Abstract：
:Working from the general postulate that natural selection of plant form operates so as to maximize the survival potential of a species, this paper examines the hypothesis that the mechanical support of tree foliage must approach optimality in the use of wood, i.e., that tree stems and branches will have "optimal form" with respect to the amount of support tissue. Mathematical models of bole and branch form are presented, based on the proposition that either wind or gravity are the primary limiting factors for tree size and shape. Predictions of trunk and branch diameter as a function of tree size were tested with dimensional measurements of Populus tremuloides. The individual stems were selected from close-grown stands of differing ages. For small and intermediate trees, trunk diameter is such that stems have only 1.6 times as much wood as the minimum required to keep the tree from buckling under its own weight due to elastic instability. Branch diameters are shown to be close to the minimum required to maintain the spatial position of growing branches, as well as withstand wind forces. This minimal branch cost not only reduces the load which the stem must support against elastic instability, but allows the crown to flex in high winds. The flexing, in turn, reduces the drag force exerted by the wind on the trunk. Thus, the hypothesis that the observed tree form is an optimal design cannot be rejected on the basis of these results. Additional studies are planned with respect to optimal foliage distribution.
journal_name
Radiat Environ Biophysjournal_title
Radiation and environmental biophysicsauthors
King D,Loucks OLdoi
10.1007/BF01323263subject
Has Abstractpub_date
1978-08-10 00:00:00pages
141-65issue
2eissn
0301-634Xissn
1432-2099journal_volume
15pub_type
杂志文章abstract：:Hematoporphyrin (Hp) solutions were subjected to a wide range high intensity (0.2-10.0 GW/cm2) near-UV laser pulse radiation (lambda exc = 355 nm, pulse duration 30 ps). The formation of stable Hp photoproducts was followed by UV-VIS absorption spectroscopy and liquid-gel column chromatography. As judged by the influe...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210525
更新日期：1990-01-01 00:00:00
abstract：:Age-specific and cumulative mortality rates are presented for different cancer sites from 1970 until 1988 for the 11 individual federal states of West Germany (FRG). Sex- and age-specific evaluations are performed and temporal and regional trends in mortality from different cancer sites are revealed. In the FRG there ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01212802
更新日期：1993-01-01 00:00:00
abstract：:This study examined the effects of three disasters (the Great East Japan Earthquake of March 11, 2011, followed by a tsunami and the Fukushima Daiichi Nuclear Power Plant accident) on feeding methods and growth in infants born after the disasters. Using results from the Fukushima Health Management Survey, Soso Distric...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-016-0636-7
更新日期：2016-05-01 00:00:00
abstract：:Estimates are presented on the carbon-14 generation rates in several reactor types and in peaceful nuclear explosions. If the carbon-14 generated in light water reactors is released, the population radiation dose rate it causes initially will be comparable to that resulting from the krypton-85 and tritium generated in...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01331176
更新日期：1976-12-23 00:00:00
abstract：:Thorough studies of 28 water bodies, predominantly lakes from the younger moraine area of Schleswig-Holstein, Northern Germany but also some peat bog waters in Niedersachsen, Northern Germany and lake Balaton in Hungary, showed the presence of at least six redox systems: NO3-/NO2-; NO3-/NH4+; NO2-/NH4+; So/HS-; So/H2S...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01221229
更新日期：1986-01-01 00:00:00
abstract：:The sulphur-containing radioprotectors mercaptoethylamine (MEA), aminoethylisothiourea (AET), 2- aminothiazoline , 4-oxo-2- aminothiazoline , and S-S-3- oxapentane -1,5- diisothiourea , and the radioprotective biogenic amines serotonin, histamine, and dopamine, caused the elevation of cAMP content and intensified the ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01213732
更新日期：1984-01-01 00:00:00
abstract：:To investigate whether residual radiation damage in hematopoietic tissue is measurable in situ by a change in cell turnover, the retention of the thymidine analogue 5-(125-I)iodo-2'-deoxyuridine (125-IUdR) following incorporation into DNA of cells in bone marrow and spleen of mice was measured 35 days after 0-500 rad ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01325468
更新日期：1982-01-01 00:00:00
abstract：:Radiation is known to be carcinogenic to humans but attempts to demonstrate the process using human tissue culture models have met with little success. In the present study explants were established from urothelium and exposed to radiation and a range of chemical carcinogens, suspected promotor or metabolic agents. Th...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210524
更新日期：1990-01-01 00:00:00
abstract：:Microcalorimetry, in combination with conventional methods for determining metabolic activity, opens the possibility to study the efficiency with which ATP, produced as a result of metabolic activity, is utilized by the cell for energy-requiring synthetic reactions. Using commercial baker's yeast as a test organism an...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01323416
更新日期：1975-12-04 00:00:00
abstract：:The risk of cancer after diagnostic X-rays received as fetus or during early childhood has been investigated in many studies. The results of recent epidemiological studies are summarized in a present systematic review. The strategies for literature search, inclusion criteria, and items for study quality assessment wer...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章,评审
doi：10.1007/s00411-008-0171-2
更新日期：2008-07-01 00:00:00
abstract：:Various transport models are presently used to predict the long-term migration behaviour of fallout radiocesium on the soil. To examine to what extent the uncertainty of these predictions is influenced by the spatial variability of the migration rates, we determined the depth profiles of Chernobyl-derived 137Cs at 100...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s004110000062
更新日期：2000-09-01 00:00:00
abstract：:The naturally synchronous development of early mouse embryos was exploited to address the question, whether micronuclei require a mitosis for expression or whether they can be expressed in the same cell cycle, in which exposure to X-rays or caffeine took place. Experiments with 2-cell and with 4-cell embryos showed th...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01219345
更新日期：1991-01-01 00:00:00
abstract：:Procedures for age-adjustment of cancer fractions are proposed which do not require fixed age intervals. The full available information on survival times can then be used, which is especially important in small treatment groups. For incidental cancers a non-decreasing prevalence function and for fatal cancers the Kapl...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-004-0250-y
更新日期：2004-09-01 00:00:00
abstract：:The effects of single pulses and multiple pulses of 7 MV electrons on micronuclei (MN) induction in cytokinesis-blocked human peripheral blood lymphocytes (PBLs) were investigated over a wide range of dose rates per pulse (instantaneous dose rate). PBLs were exposed to graded doses of 2, 3, 4, 6, and 8 Gy of single el...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-011-0353-1
更新日期：2011-05-01 00:00:00
abstract：:A method which allows growth of normal human tissue to be studied in vitro is used to investigate possible interactive effects of radiation and environmentally important carcinogens on oesophageal and urothelial cell growth. Carcinogens chosen were selected for their known or suspected effect on the oesophageal mucosa...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01211257
更新日期：1989-01-01 00:00:00
abstract：:Most of plutonium released by nuclear explosions is Pu-241 which decays to Am-241. We have studied the deposition of Pu-241 and Am-241 in lichens collected since 1958 in the central part of Sweden (62.3 degrees N, 12. 4 degrees E). Comparative studies with Pu-isotopes, Pu-239 + 240 and Pu-238 were also performed. In 1...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF02176794
更新日期：1978-10-12 00:00:00
abstract：:The macroscopic reaction of the mouse skin was used to derive RBE values for negative pi-Mesons. Hind limbs of mice were irradiated with pions or X-rays. The pions were produced by the 590 MeV accelerator of the Schweizerisches Institut für Nuklearforschung (SIN). Early reaction was assessed over a period of 6--30 day...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01358292
更新日期：1979-08-10 00:00:00
abstract：:Within the Theory of Dual Radiation Action, the heuristically useful function, gamma(chi), that two energy depositions, a distance chi apart, will result in observable damage can be written in terms of two more fundamental quantities: One, s(chi), describes the structure of the sensitive matrix of the cell. The other,...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210836
更新日期：1988-01-01 00:00:00
abstract：:For studies on cell membranes, mice were exposed to mixed neutron + gamma reactor-radiation in the range of total doses from 0.5 to 4.5 Gy. Changes in functional activity of plasma membranes of erythrocytes, platelets, and lymphocytes were followed by a lectin-binding technique at various intervals afterwards. The amo...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01407598
更新日期：1984-01-01 00:00:00
abstract：:It is usually assumed that sparsely ionizing radiation produces randomly distributed DNA breakages. This seems to be supported by the finding that in some DNA fragments single-strand scissions occur uniformly at all nucleotide sites, regardless of sequence. We performed experiments on two DNA fragments of about 300 bp...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01255271
更新日期：1994-01-01 00:00:00
abstract：:In mice, persisting radiation-induced growth retardation of hematopoietic tissue suggested that at least part of the surviving stem cells are genetically injured. Additional mitotic stress some time after the radiation insult might remove injured stem cells, thus improving the overall recovery of the irradiated bone m...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01211410
更新日期：1987-01-01 00:00:00
abstract：:The number and type of stem cells in spleen and bone marrow of mice were determined after exposure to a single dose of 150 R on day 6, to a single dose of 500 R on day 6 or day 9 or to a fractionated dose of 150 R + 350 R on day 6 and 9. The stem cells were assayed on the basis of colony forming units (CFU) in spleen ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01324267
更新日期：1980-01-01 00:00:00
abstract：:Ionizing radiation can produce adverse biological effects in astronauts during space travel. Of particular concern are the types of radiation from highly energetic, heavy, charged particles known as HZE particles. The aims of our studies are to characterize HZE particle radiation induced biological effects and evaluat...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-006-0089-5
更新日期：2007-06-01 00:00:00
abstract：:The influence of microgravity on the repair of x-ray-induced DNA double-strand breaks was studied in the temperature-conditional repair mutant rad54-3 of diploid yeast Saccharomyces cerevisiae. Cells were exposed on the ground and kept at a low temperature until microgravity conditions were achieved. In orbit, they we...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s004110050149
更新日期：1999-07-01 00:00:00
abstract：:Growth rates and cell diameters were determined from 12 species of plant roots exposed to a 60-Hertz (Hz) electric field of 360 Volts per meter (V/m) in an aqueous inorganic nutrient medium [conductivity: 0.07-0.09 Siemens per meter (S/m)]. The degree of growth depression ranged from zero to nearly 100 percent of cont...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210937
更新日期：1985-01-01 00:00:00
abstract：:The non-cancer mortality data for cerebrovascular disease (CVD) and cardiovascular diseases from Report 13 on the atomic bomb survivors published by the Radiation Effects Research Foundation were analysed to investigate the dose-response for the influence of radiation on these detrimental health effects. Various param...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-012-0410-4
更新日期：2012-05-01 00:00:00
abstract：:Several proteins are known to form foci at DNA sites damaged by ionizing radiation. We study DNA damage response by immunofluorescence microscopy after microirradiation of cells with energetic ions. By using microirradiation, it is possible to irradiate different regions on a single dish at different time-points and t...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-008-0181-0
更新日期：2008-11-01 00:00:00
abstract：:At five stages of gestation, mice were exposed dorsally to ultrasonic irradiation at 1 W/cm2 (spatial and temporal average), 2 MHz, and 34 and 37 degrees C (temperature at beginning of exposure). The results indicated that ultrasonic exposure up to at least 100 s is not hazardous to a pregnant mouse or its offspring i...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01323651
更新日期：1980-01-01 00:00:00
abstract：:An inter-comparison of five models designed to predict the effect of ionizing radiation on populations of non-human wildlife, performed under the IAEA EMRAS II programme, is presented and discussed. A benchmark scenario 'Population response to chronic irradiation' was developed in which stable generic populations of m...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-012-0430-0
更新日期：2012-11-01 00:00:00
abstract：:Autoradiography is an effective tool for the imaging of radionuclide distributions in various samples. In sophisticated applications with special preparation and development of sample-emulsion combinations and subsequent grain counts it can be highly quantitative, but it requires carefully controlled conditions and a ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01209769
更新日期：1993-01-01 00:00:00
