Plasma heating by electric field compression.

Plasma heating by compression of electric fields is proposed. It is shown that periodic cycles of external compression followed by the free expansion of electric fields in the plasma cause irreversible, collisionless plasma heating and corresponding entropy generation. As a demonstration of general ideas and scalings, the heating is shown in the case of a dusty plasma, where electric fields are created due to the presence of charged dust. The method is expected to work in the cases of compression of low frequency or dc electric fields created by other methods. Applications to high power laser heating of plasmas using this scheme are discussed.

Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius.

Development of a novel surface assisted volume negative hydrogen ion source.

H- ion based neutral beam injector is a critical heating and current drive system in a fusion reactor. However, the present H- ion source configuration has limitations in terms of production, extraction, cesium (Cs) inventory and management. To overcome these limitations, a proof-of-principle experiment based on a novel concept regarding surface assisted volume H- ions production by sprinkling Cs coated tungsten (W) dust grains (low work function surface) into a hydrogen plasma is carried out. Four different diagnostics have been used to validate the concept. The H- ion fraction is estimated from (a) Langmuir probe diagnostic, (b) phase velocity of ion acoustic waves, (c) dust current and confirmed by the measurement of (d) Balmer line ratio. The measured H- ion fraction with respect to the plasma density for different discharge conditions varies from ~0.2 to 0.3 in presence of Cs coated W dust particles. The experimental results show good agreement with the theoretical estimation.

Real-time study of fast-electron transport inside dense hot plasmas.

We offer a method to study transport of fast electrons in dense hot media. The technique relies on temporal profiling of the laser induced magnetic fields and offers a unique capability to map the hot electron currents and their neutralization (or lack of it) by the return currents in the plasma. We report direct quantitative measurements of strong electric inhibition in insulators and turbulence induced anomalous stopping of hot electrons in conductors. The present technique can prove extremely important from the point of view of fast ignition scheme, which relies on the penetration of fast electrons into the fusion core.

Association of immunoreactive hepatocyte growth factor with poor survival in resectable non-small cell lung cancer.

We have shown previously that hepatocyte growth factor (HGF), which is produced by lung fibroblasts, is a potent mitogen and motogen for both normal and neoplastic bronchial epithelium, and that expression of the HGF receptor, the c-met proto-oncogene protein, is uniformly found in the human bronchial epithelium and in non-small cell lung carcinomas (NSCLCs; P. Singh-Kaw et al., Am. J. Physiol., 268: L1012-L1020, 1995). Yamashita et al. have reported an association of HGF with poor survival in invasive ductal carcinoma of the breast (Cancer Res., 54: 1630-1633, 1994). There are few prognostic markers for lung cancer, and the high recurrence rate for stage I lung cancer suggests the frequent presence of undetectable tumor burden in such patients. Criteria are needed to evaluate these patients for risk of recurrence. We have now evaluated whether HGF present in resectable lung tumors has prognostic significance. In this study, 56 primary NSCLCs, mainly adenocarcinomas, were examined for presence of HGF by quantitative Western blot. These tumors consisted of tissue from 34 stage I patients, 9 stage II patients, and 13 stage IIIa patients who underwent curative resection for primary NSCLC. Extracts of whole tumor tissue were analyzed after separation of proteins by electrophoresis and transfer of proteins to nitrocellulose membranes. Immunoreactive (ir)-HGF was visualized by reaction with a polyclonal anti-HGF antiserum and quantitated by densitometry. Lung tumor content of ir-HGF varied widely among individuals. Median ir-HGF content in tumor extracts was 15.3 ng/40 microg of tumor protein; mean ir-HGF was 27.2 ng/40 microg of tumor protein. The median and mean ir-HGF were both significantly higher in tumor tissue from patients who suffered a recurrence during the follow-up period compared with those with no evidence or residual disease; this was true of all patients (P = 0.0001) and stage I patients analyzed separately (P = 0.002). Analysis of survival curves indicated that ir-HGF levels higher than the median were associated with poor overall survival (P < 0.03). Univariate analysis showed three factors related to poor overall survival in this set of patients: ir-HGF, tumor (T) status (a measure of primary tumor size and extent), and age. Nodal (N) status and stage were only marginally related to overall survival, most likely because the majority of the patients in the study were stage I. N status, stage, and T status were related to disease-free survival, however. Multivariate Cox analysis showed that ir-HGF, T status, and age independently had a negative impact on overall survival. ir-HGF was a strong independent negative prognostic indicator (P = 0.0001) with a relative risk of 1.022 per unit of ir-HGF (ng/40 microg of protein). This demonstrates that, in this group of patients, the relative risk of ir-HGF content increased continuously as ir-HGF increased, and exceeded 10 at units of ir-HGF of 100 or more. In comparison, in this group of patients, the relative risk of a T status greater than 1 was 4.75 and that of age greater than 65 was 3.95. The combined negative effect of a T status greater than 1 and elevated ir-HGF on survival was also highly pronounced (P < 0.005). In addition, elevated ir-HGF had a negative impact on survival when patients were stratified by stage or N status. Stage I patients with high ir-HGF values had a worse outcome than stage II or stage IIIa patients with low ir-HGF values. Elevated ir-HGF was strongly associated with poor outcome for resectable NSCLC patients as a group, and also identified stage I patients with poor outcome, indicating that it could be a useful indicator of risk of relapse and death in patients who have early lung cancer. The impact of elevated ir-HGF was especially prominent in patients whose T status was greater than 1, suggesting that patients with both risk factors who are stag

Three-dimensional particle-in-cell simulations of energetic electron generation and transport with relativistic laser pulses in overdense plasmas.

The interaction of relativistic laser light with overdense plasmas is studied by three-dimensional particle-in-cell simulations. Generation of layered current sheets and quasistatic magnetic fields is observed near the target surface owing to anisotropic laser filamentation and Weibel instabilities. Later these current sheets tear into filaments that partially merge with each other to form isolated magnetic channels penetrating into the dense plasmas. It is found that fast electron energy flow is not only inside the magnetic channels but also it is widely distributed outside the channels. This is possible because of electron anomalous diffusion across self-generated magnetic fields. Consequently, the total hot electron current exceeds a few hundred kiloamperes and is much larger than the Alfvén current. Hence a considerable amount of energy flows towards the plasma core. Significant heating of the bulk plasma electrons is also observed.

Treatment of subtotal medial rectus myectomy complicating functional endoscopic sinus surgery.

During the past 2 decades, the introduction of functional endoscopic sinus surgery (FESS) has dramatically improved the treatment of sinus disorders. However, a variety of orbital complications have been reported, including optic nerve damage, hemorrhage, infection, compromise of the lacrimal drainage apparatus, and strabismus. At least 10 cases have reported damage to the medial rectus muscle. (1-8) Treatment options for such patients have been limited, especially because most are adults at risk for anterior segment ischemia after transposition of vertical rectus muscles. We describe 2 patients whose medial rectus myectomies were repaired by using nonabsorbable "hang-back" sutures in combination with a botulinum toxin (Botox) injection of the antagonist lateral rectus muscle. Good primary position alignment was achieved in both patients, and one patient was able to regain binocular function. We recommend this surgical approach, especially in patients at increased risk for anterior segment ischemia.

Performance of large electron energy filter in large volume plasma device.

This paper describes an in-house designed large Electron Energy Filter (EEF) utilized in the Large Volume Plasma Device (LVPD) [S. K. Mattoo, V. P. Anita, L. M. Awasthi, and G. Ravi, Rev. Sci. Instrum. 72, 3864 (2001)] to secure objectives of (a) removing the presence of remnant primary ionizing energetic electrons and the non-thermal electrons, (b) introducing a radial gradient in plasma electron temperature without greatly affecting the radial profile of plasma density, and (c) providing a control on the scale length of gradient in electron temperature. A set of 19 independent coils of EEF make a variable aspect ratio, rectangular solenoid producing a magnetic field (B(x)) of 100 G along its axis and transverse to the ambient axial field (B(z) ~ 6.2 G) of LVPD, when all its coils are used. Outside the EEF, magnetic field reduces rapidly to 1 G at a distance of 20 cm from the center of the solenoid on either side of target and source plasma. The EEF divides LVPD plasma into three distinct regions of source, EEF and target plasma. We report that the target plasma (n(e) ~ 2 × 10(11) cm(-3) and T(e) ~ 2 eV) has no detectable energetic electrons and the radial gradients in its electron temperature can be established with scale length between 50 and 600 cm by controlling EEF magnetic field. Our observations reveal that the role of the EEF magnetic field is manifested by the energy dependence of transverse electron transport and enhanced transport caused by the plasma turbulence in the EEF plasma.

Nonlinear wave propagation in strongly coupled dusty plasmas.

The nonlinear propagation of low-frequency waves in a strongly coupled dusty plasma medium is studied theoretically in the framework of the phenomenological generalized hydrodynamic (GH) model. A set of simplified model nonlinear equations are derived from the original nonlinear integrodifferential form of the GH model by employing an appropriate physical ansatz. Using standard perturbation techniques characteristic evolution equations for finite small amplitude waves are then obtained in various propagation regimes. The influence of viscoelastic properties arising from dust correlation contributions on the nature of nonlinear solutions is discussed. The modulational stability of dust acoustic waves to parallel perturbation is also examined and it is shown that dust compressibility contributions influenced by the Coulomb coupling effects introduce significant modification in the threshold and range of the instability domain.

Experimental study of nonlinear dust acoustic solitary waves in a dusty plasma.

The excitation and propagation of finite-amplitude low-frequency solitary waves are investigated in an argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Korteveg-de Vries equation.

Near-complete absorption of intense, ultrashort laser light by sub-lambda gratings.

We demonstrate near-100% light absorption and increased x-ray emission from dense plasmas created on solid surfaces with a periodic sub-lambda structure. The efficacy of the structure-induced surface plasmon resonance, responsible for enhanced absorption, is directly tested at the highest intensities to date (3 x 10{15} W cm{-2}) via systematic, correlated measurements of absorption and x-ray emission. An analytical grating model as well as 2D particle-in-cell simulations conclusively explain our observations. Our study offers a definite, quantitative way forward for optimizing and understanding the absorption process.

Mechanisms of edge-localized-mode mitigation by external-magnetic-field perturbations.

Particle and energy transport in the tokamak edge transport barrier is analyzed in the presence of magnetic field perturbations from external resonant coils. In recent experiments such coils have been verified as an effective tool for mitigation of the edge-localized modes of type I. The observed reduction of the density in plasmas of low collisionality is explained by the generation of charged particle flows along perturbed field lines. The increase of the electron and ion temperatures in the barrier is interpreted by the reduction of perpendicular neoclassical transport with decreasing density and nonlocality of parallel heat transport. The found modification of the pressure gradient implies the stabilization of ballooning-peeling MHD modes responsible for type I ELMs.

Laser-pulse-induced second-harmonic and hard x-ray emission: role of plasma-wave breaking.

We report time resolved measurements of second-harmonic and hard x rays emitted during the interaction of an intense laser pulse (10(16) W cm(-2), 100 fs) with a preplasma generated on a solid target. We observe that for a particular length scale the second harmonic goes through a minimum, while hard x-ray emission on the contrary maximizes. Theoretical or numerical modeling of this anticorrelation in terms of wave breaking of strongly driven electron plasma waves clearly brings out hitherto unexplored links between the physical mechanisms of second-harmonic generation and hard x-ray emission.

Commonly missed diagnoses in the childhood eye examination.

Early and accurate detection of eye disorders in children can present a challenge for family physicians. Visual acuity screening, preferably performed before four years of age, is essential for diagnosing amblyopia. Cover testing may disclose small-angle or intermittent strabismus. Leukocoria, which is detected with an ophthalmoscope, may indicate retinoblastoma or cataract. Children with glaucoma may have light sensitivity and enlargement of the cornea, and conjunctivitis that does not respond quickly to treatment may reflect more serious ocular inflammation. Children with serious eye injuries often present to the primary care physician. Nystagmus and many systemic conditions are associated with specific eye findings.

Experimental observations of transverse shear waves in strongly coupled dusty plasmas.

We report experimental observations of transverse shear waves in a three-dimensional dusty plasma that is in the strongly coupled fluid regime. These spontaneous oscillations occur when the ambient neutral pressure is reduced below a threshold value and the measured dispersion characteristics of these waves are found to be in good agreement with predictions of a viscoelastic theory of dusty plasmas.

Anomalous resistivity resulting from MeV-electron transport in overdense plasma.

Laser produced hot electron transport in an overdense plasma is studied by three-dimensional particle-in-cell simulations. Hot electron currents into the plasma generate neutralizing return currents in the cold plasma electrons, leading to a configuration which is unstable to electromagnetic Weibel and tearing instabilities. The resulting current filaments self-organize through a coalescence process finally settling into a single global current channel. The plasma return current experiences a strong anomalous resistivity due to diffusive flow of cold electrons in the magnetic perturbations. The resulting electrostatic field leads to an anomalously rapid stopping of fast MeV electrons (almost 3 orders of magnitude stronger than that through classical collisional effects).

Experimental observation of vertically polarized transverse dust-lattice wave propagating in a one-dimensional strongly coupled dust chain.

Externally driven, vertically polarized transverse dust-lattice waves were observed in a one-dimensional strongly coupled dust chain levitated in the plasma-sheath boundary of a dc argon plasma at low gas pressure around 5 mtorr. Real and imaginary parts of the complex wave number were measured in the experiments. The experimental result clearly shows that the observed transverse dust-lattice wave propagates as a backward wave, which is in good agreement with the theoretical prediction.

Pharmacodynamics of daptomycin in a murine thigh model of Staphylococcus aureus infection.

Daptomycin is a lipopeptide antibiotic with activity against gram-positive bacteria, including Staphylococcus aureus. We defined the pharmacodynamic parameters that determine the activity of daptomycin for S. aureus using in vitro methods and the Craig (W. A. Craig, J. Redington, and S. C. Ebert, J. Antimicrob. Chemother. 27[Suppl. C]:29--40, 1991) neutropenic mouse thigh infection model. In Mueller-Hinton broth, the MICs for three S. aureus isolates were 0.1 to 0.2 microg/ml. In mouse serum, the MICs were 1.0 microg/ml. The protein binding of daptomycin was 90 to 92.5% in mouse serum. Single-dose intraperitoneal (i.p.) pharmacokinetic studies with infected mice showed a linear relationship between dose versus the maximum concentration of drug in serum and dose versus the area under the concentration-time curve (AUC). The serum half-life of daptomycin in infected mice was approximately 1.8 h. In single-dose, dose-ranging studies using mice, daptomycin showed a dose-response effect described by an inhibitory sigmoid E(max) (maximum effect) curve (r = 0.974; P << 0.001). The density of S. aureus in untreated controls was 8.26 log(10) CFU/g, and the E(max) was 3.97 log(10) CFU/g. The 50% effective dose (ED(50)) was 3.7 mg/kg of body weight i.p. and the stasis dose was 7.1 mg/kg. Dose fractionation studies at schedules of Q6h, Q12h, and Q24h, for total 24-h ED(30), ED(60), and ED(80) doses of 2.5, 5.6, and 15 mg/kg i.p., showed no difference in effect at each total 24-h dose level by schedule, indicating that the AUC/MIC ratio is the dynamically linked variable.