34,460 research outputs found
Well-Ordered Philosophy? Reflections on Kitcher's Proposal for a Renewal of Philosophy.
In his recent article Philosophy Inside Out, Philip Kitcher presents a metaphilosophical outlook that aims at nothing less than a renewal of philosophy. His idea is to draw philosophersâ attention away from âtimeless questionsâ in the so-called âcore areasâ of philosophy. Instead, philosophers should address questions that matter to human lives. The aim of this paper is twofold: first, to reconstruct Kitcherâs view of how philosophy should be renewed; second, to point out some difficulties relating to his position. These difficulties concern the integration of his naturalism into the pragmatic vision of philosophy, the role of putative philosophical experts, and the ideal status of the program of well-ordered inquiry
Spectral analysis of electron transfer kinetics II
Electron transfer processes in Debye solvents are studied using a spectral
analysis method recently proposed. Spectral structure of a nonadiabatic
two-state diffusion equation is investigated to reveal various kinetic regimes
characterized by a broad range of physical parameters; electronic coupling,
energy bias, reorganization energy, and solvent relaxation rate. Within this
unified framework, several kinetic behaviors of the electron transfer kinetics,
including adiabatic Rabi oscillation, crossover from the nonadiabatic to
adiabatic limits, transition from the incoherent to coherent kinetic limits,
and dynamic bath effect, are demonstrated and compared with results from
previous theoretical models. Dynamics of the electron transfer system is also
calculated with the spectral analysis method. It is pointed out that in the
large reorganization energy case the nonadiabatic diffusion equation exhibits a
non-physical behavior, yielding a negative eigenvalue.Comment: submitted for a publication in Journal of Chemical Physic
A non-hyponormal operator generating Stieltjes moment sequences
A linear operator in a complex Hilbert space \hh for which the set
\dzn{S} of its -vectors is dense in \hh and is a Stieltjes moment sequence for every f \in \dzn{S}
is said to generate Stieltjes moment sequences. It is shown that there exists a
closed non-hyponormal operator which generates Stieltjes moment sequences.
What is more, \dzn{S} is a core of any power of . This is
established with the help of a weighted shift on a directed tree with one
branching vertex. The main tool in the construction comes from the theory of
indeterminate Stieltjes moment sequences. As a consequence, it is shown that
there exists a non-hyponormal composition operator in an -space (over a
-finite measure space) which is injective, paranormal and which
generates Stieltjes moment sequences. In contrast to the case of abstract
Hilbert space operators, composition operators which are formally normal and
which generate Stieltjes moment sequences are always subnormal (in fact
normal). The independence assertion of Barry Simon's theorem which
parameterizes von Neumann extensions of a closed real symmetric operator with
deficiency indices is shown to be false
Temperature and light requirements for growth of two diatom species (Bacillariophyceae) isolated from an Arctic macroalga
In the present study, two abundant epiphyticdiatom taxa were isolated from the assimilation hairs ofthe brown macroalga Chordaria flagelliformis collected inthe Arctic Kongsfjorden (Spitsbergen, Norway), establishedas unialgal cultures and their growth rates determinedunder controlled photon fluence rate andtemperature conditions. Using morphological (light andscanning electron microscopy) and SSU rRNA gene databoth isolates (ROS D99 and ROS D125) were identifiedas members of a FragilariaSynedropsis clade. Themolecular data of ROS D99 and ROS D125 were notidentical to any other published sequence. While ROSD99 has been identified as Fragilaria barbararum mainlydue to the SEM characteristics, ROS D125 could not bedefinitely identified although morphological data speakfor Fragilaria striatula. Both diatom species showedsimilar growth rates at all temperatures and photon fluencerates tested. They grew well between 0 and 15Cwithoptimum temperatures of 1214C, but did not survive20C. Therefore, compared to Antarctic diatoms bothtaxa from Kongsfjorden can be characterised as eurythermalorganisms. Increasing photon fluence rates between2 and 15 lmol m2 s1 were accompanied with analmost twofold increase in growth rates, but photon fluencerates >15 lmol m2 s1 did not further enhancegrowth pointing to low light requirements. From thesedata optimum, minimum and maximum photon fluencerates and temperatures for growth can be assessed indicatingthat both diatoms are well acclimated to the fluctuatingenvironmental conditions in the Arctic habitat
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