Index For Flow Research Articles

Discussion on “ Characteristics of the Instantaneous Kinetic Energy and Agitating intensity Index for the Bath Flow Under Various Bottom Regiment Configurations” Published in the Transactions of IIM, 2024, pp. 2073–2081

Discussion on “ Characteristics of the Instantaneous Kinetic Energy and Agitating intensity Index for the Bath Flow Under Various Bottom Regiment Configurations” Published in the Transactions of IIM, 2024, pp. 2073–2081

Characteristics of the Instantaneous Kinetic Energy and Agitating Intensity Index for the Bath Flow under Various Bottom Regiment Configurations

Characteristics of the Instantaneous Kinetic Energy and Agitating Intensity Index for the Bath Flow under Various Bottom Regiment Configurations

From DNA to diagnostics: A case study using macroinvertebrate metabarcoding to assess the effectiveness of restoration measures in a Dutch stream

Stream ecosystems are under pressure due to multiple stressors. Restoration measures can halt further degradation and improve their ecological status. However, assessment of the effectiveness of the implemented measures is often insufficient because of logistic and financial constraints. DNA-metabarcoding has been proposed to scale up sample processing, although its application as a diagnostic tool has received less attention. The aim of our study was to evaluate if DNA-metabarcoding of stream macroinvertebrates can be used to compute a stressor-specific index to assess the effectiveness of a stream restoration project. For this purpose, we sampled the upstream, restored, and downstream section of a recently restored lowland stream in the Netherlands. At each site, we applied three different methods of macroinvertebrate identification: morphological identification of bulk samples (morphology), DNA-metabarcoding of the same bulk samples (DNA) and metabarcoding of eDNA extracted from the water (eDNA). First, we compared the community composition identified by each method. The communities identified by morphology and DNA were highly similar, whereas the communities generated by the eDNA differed. Second, we analysed whether the identification methods could be used to assess the effectiveness of the restoration project, focussing on a stressor-specific index for flow as the restoration measures aimed at improving flow conditions. Both the morphology and bulk DNA samples indicated improved flow conditions in the restored section of the stream (i.e., less stress from the reduction or absence of flow than in the unrestored sections). Contrary, the eDNA-water samples did not differentiate the amount of stress throughout the catchment, although applying recent developments in eDNA sampling could lead to more robust results. In conclusion, this study forms proof of concept that DNA from bulk samples can be utilized to assess the effectiveness of restoration measures, showing the added value of this approach for water managers.

Condensation Performance of Symmetrical and Parallel Capsule Plate Heat Exchangers

Condensation characteristics of symmetrical and parallel capsule plate heat exchangers were experimentally investigated in this article. Plate heat exchangers with parallel capsule corrugation, symmetrical capsule corrugation, and chevron-type corrugation are manufactured as the test sections, each containing 41 plates. Pure steam and water are the hot and cold fluids, respectively. The experiments covered a range of equivalent Reynolds number from 9,000 to 25,000, mass flux of condensing fluid from to 18 to 49 kg/(m2·s), liquid Prandtl number from 1.37 to 1.71, average vapor quality from 0.5 to 0.7, and condensation pressure from 110 to 240 kPa. The correlations of condensation heat transfer coefficient and friction factor of the symmetrical and parallel capsule plate heat exchangers are developed. Compared with chevron-type plate heat exchangers, capsule plate heat exchangers show low friction pressure drop, and 33% higher energy efficiency index for condensation flow and heat transfer. Specifically, the energy efficiency index of the symmetrical capsule plate heat exchanger is 8.6% higher than that of the parallel capsule plate heat exchanger, indicating the superiority of counter-rotating longitudinal vortices over co-rotating longitudinal vortices in condensation, similar to what is observed in single-phase flow and heat transfer.

The Diagnostic Performance of the FEF 25%-75% in the Evaluation of 34 Cases of Asthmatic Children and Adolescents Sensitized and Non-Sensitized to House Dust Mites

The guidelines for asthma and spirometry do not mention the forced expiratory flow between 25% and 75% of forced vital capacity (FEF 25%-75%) in evaluation of airflow obstruction in asthma. The aim of this study was to assess the diagnostic performance of the FEF 25%-75% of children and adolescents with asthma sensitized to house dust mites (HDM). A retrospective case series was done in the Hospital Municipal Jesus, Rio de Janeiro, Brazil with 34 participants with asthma sensitized (n=26) and non-sensitized (n=8) to HDM. Standard reference value for FEF 25%-75% was considered abnormal if below at 65% of predicted. The percentages of 62% of sensitized participants and 38% of not sensitized to HDM had asthma with small airway obstruction by FEF 25-75% index and normal reference values for large airway flow in the spirometry report according to FEV 1/FVC ratio. The means of FEF 25%-75% for HDM and non-HDM were 44.27±9.96 vs. 56.62±13.56, respectively (t=1.86, P=0.0719). The results calculated were a positive predictive value of 80%, a sensitivity of 65%, and an accuracy of 62% amongst other significant parameters (P<0.05). We concluded that the FEF 25%-75% had a high diagnostic performance in children and adolescents with asthma sensitized to HDM.

A novel multi-modal analysis model with Baidu Search Index for subway passenger flow forecasting

With the boom of big data, the Internet contains more and more personal behavior information, but it is difficult to extract effectively. A model involving multivariate processing capability must be constructed to deal with these time series with complex characteristics. In this paper, a novel hybrid model embedding Baidu Search Index is therefore proposed to implement multi-step ahead subway passenger flow forecasting. Firstly, we collect data from informative Baidu Search Index, reduce dimensionality, and screen out the powerful predictors by statistical analysis. Secondly, we extract matching common modes at similar time scales between the subway passenger flow and screened Baidu Search Index via multivariate mode decomposition being optimized by multi-objective algorithm. Furthermore, to eliminate pseudo statistical causality, we select the optimal combination of modal components between subway passenger flow and its corresponding Baidu Search Index at each time scale by an innovative multi–modal analysis strategy. Thirdly, we reconstruct the forecasting values of each selected optimal combination as the final results. The empirical results of Beijing, Shanghai and Guangzhou show that the proposed model can significantly outperform six benchmark models in both the level and directional accuracy. So introducing Baidu Search Index creates a sound opportunity to enhance the subway passenger flow forecasting ability.

A CFD study on thermohydraulic characteristics of a nanofluid in a shell-and-tube heat exchanger fitted with new unilateral ladder type helical baffles

The present study aims to research the thermohydraulic characteristics and performance index for flow of the nanofluids containing varied particle shapes including cylinder, blade, brick, platelet, and Oblate Spheroid (OS) in a shell and tube heat exchanger (STHX). The STHX is equipped with new unilateral ladder-type helical baffles to develop spiral stream inside the shell side. The nanofluid is assumed as the hot fluid that passes inside the tube side. Water is selected for the cold fluid that flows within the shell side with Reynolds numbers of 5000 to 20,000. The flow pattern developed by the baffles has noticeable impacts on the STHX performance. By the rise in the Reynolds number of the shell side, the heat transfer rate, overall heat transfer coefficient, effectiveness, Number of Transfer Unit (NTU), and pressure drop increase, whereas the performance index decreases. Moreover, the highest heat transfer rate, overall coefficient, and pressure loss belong to the nanofluid containing the platelet additives, while the greatest effectiveness, NTU, and performance index happen for the nanofluid with the OS additives. The severe cross and secondary flows are completely obvious in the shell side due to the existence of the new baffles, specially at high Reynolds numbers.

A three-scale index for flow in karst conduits in carbonate rocks

A three-scale model for flow in karst conduit networks in fractured carbonates is rigorously constructed based on a reiterated homogenization procedure. The first upscaling, performed from the high-fidelity flow model, is based on sequential partially and fully topological model reduction procedures considering two discrete networks of solution-enlarged fractures and conduits. The subsequent macroscopization procedure projects the reduced model into the cells of a coarse computational grid, where homogenized equivalent properties are numerically constructed. Such a two-level upscaling gives rise to a macroscopic flow model characterized by mass-transfer functions between the geological structures. A notable consequence of the approach proposed herein is the appearance of a new karst index concept, whose underlying physics relies on the generalization of the traditional Peaceman’s theory of well index. Such a concept rules the mass exchange between conduits and matrix and can be extended to the general scenario of coupled flow in multi-branch karst conduit systems, displaying general non-circular cross sections and surrounding damage zones. The downscaling representation for the karst index can be further explored to improve accuracy of the exchange coefficient between the geological objects. Numerical experiments are carried-out showing the magnitude of the index for certain conduit and fracture arrangements, along with illustrating the impact upon flow patterns.

Reliability of Skin Blood Flow Measurement with Multiple Laser Doppler Probes

Skin blood flow (SkBF) measurements with laser Doppler probe provide a continuous real‐time index for local microcirculatory blood flow under the probe. However, because the area detected by a single probe is very small, it is known that SkBF reading may vary significantly if the position of the probe is moved slightly. The possible low reliability after replacing the probe limits the application of this measurement in some experiments (e.g. prior and after outdoor exercise). In this study, we tested the hypothesis that using multiple laser Doppler probes could increase the reliability of the measurements. SkBF, local skin temperature (Tsk) and blood pressure were measured with 3 repeated trials in 11 subjects (6 M, 5 F, 42 ± 5 yrs) in a temperature controlled room. Seven laser Doppler probes were placed in a custom‐made holder (round shape, diameter 45 mm). Trial 1: after the probe holder was placed on a forearm, the position was marked. After ~5 min rest, SkBF and Tsk (under the holder) were recorded for 3 min. Then, the probe holder was removed from the forearm and placed on the side calf of a leg to measure leg SkBF. After dis‐instrumentation, subjects were released from the testing table for 10–15 min. Trial 2 and 3: the probe holder was carefully replaced as close as possible on the same positions according to the markers on the skin. The measurements on forearm and then leg as well as the intervals between the trials were repeated. In this Test‐Retest Reliability study, two‐way mixed‐effects models with absolute agreement were used to compute the intraclass correlation coefficient (ICC). There was no significant difference in blood pressure and Tsk between the trials. With the measurements from each single probe, the lowest ICCs were 0.68 (95% Confidence Interval: 0.35, 0.89) for SkBF and 0.76 (0.48, 0.92) for cutaneous vascular conductance (CVC) at leg. With the averaged values from 7 probes, the ICCs were 0.86 (0.62, 0.96) for SkBF and 0.91 (0.74, 0.97) for CVC at leg, and 0.95 (0.87, 0.99) for SkBF and 0.96 (0.88, 0.99) for CVC at forearm. Moreover, with the averaged values from 4 contiguous probes, the ICCs were greater than 0.84. These data suggest that SkBF measurement with multiple laser Doppler probes in a custom‐made holder has high reliability after replacing the probes on the same subjects.Support or Funding InformationSupported by NIH MPI R01 HL141198 (Li and Cui) and UL1 TR002014 (Sinoway)

Pseudo-steady state inflow performance relationship of reservoirs undergoing multiphase flow and different wellbore conditions

This paper introduces an integrated approach for the inflow performance relationship of reservoirs that undergo multiphase flow conditions and drained by vertical wells with different wellbore conditions. The main objective is eliminating uncertainties that govern predicting reservoir performance by assuming single phase flow in the porous media. The proposed approach includes developing several models for multiphase flow conditions using PVT data and relative permeability curves. These models are assembled with the inflow performance relationship to substantially approaching the realistic reservoir pressure/flow rate trend with time.Three tasks are conducted in this study. The first is developing three models for the three reservoir fluid compressibility functions [f(Co)], [f(Cg)], and [f(w)] that consider the changes in comperssibilities with reservoir pressure. These functions are dependent on reservoir fluids properties that are in turn functions of reservoir pressure. While the second involves developing five models of reservoir fluid mobilities using relative permeability curves and the three functions of reservoir fluid comperssibilities. In this task the change in reservoir fluid saturations and the three saturations are calculated and used to calculate relative permeabilities at different reservoir pressures. Multiphase flow reservoir pressure function [f(P)mp] is estimated in third task and used to predict the inflow performance relationships for different wellbore inner boundary conditions i.e. constant Sandface flow rate and constant wellbore pressure. The models in the three tasks are obtained by multi-regression analysis of PVT data and relative permeability curves.The outcomes of this study are: 1) Developing models for reservoir fluid motilities and comperssibilities using PVT data and relative permeabilities curves by multi-regression analysis. 2) Considering the impact of multiphase flow in the porous media by generating multiphase flow pressure function [f(P)mp]. 3) Predicting inflow performance relationships for multiphase flow for different wellbore inner boundary conditions. The study has pointed out: 1) Productivity index of multiphase flow is less than the index for single phase flow. 2) There are no significant differences in the inflow performance relationships of single and multiphase flow for the two inner wellbore boundary conditions, however, constant Sandface flow rate may have better inflow performance relationship than constant wellbore pressure. 3) Most of the models generated by multi-regression analysis exhibits high accuracy (high R-squared value). 4) The proposed models may not have similar trendlines for different reservoirs.

Effect of Combination of Low-Frequency Sonophoresis or Electroporation with Iontophoresis on the Mannitol Flux or Electroosmosis through Excised Skin.

In vitro permeation studies of mannitol were conducted across excised hairless mouse skin to determine and compare the enhancing effect of electroporation (EP) or sonophoresis (SP) combined with iontophoresis (IP) on the electroosmotic flow, and to analyze the enhancement mechanism of these combined methods. Mannitol flux was utilized as an index for the electroosmotic flow due to its low molecular weight and no electrorepulsion effect. The combination of SP and IP (SP/IP) resulted in an apparent increase of electroosmotic flow (no effect was sometimes observed by SP/IP), while that of EP and IP (EP/IP) had no synergistic enhancing effect on the electroosmosis. Next, the combined effect of tape-stripping (TS) and IP (TS/IP) was examined in a similar manner to clarify the difference between the SP/IP and EP/IP effects on electroosmosis. When the TS number increased from 0 to 3, the electroosmotic flow increased with the TS number. However, no further increase was observed when the TS number became more than 3, and the flow started to decrease when the TS number became 5. The electric charge of the skin surface was then measured after SP or TS application. When SP was applied, the skin surface charge became much more negative and the electroosmotic flow by SP/IP was markedly increased. Thus, an increase in the electroosmotic flow across the skin during IP application can be obtained not by EP and TS, but by SP. The combined use of SP and IP is a promising means for the enhanced skin delivery of non-electrolyte drugs.

Hierarchical flow of sensory information in rat somatosensory cortex

Through intracortical processing, sensory stimuli are encoded initially according to elemental features and finally by the action to be taken as a result of the stimulus. The transformation between cortical regions is still not understood although it is known that the participation of primary somatosensory cortex (S1) and secondary somatosensory cortex (S2) differs according to behavioral task [1]. To investigate the sensory information flow between S1 and S2, we recorded from both areas as rats identified textured plates through whisker palpation [2]. Neurons in S2 typically fired with a longer latency to whisker contact, consistent with sequential processing. We used linear discriminant analysis of firing rates of populations of simultaneously recorded neurons [3] in S1 and S2 to compare how they encoded the stimulus. Populations in both regions reliably encoded the stimuli, but the discriminability afforded by neuronal populations in S2 reached a peak 50 ms later than that of S1 populations, also consistent with sequential processing. Different rats were trained with different combinations of texture/reward associations from a set of three textures and two reward locations (left and right). This made it possible to compare the decoding of texture and the decoding of the choice of the animal (left turn versus right), both in correct and incorrect trials. S1 populations carried more information about texture while S2 populations carried more information about choice. Using linear classifiers based on the texture and turn direction classes, we compared the trial-by-trial relationship of the stimulus representation in the two regions to the animal’s choice. When neuronal populations in both regions correctly encoded the stimulus, the rat made the correct choice with 85% probability. When neuronal populations in both regions incorrectly encoded the stimulus, the rat made the correct choice with just 30% probability. When S1 and S2 had disparate representations of the stimulus, the choice of the rat was more than twice as likely to be consistent with the output of S2 than with S1. Thus, neuronal activity in S2 appeared to have a more direct connection to the rat’s decision. The above findings suggest a causal flow of signals from S1 to S2; to test this idea, we computed the directed information [4] between single S1 and S2 units as well as between the S1 and S2 population vectors. We found a significantly higher causality index for the texture information flow from S1 to S2 as the rat palpated the texture, while the sign and value of the causality changed during the decision period when the rat already made its decision. Finally, using a linear feedforward neural network trained with S1 or S2 inputs and outputs, and tested with S1 or S2 inputs and outputs, we found that the feedforward network with S1 input and S2 output had significantly higher performance with respect to the reverse directionality of the input and output. All these findings suggest a hierarchical flow of information between cortical regions, as sensation is transformed to percept and choice.

Numerical analysis of an averaged model of turbulent transport near a roughness layer

We formulate and numerically analyse the averaged model of dispersion in turbulent canopy flows. The averaging is carried out across the flow, for example over the river depth. To perform the averaging, we use the general approach suggested by Roberts and co-authors in the late 1980s, which is based on centre manifold theory. We derive an evolution partial differential equation for the depth averaged concentration, involving first, second and higher order derivatives with respect to the downstream coordinate. The coefficients of the equation are expressed in terms of parameters characterising the turbulent flow. Preliminary numerical results are demonstrated. In particular, it is shown that the advection and diffusion coefficients coincide with their values obtained earlier for the flow over a smooth bottom in the limit of large depths. References Mercer, G. N. and Roberts, A. J., A centre manifold description of contaminant dispersion in channels with varying flow properties, SIAM J. Appl. Math., 50, 1990, 1547--1565. doi:10.1137/0150091 Roberts, A. J. and Strunin, D. V., Two-zone model of shear dispersion in a channel using centre manifolds, Quarterly J. Mech. Appl. Math., 57, 2004, 363--378. doi:10.1.1.102.854 Macdonald, R. W., Modelling the mean velocity profile in the urban canopy layer, Boundary-Layer Meteorol., 97, 2000, 25--45. doi:10.1023/A:1002785830512 Harman, I. N. and Finnigan, J. J., A simple unified theory for flow in the canopy and roughness sublayer, Boundary-Layer Meteorol., 123, 2007, 339--363. doi:10.1007/s10546-006-9145-6 H. Tennekes and J. L. Lumley. A First Course in Turbulence. MIT Press, Cambridge, MA, 1972. Cionco, R. M, Mathematical model for air flow in a vegetative canopy, J. Appl. Meteorol., 4, 1965, 517--522. doi:10.1175/1520-0450(1965)004<0517:AMMFAF>2.0.CO:2 Cionco, R. M., A wind-profile index for canopy flow, Boundary-Layer Meteorol., 3, 1972, 255--263. doi:10.1007/BF0203923 Barenblatt, G. I., Transfer of a passive additive in a turbulent boundary layer at very large Reynolds numbers, Proc. Nat. Acad. Sci., 100, 2003, 1481--1483. doi:10.1073/pnas.0337426100 Strunin, D. V., Universality of turbulent dispersion in a steady flow in an open channel, Quarterly J. Mech. Appl. Math., 64, 2011, 197--214. doi:10.1093/qjmam/hbr002

ASSESSING HEMODYNAMIC PERFORMANCES OF SMALL DIAMETER HELICAL GRAFTS: TRANSIENT SIMULATION

The present study numerically simulated the physiological pulsatile flow in helical grafts to increase understanding of its flow mechanism which may contribute to the design of better grafts. The wall-indices like time-averaged wall shear stress (WSS) and oscillatory shear index (OSI), joint with a quantitative index for helical flow by means of Lagrangian approach, were introduced as effective instruments to classify the hemodynamic performance of helical grafts. The simulation suggests that the helical geometry created amplified WSS magnitudes as well as elevated velocities near the wall. The calculated oscillatory shear index (OSI) values were never exceeded to 0.07 which is not considered physiologically significant. In addition, the strong secondary flow in helical graft helped the flow mixing between low-momentum fluid closer to the surface and high-momentum fluid at the center which brought the high-momentum fluid to the surface. Furthermore, Helicity analysis revealed that most of the fluid particles experienced counter-clockwise rotation during the whole cardiac cycle which helps to protect the graft wall from damage by reducing the laterally directed forces and keep flow stability. It concluded that a helical graft provides guaranties for the graft wall surface to get smooth and even washing by the blood and eliminates mechanical trauma to blood cells so that atherosclerotic plaques can hardly form in the graft wall.

Unilateral ablation of follicles ≥ 4 mm leads to compensatory follicle response from the contralateral ovary in heifers

In each of two experiments, heifers were assigned to a control group and a unilaterally ablated (UA) group (n = 6/group). In the UA group, follicles ≥ 4 mm in the left ovary were ablated by transvaginal ultrasound-guided technique at Hour 0 (8:00 AM) on the day of ovulation. Follicles in the CL-bearing right ovary remained intact. In Experiment 1, ablations continued until the next ovulation, and new follicles emerged in the right ovary in 9 of 14 (64%) waves. The number of follicles/wave (combined, 6.4 ± 0.4) did not differ between groups. In Experiment 2, follicles were counted at Hours 0, 4, 8, 12, and 24; the resistance index (RI) for blood flow in the ovarian pedicle was determined at Hours 0 and 12; and blood samples were collected every hour from Hours 0 to 12 and at Hour 24. An increase (P < 0.05) in the number of follicles in the follicle-intact ovary began at Hour 4 with complete compensation by Hour 24. Concentrations of FSH did not change between Hours 0 and 24 in the UA group but decreased (P < 0.05) in the controls by Hour 7. At Hour 12, RI to the right ovary approached being lower (P < 0.06) in the UA group than in the control group. Results indicated that unilateral ablation of follicles ≥ 4 mm led to compensatory follicle response in the follicle-intact ovary, and initially circulatory FSH concentrations were maintained and blood flow to the follicle-intact ovary increased.

Optimal anticipative congestion control of flows with time-varying input stream

This paper is concerned with a new type of congestion control method that we call anticipative congestion control, which exploits probabilistic information available at a network node about congestion at other nodes. Motivated by the Internet flows behaving according to the Transmission Control Protocol, we consider a flow with time-varying input stream. We design a Markov decision process model for flow admission control and characterize the Whittle index in a closed form. This index measures the efficiency of flow data transmission at a router. We prove that such an index policy is optimal and that it further implies optimality of threshold policies. We apply the results to obtain an expression of the index for a single-bottleneck flow under several types of fairness criteria.

Rheology, Morphology and Mechanical Property Relationship of Non-Halogen Flame Retarded Glass Fibre Reinforced Polyamide 66

In this study, the rheological behaviour of polyamide 66 (PA 66) composites consisting of flame retardant (FR)—MPP, glass fibre (GF) was characterized with a capillary rheometer at different shear rates. The effect of the shear rate on the viscosity and flow curve was discussed in terms of the power law index for non-Newtonian flow. The effect of the loading level of flame retardant on the rheological properties was studied. The results showed that MPPmodified the interfacial interaction between PA 66 and glass fibre. The PA 66/GF/MPP composite behaviour as shear thinning flow under the experimental conditions was investigated, and the investigation of activation energy showed that the proper processing temperature was 275 °C for PA 66/GF/MPP The morphology of the samples observed by scanning electron microscopy was consistent with the predictions from rheological results. The influence of rheology and morphology on the mechanical properties was also examined. It was found that mechanical strength of the composites was improved within a certain range of contents.

Development and application of a catchment similarity index for subsurface flow

In this study, we develop a similarity parameter to describe shallow subsurface hydrological response of small catchments on the basis of the hillslope‐Péclet number. This new similarity parameter, named the catchment‐Péclet (caPe) number, provides a theoretical framework to compare the relative hydrologic response derived from shallow subsurface flow of small catchments on the basis of geomorphic properties. Using 400,000 synthetically derived catchments to model catchment‐scale characteristic response functions (CRFs), we see good agreement between the synthetic and theoretical relationships relating the caPe number to the first two dimensionless moments of the CRF of small catchments. Working with real‐world data, however, requires the estimation of hydrologic parameters and delineation of hillslopes to apply the caPe number. Allowing for uncertainty in the estimation of hydrologic parameters and in the definition of the extent of the channel network, the caPe number is able to recreate the observed moments of an approximate catchment‐scale CRF for four small catchments ranging in size from 0.025 to 880 ha in two distinct climatic and geologic settings. By using physics to underpin the link between landscape and hydrological response, the caPe number creates a functional relationship between hydraulic theory and a catchment's pedogeomorphological structure. While this study is limited to small headwater catchments, it lays the groundwork for a catchment‐scale similarity parameter that could be expanded to larger scales where channel network structure and storage become more important.

Improving patient flow through axiomatic design of hospital emergency departments

In response to crowding in hospital emergency departments, efforts have been made to increase patient flow through fast tracks (FT). However FTs are often underutilized. We find that this is mainly caused by the current practice of assigning patients to FT based only on the emergency severity index. This usage results in a coupling between prioritizing of patients and encouraging fast patient flow. By introducing a new index for patient flow, we could uncouple this design problem and significantly decrease the overall patient waiting time (∼50%) compared to that of the existing use of FT.

Sympathetic cutaneous vasomotor alerting responses (SCVARs) are associated with hippocampal theta rhythm in non-moving conscious rats

Alerting stimuli that cause sympathetic cutaneous vasomotor alerting responses (“SCVARs”) in the thermoregulatory vascular bed of the rabbit ear pinna also induce theta (5–8 Hz) rhythm in the hippocampal EEG, a marker that the animal is engaged with the environment. The present study determines the relation between SCVARs in the thermoregulatory tail artery vascular bed and hippocampal EEG theta rhythm in Sprague-Dawley rats. A Doppler ultrasonic flow probe chronically implanted around the base of the tail artery was used to measure SCVARs. Unipolar electrodes were implanted in the hippocampus (CA1 region) to measure EEG. Six standard non-noxious brief alerting stimuli were administered during continuous recording of tail blood flow and EEG. The SCVAR index was calculated as the percentage fall from pre-alerting blood flow values. After stimuli the SCVAR index for the tail artery blood flow was 84 ± 2% of the pre-alerting control. In contrast, the same stimuli caused little fall in blood flow within the superior mesenteric bed (SCVAR index = 18 ± 2%). The proportion of theta power in the total frequency range (0–20 Hz) increased significantly after alerting stimuli (46 ± 2% vs. 29 ± 1% before stimuli, p < 0.05). Theta proportion began to increase approximately 0.5 s after the stimuli and preceded SCVARs by approximately 1 s. The SCVAR index was correlated with the magnitude of the increment in theta power. Our study demonstrates that alerting responses resulting in selective vasoconstriction of the tail vascular bed are associated with hippocampal theta rhythm in conscious rats.