scholarly journals Biphenyl Dioxygenase from an Arctic Isolate Is Not Cold Adapted

2008 ◽  
Vol 74 (12) ◽  
pp. 3908-3911 ◽  
Author(s):  
Emma R. Master ◽  
Nathalie Y. R. Agar ◽  
Leticia Gómez-Gil ◽  
Justin B. Powlowski ◽  
William W. Mohn ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Biphenyl Dioxygenase ◽  
Pseudomonas Pseudoalcaligenes ◽  
Cold Adapted ◽  
Detectable Activity ◽  
Burkholderia Xenovorans ◽  
Psychrotolerant Bacterium

ABSTRACT Biphenyl dioxygenase from the psychrotolerant bacterium Pseudomonas sp. strain Cam-1 (BPDOCam-1) was purified and found to have an apparent \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(k_{cat}\) \end{document} for biphenyl of 1.1 ± 0.1 s−1 (mean ± standard deviation) at 4°C. In contrast, BPDOLB400 from the mesophile Burkholderia xenovorans LB400 had no detectable activity at this temperature. At 57°C, the half-life of the BPDOCam-1 oxygenase was less than half that of the BPDOLB400 oxygenase. Nevertheless, BPDOCam-1 appears to be a typical Pseudomonas pseudoalcaligenes KF707-type dioxygenase.

scholarly journals Directed Evolution of Biphenyl Dioxygenase: Emergence of Enhanced Degradation Capacity for Benzene, Toluene, and Alkylbenzenes

2001 ◽  
Vol 183 (18) ◽  
pp. 5441-5444 ◽  
Author(s):  
Hikaru Suenaga ◽  
Mariko Mitsuoka ◽  
Yuko Ura ◽  
Takahito Watanabe ◽  
Kensuke Furukawa
Keyword(s):  
Amino Acids ◽  
Aromatic Hydrocarbons ◽  
Burkholderia Cepacia ◽  
Large Subunit ◽  
Site Directed Mutagenesis ◽  
Biphenyl Dioxygenase ◽  
Pseudomonas Pseudoalcaligenes ◽  
Benzene Toluene ◽  
Related Compounds ◽  
Enhanced Degradation

ABSTRACT Biphenyl dioxygenase (Bph Dox) catalyzes the initial oxygenation of biphenyl and related compounds. Bph Dox is a multicomponent enzyme in which a large subunit (encoded by the bphA1 gene) is significantly responsible for substrate specificity. By using the process of DNA shuffling of bphA1 of Pseudomonas pseudoalcaligenes KF707 and Burkholderia cepaciaLB400, a number of evolved Bph Dox enzymes were created. Among them, anEscherichia coli clone expressing chimeric Bph Dox exhibited extremely enhanced benzene-, toluene-, and alkylbenzene-degrading abilities. In this evolved BphA1, four amino acids (H255Q, V258I, G268A, and F277Y) were changed from the KF707 enzyme to those of the LB400 enzyme. Subsequent site-directed mutagenesis allowed us to determine the amino acids responsible for the degradation of monocyclic aromatic hydrocarbons.

scholarly journals University of Miami Radiocarbon Dates XVI

Radiocarbon ◽  
1979 ◽  
Vol 21 (3) ◽  
pp. 477-483
Author(s):  
D S Introne ◽  
R Johnson ◽  
J J Stipp
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Marine Carbonates ◽  
Age Correction ◽  
University Of Miami ◽  
Reservoir Age ◽  
Modern Standard

Radiocarbon measurements have been continued on a variety of projects and materials. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282. Dates are calculated using the Libby 14C half-life of 5568 years; errors are reported as one-standard deviation (1σ) based only on statistical counting uncertainties in background, modern standard, and sample activities. All samples for which 13C/12C ratios are available are corrected for isotopic fractionation by normalizing to —25‰. A 400-year reservoir age correction has been applied to marine carbonates.

scholarly journals University of Miami Radiocarbon Dates VIII

Radiocarbon ◽  
1977 ◽  
Vol 19 (1) ◽  
pp. 118-126 ◽  
Author(s):  
D Piepgras ◽  
J J Stipp
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Radiocarbon Dates ◽  
Partial List ◽  
University Of Miami

The following radiocarbon measurements are a partial list of projects and samples dated since January 1975. The technique used is described in R, v 16, pp 402-408 and R, v 18, pp 210-220. Dates are calculated using 14C half-life of 5568 yr and errors are reported as one-standard deviation.

Propaganda and Protest in Autocracies

2020 ◽  
pp. 002200272097509
Author(s):  
Erin Baggott Carter ◽  
Brett L. Carter
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Popular Protest ◽  
Original Dataset ◽  
Initial Effect ◽  
Temporal Persistence ◽  
Over Time

Does propaganda reduce the rate of popular protest in autocracies? To answer this question, we draw on an original dataset of state-run newspapers from thirty countries, encompassing six languages and over four million articles. We find that propaganda diminishes the rate of protest, and that its effects persist over time. By increasing the level of pro-regime propaganda by one standard deviation, autocrats have reduced the odds of protest the following day by 15%. The half-life of this effect is between five and ten days, and very little of the initial effect persists after one month. This temporal persistence is remarkably consistent with campaign advertisements in democracies.

scholarly journals National Physical Laboratory Radiocarbon Measurements IV

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 340-347 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Geraldine I. Hassall
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Count Rate ◽  
National Physical Laboratory ◽  
Background Count ◽  
Best Value ◽  
Sample Count ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL III and is complete to the end of November 1965.Ages are relative to A.D. 1950 and are calculated using a half-life of 5568 yr. The measurements, corrected for fractionation (quoted δC13 values are relative to the P.D.B. standard), are referred to 0.950 times the activity of the NBS oxalic acid as contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances as described in detail in NPL III. These variances are those of the standard and background measurements over a rolling twenty week period, of the sample δC14 and δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty then included. If the net sample count rate is less than 4 times the standard error of the difference between the sample and background count rates, a lower limit to the age is reported corresponding to a net sample count rate of 4 times the standard error of this difference.

scholarly journals Tartu Radiocarbon Dates XIII

Radiocarbon ◽  
1994 ◽  
Vol 36 (1) ◽  
pp. 153-158
Author(s):  
Arvi Liiva ◽  
Ilze Loze
Keyword(s):  
Standard Deviation ◽  
Oxalic Acid ◽  
Liquid Scintillation Counting ◽  
Half Life ◽  
Liquid Scintillation ◽  
Standard Sample ◽  
Scintillation Counting ◽  
Radiocarbon Dates ◽  
Academy Of Sciences ◽  
Modern Standard

This date list reports dates of archaeological samples of Mesolithic and Neolithic sites of Estonia, Latvia and Lithuania. We use liquid scintillation counting at the Geochemical and Statistical Laboratory of the Institute of Zoology and Botany, Estonian Academy of Sciences. Our modern standard is benzene enriched in 14C and its activity is checked with an NBS oxalic acid standard sample. Dates are given in conventional 14C years, based on the Libby half-life of 5570 ± 30 yr. AD 1950 is the reference year. Errors are based on one standard deviation calculated from count rates.

scholarly journals National Physical Laboratory Radiocarbon Measurements II

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 25-30 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Daphne H. Pritchard
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Research Programme ◽  
National Physical Laboratory ◽  
Reference Standard ◽  
Best Value ◽  
Physical Laboratory ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL I and is complete to the end of November 1963.Ages are relative to a.d. 1950 and are calculated using a half-life of 5568 yr. The measurements have been corrected for fractionation and referred to 0.950 times the activity of the NBS oxalic acid as a contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances, viz. those of the standard and background measurements over a rolling twenty-week period, of the sample measurements from at least three independent fillings, of the δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty included. If the net sample activity is less than 4 times the standard error of the difference between the sample and background activities, a lower limit to the age is reported equivalent to a sample activity of 4 times the standard error of this difference.The description of each sample is based on information provided by the person submitting the sample to the Laboratory.The work reported forms part of the research programme of the Laboratory and is published by permission of the Director.

scholarly journals Lyon Natural Radiocarbon Measurements VIII

Radiocarbon ◽  
1979 ◽  
Vol 21 (3) ◽  
pp. 405-452 ◽  
Author(s):  
J Evin ◽  
G Marien ◽  
C Pachiaudi
Keyword(s):  
Standard Deviation ◽  
Chemical Treatment ◽  
Calculation Method ◽  
Half Life ◽  
Liquid Scintillation ◽  
Small Samples ◽  
Sample Versus ◽  
Made In

This list includes most of the measurements made in 1977 and 1978 using the two Packard liquid scintillation spectrometers described in Lyon VII (R, 1978, v 20, p 19). The backgrounds of both spectrometers decreased by about 30% with new photomultipliers, giving 1.9 ± 0.1cpm and 2.4 ± 0.2 cpm, respectively, for 3ml C6H6(depending on counting vessels). Proportional detectors are only used for very small samples. Counting procedures are described in the text. Dilution ratios indicate the amount of sample versus the total quantity of C6H6or CO2introduced in the detectors. No change was made either in chemical treatment or in the calculation method (half-life: 5570 ± 0, one standard deviation, standard13C correction only for bones).

scholarly journals University of Michigan Radiocarbon Dates XI

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 256-285 ◽  
Author(s):  
H. R. Crane ◽  
James B. Griffin
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Geiger Counter ◽  
University Of Michigan ◽  
Radiocarbon Dates ◽  
Statistical Errors ◽  
Sources Of Error ◽  
The Many ◽  
Many Sources

The following is a list of dates obtained since the time of the compilation of List X in December 1964. The method is essentially the same as that used for the work described in the previous list. Two CO2-CS2Geiger counter systems are used. The equipment and counting techniques have been described elsewhere (Crane, 1961). The dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) A.D. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In previous Michigan date lists up to and including VII we have quoted errors at least twice as great as the statistical errors of counting, in order to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many sources of error in the dating process, we suggest he double the figures that are given in this list.

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