Observation of intermediate structure in inelastic proton amplitudes in 49V

The magnitudes and relative signs of inelastic proton channel amplitudes were measured for $\text{72}\text{3}\text{2}{}^{\mathrm{?}}$ resonances in ⁴⁹V. Localized non-statistical behavior is observed in the inelastic amplitudes.     

Free energy difference calculations by thermodynamic integration: Difficulties in obtaining a precise value

Free energy difference calculations have been performed by the “slow growth” method of thermodynamic integration of the AMBER 3.0 molecular dynamics program for the mutation of a conformationally restricted threonine dipeptide, N-acetyl threonyl-N-methylamide, to the corresponding alanyl dipeptide. By varying the total simulation length, it has been determined that precise free energy values are obtained only for simulations of greater than 100 ps total simulation time length. By varying the starting configurations for simulations of the same length, it has been determined that averaging the free energies obtained from shorter simulations may not give precise answers. Possible reasons for this behavior are discussed.     

Synthesis of p-aminobenzamides of aminopiperidazines as potential antiarrhythmic agents

1,2-Dimethyl-4-aminopiperidazine ( 4 ), 1-(2-aminoethyl)2-methylpiperidazine ( 11 ), 2-(2-aminoethyl)-3-meth-yl-2,3-diazabicyclo[2.2.1]heptane ( 16 ), and 1,2-dimethyl-3-aminomethylpiperidazine ( 21 ) have been synthesized. Amines 4, 11 , and 16 were converted to the corresponding p-nitrobenzamides 7,12 , and 17. Catalytic reduction of the latter nitro derivatives gave the corresponding p-aminobenzamides 8,13 , and 18. For comparative studies, the acyclic analog, 4-amino-N[2-(1,1,2-trimethylhydrazino)ethyl]benzamide ( 25 ) was also synthesized. Compounds 8,13 and 25 which are analogs of procainamide were evaluated in the isolated cardiac Purkinje fiber preparation by measuring their effects on the action potential upstroke velocity.     

Recognizing polygonal parts from width measurements

Automatic recognition of parts is an important problem in many industrial applications. One model of the problem is: given a finite set of polygonal parts, use a set of “width” measurements taken by a parallel-jaw gripper to determine which part is present. We study the problem of computing efficient strategies (“grasp plans”), with the goal to minimize the number of measurements necessary in the worst case. We show that finding a minimum length grasp plan is -hard, and give a polynomial time approximation algorithm that is simple and produces a solution that is within a log factor from optimal.     

3-Aryl-5-[(aryloxy)methyl]-3-[(1H-1,2,4-triazol-1-yl)methyl]-2-methylisoxazolidine derivatives. Synthesis and antifungal activity

The synthesis and antifungal activity of a novel series of 3-aryl-5-[(aryloxy)methyl]-3-[(1H-1,2,4-triazol-1-yl)-methyl]-2-methylisoxazolidines are described. The in vitro activity was evaluated in solid agar cultures against a variety of dermatophytes and yeast fungi, while in vivo activity was measured in an immune-compromised mouse model of systemic candidiasis. The activity of the title series was compared to that of ketoconazole and one derivative, the cis-3-(4-chlorophenyl)-5-(4-chlorophenyloxy)methyl analogue 5f was found to possess a similar potency in the in vivo assay. Structure-activity relationship correlations are also discussed.     

Wide-band measurement of frequency-dependent viscoelastic properties using an inverse nyquist plane parameter extraction methodology

This paper presents a new method for dynamically characterizing viscoelastics materials. A multi-degree of freedom vibration model is employed to extract frequency-dependent storage moduli and loss factors from experimental frequency-response functions of the elastomer specimen. The frequency range over which reliable data are available spans from 300 to 6,000 Hz. Hundreds of estimates can be obtained from a single test, Compared with conventional methods, it exhibits the remarkable advantages of covering a wider frequency range, of being more testwise efficient, and of providing more estimates within the frequency range of interest. Paper was presented at the 1989 SEM Spring Conference on Experimental Mechanics held in Cambridge, MA on May 28–June 1.