A simple, sensitive liquid chromatographic method for quantitation of D-galactose and D-glucose in blood plasma

The concentrations of D-glucose and D-galactose in plasma of galactosemic rats were quantitatively measured by a liquid chromatographic method, based on retention of the weakly ionized monosaccharides by an anion exchange column under alkaline conditions, elution with 9 mmol/L NaOH, and electrochemical detection. This method is both simple and sensitive, since very dilute plasma samples can be directly analysed.     

Principal minors, Part I: A method for computing all the principal minors of a matrix

An order O(2ⁿ) algorithm for computing all the principal minors of an arbitrary n × n complex matrix is motivated and presented, offering an improvement by a factor of n³ over direct computation. The algorithm uses recursive Schur complementation and submatrix extraction, storing the answer in a binary order. An implementation of the algorithm in MATLAB® is also given and practical considerations are discussed and treated accordingly.     

Improved high-performance liquid chromatographic method for the determination of 6-N,N,N-trimethyllysine in plasma and urine: biomedical application of chromatographic figures of merit and amine mobile phase modifiers

An internally standardized method for the determination of 6-N,N,N-trimethyllysine in human plasma, human urine, rat plasma, rat urine and hydrolyzed rat urine is described. This methylated amino acid and the procedural internal standard 6-N,N,N-trimethyllysine were isolated from the sample matrices using short ion-exchange columns and detected following high-performance liquid chromatography using a postcolumn reaction (o-phthalic-dicarboxaldehyde-2-mercaptoethanol) and fluorometric detection. The reliable detection limit for 6-N,N,N-trimethyllysine was 0.2 nmol/ml in 200 microliters of human plasma. The chromatographic separation exploits the unique properties of a novel tertiary amine mobile phase modifier, 3-(N,N-dimethylamino)-1,2-propanediol. The capacity factor and "Chromatographic Figures of Merit" (including peak asymmetry and relative system efficiency) were calculated for the chromatographic peak representing 6-N,N,N-trimethyllysine in over 2200 injections made while evaluating 900 biological specimens.     

Special examples of quantized friction

The non-linear velocity potential formulation of quantal friction is studied in several special schematic cases: the spreading of a Gaussian packet, superposition of packets, barrier penetration, and potential resonances. Those features which emerge are unified by the concept of a local fluid velocity to which friction is proportional.     

Non-classical law of the iterated logarithm behaviour for trimmed sums

Summary We study the law of the iterated logarithm for the partial sum of i.i.d. random variables when the r _n largest summands are excluded, where r _n=o(log logn). This complements earlier work in which the case log log_n=O(r_n) was considered. A law of the iterated logarithm is again seen to prevail for a wide class of distributions, but for reasons quite different from previously.Research supported in part by NSF Grant DMS-8501732