Measuring the geometrical size of multiparticle processes

We examine the possibility of measuring the geometrical size of multiparticle processes. The mean-square impact parameter, 〈b²〉, of a process can be estimated by means of lower bounds which are determined from experiment. A bound of this type, which has been proposed by Webber, is found to be inadequate for the estimate. We propose several alternative bounds. One of them represents a considerable improvement over Webber's bound, with essentially no increase in the difficulty of the measurement. Another is a theoretically optimal bound which, however, requires an extremely high-statistics experiment. We also describe a method of deriving further bounds; and make estimates of the difference between the bounds and the true 〈b²〉.     

The structure of pacifigorgiol,an ichthyotoxic sesquiterpenoid from the pacific gorgonian coral pacifigorgiacf.adamsii

An ichthyotoxic sesquiterpenoid of unusual structure, pacifigorgiol, has been isolated from the Pacific gorgonian caora $\text{Pacifigorgia}$$\text{adamsii}$. The structure of pacifigorgiol, with relative stereochemistry only, has been defined by a combination of spectral and x-ray crystallographic techniques.     

Mott insulators without symmetry breaking

We present theoretical models, in one and two space dimensions, that exhibit Mott insulating ground states at fractional occupations without any symmetry breaking. The Hamiltonians of these models are nonlocal in configuration space, but local in phase space.     

Thermodynamic Model of Inorganic Arsenic Species in Aqueous Solutions. Potentiometric Study of the Hydrolytic Equilibrium of Arsenious Acid

A potentiometric study of the hydrolysis of arsenious acid was carried out to define the thermodynamic model of the inorganic arsenic species in aqueous solutions. The protonation equilibrium of arsenious acid was determined at 25^°C. The variation of the stoichiometric formation constant with the ionic strength was also studied up to ionic strength 3.0 mol-dm^–3 in aqueous NaClO₄, NaCl, and KCl. The thermodynamic formation constant of arsenious acid (log K ^o = 9.22 ± 0.01) and the various interaction parameters were computed using the Modified Bromley Methodology (MBM), for both the molar and molal concentration scales at constant temperature (25^°C). The results showed the importance, not only of ionic strength, but also of the composition of the ionic medium on the distribution of the acid-base As(III) species as a function of pH in natural waters.     

Dynamic helical chirality of an intramolecularly hydrogen-bonded bisoxazoline

The synthesis and conformational properties of 2,6-bis-[2-((4S)-4-methyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]carbam oylpyridines, 2, have been described. Bisoxazoline 2a was prepared in five steps from 2-nitrobenzoyl chloride in an overall yield of 71%. In contrast to related structures such as 1, bisoxazoline 2a exhibits a highly biased P-type helical conformation in solution and in the solid state. In the crystal lattice, 2a further assembles into a left-handed helical superstructure aligned along the crystallographic c axis. The barrier to helical interconversion, as measured by line-shape analysis of the temperature-dependent (1)H NMR spectra of thiobenzyl derivative 2b, was determined to be quite low ((Delta)G(++) = 12.3 kcal/mol), indicating the presence of a highly dynamic helical chirality.     

Personal characteristics of older primary care patients who provide a buccal swab for apolipoprotein E testing and banking of genetic material: the spectrum study

OBJECTIVE: To determine the personal characteristics and reasons associated with providing a buccal swab for apolipoprotein E (APOE) genetic testing in a primary care study. METHODS: The study sample consisted of 342 adults aged 65 years and older recruited from primary care settings. RESULTS: In all, 88% of patients agreed to provide a DNA sample for APOE genotyping and 78% of persons providing a sample agreed to banking of the DNA. Persons aged 80 years and older and African-Americans were less likely to participate in APOE genotyping. Concern about confidentiality was the most common reason for not wanting to provide a DNA sample or to have DNA banked. CONCLUSION: We found stronger relationships between sociodemographic variables of age and ethnicity with participation in genetic testing than we did between level of educational attainment, gender, function, cognition, and affect.     

Analytical approximations for stick-slip vibration amplitudes

The classical “mass-on-moving-belt” model for describing friction-induced vibrations is considered, with a friction law describing friction forces that first decreases and then increases smoothly with relative interface speed. Approximate analytical expressions are derived for the conditions, the amplitudes, and the base frequencies of friction-induced stick-slip and pure-slip oscillations. For stick-slip oscillations, this is accomplished by using perturbation analysis for the finite time interval of the stick phase, which is linked to the subsequent slip phase through conditions of continuity and periodicity. The results are illustrated and tested by time-series, phase plots and amplitude response diagrams, which compare very favorably with results obtained by numerical simulation of the equation of motion, as long as the difference in static and kinetic friction is not too large.     

Design and evaluation of a real-time activity probe for focal adhesion kinase

Focal adhesion kinase (FAK) has been identified as a potential therapeutic target for the treatment of metastatic cancers. Herein we describe the design, synthesis and optimization of a direct activity sensor for FAK and its application to screening FAK inhibitors. We find that the position of the sensing moiety, a phosphorylation-sensitive sulfonamido-oxine fluorophore, can dramatically influence the performance of peptide sensors for FAK. Real-time fluorescence activity assays using an optimized sensor construct, termed FAKtide-S2, are highly reproducible (Z' = 0.91) and are capable of detecting as little as 1 nM recombinant FAK. Utilizing this robust assay format, we define conditions for the screening of FAK inhibitors and demonstrate the utility of this platform using a set of well-characterized small molecule kinase inhibitors. Additionally, we provide the selectivity profile of FAKtide-S2 among a panel of closely related enzymes, identifying conditions for selectively monitoring FAK activity in the presence of off-target enzymes. In the long term, the chemosensor platform described in this work can be used to identify novel FAK inhibitor scaffolds and potentially assess the efficacy of FAK inhibitors in disease models.