dissenting.
Litigation-induced assaults on the conduct of science and scientists, by aggressive advocates intent on destruction of reputation and property for private gain, produced the past “plague” of charges of “inequitable conduct.” A successful attack on the inventor or his lawyer will destroy the patent, no matter how valid the patent and how sound the invention. The uncertainties of the processes of scientific research, the vagaries of the inductive method, the complexities of patent procedures, and the twists of hindsight, all provided grist for this pernicious mill. Indeed, the prevalence of accusations of inequitable conduct in patent cases led judges to suspect that all scientists are knaves and all patent attorneys jackals. Today this court revives that misbegotten era.
The Federal Circuit, having observed the ease with which ordinary actions in scientific research or patent prosecution can be distorted by zealous attack, established the requirement that the attacker make clear and convincing showings of both material misrepresentation and de*1373ceptive intent. See Kingsdoum Medical Consultants, Ltd. v. Hollister Inc., 863 F.2d 867, 876, 9 USPQ2d 1384, 1392 (Fed.Cir.1988) (there must be clear and convincing evidence that material information was known to the inventor and was misrepresented or withheld for the purpose of deceiving or misleading the examiner into granting the patent). See also, e.g., Regents of the University of California v. Eli Lilly & Co., 119 F.3d 1559, 1570, 43 USPQ2d 1398, 1407 (Fed.Cir.1997); Scripps Clinic & Research Found. v. Genentech, Inc., 927 F.2d 1565, 1582, 18 USPQ2d 1896 (Fed.Cir.1991). Today the court casts this safeguard aside, finds misrepresentation in correct science, infers malevolence from verb tense, and grounds intent to deceive on personal slurs by a hostile witness.
These inventors made the discovery that the Thermus aquaticus enzyme has a quite different molecular weight and specific activity than had been reported in scientific publications of a decade earlier. The Taq enzyme isolated and characterized by Dr. Gelfand and Ms. Stoffel had an activity over ten times that of the Taq enzyme previously reported. This discovery led Cetus to commercial development of this important invention, with Promega obtaining a license. Now attempting to destroy the patent, Promega attacks the competence as well as the integrity of the inventors.
The patentability and validity of this discovery is not challenged. Instead, Promega charges the inventors with inequitable conduct in obtaining the patent, focused on two areas. First, Promega asserts that more experiments should have been done by the inventors than were done, particularly with respect to reproducing the prior art. Although Promega’s witnesses conceded that the inventors drew the correct conclusions, Promega argued successfully in the district court that they should have performed certain additional experiments and that their failure to do so established omission, misrepresentation, and deceptive intent. Although the majority opinion properly rejects these attacks with respect to molecular weight, they have accepted them with respect to other properties.
Second, the panel majority finds grounds of inequitable conduct in the presentation in the patent application of a specific example that was a combination of two chromatographic purification procedures but did not say so. It is undisputed that the example works as written and that it was included in the patent application because it was the best mode known to the inventors, who had previously distributed the procedure of this example to potential manufacturers. The panel majority holds that because the example was not written entirely in the present tense and identified as “prophetic,” this establishes, without more, both material misrepresentation and deceptive intent.
This case illustrates the ease of opportunistic challenge to the conduct of experimental science in patent context. My colleagues have distorted the patent process, and the science it supports, into a game of high stakes hindsight that few patents can survive. This additional risk to those who create valuable advances of science and technology has no countervailing public benefit, for the only beneficiary is the in-fringer who destroys the patent. I must, respectfully, dissent.
I
MOLECULAR WEIGHT
The panel majority has reversed the district court’s rulings of inequitable conduct based on molecular weight.1 I concur in *1374the majority’s decision with respect to this aspect, and remark only that this record well illustrates the litigation tactic of probing the hundreds if not thousands of experimental details, scrutinizing every experiment performed and not performed, criticizing everything done or undone, and then charging that the research process was somehow fraudulent, although there was no evidence of either misrepresentation or intent to deceive, and the validity of the claims is not challenged.
II
EXAMPLE VI
Example VI describes a five-column chromatographic purification procedure for the Taq enzyme. This five-column procedure had been distributed to potential contractors for commercial production, and was added to the specification in a continuation-in-part application in order to comply with the best mode requirement. There is no challenge to the district court’s finding that “Gelfand and Stoffel combined the steps from purifications numbered three and four to arrive at Example VI, which they considered the best method for purifying Taq.”
A. Example VI is Scientiñcally Accurate
Example VI as written was a combination of the chromatographic columns of two purification sequences designated as Prep 3 and Prep 4. Prep 3 was the three-column purification of the Taq enzyme through a phosphocellulose column, a heparin sepharose column, and a hydroxya-patite column. These are columns 1, 2, and 3 of Example VI. The product of Prep 3 had a specific activity of 248,000 units/ mg. Prep 4 used the same first two columns of Prep 3 plus a DEAE-Trisacryl column and a CM-Trisacryl column; these are columns 1, 2, 4, and 5 of Example VI. The product of Prep 4 had a specific activity of 390,000 units/mg. Thus Example VI combined the three columns of Prep 3 with the four columns of Prep 4 to form a five-column purification procedure, and described the product as having the properties of the preparations that it embodied. At the time of filing of the patent application, Example VI had not been run by the inventors as it was written.
The fatal flaw, according to the panel majority, is that the entire Example VI was not written in the present tense, the code for “prophetic” or “paper” examples in the Manual of Patent Examining Procedure. The Manual states that “simulated or predicted test results and prophetical examples (paper examples) are permitted,” and that the past tense should not be used for paper examples. MPEP § 608.01(p) (8th ed., 2001).2 Example VI was written in the past tense for the five chromatographic columns, and concluded by reporting some properties of the Taq enzyme in the present tense. E.g., “The results show *1375a single 88 kd band with a specific activity of 250,000 units/mg.” My colleagues rule that the use of the past tense, without more, is a material misrepresentation with deceptive intent.
Example VI is a faithful representation of the purification columns that were actually run. At trial Roche offered extensive evidence comparing the inventors’ experimental data to Example VI. There was no evidence, or suggestion, that Example VI did not work as stated. Promega’s expert Dr. Mosbaugh compared Prep 3 and Prep 4 to Example VI; he concluded that the inventors performed each of the chromatographic steps of Example VI, but stated that “it’s not just a matter of doing five steps. It’s important what those five steps are, the order in which they're carried out.” Dr. Mosbaugh testified that he could not predict how such a combination of chromatographic steps would perform, although he did not disagree with Dr. Chamberlin (expert witness for Roche) and Dr. Linn (expert witness for Promega), both of whom testified that the five-column purification procedure, using the third columns of Prep 3 with the four columns of Prep 4, would reasonably be expected to produce a product at least as pure as the four columns alone.
My colleagues simply err in stating that there was “no evidence” that Example VI was accurately projected from Preps 3 and 4. Indeed, the district court made no such finding. Although Dr. Mosbaugh stated that he was not capable of this projection, this admission, compared with the testimony of other witnesses including an expert for Promega, cannot be clear and convincing evidence that the inventors made a material misrepresentation for the purpose of deception, in making the accurate projection. The inventors believed, and so testified, that the combination of Preps 3 and 4 would be an optimum procedure, and added it to the disclosure because it was their best mode. The issue before the court was not whether Example VI had been performed in complete sequence; the issue was whether there was a misrepresentation material to patentability, and whether the misrepresentation was made in order to deceive the examiner into granting the patent. The ascribed material misrepresentation is not the data in the example, but only the use of the past tense. It was not disputed that the procedure and results of Example VI were supported by Roche’s experimental data.3 There was no proffered evidence of deceptive intent, or basis for such an inference, and no contradiction to the evidence that Example VI was added because the inventors believed it to be the best mode.
The panel majority has selected some parameters from Example VI that it describes as “Misrepresentations.” Inspection negates this description. For example, the panel majority designates as misrepresentations the statements that “a certain quantity of cells 'were resuspend-*1376ed in 75 ml of a buffer,’ that cells ‘were lysed in a French press,’ after which 300 ml. of Tris-EDTA ‘were added.’” Maj. op. at 1364. In Prep 3 the cells “were resuspended in 75 ml of a buffer,” the cells were “lysed in a French press,” and 395 ml of Tris-EDTA were added. The other criticisms by the panel majority are equally trivial, and at trial were devoid of even the accusation, much less proof, of deceptive intent.
Example VI was a protocol that had been written for use by manufacturers, and had been given to those manufacturers as instructions for commercial scale purification of Taq polymerase. The inventors explained that Example VI was the best mode and had already been distributed, explaining why Example VI was added to the specification. Evidence of the reason why an action was taken is highly relevant when fraudulent intent is charged. See Kingsdown, 863 F.2d at 876, 9 USPQ2d at 1392 (good faith must always be considered). The district court erred in ruling that “the fact that Example VI may have been a superior method of purification is irrelevant,” for it was the superior method that led the inventors to include it in the patent.
The panel majority finds that the purity values in Example VI were not actually obtained because Example VI was not actually run, and therefore challenges as fraudulent the statement that the product of Example VI has a specific activity of approximately 250,000 units/mg. As I have mentioned, the product of Prep 3 had a specific activity of about 248,000 and the product of Prep 4 had a specific activity of about 390,000 units/mg. Although the majority questions how specific activity was measured, it was undisputed that these activities are comparable and that the specific activity of the product of the Example VI procedure is at least as high as reported in Example VI.
It was also undisputed that the inventors’ statement to the examiner that “the present preparations [of Taq] are far more pure than the Chien et al. and Kaledin et al. preparations” was a true statement. The evidence was that Dr. Gelfand and Ms. Stoffel achieved approximately 8900-fold purification of Taq from the crude T. aquaticus extracts,, whereas Kaledin described 140-fold purification of his enzyme. Comparison with Chien was complicated by the addition of stabilizing protein in her final step, and her final fold purification was not calculated, but Chien had achieved less than 50-fold purification prior to her final column. Dr. Chamberlin testified that a 100-fold increase in purity in a single step — which would still leave Chien at less than half the purity of Gelfand— was greater than any effect he had seen. Promega did not challenge Roche’s evidence that Chien’s preparation could not possibly have reached the purity levels of the inventors. Although the panel majority disputes the statement that the Example VI purity is “more than an order of magnitude [ten times] higher than that claimed for the previously isolated Taq polymerase and at least an order of magnitude higher than that for E. coli polymerase,” '818 patent, col. 41, lines 17-20, the prior art activities of 118.7 units/mg for the Chien Taq polymerase and 7,658 units/mg for the Kaledin Taq polymerase were conceded by Promega’s witnesses to be less than one tenth that of the product of Example VI, however activity was calculated. And there was no challenge to the accuracy of the inventors’ statement comparing the activity of the Example VI Taq polymerase with that of E. Coli polymerase.
The district court found that the examiner “did not indicate in any way that she considered the greater purity of the Cetus enzyme to be a basis for patentability.” Nonetheless, the statement of “single band purity” of the product of Example VI is *1377raised by the panel majority as grounds of inequitable conduct. The district court found that Prep 4 “very nearly yielded a single band,” and referred to the evidence that “faint bands” evident in these preparations are not contaminating proteins but are shorter forms of the Taq enzyme that are artifacts of the purification process. The evidence that these procedures achieved “essentially a pure protein” stands undisputed. Also, someone of skill in this art would understand the statement that the purified fractions were “nuclease free” to indicate that nuclease was not detected over background levels, according to Promega’s expert Dr. Linn, who explained that he instructs his graduate students to state nuclease activity as “less than” a particular value to avoid the phrase “nuclease free.” I take note that nuclease activity was not an issue during prosecution, and that for these properties there was no evidence of material misrepresentation with intent to deceive the examiner.
B. Constructive Reduction to Practice
Example VI is not really a “paper example,” as the term is normally used, for Example VI is a combination of actual experiments. However, even if any example that was not performed precisely as written were deemed to be a “paper example,” such examples have long been accepted in patent documents, unlike their prohibition in scientific articles. Paper examples meet the practical need of compliance with the requirement for specific embodiments of every invention, as well as with aspects of patent law such as the need to provide a full range of variables or to describe and enable alternatives or equivalents. To fulfill their legal purpose, such examples must be enabling of specific embodiments. For some inventions the detailed embodiments can be described and enabled by the inventor without conducting full laboratory experiments or building entire machines. The patent law authorizes that an invention may be constructively reduced to practice by filing a patent application, whether the embodiments were actually made or are constructed in the patent application.
“Constructive reduction to practice” is a legal status unique to the patent art. Unlike the rules for scientific publications, which require actual performance of every experimental detail, patent law and practice are directed to teaching the invention so that it can be practiced. The inclusion of constructed examples in a patent application is an established method of providing the technical content needed to support the conceived scope of the invention. The Manual of Patent Examining Procedure implements this legal status and purpose, in its explicit recognition that “simulated or predicted test results and prophetic examples (paper examples) are permitted.” MPEP § 608.01(p). Although the MPEP states that the present tense should be used for such examples, see n. 2 supra, patenta-bility does not depend on whether the example was actually conducted. The presentation of accurate “constructive” descriptive and enabling information in the specification, whether or not marked as “prophetic,” is not material misrepresentation with culpable intent. Indeed, were there negligence on the part of the inventors in presenting most of Example VI in the past tense, it is established law that negligence alone, even gross negligence, does not establish inequitable conduct. Kingsdown, 863 F.2d at 876, 9 USPQ2d at 1392.
It is not scientifically improper to gather knowledge from separate experiments and to draw scientific conclusions based thereon; that is the methodology of science. It is not a legal misrepresentation to fuse knowledge from various sources, drawing *1378on one’s skill and experience. Although Dr. Mosbaugh testified that: “As an enzy-mologist, I cannot fuse these [Prep 3 and Prep 4] together and get any prediction as to what the outcome would be,” these inventors did fuse them and did predict the outcome. It is not inequitable conduct to have superior knowledge and experience, and to use them to successfully predict the scientific result. Precedent recognizes that whether an example was performed precisely as written does not establish materiality or deceptive intent. In Regents v. Eli Lilly the court considered specific examples (written in the past tense) that differed from the experiments actually performed, but found no inequitable conduct despite the applicant’s modification of the experimental details. 119 F.3d at 1570, 43 USPQ2d at 1407 (“There is no reason to believe that a reasonable examiner would have made any different decision if UC had framed Examples 4 and 5 as constructive examples.”) In Atlas Powder Co. v. E.I. du Pont De Nemours & Co., 750 F.2d 1569, 1578, 224 USPQ 409, 415 (Fed.Cir.1984) the entire text of the patent is in the present tense (including all examples), the court holding that when “all but one of the examples were based on actual experiments and only slightly modified to reflect the inventor’s notion of the most effective formulation,” the inventor’s “failing to tell the examiner that the examples were ‘prophetic’ ” is not inequitable conduct. The district court agreed that the properties of the Taq polymerase described in Example VI were not significantly different from the properties of the products of Prep 3 or Prep 4. There was no evidence that the examiner might have decided differently as to patentability had the examiner known the origin of Example VI.
Even were Example VI deemed not to be in impeccable compliance with the protocol of the Manual of Patent Examining Procedure, this is not material misrepresentation and deceptive intent. Inventors Gelfand and Stoffel were interrogated at length concerning their use of verb tense. They testified that they were not aware of the protocol of using the present tense in patent examples, and that Example VI was provided to comply with the best mode requirement. The panel majority misconstrues this testimony: Dr. Gelfand did not state that he knew of (and thus deliberately violated) the patent protocol of past and present tense, as he distinguished scientific writing from the “arcaneness” of patent documents. Dr. Gelfand was persistently asked, over many pages of the trial transcript, whether he understood the significance of verb tense in scientific publications, as Promega attempted to impugn the scientific integrity of the inventors. The following exchanges are typical:
Mr. Troupis (Promega’s attorney): So when you used the term “was” or “were,” you understood, did you not, that that communicates that you had done it? You understood that; did you not, Dr. Gelfand?
Dr. Gelfand: We’re coming to an area that deals with prophetic examples and arcaneness, and I—
Mr. Troupis: I’m not coming to anything with regard to the law. I’m coming to the facts, Dr. Gelfand. I’m simply asking you: when you used those terms, “was,” “were,” or the like, you mean you actually did it; don’t you? When you used those terms as a scientist, that’s what you mean, you did it?
Dr. Gelfand: We did many, many of the things described. The “was” is absolutely correct....
Mr. Troupis: I want this record to be clear. No one did Example VI before June of 1987 — That’s a “yes” or “no” question, Dr. Gelfand — isn’t that right?
*1379Dr. Gelfand: I believe that’s correct.
Mr. Troupis: Yet you put in the patent that you or somebody had done it; isn’t that right?
Dr. Gelfand: We put in the patent in the description, in Example VI, what I believed to be the best way to go about isolating Taq DNA polymerase at the time.
Mr. Troupis: You used the tense, the past tense, in Example VI indicating you had done it, and in a scientific publication that means you did it, it doesn’t mean you hoped for it, it means you did it; doesn’t it, Dr. Gelfand?
Dr. Gelfand: In a scientific publication, yes.
Mr. Troupis: You chose at that time not to tell the patent office what you had done, but chose to tell them something you had not done? You just indicated you made a conscious decision to tell them something you had not done and tell them in a way as if it had been done; isn’t that right?
Dr. Gelfand: No. It was my understanding that we had an obligation to tell the Patent Office what we believed to be the best way of [purifying Taq] drawing on the experience from the third prep, drawing on the experience from the fourth prep and describing for the Patent Office, for the world, the best way we thought to go about doing it. That’s what I believed.
Ms. Stoffel was similarly interrogated. The panel majority now faults the inventors for not explaining why a different principle applies in patent applications than in scientific articles. Indeed, the differences between scientific and patent practice are commonly misunderstood. However, the patent use of constructed examples is not a material misrepresentation, whether or not the examples are designated as constructed; and the provision of accurate science in the wrong verb tense does not establish deceptive intent. Such findings, which require the elements of common law fraud, are measured by objective reasonableness. Telling the truth, even in the past tense, cannot be a material misrepresentation or clear and convincing evidence of deceptive intent.
Ill
FIDELITY AND ACTIVITY
The panel majority also finds grounds of inequitable conduct because the inventors, in comparing their Taq polymerase with the Chien and Kaledin published properties of the prior art Taq, did not repeat the prior art procedures. Indeed, it is facile to ascertain what experiments were not done, and then to argue that they should have been done, on risk of invalidating the patent for inequitable conduct. My colleagues hold that the inventors should not have stated that their products were superior, in activity and in fidelity, to the products reported in the publications of Chien and Kaledin, because the inventors should not have relied on the data in those publications without duplicating them. The publications of Chien and Kaledin included the specific activities of their products as well as the molecular weights, and the methods of measurement. There was no evidence that these data were incorrect; the only charge was that the prior art could not “legitimately” be compared.
There was no evidence that the published assays of Chien and Kaledin were incorrect for their products, or should have been suspected to be materially different from the published values. Indeed, the evidence was undisputed that the Chien and Kaledin products were degraded, as Gelfand and Stoffel discovered, and that the properties reported for this early work were for degraded products. There was *1380no evidence that the improvements in assay conditions over the ensuing decade would have altered the dramatic difference between the activities of 118.7 units/mg and 7,658 units/mg reported by Chien and Kaledin respectively, and the activities found by Gelfand and Stoffel for their un-degraded enzyme. Indeed, the examiner did not question the inventors’ comparisons of activity with the prior art, although the examiner did question the molecular weight comparisons. While Promega places emphasis on the evolution of precision in measurement of Taq polymerase activity, and on an apparent uncertainty in Ms. Stoffel’s recollection at trial of the details of assay procedures used at various times, it is not disputed that the magnitude of the claimed differences in activity was correct.4 No information is asserted to have been withheld from the examiner. The findings of materiality and deceptive intent in the comparison of activity are devoid of any support.
Similarly, the panel majority challenges the comparisons of fidelity and template dependency. The only evidence on this issue was the testimony of Promega’s expert Dr. Kunkel. He testified that it was scientifically unacceptable for Dr. Gelfand to have compared his results with the prior art. Dr. Kunkel stated that “[the results] don’t lead me, and I don’t think they would lead any correct-thinking scientist, to conclude that those results can be fairly compared to what was done with activated DNA. It simply is not a scientifically valid comparison to make.” Dr. Kunkel testified that “It is certainly not a scientifically-valid statement to say that based on this information, that the patented enzyme was far superior to the prior art in this regard .... It’s simply not correct scientific principles.” He compared the statements in the patent concerning fidelity to “scientific misconduct,” and designated them as “intentional misrepresentations.” He stated that the inventors should have duplicated the prior art in order to conduct a side-by-side comparison. The district court asked:
The court: In your view is Dr. Gelfand a fraud?
Dr. Kunkel: Yes. In B on the issues related to this case, yes.... And he knew better.
Thus the witness challenged the inventors’ integrity and competence, although it was undisputed that their conclusions were correct.5 My colleagues adopt these specious charges of scientific fraud although neither inaccuracy nor falsity of any data was shown. It is not a material misrepresentation with intent to deceive, for an inventor to use his/her knowledge and experience to reach a reasonable conclusion.
The panel majority appears to misunderstand the statements in the specification and during prosecution. The patent states that the inventors’ results “are consistent with” a high fidelity polymerase, and that the activity reported by Kaledin “is not consistent with the expected value and suggests misincorporation of nucleo*1381tide triphosphate(s).” The inventors explained to the examiner that Chien and Kaledin’s data “would lead one of ordinary skill in the art to conclude that” the prior products “are not suitable for template-directed in vitro DNA synthesis” and “have a rather substantial promiscuous ability to synthesize DNA in the absence of one of the four deoxynucleoside triphosphate.” Response, March 17, 1989. It is undisputed that the inventors’ data were accurately presented. Dr. Kunkel’s charge that Dr. Gelfand “knew better” is mysterious indeed, when despite this inflammatory testimony, the district court found as fact that: “Evidence adduced by the inventors led them to believe that the prior art had generated something other than that which the inventors purified.” No error has been asserted in this finding. A hostile witness’ flashy challenge to the inventor’s personal integrity is not probative of anything.
IV
THE NEW PLAGUE
Of course patent applicants must conduct themselves with honesty and integrity. However, unwarranted charges of inequitable conduct can infect the entire body of invention and inventors. As illustrated in this case, every experiment done and not done, every scientific inference, every judgment or belief, is fair game for opportunistic attack. Such attacks feed upon the complexities of science and technology, and it is rare indeed that some flaw cannot be found. In this case, straightforward scientific and patent activity were distorted until judicial suspicions were raised, despite the absence of any significant error or misstatement. The actions challenged herein, even if viewed in their worst light (whatever that might be) do not establish material misrepresentation and intent to deceive. The need for attention to the burden of proof and its requirement of clear and convincing evidence of both material misrepresentation and deceptive intent, is forcefully illustrated.
. Only molecular weight is included in the claims. Claim 1 follows:
*13741. Purified thermostable Thermus aquati-cus DNA polymerase that migrates on a denaturing polyacrylamide gel faster than phosphorylase B and more slowly than does bovine serum albumin and has an estimated molecular weight of 86,000-90,000 dal-tons when compared with a phosphorylase B standard assigned a molecular weight of 92,500 daltons.
. § 608.01 (p). Simulated or predicted test results and prophetical examples (paper examples) are permitted in patent applications. Working examples correspond to work actually performed and may describe tests which have actually been conducted and results that were achieved. Paper examples describe the manner and process of making an embodiment of the invention which has not actually been conducted. Paper examples should not be represented as work actually done. No results should be represented as actual results unless they have actually been achieved. Paper examples should not be described using the past tense.
. Roche’s expert witness Dr. Chamberlin was comparing Prep 4 to Example VI when the district court cut off the testimony:
The court: This whole line of questioning you’ve shown the consistency between the notebooks and what's on the flowchart, and what's on the flowchart and the patent. And so what's the point you're making?
Roche Attorney: That this fourth purification scheme in fact leads to a preparation that meets the purity levels that were already to the Patent Office.
The court: And I ask you again, what is the significance of that?
Roche Attorney: That the inventors had, in fact, performed a purification run where they obtained preparations of significantly high purity, that they could make the arguments that they made to the Patent Office, your honor.
The court: All right. Well, I think you've made your point without belaboring it.
. The district court re-calculated the specific activity data to accord with the definition of "unit” in Example VI. The Chien and Kaledin publications both define "unit” in accordance with the inventors' raw data, supporting the inventors’ activity number of 250,000 units/ mg. By any of the calculation methods presented at trial, whether that of Cetus, Prome-ga, or the district court, there was at least a ten-fold improvement of unit activity, as described in the patent in suit.
. In support of Dr. Kunkel's charges of scientific fraud based on his asserted personal knowledge of what Dr. Gelfand knew of the science, the panel majority reports that Dr. Kunkel "worked with Dr. Gelfand and Cetus” during 1986-1989. When cross-examined, Dr. Kunkel admitted that the extent of his contact with Cetus was a single visit in 1988 to deliver a seminar.