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Microbiology Topics. ABOUT THE AUTHOR Measurement of Microbial Cells by Optical Density
No full text"Microbiology Topics" discusses various topics in microbiology of practical use in validation and compliance. We intend this column to be a useful resource for daily work applications. Reader comments, questions, and suggestions are needed to help us fulfill our objective for this column. Please send your comments and suggestions to column coordinator Scott Sutton at scott. [email protected] or journal coordinating editor Susan Haigney at [email protected]. KEY POINTS The following key points are discussed: Quality control (QC) microbiology tests require controlled levels of inocula and require fresh preparations of cells for those inocula The concentration of cells in a suspension can be estimated by optical density, but this must be confirmed by plate count The optical density readings against cell mass are specific to the microorganism species The qualification of these readings must be confirmed after major maintenance to the bench top spectrophotometer (e.g., after replacement of the bulb). There are, of course, two problems with these instructions. The first is that the technician is instructed to use an inoculum of about 10 8 microorganisms per milliliter and then instructed to determine this by plate count. Colony forming units (CFU) and cells (micro-organisms and spores) are different measures. This will inevitably lead to difficulties as the unfortunate lab worker cannot guarantee the number of cells in the suspension, only the number of CFU found. However, we can accept the scientific inaccuracy, as the numbers will generally work out. The more serious problem is the instruction to use the plate count CFU for determination of the inoculum for the test, and that the suspension shall be used immediately. This quite frankly cannot be done. If you use the suspension immediately, the plate counts are unavailable; if you use the plate counts to set the inoculum, then the suspension is at least a day old. DETERMINATION OF INOCULUM FOR THE AET Contrast these instructions with those in the United States Pharmacopeia (USP) (2) for the same exercise: Scott Sutton are needed to help us fulfill our objective fo fo for this column. Please send your comments an an and d d su u ugg gg gges es etions to column coordinator Scott Su Su Sutt tt tton n n at sc sc scot ot ott. t. t. [email protected] or journal co co coor o o dina a nating e e editor Susan Haigney at shaigney@ y@ [email protected]. KEY POINTS suspending fluid … Add sufficient suspend fluid to reduce the microbial count to about micro-organisms per milliliter…Remove imm ately a suitable sample from each suspension d d de d termine the number of colony-forming u per milliliter in each suspension by plate coun membrane filtration (2.6.12). This value se KEY POINTS The following key points are discuss sed ed: Quality control (QC) microbiolog gy test sts s re equ quire controlled levels of inocula and nd r re equi ire f fresh sh preparations of cells for those inocula The co o onc ncen en ntr tr trat at atio io ion n n of cells in n a a su uspen nsi sion o can be es s sti i imated b b by y y op op opti ti tical dens nsity, y, b but ut this s mu must s be membrane filtration (2.6.12). This value se to determine the inoculum and the baselin use in the test. The suspensions shall be u immediately." There are, of course, two problems with these t t tion n ns. s. s. T T The he he f f fir ir irst st i is s s th th hat at t t th h he t t tec e echnicia an is is i ins nstr truc u te an an an ino no noculum of a a abo out 10 0 0 8 8 8 m m mic croorg gan nisms s pe per m c co conf f fir rmed by p p plate te te c c cou o o nt t Th h he op p ptical den n nsit t ty r re rea adin ings gs a agai inst st cel e l m mass a are r s s sp s ec ec ec e ifi i ic to th h h he e e e m m mi m croo o o org gan an anis is sm specie ie es Th Th Th he q qu l l alif if ifi i ication of the h h se readings mu t t st be confirmed e e e a a a after m m m maj j j jor o o mai ai aint t ten e e ance ce ce t t to o o the e e be b b nc c ch h h t t top sp sp sp spec ec e ect t tropho ho ho hoto to to tom m meter r (e (e (e.g g g., aft fter er er r repla ace ement nt nt of the bulb) a a and d d th th then n n i i instru u ucte e ed to o o d d deter erm mine e thi his s by by plat C C Colony f f fo o orm m ming un n nits ( ( (CF C CFU) U) a and nd ce ells s ( (mi mic cro-or an an and d d d sp p por r res es es es) ) ) ) are d d dif f ffer er er ere e en e t measu ur u es es es. T This w w wil ill l l in l l lead d d d t t t to o o di di di dif fficulties as t t the unfortun t t ate lab wo k k rke guar r r ran a a a tee th th th he e e e numb mb mb ber of f f f ce ce ce cell ll lls s in t t the he he s s sus u u pens ns nsi i i the e e nu nu nu numb m m m er o o of CFU U U foun n n nd d. d. d H H Ho ow o ev ver er r, , w w we can n n a a ac scientific inaccuracy as the numbers will genera of the bulb) ) ). DE DE DE DETE TE TE TERM RM RM RMIN IN IN INAT AT AT ATIO IO IO ION N N N OF OF OF OF I I INO NO NOCU CU CULU LU LUM M M FO FO FOR R R scientific inaccuracy, y as the numbers will g genera ou ou ou out. t t t Th Th Th The e e e mo mo mo more re re re s s ser er er erio io io ious us us us p p p pro r ro robl bl bl blem em em i i is s s th th the e e in in inst st stru ru ruct ct ctio o th th th the e e e pl pl pl plat at at a e e e e co co co coun un un unt t t t CF CF CF CFU U U U fo fo fo for r r r de de de dete te te t rm rm rmin in inat at atio io ion n n of of of t t the he he i i in
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Limiting Avoidable Microbiological Variability
No full text[ "Microbiology Topics" discusses various topics in microbiology of practical use in validation and compliance. We intend this column to be a useful resource for daily work applications. Reader comments, questions, and suggestions are needed to help us fulfill our objective for this column. Case studies from readers are most welcome. Please send your comments and suggestions to column coordinator Scott Sutton at scott.sutton@microbiol. org or journal coordinating editor Susan Haigney at [email protected]. KEY POINTS The following key points are discussed in this article: • Quality control (QC) microbiology test data are subject to significant variability, both avoidable and unavoidable • Good microbiological procedures, backed by sound microbiological practices, can serve to minimize avoidable variability • The lab's standard operating procedure (SOP) system is a powerful tool to describe and document compliance with good practice • The lab should determine critical areas of coverage for the SOP system to ensure a comprehensive program • The SOP for a lab test should describe critical parameters of the test and meet the criteria of regulatory requirements and guidance for that procedure. The documentation of compliance with these requirements is both a legitimate good manufacturing practice (GMP) audit concern and a useful source of information for investigations. • A sound SOP system can serve to minimize avoidable variability in the microbiology lab • SOPs may be categorized into testing methods, documentation and SOPs, environmental monitoring, and laboratory support activities • Training for the members of the lab should be tightly tied to the SOP system, and can support functional specialization of staff • SOPs for each functional area are described • The content of this discussion should serve to benchmark your system, guide regulatory compliance, and be a framework for training • Considering the SOP system from a functional perspective links job skills to SOPs and facilitates tracking of revisions • Controlling variability and avoidable error is critical to successful microbiology laboratory operation because microbiology is exquisitely sensitive to personnel performance and techniques. INTRODUCTION Microbiology in the QC laboratory is subject to variability in the test results, in the samples taken, in the manner in which they are taken (with severe limitations in sample size contributing to the problem), and Limiting Avoidable Microbiological Variability Scott Sutton ABOUT THE AUTHOR Scott Sutton, Ph.D., is owner and operator of The Microbiology Network (www.microbiol.org), which provides services to microbiology-related user's groups. Dr. Sutton can be reached at scott. [email protected]. g x p a n d j v t . c o
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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