4,650 research outputs found
Processes of Strategic Renewal, Competencies, and the Management of Speed
We discuss strategic renewal from a competence perspective. We argue that the management of speed and timing in this process is viewed distinctively when perceived through a cognitive lens. Managers need more firmly grounded process-understanding. The key idea of this paper is to dynamically conceptualize key activities of strategic renewal, and possible sources of break-down as they relate to the managment of speed and timing. Based on a case from the media industry, we identify managerial trade-offs and show how these can be influenced through managing subjective perception, strategic involvement and external knowledge-sourcing.Strategic Renewal, Process, Learning, Knowledge-Sourcing
Stable phase field approximations of anisotropic solidification
We introduce unconditionally stable finite element approximations for a phase
field model for solidification, which take highly anisotropic surface energy and kinetic
effects into account. We hence approximate Stefan problems with anisotropic
Gibbs{Thomson law with kinetic undercooling, and quasi-static variants thereof.
The phase field model is given by
#wt + � %(') 't = r: (b(')rw) ;
c
a
� %(')w = " �
� �(r') '
Metabolic and cometabolic degradation of herbicides in the fine material of railway ballast
Microbial degradation of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and mineralization of 4-chloro-2-methylphenoxyacetic acid (MCPA) were studied in soil samples taken from the ballast layers of three Swedish railway embankments. The degradation of diuron followed first-order kinetics and half-lives ranged between 122 and 365 days. The half-lives correlated strongly with microbial biomass estimated by substrate-induced respiration (SIR; R=-0.85; p<0.05) and with the amount of organic matter measured as loss on ignition (R=-0.87; p<0.05). Accumulation of the metabolites 1-(3,4-dichlorophenyl)-3-methyl urea (DCPMU) and 1-(3,4-dichlorophenyl) urea (DCPU) was observed in all samples and these were only detectably degraded in the sample with the highest SIR. Addition of ground lucerne straw to the ballast samples stimulated microbial activity and led to increased formation of metabolites, but further transformation of DCPMU and DCPU was not enhanced. Mineralization of MCPA followed growth-linked kinetics and the time for 50% mineralization was 44.5±7.1 days in samples of previously untreated ballast. In samples of ballast that had been previously treated with the herbicide formulation MCPA 750, the time for 50% mineralization was reduced to 13.7±11.3 days. The number of MCPA degraders, quantified using an MPN technique, was clearly increased but highly variable. An average yield of 0.18 cells pg−1 of MCPA was estimated from the kinetic data. The yield estimates correlated with the amount of nitrogen in the ballast, indicating that mineralization of MCPA was nitrogen-limited in the railway embankments studied. This has practical implications for weed control using herbicides on railways
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Stable and Clumped Isotope Characterization of Authigenic Carbonates in Methane Cold Seep Environments
Cold seep environments are characterized by methane-rich fluid migration and discharge at the seafloor. These environments are also intimately linked to microbial communities, which oxidize methane anaerobically, increase alkalinity and promote authigenic carbonate precipitation. We have analyzed a suite of methane-derived authigenic carbonate (MDAC) crusts from the North and Barents Sea using stable and clumped isotopes (δ¹³C, δ¹⁸O, δ⁴⁴Ca, and Δ₄₇) to characterize the sources of fluids as well as the environment of carbonate authigenesis. We additionally assess the potential of MDACs as a Δ₄₇-based paleotemperature archive.
The MDACs occur as three main textural-mineralogic types: micritic Mg-calcite cements, micritic aragonite cements and cavity filling aragonite cements. We find that micritic Mg-calcite cements have low δ¹³C_(VPDB) values (−30 to −47‰), high δ⁴⁴Ca_(SW) values (−0.4 to −0.8‰), and Δ₄₇-temperatures (0–6 °C) consistent with shallow sub-seafloor precipitation in isotopic equilibrium. Micritic aragonite cements and cavity filling aragonite cements both have a wider range in δ¹³C_(VPDB) values (−18 to −58‰), lower δ⁴⁴Ca_(SW) values (−0.8 to −1.6‰) and a larger range in Δ₄₇-based apparent temperatures (–2 – 25 °C) with samples displaying equilibrium and disequilibrium clumped isotope values.
The range in apparent temperatures as well as δ⁴⁴Ca_(SW) values seen in the aragonite MDACs suggest two kinetic processes: a kinetic isotope effect (KIE) due to the incomplete equilibration of carbon and oxygen isotopes among DIC species from the different sources of DIC (i.e., seawater, methane-sourced DIC and DIC residual to CO₂ degassing or diffusion) and a KIE due to a fast, irreversible precipitation affecting the cations, particularly Ca, bound to carbonate mineral. Our results improve the understanding of kinetic effects on clumped isotope temperatures in MDACs and demonstrate how the multi-isotopic approach combined with textural-mineralogic criteria can be used to identify MDACs for accurate paleotemperature reconstructions
Block theory, branching rules, and centralizer algebras
This paper is one in a series [8–11] exploring the algebra kGH , the centralizer in the
group algebra kG of the subalgebra kH, where k is a field of characteristic not zero,
G is a finite group, and H is a subgroup of G. All these papers search for theorems
similar to Alperin’s weight conjecture [2]. The immediate goal is to find results that relate
information about blocks of kGH or simple modules over kGH to p-local information.
The ultimate goal is to gain insight into Alperin’s conjecture. See the introductions to [10]
and [11] for a detailed description of the program
The action of the Murphy element on the restricition of an irreducible Sn-Module to Sn-1
We study the irreducible representations of the symmetric group n
over a eld F of positive characteristic p. For convenience, but no
loss of generality, we shall assume that F is algebraically closed. Let
= (1 2 : : : l > 0) be a partition of n. As usual the set
of nodes [] := f(i; j) 2 Z2 j 1 i l; 1 j ig is called the
Young diagram of . We represent [] as a set of square boxes in Z2,
by placing a square with opposite corners (
Branching Rules for Specht Modules
Let n be the symmetric group of degree n, and let F be a eld
of characteristic distinct from 2. Let S F be the Specht module over Fn corresponding
to the partition of n. We nd the indecomposable components of
the restricted module S
F #n1 and the induced module S
F "n+1 . Namely,
if b and B are block idempotents of Fn1 and Fn+1 respectively, then
the modules S
F #n1
b and S
F "n+1 B are 0 or indecomposable. We give
examples to show that the assumption char F 6= 2 cannot be dropped
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