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Sample records for standard atomic weight

  1. How Good Are the Standard Atomic Weights?

    ERIC Educational Resources Information Center

    Peiser, H. Steffen

    1985-01-01

    This review of standard atomic weights is written chiefly for chemical analysts who may place too much confidence in the accuracy of these values. Topics considered include Frank Clarke's atomic weights, effects of radioactivity and other anomalies in isotopic abundance, atomic weight limitations from experimental uncertainties, and others. (JN)

  2. Clarifying atomic weights: A 2016 four-figure table of standard and conventional atomic weights

    USGS Publications Warehouse

    Coplen, Tyler B.; Meyers, Fabienne; Holden, Norman E.

    2017-01-01

    To indicate that atomic weights of many elements are not constants of nature, in 2009 and 2011 the Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) replaced single-value standard atomic weight values with atomic weight intervals for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium); for example, the standard atomic weight of nitrogen became the interval [14.00643, 14.00728]. CIAAW recognized that some users of atomic weight data only need representative values for these 12 elements, such as for trade and commerce. For this purpose, CIAAW provided conventional atomic weight values, such as 14.007 for nitrogen, and these values can serve in education when a single representative value is needed, such as for molecular weight calculations. Because atomic weight values abridged to four figures are preferred by many educational users and are no longer provided by CIAAW as of 2015, we provide a table containing both standard atomic weight values and conventional atomic weight values abridged to four figures for the chemical elements. A retrospective review of changes in four-digit atomic weights since 1961 indicates that changes in these values are due to more accurate measurements over time or to the recognition of the impact of natural isotopic fractionation in normal terrestrial materials upon atomic weight values of many elements. Use of the unit “u” (unified atomic mass unit on the carbon mass scale) with atomic weight is incorrect because the quantity atomic weight is dimensionless, and the unit “amu” (atomic mass unit on the oxygen scale) is an obsolete term: Both should be avoided.

  3. STANDARD ATOMIC WEIGHT VALUES FOR THE MONONUCLIDIC ELEMENTS - 2001.

    SciTech Connect

    HOLDEN, N.E.

    2001-06-29

    Atomic Mass Evaluations have had a major impact on the values of the atomic weights for the twenty mononuclidic elements plus two elements, Thorium and Protactinium, which have no stable nuclides but a characteristic terrestrial isotopic composition. This paper reviews the history of the atomic weight values of these elements in the years, since the reference mass standard changed from {sup 16}O to {sup 12}C. There is a problem for Thorium, which is considered to have an abundance value of 100%, but is not treated as such in the Standard Atomic Weights' Table. Recommendations for handling the Standard Atomic Weight values for 2001 are presented.

  4. RADIOACTIVE ELEMENTS IN THE STANDARD ATOMIC WEIGHTS TABLE

    SciTech Connect

    Holden, N.E.; Holden, N.; Holden,N.E.

    2011-07-27

    , from which an atomic weight value could be calculated to five or more figure accuracy, without prior knowledge of the sample involved. These elements were again listed in the Atomic Weights Table with no further information, i.e., with no mass number or atomic weight value. For the elements, which have no stable characteristic terrestrial isotopic composition, the data on the half-lives and the relative atomic masses for the nuclides of interest for those elements have been evaluated. The values of the half-lives with their uncertainties are listed in the table. The uncertainties are given for the last digit quoted of the half-life and are given in parentheses. A half-life entry for the Table having a value and an uncertainty of 7 {+-} 3 is listed in the half-life column as 7 (3). The criteria to include data in this Table, is to be the same as it has been for over sixty years. It is the same criteria, which are used for all data that are evaluated for inclusion in the Standard Table of Atomic Weights. If a report of data is published in a peer-reviewed journal, that data is evaluated and considered for inclusion in the appropriate table of the biennial report of the Atomic Weights Commission. As better data becomes available in the future, the information that is contained in either of the Tables of Standard Atomic Weights or in the Table of Radioactive Elements may be modified. It should be noted that the appearance of any datum in the Table of the Radioactive Elements is merely for the purposes of calculating an atomic mass value for any sample of a radioactive material, which might have a variety of isotopic compositions and it has no implication as to the priority for claiming discovery of a given element and is not intended to. The atomic mass values have been taken primarily from the 2003 Atomic Mass Table. Mass values for those radioisotopes that do not appear in the 2003 Atomic mass Table have been taken from preliminary data of the Atomic Mass Data Center

  5. Radioactive Elements in the Standard Atomic Weights Table.

    SciTech Connect

    Holden,N.E.

    2007-08-04

    In the 1949 Report of the Atomic Weights Commission, a series of new elements were added to the Atomic Weights Table. Since these elements had been produced in the laboratory and were not discovered in nature, the atomic weight value of these artificial products would depend upon the production method. Since atomic weight is a property of an element as it occurs in nature, it would be incorrect to assign an atomic weight value to that element. As a result of that discussion, the Commission decided to provide only the mass number of the most stable (or longest-lived) known isotope as the number to be associated with these entries in the Atomic Weights Table. As a function of time, the mass number associated with various elements has changed as longer-lived isotopes of a particular element has been found in nature, or as improved half-life values of an element's isotopes might cause a shift in the longest-lived isotope from one mass to another. In the 1957 Report of the Atomic Weights Commission, it was decided to discontinue the listing of the mass number in the Atomic Weights Table on the grounds that the kind of information supplied by the mass number is inconsistent with the primary purpose of the Table, i.e., to provide accurate values of 'these constants' for use in various chemical calculations. In addition to the Table of Atomic Weights, the Commission included an auxiliary Table of Radioactive Elements for the first time, where the entry would be the isotope of that element which was the most stable, i.e., the one with the longest known half-life. In their 1973 Report, the Commission noted that the users of the main Table of Atomic Weights were dissatisfied with the omission of values for some elements in that Table and it was decided to reintroduce the mass number for the radioactive elements into the main Table. In their 1983 Report, the Commission decided that radioactive elements were considered to lack a characteristic terrestrial isotopic composition

  6. STANDARD ATOMIC WEIGHTS TABLES 2007 ABRIDGED TO FOUR AND FIVE SIGNIFICANT FIGURES.

    SciTech Connect

    HOLDEN,N.E.

    2007-08-01

    In response to a recommendation to the Commission on Isotopic Abundances and Atomic Weights (CIAAW) that abridged versions of the Table on Standard Atomic Weights be prepared and published, this report has been prepared. A brief history is presented of such Atomic Weight tables that have been abridged to four significant figures and to five significant figures are noted. Tables of Standard Atomic Weight values abridged to four places and five places from the official 2007 Table of Atomic Weights approved by CIAAW are included.

  7. Forecast of Standard Atomic Weights for the Mononuclidic Elements – 2011

    SciTech Connect

    Holden, N.E.; Holden, N.; Holden,N.E.

    2011-07-27

    In this short report, I will provide an early warning about potential changes to the standard atomic weight values for the twenty mononuclidic and the so-called pseudo-mononuclidic ({sup 232}Th and {sup 231}Pa) chemical elements due to the estimated changes in the mass values to be published in the next Atomic Mass Tables within the next two years. There have been many new measurements of atomic masses, since the last published Atomic Mass Table. The Atomic Mass Data Center has released an unpublished version of the present status of the atomic mass values as a private communication. We can not update the Standard Atomic Weight Table at this time based on these unpublished values but we can anticipate how many changes are probably going to be expected in the next few years on the basis of the forthcoming publication of the Atomic Mass Table. I will briefly discuss the procedures that the Atomic Weights Commission used in deriving the recommended Standard Atomic Weight values and their uncertainties from the atomic mass values. I will also discuss some concern raised about a proposed change in the definition of the mole. The definition of the mole is now connected directly to the mass of a {sup 12}C isotope (which is defined as 12 exactly) and to the kilogram. A change in the definition of the mole will probably impact the mass of {sup 12}C.

  8. Data reduction framework for standard atomic weights and isotopic compositions of the elements

    NASA Astrophysics Data System (ADS)

    Meija, Juris; Possolo, Antonio

    2017-04-01

    We outline a general framework to compute consensus reference values of standard atomic weights, isotope ratios, and isotopic abundances, and to evaluate associated uncertainties using modern statistical methods for consensus building that can handle mutually inconsistent measurement results. The multivariate meta-regression approach presented here is directly relevant to the work of the IUPAC Commission on Isotopic Abundances and atomic weights (CIAAW), and we illustrate the proposed method in meta-analyses of the isotopic abundances and atomic weights of zinc, platinum, antimony, and iridium.

  9. Atomic Weights and Isotopic Compositions

    National Institute of Standards and Technology Data Gateway

    SRD 144 Atomic Weights and Isotopic Compositions (Web, free access)   The atomic weights are available for elements 1 through 111, and isotopic compositions or abundances are given when appropriate.

  10. Review of footnotes and annotations to the 1949–2013 tables of standard atomic weights and tables of isotopic compositions of the elements (IUPAC Technical Report)

    USGS Publications Warehouse

    Coplen, Tyler B.; Holden, Norman E.

    2016-01-01

    The Commission on Isotopic Abundances and Atomic Weights uses annotations given in footnotes that are an integral part of the Tables of Standard Atomic Weights to alert users to the possibilities of quite extraordinary occurrences, as well as sources with abnormal atomic-weight values outside an otherwise acceptable range. The basic need for footnotes to the Standard Atomic Weights Table and equivalent annotations to the Table of Isotopic Compositions of the Elements arises from the necessity to provide users with information that is relevant to one or more elements, but that cannot be provided using numerical data in columns. Any desire to increase additional information conveyed by annotations to these Tables is tempered by the need to preserve a compact format and a style that can alert users, who would not be inclined to consult either the last full element-by-element review or the full text of a current Standard Atomic Weights of the Elements report. Since 1989, the footnotes of the Tables of Standard Atomic Weights and the annotations in column 5 of the Table of Isotopic Compositions of the Elements have been harmonized by use of three lowercase footnotes, “g”, “m”, and “r”, that signify geologically exceptionally specimens (“g”), modified isotopic compositions in material subjected to undisclosed or inadvertent isotopic fractionation (“m”), and the range in isotopic composition of normal terrestrial material prevents more precise atomic-weight value being given (“r”). As some elements are assigned intervals for their standard atomic-weight values (applies to 12 elements since 2009), footnotes “g” and “r” are no longer needed for these elements.

  11. Review of footnotes and annotations to the 1949–2013 tables of standard atomic weights and tables of isotopic compositions of the elements (IUPAC Technical Report)

    SciTech Connect

    Coplen, Tyler B.; Holden, Norman E.

    2016-01-01

    Abstract

    The Commission on Isotopic Abundances and Atomic Weights uses annotations given in footnotes that are an integral part of the Tables of Standard Atomic Weights to alert users to the possibilities of quite extraordinary occurrences, as well as sources with abnormal atomic-weight values outside an otherwise acceptable range. The basic need for footnotes to the Standard Atomic Weights Table and equivalent annotations to the Table of Isotopic Compositions of the Elements arises from the necessity to provide users with information that is relevant to one or more elements, but that cannot be provided using numerical data in columns. Any desire to increase additional information conveyed by annotations to these Tables is tempered by the need to preserve a compact format and a style that can alert users, who would not be inclined to consult either the last full element-by-element review or the full text of a current Standard Atomic Weights of the Elements report. Since 1989, the footnotes of the Tables of Standard Atomic Weights and the annotations in column 5 of the Table of Isotopic Compositions of the Elements have been harmonized by use of three lowercase footnotes, “g”, “m”, and “r”, that signify geologically exceptionally specimens (“g”), modified isotopic compositions in material subjected to undisclosed or inadvertent isotopic fractionation (“m”), and the range in isotopic composition of normal terrestrial material prevents more precise atomic-weight value being given (“r”). As some elements are assigned intervals for their standard atomic-weight values (applies to 12 elements since 2009), footnotes “g” and “r” are no longer needed for these elements.

  12. Review of footnotes and annotations to the 1949–2013 tables of standard atomic weights and tables of isotopic compositions of the elements (IUPAC Technical Report)

    DOE PAGES

    Coplen, Tyler B.; Holden, Norman E.

    2016-01-01

    The Commission on Isotopic Abundances and Atomic Weights uses annotations given in footnotes that are an integral part of the Tables of Standard Atomic Weights to alert users to the possibilities of quite extraordinary occurrences, as well as sources with abnormal atomic-weight values outside an otherwise acceptable range. The basic need for footnotes to the Standard Atomic Weights Table and equivalent annotations to the Table of Isotopic Compositions of the Elements arises from the necessity to provide users with information that is relevant to one or more elements, but that cannot be provided using numerical data in columns. Anymore » desire to increase additional information conveyed by annotations to these Tables is tempered by the need to preserve a compact format and a style that can alert users, who would not be inclined to consult either the last full element-by-element review or the full text of a current Standard Atomic Weights of the Elements report. Since 1989, the footnotes of the Tables of Standard Atomic Weights and the annotations in column 5 of the Table of Isotopic Compositions of the Elements have been harmonized by use of three lowercase footnotes, “g”, “m”, and “r”, that signify geologically exceptionally specimens (“g”), modified isotopic compositions in material subjected to undisclosed or inadvertent isotopic fractionation (“m”), and the range in isotopic composition of normal terrestrial material prevents more precise atomic-weight value being given (“r”). As some elements are assigned intervals for their standard atomic-weight values (applies to 12 elements since 2009), footnotes “g” and “r” are no longer needed for these elements.« less

  13. Atomic weights of the elements 1999

    USGS Publications Warehouse

    Coplen, T.B.

    2001-01-01

    The biennial review of atomic-weight, Ar(E), determinations and other cognate data have resulted in changes for the standard atomic weights of the following elements: Presented are updated tables of the standard atomic weights and their uncertainties estimated by combining experimental uncertainties and terrestrial variabilities. In addition, this report again contains an updated table of relative atomic-mass values and half-lives of selected radioisotopes. Changes in the evaluated isotopic abundance values from those published in 1997 are so minor that an updated list will not be published for the year 1999. Many elements have a different isotopic composition in some nonterrestrial materials. Some recent data on parent nuclides that might affect isotopic abundances or atomic-weight values are included in this report for the information of the interested scientific community.

  14. Atomic weights: no longer constants of nature

    USGS Publications Warehouse

    Coplen, Tyler B.; Holden, Norman E.

    2011-01-01

    Many of us were taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis have changed the way we view atomic weights and why they are no longer constants of nature

  15. Atomic Weights No Longer Constants of Nature

    SciTech Connect

    Coplen, T.B.; Holden, N.

    2011-03-01

    Many of us grew up being taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis has changed the way we view atomic weights and why they are no longer constants of nature.

  16. Atomic weights of the elements 1999

    USGS Publications Warehouse

    Coplen, T.B.

    2001-01-01

    The biennial review of atomic-weight, Ar(E), determinations and other cognate data have resulted in changes for the standard atomic weights of the following elements: from to nitrogen 14.006 74??0.000 07 14.0067??0.0002 sulfur 32.066??0.006 32.065??0.005 chlorine 35.4527??0.0009 35.453??0.002 germanium 72.61??0.02 72.64??0.01 xenon 131.29??0.02 131.293??0.006 erbium 167.26??0.03 167.259??0.003 uranium 238.0289??0.0001 238.028 91??0.000 03 Presented are updated tables of the standard atomic weights and their uncertainties estimated by combining experimental uncertainties and terrestrial variabilities. In addition, this report again contains an updated table of relative atomic mass values and half-lives of selected radioisotopes. Changes in the evaluated isotopic abundance values from those published in 1997 are so minor that an updated list will not be published for the year 1999. Many elements have a different isotopic composition in some nonterrestrial materials. Some recent data on parent nuclides that might affect isotopic abundances or atomic-weight values are included in this report for the information of the interested scientific community. ?? 2001 American Institute of Physics.

  17. Atomic weights of the elements 2011 (IUPAC Technical Report)

    USGS Publications Warehouse

    Wieser, Michael E.; Holden, Norman; Coplen, Tyler B.; Böhlke, John K.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Loss, Robert D.; Meija, Juris; Hirata, Takafumi; Prohaska, Thomas; Schoenberg, Ronny; O'Connor, Glenda; Walczyk, Thomas; Yoneda, Shige; Zhu, Xiang-Kun

    2013-01-01

    The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of five elements. The atomic weight of bromine has changed from 79.904(1) to the interval [79.901, 79.907], germanium from 72.63(1) to 72.630(8), indium from 114.818(3) to 114.818(1), magnesium from 24.3050(6) to the interval [24.304, 24.307], and mercury from 200.59(2) to 200.592(3). For bromine and magnesium, assignment of intervals for the new standard atomic weights reflects the common occurrence of variations in the atomic weights of those elements in normal terrestrial materials.

  18. Atomic weights of the elements 2009 (IUPAC technical report)

    USGS Publications Warehouse

    Wieser, M.E.; Coplen, T.B.

    2011-01-01

    The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of 11 elements. Many atomic weights are not constants of nature, but depend upon the physical, chemical, and nuclear history of the material. The standard atomic weights of 10 elements having two or more stable isotopes have been changed to reflect this variability of atomic-weight values in natural terrestrial materials. To emphasize the fact that these standard atomic weights are not constants of nature, each atomic-weight value is expressed as an interval. The interval is used together with the symbol [a; b] to denote the set of atomic-weight values, Ar(E), of element E in normal materials for which a ≤ Ar(E) ≤ b. The symbols a and b denote the bounds of the interval [a; b]. The revised atomic weight of hydrogen, Ar(H), is [1.007 84; 1.008 11] from 1.007 94(7); lithium, Ar(Li), is [6.938; 6.997] from 6.941(2); boron, Ar(B), is [10.806; 10.821] from 10.811(7); carbon, Ar(C), is [12.0096; 12.0116] from 12.0107(8); nitrogen, Ar(N), is [14.006 43; 14.007 28] from 14.0067(2); oxygen, Ar(O), is [15.999 03; 15.999 77] from 15.9994(3); silicon, Ar(Si), is [28.084; 28.086] from 28.0855(3); sulfur, Ar(S), is [32.059; 32.076] from 32.065(2); chlorine, Ar(Cl), is [35.446; 35.457] from 35.453(2); and thallium, Ar(Tl), is [204.382; 204.385] from 204.3833(2). This fundamental change in the presentation of the atomic weights represents an important advance in our knowledge of the natural world and underscores the significance and contributions of chemistry to the well-being of humankind in the International Year of Chemistry 2011. The standard atomic weight of germanium, Ar(Ge), was also changed to 72.63(1) from 72.64(1).

  19. Prospects for atomic frequency standards

    NASA Technical Reports Server (NTRS)

    Audoin, C.

    1984-01-01

    The potentialities of different atomic frequency standards which are not yet into field operation, for most of them, but for which preliminary data, obtained in laboratory experiments, give confidence that they may improve greatly the present state of the art are described. The review will mainly cover the following devices: (1) cesium beam frequency standards with optical pumping and detection; (2) optically pumped rubidium cells; (3) magnesium beam; (4) cold hydrogen masers; and (5) traps with stored and cooled ions.

  20. The role of mass spectrometry in atomic weight determinations.

    PubMed

    De Laeter, John R

    2009-01-01

    accurate isotopic measurements. Atomic weights can no longer be regarded as constants of nature, except for the monoisotopic elements whose atomic weights are determined solely by the relative atomic mass of that nuclide. Stable isotope geochemists developed mass spectrometric protocols by the adoption of internationally accepted reference materials for the light elements, to which measurements from various laboratories could be compared. Subsequently, a number of heavy elements such as iron, molybdenum and cadmium have been shown to exhibit isotope fractionation. The magnitude of such isotope fractionation in nature is less than for the light elements, but technological developments, such as multiple collector-inductively coupled plasma-mass spectrometry, have enabled such fractionation effects to be determined. Measurements of the atomic weights of certain elements affect the determination of important fundamental constants such as the Avogadro Constant, the Faraday Constant and the Universal Gas Constant. Heroic efforts have been made to refine the accuracy of the atomic weight of silicon, with the objective of replacing the SI standard of mass--the kilogram--with the Avogadro Constant. Improvements in these fundamental constants in turn affect the set of self-consistent values of other basic constants through a least-squares adjustment methodology. Absolute isotope abundances also enable the Solar System abundances of the s-, r-, and p-process of nucleosynthesis to be accurately determined, thus placing constraints on theories of heavy element nucleosynthesis. Future developments in the science of atomic weight determinations are also examined.

  1. GPS Block IIF Atomic Frequency Standard Analysis

    DTIC Science & Technology

    2010-11-01

    Frequency stability of GPS constellation for October 2010 (NGA products). REFERENCES [1] “ Rubidium Atomic Frequency Standard (RAFS) GPS...Block IIR Rubidium Atomic Frequency Standard Life Test,” in Proceedings of the 30 th Annual Precise Time and Time Interval (PTTI) Applications and...42 nd Annual Precise Time and Time Interval (PTTI) Meeting 181 GPS BLOCK IIF ATOMIC FREQUENCY STANDARD ANALYSIS

  2. 7 CFR 51.1863 - Standard weight.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... net weight of 15 pounds (6.80 kg) or more, the net weight of the contents shall not be less than...

  3. Atomic weights of the elements 2013 (IUPAC Technical Report)

    USGS Publications Warehouse

    Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna; Loss, Robert D.; Walczyk, Thomas; Prohaska, Thomas

    2016-01-01

    The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of 19 elements. The standard atomic weights of four elements have been revised based on recent determinations of isotopic abundances in natural terrestrial materials:cadmium to 112.414(4) from 112.411(8),molybdenum to 95.95(1) from 95.96(2),selenium to 78.971(8) from 78.96(3), andthorium to 232.0377(4) from 232.038 06(2). The Commission on Isotopic Abundances and Atomic Weights (ciaaw.org) also revised the standard atomic weights of fifteen elements based on the 2012 Atomic Mass Evaluation:aluminium (aluminum) to 26.981 5385(7) from 26.981 5386(8),arsenic to 74.921 595(6) from 74.921 60(2),beryllium to 9.012 1831(5) from 9.012 182(3),caesium (cesium) to 132.905 451 96(6) from 132.905 4519(2),cobalt to 58.933 194(4) from 58.933 195(5),fluorine to 18.998 403 163(6) from 18.998 4032(5),gold to 196.966 569(5) from 196.966 569(4),holmium to 164.930 33(2) from 164.930 32(2),manganese to 54.938 044(3) from 54.938 045(5),niobium to 92.906 37(2) from 92.906 38(2),phosphorus to 30.973 761 998(5) from 30.973 762(2),praseodymium to 140.907 66(2) from 140.907 65(2),scandium to 44.955 908(5) from 44.955 912(6),thulium to 168.934 22(2) from 168.934 21(2), andyttrium to 88.905 84(2) from 88.905 85(2). The Commission also recommends the standard value for the natural terrestrial uranium isotope ratio, N(238U)/N(235U)=137.8(1).

  4. NASA atomic hydrogen standards program: An update

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S.; Kaufmann, D. C.; Adams, W. A.; Deluca, J. J.; Soucy, J. L.

    1976-01-01

    Comparisons are made between the NP series and the NX series of hydrogen masers. A field operable hydrogen maser (NR series) is also described. Atomic hydrogen primary frequency standards are in development stages. Standards are being developed for a hydrogen beam frequency standard and for a concertina hydrogen maser.

  5. 7 CFR 51.1863 - Standard weight.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... the contents shall not be less than the designated net weight and shall not exceed the...

  6. Updated Atomic Weights: Time to Review Our Table

    DOE PAGES

    Tyler B. Coplen; Holden, Norman E.; Meyers, Fabienne

    2016-04-05

    Many readers might wonder what can be new about atomic weights and why such a subject deserves even a short paper in Chemistry Views magazine. However, despite common belief, atomic weights are not constants of nature. Scientists' ability to measure these values is regularly improving, so one would expect that the accuracy of these values should be improving with time.

  7. Updated Atomic Weights: Time to Review Our Table

    SciTech Connect

    Tyler B. Coplen; Holden, Norman E.; Meyers, Fabienne

    2016-04-05

    Many readers might wonder what can be new about atomic weights and why such a subject deserves even a short paper in Chemistry Views magazine. However, despite common belief, atomic weights are not constants of nature. Scientists' ability to measure these values is regularly improving, so one would expect that the accuracy of these values should be improving with time.

  8. THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.

    SciTech Connect

    HOLDEN, N.E.

    2005-08-07

    Following Thomson's discovery of stable isotopes in non-radioactive chemical elements, the derivation of atomic weight values from mass spectrometric measurements of isotopic abundance ratios moved very slowly. Forty years later, only 3 1/2 % of the recommended values were based on mass spectrometric measurements and only 38% in the first half century. It might be noted that two chemical elements (tellurium and mercury) are still based on chemical measurements, where the atomic weight value calculated from the relative isotopic abundance measurement either agrees with the value from the chemical measurement or the atomic weight value calculated from the relative isotopic abundance measurement falls within the uncertainty of the chemical measurement of the atomic weight. Of the 19 chemical elements, whose atomic weight is based on non-corrected relative isotopic abundance measurements, five of these are two isotope systems (indium, iridium, lanthanum, lutetium and tantalum) and one is a three-isotope system (oxygen).

  9. Atomic weights of the elements--Review 2000 (IUPAC Technical Report)

    USGS Publications Warehouse

    de Laeter, John R.; Böhlke, John Karl; De Bièvre, P.; Hidaka, H.; Peiser, H.S.; Rosman, K.J.R.; Taylor, P.D.P.

    2003-01-01

    A consistent set of internationally accepted atomic weights has long been an essential aim of the scientific community because of the relevance of these values to science and technology, as well as to trade and commerce subject to ethical, legal, and international standards. The standard atomic weights of the elements are regularly evaluated, recommended, and published in updated tables by the Commission on Atomic Weights and Isotopic Abundances (CAWIA) of the International Union of Pure and Applied Chemistry (IUPAC). These values are invariably associated with carefully evaluated uncertainties. Atomic weights were originally determined by mass ratio measurements coupled with an understanding of chemical stoichiometry, but are now based almost exclusively on knowledge of the isotopic composition (derived from isotope-abundance ratio measurements) and the atomic masses of the isotopes of the elements. Atomic weights and atomic masses are now scaled to a numerical value of exactly 12 for the mass of the carbon isotope of mass number 12. Technological advances in mass spectrometry and nuclear-reaction energies have enabled atomic masses to be determined with a relative uncertainty of better than 1 ×10−7 . Isotope abundances for an increasing number of elements can be measured to better than 1 ×10−3 . The excellent precision of such measurements led to the discovery that many elements, in different specimens, display significant variations in their isotope-abundance ratios, caused by a variety of natural and industrial physicochemical processes. While such variations increasingly place a constraint on the uncertainties with which some standard atomic weights can be stated, they provide numerous opportunities for investigating a range of important phenomena in physical, chemical, cosmological, biological, and industrial processes. This review reflects the current and increasing interest of science in the measured differences between source-specific and even sample

  10. Isotope-abundance variations and atomic weights of selected elements: 2016 (IUPAC Technical Report)

    USGS Publications Warehouse

    Coplen, Tyler B.; Shrestha, Yesha

    2016-01-01

    There are 63 chemical elements that have two or more isotopes that are used to determine their standard atomic weights. The isotopic abundances and atomic weights of these elements can vary in normal materials due to physical and chemical fractionation processes (not due to radioactive decay). These variations are well known for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium), and the standard atomic weight of each of these elements is given by IUPAC as an interval with lower and upper bounds. Graphical plots of selected materials and compounds of each of these elements have been published previously. Herein and at the URL http://dx.doi.org/10.5066/F7GF0RN2, we provide isotopic abundances, isotope-delta values, and atomic weights for each of the upper and lower bounds of these materials and compounds.

  11. Atomic frequency standard relativistic Doppler shift experiment

    NASA Technical Reports Server (NTRS)

    Peters, H. E.; Reinhardt, V. S.

    1974-01-01

    An experiment has been performed to measure possible space anisotropy as it would effect the frequency of a cesium atomic beam standard clock in a laboratory on earth due to motion relative to external coordinate frames. The cesium frequency was measured as a function of orientation with respect to an atomic hydrogen maser standard. Over a period of 34 days 101 measurements were made. The results are consistent with a conclusion that no general orientation dependance attributable to spacial anisotropy was observed. It is shown that both the airplane clock results, and the null results for the atomic beam clock, are consistent with Einstein general or special relativity, or with the Lorentz transformations alone.

  12. JPL Ultrastable Trapped Ion Atomic Frequency Standards.

    PubMed

    Burt, Eric A; Yi, Lin; Tucker, Blake; Hamell, Robert; Tjoelker, Robert L

    2016-07-01

    Recently, room temperature trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on three directions: 1) ultrastable atomic clocks, usually for terrestrial applications emphasizing ultimate stability performance and autonomous timekeeping; 2) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements; and 3) miniature clocks. In this paper, we concentrate on the first direction and present a design and the initial results from a new ultrastable clock referred to as L10 that achieves a short-term stability of 4.5 ×10(-14)/τ(1/2) and an initial measurement of no significant drift with an uncertainty of 2.4 ×10(-16) /day over a two-week period.

  13. Updated atomic weights: Time to review our table

    USGS Publications Warehouse

    Coplen, Tyler B.; Meyers, Fabienne; Holden, Norman E.

    2016-01-01

    Despite common belief, atomic weights are not necessarily constants of nature. Scientists’ ability to measure these values is regularly improving, so one would expect that the accuracy of these values should be improving with time. It is the task of the IUPAC (International Union of Pure and Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights (CIAAW) to regularly review atomic-weight determinations and release updated values.According to an evaluation published in Pure and Applied Chemistry [1], even the most simplified table abridged to four significant digits needs to be updated for the elements selenium and molybdenum. According to the most recent 2015 release of "Atomic Weights of the Elements" [2], another update is needed for ytterbium.

  14. Accurate rubidium atomic fountain frequency standard

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Yuri; Marra, Giuseppe

    2011-06-01

    The design, operating parameters and the accuracy evaluation of the NPL Rb atomic fountain are described. The atomic fountain employs a double magneto-optical arrangement that allows a large number of 87Rb atoms to be trapped, a water-cooled temperature-stabilized interrogation region and a high quality factor interrogation cavity. From the uncertainties of measured and calculated systematic frequency shifts, the fractional frequency accuracy is estimated to be 3.7 × 10-16. The fractional frequency stability, limited predominantly by noise in the local oscillator, is measured to be 7 × 10-16 after one day of averaging. Based on the proposed quasi-continuous regime of operation of the fountain, the accuracy of the Rb standard of 5 × 10-17 reachable in two days of averaging is predicted.

  15. Primary mass standard based on atomic masses

    NASA Astrophysics Data System (ADS)

    Becker, Peter; Gläser, Michael

    2006-04-01

    The paper summarises the activities of several national and international Metrology Institutes in replacing the kilogram artefact, the unit of mass, by the mass of a certain number of atoms, in particular the atomic masses of silicon or bismuth. This task is based on two different experiments: a very accurate determination of the Avogadro constant, NA, measuring the density and lattice parameter of an enriched silicon-28 crystal, and the accumulation of decelerated bismuth-209 ions by using a mass separator. The relative measurement uncertainties reached so far are in the first case 2 parts in 107, and in the latter several part in 104. The bismuth experiment is still in an early state of the work. The ratios between the masses of 28Si or 209Bi, respectively, and the present atomic mass standard, the mass of 12C, can be determined with an accuracy now approaching 10-10 using high precision Penning traps mass spectrometers.

  16. Optical Frequency Standards Based on Neutral Atoms and Molecules

    NASA Astrophysics Data System (ADS)

    Riehle, Fritz; Helmcke, Juergen

    The current status and prospects of optical frequency standards based on neutral atomic and molecular absorbers are reviewed. Special attention is given to an optical frequency standard based on cold Ca atoms which are interrogated with a pulsed excitation scheme leading to resolved line structures with a quality factor Q > 10^12. The optical frequency was measured by comparison with PTB's primary clock to be νCa = 455 986 240 494.13 kHz with a total relative uncertainty of 2.5 x10^-13. After a recent recommendation of the International Committee of Weights and Measures (CIPM), this frequency standard now represents one of the most accurate realizations of the length unit.

  17. STATUS OF RADIOACTIVE ELEMENTS IN THE ATOMIC WEIGHTS TABLE.

    SciTech Connect

    HOLDEN,N.E.

    2003-08-08

    During discussions within the Inorganic Chemistry Division Committee, that dealt with the Periodic Table of the Chemical Elements and the official IUPAC position on its presentation, the following question was raised. When the various chemical elements are presented, each with their appropriate atomic weight value, how should the radioactive elements be presented? The Atomic Weights Commission has treated this question in a number of different ways during the past century, almost in a random manner. This report reviews the position that the Commission has taken as a function of time, as a prelude to a discussion in Ottawa about how the Commission should resolve this question for the future.

  18. Weight Reduction Techniques Adopted When Weight Standards are Enforced

    DTIC Science & Technology

    1993-01-01

    ORGANIZATION NAME(S) AND ADDRESS(ES) 8, PERFORMING ORGANIZATION Military Nutrition Division REPORT NUMBER U. S. Army Research Institute of Environmental...affecting more soldiers than those Identified by the AWCP and possibly developing during a career In the Army. Nutrition /education programs should...that appeas to be Inevitable with aging and a career in the’Army. 14. SUBJECT TERMS 15. NUMBIEN OF PAGES Nutrition , weight reduction, Army weight

  19. Weight Measurements and Standards for Soldiers

    DTIC Science & Technology

    2009-10-01

    Medical Brigade with an environmental/internet-based intervention to increase health risk communication and promote healthy body weight/ fatness and...Soldiers, health, weight, body fat 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE...the 94th RRC with an environmental/internet-based intervention to increase health risk communication and promote healthy body weight/ fatness and

  20. Weight Measurements and Standards for Military Personnel

    DTIC Science & Technology

    2007-10-01

    body weight/ fatness and physical performance, 3) monitor the fatness and physical performance of the Reservists for two years following a one-year...Nutrition, physical fitness, Soldiers, health, weight, body fat 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a...promote healthy body weight/ fatness and physical performance, 3) monitor the fatness and physical performance of the Reservists for two years

  1. Innovation and reliability of atomic standards for PTTI applications

    NASA Technical Reports Server (NTRS)

    Kern, R.

    1981-01-01

    Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.

  2. Weight Measurements and Standards for Soldiers

    DTIC Science & Technology

    2013-10-01

    available for all population Soldiers during periods designated by the research study design. nutrition , physical fitness, Soldiers, health , weight, body...Leveraging Technology: Creating and Sustaining changes for Health ”, to present a talk on nutrition intake tracking and the H.E.A.L.T.H. program...Army National Guard (LANG) called Healthy Eating , Activity, and Lifestyle Training Headquarters (H.E.A.L.T.H.) (1). This program was designed to

  3. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    NASA Technical Reports Server (NTRS)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  4. Magnetic state selection in atomic frequency and time standards. [hydrogen masers

    NASA Technical Reports Server (NTRS)

    Peters, H. E.

    1982-01-01

    Atomic standards such as those based upon cesium and hydrogen rely upon magnetic state selection to obtain population inversion in the hyperfine transition levels. Use of new design approaches and improved magnetic materials has made it possible to fabricate improved state selectors of small size, and thus the efficiency of utilization of beam flux is greatly improved and the size and weight of the standard is reduced. The sensitivity to magnetic perturbations is also decreased, so that the accuracy and stability of the standard is improved. Several new state selector designs are illustrated and the application to standards utilizing different atomic species is analyzed.

  5. Variation in the terrestrial isotopic composition and atomic weight of argon

    USGS Publications Warehouse

    Böhlke, John Karl

    2014-01-01

    The isotopic composition and atomic weight of argon (Ar) are variable in terrestrial materials. Those variations are a source of uncertainty in the assignment of standard properties for Ar, but they provide useful information in many areas of science. Variations in the stable isotopic composition and atomic weight of Ar are caused by several different processes, including (1) isotope production from other elements by radioactive decay (radiogenic isotopes) or other nuclear transformations (e.g., nucleogenic isotopes), and (2) isotopic fractionation by physical-chemical processes such as diffusion or phase equilibria. Physical-chemical processes cause correlated mass-dependent variations in the Ar isotope-amount ratios (40Ar/36Ar, 38Ar/36Ar), whereas nuclear transformation processes cause non-mass-dependent variations. While atmospheric Ar can serve as an abundant and homogeneous isotopic reference, deviations from the atmospheric isotopic ratios in other Ar occurrences limit the precision with which a standard atomic weight can be given for Ar. Published data indicate variation of Ar atomic weights in normal terrestrial materials between about 39.7931 and 39.9624. The upper bound of this interval is given by the atomic mass of 40Ar, as some samples contain almost pure radiogenic 40Ar. The lower bound is derived from analyses of pitchblende (uranium mineral) containing large amounts of nucleogenic 36Ar and 38Ar. Within this interval, measurements of different isotope ratios (40Ar/36Ar or 38Ar/36Ar) at various levels of precision are widely used for studies in geochronology, water–rock interaction, atmospheric evolution, and other fields.

  6. Fit to WHO weight standard of European infants over time

    PubMed Central

    Levin, Daniel; Marryat, Louise; Cole, Tim J; McColl, John; Harjunmaa, Ulla; Ashorn, Per; Wright, Charlotte

    2016-01-01

    Objectives The 2006 WHO growth charts were created to provide an international standard for optimal growth, based on healthy, breastfed populations, but it has been suggested that Northern European children fit them poorly. This study uses infant weight data spanning 50 years to determine how well-nourished preschool children from different eras fit the WHO standard, and discuss the implications of deviations. Design Four longitudinal datasets from the UK and one from Finland were used comprising over 8000 children born between1959 and 2003. Weights from birth to 2 years were converted to age–sex-adjusted Z scores using the WHO standard and summarised using Generalized Additive Models for Location, Scale and Shape. Results Weights showed a variable fit to the WHO standard. Mean weights for all cohorts were above the WHO median at birth, but dipped by up to 0.5 SD to a nadir at 8 weeks before rising again. Birth weights increased in successive cohorts and the initial dip became slightly shallower. By age 1 year, cohorts were up to 0.75 SD above the WHO median, but there was no consistent pattern by era. Conclusions The WHO standard shows an acceptable, but variable fit for Northern European infants. While birth weights increased over time, there was, unexpectedly, no consistent variation by cohort beyond this initial period. Discrepancies in weight from the standard may reflect differences in measurement protocol and trends in infant feeding practice. PMID:26883079

  7. ISO/GUM UNCERTAINTIES AND CIAAW (UNCERTAINTY TREATMENT FOR RECOMMENDED ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES)

    SciTech Connect

    HOLDEN,N.E.

    2007-07-23

    The International Organization for Standardization (ISO) has published a Guide to the expression of Uncertainty in Measurement (GUM). The IUPAC Commission on Isotopic Abundance and Atomic Weight (CIAAW) began attaching uncertainty limits to their recommended values about forty years ago. CIAAW's method for determining and assigning uncertainties has evolved over time. We trace this evolution to their present method and their effort to incorporate the basic ISO/GUM procedures into evaluations of these uncertainties. We discuss some dilemma the CIAAW faces in their present method and whether it is consistent with the application of the ISO/GUM rules. We discuss the attempt to incorporate variations in measured isotope ratios, due to natural fractionation, into the ISO/GUM system. We make some observations about the inconsistent treatment in the incorporation of natural variations into recommended data and uncertainties. A recommendation for expressing atomic weight values using a tabulated range of values for various chemical elements is discussed.

  8. Atomic frequency standards for ultra-high-frequency stability

    NASA Technical Reports Server (NTRS)

    Maleki, L.; Prestage, J. D.; Dick, G. J.

    1987-01-01

    The general features of the Hg-199(+) trapped-ion frequency standard are outlined and compared to other atomic frequency standards, especially the hydrogen maser. The points discussed are those which make the trapped Hg-199(+) standard attractive: high line Q, reduced sensitivity to external magnetic fields, and simplicity of state selection, among others.

  9. CAFS: A Cesium Atomic Frequency Standard for GPS block IIR

    NASA Technical Reports Server (NTRS)

    Wisnia, Jeffry A.

    1993-01-01

    Kernco, Inc. was selected to design the Cesium Atomic Frequency Standards (CAFS) for the GPS Block IIR NAVSTAR satellites. These spacecraft are scheduled to be launched in the mid-1990's to replenish and upgrade the existing constellation of Global Positioning System satellites. The Block IIR CAFS output frequency is 13.4003378 MHz, the 686th submultiple of the cesium atomic resonance frequency. Using an integer submultiple simplifies the design of the atomic frequency standard's rf multiplier circuits, eliminating the secondary frequency synthesizer needed in previous designs. The GPS Block IIR CAFS design, particularly the improvements made on our earlier Block II design is described. Test results are included.

  10. Weight Measurements and Standards for Soldiers, Phase 2

    DTIC Science & Technology

    2014-10-01

    standards, nutrition , physical fitness,health, weight, body fat 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF...designed to aid military personnel in achieving healthy management of body weight, healthy nutrition , physical fitness, and combat readiness. The...their diet/ nutrition and exercise/fitness goals. Further, with the use 9 of portable computers and the Soldier’s Smartphones, Field Managers are

  11. Proposed standard-weight equations for brook trout

    USGS Publications Warehouse

    Hyatt, M.W.; Hubert, W.A.

    2001-01-01

    Weight and length data were obtained for 113 populations of brook trout Salvelinus fontinalis across the species' geographic range in North America to estimate a standard-weight (Ws) equation for this species. Estimation was done by applying the regression-line-percentile technique to fish of 120-620 mm total length (TL). The proposed metric-unit (g and mm) equation is log10Ws = -5.186 + 3.103 log10TL; the English-unit (lb and in) equivalent is log10Ws = -3.483 + 3.103 log10TL. No systematic length bias was evident in the relative-weight values calculated from these equations.

  12. A century of progress in the sciences due to atomic weight and isotopic composition measurements.

    PubMed

    De Laeter, J R; Peiser, H S

    2003-01-01

    Even before the 20th century, a consistent set of internationally accepted atomic weights was an important objective of the scientific community because of the fundamental importance of these values to science, technology and trade. As the 20th century progressed, physicists, geoscientists, and metrologists collaborated with chemists to revolutionize the science of atomic weights. At the beginning of the century, atomic weights were determined from mass relationships between chemical reactants and products of known stoichiometry. They are now derived from the measured isotopic composition of elements and the atomic masses of the isotopes. Accuracy in measuring atomic weights has improved continually, leading to the revelation of small but significant variations in the isotope abundances of many elements in their normal terrestrial occurrences caused by radioactivity and a variety of physicochemical and biochemical fractionation mechanisms. This atomic-weight variability has now been recognized as providing new scientific insights into and knowledge of the history of materials. Atomic weights, except those of the monoisotopic elements, are thus no longer regarded as "constants of nature". At the beginning of the 20th century, two scales for atomic weights were in common use: that based on the atomic weight of hydrogen being 1 and that based on the atomic weight of oxygen being 16. Atomic weights are now scaled to (12)C, which has the value 12 exactly. Accurate atomic weights of silicon, silver, and argon, have enabled the values of the Avogadro, Faraday and Universal Gas constants, respectively, to be established, with consequent effects on other fundamental constants.

  13. Predicting the Atomic Weights of the Trans-Lawrencium Elements: A Novel Application of Dobereiner's Triads

    ERIC Educational Resources Information Center

    Ibrahim, Sami A.

    2005-01-01

    Johann Wolfgang Dobereiner, in 1829, made the first significant attempt to reveal a relation between the properties of the chemical elements and their atomic weights. His groupings remain useful for providing reasonable estimates for the properties and the atomic weights of the trans-lawrencium elements.

  14. The atomic weight and isotopic composition of boron and their variation in nature

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The boron isotopic composition and atomic weight value and their variation in nature are reviewed. Questions are raised about the previously recommended value and the uncertainty for the atomic weight. The problem of what constitutes an acceptable range for normal material and what should then be considered geologically exceptional is discussed. Recent measurements make some previous decisions in need of re-evaluation.

  15. Standard weight (Ws) equations for four rare desert fishes

    USGS Publications Warehouse

    Didenko, A.V.; Bonar, Scott A.; Matter, W.J.

    2004-01-01

    Standard weight (Ws) equations have been used extensively to examine body condition in sport fishes. However, development of these equations for nongame fishes has only recently been emphasized. We used the regression-line-percentile technique to develop standard weight equations for four rare desert fishes: flannelmouth sucker Catostomus latipinnis, razorback sucker Xyrauchen texanus, roundtail chub Gila robusta, and humpback chub G. cypha. The Ws equation for flannelmouth suckers of 100-690 mm total length (TL) was developed from 17 populations: log10Ws = -5.180 + 3.068 log10TL. The Ws equation for razorback suckers of 110-885 mm TL was developed from 12 populations: log 10Ws = -4.886 + 2.985 log10TL. The W s equation for roundtail chub of 100-525 mm TL was developed from 20 populations: log10Ws = -5.065 + 3.015 log10TL. The Ws equation for humpback chub of 120-495 mm TL was developed from 9 populations: log10Ws = -5.278 + 3.096 log 10TL. These equations meet criteria for acceptable standard weight indexes and can be used to calculate relative weight, an index of body condition.

  16. Investigations of laser pumped gas cell atomic frequency standard

    NASA Technical Reports Server (NTRS)

    Volk, C. H.; Camparo, J. C.; Fueholz, R. P.

    1982-01-01

    The performance characteristics of a rubidium gas cell atomic frequency standard might be improved by replacing the standard rubidium discharge lamp with a single mode laser diode. Aspects of the laser pumped gas cell atomic clock studied include effects due to laser intensity, laser detuning, and the choice of the particular atomic absorption line. Results indicate that the performance of the gas cell clock may be improved by judicious choice of the operating parameters of the laser diode. The laser diode also proved to be a valuable tool in investigating the operation of the conventional gas cell clock. Results concerning linewidths, the light shift effect and the effect of isotopic spin exchange in the conventional gas cell clock are reported.

  17. Atom-Probe Measurements of Meteoritic Nanodiamonds and Terrestrial Standards

    NASA Astrophysics Data System (ADS)

    Lewis, J. B.; Isheim, D.; Floss, C.; Daulton, T. L.; Seidman, D. N.; Heck, P. R.; Davis, A. M.; Pellin, M. J.; Savina, M. R.; Hiller, J.; Mane, A.; Elam, J. W.; Stephan, T.

    2013-09-01

    We present new data from the novel application of atom-probe tomography to the study of nanodiamonds from the meteorite Allende. The mean meteoritic ^12C/^13C peak ratio is higher than that of our standards, but there are instrumental artifacts.

  18. The problem of frequency weighting functions and standards for birds

    NASA Astrophysics Data System (ADS)

    Dooling, Robert; Brittan-Powell, Elizabeth; Lauer, Amanda; Dent, Micheal; Noirot, Isabelle

    2005-09-01

    Frequency weighting functions in humans are widely used as a single-figure guess to assess noise problems and aid in making decisions with regard to noise limitations when no other data exist. However, this use of frequency weightings invariably results in a loss of precision in assessing the likelihood of a sound to produce hearing damage or sound annoyance. There is a growing interest in developing frequency weighting functions in animals presumably to assist in judging the risk of hearing damage, interference with acoustic communication, or habitat suitability. Laboratory studies reveal many parallels between humans and animals on a variety of psychoacoustic measures, such as equal loudness contours. However, differences between humans and animals on specific tests argue against using standards developed for humans to gauge the effect of noise on animals. Here we review data which show this same problem exists among birds. That is, the differences in the effects of noise among bird species can be as large as the differences between humans and birds. These results suggest that whereas frequency weighting functions and acoustic standards for a specific species might be useful, generalizing across species is likely not practical.

  19. Compact frequency standard using atoms trapped on a chip

    NASA Astrophysics Data System (ADS)

    Ramírez-Martínez, F.; Lacroûte, C.; Rosenbusch, P.; Reinhard, F.; Deutsch, C.; Schneider, T.; Reichel, J.

    2011-01-01

    We present a compact atomic frequency standard based on the interrogation of magnetically trapped 87Rb atoms. Two photons, in the microwave and radiofrequency domain excite the atomic transition. At a magnetic field of 3.23 G this transition from ∣F = 1, mF = -1> to ∣F = 2, mF = 1> is 1st order insensitive to magnetic field variations. Long Ramsey interrogation times can thus be achieved, leading to a projected stability in the low 10-13 at 1 s. This makes this device a viable alternative to LITE and HORACE as a good candidate for replacing or complementing the rubidium frequency standards and passive hydrogen masers already on board of the GPS, GLONASS, and GALILEO satellites. Here we present preliminary results. We use an atom chip to cool and trap the atoms. A coplanar waveguide is integrated to the chip to carry the Ramsey interrogation signal, making the physics package potentially as small as (5 cm)3. We describe the experimental apparatus and show preliminary Ramsey fringes of 1.25 Hz linewidth. We also show a preliminary frequency stability σy = 1.5 × 10-12τ-1/2 for 10 < τ < 103 s. This represents one order of magnitude improvement with respect to previous experiments.

  20. An optical frequency standard based on ultracold magnesium atoms

    NASA Astrophysics Data System (ADS)

    Goncharov, A. N.; Bonert, A. E.; Brazhnikov, D. V.; Prudnikov, O. N.; Tropnikov, M. A.; Kuznetsov, S. A.; Taichenachev, A. V.; Bagayev, S. N.

    2017-01-01

    This paper presents the recent experimental results on development of an optical frequency standard based on ultra cold magnesium atoms with relative frequency uncertainty and long term stability at the level of Δv/v <10‑16. We stabilized the frequency of our clock laser system at 655 THz to narrow Ramsey fringes in a time separated laser fields interacting with cooled Mg atoms localized in a magneto-optical trap (MOT). The intercombination line 1S0→3P1 was used as the reference for frequency stabilization. The results of stabilization were studied with femtosecond comb based on Ti:Sa laser.

  1. Bringing Standardized Processes in Atom-Probe Tomography: I Establishing Standardized Terminology

    SciTech Connect

    Anderson, Ian M; Danoix, F; Forbes, Richard; Gault, Baptiste; Kelly, T. F.; Marquis, E A; Miller, Michael K; Moody, M. P.; Vurpillot, F

    2011-01-01

    Defining standardized methods requires careful consideration of the entire field and its applications. The International Field Emission Society (IFES) has elected a Standards Committee, whose task is to determine the needed steps to establish atom-probe tomography as an accepted metrology technique. Specific tasks include developing protocols or standards for: terminology and nomenclature; metrology and instrumentation, including specifications for reference materials; test methodologies; modeling and simulations; and science-based health, safety, and environmental practices. The Committee is currently working on defining terminology related to atom-probe tomography with the goal to include terms into a document published by the International Organization for Standards (ISO). A lot of terms also used in other disciplines have already been defined) and will be discussed for adoption in the context of atom-probe tomography.

  2. Absolute Isotopic Abundance Ratios and Atomic Weight of a Reference Sample of Nickel

    PubMed Central

    Gramlich, J. W.; Machlan, L. A.; Barnes, I. L.; Paulsen, P. J.

    1989-01-01

    Absolute values have been obtained for the isotopic abundance ratios of a reference sample of nickel (Standard Reference Material 986), using thermal ionization mass spectrometry. Samples of known isotopic composition, prepared from nearly isotopically pure separated nickel isotopes, were used to calibrate the mass spectrometers. The resulting absolute isotopic ratios are: 58Ni/60Ni=2.596061±0.000728, 61Ni/60Ni=0.043469±0.000015,62Ni/60Ni=0.138600±0.000045, and 64Ni/60Ni=0.035295±0.000024, which yield atom percents of 58Ni=68.076886 ±0.005919, 60Ni = 26.223146±0.005144,61Ni=1.139894±0.000433, 62Ni =3.634528±0.001142, and 64Ni =0.925546±0.000599. The atomic weight calculated from this isotopic composition is 58.693353 ±0.000147. The indicated uncertainties are overall limits of error based on two standard deviations of the mean and allowances for the effects of known sources of possible systematic error. PMID:28053421

  3. Portable atomic frequency standard based on coherent population trapping

    NASA Astrophysics Data System (ADS)

    Shi, Fan; Yang, Renfu; Nian, Feng; Zhang, Zhenwei; Cui, Yongshun; Zhao, Huan; Wang, Nuanrang; Feng, Keming

    2015-05-01

    In this work, a portable atomic frequency standard based on coherent population trapping is designed and demonstrated. To achieve a portable prototype, in the system, a single transverse mode 795nm VCSEL modulated by a 3.4GHz RF source is used as a pump laser which generates coherent light fields. The pump beams pass through a vapor cell containing atom gas and buffer gas. This vapor cell is surrounded by a magnetic shield and placed inside a solenoid which applies a longitudinal magnetic field to lift the Zeeman energy levels' degeneracy and to separate the resonance signal, which has no first-order magnetic field dependence, from the field-dependent resonances. The electrical control system comprises two control loops. The first one locks the laser wavelength to the minimum of the absorption spectrum; the second one locks the modulation frequency and output standard frequency. Furthermore, we designed the micro physical package and realized the locking of a coherent population trapping atomic frequency standard portable prototype successfully. The short-term frequency stability of the whole system is measured to be 6×10-11 for averaging times of 1s, and reaches 5×10-12 at an averaging time of 1000s.

  4. Mean Atomic Weight of Chondrules and Matrices in Semarkona, Allende and Sharps Meteorites

    NASA Astrophysics Data System (ADS)

    Szurgot, M.

    2017-02-01

    Mean atomic weight Amean of chondrules and matrices of Semarkona, Allende and Sharps meteorites was determined using chemical composition and Amean(Fe/Si) dependence. Amean values of matrices are higher than chondrules and meteorites.

  5. ADME evaluation in drug discovery. 2. Prediction of partition coefficient by atom-additive approach based on atom-weighted solvent accessible surface areas.

    PubMed

    Hou, T J; Xu, X J

    2003-01-01

    A novel method for the calculations of 1-octanol/water partition coefficient (log P) of organic molecules has been presented here. The method, SLOGP v1.0, estimates the log P values by summing the contribution of atom-weighted solvent accessible surface areas (SASA) and correction factors. Altogether 100 atom/group types were used to classify atoms with different chemical environments, and two correlation factors were used to consider the intermolecular hydrophobic interactions and intramolecular hydrogen bonds. Coefficient values for 100 atom/group and two correction factors have been derived from a training set of 1850 compounds. The parametrization procedure for different kinds of atoms was performed as follows: first, the atoms in a molecule were defined to different atom/group types based on SMARTS language, and the correction factors were determined by substructure searching; then, SASA for each atom/group type was calculated and added; finally, multivariate linear regression analysis was applied to optimize the hydrophobic parameters for different atom/group types and correction factors in order to reproduce the experimental log P. The correlation based on the training set gives a model with the correlation coefficient (r) of 0.988, the standard deviation (SD) of 0.368 log units, and the absolute unsigned mean error of 0.261. Comparison of various procedures of log P calculations for the external test set of 138 organic compounds demonstrates that our method bears very good accuracy and is comparable or even better than the fragment-based approaches. Moreover, the atom-additive approach based on SASA was compared with the simple atom-additive approach based on the number of atoms. The calculated results show that the atom-additive approach based on SASA gives better predictions than the simple atom-additive one. Due to the connection between the molecular conformation and the molecular surface areas, the atom-additive model based on SASA may be a more

  6. Topics in atomic hydrogen standard research and applications

    NASA Technical Reports Server (NTRS)

    Peters, H. E.

    1971-01-01

    Hydrogen maser based frequency and time standards have been in continuous use at NASA tracking stations since February 1970, while laboratory work at Goddard has continued in the further development and improvement of hydrogen masers. Concurrently, experimental work has been in progress with a new frequency standard based upon the hydrogen atom using the molecular beam magnetic resonance method. Much of the hydrogen maser technology is directly applicable to the new hydrogen beam standard, and calculations based upon realistic data indicate that the accuracy potential of the hydrogen atomic beam exceeds that of either the cesium beam tube or the hydrogen maser, possibly by several orders of magnitude. In addition, with successful development, the hydrogen beam standard will have several other performance advantages over other devices, particularly exceptional stability and long continuous operating life. Experimental work with a new laboratory hydrogen beam device has recently resulted in the first resonance transition curves, measurements of relative state populations, beam intensities, etc. The most important aspects of both the hydrogen maser and the hydrogen beam work are covered.

  7. Rubidium atomic frequency standards for GPS Block IIR

    NASA Technical Reports Server (NTRS)

    Riley, William J.

    1990-01-01

    The Rubidium Atomic Frequency Standards (RAFS) were provided for the GPS Block IIR NAVSTAR satellites. These satellites will replenish and upgrade the space segment of the Global Positioning System in the mid 1990s. The GPS RAFS Rb clocks are the latest generation of the high-performance rubidium frequency standards. They offer an aging rate in the low pp 10(exp 14)/day range and a drift-corrected 1-day stability in the low pp 10(exp 14) range. The Block IIR version of these devices will have improved performance, higher reliability, smaller size, and greater radiation hardness. The GPS Block IIR atomic clocks have a natural frequency configuration whereby they output a frequency of about 13.4 MHz that is a submultiple of the atomic resonance of Rb (or Cs). The RAFS operates at a low, fixed C-field for increased stability. The GPS Block IIR RAFS design, including the changes and improvements made, and the test results obtained are described.

  8. Weighted total least squares formulated by standard least squares theory

    NASA Astrophysics Data System (ADS)

    Amiri-Simkooei, A.; Jazaeri, S.

    2012-01-01

    This contribution presents a simple, attractive, and flexible formulation for the weighted total least squares (WTLS) problem. It is simple because it is based on the well-known standard least squares theory; it is attractive because it allows one to directly use the existing body of knowledge of the least squares theory; and it is flexible because it can be used to a broad field of applications in the error-invariable (EIV) models. Two empirical examples using real and simulated data are presented. The first example, a linear regression model, takes the covariance matrix of the coefficient matrix as QA = QnQm, while the second example, a 2-D affine transformation, takes a general structure of the covariance matrix QA. The estimates for the unknown parameters along with their standard deviations of the estimates are obtained for the two examples. The results are shown to be identical to those obtained based on the nonlinear Gauss-Helmert model (GHM). We aim to have an impartial evaluation of WTLS and GHM. We further explore the high potential capability of the presented formulation. One can simply obtain the covariance matrix of the WTLS estimates. In addition, one can generalize the orthogonal projectors of the standard least squares from which estimates for the residuals and observations (along with their covariance matrix), and the variance of the unit weight can directly be derived. Also, the constrained WTLS, variance component estimation for an EIV model, and the theory of reliability and data snooping can easily be established, which are in progress for future publications.

  9. Weighted data gravitation classification for standard and imbalanced data.

    PubMed

    Cano, Alberto; Zafra, Amelia; Ventura, Sebastián

    2013-12-01

    Gravitation is a fundamental interaction whose concept and effects applied to data classification become a novel data classification technique. The simple principle of data gravitation classification (DGC) is to classify data samples by comparing the gravitation between different classes. However, the calculation of gravitation is not a trivial problem due to the different relevance of data attributes for distance computation, the presence of noisy or irrelevant attributes, and the class imbalance problem. This paper presents a gravitation-based classification algorithm which improves previous gravitation models and overcomes some of their issues. The proposed algorithm, called DGC+, employs a matrix of weights to describe the importance of each attribute in the classification of each class, which is used to weight the distance between data samples. It improves the classification performance by considering both global and local data information, especially in decision boundaries. The proposal is evaluated and compared to other well-known instance-based classification techniques, on 35 standard and 44 imbalanced data sets. The results obtained from these experiments show the great performance of the proposed gravitation model, and they are validated using several nonparametric statistical tests.

  10. Cycle Time Reduction in Trapped Mercury Ion Atomic Frequency Standards

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Tjoelker, Robert L.; Taghavi, Shervin

    2011-01-01

    The use of the mercury ion isotope (201)Hg(+) was examined for an atomic clock. Taking advantage of the faster optical pumping time in (201)Hg(+) reduces both the state preparation and the state readout times, thereby decreasing the overall cycle time of the clock and reducing the impact of medium-term LO noise on the performance of the frequency standard. The spectral overlap between the plasma discharge lamp used for (201)Hg(+) state preparation and readout is much larger than that of the lamp used for the more conventional (199)Hg(+). There has been little study of (201)Hg(+) for clock applications (in fact, all trapped ion clock work in mercury has been with (199)Hg(+); however, recently the optical pumping time in (201)Hg(+) has been measured and found to be 0.45 second, or about three times faster than in (199)Hg(+) due largely to the better spectral overlap. This can be used to reduce the overall clock cycle time by over 2 seconds, or up to a factor of 2 improvement. The use of the (201)Hg(+) for an atomic clock is totally new. Most attempts to reduce the impact of LO noise have focused on reducing the interrogation time. In the trapped ion frequency standards built so far at JPL, the optical pumping time is already at its minimum so that no enhancement can be had by shortening it. However, by using (201)Hg(+), this is no longer the case. Furthermore, integrity monitoring, the mechanism that determines whether the clock is functioning normally, cannot happen faster than the clock cycle time. Therefore, a shorter cycle time will enable quicker detection of failure modes and recovery from them.

  11. History of the recommended atomic-weight values from 1882 to 1997: A comparision of differences from current values to the estimated uncertainties of earlier values.

    USGS Publications Warehouse

    Coplen, T.B.; Peiser, H.S.

    1998-01-01

    International commissions and national committees for atomic weights (mean relative atomic masses) have recommended regularly updated, best values for these atomic weights as applicable to terrestrial sources of the chemical elements. Presented here is a historically complete listing starting with the values in F. W. Clarke's 1882 recalculation, followed by the recommended values in the annual reports of the American Chemical Society's Atomic Weights Commission. From 1903, an International Commission published such reports and its values (scaled to an atomic weight of 16 for oxygen) are here used in preference to those of national committees of Britain, Germany, Spain, Switzerland, and the U.S.A. We have, however, made scaling adjustments from Ar(16O) to Ar(12C) where not negligible. From 1920, this International Commission constituted itself under the International Union of Pure and Applied Chemistry (IUPAC). Since then, IUPAC has published reports (mostly biennially) listing the recommended atomic weights, which are reproduced here. Since 1979, these values have been called the "standard atomic weights" and, since 1969, all values have been published, with their estimated uncertainties. Few of the earlier values were published with uncertainties. Nevertheless, we assessed such uncertainties on the basis of our understanding of the likely contemporary judgement of the values' reliability. While neglecting remaining uncertainties of 1997 values, we derive "differences" and a retrospective index of reliability of atomic-weight values in relation to assessments of uncertainties at the time of their publication. A striking improvement in reliability appears to have been achieved since the commissions have imposed upon themselves the rule of recording estimated uncertainties from all recognized sources of error.

  12. Weight Measurements and Standards for Soldiers, Phase 2

    DTIC Science & Technology

    2011-10-01

    report contains proprietary information 13. SUPPLEMENTARY NOTES 14. ABSTRACT The specific aims of the study are to: 1) compare body weight and fat ... body weight, body fat , and fitness in the control group when these participants are provided access to the H.E.A.L.T.H. intervention, and 4) evaluate the...maintenance of changes in body weight, body fat , and fitness after discontinuation of the promotion associated with the H.E.A.L.T.H. program. The

  13. Absolute isotopic composition and atomic weight of neodymium using thermal ionization mass spectrometry.

    PubMed

    Zhao, Motian; Zhou, Tao; Wang, Jun; Lu, Hai; Fang, Xiang; Guo, Chunhua; Li, Qiuli; Li, Chaofeng

    2005-01-01

    Synthetic mixtures prepared gravimetrically from highly enriched isotopes of neodymium in the form of oxides of well-defined purity were used to calibrate a thermal ionization mass spectrometer. A new error analysis was applied to calculate the final uncertainty of the atomic weight value. Measurements on natural neodymium samples yielded an absolute isotopic composition of 27.153(19) atomic percent (at.%) 142Nd, 12.173(18) at.% 143Nd, 23.798(12) at.% 144Nd, 8.293(7) at.% 145Nd, 17.189(17) at.% 146Nd, 5.756(8) at.% 148Nd, and 5.638(9) at.% 150Nd, and the atomic weight of neodymium as 144.2415(13), with uncertainties given on the basis of 95% confidence limits. No isotopic fractionation was found in terrestrial neodymium materials.

  14. Weight Loss Behaviors Used by Active Duty Air Force Personnel to Maintain Compliance with Weight Control Standards

    DTIC Science & Technology

    1997-05-01

    standards (AFI 40-502,1994). 90-Day Exercise Program A specifically designed conditioning and dietary program for members in the WMP (AFI 40-502, 1994...billion is spent annually in America for these programs. They did note that dietary changes were the most common weight loss strategy. This covers...method by body builders. Competitive swimmers have been studied to determine their perception of weight and how they control their weight (Dummer

  15. The Brazilian time and frequency atomic standards program.

    PubMed

    Ahmed, Mushtaq; Magalhães, Daniel V; Bebeachibuli, Aida; Müller, Stella T; Alves, Renato F; Ortega, Tiago A; Weiner, John; Bagnato, Vanderlei S

    2008-06-01

    Cesium atomic beam clocks have been the workhorse for many demanding applications in science and technology for the past four decades. Tests of the fundamental laws of physics and the search for minute changes in fundamental constants, the synchronization of telecommunication networks, and realization of the satellite-based global positioning system would not be possible without atomic clocks. The adoption of optical cooling and trapping techniques, has produced a major advance in atomic clock precision. Cold-atom fountain and compact cold-atom clocks have also been developed. Measurement precision of a few parts in 10(15) has been demonstrated for a cold-atom fountain clock. We present here an overview of the time and frequency metrology program based on cesium atoms under development at USP São Carlos. This activity consists of construction and characterization of atomic-beam, and several variations of cold-atom clocks. We discuss the basic working principles, construction, evaluation, and important applications of atomic clocks in the Brazilian program.

  16. Weight Management Behaviors Used by Active Duty Nurses to Maintain Compliance With Military Weight Control Standards

    DTIC Science & Technology

    2003-05-01

    room, and bulimia (Sweeney & Bonnabeau, 1990). Healthy weight loss techniques Conceptual: Weight loss strategies that include a healthy balance of...shown that these behaviors can lead to more serious eating disorders such as Anorexia or Bulimia . Based on results of previous studies done like this...minimally normal body weight) or bulimia nervosa (repeated episodes of binge eating followed by inappropriate compensatory behaviors)? ___ Yes ___ No

  17. Weight Measurements and Standards for Soldiers, Phase 2

    DTIC Science & Technology

    2015-10-01

    internet/population-based weight management program for the U.S. Army. Journal of Diabetes , Science and Technology 2(1), 116-126. 2. U.S. Army. The...Internet/Population-based Behavioral Weight Management Program for the U.S. Army. Journal of Diabetes Science and Technology 5, 178-187. 5. Newton, R...Reserve Soldiers: H.E.A.L.T.H. Journal of Diabetes Science and Technology, 5(5), 1255-1262. 6. Stewart, T. (2014). Preliminary Evidence on an

  18. Improved atomic resonance gas cell for use in frequency standards

    NASA Technical Reports Server (NTRS)

    Huggett, G. R.

    1968-01-01

    Atomic resonance gas cell maintains a stable operating frequency in the presence of pressure fluctuations in the ambient atmosphere. The new cell includes an envelope which is transparent to radiation in the optical region and to microwave energy at the atomic resonance frequency of the alkali-metal vapor within the envelope.

  19. Theodore William Richards: apostle of atomic weights and Nobel Prize winner in 1914.

    PubMed

    Herschbach, Dudley R

    2014-12-15

    In recognition of his exact determinations of the atomic weights of a large number of the chemical elements, T. W. Richards received the Nobel Prize in Chemistry in 1914. His meticulous techniques resulted in "a degree of accuracy never before attained". This Essay follows Richards from his precocious youth to becoming a celebrated chemist and emphasizes his dedication to forseeing likely sources of error and how to avoid them.

  20. Precision Laboratory Standards of Mass and Laboratory Weights

    DTIC Science & Technology

    1954-08-20

    Preferred denominations for laboratory weights Classes P. Q, and T Classes 11 and Q Class 1P Metric Avoirdupois Apothecary Troy Grain Carat kg l. 0Z 0...I g., or 500 ing 10 IngAvorduoi.--------------------------------------8, 4, 2, or 1 11), or S oz I j; oz5 Apothecary ...jeceiiUte Assay toni (29.1667 g) ----- ----- T’ Carat (200 nig) - - - - - - - - - - D~rain, apothecaries ’- -(-- ---- - Ir ap G rain

  1. Standardization of methods of expressing lengths and weights of fish

    USGS Publications Warehouse

    Hile, Ralph

    1948-01-01

    Fishery workers in the United States and Canada are unable to think readily in terms of the metric system of weights and measurements. Even long experience does not make it possible to form a clear idea as to the actual size of fish for which lengths and weights are given in metric units, without first converting to the English system. A more general adoption of the English system of weights and measurements in fishery work is recommended. The use of English units exclusively is suggested for articles of a popular or semi-popular nature, but in more formal publications the key information, at least, should be recorded in both systems. In highly technical papers metric units alone may prove satisfactory. Agreement is also lacking as to which length measurement of fish is suited best for uniform adoption. The total length is recommended here for the reason that it is the only measurement that includes all of the fish. This length is defined as the distance from the tip of the head (jaws closed) to the tip of the tail with the lobes compressed so as to give the maximum possible measurement.

  2. The Weighted Airman Promotion System: Standardizing Test Scores

    DTIC Science & Technology

    2008-01-01

    RAND Project AIR FORCE (PAF), is a follow-on to Air Force Enlisted Force Management: System Interactions and Synchronization Strategies (Schiefer et...conducted in four programs: Aerospace Force Develop- ment; Manpower, Personnel, and Training; Resource Management; and Strategy and Doctrine...74 Standardization Strategies

  3. Prospects for advances in microwave atomic frequency standards

    NASA Technical Reports Server (NTRS)

    Walls, F. L.

    1979-01-01

    Traditional standards based on rubidium, cesium and hydrogen have been greatly refined over the past decade, such that the frequency stability of the current generation of devices is generally limited by those basic concepts on which they are based. Future advances in frequency stability will principally come from changes in the concepts on which the standards are based, and only secondarily from more careful engineering of the old concepts. The fundamental limitations in these standards are considered and the important conceptual and component advances which could have a major impact on future performance of these standards are indicated. A very promising new class of microwave standards based on ion storage techniques is examined.

  4. Investigation and comparison of performance of effervescent and standard pneumatic atomizer intended for soluble aqueous coating.

    PubMed

    Nielsen, Anne Flachs; Poul, Bertelsen; Kristensen, Henning Gjelstrup; Kristensen, Jakob; Hovgaard, Lars

    2006-01-01

    Effervescent atomizers belong to the group of internal mixing atomizers. The effervescent approach might be a potential alternative to traditional atomization techniques, e.g., for applications where low atomization air consumption is advantageous In this paper, performance of one proposed design of the effervescent atomizer is investigated and compared to that of a standard pneumatic atomizer. The purpose of the comparison is to evaluate the actual potential of the specific effervescent atomizer in pharmaceutical relevant aqueous coating applications. Aqueous solutions of Hypromellose 5 as well as Povidone K-90F were characterized in terms of rheological properties and surface tension. Solutions were atomized by means of a standard Schlick pneumatic atomizer as well as a customized inside-out type effervescent atomizer. Spray droplet size distributions were recorded by a Spraytec instrument. Increased shear viscosity in the range 24-836 mPa.s had a modest effect on spray mean diameters for pneumatic sprays of the Newtonian solutions of Hypromellose 5. In contrast, mean droplet diameters increased by a factor of 3-5 in pneumatic sprays of Povidone K-90F solutions 11-175 mPa.s in viscosity, where non-Newtonian behavior was observed. Further, sprays of all solutions of Povidone K-90F have considerably larger mean droplet size. The effervescent atomizer atomized low viscosity solutions of Povidone K-90F more efficiently than Hypromellose 5 solutions of corresponding shear viscosity. However, atomization of high viscosity Povidone K-90F results in a coarser spray than that of the corresponding Hypromellose 5 solution. Viscosity, visco-elasticity, and surface tension of solutions all seem to affect atomization efficiency. The pneumatic atomizer was not sensitive to changes in airflow above 8.4 kg/h and liquid flow only had a considerable effect at suboptimal air flows. In its current design the effervescent atomizer improved efficiency throughout the investigated range

  5. A subsurface add-on for standard atomic force microscopes.

    PubMed

    Verbiest, G J; van der Zalm, D J; Oosterkamp, T H; Rost, M J

    2015-03-01

    The application of ultrasound in an Atomic Force Microscope (AFM) gives access to subsurface information. However, no commercially AFM exists that is equipped with this technique. The main problems are the electronic crosstalk in the AFM setup and the insufficiently strong excitation of the cantilever at ultrasonic (MHz) frequencies. In this paper, we describe the development of an add-on that provides a solution to these problems by using a special piezo element with a lowest resonance frequency of 2.5 MHz and by separating the electronic connection for this high frequency piezo element from all other connections. In this sense, we support researches with the possibility to perform subsurface measurements with their existing AFMs and hopefully pave also the way for the development of a commercial AFM that is capable of imaging subsurface features with nanometer resolution.

  6. A subsurface add-on for standard atomic force microscopes

    SciTech Connect

    Verbiest, G. J.; Zalm, D. J. van der; Oosterkamp, T. H.; Rost, M. J.

    2015-03-15

    The application of ultrasound in an Atomic Force Microscope (AFM) gives access to subsurface information. However, no commercially AFM exists that is equipped with this technique. The main problems are the electronic crosstalk in the AFM setup and the insufficiently strong excitation of the cantilever at ultrasonic (MHz) frequencies. In this paper, we describe the development of an add-on that provides a solution to these problems by using a special piezo element with a lowest resonance frequency of 2.5 MHz and by separating the electronic connection for this high frequency piezo element from all other connections. In this sense, we support researches with the possibility to perform subsurface measurements with their existing AFMs and hopefully pave also the way for the development of a commercial AFM that is capable of imaging subsurface features with nanometer resolution.

  7. A kind of magnetron cavity used in rubidium atomic frequency standards

    NASA Astrophysics Data System (ADS)

    Shiyu, Yang; Jingzhong, Cui; Jianhui, Tu; Yaoting, Liang

    2011-12-01

    Research on the magnetron cavity used in the rubidium atomic frequency standards is developed, through which the main characteristic parameters of the magnetron cavity are studied, mainly including the resonant frequency, quality factor and oscillation mode. The resonant frequency and quality factor of the magnetron cavity were calculated, and the test results of the resonant frequency agreed well with the calculation theory. The test results also show that the resonant frequency of the magnetron cavity can be attenuated to 6.835 GHz, which is the resonant frequency of the rubidium atoms, and the Q-factor can be attenuated to 500-1000. The oscillation mode is a typical TE011 mode and is the correct mode needed for the rubidium atomic frequency standard. Therefore these derivative magnetron cavities meet the requirements of the rubidium atomic frequency standards well.

  8. Progress toward a spin squeezed optical atomic clock beyond the standard quantum limit

    NASA Astrophysics Data System (ADS)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2015-05-01

    State of the art optical lattice atomic clocks have reached a relative inaccuracy level of 10-18, already making them the most stable time references in existence. One restriction on the precision of these clocks is the projection noise caused by the measurement of the atomic state. This limit, known as the standard quantum limit (SQL), can be overcome by entangling the atoms. By performing spin squeezing, it is possible to robustly generate such entanglement and therefore surpass the SQL of precision in optical atomic clocks. I will report on recent experimental progress toward realizing spin squeezing in an 171Yb optical lattice clock. A high-finesse micromirror-based optical cavity mediates the atom-atom interaction necessary for generating the entanglement. By exceeding the SQL in this state of the art system, we are aiming to advance precision time metrology, as well as expanding the boundaries of quantum control and measurement.

  9. Progress toward a spin squeezed optical atomic clock beyond the standard quantum limit

    NASA Astrophysics Data System (ADS)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2014-05-01

    State of the art optical lattice atomic clocks have reached a relative inaccuracy level of 10-18, already making them the most stable time references in existence. One restriction on the precision of these clocks is the projection noise caused by the measurement of the atomic state. This limit, known as the standard quantum limit (SQL), can be overcome by entangling the atoms. By performing spin squeezing, we can robustly generate such entanglement and surpass the SQL of precision in optical atomic clocks. I will report on recent experimental progress toward realizing spin squeezing in an 171Yb optical lattice clock. A high-finesse micromirror-based optical cavity mediates the atom-atom interaction necessary for generating the entanglement. By exceeding the SQL in this state of the art system, we are aiming to advance precision time metrology, as well as expanding the boundaries of quantum control and measurement. Supported by DARPA QUASAR and NSERC.

  10. Effects of obestatin on feeding and body weight after standard or cafeteria diet in the rat.

    PubMed

    Brunetti, Luigi; Leone, Sheila; Orlando, Giustino; Recinella, Lucia; Ferrante, Claudio; Chiavaroli, Annalisa; Di Nisio, Chiara; Di Michele, Pierpaolo; Vacca, Michele

    2009-07-01

    Obestatin is a gastric derived 23 amino acid peptide, which has shown anorectic effects in a number of experimental paradigms after both peripheral and central administration. On the other hand, several researchers were not able to confirm these data. Since all previous experiments have been performed in animals fed a standard laboratory diet, we studied obestatin effects in male Wistar rats fed both a standard laboratory chow (STD) diet (3.5% fat, 63% carbohydrate, 14% protein, 19.5% other components without caloric value; 3.20 kcal/g) and a highly palatable cafeteria-style (CAF) diet (30% fat, 56% carbohydrate, 14% protein; 4.20 kcal/g). Vehicle or obestatin (10, 50 or 100 nmol/kg) was injected intraperitoneally daily for 12 days. In STD diet rats, obestatin decreased daily caloric intake and body weight gain compared to vehicle treated rats. The anorectic and weight reducing effects of obestatin treatment were evidenced since day 6 and day 8 of treatment, respectively, and were consistent through the end of treatment. On the other hand, in CAF diet rats, obestatin treatment did not modify either daily caloric intake or body weight gain. In CAF diet rats, the percentage intake from standard food was decreased, balanced by an increase in cafeteria food intake. Obestatin treatment affected neither water consumption nor the intake of any specific food within the cafeteria diet. In conclusion, obestatin decreases caloric intake and body weight gain, but only in rats fed a STD diet.

  11. Response to a standard behavioral weight loss intervention by age of onset of obesity

    PubMed Central

    Taverno Ross, S. E.; Lang, W.; Jakicic, J. M.

    2016-01-01

    Summary Background The purpose of this study was to examine weight loss, physical activity, fitness and diet changes in response to a standard behavioral weight loss intervention in adults with self‐reported juvenile onset (n = 61) or adult onset (n = 116) obesity. Methods Participants (n = 177; 43.0 ± 8.6 years; body mass index [BMI] = 33.0 ± 3.4 kg m−2) engaged in an 18‐month standard behavioral weight loss intervention. Participants were randomized into three different intervention groups as part of the larger parent trial. BMI, physical activity, fitness and diet were assessed at baseline, 6, 12 and 18 months. Separate adjusted mixed models were constructed using SAS version 9.4 (SAS Institute, Cary, NC). Results There was significant weight loss, increased physical activity, improved fitness and reduced caloric intake over time (p < 0.001). There were no significant differences in these outcome variables by obesity onset group. However, there was a significant group by time interaction for fitness (p = 0.001), with the adult onset making significantly greater gains in fitness from baseline to 6 months (p < 0.001); however, this difference was no longer present at 12 or 18 months. Conclusions With the exception of fitness at 6 months, weight loss, physical activity and diet did not differ between juvenile onset and adult onset participants, suggesting that those with juvenile onset obesity are equally responsive to a standard behavioral weight loss intervention in adulthood. PMID:27708841

  12. Proposed standard-weight (Ws) equation and length-categorization standards for brown trout (Salmo trutta) in lentic habitats

    USGS Publications Warehouse

    Hyatt, M.W.; Hubert, W.A.

    2001-01-01

    We developed a standard-weight (Ws) equation for brown trout (Salmo trutta) in lentic habitats by applying the regression-line-percentile technique to samples from 49 populations in North America. The proposed Ws equation is log10 Ws = -5.422 + 3.194 log10 TL, when Ws is in grams and TL is total length in millimeters. The English-unit equivalent is log10 Ws = -3.592 + 3.194 log10 TL, when Ws is in pounds and TL is total length in inches. The equation is applicable for fish of 140-750 mm TL. Proposed length-category standards to evaluate fish within populations are: stock, 200 mm (8 in); quality, 300 mm (12 in); preferred, 400 mm (16 in); memorable, 500 mm (20 in); and trophy, 600 mm (24 in).

  13. The Effect of Individualized Versus Standardized Parenteral Nutrition on Body Weight in Very Preterm Infants

    PubMed Central

    Evering, Vincent H. M.; Andriessen, Peter; Duijsters, Carola E. P. M.; Brogtrop, Jeroen; Derijks, Luc J. J.

    2017-01-01

    Background This study was designed to evaluate whether standardizing total parenteral nutrition (TPN) is at least non-inferior to TPN with individualized composition in premature infants with a gestational age (GA) < 32 weeks. Methods In this retrospective cohort study, all preterm born in or transferred to Maxima Medical Center (MMC) within 24 hours after birth with a GA < 32 weeks were included. The individualized group (2011) was compared to the partially standardized group (2012) and completely standardized group (2014) consequently. The primary endpoint was difference in growth. Secondary endpoints included differences in electrolyte concentrations. Results A total of 299 preterm were included in this study. When comparing weight gain, the infants in the (partially) standardized group demonstrated significantly (P < 0.05) less weight loss during the first days of life and grew faster subsequently in the following days than the individualized TPN regimen. Furthermore, significant differences in abnormal serum sodium, chloride, calcium, creatinine, magnesium and triglycerides values were demonstrated. Conclusion TPN with a (partially) standardized composition revealed to be at least non-inferior to TPN with an individualized composition. PMID:28270894

  14. Academy of Nutrition and Dietetics: standards of practice and standards of professional performance for registered dietitian nutritionists (competent, proficient, and expert) in adult weight management.

    PubMed

    Jortberg, Bonnie; Myers, Eileen; Gigliotti, Linda; Ivens, Barbara J; Lebre, Monica; Burke March, Susan; Nogueira, Isadora; Nwankwo, Robin; Parkinson, Meredith R; Paulsen, Barbara; Turner, Tonya

    2015-04-01

    Weight management encompasses the inter-relationship of nutrition, physical activity, and health behavior change. Nutrition is key for the prevention and treatment of obesity and chronic disease and maintenance of overall health. Thus, the Weight Management Dietetic Practice Group, with guidance from the Academy of Nutrition and Dietetics Quality Management Committee, has developed Standards of Practice and Standards of Professional Performance for Registered Dietitian Nutritionists (RDNs) in Adult Weight Management as a resource for RDNs working in weight management. This document allows RDNs to assess their current skill levels and to identify areas for further professional development in this expanding practice area. This document describes the current standards for weight management practice for RDNs. The Standards of Practice represent the four steps in the Nutrition Care Process as applied to the care of patients/clients. The Standards of Professional Performance consist of six domains of professionalism: Quality in Practice, Competence and Accountability, Provision of Services, Application of Research, Communication and Application of Knowledge, and Utilization and Management of Resources. Within each standard, specific indicators provide measurable action statements that illustrate how the standard can be applied to practice. The indicators describe three skill levels (competent, proficient, and expert) for RDNs working in weight management. The Standards of Practice and Standards of Professional Performance are complementary resources for the Registered Dietitian Nutritionist in weight management.

  15. Possible applications of atomic frequency standards with an internal high resolution digital synthesizer

    NASA Technical Reports Server (NTRS)

    Detoma, E.; Stern, A.

    1993-01-01

    The applications of Atomic Frequency Standards with an internal synthesizer (thereafter referred as 'Synthesized Frequency Standards or Oscillators') with a special emphasis on the Rb oscillator are reviewed. A fractional frequency synthesizer, developed by SEPA, was incorporated in the Frequency Locked Loop of a TFL Rubidium Frequency Standard. This combination allows a frequency settability in steps of 1.5 x 10(exp -12) (optional 1 x 10(exp -13) over a range of 6 x 10(exp -9) without having to resort to change the C-field to tune the output frequency of the device. This capability, coupled to the excellent short term stability of the Rb frequency standard, opens new possibilities for time and frequency users in the various fields (time metrology, navigation, communication, etc.) in which stable frequency standards find their application.

  16. A new method to compute standard-weight equations that reduces length-related bias

    USGS Publications Warehouse

    Gerow, K.G.; Anderson-Sprecher, R. C.; Hubert, W.A.

    2005-01-01

    We propose a new method for developing standard-weight (Ws) equations for use in the computation of relative weight (Wr) because the regression line-percentile (RLP) method often leads to length-related biases in Ws equations. We studied the structural properties of W s equations developed by the RLP method through simulations, identified reasons for biases, and compared Ws equations computed by the RLP method and the new method. The new method is similar to the RLP method but is based on means of measured weights rather than on means of weights predicted from regression models. The new method also models curvilinear W s relationships not accounted for by the RLP method. For some length-classes in some species, the relative weights computed from Ws equations developed by the new method were more than 20 Wr units different from those using Ws equations developed by the RLP method. We recommend assessment of published Ws equations developed by the RLP method for length-related bias and use of the new method for computing new Ws equations when bias is identified. ?? Copyright by the American Fisheries Society 2005.

  17. An extended aqueous solvation model based on atom-weighted solvent accessible surface areas: SAWSA v2.0 model.

    PubMed

    Hou, Tingjun; Zhang, Wei; Huang, Qin; Xu, Xiaojie

    2005-02-01

    A new method is proposed for calculating aqueous solvation free energy based on atom-weighted solvent accessible surface areas. The method, SAWSA v2.0, gives the aqueous solvation free energy by summing the contributions of component atoms and a correction factor. We applied two different sets of atom typing rules and fitting processes for small organic molecules and proteins, respectively. For small organic molecules, the model classified the atoms in organic molecules into 65 basic types and additionally. For small organic molecules we proposed a correction factor of "hydrophobic carbon" to account for the aggregation of hydrocarbons and compounds with long hydrophobic aliphatic chains. The contributions for each atom type and correction factor were derived by multivariate regression analysis of 379 neutral molecules and 39 ions with known experimental aqueous solvation free energies. Based on the new atom typing rules, the correlation coefficient (r) for fitting the whole neutral organic molecules is 0.984, and the absolute mean error is 0.40 kcal mol(-1), which is much better than those of the model proposed by Wang et al. and the SAWSA model previously proposed by us. Furthermore, the SAWSA v2.0 model was compared with the simple atom-additive model based on the number of atom types (NA). The calculated results show that for small organic molecules, the predictions from the SAWSA v2.0 model are slightly better than those from the atom-additive model based on NA. However, for macromolecules such as proteins, due to the connection between their molecular conformation and their molecular surface area, the atom-additive model based on the number of atom types has little predictive power. In order to investigate the predictive power of our model, a systematic comparison was performed on seven solvation models including SAWSA v2.0, GB/SA_1, GB/SA_2, PB/SA_1, PB/SA_2, AM1/SM5.2R and SM5.0R. The results showed that for organic molecules the SAWSA v2.0 model is better

  18. Accuracy of Nanoscale Pitch Standards Fabricated by Laser-Focused Atomic Deposition

    PubMed Central

    McClelland, Jabez J.; Anderson, William R.; Bradley, Curtis C.; Walkiewicz, Mirek; Celotta, Robert J.; Jurdik, Erich; Deslattes, Richard D.

    2003-01-01

    The pitch accuracy of a grating formed by laser-focused atomic deposition is evaluated from the point of view of fabricating nanoscale pitch standard artifacts. The average pitch obtained by the process, nominally half the laser wavelength, is simply traceable with small uncertainty to an atomic frequency and hence can be known with very high accuracy. An error budget is presented for a Cr on sapphire sample, showing that a combined standard uncertainty of 0.0049 nm, or a relative uncertainty of 2.3 × 10−5, is readily obtained, provided the substrate temperature does not change. Precision measurements of the diffraction of the 351.1 nm argon ion laser line from such an artifact are also presented. These yield an average pitch of (212.7777 ± 0.0069) nm, which agrees well with the expected value, as corrected for thermal contraction, of (212.7705 ± 0.0049) nm. PMID:27413597

  19. Development of standard weight equations for Caribbean and Gulf of Mexico amphidromous fishes

    USGS Publications Warehouse

    Cooney, Patrick B.; Kwak, Thomas J.

    2010-01-01

    We collected and compiled length and weight information from four countries and one commonwealth to develop standard weight (Ws) equations for three amphidromous fish species native to the Caribbean and Gulf of Mexico regions: mountain mullet Agonostomus monticola (N = 9,768 individuals, 52 populations), river goby Awaous banana (N = 1,847 individuals, 62 populations), and bigmouth sleeper Gobiomorus dormitor (N = 2,983 individuals, 53 populations). Linear and quadratic Ws equations for three quartiles (25%, median, 75%) are presented for these three species. The length-weight relationship from eight lentic bigmouth sleeper populations was significantly different from that of lotic populations, reflecting higher weights of juvenile fish (< 70 mm total length) in lentic environments. Thus, independent W(s) equations were developed for lotic populations of bigmouth sleepers. W(s) equations were not developed from lentic bigmouth sleeper populations alone due to the low number of applicable populations caused by life history constraints; the equation from combined lentic and lotic populations is suggested for application to lentic bigmouth sleeper populations. These morphometric relationships for amphidromous fishes may improve the ability to assess existing and potential sport fisheries and allow ecological assessment based on fish condition.

  20. Short-term stability improvements of an optical frequency standard based on free Ca atoms

    NASA Astrophysics Data System (ADS)

    Sherman, Jeff; Oates, Chris

    2010-03-01

    Compared to optical frequency standards featuring trapped ions or atoms in optical lattices, the strength of a standard using freely expanding neutral calcium atoms is not ultimate accuracy but rather short-term stability and experimental simplicity. Recently, a fractional frequency instability of 4 x10-15 at 1 second was demonstrated for the Ca standard at 657 nm [1]. The short cycle time (˜2 ms) combined with only a moderate interrogation duty cycle (˜15 %) is thought to introduce excess, and potentially critically limiting technical noise due to the Dick effect---high-frequency noise on the laser oscillator is not averaged away but is instead down-sampled by aliasing. We will present results of two strategies employed to minimize this effect: the reduction of clock laser noise by filtering the master clock oscillator through a high-finesse optical cavity [2], and an optimization of the interrogation cycle to match our laser's noise spectrum.[4pt] [1] Oates et al., Optics Letters, 25(21), 1603--5 (2000)[0pt] [2] Nazarova et al., J. Opt. Soc. Am. B, 5(10), 1632--8 (2008)

  1. Atomic Force Microscope Cantilever Flexural Stiffness Calibration: Toward a Standard Traceable Method

    PubMed Central

    Gates, Richard S.; Reitsma, Mark G.; Kramar, John A.; Pratt, Jon R.

    2011-01-01

    The evolution of the atomic force microscope into a useful tool for measuring mechanical properties of surfaces at the nanoscale has spurred the need for more precise and accurate methods for calibrating the spring constants of test cantilevers. Groups within international standards organizations such as the International Organization for Standardization and the Versailles Project on Advanced Materials and Standards (VAMAS) are conducting studies to determine which methods are best suited for these calibrations and to try to improve the reproducibility and accuracy of these measurements among different laboratories. This paper expands on a recent mini round robin within VAMAS Technical Working Area 29 to measure the spring constant of a single batch of triangular silicon nitride cantilevers sent to three international collaborators. Calibration techniques included reference cantilever, added mass, and two forms of thermal methods. Results are compared to measurements traceable to the International System of Units provided by an electrostatic force balance. A series of guidelines are also discussed for procedures that can improve the running of round robins in atomic force microscopy. PMID:26989594

  2. Postmortem lung volume/body weight standards for term and preterm infants.

    PubMed

    De Paepe, Monique E; Shapiro, Svetlana; Hansen, Katrine; Gündoğan, Füsun

    2014-01-01

    Assessment of lung growth is a critical component of the perinatal autopsy. Increased lung liquid content may lead to overestimation of lung growth based on (wet) lung weight. In contrast, lung volume is not influenced by intraalveolar lung liquid. Our aim was to establish age-specific reference values for postmortem lung volume/BW in preterm and term infants. We performed a retrospective analysis of fetuses/infants (16-41 weeks' gestation) without (N = 134) or with (N = 79) risk factors for pulmonary hypoplasia. Lungs were inflated at standardized pressure and volumes determined by water immersion method. Lung volume increased 11-fold between 16 and 41 weeks' gestation, concomitant with a 16-fold increase in BW. Mean lung volume/BW remained constant at 33-34 ml/kg between 16 and 31 weeks' gestation and decreased to 23.4 ml/kg at term. Lung volume/BW of infants with severe risk factors (renal anomalies, diaphragmatic hernia) was significantly lower than age-matched standards. In this group, all fetuses/infants diagnosed as having lung hypoplasia by lung volume/BW also had lung hypoplasia LW/BW standards. However, in infants with "softer" risk factors (rupture of membranes, chromosomal anomalies), 5/26 cases diagnosed with lung hypoplasia based on lung volume/BW had normal LW/BW ratios. In these discrepant cases, lung sections showed significant inflammation and edema, likely accounting for increased wet lung weight. In conclusion, we determined age-specific lung volume/BW reference values for preterm and term infants. In selected situations assessment of lung volume/BW may represent a useful complementary tool to LW/BW for postmortem evaluation of lung size.

  3. Precise determination of the absolute isotopic abundance ratio and the atomic weight of chlorine in three international reference materials by the positive thermal ionization mass spectrometer-Cs2Cl+-graphite method.

    PubMed

    Wei, Hai-Zhen; Jiang, Shao-Yong; Xiao, Ying-Kai; Wang, Jun; Lu, Hai; Wu, Bin; Wu, He-Pin; Li, Qing; Luo, Chong-Guang

    2012-12-04

    Because the variation in chlorine isotopic abundances of naturally occurring chlorine bearing substances is significant, the IUPAC Inorganic Chemistry Division, Commission on Isotopic Abundances and Atomic Weights (CIAAW-IUPAC) decided that the uncertainty of atomic weight of chlorine (A(r)(Cl)) should be increased so that the implied range was related to terrestrial variability in 1999 (Coplen, T. B. Atomic weights of the elements 1999 (IUPAC Technical Report), Pure Appl. Chem.2001, 73(4), 667-683; and then, it emphasized that the standard atomic weights of ten elements including chlorine were not constants of nature but depend upon the physical, chemical, and nuclear history of the materials in 2009 (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396). According to the agreement by CIAAW that an atomic weight could be defined for one specified sample of terrestrial origin (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396), the absolute isotope ratios and atomic weight of chlorine in standard reference materials (NIST 975, NIST 975a, ISL 354) were accurately determined using the high-precision positive thermal ionization mass spectrometer (PTIMS)-Cs(2)Cl(+)-graphite method. After eliminating the weighing error caused from evaporation by designing a special weighing container and accurately determining the chlorine contents in two highly enriched Na(37)Cl and Na(35)Cl salts by the current constant coulometric titration, one series of gravimetric synthetic mixtures prepared from two highly enriched Na(37)Cl and Na(35)Cl salts was used to calibrate two thermal ionization mass spectrometers in two individual laboratories. The correction factors (i.e., K(37/35) = R(37/35meas)/R(37/35calc)) were obtained from five cycles of iterative calculations on the basis of calculated and determined R((37)Cl/(35)Cl) values in gravimetric synthetic mixtures. The absolute R((37)Cl/(35)Cl) ratios for NIST SRM 975, NIST 975a, and ISL 354 by the precise

  4. Stability of low concentration calibration standards for graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Bass, D A; TenKate, L B

    1993-11-01

    Graphite furnace atomic absorption spectrophotometry (GFAAS) is used for determination of ultra-trace metals in environmentally important samples. In the generation of GFAAS calibration curves for many environmental applications, low concentration calibration standards must be prepared dally, as required by the Statement of Work (SOW) for the US Environmental Protection Agency (EPA) Contract Laboratory Program (CLP). This results in significant time and work for the analyst and significant cost to the Analytical Chemistry Laboratory (ACL) for chemicals and waste management. While EPA SW 846 is less prescriptive than the CLP SOW, ACL has been following the CLP guidelines because in-house criteria regarding the stability of GFAAS standards have not been established. A study was conducted to determine the stability of GFAAS standards for analytes commonly used in the ACL (single and mixed) as a function of time. Data were collected over nine months. The results show that GFAAS standards for Sb, Pb, Se, Ag, and TI are stable for a longer period of time than currently assumed by the CLP SOW. Reducing the frequency of preparing these standards will increase efficiency, decrease the handling of hazardous the quantity of hazardous waste generated, and decrease the quantity of hazardous substances to be ordered and stocked by the laboratory. These benefits will improve GFAAS analysis quality, reduce costs, enhance safety, and lower environmental concerns.

  5. METALLURGICAL PROGRAMS: CALCULATION OF MASS FROM VOLUME, DENSITY OF MIXTURES, AND CONVERSION OF ATOMIC TO WEIGHT PERCENT

    NASA Technical Reports Server (NTRS)

    Degroh, H.

    1994-01-01

    The Metallurgical Programs include three simple programs which calculate solutions to problems common to metallurgical engineers and persons making metal castings. The first program calculates the mass of a binary ideal (alloy) given the weight fractions and densities of the pure components and the total volume. The second program calculates the densities of a binary ideal mixture. The third program converts the atomic percentages of a binary mixture to weight percentages. The programs use simple equations to assist the materials staff with routine calculations. The Metallurgical Programs are written in Microsoft QuickBASIC for interactive execution and have been implemented on an IBM PC-XT/AT operating MS-DOS 2.1 or higher with 256K bytes of memory. All instructions needed by the user appear as prompts as the software is used. Data is input using the keyboard only and output is via the monitor. The Metallurgical programs were written in 1987.

  6. Re-calibration of the NIST SRM 2059 master standard using traceable atomic force microscope metrology

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald; Potzick, James; Orji, Ndubuisi G.

    2008-10-01

    The current photomask linewidth Standard Reference Material (SRM) supplied by the National Institute of Standards and Technology (NIST), SRM 2059, is the fifth generation of such standards for mask metrology. An in house optical microscope tool developed at NIST, called the NIST ultra-violet (UV) microscope, was used in transmission mode to calibrate the SRM 2059 photomasks. Due to the limitations of available optical models for determining the edge response in the UV microscope, the tool was used in a comparator mode. One of the masks was selected as a master standard - and the features on this mask were calibrated using traceable critical dimension atomic force microscope (CD-AFM) dimensional metrology. The optical measurements were then used to determine the relative offsets between the widths on the master standard and individual masks for sale to customers. At the time of these measurements, however, the uncertainties in the CD-AFM reference metrology on the master standard were larger than can now be achieved because the NIST single crystal critical dimension reference material (SCCDRM) project had not been completed. Using our CD-AFM at NIST, we have performed new measurements on the SRM 2059 master standard. The new AFM results are in agreement with the prior measurements and have expanded uncertainties approximately one fourth of those of the earlier results for sub-micrometer features. When the optical comparator data for customers masks are reanalyzed using these new AFM results, we expect to reduce the combined reported uncertainties for the linewidths on the actual SRMs by at least 40 % for the nominal 0.25 μm features.

  7. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms

    PubMed Central

    Zhang, S. Y.; Wu, J. T.; Zhang, Y. L.; Leng, J. X.; Yang, W. P.; Zhang, Z. G.; Zhao, J. Y.

    2015-01-01

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios. PMID:26459877

  8. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms.

    PubMed

    Zhang, S Y; Wu, J T; Zhang, Y L; Leng, J X; Yang, W P; Zhang, Z G; Zhao, J Y

    2015-10-13

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios.

  9. Preclinical safety evaluation of low molecular weight galactomannans based standardized fenugreek seeds extract

    PubMed Central

    Deshpande, Pallavi; Mohan, Vishwaraman; Thakurdesai, Prasad

    2016-01-01

    The objective of the present study was to evaluate acute oral toxicity, subchronic toxicity, and mutagenic potential of low molecular weight galactomannans based standardized fenugreek seeds extract (LMWGAL-TF) in laboratory animals rats as per Organization for Economic Co-operation and Development (OECD) guidelines. For the acute toxicity (AOT) study, LMWGAL-TF was orally administered to Sprague-Dawley (SD) rats at a dose of 2000 mg/kg with vehicle control (VC) group (n = 5 per sex per group) as per OECD guideline no. 423. For the repeated dose toxicity study, the SD rats were orally administered with a daily oral dose of LMWGAL-TF 250, 500 and 1000 mg/kg/day with VC group (n = 15 per sex) for a period of 90 days followed by a recovery period of 28 days as per OECD guideline no. 408. The effects on body weight, food and water consumption, organ weights with hematology, clinical biochemistry, and histology were studied. The mutagenic potential of LMWGAL-TF was tested using reverse mutation assay (AMES test, OECD guideline No. 471). The LMWGAL-TF did not show mortality or treatment-related adverse signs during acute (dose 2000 mg/kg) and subchronic (90-days repeated dose 250, 500 and 1000 mg/kg) administration. The LMWGAL-TF showed oral lethal dose (LD50) more than 2000 mg/kg during AOT study. The dose of 1000 mg/kg was found as no observed adverse effect level (NOAEL) in rats during subchronic toxicity study. Furthermore, LMWGAL-TF did not show mutagenic potential in vitro. In conclusion, LMWGAL-TF was found safe during acute and subchronic (90 days repeated dose) toxicity studies in rats with no mutagenicity. PMID:27822173

  10. Determination of the atomic weight of 28Si-enriched silicon for a revised estimate of the Avogadro constant.

    PubMed

    Yang, Lu; Mester, Zoltán; Sturgeon, Ralph E; Meija, Juris

    2012-03-06

    The much anticipated overhaul of the International System of Units (SI) will result in new definitions of base units in terms of fundamental constants. However, redefinition of the kilogram in terms of the Planck constant (h) cannot proceed without consistency between the Avogadro and Planck constants, which are both related through the Rydberg constant. In this work, an independent assessment of the atomic weight of silicon in a highly enriched (28)Si crystal supplied by the International Avogadro Coordination (IAC) was performed. This recent analytical approach, based on dissolution with NaOH and its isotopic characterization by multicollector inductively coupled plasma mass spectrometry, is critically evaluated. The resultant atomic weight A(r)(Si) = 27.976 968 39(24)(k=1) differs significantly from the most recent value of A(r)(Si) = 27.976 970 27(23)(k=1). Using the results generated herein for A(r)(Si) along with other IAC measurement results for mass, volume, and the lattice spacing, the estimate of the Avogadro constant becomes N(A) = 6.022 140 40(19) × 10(23) mol(-1).

  11. A standard format for reporting atomic positions in measured or calculated surface structures: The CIF file

    NASA Astrophysics Data System (ADS)

    Marks, Laurence D.

    2010-06-01

    In his editorial in this issue, the editor-in-chief emphasizes the editorial policy that any paper which involves a crystallographic structure (whether experimentally measured or theoretically calculated) must also include a complete listing of all the atomic positions within the crystal structure, either as supporting information or directly within the paper itself. He also strongly recommends that the complete crystallographic data set be included as supporting information. At the request of the editor-in-chief, I outline here the reasons why this is scientifically desirable. Furthermore, I propose here that the Surface Science community adopt the same standard format for reporting these as is already widely used in bulk crystallography publications, namely the inclusion of a Crystallographic Information Format file (or CIF file) as supporting information. Finally, I describe the details of this specific file format, with illustrative examples.

  12. wARP: improvement and extension of crystallographic phases by weighted averaging of multiple-refined dummy atomic models.

    PubMed

    Perrakis, A; Sixma, T K; Wilson, K S; Lamzin, V S

    1997-07-01

    wARP is a procedure that substantially improves crystallographic phases (and subsequently electron-density maps) as an additional step after density-modification methods such as solvent flattening and averaging. The initial phase set is used to create a number of dummy atom models which are subjected to least-squares or maximum-likelihood refinement and iterative model updating in an automated refinement procedure (ARP). Averaging of the phase sets calculated from the refined output models and weighting of structure factors by their similarity to an average vector results in a phase set that improves and extends the initial phases substantially. An important requirement is that the native data have a maximum resolution beyond approximately 2.4 A. The wARP procedure shortens the time-consuming step of model building in crystallographic structure determination and helps to prevent the introduction of errors.

  13. Proposed standard-weight (W(s)) equations for kokanee, golden trout and bull trout

    USGS Publications Warehouse

    Hyatt, M.H.; Hubert, W.A.

    2000-01-01

    We developed standard-weight (W(s)) equations for kokanee (lacustrine Oncorhynchus nerka), golden trout (O. aguabonita), and bull trout (Salvelinus confluentus) using the regression-line-percentile technique. The W(s) equation for kokanee of 120-550 mm TL is log10 W(s) = -5.062 + 3.033 log10 TL, when W(s) is in grams and TL is total length in millimeters; the English-unit equivalent is log10 W(s) = -3.458 + 3.033 log10 TL, when W(s) is in pounds and TL is total length in inches. The W(s) equation for golden trout of 120-530 mm TL is log10 W(s) = -5.088 + 3.041 log10 TL, with the English-unit equivalent being log10 W(s) = -3.473 + 3.041 log10 TL. The W(s) equation for bull trout of 120-850 mm TL is log10 W(s) = -5.327 + 3.115 log10 TL, with the English-unit equivalent being log10 W(s) = -3.608 + 3.115 log10 TL.

  14. Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples.

    PubMed

    Taher, Mohammad Ali; Pourmohammad, Fatemeh; Fazelirad, Hamid

    2015-12-01

    In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra-trace amounts of rhodium after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015-0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values.

  15. Comparison of Errors of 35 Weight Estimation Formulae in a Standard Collective

    PubMed Central

    Hoopmann, M.; Kagan, K. O.; Sauter, A.; Abele, H.; Wagner, P.

    2016-01-01

    Issue: The estimation of foetal weight is an integral part of prenatal care and obstetric routine. In spite of its known susceptibility to errors in cases of underweight or overweight babies, important obstetric decisions depend on it. In the present contribution we have examined the accuracy and error distribution of 35 weight estimation formulae within the normal weight range of 2500–4000 g. The aim of the study was to identify the weight estimation formulae with the best possible correspondence to the requirements of clinical routine. Materials and Methods: 35 clinically established weight estimation formulae were analysed in 3416 foetuses with weights between 2500 and 4000 g. For this we determined and compared the mean percentage error (MPE), the mean absolute percentage error (MAPE), and the proportions of estimates within the error ranges of 5, 10, 20 and 30 %. In addition, separate regression lines were calculated for the relationship between estimated and actual birth weights for the weight range 2500–4000 g. The formulae were thus examined for possible inhomogeneities. Results: The lowest MPE were achieved with the Hadlock III and V formulae (0.8 %, STW 9.2 % or, respectively, −0.8 %, STW 10.0 %). The lowest absolute error (6.6 %) as well as the most favourable frequency distribution in cases below 5 % and 10 % error (43.9 and 77.5) were seen for the Halaska formula. In graphic representations of the regression lines, 16 formulae revealed a weight overestimation in the lower weight range and an underestimation in the upper range. 14 formulae gave underestimations and merely 5 gave overestimations over the entire tested weight range. Conclusion: The majority of the tested formulae gave underestimations of the actual birth weight over the entire weight range or at least in the upper weight range. This result supports the current strategy of a two-stage weight estimation in which a formula is first chosen after a pre-estimation of

  16. Orthogonal natural atomic orbitals form an appropriate one-electron basis for expanding CASSCF wave functions into localized bonding schemes and their weights.

    PubMed

    Bachler, Vinzenz

    2007-09-01

    Localized bonding schemes and their weights have been obtained for the pi-electron system of nitrone by expanding complete active space self-consistent field wave functions into a set of Slater determinants composed of orthogonal natural atomic orbitals (NAOs) of Weinhold and Landis (Valency and Bonding: A Natural Bond Orbital Donor-Acceptor Perspective, 2005). Thus, the derived bonding schemes are close to orthogonal valence bond structures. The calculated sequence of bonding scheme weights accords with the sequence of genuine resonance structure weights derived previously by Ohanessian and Hiberty (Chem Phys Lett 1987, 137, 437), who employed nonorthogonal atomic orbitals. This accord supports the notion that NAOs form an appropriate orthogonal one-electron basis for expanding complete active space self-consistent field wave functions into meaningful bonding schemes and their weights.

  17. 77 FR 63763 - Regulatory Capital Rules: Standardized Approach for Risk-Weighted Assets; Market Discipline and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... the asset risk weights; 2. Revising the treatment of counterparty credit risk; 3. Replacing references... assets and up for others. For those assets with a higher risk weight under the NPR, that increase may be large in some instances, for example, the equivalent of a dollar-for-dollar capital charge for...

  18. Benchmarks of improved complete basis set extrapolation schemes designed for standard CCSD(T) atomization energies.

    PubMed

    Feller, David

    2013-02-21

    Simple modifications of complete basis set extrapolation formulas chosen from the literature are examined with respect to their abilities to reproduce a diverse set of 183 reference atomization energies derived primarily from very large basis set standard, frozen core coupled-cluster singles, doubles plus perturbative triples (CCSD(T)) with the aug-cc-pVnZ basis sets. This reference set was augmented with a few larger chemical systems treated with explicitly correlated CCSD(T)-F12b using a quadruple zeta quality basis set followed by extrapolation to complete basis set limit. Tuning the extrapolation formula parameters for the present reference set resulted in substantial reductions in the error metrics. In the case of the best performing approach, the aVnZ extrapolated results are equivalent to or better than results obtained from raw aV(n + 3)Z basis set calculations. To the extent this behavior holds for molecules outside the reference set, it represents an improvement of at least one basis set level over the original formulations and a further significant reduction in the amount of computer time needed to accurately approximate the basis set limit.

  19. New Homogeneous Standards by Atomic Layer Deposition for Synchrotron X-ray Fluorescence and Absorption Spectroscopies.

    SciTech Connect

    Butterworth, A.L.; Becker, N.; Gainsforth, Z.; Lanzirotti, A.; Newville, M.; Proslier, T.; Stodolna, J.; Sutton, S.; Tyliszczak, T.; Westphal, A.J.; Zasadzinski, J.

    2012-03-13

    Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and characterizing them using multiple analytical methods, including ellipsometry, Rutherford Back Scattering at Evans Analytical, Synchrotron X-ray Fluorescence (SXRF) at Advanced Photon Source (APS) Beamline 13-ID, Synchrotron X-ray Absorption Spectroscopy (XAS) at Advanced Light Source (ALS) Beamlines 11.0.2 and 5.3.2.1 and by electron microscopy techniques. Our motivation for developing much-needed cross-calibration of synchrotron techniques is borne from coordinated analyses of particles captured in the aerogel of the NASA Stardust Interstellar Dust Collector (SIDC). The Stardust Interstellar Dust Preliminary Examination (ISPE) team have characterized three sub-nanogram, {approx}1{micro}m-sized fragments considered as candidates to be the first contemporary interstellar dust ever collected, based on their chemistries and trajectories. The candidates were analyzed in small wedges of aerogel in which they were extracted from the larger collector, using high sensitivity, high spatial resolution >3 keV synchrotron x-ray fluorescence spectroscopy (SXRF) and <2 keV synchrotron x-ray transmission microscopy (STXM) during Stardust ISPE. The ISPE synchrotron techniques have complementary capabilities. Hard X-ray SXRF is sensitive to sub-fg mass of elements Z {ge} 20 (calcium) and has a spatial resolution as low as 90nm. X-ray Diffraction data were collected simultaneously with SXRF data. Soft X-ray STXM at ALS beamline 11.0.2 can detect fg-mass of most elements, including cosmochemically important oxygen, magnesium, aluminum and silicon, which are invisible to SXRF in this application. ALS beamline 11.0.2 has spatial resolution

  20. Beller Lectureship: From Artefacts to Atoms: The Origins and Early Years of the International Bureau of Weights and Measures (BIPM)

    NASA Astrophysics Data System (ADS)

    Quinn, Terry

    2012-02-01

    The BIPM was founded by the Metre Convention in 1875. Its main task was to maintain and disseminate the units of length and mass using the new International Prototypes of the Metre and Kilogram. My talk will be based on the opening chapters of my book ``From Artefacts to Atoms'' which recount the story of the Metre Convention and the creation of the BIPM at the Pavillon de Breteuil in Sèvres on the outskirts of Paris, as the first international scientific institute. I shall include a brief outline of the sometimes acrimonious discussions at the Diplomatic Conference of the Metre, which opened on 1 March 1875 and concluded with the signing of the Convention on 20 May, of the construction of a new laboratory building, recruitment of staff, purchase of instruments and equipment and the beginning of scientific work. There was no precedent for any of this, success was due to the wisdom and foresight of those who drafted the Convention and to the founder Members of the International Committee for Weights and Measures overseeing the BIPM and to the high quality of the original scientific staff. However, success came at a price, the decision to define the Metre at 0 ^oC, for example, led to much ill health in the early years among the staff from working in cold damp laboratories, an aspect of metrology that is easy to forget these days.

  1. Differences in Weight Loss Between Persons on Standard Balanced vs Nutrigenetic Diets in a Randomized Controlled Trial

    PubMed Central

    Kenyon, Mandy L.; Rutledge, Thomas R.; Liao, Patricia S.; Gupta, Samir; Herbst, Karen L.; Zarrinpar, Amir

    2015-01-01

    Background & Aims Many companies provide genetic tests for obesity-related polymorphisms (nutrigenetics) and make dietary recommendations for weight loss based on the results. We performed a randomized controlled trial to determine whether more participants who followed a nutrigenetic-guided diet lost ≥5% of their body weight than participants on a standard balanced diet, for 8 and 24 weeks. Methods We performed a prospective study of 51 obese or overweight US veterans on an established weight management program at the Veterans Administration San Diego Healthcare System (the MOVE! Program). Participants were randomly assigned to groups placed on a nutrigenetic-guided diet (balanced, low-carbohydrate, low-fat, or Mediterranean; n=30) or a standard balanced diet (n=21). Nutrigenetic diets were selected based on results from the Pathway FIT test (Pathway Genomics; San Diego, CA). Results There was no significant difference in the percentage of participants on the balanced diet vs the nutrigenetic-guided diet who lost 5% of their body weight at 8 weeks (35.0%±20.9% vs 26.9%±17.1%, respectively; P=.28) or at 24 weeks. Both groups had difficulty adhering to the diets. However, adherence to the nutrigenetic-guided diet correlated with weight loss (r=0.74; P= 4.0 × 10−5), but not adherence to standard therapy (r=0.34; P=.23). Participants who had low-risk polymorphisms for obesity lost more weight than all other participants at 8 weeks (5.0% vs 2.9%, respectively; P=.02), and had significantly greater reductions in body mass index (6.4% vs 3.6% respectively; P=.03) and waist circumference (6.5% vs 2.6% respectively; P=.02) at 24 weeks. Conclusions In a prospective study, a nutrigenetic-based diet did not increase weight loss compared with a standard balanced diet. However, genetic features can identify individuals most likely to benefit from a balanced diet weight loss strategy; these findings require further investigation. ClincialTrials.gov number: NCT01859403

  2. Univariate and Default Standard Unit Biases in Estimation of Body Weight and Caloric Content

    ERIC Educational Resources Information Center

    Geier, Andrew B.; Rozin, Paul

    2009-01-01

    College students estimated the weight of adult women from either photographs or a live presentation by a set of models and estimated the calories in 1 of 2 actual meals. The 2 meals had the same items, but 1 had larger portion sizes than the other. The results suggest: (a) Judgments are biased toward transforming the example in question to the…

  3. Testing Lorentz Invariance with Laser-Cooled Cesium Atomic Frequency Standards

    NASA Technical Reports Server (NTRS)

    Klipstein, William M.

    2004-01-01

    This slide presentation reviews the Lorentz invariance testing during the proposed PARCS experiment. It includes information on the primary atomic reference clock in space (PARCS), cesium, laser cooling, and the vision for the future.

  4. Prediction of enthalpy and standard Gibbs energy of vaporization of haloaromatics from atomic properties.

    PubMed

    Monte, M J S; Almeida, A R R P; Liebman, J F

    2015-11-01

    Halogenated benzenes form a class of pollutants with a huge number of members - 1504 distinct benzene compounds, where one or more hydrogen atoms are replaced by halogens, may exist theoretically. This study presents a user friendly method for accurate prediction of vapor pressures and enthalpies of vaporization, at 298.15 K, of any mono or poly halobenzene compound. The derived equations for the prediction of those vaporization properties depend just on the number of each constituent halogen atom. This is a consequence of the absence of intramolecular interactions between the halogen atoms, revealed after examining vaporization results of ca. 40 halogenated benzenes. In order to rationalize the estimation equations, the contribution of the halogen atoms for the referred to above properties of vaporization was decomposed into two atomic properties - the volume and electron affinity. Extension of the applicability of the estimation method to substituted benzenes containing other substituent groups beyond halogen atoms as well as to some polycyclic aromatic species was tested with success.

  5. The Effects of Ambient Temperature Fluctuations on the Long-Term Frequency Stability of a Miniature Rubidium Atomic Frequency Standard

    DTIC Science & Technology

    2007-11-02

    technologies; lasers and electro-optics, solid state laser design, micro-optics, optical communications, and fiber optic sensors ; atomic frequency standards...elastomer change could also shift the position of physics package components, thereby creating a greater sensitivity to microwave power or magnetic...applied laser spectroscopy, laser chemistry, atmospheric propagation and beam control, LEDAR/LADAR remote sensing; solar cell and array testing and

  6. Weighting Factors for the Commercial Building Prototypes Used in the Development of ANSI/ASHRAE/IESNA Standard 90.1-2010

    SciTech Connect

    Jarnagin, Ronald E.; Bandyopadhyay, Gopal K.

    2010-01-21

    Detailed construction data from the McGraw Hill Construction Database was used to develop construction weights by climate zones for use with DOE Benchmark Buildings and for the ASHRAE Standard 90.1-2010 development. These construction weights were applied to energy savings estimates from simulation of the benchmark buildings to establish weighted national energy savings.

  7. 77 FR 52887 - Regulatory Capital Rules: Standardized Approach for Risk-Weighted Assets; Market Discipline and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-30

    ...The Office of the Comptroller of the Currency (OCC), the Board of Governors of the Federal Reserve System (Board), and the Federal Deposit Insurance Corporation (FDIC) (collectively, the agencies) are seeking comment on three notices of proposed rulemaking (NPRs) that would revise and replace the agencies' current capital rules. This NPR (Standardized Approach NPR) includes proposed changes to......

  8. Proportion of U.S. Civilian Population Ineligible for U.S. Air Force Enlistment Based on Current and Previous Weight Standards

    DTIC Science & Technology

    2007-09-01

    place. However, in June 2006 the USAF implemented a new set of height-weight limits utilizing body mass index ( BMI ) criteria [3, 4]. The...the maximum weight limit, alternative body fat assessments are made to guarantee that eligible and qualified enlistees do not get overlooked [5...weight standards serve as a preliminary appraisal, and should an individual exceed these limits, he/she may undergo a standardized body fat

  9. Mesoscopic atomic entanglement for precision measurements beyond the standard quantum limit.

    PubMed

    Appel, J; Windpassinger, P J; Oblak, D; Hoff, U B; Kjaergaard, N; Polzik, E S

    2009-07-07

    Squeezing of quantum fluctuations by means of entanglement is a well-recognized goal in the field of quantum information science and precision measurements. In particular, squeezing the fluctuations via entanglement between 2-level atoms can improve the precision of sensing, clocks, metrology, and spectroscopy. Here, we demonstrate 3.4 dB of metrologically relevant squeezing and entanglement for greater, similar 10(5) cold caesium atoms via a quantum nondemolition (QND) measurement on the atom clock levels. We show that there is an optimal degree of decoherence induced by the quantum measurement which maximizes the generated entanglement. A 2-color QND scheme used in this paper is shown to have a number of advantages for entanglement generation as compared with a single-color QND measurement.

  10. Task-based evaluation of segmentation algorithms for diffusion-weighted MRI without using a gold standard.

    PubMed

    Jha, Abhinav K; Kupinski, Matthew A; Rodríguez, Jeffrey J; Stephen, Renu M; Stopeck, Alison T

    2012-07-07

    In many studies, the estimation of the apparent diffusion coefficient (ADC) of lesions in visceral organs in diffusion-weighted (DW) magnetic resonance images requires an accurate lesion-segmentation algorithm. To evaluate these lesion-segmentation algorithms, region-overlap measures are used currently. However, the end task from the DW images is accurate ADC estimation, and the region-overlap measures do not evaluate the segmentation algorithms on this task. Moreover, these measures rely on the existence of gold-standard segmentation of the lesion, which is typically unavailable. In this paper, we study the problem of task-based evaluation of segmentation algorithms in DW imaging in the absence of a gold standard. We first show that using manual segmentations instead of gold-standard segmentations for this task-based evaluation is unreliable. We then propose a method to compare the segmentation algorithms that does not require gold-standard or manual segmentation results. The no-gold-standard method estimates the bias and the variance of the error between the true ADC values and the ADC values estimated using the automated segmentation algorithm. The method can be used to rank the segmentation algorithms on the basis of both the ensemble mean square error and precision. We also propose consistency checks for this evaluation technique.

  11. Correcting bias from the standard linear adjustment of weaning weight to an age-constant basis for beef calves.

    PubMed

    Rossi, D J; Kress, D D; Tess, M W; Burfening, P J

    1992-05-01

    Standard linear adjustment of weaning weight to a constant age has been shown to introduce bias in the adjusted weight due to nonlinear growth from birth to weaning of beef calves. Ten years of field records from the five strains of Beefbooster Cattle Alberta Ltd. seed stock herds were used to investigate the use of correction factors to adjust standard 180-d weight (WT180) for this bias. Statistical analyses were performed within strain and followed three steps: 1) the full data set was split into an estimation set (ES) and a validation set (VS), 2) WT180 from the ES was used to develop estimates of correction factors using a model including herd (H), year (YR), age of dam (DA), sex of calf (S), all two and three-way interactions, and any significant linear and quadratic covariates of calf age at weaning deviated from 180 d (DEVCA) and interactions between DEVCA and DA, S or DA x S, and 3) significant DEVCA coefficients were used to correct WT180 from the VS, then WT180 and the corrected weight (WTCOR) from the VS were analyzed with the same model as in Step 2 and significance of DEVCA terms were compared. Two types of data splitting were used. Adjusted R2 was calculated to describe the proportion of total variation of DEVCA terms explained for WT180 from the ES. The DEVCA terms explained .08 to 1.54% of the total variation for the five strains. Linear and quadratic correction factors were both positive and negative. Bias in WT180 from the ES within 180 +/- 35 d of age ranged from 2.8 to 21.7 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Pattern of growth of very low birth weight preterm infants, assessed using the WHO Growth Standards, is associated with neurodevelopment.

    PubMed

    Nash, Andrea; Dunn, Michael; Asztalos, Elizabeth; Corey, Mary; Mulvihill-Jory, Bridget; O'Connor, Deborah L

    2011-08-01

    Several Canadian professional organizations recently recommended that the growth of preterm infants be monitored using the World Health Organization Growth Standards (WHO-GS) after hospital discharge. The WHO-GS are a prescriptive set of growth charts that describe how term infants should grow under ideal environmental conditions. Whether preterm infants following this pattern of growth have better outcomes than infants that do not has yet to be evaluated. Our aim was to determine whether the pattern of growth of very low birth weight (VLBW) infants during the first 2 years, assessed using the WHO-GS or the traditional Centers for Disease Control and Prevention reference growth charts (CDC-RGC), is associated with neurodevelopment. Pattern of weight, length, and head circumference gain of appropriate-for-gestation VLBW preterm infants (n = 289) from birth to 18-24 months corrected age was classified, using the WHO-GS and CDC-RGC, as sustained (change in Z-score ≤1 SD), decelerated (decline >1 SD), or accelerated (incline >1 SD). Development was assessed using the Bayley Scales of Infant and Toddler Development (BSID)-III at 18-24 months corrected age. Using the WHO-GS, children with a decelerated pattern of weight gain had lower cognitive (10 points), language (6 points), and motor (4 points) scores than infants with sustained weight gain (p < 0.05), even after adjustment for morbidities. No association was found using the CDC-RGC. In conclusion, a decelerated pattern of weight gain, determined with the WHO-GS, but not the CDC-GRC, is associated with poorer neurodevelopment scores on the BSID-III than a pattern of sustained growth.

  13. A flow-batch internal standard procedure for iron determination in hydrated ethanol fuel by flame atomic absorption spectrometry.

    PubMed

    da Silva, José Edson; da Silva, Fábio André; Pimentel, M Fernanda; Honorato, Ricardo Saldanha; da Silva, Valdinete Lins; Montenegro, Maria da Conceição B S M; Araújo, Alberto N

    2006-10-15

    A flow-batch manifold coupled to a flame atomic absorption spectrometer was evaluated to assess the iron content by the internal standard method in hydrated ethanol used as fuel in automotive industry. For this assessment official methods require calibration procedures with matrix matching, making it difficult to obtain accurate results for samples adulterated by the addition of water. Nickel was selected as the internal standard since it is usually absent in samples and because it requires similar conditions of atomization. After procedure optimization, which requires about 4.25mL of sample and standard per measurement, it was possible to get linear analytical response for iron concentrations between 0.12 and 1.40mgL(-1) and a detection limit of 0.04mgL(-1). Eighteen samples were collected randomly from fuel stations in Pernambuco (Brazil) and iron concentration was determined using the proposed procedure. Comparison of results obtained (0.20-1.50mgL(-1)) showed a mean standard error of 3.9%, with 3.8% and 2.3% calculated for the mean variation coefficients of the proposed method and the reference procedure, respectively. For adulterated samples (0.12-0.64mgL(-1)), the mean standard error was 4.8% when compared with the standard addition method. These results allowed concluding that the proposed procedure is adequate to accomplish the determination of iron in ethanol fuel in a large scale basis with a sampling rate of about 10h(-1).

  14. Comparison of various alkali gas-cell atomic-frequency standards. Technical report

    SciTech Connect

    Camparo, J.C.; Frueholz, R.P.

    1988-02-12

    The present calculations indicate that a Rubidium gas cell standard shows the greatest potential for frequency stability, and in this regard nature has been uncommonly propitious. One should not, however, interpret this result as a superiority of the Rb87 standard in all regards. For example, if it is of primary importance to construct a miniature gas-cell standard, then cesium might prove to be more advantageous given the fact that its minimum-volume cavity occupies less than half the volume of a corresponding Rb87 cavity. Additionally, magnetic field sensitivities are less for Cs133 as a consequence of its greater hyperfine transition frequency. The only statement one should make regarding the present results is that, of all the possible alkali gas-cell standards that could be considered, a Rb87 standard appears to yield the best attainable short-noise-limited performance.

  15. Historical Review of Atomic Frequency Standards Used in Space Systems - 10 Year Update

    DTIC Science & Technology

    2007-01-01

    CASSINI - HUYGENS MISSION The Cassini - Huygens mission to Saturn and its moon Titan began with the launch on 15 October 1997 and completed with the...The transmitter ultrastable oscillator (TUSO) was on the Huygens probe and the receiver ultrastable oscillator (RUSO) was on the Cassini orbiter...the newer systems (Galileo, GPS IIR and IIF, GLONASS-M, Cassini - Huygens , AEHF, and QZSS) and potential space systems (PARCS and PHARAO) using atomic

  16. Real-Time GPS Monitoring of Atomic Frequency Standards in the Canadian Active Control System (CACS)

    DTIC Science & Technology

    1998-12-01

    orbit predictions and RTACP coordinates in a least-squares adjustment to determine satellite and station clock offsets with respect to a virtual ... reference clock (VRC). The VRC is maintained us a weighted mean of RTACP long-term clock models. The VRC is related to the mean GPS system time using a long

  17. Studies on Temperature Dependence of Rubidium Lamp for Atomic Frequency Standard

    NASA Astrophysics Data System (ADS)

    Ghosal, Bikash; Banik, Alak; Vats, Vaibhav; Pal, Sukamal; Bahl, R. K.

    2011-10-01

    Rb lamp is a very critical component of the Rb atomic clock's Physics Package. The Rb lamp's performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110° C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rb lamp under various operating conditions are reported in the paper.

  18. Studies on Temperature Dependence of Rubidium Lamp for Atomic Frequency Standard

    SciTech Connect

    Ghosal, Bikash; Banik, Alak; Vats, Vaibhav; Pal, Sukamal; Bahl, R. K

    2011-10-20

    Rb lamp is a very critical component of the Rb atomic clock's Physics Package. The Rb lamp's performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110 deg. C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rb lamp under various operating conditions are reported in the paper.

  19. New microwave excitation signal generating circuit for quantum frequency standard on the atoms of caesium Cs133

    NASA Astrophysics Data System (ADS)

    Petrov, A. A.; Davydov, V. V.

    2016-03-01

    In this work the study, design, development and experimental results of a new microwave excitation signal generating circuit are presented. New design of this circuit is based on the method of direct digital synthesis. The results of theoretical calculations and experimental researches show that the new design not only has a high precision, but also has an improvement in the spectral characteristics of the output signal. Range of generated output frequencies is expanded, that leads to the possibility of detuning the frequency of the neighboring resonance of spectral line and adjust the C-field in quantum frequency standard. Experimental research of the metrological characteristics of the quantum frequency standard on the atoms of caesium with a new functional unit showed an improvement in the daily frequency stability.

  20. High-speed imaging upgrade for a standard sample scanning atomic force microscope using small cantilevers

    SciTech Connect

    Adams, Jonathan D.; Nievergelt, Adrian; Erickson, Blake W.; Yang, Chen; Dukic, Maja; Fantner, Georg E.

    2014-09-15

    We present an atomic force microscope (AFM) head for optical beam deflection on small cantilevers. Our AFM head is designed to be small in size, easily integrated into a commercial AFM system, and has a modular architecture facilitating exchange of the optical and electronic assemblies. We present two different designs for both the optical beam deflection and the electronic readout systems, and evaluate their performance. Using small cantilevers with our AFM head on an otherwise unmodified commercial AFM system, we are able to take tapping mode images approximately 5–10 times faster compared to the same AFM system using large cantilevers. By using additional scanner turnaround resonance compensation and a controller designed for high-speed AFM imaging, we show tapping mode imaging of lipid bilayers at line scan rates of 100–500 Hz for scan areas of several micrometers in size.

  1. Determining Optimum C-Field Settings that Minimize Output Frequency Variations in Cesium Atomic Frequency Standards

    DTIC Science & Technology

    1989-11-01

    current setting is probably on the order of parts in lo4 in our laboratory environment over the three months during which data were taken; this...hardware and long-term frequency-stability measurements. This work was supported, in part , by the U.S. Air Force Space Systems Division under Contract...Long-Term Stability in Cesium Beam Frequency Standards," IEEE Trans. Ultrasonics , Ferroelectronics, and Frequency Control UFFC-34 [6], 598-601 (Novem

  2. UTC(OP) based on LNE-SYRTE atomic fountain primary frequency standards

    NASA Astrophysics Data System (ADS)

    Rovera, G. D.; Bize, S.; Chupin, B.; Guéna, J.; Laurent, Ph; Rosenbusch, P.; Uhrich, P.; Abgrall, M.

    2016-06-01

    UTC(OP), the French national realization of the international coordinated universal time, was redesigned and rebuilt. The first step was the implementation in October 2012 of a new algorithm based on a H-maser and on atomic fountain data. Thanks to the new implementation, the stability of UTC(OP) was dramatically improved and UTC(OP) competes with the best time scales available today. Then the hardware generation and distribution of the UTC(OP) physical signals were replaced. Part of the new hardware is composed of commercial devices, but the key elements were specifically developed. One of them is a special switch that allows the UTC(OP) signals to be derived from one of two time scales, based on two different H-masers, which are generated simultaneously. This insures the continuity of the UTC(OP) signal even when a change of the reference H-maser is required. With the new hardware implementation, UTC(OP) is made available through three coherent signals: 100 MHz, 10 MHz and 1 PPS. For more than 3 years, UTC(OP) remained well below 10 ns close to UTC, with a difference even less than 5 ns if we except a short period around MJD 56650.

  3. The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards

    NASA Technical Reports Server (NTRS)

    Riley, William J.

    1990-01-01

    Environmental sensitivity is often the most significant limitation to the practical stability of rubidium frequency standards (RFS). For example, temperature sensitivity can cause a rapid frequency change of several parts in 10(exp 10) for a tactical RFS that has an aging of only 1 times 10(exp -11)/month. Other important environmental factors are barometric pressure, vibration, magnetic field, and nuclear radiation. The physical mechanisms that lie behind these environmental sensitivities are considered. These physical mechanisms are related to the performance of actual rubidium frequency standards. For the user of these devices, a better knowledge of the causes for Rb clock instability will aid in their testing and proper application. For the time frequency specialist, a review of these factors may prove useful toward improving RFS design. Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of dc magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environment factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget with large unit-to-unit variations. Today's rubidium frequency standards span a wide performance range from small, inexpensive units with pp 10(exp 10) error budgets to larger, higher performance versions offering pp 10(exp 10) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case and how to make improvements are discussed.

  4. Speciation of zinc in low molecular weight proteins of breast milk and infant formulas by size exclusion chromatography/flame atomic absorption spectroscopy.

    PubMed

    Bermejo, P; Peña, E M; Fompedriña, D; Domínguez, R; Bermejo, A; Cocho, J A; Fernández, J R; Fraga, J M

    2001-01-01

    Size exclusion chromatography (SEC) and flame atomic absorption spectroscopy (FAAS) were used for the separation of metal-containing species in milk whey. After milk ultracentrifugation, the sample was injected into a TSK-Gel G2000 glass column and eluted with 0.2M NH4NO3-NH3, pH 6.7. Low molecular weight proteins were fractionated, and the fractions were characterized by molecular weight. Zinc distributions were obtained by FAAS using a high performance nebulizer. The method was very sensitive (limit of detection = 2.6 x 10(-3) microg/mL; limit of quantitation = 8.9 x 10(-3) microg/mL) and precise (RSDs < or =10%). This method was applied to the determination of Zn in binding compounds in breast milk whey and in commercial cow's milk-based formulas. Distribution patterns were different. The presence of Zn in most fractions in breast milk was most significant, whereas in infant formulas Zn was detected only in fractions of molecular weight <5 kDa and in the highest molecular weight peak.

  5. Assignment of Weight-Based Antibody Units for Seven Additional Serotypes to a Human Pneumococcal Standard Reference Serum, 007sp.

    PubMed

    Goldblatt, D; Tan, C Y; Burbidge, P; McElhiney, S; McLaughlin, L; Tucker, R; Rauh, M; Sidhu, M; Giardina, P C

    2015-11-01

    The pneumococcal enzyme-linked immunosorbent assay (ELISA) reference standard serum, lot 89SF, has been in use since 1990 and was replaced in 2013 with a new reference standard, 007sp, that is projected to be available for the next 25 years. 007sp was generated under an FDA-approved clinical protocol; 278 adult volunteers were immunized with the 23-valent unconjugated polysaccharide vaccine Pneumovax II, and a unit of blood was obtained twice from each immunized subject within 120 days following immunization. Pooled serum was prepared from the plasma of 262 subjects, filled at 6 ml per vial, and lyophilized. Five independent laboratories participated in bridging the serotype-specific IgG assignments for 89SF to the new reference standard, 007sp, to establish equivalent reference values for 13 pneumococcal capsular serotypes (1,3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) by using the WHO reference ELISA. In a second study involving three laboratories, a similar protocol was used to assign weight-based IgG concentrations in micrograms per ml to 007sp of seven serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) also present in the 23-valent pneumococcal unconjugated polysaccharide vaccine. In addition, the IgG assignments for a 12-member WHO quality control (QC) serum panel were also extended to cover these seven serotypes. Agreement was excellent, with a concordance correlation coefficient (r(c)) of >0.996 when each laboratory was compared to the assigned values for the 12 WHO QC serum samples. There are four remaining pneumococcal serotypes (2, 9N, 17F, and 20) found in Pneumovax II for which IgG assignments exist for 89SF and remain to be bridged.

  6. The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards.

    PubMed

    Riley, W R

    1992-01-01

    The physical mechanisms behind environmental sensitivity are considered, and they are related to the performances of rubidium frequency standards (RFSs). Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of DC magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environmental factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget, with large unit-to-unit variations. Today's RFSs span a wide performance range from small, inexpensive units with pp10(10) error budgets to larger, higher-performance versions offering pp10(14) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case is explained, and some insight into how to make improvements is offered.

  7. Semi-exact concentric atomic density fitting: Reduced cost and increased accuracy compared to standard density fitting

    SciTech Connect

    Hollman, David S.; Schaefer, Henry F.; Valeev, Edward F.

    2014-02-14

    A local density fitting scheme is considered in which atomic orbital (AO) products are approximated using only auxiliary AOs located on one of the nuclei in that product. The possibility of variational collapse to an unphysical “attractive electron” state that can affect such density fitting [P. Merlot, T. Kjærgaard, T. Helgaker, R. Lindh, F. Aquilante, S. Reine, and T. B. Pedersen, J. Comput. Chem. 34, 1486 (2013)] is alleviated by including atom-wise semidiagonal integrals exactly. Our approach leads to a significant decrease in the computational cost of density fitting for Hartree–Fock theory while still producing results with errors 2–5 times smaller than standard, nonlocal density fitting. Our method allows for large Hartree–Fock and density functional theory computations with exact exchange to be carried out efficiently on large molecules, which we demonstrate by benchmarking our method on 200 of the most widely used prescription drug molecules. Our new fitting scheme leads to smooth and artifact-free potential energy surfaces and the possibility of relatively simple analytic gradients.

  8. Rheological and molecular weight comparisons of approved hyaluronic acid products - preliminary standards for establishing class III medical device equivalence.

    PubMed

    Braithwaite, Gavin J C; Daley, Michael J; Toledo-Velasquez, David

    2016-01-01

    Hyaluronic acid of various molecular weights has been in use for the treatment of osteoarthritis knee pain for decades. Worldwide, these products are regulated as either as drugs or devices and in some countries as both. In the US, this class of products is regulated as Class III medical devices, which places specific regulatory requirements on developers of these materials under a Pre-Market Approval process, typically requiring data from prospective randomized controlled clinical studies. In 1984 pharmaceutical manufacturers became able to file an Abbreviated New Drug Application for approval of a generic drug, thus establishing standards for demonstrating equivalence to an existing chemical entity. Recently, the first biosimilar, or 'generic biologic', was approved. Biosimilars are biological products that are approved by the FDA because they are 'highly similar' to a reference product, and have been shown to have no clinically meaningful differences from the reference product. For devices, Class II medical devices have a pathway for declaring equivalence to an existing product by filing a 510 k application for FDA clearance. However, until recently no equivalent regulatory pathway was available to Class III devices. In this paper, we consider the critical mechanical performance parameters for intra-articular hyaluronic products to demonstrate indistinguishable characteristics. Analogous to the aforementioned pathways that allow for a demonstration of equivalence, we examine these parameters for an existing, marketed device and compare molecular weight and rheological properties of multiple batches of a similar product. We propose that this establishes a scientific rationale for establishing Class III medical device equivalence.

  9. Evidence of radiation-induced reduction of height and body weight from repeated measurements of adults exposed in childhood to the atomic bombs

    SciTech Connect

    Otake, Masanori; Funamoto, Sachiyo; Fujikoshi, Yasunori; Schull, W.J.

    1994-10-01

    Reduction of growth from exposure to atomic bomb radiation has been examined using individuals under 10 years old at the time of the bombing (ATB) and a growth curve analysis based on measurements of height and weight made in the course of the 4th-7th cycles of the Adult Health Study examinations (1964-1972). As expected, the largest difference in growth to emerge is between males and females. However, a highly significant reduction of growth associated with dose (DS86) was observed among those survivors for whom four repeated measurements of height and weight were available. Longitudinal analysis of a more extended data set (n = 821), using expected values based on simple linear regression models fitted to the three available sets of measurements of height and weight on the 254 individuals with a missing measurement, also indicates a significant radiation-related growth reduction. The possible contribution of such factors as poor nutrition and disruption of normal family life in the years immediately after the war is difficult to evaluate, but the effects of socioeconomic factors on the analysis of these data are discussed. 33 refs., 5 figs., 3 tabs.

  10. Laser induced asymmetry and inhomogeneous broadening of the microwave lineshape of a gas cell atomic frequency standard

    NASA Technical Reports Server (NTRS)

    Camparo, J. C.; Freuholz, R. P.; Volk, C. H.

    1983-01-01

    The possibility of replacing the RF discharge lamp in a rubidium gas cell clock with a single mode laser diode is addressed. Since the short term stability of the rubidium frequency standard is limited by the shot noise of the photodetector, an increased signal-to-noise ratio due to more efficient laser diode optical pumping might improve the short term performance. Because the emission wavelength of the laser diode can be tuned, improved long term performance could be gained through the control of the light shift effect. However, due to the nature of the gas cell frequency standard, various physical phenomena are strongly coupled in their effect on the frequency output, and thus careful consideration must be given to any change in one parameter because of its interrelation with other parameters. Some investigations concerning the coupled effect of the optical and microwave fields in the rubidium atomic clock are reported. It is shown that this type of coupling is an important consideration for any attempt to incorporate a laser diode into a gas cell clock.

  11. Accurate analytical measurements in the atomic force microscope: a microfabricated spring constant standard potentially traceable to the SI

    NASA Astrophysics Data System (ADS)

    Cumpson, Peter J.; Hedley, John

    2003-12-01

    Calibration of atomic force microscope (AFM) cantilevers is necessary for the measurement of nanonewton and piconewton forces, which are critical to analytical applications of AFM in the analysis of polymer surfaces, biological structures and organic molecules at nanoscale lateral resolution. We have developed a compact and easy-to-use reference artefact for this calibration, using a method that allows traceability to the SI (Système International). Traceability is crucial to ensure that force measurements by AFM are comparable to those made by optical tweezers and other methods. The new non-contact calibration method measures the spring constant of these artefacts, by a combination of electrical measurements and Doppler velocimetry. The device was fabricated by silicon surface micromachining. The device allows AFM cantilevers to be calibrated quite easily by the 'cantilever-on-reference' method, with our reference device having a spring constant uncertainty of around ± 5% at one standard deviation. A simple substitution of the analogue velocimeter used in this work with a digital model should reduce this uncertainty to around ± 2%. Both are significant improvements on current practice, and allow traceability to the SI for the first time at these nanonewton levels.

  12. Randomized trial of human milk cream as a supplement to standard fortification of an exclusive human milk-based diet in infants 750-1250 g birth weight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to evaluate whether premature infants who received an exclusive human milk (HM)-based diet and a HM-derived cream supplement (cream) would have weight gain (g/kg/d) at least as good as infants receiving a standard feeding regimen (control). In a prospective noninferiority, randomiz...

  13. Time-order errors and standard-position effects in duration discrimination: An experimental study and an analysis by the sensation-weighting model.

    PubMed

    Hellström, Åke; Rammsayer, Thomas H

    2015-10-01

    Studies have shown that the discriminability of successive time intervals depends on the presentation order of the standard (St) and the comparison (Co) stimuli. Also, this order affects the point of subjective equality. The first effect is here called the standard-position effect (SPE); the latter is known as the time-order error. In the present study, we investigated how these two effects vary across interval types and standard durations, using Hellström's sensation-weighting model to describe the results and relate them to stimulus comparison mechanisms. In Experiment 1, four modes of interval presentation were used, factorially combining interval type (filled, empty) and sensory modality (auditory, visual). For each mode, two presentation orders (St-Co, Co-St) and two standard durations (100 ms, 1,000 ms) were used; half of the participants received correctness feedback, and half of them did not. The interstimulus interval was 900 ms. The SPEs were negative (i.e., a smaller difference limen for St-Co than for Co-St), except for the filled-auditory and empty-visual 100-ms standards, for which a positive effect was obtained. In Experiment 2, duration discrimination was investigated for filled auditory intervals with four standards between 100 and 1,000 ms, an interstimulus interval of 900 ms, and no feedback. Standard duration interacted with presentation order, here yielding SPEs that were negative for standards of 100 and 1,000 ms, but positive for 215 and 464 ms. Our findings indicate that the SPE can be positive as well as negative, depending on the interval type and standard duration, reflecting the relative weighting of the stimulus information, as is described by the sensation-weighting model.

  14. Establishment of replacement batches for heparin low-molecular-mass for calibration CRS, and the International Standard Low Molecular Weight Heparin for Calibration.

    PubMed

    Mulloy, B; Heath, A; Behr-Gross, M-E

    2007-12-01

    An international collaborative study involving fourteen laboratories has taken place, organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM) with National Institute for Biological Standards & Control (NIBSC) (in its capacity as a World Health Organisation (WHO) Laboratory for Biological Standardisation) to provide supporting data for the establishment of replacement batches of Heparin Low-Molecular-Mass (LMM) for Calibration Chemical Reference Substance (CRS), and of the International Reference Reagent (IRR) Low Molecular Weight Heparin for Molecular Weight Calibration. A batch of low-molecular-mass heparin was donated to the organisers and candidate preparations of freeze-dried heparin were produced at NIBSC and EDQM. The establishment study was organised in two phases: a prequalification (phase 1, performed in 3 laboratories in 2005) followed by an international collaborative study (phase 2). In phase 2, started in March 2006, molecular mass parameters were determined for seven different LMM heparin samples using the current CRS batch and two batches of candidate replacement material with a defined number average relative molecular mass (Mn) of 3,700, determined in phase 1. The values calculated using the candidates as standard were systematically different from values calculated using the current batch with its assigned number-average molecular mass (Mna) of 3,700. Using raw data supplied by participants, molecular mass parameters were recalculated using the candidates as standard with values for Mna of 3,800 and 3,900. Values for these parameters agreed more closely with those calculated using the current batch supporting the fact that the candidates, though similar to batch 1 in view of the production processes used, differ slightly in terms of molecular mass distribution. Therefore establishment of the candidates was recommended with an assigned Mna value of 3,800 that is both consistent with phase 1 results and guarantees

  15. High Atomic Weight Isotope Separator.

    DTIC Science & Technology

    This patent discusses a method of separating one isotopic species of a given element from a mixture. Collisionless plasma instabilities slow down the ions and oppositely charged electrodes separate the isotopes.

  16. Probing exchange kinetics and atomic resolution dynamics in high-molecular-weight complexes using dark-state exchange saturation transfer NMR spectroscopy.

    PubMed

    Fawzi, Nicolas L; Ying, Jinfa; Torchia, Dennis A; Clore, G Marius

    2012-07-19

    We present the protocol for the measurement and analysis of dark-state exchange saturation transfer (DEST), a novel solution NMR method for characterizing, at atomic resolution, the interaction between an NMR-'visible' free species and an NMR-'invisible' species transiently bound to a very high-molecular-weight (>1 MDa) macromolecular entity. The reduced rate of reorientational motion in the bound state that precludes characterization by traditional NMR methods permits the observation of DEST. (15)N-DEST profiles are measured on a sample comprising the dark state in exchange with an NMR-visible species; in addition, the difference (ΔR(2)) in (15)N transverse relaxation rates between this sample and a control sample comprising only the NMR-visible species is also obtained. The (15)N-DEST and ΔR(2) data for all residues are then fitted simultaneously to the McConnell equations for various exchange models describing the residue-specific dynamics in the bound state(s) and the interconversion rate constants. Although the length of the experiments depends strongly on sample conditions, approximately 1 week of NMR spectrometer time was sufficient for full characterization of samples of amyloid-β (Aβ) at concentrations of ~100 μM.

  17. Comparison of a noise-weighted filtered backprojection algorithm with the Standard MLEM algorithm for poisson noise.

    PubMed

    Zeng, Gengsheng L

    2013-12-01

    Iterative maximum-likelihood expectation maximization and ordered-subset expectation maximization algorithms are excellent for image reconstruction and usually provide better images than filtered backprojection (FBP). Recently, an FBP algorithm able to incorporate noise weighting during reconstruction was developed. This paper compares the performance of the noise-weighted FBP algorithm and the iterative maximum-likelihood expectation maximization algorithm with Poisson noise-corrupted emission data generated by computer simulations and a SPECT experimental study. The results show comparable performance for these 2 algorithms.

  18. Nano-scale simulative measuring model for tapping mode atomic force microscopy and analysis for measuring a nano-scale ladder-shape standard sample.

    PubMed

    Lin, Zone-Ching; Chou, Ming-Ho

    2010-07-01

    This study proposes to construct a nano-scale simulative measuring model of Tapping Mode Atomic Force Microscopy (TM-AFM), compare with the edge effect of simulative and measurement results. It combines with the Morse potential and vibration theory to calculate the tip-sample atomic interaction force between probe and sample. Used Silicon atoms (Si) arrange the shape of the rectangular cantilever probe and the nano-scale ladder-shape standard sample atomic model. The simulative measurements are compared with the results for the simulative measurements and experimental measurement. It is found that the scan rate and the probe tip's bevel angle are the two reasons to cause the surface error and edge effect of measuring the nano-scale ladder-shape standard sample by TM-AFM. And the bevel angle is about equal to the probe tip's bevel angle from the results of simulated and experimented on the vertical section of the sample edge. To compare with the edge effect between the simulation and experimental measurement, its error is small. It could be verified that the constructed simulative measuring model for TM-AFM in this article is reasonable.

  19. Does the type of weight loss diet affect who participates in a behavioral weight loss intervention? A comparison of participants for a plant-based diet versus a standard diet trial.

    PubMed

    Turner-McGrievy, Gabrielle M; Davidson, Charis R; Wilcox, Sara

    2014-02-01

    Studies have found that people following plant-based eating styles, such as vegan or vegetarian diets, often have different demographic characteristics, eating styles, and physical activity (PA) levels than individuals following an omnivorous dietary pattern. There has been no research examining if there are differences in these characteristics among people who are willing to participate in a weight loss intervention using plant-based dietary approaches as compared to a standard reduced calorie approach, which does not exclude food groups. The present study compared baseline characteristics (demographics, dietary intake, eating behaviors (Eating Behavior Inventory), and PA (Paffenbarger Physical Activity Questionnaire)) of participants enrolling in two different 6-month behavioral weight loss studies: the mobile Pounds Off Digitally (mPOD) study, which used a standard reduced calorie dietary approach and the New Dietary Interventions to Enhance the Treatments for weight loss (New DIETs) study, which randomized participants to follow one of five different dietary approaches (vegan, vegetarian, pesco-vegetarian, semi-vegetarian, or omnivorous diets). There were no differences in baseline demographics with the exception of New DIETs participants being older (48.5±8.3years versus 42.9±11.2, P=0.001) and having a higher Body Mass Index (BMI, 35.2±5.3kg/m(2) versus 32.6±4.7kg/m(2), P=0.001) than mPOD participants. In age- and BMI-adjusted models, there were no differences in EBI scores or in any dietary variables, with the exception of vitamin C (85.6±5.9mg/d mPOD versus 63.4±7.4mg/d New DIETs, P=0.02). New DIETs participants reported higher levels of intentional PA/day (180.0±18.1kcal/d) than mPOD participants (108.8±14.4kcal/d, P=0.003), which may have been the result of New DIETs study recommendations to avoid increasing or decreasing PA during the study. The findings of this study demonstrate that using plant-based dietary approaches for weight loss

  20. Effects of neutron fluence on the operating characteristics of diode lasers used in atomic frequency standards. Technical report

    SciTech Connect

    Frueholz, R.P.; Camparo, J.C.; Delcamp, S.B.; Barnes, C.E.

    1990-08-15

    One of the next major advances in rubidium and cesium atomic clock technology will center on the use of diode lasers for optical pumping. The atomic clocks used on board satellites have the potential to interact with various forms of radiation that are not present in the laboratory environment, and the effects of this radiation on the laser's operating characteristics relevant to clock applications are not well known. The present report describes an ongoing experiment to study the effects of neutron fluence on the operating characteristics of Mitsubishi Transverse Junction Stripe (TJS) AlGaAs diode lasers. Different models of the TJS diode laser produce optical radiation in both the 780 and 850 nm range, appropriate for optical pumping in rubidium and cesium atomic clocks, respectively. In this phase, a set of TJS diode lasers has been exposed to a neutron fluence of 2 x 1012 n/cm2, and four laser characteristics were examined after each exposure. The laser's light output versus injection current and single-mode linewidth versus output power both influence the efficiency of optical pumping and hence the atomic clock's signal-to-noise ratio. We have also measured the laser's single-mode wavelength versus injection current (laser tuning). Since the diode laser must remain tuned to the appropriate atomic transition, any degradation in the ability to tune the laser will impact atomic clock reliability. Finally, the diode laser's gain curve has been studied at several injection currents below threshold. This diode laser characteristic is taken as an indicator of the neutron damage mechanisms in the laser's semiconductor material. Changes in these characteristics due to the neutron exposure are reported.

  1. Foundations of Metrology: Important Early Works on Weights and Measures in the Library of the National Bureau of Standards.

    ERIC Educational Resources Information Center

    Terner, Janet R.

    The purpose of this project was to survey the National Bureau of Standards library holdings of pre-1900 works on metrology and from these, to assemble a special collection of historically important documents. The 265 imprints selected for the collection are listed in this report. Each entry includes the main author, title, imprint, and collation…

  2. Aligning School Finance with Academic Standards: A Weighted-Student Formula Based on a Survey of Practitioners. Occasional Paper

    ERIC Educational Resources Information Center

    Sonstelie, Jon

    2007-01-01

    This report contains estimates of the cost to California's public schools of meeting the state's achievement standards. In the aggregate, the cost is about 40 percent greater than the expenditures of California schools in 2003-04. The bulk of these additional costs are for resources needed to boost achievement in schools primarily serving students…

  3. Accurate physical laws can permit new standard units: The two laws F→=ma→ and the proportionality of weight to mass

    NASA Astrophysics Data System (ADS)

    Saslow, Wayne M.

    2014-04-01

    Three common approaches to F→=ma→ are: (1) as an exactly true definition of force F→ in terms of measured inertial mass m and measured acceleration a→; (2) as an exactly true axiom relating measured values of a→, F→ and m; and (3) as an imperfect but accurately true physical law relating measured a→ to measured F→, with m an experimentally determined, matter-dependent constant, in the spirit of the resistance R in Ohm's law. In the third case, the natural units are those of a→ and F→, where a→ is normally specified using distance and time as standard units, and F→ from a spring scale as a standard unit; thus mass units are derived from force, distance, and time units such as newtons, meters, and seconds. The present work develops the third approach when one includes a second physical law (again, imperfect but accurate)—that balance-scale weight W is proportional to m—and the fact that balance-scale measurements of relative weight are more accurate than those of absolute force. When distance and time also are more accurately measurable than absolute force, this second physical law permits a shift to standards of mass, distance, and time units, such as kilograms, meters, and seconds, with the unit of force—the newton—a derived unit. However, were force and distance more accurately measurable than time (e.g., time measured with an hourglass), this second physical law would permit a shift to standards of force, mass, and distance units such as newtons, kilograms, and meters, with the unit of time—the second—a derived unit. Therefore, the choice of the most accurate standard units depends both on what is most accurately measurable and on the accuracy of physical law.

  4. Internal quality control system for non-stationary, non-ergodic analytical processes based upon exponentially weighted estimation of process means and process standard deviation.

    PubMed

    Jansen, Rob T P; Laeven, Mark; Kardol, Wim

    2002-06-01

    The analytical processes in clinical laboratories should be considered to be non-stationary, non-ergodic and probably non-stochastic processes. Both the process mean and the process standard deviation vary. The variation can be different at different levels of concentration. This behavior is shown in five examples of different analytical systems: alkaline phosphatase on the Hitachi 911 analyzer (Roche), vitamin B12 on the Access analyzer (Beckman), prothrombin time and activated partial thromboplastin time on the STA Compact analyzer (Roche) and PO2 on the ABL 520 analyzer (Radiometer). A model is proposed to assess the status of a process. An exponentially weighted moving average and standard deviation was used to estimate process mean and standard deviation. Process means were estimated overall and for each control level. The process standard deviation was estimated in terms of within-run standard deviation. Limits were defined in accordance with state of the art- or biological variance-derived cut-offs. The examples given are real, not simulated, data. Individual control sample results were normalized to a target value and target standard deviation. The normalized values were used in the exponentially weighted algorithm. The weighting factor was based on a process time constant, which was estimated from the period between two calibration or maintenance procedures. The proposed system was compared with Westgard rules. The Westgard rules perform well, despite the underlying presumption of ergodicity. This is mainly caused by the introduction of the starting rule of 12s, which proves essential to prevent a large number of rule violations. The probability of reporting a test result with an analytical error that exceeds the total allowable error was calculated for the proposed system as well as for the Westgard rules. The proposed method performed better. The proposed algorithm was implemented in a computer program running on computers to which the analyzers were

  5. Weight-for-age standard score - distribution and effect on in-hospital mortality: A retrospective analysis in pediatric cardiac surgery

    PubMed Central

    George, Antony; Jagannath, Pushpa; Joshi, Shreedhar S.; Jagadeesh, A. M.

    2015-01-01

    Objective: To study the distribution of weight for age standard score (Z score) in pediatric cardiac surgery and its effect on in-hospital mortality. Introduction: WHO recommends Standard Score (Z score) to quantify and describe anthropometric data. The distribution of weight for age Z score and its effect on mortality in congenital heart surgery has not been studied. Methods: All patients of younger than 5 years who underwent cardiac surgery from July 2007 to June 2013, under single surgical unit at our institute were enrolled. Z score for weight for age was calculated. Patients were classified according to Z score and mortality across the classes was compared. Discrimination and calibration of the for Z score model was assessed. Improvement in predictability of mortality after addition of Z score to Aristotle Comprehensive Complexity (ACC) score was analyzed. Results: The median Z score was -3.2 (Interquartile range -4.24 to -1.91] with weight (mean±SD) of 8.4 ± 3.38 kg. Overall mortality was 11.5%. 71% and 52.59% of patients had Z score < -2 and < -3 respectively. Lower Z score classes were associated with progressively increasing mortality. Z score as continuous variable was associated with O.R. of 0.622 (95% CI- 0.527 to 0.733, P < 0.0001) for in-hospital mortality and remained significant predictor even after adjusting for age, gender, bypass duration and ACC score. Addition of Z score to ACC score improved its predictability for in-hosptial mortality (δC - 0.0661 [95% CI - 0.017 to 0.0595, P = 0.0169], IDI- 3.83% [95% CI - 0.017 to 0.0595, P = 0.00042]). Conclusion: Z scores were lower in our cohort and were associated with in-hospital mortality. Addition of Z score to ACC score significantly improves predictive ability for in-hospital mortality. PMID:26139742

  6. Gestational weight gain standards based on women enrolled in the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project: a prospective longitudinal cohort study

    PubMed Central

    Bishop, Deborah C; Pang, Ruyan; Ohuma, Eric O; Kac, Gilberto; Abrams, Barbara; Rasmussen, Kathleen; Barros, Fernando C; Hirst, Jane E; Lambert, Ann; Papageorghiou, Aris T; Stones, William; Jaffer, Yasmin A; Altman, Douglas G; Noble, J Alison; Giolito, Maria Rosa; Gravett, Michael G; Purwar, Manorama; Kennedy, Stephen H; Bhutta, Zulfiqar A; Villar, José

    2016-01-01

    Objective To describe patterns in maternal gestational weight gain (GWG) in healthy pregnancies with good maternal and perinatal outcomes. Design Prospective longitudinal observational study. Setting Eight geographically diverse urban regions in Brazil, China, India, Italy, Kenya, Oman, United Kingdom, and United States, April 2009 to March 2014. Participants Healthy, well nourished, and educated women enrolled in the Fetal Growth Longitudinal Study component of the INTERGROWTH-21st Project, who had a body mass index (BMI) of 18.50-24.99 in the first trimester of pregnancy. Main outcome measures Maternal weight measured with standardised methods and identical equipment every five weeks (plus/minus one week) from the first antenatal visit (<14 weeks’ gestation) to delivery. After confirmation that data from the study sites could be pooled, a multilevel, linear regression analysis accounting for repeated measures, adjusted for gestational age, was applied to produce the GWG values. Results 13 108 pregnant women at <14 weeks’ gestation were screened, and 4607 met the eligibility criteria, provided consent, and were enrolled. The variance within sites (59.6%) was six times higher than the variance between sites (9.6%). The mean GWGs were 1.64 kg, 2.86 kg, 2.86 kg, 2.59 kg, and 2.56 kg for the gestational age windows 14-18+6 weeks, 19-23+6 weeks, 24-28+6 weeks, 29-33+6 weeks, and 34-40+0 weeks, respectively. Total mean weight gain at 40 weeks’ gestation was 13.7 (SD 4.5) kg for 3097 eligible women with a normal BMI in the first trimester. Of all the weight measurements, 71.7% (10 639/14 846) and 94.9% (14 085/14 846) fell within the expected 1 SD and 2 SD thresholds, respectively. Data were used to determine fitted 3rd, 10th, 25th, 50th, 75th, 90th, and 97th smoothed GWG centiles by exact week of gestation, with equations for the mean and standard deviation to calculate any desired centiles according to gestational age in exact weeks. Conclusions Weight

  7. New scheme of the microwave signal formation for quantum frequency standard on the atoms of caesium-133

    NASA Astrophysics Data System (ADS)

    Petrov, A. A.; Davydov, V. V.

    2016-11-01

    In present work several directions of quantum frequency standard modernization are considered. A new implementation of a frequency synthesizer and a magnetic field control unit are presented. Experimental study of a frequency synthesizer showed improvement parameters of a microwave-excitation signal, such as step frequency tuning, time frequency tuning, range of generating frequencies and spectral characteristics. Magnetic field control unit eliminates one of the most important perturbing factors affecting the long-term frequency stability. Daily frequency stability of quantum frequency standard improved on 15%.

  8. 75 FR 6070 - Notice of Public Meeting on the International Atomic Energy Agency Basic Safety Standards Version...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-05

    ... was published in 1996 ( http://www-pub.iaea.org/MTCD/publications/PDF/ss-115-web/Pub996_web-1a.pdf... draft (DS379) is available for viewing and downloading on the Internet at: http://www-ns.iaea.org/standards/documents/draft-ms-posted.asp . Several other International Organizations, including the...

  9. A Derivation of the Long-Term Degradation of a Pulsed Atomic Frequency Standard from a Control-Loop Model

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    1996-01-01

    The phase of a frequency standard that uses periodic interrogation and control of a local oscillator (LO) is degraded by a long-term random-walk component induced by downconversion of LO noise into the loop passband. The Dick formula for the noise level of this degradation is derived from an explicit solution of an LO control-loop model.

  10. Efficacy of Standard Versus Enhanced Features in a Web-Based Commercial Weight-Loss Program for Obese Adults, Part 2: Randomized Controlled Trial

    PubMed Central

    Morgan, Philip J; Hutchesson, Melinda J; Callister, Robin

    2013-01-01

    Background Commercial Web-based weight-loss programs are becoming more popular and increasingly refined through the addition of enhanced features, yet few randomized controlled trials (RCTs) have independently and rigorously evaluated the efficacy of these commercial programs or additional features. Objective To determine whether overweight and obese adults randomized to an online weight-loss program with additional support features (enhanced) experienced a greater reduction in body mass index (BMI) and increased usage of program features after 12 and 24 weeks compared to those randomized to a standard online version (basic). Methods An assessor-blinded RCT comparing 301 adults (male: n=125, 41.5%; mean age: 41.9 years, SD 10.2; mean BMI: 32.2 kg/m2, SD 3.9) who were recruited and enrolled offline, and randomly allocated to basic or enhanced versions of a commercially available Web-based weight-loss program for 24 weeks. Results Retention at 24 weeks was greater in the enhanced group versus the basic group (basic 68.5%, enhanced 81.0%; P=.01). In the intention-to-treat analysis of covariance with imputation using last observation carried forward, after 24 weeks both intervention groups had reductions in key outcomes with no difference between groups: BMI (basic mean –1.1 kg/m2, SD 1.5; enhanced mean –1.3 kg/m2, SD 2.0; P=.29), weight (basic mean –3.3 kg, SD 4.7; enhanced mean –4.0 kg, SD 6.2; P=.27), waist circumference (basic mean –3.1 cm, SD 4.6; enhanced mean –4.0 cm, SD 6.2; P=.15), and waist-to-height ratio (basic mean –0.02, SD 0.03; enhanced mean –0.02, SD 0.04, P=.21). The enhanced group logged in more often at both 12 and 24 weeks, respectively (enhanced 12-week mean 34.1, SD 28.1 and 24-week mean 43.1, SD 34.0 vs basic 12-week mean 24.6, SD 25.5 and 24-week mean 31.8, SD 33.9; P=.002). Conclusions The addition of personalized e-feedback in the enhanced program provided limited additional benefits compared to a standard commercial Web

  11. Standardization and validation of a new atomic absorption spectroscopy technique for determination and quantitation of aluminium adjuvant in immunobiologicals.

    PubMed

    Mishra, Arti; Bhalla, Sumir Rai; Rawat, Sameera; Bansal, Vivek; Sehgal, Rakesh; Kumar, Sunil

    2007-10-01

    In the present study, Aluminium quantification in immunobiologicals has been described using atomic absorption spectroscopy (AAS) technique. The assay was found to be linear in 25-125 microg/ml Aluminium range. The procedure was found to be accurate for different vaccines with recoveries of external additions ranging between 93.26 and 103.41%. The mean Limit of Variation (L.V.) for both intra- and inter-assay precision was calculated to be 1.62 and 2.22%, respectively. Further the procedure was found to be robust in relation to digestion temperature, alteration in acid (HNO(3) and H(2)SO(4)) ratio used for sample digestion and storage of digested vaccine samples up to a period of 15 days. After validation, AAS method was compared for its equivalency with routinely used complexometric titration method. On simultaneously applying on seven different groups of both bacterial and viral vaccines, viz., DPT, DT, TT, Hepatitis-A and B, Antirabies vaccine (cell culture) and tetravalent DPT-Hib, a high degree of positive correlation (+0.85-0.998) among AAS and titration methods was observed. Further AAS method was found to have an edge over complexometric titration method that a group of vaccines, viz., ARV (cell culture, adsorbed) and Hepatitis-A, in which Aluminium estimation is not feasible by pharmacopoeial approved complexometric titration method (possibly due to some interference in the sample matrix), this newly described and validated AAS assay procedure delivered accurate and reproducible results.

  12. PREPARATION OF BLOCK COPOLYMERS OF POLY(STYRENE) AND POLY(T-BUTYL ACRYLATE) OF VARIOUS MOLECULAR WEIGHTS AND ARCHITECTURES BY ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    EPA Science Inventory

    Block copolymers of polystyrene and poly(t-butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N,NProbing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model.

    PubMed

    Solares, Santiago D

    2014-01-01

    This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip-sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip-sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip-sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

  13. Comparative study of some robust statistical methods: weighted, parametric, and nonparametric linear regression of HPLC convoluted peak responses using internal standard method in drug bioavailability studies.

    PubMed

    Korany, Mohamed A; Maher, Hadir M; Galal, Shereen M; Ragab, Marwa A A

    2013-05-01

    This manuscript discusses the application and the comparison between three statistical regression methods for handling data: parametric, nonparametric, and weighted regression (WR). These data were obtained from different chemometric methods applied to the high-performance liquid chromatography response data using the internal standard method. This was performed on a model drug Acyclovir which was analyzed in human plasma with the use of ganciclovir as internal standard. In vivo study was also performed. Derivative treatment of chromatographic response ratio data was followed by convolution of the resulting derivative curves using 8-points sin x i polynomials (discrete Fourier functions). This work studies and also compares the application of WR method and Theil's method, a nonparametric regression (NPR) method with the least squares parametric regression (LSPR) method, which is considered the de facto standard method used for regression. When the assumption of homoscedasticity is not met for analytical data, a simple and effective way to counteract the great influence of the high concentrations on the fitted regression line is to use WR method. WR was found to be superior to the method of LSPR as the former assumes that the y-direction error in the calibration curve will increase as x increases. Theil's NPR method was also found to be superior to the method of LSPR as the former assumes that errors could occur in both x- and y-directions and that might not be normally distributed. Most of the results showed a significant improvement in the precision and accuracy on applying WR and NPR methods relative to LSPR.

  14. A physics package for rubidium atomic frequency standard with a short-term stability of 2.4 × 10-13 τ-1/2

    NASA Astrophysics Data System (ADS)

    Hao, Qiang; Li, Wenbing; He, Shengguo; Lv, Jianfeng; Wang, Pengfei; Mei, Ganghua

    2016-12-01

    In this article, a new type of physics package with high signal to noise ratio for a rubidium atomic frequency standard is reported. To enhance the clock transition signal, a slotted tube microwave cavity with a field orientation factor of 0.93 and an absorption cell with the diameter of 30 mm were utilized in design of the cavity-cell assembly. Based on the spectral analysis of the three commonly used rubidium spectral lamps, the spectral lamp filled with Xe gas was chosen as the optical pumping source for its small line shape distortion. To suppress the shot noise of the signal, a band pass interference filter was used to filter out Xe spectral lines from the pumping light. A desk system of the rubidium frequency standard with the physics package was realized, and the short-term stability of the system was predicted and tested. The measured result is 2.4 × 10-13 τ-1/2 up to 100 s averaging time, in good agreement with the predicted one.

  15. A physics package for rubidium atomic frequency standard with a short-term stability of 2.4 × 10(-13) τ(-1/2).

    PubMed

    Hao, Qiang; Li, Wenbing; He, Shengguo; Lv, Jianfeng; Wang, Pengfei; Mei, Ganghua

    2016-12-01

    In this article, a new type of physics package with high signal to noise ratio for a rubidium atomic frequency standard is reported. To enhance the clock transition signal, a slotted tube microwave cavity with a field orientation factor of 0.93 and an absorption cell with the diameter of 30 mm were utilized in design of the cavity-cell assembly. Based on the spectral analysis of the three commonly used rubidium spectral lamps, the spectral lamp filled with Xe gas was chosen as the optical pumping source for its small line shape distortion. To suppress the shot noise of the signal, a band pass interference filter was used to filter out Xe spectral lines from the pumping light. A desk system of the rubidium frequency standard with the physics package was realized, and the short-term stability of the system was predicted and tested. The measured result is 2.4 × 10(-13) τ(-1/2) up to 100 s averaging time, in good agreement with the predicted one.

  16. Material discrimination using scattering and stopping of cosmic ray muons and electrons: Differentiating heavier from lighter metals as well as low-atomic weight materials

    NASA Astrophysics Data System (ADS)

    Blanpied, Gary; Kumar, Sankaran; Dorroh, Dustin; Morgan, Craig; Blanpied, Isabelle; Sossong, Michael; McKenney, Shawn; Nelson, Beth

    2015-06-01

    Reported is a new method to apply cosmic-ray tomography in a manner that can detect and characterize not only dense assemblages of heavy nuclei (like Special Nuclear Materials, SNM) but also assemblages of medium- and light-atomic-mass materials (such as metal parts, conventional explosives, and organic materials). Characterization may enable discrimination between permitted contents in commerce and contraband (explosives, illegal drugs, and the like). Our Multi-Mode Passive Detection System (MMPDS) relies primarily on the muon component of cosmic rays to interrogate Volumes of Interest (VOI). Muons, highly energetic and massive, pass essentially un-scattered through materials of light atomic mass and are only weakly scattered by conventional metals used in industry. Substantial scattering and absorption only occur when muons encounter sufficient thicknesses of heavy elements characteristic of lead and SNM. Electrons are appreciably scattered by light elements and stopped by sufficient thicknesses of materials containing medium-atomic-mass elements (mostly metals). Data include simulations based upon GEANT and measurements in the HMT (Half Muon Tracker) detector in Poway, CA and a package scanner in both Poway and Socorro NM. A key aspect of the present work is development of a useful parameter, designated the "stopping power" of a sample. The low-density regime, comprising organic materials up to aluminum, is characterized using very little scattering but a strong variation in stopping power. The medium-to-high density regime shows a larger variation in scattering than in stopping power. The detection of emitted gamma rays is another useful signature of some materials.

  17. Working towards accreditation by the International Standards Organization 15189 Standard: how to validate an in-house developed method an example of lead determination in whole blood by electrothermal atomic absorption spectrometry.

    PubMed

    Garcia Hejl, Carine; Ramirez, Jose Manuel; Vest, Philippe; Chianea, Denis; Renard, Christophe

    2014-09-01

    Laboratories working towards accreditation by the International Standards Organization (ISO) 15189 standard are required to demonstrate the validity of their analytical methods. The different guidelines set by various accreditation organizations make it difficult to provide objective evidence that an in-house method is fit for the intended purpose. Besides, the required performance characteristics tests and acceptance criteria are not always detailed. The laboratory must choose the most suitable validation protocol and set the acceptance criteria. Therefore, we propose a validation protocol to evaluate the performance of an in-house method. As an example, we validated the process for the detection and quantification of lead in whole blood by electrothermal absorption spectrometry. The fundamental parameters tested were, selectivity, calibration model, precision, accuracy (and uncertainty of measurement), contamination, stability of the sample, reference interval, and analytical interference. We have developed a protocol that has been applied successfully to quantify lead in whole blood by electrothermal atomic absorption spectrometry (ETAAS). In particular, our method is selective, linear, accurate, and precise, making it suitable for use in routine diagnostics.

  18. Next Generation JPL Ultra-Stable Trapped Ion Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Burt, Eric; Tucker, Blake; Larsen, Kameron; Hamell, Robert; Tjoelker, Robert

    2013-01-01

    Over the past decade, trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on two directions: 1) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements, and 2) ultra-stable atomic clocks, usually for terrestrial applications emphasizing ultimate performance. In this paper we present a new ultra-stable trapped ion clock designed, built, and tested in the second category. The first new standard, L10, will be delivered to the Naval Research Laboratory for use in characterizing DoD space clocks.

  19. Optimized microwave-assisted decomposition method for multi-element analysis of glass standard reference material and ancient glass specimens by inductively coupled plasma atomic emission spectrometry.

    PubMed

    Zachariadis, G; Dimitrakoudi, E; Anthemidis, A; Stratis, J

    2006-02-28

    A novel microwave-assisted wet-acid decomposition method for the multi-element analysis of glass samples using inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed and optimized. The SRM 621 standard reference glass material was used for this purpose, because it has similar composition with either archaeological glass specimens or common modern glasses. For the main constituents of SRM 621 (Ca, Na, Al, Fe, Mg, Ba and Ti), quality control data are given for all the examined procedures. The chemical and instrumental parameters of the method were thoroughly optimized. Thirteen acid mixtures of hydrochloric, nitric, and hydrofluoric acids in relation to two different microwave programs were examined in order to establish the most efficient protocol for the determination of metals in glass matrix. For both microwave programs, an intermediate step was employed with addition of H(3)BO(3) in order to compensate the effect of HF, which was used in all protocols. The suitability of the investigated protocols was evaluated for major (Ca, Na, Al), and minor (Fe, Mg, Ba, Ti, Mn, Cu, Sb, Co, Pb) glass constituents. The analytes were determined using multi-element matrix matched standard solutions. The analytical data matrix was processed chemometrically in order to evaluate the examined protocols in terms of their accuracy, precision and sensitivity, and eventually select the most efficient method for ancient glass. ICP-AES parameters such as spectral line, RF power and sample flow rate were optimized using the proposed protocol. Finally, the optimum method was successfully applied to the analysis of a number of ancient glass fragments.

  1. Detection of Traumatic Bone Marrow Lesions after Knee Trauma: Comparison of ADC Maps Derived from Diffusion-weighted Imaging with Standard Fat-saturated Proton Density-weighted Turbo Spin-Echo Sequences.

    PubMed

    Klengel, Alexis; Stumpp, Patrick; Klengel, Steffen; Böttger, Ina; Rönisch, Nadja; Kahn, Thomas

    2016-10-24

    Purpose To compare single-shot echo-planar diffusion-weighted imaging-derived apparent diffusion coefficient (ADC) maps with fat-saturated (FS) proton density (PD)-weighted turbo spin-echo (TSE) imaging in the detection of bone marrow lesions (BMLs) after knee trauma. Materials and Methods Institutional review board approval was obtained from Leipzig University. Written informed consent was waived. Three radiologists retrospectively re-examined 97 consecutive patients with reported knee trauma who underwent 1.5-T magnetic resonance (MR) imaging within 90 days of knee trauma. The following sequences were used: (a) sagittal T1-weighted TSE and FS PD-weighted TSE and (b) sagittal T1-weighted TSE and single-shot echo-planar diffusion-weighted imaging-derived ADC mapping. BMLs on the lateral and medial femoral condyle, lateral and medial aspect of the tibial plateau, and patella were documented. Volumetry was performed on BMLs with a thickness of at least 15 mm (major BMLs). ADC values were measured in intact bone marrow and major BMLs. A McNemar test and t tests were used as appropriate to test for significant differences between BML number and volume at an α level of .05. Results Significantly more patients showed at least one BML on ADC maps (98%, 95 of 97 patients) than on FS PD-weighted TSE images (86%, 84 of 97 patients) (P < .001). Of the affected regions detected on FS PD-weighted TSE images, 97% (170 of 175 regions) were identified consistently on ADC maps. Only 58% of the affected regions detected on ADC maps (170 of 293 regions) were identified on FS PD-weighted TSE images (P < .001). Median volume of concordant major BML was approximately two times larger on ADC maps (81 cm(3)) than on FS PD-weighted TSE images (39 cm(3)) (P < .001). The ADC values of intact bone marrow and BMLs did not overlap. Conclusion ADC maps are more sensitive than corresponding FS PD-weighted TSE images for detection of BML after knee trauma and allow detection of significantly more

  2. 14 CFR 31.14 - Weight limits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.14 Weight limits. (a) The range of weights over which the balloon may be safely operated must be established. (b) Maximum weight. The maximum weight...

  3. 14 CFR 31.14 - Weight limits.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.14 Weight limits. (a) The range of weights over which the balloon may be safely operated must be established. (b) Maximum weight. The maximum weight...

  4. 14 CFR 31.14 - Weight limits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.14 Weight limits. (a) The range of weights over which the balloon may be safely operated must be established. (b) Maximum weight. The maximum weight...

  5. 14 CFR 31.14 - Weight limits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.14 Weight limits. (a) The range of weights over which the balloon may be safely operated must be established. (b) Maximum weight. The maximum weight...

  6. Short-Term Influence of Revised Provincial Accreditation Standards on Physical Activity, Sedentary Behavior, and Weight Status in Alberta, Canada Child Care Centers

    ERIC Educational Resources Information Center

    Carson, Valerie; Clark, Dawne; Ogden, Nancy; Harber, Vicki; Kuzik, Nicholas

    2015-01-01

    In December, 2013, revised Alberta child care accreditation standards were released by the Alberta Government in Canada that included a new standard for physical activity and sedentary behavior in accredited child care settings. The main purpose of this study was to examine the effectiveness of the new accreditation standard in increasing physical…

  7. Weight Management

    MedlinePlus

    ... Weight share What It Takes to Lose Weight: Calorie Basics When you’re trying to lose weight... ... wcdapps.hhs.gov/Badges/Handlers/Badge.ashx?js=0&widgetname=betobaccofreew200short</NOFRAMES& ...

  8. Definition of the low molecular weight glutenin subunit gene family members in a set of standard bread wheat (Triticum aestivum L.) varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low-molecular-weight glutenin subunits (LMW-GS) are a class of seed storage proteins that play a major role in the determination of the viscoelastic properties of wheat dough. Most of the LMW-GSs are encoded by a multi-gene family located on the short arms of the homoeologous group 1 chromosomes, at...

  9. [WHO child growth standards for children 0-5 years. Percentile charts of length/height, weight, body mass index and head circumference].

    PubMed

    Woynarowska, Barbara; Palczewska, Iwona; Oblacińska, Anna

    2012-01-01

    The aim of this paper was to present the growth standards for children aged 0-5 years - which is a new tool for the assessment of health, growth and nutritional status recommended by WHO for use all over the world. These standards were elaborated in 2006 on the basis of the results of the WHO Multicentre Growth Reference Study (a longitudinal and cross-sectional survey) carried out between 1997-2003 in Brazil, Ghana, India, Norway, Oman and the USA. An innovative approach to developing growth reference was applied. Healthy children living under conditions allowing them to achieve their full genetic potential were the sample of children under study. The results showed that the growth pattern of children in their early childhood in different countries, ethnic groups and of different socioeconomic status was the same when their health and care needs were met. The new standards indicate how children should grow in all countries, rather than merely describing how they grew at a particular place and time. The WHO Child Growth Standards for Children 0-5 years were adapted and used in over 100 countries. Activities designed to adapt WHO standards in Poland were undertaken in 2009. The comparison between the growth reference for Warsaw children and WHO standards showed no differences, or very small ones. Following discussion with the participation of many experts, in 2011 recommendations concerning the implementation of these standards were signed by the Committee of Human Development and the Committee of Anthropology of the Polish Academy of Science, the Main Board of the Polish Anthropological Society, the Institute of Mother and Child, and the Institute of Food and Nutrition. The percentile charts were adapted to the set of percentiles hitherto used in Poland.

  10. Healthy Weight

    MedlinePlus

    ... Activity Overweight & Obesity Healthy Weight Breastfeeding Micronutrient Malnutrition State and Local ... it comes to weight loss, there's no lack of fad diets promising fast results. But such diets limit your nutritional intake, can be unhealthy, and tend to fail ...

  11. Weight Management

    MedlinePlus

    ... Together Understanding Adult Overweight & Obesity About Food Portions Bariatric Surgery for Severe Obesity More Weight Management Topics Healthy ... Sleep Apnea Weight Management Topics About Food Portions Bariatric Surgery for Severe Obesity Being Healthy is a Big ...

  12. Rice by Weight, Other Produce by Bulk, and Snared Iguanas at So Much Per One. A Talk on Measurement Standards and on Metric Conversion.

    ERIC Educational Resources Information Center

    Allen, Harold Don

    This script for a short radio broadcast on measurement standards and metric conversion begins by tracing the rise of the metric system in the international marketplace. Metric units are identified and briefly explained. Arguments for conversion to metric measures are presented. The history of the development and acceptance of the metric system is…

  13. Static polarizability measurements and inertial sensing with nanograting atom interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell D.

    I used a Mach-Zehnder atom interferometer to measure the static electric-dipole polarizabilities of K, Rb, and Cs atoms with 0.11% uncertainty. Static polarizability measurements serve as benchmark tests for ab initio atomic structure calculations. Calculating atomic properties such as polarizabilities, van der Waals coefficients, state lifetimes, or oscillator strengths involves accurately calculating the valence electrons' electric-dipole transition matrix elements. Additionally, testing Cs atomic structure calculations helps interpret the results of parity non-conservation experiments, which in turn places constraints on beyond-the-standard-model physics. I discuss improvements to our experiment that allowed us to measure static polarizabilities with 0.11% uncertainty, and we present our results in the context of recent ab initio and semi-empirical static polarizabilities and recent, high-precision measurements of excited state lifetimes and van der Waals C6 coefficients. I also used our interferometer to develop a new technique for inertial sensing. High precision, portable, atom-interferometer gyroscopes and accelerometers are desirable for self-contained inertial navigation and in the future may be used for tests of General Relativity and searches for gravitational waves using satellite-mounted inertial sensors. Satellite-mounted atom interferometers are challenging to build because of size, weight, power, and reliability constraints. Atom interferometers that use nanogratings to diffract atoms are attractive for satellite-mounted inertial sensing applications because nanogratings weigh approximately nothing and require no power. We developed a new in situ measurement technique using our nanograting atom interferometer, and we used it to measure inertial forces for the benefit of our static polarizability measurements. I also review how to calculate the sensitivity of a nanograting atom interferometer, and I employed these calculations in order to design a

  14. Weighted Automata and Weighted Logics

    NASA Astrophysics Data System (ADS)

    Droste, Manfred; Gastin, Paul

    In automata theory, a fundamental result of Büchi and Elgot states that the recognizable languages are precisely the ones definable by sentences of monadic second order logic. We will present a generalization of this result to the context of weighted automata. We develop syntax and semantics of a quantitative logic; like the behaviors of weighted automata, the semantics of sentences of our logic are formal power series describing ‘how often’ the sentence is true for a given word. Our main result shows that if the weights are taken in an arbitrary semiring, then the behaviors of weighted automata are precisely the series definable by sentences of our quantitative logic. We achieve a similar characterization for weighted Büchi automata acting on infinite words, if the underlying semiring satisfies suitable completeness assumptions. Moreover, if the semiring is additively locally finite or locally finite, then natural extensions of our weighted logic still have the same expressive power as weighted automata.

  15. Weighting Regressions by Propensity Scores

    ERIC Educational Resources Information Center

    Freedman, David A.; Berk, Richard A.

    2008-01-01

    Regressions can be weighted by propensity scores in order to reduce bias. However, weighting is likely to increase random error in the estimates, and to bias the estimated standard errors downward, even when selection mechanisms are well understood. Moreover, in some cases, weighting will increase the bias in estimated causal parameters. If…

  16. 14 CFR 29.25 - Weight limits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 29.25 Section 29.25... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight General § 29.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part...

  17. 14 CFR 29.25 - Weight limits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Weight limits. 29.25 Section 29.25... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight General § 29.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part...

  18. 14 CFR 29.25 - Weight limits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Weight limits. 29.25 Section 29.25... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight General § 29.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part...

  19. 14 CFR 27.25 - Weight limits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Weight limits. 27.25 Section 27.25... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight General § 27.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part is...

  20. 14 CFR 27.25 - Weight limits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Weight limits. 27.25 Section 27.25... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight General § 27.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part is...

  1. 14 CFR 27.25 - Weight limits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 27.25 Section 27.25... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight General § 27.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part is...

  2. 14 CFR 27.25 - Weight limits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Weight limits. 27.25 Section 27.25... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight General § 27.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part is...

  3. 14 CFR 29.25 - Weight limits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Weight limits. 29.25 Section 29.25... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight General § 29.25 Weight limits. (a) Maximum weight. The maximum weight (the highest weight at which compliance with each applicable requirement of this part...

  4. Establishment of 6- to 7-MeV high-energy gamma-ray calibration fields produced using the 4-MV Van de Graaff accelerator at the Facility of Radiation Standards, Japan Atomic Energy Agency.

    PubMed

    Kowatari, Munehiko; Tanimura, Yoshihiko

    2016-03-01

    A 6- to 7-MeV high-energy gamma-ray field, produced by the nuclear reaction of (19)F(p, αγ)(16)O, has been established at the Facility of Radiation Standards (FRS) in Japan Atomic Energy Agency for calibration purposes. Basic dosimetric quantities (i.e. averaged gamma-ray energy, air-kerma-to-dose equivalent conversion coefficients and air kerma rates at the point of test) have been precisely determined through a series of measurements using the NaI(Tl) spectrometer and an ionisation chamber coupled with an appropriate build-up material. The measurements obtained comply with values recommended by the International Organization for Standardization for an 'R-F field'. The neutron contamination component for the field has also been measured by means of a conventional neutron dose equivalent meter (the so-called neutron rem-counter) and determined to be ∼ 0.5 % of the total dose equivalent.

  5. Atomic polarizabilities

    SciTech Connect

    Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  6. Implications of Research on Children's Learning for Standards and Assessment: A Proposed Learning Progression for Matter and the Atomic-Molecular Theory

    ERIC Educational Resources Information Center

    Smith, Carol L.; Wiser, Marianne; Anderson, Charles W.; Krajcik, Joseph

    2006-01-01

    The purpose of this article is to suggest ways of using research on children's reasoning and learning to elaborate on existing national standards and to improve large-scale and classroom assessments. The authors suggest that "learning progressions"--descriptions of successively more sophisticated ways of reasoning within a content domain based on…

  7. Weight simulator

    NASA Technical Reports Server (NTRS)

    Howard, W. H.; Young, D. R.

    1972-01-01

    Device applies compressive force to bone to minimize loss of bone calcium during weightlessness or bedrest. Force is applied through weights, or hydraulic, pneumatic or electrically actuated devices. Device is lightweight and easy to maintain and operate.

  8. Evaluation of Bi as internal standard to minimize matrix effects on the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru permanent modifier with co-injection of Pd/Mg(NO 3) 2

    NASA Astrophysics Data System (ADS)

    de Oliveira, Silvana Ruella; Neto, José Anchieta Gomes

    2007-09-01

    Bismuth was evaluated as an internal standard for the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru as a permanent modifier with co-injection of Pd/Mg(NO 3) 2. The correlation coefficient of the graph plotted from the normalized absorbance signals of Bi versus Pb was r = 0.989. Matrix effects were evaluated by analyzing the slope ratios between the analytical curve obtained from reference solutions prepared in 0.2% (v/v) HNO 3 and analytical curves obtained from Pb additions in red and white wine vinegar samples. The calculated ratios were around 1.04 and 1.02 for analytical curves established applying an internal standard and 1.3 and 1.5 for analytical curves without. Analytical curves in the 2.5-15 μg L - 1 Pb concentration interval were established using the ratio Pb absorbance to Bi absorbance versus analyte concentration, and typical linear correlations of r = 0.999 were obtained. The proposed method was applied for direct determination of Pb in 18 commercial vinegar samples and the Pb concentration varied from 2.6 to 31 μg L - 1 . Results were in agreement at a 95% confidence level (paired t-test) with those obtained for digested samples. Recoveries of Pb added to vinegars varied from 96 to 108% with and from 72 to 86% without an internal standard. Two water standard reference materials diluted in vinegar sample were also analyzed and results were in agreement with certified values at a 95% confidence level. The characteristic mass was 40 pg Pb and the useful lifetime of the tube was around 1600 firings. The limit of detection was 0.3 μg L - 1 and the relative standard deviation was ≤ 3.8% and ≤ 8.3% ( n = 12) for a sample containing 10 μg L - 1 Pb with and without internal standard, respectively.

  9. Serial weighting of micro-objects with resonant microchanneled cantilevers

    NASA Astrophysics Data System (ADS)

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-01

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples.

  10. Atomic hydrogen rocket engine

    NASA Technical Reports Server (NTRS)

    Etters, R. D.; Flurchick, K.

    1981-01-01

    A rocket using atomic hydrogen propellant is discussed. An essential feature of the proposed engine is that the atomic hydrogen fuel is used as it is produced, thus eliminating the necessity of storage. The atomic hydrogen flows into a combustion chamber and recombines, producing high velocity molecular hydrogen which flows out an exhaust port. Standard thermodynamics, kinetic theory and wall recombination cross-sections are used to predict a thrust of approximately 1.4 N for a RF hydrogen flow rate of 4 x 10 to the 22nd/sec. Specific impulses are nominally from 1000 to 2000 sec. It is predicted that thrusts on the order of one Newton and specific impulses of up to 2200 sec are attainable with nominal RF discharge fluxes on the order of 10 to the 22nd atoms/sec; further refinements will probably not alter these predictions by more than a factor of two.

  11. 40 CFR 63.11438 - What are the standards for new and existing sources?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Hazardous Air Pollutants for Clay Ceramics... your facility. (c) For each atomized glaze spray booth located at a clay ceramics manufacturing... in § 63.11440. (2) Alternatively, use wet glazes containing less than 0.1 (weight) percent...

  12. 40 CFR 63.11438 - What are the standards for new and existing sources?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Hazardous Air Pollutants for Clay Ceramics... your facility. (c) For each atomized glaze spray booth located at a clay ceramics manufacturing... in § 63.11440. (2) Alternatively, use wet glazes containing less than 0.1 (weight) percent...

  13. Interplay between surface properties of standard, vitamin E blended and oxidised ultra high molecular weight polyethylene used in total joint replacement and adhesion of Staphylococcus aureus and Escherichia coli.

    PubMed

    Banche, G; Allizond, V; Bracco, P; Bistolfi, A; Boffano, M; Cimino, A; Brach del Prever, E M; Cuffini, A M

    2014-04-01

    We have assessed the different adhesive properties of some of the most common bacteria associated with periprosthetic joint infection on various types of ultra high molecular Weight Polyethylene (UHMWPE). Quantitative in vitro analysis of the adhesion of biofilm producing strains of Staphylococcus aureus and Escherichia coli to physically and chemically characterised standard UHMWPE (PE), vitamin E blended UHMWPE (VE-PE) and oxidised UHMWPE (OX-PE) was performed using a sonication protocol. A significant decreased bacterial adhesion was registered for both strains on VE-PE, in comparison with that observed on PE, within 48 hours of observation (S. aureus p = 0.024 and E. coli p = 0.008). Since Vitamin E reduces bacterial adhesive ability, VE-stabilised UHMWPE could be valuable in joint replacement by presenting excellent mechanical properties, while reducing bacterial adhesiveness.

  14. Determination of selenium in plasma, urine and tissues, of standard diet-fed rats and dogs by ETA-atomic absorption spectroscopy with Zeeman background correction.

    PubMed

    Giachetti, C; Assandri, A; Testa, B; Lombardini, E; Zanolo, G

    1996-09-01

    The method described was developed to be applied in determination of selenium in biological matrices (plasma, urine and tissues) using ETA-AAS with Zeeman background correction. These matrices were obtained from non-fasting S.D. rats and Beagle dogs of both sexes in order to acquire data on the endogenous levels of selenium in these laboratory animals when fed with standard diets. For tissue digestion, a simple procedure using the strong organic base, Soluene 350, was adopted. Precision assays were carried out monitoring Se(IV) levels in spiked matrices (range from 25 to 200 ng) and obtaining relative standard deviations (RSD%) in the range from 3.2% to 14.5% (intra-day) and from 7.6% to 15.9% (inter-day). Accuracy assays gave relative errors (RE%) in the range from -6.5 to 4.2% (intra-day) and from -5.5% to 5.7% (inter-day). The validity of the method was checked on reference material (NBS SRM 1577 bovine liver) and the values obtained correlated with the certified ones. The detection limit assumed was 0.9 ng/ml, whereas the quantitation limit of selenium in matrices ranged from 2 to 5 ng/ml (or g), depending on the kind of sample.

  15. Cobalt internal standard for Ni to assist the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis.

    PubMed

    de Babos, Diego Victor; Bechlin, Marcos André; Barros, Ariane Isis; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta; de Oliveira, Silvana Ruella

    2016-05-15

    A new method is proposed for the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS), employing direct solid sample analysis (DSS) and internal standardization (IS). Cobalt was used as internal standard to minimize matrix effects during Ni determinations, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9937. The performance of the method was checked by analysis of six plant certified reference materials, and the results for Mo and Ni were in agreement with the certified values (95% confidence level, t-test). Analysis was made of different types of plant materials used as renewable sources of energy, including sugarcane leaves, banana tree fiber, soybean straw, coffee pods, orange bagasse, peanut hulls, and sugarcane bagasse. The concentrations found for Mo and Ni ranged from 0.08 to 0.63 ng mg(-1) and from 0.41 to 6.92 ng mg(-1), respectively. Precision (RSD) varied from 2.1% to 11% for Mo and from 3.7% to 10% for Ni. Limits of quantification of 0.055 and 0.074 ng were obtained for Mo and Ni, respectively.

  16. Atomic supersymmetry

    NASA Technical Reports Server (NTRS)

    Kostelecky, V. Alan

    1993-01-01

    Atomic supersymmetry is a quantum-mechanical supersymmetry connecting the properties of different atoms and ions. A short description of some established results in the subject are provided and a few recent developments are discussed including the extension to parabolic coordinates and the calculation of Stark maps using supersymmetry-based models.

  17. Keynote address: The past, present, and future of atomic time

    NASA Technical Reports Server (NTRS)

    Ramsey, Norman F.

    1990-01-01

    The early history of atomic time and frequency standards is reviewed. The most accurate and stable present standards are described. Prospective future improvements are discussed, particularly those with laser cooling and with trapped ions and atoms.

  18. 14 CFR 31.16 - Empty weight.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.16 Empty weight. The empty weight must be determined by weighing the balloon with installed equipment but without lifting gas or heater fuel....

  19. 14 CFR 31.16 - Empty weight.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.16 Empty weight. The empty weight must be determined by weighing the balloon with installed equipment but without lifting gas or heater fuel....

  20. 14 CFR 31.16 - Empty weight.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.16 Empty weight. The empty weight must be determined by weighing the balloon with installed equipment but without lifting gas or heater fuel....

  1. 14 CFR 31.16 - Empty weight.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.16 Empty weight. The empty weight must be determined by weighing the balloon with installed equipment but without lifting gas or heater fuel....

  2. 14 CFR 31.16 - Empty weight.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.16 Empty weight. The empty weight must be determined by weighing the balloon with installed equipment but without lifting gas or heater fuel....

  3. Acting Atoms.

    ERIC Educational Resources Information Center

    Farin, Susan Archie

    1997-01-01

    Describes a fun game in which students act as electrons, protons, and neutrons. This activity is designed to help students develop a concrete understanding of the abstract concept of atomic structure. (DKM)

  4. Kinetic Atom.

    ERIC Educational Resources Information Center

    Wilson, David B.

    1981-01-01

    Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

  5. Hirshfeld atom refinement.

    PubMed

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  6. Scuba Weights

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Attitude Adjuster is a system for weight repositioning corresponding to a SCUBA diver's changing positions. Compact tubes on the diver's air tank permit controlled movement of lead balls within the Adjuster, automatically repositioning when the diver changes position. Manufactured by Think Tank Technologies, the system is light and small, reducing drag and energy requirements and contributing to lower air consumption. The Mid-Continent Technology Transfer Center helped the company with both technical and business information and arranged for the testing at Marshall Space Flight Center's Weightlessness Environmental Training Facility for astronauts.

  7. Primary Atomic Clock Reference System

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An artist's concept of the Primary Atomic Clock Reference System (PARCS) plarned to fly on the International Space Station (ISS). PARCS will make even more accurate atomic time available to everyone, from physicists testing Einstein's Theory of Relativity, to hikers using the Global Positioning System to find their way. In ground-based atomic clocks, lasers are used to cool and nearly stop atoms of cesium whose vibrations are used as the time base. The microgravity of space will allow the atoms to be suspended in the clock rather than circulated in an atomic fountain, as required on Earth. PARCS is being developed by the Jet Propulsion Laboratory with principal investigators at the National Institutes of Standards and Technology and the University of Colorado, Boulder. See also No. 0103191

  8. Primary Atomic Clock Reference System

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An artist's concept of the Primary Atomic Clock Reference System (PARCS) plarned to fly on the International Space Station (ISS). PARCS will make even more accurate atomic time available to everyone, from physicists testing Einstein's Theory of Relativity, to hikers using the Global Positioning System to find their way. In ground-based atomic clocks, lasers are used to cool and nearly stop atoms of cesium whose vibrations are used as the time base. The microgravity of space will allow the atoms to be suspended in the clock rather than circulated in an atomic fountain, as required on Earth. PARCS is being developed by the Jet Propulsion Laboratory with principal investigators at the National Institutes of Standards and Technology and the University of Colorado, Boulder. See also No. 0100120.

  9. Generation of Well-Relaxed All-Atom Models of Large Molecular Weight Polymer Melts: A Hybrid Particle-Continuum Approach Based on Particle-Field Molecular Dynamics Simulations.

    PubMed

    De Nicola, Antonio; Kawakatsu, Toshihiro; Milano, Giuseppe

    2014-12-09

    A procedure based on Molecular Dynamics (MD) simulations employing soft potentials derived from self-consistent field (SCF) theory (named MD-SCF) able to generate well-relaxed all-atom structures of polymer melts is proposed. All-atom structures having structural correlations indistinguishable from ones obtained by long MD relaxations have been obtained for poly(methyl methacrylate) (PMMA) and poly(ethylene oxide) (PEO) melts. The proposed procedure leads to computational costs mainly related on system size rather than to the chain length. Several advantages of the proposed procedure over current coarse-graining/reverse mapping strategies are apparent. No parametrization is needed to generate relaxed structures of different polymers at different scales or resolutions. There is no need for special algorithms or back-mapping schemes to change the resolution of the models. This characteristic makes the procedure general and its extension to other polymer architectures straightforward. A similar procedure can be easily extended to the generation of all-atom structures of block copolymer melts and polymer nanocomposites.

  10. Atomic research

    NASA Technical Reports Server (NTRS)

    Hadaway, James B.; Connatser, Robert; Cothren, Bobby; Johnson, R. B.

    1993-01-01

    Work performed by the University of Alabama in Huntsville's (UAH) Center for Applied Optics (CAO) entitled Atomic Research is documented. Atomic oxygen (AO) effects on materials have long been a critical concern in designing spacecraft to withstand exposure to the Low Earth Orbit (LEO) environment. The objective of this research effort was to provide technical expertise in the design of instrumentation and experimental techniques for analyzing materials exposed to atomic oxygen in accelerated testing at NASA/MSFC. Such testing was required to answer fundamental questions concerning Space Station Freedom (SSF) candidate materials and materials exposed to atomic oxygen aboard the Long-Duration Exposure Facility (LDEF). The primary UAH task was to provide technical design, review, and analysis to MSFC in the development of a state-of-the-art 5eV atomic oxygen beam facility required to simulate the RAM-induced low earth orbit (LEO) AO environment. This development was to be accomplished primarily at NASA/MSFC. In support of this task, contamination effects and ultraviolet (UV) simulation testing was also to be carried out using NASA/MSFC facilities. Any materials analysis of LDEF samples was to be accomplished at UAH.

  11. A Simple Relativistic Bohr Atom

    ERIC Educational Resources Information Center

    Terzis, Andreas F.

    2008-01-01

    A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…

  12. Atom Interferometry

    ScienceCinema

    Mark Kasevich

    2016-07-12

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  13. Atom Interferometry

    SciTech Connect

    Kasevich, Mark

    2008-05-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  14. Atom Interferometry

    SciTech Connect

    Mark Kasevich

    2008-05-07

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  15. RADIOACTIVE CHEMICAL ELEMENTS IN THE ATOMIC TABLE.

    SciTech Connect

    HOLDEN, N.E.

    2005-08-13

    In the 1949 Report of the Atomic Weights Commission, a series of new elements were added to the Atomic Weights Table. Since these elements had been produced in the laboratory and were not discovered in nature, the atomic weight value of these artificial products would depend upon the production method. Since atomic weight is a property of an element as it occurs in nature, it would be incorrect to assign an atomic weight value to that element. As a result of that discussion, the Commission decided to provide only the mass number of the most stable (longest-lived) known isotope as the number to be associated with these entries in the Atomic Weights Table. As a function of time, the mass number associated with various elements has changed as longer-lived isotopes of a particular elements has been found in nature, or as improved half-life values of an element's isotopes might cause a shift in the longest-lived isotope from one mass number to another. In the 1957 Report of the Atomic Weights Commission, it was decided to discontinue the listing of the mass number in the Atomic Weights Table on the grounds that the kind of information supplied by the mass number is inconsistent with the primary purpose of the Table, i.e., to provide accurate values of ''these constants'' for use in chemical calculations. In addition to the Table of Atomic Weights, the Commission included an auxiliary Table of Radioactive Elements for the first time, where the entry would be the isotope of that element which was most stable, i.e., it had the longest known half-life. In their 1973 report, the Commission noted that the users of the Atomic Weights Table were dissatisfied with the omission of values in the Table for some elements and it was decided to reintroduce the mass number for elements. In their 1983 report, the Commission decided that radioactive elements were considered to lack a characteristic terrestrial isotopic composition, from which an atomic weight value could be calculated to

  16. Your Child's Weight

    MedlinePlus

    ... Parents MORE ON THIS TOPIC Weight Loss Surgery (Bariatric Surgery) Overweight and Obesity Weight and Diabetes Growth Charts ... Losing Weight: Brandon's Story (Video) Managing Your Weight Weight Loss Surgery When Being Overweight Is a Health Problem Who ...

  17. Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

    PubMed Central

    2016-01-01

    Summary Significant progress has been accomplished in the development of experimental contact-mode and dynamic-mode atomic force microscopy (AFM) methods designed to measure surface material properties. However, current methods are based on one-dimensional (1D) descriptions of the tip–sample interaction forces, thus neglecting the intricacies involved in the material behavior of complex samples (such as soft viscoelastic materials) as well as the differences in material response between the surface and the bulk. In order to begin to address this gap, a computational study is presented where the sample is simulated using an enhanced version of a recently introduced model that treats the surface as a collection of standard-linear-solid viscoelastic elements. The enhanced model introduces in-plane surface elastic forces that can be approximately related to a two-dimensional (2D) Young’s modulus. Relevant cases are discussed for single- and multifrequency intermittent-contact AFM imaging, with focus on the calculated surface indentation profiles and tip–sample interaction force curves, as well as their implications with regards to experimental interpretation. A variety of phenomena are examined in detail, which highlight the need for further development of more physically accurate sample models that are specifically designed for AFM simulation. A multifrequency AFM simulation tool based on the above sample model is provided as supporting information. PMID:27335746

  18. Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: Coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

    SciTech Connect

    Solares, Santiago D.

    2016-04-15

    Significant progress has been accomplished in the development of experimental contact-mode and dynamic-mode atomic force microscopy (AFM) methods designed to measure surface material properties. However, current methods are based on one-dimensional (1D) descriptions of the tip-sample interaction forces, thus neglecting the intricacies involved in the material behavior of complex samples (such as soft viscoelastic materials) as well as the differences in material response between the surface and the bulk. In order to begin to address this gap, a computational study is presented where the sample is simulated using an enhanced version of a recently introduced model that treats the surface as a collection of standard-linear-solid viscoelastic elements. The enhanced model introduces in-plane surface elastic forces that can be approximately related to a two-dimensional (2D) Young's modulus. Relevant cases are discussed for single-and multifrequency intermittent-contact AFM imaging, with focus on the calculated surface indentation profiles and tip-sample interaction force curves, as well as their implications with regards to experimental interpretation. A variety of phenomena are examined in detail, which highlight the need for further development of more physically accurate sample models that are specifically designed for AFM simulation. As a result, a multifrequency AFM simulation tool based on the above sample model is provided as supporting information.

  19. Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: Coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

    DOE PAGES

    Solares, Santiago D.

    2016-04-15

    Significant progress has been accomplished in the development of experimental contact-mode and dynamic-mode atomic force microscopy (AFM) methods designed to measure surface material properties. However, current methods are based on one-dimensional (1D) descriptions of the tip-sample interaction forces, thus neglecting the intricacies involved in the material behavior of complex samples (such as soft viscoelastic materials) as well as the differences in material response between the surface and the bulk. In order to begin to address this gap, a computational study is presented where the sample is simulated using an enhanced version of a recently introduced model that treats the surfacemore » as a collection of standard-linear-solid viscoelastic elements. The enhanced model introduces in-plane surface elastic forces that can be approximately related to a two-dimensional (2D) Young's modulus. Relevant cases are discussed for single-and multifrequency intermittent-contact AFM imaging, with focus on the calculated surface indentation profiles and tip-sample interaction force curves, as well as their implications with regards to experimental interpretation. A variety of phenomena are examined in detail, which highlight the need for further development of more physically accurate sample models that are specifically designed for AFM simulation. As a result, a multifrequency AFM simulation tool based on the above sample model is provided as supporting information.« less

  20. Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions.

    PubMed

    Solares, Santiago D

    2016-01-01

    Significant progress has been accomplished in the development of experimental contact-mode and dynamic-mode atomic force microscopy (AFM) methods designed to measure surface material properties. However, current methods are based on one-dimensional (1D) descriptions of the tip-sample interaction forces, thus neglecting the intricacies involved in the material behavior of complex samples (such as soft viscoelastic materials) as well as the differences in material response between the surface and the bulk. In order to begin to address this gap, a computational study is presented where the sample is simulated using an enhanced version of a recently introduced model that treats the surface as a collection of standard-linear-solid viscoelastic elements. The enhanced model introduces in-plane surface elastic forces that can be approximately related to a two-dimensional (2D) Young's modulus. Relevant cases are discussed for single- and multifrequency intermittent-contact AFM imaging, with focus on the calculated surface indentation profiles and tip-sample interaction force curves, as well as their implications with regards to experimental interpretation. A variety of phenomena are examined in detail, which highlight the need for further development of more physically accurate sample models that are specifically designed for AFM simulation. A multifrequency AFM simulation tool based on the above sample model is provided as supporting information.

  1. Optical frequency standards for time and length applications

    NASA Astrophysics Data System (ADS)

    Hong, Feng-Lei

    2017-01-01

    The last decade has witnessed tremendous progress in research on optical frequency metrology. Optical frequency standards using optical lattice and single-ion trap technologies have reached levels of stability and accuracy that surpass the performance of the best Cs fountain atomic clocks by orders of magnitude. Optical frequency standards are also used for various applications including length metrology. Optical frequency measurement and links using optical frequency combs and optical fibres play important roles in the development of optical frequency standards. This article introduces optical frequency standards recommended by the International Committee for Weights and Measures (CIPM) along with updates provided by recent research results. Frequency ratio measurements and remote frequency comparisons are addressed in relation to the work whose goal is to redefine the second. Optical frequency standard and optical frequency comb applications are also described.

  2. Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy

    PubMed Central

    Wilson, Walter B.; Alfarhani, Bassam; Moore, Anthony F. T.; Bisson, Cristina; Wise, Stephen A.; Campiglia, Andres D.

    2016-01-01

    This article presents an alternative approach for the analysis of high molecular weight – polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302 Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302 Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2 K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24 μg L−1 (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples. PMID:26653471

  3. Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy.

    PubMed

    Wilson, Walter B; Alfarhani, Bassam; Moore, Anthony F T; Bisson, Cristina; Wise, Stephen A; Campiglia, Andres D

    2016-02-01

    This article presents an alternative approach for the analysis of high molecular weight - polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302 Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302 Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24 µg L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples.

  4. 14 CFR 25.25 - Weight limits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 25.25 Section 25.25 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights....

  5. 14 CFR 31.14 - Weight limits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 31.14 Section 31.14 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.14 Weight limits. (a) The range of weights...

  6. 14 CFR 25.25 - Weight limits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights. Maximum weights corresponding to the airplane operating conditions (such as ramp, ground or water taxi,...

  7. 14 CFR 25.25 - Weight limits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights. Maximum weights corresponding to the airplane operating conditions (such as ramp, ground or water taxi,...

  8. 14 CFR 25.25 - Weight limits.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights. Maximum weights corresponding to the airplane operating conditions (such as ramp, ground or water taxi,...

  9. 14 CFR 25.25 - Weight limits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights. Maximum weights corresponding to the airplane operating conditions (such as ramp, ground or water taxi,...

  10. Atomic arias

    NASA Astrophysics Data System (ADS)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  11. Atomic rivals

    SciTech Connect

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  12. Atomic physics

    SciTech Connect

    Livingston, A.E.; Kukla, K.; Cheng, S.

    1995-08-01

    In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.

  13. Atomic Databases

    NASA Astrophysics Data System (ADS)

    Mendoza, Claudio

    2000-10-01

    Atomic and molecular data are required in a variety of fields ranging from the traditional astronomy, atmospherics and fusion research to fast growing technologies such as lasers, lighting, low-temperature plasmas, plasma assisted etching and radiotherapy. In this context, there are some research groups, both theoretical and experimental, scattered round the world that attend to most of this data demand, but the implementation of atomic databases has grown independently out of sheer necessity. In some cases the latter has been associated with the data production process or with data centers involved in data collection and evaluation; but sometimes it has been the result of individual initiatives that have been quite successful. In any case, the development and maintenance of atomic databases call for a number of skills and an entrepreneurial spirit that are not usually associated with most physics researchers. In the present report we present some of the highlights in this area in the past five years and discuss what we think are some of the main issues that have to be addressed.

  14. Optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

    2013-12-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  15. Effects of hydrogen atom spin exchange collisions on atomic hydrogen maser oscillation frequency

    NASA Technical Reports Server (NTRS)

    Crampton, S. B.

    1979-01-01

    Frequency shifts due to collisions between hydrogen atoms in an atomic hydrogen maser frequency standard are studied. Investigations of frequency shifts proportional to the spin exchange frequency shift cross section and those proportional to the duration of exchange collisions are discussed. The feasibility of operating a hydrogen frequency standard at liquid helium temperatures is examined.

  16. Atomic resolution crystal structure of VcLMWPTP-1 from Vibrio cholerae O395: Insights into a novel mode of dimerization in the low molecular weight protein tyrosine phosphatase family

    SciTech Connect

    Nath, Seema; Banerjee, Ramanuj; Sen, Udayaditya

    2014-07-18

    Highlights: • VcLMWPTP-1 forms dimer in solution. • The dimer is catalytically active unlike other reported dimeric LMWPTPs. • The formation of extended dimeric surface excludes the active site pocket. • The surface bears closer resemblance to eukaryotic LMWPTPs. - Abstract: Low molecular weight protein tyrosine phosphatase (LMWPTP) is a group of phosphotyrosine phosphatase ubiquitously found in a wide range of organisms ranging from bacteria to mammals. Dimerization in the LMWPTP family has been reported earlier which follows a common mechanism involving active site residues leading to an enzymatically inactive species. Here we report a novel form of dimerization in a LMWPTP from Vibrio cholera 0395 (VcLMWPTP-1). Studies in solution reveal the existence of the dimer in solution while kinetic study depicts the active form of the enzyme. This indicates that the mode of dimerization in VcLMWPTP-1 is different from others where active site residues are not involved in the process. A high resolution (1.45 Å) crystal structure of VcLMWPTP-1 confirms a different mode of dimerization where the active site is catalytically accessible as evident by a tightly bound substrate mimicking ligand, MOPS at the active site pocket. Although being a member of a prokaryotic protein family, VcLMWPTP-1 structure resembles very closely to LMWPTP from a eukaryote, Entamoeba histolytica. It also delineates the diverse surface properties around the active site of the enzyme.

  17. Atom Skimmers and Atom Lasers Utilizing Them

    NASA Technical Reports Server (NTRS)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  18. High Atom Number in Microsized Atom Traps

    DTIC Science & Technology

    2015-12-14

    cooling of some atoms in atomic beam. We have reconfigured the apparatus for applying bichromatic forces transverse to the atomic beam, as it will be...apparatus for applying bichromatic forces transverse to the atomic beam, as it will be easier to extend this to two dimensions. Research to develop

  19. Atomic magnetometer

    DOEpatents

    Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  20. Study on the Algorithm of Local Atomic Time

    NASA Astrophysics Data System (ADS)

    Li, B.; Qu, L. L.; Gao, Y. P.; Hu, Y. H.

    2010-10-01

    It is always an endless target for all time and frequency laboratories to develop, own and keep a stable, accurate and reliable time scale. As a comparatively mature algorithm, ALGOS, which has been concerned about the long-term stability of the time scale, is widely used by the majority of time laboratories. For ALGOS, the weights are assumed on the basis of the frequencies of 12 months and the present month interval is included in the computation. This procedure uses clock measurements covering 12 months, so annual frequency variations and long-term drifts can lead to de-weight. This helps to decrease the seasonal variation of the time scale and improve its long-term stability. However, the local atomic time scale is primarily concerned with long-term stability not more than 60 days. So when the local time scale is computed with ALGOS in time laboratories, it is necessary to modify ALGOS correspondingly according to the performances of contributing clocks, the requirement of stability for local time scale and so on. There are 22 high performance atomic clocks at National Time Service Center, Chinese Academy of Sciences (NTSC). They include 18 cesium standards and 4 hydrogen masers. Because hydrogen masers behave poor, we only regard an ensemble of 18 cesium clocks in our improved algorithm. The performances of these clocks are very similar, and the number is less than 20. By analyzing and studying the noise models of atomic clocks, this paper presents a complete improved algorithm of TA(NTSC). This improved TA(NTSC) algorithm includes three aspects: the selection of the maximum weight, the selection of clocks taking part in TA(NTSC) computation and the estimation of the weights of contributing clocks. We validate the new algorithm with the annually atomic clock comparative data of NTSC taking part in TAI computation in 2008. The results show that the long-term and short-term stabilities of TA(NTSC) are all improved. This conclusion is based on the clock

  1. Atom and Bond Fukui Functions and Matrices: A Hirshfeld-I Atoms-in-Molecule Approach.

    PubMed

    Oña, Ofelia B; De Clercq, Olivier; Alcoba, Diego R; Torre, Alicia; Lain, Luis; Van Neck, Dimitri; Bultinck, Patrick

    2016-09-19

    The Fukui function is often used in its atom-condensed form by isolating it from the molecular Fukui function using a chosen weight function for the atom in the molecule. Recently, Fukui functions and matrices for both atoms and bonds separately were introduced for semiempirical and ab initio levels of theory using Hückel and Mulliken atoms-in-molecule models. In this work, a double partitioning method of the Fukui matrix is proposed within the Hirshfeld-I atoms-in-molecule framework. Diagonalizing the resulting atomic and bond matrices gives eigenvalues and eigenvectors (Fukui orbitals) describing the reactivity of atoms and bonds. The Fukui function is the diagonal element of the Fukui matrix and may be resolved in atom and bond contributions. The extra information contained in the atom and bond resolution of the Fukui matrices and functions is highlighted. The effect of the choice of weight function arising from the Hirshfeld-I approach to obtain atom- and bond-condensed Fukui functions is studied. A comparison of the results with those generated by using the Mulliken atoms-in-molecule approach shows low correlation between the two partitioning schemes.

  2. Effect of clothing weight on body weight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: In clinical settings, it is common to measure weight of clothed patients and estimate a correction for the weight of clothing, but we can find no papers in the medical literature regarding the variability in clothing weight with weather, season, and gender. Methods: Fifty adults (35 wom...

  3. Two-Photon Spectroscopy in Rb for an Optical Frequency Standard

    NASA Astrophysics Data System (ADS)

    Martin, Kyle; Phelps, Gretchen; Lemke, Nathan; Blakley, Daniel; Erickson, Christopher; Burke, John; Applied Technology Associates Team; Space Dynamics Laboratory Team; Air Force Research Laboratory Team

    2016-05-01

    The Air Force Research Laboratory is pursuing optical atomic clocks for navigation and timing applications. Optical clocks are of particular interest owing to their very high oscillation frequencies. We present an optical rubidium atomic frequency standard (O-RAFS), based upon a two-photon transition at 778 nm, that utilizes readily available commercial off-the-shelf components. Compared to existing GPS clocks, O-RAFS offers reduced short-term instability (7 ×10-13 /√{ τ}), improved manufacturability, and competitive size, weight, and power, making it an attractive candidate for future space operation.

  4. Compact differences of weighted composition operators on the weighted Bergman spaces.

    PubMed

    Wang, Maocai; Yao, Xingxing; Chen, Fen

    2017-01-01

    In this paper, we consider the compact differences of weighted composition operators on the standard weighted Bergman spaces. Some necessary and sufficient conditions for the differences of weighted composition operators to be compact are given, which extends Moorhouse's results in (J. Funct. Anal. 219:70-92, 2005).

  5. Somatotypes of weight lifters.

    PubMed

    Orvanová, E

    1990-01-01

    The present paper reviews published studies on the body shape of weight lifters. The differences between the somatotype ratings of weight lifters studied using the Sheldon and the Heath-Carter methods, and the differences between performance levels and age groups of weight lifters are discussed. The differences in mean somatoplots among the weight lifters studied as a whole group, weight lifters divided into two, three or four groups according to body weight, and weight lifters considered according to the official weight classes, are assessed. Weight lifters in the lighter weight classes are found to be ectomorphic or balanced mesomorphs, while those in the heavier weight classes tend to be endomorphic mesomorphs. Ectomorphy decreases, whereas mesomorphy and endomorphy increase with weight class. When three age groups of weight lifters were compared within each weight class, the same pattern of differences between ages occurs. The younger lifters in each weight class have higher endomorphy and lower mesomorphy than the senior lifters. Ectomorphy is higher in the younger lifters below the weight class of 82.5 kg. Since significant differences in all three somatotype components between 10 weight classes of weight lifters and also within three age groups were noted, it will be necessary in future studies to consider the somatotypes of weight lifters according to the official weight classes.

  6. Informed Test Component Weighting.

    ERIC Educational Resources Information Center

    Rudner, Lawrence M.

    2001-01-01

    Identifies and evaluates alternative methods for weighting tests. Presents formulas for composite reliability and validity as a function of component weights and suggests a rational process that identifies and considers trade-offs in determining weights. Discusses drawbacks to implicit weighting and explicit weighting and the difficulty of…

  7. Standards not that standard.

    PubMed

    Vilanova, Cristina; Tanner, Kristie; Dorado-Morales, Pedro; Villaescusa, Paula; Chugani, Divya; Frías, Alba; Segredo, Ernesto; Molero, Xavier; Fritschi, Marco; Morales, Lucas; Ramón, Daniel; Peña, Carlos; Peretó, Juli; Porcar, Manuel

    2015-01-01

    There is a general assent on the key role of standards in Synthetic Biology. In two consecutive letters to this journal, suggestions on the assembly methods for the Registry of standard biological parts have been described. We fully agree with those authors on the need of a more flexible building strategy and we highlight in the present work two major functional challenges standardization efforts have to deal with: the need of both universal and orthogonal behaviors. We provide experimental data that clearly indicate that such engineering requirements should not be taken for granted in Synthetic Biology.

  8. Weight Loss Surgery

    MedlinePlus

    ... A Week of Healthy Breakfasts Shyness Weight Loss Surgery KidsHealth > For Teens > Weight Loss Surgery A A ... Risks and Side Effects? What Is Weight Loss Surgery? For some people, being overweight is about more ...

  9. Weight Loss Surgery

    MedlinePlus

    ... serious medical problems. Weight loss surgery (also called bariatric surgery) can help very obese people lose weight. But ... Gastric banding is the simplest of the three weight loss surgeries. People who get it might not lose as ...

  10. Frequency Standards and Metrology

    NASA Astrophysics Data System (ADS)

    Maleki, Lute

    2009-04-01

    Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and

  11. 7 CFR 52.3755 - Minimum drained weights.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Canned Ripe Olives 1 Product Description... olives is determined by emptying the contents of the container upon a U.S. Standard No. 8 circular sieve.... The weight of drained olives is the weight of the sieve and product less the weight of the dry...

  12. 7 CFR 52.3755 - Minimum drained weights.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Canned Ripe Olives 1 Product Description... olives is determined by emptying the contents of the container upon a U.S. Standard No. 8 circular sieve.... The weight of drained olives is the weight of the sieve and product less the weight of the dry...

  13. 7 CFR 52.3755 - Minimum drained weights.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Canned Ripe Olives 1 Product Description... olives is determined by emptying the contents of the container upon a U.S. Standard No. 8 circular sieve.... The weight of drained olives is the weight of the sieve and product less the weight of the dry...

  14. Collective State Raman Atomic Clock Using Trapped Atoms

    NASA Astrophysics Data System (ADS)

    Kim, May; Sarkar, Resham; Fang, Renpeng; Tu, Yanfei; Shahriar, Selim

    2014-05-01

    Atomic clock has set the standard as the most accurate clock in the world. So far, the approach to making the atomic clock has been limited to utilizing individual atomic states. We have developed the framework for a collective atomic clock-in an ensemble of cold atoms using the method of separated Raman-Ramsey fields-by conceiving a method to detect the collective states, analyzing the signal to noise ratio, and finding the bounds for efficiency of our detector. The width of the Raman-Ramsey fringe in such a clock is narrower than that of a conventional Raman-Ramsey fringe by a factor of root-N, where N is the number of atoms in the ensemble. When the collection efficiency of the detection process is taken into account, such a clock can have a frequency stability that is expected to be better than that of a conventional Raman-Ramsey clock. The ultra-narrow fringe may also offer many other potential advantages, such as suppression of errors due to fluctuations in the bias field used for lifting Zeeman sublevel degeneracy, and the long-term bias drift. We will present the theoretical model, and describe the status of our experimental efforts towards demonstrating such a clock.

  15. The atomic orbitals of the topological atom.

    PubMed

    Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István

    2013-06-07

    The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.

  16. "Bohr's Atomic Model."

    ERIC Educational Resources Information Center

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  17. Body weight relationships in early marriage. Weight relevance, weight comparisons, and weight talk.

    PubMed

    Bove, Caron F; Sobal, Jeffery

    2011-12-01

    This investigation uncovered processes underlying the dynamics of body weight and body image among individuals involved in nascent heterosexual marital relationships in Upstate New York. In-depth, semi-structured qualitative interviews conducted with 34 informants, 20 women and 14 men, just prior to marriage and again one year later were used to explore continuity and change in cognitive, affective, and behavioral factors relating to body weight and body image at the time of marriage, an important transition in the life course. Three major conceptual themes operated in the process of developing and enacting informants' body weight relationships with their partner: weight relevance, weight comparisons, and weight talk. Weight relevance encompassed the changing significance of weight during early marriage and included attracting and capturing a mate, relaxing about weight, living healthily, and concentrating on weight. Weight comparisons between partners involved weight relativism, weight competition, weight envy, and weight role models. Weight talk employed pragmatic talk, active and passive reassurance, and complaining and critiquing criticism. Concepts emerging from this investigation may be useful in designing future studies of and approaches to managing body weight in adulthood.

  18. Body Weight Relationships in Early Marriage: Weight Relevance, Weight Comparisons, and Weight Talk

    PubMed Central

    Bove, Caron F.; Sobal, Jeffery

    2011-01-01

    This investigation uncovered processes underlying the dynamics of body weight and body image among individuals involved in nascent heterosexual marital relationships in Upstate New York. In-depth, semi-structured qualitative interviews conducted with 34 informants, 20 women and 14 men, just prior to marriage and again one year later were used to explore continuity and change in cognitive, affective, and behavioral factors relating to body weight and body image at the time of marriage, an important transition in the life course. Three major conceptual themes operated in the process of developing and enacting informants’ body weight relationships with their partner: weight relevance, weight comparisons, and weight talk. Weight relevance encompassed the changing significance of weight during early marriage and included attracting and capturing a mate, relaxing about weight, living healthily, and concentrating on weight. Weight comparisons between partners involved weight relativism, weight competition, weight envy, and weight role models. Weight talk employed pragmatic talk, active and passive reassurance, and complaining and critiquing criticism. Concepts emerging from this investigation may be useful in designing future studies of and approaches to managing body weight in adulthood. PMID:21864601

  19. Atomic Energy Basics, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  20. 14 CFR 23.25 - Weight limits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 23.25 Section 23.25 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight General § 23.25 Weight...

  1. Iterative methods for weighted least-squares

    SciTech Connect

    Bobrovnikova, E.Y.; Vavasis, S.A.

    1996-12-31

    A weighted least-squares problem with a very ill-conditioned weight matrix arises in many applications. Because of round-off errors, the standard conjugate gradient method for solving this system does not give the correct answer even after n iterations. In this paper we propose an iterative algorithm based on a new type of reorthogonalization that converges to the solution.

  2. Determination of arsenic in vegetable samples by hydride generation atomic absorption spectrometry

    SciTech Connect

    Navarro, M.; Lopez, M.C.; Lopez, H.; Sanchez, M.

    1992-11-01

    A procedure is described for the determination of arsenic in vegetable samples by hydride generation atomic absorption spectrometry. The samples are mineralized in a microwave acid digestion bomb with nitric acid in the presence of small amounts of vanadium pentoxide. The determination of arsenic is made by the standard addition method. A certified reference sample is analyzed, and the result obtained agreed well with the certified value. The detection limit (dry weight) was about 0.020 {mu}g/g. Reproducibility relative standard deviations ranged from 6.45% at 0.152 {mu}g As/g to 8.31% at 0.059 {mu}g As/g. The concentrations of arsenic in vegetable samples ranged from 0.029 to 0.444 {mu}g/g (fresh weight). 24 refs., 4 tabs.

  3. Proven Weight Loss Methods

    MedlinePlus

    Fact Sheet Proven Weight Loss Methods What can weight loss do for you? Losing weight can improve your health in a number of ways. It can lower ... at www.hormone.org/Spanish . Proven Weight Loss Methods Fact Sheet www.hormone.org

  4. Standardization of hormone determinations.

    PubMed

    Stenman, Ulf-Håkan

    2013-12-01

    Standardization of hormone determinations is important because it simplifies interpretation of results and facilitates the use of common reference values for different assays. Progress in standardization has been achieved through the introduction of more homogeneous hormone standards for peptide and protein hormones. However, many automated methods for determinations of steroid hormones do not provide satisfactory result. Isotope dilution-mass spectrometry (ID-MS) has been used to establish reference methods for steroid hormone determinations and is now increasingly used for routine determinations of steroids and other low molecular weight compounds. Reference methods for protein hormones based on MS are being developed and these promise to improve standardization.

  5. Limitations on long-term stability and accuracy in atomic clocks

    NASA Technical Reports Server (NTRS)

    Wineland, D. J.

    1979-01-01

    The limits to accuracy and long term stability in present atomic clocks are examined. Recent proposals for new frequency standards are discussed along with the advantages and disadvantages of frequency standards based on such ideas as laser transitions, single atoms, and atom cooling. The applicability of some of these new techniques to existing standards is examined.

  6. Atomic time scales and pulsars

    NASA Astrophysics Data System (ADS)

    Petit, G.

    2014-12-01

    I review the atomic time scales generated by the BIPM, International Atomic Time TAI and the realization of Terrestrial Time TT(BIPM). TT(BIPM) is shown to be now accurate to within a few 10..16 in relative frequency and the performances of TAI and TT(BIPM) are compared. Millisecond pulsars have a very regular period of rotation and data from several pulsars may be used to realize an ensemble pulsar timescale. It is shown that a pulsar timescale may detect past instabilities in TAI. However TT(BIPM) is much more stable than TAI and should be used as a reference in pulsar analysis. Since the beginning of regular millisecond pulsar observations in the 1980s, primary standards and atomic time have gained one order of magnitude in accuracy every ~ 12 years, and this trend should continue for some time.

  7. Laser Trapping of Radioactive Atoms

    NASA Astrophysics Data System (ADS)

    Lu, Zheng-Tian

    2013-04-01

    Stuart Freedman conceived the idea of laser trapping radioactive atoms for the purpose of studying beta correlation effects. ``This is really the theorist's view of a radioactive source,'' as he fondly claimed. It is ideal because the atoms form a point source, compressed in both position and momentum space, with no material walls nearby. The Berkeley group succeeded in trapping ^21Na (half-life = 22 s) atoms [Lu et al., PRL 72, 3791 (1994)], and determined its beta-neutrino correlation coefficient a=0.5502(60) to be in agreement with the Standard Model [Vetter et al., PRC 77, 035502 (2008)]. Other groups have joined this effort with searches for scalar or tensor couplings in the weak interaction. Moreover, the technique has been extended to trap very short lived ^8He (0.1 s) to study its halo structure or the very long lived ^81Kr (230,000 yr) to map the movement of groundwater.

  8. Atom lithography with metastable helium

    SciTech Connect

    Allred, Claire S.; Reeves, Jason; Corder, Christopher; Metcalf, Harold

    2010-02-15

    A bright metastable helium (He*) beam is collimated sequentially with the bichromatic force and three optical molasses velocity compression stages. Each He* atom in the beam has 20 eV of internal energy that can destroy a molecular resist assembled on a gold coated silicon wafer. Patterns in the resist are imprinted onto the gold layer with a standard selective etch. Patterning of the wafer with the He{sup *} was demonstrated with two methods. First, a mesh was used to protect parts of the wafer making an array of grid lines. Second, a standing wave of {lambda}=1083 nm light was used to channel and focus the He* atoms into lines separated by {lambda}/2. The patterns were measured with an atomic force microscope establishing an edge resolution of 80 nm. Our results are reliable and repeatable.

  9. Characteristics of advanced hydrogen maser frequency standards

    NASA Technical Reports Server (NTRS)

    Peters, H. E.

    1973-01-01

    In house research and development at Goddard Space Flight Center to provide advanced frequency and time standards for the most demanding applications is concentrated primarily in field operable atomic hydrogen masers. Some of the most important goals for the new maser designs have been improved long and short term stability, elimination of the need for auto tuning, increased maser oscillation level, improved hydrogen economy, increased operational life, minimization of operator control or monitoring, improvement in magnetic isolation or sensitivity, and reduction in size and weight. New design concepts which have been incorporated in these masers to achieve these goals are described. The basic maser assemblies and control systems have recently been completed; the masers are oscillating; and operational testing has begun. Data illustrating the improvements in maser performance was available and presented.

  10. Temperature measurement of cold atoms using single-atom transits and Monte Carlo simulation in a strongly coupled atom-cavity system

    SciTech Connect

    Li, Wenfang; Du, Jinjin; Wen, Ruijuan; Yang, Pengfei; Li, Gang; Zhang, Tiancai; Liang, Junjun

    2014-03-17

    We investigate the transmission of single-atom transits based on a strongly coupled cavity quantum electrodynamics system. By superposing the transit transmissions of a considerable number of atoms, we obtain the absorption spectra of the cavity induced by single atoms and obtain the temperature of the cold atom. The number of atoms passing through the microcavity for each release is also counted, and this number changes exponentially along with the atom temperature. Monte Carlo simulations agree closely with the experimental results, and the initial temperature of the cold atom is determined. Compared with the conventional time-of-flight (TOF) method, this approach avoids some uncertainties in the standard TOF and sheds new light on determining temperature of cold atoms by counting atoms individually in a confined space.

  11. Line splitting and modified atomic decay of atoms coupled with N quantized cavity modes

    NASA Astrophysics Data System (ADS)

    Zhu, Yifu

    1992-05-01

    We study the interaction of a two-level atom with N non-degenerate quantized cavity modes including dissipations from atomic decay and cavity damps. In the strong coupling regime, the absorption or emission spectrum of weakly excited atom-cavity system possesses N + 1 spectral peaks whose linewidths are the weighted averages of atomic and cavity linewidths. The coupled system shows subnatural (supernatural) atomic decay behavior if the photon loss rates from the N cavity modes are smaller (larger) than the atomic decay rate. If N cavity modes are degenerate, they can be treated effectively as a single mode. In addition, we present numerical calculations for N = 2 to characterize the system evolution from the weak coupling to strong coupling limits.

  12. Low keV electron probe analysis of silicate minerals for Mg, Al, and Si using pure-element standards

    NASA Technical Reports Server (NTRS)

    Cunningham, G. G.

    1972-01-01

    Accurate electron probe values for Mg, Al, and Si in silicate minerals may be obtained with pure-element standards. Analysis must be done at low (6 kV) accelerating potential and for best results, the average atomic number of the sample should be within about plus or minus 1 of the atomic number of the pure-element standard. This last requirement is automatically fulfilled for most common silicate minerals, as their average atomic numbers usually fall within the 11 to 15 range. Examples studied include a wet-chemically analyzed cordierite containing 17.71 weight percent Al, for which a value of 17.6 plus or minus 0.3 percent was obtained with the electron probe, and a hornblende containing 19.15 percent Si, which gave 19.0 plus or minus 0.3 percent using the probe method.

  13. Neutral atom traps.

    SciTech Connect

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  14. Stochastic models for atomic clocks

    NASA Technical Reports Server (NTRS)

    Barnes, J. A.; Jones, R. H.; Tryon, P. V.; Allan, D. W.

    1983-01-01

    For the atomic clocks used in the National Bureau of Standards Time Scales, an adequate model is the superposition of white FM, random walk FM, and linear frequency drift for times longer than about one minute. The model was tested on several clocks using maximum likelihood techniques for parameter estimation and the residuals were acceptably random. Conventional diagnostics indicate that additional model elements contribute no significant improvement to the model even at the expense of the added model complexity.

  15. Losing weight after pregnancy

    MedlinePlus

    ... below the minimum number of calories you need. Breastfeeding If you are breastfeeding, you will want to lose weight slowly. Weight ... not affect your milk supply or your health. Breastfeeding makes your body burn calories. It helps you ...

  16. Antidepressants and Weight Gain

    MedlinePlus

    Diseases and Conditions Depression (major depressive disorder) Can antidepressants cause weight gain? Answers from Daniel K. Hall-Flavin, M.D. Weight gain is a possible side effect of nearly all antidepressants. ...

  17. Atomic Force Microscopy on Its Way to Adolescence

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.

    2003-12-01

    When the atomic force microscope (AFM) was introduced in 1986, its potential to resolve surfaces with true atomic resolution was already proposed. However, substantial problems had to be overcome before atomic resolution became possible by AFM. Today, true atomic resolution by AFM is standard practice. This article discusses the influence of the cantilever stiffness and — amplitude on noise and short-range force sensitivity and introduces a sensor operating at near optimal conditions (qPlus sensor). The data achieved with this optimized sensing technology show substructures within single atom images, attributed to atomic orbitals.

  18. Chip-Scale Magnetic Source of Cold Atoms

    DTIC Science & Technology

    2013-06-01

    Atom Production . . . . . . . . . . . . . 2 1.1.3.1 The Magneto-Optic Trap . . . . . . . . . . . . . . . . . 2 1.1.3.2 The Zeeman Slower...a confined gas of atoms is cooled past a certain threshold, quantum effects become apparent. On a broad level, this can be understood by the de...Methods of Cold Atom Production. 1.1.3.1 The Magneto-Optic Trap. The effective standard for creating cold neutral atoms is the magneto-optic trap (MOT

  19. Gradient Weight in Phonology

    ERIC Educational Resources Information Center

    Ryan, Kevin Michael

    2011-01-01

    Research on syllable weight in generative phonology has focused almost exclusively on systems in which weight is treated as an ordinal hierarchy of clearly delineated categories (e.g. light and heavy). As I discuss, canonical weight-sensitive phenomena in phonology, including quantitative meter and quantity-sensitive stress, can also treat weight…

  20. Assessing Your Weight

    MedlinePlus

    ... to learn more? Preventing Weight Gain Choosing a lifestyle that includes good eating habits and daily physical activity can help you maintain a healthy weight and prevent weight gain. The Possible Health Effects from Having Obesity Having obesity can increase your chances of developing ...

  1. Band geometry, Berry curvature, and superfluid weight

    NASA Astrophysics Data System (ADS)

    Liang, Long; Vanhala, Tuomas I.; Peotta, Sebastiano; Siro, Topi; Harju, Ari; Törmä, Päivi

    2017-01-01

    We present a theory of the superfluid weight in multiband attractive Hubbard models within the Bardeen-Cooper-Schrieffer (BCS) mean-field framework. We show how to separate the geometric contribution to the superfluid weight from the conventional one, and that the geometric contribution is associated with the interband matrix elements of the current operator. Our theory can be applied to systems with or without time-reversal symmetry. In both cases the geometric superfluid weight can be related to the quantum metric of the corresponding noninteracting systems. This leads to a lower bound on the superfluid weight given by the absolute value of the Berry curvature. We apply our theory to the attractive Kane-Mele-Hubbard and Haldane-Hubbard models, which can be realized in ultracold atom gases. Quantitative comparisons are made to state of the art dynamical mean-field theory and exact diagonalization results.

  2. The Effect of the Weight Scheme on DFT Vibrational Frequencies

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles; Ricca, Alessandra

    1999-01-01

    All-electron B3LYP harmonic frequencies of Ge2H5 and Ge2H6 are computed for several choices of grid and using both the Becke and the Stratmann, Scuseria, and Frisch atomic partition functions (weight scheme). For large grids, the results are independent of the weighting scheme. The lowest frequency mode is much more stable with respect to the number of grid points when the Stratmann, Scuseria, and Frisch weights are used.

  3. Optimization of electrothermal atomization parameters for simultaneous multielement atomic absorption spectrometry

    USGS Publications Warehouse

    Harnly, J.M.; Kane, J.S.

    1984-01-01

    The effect of the acid matrix, the measurement mode (height or area), the atomizer surface (unpyrolyzed and pyrolyzed graphite), the atomization mode (from the wall or from a platform), and the atomization temperature on the simultaneous electrothermal atomization of Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn was examined. The 5% HNO3 matrix gave rise to severe irreproducibility using a pyrolyzed tube unless the tube was properly "prepared". The 5% HCl matrix did not exhibit this problem, and no problems were observed with either matrix using an unpyrolized tube or a pyrolyzed platform. The 5% HCl matrix gave better sensitivities with a pyrolyzed tube but the two matrices were comparable for atomization from a platform. If Mo and V are to be analyzed with the other seven elements, a high atomization temperature (2700??C or greater) is necessary regardless of the matrix, the measurement mode, the atomization mode, or the atomizer surface. Simultaneous detection limits (peak height with pyrolyzed tube atomization) were comparable to those of conventional atomic absorption spectrometry using electrothermal atomization above 280 nm. Accuracies and precisions of ??10-15% were found in the 10 to 120 ng mL-1 range for the analysis of NBS acidified water standards.

  4. Atomic Particle Detection, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Hellman, Hal

    This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. The instruments used to detect both particles and electromagnetic radiation that emerge from the nucleus are described. The counters reviewed include ionization chambers,…

  5. Atomic Fuel, Understanding the Atom Series. Revised.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is part of the "Understanding the Atom" series. Complete sets of the series are available free to teachers, schools, and public librarians who can make them available for reference or use by groups. Among the topics discussed are: What Atomic Fuel Is; The Odyssey of Uranium; Production of Uranium; Fabrication of Reactor…

  6. Determination of nanogram amounts of bismuth in rocks by atomic absorption spectrometry with electrothermal atomization

    USGS Publications Warehouse

    Kane, J.S.

    1979-01-01

    Bismuth concentrations as low as 10 ng g-1 in 100-mg samples of geological materials can be determined by atomic absorption spectrometry with electrothermal atomization. After HF-HClO4 decomposition of the sample, bismuth is extracted as the iodide into methyl isobutyl ketone and is then stripped with ethylenediaminetetraacetic acid into the aqueous phase. Aliquots of this solution are pipetted into the graphite furnace and dried, charred, and atomized in an automated sequence. Atomic absorbance at the Bi 223.1-nm line provides a measure of the amount of bismuth present. Results are presented for 14 U.S. Geological Survey standard rocks. ?? 1979.

  7. Yogurt and weight management.

    PubMed

    Jacques, Paul F; Wang, Huifen

    2014-05-01

    A large body of observational studies and randomized controlled trials (RCTs) has examined the role of dairy products in weight loss and maintenance of healthy weight. Yogurt is a dairy product that is generally very similar to milk, but it also has some unique properties that may enhance its possible role in weight maintenance. This review summarizes the human RCT and prospective observational evidence on the relation of yogurt consumption to the management and maintenance of body weight and composition. The RCT evidence is limited to 2 small, short-term, energy-restricted trials. They both showed greater weight losses with yogurt interventions, but the difference between the yogurt intervention and the control diet was only significant in one of these trials. There are 5 prospective observational studies that have examined the association between yogurt and weight gain. The results of these studies are equivocal. Two of these studies reported that individuals with higher yogurt consumption gained less weight over time. One of these same studies also considered changes in waist circumference (WC) and showed that higher yogurt consumption was associated with smaller increases in WC. A third study was inconclusive because of low statistical power. A fourth study observed no association between changes in yogurt intake and weight gain, but the results suggested that those with the largest increases in yogurt intake during the study also had the highest increase in WC. The final study examined weight and WC change separately by sex and baseline weight status and showed benefits for both weight and WC changes for higher yogurt consumption in overweight men, but it also found that higher yogurt consumption in normal-weight women was associated with a greater increase in weight over follow-up. Potential underlying mechanisms for the action of yogurt on weight are briefly discussed.

  8. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    NASA Astrophysics Data System (ADS)

    Marschner, Karel; Musil, Stanislav; Dědina, Jiří

    2015-07-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH4 in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l- 1 and 1.0 ng l- 1, respectively.

  9. Light-weight ceramic insulation

    NASA Technical Reports Server (NTRS)

    Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    2002-01-01

    Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

  10. Spreadsheet-Based Program for Simulating Atomic Emission Spectra

    ERIC Educational Resources Information Center

    Flannigan, David J.

    2014-01-01

    A simple Excel spreadsheet-based program for simulating atomic emission spectra from the properties of neutral atoms (e.g., energies and statistical weights of the electronic states, electronic partition functions, transition probabilities, etc.) is described. The contents of the spreadsheet (i.e., input parameters, formulas for calculating…

  11. Polymeric Materials Resistant to Erosion by Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Kiefer, Richard L.; Thibeault, Sheila A.

    2004-01-01

    Polymer-matrix composites are ideally suited for space vehicles because of high strength to weight ratios. The principal component of the low earth orbit (LEO) is atomic oxygen. Atomic oxygen causes surface erosion to polymeric materials. Polymer films with an organometallic additive showed greater resistance to atomic oxygen than the pure polymer in laboratory experiments and in the OPM/MIR experiment. In MISSE, the film with the organometallic additive was still intact after the pure film had completely eroded.

  12. Muonic Atoms and the Nuclear Structure

    NASA Astrophysics Data System (ADS)

    Antognini, A.

    High-precision laser spectroscopy of atomic energy levels enables the measurement of nuclear properties. Sensitivity to these properties is particularly enhanced in muonic atoms which are bound systems of a muon and a nucleus. Exemplary is the measurement of the proton charge radius from muonic hydrogen performed by the CREMA collaboration which resulted in an order of magnitude more precise charge radius as extracted from other methods but at a variance of 7 standard deviations. Here, we summarize the role of muonic atoms for the extraction of nuclear charge radii, we present the status of the so called "proton charge radius puzzle", and we sketch how muonic atoms can be used to infer also the magnetic nuclear radii, demonstrating again an interesting interplay between atomic and particle/nuclear physics.

  13. Presenting the Bohr Atom.

    ERIC Educational Resources Information Center

    Haendler, Blanca L.

    1982-01-01

    Discusses the importance of teaching the Bohr atom at both freshman and advanced levels. Focuses on the development of Bohr's ideas, derivation of the energies of the stationary states, and the Bohr atom in the chemistry curriculum. (SK)

  14. Standard Procedure.

    ERIC Educational Resources Information Center

    Uher, Alan E.

    Whether common standards exist among the national standards for kindergarten through grade 12 mathematics, science, and civics and government was studied. Common standards were explored among "Curriculum and Evaluation Standards for School Mathematics," produced by the National Council of Teachers of Mathematics, the "National…

  15. Atom column indexing: atomic resolution image analysis through a matrix representation.

    PubMed

    Sang, Xiahan; Oni, Adedapo A; LeBeau, James M

    2014-12-01

    Here, we report the development of an approach to map atomic resolution images into a convenient matrix representation. Through the combination of two-dimensional Gaussian fitting and the projective standard deviation, atom column locations are projected onto two noncollinear reference lattice vectors that are used to assign each a unique (i, j) matrix index. By doing so, straightforward atomic resolution image analysis becomes possible. Using practical examples, we demonstrate that the matrix representation greatly simplifies categorizing atom columns to different sublattices. This enables a myriad of direct analyses, such as mapping atom column properties and correlating long-range atom column pairs. MATLAB source code can be downloaded from https://github.com/subangstrom/aci.

  16. Atoms in Action

    SciTech Connect

    2009-01-01

    This movie produced with Berkeley Lab's TEAM 0.5 microscope shows the growth of a hole and the atomic edge reconstruction in a graphene sheet. An electron beam focused to a spot on the sheet blows out the exposed carbon atoms to make the hole. The carbon atoms then reposition themselves to find a stable configuration. http://newscenter.lbl.gov/press-releases/2009/03/26/atoms-in-action/

  17. HYDROGEN ATOM THERMAL PARAMETERS.

    PubMed

    JENSEN, L H; SUNDARALINGAM, M

    1964-09-11

    Isotropic hydrogen atom thermal parameters for N,N'- hexamethylenebispropionamide have been determined. They show a definite trend and vary from approximately the same as the mean thermal parameters for atoms other than hydrogen near the center of the molecule to appreciably greater for atoms near the end. The indicated trend for this compound, along with other results, provides the basis for a possible explanation of the anomolous values that have been obtained for hydrogen atom thermal parameters.

  18. Atomizing nozzle and process

    DOEpatents

    Anderson, I.E.; Figliola, R.S.; Molnar, H.M.

    1993-07-20

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  19. Atomizing nozzle and process

    DOEpatents

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1992-06-30

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  20. A compact atomic beam based system for Doppler-free laser spectroscopy of strontium atoms

    NASA Astrophysics Data System (ADS)

    Verma, Gunjan; Vishwakarma, Chetan; Dharmadhikari, C. V.; Rapol, Umakant D.

    2017-03-01

    We report the construction of a simple, light weight, and compact atomic beam spectroscopy cell for strontium atoms. The cell is built using glass blowing technique and includes a simple titanium sublimation pump for the active pumping of residual and background gases to maintain ultra-high vacuum. A commercially available and electrically heated dispenser source is used to generate the beam of Sr atoms. We perform spectroscopy on the 5 s2S10 →5 s 5 pP11 transition to obtain a well resolved Doppler free spectroscopic signal for frequency stabilization of the laser source. This design can be easily extended to other alkali and alkaline earth metals.

  1. The Nature of Atoms.

    ERIC Educational Resources Information Center

    Holden, Alan

    This monograph was written for the purpose of presenting physics to college students who are not preparing for careers in physics. It deals with the nature of atoms, and treats the following topics: (1) the atomic hypothesis, (2) the chemical elements, (3) models of an atom, (4) a particle in a one-dimensional well, (5) a particle in a central…

  2. Atomic Spectra Database (ASD)

    National Institute of Standards and Technology Data Gateway

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  3. Images of Atoms.

    ERIC Educational Resources Information Center

    Wright, Tony

    2003-01-01

    Recommends using a simple image, such as the fuzzy atom ball to help students develop a useful understanding of the molecular world. Explains that the image helps students easily grasp ideas about atoms and molecules and leads naturally to more advanced ideas of atomic structure, chemical bonding, and quantum physics. (Author/NB)

  4. Upper Limit of Weights in TAI Computation

    NASA Technical Reports Server (NTRS)

    Thomas, Claudine; Azoubib, Jacques

    1996-01-01

    The international reference time scale International Atomic Time (TAI) computed by the Bureau International des Poids et Mesures (BIPM) relies on a weighted average of data from a large number of atomic clocks. In it, the weight attributed to a given clock depends on its long-term stability. In this paper the TAI algorithm is used as the basis for a discussion of how to implement an upper limit of weight for clocks contributing to the ensemble time. This problem is approached through the comparison of two different techniques. In one case, a maximum relative weight is fixed: no individual clock can contribute more than a given fraction to the resulting time scale. The weight of each clock is then adjusted according to the qualities of the whole set of contributing elements. In the other case, a parameter characteristic of frequency stability is chosen: no individual clock can appear more stable than the stated limit. This is equivalent to choosing an absolute limit of weight and attributing this to to the most stable clocks independently of the other elements of the ensemble. The first technique is more robust than the second and automatically optimizes the stability of the resulting time scale, but leads to a more complicated computatio. The second technique has been used in the TAI algorithm since the very beginning. Careful analysis of tests on real clock data shows that improvement of the stability of the time scale requires revision from time to time of the fixed value chosen for the upper limit of absolute weight. In particular, we present results which confirm the decision of the CCDS Working Group on TAI to increase the absolute upper limit by a factor of 2.5. We also show that the use of an upper relative contribution further helps to improve the stability and may be a useful step towards better use of the massive ensemble of HP 507IA clocks now contributing to TAI.

  5. Frequency Tunable Atomic Magnetometer based on an Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Narducci, Frank; Braje, Danielle; Davis, Jon; Adler, Charles

    2013-05-01

    We theoretically and experimentally study a magnetically sensitive atom interferometer. Using a stationary atom cloud, a time-domain interferometer is formed on magnetically sensitive states of 85Rb. We show that the temporal spacing of a Raman pulse sequence controls the frequency of the magnetic field detected by the interferometer, thereby potentially eliminating unwanted noise and optimizing detection in frequency bands of interest. We focus on a standard π / 2 - π - π / 2 sequence and explore the utility of multiple π pulses. The Lincoln Laboratory portion of this work is sponsored by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract #FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the authors and are not necessarily endorsed by the United States Government. This work at NavAir was supported by the Office of Naval Research and by the NavAir Chief Technology Office.

  6. Single atom electrochemical and atomic analytics

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  7. Multilevel Atomic Coherent States and Atomic Holomorphic Representation

    NASA Technical Reports Server (NTRS)

    Cao, Chang-Qi; Haake, Fritz

    1996-01-01

    The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

  8. Atomic Clock Based On Linear Ion Trap

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Dick, G. John

    1992-01-01

    Highly stable atomic clock based on excitation and measurement of hyperfine transition in 199Hg+ ions confined in linear quadrupole trap by radio-frequency and static electric fields. Configuration increases stability of clock by enabling use of enough ions to obtain adequate signal while reducing non-thermal component of motion of ions in trapping field, reducing second-order Doppler shift of hyperfine transition. Features described in NPO-17758 "Linear Ion Trap for Atomic Clock." Frequency standard based on hyperfine transition described in NPO-17456, "Trapped-Mercury-Ion Frequency Standard."

  9. Portable compact cold atoms clock topology

    NASA Astrophysics Data System (ADS)

    Pechoneri, R. D.; Müller, S. T.; Bueno, C.; Bagnato, V. S.; Magalhães, D. V.

    2016-07-01

    The compact frequency standard under development at USP Sao Carlos is a cold atoms system that works with a distributed hardware system principle and temporal configuration of the interrogation method of the atomic sample, in which the different operation steps happen in one place: inside the microwave cavity. This type of operation allows us to design a standard much more compact than a conventional one, where different interactions occur in the same region of the apparatus. In this sense, it is necessary to redefine all the instrumentation associated with the experiment. This work gives an overview of the topology we are adopting for the new system.

  10. Weight gain - unintentional

    MedlinePlus

    ... trying to do so can have many causes. Metabolism slows down as you age . This can cause weight gain if you eat too much, eat the wrong foods, or do not get enough exercise. Drugs that can cause weight gain include: Birth ...

  11. The Meaning of Weight

    ERIC Educational Resources Information Center

    Iona, Mario

    1975-01-01

    Presents a summary and comparison of various views on the concepts of mass and weight. Includes a consideration of gravitational force in an inertial system and apparent gravitational force on a rotating earth. Discusses the units and methods for measuring mass and weight. (GS)

  12. Labor Supply and Weight

    ERIC Educational Resources Information Center

    Lakdawalla, Darius; Philipson, Tomas

    2007-01-01

    We use panel data from the National Longitudinal Survey of Youth to investigate on-the-job exercise and weight. For male workers, job-related exercise has causal effects on weight, but for female workers, the effects seem primarily selective. A man who spends 18 years in the most physical fitness-demanding occupation is about 25 pounds (14…

  13. Keep Weight Off

    MedlinePlus

    ... proved to be the most useful by the end of the 2 ½-year study. Researchers say overall the effects of the counseling and support were modest, and most people in the study did regain some weight. But they note that even modest weight loss can have health ...

  14. Exercise and Weight Control.

    ERIC Educational Resources Information Center

    Katch, Victor L.

    This paper describes a number of factors which go into determining weight. The paper describes what calories are, how caloric expenditure is measured, and why caloric expenditure is different for different people. The paper then outlines the way the body tends to adjust food intake and exercise to maintain a constant body weight. It is speculated…

  15. Pregnancy and Healthy Weight

    MedlinePlus

    ... Profiles Multimedia Pregnancy & Healthy Weight Skip sharing on social media links Share this: Page Content New research shows that maintaining a healthy weight before and during pregnancy can reduce the likelihood of negative effects for mothers and babies We’ve heard the ...

  16. The Weighted Oblimin Rotation.

    ERIC Educational Resources Information Center

    Lorenzo-Seva, Urbano

    2000-01-01

    Demonstrates that the weighting procedure proposed by E. Cureton and S. Mulaik (1975) can be applied to the Direct Oblimin approach of D. Clarkson and R. Jennrich (1988) to provide good results. The rotation method obtained is called Weighted Oblimin. Compared this method to other rotation methods with favorable results. (SLD)

  17. Common Weight Loss Challenges

    MedlinePlus

    ... to lose that we’ve been talking about weight-loss surgery. Is that something we should consider?” Although the ... have the operation should not be made hastily. Weight-loss surgery is only advisable for extremely overweight adolescents for ...

  18. Head-on Collisions of Xe Atoms Against Superfluid ^4 He Nanodroplets

    NASA Astrophysics Data System (ADS)

    Coppens, François; Leal, Antonio; Barranco, Manuel; Halberstadt, Nadine; Pi, Marti

    2016-11-01

    We study the head-on collision of a heliophilic xenon atom with a superfluid ^4 He droplet made of 1000 atoms. At variance with the findings for a heliophobic cesium atom of a similar atomic weight, it is found that the xenon atom has to hit the droplet with a large kinetic energy in order to get across it without being captured. When it is not captured, the xenon impurity does not emerge as a bare atom; instead, due to its heliophilic character it carries away some helium atoms.

  19. Sulfide bonded atomic radii

    NASA Astrophysics Data System (ADS)

    Gibbs, G. V.; Ross, N. L.; Cox, D. F.

    2017-03-01

    The bonded radius, r b(S), of the S atom, calculated for first- and second-row non-transition metal sulfide crystals and third-row transition metal sulfide molecules and crystals indicates that the radius of the sulfur atom is not fixed as traditionally assumed, but that it decreases systematically along the bond paths of the bonded atoms with decreasing bond length as observed in an earlier study of the bonded radius of the oxygen atom. When bonded to non-transition metal atoms, r b(S) decreases systematically with decreasing bond length from 1.68 Å when the S atom is bonded to the electropositive VINa atom to 1.25 Å when bonded to the more electronegative IVP atom. In the case of transition metal atoms, rb(S) likewise decreases with decreasing bond length from 1.82 Å when bonded to Cu and to 1.12 Å when bonded to Fe. As r b(S) is not fixed at a given value but varies substantially depending on the bond length and the field strength of the bonded atoms, it is apparent that sets of crystal and atomic sulfide atomic radii based on an assumed fixed radius for the sulfur atom are satisfactory in that they reproduce bond lengths, on the one hand, whereas on the other, they are unsatisfactory in that they fail to define the actual sizes of the bonded atoms determined in terms of the minima in the electron density between the atoms. As such, we urge that the crystal chemistry and the properties of sulfides be studied in terms of the bond lengths determined by adding the radii of either the atomic and crystal radii of the atoms but not in terms of existing sets of crystal and atomic radii. After all, the bond lengths were used to determine the radii that were experimentally determined, whereas the individual radii were determined on the basis of an assumed radius for the sulfur atom.

  20. Weight discrimination and bullying.

    PubMed

    Puhl, Rebecca M; King, Kelly M

    2013-04-01

    Despite significant attention to the medical impacts of obesity, often ignored are the negative outcomes that obese children and adults experience as a result of stigma, bias, and discrimination. Obese individuals are frequently stigmatized because of their weight in many domains of daily life. Research spanning several decades has documented consistent weight bias and stigmatization in employment, health care, schools, the media, and interpersonal relationships. For overweight and obese youth, weight stigmatization translates into pervasive victimization, teasing, and bullying. Multiple adverse outcomes are associated with exposure to weight stigmatization, including depression, anxiety, low self-esteem, body dissatisfaction, suicidal ideation, poor academic performance, lower physical activity, maladaptive eating behaviors, and avoidance of health care. This review summarizes the nature and extent of weight stigmatization against overweight and obese individuals, as well as the resulting consequences that these experiences create for social, psychological, and physical health for children and adults who are targeted.

  1. Parental weight (mis)perceptions: factors influencing parents' ability to correctly categorise their child's weight status.

    PubMed

    Hudson, Eibhlin; McGloin, Aileen; McConnon, Aine

    2012-12-01

    This study investigates parents' ability to correctly classify their child's weight status. The influence of parent and child socio-demographic and lifestyle factors on parental misclassification of their child's weight status is explored. A representative sample of Irish children (aged 5-12 (n = 596) years, aged 13-17 years (n = 441)) and their parents (n = 1885) were recruited to participate in a national dietary survey. Parental perceptions of their child's weight and their own weight were measured. Anthropometric measurements (weight and height) were objectively measured for parents and children. Body Mass Index (BMI) scores were derived and categorised as normal, overweight or obese using standard references. Over 80% of parents of overweight boys and 79.3% of parents of overweight girls reported their child's weight was fine for his/her height and age. Furthermore, 44.4% of parents of obese boys and 45.3% of parents of obese girls felt their child's weight was fine for their height and age. Parents were significantly less likely to be correct about their sons' weight status and more likely to be correct the older the child. Parents were over 86% less likely to be correct about their child's weight if their child was overweight and approximately 59% less likely to be correct if the child was obese, compared to parents of normal weight children. This research suggests that parents are failing to recognise overweight and obesity in their children with factors such as parental weight status, child's age and gender influencing this.

  2. Birth Weight, Early Weight Gain and Pubertal Maturation: a Longitudinal Study

    PubMed Central

    Wang, Yan; Dinse, Gregg E.; Rogan, Walter J.

    2011-01-01

    Objective To investigate the effect of birth weight and early weight gain on the timing of various measures of puberty in both girls and boys. Methods A total of 856 newborns enrolled in the North Carolina Infant Feeding Study were followed to age 5 years, with 600 children followed up at adolescence. Birth weight was obtained from medical records and children were weighed at study visits until age 5 years; gains in standardized weights were calculated over four early age intervals: 0–6 months, 6–12 months, 1–2 years, and 2–5 years. Age at menarche in girls and age at advanced Tanner stages in both girls and boys were reported by adolescents and their parents. Survival models were used to analyze the effects of birth weight and early weight gain on these outcomes. Results Girls with higher birth weight and greater weight gains during the four early age intervals were younger when they reached menarche and advanced Tanner stages; boys with greater early weight gains also were younger when they reached advanced Tanner stages, but few of these effects were statistically significant. Conclusions Higher birth weights and greater weight gains during infancy and early childhood can lead to earlier sexual maturation in girls. PMID:22434749

  3. Internal disinhibition predicts 5‐year weight regain in the National Weight Control Registry (NWCR)

    PubMed Central

    Thomas, J. G.; Niemeier, H.; Wing, R. R.

    2016-01-01

    Summary Background Maintenance of weight loss remains elusive for most individuals. One potential innovative target is internal disinhibition (ID) or the tendency to eat in response to negative thoughts, feelings or physical sensations. Individuals high on ID do worse on average in standard behavioural treatment programmes, and recent studies suggest that disinhibition could play a significant role in weight regain. Purpose The purpose of the current study was to examine whether ID was associated with weight change over 5 years of follow‐up in the National Weight Control Registry, a registry of individuals who have successfully lost weight and maintained it. Methods From the National Weight Control Registry, 5,320 participants were examined across 5 years. Weight data were gathered annually. The disinhibition subscale of the Eating Inventory was used to calculate internal disinhibition and External Disinhibition (ED) and was collected at baseline, year 1, year 3 and year 5. Linear mixed models were used to estimate the weight loss maintained across follow‐up years 1 to 5 using ID and ED as baseline and prospective predictors. Results Internal disinhibition predicted weight regain in all analyses. ED interacted with ID, such that individuals who were high on ID showed greater weight regain if they were also higher on ED. Conclusions The ID scale could be a useful screening measure for risk of weight regain, given its brevity. Improved psychological coping could be a useful target for maintenance or booster interventions. PMID:27812382

  4. 7 CFR 51.3055 - Standard pack.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Florida Avocados Standard Pack § 51.3055 Standard pack. (a) The avocados shall be packed in accordance with good commercial practice and the pack shall be at... of the weight of the largest fruit in the container. Size of the avocados may be specified by...

  5. Modeling of atomic systems for atomic clocks and quantum information

    NASA Astrophysics Data System (ADS)

    Arora, Bindiya

    This dissertation reports the modeling of atomic systems for atomic clocks and quantum information. This work is motivated by the prospects of optical frequency standards with trapped ions and the quantum computation proposals with neutral atoms in optical lattices. Extensive calculations of the electric-dipole matrix elements in monovalent atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np1/2, np 3/2 states and a large number of excited states of alkali-metal atoms are evaluated using the all-order method. For Ca+ ion, additional allowed transitions between nd5/2, np 3/2, nf5/2, nf 7/2 states and a large number of excited states are evaluated. We combine D1 lines measurements by Miller et al. [18] with our all-order calculations to determine the values of the electric-dipole matrix elements for the 4pj - 3d j' transitions in K and for the 5pj - 4dj' transitions in Rb to high precision. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of ground state of alkali atoms. Our values of static polarizabilities are found to be in excellent agreement with available experiments. Calculations were done for the wavelength in the range 300--1600 nm, with particular attention to wavelengths of common infrared lasers. We parameterize our results so that they can be extended accurately to arbitrary wavelengths above 800 nm. Our data can be used to predict the oscillation frequencies of optically-trapped atoms, and particularly the ratios of frequencies of different species held in the same trap. We identify wavelengths at which two different alkali atoms have the same oscillation frequency. We present results of all-order calculations of static and frequency-dependent polarizabilities of excited np1/2 and np3

  6. The Future of Atomic Energy

    DOE R&D Accomplishments Database

    Fermi, E.

    1946-05-27

    There is definitely a technical possibility that atomic power may gradually develop into one of the principal sources of useful power. If this expectation will prove correct, great advantages can be expected to come from the fact that the weight of the fuel is almost negligible. This feature may be particularly valuable for making power available to regions of difficult access and far from deposits of coal. It also may prove a great asset in mobile power units for example in a power plant for ship propulsion. On the negative side there are some technical limitations to be applicability of atomic power of which perhaps the most serious is the impossibility of constructing light power units; also there will be some peculiar difficulties in operating atomic plants, as for example the necessity of handling highly radioactive substances which will necessitate, at least for some considerable period, the use of specially skilled personnel for the operation. But the chief obstacle in the way of developing atomic power will be the difficulty of organizing a large scale industrial development in an internationally safe way. This presents actually problems much more difficult to solve than any of the technical developments that are necessary, It will require an unusual amount of statesmanship to balance properly the necessity of allaying the international suspicion that arises from withholding technical secrets against the obvious danger of dumping the details of the procedures for an extremely dangerous new method of warfare on a world that may not yet be prepared to renounce war. Furthermore, the proper balance should be found in the relatively short time that will elapse before the 'secrets' will naturally become open knowledge by rediscovery on part of the scientists and engineers of other countries.

  7. Interventions to reduce weight gain in schizophrenia

    PubMed Central

    Faulkner, Guy; Cohn, Tony; Remington, Gary

    2014-01-01

    Background Weight gain is common for people with schizophrenia and this has serious implications for health and well being. Objectives To determine the effects of both pharmacological (excluding medication switching) and non pharmacological strategies for reducing or preventing weight gain in people with schizophrenia. Search methods We searched key databases and the Cochrane Schizophrenia Group’s trials register (April 2006), reference sections within relevant papers, hand searched key journals, and contacted the first author of each relevant study and other experts to collect further information. Selection criteria We included all clinical randomised controlled trials comparing any pharmacological or non pharmacological intervention for weight gain (diet and exercise counselling) with standard care or other treatments for people with schizophrenia or schizophrenia-like illnesses. Data collection and analysis We reliably selected, quality assessed and extracted data from studies. As weight is a continuous outcome measurement, weighted mean differences (WMD) of the change from baseline were calculated. The primary outcome measure was weight loss. Main results Twenty-three randomised controlled trials met the inclusion criteria for this review. Five trials assessed a cognitive/behavioural intervention and eighteen assessed a pharmacological adjunct. In terms of prevention, two cognitive/behavioural trials showed significant treatment effect (mean weight change) at end of treatment (n=104, 2 RCTs, WMD −3.38 kg CI −4.2 to −2.0). Pharmacological adjunct treatments were significant with a modest prevention of weight gain (n=274, 6 RCTs, WMD − 1.16 kg CI −1.9 to −0.4). In terms of treatments for weight loss, we found significantly greater weight reduction in the cognitive behavioural intervention group (n=129, 3 RCTs, WMD −1.69 kg CI −2.8 to −0.6) compared with standard care. Authors’ conclusions Modest weight loss can be achieved with selective

  8. Light-weight plastination.

    PubMed

    Steinke, Hanno; Rabi, Suganthy; Saito, Toshiyuki; Sawutti, Alimjan; Miyaki, Takayoshi; Itoh, Masahiro; Spanel-Borowski, Katharina

    2008-11-20

    Plastination is an excellent technique which helps to keep the anatomical specimens in a dry, odourless state. Since the invention of plastination technique by von Hagens, research has been done to improve the quality of plastinated specimens. In this paper, we have described a method of producing light-weight plastinated specimens using xylene along with silicone and in the final step, substitute xylene with air. The finished plastinated specimens were light-weight, dry, odourless and robust. This method requires less use of resin thus making the plastination technique more cost-effective. The light-weight specimens are easy to carry and can easily be used for teaching.

  9. Atom trap loss, elastic collisions, and technology

    NASA Astrophysics Data System (ADS)

    Booth, James

    2012-10-01

    The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

  10. Graphite filter atomizer in atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.

    2007-09-01

    Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.

  11. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  12. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  13. Electrochemical Atomic Layer Processing

    DTIC Science & Technology

    1994-06-25

    where an atomic layer of an element is deposited , or removed, in a surface limited reaction. The potentials used are referred to as underpotentials in...the electrochemical literature. The atomic layer deposition process is referred to as underpotential deposition (UPD). 14. SUBJECT TERMS 15, NUMBER OF...reaction. The potentials used are referred to as underpotentials in the electrochemical literature. The atomic layer deposition process is referred to as

  14. The Software Atom

    NASA Astrophysics Data System (ADS)

    Javanainen, Juha

    2017-03-01

    By putting together an abstract view on quantum mechanics and a quantum-optics picture of the interactions of an atom with light, we develop a corresponding set of C++ classes that set up the numerical analysis of an atom with an arbitrary set of angular-momentum degenerate energy levels, arbitrary light fields, and an applied magnetic field. As an example, we develop and implement perturbation theory to compute the polarizability of an atom in an experimentally relevant situation.

  15. Atomicity in Electronic Commerce,

    DTIC Science & Technology

    1996-01-01

    tremendous demand for the ability to electronically buy and sell goods over networks. Electronic commerce has inspired a large variety of work... commerce . It then briefly surveys some major types of electronic commerce pointing out flaws in atomicity. We pay special attention to the atomicity...problems of proposals for digital cash. The paper presents two examples of highly atomic electronic commerce systems: NetBill and Cryptographic Postage Indicia.

  16. Advances in atomic physics

    PubMed Central

    El-Sherbini, Tharwat M.

    2013-01-01

    In this review article, important developments in the field of atomic physics are highlighted and linked to research works the author was involved in himself as a leader of the Cairo University – Atomic Physics Group. Starting from the late 1960s – when the author first engaged in research – an overview is provided of the milestones in the fascinating landscape of atomic physics. PMID:26425356

  17. Atomic Oxygen Effects

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K. R.

    2014-01-01

    Atomic oxygen, which is the most predominant species in low Earth orbit, is highly reactive and can break chemical bonds on the surface of a wide variety of materials leading to volatilization or surface oxidation which can result in failure of spacecraft materials and components. This presentation will give an overview of how atomic oxygen reacts with spacecraft materials, results of space exposure testing of a variety of materials, and examples of failures caused by atomic oxygen.

  18. Preventing Weight Gain

    MedlinePlus

    ... body composition gradually shifts — the proportion of muscle decreases and the proportion of fat increases. This shift slows their metabolism, making it easier to gain weight. In addition, some people become less physically ...

  19. Your Child's Weight

    MedlinePlus

    ... spurts in height and weight gain in both boys and girls. Once these changes start, they continue for several ... or obese . Different BMI charts are used for boys and girls under the age of 20 because the amount ...

  20. Weight in Diabetes

    PubMed Central

    Kenshole, Anne B.

    1972-01-01

    Diabetes is being increasingly detected among the overweight. The author discusses the links between diabetes and obesity, and outlines methods by which satisfactory weight reduction may be achieved. PMID:20468726

  1. Prizes for weight loss.

    PubMed Central

    Englberger, L.

    1999-01-01

    A programme of weight loss competitions and associated activities in Tonga, intended to combat obesity and the noncommunicable diseases linked to it, has popular support and the potential to effect significant improvements in health. PMID:10063662

  2. Improved graphite furnace atomizer

    DOEpatents

    Siemer, D.D.

    1983-05-18

    A graphite furnace atomizer for use in graphite furnace atomic absorption spectroscopy is described wherein the heating elements are affixed near the optical path and away from the point of sample deposition, so that when the sample is volatilized the spectroscopic temperature at the optical path is at least that of the volatilization temperature, whereby analyteconcomitant complex formation is advantageously reduced. The atomizer may be elongated along its axis to increase the distance between the optical path and the sample deposition point. Also, the atomizer may be elongated along the axis of the optical path, whereby its analytical sensitivity is greatly increased.

  3. Magnetic measurements with atomic-plane resolution

    PubMed Central

    Rusz, Ján; Muto, Shunsuke; Spiegelberg, Jakob; Adam, Roman; Tatsumi, Kazuyoshi; Bürgler, Daniel E.; Oppeneer, Peter M.; Schneider, Claus M.

    2016-01-01

    Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide. PMID:27578421

  4. Magnetic measurements with atomic-plane resolution

    NASA Astrophysics Data System (ADS)

    Rusz, Ján; Muto, Shunsuke; Spiegelberg, Jakob; Adam, Roman; Tatsumi, Kazuyoshi; Bürgler, Daniel E.; Oppeneer, Peter M.; Schneider, Claus M.

    2016-08-01

    Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide.

  5. Solid Hydrogen Formed for Atomic Propellants

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan A.

    2000-01-01

    Several experiments on the formation of solid hydrogen particles in liquid helium were recently conducted at the NASA Glenn Research Center at Lewis Field. The solid hydrogen experiments are the first step toward seeing these particles and determining their shape and size. The particles will ultimately store atoms of boron, carbon, or hydrogen, forming an atomic propellant. Atomic propellants will allow rocket vehicles to carry payloads many times heavier than possible with existing rockets or allow them to be much smaller and lighter. Solid hydrogen particles are preferred for storing atoms. Hydrogen is generally an excellent fuel with a low molecular weight. Very low temperature hydrogen particles (T < 4 K) can prevent the atoms from recombining, making it possible for their lifetime to be controlled. Also, particles that are less than 1 mm in diameter are preferred because they can flow easily into a pipe when suspended in liquid helium. The particles and atoms must remain at this low temperature until the fuel is introduced into the engine combustion (or recombination) chamber. Experiments were, therefore, planned to look at the particles and observe their formation and any changes while in liquid helium.

  6. Atomic hydrogen as a launch vehicle propellant

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan A.

    1990-01-01

    An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb (sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 1b(sub f)/s/lb(sub m) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

  7. Nonlinear atom interferometer surpasses classical precision limit.

    PubMed

    Gross, C; Zibold, T; Nicklas, E; Estève, J; Oberthaler, M K

    2010-04-22

    Interference is fundamental to wave dynamics and quantum mechanics. The quantum wave properties of particles are exploited in metrology using atom interferometers, allowing for high-precision inertia measurements. Furthermore, the state-of-the-art time standard is based on an interferometric technique known as Ramsey spectroscopy. However, the precision of an interferometer is limited by classical statistics owing to the finite number of atoms used to deduce the quantity of interest. Here we show experimentally that the classical precision limit can be surpassed using nonlinear atom interferometry with a Bose-Einstein condensate. Controlled interactions between the atoms lead to non-classical entangled states within the interferometer; this represents an alternative approach to the use of non-classical input states. Extending quantum interferometry to the regime of large atom number, we find that phase sensitivity is enhanced by 15 per cent relative to that in an ideal classical measurement. Our nonlinear atomic beam splitter follows the 'one-axis-twisting' scheme and implements interaction control using a narrow Feshbach resonance. We perform noise tomography of the quantum state within the interferometer and detect coherent spin squeezing with a squeezing factor of -8.2 dB (refs 11-15). The results provide information on the many-particle quantum state, and imply the entanglement of 170 atoms.

  8. WEIGHT OF EVIDENCE IN ECOLOGICAL ASSESSMENT

    EPA Science Inventory

    This document provides guidance on methods for weighing ecological evidence using a a standard framework consisting of three steps: assemble evidence, weight evidence and weigh the body of evidence. Use of the methods will improve the consistency and reliability of WoE-based asse...

  9. Determination of equivalent weight of amines

    SciTech Connect

    Selig, W.S.

    1987-01-08

    A procedure for the determination of equivalent weight of amines is described. This procedure is based on an acid-base reaction performed in glacial acetic acid. The sum of primary, secondary, and tertiary amines are determined by titration with standard perchloric acid in glacial acetic acid. 1 ref.

  10. Nano-soldering to single atomic layer

    DOEpatents

    Girit, Caglar O.; Zettl, Alexander K.

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  11. Atomic Oxygen Fluence Monitor

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.

    2011-01-01

    This innovation enables a means for actively measuring atomic oxygen fluence (accumulated atoms of atomic oxygen per area) that has impinged upon spacecraft surfaces. Telemetered data from the device provides spacecraft designers, researchers, and mission managers with real-time measurement of atomic oxygen fluence, which is useful for prediction of the durability of spacecraft materials and components. The innovation is a compact fluence measuring device that allows in-space measurement and transmittance of measured atomic oxygen fluence as a function of time based on atomic oxygen erosion yields (the erosion yield of a material is the volume of material that is oxidized per incident oxygen atom) of materials that have been measured in low Earth orbit. It has a linear electrical response to atomic oxygen fluence, and is capable of measuring high atomic oxygen fluences (up to >10(exp 22) atoms/sq cm), which are representative of multi-year low-Earth orbital missions (such as the International Space Station). The durability or remaining structural lifetime of solar arrays that consist of polymer blankets on which the solar cells are attached can be predicted if one knows the atomic oxygen fluence that the solar array blanket has been exposed to. In addition, numerous organizations that launch space experiments into low-Earth orbit want to know the accumulated atomic oxygen fluence that their materials or components have been exposed to. The device is based on the erosion yield of pyrolytic graphite. It uses two 12deg inclined wedges of graphite that are over a grit-blasted fused silica window covering a photodiode. As the wedges erode, a greater area of solar illumination reaches the photodiode. A reference photodiode is also used that receives unobstructed solar illumination and is oriented in the same direction as the pyrolytic graphite covered photodiode. The short-circuit current from the photodiodes is measured and either sent to an onboard data logger, or

  12. Evanescent Wave Atomic Mirror

    NASA Astrophysics Data System (ADS)

    Ghezali, S.; Taleb, A.

    2008-09-01

    A research project at the "Laboratoire d'électronique quantique" consists in a theoretical study of the reflection and diffraction phenomena via an atomic mirror. This poster presents the principle of an atomic mirror. Many groups in the world have constructed this type of atom optics experiments such as in Paris-Orsay-Villetaneuse (France), Stanford-Gaithersburg (USA), Munich-Heidelberg (Germany), etc. A laser beam goes into a prism with an incidence bigger than the critical incidence. It undergoes a total reflection on the plane face of the prism and then exits. The transmitted resulting wave out of the prism is evanescent and repulsive as the frequency detuning of the laser beam compared to the atomic transition δ = ωL-ω0 is positive. The cold atomic sample interacts with this evanescent wave and undergoes one or more elastic bounces by passing into backward points in its trajectory because the atoms' kinetic energy (of the order of the μeV) is less than the maximum of the dipolar potential barrier ℏΩ2/Δ where Ω is the Rabi frequency [1]. In fact, the atoms are cooled and captured in a magneto-optical trap placed at a distance of the order of the cm above the prism surface. The dipolar potential with which interact the slow atoms is obtained for a two level atom in a case of a dipolar electric transition (D2 Rubidium transition at a wavelength of 780nm delivered by a Titane-Saphir laser between a fundamental state Jf = l/2 and an excited state Je = 3/2). This potential is corrected by an attractive Van der Waals term which varies as 1/z3 in the Lennard-Jones approximation (typical atomic distance of the order of λ0/2π where λ0 is the laser wavelength) and in 1/z4 if the distance between the atom and its image in the dielectric is big in front of λ0/2π. This last case is obtained in a quantum electrodynamic calculation by taking into account an orthornormal base [2]. We'll examine the role of spontaneous emission for which the rate is inversely

  13. Electron - Atom Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Kim, Longhuan

    In this work we study the features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point Coulomb potential and screened potentials are obtained using a classical numerical method. The results agree with exact quantum mechanical partial wave results for low incident electron energies in both the point Coulomb and screened potentials. In the screened potential the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. We also studied the scaling properties of bremsstrahlung spectra and energy losses. It is found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T(,1)/Z('2). This scaling is exact in the case of the point Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. We also studied bremsstrahlung from atoms in hot dense plasmas, describing the atomic potentials by the temperature-and-density dependent Thomas - Fermi model. Gaunt factors are obtained with the relativistic partial wave method for atoms in plasmas of various densities and temperatures. Features of the bremsstrahlung from atoms in such environments are discussed. The dependence of predicted bremsstrahlung spectra on the choice of potential from various average atom potential models for strongly coupled plasmas are also studied. For the energy range and plasma densities were considered, the choice of potential model among the elaborate atomic potentials is less important than the choice of the method of calculation. The use of a detailed configuration accounting method for bremsstrahlung processes in dense plasmas is less important than for some other atomic processes. We justify the usefulness

  14. Quantum Teleportation of High-dimensional Atomic Momenta State

    NASA Astrophysics Data System (ADS)

    Qurban, Misbah; Abbas, Tasawar; Rameez-ul-Islam; Ikram, Manzoor

    2016-06-01

    Atomic momenta states of the neutral atoms are known to be decoherence resistant and therefore present a viable solution for most of the quantum information tasks including the quantum teleportation. We present a systematic protocol for the teleportation of high-dimensional quantized momenta atomic states to the field state inside the cavities by applying standard cavity QED techniques. The proposal can be executed under prevailing experimental scenario.

  15. Accurate atom-mapping computation for biochemical reactions.

    PubMed

    Latendresse, Mario; Malerich, Jeremiah P; Travers, Mike; Karp, Peter D

    2012-11-26

    The complete atom mapping of a chemical reaction is a bijection of the reactant atoms to the product atoms that specifies the terminus of each reactant atom. Atom mapping of biochemical reactions is useful for many applications of systems biology, in particular for metabolic engineering where synthesizing new biochemical pathways has to take into account for the number of carbon atoms from a source compound that are conserved in the synthesis of a target compound. Rapid, accurate computation of the atom mapping(s) of a biochemical reaction remains elusive despite significant work on this topic. In particular, past researchers did not validate the accuracy of mapping algorithms. We introduce a new method for computing atom mappings called the minimum weighted edit-distance (MWED) metric. The metric is based on bond propensity to react and computes biochemically valid atom mappings for a large percentage of biochemical reactions. MWED models can be formulated efficiently as Mixed-Integer Linear Programs (MILPs). We have demonstrated this approach on 7501 reactions of the MetaCyc database for which 87% of the models could be solved in less than 10 s. For 2.1% of the reactions, we found multiple optimal atom mappings. We show that the error rate is 0.9% (22 reactions) by comparing these atom mappings to 2446 atom mappings of the manually curated Kyoto Encyclopedia of Genes and Genomes (KEGG) RPAIR database. To our knowledge, our computational atom-mapping approach is the most accurate and among the fastest published to date. The atom-mapping data will be available in the MetaCyc database later in 2012; the atom-mapping software will be available within the Pathway Tools software later in 2012.

  16. Weight Loss Nutritional Supplements

    NASA Astrophysics Data System (ADS)

    Eckerson, Joan M.

    Obesity has reached what may be considered epidemic proportions in the United States, not only for adults but for children. Because of the medical implications and health care costs associated with obesity, as well as the negative social and psychological impacts, many individuals turn to nonprescription nutritional weight loss supplements hoping for a quick fix, and the weight loss industry has responded by offering a variety of products that generates billions of dollars each year in sales. Most nutritional weight loss supplements are purported to work by increasing energy expenditure, modulating carbohydrate or fat metabolism, increasing satiety, inducing diuresis, or blocking fat absorption. To review the literally hundreds of nutritional weight loss supplements available on the market today is well beyond the scope of this chapter. Therefore, several of the most commonly used supplements were selected for critical review, and practical recommendations are provided based on the findings of well controlled, randomized clinical trials that examined their efficacy. In most cases, the nutritional supplements reviewed either elicited no meaningful effect or resulted in changes in body weight and composition that are similar to what occurs through a restricted diet and exercise program. Although there is some evidence to suggest that herbal forms of ephedrine, such as ma huang, combined with caffeine or caffeine and aspirin (i.e., ECA stack) is effective for inducing moderate weight loss in overweight adults, because of the recent ban on ephedra manufacturers must now use ephedra-free ingredients, such as bitter orange, which do not appear to be as effective. The dietary fiber, glucomannan, also appears to hold some promise as a possible treatment for weight loss, but other related forms of dietary fiber, including guar gum and psyllium, are ineffective.

  17. Atomic Power Safety.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is one of a series of information booklets for the general public published by The United States Atomic Energy Commission. Among the topics discussed are: What is Atomic Power?; What Does Safety Depend On?; Control of Radioactive Material During Operation; Accident Prevention; Containment in the Event of an Accident; Licensing and…

  18. When Atoms Want

    ERIC Educational Resources Information Center

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  19. Neutrino-atom collisions

    NASA Astrophysics Data System (ADS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2016-05-01

    Neutrino-atom scattering provides a sensitive tool for probing nonstandard interactions of massive neutrinos in laboratory measurements. The ionization channel of this collision process plays an important role in experiments searching for neutrino magnetic moments. We discuss some theoretical aspects of atomic ionization by massive neutrinos. We also outline possible manifestations of neutrino electromagnetic properties in coherent elastic neutrino-nucleus scattering.

  20. Atom Interferometer Modeling Tool

    DTIC Science & Technology

    2011-08-08

    a specific value at each timestep . LiveAtom will reflect the specified current sources in the visualization through a plot that is brighter at 6...Carlo (DSMC) modeling feature, users can simulate the behavior of cold, thermal atoms in a dynamic magnetic potential. This could be used, for example

  1. Greek Atomic Theory.

    ERIC Educational Resources Information Center

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  2. Atomic Scale Plasmonic Switch.

    PubMed

    Emboras, Alexandros; Niegemann, Jens; Ma, Ping; Haffner, Christian; Pedersen, Andreas; Luisier, Mathieu; Hafner, Christian; Schimmel, Thomas; Leuthold, Juerg

    2016-01-13

    The atom sets an ultimate scaling limit to Moore's law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocation of an individual or, at most, a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ratio of 9.2 dB and operation at room temperature up to MHz with femtojoule (fJ) power consumption for a single switch operation. This demonstration of an integrated quantum device allowing to control photons at the atomic level opens intriguing perspectives for a fully integrated and highly scalable chip platform, a platform where optics, electronics, and memory may be controlled at the single-atom level.

  3. Modified Embedded Atom Method

    SciTech Connect

    Rudd, R. E.

    2012-08-01

    Interatomic force and energy calculation subroutine to be used with the molecular dynamics simulation code LAMMPS (Ref a.). The code evaluated the total energy and atomic forces (energy gradient) according to a cubic spline-based variant (Ref b.) of the Modified Embedded Atom Method (MEAM) with a additional Stillinger-Weber (SW) contribution.

  4. Atom Recombination on Surface

    NASA Astrophysics Data System (ADS)

    Kim, Young Chai

    Upon high speed re-entry of the Space Shuttle Orbiter (SSO) through the earth's atmosphere, oxygen and nitrogen atoms produced in the shock wave in front of the SSO recombine on the surface of the SSO, releasing heat. To minimize the rise of surface temperature due to the reaction, surface material of the SSO should have a low recombination probability, gamma, of atoms impinging on it. To design such material, it is necessary to understand the mechanism of atom recombination. With this in mind, gamma values were measured for recombination of O, N, and H atoms in a diffusion tube reactor between 700 and 1250 K (HT), 300 and 700 K (MT), and at 194 K (LT) on silica. The rate of recombination was first order with respect to the atom concentration from LT to HT. The Arrhenius plots, gamma vs. 1/T, were very complex. All observations are explained by assuming a surface with a small fraction of active sites that irreversibly bind chemisorbed atoms. Everything happens as if the active sites were surrounded by collection zones within which all atoms striking the surface are adsorbed reversibly with an assumed sticking probability of unity. These atoms then diffuse on the surface. Some of them reach the active sites where they can recombine with the chemisorbed atoms. At LT, all atoms striking the surface reach the active sites. As a result of desorption at MT, the collection zones shrink with increasing temperature. At HT, only atoms striking active sites directly from the gas phase lead to recombination. An analytical solution of the diffusion-reaction problem obtained for a model where the active sites are distributed uniformly fits with the experimental data from LT to HT. The two novel features of this work are the identification of the active sites on silica for recombination of H on silica at HT as surface OH groups and the suggestion that another kind of active site is responsible for recombination of O and N atoms at HT as well as for H atoms at LT and MT. Although

  5. Popular weight reduction diets.

    PubMed

    Volpe, Stella Lucia

    2006-01-01

    The percentage of people who are overweight and obese has increased tremendously over the last 30 years. It has become a worldwide epidemic. This is evident by the number of children are being diagnosed with a body mass index >85th percentile, and the number of children begin diagnosed with type 2 diabetes mellitus, a disease previously reserved for adults. The weight loss industry has also gained from this epidemic; it is a billion dollar industry. People pay large sums of money on diet pills, remedies, and books, with the hope of losing weight permanently. Despite these efforts, the number of individuals who are overweight or obese continues to increase. Obesity is a complex, multifactorial disorder. It would be impossible to address all aspects of diet, exercise, and weight loss in this review. Therefore, this article will review popular weight loss diets, with particular attention given to comparing low fat diets with low carbohydrate diets. In addition, the role that the environment plays on both diet and exercise and how they impact obesity will be addressed. Finally, the National Weight Control Registry will be discussed.

  6. Reciprocity of weighted networks

    PubMed Central

    Squartini, Tiziano; Picciolo, Francesco; Ruzzenenti, Franco; Garlaschelli, Diego

    2013-01-01

    In directed networks, reciprocal links have dramatic effects on dynamical processes, network growth, and higher-order structures such as motifs and communities. While the reciprocity of binary networks has been extensively studied, that of weighted networks is still poorly understood, implying an ever-increasing gap between the availability of weighted network data and our understanding of their dyadic properties. Here we introduce a general approach to the reciprocity of weighted networks, and define quantities and null models that consistently capture empirical reciprocity patterns at different structural levels. We show that, counter-intuitively, previous reciprocity measures based on the similarity of mutual weights are uninformative. By contrast, our measures allow to consistently classify different weighted networks according to their reciprocity, track the evolution of a network's reciprocity over time, identify patterns at the level of dyads and vertices, and distinguish the effects of flux (im)balances or other (a)symmetries from a true tendency towards (anti-)reciprocation. PMID:24056721

  7. Coaxial airblast atomizers

    NASA Technical Reports Server (NTRS)

    Hardalupas, Y.; Whitelaw, J. H.

    1993-01-01

    An experimental investigation was performed to quantify the characteristics of the sprays of coaxial injectors with particular emphasis on those aspects relevant to the performance of rocket engines. Measurements for coaxial air blast atomizers were obtained using air to represent the gaseous stream and water to represent the liquid stream. A wide range of flow conditions were examined for sprays with and without swirl for gaseous streams. The parameters varied include Weber number, gas flow rate, liquid flow rate, swirl, and nozzle geometry. Measurements were made with a phase Doppler velocimeter. Major conclusions of the study focused upon droplet size as a function of Weber number, effect of gas flow rate on atomization and spray spread, effect of nozzle geometry on atomization and spread, effect of swirl on atomization, spread, jet recirculation and breakup, and secondary atomization.

  8. Atomic Oxygen Textured Polymers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Hunt, Jason D.; Drobotij, Erin; Cales, Michael R.; Cantrell, Gidget

    1995-01-01

    Atomic oxygen can be used to microscopically alter the surface morphology of polymeric materials in space or in ground laboratory facilities. For polymeric materials whose sole oxidation products are volatile species, directed atomic oxygen reactions produce surfaces of microscopic cones. However, isotropic atomic oxygen exposure results in polymer surfaces covered with lower aspect ratio sharp-edged craters. Isotropic atomic oxygen plasma exposure of polymers typically causes a significant decrease in water contact angle as well as altered coefficient of static friction. Such surface alterations may be of benefit for industrial and biomedical applications. The results of atomic oxygen plasma exposure of thirty-three (33) different polymers are presented, including typical morphology changes, effects on water contact angle, and coefficient of static friction.

  9. Calf stretching in non-weight bearing versus weight bearing.

    PubMed

    Dinh, N V; Freeman, H; Granger, J; Wong, S; Johanson, M

    2011-03-01

    Limited ankle dorsiflexion passive range of motion (DF PROM) has been associated with lower extremity overuse injuries. Therefore, clinicians often prescribe stretching exercises to increase ankle DF PROM. However, there is limited evidence to indicate if any particular gastrocnemius stretching exercise results in greater improvement in DF PROM. The aim of this study was to determine if gastrocnemius stretching in non-weight bearing (NWB) or weight bearing (WB) results in a greater increase of ankle DF PROM. 28 healthy volunteers, aged 18-55 years, who exhibited less than 10 degrees of ankle DF PROM completed the study. Participants were randomized into 2 stretching groups: NWB and WB. Both groups completed a 3-week home gastrocnemius stretching program, consisting of 5 repetitions held for 30 s each, 2 times daily. Participants' ankle DF PROM was measured with a blinded standard goniometer in NWB and WB positions before and after participation in a 3-week home gastrocnemius stretching program. Two 3-way mixed model ANOVAs demonstrated no significant difference in ankle DF PROM between the NWB and WB groups for either the NWB measurement condition (p=0.49) or WB measurement condition (p=0.86). Gastrocnemius stretching exercises performed in NWB or WB were equally effective in increasing ankle DF PROM.

  10. Telemetry Standards

    DTIC Science & Technology

    1996-05-01

    A-18 A-8 Unfiltered 1000 kbps RNRZ PCM/FM signal and spectral mask A-18 A-9 1000 kbps OQPSK signal (sinusoidal weighting) and spectral mask A...test NPR noise power ratio NPRF noise power ratio floor NRZ-L non return to zero-level OQPSK oflset quadrature phase shift keying PBOT physical...QPSK), no filter 9.65 fi Offset QPSK ( OQPSK ), sinusoidal weighting 1.18 fi 5.2.2 -25 dBm Bandwidth. The bandwidth beyond which all power levels are

  11. Training Standardization

    SciTech Connect

    Agnihotri, Newal

    2003-09-01

    The article describes the benefits of and required process and recommendations for implementing the standardization of training in the nuclear power industry in the United States and abroad. Current Information and Communication Technologies (ICT) enable training standardization in the nuclear power industry. The delivery of training through the Internet, Intranet and video over IP will facilitate this standardization and bring multiple benefits to the nuclear power industry worldwide. As the amount of available qualified and experienced professionals decreases because of retirements and fewer nuclear engineering institutions, standardized training will help increase the number of available professionals in the industry. Technology will make it possible to use the experience of retired professionals who may be interested in working part-time from a remote location. Well-planned standardized training will prevent a fragmented approach among utilities, and it will save the industry considerable resources in the long run. It will also ensure cost-effective and safe nuclear power plant operation.

  12. Atom Probe Tomography of Geomaterials

    NASA Astrophysics Data System (ADS)

    Parman, S. W.; Diercks, D.; Gorman, B.; Cooper, R. F.

    2013-12-01

    From the electron microprobe to the secondary ion microprobe to laser-ablation ICP-MS, steady improvements in the spatial resolution and detection limits of geochemical micro-analysis have been central to generating new discoveries. Atom probe tomography (APT) is a relatively new technology that promises nm-scale spatial resolution (in three dimensions) with ppm level detection limits. The method is substantially different from traditional beam-based (electron, ion, laser) methods. In APT, the sample is shaped (usually with a dual-beam FIB) into a needle with typical dimensions of 1-2 μm height and 100-200 nm diameter. Within the atom probe, the needle is evaporated one atom (ideally) at a time by a high electric field (ten's of V per square nm at the needle tip). A femtosecond laser (12 ps pulse width) is used to assist in evaporating non-conducting samples. The two-dimensional detector locates where the atom was released from the needle's surface and so can reconstruct the positions of all detected atoms in three dimensions. It also records the time of flight of the ion, which is used to calculate the mass/charge ratio of the ion. We will discuss our results analyzing a range of geologic materials. In one case, naturally occurring platinum group alloys (PGA) from the Josephine Ophiolite have been imaged. Such alloys are of interest as recorders of the Os heterogeneity of the mantle [1,2]. Optimal ablation was achieved with a laser power of 120-240 pJ and laser pulse rates 500 kHz. Runs were stopped after 10 million atoms were imaged. An example analysis is: Pt 61(1), Fe 26.1(9), Rh 1.20(4), Ir 7.0(7), Ni 2.65(8), Ru 0.20(9), Cu 1.22(8), Co 0.00029(5). Values are in atomic %; values in parentheses are one-sigma standard deviations on five separate needles from the same FIB lift-out, which was 30 μm long. Assuming the sample is homogenous over the 30 μm from which the needle was extracted, the analyses suggest relative errors for major elements below 5% and for

  13. Light weight phosphate cements

    DOEpatents

    Wagh, Arun S.; Natarajan, Ramkumar,; Kahn, David

    2010-03-09

    A sealant having a specific gravity in the range of from about 0.7 to about 1.6 for heavy oil and/or coal bed methane fields is disclosed. The sealant has a binder including an oxide or hydroxide of Al or of Fe and a phosphoric acid solution. The binder may have MgO or an oxide of Fe and/or an acid phosphate. The binder is present from about 20 to about 50% by weight of the sealant with a lightweight additive present in the range of from about 1 to about 10% by weight of said sealant, a filler, and water sufficient to provide chemically bound water present in the range of from about 9 to about 36% by weight of the sealant when set. A porous ceramic is also disclosed.

  14. Generalized constructive tree weights

    SciTech Connect

    Rivasseau, Vincent E-mail: adrian.tanasa@ens-lyon.org; Tanasa, Adrian E-mail: adrian.tanasa@ens-lyon.org

    2014-04-15

    The Loop Vertex Expansion (LVE) is a quantum field theory (QFT) method which explicitly computes the Borel sum of Feynman perturbation series. This LVE relies in a crucial way on symmetric tree weights which define a measure on the set of spanning trees of any connected graph. In this paper we generalize this method by defining new tree weights. They depend on the choice of a partition of a set of vertices of the graph, and when the partition is non-trivial, they are no longer symmetric under permutation of vertices. Nevertheless we prove they have the required positivity property to lead to a convergent LVE; in fact we formulate this positivity property precisely for the first time. Our generalized tree weights are inspired by the Brydges-Battle-Federbush work on cluster expansions and could be particularly suited to the computation of connected functions in QFT. Several concrete examples are explicitly given.

  15. Fractional dissipative standard map.

    PubMed

    Tarasov, Vasily E; Edelman, M

    2010-06-01

    Using kicked differential equations of motion with derivatives of noninteger orders, we obtain generalizations of the dissipative standard map. The main property of these generalized maps, which are called fractional maps, is long-term memory. The memory effect in the fractional maps means that their present state of evolution depends on all past states with special forms of weights. Already a small deviation of the order of derivative from the integer value corresponding to the regular dissipative standard map (small memory effects) leads to the qualitatively new behavior of the corresponding attractors. The fractional dissipative standard maps are used to demonstrate a new type of fractional attractors in the wide range of the fractional orders of derivatives.

  16. Weighted Uncertainty Relations

    PubMed Central

    Xiao, Yunlong; Jing, Naihuan; Li-Jost, Xianqing; Fei, Shao-Ming

    2016-01-01

    Recently, Maccone and Pati have given two stronger uncertainty relations based on the sum of variances and one of them is nontrivial when the quantum state is not an eigenstate of the sum of the observables. We derive a family of weighted uncertainty relations to provide an optimal lower bound for all situations and remove the restriction on the quantum state. Generalization to multi-observable cases is also given and an optimal lower bound for the weighted sum of the variances is obtained in general quantum situation. PMID:26984295

  17. Average Weighted Receiving Time of Weighted Tetrahedron Koch Networks

    NASA Astrophysics Data System (ADS)

    Dai, Meifeng; Zhang, Danping; Ye, Dandan; Zhang, Cheng; Li, Lei

    2015-07-01

    We introduce weighted tetrahedron Koch networks with infinite weight factors, which are generalization of finite ones. The term of weighted time is firstly defined in this literature. The mean weighted first-passing time (MWFPT) and the average weighted receiving time (AWRT) are defined by weighted time accordingly. We study the AWRT with weight-dependent walk. Results show that the AWRT for a nontrivial weight factor sequence grows sublinearly with the network order. To investigate the reason of sublinearity, the average receiving time (ART) for four cases are discussed.

  18. Relationships between heart score, heart weight and body weight in Greyhound dogs.

    PubMed

    Steel, J D; Taylor, R I; Davis, P E; Stewart, G A; Salmon, P W

    1976-12-01

    The aim of this study was to determine the relationships between heart score (mean QRS interval), heart weight and body weight in Greyhound dogs. Highly significant correlations between these measurements have been observed and distinct sex differences have been demonstrated. The results of multiple regression analysis indicated that 66% of the variation in heart weight was due to variation in heart score and body weight. From the regression analysis, a formula for heart weight prediction with a standard deviation of 27.1 g was derived. The implications of these findings have been discussed briefly and emphasis has been placed on the need for good electrocardiographic technique, if the procedures outlined are to be used successfully. The positive correlation between heart score and heart size demonstrated here in Greyhounds is in accord with similar correlations reported previously in racehorses and human athletes.

  19. 78 FR 58571 - Maine Yankee Atomic Power Company, Connecticut Yankee Atomic Power Company, and The Yankee Atomic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-24

    ... Atomic Power Company, Connecticut Yankee Atomic Power Company, and The Yankee Atomic Electric Company... Power Company (Maine Yankee), Connecticut Yankee Atomic Power Company (Connecticut Yankee), and the Yankee Atomic Electric Company (Yankee Atomic) (together, ``licensees'' or ``the Yankee Companies'')...

  20. Diet for rapid weight loss

    MedlinePlus

    ... diet; VLCD; Low-calorie diet; LCD; Very low energy diet; Weight loss - rapid weight loss; Overweight - rapid ... AM, Aveyard P. Clinical effectiveness of very-low-energy diets in the management of weight loss: a ...

  1. Weight and Diabetes (For Parents)

    MedlinePlus

    ... your child lose weight to control diabetes, a weight management plan may be created. Even if your child's ... overweight, talk to your doctor about beginning a weight management program so you can set a good example. ...

  2. Brief report: Weight dissatisfaction, weight status, and weight loss in Mexican-American children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study objectives were to assess the association between weight dissatisfaction, weight status, and weight loss in Mexican-American children participating in a weight management program. Participants included 265 Mexican American children recruited for a school-based weight management program. Al...

  3. Bessel Weighted Asymmetries

    SciTech Connect

    Avakian, Harut; Gamberg, Leonard; Rossi, Patrizia; Prokudin, Alexei

    2016-05-01

    We review the concept of Bessel weighted asymmetries for semi-inclusive deep inelastic scattering and focus on the cross section in Fourier space, conjugate to the outgoing hadron’s transverse momentum, where convolutions of transverse momentum dependent parton distribution functions and fragmentation functions become simple products. Individual asymmetric terms in the cross section can be projected out by means of a generalized set of weights involving Bessel functions. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Monte Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy and hard scale Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.

  4. Strengthening Weight Rooms.

    ERIC Educational Resources Information Center

    Sherman, Rachel M.

    1997-01-01

    Examines ways of giving an existing weight-training room new life without spending a lot of time and money. Tips include adding rubber floor coverings; using indirect lighting; adding windows, art work, or mirrors to open up the room; using more aesthetically pleasing ceiling tiles; upgrading ventilation; repadding or painting the equipment; and…

  5. Involuntary weight loss.

    PubMed

    Wong, Christopher J

    2014-05-01

    Involuntary weight loss remains an important and challenging clinical problem, with a high degree of morbidity and mortality. Because of the frequency of finding a serious underlying diagnosis, clinicians must be thorough in assessment, keeping in mind a broad range of possible causes. Although prediction scores exist, they have not been broadly validated; therefore, clinical judgment remains ever essential.

  6. Weight Training Adds Up.

    ERIC Educational Resources Information Center

    Nutter, June

    1995-01-01

    Secondary level physical education teachers can have their students use math concepts while working out on the weight-room equipment. The article explains how students can reinforce math skills while weightlifting by estimating their strength, estimating their power, or calculating other formulas. (SM)

  7. Weight-loss medications

    MedlinePlus

    ... term use. All other drugs are approved for short-term use of no more than a few weeks. Be sure you understand the side effects of weight-loss medicines. Side effects can include: Increase in blood pressure Problems sleeping, headache, nervousness, and palpitations Nausea, constipation, and dry ...

  8. Dynamic Weighted Data Structures.

    DTIC Science & Technology

    1982-06-01

    van "j Beethoven, Igor Stravinsky, Glan-Carlo Menotti, and Johann Sebastian Bach . Dynamic Weighted Data Structures Samuel W. Bent This thesis discusses...and Bonnie Hampton, who taught me much more than how to play the cello. Finally, for hours of artistic satisfaction, I thank Johannes Brahms, Ludwig

  9. Weighted Multiplex Networks

    PubMed Central

    Menichetti, Giulia; Remondini, Daniel; Panzarasa, Pietro; Mondragón, Raúl J.; Bianconi, Ginestra

    2014-01-01

    One of the most important challenges in network science is to quantify the information encoded in complex network structures. Disentangling randomness from organizational principles is even more demanding when networks have a multiplex nature. Multiplex networks are multilayer systems of nodes that can be linked in multiple interacting and co-evolving layers. In these networks, relevant information might not be captured if the single layers were analyzed separately. Here we demonstrate that such partial analysis of layers fails to capture significant correlations between weights and topology of complex multiplex networks. To this end, we study two weighted multiplex co-authorship and citation networks involving the authors included in the American Physical Society. We show that in these networks weights are strongly correlated with multiplex structure, and provide empirical evidence in favor of the advantage of studying weighted measures of multiplex networks, such as multistrength and the inverse multiparticipation ratio. Finally, we introduce a theoretical framework based on the entropy of multiplex ensembles to quantify the information stored in multiplex networks that would remain undetected if the single layers were analyzed in isolation. PMID:24906003

  10. Epitaxy: Programmable Atom Equivalents Versus Atoms.

    PubMed

    Wang, Mary X; Seo, Soyoung E; Gabrys, Paul A; Fleischman, Dagny; Lee, Byeongdu; Kim, Youngeun; Atwater, Harry A; Macfarlane, Robert J; Mirkin, Chad A

    2017-01-24

    The programmability of DNA makes it an attractive structure-directing ligand for the assembly of nanoparticle (NP) superlattices in a manner that mimics many aspects of atomic crystallization. However, the synthesis of multilayer single crystals of defined size remains a challenge. Though previous studies considered lattice mismatch as the major limiting factor for multilayer assembly, thin film growth depends on many interlinked variables. Here, a more comprehensive approach is taken to study fundamental elements, such as the growth temperature and the thermodynamics of interfacial energetics, to achieve epitaxial growth of NP thin films. Both surface morphology and internal thin film structure are examined to provide an understanding of particle attachment and reorganization during growth. Under equilibrium conditions, single crystalline, multilayer thin films can be synthesized over 500 × 500 μm(2) areas on lithographically patterned templates, whereas deposition under kinetic conditions leads to the rapid growth of glassy films. Importantly, these superlattices follow the same patterns of crystal growth demonstrated in atomic thin film deposition, allowing these processes to be understood in the context of well-studied atomic epitaxy and enabling a nanoscale model to study fundamental crystallization processes. Through understanding the role of epitaxy as a driving force for NP assembly, we are able to realize 3D architectures of arbitrary domain geometry and size.

  11. Atom trap trace analysis

    SciTech Connect

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O'Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  12. Atomic and molecular supernovae

    NASA Technical Reports Server (NTRS)

    Liu, Weihong

    1997-01-01

    Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

  13. Primary cesium time and frequency standards

    SciTech Connect

    Abashev, Yu.G.; Elkin, G.A.; Pushkin, S.B.

    1984-05-01

    Cesium frequency standards are used to determine the atomic second in SI units and to provide a national atomic-time scale at the leading meteorological laboratories of the world. In this paper, the state of cesium and atomic frequency standards are examined and methods of increasing their accuracy are analyzed. High-purity polycrystals of platinum-iridium alloy or high-purity and structurally perfect single crystals of tungsten and molybdenum are used as ionizers in beam detection. Relative frequency instabilities that have been obtained at the various laboratories are presented. The main sources of error in reproducing the unperturbed-transition frequency of cesium atoms are discussed, including the second-order Doppler effect and the Majorana effect. Accuracy estimates for cesium frequency standards of the world's leading meteorological laboratories are shown.

  14. Active Faraday optical frequency standard.

    PubMed

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks.

  15. Physiological weight loss in the breastfed neonate: a systematic review

    PubMed Central

    Noel-Weiss, Joy; Courant, Genevieve; Woodend, A Kirsten

    2008-01-01

    Background Healthy, full-term, exclusively breastfed infants are expected to lose weight in the first days following birth. There are conflicting opinions about what constitutes a normal neonatal weight loss, and about when interventions such as supplemental feedings should be considered. Objective To establish the reference weight loss for the first 2 weeks following birth by conducting a systematic review of studies reporting birth weights of exclusively breastfed neonates. Methods We searched 5 electronic databases from June 2006 to June 2007: the Cochrane Database of Systematic Reviews; MEDLINE (from 1950); CINAHL (from 1982); EMBASE (from 1980); and Ovid HealthSTAR (from 1999). We included primary research studies with weight loss data for healthy, full-term, exclusively breastfed neonates in the first 2 weeks following birth. Results Eleven studies met the inclusion criteria. Definitions, types of measurements, and reporting styles varied among studies. In most studies, daily weights were not measured and measurements did not continue for 2 weeks. Mean weight loss ranged from 5.7% to 6.6%, with standard deviations around 2%. Median percentage weight loss ranged from 3.2 to 8.3, with the majority around 6%. The majority of infants in these 11 studies regained their birth weight within the first 2 weeks postpartum. The second and third days following birth appear to be the days of maximum weight loss. Discussion Methods used to report weight loss were inconsistent, using either an average of single lowest weights or a combination of weight losses. The 7% maximum allowable weight loss recommended in 4 clinical practice guidelines appears to be based on mean weight loss and does not account for standard deviation. Further research is needed to understand the causes of neonatal weight loss and its implications for morbidity and mortality. PMID:21602959

  16. EOS standards

    SciTech Connect

    Greeff, Carl W

    2011-01-12

    An approach to creating accurate EOS for pressure standards is described. Applications to Cu, Au, and Ta are shown. Extension of the method to high compressions using DFT is illustrated. Comparisons with modern functionals show promise.

  17. Networking standards

    NASA Technical Reports Server (NTRS)

    Davies, Mark

    1991-01-01

    The enterprise network is currently a multivendor environment consisting of many defacto and proprietary standards. During the 1990s, these networks will evolve towards networks which are based on international standards in both Local Area Network (LAN) and Wide Area Network (WAN) space. Also, you can expect to see the higher level functions and applications begin the same transition. Additional information is given in viewgraph form.

  18. 40 CFR 63.1362 - Standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Standards for Hazardous Air Pollutants for Pesticide Active Ingredient Production § 63.1362 Standards. (a... reduced by 90 percent or greater by weight. (iv) As an alternative to the requirements in paragraphs (b)(2...(a)(4); or (D) In accordance with the alternative standard specified in paragraph (b)(6) of...

  19. 40 CFR 63.1362 - Standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Standards for Hazardous Air Pollutants for Pesticide Active Ingredient Production § 63.1362 Standards. (a... reduced by 90 percent or greater by weight. (iv) As an alternative to the requirements in paragraphs (b)(2...(a)(4); or (D) In accordance with the alternative standard specified in paragraph (b)(6) of...

  20. (Terminology standardization)

    SciTech Connect

    Strehlow, R.A.

    1990-10-19

    Terminological requirements in information management was but one of the principal themes of the 2nd Congress on Terminology and Knowledge Engineering. The traveler represented the American Society for Testing and Materials' Committee on Terminology, of which he is the Chair. The traveler's invited workshop emphasized terminology standardization requirements in databases of material properties as well as practical terminology standardizing methods. The congress included six workshops in addition to approximately 82 lectures and papers from terminologists, artificial intelligence practitioners, and subject specialists from 18 countries. There were approximately 292 registrants from 33 countries who participated in the congress. The congress topics were broad. Examples were the increasing use of International Standards Organization (ISO) Standards in legislated systems such as the USSR Automated Data Bank of Standardized Terminology, the enhanced Physics Training Program based on terminology standardization in Physics in the Chinese province of Inner Mongolia, and the technical concept dictionary being developed at the Japan Electronic Dictionary Research Institute, which is considered to be the key to advanced artificial intelligence applications. The more usual roles of terminology work in the areas of machine translation. indexing protocols, knowledge theory, and data transfer in several subject specialties were also addressed, along with numerous special language terminology areas.

  1. A concentrated radioactive beam source for atom cooling and trapping

    SciTech Connect

    Maddi, J.; Dinneen, T.; Ghiorso, A.; Gould, H.

    1996-05-01

    The authors describe a novel oven to obtain concentrated beams of radioactive atoms. The Orthotropic oven works by ionizing atoms on its interior walls and electrostatically concentrating them on a neutralizer. Once neutralized the atoms can escape from the oven and form a narrow beam. Atoms that fail to escape become ionized again and repeat the cycle. The authors demonstrate the operation of this oven using {sup 221}Fr and compare both the theoretical and experimental efficiency of this source with standard effusive and channeled ovens.

  2. Parametric study of transport aircraft systems cost and weight

    NASA Technical Reports Server (NTRS)

    Beltramo, M. N.; Trapp, D. L.; Kimoto, B. W.; Marsh, D. P.

    1977-01-01

    The results of a NASA study to develop production cost estimating relationships (CERs) and weight estimating relationships (WERs) for commercial and military transport aircraft at the system level are presented. The systems considered correspond to the standard weight groups defined in Military Standard 1374 and are listed. These systems make up a complete aircraft exclusive of engines. The CER for each system (or CERs in several cases) utilize weight as the key parameter. Weights may be determined from detailed weight statements, if available, or by using the WERs developed, which are based on technical and performance characteristics generally available during preliminary design. The CERs that were developed provide a very useful tool for making preliminary estimates of the production cost of an aircraft. Likewise, the WERs provide a very useful tool for making preliminary estimates of the weight of aircraft based on conceptual design information.

  3. The Atomic Dating Game.

    ERIC Educational Resources Information Center

    Cummo, Evelyn; Matthews, Catherine E.

    2002-01-01

    Presents an activity designed to provide students with opportunities to practice drawing atomic models and discover the logical pairings of whole families on the periodic table. Follows the format of a television game show. (DDR)

  4. Atomic Bomb Health Benefits

    PubMed Central

    Luckey, T. D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation, leukemia and solid tissue cancer mortality rates, and increased average lifespan. Each study exhibits a threshold that repudiates the LNT dogma. The average threshold for acute exposures to atomic bombs is about 100 cSv. Conclusions from these studies of atomic bomb survivors are: One burst of low dose irradiation elicits a lifetime of improved health.Improved health from low dose irradiation negates the LNT paradigm.Effective triage should include radiation hormesis for survivor treatment. PMID:19088902

  5. Atomic bomb health benefits.

    PubMed

    Luckey, T D

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation, leukemia and solid tissue cancer mortality rates, and increased average lifespan. Each study exhibits a threshold that repudiates the LNT dogma. The average threshold for acute exposures to atomic bombs is about 100 cSv. Conclusions from these studies of atomic bomb survivors are: One burst of low dose irradiation elicits a lifetime of improved health.Improved health from low dose irradiation negates the LNT paradigm.Effective triage should include radiation hormesis for survivor treatment.

  6. Atomic & Molecular Interactions

    SciTech Connect

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  7. Improved Atomizer Resists Clogging

    NASA Technical Reports Server (NTRS)

    Dea, J. Y.

    1983-01-01

    Improved constant-output atomizer has conical orifice that permits air to sweep out all liquid thoroughly and prevent any buildup of liquid or dissolved solids. Capillary groove guides liquid to gas jet. Simple new design eliminates clogging.

  8. Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Saini, Subhash (Technical Monitor)

    1998-01-01

    Adatom chains, precise structures artificially created on an atomically regulated surface, are the smallest possible candidates for future nanoelectronics. Since all the devices are created by combining adatom chains precisely prepared with atomic precision, device characteristics are predictable, and free from deviations due to accidental structural defects. In this atomic dimension, however, an analogy to the current semiconductor devices may not work. For example, Si structures are not always semiconducting. Adatom states do not always localize at the substrate surface when adatoms form chemical bonds to the substrate atoms. Transport properties are often determined for the entire system of the chain and electrodes, and not for chains only. These fundamental issues are discussed, which will be useful for future device considerations.

  9. The Casimir atomic pendulum

    NASA Astrophysics Data System (ADS)

    Razmi, H.; Abdollahi, M.

    2008-11-01

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock!

  10. Anti-atoms: Gotcha!

    NASA Astrophysics Data System (ADS)

    Surko, Clifford M.

    2011-07-01

    Refined techniques to mix cold antiprotons and positrons in a magnetic bottle show that antihydrogen atoms can be trapped for 15 minutes -- an improvement of four orders of magnitude over previous experiments.

  11. Atom chip gravimeter

    NASA Astrophysics Data System (ADS)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

  12. Effect of Parent Weight on Weight Loss in Obese Children.

    ERIC Educational Resources Information Center

    Epstein, Leonard H.; And Others

    1986-01-01

    Assessed effect of parent weight and parent control versus child self-control on weight loss in obese preadolescent children over three-year period. Children of nonobese parents had significantly greater decrease in relative weight after one year than children of obese parents. At three years, there was no effect of parent weight. Locus of control…

  13. Bounds for weighted Lebesgue functions for exponential weights

    NASA Astrophysics Data System (ADS)

    Kubayi, D. G.

    2001-08-01

    The weighted Lebesgue functions for even weights W=e-Q on the real line have been intensively studied in recent years. In this paper, we discuss the corresponding results for a class of weights that includes non-even weights.

  14. Are early first trimester weights valid proxies for preconception weight?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An accurate estimate of preconception weight is necessary for providing a gestational weight gain range based on the Institute of Medicine’s guidelines; however, an accurate and proximal preconception weight is not available for most women. We examined the validity of first trimester weights for est...

  15. Sharing the atom bomb

    SciTech Connect

    Chace, J.

    1996-01-01

    Shaken by the devastation of Hiroshima and Nagasaki and fearful that the American atomic monopoly would spark an arms race, Dean Acheson led a push in 1946 to place the bomb-indeed, all atomic energy-under international control. But as the memories of wartime collaboration faded, relations between the superpowers grew increasingly tense, and the confrontational atmosphere undid his proposal. Had Acheson succeeded, the Cold War might not have been. 2 figs.

  16. Atomizing nozzle and method

    DOEpatents

    Ting, Jason; Anderson, Iver E.; Terpstra, Robert L.

    2000-03-16

    A high pressure close-coupled gas atomizing nozzle includes multiple discrete gas jet discharge orifices having aerodynamically designed convergent-divergent geometry with an first converging section communicated to a gas supply manifold and to a diverging section by a constricted throat section to increase atomizing gas velocity. The gas jet orifices are oriented at gas jet apex angle selected relative to the melt supply tip apex angle to establish a melt aspiration condition at the melt supply tip.

  17. Optical atomic magnetometer

    DOEpatents

    Budker, Dmitry; Higbie, James; Corsini, Eric P

    2013-11-19

    An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

  18. Metal atomization spray nozzle

    DOEpatents

    Huxford, T.J.

    1993-11-16

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal. 6 figures.

  19. Metal atomization spray nozzle

    DOEpatents

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  20. Anonymous Atomic Transactions,

    DTIC Science & Technology

    1996-07-01

    We show here an example of a protocol that satisfies anonymity properties while providing strong ACID (atomic, consistent, isolated, durable...transactional properties, resolving an open question. Blinded signatures are used to certify an anonymous asymmetric key which authorizes the use of a...key is spent. We show here an example of a protocol that satisfies anonymity properties while providing strong ACID (atomic, consistent, isolated

  1. Fundamental Mechanism of Atomization

    DTIC Science & Technology

    1989-07-01

    2Sk, The relation between the spatial amplification rate and (21) the wavelength is shown in Fig. 2 for the case of A 2 = 100 where Tin ...hand without the interference from the pressure fluctuation. Finally, in order to induce the shear waves to assist the atomization, we require ’c - a and...condition is satisfied. This example demonstrates how hard it is to induce the shear wave to assist in the onset of atomization. It should be

  2. Heterogeneous edge weights promote epidemic diffusion in weighted evolving networks

    NASA Astrophysics Data System (ADS)

    Duan, Wei; Song, Zhichao; Qiu, Xiaogang

    2016-08-01

    The impact that the heterogeneities of links’ weights have on epidemic diffusion in weighted networks has received much attention. Investigating how heterogeneous edge weights affect epidemic spread is helpful for disease control. In this paper, we study a Reed-Frost epidemic model in weighted evolving networks. Our results indicate that a higher heterogeneity of edge weights leads to higher epidemic prevalence and epidemic incidence at earlier stage of epidemic diffusion in weighted evolving networks. In addition, weighted evolving scale-free networks come with a higher epidemic prevalence and epidemic incidence than unweighted scale-free networks.

  3. Standard Model in multiscale theories and observational constraints

    NASA Astrophysics Data System (ADS)

    Calcagni, Gianluca; Nardelli, Giuseppe; Rodríguez-Fernández, David

    2016-08-01

    We construct and analyze the Standard Model of electroweak and strong interactions in multiscale spacetimes with (i) weighted derivatives and (ii) q -derivatives. Both theories can be formulated in two different frames, called fractional and integer picture. By definition, the fractional picture is where physical predictions should be made. (i) In the theory with weighted derivatives, it is shown that gauge invariance and the requirement of having constant masses in all reference frames make the Standard Model in the integer picture indistinguishable from the ordinary one. Experiments involving only weak and strong forces are insensitive to a change of spacetime dimensionality also in the fractional picture, and only the electromagnetic and gravitational sectors can break the degeneracy. For the simplest multiscale measures with only one characteristic time, length and energy scale t*, ℓ* and E*, we compute the Lamb shift in the hydrogen atom and constrain the multiscale correction to the ordinary result, getting the absolute upper bound t*<10-23 s . For the natural choice α0=1 /2 of the fractional exponent in the measure, this bound is strengthened to t*<10-29 s , corresponding to ℓ*<10-20 m and E*>28 TeV . Stronger bounds are obtained from the measurement of the fine-structure constant. (ii) In the theory with q -derivatives, considering the muon decay rate and the Lamb shift in light atoms, we obtain the independent absolute upper bounds t*<10-13 s and E*>35 MeV . For α0=1 /2 , the Lamb shift alone yields t*<10-27 s , ℓ*<10-19 m and E*>450 GeV .

  4. NONLINEAR ATOM OPTICS

    SciTech Connect

    T. MILONNI; G. CSANAK; ET AL

    1999-07-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objectives were to explore theoretically various aspects of nonlinear atom optics effects in cold-atom waves and traps. During the project a major development occurred the observation, by as many as a dozen experimental groups, of Bose-Einstein condensation (BEC) in cold-atom traps. This stimulated us to focus our attention on those aspects of nonlinear atom optics relating to BEC, in addition to continuing our work on a nonequilibrium formalism for dealing with the interaction of an electromagnetic field with multi-level atomic systems, allowing for macroscopic coherence effects such as BEC. Studies of several problems in BEC physics have been completed or are near completion, including the suggested use of external electric fields to modify the nature of the interatomic interaction in cold-atom traps; properties of two-phase condensates; and molecular loss processes associated with BEC experiments involving a so-called Feshbach resonance.

  5. Atomic mass compilation 2012

    SciTech Connect

    Pfeiffer, B.; Venkataramaniah, K.; Czok, U.; Scheidenberger, C.

    2014-03-15

    Atomic mass reflects the total binding energy of all nucleons in an atomic nucleus. Compilations and evaluations of atomic masses and derived quantities, such as neutron or proton separation energies, are indispensable tools for research and applications. In the last decade, the field has evolved rapidly after the advent of new production and measuring techniques for stable and unstable nuclei resulting in substantial ameliorations concerning the body of data and their precision. Here, we present a compilation of atomic masses comprising the data from the evaluation of 2003 as well as the results of new measurements performed. The relevant literature in refereed journals and reports as far as available, was scanned for the period beginning 2003 up to and including April 2012. Overall, 5750 new data points have been collected. Recommended values for the relative atomic masses have been derived and a comparison with the 2003 Atomic Mass Evaluation has been performed. This work has been carried out in collaboration with and as a contribution to the European Nuclear Structure and Decay Data Network of Evaluations.

  6. Atoms talking to SQUIDs

    NASA Astrophysics Data System (ADS)

    Hoffman, J. E.; Grover, J. A.; Ravets, S.; Voigt, K. D.; Lee, J.; Kim, Z.; Wood, A. K.; Schoch, I.; Anderson, J. R.; Dragt, A. J.; Hafezi, M.; Lobb, C. J.; Orozco, L. A.; Rolston, S. L.; Taylor, J. M.; Wellstood, F. C.

    2012-02-01

    We present our advances towards a hybrid quantum system of ^87Rb atoms coupled to a superconducting flux qubit through the magnetic dipole transition. We plan to trap atoms in the evanescent field outside a 500 nm nanofiber. This will allow us to bring the atoms less than 5 μm above the surface of the superconductor without producing excessive heating or changing magnetic fields. As an intermediate step, we plan on coupling the atoms to a superconducting LC resonator. Current progress includes production of nanofibers with >98% transmission, and a tunable high-Q superconducting resonator. Additionally, we show how to use our system as a unified interface for microwave and optical photons, in which the atoms act both as a quantum memory and transduce excitations between the two frequency domains. Using coherent control techniques, we examine conversion and storage of quantum information between microwave photons in superconducting resonators, ensembles of ultracold atoms, and optical photons as well as a method for transferring information between two resonators.

  7. Combining forecast weights: Why and how?

    NASA Astrophysics Data System (ADS)

    Yin, Yip Chee; Kok-Haur, Ng; Hock-Eam, Lim

    2012-09-01

    This paper proposes a procedure called forecast weight averaging which is a specific combination of forecast weights obtained from different methods of constructing forecast weights for the purpose of improving the accuracy of pseudo out of sample forecasting. It is found that under certain specified conditions, forecast weight averaging can lower the mean squared forecast error obtained from model averaging. In addition, we show that in a linear and homoskedastic environment, this superior predictive ability of forecast weight averaging holds true irrespective whether the coefficients are tested by t statistic or z statistic provided the significant level is within the 10% range. By theoretical proofs and simulation study, we have shown that model averaging like, variance model averaging, simple model averaging and standard error model averaging, each produces mean squared forecast error larger than that of forecast weight averaging. Finally, this result also holds true marginally when applied to business and economic empirical data sets, Gross Domestic Product (GDP growth rate), Consumer Price Index (CPI) and Average Lending Rate (ALR) of Malaysia.

  8. Low frequency mechanical modes of viruses with atomic detail

    NASA Astrophysics Data System (ADS)

    Dykeman, Eric; Sankey, Otto

    2008-03-01

    The low frequency mechanical modes of viruses can provide important insights into the large global motions that a virus may exhibit. Recently it has been proposed that these large global motions may be excited using impulsive stimulated Raman scattering producing permanent damage to the virus. In order to understand the coupling of external probes to the capsid, vibrational modes with atomic detail are essential. The standard approach to find the atomic modes of a molecule with N atoms requires the formation and diagonlization of a 3Nx3N matrix. As viruses have 10^5 or more atoms, the standard approach is difficult. Using ideas from electronic structure theory, we have developed a method to construct the mechanical modes of large molecules such as viruses with atomic detail. Application to viruses such as the cowpea chlorotic mottle virus, satellite tobacco necrosis virus, and M13 bacteriophage show a fairly complicated picture of the mechanical modes.

  9. Evaluation of ultrafiltration for determining molecular weight of fulvic acid

    USGS Publications Warehouse

    Aiken, G.R.

    1984-01-01

    Two commonly used ultrafiltration membranes are evaluated for the determination of molecular weights of humic substances. Polyacrylic acids of Mr 2000 and 5000 and two well-characterized fulvic acids are used as standards. Molecular size characteristics of standards, as determined by small-angle X-ray scattering, are presented. Great care in evaluating molecular weight data obtained by ultrafiltration is needed because of broad nominal cutoffs and membrane-solute interactions.

  10. Birth weight is forever.

    PubMed

    Basso, Olga

    2008-03-01

    Birth weight is associated not just with infant morbidity and mortality, but with outcomes occurring much later in life, including adult mortality, as reported by a paper by Baker and colleagues in this issue of Epidemiology. While these associations are tantalizing per se, the truly interesting question concerns the mechanisms that underlie these links. The prevailing hypothesis suggests a "fetal origin" of diseases resulting from alterations in fetal nutrition that permanently program organ function. The most commonly proposed alternative is that factors, mainly genetic, that affect both fetal growth and disease risk are responsible for the observed associations. Although both mechanisms are intellectually attractive-and may well coexist-we should be cautious to not focus excessively on fetal growth. Doing this may lead us in the wrong direction, as has likely happened in the case of birth weight in relation to infant survival.

  11. Reducing rotor weight

    SciTech Connect

    Cheney, M.C.

    1997-12-31

    The cost of energy for renewables has gained greater significance in recent years due to the drop in price in some competing energy sources, particularly natural gas. In pursuit of lower manufacturing costs for wind turbine systems, work was conducted to explore an innovative rotor designed to reduce weight and cost over conventional rotor systems. Trade-off studies were conducted to measure the influence of number of blades, stiffness, and manufacturing method on COE. The study showed that increasing number of blades at constant solidity significantly reduced rotor weight and that manufacturing the blades using pultrusion technology produced the lowest cost per pound. Under contracts with the National Renewable Energy Laboratory and the California Energy Commission, a 400 kW (33m diameter) turbine was designed employing this technology. The project included tests of an 80 kW (15.5m diameter) dynamically scaled rotor which demonstrated the viability of the design.

  12. Dynamic atomic contributions to infrared intensities of fundamental bands.

    PubMed

    Silva, Arnaldo F; Richter, Wagner E; Bassi, Adalberto B M S; Bruns, Roy E

    2015-11-11

    Dynamic atomic intensity contributions to fundamental infrared intensities are defined as the scalar products of dipole moment derivative vectors for atomic displacements and the total dipole derivative vector of the normal mode. Intensities of functional group vibrations of the fluorochloromethanes can be estimated within 6.5 km mol(-1) by displacing only the functional group atoms rather than all the atoms in the molecules. The asymmetric CF2 stretching intensity, calculated to be 126.5 km mol(-1) higher than the symmetric one, is accounted for by an 81.7 km mol(-1) difference owing to the carbon atom displacement and 40.6 km mol(-1) for both fluorine displacements. Within the Quantum Theory of Atoms in Molecules (QTAIM) model differences in atomic polarizations are found to be the most important for explaining the difference in these carbon dynamic intensity contributions. Carbon atom displacements almost completely account for the differences in the symmetric and asymmetric CCl2 stretching intensities of dichloromethane, 103.9 of the total calculated value of 105.2 km mol(-1). Contrary to that found for the CF2 vibrations intramolecular charge transfer provoked by the carbon atom displacement almost exclusively explains this difference. The very similar intensity values of the symmetric and asymmetric CH2 stretching intensities in CH2F2 arise from nearly equal carbon and hydrogen atom contributions for these vibrations. All atomic contributions to the intensities for these vibrations in CH2Cl2 are very small. Sums of dynamic contributions of the individual intensities for all vibrational modes of the molecule are shown to be equal to mass weighted atomic effective charges that can be determined from atomic polar tensors evaluated from experimental infrared intensities and frequencies. Dynamic contributions for individual intensities can also be determined solely from experimental data.

  13. Atom-atom inelastic collisions and three-body atomic recombination in weakly ionized argon plasmas

    NASA Technical Reports Server (NTRS)

    Braun, C. G.; Kunc, J. A.

    1989-01-01

    A stationary collisional-radiative model including both inelastic electron-atom and atom-atom collisions is used to examine nonequilibrium weakly ionized argon plasmas with atomic densities 10 to the 16th to 10 to the 20th/cu cm, temperatures below 6000 K, and with different degrees of radiation trapping. It is shown that three-body atomic recombination becomes important at high particle densities. Comparison is made between the present approach and Thomson's theory for atomic recombination.

  14. Revealing the hidden atom in graphite by low-temperature atomic force microscopy.

    PubMed

    Hembacher, Stefan; Giessibl, Franz J; Mannhart, Jochen; Quate, Calvin F

    2003-10-28

    Carbon, the backbone material of life on Earth, comes in three modifications: diamond, graphite, and fullerenes. Diamond develops tetrahedral sp3 bonds, forming a cubic crystal structure, whereas graphite and fullerenes are characterized by planar sp2 bonds. Polycrystalline graphite is the basis for many products of everyday life: pencils, lubricants, batteries, arc lamps, and brushes for electric motors. In crystalline form, highly oriented pyrolytic graphite is used as a diffracting element in monochromators for x-ray and neutron scattering and as a calibration standard for scanning tunneling microscopy (STM). The graphite surface is easily prepared as a clean atomically flat surface by cleavage. This feature is attractive and is used in many laboratories as the surface of choice for "seeing atoms." Despite the proverbial ease of imaging graphite by STM with atomic resolution, every second atom in the hexagonal surface unit cell remains hidden, and STM images show only a single atom in the unit cell. Here we present measurements with a low-temperature atomic force microscope with pico-Newton force sensitivity that reveal the hidden surface atom.

  15. FOREWORD: Fifty years of atomic time-keeping: 1955 to 2005

    NASA Astrophysics Data System (ADS)

    Quinn, Terry

    2005-06-01

    The year 2005 is the centenary of Einstein's four famous papers that were published in 1905. This anniversary is being widely celebrated all over the world and, indeed, 2005 has been dubbed World Year of Physics. The year 2005, however, also marks the fiftieth anniversary of the first operation of Essen and Parry's caesium beam atomic frequency standard at the NPL in May 1955. While Einstein's papers signalled a revolution in physics and in our understanding of the natural world, the first atomic clock signalled a revolution in time-keeping that has become, among other things, one of the most powerful tools in pushing back the frontiers of Einstein's theories of special and general relativity. The atomic clock has also had consequences for navigation comparable to those brought about by Harrison's mechanical clocks almost exactly two hundred years before. Harrison's H3 was completed in 1757 and H4 in 1759. The atomic clock, and the creation of an atomic time scale that quickly followed, led ten years later to the adoption of an atomic definition for the SI second in Resolution 1 of the 13th General Conference on Weights and Measures, 1967/68. This marked the end of time-keeping based on the movements of the heavenly bodies that had beaten the rhythm of the days and the seasons since the dawn of human civilization. Fifty years on is a good occasion to look back, to look forward and at the same time to examine where we are today, in terms of measuring time. While we still arrange for our atomic clocks to show noon when the sun is overhead on the Greenwich meridian, everything else has changed in the fifty years since 1955. In this special issue of Metrologia the reader will find articles on the development of the atomic clock, its theory and practice, how the first atomic time scale was devised and formally introduced and how we maintain atomic time today, as well as articles looking forward to even more accurate clocks and time scales. Included also are articles on

  16. Rb atomic magnetometer toward EDM experiment with laser cooled francium atoms

    NASA Astrophysics Data System (ADS)

    Inoue, Takeshi; Ando, Shun; Aoki, Takahiro; Arikawa, Hiroshi; Harada, Ken-Ichi; Hayamizu, Tomohiro; Ishikawa, Taisuke; Itoh, Masatoshi; Kato, Ko; Kawamura, Hirokazu; Sakamoto, Kosuke; Uchiyama, Aiko; Asahi, Koichiro; Yoshimi, Akihiro; Sakemi, Yasuhiro

    2014-09-01

    A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield. We prepared the cell coated with an anti-relaxation material and measured the relaxation time. A degauss of the shield was performed to eliminate the residual field. We will report the present status of the magnetometer. A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield

  17. Cold-atom double-Λ coherent population trapping clock

    NASA Astrophysics Data System (ADS)

    Esnault, F.-X.; Blanshan, E.; Ivanov, E. N.; Scholten, R. E.; Kitching, J.; Donley, E. A.

    2013-10-01

    Miniature atomic clocks based on coherent population trapping (CPT) states in thermal atoms are an important component in many field applications, particularly where satellite frequency standards are not accessible. Cold-atom CPT clocks promise improved accuracy and stability over existing commercial technologies. Here we demonstrate a cold-atom CPT clock based on 87Rb using a high-contrast double-Λ configuration. Doppler frequency shifts are explained using a simple model and canceled by interrogating the atoms with counterpropagating light beams. We realize a compact cold-atom CPT clock with a fractional frequency stability of 4×10-11τ-1/2, thus demonstrating the potential of these devices. We also show that the long-term stability is currently limited by the second-order Zeeman shift to 2×10-12 at 1000 s.

  18. Compact high-flux source of cold sodium atoms

    NASA Astrophysics Data System (ADS)

    Lamporesi, G.; Donadello, S.; Serafini, S.; Ferrari, G.

    2013-06-01

    We present a compact source of cold sodium atoms suitable for the production of quantum degenerate gases and versatile for a multi-species experiment. The magnetic field produced by permanent magnets allows to simultaneously realize a Zeeman slower and a two-dimensional magneto-optical trap (MOT) within an order of magnitude smaller length than standard sodium sources. We achieve an atomic flux exceeding 4 × 109 atoms/s loaded in a MOT, with a most probable longitudinal velocity of 20 m/s, and a brightness larger than 2.5 × 1012 atoms/s/sr. This atomic source allows us to produce pure Bose-Einstein condensates with more than 107 atoms and a background pressure limited lifetime of 5 min.

  19. Algebraic direct methods for few-atoms structure models.

    PubMed

    Hauptman, Herbert A; Guo, D Y; Xu, Hongliang; Blessing, Robert H

    2002-07-01

    As a basis for direct-methods phasing at very low resolution for macromolecular crystal structures, normalized structure-factor algebra is presented for few-atoms structure models with N = 1, 2, 3, em leader equal atoms or polyatomic globs per unit cell. Main results include: [see text]. Triplet discriminant Delta(hk) and triplet weight W(hk) parameters, a approximately 4.0 and b approximately 3.0, respectively, were determined empirically in numerical error analyses. Tests with phases calculated for few-atoms 'super-glob' models of the protein apo-D-glyceraldehyde-3-phosphate dehydrogenase (approximately 10000 non-H atoms) showed that low-resolution phases from the new few-atoms tangent formula were much better than conventional tangent formula phases for N = 2 and 3; phases from the two formulae were essentially the same for N > or = 4.

  20. Comment on 'Accurate rubidium atomic fountain frequency standard'

    NASA Astrophysics Data System (ADS)

    Li, Ruoxin; Gibble, Kurt

    2011-10-01

    We discuss the treatment of distributed cavity phase, microwave lensing and microwave leakage in the paper by Ovchinnikov and Marra (2011 Metrologia 48 87-100). The paper neglects the potential distributed cavity phase shifts from linear phase gradients and quadrupolar phase variations. Only azimuthally symmetric phase variations were analysed and an incorrect model was used for these. The paper also omits an uncertainty due to microwave lensing, which must be included. Finally, we describe additional measurements that could clarify the model used to analyse the frequency shifts due to microwave leakage.

  1. Vehicle Maximum Weight Limitation Based on Intelligent Weight Sensor

    NASA Astrophysics Data System (ADS)

    Raihan, W.; Tessar, R. M.; Ernest, C. O. S.; Byan, W. R. E.; Winda, A.

    2017-03-01

    Vehicle weight is an important factor to be maintained for transportation safety. A weight limitation system is proposed to make sure the vehicle weight is always below its designation prior the vehicle is being used by the driver. The proposed system is divided into two systems, namely vehicle weight confirmation system and weight warning system. In vehicle weight confirmation system, the weight sensor work for the first time after the ignition switch is turned on. When the weight is under the weight limit, the starter engine can be switched on to start the engine system, otherwise it will be locked. The seconds system, will operated after checking all the door at close position, once the door of the car is closed, the weight warning system will check once again the weight during runing engine condition. The results of these two systems, vehicle weight confirmation system and weight warning system have 100 % accuracy, respectively. These show that the proposed vehicle weight limitation system operate well.

  2. The grasp2K relativistic atomic structure package

    NASA Astrophysics Data System (ADS)

    Jönsson, P.; He, X.; Froese Fischer, C.; Grant, I. P.

    2007-10-01

    This paper describes grasp2K, a general-purpose relativistic atomic structure package. It is a modification and extension of the GRASP92 package by [F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. 94 (1996) 249]. For the sake of continuity, two versions are included. Version 1 retains the GRASP92 formats for wave functions and expansion coefficients, but no longer requires preprocessing and more default options have been introduced. Modifications have eliminated some errors, improved the stability, and simplified interactive use. The transition code has been extended to cases where the initial and final states have different orbital sets. Several utility programs have been added. Whereas Version 1 constructs a single interaction matrix for all the J's and parities, Version 2 treats each J and parity as a separate matrix. This block structure results in a reduction of memory use and considerably shorter eigenvectors. Additional tools have been developed for this format. The CPU intensive parts of Version 2 have been parallelized using MPI. The package includes a "make" facility that relies on environment variables. These make it easier to port the application to different platforms. The present version supports the 32-bit Linux and ibmSP environments where the former is compatible with many Unix systems. Descriptions of the features and the program/data flow of the package will be given in some detail in this report. Program summaryProgram title: grasp2K Catalogue identifier: ADZL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 213 524 No. of bytes in distributed program, including test data, etc.: 1 328 588 Distribution format: tar.gz Programming language: Fortran and C Computer: Intel

  3. Atomic resolution holography.

    PubMed

    Hayashi, Kouichi

    2014-11-01

    Atomic resolution holography, such as X-ray fluorescence holography (XFH)[1] and photoelectron holography (PH), has the attention of researcher as an informative local structure analysis, because it provides three dimensional atomic images around specific elements within a range of a few nanometers. It can determine atomic arrangements around a specific element without any prior knowledge of structures. It is considered that the atomic resolution holographic is a third method of structural analysis at the atomic level after X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). As known by many researchers, XRD and XAFS are established methods that are widespread use in various fields. XRD and XAFS provide information on long-range translational periodicities and very local environments, respectively, whereas the atomic resolution holography gives 3D information on the local order and can visualize surrounding atoms with a large range of coordination shells. We call this feature "3D medium-range local structure observation".In addition to this feature, the atomic resolution holography is very sensitive to the displacement of atoms from their ideal positions, and one can obtain quantitative information about local lattice distortions by analyzing reconstructed atomic images[2] When dopants with different atomic radii from the matrix elements are present, the lattices around the dopants are distorted. However, using the conventional methods of structural analysis, one cannot determine the extent to which the local lattice distortions are preserved from the dopants. XFH is a good tool for solving this problem.Figure 1 shows a recent achievement on a relaxor ferroelectric of Pb(Mg1/3Nb2/3)O3 (PMN) using XFH. The structural studies of relaxor ferroelectrics have been carried out by X-ray or neutron diffractions, which suggested rhombohedral distortions of their lattices. However, their true pictures have not been obtained, yet. The Nb Kα holograms showed

  4. Pesticide Standards

    ERIC Educational Resources Information Center

    Shea, Kevin P.

    1976-01-01

    The Environmental Protection Agency chose the American Society of Testing and Materials to develop standardized guidelines for pesticide registration. Since the numbers and uses of pesticides is so wide, establishing ecological and public health guidelines may be difficult. Strong industry and government representation might also hamper the…

  5. Telemetry Standards

    DTIC Science & Technology

    1999-01-01

    signal and spectral mask (frequency span = 5 MHz) A-17 A-8 Unfiltered 1000 kbps RNRZ PCM/FM signal and spectral mask A-17 A-9 1000 kbps OQPSK ...INITIALISMS N newton NNT notch noise test NPR noise power ratio NPRF noise power ratio floor NRZ-L non return to zero-level OQPSK offset quadrature...0.7ft 1.50 ft PSK, no filter 19.30 ft Quadrature phase shift keying (QPSK), no filter 9.65 ft Offset QPSK ( OQPSK ), sinusoidal weighting 1.18 ft 5I

  6. Atomic oxygen stimulated outgassing

    NASA Technical Reports Server (NTRS)

    Linton, Roger C.; Reynolds, John M.

    1991-01-01

    The passive Long Duration Exposure Facility (LDEF) Experiment A0034, Atomic Oxygen Simulated Outgassing, consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge and, for reference, to the relative wake environment on the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of the various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and a optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to the RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

  7. Atom-chip-based generation of entanglement for quantum metrology.

    PubMed

    Riedel, Max F; Böhi, Pascal; Li, Yun; Hänsch, Theodor W; Sinatra, Alice; Treutlein, Philipp

    2010-04-22

    Atom chips provide a versatile quantum laboratory for experiments with ultracold atomic gases. They have been used in diverse experiments involving low-dimensional quantum gases, cavity quantum electrodynamics, atom-surface interactions, and chip-based atomic clocks and interferometers. However, a severe limitation of atom chips is that techniques to control atomic interactions and to generate entanglement have not been experimentally available so far. Such techniques enable chip-based studies of entangled many-body systems and are a key prerequisite for atom chip applications in quantum simulations, quantum information processing and quantum metrology. Here we report the experimental generation of multi-particle entanglement on an atom chip by controlling elastic collisional interactions with a state-dependent potential. We use this technique to generate spin-squeezed states of a two-component Bose-Einstein condensate; such states are a useful resource for quantum metrology. The observed reduction in spin noise of -3.7 +/- 0.4 dB, combined with the spin coherence, implies four-partite entanglement between the condensate atoms; this could be used to improve an interferometric measurement by -2.5 +/- 0.6 dB over the standard quantum limit. Our data show good agreement with a dynamical multi-mode simulation and allow us to reconstruct the Wigner function of the spin-squeezed condensate. The techniques reported here could be directly applied to chip-based atomic clocks, currently under development.

  8. Anabolic steroid boosts weight.

    PubMed

    1996-09-01

    A randomized study of nandrolone decanoate (Deca-Durabolin) showed that the anabolic steroid can increase weight in people with HIV infections. The group receiving nandrolone experienced a greater increase both in fat-free mass and body cell mass (although the latter measure did not reach statistical significance) than those on placebo. Deca-Durabolin had little to do with two occurrences of Kaposi's sarcoma (KS) in the study group, but until further studies are completed, caution is advised when using this steroid in patients with KS. A new study comparing nandrolone to growth hormone in patients with wasting is slated to begin in the next 3 or 4 months.

  9. Atomic Models of Strong Solids Interfaces Viewed as Composite Structures

    NASA Astrophysics Data System (ADS)

    Staffell, I.; Shang, J. L.; Kendall, K.

    2014-02-01

    This paper looks back through the 1960s to the invention of carbon fibres and the theories of Strong Solids. In particular it focuses on the fracture mechanics paradox of strong composites containing weak interfaces. From Griffith theory, it is clear that three parameters must be considered in producing a high strength composite:- minimising defects; maximising the elastic modulus; and raising the fracture energy along the crack path. The interface then introduces two further factors:- elastic modulus mismatch causing crack stopping; and debonding along a brittle interface due to low interface fracture energy. Consequently, an understanding of the fracture energy of a composite interface is needed. Using an interface model based on atomic interaction forces, it is shown that a single layer of contaminant atoms between the matrix and the reinforcement can reduce the interface fracture energy by an order of magnitude, giving a large delamination effect. The paper also looks to a future in which cars will be made largely from composite materials. Radical improvements in automobile design are necessary because the number of cars worldwide is predicted to double. This paper predicts gains in fuel economy by suggesting a new theory of automobile fuel consumption using an adaptation of Coulomb's friction law. It is demonstrated both by experiment and by theoretical argument that the energy dissipated in standard vehicle tests depends only on weight. Consequently, moving from metal to fibre construction can give a factor 2 improved fuel economy performance, roughly the same as moving from a petrol combustion drive to hydrogen fuel cell propulsion. Using both options together can give a factor 4 improvement, as demonstrated by testing a composite car using the ECE15 protocol.

  10. Atomic hydrogen as a launch vehicle propellant

    SciTech Connect

    Palaszewski, B.A.

    1990-01-01

    An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I{sub sp}) were 750 and 1500 lb{sub f}/s/lb{sub m}. The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I{sub sp} (greater than 750 lb{sub f}/s/lb{sub m}) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

  11. Atomic hydrogen as a launch vehicle propellant

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan A.

    1990-01-01

    An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

  12. Development of a compact cold-atom atomic clock based on coherent population trapping

    NASA Astrophysics Data System (ADS)

    Blanshan, Eric M.

    Field-grade atomic clocks capable of primary standard performance in compact physics packages would be of significant value in a variety of applications ranging from network synchronization and secure communications to GPS hold-over and inertial navigation. A cold-atom coherent population trapping (CACPT) clock featuring laser-cooled atoms and pulsed Ramsey interrogation is a strong candidate for this technology if the principal frequency shifts can be controlled and the performance degradation associated with miniaturization can be overcome. In this thesis, research focused on the development of this type of compact atomic clock is presented. To address the low atom numbers obtained in small cold-atom sources, experiments were performed in which an atomic beam was decelerated with bichromatic stimulated laser forces and loaded into a mm-scale magneto-optical trap, increasing the atom number by a factor of 12.5. A CACPT clock using the high-contrast lin||lin optical interrogation technique was developed and achieved a stability of 7 x 10-13 after one hour of integration. Doppler shifts in the clock are explained using a simple kinematic model and canceled by interrogating the atoms with a counter-propagating CPT configuration. Finally, a thorough characterization of the AC-stark effect in lin||lin CPT was performed. Observed shifts are explained in terms of contributions from coherent CPT-generating couplings and population transfer effects caused by optical pumping from incoherent light. Measurements are compared with existing and new theoretical treatments, and a laser configuration is identified that reduces clock drift from light shifts to less than 10-14 for the current system.

  13. Single atom devices by ion implantation.

    PubMed

    van Donkelaar, Jessica; Yang, C; Alves, A D C; McCallum, J C; Hougaard, C; Johnson, B C; Hudson, F E; Dzurak, A S; Morello, A; Spemann, D; Jamieson, D N

    2015-04-22

    To expand the capabilities of semiconductor devices for new functions exploiting the quantum states of single donors or other impurity atoms requires a deterministic fabrication method. Ion implantation is a standard tool of the semiconductor industry and we have developed pathways to deterministic ion implantation to address this challenge. Although ion straggling limits the precision with which atoms can be positioned, for single atom devices it is possible to use post-implantation techniques to locate favourably placed atoms in devices for control and readout. However, large-scale devices will require improved precision. We examine here how the method of ion beam induced charge, already demonstrated for the deterministic ion implantation of 14 keV P donor atoms in silicon, can be used to implant a non-Poisson distribution of ions in silicon. Further, we demonstrate the method can be developed to higher precision by the incorporation of new deterministic ion implantation strategies that employ on-chip detectors with internal charge gain. In a silicon device we show a pulse height spectrum for 14 keV P ion impact that shows an internal gain of 3 that has the potential of allowing deterministic implantation of sub-14 keV P ions with reduced straggling.

  14. Hg(+) Frequency Standards

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  15. Korean atomic bomb victims.

    PubMed

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea).

  16. Iowa Powder Atomization Technologies

    SciTech Connect

    2012-01-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  17. Atomic Force Microscope

    SciTech Connect

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  18. Atomic cluster collisions

    NASA Astrophysics Data System (ADS)

    Korol, Andrey V.; Solov'yov, Andrey

    2013-01-01

    Atomic cluster collisions are a field of rapidly emerging research interest by both experimentalists and theorists. The international symposium on atomic cluster collisions (ISSAC) is the premier forum to present cutting-edge research in this field. It was established in 2003 and the most recent conference was held in Berlin, Germany in July of 2011. This Topical Issue presents original research results from some of the participants, who attended this conference. This issues specifically focuses on two research areas, namely Clusters and Fullerenes in External Fields and Nanoscale Insights in Radiation Biodamage.

  19. Atomization and Mixing Study

    NASA Technical Reports Server (NTRS)

    Ferrenberg, A.; Hunt, K.; Duesberg, J.

    1985-01-01

    The primary objective was the obtainment of atomization and mixing performance data for a variety of typical liquid oxygen/hydrocarbon injector element designs. Such data are required to establish injector design criteria and to provide critical inputs to liquid rocket engine combustor performance and stability analysis, and computational codes and methods. Deficiencies and problems with the atomization test equipment were identified, and action initiated to resolve them. Test results of the gas/liquid mixing tests indicated that an assessment of test methods was required. A series of 71 liquid/liquid tests were performed.

  20. Iowa Powder Atomization Technologies

    ScienceCinema

    None

    2016-07-12

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  1. Long term stability of atomic time scales

    NASA Astrophysics Data System (ADS)

    Petit, G.; Arias, F.

    2015-03-01

    We review the stability and accuracy achieved by the reference atomic time scales TAI and TT(BIPM). We show that they presently are in the low 10-16 in relative value, based on the performance of primary standards, of the ensemble time scale and of the time transfer techniques. We consider how the 1 × 10-16 value could be reached or superseded and which are the present limitations to attain this goal.

  2. Weighted triangulation adjustment

    USGS Publications Warehouse

    Anderson, Walter L.

    1969-01-01

    The variation of coordinates method is employed to perform a weighted least squares adjustment of horizontal survey networks. Geodetic coordinates are required for each fixed and adjustable station. A preliminary inverse geodetic position computation is made for each observed line. Weights associated with each observed equation for direction, azimuth, and distance are applied in the formation of the normal equations in-the least squares adjustment. The number of normal equations that may be solved is twice the number of new stations and less than 150. When the normal equations are solved, shifts are produced at adjustable stations. Previously computed correction factors are applied to the shifts and a most probable geodetic position is found for each adjustable station. Pinal azimuths and distances are computed. These may be written onto magnetic tape for subsequent computation of state plane or grid coordinates. Input consists of punch cards containing project identification, program options, and position and observation information. Results listed include preliminary and final positions, residuals, observation equations, solution of the normal equations showing magnitudes of shifts, and a plot of each adjusted and fixed station. During processing, data sets containing irrecoverable errors are rejected and the type of error is listed. The computer resumes processing of additional data sets.. Other conditions cause warning-errors to be issued, and processing continues with the current data set.

  3. Weight and weddings. Engaged men's body weight ideals and wedding weight management behaviors.

    PubMed

    Klos, Lori A; Sobal, Jeffery

    2013-01-01

    Most adults marry at some point in life, and many invest substantial resources in a wedding ceremony. Previous research reports that brides often strive towards culturally-bound appearance norms and engage in weight management behaviors in preparation for their wedding. However, little is known about wedding weight ideals and behaviors among engaged men. A cross-sectional survey of 163 engaged men asked them to complete a questionnaire about their current height and weight, ideal wedding body weight, wedding weight importance, weight management behaviors, formality of their upcoming wedding ceremony, and demographics. Results indicated that the discrepancy between men's current weight and reported ideal wedding weight averaged 9.61 lb. Most men considered being at a certain weight at their wedding to be somewhat important. About 39% were attempting to lose weight for their wedding, and 37% were not trying to change their weight. Attempting weight loss was more frequent among men with higher BMI's, those planning more formal weddings, and those who considered being the right weight at their wedding as important. Overall, these findings suggest that weight-related appearance norms and weight loss behaviors are evident among engaged men.

  4. Marital status and body weight, weight perception, and weight management among U.S. adults.

    PubMed

    Klos, Lori A; Sobal, Jeffery

    2013-12-01

    Married individuals often have higher body weights than unmarried individuals, but it is unclear how marital roles affect body weight-related perceptions, desires, and behaviors. This study analyzed cross-sectional data for 4,089 adult men and 3,989 adult women using multinomial logistic regression to examine associations between marital status, perceived body weight, desired body weight, and weight management approach. Controlling for demographics and current weight, married or cohabiting women and divorced or separated women more often perceived themselves as overweight and desired to weigh less than women who had never married. Marital status was unrelated to men's weight perception and desired weight change. Marital status was also generally unrelated to weight management approach, except that divorced or separated women were more likely to have intentionally lost weight within the past year compared to never married women. Additionally, never married men were more likely to be attempting to prevent weight gain than married or cohabiting men and widowed men. Overall, married and formerly married women more often perceived themselves as overweight and desired a lower weight. Men's marital status was generally unassociated with weight-related perceptions, desires, and behaviors. Women's but not men's marital roles appear to influence their perceived and desired weight, suggesting that weight management interventions should be sensitive to both marital status and gender differences.

  5. Interface standardization

    NASA Technical Reports Server (NTRS)

    Spencer, R.; Wong, V.

    1983-01-01

    Central-station applications create a large and attractive market for photovoltaics in the near future. However, some significant barriers lie between the industry of today and realization of that market. Manufacturing capacity and price are two principal impediments. The Utilities, which are the future system owners, are gaining experience with central-station PV power through the Sacramento Municipal Utility District, Hesperia and similar small central-station installations. SMUD has recognized that competition must be maintained to help reduce prices. So little standardization exists that the cost is driven upward to redefine mechanical and electrical interfaces for each vendor. New structues are required for each vendor and nonoptimum field geometries result from attempts to include more than one vendor in an array field. Standards at some hardware level are required.

  6. Atoms.inp Archive: Crystallographic Data from GSECARS

    DOE Data Explorer

    Newville, Matthew

    The Atoms.inp Archive is a collection of crystallographic data for use in XAFS analysis. The crystallographic data is stored as atoms.inp files, which contain all the information necessary to describe the crystal, and can be used by the program ATOMS to generate feff.inp files. These files can then be used by the FEFF program [See http://leonardo.phys.washington.edu/feff/] to calculate a theoretical XAFS spectrum for the crystal. This archive exists because it can take a considerable amount of time to locate a suitable reference for a model structure to use for making theoretical XAFS standards. Even then, references sometimes give non-standard or incomplete crystallographic notation that ATOMS has difficulty interpreting. All of this means that getting a reliable atoms.inp file can take quite a bit of effort. It is hoped that this collection of well-documented and well-tested atoms.inp files will eliminate much of the work in creating theoretical XAFS standards from FEFF. [Taken from http://cars9.uchicago.edu/~newville/adb/]. The collection currently has more than 200 crystal structures, 2748 data files, and it continues to expand. The collection is related to the UWXAFS Project [http://depts.washington.edu/uwxafs/] and to the work of the Consortium for Advanced Radiation Sources (CARS). After searching the Archive, a user may also choose to run the web version of ATOMS software.

  7. Liquid calories, sugar, and body weight.

    PubMed

    Drewnowski, Adam; Bellisle, France

    2007-03-01

    The consumption of sugar-sweetened beverages has been linked to rising rates of obesity in the United States. The standard explanation is that energy-containing liquids are less satiating than are solid foods. However, purely physiologic mechanisms do not fully account for the proposed links between liquid sugar energy and body weight change. First, a reevaluation of published epidemiologic studies of consumption of sweetened beverages and overweight shows that most such studies either are cross-sectional or are based on passive surveillance of temporal trends and thus permit no conclusions about causal links. Second, research evidence comparing the short-term satiating power of different types of liquids and of solids remains inconclusive. Numerous clinical studies have shown that sugar-containing liquids, when consumed in place of usual meals, can lead to a significant and sustained weight loss. The principal ingredient of liquid meal replacement shakes is sugar, often high-fructose corn syrup, which is present in amounts comparable to those in soft drinks. Far from suppressing satiety, one such liquid shake is marketed on the grounds that it helps control hunger and prevents hunger longer when consumed for the purpose of weight loss. These inconsistencies raise the question whether the issue of sugars and body weight should continue to be framed purely in metabolic or physiologic terms. The effect of sugar consumption on body weight can also depend on behavioral intent, context, and the mode of use, availability, and cost of sweetened liquids.

  8. Strong gold atom strands formed by incorporation of carbon atoms

    NASA Astrophysics Data System (ADS)

    Oshima, Yoshifumi; Kurui, Yoshihiko; Nguyen, Huy Duy; Ono, Tomoya; Takayanagi, Kunio

    2011-07-01

    Single metal atom strands have attracted significant interest because of their unique properties, such as quantization effects and a high degree of strength. Recently it was suggested that the strength of a gold atom strand can be enhanced by the insertion of an impurity atom, but it has not been experimentally investigated. Using a transmission electron microscope under ultrahigh vacuum conditions, we observed that gold atoms were pulled out one by one from a carbon-contaminated gold (111) surface to form a long atom strand. The strand was so strong that it did not break even upon bending. Supported by first-principles calculations, the strand was found to have two carbon atoms at each gold atom interval. Our observations suggest that the carbon atoms act as a glue to form a long gold atom strand.

  9. Spatially resolved photoionization of ultracold atoms on an atom chip

    SciTech Connect

    Kraft, S.; Guenther, A.; Fortagh, J.; Zimmermann, C.

    2007-06-15

    We report on photoionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 {mu}K in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 {mu}m, two laser beams are focused onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two-photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photoionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is suitable not only to investigate mixtures of Bose-Einstein condensates and ions but also for single-atom detection on an atom chip.

  10. Hardware friendly adaptive support-weight approach for stereo matching

    NASA Astrophysics Data System (ADS)

    Hou, Zuoxun; Han, Pei; Zhang, Hongwei; An, Ran

    2016-10-01

    In this paper, the hardware friendly adaptive support-weight approach is proposed to simplify the weight calculation process of the standard approach, which employs the support region to simplify the calculation of the similarity and uses the fixed distance dependent weight to present the proximity. In addition, the complete stereo matching algorithm and the hardware structure for FPGA implementation compatible with the approach is proposed. The experimental results show that the algorithm produces the disparity map accurately in different illumination conditions and different scenes, and its processing average bad pixel rate is only 6.65% for the standard test images of the Middlebury database, which is approximate to the performance of the standard adaptive support-weight approach. The proposed hardware structure provides a basis for design and implementation of real-time accurate stereo matching FPGA system.

  11. Anatomical MRI with an atomic magnetometer.

    PubMed

    Savukov, I; Karaulanov, T

    2013-06-01

    Ultra-low field (ULF) MRI is a promising method for inexpensive medical imaging with various additional advantages over conventional instruments such as low weight, low power, portability, absence of artifacts from metals, and high contrast. Anatomical ULF MRI has been successfully implemented with SQUIDs, but SQUIDs have the drawback of a cryogen requirement. Atomic magnetometers have sensitivity comparable to SQUIDs and can be in principle used for ULF MRI to replace SQUIDs. Unfortunately some problems exist due to the sensitivity of atomic magnetometers to a magnetic field and gradients. At low frequency, noise is also substantial and a shielded room is needed for improving sensitivity. In this paper, we show that at 85 kHz, the atomic magnetometer can be used to obtain anatomical images. This is the first demonstration of any use of atomic magnetometers for anatomical MRI. The demonstrated resolution is 1.1 mm×1.4 mm in about 6 min of acquisition with SNR of 10. Some applications of the method are discussed. We discuss several measures to increase the sensitivity to reach a resolution 1 mm×1 mm.

  12. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1994-02-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 185 citations and includes a subject term index and title list.)

  13. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 204 citations and includes a subject term index and title list.)

  14. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-04-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications for high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion are examined. (Contains a minimum of 151 citations and includes a subject term index and title list.)

  15. Polarizability of 5s25p(2P12) atomic indium

    NASA Astrophysics Data System (ADS)

    Guella, T. P.; Miller, Thomas M.; Bederson, B.; Stockdale, J. A. D.; Jaduszliwer, B.

    1984-06-01

    We have measured the static electric dipole polarizability of ground state 115 49In5s25p(2P12) with a small (~9%) admixture of metastable 5s25p(2P32). Three different methods were used: (a) E-H gradient balance, (b) comparison of deflection in an inhomogeneous electric field with an alkalimetal-atom "standard," and (c) a deflection analysis using a computer program with no adjustable parameters except the polarizability itself. All methods agree to within 11%. Our weighted final result is (10.18+/-1.20)×10-24 cm3. This is in very close agreement to a recent computation by Liberman and Zangwill, using fully relativistic wave functions and including electron correlation.

  16. Modeling operating weight and axle weight distributions for highway vehicles

    SciTech Connect

    Greene, D.L.; Liang, J.C.

    1988-07-01

    The estimation of highway cost responsibility requires detailed information on vehicle operating weights and axle weights by type of vehicle. Typically, 10--20 vehicle types must be cross-classified by 10--20 registered weight classes and again by 20 or more operating weight categories, resulting in 100--400 relative frequencies to be determined for each vehicle type. For each of these, gross operating weight must be distributed to each axle or axle unit. Given the rarity of many of the heaviest vehicle types, direct estimation of these frequencies and axle weights from traffic classification count statistics and truck weight data may exceed the reliability of even the largest (e.g., 250,000 record) data sources. An alternative is to estimate statistical models of operating weight distributions as functions of registered weight, and models of axle weight shares as functions of operating weight. This paper describes the estimation of such functions using the multinomial logit model (a log-linear model) and the implementation of the modeling framework as a PC-based FORTRAN program. Areas for further research include the addition of highway class and region as explanatory variables in operating weight distribution models, and the development of theory for including registration costs and costs of operating overweight in the modeling framework. 14 refs., 45 figs., 5 tabs.

  17. A Dozen Primers on Important Information Standards

    ERIC Educational Resources Information Center

    Dempsey, Kathy, Comp.

    2007-01-01

    This is a compilation of 12 primers on important information standards and protocols. These primers are: (1) Atom; (2) COinS; (3) MADS; (4) MARC 21/MARCXML; (5) MIX; (6) MXG; (7) OpenSearch; (8) PREMIS; (9) RESTful HTTP; (10) unAPI; (11) XMPP (aka Jabber); and (12) ZeeRex. The Atom Syndication Format defines a new XML-based syndication format for…

  18. Microfabricated ion frequency standard

    DOEpatents

    Schwindt, Peter; Biedermann, Grant; Blain, Matthew G.; Stick, Daniel L.; Serkland, Darwin K.; Olsson, III, Roy H.

    2010-12-28

    A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

  19. Atomically Traceable Nanostructure Fabrication.

    PubMed

    Ballard, Josh B; Dick, Don D; McDonnell, Stephen J; Bischof, Maia; Fu, Joseph; Owen, James H G; Owen, William R; Alexander, Justin D; Jaeger, David L; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J; Wallace, Robert M; Reidy, Richard; Silver, Richard M; Randall, John N; Von Ehr, James

    2015-07-17

    Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

  20. Experiments with Ξ- atoms

    NASA Astrophysics Data System (ADS)

    Batty, C. J.; Friedman, E.; Gal, A.

    1999-01-01

    Experiments with Ξ- atoms are proposed in order to study the nuclear interaction of Ξ hyperons. The production of Ξ- in the (K-,K+) reaction, the Ξ- stopping in matter, and its atomic cascade are incorporated within a realistic evaluation of the results expected for Ξ- x-ray spectra across the periodic table, using an assumed Ξ-nucleus optical potential Vopt. Several optimal targets for measuring the strong-interaction shift and width of the x-ray transition to the ``last'' atomic level observed are singled out: F, Cl, I, and Pb. The sensitivity of these observables to the parameters of Vopt is considered. The relevance of such experiments is discussed in the context of strangeness -2 nuclear physics and multistrange nuclear matter. Finally, with particular reference to searches for the H dibaryon, the properties of Ξ-d atoms are also discussed. The role of Stark mixing and its effect on S and P state capture of Ξ- by the deuteron together with estimates of the resulting probability for producing the H dibaryon are considered in detail.