scholarly journals Correction to ‘Cracking failure of curved hollow tree trunks’

2020 ◽  
Vol 7 (5) ◽  
pp. 200643
Author(s):  
Yan-San Huang ◽  
Pei-Lin Chiang ◽  
Ying-Chuan Kao ◽  
Fu-Lan Hsu ◽  
Jia-Yang Juang
Keyword(s):  
2005 ◽  
Vol 38 (5) ◽  
pp. 410-415 ◽  
Author(s):  
Maria Hismênia H.M. Garcia ◽  
Lindemberg Souza ◽  
Rita de Cássia M. de Souza ◽  
Alexandre S. Paula ◽  
Érika C. Borges ◽  
...  

Panstrongylus lutzi is generally restricted to the "caatinga" areas of north-eastern Brazil. Adult insects are frequently found in local houses, but colonies have not previously been registered in the statistics of the Control Programme of Chagas Disease. In Ceará State, our study revealed increasing occurrence of this species, usually with high infection rates for Trypanosoma cruzi, and always represented by adults that invaded the artificial environment. We also found nymphs in the peridomicile and inside the houses. In silvatic habitats we collected two adult females from hollow tree trunks, which may represent an alternative natural ecotope for the species in this state. Panstrongylus lutzi entomological collections from Sobral and Crateús, studied by morphology and morphometrics, showed great variability; those from Crateús were larger smaller and paler in colour, with individuals showing genital features consistent with those described for Panstrongylus lutzi or Panstrongylus sherlocki, whereas those from Sobral were darker and with genitalia compatible with P. sherlocki, nevertheless, all were considered to be Panstrongylus lutzi.


The author had already stated, in a former communication to the Royal Society, his having noticed that for several days previous to the settling of a swarm of bees in the cavity of a hollow tree adapted to their reception, a considerable number of these insects were incessantly employed in examining the state of the tree, and particularly of every dead knot above the cavity which appeared likely to admit water. He has since had an opportunity of observing that the bees who performed this task of inspection, instead of being the same individuals as he had formerly supposed, were in fact a continual succession of different bees; the whole number in the course of three days being such as to warrant the inference that not a single labouring bee ever emigrates in a swarm without having seen its proposed future habitation. He finds that the same applies not only to the place of permanent settlement, but also to that where the bees rest temporarily, soon after swarming, in order to collect their numbers. The swarms, which were the subjects of Mr. Knight’s experiments, showed a remarkable disposition to unite under the same queen. On one occasion a swarm, which had arisen from one of his hives, settled upon a bush at a distance of about twenty-five yards; but instead of collecting together into a compact mass, as they usually do, they remained thinly dispersed for nearly half an hour; after which, as if tired of waiting, they singly, one after the other, and not in obedience to any signal, arose and returned home. The next morning a swarm issued from a neighbouring hive, and proceeded to the same bush upon which the other bees had settled on the preceding day; collecting themselves into a mass, as they usually do when their queen is present. In a few minutes afterwards a very large assemblage of bees rushed from the hive from which the former swarm had issued, and proceeded directly to the one which had just settled, and instantly united with them. The author is led from these and other facts to conclude that such unions of swarms are generally, if not always, the result of previous concert and arrangement.


Author(s):  
Kenneth Grahame

The front door of the hollow tree faced eastwards, so Toad was called at an early hour; partly by the bright sunlight streaming in on him, partly by the exceeding coldness of his toes, which made him dream that he was at home in...


2017 ◽  
Vol 4 (4) ◽  
pp. 160972 ◽  
Author(s):  
Yan-San Huang ◽  
Fu-Lan Hsu ◽  
Chin-Mei Lee ◽  
Jia-Yang Juang

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t / R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t / R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 <  t / R  < 0.06, 0.06 <  t / R  < 0.27 and 0.27 <  t / R  < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings.


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