========================================================================= Date: Wed, 10 Jul 2002 19:16:18 -0600 Reply-To: cassie@tekcomm.com Sender: Radiocarbon Mailing List From: Cassie Hemphill Subject: Volunteer Position Announcement -- TAC Needs Your Help MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Volunteer Position Announcement: Assistant Underwriting Coordinator, Archaeological Legacy Institute Background: Underwriting, the nonprofit form of sponsorship, is key to the fundraising strategy of The Archaeology Channel (www.archaeologychannel.org), our streaming-media public-education website. Strong growth in our audience (now 600,000 hits/month from 45,000 individual visitors) has moved TAC to the upper ranks of archaeology websites worldwide. The size of our audience also makes us more attractive to prospective underwriters. To realize the potential of this form of financial support, we must make a concerted effort to reach companies and organizations who may be inclined to join with us as underwriting partners. We are seeking a qualified volunteer to assist our volunteer Underwriting Coordinator, Dr. Guy Prouty, in his efforts to expand our Underwriting Program. Duties: Work with Underwriting Coordinator in prospecting for and communicating with underwriters. Help develop underwriting prospect list. Contact and communicate with prospective and existing underwriters. This involves making daytime telephone calls (Monday-Friday) to prospects on the list. Work from your own home or office. Qualifications: Marketing experience. Communication skills. Archaeological background preferred but not absolutely required. Must be willing to introduce TAC to companies and organizations over the telephone. Must be able to spend 5-10 hours per week on this task. Deadline: 20 July 2002 To apply: Send brief e-mail message expressing interest along with attached or appended resume to Dr. Guy Prouty (mailto:guyprouty@msn.com), Underwriting Coordinator, Archaeological Legacy Institute Posted by: Richard M. Pettigrew, Ph.D., RPA President and Executive Director Archaeological Legacy Institute www.archaeologychannel.org =========== Forwarded by: Cassie Hemphill mailto:cassie@tekcomm.com Volunteer List Serve Coordinator for TAC =========================================================================== To unsubscribe from this list, send the command SIGNOFF C14-L to LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to C14-L-request@LISTSERV.ARIZONA.EDU. ========================================================================= Date: Mon, 22 Jul 2002 12:23:34 -0400 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: "Brown, Clifford Dr. (NAVFACHQ)" Subject: Combining C14 dates MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Co-listeros: Does anyone have any good references on the processes and principles of combining multiple radiocarbon dates from the same sample or the same event to increase the precision of the dating estimate? Many thanks! Clifford T. Brown ------------------------------------- Clifford T. Brown, Ph.D. Voice - (202) 685-9193 (DSN 325) Fax - (202) 685-1577/1581 =========================================================================== To unsubscribe from this list, send the command SIGNOFF C14-L to LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to C14-L-request@LISTSERV.ARIZONA.EDU. ========================================================================= Date: Tue, 23 Jul 2002 11:47:22 -0700 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Paula Reimer Subject: Re: Combining C14 dates In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Dear Dr. Brown, The method presented in Ward and Wilson, 1978 (Archaeometry 20:19-31) has become the standard for comparing and combining multiple radiocarbon dates. Calibration programs such as Calib (www.calib.org) and Oxcal (www.rlaha.ox.ac.uk/orau) provide this feature. However, the method for testing whether sample radiocarbon ages are statistically the same and can be combined was developed prior to high-precision calibration data-sets. It does not take into account the resulting distortions in calibrated distributions. If anyone knows of a method for testing samples for contemporaneity based on the calibrated distributions, I would very much like the reference. Cheers, Paula Reimer At 12:23 PM 7/22/2002 -0400, you wrote: >Co-listeros: > >Does anyone have any good references on the processes and principles of >combining multiple radiocarbon dates from the same sample or the same event >to increase the precision of the dating estimate? > >Many thanks! > >Clifford T. Brown > >------------------------------------- >Clifford T. Brown, Ph.D. >Voice - (202) 685-9193 (DSN 325) >Fax - (202) 685-1577/1581 > >============================================================================ >To unsubscribe from this list, send the command SIGNOFF C14-L to >LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to >C14-L-request@LISTSERV.ARIZONA.EDU. Dr. Paula Reimer Center for Accelerator Mass Spectrometry L-397 Lawrence Livermore National Laboratory P.O. Box 808 Livermore, CA 94550 Phone: (925) 422-7151 FAX: (925) 423-7884 email:pjreimer@llnl.gov =========================================================================== To unsubscribe from this list, send the command SIGNOFF C14-L to LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to C14-L-request@LISTSERV.ARIZONA.EDU. ========================================================================= Date: Thu, 25 Jul 2002 14:23:56 +0100 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Bernhard Weninger Subject: Re: Combining C14 dates MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Dear Clifford, Your question obviously goes to the very heart of the 14C calibration problem and is not at all easy to adress. I wrote my entire PhD on such things some 10 years ago (sorry: in German), and will provide a briefer effort here in a few lines. I have no solution, but hope to be able at illucidate the problem. Allow me to follow up on what Paula Reimer already wrote: the standard procedures for combining multiple conventional 14C-ages are described by Ward and Wilson (1978) in Archaeometry 20 p 19-31. These procedures produce a weighted average, the requested smaller standard error, and a corresponding test-statistic, all on the 14C-scale. All this works nicely for 14C measurements on the same sample, and the result can be calibrated using largely standardised procedures, e.g. as implemented in much of the software on the www.radiocarbon.org/ site. As a result, we get a list of alternative calendric-age readings. The next step resp. idea is to analyze 14C measurements performed not on the same sample, but on samples we know (judge) to be of the same calendric age. If we simply calibrate them one after another, we just get some extended list of alternative cal-age readings, which - even when stacked/graphed - (e.g. via histogram method) do not help much in terms of reducing the number of alternative readings, nor does such stacking reduce the length of the overall cal-age interval. The histogram may give us a nice picture of the spread of the 14C-data, on both time-scales. But how do we get at the refined cal-scaled dating precision we know MUST (?) exist with multiple 14C-measurements on the same event(s) ? There is an article by H.Ottaway, back in the 70's, nicely describing the dilemma, which I abbreviate: the more dates we get, the wider the distribution. Let us look closer at this (actually mind-boggling) problem. To illustrate, take two 14C-ages A and B and define a calibration operator "cal". The normal "averaging" would be something like the equation "cal(A+B) = cal(A) + cal(B)" or any arithmetic variant e.g. cal(A/2+B/2) = cal((A+B)/2) = 1/2*cal(A+B). But for 14C ages this equation is not valid, due to the multiple calcurve-readings. It makes a difference whether we average on the 14C-scale or on the calendric-time scale. -> The cal-operator is non-commutative. It turns out, therefore, in 14C we have to do with a very special class of "probabilities", the underlying axioms of which are neither classical nor Bayesian but instead accord to a non-commutative algebra of type similar to (although not quite as fundamental as) that underlying quantum mechanics. But there has been little discussion on such fundamental aspects of radiocarbon analyis and assumedly very different opinions may exist here. To conclude, there is no solution to the problem you adress. But we have available a lot of work-around solutions. Sincerely Bernie Weninger ************************************ Dr. Bernhard Weninger Radiocarbon Laboratory Institut der Ur- und Frühgeschichte Weyertal 125 D-50923 Köln Tel (+) 221 470 2880 Fax.(+) 221 470 4892 Site http://www.calpal.de/ ************************************ =========================================================================== To unsubscribe from this list, send the command SIGNOFF C14-L to LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to C14-L-request@LISTSERV.ARIZONA.EDU. ========================================================================= Date: Fri, 26 Jul 2002 09:05:22 +0200 Reply-To: Radiocarbon Mailing List Sender: Radiocarbon Mailing List From: Maarten Blaauw Subject: Re: Combining C14 dates In-Reply-To: <3D3FFBEC.BFC92821@uni-koeln.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" ; format="flowed" There's a recent paper in the Holocene, discussing the problem of combining 14C dates: Bennett, K.D., and Fuller, J.L., 2002: Determining the age of the mid-Holocene Tsuga canadensis (hemlock) decline, eastern North America. The Holocene 12(4): 421-429. -- ------------------------------------------------------------------ Maarten Blaauw, PhD student in palaeo-ecology Institute for Biodiversity and Ecosystem Dynamics (IBED) Research Group Palynology and Paleo/Actuo-ecology * Faculty of Science, Universiteit van Amsterdam Postal address: IBED, P.O.Box 94062, 1090 GB Amsterdam, the Netherlands (Visiting address: Kruislaan 318, Building I, Room B114) E-mail: blaauw@science.uva.nl Phone: +31 20 525 7666 Fax: +31 20 525 7832 Private phone: +31 75 635 5775 *Member of Graduate School 'Centre for Geo-ecological Research' (ICG) ------------------------------------------------------------------ =========================================================================== To unsubscribe from this list, send the command SIGNOFF C14-L to LISTSERV@LISTSERV.ARIZONA.EDU, or send a request to C14-L-request@LISTSERV.ARIZONA.EDU.