a-Acetamido-N-benzylsuccinamic Acid (V, R' = CHsCO).-When either a-acetamino-N-benzylsuccinimide (VI) or a-acetamido-a-carbethoxysuccinbenzylimide was refluxed for three hours with 10% sodium carbonate and the solution made acid to Congo paper with hydrochloric acid there was obtained an acid which, on crystallization from a large volume of ethyl acetate, melted at 153-155°. This proved to be a-acetamido-N-benzylsuccinamic acid.

Diffusion tensor imaging (DTI) is commonly used for studies of the human brain due to its inherent sensitivity to the microstructural architecture of white matter. In order to increase sampling diversity, it is often desirable to perform multicenter studies. However, it is likely that the variability of acquired data will be greater in multicenter studies than in single-center studies due to the added confound of differences between sites. Therefore, careful characterization of the contributions to variance in a multicenter study is extremely important for meaningful pooling of data from multiple sites. We propose a two-step analysis framework for first identifying outlier datasets, followed by a parametric variance analysis for identification of interand intra-site contributions to total variance. This framework is then applied to phantom data from the NIH MRI study of Normal Brain Development (PedsMRI). Our results suggest that initial outlier identification is extremely important for accurate assessment of inter- and intra-site variability, as well as for early identification of problems with data acquisition. We recommend the use of the presented framework at frequent intervals during the data acquisition phase of multicenter DTI studies, which will allow investigators to identify and solve problems as they occur.

No abstract

The rates of the thermal unimolecular isomerisation of 3-t-butyl-3-methylcyclobutene and 3-methyl-3-phenylcyclobutene have been measured in the gas phase over the temperature ranges 158-190' and 120-180", respectively. They are correlated by the Arrhenius expressions k = 1 014-08 * o*80exp( -1 50.8 f 2.5/RT) sand k = 1 012.60 * O*lzexp( -1 26.1 5 f 0.95/RT) s-l, respectively. The ratio of Z-to €-isomer of the butadienes formed has been measured both for these two and for the 3-methyl-3-R-cyclobutenes, where R = isopropyl, n-propyl, cyclopropyl, pentadeuterioethyl, 4 -methoxyphenyl, 3-methoxyphenyl, and 4-cyanophenyl. In each case the proportion of Z-isomer formed is much larger than would be predicted on steric grounds. For the aryl compounds an attractive interaction during the formation of the Z-diene is proposed to account for its excess formation. For the alkyl substituents, a repulsive electronic interaction between the group and the developing remote double bond should be larger for methyl than for the other alkyl groups, accounting for the observed product ratios. The rates of isomerization of the 3-aryl-3-methylcyclobutenes at 161' correlate with the LUMO of the aromatic ring. The conclusions are shown to apply to results which have been reported by other authors.

Despite the vulnerability of object detectors to adversarial attacks, very few defenses are known to date. While adversarial training can improve the empirical robustness of image classifiers, a direct extension to object detection is very expensive. This work is motivated by recent progress on certified classification by randomized smoothing. We start by presenting a reduction from object detection to a regression problem. Then, to enable certified regression, where standard mean smoothing fails, we propose median smoothing, which is of independent interest. We obtain the first model-agnostic, training-free, and certified defense for object detection against 2 -bounded attacks.Preprint. Under review.