2,570 research outputs found
The Rise and Fall of Canadian Military Assistance in the Developing World, 1952–1971
Since the end of the Second World War, military assistance has emerged as an important instrument of international diplomacy. Initially employed by the United States in Europe, Latin America and Asia for a variety of economic and political reasons in the mid-1940s, by the end of the decade American military assistance had been fashioned into a coherent program “whose principal goal was the containment of Communist expansion.” By the mid-1950s, both the Soviet Union and Communist China had responded with their own assistance programs designed to woo the developing states of Asia and Africa. As Britain and France dissolved their colonial empires in the late 1950s, they too chose military aid as an effective way to maintain their links with the post-colonial state and to demonstrate their continued capacity to pursue independent global initiatives. Other states were also attracted by this kind of aid. West Germany, for example, began distributing military assistance in 1960 as part of its efforts to garner international support for its claim to sovereignty.
Canada’s decision to supply small amounts of military assistance to the developing world owed relatively little to the cold war calculations of the superpowers and the considerations of national prestige that motivated other donors. Though Canadian diplomats recognized the benefits that military assistance might bring to the western world in the early 1950s, they were not especially anxious to divert scarce resources away from Europe towards the handful of small African and Asian states requesting aid. This was particularly true when any Canadian venture was likely to duplicate Washington’s substantial efforts to secure regional allies with promises of military assistance. As a consequence, the Department of External Affairs wasted little time and effort in convincing a reluctant Department of National Defence to accept military assistance as part of its mandate
The Importance of Off-Axis Beaming in Jet Models
Gamma-Ray Bursts (GRBs) are widely thought to originate from collimated jets
of material moving at relativistic velocities. Emission from such a jet should
be visible even when viewed from outside the angle of collimation. Using Monte
Carlo population synthesis methods and including the effects of this off-axis
beaming, we can compare various GRB jet models against the global properties of
observed bursts. We explore whether or not the X-Ray Flashes (XRFs) seen by
HETE-2 and BeppoSAX can be explained as classical GRBs viewed off-axis, and
begin to address the more general question of the importance of off-axis
beaming in current burst samples.Comment: 4 pages, 1 figure. Poster presented at the 4th Workshop Gamma-Ray
Bursts in the Afterglow Era, Rome,18-22 October 2004. Editors: L. Piro, L.
Amati, S. Covino, and B. Gendre. Il Nuovo Cimento, in pres
Risk and Growth: Theoretical Relationships and Preliminary Estimates for South Africa
In the recent literature on economic growth there is disagreement over the relationship between growth and volatility and their relative benefits and costs in welfare terms. An analytical resolution of this issue, which has serious implications for domestic and international development policies, has been seen to be contingent upon how relative risk aversion and intertemporal substitutability are related in frameworks characterizing utility maximization of representative agents. It is commonly assumed that these aspects of preferences are rigidly linked, casting doubt on the expected utility maximizing paradigm as an appropriate modeling methodology for analyzing this important issue. In this paper it is first shown that these concerns are only relevant for special functional forms that enforce a unitary consumption elasticity of wealth. Next, a theoretical approach is employed to specify a more general relationship between risk aversion and intertemporal substitutability. The theoretical model is developed in the context of a two country representative agent model where risk affects domestic and direct foreign investment in both countries. The two country orientation is also capable of interpretation of the relationship between one country and the rest of the world. In a preliminary empirical application of the methodology to South African data, we attempt estimation of the parameters of generalized functions for preferences and technology which are capable of distinguishing between risk aversion and intertemporal substitutability.
Jet Models of X-Ray Flashes
One third of all HETE-2--localized bursts are X-Ray Flashes (XRFs), a class
of events first identified by Heise in which the fluence in the 2-30 keV energy
band exceeds that in the 30-400 keV energy band. We summarize recent HETE-2 and
other results on the properties of XRFs. These results show that the properties
of XRFs, X-ray-rich gamma-ray bursts (GRBs), and GRBs form a continuum, and
thus provide evidence that all three kinds of bursts are closely related
phenomena. As the most extreme burst population, XRFs provide severe
constraints on burst models and unique insights into the structure of GRB jets,
the GRB rate, and the nature of Type Ib/Ic supernovae. We briefly mention a
number of the physical models that have been proposed to explain XRFs. We then
consider two fundamentally different classes of phenomenological jet models:
universal jet models, in which it is posited that all GRBs jets are identical
and that differences in the observed properties of the bursts are due entirely
to differences in the viewing angle; and variable-opening angle jet models, in
which it is posited that GRB jets have a distribution of jet opening angles and
that differences in the observed properties of the bursts are due to
differences in the emissivity and spectra of jets having different opening
angles. We consider three shapes for the emissivity as a function of the
viewing angle theta_v from the axis of the jet: power-law, top hat (or
uniform), and Gaussian (or Fisher). We then discuss the effect of relativistic
beaming on each of these models. We show that observations can distinguish
between these various models.Comment: 8 pages, 7 figures, 1 table. Invited review talk at the 4th Workshop
Gamma-Ray Bursts in the Afterglow Era, Rome,18-22 October 2004. Editors: L.
Piro, L. Amati, S. Covino, and B. Gendre. Il Nuovo Cimento, in pres
Productivity tradeoffs and synergies for grazing lands in central Queensland to generate carbon offsets
This paper reports research seeking to understand the economic implications for central Queensland graziers of participating in a carbon trading scheme and to measure the likely participation of graziers in an emissions trading scheme under various market design scenarios. An initial desktop study was undertaken to compare an enterprise which produced only cattle to one which produced cattle and sequestered carbon. The findings from this analysis were used to inform the design of an experimental auction to test alternative carbon trading scenarios. An experimental workshop was conducted at seven locations across central Queensland with a range of beef producers, extension officers and consultants. Participants were presented with a scenario in which they had the choice of maintaining current management practices against altering management practices to reduce beef production and enter into a carbon sequestration contract (CSC). They were asked at what price they would enter into a CSC and how that price and likelihood of participating would change under a range of alternative contract conditions. The results of the experimental auctions found significantly higher than breakeven prices for carbon would be required before landholders would offer land as a carbon offset. Participation rates were influenced by price and also the carbon contract rules. Five rule changes were trialled and all were found to have a significant impact on reducing participation and increasing required payment levels.Farm Management,
Gamma-Ray Burst Jet Profiles And Their Signatures
HETE-II and BeppoSAX have produced a sample of GRBs and XRFs with known
redshifts and . This sample provides four important empirical
constraints on the nature of the source jets: Log is approximately
uniformly distributed over several orders of magnitude; the inferred prompt
energy Log is narrowly distributed; the Amati relation holds
between and ; and the Ghirlanda relation holds between
and .
We explore the implications of these constraints for GRB jet structure during
the prompt emission phase. We infer the underlying angular profiles from the
first two of the above constraints assuming all jets have the same profile and
total energy, and show that such ``universal jet'' models cannot satisfy both
constraints.
We introduce a general and efficient method for calculating relativistic
emission distributions and distributions from jets with arbitrary
(smooth) angular jet profiles. We also exhibit explicit analytical formulas for
emission from top-hat jets (which are not smooth). We use these methods to
exhibit and as a function of viewing angle, for several
interesting families of GRB jet profiles. We use the same methods to calculate
expected frequency distributions of and for the same
families of models.
We then proceed to explore the behavior of universal jet models under a range
of profile shapes and parameters, to map the extent to which these models can
conform to the above four empirical constraints.Comment: 71 page, 33 figures. Submitted to Ap
Likelihood Analysis of GRB Evolution with Redshift
We present a likelihood approach to modeling multi-dimensional GRB
Epeak--fluence--redshift data that naturally incorporates instrument detection
thresholds. The treatment of instrument thresholds is essential for analyzing
evidence for GRB evolution. The method described here compares the data to a
uniform jet model, in which the jet parameters are allowed to vary with
redshift. Data from different experiments may be modeled jointly. In addition,
BATSE data (for which no redshift information is available) may be incorporated
by ascribing to each event a likelihood derived from the full model by
integrating the probability density over the unknown redshift. The loss of
redshift information is mitigated by the large number of available bursts. We
discuss the implementation of the method, and validation of it using simulated
data.Comment: 4 pages, 1 figure. Poster presented at the 4th Workshop Gamma-Ray
Bursts in the Afterglow Era, Rome,18-22 October 2004. Editors: L. Piro, L.
Amati, S. Covino, and B. Gendre. Il Nuovo Cimento, in pres
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