Hermitian operator method calculation in thepf-shell

Excitations inpf-shell nuclei that may be described by a one-body Hermitian operator are calculated. For the ground states highly correlated wave functions are used, which were obtained by means of the Generator Coordinate Method (GCM). It is found that the results of the Hermitian Operator Method (HOM) for the excited states are sometimes superior to those of the GCM, especially for the two-quasiparticle states in the N=28 nuclei⁵⁰Ti,⁵²Cr,⁵⁴Fe. Typically vibrational or quasi-rotational 4⁺ and 6⁺ states in^{46, 48}Ti,⁵⁰Cr are not well reproduced by the HOM, as expected. A good account for theB(E2) values of transitions to the ground state can be given for all nuclei. It is concluded that the HOM is quite useful as a supplementary calculation and as a check for complicated calculations like the GCM.     

Triplet state dipole moments of aminobenzonitriles

The triplet state dipole moments mu(T) of a series of 4-amino- and 3-aminobenzonitriles in cyclohexane, benzene, and 1,4-dioxane are recalculated from previously published [J. Phys. Chem. 1992, 96, 10809] time-resolved microwave conductivity data, on the basis of newly measured intersystem crossing yields. For 4-(dimethylamino)benzonitrile (DMABN), the following values are now determined for mu(T): 8.3 D (cyclohexane), 8.9 D (benzene), and 9.7 D (1,4-dioxane), as compared with the previously reported dipole moment of 12 D for the first and the last solvent. With the other aminobenzonitriles, similar mu(T) data are obtained, between 6.9 D for 4-aminobenzonitrile (ABN) in n-hexane and 10.0 D for 4-(di-n-decylamino)benzonitrile (DDABN) in 1,4-dioxane. The increase of mu(T) observed for all aminobenzonitriles when going from cyclohexane via benzene to 1,4-dioxane may indicate that their triplet dipole moments become larger with increasing solvent polarity. The present mu(T) of DMABN, between 8.3 and 9.7 D, although larger than the ground state dipole moment mu(0) of 6.6 D, is somewhat smaller than that of the locally excited (LE) state (9.9 D) but considerably smaller than the dipole moment of the intramolecular charge transfer (ICT) state (17 D). By comparing these mu(X) data with the frequency (CN) of the cyano vibration in each state, it appears that at least for DMABN in the triplet state (CN) is not a reliable indication of the extent of charge transfer as compared with the other states S0, LE, and ICT.     

A caveat concerning the application of the jack-knife to designed data

The jack-knife is a resampling method that is increasingly used for assessing the uncertainty in regression coefficient estimates, even when the predictor variables (X) are designed. Application of the jack-knife to designed data, however, violates a basic assumption underlying all resampling methods, namely that the resampled units should constitute a random sample from some distribution; the idea is to ‘resample the sample.’ This paper advances the view that the jack-knife should not be applied to estimate the uncertainty in regression coefficient estimates obtained from designed data, since a sound alternative is available. A literature data set is re-analyzed to lend support to this view.     

Gas phase spectra of all-benzenoid polycyclic aromatic hydrocarbons: triphenylene

The jet-cooled laser-induced fluorescence and dispersed fluorescence spectra of the S1(A1')<--S0(A1') transition of triphenylene are reported. The spectra exhibit false origins of e' symmetry which are modeled by performing calculations of Herzberg-Teller coupling using time-dependent density functional theory. It is found that this level of theory reproduces the main features of the observed spectra. The oscillator strength of the strongest band is calculated to be f=7x10(-4). From a combination of theory and the observed upper state lifetime of 41 ns, an estimate of the fluorescence yield is made of PhiF=0.084, in agreement with previous studies in the condensed phase.     

Selective conversion of plasma glucose into CO2 by Saccharomyces cerevisiae for the measurement of 13C abundance by isotope ratio mass spectrometry: proof of principle

To study carbohydrate digestion and glucose absorption, time-dependent (13)C enrichment in plasma glucose is measured after oral administration of naturally occurring (13)C-enriched carbohydrates. The isotope enrichment of the administered carbohydrate is low (APE <0.1%) and plasma (13)C glucose measurements are routinely determined with gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) or liquid chromatography/combustion/isotope ratio mass spectrometry (LC/C/IRMS). In this study, plasma glucose was converted into CO(2) by an in-tube reaction with yeast permitting direct measurement of (13)CO(2) in the headspace. Saccharomyces cerevisiae incubated under anaerobic conditions was able to convert sufficient glucose into CO(2) to produce a consistent CO(2) peak in IRMS with little variation in peak area and precise delta(13)C(PDB) values for corn glucose: -11.40 +/- 0.16 per thousand, potato glucose: -25.17 +/- 0.13 per thousand, and plasma glucose: -26.29 +/- 0.05 per thousand. The measurement showed high linearity (R(2) = 0.999) and selectivity and was not affected by the glucose concentration in the tested range of 5-15 mM. Comparison with GC/C/IRMS showed a good correlation of enrichment data: R(2) > 0.98 for both sources of glucose and plasma samples. Commercially available, instant dried baker's yeast was qualitatively and quantitatively comparable with freshly prepared yeast: R(2) > 0.96, slope 1.03 and 1.08 for glucose solutions and plasma, respectively. Thus, yeast conversion of plasma glucose into CO(2) and (13)C measurement applying a breath (13)CO(2) analyzer is an inexpensive, simple and equally accurate alternative to the more expensive and laborious GC/C/IRMS and LC/C/IRMS measurements.     

Photo-induced birefringence in semiconductors compared with optical fibers

We analyze the photon-induced birefringence in semiconductors based on pump-probe setups, within the semiconductor Bloch equations formalism and the Luttinger-Kohn model for the band structure. When the pump and probe pulses are well separated in time, the anisotropic momentum space filling of the photo-excited electrons is the only mechanism causing the induced birefringence. The birefringence ratio is then for pump and probe having perpendicular vs. parallel linear polarizations. This ratio is for opposite vs. identical circular polarization. When the pump and probe pulses overlap in time, these birefringence ratios become for linear polarizations and in case of circular polarizations. These predictions differ markedly from those for optical fibers.     

Activation of the General Stress Response of Bacillus subtilis by Visible Light

A key challenge for microbiology is to understand how evolution has shaped the wiring of regulatory networks. This is amplified by the paucity of information of power‐spectra of physicochemical stimuli to which microorganisms are exposed. Future studies of genome evolution, driven by altered stimulus regimes, will therefore require a versatile signal transduction system that allows accurate signal dosing. Here, we review the general stress response of Bacillus subtilis, and its upstream signal transduction network, as a candidate system. It can be activated by red and blue light, and by many additional stimuli. Signal integration therefore is an intricate function of this system. The blue‐light response is elicited via the photoreceptor YtvA, which forms an integral part of stressosomes, to activate expression of the stress regulon of B. subtilis. Signal transfer through this network can be assayed with reporter enzymes, while intermediate steps can be studied with live‐cell imaging of fluorescently tagged proteins. Different parts of this system have been studied in vitro, such that its computational modeling has made significant progress. One can directly relate the microscopic characteristics of YtvA with activation of the general stress regulon, making this system a very well‐suited system for network evolution studies.     

An inequality for sums of binary digits, with application to Takagi functions

Let ?(x)=2inf{|x−n|:n∈Z}, and define for α>0 the function

     

Lelek?s problem is not a metric problem

We show that Lelek?s problem on the chainability of continua with span zero is not a metric problem: from a non-metric counterexample one can construct a metric one.