Fast approximate calculation of multiply scattered lidar returns

An efficient method is described for the approximate calculation of the intensity of multiply scattered lidar returns. It divides the outgoing photons into three populations, representing those that have experienced zero, one, and more than one forward-scattering event. Each population is parameterized at each range gate by its total energy, its spatial variance, the variance of photon direction, and the covariance of photon direction and position. The result is that for an N-point profile the calculation is O(N2) efficient and implicitly includes up to N-order scattering, making it ideal for use in iterative retrieval algorithms for which speed is crucial. In contrast, models that explicitly consider each scattering order separately are at best O(Nm/m!) efficient for m-order scattering and often cannot be performed to more than the third or fourth order in retrieval algorithms. For typical cloud profiles and a wide range of lidar fields of view, the new algorithm is as accurate as an explicit calculation truncated at the fifth or sixth order but faster by several orders of magnitude.     

Charge reduced electrospray size spectrometry of mega- and gigadalton complexes: whole viruses and virus fragments

The ability to analyze and identify large macromolecular complexes whose molecular weight is beyond the analyzable range of mass spectrometry is of great interest. The size of such complexes makes them suitable for analysis via mobility size spectrometry. In this work, charge reduced electrospray size spectrometry was used for the analysis of bacteriophage viruses with total molecular masses ranging from 3.6 MDa up to the gigadalton range. The electrospray source used was operated in "cone jet" mode with a mean droplet diameter of 170.56 nm. Bacteriophage MS2 was found to have a mobility diameter of 24.13 +/- 0.06 nm and remain highly viable after the electrospray process. Larger bacteriophages T2 and T4 have lengths greater than the diameter of the electrospray jet and droplets; thus, they could not be completely enclosed and were found to fragment at the virus capsid head-tail noncovalent interface during either the jet formation or jet breakup process. No viable T2 or T4 virions were detectable after being electrosprayed. While the exact mechanism of fragmentation could not be determined, it is proposed here that macromolecular fragmentation at noncovalent interfaces occurs due to mechanically and electrically induced stresses during jet formation and jet breakup. Bacteriophage T4 capsid heads were found to be statistically significantly larger than bacteriophage T2 capsid heads, with a mean peak diameter of 88.32 +/- 1.02 nm for T4 and 87.03 +/- 0.18 nm for T2. While capsid head fragments were detectable, tail and tail-fiber fragments could not be detected by size spectrometric analysis. This is attributed to the fact that the contractile tails of bacteriophage T2 and T4 virions mechanically deform to a varying degree while confined within the smaller jet and droplets. Further evidence of contractile tail deformation during the electrospray process was found by measuring the size spectrum of bacteriophage lambda, which has a noncontractile tail. Bacteriophage lambda had two distinct peaks in its size spectrum, one corresponding to the capsid head and the other corresponding to the tail fragment. Size spectrometry was also used for rapid quantification of virus concentrations, thus demonstrating its full capabilities in the analysis of large macromolecular complexes.     

Intramammary challenge of the bovine mammary gland with coliform bacteria during early involution

Isolates of Escherichia coli (n = 12), Klebsiella pneumoniae (n = 20), and Klebsiella oxytoca (n = 10) were used to challenge involuting mammary glands at 7 d of the dry period. Bacteria were selected for challenge on the basis of their ability to grow in a pooled source of dry cow secretion obtained at 21 d of involution. Challenge bacteria were classified as highly adapted (in vitro growth greater than 7 cfu log10/ml) or poorly adapted (growth less than 2 cfu log10/ml) for growth in dry cow secretion. Intramammary infusion of Escherichia coli, K. pneumoniae, and K. oxytoca resulted in 0, 40, and 30%, respectively, of quarters infected. Isolates highly adapted for growth in dry cow secretion caused 75% of K. pneumoniae and 67% of K. oxytoca experimental intramammary infections. Results indicated that the ability to overcome inhibitory properties of dry cow secretion was related to the establishment of K. pneumoniae and K. oxytoca intramammary infections in the dry gland. There was no evidence that growth of E. coli in dry cow secretion related to pathogenicity in the dry gland. Experimental challenge using multiple isolates did confirm the resistance of the involuting mammary gland to E. coli infection.     

Development of food recognition in young chicks: I. Maturation and nutrition.

Investigated age and food ingestion as factors influencing food recognition in 5 experiments with a total of 338 Burmese Red Junglefowl chicks. Newly hatched chicks pecked indiscriminately at sand and food; by 3 days of age, pecks were directed primarily at food. Pecking at food or sand had little effect on subsequent pecking at either stimulus until the chicks were 2-3 days old. Ingestion of food then served to facilitate pecking, but such facilitation did not occur until 10 min to 1 hr after ingestion. The effects that occurred on Day 3 were not specific to the stimulus pecked, but pecking at food and sand increased in frequency when the chicks had ingested food. Control experiments using a forced-feeding technique showed that these effects were due to ingestion of food and occurred only if food ingestion was associated with pecking. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Myocardial distribution of antegrade cold crystalloid and tepid blood cardioplegia

BACKGROUND: Tepid blood (TB) cardioplegia combines the improved rheologic characteristics and the augmented oxygen and substrate delivery of blood cardioplegia with the advantages of moderate hypothermia. In addition, the intramyocardial distribution of continuous TB cardioplegia may also be better than intermittent cold crystalloid (CC) cardioplegia. We sought to compare the distribution of TB and CC cardioplegia at varying infusion pressures. METHODS: In situ, isolated canine hearts were randomized to antegrade, continuous TB (28 degrees C, n = 8) or intermittent CC (n = 8) cardioplegia infused at 50, 75, and 100 mm Hg. The regional distribution of cardioplegia at each pressure was measured by 15-microm colored microspheres. Cardioplegia distribution was measured from three areas each of the right ventricle (inflow, outflow, and apex) and the left ventricle (anterior, lateral, and posterior). Left ventricular samples were subdivided into subepicardial, midmyocardial, and subendocardial. RESULTS: Delivery of cardioplegia to all areas of the right and left ventricles showed a linear pressure-flow relationship over the range of pressures tested. Right ventricular distribution was two-thirds of that to the left ventricle, and left ventricular subepicardial distribution was approximately one half of subendocardial flow in both groups at all delivery pressures. However, the subendocardial to subepicardial ratio was significantly greater with TB cardioplegia than with CC cardioplegia. Transmural right ventricular cardioplegia flow was comparable in both groups. In contrast, left ventricular distribution of CC cardioplegia was greater than TB cardioplegia at all three pressures tested. CONCLUSIONS: The pressure-flow relationship in both CC and TB cardioplegia is linear in both the right and left ventricular myocardium over clinically applicable delivery pressures. The distribution of cardioplegia to the right ventricle is not altered by increased pressure.     

Isolation of eukaryotic ribosomal proteins. Purification and characterization of the 40 S ribosomal subunit proteins Sa, Sc, S3a, S3b, S5', S9, S10, S11, S12, S14, S15, S15', S16, S17, S18, S19, S20, S21, S26, S27', and S29

The proteins of the small subunit of rat liver ribosomes were separated into five main groups by stepwise elution from carboxymethylcellulose with LiCl at pH 6.5. Twenty-one proteins (Sa, Sc, S3a, S3b, S5', S9, S10, S11, S12, S14, S15, S15', S16, S17, S18, S19, S20, S21, S26, S27', and S29) were isolated from three groups (A40, C40, and D40) by ion exchange chromatography on DEAE-cellulose, carboxymethylcellulose, and phosphocellulose and by filtration through Sephadex. The amount of protein obtained varied from 0.1 to 11 mg. Six of the proteins (S5', S10, S11, S18, S19, and S27') had no detectable contamination; the impurities in the others were no greater than 9%. The molecular weight of the proteins was estimated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate; the amino acid composition was determined.