Dear Ian, I take issue with your assertion below that “the totally precise **scientific** meaning....is an **engineering**” definition. Science and engineering are not the same. Health and safety leads to the need in engineering for redundancy and indeed safety factors. In essence, in engineering terms, one feels safest on a Brunel bridge than a Boris Johnson “across the Thames” walkway. The matter for science is encapsulated in Hermann’s excellent proposal, now seconded twice, MPR, measurements per hkl reflection. Even with Xray damage hkl as a label is the constant. Also XFELs offer Xray damage free reflection intensity measurements of an hkl reflection. Likewise neutrons offer damage free intensity measurements of an hkl.
Best regards, John Emeritus Professor John R Helliwell DSc > On 30 Jun 2020, at 14:07, Ian Tickle <ianj...@gmail.com> wrote: > > > > I agree about RAID but I would go a lot further. There seems to be some > confusion here over the correct meaning of 'redundant' as used in a > scientific context. I don't think looking it up in an English dictionary is > very helpful. So as has been mentioned the non-scientific and rather > imprecise meanings are "not or no longer needed or useful; superfluous" or > "exceeding what is necessary or natural; superfluous" and "needlessly > repetitive; verbose". In fact both redundant and abundant have the same > Latin etymology, and redundant literally means 're' (again) + 'unda' (wave), > i.e. 'repeating as a wave'. The original meaning in English is in fact > 'over-abundant' and is still used in poetry with that meaning (e.g. "as > redundant as the poppies in the field"). There's of course also the meaning > 'dismissal from a job due to a need to reduce the head count' and from there > 'out of work', but that's relatively recent having been coined by a UK > Government official in the 1900s! > > The correct and totally precise scientific meaning which is appropriate in > the context of this discussion is to be found here: > https://en.wikipedia.org/wiki/Redundancy_(engineering) . Note that it > applies equally to both hardware and software engineering: > > Redundancy is the duplication of critical components or functions of a system > with the intention of increasing reliability of the system, usually in the > form of a backup or fail-safe, or to improve actual system performance. > > Nothing there about not or no longer needed or useful, superfluous, > needlessly repetitive, verbose! Note that 'multiplicity' totally fails to > carry the connotation of increasing the system reliability by duplication > (i.e. there are multiple copies but there's nothing that indicates the > justification for them). Redundancy occurs in TMR (triple modular > redundancy) systems used (as I guess Bernhard knows well) in triplicated > control systems in commercial aircraft. I don't know about you but I > wouldn't regard the extra two backup systems in TMR as 'not needed or useful' > when I'm an airline passenger ! > > https://en.wikipedia.org/wiki/Triple_modular_redundancy > > More is always better when it's critical: > > https://www.isa.org/standards-and-publications/isa-publications/intech-magazine/2003/october/more-is-always-better-when-its-critical > > There's also the question of the same word (redundancy, multiplicity or > whatever) having different meanings according to context. That's unavoidable > given that the number of concepts that we might want to name far exceeds the > number of words available, so we have to rely heavily on context when > assigning meaning. We don't say what the context is so the context must be > obvious and unambiguous. Whether we're talking about RAID or losing one's > job it's obvious what the intended meaning is from the context because the > contexts are totally separate. The important thing is that the contexts > should be well-separated so that no confusion is possible. Graeme says he's > not confused by the various meanings of 'multiplicity' but > non-crystallographer consumers of Table 1 surely might be! The various > contexts in which 'multiplicity' is used are certainly not well-separated and > overlap in program outputs and documentation, allowing plenty of scope for > confusion. > > In a scientific context 'redundancy' has a unique precise meaning whereas > 'multiplicity' has a multiplicity! > > BTW I use CCP4/Aimless and 'redundancy' (as you no doubt will have guessed, > because it's the word that unambiguously describes the concept), so > apparently I'm with you lot across the pond on this! > > Cheers > > -- Ian > > > >> On Tue, 30 Jun 2020 at 09:01, David Waterman <dgwater...@gmail.com> wrote: >> Reflections are as "redundant" as the disks in a RAID 0 array >> >>> On Tue, 30 Jun 2020, 02:49 James Holton, <jmhol...@lbl.gov> wrote: >>> What could possibly go wrong? >>> >>> -James Holton >>> MAD Scientist >>> >>> On 6/29/2020 6:17 PM, Edward A. Berry wrote: >>> > Now can we get rid of all the superfluous disks in our RAID? Or at >>> > least not replace them when they fail? >>> > >>> > On 06/29/2020 06:24 PM, Andreas Förster wrote: >>> >> I like to think that the reflections I carefully measured at high >>> >> multiplicity are not redundant, which the dictionary on my computer >>> >> defines as "not or no longer needed or useful; superfluous" and the >>> >> American Heritage Dictionary as "exceeding what is necessary or >>> >> natural; superfluous" and "needlessly repetitive; verbose". >>> >> >>> >> Please don't use the term Needless repetitivity in your Table 1. It >>> >> sends the wrong message. Multiplicity is good. >>> >> >>> >> All best. >>> >> >>> >> >>> >> Andreas >>> >> >>> >> >>> >> >>> >> On Tue, Jun 30, 2020 at 12:03 AM James Holton <jmhol...@lbl.gov >>> >> <mailto:jmhol...@lbl.gov>> wrote: >>> >> >>> >> I have found that the use of "redundancy" vs "multiplicity" >>> >> correlates very well with the speaker's favorite processing >>> >> software. The Denzo/HKL program scalepack outputs "redundancy", >>> >> whereas scala/aimless and other more Europe-centric programs output >>> >> "multiplicity". >>> >> >>> >> At least it is not as bad as "intensity", which is so ambiguous >>> >> as to be almost useless as a word on its own. >>> >> >>> >> -James Holton >>> >> MAD Scientist >>> >> >>> >> On 6/24/2020 10:27 AM, Bernhard Rupp wrote: >>> >>> >>> >>> > Oh, and some of us prefer the word 'multiplicity' ;-0____ >>> >>> >>> >>> Hmmm…maybe not. ‘Multiplicity’ in crystallography is context >>> >>> sensitive, and not uniquely defined. It can refer to ____ >>> >>> >>> >>> 1. the position multiplicity (number of equivalent sites per >>> >>> unit cell, aka Wyckoff-Multiplicity), the only (!) cif use of >>> >>> multiplicity____ >>> >>> 2. the multiplicity of the reflection, which means the >>> >>> superposition of reflections with the same /d/ (mostly powder >>> >>> diffraction) ____ >>> >>> 3. the multiplicity of observations, aka redundancy.____ >>> >>> >>> >>> While (a) and (b) are clearly defined, (c) is an arbitrary >>> >>> experimental number.____ >>> >>> >>> >>> How from (a) real space symmetry follows (b) in reciprocal space >>> >>> (including the epsilon zones, another ‘multiplicity’) is explained >>> >>> here ____ >>> >>> >>> >>> https://scripts.iucr.org/cgi-bin/paper?a14080 >>> >>> <https://urldefense.com/v3/__https://scripts.iucr.org/cgi-bin/paper?a14080__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-s72_nF7$> >>> >>> ____ >>> >>> >>> >>> and also on page 306 in BMC.____ >>> >>> >>> >>> Too much multiplicity might create duplicity… ____ >>> >>> >>> >>> Cheers, BR____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> Jon Cooper____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> On 23 Jun 2020 22:04, "Peat, Tom (Manufacturing, Parkville)" >>> >>> <tom.p...@csiro.au <mailto:tom.p...@csiro.au>> wrote:____ >>> >>> >>> >>> I would just like to point out that for those of us who have >>> >>> worked too many times with P1 or P21 that even 360 degrees will not >>> >>> give you 'super' anomalous differences. ____ >>> >>> >>> >>> I'm not a minimalist when it comes to data- redundancy is a >>> >>> good thing to have. ____ >>> >>> >>> >>> cheers, tom ____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> Tom Peat >>> >>> Proteins Group >>> >>> Biomedical Program, CSIRO >>> >>> 343 Royal Parade >>> >>> Parkville, VIC, 3052 >>> >>> +613 9662 7304 >>> >>> +614 57 539 419 >>> >>> tom.p...@csiro.au <mailto:tom.p...@csiro.au> ____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>> > -- >>> >>> >>> >>> *From:*CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK >>> >>> <mailto:CCP4BB@JISCMAIL.AC.UK>> on behalf of >>> >>> 00000c2488af9525-dmarc-requ...@jiscmail.ac.uk >>> >>> <mailto:00000c2488af9525-dmarc-requ...@jiscmail.ac.uk> >>> >>> <00000c2488af9525-dmarc-requ...@jiscmail.ac.uk >>> >>> <mailto:00000c2488af9525-dmarc-requ...@jiscmail.ac.uk>> >>> >>> *Sent:* Wednesday, June 24, 2020 1:10 AM >>> >>> *To:* CCP4BB@JISCMAIL.AC.UK <mailto:CCP4BB@JISCMAIL.AC.UK> >>> >>> <CCP4BB@JISCMAIL.AC.UK <mailto:CCP4BB@JISCMAIL.AC.UK>> >>> >>> *Subject:* Re: [ccp4bb] number of frames to get a full >>> >>> dataset? ____ >>> >>> >>> >>> ____ >>> >>> >>> >>> Someone told me there is a cubic space group where you can >>> >>> get away with something like 11 degrees of data. It would be >>> >>> interesting if that's correct. These minimum ranges for data >>> >>> collection rely on the crystal being pre-oriented, which is >>> >>> unheard-of these days, although they can help if someone is nagging >>> >>> you to get off the beam line or if your diffraction fades quickly. >>> >>> Going for 180 degrees always makes sense for a well-behaved crystal, >>> >>> or 360 degrees if you want super anomalous differences. Hope this >>> >>> helps a bit. ____ >>> >>> >>> >>> Jon Cooper____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> On 23 Jun 2020 07:29, Andreas Förster >>> >>> <andreas.foers...@dectris.com <mailto:andreas.foers...@dectris.com>> >>> >>> wrote:____ >>> >>> >>> >>> Hi Murpholino,____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> in my opinion (*), the question is neither number of >>> >>> frames nor degrees. The only thing that matters to your crystal is >>> >>> dose. How many photons does your crystal take before it dies? >>> >>> Consequently, the question to ask is How best to use photons. Some >>> >>> people have done exactly that.____ >>> >>> >>> >>> https://doi.org/10.1107/S2059798319003528 >>> >>> <https://urldefense.com/v3/__https://doi.org/10.1107/S2059798319003528__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-hiQXkxe$>____ >>> >>> >>> >>> >>> >>> All best.____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> __ __ >>> >>> >>> >>> Andreas____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> __ __ >>> >>> >>> >>> (*) Disclaimer: I benefit when you use PILATUS or EIGER >>> >>> - but I want you to use them to your advantage.____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> __ __ >>> >>> >>> >>> __ __ >>> >>> >>> >>> On Tue, Jun 23, 2020 at 12:04 AM Murpholino Peligro >>> >>> <murpholi...@gmail.com <mailto:murpholi...@gmail.com>> wrote:____ >>> >>> >>> >>> Hi. >>> >>> Quick question...____ >>> >>> >>> >>> I have seen *somewhere* that to get a 'full dataset >>> >>> we need to collect n frames':____ >>> >>> >>> >>> at least 180 frames if symmetry is X____ >>> >>> >>> >>> at least 90 frames if symmetry is Y____ >>> >>> >>> >>> at least 45 frames if symmetry is Z____ >>> >>> >>> >>> Can somebody point where is *somewhere*? ____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> ...also...____ >>> >>> >>> >>> what other factors can change n... besides symmetry >>> >>> and radiation damage?____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> Thanks____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>> > ---------- >>> >>> >>> >>> To unsubscribe from the CCP4BB list, click the >>> >>> following link: >>> >>> https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 >>> >>> <https://urldefense.com/v3/__https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-tcC1DQz$> >>> >>> >>> >>> ____ >>> >>> >>> >>> >>> >>> >>> >>> -- ____ >>> >>> >>> >>> Andreas Förster, Ph.D.____ >>> >>> >>> >>> Application Scientist Crystallography, Area Sales >>> >>> Manager Asia & Pacific____ >>> >>> >>> >>> Phone: +41 56 500 21 00| Direct: +41 56 500 21 76| >>> >>> Email: andreas.foers...@dectris.com >>> >>> <mailto:andreas.foers...@dectris.com>____ >>> >>> >>> >>> DECTRIS Ltd. | Taefernweg 1 | 5405 Baden-Daettwil | >>> >>> Switzerland | www.dectris.com >>> >>> <https://urldefense.com/v3/__https://www.dectris.com__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-gynYjCs$>____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> __ __ >>> >>> >>> >>> ____ >>> >>> >>> >>> LinkedIn >>> >>> <https://urldefense.com/v3/__https://www.linkedin.com/company/5067919__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-kAHivj7$>____ >>> >>> >>> >>> facebook >>> >>> <https://urldefense.com/v3/__https://www.facebook.com/pages/Dectris-Ltd/623855944369304__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-rsWJB_s$><https://urldefense.com/v3/__https://twitter.com/DECTRIS_News__;!!GobTDDpD7A!Z-SrnEqSZwQOXWOwbMCkZ1GB3fvdFuQ5lzYUYwQdUVTCALc3j9O3xqX7-j3aXyCU$>____ >>> >>> >>> >>> __ __ >>> >>> >>> >>> /Confidentiality Note: This message is intended only for >>> >>> the use of the named recipient(s)/____ >>> >>> >>> >>> /and may contain confidential and/or privileged >>> >>> information. 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