60,151 research outputs found
Protocyanobacteria: Oxygenic and Anoxygenic photosynthesis in mat-forming bacteria
The oldest record of life is preserved in prePhanerozoic stromatolites dated 3500 million years old and is most likely of filamentous mat-forming cyanobacteria. The sedimentary records of cyanobacterial mats in stromatolites are the most abundant record of life throughout the prePhanerozoic. Stromatolites persisted into the Phanerozoic Eon, yet they become much less pronounced relative to earlier ones. The abundance and persistence of cyanobacterial mats throughout most of geological time point to the evolutionary success of these kinds of microbial communities and their possible role in the evolution of the earth and atmosphere
Configurations, and parallelograms associated to centers of mass
The purpose of this article is to
\begin{enumerate}
\item define the -fold center of mass arrangement for points
in the plane,
\item give elementary properties of and
\item give consequences concerning the space of distinct points
in the plane, no four of which are the vertices of a parallelogram.
\end{enumerate}
The main result proven in this article is that the classical unordered
configuration of points in the plane is not a retract up to homotopy of the
space of unordered distinct points in the plane, no four of which are the
vertices of a parallelogram. The proof below is homotopy theoretic without an
explicit computation of the homology of these spaces.
In addition, a second, speculative part of this article arises from the
failure of these methods in the case of odd primes . This failure gives rise
to a candidate for the localization at odd primes of the double loop space
of an odd sphere obtained from the -fold center of mass arrangement.
Potential consequences are listed.Comment: 11 page
The conductance of a multi-mode ballistic ring: beyond Landauer and Kubo
The Landauer conductance of a two terminal device equals to the number of
open modes in the weak scattering limit. What is the corresponding result if we
close the system into a ring? Is it still bounded by the number of open modes?
Or is it unbounded as in the semi-classical (Drude) analysis? It turns out that
the calculation of the mesoscopic conductance is similar to solving a
percolation problem. The "percolation" is in energy space rather than in real
space. The non-universal structures and the sparsity of the perturbation matrix
cannot be ignored.Comment: 7 pages, 8 figures, with the correct version of Figs.6-
The locust frontal ganglion: a central pattern generator network controlling foregut rhythmic motor patterns
The frontal ganglion (FG) is part of the insect
stomatogastric nervous system and is found in most insect
orders. Previous work has shown that in the desert locust,
Schistocerca gregaria, the FG constitutes a major source of
innervation to the foregut. In an in vitro preparation,
isolated from all descending and sensory inputs, the FG
spontaneously generated rhythmic multi-unit bursts of
action potentials that could be recorded from all its
efferent nerves. The consistent endogenous FG rhythmic
pattern indicates the presence of a central pattern
generator network. We found the appearance of in vitro
rhythmic activity to be strongly correlated with the
physiological state of the donor locust. A robust pattern
emerged only after a period of saline superfusion, if the
locust had a very full foregut and crop, or if the animal
was close to ecdysis. Accordingly, haemolymph collected
at these stages inhibited an ongoing rhythmic pattern
when applied onto the ganglion. We present this novel
central pattern generating system as a basis for future
work on the neural network characterisation and its role
in generating and controlling behaviour
The Continuity of Discontinuity: How Young Jews Are Connecting, Creating, and Organizing Their Own Jewish Lives
Based on case studies of four self-initiated ventures in Jewish self-organizing, explores their organizing principles, the limitations of and challenges for conventional institutions, and implications for engaging the new generation
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Role of atomic coordination on superconducting properties of boron-doped amorphous carbon
We study the effect of atomic coordination (orbital hybridization) on superconducting properties of boron-doped amorphous carbon. The ratio of threefold coordinated (sp2-hybridized) and fourfold coordinated (sp3-hybridized) atoms in the system is found to have an impact on their electronic, vibrational, and superconducting properties. Our findings show that a high proportion of fourfold coordination in both carbon and boron atoms is important for realizing a high superconducting transition temperature
Beyond Distancing: Young Adult American Jews and Their Alienation from Israel
This research reports on a mounting body of evidence that has pointed to a growing distancing from Israel of American Jews, most pronounced among younger Jews, and explores critical questions behind their presumably diminished attachment to Israel
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Antecedents and consequences of market orientation in universities: Literature review and conceptual framework
Recent developments in marketing theory have resulted in the conceptualisation of the market orientation construct in different cultural and industrial settings. However, there is little research investigating the applicability of market orientation in the higher education context. Building on the existing literature on market orientation and higher education marketing, the authors propose a theoretical framework of market orientation from a higher education management perspective. The framework analysis leads to propositions relating to the antecedents and consequences of market oriented universities. On the basis of the formulated propositions, the authors conclude with a discussion of the implications both for academia and practice and further research
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