Darren W Johnson

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Density dependence in demographic rates can strongly affect the dynamics of populations. However, the mechanisms generating density dependence (e.g., predation) are also dynamic processes and may be influenced by local conditions. Understanding the manner in which local habitat features affect the occurrence and/or strength of density dependence will(More)
Purpose: To evaluate the antitumor effects and toxicities of whole brain irradiation (WBI) with temozolomide (TMZ) administered by prolonged oral dosing in patients with melanoma metastatic to the brain. Background: Patients with melanoma metastatic to the central nervous system (CNS) have an extremely poor prognosis and appear to benefit little from WBI.(More)
For species that have an open population structure, local population size may be strongly influenced by a combination of propagule supply and post-settlement survival. While it is widely recognized that supply of larvae (or recruits) is variable and that variable recruitment may affect the relative contribution of pre- and post-settlement factors, less(More)
The production of Υ (1S), Υ (2S) and Υ (3S) mesons in proton-proton collisions at the centre-of-mass energy of √ s = 7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb−1 collected at the Large Hadron Collider. The Υ mesons are reconstructed in the decay mode Υ → μ+μ− and the signal yields are extracted from a fit to the(More)
OBJECTIVE To determine the prevalence of anal human papillomavirus (HPV) infections and anal cytologic abnormalities in HIV-seropositive and HIV-seronegative women. DESIGN This cross-sectional study of a cohort of women with known HIV serostatus involved a standardized interview and a gynecologic examination, including a cytologic evaluation of the cervix(More)
Do small-scale experiments showing spatial density dependence in marine fishes scale-up to temporal density dependence and regulation of relatively large local populations? If so, what are the causative mechanisms and their implications? We conducted an eight-year multigeneration study of population dynamics of bicolor damselfish (Stegastes partitus)(More)
Interactions between ions and aromatic rings are now a mainstay in the field of supramolecular chemistry. The prototypical cation-π interaction, first characterized in the gas phase, is now well-known as an important contributor to protein structure and enzyme function and as a noncovalent force found in many synthetic systems. The complementary "anion-π(More)
Experimental manipulation of population density has frequently been used to demonstrate demographic density dependence. However, such studies are usually small scale and typically provide evidence of spatial (within-generation) density dependence. It is often unclear whether small-scale, experimental tests of spatial density dependence will accurately(More)