230 research outputs found
Metastable anions of dinitrobenzene: resonances for electron attachment and kinetic energy release
Attachment of free, low-energy electrons to dinitrobenzene (DNB) in the gas phase leads to DNB as well as several fragment anions. DNB, (DNB-H), (DNB-NO), (DNB-2NO), and (DNB-NO(2)) are found to undergo metastable (unimolecular) dissociation. A rich pattern of resonances in the yield of these metastable reactions versus electron energy is observed; some resonances are highly isomer-specific. Most metastable reactions are accompanied by large average kinetic energy releases (KER) that range from 0.5 to 1.32 eV, typical of complex rearrangement reactions, but (1,3-DNB-H)(-) features a resonance with a KER of only 0.06 eV for loss of NO. (1,3-DNB-NO)(-) offers a rare example of a sequential metastable reaction, namely, loss of NO followed by loss of CO to yield C(5)H(4)O(-) with a large KER of 1.32 eV. The G4(MP2) method is applied to compute adiabatic electron affinities and reaction energies for several of the observed metastable channels. (C) 2010 American Institute of Physics. [doi:10.1063/1.3514931
Identification of Ventricular Tachycardia Using Intracardiac Electrograms: A Comparison of Unipolar Versus Bipolar Waveform Analysis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75535/1/j.1540-8159.1991.tb04091.x.pd
Ultra-low energy scattering of a He atom off a He dimer
We present a new, mathematically rigorous, method suitable for bound state
and scattering processes calculations for various three atomic or molecular
systems where the underlying forces are of a hard-core nature. We employed this
method to calculate the binding energies and the ultra-low energy scattering
phase shifts below as well as above the break-up threshold for the three
He-atom system. The method is proved to be highly successful and suitable for
solving the three-body bound state and scattering problem in configuration
space and thus it paves the way to study various three-atomic systems, and to
calculate important quantities such as the cross-sections, recombination rates
etc.Comment: LaTeX, RevTeX and amssymb styles, 7 pages (25 Kb), 3 table
Polytetrahedral Clusters
By studying the structures of clusters bound by a model potential that
favours polytetrahedral order, we find a previously unknown series of `magic
numbers' (i.e. sizes of special stability) whose polytetrahedral structures are
characterized by disclination networks that are analogous to hydrocarbons.Comment: 4 pages, 4 figure
New Tetrahedral Global Minimum for the 98-atom Lennard-Jones Cluster
A new atomic cluster structure corresponding to the global minimum of the
98-atom Lennard-Jones cluster has been found using a variant of the
basin-hopping global optimization algorithm. The new structure has an unusual
tetrahedral symmetry with an energy of -543.665361, which is 0.022404 lower
than the previous putative global minimum. The new LJ_98 structure is of
particular interest because its tetrahedral symmetry establishes it as one of
only three types of exceptions to the general pattern of icosahedral structural
motifs for optimal LJ microclusters. Similar to the other exceptions the global
minimum is difficult to find because it is at the bottom of a narrow funnel
which only becomes thermodynamically most stable at low temperature.Comment: 3 pages, 2 figures, revte
Molecular-dynamics simulations in systems of rare gases using Axilrod-Teller and exchange three-atom interactions
Sentinel node procedure in Ib cervical cancer: a preliminary series
The aim of this study was to determine the diagnostic accuracy and feasibility of sentinel lymph node (SLN) detection using a gamma probe in patients with Figo IB cervical cancer. Between January 1999 and September 2000, 14 patients with cervical cancer, planned for radical hysterectomy were eligible for the study. The day before radical hysterectomy we injected technetium99m-labelled nanocolloid in each quadrant of the cervix. Dynamic and static images were recorded using a gamma camera. SLNs were identified intraoperatively using a handheld gamma-detection probe. After resection of SLNs a standard radical hysterectomy with pelvic lymph node dissection was performed. Patients and tumour characteristics were compared with sentinel node detection and with final histopathological and immunohistochemical results. Scintigraphy showed focal uptake in 13 of the 14 patients. Intraoperatively we detected 26 sentinel nodes by gamma probe. In 8 of 13 patients, one or more sentinel nodes were identified unilaterally, in 5 women bilaterally. Histologically positive SLNs were found in only 1 patient. We did not find any false-negative SLN in our series. In conclusion identification of sentinel nodes in cervical cancer is feasible with preoperatively administered technetium99m-labelled nanocolloid. A larger series will be required to establish sentinel node detection in cervical cancer for further therapy concepts and planning. © 2001 Cancer Research Campaignhttp://www.bjcancer.co
Metastable anions of dinitrobenzene: Resonances for electron attachment and kinetic energy release
Endometrial stromal sarcoma: a population-based analysis
To determine independent prognostic factors for the survival of patients with endometrial stromal sarcoma (ESS), data were abstracted from the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute from 1988 to 2003. Kaplan–Meier and Cox proportional hazards models were used for analyses. Of 831 women diagnosed with ESS, the median age was 52 years (range: 17–96 years). In total, 59.9% had stage I, 5.1% stage II, 14.9% stage III, and 20.1% had stage IV disease. Overall, 13.0, 36.1, and 34.7% presented with grades 1, 2, and 3, respectively. Patients with stage I–II vs III–IV disease had 5 years DSS of 89.3% vs 50.3% (P<0.001) and those with grades 1, 2, and 3 cancers had survivals of 91.4, 95.4, and 42.1% (P<0.001). In multivariate analysis, older patients, black race, advanced stage, higher grade, lack of primary surgery, and nodal metastasis were independent prognostic factors for poorer survival. In younger women (<50 years) with stage I–II disease, ovarian-sparing procedures did not adversely impact survival (91.9 vs 96.2%; P=0.1). Age, race, primary surgery, stage, and grade are important prognostic factors for ESS. Excellent survival in patients with grade 1 and 2 disease of all stages supports the concept that these tumors are significantly different from grade 3 tumors. Ovarian-sparing surgeries may be considered in younger patients with early-stage disease
Analysis of three-body potentials in systems of rare-gas atoms: Axilrod-Teller versus three-atom exchange interactions
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