Increased Plasma Beta Research Articles

Dependence of the polytropic behaviour of solar wind protons on temperature anisotropy and plasma beta near L1

A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature, while the value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom of that specific process. In this paper we investigate in depth the relationship between the proton effective polytropic index gamma in the solar wind, the proton anisotropy alpha , and plasma beta , while---for the first time to our knowledge to such an extent---we further investigate the dependence of the partial (with respect to the magnetic field) polytropic index to both the above-mentioned plasma parameters. To this end we use the entire Wind dataset spanning the 1995 to 2023 time period to derive the distributions of the polytropic index in the near-Earth space (L1). Our results indicate that the proton gamma increases with increasing proton anisotropy and decreases with increasing plasma beta . Finally, we show that even though the average (over long time periods) total and partial proton polytropic index values are very close, these values correspond to isotropic plasma alone, with a further balance between the thermal and magnetic pressure.On the contrary, for shorter time periods and/or specific solar wind structures, where the proton anisotropy and plasma beta exhibit deviations from these average values, the partial proton polytropic index exhibits significant variation that is dependent on the anisotropy and on plasma beta .

OPTEMIST: A neutral beam for measuring quasi-omnigenity in Wendelstein 7-X

A new neutral beamline (OPTEMIST) uniquely capable of exploring the predicted improvement of fast ion confinement in Wendelstein 7-X (W7-X), which comes with increasing plasma beta, is proposed. As the plasma beta increases in the W7-X device, the high mirror magnetic configuration has drift orbits that begin to close, enhancing the confinement of the deeply trapped particles. The existing neutral beam system is found to produce particle populations that do not adequately probe the deeply trapped orbits. Fast tritons generated by thermal deuterium–deuterium fusion reactions are found to probe the necessary conditions for demonstrating this effect. However, it is found that diagnostically measuring this effect will be difficult. A scoping study of a neutral beamline that directly populates the trapped orbits is performed. It is found that a monoenergetic population of 120 kV injected protons provides the largest confinement enhancement in the fast ion population as the plasma beta is increased. The necessity to raise plasma density to increase plasma beta results in blinding of spectroscopic beam measurements by bremsstrahlung. An array of novel fast ion loss detectors that would adequately assess the confinement of these particles is proposed.

Gyro orbit simulations of neutral beam injection in Wendelstein 7-X

Simulations exploring neutral beam operation in Wendelstein 7-X (W7-X) at reduced magnetic field are performed using a newly implemented gyro orbit model in the BEAMS3D code. Operation at field strengths below the nominal 2.5 T are seen as a path to explore both high beta plasmas and as a means to access magnetic configurations not possible at 2.5 T. As the field strength becomes smaller, the gyro radius for 55 keV fast protons grows from at 2.5 T to at 0.75 T in a device with minor radius bringing into question the applicability of the gyro center approximation. To address this a gyro orbit model was implemented in the BEAMS3D code. Agreement is found between the gyro center and gyro orbit models in a circular cross section tokamak equilibrium at high field. A set of W7-X equilibria are assessed with fixed density and temperature profiles but decreasing magnetic field strength (increasing plasma beta). Neutral beam deposition is found to be mostly unaffected with changes in the core of the plasma associated with the Shafranov-shift. In general good agreement is found between gyro orbit and gyro center simulations at 2.5 T. Both models indicate increasing losses with decreasing magnetic field strength with the gyro orbit losses being higher at all field strengths. Gyro orbit simulations to the first wall of W7-X show a change in loss pattern with decreasing magnetic field strength. A preliminary assessment of losses to fast ion loss detectors are made.

Equilibrium effects on the structure of island divertor and its impact on the divertor heat flux distribution in Wendelstein 7-X

To support the planning of high-performance long-pulse plasma operation for W7-X, the role of equilibrium effects for the structure of island divertor and its profound impacts on the divertor heat flux distribution have been investigated. Finite-beta full-field three-dimensional equilibria for the four most important configurations of W7-X (‘standard’, ‘high-mirror’, ‘high-iota’ and ‘low-iota’) were obtained with the HINT code. Equilibrium calculations show a strong dependence of the edge stochastization on the magnetic configurations. Parameterization to estimate equilibrium effects on edge stochastization and plasma shape was attempted for individual functions. The results indicate that a more stochastic boundary can be attained with increasing plasma beta, except for the low-iota configuration. According to fully diffusive heat-load estimations, it turns out that equilibrium effects are beneficial for spreading the heat flux on the divertor target. The interactions of the beta effects with effects driven by the toroidal plasma current are also analyzed for the standard configuration. Infrared camera measurements confirm the predictions concerning global heat load distributions.

The Role of Parametric Instabilities in Turbulence Generation and Proton Heating: Hybrid Simulations of Parallel-propagating Alfvén Waves

Abstract Large-amplitude Alfvén waves tend to be unstable to parametric instabilities that result in a decay process of the initial wave into different daughter waves depending upon the amplitude of the fluctuations and the plasma beta. The propagation angle with respect to the mean magnetic field of the daughter waves plays an important role in determining the type of decay. In this paper, we revisit this problem by means of multidimensional hybrid simulations. In particular, we study the decay and the subsequent nonlinear evolution of large-amplitude Alfvén waves by investigating the saturation mechanism of the instability and its final nonlinear state reached for different wave amplitudes and plasma beta conditions. As opposed to one-dimensional simulations where the Decay instability is suppressed for increasing plasma beta values, we find that the decay process in multidimensions persists at large values of the plasma beta via the filamentation/magnetosonic decay instabilities. In general, the decay process acts as a trigger both to develop a perpendicular turbulent cascade and to enhance mean field-aligned wave–particle interactions. We find indeed that the saturated state is characterized by a turbulent plasma displaying a field-aligned beam at the Alfvén speed and increased temperatures that we ascribe to the Landau resonance and pitch-angle scattering in phase space.

Voluntary alcohol consumption and plasma beta-endorphin levels in alcohol preferring rats chronically treated with lamotrigine

Several recent studies have indicated that lamotrigine, similarly to other antiepileptic drugs, may be useful in the therapy of alcohol dependence. The rationale for using lamotrigine in the treatment of alcohol addiction is based on its multiple mechanisms of action which include inhibition of voltage-sensitive sodium channels, modulation voltage-gated calcium currents and transient potassium outward current. However, the known mechanism of lamotrigine does not fully explain its efficacy in alcohol addiction therapy. For this reason we have decided to examine the effect of lamotrigine on the opioid system. Our previous studies showed that topiramate and levetiracetam (antiepileptic drugs) as well as the most effective drugs in alcohol addiction therapy i.e. naltrexone and acamprosate, when given repeatedly, all increased plasma beta endorphin (an endogenous opioid peptide) level, despite operating through different pharmacological mechanisms. It is known that low beta-endorphin level is often associated with alcohol addiction and also that alcohol consumption elevates the level of this peptide. This study aims to assess the effect of repeated treatment with lamotrigine on voluntary alcohol intake and beta-endorphin plasma level in alcohol preferring rats (Warsaw high preferring (WHP) rats). We observed a decrease in alcohol consumption in rats treated with lamotrigine. However we didn't observe significant changes in beta-endorphin level during withdrawal of alcohol, which may indicate that the drug does not affect the opioid system. We suppose that lamotrigine may be useful in alcohol dependence therapy and presents a potential area for further study.

A primitive kinetic-fluid model for quasi-parallel propagating magnetohydrodynamic waves

The extension and limitation of the existing one-dimensional kinetic-fluid model (Vlasov-MHD (magnetohydrodynamic) model), which has been used to analyze parametric instabilities of parallel propagating Alfvén waves, are discussed. The inconsistency among the given velocity distribution functions in the past studies is resolved through the systematic derivation of the multi-dimensional Vlasov-MHD model. The linear dispersion analysis of the present model indicates that the collisionless damping of the slow modes is adequately evaluated in low beta plasmas, although the deviation between the present model and the full-Vlasov theory increases with increasing plasma beta and increasing propagation angle. This is because the transit-time damping is not correctly evaluated in the present model. It is also shown that the ponderomotive density fluctuations associated with the envelope-modulated quasi-parallel propagating Alfvén waves derived from the present model is not consistent with those derived from the other models such as the Landau-fluid model, except for low beta plasmas. The result indicates the present model would be useful to understand the linear and nonlinear development of the Alfvénic turbulence in the inner heliosphere, whose condition is relatively low beta, while the existing model and the present model are insufficient to discuss the parametric instabilities of Alfvén waves in high beta plasmas and the obliquely propagating waves.

Effect of an antioxidant-rich multivitamin supplement in cystic fibrosis

Background Despite supplementation with standard multivitamins and pancreatic enzymes, deficiencies of vitamins D and K and antioxidants are common in cystic fibrosis (CF). Methods In this non-randomized, open-label study, AquADEKs® softgels were given daily over 12 weeks to 14 CF subjects (mean age 15 years, range 10–23) without a preceding wash-out period. Both pancreatic sufficient and insufficient subjects were enrolled. Plasma vitamin and antioxidant levels, urine 8-isoprostane levels, anthropometric measures, and pulmonary function were determined at baseline, 6 and 12 weeks. Results Daily supplementation significantly increased plasma beta(β)-carotene, coenzyme Q10, and γ-tocopherol concentrations, decreased proteins induced in vitamin K absence (PIVKA-II) levels, but did not normalize vitamin D and K status in all subjects. Vitamin A levels did not exceed the normal range for any subject during the entire study period. Modest improvements in weight percentile and pulmonary function were observed. Change in plasma β-carotene concentrations weakly correlated with changes in weight and body mass index percentiles. Conclusions In this study, AquADEKs® increased systemic antioxidant levels, while maintaining vitamin A levels in the normal range, and improved but did not completely normalize vitamin D and K status. Increased β-carotene levels were associated with improved growth parameters. These results warrant further clinical evaluation in CF.

Platelet activation in pregnancy-induced hypertension

Background Although excess platelet activation, as indicated by increased plasma beta thromboglobulin (β-TG), has been shown in pregnancy-induced hypertension (PIH), platelet adhesion, platelet morphology and a comparison of platelet and soluble (plasma) levels of the adhesion molecules P-selectin (pPsel and sPsel, respectively) have not been studied. Methods We conducted a cross-sectional study of 35 consecutive women with PIH (age 31±6 years), 31 consecutive women with normotensive pregnancies (age 29±5 years) and 30 normotensive non pregnant women (age 30±5 years). Platelet adhesion was studied in vitro by binding to fibrinogen-coated microwells, platelet morphology [mass and volume by flow cytometry], whole-platelet P-selectin (pPsel) by ELISA of the lysate of 2×10 8 cells, and the plasma markers soluble P-selectin (sP-sel) and β-TG, by ELISA. Results The women with PIH had significantly raised sPsel, pPsel and (as expected) β-TG (all p<0.05), when compared to the normotensive pregnant women and controls. However, in PIH platelet adhesion was similar to that in the normotensive pregnancy, but still higher than the normal controls ( p<0.001). There was no difference among the three groups with respect to platelet mass and volume. pPsel and platelet adhesion correlated with gestational age and with systolic and diastolic blood pressure (all p<0.05). Conclusions Increased platelet activation and adhesion develop during normal pregnancy, with some indices being further altered in PIH.

268. Experimentally induced hypoglycemia: a model to examine the effects of lactation on reproductive function in dairy cows?

The metabolic changes subsequent to lactogenesis have been associated with poor reproduction in high-producing dairy cows.1,2 Periods of hypoglycaemia reflect severe energy deficit and are associated with changes in plasma levels of growth hormone (GH), insulin-like growth hormone-I (IGF-I) and insulin-like growth hormone-II (IGF-II). Somatotropic activity has been shown to influence reproductive functions.3–5 This study evaluated the effects of experimentally induced hypoglycaemia in seven non-lactating cows, over a 7-day period. Phloridizin treatment (8 g/d) resulted in urinary glucose loss (control: 3.5 ± 1.0 g/d and phloridizin: 468 ± 46 g/d) and decline in plasma glucose (control: 60.6 ± 0.6 mg/dL and phloridizin: 71.8 ± 0.4 mg/dL; P &lt; 0.001). Treatment increased plasma beta hydroxybutyrate (BOH), non-esterified fatty acids (NEFA) and IGF-I concentrations (P &lt; 0.001). Plasma insulin and GH concentrations did not differ. During treatment, expression of mRNA for total growth hormone receptor (GHR(tot); P = 0.012) and GHR(1A) (P &lt; 0.001) in liver tissue declined. Luteal and follicle diameters in ovaries recovered after treatment did not differ. Expressions of mRNA for IGF-I (P = 0.052) and interleukin-1β (IL-1β) in corpus luteum and for 3β-hydroxysteroid dehydroxyenase (3β-HSD) within dominant follicles were significantly elevated, while mRNA for GHR(tot), cytochrome P450 cholesterol side chain cleavage enzyme (P450-SCC), and steroidogenic acute regulatory protein (StAR) tended to increase (P &lt; 0.1) with treatment. The treatment resulted in changes similar to those of nutritional stress or the initiation of lactogenesis. Phloridizin-induced hypoglycaemia may be a model to investigate mechanisms linking glucose metabolism, and the somatotropic axis to reproductive function. The advantages of such a model, is that it allows for strict control of the level of hypoglycaemia. The use of non-lactating cows also removes the feedback mechanisms that modulate mammary gland requirements, and therefore will minimize the between cow variance when using lactating cows. This work was completed with the help from Dexcel Farms and the Dairy Cattle Fertility team. This study was funded by the New Zealand Foundation for Research, Science and Technology (DRCX 0202). (1)Roberts et al. (1997) Journal of Animal Science 75, 1909–1917.(2)Thatcher et al. (1996) Reproduction, Fertility and Development 8, 203–217.(3)Royal et al. (2000) Animal Science 70, 487–501.(4)Butler (2000) Animal Reproduction Science 60, 449–457.(5)Lucy (2000) Journal of Dairy Science 84, 1635–1647.

Investigation of Platelet Functions in Chronic Myeloproliferative Disorders by Optical and Luminesance Method.

Background: Bleeding and thrombosis are common causes of morbidity and mortality in patients with myeloproliferative disorders (MPD). Qualitative platelet abnormalities are frequently found in these patients and range from platelet hypofunction as demonstrated by defective invitro platelet aggregation, acquired storage pool disease and/or platelet membrane defects, in addition to enhanced platelet aggregation, increased plasma beta thromboglobulin levels or shortened platelet survival. In this study we aimed to perform platelet aggregation studies by optical method (on platelet rich plasma=PRP) and luminesance method (on whole blood) in chronic myeloproliferative disorders.Methods:A total of twenty-five patients with MPD (17 chronic myeloid leukemia, 6 polycythemia vera, 2 essential thrombocytosis) were enrolled. Median age was 54,4 (29–76). Platelet aggregation was measured using the optic and luminesance method. The agonists used were adenosine diphosphate (ADP), arachidonic acid (AA) ristocetin and collagen. Platelets were considered to be hyperactive if at least one result (i.e. aggregation or ATP release with one agonist) was above the reference range, and hypoactive if at least one result (i.e. aggregation or ATP release) was below the reference range. Mixed hypo- and hyperactive platelets were considered present when at least one result (i.e. aggregation or ATP release) was below and above the reference range respectively.Results:Platelet aggregation test results by two methods in myeloproliferative disorders were shown in Table 1. The percent for detection of platelet function abnormality by luminesance method was found to be higher than the optic method and a significant difference was shown between two methods (p<0,05).Conclusion Our findings suggest that;1. Luminesance platelet aggregation study is more valuable than optic platelet aggregation study for invitro assessment of platelet function in patients with MPD. 2. The use of luminesance platelet aggregation study appears useful to select patients for antiplatelet therapy.Platelet aggregation test results in myeloproliferative disorders (n=25)NormalHypofunctionHyperfunctionMixTotal abnormalityLuminesance method1(%4)4(%16)8(%32)11(%44)24(%96)Optic method9(%36)11(%44)2(%8)3(%12)16(%64)

Structuring and support by Alfvén waves around prestellar cores

Observations of molecular clouds show the existence of starless, dense cores, threaded by magnetic fields. Observed line widths indicate these dense condensates to be embedded in a supersonically turbulent environment. Under these conditions, the generation of magnetic waves is inevitable. In this paper, we study the structure and support of a 1D plane-parallel, self-gravitating slab, as a monochromatic, circularly polarized Alfven wave is injected in its central plane. Dimensional analysis shows that the solution must depend on three dimensionless parameters. To study the nonlinear, turbulent evolution of such a slab, we use 1D high resolution numerical simulations. For a parameter range inspired by molecular cloud observations, we find the following. 1) A single source of energy injection is sufficient to force persistent supersonic turbulence over several hydrostatic scale heights. 2) The time averaged spatial extension of the slab is comparable to the extension of the stationary, analytical WKB solution. Deviations, as well as the density substructure of the slab, depend on the wave-length of the injected wave. 3) Energy losses are dominated by loss of Poynting-flux and increase with increasing plasma beta. 4) Good spatial resolution is mandatory, making similar simulations in 3D currently prohibitively expensive.

On the linear and nonlinear resistive tearing‐mode instabilities

The tearing‐mode instabilities of Harris sheet magnetic field configuration are studied based on the numerical simulations of two‐dimensional, resistive, compressible MHD models with isotropic pressure. The linear growth rate and the eigenmode structure are calculated from the linear numerical model for various parameters: magnetic Reynolds number, Rm; the ratio of wavelength to the layer thickness; magnetic By component; and plasma beta, as well as for different equations of state. The linear solutions are then used as initial perturbations of the nonlinear numerical model to allow the full evolution of resistive tearing‐mode instability. The linear calculations show that for the range of Rm = 10–105 the fastest growth rate increases with decreasing Rm and only slightly increases with increasing plasma beta and By but that it is not sensitive to the equation of state. While the nonlinear calculations snow that only for large Rm, where the diffusion time is much larger than the linear growth time, the magnetic island may possibly grow substantially and become saturated. For small Rm the plasmoids either diminish in the late stage or do not have apparent growing; that is, the linear analysis is not meaningful for large resistivity cases. The calculations are compared to the magnetic island structure at Earth's magnetopause reconstructed from the single‐spacecraft data by Hau and Sonnerup [1999].

Evidences for a dopamine-regulated peripheral source of circulating beta-endorphin.

Circulating beta-endorphin (beta EP) and beta-lipotropin (beta LPH) concentrations increase after the administration of acetylcholine or serotonin agonist drugs. In this study we examined the effect of dopamine receptor agonists and/or antagonists on plasma beta EP, beta LPH, cortisol, and PRL levels in normal subjects. Neither direct dopamine (DA) agonist drugs, DA (1 microgram/kg min for 120 min), bromocriptine (2.5 mg po), L-dopa (500 mg po) or an indirect DA agonist, nomifensine (200 mg po), significantly altered plasma beta EP and beta LPH levels. The administration of metoclopramide, a DA antagonist (10 mg iv), significantly increased plasma beta EP, beta LPH, PRL, and cortisol levels. This effect was completely reversed by pretreatment with L-dopa (500 mg po) and only partially antagonized by DA infusion. Domperidone (10 mg iv), a DA antagonist which does not cross the blood brain barrier, increased only plasma beta EP levels, an effect inhibited both by L-dopa and DA. After dexamethasone (2 mg/day for 2 days) domperidone still increased plasma beta EP and PRL levels. The concomitant increase of beta EP, beta LPH, and cortisol after metoclopramide suggests that endogenous DA inhibits the secretion of proopiomelanocortin-related peptides. Moreover, since domperidone increases only beta EP and this effect is not altered by dexamethasone, there may be a corticotropin-releasing hormone-independent source of circulating beta EP in humans, which is inhibited by DA.

Plasma beta-endorphin, free fatty acids and blood lipid changes in type 2 (non-insulin dependent) diabetic patients.

A lipolytic activity for beta-endorphin (beta EP) has been recently suggested both in vitro and in vivo. In our study we evaluated the relationship between beta EP and blood lipid pattern in Type 2 (non-insulin dependent) diabetic patients. Plasma beta EP, together with plasma beta-lipotropin (beta LPH), ACTH, cortisol and plasma insulin (IRI), was measured by RIA after silicic acid plasma extraction and Sephedex G-75 column chromatography. Although reduced beta EP (7.12 +/- 3.8 fmol/ml) and increased beta LPH (9.3 +/- 3.7 fmol/ml) levels were found in diabetic patients, compared to controls (8.53 +/- 3.3 fmol/ml, p less than 0.05 and 8.34 +/- 2.6 fmol/ml, p less than 0.05, respectively), higher plasma beta EP concentrations were demonstrated in hyperlipidemic diabetic patients (10.3 +/- 3.9 fmol/ml) than in patients with normal blood lipid pattern (4.85 +/- 1.45 fmol/ml, p less than 0.001). Several positive correlations between beta EP, plasma free fatty acids (r = 0.75, p less than 0.001), triglycerides (r = 0.84, p less than 0.001) and VLDL (r = 0.80, p less than 0.001) were found in our patients independently of overweight, hypoglycemic treatment, plasma IRI levels and of the degree of metabolic control. A higher prevalence of micro- and macrovascular complications was demonstrated in hyperlipidemic than in normolipidemic patients. Blood lipid disorders might therefore be associated with increased plasma beta EP levels in Type 2 diabetes.

Diurnal rhythm of beta endorphin in normotensive and hypertensive patients: the effect of clonidine.

Diurnal rhythm of plasma beta endorphin was established with the highest level in the morning and the lowest one at midnight in normotensive subjects and also in patients with essential hypertension. Clonidine (300 micrograms daily) significantly increased plasma beta endorphin concentrations only in the hypertensive patients. The significant linear correlation between the increase in plasma beta endorphin concentration and the decrease in blood pressure (both systolic and diastolic) in these patients may point to the role of this endogenous opioid in the antihypertensive action of clonidine.

Plasma beta-thromboglobulin: differentiation between intravascular and extravascular platelet destruction

To elucidate the usefulness of beta-thromboglobulin (beta TG) in the differentiation of the mechanism of thrombocytopenia, plasma beta TG concentration was measured in one patient with amegakaryocytic thrombocytopenia, four patients with autoimmune thrombocytopenia (ATP), two patients with thrombotic thrombocytopenia (TTP), and one patient with thrombocytopenia secondary to disseminated intravascular coagulation (DIC). Plasma beta TG was not measurable in amegakaryocytic thrombocytopenia, was normal in ATP, and was increased in TTP and DIC. These data indicate that in thrombocytopenic patients, increased plasma beta TG concentration may result from intravascular platelet consumption with release of platelet constituents in contrast to extravascular platelet destruction by the macrophage-monocyte system.

Plasma ß-Thromboglobulin: Differentiation Between Intravascular and Extravascular Platelet Destruction

AbstractTo elucidate the usefulness of beta-thromboglobulin (beta TG) in the differentiation of the mechanism of thrombocytopenia, plasma beta TG concentration was measured in one patient with amegakaryocytic thrombocytopenia, four patients with autoimmune thrombocytopenia (ATP), two patients with thrombotic thrombocytopenia (TTP), and one patient with thrombocytopenia secondary to disseminated intravascular coagulation (DIC). Plasma beta TG was not measurable in amegakaryocytic thrombocytopenia, was normal in ATP, and was increased in TTP and DIC. These data indicate that in thrombocytopenic patients, increased plasma beta TG concentration may result from intravascular platelet consumption with release of platelet constituents in contrast to extravascular platelet destruction by the macrophage-monocyte system.

Recent Developments in the Design of Conceptual Fusion Reactors

Since the first round of conceptual fusion reactor designs in 1973 - 1974, there has been considerable progress in design improvement. Two recent tokamak designs of the Wisconsin and Culham groups, with increased plasma beta and wall loading (power density), lead to more compact reactors with easier maintenance. The Reference Theta-Pinch Reactor has undergone considerable upgrading in the design of the first wall insulator and blanket. In addition, a conceptual homopolar energy storage and transfer system has been designed. In the case of the mirror reactor, there are design changes toward improved modular construction and ease of handling, as well as improved direct converters. Conceptual designs of toroidal-multiple-mirror, liner-compression, and reverse-field pinch reactors are also discussed. A design is presented of a toroidal multiple-mirror reactor that combines the advantages of steady-state operation and high-aspect ratio. The liner-compression reactor eliminates a major problem of radiation damage by using a liquid-metal first wall that also serves as a neutron-thermalizing blanket. The reverse-field pinch reactor operates at higher beta, larger current density and larger aspect ratio than a tokamak reactor. These properties allow the possibility of ignition by ohmic heating alone and greater ease of maintenance.