Measurement Of Plasma Flow Research Articles

Technical note: Measurement of mammary plasma flow in sows by downstream dilution of mammary vein infused -aminohippuric acid.

The objectives of the present study were to design a method to estimate mammary plasma flow (MPF) in lactating sows using downstream dilution of -aminohippuric acid (AH) and to compare these estimates with MPF estimates based on specific AA as internal markers (MPF-AA). A permanent indwelling catheter was surgically implanted in the femoral artery, and another 2 were inserted in the right cranial mammary vein of 8 second- and third-parity sows on d 76 ± 2 SEM of gestation. On the 3rd and 17th days in milk, arterial and venous blood samples were drawn in hourly intervals from 0.5 h before until 6.5 h after feeding. The MPF in the right cranial mammary vein was measured by downstream dilution of infused AH (3.0 mmol/h). Total MPF-AH was calculated assuming that the measured flow constituted the flow from 5 out of 14 suckled glands on the basis of the anatomical structure of the mammary vascular system. Total MPF-AA was estimated on the basis of the output of the specific AA marker in milk and the arteriovenous differences of the marker as free AA in plasma, assuming a direct transfer of AA from plasma to milk protein. Total MPF-AH was 6,860 L/d in early lactation and increased to 8,953 L/d at peak lactation ( = 0.003). In early lactation, MPF-AA estimates were greater or tended to be greater (132% to 175%; < 0.10) than MPF-AH estimates for all internal markers, except Met (119%). Moreover, MPF-AH was correlated with MPF-AA only for MET as an internal marker ( = 0.74; = 0.03) in early lactation. In contrast, MPF-AH and MPF-AA estimates did not differ and were well correlated at peak lactation with the strongest correlation observed when Met ( = 0.84; = 0.009) and Phe + Tyr ( = 0.82; = 0.01) were used as the internal AA markers. Litter gain increased from d 3 to 17 of lactation (2.13 vs. 3.46 g/d; = 0.001) and was correlated with MPF-AH during lactation ( = 0.74; < 0.001), whereas no correlation between litter gain and MPF-AA was observed ( > 0.10). These results suggest that downstream dilution of infused AH and the AA methods are applicable methods to estimate MPF at peak lactation. The reason for the observed discrepancy in early lactation between MPF- AH and MPF-AA is not obvious but might be related to the rapid metabolic changes observed in early lactation. In conclusion, MPF measured by downstream dilution of mammary infused AH was higher at peak compared to early lactation, which the internal AA marker approach failed to show.

Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device.

We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities.

The rebirth of interest in renal tubular function.

The measurement of glomerular filtration rate by the clearance of inulin or creatinine has evolved over the past 50 years into an estimated value based solely on plasma creatinine concentration. We have examined some of the misconceptions and misunderstandings of the classification of renal disease and its course, which have followed this evolution. Furthermore, renal plasma flow and tubular function, which in the past were estimated by the clearance of the exogenous aryl amine, para-aminohippurate, are no longer measured. Over the past decade, studies in experimental animals with reduced nephron mass and in patients with reduced renal function have identified small gut-derived, protein-bound uremic retention solutes ("uremic toxins") that are poorly filtered but are secreted into the lumen by organic anion transporters (OATs) in the proximal renal tubule. These are not effectively removed by conventional hemodialysis or peritoneal dialysis. Residual renal function, urine produced in patients with advanced renal failure or undergoing dialysis treatment, may represent, at least in part, secretion of fluid and uremic toxins, such as indoxyl sulfate, mediated by proximal tubule OATs and might serve as a useful survival function. In light of this new evidence of the physiological role of proximal tubule OATs, we suggest that measurement of renal tubular function and renal plasma flow may be of considerable value in understanding and managing chronic kidney disease. Data obtained in normal subjects indicate that renal plasma flow and renal tubular function might be measured by the clearance of the endogenous aryl amine, hippurate.

Access of energetic particles to Titan׳s exobase: A study of Cassini׳s T9 flyby

We study how the local electromagnetic disturbances introduced by Titan affect the ionization rates of the atmosphere. For this, we model the precipitation of energetic particles, specifically hydrogen and oxygen ions with energies between 1keV and 1MeV, into Titan׳s exobase for the specific magnetospheric configuration of the T9 flyby. For the study, a particle tracing software package is used which consists of an integration of the single particle Lorentz force equation using a 4th order Runge–Kutta numerical method. For the electromagnetic disturbances, the output of the A.I.K.E.F. hybrid code (kinetic ions, fluid electrons) is used, allowing the possibility of analyzing the disturbances and asymmetries in the access of energetic particles originated by their large gyroradii. By combining these methods, 2D maps showing the access of each set of particles were produced. We show that the access of different particles is largely dominated by their gyroradii, with the complexity of the maps increasing with decreasing gyroradius, due to the larger effect that local disturbances introduced by the presence of the moon have in the trajectory of the particles with lower energies. We also show that for particles with gyroradii much larger than the moon׳s radius, simpler descriptions of the electromagnetic environment can reproduce similar results to those obtained when using the full hybrid simulation description, with simple north–south fields being sufficient to reproduce the hybrid code results for O+ ions with energies larger than 10keV but not enough to reproduce those for H+ ions at any of the energies covered in the present study. Finally, by combining the maps created with upstream plasma flow measurements by the MIMI/CHEMS instrument, we are able to estimate normalized fluxes arriving at different selected positions of the moon׳s exobase. We then use these fluxes to calculate energy deposition and non-dissociative N2 ionization rates for precipitating O+ and H+ ions and find differences in the ion production rates of up to almost 80% at the selected positions. All these results combined show that the electromagnetic field disturbances present in the vicinity of Titan significantly affect the contribution of energetic ions to local ionization profiles.

Multidirectional plasma flow measurement by Gundestrup Probe in scrape-off layer of ADITYA tokamak

Multidirectional plasma flow measurements by using Gundestrup Probe in the scrape-off layer of ADITYA tokamak are presented. The ADITYA Gundestrup Probe-head consists of eight plates arranged around the ceramic rod and three pins normal to side plates. Plates are used to measure both parallel and perpendicular flows simultaneously and pins are used to measure plasma density and floating potential. A comparison of direct perpendicular flow measurement and by two other plates of Gundestrup Probe is presented. Possible causes of perpendicular flows are identified and compared with the measured flows. It is observed that the mechanism of the parallel flow and the perpendicular flow is different only at high parallel Mach number. A puff of the working gas is used to study its effect on the perpendicular flows and its reversal with the gas puff is observed.

The influence of VTP-27999 on renal and hormonal responses

Blockade of Renin-Angiotensin-System (RAS), using either angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, halts the progression of chronic kidney disease (CKD). In addition, measurements of Renal Plasma Flow (RPF), as a marker of renal vascular function, and the renal hormonal profile guide our understanding of RAS blockades’ effects. Small mechanistic studies showed encouraging results when Aliskiren, the first approved renin inhibitor, was used; however, its clinical application in CKD was unfavorable in a large clinical trial. We tested the impact of a novel renin inhibitor (VTP-27999) on the kidneys in a single-center, double-blinded study. VTP-27999 (at 4 doses 75, 150, 300 and 600 mg) was compared to either placebo or aliskiren at 300 mg dosing in salt restricted normal volunteers. To determine the impact of the interventions, we measured hourly the change of RPF from baseline using para-aminohippurate infusion along with the change of plasma levels of renin, prorenin, trapping plasma renin activity (PRA) and Angiotensin II (Ang II) after 5 hours from administration. In 6 groups of 9 to 12 subjects, the observed RPF response to VTP22799 administration was dose-dependent and was significantly higher than placebo (Fig1). The respective changes in RPF ( SEM), were as follows: Placebo 5.7% 14.3%, aliskiren 18.1% 17%, VTP-27999 75 mg 8.1% 10.2%, VTP-27999 150 mg 16% 9.5%, 300 mg 22.8% 13.8%, and 600 mg 26.8% 13.2%. In addition, administration of VTP-27999 reduced both PRA and Ang II and increased renin and prorenin levels significantly (p <0.05 for all VTP-27999 dosing higher than 75mg) (Table1). Both renal and hormonal responses were higher in the VTP27999 group at 600 mg dosing than those in the aliskiren’s. The favorable renal function and hormonal responses to VTP-27999 exceeded placebo at all doses and aliskiren at maximum dose. VTP27999 may offer a sufficient RAS blockade and it might be of therapeutic application in CKD.

Novel Design of Multi-Purpose Probe for the Measurement of Plasma Density Gradient, Flow and Transport

We have designed, constructed and installed a multi-purpose probe (MPP) for the measurements of plasma density gradient, flow and turbulent transport in edge plasma of IR-T1 tokamak. Moreover, the effects of radial density gradient and parallel flow on turbulent transport have been investigated. The radial gradient density and the parallel flow variation were measured by the electrical part of MPP. The probability distribution function and the expected value between turbulence, density and parallel flow have been computed.

Initial Evaluation of (99m)Tc(CO)3(ASMA) as a Renal Tracer in Healthy Human Volunteers.

Preclinical studies in rats showed that two of (99m)Tc(CO)3(ASMA) isomers (rac- and L-ASMA) had pharmacokinetic properties equivalent to that of (131)I-OIH, the radiopharmaceutical standard for the measurement of effective renal plasma flow. The aim of this study was to evaluate the pharmacokinetics of (99m)Tc(CO)3(ASMA) isomers in healthy human subjects. Three ASMA ligands (rac-, L- and D-ASMA) were labeled with (99m)Tc(CO)3 using an IsoLink kit (Covidien), and each formed (99m)Tc(CO)3(ASMA) tracer was co-injected with (131)I-OIH into healthy human subjects followed by sequential imaging, plasma clearance measurements and timed urine collection. Plasma protein binding, red cell uptake and percent injected dose in the urine were determined. Urine from each group of volunteers was analyzed for metabolites by HPLC. Image quality was excellent with all three agents. Each (99m)Tc(CO)3(ASMA) preparation was excreted unchanged in the urine. The plasma clearance ratio ((99m)Tc(CO)3(ASMA)/(131)I-OIH) was 81 ± 3% for D-ASMA compared to only 20 ± 4% for L-ASMA and 37 ± 7% for rac-ASMA; the 81% clearance ratio for D-ASMA isomer is still ∼ 30% higher than the (99m)Tc-MAG3/(131)I-OIH clearance ratio (∼50-60%). Red cell uptake was similar for all three tracers (6-9%), and all tracers had a relatively rapid renal excretion; at 3h, the (99m)Tc(CO)3(ASMA)/(131)I-OIH urine ratio was 100 ± 3% for D-ASMA, 80 ± 2% for L-ASMA and 88 ± 1% for rac-ASMA. The renal excretion characteristics of (99m)Tc(CO)3(D-ASMA) in humans are superior to those of the other two (99m)Tc(CO)3(ASMA) isomers studied, but are still inferior to (131)I-OIH, even though there was no difference in the clearance of two of (99m)Tc(CO)3(ASMA) isomers and (131)I-OIH in rats. The work described here demonstrates the sensitivity in in vivo biological behavior of (99m)Tc(CO)3(ASMA) isomers to their subtle structural differences.

The effect of angiotensin converting enzyme inhibition on effective renal plasma flow in patients with diffuse renal parenchymal diseases and hypertension

Angiotensin converting enzyme inhibitors are commonly used to treat various hypertensive conditions and in addition to lowering blood pressure these drugs affect the local renal hemodynamic status, thereby influencing the glomerular filtration rate and effective renal plasma flow. The study was aimed at determining whether angiotensin converting enzyme inhibitors can produce significant changes in effective renal plasma flow in patients with parenchymal renal disease and to assess whether the changes depend on the pre-existing functional status of the kidney. The study included 80 subjects, 40 subjects with hypertension associated with diffuse renal parenchymal disease and 40 subjects with essential hypertension. All study subjects underwent the baseline effective renal plasma flow measurement and the repeated effective renal plasma flow measurement after administration of captopril. Effective renal plasma flow was determined by 131 I-hippuran clearance in blood samples taken at 20 and 30 minutes. Angiotensin converting enzyme inhibitors caused significant effective renal plasma flow changes in 55% of subjects with diffuse renal parenchymal disease and in 75% of subjects with essential hypertension. The effective renal plasma flow changes were more significant in subjects with preserved renal function (normal baseline effective renal plasma flow) compared to subjects with reduced baseline effective renal plasma flow. The application of angiotensin converting enzyme inhibitors in patients with diffuse renal parenchymal disease and in individuals with essential hypertension may result in significant hemodynamic changes in the kidney, accompanied by changes in effective renal plasma flow. The extent of the changes caused by angiotensin converting enzyme inhibitors depends on the preexisting functional status of the kidney.

Al18F-NODA-butyric acid: Biological evaluation of a new PET renal radiotracer

Renal scintigraphy is an important imaging modality for the diagnosis and management of a variety of renal diseases including obstruction and renovascular hypertension as well as the evaluation of absolute and relative kidney function. The goal of this work was to evaluate Al(18)F-NODA-butyric acid (Al(18)F-1) as a potential PET tracer to image the kidneys and monitor renal function by comparing its pharmacokinetic properties with those of (131)I-o-iodohippurate ((131)I-OIH), the radioactive standard for the measurement of effective renal plasma flow. Al(18)F-1 was prepared in aqueous conditions using a one-pot Al(18)F-radiofluorination method and its radiochemical purity was determined by HPLC. Biodistribution studies, using (131)I-OIH as an internal control, were performed in normal rats and in rats with renal pedicle ligation. In vitro stability and metabolism of Al(18)F-1 were analyzed by HPLC. Dynamic microPET/CT studies were conducted in normal rats. Al(18)F-1 showed excellent stability in vitro and in vivo. Biodistribution studies in normal rats and in rats with simulated renal failure confirmed that Al(18)F-1 was exclusively cleared through the renal-urinary pathway and that the hepatic/gastrointestinal activity was less for Al(18)F-1 than for (131)I-OIH both at 10 and 60 min. Dynamic PET showed a rapid transit of Al(18)F-1 through the kidneys into the bladder. These results suggest that the easily labeled Al(18)F-based compounds provide a highly promising approach for the development of a PET renal radiotracer that combines superior imaging qualities with a reliable measure of effective renal plasma flow.

Simultaneous ion temperature and flow measurements using a retarding field analyzer in the HL-2A tokamak

A retarding field analyzer (RFA) was designed and built for use on the HL-2A tokamak to simultaneously measure the ion temperature and plasma flow velocities in the scrape-off layer via a reciprocating probe drive. The probe was built with many off-the-shelf components, making it even more attractive as a diagnostic tool. The probe consisted of two back-to-back RFA analyzers aligned along the toroidal magnetic field lines to measure the downstream and upstream ion temperatures. The true ion temperature was obtained by averaging the two temperatures. RFA measurements on HL-2A have consistently reported ion temperatures higher than electron temperature with ion-to-electron temperature ratios in the range 1–3. The entrance slit plates of the RFA were used as Mach probes for plasma flow measurements, a first among published RFA experiments.

A rotating directional probe for the measurements of fast ion losses and plasma rotation at Tokamak Experiment for Technology Oriented Research

This work discusses a new directional probe designed for measurements of fast ion losses and the plasma rotation with a high angular resolution in magnetically confined plasmas. Directional and especially Mach probes are commonly used diagnostics for plasma flow measurements, and their applicability for the fast ion losses detection has been demonstrated. A limitation of static Mach probes is their low angular resolution. At the Tokamak Experiment for Technology Oriented Research, the angular resolution is strongly restricted by the finite number of available measurement channels. In a dynamic plasma, where instabilities can lead to local changes of the field line pitch-angle, plasma flow, or fast ion losses, a low angular resolution makes a precise data analysis difficult and reduces the quality of the measured data. The new probe design, the rotating directional probe, combines the features of early directional probes and Mach probes. It consists of two radially aligned arrays of nine Langmuir probe pins with each array facing opposite directions. During the measurement the probe head rotates along its axis to measure the ion saturation current from all directions. As a result, the rotating directional probe simultaneously provides an angular dependent plasma flow and fast ion losses measurement at different radial positions. Based on the angular dependent data, a precise determination of the current density is made. In addition, the simultaneous measurement of the ion saturation current at different radial positions allows for resolving radially varying field line pitch-angles and identifying the radial dynamic of processes like fast ion losses.

ULF waves in the outer magnetosphere: Geotail observation 1 transverse waves

A survey of ULF waves in the Pc 5 frequency range during the six year period (1995–2000) has been made for the field line resonance waves in the outer magnetosphere, using plasma flow and magnetic field measurements with the Geotail spacecraft. On the morning side a series of wave trains often appears during several hours. In contrast such a series of wave trains with a long duration is rarely observed in the afternoon to evening sector. Most of waves in the afternoon sector are isolated, of which duration is approximately one hour. The existence of a set of preferential frequencies and the pronounced dawn-dusk asymmetry of wave occurrence and wave features, which were found in ground-based and ionospheric measurements of geomagnetic ULF pulsations, were statistically confirmed. It is also noted that the background plasma flow is sunward in the evening sector without exception. Transverse waves are generally observed in the condition of plasma β below 1.5. High β cases are mostly associated with events on the dusk side. As for the relation to solar wind conditions, Pc 5 waves tend to occur under the condition of more radial than the average IMF spiral angle, or of low cone angle. Key words: Pc 5 waves, dawn-dusk asymmetry of occurrence, radial IMF.

Acute kidney injury following orthopedic trauma in obese Zucker rats

An increased incidence of multiple organ failure occurs following trauma in obesity, but the extent and mechanism of exacerbated damage to specific organs is not understood. The kidney, in particular, is susceptible to organ failure. We hypothesized that there would be impairment in renal function following trauma in obesity. Lean (LZ) and obese (OZ) Zucker rats (11–13 wk, n=6 per group) were used. Orthopedic trauma was mimicked with bilateral hind limb soft tissue injury, followed by an injection of crushed bone components to the area. Twenty‐four hours after trauma, glomerular filtration rate (GFR), renal plasma flow (RPF), blood pressure (BP), and urine albumin measurements were taken. RPF was similar in all groups. LZ and OZ exhibited similar basal BP (122 ± 3 vs. 125 ± 5 mmHg, respectively) and GFR (1.51 ± .15 vs. 1.70 ± .13 ml/min/g). Trauma resulted in a significantly decreased BP (108 ± 3 mmHg) and GFR (0.89 ± .07 ml/min/g) in OZ with no changes in LZ (115 ± 3 mmHg, 1.40 ± .20 ml/min/g). As compared to pre‐trauma values, urine albumin excretion was significantly increased in the twenty hours following trauma in OZ (.63 ± .30 vs. 1.60 ± .51 mg), but not in LZ (.27 ± .05 vs. .51 ± .12 mg). These results show that in our model of orthopedic trauma, acute kidney injury occurs in obese but not in lean rats. This model will allow us to elucidate the mechanisms of trauma‐induced renal damage in obesity.Supported by NIH HL‐51971, HL‐89581, AHA‐12SDG12050525

99mTc(CO)3(NTA) and 131I-OIH: Comparable Plasma Clearances in Patients with Chronic Kidney Disease

The pharmacokinetics of the tricarbonyl core radiopharmaceutical (99m)Tc(CO)3-nitrilotriacetic acid ((99m)Tc(CO)3(NTA)) in rats and subjects with normal renal function are comparable to those of (131)I-o-iodohippuran ((131)I-OIH), the radiopharmaceutical gold standard for the measurement of effective renal plasma flow. Our objective was to compare the pharmacokinetics of these 2 tracers in subjects with renal failure. (99m)Tc(CO)3(NTA) was prepared with commercially available NTA and a commercially available labeling kit and isolated by reversed-phase high-performance liquid chromatography. Approximately 74 MBq (2.0 mCi) of (99m)Tc(CO)3(NTA) were coinjected with approximately 11.1 MBq (300 μCi) of (131)I-OIH in 8 subjects with stage 3-4 renal failure; simultaneous images were obtained for 24 min, followed by an anterior image over the gallbladder and abdomen. Plasma clearances were determined from 10 blood samples obtained 3-180 min after injection using the single-injection, 2-compartment model. Plasma protein binding, red cell uptake, and percentage injected dose in the urine at 30 and 180 min were determined. There was no difference in the plasma clearances of (99m)Tc(CO)3(NTA) and (131)I-OIH (177 ± 63 vs. 171 ± 66 mL/min/1.73 m(2), respectively) (P = 0.41). The plasma protein binding and red cell uptake of (99m)Tc(CO)3(NTA) were 35% ± 7% and 6% ± 3%, respectively; both values were significantly lower than the plasma protein binding (71% ± 5%) and red cell uptake (16% ± 2%) of (131)I-OIH (P < 0.001). There was no significant difference in the percentage injected dose in the urine at 30 min (P = 0.24) and at 3 h (P = 0.82); for comparison, the percentage dose in the urine at 3 h was 77% ± 9% for (99m)Tc(CO)3(NTA) and 78% ± 11% for (131)I-OIH. Image quality with (99m)Tc(CO)3(NTA) was excellent and no activity was identified in the gallbladder or intestine. Results in patients with renal failure show the clearance and rate of urine excretion of (99m)Tc(CO)3(NTA) to be equivalent to that of (131)I-OIH.

Simultaneous determination of renal plasma flow and glomerular filtration rate in conscious mice using dual bolus injection

IntroductionThe present report describes and evaluates a simple protocol for serial measurements of glomerular filtration rate (GFR) and renal plasma flow (RPF) in conscious mice. MethodsIn conscious mice, a bolus of [3H]methoxy-inulin and [14C]para-amino-hippuric (PAH) was injected in the tail vein whereupon eight blood samples were taken during the following 75min. Plasma concentrations were determined by liquid scintillation and clearances of the injected markers were calculated by non-compartmental pharmacokinetic data analysis of the plasma disappearance curves. In anaesthetized mice, the renal extraction ratio of PAH was determined by infusion of PAH and subsequent analysis of blood taken from the carotid artery and the renal vein. The acquired value (0.70±0.02) was used for all subsequent calculations of RPF. To evaluate the protocol, a crossover study was performed where either the vehicle or the angiotensin II AT1 receptor antagonist candesartan was given prior to the clearance measurements. ResultsBaseline values of GFR and RPF were in line with those earlier reported in mice. Administration of candesartan increased RPF and reduced the filtration fraction, whereas GFR was unaltered. These changes are supported by earlier findings and demonstrate that GFR and RPF can be determined independently. Furthermore, modelling experiments demonstrated that acceptable results are obtained even if the number of blood samples is reduced to four which is a way to further simplify the procedure. DiscussionThe method provides an effective way for repeated measurements of GFR and RPF in mice without potentially confounding effects of anaesthesia.

Plasma flows in scrape-off layer of Aditya tokamak

The magnetized Mach probe is used to make measurement of plasma flows in the scrape-off layer of the Aditya tokamak [R. Jha et al., Plasma Phys. Controlled Fusion 51, 095010 (2009)]. This probe is further used to measure dependencies of Mach number on local plasma densities and radial distances of the probe in the scrape-off layer. The measured Mach number has contributions from E×B drift, Pfrisch-Schlüter, and transport driven flows. We have determined that the toroidal flow is towards the ion side of the limiter and the poloidal flow direction is towards the contact of the last closed flux surface with the limiter.

Differences in regional bone metabolism at the spine and hip: a quantitative study using 18F-fluoride positron emission tomography

This study showed that regional bone blood flow and (18)F-fluoride bone plasma clearance measured by positron emission tomography are three times lower at the hip than the lumbar spine. Measurements of effective bone plasma flow (K (1)), bone plasma clearance (K ( i )) and standardised uptake values (SUV) using (18)F-fluoride positron emission tomography ((18)F-PET) provide a useful means of studying regional bone metabolism at different sites in the skeleton. This study compares the regional (18)F-fluoride kinetics and SUV at the hip and lumbar spine (LS). Twelve healthy postmenopausal women with no history of metabolic bone disease apart from two with untreated osteoporosis were recruited. Each subject underwent 60-min dynamic (18)F-PET scans at the LS and proximal femur two weeks apart. K (1), K ( i ) and SUV were measured at the LS (mean of L(1)-L(4)), femoral neck (FN), total hip (TH) and femoral shaft (FS). Differences between sites were assessed using the nonparametric Kruskal-Wallis test with a Bonferroni correction for multiple comparisons. Values of K (1), K ( i ) and SUV at the FN, TH and FS were three times lower than at the LS (p = 0.003). Amongst the proximal femur sites, K ( i ) and SUV were lower at the FS compared with the FN and TH, and SUV was lower at the TH compared with the FN (all p < 0.05). The volume of distribution was lower at the TH and FS compared with the LS (p < 0.05). The lower values of K (1), K ( i ) and SUV at the hip suggest that lower bone blood flow in the proximal femur is an important factor explaining the principal reason for the differences in bone fluoride kinetics between the LS and hip sites.

Effect of neutral pressure on the He plasma flow measurement in a linear device

Axial and azimuthal flow velocities have been measured in a linear plasma device called NAGDIS-II (NAGoya DIvertor Simulator-II), along with plasma density and electron temperature, using a vector Mach probe composed of two Mach probes, one of which is for the axial flow, and the other is for the azimuthal flow. To study the effect of neutral pressure on the deduction of the Mach numbers, the ratio of upstream to downstream currents are measured by changing the neutral pressure for the deduction of flow velocities. Helium plasma was generated with pressure of 2–35 mTorr. Since the ion gyro-radius at the magnetic flux of 300 G is larger than the probe size, an unmagnetized collisionless Mach probe theory was used for the deduction of Mach numbers and their variations. In order to check the range of collisionality, plasma density (ne = 1010–1011 cm−3) and electron temperature (Te = 2–9 eV) are measured by a single electric probe using a conventional collisionless probe theory. Variations of Mach number, electron temperature and plasma density with collisionless models are to be compared with those using collisional models for different pressures where ionization and ion-neutral collision are included. Mach numbers by the collisionless model are found to be overestimated by 120% for the maximum difference even in weakly collisional plasmas. A clear flow reversal exists in the axial direction with higher pressure plasma, even in the linear machine. Azimuthal flows are also measured simultaneously along with axial flows, yet they seem to be very small in the present cold ion plasma (Ti/Te << 1).

Coincident multi-point observations of the E- and F-region decametre-scale plasma waves at high latitudes

Presented is an extensive analysis of the E-region backscatter observed at magnetic latitudes 75°–80°N by the PolarDARN component of the Super Dual Auroral Radar Network (SuperDARN). The statistical occurrence characteristics of the short-range echoes reveal significant differences from those of the auroral and sub-auroral SuperDARN radars. In particular, most backscatter is detected in the midnight sector in the closest range gates where the geometric magnetic aspect angles are in excess of 10° where no backscatter is normally expected. One explanation offered is that intense ionisation layers significantly refract the radar waves allowing a regular detection of the backscatter from the nearest range gates. A statistical analysis of the spectral echo types within the PolarDARN dataset showed strong similarities with the auroral SuperDARN radars, despite significant differences in the geometric aspect angle coverage. The low-velocity echoes dominated the datasets, while the high-velocity echoes were observed rather sporadically in the morning sector. The location of the PolarDARN radars relative to the more-equatorward SuperDARN radars facilitates the use of a new experimental setup that has coincident and simultaneous HF radar coverage of the E and F regions on the same magnetic field lines. Using this configuration, the SuperDARN plasma flow measurements are employed to investigate the E-region phase velocity dependence on the electric field strength and the flow angle at multiple locations. By employing elevation angle estimates, a marked decrease in the normalised phase velocity with decreasing altitude is observed, which provides direct support to the previously suggested collisional depression of the irregularity phase velocity. It is also shown that the normalised phase velocity is smaller for higher electric fields, which is interpreted as being due to a change in the contribution of the convective effects to the plasma wave growth at decametre scales.