18,664 research outputs found
Developmental biology of wood formation
The wood-forming vascular cambium is responsible for the production of a large part of the biomass on this planet. Yet, there is only limited knowledge on how cell proliferation and differentiation in the cambial meristem are regulated. In this thesis the wood-forming tissues of aspen were used as a model system to identify and characterize molecular factors related to cambial meristem activity. An important regulator of cambial meristem activity is the plant hormone auxin. As polar transport is crucial for the delivery of auxin to the cambial zone, we identified homologues of known regulators of polar auxin transport and described their regulation by environmental and developmental factors. Translating changes in auxin concentration into changes in gene expression involves members of the Aux/IAA gene family. Aspen homologues of Aux/IAA genes were cloned and found to be expressed in a highly tissue-specific fashion, which is further influenced by developmental events and changes in the environment. A major response of trees to environmental changes is the suspension of meristematic growth during winter dormancy. A comparison of gene expression in active and dormant cambia revealed dramatic changes in the transcriptome including the expression of many cold and stress related genes during winter. During the process of wood formation, cells originating in the vascular cambium go through an elaborate process of cell division, cell expansion, secondary wall formation and programmed cell death. Large-scale analysis of gene expression was used to create transcriptional maps of the differentiation process. This extensive dataset allowed us to confirm the proposed functions of various genes involved in wood formation, assign other known genes to specific stages along the developmental gradient and identify a large number of novel potential regulators of wood formation. The data further suggest that the cambial meristem shares regulatory mechanisms with other meristems in addition to its own, specific factors
Integrable systems from the classical reflection equation
We construct integrable Hamiltonian systems on , where is a
quasitriangular Poisson Lie group and is a Lie subgroup arising as the
fixed point set of a group automorphism of satisfying the
classical reflection equation. In the case that is factorizable, we show
that the time evolution of these systems is described by a Lax equation, and
present its solution in terms of a factorization problem in . Our
construction is closely related to the semiclassical limit of Sklyanin's
integrable quantum spin chains with reflecting boundaries.Comment: 23 pages, published versio
Evaluation of Several Commercial Algicides for Control of Odor-producing Cyanobacteria
The production of certain odorous metabolites is an undesirable attribute of cyanobacteria (blue-green algae) growth in aquaculture ponds [e.g., channel catfish(Ictalurus punctatus)] and in drinking water reservoirs. The most common odorous compounds encountered in catfish aquaculture are geosmin (trans-1,10-dimethyltrans-9-decalol) and 2-methylisoborneol(exo-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol).
These compounds are also frequently encountered worldwide
in reservoirs and aqueducts used for municipal drinking water systems(Schrader et al. 2002). In this study, several algicides were evaluated
using a rapid bioassay to determine their effectiveness in
controlling the MIB-producing cyanobacterium
Oscillatoria
perornata
from a west Mississippi catfish pond and the MIBproducing
Pseudanabaena
sp. (strain LW397) from Lake
Whitehurst, Virginia, used as a city water supply reservoir.
The cyanobacterium
Oscillatoria agardhii
, not a MIB-producer,
and the green alga
Selenastrum capricornutum
, found in catfish
ponds in the southeastern United States, were included
in the bioassay to help determine potential broad-spectrum
toxicity of the commercial products. (PDF has 3 pages.
Mussolini\u27s Gladius: The Double-Edged Sword of Antiquity in Fascist Italy
Mussolini and the Fascist Party used a plethora of propaganda techniques in order to suggest the renewal of the old Roman Empire with the rise of the Italian Fascist Party. Through the use of ideology, race issues, religion, educational control, posters, theatre, architecture, and archeology, the Fascists used the Roman past to glorify modern Italy and the Fascist party. The Fascists’ use of these Roman allusions made their own deficiencies more apparent and led to a general failure of their propaganda program in terms of creating a new Italian identity focused upon the Ancient Roman past
Direct nanofiltration of wastewater treatment plant effluent
Membrane technology, especially nanofiltration, is seen as a suitable technology to polish WWTP effluent to EU WFD standards and consequently produce an effluent quality suitable for agricultural or (in)direct potable usage. The objective of this study was to assess the potential of direct nanofiltration as technique for effluent reclamation
Multiple input radio receiver Patent
Radio receiver with array of independently steerable antennas for deep space communicatio
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