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Syrian hamster embryo (SHE) assay (pH 6.7) coupled with infrared spectroscopy and chemometrics towards toxicological assessment

The Syrian hamster embryo (SHE) assay (pH 6.7) is an in vitro candidate to replace in vivo carcinogenicity tests. However, the conventional method of visual scoring of foci (non-transformed vs. transformed colonies) can be time-consuming and is open to subjectivity. Infrared (IR) spectroscopy has the potential to provide objective assessment of such SHE colonies with the added advantage of potentially providing mechanistic information. In this study, SHE cells were treated with one of eight different chemical regimens, allowed in culture to attach and form foci on IR-reflective glass slides; these were subsequently interrogated by attenuated total reflection (ATR) Fourier-transform IR (FTIR) spectroscopy. Derived mid-IR spectra (n = 13,406) were subjected to chemometric analysis focusing primarily on the extraction of biochemical information related to test agent treatment and/or morphological transformation. The use of ATR-FTIR spectroscopy with chemometrics to analyze the SHE assay is a novel approach to toxicological assessment.     

On ε‐biased generators in NC0

Cryan and Miltersen (Proceedings of the 26th Mathematical Foundations of Computer Science, 2001, pp. 272–284) recently considered the question of whether there can be a pseudorandom generator in NC⁰, that is, a pseudorandom generator that maps n‐bit strings to m‐bit strings such that every bit of the output depends on a constant number k of bits of the seed. They show that for k = 3, if m ≥ 4n + 1, there is a distinguisher; in fact, they show that in this case it is possible to break the generator with a linear test, that is, there is a subset of bits of the output whose XOR has a noticeable bias. They leave the question open for k ≥ 4. In fact, they ask whether every NC⁰ generator can be broken by a statistical test that simply XORs some bits of the input. Equivalently, is it the case that no NC⁰ generator can sample an ε‐biased space with negligible ε? We give a generator for k = 5 that maps n bits into cn bits, so that every bit of the output depends on 5 bits of the seed, and the XOR of every subset of the bits of the output has bias 2. For large values of k, we construct generators that map n bits to bits such that every XOR of outputs has bias . We also present a polynomial‐time distinguisher for k = 4,m ≥ 24n having constant distinguishing probability. For large values of k we show that a linear distinguisher with a constant distinguishing probability exists once m ≥ Ω(2^kn^?k/2?). Finally, we consider a variant of the problem where each of the output bits is a degree k polynomial in the inputs. We show there exists a degree k = 2 pseudorandom generator for which the XOR of every subset of the outputs has bias 2^?Ω(n) and which maps n bits to Ω(n²) bits. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006     

Maximality of the signless Laplacian energy

We study the problem of determining the graph with $n$ vertices having largest signless Laplacian energy. We conjecture it is the complete split graph whose independent set has (roughly) $2n∕3$ vertices. We show that the conjecture is true for several classes of graphs. In particular, the conjecture holds for the set of all complete split graphs of order $n$, for trees, for unicyclic and bicyclic graphs. We also give conditions on the number of edges, number of cycles and number of small eigenvalues so the graph satisfies the conjecture.     

Quark sea structure functions of the nucleon in a statistical model

Within a statistical model of linear confined quarks we obtain the flavor asymmetry and corresponding structure function of the nucleon. The model parameters are fixed by the experimental available data. The temperature parameter is adjusted by the Gottfried sum rule violation and the chemical potentials by the corresponding up (u) and down (d) quark normalizations in the nucleon. The light antiquark and quark distributions in the proton, given by d̄/ū, d/u and d̄-ū, as well as the neutron to proton ratio of the structure functions, extracted from the experimental data, are well fitted by the model. As the quark-confining strengths should be flavor dependent, a mechanism is introduced in the model to adjust the corresponding distribution, in order to improve the comparison obtained for the sea-quark asymmetries in the nucleon with the available experimental analysis. PACS  11.30.Hv; 14.20.Dh; 12.39.Ki; 12.40.Ee; 11.55.Hx     

Synthetic studies on the trans-chlorocyclopropane dienyne side chain of callipeltoside A

[structure] Enantiomerically enriched trans-chlorocyclopropanemethanol was obtained by lipase kinetic resolution of dichlorocyclopropanemethanol 3, followed by reduction. The sp-sp(2) bond of the trans-chlorocyclopropane dienyne side chain of callipeltoside A was constructed via a Stille coupling reaction of 1, 1-dibromo-1-alkene 7 and a vinylstannane in a highly dipolar solvent capable of promoting HBr elimination to give internal alkynes.     

Experimental results on proton diffractive dissociation

Properties of proton diffractive dissociation have been investigated for four-prong final states in proton-proton reactions at 360 GeV/c, in particular forpp→ppπ ⁺π^? mπ ⁰(m=0,1,2). Mass distributions and decay angular distributions are given. The decay of the diffractive system is seen to be very anisotropic, and largep _T is suppressed at higher masses. It is found that the “pomeron” couples with a single valence quark of the incident proton, but indications for a diquark-pomeron coupling are also found. Similarities with fragmentation in lepton-hadron deep inelastic scattering are underlined.     

Slow proton andΔ ++ production inK + p interactions at 70 GeV/c

The inclusive inelastic processesK ⁺ p→pX ⁺ andK ⁺ p→Δ ⁺⁺ X ⁰ are studied at an incident momentum of 70 GeV/c. The data comes from the Big European Bubble Chamber BEBC filled with hydrogen, exposed to an rf reparatedK ⁺ beam at the CERN SPS accelerator. The inclusive cross section for protons with laboratory momentump _LAB≦1.2 GeV/c is equal to (6.1±0.1) mb. InclusiveΔ ⁺⁺-production is studied for |t _{p, Δ}|<1.0(GeV/c)². Comparisons are made with otherK ⁺ p data and withpp data at 69 GeV/c. Evidence is found for Pomeron exchange at the beam vertex both for slow proton andΔ ⁺⁺-production as well as for absorptive pion exchange at the (p,Δ ⁺⁺) vertex.     

Effective operators for magic ±2 nuclei

Using the many-body Green function technique effective operators for magix ±2 nuclei are derived. Our formulation allows a microscopic proof of the heuristically found additivity of anomalous moments. Possible deviations of the rule are quantitatively discussed. The theory is applied to²⁰⁶Pb,²¹⁰Pb and²¹⁰Po. The theoretical results are in good agreement with experiment.     

Octaline and decalone derivatives from a new annulation reaction in enamine field

An octaline system is obtained from the reaction between 2-cyclohexenyl-1-morpholino-ethene and β-nitrostyrene, carried out under kinetic control. By hydrolysis, it is converted to a 1-decalone derivative, which is also a kinetic control product. The stereochemical aspects of formation and equilibration of the products are examined.