Communications Biophysics

COntains reports on six research projects.National Institutes of Health (Grant 2 P01 MH-04737-06)National Institutes of Health (Grant 5 ROl NB-05462-02)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GK-835)National Aeronautics and Space Administration (Grant NsG-496

Padronização de métodos para análise granulométrica no Brasil.

bitstream/item/96926/1/ComTec-66-Analise-Granulometrica.pd

Antarctic temperature changes during the last millennium: evaluation of simulations and reconstructions

Temperature changes in Antarctica over the last millennium are investigated using proxy records, a set of simulations driven by natural and anthropogenic forcings and one simulation with data assimilation. Over Antarctica, a long term cooling trend in annual mean is simulated during the period 1000–1850. The main contributor to this cooling trend is the volcanic forcing, astronomical forcing playing a dominant role at seasonal timescale. Since 1850, all the models produce an Antarctic warming in response to the increase in greenhouse gas concentrations. We present a composite of Antarctic temperature, calculated by averaging seven temperature records derived from isotope measurements in ice cores. This simple approach is supported by the coherency displayed between model results at these data grid points and Antarctic mean temperature. The composite shows a weak multi-centennial cooling trend during the pre-industrial period and a warming after 1850 that is broadly consistent with model results. In both data and simulations, large regional variations are superimposed on this common signal, at decadal to centennial timescales. The model results appear spatially more consistent than ice core records. We conclude that more records are needed to resolve the complex spatial distribution of Antarctic temperature variations during the last millennium

Communication Biophysics

Contains reports on five research projects.National Institutes of Health (Grant 5 RO1 NB-05462-02)National Aeronautics and Space Administration (Grant NsG-496)National Science Foundation (Grant GP-2495)National Institutes of Health (Grant MH-04737-05

Communications Biophysics

Contains research objectives, summary of research and reports on three research projects.National Institutes of Health (Grant 5 PO1 GM14940-06)National Institutes of Health (Grant 2 TOl GM01555-06)National Institutes of Health (Grant 1 ROl NS10737-01)National Aeronautics and Space Administration (Grant NGL 22-009-304)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300B-D Electrodyne Division, Becton Dickinson and Company (Grant)Boston City Hospital Purchase Order 1176-21-33

Communications Biophysics

Contains research objectives and summary of research on five research projects, with ten sub-topics.National Institutes of Health (Grant 1 RO1 NS10916-01)National Institutes of Health (Grant 5 RO1 NS11000-03)National Institutes of Health (Grant 1 RO1 NS11153-01)Harvard-M.I.T. Rehabilitation Engineering CenterU. S. Department of Health, Education, and Welfare (Grant 23-P-55854)National Institutes of Health (Grant 1 RO1 NS11680-01)National Institutes of Health (Grant 5 ROI NS11080-02)M.I.T. Health Sciences FundNational Aeronautics and Space Administration (Grant NSG-2032)National Institutes of Health (Grant 5 TO1 GM01555-09)Massachusetts General Hospital Purchase Order F63853Boston City Hospital Purchase Order 4338-7543

Carbenic nitrile imines: Properties and reactivity

Structures and properties of nitrile imines were investigated computationally at B3LYP and CCSD(T) levels. Whereas NBO analysis at the B3LYP DFT level invariably predicts a propargylic electronic structure, CCSD(T) calculations permit a clear distinction between propargylic, allenic, and carbenic structures. Nitrile imines with strong IR absorptions above ca. 2150 cm-1 have propargylic structures with a CN triple bond (RCNNSiMe 3 and R2BCNNBR2), and those with IR absorptions below ca. 2150 cm-1 are allenic (HCNNH, PhCNNH, and HCNNPh). Nitrile imines lacking significant cumulenic IR absorptions at 1900-2200 cm -1 are carbenic (R-(C:)-N=N-R′). Electronegative but lone pair-donating groups NR2, OR, and F stabilize the carbenic form of nitrile imines in the same way they stabilize "normal" singlet carbenes, including N-heterocyclic carbenes. NBO analyses at the CCSD(T) level confirm the classification into propargylic, allenic, and carbenic reactivity types. Carbenic nitrile imines are predicted to form azoketenes 21 with CO, to form [2+2] and [2+4] cycloadducts and borane adducts, and to cyclize to 1H-diazirenes of the type 24 in mildly exothermic reactions with activation energies in the range 29-38 kcal/mol. Such reactions will be readily accessible photochemically and thermally, e.g., under the conditions of matrix photolysis and flash vacuum thermolysis

Communications Biophysics

Contains research objectives, summary of research and reports on two research project.National Institutes of Health (Grant 5 PO1 GM14940-03)National Institutes of Health (Grant 5 TO1 GM01555-03)National Aeronautics and Space Administration (Grant NGL 22-009-304

Communications Biophysics

Contains research objectives, summary of research and reports on four research projects.National Institutes of Health (Grant 5 P01 GM14940-05)National Institutes of Health (Grant 5 TOl GM01555-05)National Aeronautics and Space Administration (Grant NGL 22-009-304)B-D ElectrodyneBoston City Hospital Purchase Order 1065