Surface state lifetime in quasi-one-dimensional oxygen stripes on Cu(1 1 0)

Scanning tunneling spectroscopy data on the lifetime and bottom energy of a surface state band in quasi-one-dimensional stripes are presented as a function of stripe width. The adsorbate system Cu(1 1 0)-p(2 × 1)O has been used to prepare a two-dimensional adsorbate layer and almost defect free quasi-one-dimensional stripes with a width of 3-15 CuO rows, respectively. The onset of an unoccupied surface state band (at 0.56 eV above Fermi-energy on the fully covered surface) has been analyzed with respect to the quasi-particle lifetime at the crossover from two to one dimension. A drastic increase of the onset-width with decreasing stripe width is observed. It can be explained by a decrease of quasi-particle lifetime using a Fabry-Pérot-like model. We obtain a reduction of lifetime from 37 ± 8 fs on the two-dimensional adsorbate layer to 5 ± 1 fs on a three CuO rows wide stripe.     

Dual multilevel optimization

We study the structure of dual optimization problems associated with linear constraints, bounds on the variables, and separable cost. We show how the separability of the dual cost function is related to the sparsity structure of the linear equations. As a result, techniques for ordering sparse matrices based on nested dissection or graph partitioning can be used to decompose a dual optimization problem into independent subproblems that could be solved in parallel. The performance of a multilevel implementation of the Dual Active Set algorithm is compared with CPLEX Simplex and Barrier codes using Netlib linear programming test problems.      

Pikrins?ure in ihrem Verhalten zu den Alkalo?den

Ohne Zusammenfassung     

Spin labelling of human erythrocytes with nitroxide radicals

Summary Human erythrocytes were labelled with nitroxide, the spin label SYNVAR 101, under various experimental conditions. A study was made of the influence of antireductants on the labelling efficiency and the kinetics of the radical decay during the labelling process. The antireductant hydrogen peroxide was effective in suppressing the decay, whereas ferricyanide was not very effective in this role. The nitroxide radical concentration in a nondialyzed plasma suspension of spin-labelled erythrocytes continuously decayed exponentially with a time constant of 35 min. Nitroxide radicals in nondialyzed plasma exhibited a similar decay to a final residual value which was small relative to the initial concentration. Dialyzing the plasma raised the residual concentration to three quarters of the initial value without changing the decay time.

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Riassunto Eritrociti umani sono marcati con ossido di azoto, il marchio di spin SYNVAR 101, in varie condizioni sperimentali. Si è fatto uno studio dell’influenza degli agenti antiriducenti sulla capacità di marcare e sulla cinetica del decadimento dei radicali durante il processo di marcatura. Il perossido d’idrogeno antiriducente era efficacie nel sopprimere il decadimento, mentre il ferrocianuro non era molto efficacie in questo roulo. La concentrazione dei radicali dell’ossido di azoto in una sospensione di plasma non dializzato degli eritrociti marcati secondo lo spin decade continuamente in maniera esponenziale con una costante di tempo di 35 min. I radicali dell’ossido di azoto nel plasma non dializzato esibiscono un decadimento simile al valore residuo finale che era piccolo in relazione alla concentrazione iniziale. Dializzare il plasma aumenta la concentrazione residua a tre quarti del valore iniziale senza cambiare il tempo di decadimento.

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Резюме В различных эксрериментальных условиях метятся человеческие эритроциты с окисью азота. Исследуются влияния антивосстановителя на эффективность нанесения метки и кинетику распада радикалов в процессе нанесения метки, Перекись водорода, как антивосстановитель, является эффективной для подавления распада, тогда как феррицианид не очень эффективен в этой. Концетрация радикалов окиси азота в суспензии недиализированной плазмы эритроцитов со спиновой меткой уменьшается эксоненциально с временной постоянной, равной 35 мин. Радикалы окиси азота в недиализированной плазме обнаруживают аналогичный распад, причем конечная остаточная величина концентрации оказывается малой по сравнений с начальной концентрацией. Диализация рлазмы увеличивает остаточную концентрацию до трех четвертых начальной без изменения времени распада.

     

A graph theoretic upper bound on the permanent of a nonnegative integer matrix. I

Let A be a fully indecomposable n×n matrix with nonnegative integer entries. Then the permanent of A is bounded above by 1+min{Π(c_i?1), Π(r_i?1)}, where c_i and r_i are the column and row sums of A. The inequality results from a bound on the number of disjoint cycle unions in an associated multigraph. This bound can improve via contractions.     

Far-infrared studies of microphase separation in sulfonated ionomers

Far-infrared spectra of a series of un-neutralized and neutralized lightly sulfonated polystyrenes with varying sulfonation levels have been investigated to seek spectroscopic evidence for microphase separation known to control the physical properties of these polymers. Broad, strong absorbance bands, not found in the spectrum of unmodified polystyrene, are observed in the spectra of the sulfonated analogs. The effects on the far-infrared spectra both of sulfonation level and of the mass and charge of the neutralizing cation are discussed in terms of cation motion and the formation of ion-rich domains.     

Identification of novel biomarker candidates by differential peptidomics analysis of cerebrospinal fluid in Alzheimer's disease

The objective of this work was the application of peptidomics technologies for the detection and identification of reliable and robust biomarkers for Alzheimer's disease (AD) contributing to facilitate and further improve the diagnosis of AD. Using a new method for the comprehensive and comparative profiling of peptides, the differential peptide display (DPD), 312 cerebrospinal fluid (CSF) samples from AD patients, cognitively unimpaired subjects and from patients suffering from other primary dementia disorders were analysed as four independent analytical sets. By combination with a cross validation procedure, candidates were selected from a total of more than 6,000 different peptide signals based on their discriminating power. Twelve candidates were identified using mass-spectrometric techniques as fragments of the possibly neuroprotective neuroendocrine protein VGF and another one as the complement factor C3 descendent C3f. The combination of peptide profiling and cross validation resulted in the detection of novel potential biomarkers with remarkable robustness and a close relation to AD pathophysiology.