3,697 research outputs found
Covariant hamiltonian spin dynamics in curved space-time
The dynamics of spinning particles in curved space-time is discussed,
emphasizing the hamiltonian formulation. Different choices of hamiltonians
allow for the description of different gravitating systems. We give full
results for the simplest case with minimal hamiltonian, constructing constants
of motion including spin. The analysis is illustrated by the example of motion
in Schwarzschild space-time. We also discuss a non-minimal extension of the
hamiltonian giving rise to a gravitational equivalent of the Stern-Gerlach
force. We show that this extension respects a large class of known constants of
motion for the minimal case.Comment: 14 pages, accepted version for Phys Lett B, added a footnote and two
reference
Modeling highly pathogenic avian influenza transmission in wild birds and poultry in West Bengal, India.
Wild birds are suspected to have played a role in highly pathogenic avian influenza (HPAI) H5N1 outbreaks in West Bengal. Cluster analysis showed that H5N1 was introduced in West Bengal at least 3 times between 2008 and 2010. We simulated the introduction of H5N1 by wild birds and their contact with poultry through a stochastic continuous-time mathematical model. Results showed that reducing contact between wild birds and domestic poultry, and increasing the culling rate of infected domestic poultry communities will reduce the probability of outbreaks. Poultry communities that shared habitat with wild birds or those indistricts with previous outbreaks were more likely to suffer an outbreak. These results indicate that wild birds can introduce HPAI to domestic poultry and that limiting their contact at shared habitats together with swift culling of infected domestic poultry can greatly reduce the likelihood of HPAI outbreaks
Emerging Markets for GM Foods: An Indian Perspective on Consumer Understanding and Willingness to Pay
This paper addresses the issues of consumer awareness, opinion, acceptance and willingness to pay for GM foods in the Indian market. A random utility approach is used to estimate a logit equation which indicates what factors affect the likelihood of consumption of non-GM and GM foods and whether or not consumers are willing to pay a premium for non-GM/GM foods. Data was generated through questionnaire survey which was administered to 602 respondents in the city of Ahmedabad and 110 respondents on internet. More than 90% of the respondents from the city survey did not know about GM foods. However, after informing them about the pros and cons of GM foods, more than 70% were willing to consume even if GM and non-GM foods were available for the same price. Ceteris paribus as the price difference between non-GM and GM food rose, people were more likely to consume GM foods. Likelihood of GM food consumption seemed to increase as one moved from very poor and not-so-poor income brackets to higher income brackets. Being a female or a joint family member increased the likelihood of choosing non-GM rice and edible oil. On an average, consumers were willing to pay 19.5% and 16.12% premiums for golden rice and GM edible oil, respectively. Overall, it appears that GM foods will be acceptable in the Indian market. However, consumer education societies, government ministries, and food companies may have to create awareness about the GM foods among Indian consumers.
Emerging Markets for GM Foods: A Study of Consumer's Willingness to Pay in India
A random utility approach is used to estimate logit equations which indicate what factors affect the likelihood of consumption of non-GM and GM foods, and, whether or not consumers are willing to pay a premium for non-GM/GM foods. Ceteris paribus as the price difference between non-GM and GM food rose, people were more likely to consume GM foods. Likelihood of GM food consumption was higher in the middle income brackets. Consumers were willing to pay an expected premium of 19.5% and 16.12% for golden rice and GM edible oil respectively. In case of chicken, consumers seemed to pay a very negligible premium for non-GM fed chicken. Overall, it appears that GM foods may be acceptable in the Indian market. However, basic awareness about the GM foods may have to be created among the consumers through government ministries, consumer interest groups, and biotech food-crop companies.GM Foods, Golden Rice, Bt cottonseed oil, GM fed chicken, Willingness to Pay, Random utility approach, Logit, India., Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Q13, D12,
Some Observations on Non-covariant Gauges and the epsilon-term
We consider the Lagrangian path-integrals in Minkowski space for gauges with
a residual gauge-invariance. From rather elementary considerations, we
demonstrate the necessity of inclusion of an epsilon-term (even) in the formal
treatments, without which one may reach incorrect conclusions. We show,
further, that the epsilon-term can contribute to the BRST WT-identities in a
nontrivial way (even as epsilon-->0). We also show that the (expectation value
of the) correct epsilon-term satisfies an algebraic condition. We show by
considering (a commonly used) example of a simple local quadratic epsilon
-term, that they lead to additional constraints on Green's function that are
not normally taken into account in the BRST formalism that ignores the
epsilon-term, and that they are characteristic of the way the singularities in
propagators are handled. We argue that for a subclass of these gauges, the
Minkowski path-integral could not be obtained by a Wick rotation from a
Euclidean path-integral.Comment: 12 pages, LaTeX2
Absence of Nonlocal Counter-terms in the Gauge Boson Propagator in Axial -type Gauges
We study the two-point function for the gauge boson in the axial-type gauges.
We use the exact treatment of the axial gauges recently proposed that is
intrinsically compatible with the Lorentz type gauges in the path-integral
formulation and has been arrived at from this connection and which is a
``one-vector'' treatment. We find that in this treatment, we can evaluate the
two-point functions without imposing any additional interpretation on the axial
gauge 1/(n.q)^p-type poles. The calculations are as easy as the other
treatments based on other known prescriptions. Unlike the
``uniform-prescription'' /L-M prescription, we note, here, the absence of any
non-local divergences in the 2-point proper vertex. We correlate our
calculation with that for the Cauchy Principal Value prescription and find from
this comparison that the 2-point proper vertex differs from the CPV calculation
only by finite terms. For simplicity of treatment, the divergences have been
calculated here with n^2>0 and these have a smooth light cone limit.Comment: 17 pages; 3 figures drawn using feyn.st
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