctuation in an electrical device is a serious problem from the viewpoint of accuracy. Carbon nanotubes (CNTs) are very useful for field-effect transistors, sensors, and microscopes, but their 1=f resistance fluctuation intensity is particularly large. 1–4) Graphene attracts attention as a new material for an electric device, but it also generates a large 1=f fluctuation. 5) Many hypotheses have been proposed about the origin of 1=f fluctuation. 6,7) Regarding the carbon material, some investigations reported that the origin of 1=f fluctuation is the mobility fluctuation in the sample, 1) but some reports insisted that the origin is the trap potential fluctuation at the sample/electrode or sample/ surrounding dielectric interface. 2–4) The potential height fluctuation by the trap and de-trap of electrons modulates the mobility or tunneling probability of the barrier between the sample and the electrode. The studies of the 1=f fluctuation in electrical devices are performed mainly by focusing on the electrical resistance. We have investigated the permittivity fluctuation of a dielectric substance, but it was about the critical fluctuation near Curie temperature. 8) In the present study, fullerene C60 is used as a sample material and the permittivity fluctuations of the real and imaginary parts are measured. Fullerene has the same hexagonal structure of carbon atoms as CNTs and graphene, but it is a dielectric substance. The fluctuation of complex permittivity provides new information. In the present study, the cross-correlation coefficient of the permittivity fluctuations of the real and imaginary parts is calculated. Furthermore, the effect of air adsorption on the surface of fullerene is investigated. A flat board capacitor, whose inside is filled with fullerene, is used to measure the permittivity fluctuation. Fullerene powder of 40 mg is packed between the metal plates with a size of 100 � 100 mm 2 and the distance between the plates is 30m. The real part of the relative permittivity of fullerene C60 is 4–4.5 and it is considered that the imaginary part of it at a low frequency is very small owing to the result of optical measurement. 9) The fluctuation of permittivity is measured by using the bridge circuit and two-phase lock-in amplifier shown in Fig. 1. Part of the bridge circuit is constructed by the fullerene capacitor and the other parts are constructed by low-noise polystyrene capacitors and series resistors. The amplitude and frequency of the applied voltage V0 are 2 V and 5 kHz, respectively. The mean value of V1 is adjusted to V0=2 by the capacitor C and the series resistor R. The value of the capacitance C is 1.7 nF and the value of the equivalent series resistance R is 93 � . The complex capacitance of the fullerene capacitor can be described as

Reducing the experimental error in an experiment to determine the latent heat of vaporization of liquid nitrogen

In this work, modifications are made to a fairly simple laboratory experiment to experimentally determine the latent heat of vaporization with a substantially lower error than those previously reported. A new experimental technique of using an asynchronous data capture method is proposed for use with an adiabatic calorimeter for measurement as it isolates the measurement vessel from changes in the surroundings affecting the measured quantity. Further modifications are made to the experiment to determine the power at each instant the rate of mass drop is measured within the measurement range to ensure the errors associated with varying power resulting from resistance fluctuations are also minimized. The asynchronous data capture method proposes the use of computer control for the entire experiment, which again reduces the error in terms of delays in human reaction time. Applying these three new techniques to the experiment enables the latent heat of [Formula: see text] to be determined experimentally and results in a substantially lower error bar attached to the final value for the latent heat of vaporization of liquid nitrogen. The value of Lv = 201.2 ± 0.194 J/g differs by approximately 1% from the accepted value of 199.0 J/g (G.W.C. Kaye and T.H. Laby. Tables of physical and chemical constants, fifteenth edition. Longman, London. 1995). Sources of systematic (experimental) error are suggested and estimated for in this experiment and thus this small discrepancy is accounted for.

Sediment entrainment by debris flows: In situ measurements from the headwaters of a steep catchment

Debris flows can dramatically increase their volume, and hence their destructive potential, by entraining sediment. Yet quantitative constraints on rates and mechanics of sediment entrainment by debris flows are limited. Using an in situ sensor network in the headwaters of a natural catchment we measured flow and bed properties during six erosive debris‐flow events. Despite similar flow properties and thicknesses of bed sediment entrained across all events, time‐averaged entrainment rates were significantly faster for bed sediment that was saturated prior to flow arrival compared with rates for sediment that was dry. Bed sediment was entrained from the sediment‐surface downward in a progressive fashion and occurred during passage of dense granular fronts as well as water‐rich, inter‐surge flow.En massefailure of bed sediment along the sediment‐bedrock interface was never observed. Large‐magnitude, high‐frequency fluctuations in total normal basal stress were dissipated within the upper 5 cm of bed sediment. Within this near surface layer, concomitant fluctuations in Coulomb frictional resistance are expected, irrespective of the influence of pore fluid pressure or fluctuations in shear stress. If the near‐surface sediment was wet as it was overridden by a flow, additional large‐magnitude, high‐frequency pore pressure fluctuations were measured in the near‐surface bed sediment. These pore pressure fluctuations propagated to depth at subsonic rates and in a diffusive manner. The depth to which large excess pore pressures propagated was typically less than 10 cm, but scaled as (D/fi)0.5, in which D is the hydraulic diffusivity and fiis the frequency of a particular pore pressure fluctuation. Shallow penetration depths of granular‐normal‐stress fluctuations and excess pore pressures demonstrate that only near‐surface bed sediment experiences the full dynamic range of effective‐stress fluctuations, and as a result, can be more easily entrained than deeper sediment. These data provide robust tests for mechanical models of entrainment and demonstrate that a debris flow over wet bed sediment will be larger than the same flow over dry bed sediment.

An electron conduction model of resistive memory for resistance dispersion, fluctuation, filament structures, and Set/Reset mechanism

A model of electron conduction in a nonvolatile resistive memory is presented. The model is based on a charge transport by hopping between localized electric states and/or metal ions in insulator. A concept of dual-level electronic energy for a hopping has been introduced. This is the first physical model which explains the dispersion, distribution tail and fluctuation of the cell resistance, and random telegraph signal noise simultaneously. All of these characteristics are represented by a random combination of hopping that is described by a simple formulation of electron hopping of a stochastic process. Main parameters causing the resistance dispersion are the distance between ions and the energy gap in hopping. Current fluctuation of cells is attributed to the variation of the hopping probability. Structures of the conduction filament are discussed with relation to the conduction model. A minimum size of the conduction filament is estimated at ∼4 nm in diameter for a stable low resistive state. A Set/Reset model is presented in which the main driving force of Set/Reset is attributed to the ion drift. A Set-process is initiated by the threshold switching of the insulator. An increased electric field in the vicinity of an electrode by the threshold switching drives the ion flow along the current path. A drift diffusion model applied to the Reset-process shows that the main driving force of the Reset process is also the ion drift rather than diffusion by Joule heating.

Resistive-Switching Memory Effect of Hybrid Structures with Polyimide and Sno2 Nanocrystals

Hybrid memory devices with polyimide and SnO2 nanocrystals on a flexible polyethersulphone substrate have shown a memristor behavior from current-voltage (I-V) measurements. The resistive-switching effects with a current bistability appeared during cycling voltage sweeping within the range of +/- 4 V. This I-V switching effect might have originated from a resistance fluctuation due to the charge trapping into the SnO2 nanocrystals as well as the oxygen vacancies of the ZnO layer and aluminum oxides that were formed between the polyimide and the interface of the Al gate electrode. In the bipolar resistance-switching behavior, the ratio of the high- and low-resistance state currents was about 3.7 x 10(4) at 1 V.

Estimating traveltimes and groundwater flow patterns using 3D time-lapse crosshole ERT imaging of electrical resistivity fluctuations induced by infiltrating river water

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by river water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the river infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantify 3D bank filtration and aquifer dynamics at a high spatial resolution.

Short-term variability of blood pressure: effects of lower-body negative pressure and long-duration bed rest

Mild lower-body negative pressure (LBNP) has been utilized to selectively unload cardiopulmonary baroreceptors, but there is evidence that arterial baroreceptors can be transiently unloaded after the onset of mild LBNP. In this paper, a black box mathematical model for the prediction of diastolic blood pressure (DBP) variability from multiple inputs (systolic blood pressure, R-R interval duration, and central venous pressure) was applied to interpret the dynamics of blood pressure maintenance under the challenge of LBNP and in long-duration, head-down bed rest (HDBR). Hemodynamic recordings from seven participants in the WISE (Women's International Space Simulation for Exploration) Study collected during an experiment of incremental LBNP (-10 mmHg, -20 mmHg, -30 mmHg) were analyzed before and on day 50 of a 60-day-long HDBR campaign. Autoregressive spectral analysis focused on low-frequency (LF, ~0.1 Hz) oscillations of DBP, which are related to fluctuations in vascular resistance due to sympathetic and baroreflex regulation of vasomotor tone. The arterial baroreflex-related component explained 49 ± 13% of LF variability of DBP in spontaneous conditions, and 89 ± 9% (P < 0.05) on day 50 of HDBR, while the cardiopulmonary baroreflex component explained 17 ± 9% and 12 ± 4%, respectively. The arterial baroreflex-related variability was significantly increased in bed rest also for LBNP equal to -20 and -30 mmHg. The proposed technique provided a model interpretation of the proportional effect of arterial baroreflex vs. cardiopulmonary baroreflex-mediated components of blood pressure control and showed that arterial baroreflex was the main player in the mediation of DBP variability. Data during bed rest suggested that cardiopulmonary baroreflex-related effects are blunted and that blood pressure maintenance in the presence of an orthostatic stimulus relies mostly on arterial control.

The Influence of Electrode on Resistivity of Conductive Asphalt Concrete for Self-Monitoring

This paper focuses on an optimized research about materials and size of electrode of self-monitoring asphalt concrete. It can be easily observed and analyzed the sensitivity of the test and resistivity fluctuations by studying the changes of output resistivity in different electrode embedded in the self-monitoring asphalt concrete. Based on the above method, we can select the proper electrode for the self-monitoring asphalt concrete. The results indicate that the output resistivity of self-monitoring asphalt concrete have much more fluctuation than which used stainless steel mesh as electrode material when choosing the iron mesh as electrode material. Meanwhile, the results demonstrate that the measured output resistivity of self-monitoring asphalt concrete is the most stable when the electrode size is 40~60% of cross-sectional area.

Random Telegraph Noise in 1X-nm CMOS Silicide Contacts and a Method to Extract Trap Density

The behavior of random telegraph noise was affected by nickel silicide barrier height engineering in advanced nano-CMOS technologies. Contact resistance fluctuations with magnitude of up to 40% were observed when a Schottky barrier was reduced to 0.2 eV. The large contact resistance instability is attributed to the barrier modification by positive charge trapping and detrapping in a Schottky contact. The prevalence and magnitude of the noise are dependent on the contact area, trap density, trap energy, and the silicide Schottky barrier height. In this letter, we propose a fast method to extract the density of responsible contact traps.

Effect of disorder on the charge‐carrier dynamics in κ ‐(D8‐ET)2Cu[N(CN)2]Br

AbstractWe have applied resistance fluctuation spectroscopy to study the intrinsic low‐frequency dynamics of the charge carriers in the system κ ‐(D8‐ET)2Cu[N(CN)2]Br for two different cooling rates. A strong increase of both the resistance and the noise level is observed below the thermodynamic glass‐transition temperature Tg. Surprisingly, the data of the normalized spectral weight 〈(δR)2〉/R2 fall on top of each other for both cooling rates except for temperatures near the Mott critical point (T0 ≃ 35 K) and below 28 K. The suppression of the peak in 〈(δR)2〉/R2 associated with the Mott transition suggests that disorder is an additional parameter in the generalized phase diagram. The enhanced noise level below 28 K might be explained by a disorder‐induced staggered magnetic moment in the metallic state close to the antiferromagnetic Mott insulator. (© 2012 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Stabilization of input impedance for wireless power supply circuit

A wireless power supply transmits electrical energy from a power source to a load without the use of a connecting wire. There are a number of wireless power supply techniques including electromagnetic induction, electromagnetic radiation, and electrical conduction. Here, we have investigated methods that use electromagnetic induction. Typically, for electromagnetic induction, we assume that the load resistance will fluctuate during battery charging due to variations in the battery voltage. Therefore, to stabilize the electrical power supply, a steady input impedance of the transmission circuit is preferable such that the influence of load resistance fluctuations is minimized. To this end, we suggest a “series-parallel resonant circuit” for the transmission circuit that has this characteristic.

Resistive switching effect for ZnO hybrid memory with metal-oxide nanocrystals

ZnO memory device with SnO2 nanocrystals embedded in a biphenyl-tertracarboxylic dianhydride–phenylen diamine polyimide layer was fabricated, and its electrical properties were evaluated. The complementary resistive switching effects with a current bistability appeared during voltage sweeping in the range of ±4V and ±5V, respectively. This switching effect of current–voltage may be originated from a resistance fluctuation due to the charge trapping into SnO2 nanocrystals. In the bipolar resistance switching behavior, the ratio of high-resistance state (HRS) and low-resistance state (LRS) currents was about 4.4×104 at 1V. The data retention of LRS/HRS currents was maintained about 2.2×103 after 103s.

A filtering method to correct time-lapse 3D ERT data and improve imaging of natural aquifer dynamics

Abstract We have developed a processing methodology that allows crosshole ERT (electrical resistivity tomography) monitoring data to be used to derive temporal fluctuations of groundwater electrical resistivity and thereby characterize the dynamics of groundwater in a gravel aquifer as it is infiltrated by river water. Temporal variations of the raw ERT apparent-resistivity data were mainly sensitive to the resistivity (salinity), temperature and height of the groundwater, with the relative contributions of these effects depending on the time and the electrode configuration. To resolve the changes in groundwater resistivity, we first expressed fluctuations of temperature-detrended apparent-resistivity data as linear superpositions of (i) time series of river-water-resistivity variations convolved with suitable filter functions and (ii) linear and quadratic representations of river-water-height variations multiplied by appropriate sensitivity factors; river-water height was determined to be a reliable proxy for groundwater height. Individual filter functions and sensitivity factors were obtained for each electrode configuration via deconvolution using a one month calibration period and then the predicted contributions related to changes in water height were removed prior to inversion of the temperature-detrended apparent-resistivity data. Applications of the filter functions and sensitivity factors accurately predicted the apparent-resistivity variations (the correlation coefficient was 0.98). Furthermore, the filtered ERT monitoring data and resultant time-lapse resistivity models correlated closely with independently measured groundwater electrical resistivity monitoring data and only weakly with the groundwater-height fluctuations. The inversion results based on the filtered ERT data also showed significantly less inversion artefacts than the raw data inversions. We observed resistivity increases of up to 10% and the arrival time peaks in the time-lapse resistivity models matched those in the groundwater resistivity monitoring data.