Search Results - (Author, Cooperation:H. Herrmann)

2018-04-06

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Lymphoid Neoplasia

2013-05-11

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Aerosols ; Atmosphere/*chemistry ; Catalysis ; *Climate ; *Dust ; Minerals/chemistry ; Oxidation-Reduction ; Sulfur Dioxide/*chemistry ; Transition Elements

2011-08-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Acetylation ; Animals ; Azepines/pharmacology ; Cell Differentiation ; Cell Line, Tumor ; Cell Proliferation ; Chromatin/metabolism ; Disease Progression ; Epigenesis, Genetic/genetics ; Gene Expression Regulation, Neoplastic ; Genes, myc/genetics ; Histones/metabolism ; Humans ; Leukemia, Myeloid, Acute/*drug therapy/*genetics/pathology ; Mice ; Neoplasm Transplantation ; Neoplastic Stem Cells/drug effects/pathology ; Nuclear Proteins/antagonists & inhibitors/biosynthesis/genetics/*metabolism ; *RNA Interference ; RNA, Small Interfering/genetics ; Transcription Factors/antagonists & inhibitors/biosynthesis/genetics/*metabolism ; Triazoles/pharmacology

1089-7674

AIP Digital Archive

Physics

The atmospheric pressure plasma jet (APPJ) [A. Schütze et al., IEEE Trans. Plasma Sci. 26, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz rf. While passing through the plasma, the feedgas becomes excited, dissociated or ionized by electron impact. Once the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains neutral metastable species (e.g., O2*, He*) and radicals (e.g., O, OH). This reactive effluent has been shown to be an effective neutralizer of surrogates for anthrax spores and mustard blister agent. Unlike conventional wet decontamination methods, the plasma effluent does not cause corrosion and it does not destroy wiring, electronics, or most plastics, making it highly suitable for decontamination of sensitive equipment and interior spaces. Furthermore, the reactive species in the effluent rapidly degrade into harmless products leaving no lingering residue or harmful by-products. © 1999 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium–tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario. © 1996 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Wall conditioning in the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] by injection of lithium pellets into the plasma has resulted in large improvements in deuterium–tritium fusion power production (up to 10.7 MW), the Lawson triple product (up to 1021 m−3 s keV), and energy confinement time (up to 330 ms). The maximum plasma current for access to high-performance supershots has been increased from 1.9 to 2.7 MA, leading to stable operation at plasma stored energy values greater than 5 MJ. The amount of lithium on the limiter and the effectiveness of its action are maximized through (1) distributing the Li over the limiter surface by injection of four Li pellets into Ohmic plasmas of increasing major and minor radius, and (2) injection of four Li pellets into the Ohmic phase of supershot discharges before neutral-beam heating is begun. © 1996 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

In the Tokamak Fusion Test Reactor (TFTR) [International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Wurzburg, Paper No. A-2-2 (International Atomic Energy Agency, Vienna, 1993)] there have been at least three types of anomalous loss of alpha-like deuterium–deuterium (D–D) fusion products: (1) a magnetohydrodynamic (MHD)-induced loss of D–D fusion products correlated with Mirnov and fishbone-type oscillations and sawtooth crashes, (2) a slow "delayed'' loss of partially thermalized D–D fusion products occurring without large MHD activity, and (3) ion cyclotron resonance heating (ICRH)-induced loss of D–D fusion products ions observed during direct electron heating experiments, and possibly also during 3He minority heating. In this paper each of these will be reviewed, concentrating on those due to MHD activity, which are the largest of these anomalous losses. The experimental results are compared with numerical models of various fusion product transport mechanisms.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

In the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] a substantial improvement in fusion performance has been realized by combining the enhanced confinement due to tritium fueling with the enhanced confinement due to extensive conditioning of the limiter with lithium. This combination has resulted in not only significantly higher global energy confinement times than have previously been obtained in high current supershots, but also in the highest central ratio of thermonuclear fusion output power to input power observed to date. © 1995 American Institute of Physics.

Electronic Resource

1089-7682

AIP Digital Archive

Physics

When dissipative particles are left alone, their fluctuation energy decays due to collisional interactions, clusters build up and grow with time until the system size is reached. When the effective dissipation is strong enough, this may lead to the "inelastic collapse," i.e., the divergence of the collision frequency of some particles. The cluster growth is an interesting physical phenomenon, whereas the inelastic collapse is an intrinsic effect of the inelastic hard sphere (IHS) model used to study the cluster growth—involving only a negligible number of particles in the system. Here, we extend the IHS model by introducing an elastic contact energy and the related contact duration tc. This avoids the inelastic collapse and allows to examine the long-time behavior of the system. For a quantitative description of the cluster growth, we propose a burning-like algorithm in continuous space, that readily identifies all particles that belong to the same cluster. The criterion for this is here chosen to be only the particle distance. With this method we identify three regimes of behavior. First, for short times a homogeneous cooling state (HCS) exists, where a mean-field theory works nicely, and the clusters are tiny and grow very slowly. Second, at a certain time which depends on the system's properties, cluster growth starts and the clusters increase in size and mass until, in the third regime, the system size is reached and most of the particles are collected in one huge cluster. © 1999 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Gas breakdown is studied in an atmospheric pressure rf capacitive plasma source developed for materials applications. At a rf frequency of 13.56 MHz, breakdown voltage is largely a function of the product of the pressure and the discharge gap spacing, approximating the Paschen curve. However, breakdown voltage varies substantially with rf frequency due to a change in the electron loss mechanism. A large increase in breakdown voltage is observed when argon, oxygen, or nitrogen is added to helium despite their lower ionization potential. Discussion is given for optimal breakdown conditions at atmospheric pressure. © 2001 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Discharge phenomena of a nonthermal atmospheric pressure plasma source have been studied. An atmospheric pressure plasma jet (APPJ) operates using rf power and produces a stable homogeneous discharge at atmospheric pressure. After breakdown, the APPJ operation is divided into two regimes, a "normal" operating mode when the discharge is stable and homogeneous, and a "failure" mode when the discharge converts into a filamentary arc. Current and voltage (I–V) characteristics and spatially resolved emission intensity profiles have been measured during the normal operating mode. These measurements show that the APPJ produces an alpha (α) mode rf capacitive discharge. Based upon a dimensional analysis using the observed I–V characteristics, a rough estimate is made for plasma density of 3×1011 cm−3 and an electron temperature of 2 eV. In addition, the gas temperature of 120 °C has been spectroscopically measured inside the discharge. These plasma parameters indicate that the APPJ shows promise for various materials applications as it can produce substantial amounts of reactive species and avoid thermal damages, while having the advantage of atmospheric pressure operation. © 2001 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A new foil deposition alpha collector sample probe has been developed for TFTR's D-T phase. D-T fusion produced alpha particles escaping from the plasma are implanted in nickel foils located in a series of collimating ports on the detector. The nickel foils are removed from the tokamak after exposure to one or more plasma discharges and analyzed for helium content. This detector is intended to provide improved alpha particle energy resolution and pitch angle coverage over existing lost alpha detectors, and to provide an absolutely calibrated cross-check with these detectors. The ability to resolve between separate energy components of alpha particle loss is estimated to be ∼20%. A full 360° of pitch angle coverage is provided for by eight channels having an acceptance range of ∼53° per channel. These detectors will be useful in characterizing classical and anomalous alpha losses and any collective alpha instabilities that may be excited during the D-T campaign of TFTR. © 1995 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Nondestructive room temperature photoluminescence of the InGaAs channel of a pseudomorphic high electron mobility transistor is presented as a function of bias applied to a semitransparent gate. The channel electron sheet concentration is evaluated via line-shape fitting of the photolumin- escence spectrum. Excellent agreement with electrically derived values of the channel charge was found. Information on the symmetry of the channel potential is also provided by the results of the photoluminescence line-shape fit.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

The electric field distribution in microwave cavities is commonly measured by frequency perturbation techniques. For many cavity modes which are important in accelerator applications, the standard bead-pulling technique cannot provide adequate discrimination between fields parallel and perpendicular to the particle trajectory, leading to inaccurate and ambiguous results. A method is described which substantially increases the directivity of the measurements. The method has been successfully used to determine the accelerator-related cavity parameters at frequencies up to three times the fundamental resonant frequency.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A poloidal array of MeV ion loss probes previously used to measure DD fusion product loss has been upgraded to measure the loss of alpha particles from DT plasmas in the Tokamak Fusion Test Reactor (TFTR). The following improvements to the system have been made in preparation for the use of tritium in TFTR: (1) relocation of detectors to a neutron-shielded enclosure in the basement to reduce neutron-induced background signals; (2) replacement of ZnS:Cu (P31) scintillators in the probes with the Y3Al5O12:Ce (P46) variety to minimize damage and assure linearity at the fluxes anticipated from DT plasmas; and (3) shielding of the fiber optic bundles which carry the light from the probes to the detectors to reduce neutron- and gamma-induced light within them. In addition to the above preparations, the probes have been absolutely calibrated for alpha particles by using the Van de Graaf accelerator at Los Alamos National Laboratory. Alpha particle losses from DT plasmas have been observed, and losses at the detector 90° below the midplane are consistent with first orbit loss. © 1995 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The often-observed extreme asymmetry in the sidelobe spectra of integrated acousto-optic filters exacerbates cross talk between wavelength-multiplexed optical channels. We explain the source of this asymmetry in terms of a systematic even-order variation of the effective waveguide birefringence as a function of distance from the device center. Calculations show what degree of nonuniformity in Ti-stripe thickness, width, or diffusion temperature are required to account for typical asymmetries. We describe two experiments in which temperature gradients were applied to low-power acousto-optic filters in order to induce sidelobe suppression on either side of the optical transmission function, while greatly enhancing sidelobes on the opposite side.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

An atmospheric pressure plasma source operated by radio frequency power has been developed. This source produces a unique discharge that is volumetric and homogeneous at atmospheric pressure with a gas temperature below 300 °C. It also produces a large quantity of oxygen atoms, ∼5×1015 cm−3, which has important value for materials applications. A theoretical model shows electron densities of 0.2–2×1011 cm−3 and characteristic electron energies of 2–4 eV for helium discharges at a power level of 3–30 W cm−3. © 2000 American Institute of Physics.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Inhibition of photosynthesis after exposure to solar radiation was investigated in the marine green alga Dunaliella salina by monitoring photosynthetic optimal quantum yield Fv/Fm and efficiency of oxygen production. Samples were exposed to solar radiation in Ancient Korinth, Greece (37°58′ N, 23°0′ E) in August 1994. Within 30 min, Fv/Fm and efficiency of oxygen production decreased with similar kinetics with increasing exposure time. The inhibition, however, diminished when ultraviolet radiation was progressively excluded by means of colour filter glasses. Samples exposed for 3 h showed complete or partial recovery of photosynthesis, with almost the same rate under all irradition conditions. The fit of the experimental data with an analytical model describing inhibition of photosynthesis as a function of a linear combination of the photon fluence in the UV-B, UV-A and PAR allows one to estimate the relative mean effectiveness for inhibition by the three spectral ranges [about 2 × 10−4, 4 × 10−6 and 2 × 10−7 (μmol photons m−2)−1 for UV-B, UV-A and PAR, respectively].

Electronic Resource

1600-0536

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Three patients with occupational contact dermatitis due to Arnica longifolia Eaton and Arnica montana L. are reported. During cultivation, harvesting of the flower heads, chemical investigation of the sesquiterpene lactone constituents and preparation of therapeutic tinctures, they had frequent contact with the plant materials. Patch tests with the two sesquiterpene lactones carabron and helenalin, isolated during investigation from A. lungifolia Eaton, were positive in all three patients, though the second patient had never shown visible allergic reactions of the skin. Sensitization experiments with carabron in five guinea pigs were successful.The investigation results revealed that carabron, helenalin and the acetyl derivative of helenalin must be considered as the sensitizers of A. longifolia, and helenalin acetate and properly arnifolin as sensitizeis of A. motana.Studies on cross reactivity in the sensitized animals with six related sesquiterpene lactones showed that only those compounds gave a positive test response which contain an α-methylene γ-lactone group. Cross reactions were obtained with a crude extract of Chrysanthemum indicum L.The case reports supported by the patch test and investigation results demonstrate that persons handling a new drug from the Compositae family run a risk of developing an allergy after intensive contact with the plant and its constituents.

Electronic Resource