Elevators or stairs?

Background:

Staff in hospitals frequently travel between floors and choose between taking the stairs or elevator. We compared the time savings with these two options.

Methods:

Four people aged 26–67 years completed 14 trips ranging from one to six floors, both ascending and descending. We compared the amount of time per floor travelled by stairs and by two banks of elevators. Participants reported their fatigue levels using a modified Borg scale. We performed two-way analysis of variance to compare the log-transformed data, with participant and time of day as independent variables.

Results:

The mean time taken to travel between each floor was 13.1 (standard deviation [SD] 1.7) seconds by stairs and 37.5 (SD 19.0) and 35.6 (SD 23.1) seconds by the two elevators (F = 8.61, p < 0.001). The difference in time taken to travel by stairs and elevator equaled about 15 minutes a day. Self-reported fatigue was less than 13 (out of 20) on the Borg scale for all participants, and they all stated that they were able to continue their duties without resting. The extra time associated with elevator use was because of waiting for its arrival. There was a difference in the amount of time taken to travel by elevator depending on the time of day and day of the week.

Interpretation:

Taking the stairs rather than the elevator saved about 15 minutes each workday. This 3% savings per workday could translate into improved productivity as well as increased fitness.Open in a separate windowImage courtesy of © Thinkstock 2011The areas visited by hospital staff in internal medicine are often on different floors, with staff making multiple trips by stairs or elevator each day. The reasons for choosing to take the elevator over the stairs include concerns about dyspnea and fatigue, and the amount of time saved.Although many people feel that taking the elevator saves time, there is little evidence to support this claim. We compared travel times for staff taking elevators and stairs in a typical urban hospital.     

Heterosis or Neutrality?

Various statistics have been proposed on an ad hoc basis to test whether alleles at a locus are selectively neutral. By considering population models in which selection operates, this paper shows that the population homozygosity is a powerful test statistic for testing departures from neutrality, in the direction of heterozygote advantage or disadvantage. The sample homozygosity plays a similar role when only sample data are available. Some numerical examples are included, showing the application of the test.—An analysis is made of the effect of heterosis on such quantities as the expected number of alleles in the population or sample, the effective number of alleles, the expected homozygosity, and on the population and sample allele frequency distributions generally.     

Lost or forgotten?

Bonobo, the Forgotten Ape by F. de Waal University of California Press, 1997. ￡39.95 hbk (210 pages) ISBN 0 520 20535 9.     

Enzyme or Electrode?

The process of dissimilatory metal reduction shapes our environment on a global scale by using minerals as terminal acceptors in a biological electron transport chain employed by bacteria under anaerobic conditions. In this issue of Structure, Edwards et?al. present the structure of an extracellular undecaheme cytochrome involved in the step of electron transfer to metal oxides.     

Science or alchemy?

Hyperbole has become a common and accepted practice in science nowadays. We sell our results, we hide our ignorance and we use stock terms that gain spurious weight through repeated use. I illustrate from the field of developmental genetics.     

6 or 9?

In this article the author offers an original interpretation of patterns found on the world's most ancient felts (Fifth Century BCE). These artifacts have been recovered from frozen burial mounds in the Altai Mountains. The interpretation presented here constitutes a new approach to the study of ornamentation as a system of symbols.