Search Results - (Author, Cooperation:D. Brenner)

2012-07-06

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Aging ; Animals ; Bone Marrow/pathology ; Cell Lineage ; CpG Islands/genetics ; DNA Methylation ; Disease Models, Animal ; Epigenesis, Genetic/*genetics ; Female ; Gene Knock-In Techniques ; Glioma/pathology ; Hematopoiesis ; Hematopoietic Stem Cells/*cytology/metabolism ; Histones/metabolism ; Humans ; Isocitrate Dehydrogenase/*genetics/*metabolism ; Leukemia, Myeloid, Acute/genetics ; Male ; Mice ; Mutant Proteins/genetics/*metabolism ; Mutation/*genetics ; Myeloid Cells/cytology/metabolism ; Spleen/pathology

2018-01-18

The American Society for Microbiology (ASM)

0022-538X

1098-5514

Medicine

2018-02-09

BMJ Publishing Group

0017-5749

1468-3288

Medicine

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A design is given of a laser ion source for the 4.2 MV Van de Graaff accelerator at the Columbia University Radiological Research Accelerator Facility (RARAF). The source has been designed with application in mind for the RARAF single-particle single-cell microbeam, though it will also be used for broad-beam irradiations. The operating principle, laser ablation, can produce heavy ions with high charge states so that their energies will be high enough to provide sufficient range—at least 20 μm—for irradiating cells on a thin surface at atmospheric pressure. The laser ion source being implemented at RARAF is based on the laser operated ion source used by Hughes at the University of Arkansas and consists of three main components: laser generator, source vacuum chamber, and spherical electrostatic analyzer. © 2002 American Institute of Physics.

Electronic Resource

0020-1693

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0957-4166

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0301-0104

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource

1432-0649

33 ; 42.10

Springer Online Journal Archives 1860-2000

Physics

Electronic Resource

0163-1047

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Psychology

Electronic Resource

1572-9591

Palladium-deuterides ; D2 ; clusters ; density-functional calculations

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract Cold fusion enhanced by chemical confinement of deuterons has been suggested as an explanation of recent reports of the production of neutrons in electrochemically-generated palladium deuterides. To test this suggestion local-density-functional cluster calculations were used to study the coulomb barrier between two deuterons within the octahedral cage in crystalline palladium. The calculated repulsive forces were always greater than the corresponding forces between deuterons in molecular D2. These results imply that the room temperature fusion rate at this site is negligible.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] SIR-Mills et al.' present data to support the view that a dose of 10~5 Gy of 14.4-keV X-rays can ablate a population of malignant cells containing 57Fe(III) o bleomycin. They suggest that such a regime may have the potential for the low-dose sterilization of superficial human tumours. This is ...

Electronic Resource

0392-6737

Biomagnetism (including magnetocardiography) ; Superconducting devices ; superconducting magnets

Springer Online Journal Archives 1860-2000

Physics

Riassunto Si è studiato lo spettro del rumore di un gradiometro superconduttore a derivata secon da in un agglomerato urbano. I dati sono stati ottenuti dal gradiometro con tre accelerometri ortogonali e un magnetometro a flussometro elettronico triassiale attaccato al dewar. Questi dati sono stati analizzati usando tecniche di elaborazione dei segnali, soprattutto un cancellatore adattativo di rumori, per ridurre i rumori nei dati del gradiometro. I risultati mostrano qui che il rumore dell’esterno e/o il rumore del movimento del dewar possono essere ridotti di 40 dB in potenza di rumore. Si è anche mostrato che, nel caso di basso rapporto segnale-rumore (S/N∼1), può essere estratta un’onda sunusoidale di 10 Hz. Questa tecnica non solo promette riduzione dei rumori, ma ha anche lo scopo d’identificare i segnali di rumore che potrebbero essere veramente considerati parte del responso evocato. L’analisi dei dati che contengono i responsi evocati è ora in corso.

Summary The noise spectrum of a superconducting second-derivative gradiometer has been investigated in an urban environment. Data have been acquired from the gradiometer with three orthogonal accelerometers and a triaxial fluxgate magnetometer attached to the dewar. These data have been analyzed by using signal processing techniques, primarily an adaptive noise canceller, to reduce noise in the gradiometer data. Results shown here indicate that the environmental noise and/or the dewar motion noise can be reduced as much as 40 dB in noise power. It is also shown, in the case of poor signal-to-noise ratio (S/N∼1), that a 10 Hz sine wave can be extracted. This technique not only shows promise for noise reduction, but also aids in the identification of noise signals which might be misconstrued as part of the evoked response. Analysis of data containing evoked response is now underway.

Electronic Resource

1432-1106

Magnetoencephalography ; Evoked fields ; Evoked potentials ; Steady state responses ; Audition

Springer Online Journal Archives 1860-2000

Medicine

Summary Neuromagnetic studies show that the location of cortical activity evoked by modulated tones and by click stimuli in the steady state paradigm can be determined non-invasively with a precision of a few millimeters. The progression of locations for tones of increasing frequency establish an orderly tonotopic map in which the distance along the cortex varies as the logarithm of the frequency. The active region responding to clicks lies at a position that is consistent with this map if the stimulus is characterized by the frequency of the peak of its power spectrum. A latency of about 50 ms observed for the response to clicks is in close correspondance with a strong component of the transient response to an isolated click reported in the literature. Monaural stimulation of the ear contralateral to the hemisphere being monitored produces a latency which is about 8 ms shorter than stimulation of the ipsilateral ear, in agreement with previous studies of transient responses. The amplitudes of the responses for binaurally presented clicks for sleeping subjects is substantially diminished for repetition rates above 20 Hz but is enhanced for lower rates.

Electronic Resource

1432-2099

Springer Online Journal Archives 1860-2000

Biology

Physics

Summary Within the Theory of Dual Radiation Action, the heuristically useful function,γ(ϰ), that two energy depositions, a distanceϰ apart, will result in observable damage can be written in terms of two more fundamental quantities: One,s(ϰ), describes the structure of the sensitive matrix of the cell. The other,g(ϰ), describes the probability that two elementary injuries, a distanceϰ apart, will combine to produce observable damage. A priori, the known enhancement exhibited byy(ϰ) at nanometer separations could be due to an enhancement ofs(ϰ),g(ϰ) or both. For the endpoint of chromatid exchanges in Chinese hamster cells,γ(ϰ) has been evaluated from experimental data ands(ϰ) from a model system. From theseg(ϰ) has been estimated and is roughly constant below ∼ 1 µm, decreasing rapidly at larger separations. Thus the enhanced short-range effect appears to be a function more of the spatial characteristics of the target rather than the probability of damage interaction.

Electronic Resource

1432-2099

Springer Online Journal Archives 1860-2000

Biology

Physics

Abstract  DNA double-strand breaks (DSBs) produced by densely ionizing radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. Stochastic DSB clustering at large scales, from 〉100 Mbp down to 〈0.01 Mbp, is modeled using computer simulations and analytic equations. A random-walk, coarse-grained polymer model for chromatin is combined with a simple track structure model in Monte Carlo software called DNAbreak and is applied to data on alpha-particle irradiation of V-79 cells. The chromatin model neglects molecular details but systematically incorporates an increase in average spatial separation between two DNA loci as the number of base-pairs between the loci increases. Fragment-size distributions obtained using DNAbreak match data on large fragments about as well as distributions previously obtained with a less mechanistic approach. Dose-response relations, linear at small doses of high linear energy transfer (LET) radiation, are obtained. They are found to be non-linear when the dose becomes so large that there is a significant probability of overlapping or close juxtaposition, along one chromosome, for different DSB clusters from different tracks. The non-linearity is more evident for large fragments than for small. The DNAbreak results furnish an example of the RLC (randomly located clusters) analytic formalism, which generalizes the broken-stick fragment-size distribution of the random-breakage model that is often applied to low-LET data.

Electronic Resource

1573-0972

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

0020-7608

Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Molecular dynamics simulations are used to study hypervelocity impacts of an ultrathin flyer plate with a semi-infinite two-dimensional model diatomic molecular solid. We show that these hypervelocity impacts can produce a dissociative phase transition from a molecular to a close-packed solid in the target material. We also show that hypervelocity impacts of ultrathin plates can produce extensive chemical reactions leading to a detonation accompanied by a phase transition in an energetic version of the model. © 1994 John Wiley & Sons, Inc.

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Electronic Resource