Basic Scientific Writing in English

Lecture 7

Professor Ralph Kirby

Faculty of Life Sciences

Extension 7323

Room B322

Active and passive voice for verbs

Inter-converting tenses between English and Chinese has many

problems• Past, present and future can rely solely on

context in Chinese. In English, it must be specified

• Whether the action has been completed or is intended to be completed is central to Chinese and has no real equivalent in English

• The passive voice of a verb has no real equivalent in Chinese

Active and Passive Voice

• He studies the book. He studied the book. He will study the book.– These are all active voice as the person is directly

involved

• The book is studied by him. The book was studied by him. The book will be studied by him.– These are all passive voice as the subject of the

sentence, ‘the book’ is acted on by someone

• Classically in science:– “The following results were obtained . . . . .”

– “We obtained the following results . . . . .”

– Which is active and which is passive”

• British English scientists tend to overuse the passive compared to American English scientists. Chinese 1st language speakers very rarely use the passive when writing a paper

• Grammar checkers will highlight all passives as wrong?

• Is the passive voice always wrong. No!

• Some scientists would say that you should never use the passive voice. I disagree

• You should avoid using the passive unless you have a reason to use it because it uses more words and can make what you mean more confusing

When to use the passive• When you cannot avoid it

– The baby was born in the Maternity Hospital

– The mother bore the baby in the Maternity Hospital• The 2nd sentence means the same, but is longer and reads poorly

– The Petri dishes were made of plastic

– The manufacturer made the Petri dishes out of plastic• Not the same meaning. Better still, “ Plastic Petri dishes”

• Why have I used “Petri” rather than “petri” in the middle of the above sentences? The word “petri” is highlighted by the spell-grammar checker!

• Emphasis– When you want to make the action rather than

the agent of the action the most important• Streptomycin, the first effective antibiotic against

tuberculosis, was discovered by Waksman

• Waksman discovered streptomycin, the first effective antibiotic against tuberculosis.

• When the agent is unknown or unimportant– Darwin most important work was published in

1859– X published Darwin’s most important work in

1859

Rules for tense in scientific papers• 1) When referring to previously published work, the results

have become knowledge and are “true”. Use the present tense– Streptomycin inhibits M. tuberculosis

• 2) When referring to your own work, in general use the past tense because it is not yet published– Under the conditions described earlier, streptomycin did not inhibit M.

tuberculosis

• 3) Except!– In the Abstract

• Because the abstract refers to the published paper

– When presenting results as figure or tables• Because these are visible to the reader at the present time

– When presenting calculations or statistics• Because these results do not change

– When stating a known truth• Water is wet

Rules for using the person in scientific papers

• Which should you use?– We showed that streptomycin inhibited M. tuberculosis

• Personal. More common than it used to be. Some journals use it more than others. Can be very repetitive if used to much

– It was shown that streptomycin inhibited M. tuberculosis• None specific impersonal. Used a lot in many papers. Disadvantage,

does not say who it was shown by and when was this shown

– The results showed that streptomycin inhibited M. tuberculosis• General impersonal. Say where the information came from in general.

Disadvantage, not highly specific

– From Figure 1, it can be seen that streptomycin inhibits M. tuberculosis

• Specific impersonal. Say exactly where the information can be found.

• Use the personal “we”, “I”, “this research group” etc. when drawing an important conclusion. – Do not use it in the Materials and Methods.– Use it very rarely in the Introduction. – Use it sparingly in the Results.– Use it most in the Discussion

• Do not use none specific impersonal• Use general impersonal if you have made

clear what results or experiments you mean.• Use specific impersonal as much as

necessary

• Examples. Change from active to passive– We examined the Southern blots for radioactive

bands– Our research group used radioactivity to detect the

protein– I detected a virus in the meat sample by PCR

• Examples. Change from passive to active– It might be expected that the treatment would be

effective– Inoculation was performed on 25 chickens– A trip for the purpose of collecting insects was

made in July 2002

More real examplesConvert them, passive to active and

let us decide which is better• In this study a non-equilibrium approach was used to

discriminate between sequences• The binding of the Lac-GFP fusion protein to

tandem lac operator repeats was exploited to detect the origin of replication

• Extensive genetic variation among strains was identified using DNA microarrays

• DNA microarrays have been used to compare interstrain and interspecific variation in bacteria

And even more real examplesConvert them, active to passive and

let us decide which is better

• We have conducted a survey of nine Shewanella species and assessed their relatedness to Shewanella oneidensis

• We discuss both the size and the nature of the contents of the Sodalis genome and it is compared to E. coli

• Most obligate intracellular bacteria are strictly vertically transmitted to the progeny

• Kuipers et al studied pairs of isolates of H. pylori, obtained 7-10 years apart, using RAPDS