30,894 research outputs found
Circular 102
In 1989, a systematic evaluation of woody and herbaceous perennial landscape
plants was begun at the University of Alaska Fairbanks Georgeson Botanical Garden
(64°51’N, 147°52’W). These evaluations were expanded to include annual flowers in
1992 and ferns in 1993. The purpose of this research is to identify hardy perennials
capable of surviving in subarctic environments; to evaluate the ornamental potential of
perennials and annuals; and to fulfill a growing demand for information on landscape
plant materials by homeowners, commercial growers, and landscapers.Introduction -- Explanation of Plant Evaluation Tables -- Table 1. Weather records for the test years -- Table 2. All plant materials evaluated in 1994: Herbaceous perennials; Ferns; Ornamental grasses; Woody perennials -- Table 4. Plantings from 1994 that have not yet been evaluated for winter survival: Herbaceous perennials; Ferns; Woody perennials -- Table 5. Annual flowers evaluated in 1994 -- Appendix 1. Commercial Sources and Organizations -- Map of GB
Circular 98
In 1989, a systematic evaluation of woody and herbaceous perennial landscape
plants was begun at the University of Alaska Fairbanks Georgeson Botanical Garden
(64051’N, 147°52’W). These evaluations were expanded to include annual flowers in
1992 and ferns in 1993. The purpose of this research is to identify hardy perennials
capable of surviving in subarctic environments; to evaluate the ornamental potential of
perennials and annuals; and to fulfill a growing demand for information on landscape
plant materials by homeowners, commercial growers, and landscapers.Introduction -- Explanation of Plan Evaluation Tables -- Table 1. Weather records for the test years -- Table 2. All plant materials evaluated in 1992: Herbaceous perennials; Ornamental grasses; Woody perennials -- Table 3. All plants that have been evaluated but did not survive the minimum number of test years: Hebaceous perennials; Ornamental grasses; Woody perennials -- Table 4. Plantings from 1993 that have not yet been evaluated for winter survival: Herbaceous perennials; Ferns; Ornamental grasses; Woody perennials -- Table 5. Annual flowers evaluated in 1993 -- Appendix 1. Commercial Sources and Organizations -- Map of GB
Time evolution and observables in constrained systems
The discussion is limited to first-class parametrized systems, where the
definition of time evolution and observables is not trivial, and to finite
dimensional systems in order that technicalities do not obscure the conceptual
framework. The existence of reasonable true, or physical, degrees of freedom is
rigorously defined and called {\em local reducibility}. A proof is given that
any locally reducible system admits a complete set of perennials. For locally
reducible systems, the most general construction of time evolution in the
Schroedinger and Heisenberg form that uses only geometry of the phase space is
described. The time shifts are not required to be 1symmetries. A relation
between perennials and observables of the Schroedinger or Heisenberg type
results: such observables can be identified with certain classes of perennials
and the structure of the classes depends on the time evolution. The time
evolution between two non-global transversal surfaces is studied. The problem
is posed and solved within the framework of the ordinary quantum mechanics. The
resulting non-unitarity is different from that known in the field theory
(Hawking effect): state norms need not be preserved so that the system can be
lost during the evolution of this kind.Comment: 31 pages, Latex fil
Ambiguous Dependence Of Minimal Plant Generation Time On Nuclear DNA Content
AMBIGUOUS DEPENDENCE OF MINIMAL PLANT GENERATION TIME ON NUCLEAR DNA CONTENT Victor B. Ivanov The minimum generation time (MGT) of plant development was suggested to depend on nuclear DNA content, which varies in plants over wide limits1. In ephemeral species with the shortest MGT, the average C values were significantly lower than in annual species, whereas the average C values in annual species were lower than those in perennial plants. However, nobody has paid attention to the ratio of annual to perennial species number as a function of C values. Here I show that with increasing C the ratio of annual to perennial species increases to C values equal to 7-8 pg (monocots) and 6-7 pg (eudicots) and then decreases and that the fraction of annuals is abundant not at the lowest, but at some higher C levels. Hence, C value increase exerts an ambiguous effect on MGT. The C value is not the only factor, which determines the duration of the plant development. Nevertheless, the nuclear DNA content exerts a pronounced effect on MGT together with other diverse factors affecting the rate of plant development, especially at higher C values
Group quantization of parametrized systems I. Time levels
A method of quantizing parametrized systems is developed that is based on a
kind of ``gauge invariant'' quantities---the so-called perennials (a perennial
must also be an ``integral of motion''). The problem of time in its particular
form (frozen time formalism, global problem of time, multiple choice problem)
is met, as well as the related difficulty characteristic for this type of
theory: the paucity of perennials. The present paper is an attempt to find some
remedy in the ideas on ``forms of relativistic dynamics'' by Dirac. Some
aspects of Dirac's theory are generalized to all finite-dimensional first-class
parametrized systems. The generalization is based on replacing the Poicar\'{e}
group and the algebra of its generators as used by Dirac by a canonical group
of symmetries and by an algebra of elementary perennials. A number of insights
is gained; the following are the main results. First, conditions are revealed
under which the time evolution of the ordinary quantum mechanics, or a
generalization of it, can be constructed. The construction uses a kind of gauge
and time choice and it is described in detail. Second, the theory is structured
so that the quantum mechanics resulting from different choices of gauge and
time are compatible. Third, a practical way is presented of how a broad class
of problems can be solved without the knowledge of explicit form of perennials.Comment: After discussions at Imperial College, a great improvement is
achieved. I particular, it is shown that many problems can be solved without
explicit knowledge of the perennial
Perennials and the Group-Theoretical Quantization of a Parametrized Scalar Field on a Curved Background
The perennial formalism is applied to the real, massive Klein-Gordon field on
a globally-hyperbolic background space-time with compact Cauchy hypersurfaces.
The parametrized form of this system is taken over from the accompanying paper.
Two different algebras and of
elementary perennials are constructed. The elements of
correspond to the usual creation and annihilation operators for particle modes
of the quantum field theory, whereas those of are the
smeared fields. Both are shown to have the structure of a Heisenberg algebra,
and the corresponding Heisenberg groups are described. Time evolution is
constructed using transversal surfaces and time shifts in the phase space.
Important roles are played by the transversal surfaces associated with
embeddings of the Cauchy hypersurface in the space-time, and by the time shifts
that are generated by space-time isometries. The automorphisms of the algebras
generated by this particular type of time shift are calculated explicitly.Comment: 31 pages, revte
- …