bluuebunny/crossref_metadata_2025 huggingface dataset:
Microdislodgment:
Authors: KIKUCHI KAN , ABE HARUHIKO , NAGATOMO TOSHIHISA , NAKASHIMA YASUHIDE
Published: December 2004

High impedance tined steroid‐eluting leads, Medtronic CapSure Z family, incorporating a small surface (1.2 mm2) electrode made of porous platinum material are designed to reduce battery current drain. However, in some prior studies, an increased incidence of microdislodgment with this lead was reported thought to be due to the reduced electrode surface area. This article reports the experience that ventricular pacing failure due to microdislodgment occurred after CapSure Z lead implantation and the previous literature is reviewed. (PACE 2003; 26[Pt. I]:1541–1543)
Lead Extraction Via the Femoral Artery of a Left Ventricular Pacing Lead Inserted in the Subclavian Artery
Authors: BRACKE FRANK , GELDER BERRY VAN , CUYPERS PHILIPPE , MEIJER ALBERT
Published: December 2004

We describe the extraction of a pacing lead via the femoral artery 5 months after it was inadvertently introduced through the right subclavian artery and positioned in the left ventricle. The lead was dislocated from the myocardium by traction from the subpectoral area and subsequently removed with a retriever inserted through the femoral artery in order to minimize the risk of cerebral embolization and bleeding at the entry site. Bleeding was controlled at the subclavian artery entry site by temporary inflation of a balloon catheter inserted through the brachial artery, and at the insertion site of the retriever in the femoral artery with a closure device. (PACE 2003; 26[Pt. I]:1544–1547)
Catheter‐Based Untying of a Knot on an Electrode Catheter
Authors: SOCHMAN JAN , HORACEK ALES , VRBSKA JANA
Published: December 2004

This case report describes an unusual complication: a knot formed on an electrode catheter, which became entangled in a pelvic vein and could not be withdrawn. The case was managed by a new catheter technique allowing the knot to be untied and subsequently removing it via the insertion site without the need for surgical intervention. (PACE 2003; 26[Pt. I]:1548–1550)
Pathophysiology of the Pulmonary Vein as an Atrial Fibrillation Initiator:
Authors: CHEN SHIH‐ANN , CHEN YI‐JEN , YEH HUNG‐I , TAI CHING‐TAI , CHEN YAO‐CHANG , LIN CHENG‐I
Published: December 2004

The basic electrophysiologic studies have proved the arrhythmogenic mechanisms of the pulmonary vein as an atrial fibrillation initiator; the mechanisms include enhanced automaticity, triggered activity, and microreentry from myocardial sleeves inside pulmonary veins. Immunohistology study has proved the conduction characteristics of pulmonary vein myocardium, and further study of ionic currents are important for understanding atrial fibrillation initiation from the pulmonary vein. (PACE 2003; 26[Pt. II]:1576–1582)
β‐Blocker Therapy in Atrial Fibrillation
Authors: GRÖNEFELD GERIAN C. , HOHNLOSER STEFAN H.
Published: December 2004

Beta‐blocking agents are a generally established therapy to achieve rate control in patients with AF. With the widely spread belief that rhythm control is the therapy of choice, their use is currently limited to patients that were considered not suitable for specific antiarrhythmic drug therapy. In contrast to that belief, recent studies show that β‐blockers do have some benefit in maintaining sinus rhythm or reducing the frequency of paroxysmal AF and that this benefit might be comparable to conventionally used antiarrhythmic drugs, with the exception of amiodarone. In addition, four prospectively randomized studies recently presented concluded that rate control may be an appropriate aim as a first line approach in patients with AF. Hence, an increased use of β‐blockers in the treatment of patients with AF is to be expected, given the proven prognostic benefit of these drugs in many cardiovascular disorders that are associated with AF. However, no prospective study has yet proven that β‐blockers do exert the same benefit in patients in AF, and one retrospective analysis suggests that there may be differences with regard to the potential benefits of β‐blocker therapy when patients are in AF compared to sinus rhythm. The article summarizes available clinical studies and reviews some experimental data examining the treatment effects of antiadrenergic therapy in AF. (PACE 2003; 26[Pt. II]:1607–1612)
Class I or Class III Agents for Atrial Fibrillation:
Authors: PACIFICO ANTONIO , HENRY PHILIP D.
Published: December 2004

Atrial fibrilliation (AF) is often combined with advanced age and structural heart disease, conditions known to invite serious proarrhythmic complications of antiarrhythmic drug therapy. Recent controlled trials comparing two AF treatment strategies—rhythm control requiring atrial defibrilliation and antiarrhythmic drugs to prevent AF and ventiricular rate control obviating sinus rhythm maintenance with such drugs—showed equal or superior results with rate control. AF is associated with derepressions of “fetospecific” expression patterns that may profoundly alter the responsiveness of atrial muscle to antiarrhythmic drugs. Therefore, effects of drugs predicted according to pharmacological classifications evaluating drug actions in intact myocardium only should be interpreted cautiously. The classification proposed by Vaughan Williams fails to distinguish between acute and chronic drug efficacy and toxicity as recommended in classical pharmacology. There is, however, overwhelming evidence that acute and chronic drug effects often differ fundamentally. For instance, amiodarone acts acutely as a sodium channel blocker, whereas chronic effects may be mediated by a downregulation of thyroid hormone receptors. Meaningful direct effects of amiodarone on atrial potassium channels is questionable, since the main candidate target‐current (IKr) may not be expressed in human atrial muscle. Multiple biophysical factors contribute to the lack of ion channel‐selective actions of antiarrhythmic agents. Nonselectivity becomes particularly important in the context of mechanisms of action of Vaughan Williams Class I and III agents on human atrial muscle. Preclinical studies indicate that Class I agents such as flecainide and propafenone may act in AF predominantly as Class III agents. Meta‐analyses of antiarrhythmic agents for the prevention of AF have failed to reveal superior drugs or drug classes. Superiority of amiodarone over other agents may depend on arbitrary amiodarone‐favoring loading protocols producing significant differential effects exclusively during the acute phase of treatment. In conclusion, the classification of current antiarrhythmic agents into Class I and III may not be a useful simplification when applied to the pharmacotherapy of AF. (PACE 2003; 26[Pt. II]:1613–1619)
Sensitivity of 70‐mer oligonucleotides and cDNAs for microarray analysis of gene expression in Arabidopsis and its related species
Authors: Lee Hyeon‐Se , Wang Jianlin , Tian Lu , Jiang Hongmei , Black Michael A. , Madlung Andreas , Watson Brian , Lukens Lewis , Pires J. Chris , Wang Jiyuan J. , Comai Luca , Osborn Thomas C. , Doerge R. W. , Chen Z. Jeffrey
Published: December 2004

Synthetic oligonucleotides (oligos) represent an attractive alternative to cDNA amplicons for spotted microarray analysis in a number of model organisms, including Arabidopsis, C. elegans, Drosophila, human, mouse and yeast. However, little is known about the relative effectiveness of 60–70‐mer oligos and cDNAs for detecting gene expression changes. Using 192 pairs of Arabidopsis thaliana cDNAs and corresponding 70‐mer oligos, we performed three sets of dye‐swap experiments and used analysis of variance (anova) to compare sources of variation and sensitivities for detecting gene expression changes in A. thaliana, A. arenosa and Brassica oleracea. Our major findings were: (1) variation among different RNA preparations from the same tissue was small, but large variation among dye‐labellings and slides indicates the need to replicate these factors; (2) sources of variation were similar for experiments with all three species, suggesting these feature types are effective for analysing gene expression in related species; (3) oligo and cDNA features had similar sensitivities for detecting expression changes and they identified a common subset of significant genes, but results from quantitative RT‐PCR did not support the use of one over the other. These findings indicate that spotted oligos are at least as effective as cDNAs for microarray analyses of gene expression. We are using oligos designed from ∼26 000 annotated genes of A. thaliana to study gene expression changes in Arabidopsis and Brassica polyploids.
High‐yield expression of a viral peptide animal vaccine in transgenic tobacco chloroplasts
Authors: Molina Andrea , Hervás‐Stubbs Sandra , Daniell Henry , Mingo‐Castel Angel M. , Veramendi Jon
Published: December 2004

The 2L21 peptide, which confers protection to dogs against challenge with virulent canine parvovirus (CPV), was expressed in tobacco chloroplasts as a C‐terminal translational fusion with the cholera toxin B subunit (CTB) or the green fluorescent protein (GFP). Expression of recombinant proteins was dependent on plant age. A very high‐yield production was achieved in mature plants at the time of full flowering (310 mg CTB‐2L21 protein per plant). Both young and senescent plants accumulated lower amounts of recombinant proteins than mature plants. This shows the importance of the time of harvest when scaling up the process. The maximum level of CTB‐2L21 was 7.49 mg/g fresh weight (equivalent to 31.1% of total soluble protein, TSP) and that of GFP‐2L21 was 5.96 mg/g fresh weight (equivalent to 22.6% of TSP). The 2L21 inserted epitope could be detected with a CPV‐neutralizing monoclonal antibody, indicating that the epitope is correctly presented at the C‐terminus of the fusion proteins. The resulting chimera CTB‐2L21 protein retained pentamerization and GM1‐ganglioside binding characteristics of the native CTB and induced antibodies able to recognize VP2 protein from CPV. To our knowledge, this is the first report of an animal vaccine epitope expression in transgenic chloroplasts. The high expression of antigens in chloroplasts would reduce the amount of plant material required for vaccination (∼100 mg for a dose of 500 µg antigen) and would permit encapsulation of freeze‐dried material or pill formation.
Thermography studies of the spatial and temporal variability in stomatal conductance of Avena leaves during stable and oscillatory transpiration
Authors: Prytz Gunnar , Futsaether Cecilia M. , Johnsson Anders
Published: December 2004

The spatial and temporal distribution of stomatal conductance of young Avena sativa cv. Seger leaves was studied when the whole‐leaf transpiration was stable or displayed complicated oscillatory behaviour to determine whether different regions of the leaf behaved synchronously.

A camera detecting infrared radiation in the 7.5–13 µm range was used to capture leaf temperature images which represented an indirect measure of the transpiration. Simultaneous gas exchange measurements of whole‐leaf transpiration were also recorded.

During nonoscillatory behaviour of whole‐leaf transpiration, nonhomogeneous, patch‐like temperature distributions across the leaf surface could sometimes be observed. However, during complex oscillatory behaviour or dampening of the oscillations, the entire leaf surface displayed the same temporal leaf temperature pattern as the whole‐leaf transpiration. Small phase differences characterized by distal regions lagging 0.5–3 min behind the central leaf region were observed.

The synchronous behaviour observed during oscillatory transpiration indicates strong coupling between stomata. During stable whole‐leaf behaviour, the coupling was weaker and temperature distributions similar to results categorized as patchy stomatal conductance could be observed.
Economic Costs of Substance Abuse, 1995
Authors: Rice Dorothy P.
Published: December 2004

Substance abuse causes illness and disease, results in high use of medical and other services and high productivity losses, and imposes a multibillion‐dollar burden on the economy each year. This article presents estimates of the economic burden of alcohol and drug abuse and smoking in 1995. Included are the direct medical care expenditures and indirect costs and the value of lost productivity for people who are ill and disabled and for people who die prematurely due to substance abuse. The methodology for the cost of alcohol and drug abuse is based on a study conducted by the Lewin Group in 1998 and prepared for the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism. The smoking‐attributable costs are based on a published study conducted by the author and her colleagues at University of California‐Berkeley and at University of California‐San Francisco for 1993 and updated to 1995. The total economic costs of substance abuse are estimated at $428.1 billion in 1995: alcohol abuse at $175.9 billion, drug abuse at $114.2 billion, and smoking at $138 billion. The distribution by type of cost varies among the three types of disorders, reflecting differences in the prevalence of these disorders, medical care use, morbidity and mortality patterns, and other related costs for each disorder. Effective interventions must be found to prevent and ameliorate the adverse health consequences of substance abuse, thereby reducing the future high costs of alcohol and drug abuse and smoking.
Systemic Replacement Therapy from Genetically Modified Epidermal Keratinocytes
Authors: Taichman Lorne B.
Published: December 2004

Epidermal keratinocytes are a potential vehicle for gene transfer and systemic delivery. We review data showing that epidermis‐secreted protein does indeed reach the circulation, and we discuss factors that bear upon the issue of how much protein epidermal keratinocytes can deliver to the circulation.
Inosine Monophosphate Dehydrogenase: A Molecular Switch Integrating Pleiotropic GTP‐Dependent β‐Cell Functions
Authors: Metz Stewart A. , Kowluru Anjaneyulu
Published: December 2004

Studies of pancreatic islet function in the pathogenesis of type 2 diabetes mellitus have tended to focus on the short‐term control of insulin secretion. However, the long‐term control of β‐cell mass is also relevant to diabetes, since this parameter is reduced substantially even in non‐insulin‐dependent diabetes in humans. In animal models of type 2 diabetes, the normal balance between β‐cell proliferation and programmed cell death is perturbed. We take the perspective in this overview that inosine monophosphate dehydrogenase (IMPDH; EC 1.1.1. 205) may represent a previously neglected molecular integrator or sensor that exerts both functional (secretory) and anatomical (proliferative) effects within β‐cells. These properties reflect the fact that IMPDH is a rate‐limiting enzyme in the new synthesis of the purine guanosine triphosphate (GTP), which modulates both exocytotic insulin secretion and DNA synthesis, as well as a number of other critical cellular functions within the β‐cell. Alterations in the expression or activity of IMPDH may be central to β‐cell replication, cell cycle progression, differentiation, and maintenance of adequate islet mass, effects that are probably mediated both by GTP directly, and indirectly via low molecular mass GTPases. If GTP becomes depleted, a hierarchy of β‐cell functions becomes progressively paralyzed, until eventually the effete cell is removed via apoptosis.
Birth Certificate Methods in Five Hospitals
Authors: Northam Sally , Polancich Shea , Restrepo Elizabeth
Published: December 2004

Abstract  This study evaluated the methods of data collection of birth certificate information by five high‐delivery hospitals in northern Texas. Research purposes were to identify sources and methods of birth certificate data collection and identify the most‐reliable methods. This descriptive study involved interviews of each hospital's data collectors and review of 1999 Texas birth certificate data. Medical record clerks, whose training varied, but usually consisted of orientation by another medical record clerk, collected birth certificate data within 24 hours of birth. There was no standard method for training, nor was there a minimum level of education required. In four of the five hospitals studied, a birth certificate clerk collected most of the information with limited input from other medical sources. The information obtained on birth certificates therefore varied according to the collector and the priority placed upon the accuracy of information. Birth certificate data contain questionable reliability, which undermines data use in research, funding, and policy decisions.
Proceedings of the 1998 Meeting of the Society for Pediatric Dermatology
Authors: Duarte Ana M. , ROTHMAN KAREN F.
Published: December 2004

The Society for Pediatric Dermatology held its annual meeting in Cambridge, Massachusetts, on July 23–26, 1998. Selected summaries of presentations at the meeting follow.
Proceedings of the 1998 Meeting of the Society for Pediatric Dermatology
Authors: Duarte Ana M. , KORF BRUCE R.
Published: December 2004

The Society for Pediatric Dermatology held its annual meeting in Cambridge, Massachusetts, on July 23–26, 1998. Selected summaries of presentations at the meeting follow.
Proceedings of the 1998 Meeting of the Society for Pediatric Dermatology
Authors: Duarte Ana M. , SHWAYDER TOR
Published: December 2004

The Society for Pediatric Dermatology held its annual meeting in Cambridge, Massachusetts, on July 23–26, 1998. Selected summaries of presentations at the meeting follow.
Livedo Reticularis in a Child with Moyamoya Disease
Authors: Richards Kristen A. , Paller Amy S.
Published: December 2004

Abstract: Moyamoya disease is a rare, chronic cerebrovascular occlusive disease of unknown etiology. It is characterized by progressive stenosis of the arteries of the circle of Willis leading to an abnormal capillary network and resultant ischemic strokes or cerebral hemorrhages. The association of moyamoya disease with livedo reticularis has been described in a previously reported patient with a factor V Leiden mutation, leading to hypercoagulation. We describe a girl with livedo reticularis and moyamoya disease with extensive cardiovascular malformations, but without a primary coagulopathy.
Primary Cutaneous North American Blastomycosis in an Immunosuppressed Child
Authors: Zampogna Jennifer C. , Hoy Miranda J. , Ramos‐Caro Francisco A.
Published: December 2004

Abstract: Primary cutaneous blastomycosis and primary cutaneous sphaeropsidale infections are rare in children. We present a 6‐year‐old immunosuppressed girl who had a solitary ulceration on her left lower leg which showed histopathologic findings of blastomycosis. She responded readily to oral itraconazole.
LEOPARD Syndrome with a New Association of Congenital Corneal Tumor, Choristoma
Authors: Choi Won‐Woo , Yoo Jong‐Yeop , Park Kyoung‐Chan , Kim Kyu‐Han
Published: December 2004

Abstract: A 5‐year‐old girl with a family history of LEOPARD syndrome had multiple lentigines on the face and trunk, hypertelorism, and growth retardation. In addition, she had congenital corneal tumors on both eyes. Histologically the tumors were choristoma. The neuroectodermal origin hypothesis of LEOPARD syndrome could explain the presence of a congenital corneal tumor in this patient. We suggest that corneal tumor may represent an unrecognized associated finding in this syndrome.
Neonatal Lupus Erythematosus Mimicking Langerhans Cell Histiocytosis
Authors: Scheker Luis Emilio , Kasteler J. Scott , Callen Jeffrey P.
Published: December 2004

Abstract: Neonatal lupus erythematosus (NLE) is an autoimmune disease characterized primarily by transient skin lesions and/or permanent congenital heart block. Other clinical findings include self‐limited cytopenias and liver disease. The syndrome results from the passive transfer of maternal anti‐SSA, anti‐SSB, or anti‐U1RNP autoantibodies to the fetus across the placenta. The cutaneous manifestations are generally analogous to those of subacute cutaneous lupus erythematosus (SCLE) and consist of small, erythematous macules that progress to annular plaques with delicate scaling. The skin lesions usually resolve within the first 6 months of life as maternal autoantibodies are cleared from the infant's circulation. We describe a patient with cutaneous NLE with hepatic and hematologic manifestations. The clinical presentation was atypical, with splenomegaly and petechiae at birth followed by a crusting, papulosquamous skin eruption of the scalp and face mimicking Langerhans cell histiocytosis (LCH).
Linear Angioma Serpiginosum
Authors: Al Hawsawi Khalid , Al Aboud Khalid , Al Aboud Daifullah , Al Githami Ahmad
Published: December 2004

Abstract: Angioma serpiginosum distributed in a linear fashion along the upper extremity of an adolescent boy is described. Histopathologic examination revealed the characteristic numerous thick‐walled capillaries in the dermal papillae.
Congenital Acantholytic Dyskeratotic Dermatosis: Localized Darier Disease or Disseminated Benign Papular Acantholytic Dermatosis?
Authors: Bergua Paula , Puig Lluís , Fernández‐Figueras María‐Teresa , Baselga Eulalia , Alomar Agustín
Published: December 2004

Abstract: Acantholytic dyskeratosis is a histopathologic pattern defined by a hyperkeratotic and parakeratotic epidermis with intraepidermal clefts containing acantholytic and dyskeratotic keratinocytes. These typical features are distinctive but not entirely pathognomonic of Darier disease, since they may occur at cutaneous and mucocutaneous sites in other conditions such as Grover disease, acantholytic and dyskeratotic epidermal nevus (nevus of Starink), warty dyskeratoma, or acantholytic papular dermatosis localized to the vulvocrural area. We report a newborn girl who had congenital erosive papules and plaques located on the left thigh, left ankle, and right side of the neck. Histopathologic examination of a punch biopsy specimen disclosed findings typical of acantholytic dyskeratosis. In the absence of any family history or other manifestations of Darier disease, we propose the descriptive term “congenital acantholytic dyskeratotic dermatosis.” This descriptor characterizes our patient's disease on the basis of the clinical and histopathologic findings and facilitates recognition of this condition until a putative genetic mutation can be demonstrated or ruled out.
Harlequin Ichthyosis in Association with Hypothyroidism and Juvenile Rheumatoid Arthritis
Authors: Chan Yuin‐Chew , Tay Yong‐Kwang , Tan Lawrence Kang‐Seng , Happle Rudolf , Giam Yoke‐Chin
Published: December 2004

Abstract: Harlequin ichthyosis is a rare and severe congenital erythrodermic ichthyosis characterized at birth by hyperkeratotic plates covering the entire body, ectropion, eclabium, poorly developed ears, and contractures of the hands and feet. Two Chinese children, a 2‐year‐old boy and an 11‐year‐old girl, presented with these classic features as well as alopecia and loss of eyebrows and eyelashes. The boy was small for his age and was found to have hypothyroidism at the age of 18 months; he is currently on thyroxine replacement therapy. At 6 years of age, the girl developed symmetrical polyarthritis associated with positive rheumatoid factor and radiologic evidence of erosive arthritis, suggestive of juvenile rheumatoid arthritis. She received prednisolone, nonsteroidal anti‐inflammatory drugs (NSAIDs), and subsequently methotrexate for her arthritis, with clinical and radiologic improvement. Early therapy with oral retinoids in both children accelerated shedding of the hyperkeratotic plates as well as improved ectropion and eclabium. There was no major adverse reaction to oral retinoids. The development of juvenile rheumatoid arthritis in survivors with harlequin ichthyosis has not been previously described. The use of prednisolone and NSAIDs in the girl did not affect the skin condition, but the addition of methotrexate led to a decrease in erythema. The association with autoimmune disease is probably coincidental. The psychosocial impact of this severe lifelong disease on the two families was enormous. Early retinoid therapy may improve the disorder and help increase survival rates. A multidisciplinary approach, including psychosocial support of the affected families, is vital in the management of this lifelong disease.
Binary Correlations in Ionized Gases
Authors: Balescu R. , Taylor H. S.
Published: December 2004

An equation of evolution for the binary distribution function in a classical homogeneous, non-equilibrium plasma is derived. It is shown that the asymptotic (long-time) solution of this equation is the Debye distribution, thus providing a rigorous dynamical derivation of the equilibrium distribution. This proof is free from the fundamental conceptual difficulties of conventional equilibrium derivations. Out of equilibrium, a closed formula is obtained for the long living correlations, in terms of the momentum distribution function. These results should form an appropriate starting point for a rigorous theory of transport phenomena in plasmas, including the effect of molecular correlations.
Escape of Planetary Atmospheres. II. Lifetimes of Minor Constituents
Authors: Gilvarry J. J.
Published: December 2004

It is shown that the essential parameter determining the escape rate is the ratio to the exospheric scale height of the radius of the escape layer as measured from the planet's center. The result of the analysis is to replace Spitzer's parameter B by a modified value Ai for the lifetime of the ith minor constituent. This revision properly takes into account the effect on a minor constituent's lifetime of the difference in temperature between the escape layer and the endosphere. Correctly, the ratio of the minor constituent's molecular weight to a mean value for the atmosphere enters into Ai as a factor; the need for this particular correction to B has been pointed out previously by Nicolet and by Bates and McDowell. Numerically, it is found that Ai and B do not differ drastically for the case of He4 in the earth's atmosphere. Computations by Spitzer and by Urey for the loss of He4 from the earth are brought into agreement by revision of the data employed by the former, and thus the discrepancy between corresponding temperatures implied for the escape layer is removed.
Green's Function for Two-Dimensional Magnetohydrodynamic Waves. I
Authors: Weitzner Harold
Published: December 2004

The Green's function is evaluated for the Lundquist equations linearized about zero flow velocity and constant matter density and magnetic field. It is also assumed that all quantities depend on two space variables and time only and that the constant magnetic field lies in the plane of the chosen two space variables.
Quantal Study of Diffusion and Viscosity Cross Sections for a Screened Coulomb Potential
Authors: McDowell M. R. C. , Peach G.
Published: December 2004

Born's approximation and the Massey-Mohr approximation are used to obtain quantum-mechanical values of the diffusion and viscosity cross sections QD and Qη for a screened Coulomb potential. The parameters are chosen to represent an ionized gas with 108 ≤ ne ≤ 1018, ne being the electron density, and 5 × 103 ≤ Te ≤ 107°K, Te being the temperature. The scattering phase shifts are also evaluated and compared with those obtained from direct numerical integration of the scattering equation. Born's approximation to the phase shift is used in a Faxén-Holtsmark type analysis to give more accurate values of the cross sections at low Te and large ne. The results are used to discuss the behavior of the electrical conductivity of a fully ionized gas.
Flow of Low-Density High-Speed Plasma through a Magnetic Barrier
Authors: Gilleo M. A.
Published: December 2004

The barrier transmission ratio I/I0 of a stream of plasma can be evaluated from theory in terms of the temperatures and masses of the ions and electrons, the speed of the stream, and the ratio ΔB/B0 of the height ΔB of the barrier field above the guiding field B0. All of these parameters were measured for a hydrogen plasma except the ion temperature Ti. Johnson-Malter double-probe data yielded at the maximum density point of the stream a plasma speed of 1.3 × 107 cm sec−1, a number density of 5 × 1013 cm−3, and an electron temperature T̃e = 3.5 ± 0.2 ev for B0 = 780 gauss at the position of the barrier. I/I0 decreased to 0.5 for ΔB/B0 = 17.8 at which point a theoretical curve has been fitted with T̃i = 7.1 ev; this value for T̃i was confirmed by application of the equipartition theory of Spitzer to the observed change of electron temperature with time.
Structural and Internal State Variables in the Description of Scalar Rate Processes in Fluids
Authors: Nettleton R. E.
Published: December 2004

Arguments are presented to show that the internal energy per molecule in a macroscopically small volume element of an infinite liquid should remain constant, in first approximation, during a sudden fluctuation in liquid structure at constant density and temperature. This result is shown to be consistent with a formulation of nonequilibrium thermodynamics in which the departures of structural parameters from their local equilibrium values appear as thermodynamic variables and in which there is no relaxing structural specific heat. However, it is shown that such a relaxing specific heat must appear in the treatment of variables which give the populations of internal states. Consistent with this fact a new theory of thermal relaxation, which includes inertial effects, is formulated. It is shown, on plausible assumptions, that one can calculate all the rate constants and relaxation times introduced to describe inertial effects, as well as the thermodynamic forces.
Source and Reflection Problems in Magneto-Ionic Media
Authors: Meecham William C.
Published: December 2004

The scattering problems involving electromagnetic radiation propagating in magneto-ionic media are formulated. Because of the magnetic field the medium becomes anisotropic. A practical case of great interest is that in which the frequency of the radiation is very low, in the audio range. A Green's formula is derived which expresses the field in interior regions in terms of the value of the field on any scattering surfaces present and the effect of sources. The Green's formula involves the Green's function in the usual way. The Green's functions is obtained, using a representation in terms of the eigenmodes for electromagnetic radiation propagating in the medium. The Green's function is evaluated for the special case of very low frequency.
Influence of Ion Motions on Nonlinear Plasma Oscillations
Authors: Vernon Russel
Published: December 2004

The effect of ion motions on the structure of nonlinear stationary electrostatic oscillations of a cold plasma is investigated. A solution is found by means of an expansion in powers of the electron-to-ion mass ratio m/M. The frequency of oscillation, which is independent of amplitude for vanishing m/M, turns out to be a decreasing function of the amplitude when the ion motions are included.
Stability of the Sharp Pinch and Unpinch with Finite Conductivity
Authors: Jukes J. D.
Published: December 2004

The stability of the sharp linear pinch and unpinch is analyzed using a model in which the magnetic fields are separated by a thin current layer of large, but finite electrical conductivity. Elsewhere the contained fluid is assumed to have zero conductivity, a model which may, for example, approximate a plasma pinch heated by the intermixing of skew magnetic fields. The perturbed radial displacement of the layer is assumed to be constant across the layer and small wavelength perturbations comparable to the layer thickness are not considered. Viscosity is also neglected. The infinitely conducting, ``stabilized'' pinch and the unpinch are now shown to be overstable to perturbations whose helices are approximately orthogonal to the helix of the mean magnetic field across the layer. The overstable growth rate is typically one tenth of the geometric mean of a fundamental, oscillatory frequency and the Ohmic diffusion rate of the layer.
Quasi-Thermalization of a Plasma Beam
Authors: Salz Frank , Meyerand Russell G.
Published: December 2004

A study of the trajectories of charged particles as they pass through a cusped magnetic field shows that a significant fraction of their original axial kinetic energy is transformed into kinetic energy of rotation around the guiding centers of the particles. The energy-exchange mechanism predicted by an idealized model agrees exactly with the analog computer solution of the equations of motion of a particle and agrees generally with the results of an experiment in which a plasma beam was transmitted through a cusped magnetic field.
Growth of a Vapor-Filled Cavity near a Heating Surface and Some Related Questions
Authors: Forster Kurt Engelberg
Published: December 2004

The growth of a vapor bubble on a heating element immersed in a liquid which is at saturation temperature or subcooled far from the heating surface but which is superheated near the heating surface, is treated as a problem of heat conduction with evaporation on a boundary. The results show, in agreement with experiment, that in a liquid at saturation temperature the radius grows as t½ at first (t is time) and as t¼ for t → ∞; for a subcooled liquid the radius as a function of time is given as an infinite series in terms of a quantity H, later identified with the thickness of the thermal boundary layer. Several relations between boundary layer thickness in a boiling liquid, maximum radius attained by the cavity before collapse and superheat and subcooling are derived and compared with experiment. For large subcooling the boundary layer thickness is shown to be about one-half (or less) the size of the maximum radius. Physical considerations concerning the mechanism of heat transmission to a boiling liquid lead to the definition of a heat diffusivity, the exchange diffusivity a* = M2 a, with M the dimensionless ratio of enthalpies of superheated liquid and of saturated vapor. The dimension of the thermal boundary layer is shown to be the diffusion length for the exchange diffusivity.
Shock Initiation of Detonation in Liquid Explosives
Authors: Campbell A. W. , Davis W. C. , Travis J. R.
Published: December 2004

Experimental studies of the initiation of liquid explosives by strong plane shocks (pressures 50 to 100 kbar) are described. These experiments demonstrate thermal explosion as a result of shock heating in the explosive. When the shock enters the explosive, the explosive is heated. After a delay, detonation in the heated, compressed explosive begins at the interface, where the explosive has been hot longest. The detonation proceeds through the compressed explosive at a velocity greater than the steady state velocity in uncompressed explosive, overtaking the initial shock and overdriving detonation in the unshocked explosive. Most of the work has been done on nitromethane, but molten TNT, molten DINA, Dithekite 13, and single crystals of PETN are shown to behave in the same way. Experiments showing the effects of bubbles and shock interactions in the explosive are presented.
Exact Relativistic Fokker-Planck Coefficients for a Plasma
Authors: Simon Albert
Published: December 2004

We consider a plasma which, in zero order, is static, spatially uniform, and infinite in extent and with no external electric or magnetic fields. Exact relativistic Fokker-Planck coefficients are obtained by a solution of the first-order coupled integral equations for the particle and oscillator pair correlation functions. The solution is by a generalization of the method of Lenard and Balescu. The resulting coefficients have contributions from both Coulomb interactions and from interactions via transverse electromagnetic fields.
Gas Law and Conductivity of a Collision-Free Plasma
Authors: Buneman O.
Published: December 2004

The moment method is used to derive a form of two-component magneto-gas dynamics for a collision-free plasma. Closure of the moment equations is achieved by ignoring variations of fourth moments of the peculiar velocities for each component. This provides a ``fully adiabatic gas law'' which represents a generalization of the single or double adiabatic laws in that it predicts the gyrations of the pressure tensor, as well as the principal pressures. The currents which small perturbing electric fields cause to flow in each species in accordance with its own adiabatic gas dynamics are calculated. A complex conductivity tensor thus is deduced. This tensor is compared with that resulting from rigorous kinetic theory (without closure), for the case of a uniform plasma. It is found to be identical with the ``warm plasma approximation'' which takes into account temperature to first order. Hence a two-component fully adiabatic theory describes supersonic phenomena adequately but misses (altogether) the phenomenon of Landau damping. It could serve to provide pessimistic stability tests for nonuniform (confined) plasmas.
Self-Consistent Reversed Field Sheath
Authors: Mjolsness R. C. , Ribe F. L. , Riesenfeld W. B.
Published: December 2004

An analytic solution is obtained for the structure of a prototype reversed field sheath. The configuration is a region of uniform (direct) magnetic field separated from a second region of uniform (reversed) field of equal magnitude but opposite sign by a current sheath of finite width composed of zero temperature plasma. Growth rates of certain instabilities of the system are calculated. It is found that the modes considered do not grow as rapidly as the plasma frequency, but the growth rates may still be quite large. Finally, a qualitative discussion is given of the results to be expected when the reversed field is opposed by a direct field of larger magnitude.
Radiation Field and Q of a Resonant Cylindrical Plasma Column
Authors: Hershberger W. D.
Published: December 2004

A cylindrical plasma column displays a series of resonant responses when it is excited by an electromagnetic wave with its electric field and direction of propagation both perpendicular to the axis of the column. In the principal member of the mode spectrum, the electrons are taken to move in phase in a direction transverse to the axis of the column. The diameter of the column is small compared to wavelength. In this paper, for the transverse electronic motion described, an expression for the vector potential in the region about the column is derived and thence the electromagnetic field components. The radiation field components Eφ and Hz vary as ρ−½. The effect of radiation damping is calculated by deriving an expression for the selectivity factor Q. The expression is Q = (λ/a)2/2π3, when the radius a is much less than a wavelength.
Flow around a Sphere in a Circular Tube
Authors: Smythe W. R.
Published: December 2004

The vector potential for the flow of an ideal fluid through a tube containing a concentric spherical obstacle is found for ratios of sphere radius to tube radius of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 0.95. The flow is confined to the space between sphere and cylinder by thin vortex sheets of variable strength and a table of their circulation intensity on the spherical surface is given. Accuracies vary from about one part in 108 for small spheres to one part in 107 for large ones. The increase in the scalar velocity potential between the ends of the tube caused by the insertion of the sphere is expressed in terms of the effective increase in tube length. This also gives the increase in resistance of a solid conducting cylinder due to the presence of a concentric spherical bubble.
Kinetic Theory of Moderately Dense, Rigid-Sphere Gases
Authors: Livingston P. M. , Curtiss C. F.
Published: December 2004

By successive partial integrations of the Liouville equation, the hierarchy of BBGKY equations are obtained. The series is terminated at the second equation by the introduction of a superposition approximation. A specialization to rigid spheres is made early in the treatment. Then, after defining a nonequilibrium pair correlation function, the first BBGKY equation is identified as an Enskog equation modified by the inclusion of a momentum-dependent correlation function in the collision integral. This equation and the second BBGKY equation completely determine the singlet distribution and pair correlation functions. An approximate solution to this pair of equations follows from the usual linearized perturbation expansion of the singlet distribution and pair correlation functions for the system near equilibrium. A set of five equations in the coefficients of the gradients are obtained, and the coupling between them is resolved by expanding these coefficients in powers of the number density. Because of the limitations imposed by the superposition approximation, only the first few terms in the density expansions are considered explicitly. The solutions to these equations and the resulting modifications of the transport coefficients are discussed.
On Landau Damping
Authors: Dawson John
Published: December 2004

The problem of Landau damping of longitudinal plasma oscillations is investigated by dividing the plasma electrons into two groups. The first group is the main plasma and consists of all electrons with velocities considerably different from the wave velocity while the second group, the resonant electrons, consists of all electrons with velocities near the wave velocity. It is assumed that initially the main plasma has a wave on it while the resonant particles are undisturbed. It is shown that equating the gain in energy of the resonant particles to the loss in energy of the wave gives the correct Landau damping. Only first-order quantities are used in the analysis so that particle trapping which is a nonlinear effect is not involved. The validity of arguments which attribute Landau damping to particle trapping is discussed. The breakdown of the linearized theory and the Galilean invariance of the damping are also investigated.
Equilibrium Ambipolar Potentials in a Mirror Machine
Authors: Post Richard F.
Published: December 2004

A plasma confined in a mirror machine can be expected to develop an electrostatic potential with respect to its surroundings. This potential arises because of the intrinsically different rate of diffusion in velocity space of the electrons and ions. When the temperature of the confined electrons is comparable to or smaller than the ion temperature, the potential will be positive, and will vary within the plasma. The variation of plasma potential with position in a mirror machine is calculated for conditions where: (a) the electron temperature is small compared to ion temperature and (b) electrons and ions are separately in diffusion equilibrium with the mirror losses. It is shown in an example that the plasma potential tends to concentrate near the mirrors, and that its variation, between the mirrors, is relatively insensitive to the total potential. Applications and extensions of the calculations are suggested.
On the Mechanism of Exploding Wires
Authors: Nash C. P. , McMillan W. G.
Published: December 2004

Experimental measurements are given for the energy input and shock wave arrival times for 10-cm No. 40 Cu wires exploded in air at an initial voltage of 9.25 kv. Two shocks in air are observed, one for each pulse before and after the dark pause. Pause duration measurements are also reported for wire explosions in gaseous He, N2, O2, Ar and CClF3 at l atm. Semiquantitative theoretical explanations are proposed for the increase in wire resistance which terminates the first current surge, and for the elapsed time (pause duration) before the vapor density of the expanding wire material declines sufficiently for reignition of the discharge.
Electromagnetic Diffusion into a Cylindrical Plasma Column during the Early Stages of Pinch Formation
Authors: Neuringer Joseph L. , Kraus Lester , Malamud Herbert
Published: December 2004

The diffusion of electromagnetic energy into a cylindrical plasma column due to the discharge of the energy stored in a capacitor is formulated taking into account the effects of the capacitance and inductance of the discharge circuit. The discharge circuit reflects the linear pinch geometry in that the energy source is a charged condenser and the return lead is a perfectly conducting cylindrical shell concentric with and surrounding the plasma column. The plasma properties enter the formulation through an extended Ohm's law which includes the time rate of change of current density. Under the assumption that changes in the ionization density and collision frequency may be neglected, Maxwell's equations lead to a third-order linear partial differential equation for the diffusion current. An exact solution is obtained by Laplace transform techniques using appropriate initial and boundary conditions which take into account the finite external circuitry. The spatial and temporal behavior of the current density distribution as functions of the parameters which characterize both the circuit and the plasma are discussed and compared with that of an ordinary conductor obeying the simple Ohm's law.
Rayleigh-Taylor Instability in a Stabilized Linear Pinch Tube
Authors: Albares D. J. , Krall N. A. , Oxley C. L.
Published: December 2004

Kerr cell photographs through a mesh anode have shown growing flute patterns on the interior luminous surface of the plasma cylinder. These appeared when the pressure of the enclosed axial field reversed the initial inward acceleration, as is expected for the accelerational hydromagnetic analog of the Rayleigh-Taylor instability. The measured growth rates ranged from about one-half to the full value predicted by simple theory. This agreement extended over a range of operational tube conditions. As predicted, application of an interior stabilizing field from a central wire erased the visible fluting.
Two-Fluid Model for the Structure of Neutral Shock Waves
Authors: Ziering S. , Ek F. , Koch P.
Published: December 2004

Recent measurements indicate that the thickness of weak and moderate strength shocks (M < 2) is given accurately by the Navier-Stokes equations, whereas there is good reason to believe that the bimodal theory of Mott-Smith is a better description for strong shocks. It is therefore desirable to develop a theory that can account for shock structure at both large and small Mach number. Results of a promising two-fluid theory by Glansdorff are recomputed and the formulation is criticized. A modified two-fluid approach is developed, employing moments of the respective Boltzmann equations for each fluid, and employing an intermediate Maxwellian distribution function with a mean flow velocity and temperature at the center of the shock to account for irreversible particle transfer between the two fluids. Numerical solutions for rigid-sphere and inverse fifth molecules are given, and comparisons with other solutions and experimental data are made. The results are in substantial agreement with requirements at both large and small Mach number.
Magnetohydrodynamic Shock Structure without Collisions
Authors: Morawetz Cathleen S.
Published: December 2004

The internal structure of a magnetohydrodynamic shock is examined under the condition that there are no collisions among the plasma particles. The equations to be solved are the collisionless, steady Boltzmann equations for ions and electrons coupled with Maxwell's equation for the fields (a self-consistent system). There is one space variable x and all quantities are prescribed constant as x = − ∞. Under appropriate conditions at − ∞, e.g., no transverse magnetic field, low ion pressure, and Alfvén-Mach number roughly less than 2, the state at + ∞ has oscillating fields, density, etc. The length scale is a mean phase length. Thus a change of state is possible without collisions.

The theory is based on an asymptotic development in the ion-to-electron mass ratio and is valid over distances that are comparable to or even large compared to the wavelength of the oscillation but small compared to the ion Larmor radius. The electrons are adiabatic.