89,848 research outputs found
Managing Uncertainty: Lessons from Xenophon\u27s Retreat
Propositions on dynamic capabilities and organizational politics are developed from management literature and are then evaluated using case analysis. The goal is to identify complementary aspects of these perspectives to change from an ancient example that can offer insights for management thought and practice today. Initially chronicled by Xenophon, roughly 10,000 Greek mercenaries spent over two years confronting demanding circumstances as they fought their way into and out of ancient Persia. The mercenaries\u27 response to changing circumstances offers a unique case for integrating literature on responses to uncertainty that range between rational and haphazard explanations. The analysis suggests uncertainty management is a complex phenomenon imperfectly represented by existing models
Black-Hole Transients and the Eddington Limit
I show that the Eddington limit implies a critical orbital period P_crit(BH)
= 2d beyond which black-hole LMXBs cannot appear as persistent systems. The
unusual behaviour of GRO J1655-40 may result from its location close to this
critical period.Comment: 3 pages, no figures; to appear in MNRA
The American Aircraft Industrial Base: On the Brink
An article reviewing the decline in the American aircraft industrial base
The [Not So] Hidden Curriculum of the Legalist State in the Book of Lord Shang and the Han-Fei-Zi
This paper loosely draws some parallels between the experience of a subject in a so-called “Legalist” state with that of a contemporary student in Western schooling today. I explore how governance in the Book of Lord Shang and the Hanfeizi can be interpreted as pedagogy. Defining pedagogy in a relatively broad sense, I investigate the rationalizations for the existence of the state, the application of state mechanisms, and even the concentration of the ruler’s power all teach subjects habits, attitudes, and sensibilities in a similar fashion to what Philip Jackson called the “hidden curriculum”. Through his framework of “crowds, praise, and power” this paper will explore how governance teaches and what those subjected to it learn. This study also attempts to provide some insight into the usefulness of approaching “Legalist” texts with a positive sociological lens
Ultraluminous X-ray Sources and Star Formation
Chandra observations of the Cartwheel galaxy reveal a population of
ultraluminous X-ray sources (ULXs) with lifetimes < 10^7 yr associated with a
spreading wave of star formation which began some 3 x 10^8 yr ago. A population
of high-mass X-ray binaries provides a simple model: donor stars of initial
masses M_2 > 15 Msun transfer mass on their thermal timescales to black holes
of masses M_1 > 10 Msun.
For alternative explanations of the Cartwheel ULX population in terms of
intermediate-mass black holes (IMBH) accreting from massive stars, the inferred
production rate > 10^-6 yr^-1 implies at least 300 IMBHs, and more probably 3 x
10^4, within the star-forming ring. These estimates are increased by factors
eta^-1 if the efficiency eta with which IMBHs find companions of > 15 Msun
within 10^7 yr is <1. Current models of IMBH production would require a very
large mass (\ga 10^{10}\msun) of stars to have formed new clusters. Further,
the accretion efficiency must be low (< 6 x 10^-3) for IMBH binaries,
suggesting super-Eddington accretion, even though intermediate black hole
masses are invoked with the purpose of avoiding it.
These arguments suggest either that to make a ULX, an IMBH must accrete from
some as yet unknown non-stellar mass reservoir with very specific properties,
or that most if not all ULXs in star-forming galaxies are high-mass X-ray
binaries.Comment: 3 pages, no figures; MNRAS accepted with minor amendment
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