Ronald H. Johnston

Publications (2)2.66 Total impact

• Article: Physiological correlates of social behaviour in Bighorn sheep: a field study using electrocardiogram telemetry

  Robert A. Macarthur, Valerius Geist, Ronald H. Johnston
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  ABSTRACT: Telemetered heart rates (HR) were correlated with social interactions of adult free-ranging Bighorn sheep (0vi.s canadensis canadensis). Minimal cardiac responses suggest that economy of expression is a pervasive feature of social behaviour in this species. Commonly performed courtship, dominance and agonistic displays elicited few HR responses in either sender or receiver; those that did occur, were transitory and usually accompanied motor reactions by the subject. Intense behavioural acts that occurred infrequently, such as mount attempts, rush-charges and clashes, evoked maximal HR increases in both performer and receiver. These findings are consistent with the complex social behaviour of Bighorn sheep and a life-strategy demanding frugal investment of resources in maintenance, in order to maximize growth and reproduction.
  Journal of Zoology 08/2009; 196(3):401 - 415. · 2.04 Impact Factor
• Article: Cross‐Vivaldi antenna for breast tumor detection

  Jingjing Zhang, Elise C. Fear, Ronald H. Johnston
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  ABSTRACT: Observation of cross-polarized reflections has been proposed for radar-based breast tumor detection. In this article, a novel cross-Vivaldi antenna is designed and investigated for this application. The antenna performance is examined over the frequency range of 2.2–5.4 GHz. Results obtained through simulations and experiments demonstrate the ability of the antenna to detect tumors in three-dimensional (3D) breast models. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 275–280, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24037
  Microwave and Optical Technology Letters 12/2008; 51(2):275 - 280. · 0.62 Impact Factor