bluuebunny/crossref_metadata_2025 huggingface dataset:
Burnout or Professional Exhaustion Syndrome Among Primary Care Tunisian Doctors
Authors: Oumaya M. , Ghanmi L. , Baccar Y. , Khédira B. , Salah K. Ben , Bouzid R.
Published: March 2009

The Burnout or the professional exhaustion syndrome is common among doctors, especially primary care practitioners. The rates range from 25 to 76% according to specialties.

Aims:

Main objective was to assess the prevalence of burnout in Tunisian primary care practitioners working in public sector in the region of the Cap Bon. Secondary objectives were to determine the risk factors and the consequences associated with this syndrome.

Methods:

transversal study using four scales: Anonymous auto questionnaire elaborated by the medical team, the Maslach Burnout Inventory (MBI), the Beck Depression inventory (BDI) and the state-trait anxiety inventory (STAI). The MBI explores the three dimensions of Burnout: emotional exhaustion, depersonalization and reduced personal accomplishment. In our study, the Burnout was defined by the presence of two or three pathological dimensions.

Results:

113 questionnaires were exploitable (85.6% of the sample). The results of the MBI showed that one third of doctors suffer from Burnout and 7.1% have severe attaints. 35% of the doctors had high score of emotional exhaustion, 21% had high depersonalization and 40% had a low score of personal accomplishment. The Burnout was significantly associated with depression (p < 0.001), suicidality (p=0.023) and anxious temperament (p< 0.001). On the other hand, a continued medical education protected significantly against the Burnout (p=0.003). Professional exhaustion was significantly related to the wish of reconversion (p=0.023) and to relational difficulties with patients and colleagues. The solutions proposed were the increase of the number of doctors and a better education of medical students in general medicine.
Social Conflict after Disaster
Authors: Portnova A.
Published: March 2009

Objective:

Studying the social conflict among inhabitants of small settlements owing to extreme situations.

Methods:

Social-psychological investigation for revealing interpersonal and intergroup (victims and nonvictims) conflicts among in townsfolk of Sydybyl (Yakutia) and Beslan (North Ossetia) after disaster with death of children.

Results:

It was shown that the basic psychological need of persons who loss their relatives during a disaster is a search of guilty of tragedy. In consequence of this, occurs the stratification of society with apportionment of such groups as “victims” and “guilty”. The “victims” additionally mark out the group of “light victims” and accuse them of insufficient efforts to rescue of children of “victims”. It was suggested that the persistent search of guilty represents a form of psychological defense against the unbearable feeling of their own guilt towards died children. The universal (non-conditioned by ethnic or cultural factors) character of described phenomena was emphasized. It was marked that the social conflict (named by author as indigenous) deteriorates the social and economic consequences of disaster.

Conclusions:

The indigenous conflict tends to persistence and passes the certain phases, final of which is characterized by a high level of neurotic diseases in the opulation and migration of an efficient part of the population.
Accounting for Variations in Acculturative Stress: Coping and Appraisal
Authors: Revollo H.W. , Qureshi A.
Published: March 2009

Acculturative stress is increasingly understood to mediate the relationship between immigration and mental health. The bullk of research in this area, however, has not addressed psychological factors that affect the degree to which the migratory process is experienced as stressful nor what sorts of strategies are used to manage stressors related to migration. The appraisal of a situation as stressful is related to the material, social and psychological resources. Coping style can mediate the psychological impact of the stressor. It would appear that the relationship between stress and coping is complex and multifaceted, and not amenable to a simple path analysis. To better understand how the migratory experience is related to mental health requires elucidating the relationship between the objective event, how it is appraised, and the coping response used. A further confounding issue is that the bulk of theorizing and instrumentation in coping and stress research is predicated on a Euro-American paradigm, and thus not necessarily appropriate for use with other cultures. In addition, it would appear that coping style not only mediates the relationship between stress and psychopathology, but is also related to the appraisal process. This paper will provide a critical analysis of conceptual and measurement issues related to stress, appraisal, and coping as applied to the migratory experience. The paper will conclude with an outline a research study currently underway that may provide insight into some of these issues.
The Experience of Contemporary Peacekeepers Healing from Trauma
Authors: Ray S.
Published: March 2009

This research study was an interpretive inquiry into the experience of contemporary peacekeepers healing from trauma. Ten contemporary peacekeepers were interviewed who have sought treatment for trauma resulting from deployments to Somalia, Rwanda, and the former Yugoslavia. A thematic analysis of the text was undertaken in which themes emerged to document and understand the ways in which contemporary peacekeepers suffer while healing from trauma. Narratives from the transcribed interviews were reviewed with the participants and reflective journaling by the researcher provided further clarification of the data to understand the experience. The peacekeepers’ descriptions of the situatedness of their bodies in time, space and relation provided a fresh way into understanding the embodied nature of suffering while healing from trauma. Three overarching themes: the centrality of brotherhood and grieving loss in the military family; the centrality of time and the body in suffering while healing from trauma; and the military response as betrayal and creating trauma from within emerged from the inquiry which will contribute to more effective practice guidelines for the care of contemporary peacekeepers suffering and healing from trauma.
Psychosocial Distress as a Risk Factor for Asthma Mortality
Authors: Razvodovsky Y.
Published: March 2009

Background:

Asthma is a mayor public health issue; its prevalence has increased in recent decades world wide. However, focus on biological risk factors has not fully explained this trend. A mounting body of research evidence suggests that psychosocial distress is likely to be a factor contributing to the development of asthma.

Purpose:

To estimate the effect of psychosocial distress on asthma mortality rate at the aggregate level.

Method:

Trends in age-adjusted, sex-specific suicide (as an integral indicator for psychosocial distress) and asthma mortality rate in Russia from 1956 to 2005 were analyzed employing an ARIMA analysis in order to asses bivariate relationship between the two time series.

Results:

Time series analysis indicates the presence of statistically significant association between the two time series for male. The association between the two time series for female also positive, however, statistically not significant.

Conclusion:

The findings of the present study add to the growing number of studies linking psychosocial distress to asthma expression and mortality. This paper presents new epidemiological evidence that supports psychosomatic concept of asthma.
Elderly People’s Seath Anxiety and Dying Anxiety in Israe: A Comparison Between Before and After the Second Lebanon War
Authors: Pon P.
Published: March 2009

Background:

Due to our fear of extinction or annihilation, there is a great deal of preoccupation with the subject of death, through which we attempt to learn to feel more at ease with the concept, and allowing us to cope with our fear of death.

Method:

The study assumptions seek to emphasize the correlations between:

A.

Demographic characteristics and anxiety of death and dying;

B.

Inner - personality characteristics and death and dying anxiety variable; and

C.

Intrapersonal characteristics and death and dying anxiety.

The connections between all of those variables were examined before and after the second Lebanon war. The study sample comprised 217 participants as the "before" group and, 151 participants as the "after" group. The study's data was collected via face-to-face interviews. All of the "after" group participant were at the "before" group.

Results:

Findings indicate that the war increased the death and dying anxieties especially among those elderly women and those who live within nursing homes. In general elderly people with a high level of self-evaluation and sense of mastery will experience lower levels of death and dying anxieties.

Conclusion:

In spite of age, experience and knowledge, war has a powerful influence on elderly people. The phenomena in which innocent citizens became more and more involved in politics violence must be in front of policy makers.
Steroid and Thyreoid Hormones and Neurotic, Stress-related and Somatoform Disorders
Authors: Ryadovaya L. , Gutkevich E. , Ivanova S.
Published: March 2009

Objective:

Study concentrations of steroid and thyreoid hormones in patients with neurotic, stress-related and somatoform disorders.

Methods:

35 patients with dissociative (conversion) disorders (ISD-10, F44), 29 patients with adjustment disorders (ISD-10, F43.2) and mentally healthy persons (27 persons) were investigated. Immunofermantal analysis for definition of concentration of steroid and thyreoid hormones were carried out.

Results:

We have observed statistically significant increased level of cortizol (p< 0,05) in patients with adjustment disorders (635,04±48,69 nmol/l) in comparison with control and patients with dissociative (conversion) disorders (444,97±24,53 nmol/l and 443,13±23,00 nmol/l accordingly). The statistically significant the lowered maintenance of dehydroepiandrosteronum is characteristic for patients with adjustment disorders in comparison with control and patients of another group (3,9±0,26; 6,35±0,62 and 6,69±0,50 mkmol/l accordingly, p< 0,05). For patients with dissociative (conversion) disorders is characteristic the statistically significant increased level of triiodthyronin (1,71±0,12 nmol/l), in patients with adjustment disorders and mentally healthy persons this metric composed 1,26±0,02 nmol/l and 1,34±0,04 nmol/l accordingly. The level of thyroxin for the persons with dissociative (conversion) disorders differ from values of control and patients with adjustment disorders (23,68±2,07 pkmol/l; 17,64±1,43 pkmol/l and 14,69±0,53 pkmol/l accordingly, p< 0,05).

Conclusion:

For patients with adjustment disorders is characteristic the statistically significant increased level of cortizol and the lowered maintenance of dehydroepiandrosteronum. Dissociative (conversion) disorders are formed in conditions of the raised maintenance thyreoid hormones and the physiological maintenance of steroid hormones.The investigation supported by project of RHSF №06-06-00691а, №07-06-95673и/М and №08-06-00284а.
Genetics of the Hypothalamic-pituitary-adrenal (HPA) Axis - a Systemic Stress Modulator in Relation to Suicidal Behaviour
Authors: Wasserman D. , Sokolowski M. , Wasserman J.
Published: March 2009

Suicide, a phenomenon characterised by heterogeneous and complex causes affects about one million people each year.

Twin studies, adoption studies and family studies indicate the role of genetic factors in suicidal behaviours. Psychobiological hypotheses regarding suicidal behaviours involve neurotransmitters such as serotonin, norepinephrine, dopamine, and their correlation to psychological functions as well as the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Whereas the genes of e.g. the 5HT system and of the key NA-biosynthesis enzyme, tyrosine hydroxylase, have been studied extensively in this context the genes in the HPA axis have only begun to be investigated.

Our novel results on the genetic variation in the CRHR1 gene in connection to depression and stress among suicidal individuals and in the TBX 19 gene, which is regulated by CRH, suggest that genetic variation in the CRH-mediated regulation of the HPA axis is a factor of importance in suicidality, especially in males with depression.
Personality and Lifestyles in Voluntary Firemen
Authors: Albuquerque C.M. Sousa , Ribeiro J.L. Pais , Mota C.P. Baptista
Published: March 2009

Background:

The main objective of this study was to verify if the Lifestyles are related with the type of Personality of the firefighters. Another objective was to verify if stress is related with the Lifestyles adopted.

Methods:

This was a transversal study applied to 146 Firefighters of Leiria, with ages between the 17 and 60 years (44 female and 102 the male). We used the NEO-Pi-R to analyze Personality and the Lifestyles Appraisal Questionnaire.

Results:

We found a significant statistical correlation between the Lifestyle Part I (risk factors) and the Neuroticism, that suggests that these citizens tend to have a bigger risk to developing illnesses. They present higher values of concern, nervousness, hypochondriacs and they have more disability answers of coping. They tend to be emotionally unsafe, revealing, sometimes, feelings of incompetence. They also show sadness, fear, embarrassment, anger and guilt. We also found significant statistical between the lifestyle Part I (risk factors) and the Lifestyle Part II (Stress). Indicates that a higher risk of developing illness is related to higher levels of stress. It was verified that the citizens present high factors of risk for their health and that this factor helps to increase the loss of control of the perception of stress.
Examination and Follow-up War Related Posttraumatic Stress Disorder (PTSD) and Prolonged Posttraumatic Stress Syndrome (PTSS) by Telepsychiatry Service
Authors: Stojakovic M. , Stojakovic B.
Published: March 2009

Background and aims:

This study was examination by Telepsychiatry and E-consalting of war related posttraumatic stress disorder (PTSD).

Methods:

The subjects were 114 male psychiatric patients by Telepsychiatry and e-consulting with war-related PTSD by videoconferencing via broadband ADSL and WADSL by 768 kbps. Posttraumatic stress syndrome-PTSS scale and 20-item Zung self rating scale was used to assess state measures of symptom severity.

Results:

The symptoms of prolonged PTSS (posttraumatic stress syndrome) with duration between six moths and two years had been founded at 84(73,68%) and 30(26,32%) of patients had no PTSS. Symptoms of depression had been found at 72(63,15%) patients. The enduring personality exchange after catastrophic expiriense (F62.0), had been found at 15(13,15%) patients (P< 0.01); symptoms of depression had been found at 54(47,36%) patients after two years.

Conclusions:

Telepsychiatry service and e-consalting it is able to serve not only PTSD but also wide range of other patient population. Continued examination and follow-up evolution of PTSD symptoms by Telepsychiatry service may be important in predicting the eventual development of depressive symptoms and precipitation of F62.0 enduring personality exchange after catastrophic expiriense in the war related PTSD.
Depression in War-related Post Traumatic Stress Disorder and the Enduring Personality Change After Catastrophic Experience (F62.0) a 15-year Follow-up
Authors: Stojakovic M. , Stojakovic B. , Pandzic V. , Vukadinovic S. , Subotic M. , Martinovic M. , Marin R.
Published: March 2009

Objective:

This study was a 15-year follow-up examination. Many patients with F 62.0 and post traumatic stress disorder (PTSD) have symptoms of depression. The authors’ objective is to analyze symptoms of depression in F 62.0 and PTSD.

Method:

The subjects were 200 male psychiatric patients at a Clinic of psychiatry medical center Banjaluka and psychiatry department of with war-related PTSD. Post traumatic stress syndrom-PTSS scale and 21-item Hamilton Rating Scale for Depression-HAMD was used to assess state measures of symptom severity; from 3 months to 15 years after returning from the war.

Results:

The symptoms of prolonged PTSS (with duration between six moths and two years) had been founded at 54%, and 32% of patients had no diagnosis PTSD. The enduring personality change after catastrophic experience (F 62.0) had been found at 14% patients (with duration more than two years), 19% met HAMD Diagnostic Criteria for major depressive disorder.

The enduring personality exchange F 62.0 had been found at 8% patients and 16% met HAMD Diagnostic Criteria for major depressive disorder 15 years after returning from the war.

Conclusions:

The statistical relationship between level of combat exposure and PTSD symptoms at 15 years, suggests that it may take time for the consequences of traumatic exposure to become apparent. Moreover, degree of exposure may be important in predicting the eventual development of symptoms and precipitation of F 62.0 enduring personality exchange. Continued follow-up will address the evolution of PTSD symptoms in war related PTSD.
Psychosocial Adjustment and Assessment of Healthy-related Quality of Life on Children with Newly Diagnosed Cancer and their Family
Authors: Tsai M.H. , Huang Y.-S. , Yang C.-P.
Published: March 2009

Aims:

To assess healthy-related quality of life and psychosocial adjustment in children with newly diagnosed cancer and their parents immediately and 6 months after diagnosis and treatment of cancer.

Method:

A prospective, case control study was conducted on eighty-nine children with newly diagnosed cancer, aged between 6 months to 16.7 years (mean, 8.2 years), and ninety healthy children of matched age group and social background. The children were assessed with the Child Behavior Checklist (CBCL), and the Parenting Stress Index (PSI) and the SF-36 questionnaire were administered to their parents immediately after diagnosis of cancer, 3 months after chemotherapy, and 6 months after chemotherapy.

Results:

No matter at the period immediately after diagnosis of cancer, 3 months or 6 months after starting chemotherapy, the parents of children with cancer scored significantly worse on every domains of SF-36 except body pain and every subscales of PSI except distractibility/hyperactivity and attachment when compared with the control group. The cancer group scored consistently lower on all CBCL syndrome scales than the control group, with anxiety, depression and body pain being significantly different. After starting chemotherapy, the parents reported improved scores on quality of life and decreasing parenting stress in both parent and child domains since 3 months or 6 months after starting chemotherapy.

Conclusion:

Considerable distress was experienced by both children with newly diagnosed cancer and their parents during the period immediately after diagnosis. However, parents can adjust gradually since 3 months after starting chemotherapy and experience improved quality of life.
Emotional Stress and Primary Hypertension in Adults
Authors: Suliburska J. , Krejpcio Z. , Wojciak R.W.
Published: March 2009

Psychological factors in the etiology of hypertension is supported by many epidemiological investigations. However, further studies are warranted because inconsistent results of several experimental and clinical studies. The aim of this study was to estimate the exposure and the resistance to emotional stress in hypertensive patients.

The 33 subjects with diagnosed primary hypertension (17 women and 16 men, 47.8±12.6 years ) and 29 healthy volunteers (12 women and 17 men, 30.0±11.0 years ) were examined. The exposure and the resistant to emotional stress in the subjects was assayed based on a questionnaire including items to assess sources of stress, occurrence of emotional stress in life periods (from childhood to nowadays) as well as the resistance to stress in the subjects own sense as good, moderate and weak. All the participants had also measured blood pressure.

Most of the subjects (80%) were exposed to emotional stress in both groups. Results of the study showed that the main sources of emotional stress in hypertensive subjects were: job (56%), family (74%) and health (56%) while in the healthy: job (50%) and family (79%). The least 11% of healthy people declared health as the main source of stress. It was found that significantly higher percentage of hypertensive subjects declared weak resistance to stress than healthy (55 vs.17%). Analysis of blood pressure didn't show any significant dependence on stress in both studied groups.

Based on the obtained results it is justified to conclude that hypertensive patients were less resistant to emotional stress than healthy people.
Stress, Coping, and Comorbidity among Hemodialysis Patients
Authors: Yeh S.-C.J.
Published: March 2009

Purposes:

The primary purposes of this study were 1) to examine relationships among stress, coping and comorbidity and 2) to test the interaction effect of comorbidity.

Background:

Hemodialysis imposes a variety of physical and psychosocial stressors that challenge patients. Comorbidity is a risk factor for many health outcomes. Research on how comorbidity influences the relationship between coping and stress is limited.

Method:

In this cross-sectional study using face to face interviews, we interviewed 2642 hemodialysis patients fifteen years or older on dialysis for at least 3 months from October 2002 to January 2003. The Hemodialysis Stressor Scale measured stressors and the Jalowiec Coping Scale were used to measure coping strategies. A hierarchical regression was used to analyze the data.

Results:

Hemodialysis patients with comorbidities were found to have higher levels of stress. Comorbidity had a moderating effect between choice of problem-oriented responses and isolated thoughts as coping strategies. These findings show that hemodialysis patients with comorbidities often choose positive coping strategies.

Conclusion:

HD patients with comorbidity have a higher stress scores than those without comorbidities. Comorbidity not only has a direct impact on stress but also has a moderating effect on the relationship between coping and stress. Therefore, taking into account the comorbidity factor became very crucial when assessing the HD patients’ level of stress.
Asymptotic solution for field-line reconnexion. Compressible case of Petschek's model
Authors: Semenov V. S. , Kubyshkin I. V. , Heyn M. F.
Published: March 2009

For the solution of Petschek's problem of field-line reconnexion, a new method is elaborated which is based on the introduction of a special co-ordinate system in which the streamlines and the magnetic lines of force become co-ordinates simultaneously. We have constructed the zero-order and the first-order approximation (for small Alfvén Mach numbers) for the solution of Petschek's problem in the steady-state, compressible, two-dimensional symmetric case. It is shown that the density across the slow shock wave increases by a factor

and the pressure by

(β = 8πρ0/B20, γ being the adiabatic exponent), and the plasma accelerates up to the Alfvén velocity. On the bases of the results obtained and of the analysis of numerical experiments on the reconnexion problem we draw the conclusion that during the initial phase of the process there develops a current sheet as described by Syrovatskii and that simultaneously there is a development of the tearing mode instability whose nonlinear phase creates the condition for the reconnexion process in the sense of Petschek.
Exact damped sinusoidal electric field of nonlinear one-dimensional Vlasov-Maxwell equations
Authors: Abraham-Shrauner B.
Published: March 2009

An exact solution for a temporally damped sinusoidal electric field which obeys the nonlinear, one-dimensional Vlasov-Maxwell equations is given. The electric field is a generalization of the O'Neil model electric field for Landau damping of plasma oscillations. The electric field is a special case of the form found from the invariance of the one-dimensional Vlasov equation under infinitesimal Lie group transformations. The time dependences of the damping decrement, of the wave-number and of the angular frequency are derived. Use of a time-dependent BGK one-particle distribution function is justified for weak damping where, in general, it is necessary to carry out a numerical calculation of the invariant of which the distribution function is a functional.
Compton and Raman free electron laser stability properties for a cold electron beam propagating through a helical magnetic wiggler
Authors: Davies John A. , Davidson Ronald C. , Johnston George L.
Published: March 2009

This paper gives an extensive characterization of the range of validity of the Compton and Raman approximations to the exact free electron laser dispersion relation for a cold, relativistic electron beam propagating through a constantamplitude helical wiggler magnetic field. The electron beam is treated as infinite in transverse extent. Specific properties of the exact and approximate dispersion relations are investigated analytically and numerically. In particular, a detailed numerical analysis is carried out to determine the range of validity of the Compton approximation.
Stimulated scattering of electromagnetic waves by magnetosonic modes in a plasma
Authors: Stenflo L.
Published: March 2009

The dispersion relation for magnetosonic waves in a dissipative plasma, which is penetrated by a high-frequency electromagnetic wave, is derived. Previous results are generalized and discussed.
On the kinetic theory of stable and weakly unstable plasma. Part 1
Authors: Rogister A. , Oberman C.
Published: March 2009

A kinetic theory is presented which is valid for both weakly unstable and stable plasma. The theory corrects the conventional Balescu—Guernsey—Lenard description for the weakly stable portions of the fluctuation spectrum. The theory is no longer Markoffian in the distribution function F alone but is in the pair F and Ik the spectrum of fluctuations. Further the evolution in time from an initially weakly unstable distribution to the stable regime can be described. Even after passage into the stable state the fluctuations can be large nd lead to enhanced diffusion across a magnetic field. The coefficient of spatial diffusion is given in this weakly stable (or untable) state. A strong coupling is found between plasmons and the particles in the distribution with velocities near the phase velocities of the plasmons. There is only weak thermal contact between the plasmons and these particles with the main body of the distribution whenever certain nonlinear processes are of secondary importance.
The dispersion and attenuation of helicon waves in a cylindrical plasma-filled wave-guide
Authors: Ferrari R. L. , Klozenberg J. P.
Published: March 2009

The dispersion equation for helicon waves in a plasma-filled wave-guide is derived. The relation between the solution and the quasi-static modes of Trivelpiece & Gould is discussed. An approximate dispersion relation, appropriate for cases where Ωe≫ ν ≫ ω, is obtained allowing the real and imaginary parts of the propagation constant to be expressed very simply in a normalized form. Curves are presented for this approximation.
Non-linear dispersion of cold plasma waves
Authors: Tam Christopher K. W.
Published: March 2009

The propagation of a packet of weakly non-linear dispersive cold plasma waves is studied by means of a two-time scale expansion. The effects of amplitude dispersion and the coupling to the mean plasma motion are taken into account. The governing equations are put into a conservation form. It is found that this system of equations is elliptic or hyperbolic depending on the wave-number of the dispersive waves. In the elliptic case modulations in the wave train grow exponentially in time and a periodic wave train will be unstable in this sense. In the hyperbolic case, slow variations in the wave train propagate and the characteristic velocities give a non-linear generalization of the linear group velocity. It is shown that except for waves which have their wave vectors nearly at right angle to the unperturbed magnetic field only fast waves with wave-number less than 0.585 (ΩiΩe)½/Vαare stable; where Vais the Alfvén velocity and ΩιΩε, are the ion and electron cyclotron frequencies respectively. A process of steepening of these waves into shocks with dissipation due to wave turbulence at the head of the wave packet is suggested.
Growing plasma oscillations for symmetrical double-humped velocity distributions
Authors: Cowley S. W. H.
Published: March 2009

The problem considered here is that of growing longitudinal waves which propagate in a hot plasma parallel to any magnetic field which may be present (i.e. the magnetic field is neglected in the Vlasov equation). The necessary and sufficient condition for stability was obtained by Penrose (1960) and growth rates for plasmas obeying a Maxwell zero-order velocity distribution were computed by Fried & Conte (1961).
Scattering from magnetic fluctuationst†
Authors: Thompson William B.
Published: March 2009

Scattering of optical and radio frequency radiation from electron density fluctuations in a plasma has been extensively studied and bids fair to become a useful diagnostic tool (see, for example, Davies & Ramsden, 1964, 1966). The scattered spectrum, although difficult to observe, contains a great deal of information. The electron density, ion and electron temperatures, the shape of the tail of the electron distribution function, spectral fluctuations in unstable systems, the magnitude and direction of the magnetic field and the charge to mass ratio of the ions present all seem to be contained in it.
Growth of ambipolar electric field in a toroidal plasma
Authors: Stringer T. E.
Published: March 2009

In the neo-classical theory of transport process in a toroidal plasma with long mean free path, the value of the poloidal rotation is determined by ambipolarity. This paper investigates the time-dependent phase during which this rotation develops. Diffusion arises from resonant particles, for which v∥ ≃ Er /Bφ. The time a particle spends in resonance, and hence its radial displacement, is now determined by the rate of change of Er, rather than collisional scattering. The time for Er to approach its quasi-stationary value is comparable to the mean time for an ion to travel the connexion length. This is short compared with typical experimental durations. The mass flow also builds up parallel to the magnetic field, but its contribution to the poloidal flow is small compared with the Er /B electric drift.
Soliton formation in magnetized Vlasov plasmas
Authors: Turner J. G. , Boyd T. J. M.
Published: March 2009

Soliton formation at the upper hybrid frequency has been discussed recently on the basis of warm two-fluid theory. In this paper we report the results of a reductive perturbation theory analysis of the Vlasov equation describing the nonlinear modulation of electrostatic waves in a warm magnetized plasma. This approach allows a treatment of soliton formation with scale lengths of the order of, or less than, the electron Larmor radius rL for both upper hybrid and Bernstein waves. A three-dimensional generalized nonlinear Schrödinger equation has been found. Contributions to the nonlinear frequency shift derive from three distinct processes. One contribution describes the generation of the second harmonic governed by (ω + ω) → 2w where ω is the frequency of the electrostatic carrier; a second arises from the self-interaction between the high-frequency waves (ω + ω → ω + ω) while the third contribution describes the nonlinear coupling between the carrier and the slow background plasma motion.

Propagation orthogonal to the magnetic field is studied and leads to a simplified nonlinear Schrodinger equation with cubic nonlinearity, predicting soliton formation at the upper hybrid and cyclotron harmonic frequencies. Expressions for the nonlinear frequency shift coefficient are presented for the upper hybrid and Bernstein modes in the low temperature limit and the relative strengths of the three competing nonlinear processes are compared. For krL ≥ 1·0, numerical analysis shows the dominant nonlinearity to be that arising from the nonlinear wave-particle interaction. The stability of the soliton solution is determined by the relative signs of the dispersion and the nonlinear frequency shift coefficient. Some properties of upper hybrid and Bernstein solitons are examined. In particular the variation of the normalized dispersion and nonlinear frequency shift coefficient with the basic plasma parameters (krL)2 and (ωpe/Ω, is presented, where (ope, fi are the electron plasma frequency and electron gyrofrequency respectively. Regions of instability are identified for both upper hybrid and Bernstein modes. The connection between reductive perturbation theory and previous warm fluid theories is also established.
A macroscopic interpretation of Landau damping
Authors: Subramaniam V. V. , Hughes W. F.
Published: March 2009

A macroscopic interpretation for the problem of Landau damping of longitudinal oscillations in a collisionless plasma is investigated by including macroscopic fluid conservation of mass, momentum, and energy. It is shown that Landau damping may be derived macroscopically by appropriate consideration of the heat flux term for a collisionless plasma. This heat flux is expressed in terms of the perturbed velocity distribution function. A possible form of an equivalent complex thermal conductivity is postulated for a collisionless plasma. Both temporal and spacial damping are discussed.
Compton and Raman free electron laser stability properties for a warm electron beam propagating through a helical magnetic wiggler
Authors: Davies John A. , Davidson Ronald C. , Johnston George L.
Published: March 2009

This paper gives an extensive analytical and numerical characterization of the growth-rate curves (imaginary frequency versus wavenumber) derived from the free electron laser dispersion relation for a warm relativistic electron beam propagating through a constant-amplitude helical magnetic wiggler field. The electron beam is treated as infinite in transverse extent. A detailed mathematical analysis is given of the exact dispersion relation and its Compton approximation for the case of a water-bag equilibrium distribution function (uniform distribution in axial momentum pz). Applicability of the water-bag results to the case of a Gaussian equilibrium distribution in pz is tested numerically. One result of the water-bag analysis is a set of validity conditions for the Compton approximation. Numerical and analytical results indicate that these conditions are applicable to the Gaussian case far outside the parameter range where the individual water-bag and corresponding Gaussian growth rate curves agree.
Second harmonic plasma emission involving ion sound waves
Authors: Cairns Iver H.
Published: March 2009

The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L ± S→T, proceeding in two three-wave steps, L ± S→L′ and L + L′→T, where L, S and T denote Langmuir. ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L′ and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.
Third and higher harmonic plasma emission due to Raman scattering
Authors: Cairns Iver H.
Published: March 2009

The theory for third and higher harmonic plasma emission by the weak turbulence (or random phase) process L + T′→T (where L denotes a Langmuir wave, and T and T′ denote transverse waves) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. The cases of L waves produced either directly by a streaming instability, or by the decay L→L′+S (S is an ion sound wave) of L waves generated by a streaming instability, are considered. Limits on the brightness temperature of the radiation are determined, and expressions for the growth rate and path-integrated wave temperatures are derived.
Nonlinear excitation of slow shear Alfvén mode by electromagnetic waves
Authors: Saleem H.
Published: March 2009

Nonlinear decay of large-amplitude ordinary and extraordinary electromagnetic waves into an electrostatic upper-hybrid wave and a slow shear Alfvén wave in a low-β plasma is considered. Expressions for the growth rates and thresholds are obtained. Applications of this investigation to both space and laboratory plasmas are pointed out.
Arbitrary-amplitude rarefactive ion-acoustic double layers in warm multi-fluid plasmas
Authors: Baboolal S. , Bharuthram R. , Hellberg M. A.
Published: March 2009

Large- and small-amplitude rarefactive ion-acoustic double layers have recently been studied in a fluid plasma with double Maxwellian electrons and a single cold ion species. Here the stationary large-amplitude theory is generalized to include two warm ion species. A technique for numerically solving the full nonlinear problem is presented. With it, useful predictions of the effect of ion temperatures and of light-ion contamination on the double-layer structure are made. A generalization to an arbitrary number of similar fluid components is pointed out. The small-amplitude perturbation theory is also extended to such a plasma, and in its restricted regime good qualitative agreement is obtained with the results of the large-amplitude theory.
Kinetic equation, spin hydrodynamics and collisional depolarization rate in a spin-polarized plasma
Authors: Balescu R. , Zhang W. Y.
Published: March 2009

On the basis of our previous work, a rigorous kinetic equation for a spin-polarized plasma is derived in the weak-coupling quasi-classical limit. The macroscopic polarization vector is defined in a unified form for spin-½ and spin-1 particles. Using the kinetic equation, an equation for the macroscopic polarization density is derived in the form of a ‘spin-hydrodynamical equation’. The depolarization rate for the spin–orbit interaction and the spin–spin interaction is estimated. Some difficulties for the spin–spin interaction are displayed and discussed.
Electromagnetic fluctuations from energetic particles in plasmas
Authors: Chu Cheng , Sperling J. L.
Published: March 2009

Electromagnetic fluctuations, induced by energetic charged particles, are calculated using correlation techniques for a uniform magnetized plasma. Power emission in the ion-cyclotron range of frequencies (ICRF) is calculated for a specific model of velocity distribution function. The emissive spectra are distinct from that of the black-body radiation and have features that are consistent with experimental observation.
Three-dimensional stability of solitary shear kinetic Alfvén waves in a low-beta plasma
Authors: Das K. P. , Kamp L. P. J. , Sluijter F. W.
Published: March 2009

The three-dimensional stability of solitary shear kinetic Alfvén waves in a low-β plasma is investigated by the method of Zakharov & Rubenchik (1974). It is found that there is no instability if the direction of perturbation falls within a certain region of space. The growth rate of the instability for the unstable region is determined. This growth rate is found to decrease with increasing angle between the direction of propagation of the solitary wave and the direction of the external uniform magnetic field. A particular case of the present analysis gives results on the stability of ion-acoustic solitons in a magnetized plasma.
The dispersion relation and the dielectric tensor of inhomogeneous magnetized plasmas
Authors: Fo. R. A. Caldela , Schneider R. S. , Ziebell L. F.
Published: March 2009

Electromagnetic-wave propagation in inhomogeneous magnetized plasmas is studied. Two different approaches to the subject are discussed and compared. Explicit expressions for the dielectric tensor components are derived following an established procedure that takes into account the effects of the gradients of plasma parameters, and are shown to possess non-resonant contributions to the anti-Hermitian parts. General and explicit expressions are also derived by following a different approach that has recently appeared in the literature, and are shown to possess satisfactory symmetry properties leading to anti-Hermitian parts comprising only resonant terms. The simple case of high-frequency waves in the ordinary mode propagating perpendicularly to the ambient magnetic field is presented as an example in order to show that the use of the dielectric tensor derived using the second method correctly describes wave absorption and/or amplification, eliminating the feature of non-resonant absorption that arises from the use of the first method.
On the existence of transverse MHD oscillations in an inhomogeneous magnetoplasma
Authors: Wright Andrew N.
Published: March 2009

In a cold plasma with no compressional field perturbation the equations governing the two perpendicular components of magnetic-field perturbation decouple. These two equations depend only upon spatial derivatives along the background magnetic field, and give the impression of independent field-line motion in the two transverse directions. However, the perturbation magnetic field b must be divergence-free. It is not meaningful to ask if the field perturbation on an individual background line of force satisfies ∇. b = 0. To decide whether b is divergence-free, we need to know about its spatial variation, i.e. what the state of the neighbouring field lines is. In this paper we investigate two classes of solutions: first we allow the perturbation magnetic flux to satisfy ∇. b = 0 by threading across the background lines of force; the second solution closes b by allowing the perturbation flux to encircle the background field lines (torsional Alfvén waves). For both of these solutions we study the relationship between neighbouring field lines, and are able to derive a set of criteria that the background medium must satisfy. For both classes we find restrictions upon the background magnetic-field geometry - the first class also has a constraint upon the plasma density. The introduction of perfectly conducting massive boundaries is also considered, and a relation given that they must satisfy if the field perturbation is to remain transverse. The criteria are presented in such a manner that it is easy to test if a given medium will be able to support the solutions described above. For example, a three-dimensional dipolo geometry is able to carry oscillatory toroidal fields; but not purely poloidal ones or a torsional Alfvén wave.
Relaxed states in a spheromak with inhomogeneous boundary fields
Authors: Dixon A. M. , Browning P. K. , Bevir M. K. , Gimblett C. G. , Priest E. R.
Published: March 2009

In this paper we consider force-free equilibrium solutions of the MHD equations in a spherical geometry for the case in which magnetic flux crosses the boundary of the containing vessel. The main motivation is to model more faithfully actual spheromak experiments in the laboratory, for which boundaries are unlikely to be magnetic surfaces. We show how a general inhomogeneous boundary field may be constructed from individual components. In particular, we consider the cases of a boundary field of dipolar form and one of quadrupolar form. We then go on to discuss solutions for fields embedded in point or ring electrodes using the ‘general solution’, some of which can be used to model experiments such as the PS-1- or CTX-type spheromaks.
Anisotropic-ion-beam-plasma interaction: drift perpendicular to magnetic field
Authors: Singh P. , Bharuthram R. , Hellberg M. A.
Published: March 2009

Using kinetic theory, low-frequency electrostatic instabilities driven by an anisotropic ion beam are investigated: In our model both the ions and electrons are magnetized, while the beam drift is across the external magnetic field. Both the ion-acoustic and ion–ion two-stream instabilities are excited. Regions of parameter space for the existence of either instability are distinguished. Detailed comparisons are made with the isotropie case.
Toroidal plasma equilibrium with arbitrary current distribution
Authors: Kucinski M. Y. , Caldas I. L. , Monteiro L. H. A. , Okano V.
Published: March 2009

A new System of co-ordinates is found and a method developed to determine the toroidal equilibrium of plasmas with arbitrary current distribution and plasma cross-section. The method depends on knowledge of the equilibrium of a straight plasma column of similar cross-section and similar current distribution. A large aspect ratio is assumed. By successive approximations, better solutions can be obtained. An explicit formula is presented for the poloidal flux of a nearly circular plasma. This can be written in terms of a function related to the asymmetry of the poloidal field due to toroidality. The method works provided that there is only one magnetic axis.
Low-frequency instability excited by a mesh grid in a double-plasma device
Authors: Chutia J. , Sato S. , Kubo H. , Nakamura Y.
Published: March 2009

Coherent low-frequency oscillations whose frequency is lower than the ion plasma frequency are generated by a mesh grid with negative d.c. bias in a double-plasma device. The frequency is inversely proportional to the one-quarter power of the grid voltage under a fixed plasma density, and is proportional to the ion plasma frequency when the grid bias is kept constant. With potential profiles near the grid, which are measured by an emissive probe, the transit time of ions is numerically calculated. The inverse of the transit time agrees well with the oscillation frequency. The oscillation is considered to be excited by a klystron bunching effect of incident ions towards the ion-rich sheaths.
Density-modulation effects on the propagation of an electromagnetic wave in a plasma
Authors: Lontano Maurizio , Lunin Nicolai
Published: March 2009

The propagation of an electromagnetic wave through a transparent plasma characterized by a spatial modulation of the density in the direction of propagation is analysed by computing the reflection coefficient of a single plasma slab and then that relevant to a set of many identical or slightly different slabs. The transmission spectra relevant to different density profiles of a single slab are computed to show the effects of (a) the density gradient, (b) a slight non-uniformity among adjacent slabs and (c) plasma modulation on the linear cut-off.