This paper investigates the probabilistic behaviour of the eigenvalue of the empirical transition matrix of a Markov chain which is of largest modulus other than 1, loosely called the second-largest ...eigenvalue. A central limit theorem is obtained for nonmultiple eigenvalues of the empirical transition matrix. When the Markov chain is actually a sequence of independent observations the distribution of the second-largest eigenvalue is determined and a test for independence is developed. The independence case is considered in more detail when the Markov chain has only two states, and some applications are given.
reaction: see text The total synthesis of the novel metabolite pyridovericin 1 is reported. The synthesis of this key intermediate in our proposed biomimetic synthesis of pyridomacrolidin 2 has been ...accomplished in good yield from readily available 2,4-dihydroxypyridine.
Membrane particles from Propionibacterium shermanii contain cytochromes b and d as the major cytochrome components. Potentiometric titration of the membranes indicate two distinct groups of b-type ...cytochromes differing in their midpoint potentials by at least 100 mV. Low temperature spectra of redox-poised membranes show that the high potential group consists of two components with approximate lambda max and midpoint potentials as follows: cytochrome b562-563 (+120 mV); cytochrome bHP556-557 (+90 mV). Resolution of the low potential group of b-type cytochromes is less clear cut but there appear to be two further components with different lambda max values but very similar midpoint potentials: cytochrome bLP556-557 (-20 mV) and cytochrome b553-554 (-20 mV). Cytochrome d630 titrates as a single species with an approximate midpoint potential of +140 mV. The low potential pair of b-type cytochromes have midpoint potentials sufficiently low to permit their functioning as components of the anaerobic electron transport path to fumarate while the high potential pair of b-type cytochromes and cytochrome d probably function on an aerobic branch of the electron transport pathway. The characteristics of the aerobic and anaerobic steady-state spectra are largely consistent with these suggestions.
Treatment of cationic rhodium piano stool complexes with trifluorovinylphosphines with proton sponge yields complexes of tethered ligands.
▪
The trifluorovinyl phosphine complexes Cp*RhCl
2{PR
3−
x
...(CF
CF
2)
x
} (
1
x
=
1,
a R
=
Ph,
b Pr
i
,
c Et;
2
x
=
2, R
=
Ph) have been prepared by treatment of Cp*RhCl(μ-Cl)
2 with the relevant phosphine. The salt Cp*RhCl(CNBu
t
){PPh
2(CF
CF
2)}BF
4,
3, was prepared by addition of Bu
t
NC to
1a in the presence of NaBF
4. The salt Cp*RhCl{κP,κS-(CF
2
CF)PPh(C
6H
4SMe-2)}BF
4 was prepared as a mixture of
cis (
5a) and
trans (
5b) isomers by treatment of Cp*RhCl(μ-Cl)
2 with the phosphine-thioether (CF
2
CF)PPh(C
6H
4SMe-2),
4, in the presence of NaBF
4. The structures of
1a–
c and
5a have been determined by single-crystal X-ray diffraction. Intramolecular dehydrofluorinative carbon–carbon coupling between pentamethylcyclopentadienyl and trifluorovinylphosphine ligands of
1a,
3 and
5 has been attempted. No reaction was observed on treatment of the neutral complex Cp*RhCl
2{PPh
2(CF
CF
2)},
1a, with proton sponge, however,
5a underwent dehydrofluorinative coupling to yield {η
5,κP,κS-(C
5Me
4CH
2CF
CF)PPh(C
6H
4SMe-2)}RhClBF
4,
6. Other reactions, in particular addition of HF across the vinyl bonds of
5, occurred leading to a mixture of products. The cation of
3 underwent similar reactions.
ABSTRACT
The purpose of this paper was to construct population‐specific charts of fetal biometry for 11−41 weeks gestation in relation to known gestational age from a large population of normal ...Australian pregnancies when examination is performed to a standard protocol by experienced operators. All consenting eligible women attending a large Brisbane clinic between January 1993 and April 2003 were recruited. Menstrual history was taken prior to examination. Measurements were performed to a standard protocol. Prospective assessment was made about the association between gestational age from the last menstrual period and biometry. Exclusion principles were applied. Statistical analyses were performed using polynomial regression models and thorough diagnostic checks were undertaken. Included within the study were separate scans for 20 555 pregnancies from 17 660 women. Equations, means and 95th reference intervals were derived and reported for the following sonographic measurements: biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). Population‐specific regression equations for BPD, HC, AC and FL have been proposed for Australian pregnancies. Once validated by others, we believe they will warrant consideration for adoption by the Australasian Society for Ultrasound in Medicine.
The coordination chemistry of the fluorovinyl substituted phosphines PPh sub(2)(Z-CFinline imageCFH) and PPh sub(2)(E-CClinline imageCFH) with K sub(2)MX sub(4) (M = Pd, Pt; X = Cl, Br, and I) salts ...has been investigated resulting in the first reported palladium(II) and platinum(II) complexes of phosphines containing partially fluorinated vinyl groups. The complexes have been characterised by a combination of multinuclear super(1)H, super(13)C{ super(1)H}, super(19)F, super(31)P{ super(1)H} NMR spectroscopy, and IR/Raman spectroscopy. The single-crystal X-ray structures of trans-PdX sub(2){PPh sub(2)(CFinline imageCFH)} sub(2), X = Cl ( 1), Br ( 2), I ( 3), trans-PdCl sub(2){PPh sub(2)(CClinline imageCFH)} sub(2) ( 4), cis-PtX sub(2){PPh sub(2)(CFinline imageCFH)} sub(2), X = Cl ( 5), Br ( 6), trans-PtI sub(2){PPh sub(2)(CFinline imageCFH)} sub(2) ( 7), and both cis- and trans-PtCl sub(2){PPh sub(2)(CClinline imageCFH)} sub(2) ( 8), have been determined. Results obtained from spectroscopic and crystallographic data suggest that replacement of a b-fluorine by hydrogen, whilst reducing the steric demand of the ligand, has little effect on the electronic character of the ligand. The presence of a proton in the vinyl group results in short proton-halide secondary interactions in the solid state (d(Hinline imageX) = 2.72(3) for 1, and 2.92(5) Aa for 2) forming an infinite chain ribbon motif.
Captive, healthy, adult badgers have blood containing haemoglobin at 13·3 g/dl, and 8·4×1012/l red cells with an MCV of 46·2 f1 and an MCH of 15·6 pg. They have 5·1×109 white cells/1 of which ...3·29×109 are polymorphs, 1·49×109 are lymphocytes, 0·26×109 are monocytes, 0·07×109 are eosinophils and 0·01×109 are basophils. These values are somewhat less in adult animals just trapped from the wild, and are lower still in wild cubs. Changes associated with tuberculosis are a rise, and then a fall in red blood count and white blood count, an increase in the proportion of polymorphs and momocytes and a fall in lymphocytes late in the disease. This picture is similar to that seen in widespread, disseminated, tuberculin negative, tuberculosis in humans, a type of disease similar to that occurring in many badgers. BCG vaccination of badgers did not produce any measurable change in the blood picture.
The recent identification of maedi-visna virus infection in three commercial flocks of indigenous sheep in Britain is described. In one flock the evidence suggested that overt clinical disease was ...present. The implications of the findings are discussed.
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