Vegetative propagation of the red alga Rhodochorton purpureum by means of fragments that escape digestion by herbivores

Intertidal populations of the filamentous red alga Rhodochorton purpureujn (Lightf.) Rosenv. (Nemaliales, Acrochaetiaceae) in the Northern Netherlands grow as dense velvety turfs in the understory of large fucalean algae. The small and rather constant size of the turf (1 to 1.5 mm) and the high percentage of 'decapitated' filaments suggest that the turf is continually 'shorn' by herbivores. Two grazing invertebrates were found on the turf: the gastropod Littorina littorea (L.) and the amphipod Gamrnarus salinus Spooner Differences between the 2 grazers in the size of ingested R. purpureum fragments and in the proportion of ingested fragments with intact apices were attributed to differences in their feeding mechanisms. Both species egested live R. purpureum fragments In their faecal pellets. These fragments had the capacity to regenerate into new filaments when cultured in the laboratory. In the field small tufts of R. purpureurn filaments were found on bare substratum, originating from fragments contained in sticky, detritus-rich envelopes, probably faecal pellets. Experiments in unlalgal cultures showed that the regeneratlve capacity of fragments is very high, as it proceeds over d broad range of temperature and light conditions, even in total darkness We conclude that the capacity of R. purpureum fragments to escape digestion by herbivores probably plays an important role in vegetative propagation of the species

Nothing moves a surface: vacancy mediated surface diffusion

We report scanning tunneling microscopy observations, which imply that all atoms in a close-packed copper surface move frequently, even at room temperature. Using a low density of embedded indium `tracer' atoms, we visualize the diffusive motion of surface atoms. Surprisingly, the indium atoms seem to make concerted, long jumps. Responsible for this motion is an ultra-low density of surface vacancies, diffusing rapidly within the surface. This interpretation is supported by a detailed analysis of the displacement distribution of the indium atoms, which reveals a shape characteristic for the vacancy mediated diffusion mechanism that we propose.Comment: 4 pages; for associated movie, see http://www-lion.leidenuniv.nl/sections/cm/groups/interface/projects/therm

La Opinión : periódico político: Año I Número 7 - (18/08/95)

Abstract Background After on-scene examination and /or treatment, emergency medical services (EMS) nurses must decide whether the patient requires further assessment or treatment, most frequently in a hospital. The primary objective of this study was to assess the reliability of the current EMS protocol by determining whether the decision not to transport the patient to a care provider was correct or not. Methods Adults receiving on-scene medical care by an EMS rapid responder or full team without transport to the hospital were included in this prospective observational study. The primary outcome measure was secondary consultation within 24 h after an on-scene EMS evaluation without transport for the same or a closely related complaint. The secondary outcome measures were patient satisfaction, type of secondarily consulted health care provider, provisional and definitive diagnosis, and correctness of the EMS members’ decision to provide on-scene medical care without transport. Results Of the 1095 participating patients, 271 (24.7%) patients requested secondary medical attention for the same complaint. This percentage was significantly larger in incidents attended by an ambulance team than by a rapid responder (N = 248 (26.5%) vs. N = 23 (14.4%); p < 0.05). In eleven (1.0%) cases an urgent medical diagnosis requiring admission was missed. A total of 873 (79.7%) patients were satisfied with the decision not to be transported. In 44 (4.0%) cases the EMS nurse’s decision was rated incorrect since the patient needed help contradictory to the EMS nurse’s recommendation. Conclusions The data show that EMS nurses can effectively examine patients, but a low threshold of referral for consultation should be considered because one in four patients requested secondary medical attention for the same complaint(s) again. However, due to a low response rate (11.3%) more research is needed to further determine the safety of the current EMS protocol. Trial registration Not applicable

Mesh inlay, mesh kit or native tissue repair for women having repeat anterior or posterior prolapse surgery: randomised controlled trial (PROSPECT)

Funding The project was funded by the National Institute for Health Research Health Technology Assessment Programme (Project Number 07/60/18). The Health Services Research Unit and the Health Economics Research Unit are funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. Acknowledgements The authors wish to thank the women who participated in the PROSPECT study. We also thank Margaret MacNeil for her secretarial support and data management; Dawn McRae and Lynda Constable for their trial management support; the programming team in CHaRT, led by Gladys McPherson; members of the Project Management Group for their ongoing advice and support of the study; and the staff at the recruitment sites who facilitated the recruitment, treatment and follow up of study participants.Peer reviewedPublisher PD

A randomised controlled trial of the clinical effectiveness and cost-effectiveness of different knee prostheses : the Knee Arthroplasty Trial (KAT)

Peer reviewedPublisher PD

Transition-pathway models of atomic diffusion on fcc metal surfaces. I. Flat surfaces

Numerical calculation of minimum-energy paths and activation energy barriers for various atomic diffusion processes on fcc metal surfaces are presented. The computational method employed is the action-derived molecular dynamics that searches the approximate Newtonian trajectory on potential-energy surfaces. The minimization of a modified action, which facilitates the conservation of total energy and the control of kinetic energy, enables us to find efficiently the minimum-energy paths of complex microscopic processes. Diverse diffusion mechanisms on flat fcc substrates are investigated in this first part of the series. More complicated systems including surface steps are simulated in paper II.open2

The Gibbs-Thomson formula at small island sizes - corrections for high vapour densities

In this paper we report simulation studies of equilibrium features, namely circular islands on model surfaces, using Monte-Carlo methods. In particular, we are interested in studying the relationship between the density of vapour around a curved island and its curvature-the Gibbs-Thomson formula. Numerical simulations of a lattice gas model, performed for various sizes of islands, don't fit very well to the Gibbs-Thomson formula. We show how corrections to this form arise at high vapour densities, wherein a knowledge of the exact equation of state (as opposed to the ideal gas approximation) is necessary to predict this relationship. Exploiting a mapping of the lattice gas to the Ising model one can compute the corrections to the Gibbs-Thomson formula using high field series expansions. We also investigate finite size effects on the stability of the islands both theoretically and through simulations. Finally the simulations are used to study the microscopic origins of the Gibbs-Thomson formula. A heuristic argument is suggested in which it is partially attributed to geometric constraints on the island edge.Comment: 27 pages including 7 figures, tarred, gzipped and uuencoded. Prepared using revtex and espf.sty. To appear in Phys. Rev.

Photoperiodic response in the formation of gametangia of the long-day plant Sphacelaria rigidula (Phaeophyceae)

The effect of daylength and irradiance on the formation of gametangia in the male gametophyte of Sphacelaria rigidula Kutz (= S. furcigera Kutz [Prud'homme van Reine 19821) was investigated. Formation of gametangia was restricted to long-day conditions: In light-dark regimes with 12 h of light per day or less, no gametangia were formed. In long-day regimes high irradiances caused a suboptimal response, especially near the critical daylength. Interruption of a long dark period with a light break promoted gametangia formation. Light breaks were most effective when given at about the 6th hour of darkness. Nine inductive long-day cycles were required to induce the formation of gametangia, which appeared after ca. 15 d. The plants remained in the induced state only for a very short time. In regimes with very long days and at high irradiance the number of fertile plants decreased after some time, when vigorous vegetative growth started without any further formation of gametangia

A standardised study to compare prostate cancer targeting efficacy of five radiolabelled bombesin analogues

Purpose: Prostate-specific antigen (PSA)-based screening for prostate cancer (PC) has dramatically increased early diagnosis. Current imaging techniques are not optimal to stage early PC adequately. A promising alternative to PC imaging is peptide-based scintigraphy using radiolabelled bombesin (BN) analogues that bind to gastrin-releasing peptide receptors (GRPR) being overexpressed in PC. When labelled to appropriate radionuclides BN targeting of GRPRs may also provide applications for peptide radionuclide receptor therapy (PRRT). Assessment studies under identical experimental conditions allowing a reliable comparison of the potential of such analogues are lacking. This study was performed to evaluate and directly compare five promising radiolabelled BN analogues for their targeting efficacy for PC under standardised conditions. Methods: The BN agonists [111In]DOTA-PESIN, [111In]AMBA, [111In]MP2346 and [111In]MP2653 and one antagonist [99mTc]Demobesin-1 were evaluated in GRPR-overexpressing human PC-3 tumou