Electrostatic in Reissner-Nordstrom space-time with a conical defect

We calculate the electrostatic potential generated by a point charge in the space-time of Reissner-Nordstrom with a conical defect. An expression for the self-energy is also presented.Comment: 7 pages, LATEX fil

Common Subcontracting and Airline Prices

In the US airline industry, independent regional airlines fly passengers on behalf of several national airlines across different markets, giving rise to $\textit{common subcontracting}$. On the one hand, we find that subcontracting is associated with lower prices, consistent with the notion that regional airlines tend to fly passengers at lower costs than major airlines. On the other hand, we find that $\textit{common}$ subcontracting is associated with higher prices. These two countervailing effects suggest that the growth of regional airlines can have anticompetitive implications for the industry

Eternal inflation and the initial singularity

It is shown that a physically reasonable spacetime that is eternally inflating to the future must possess an initial singularity.Comment: 11 pages, Tufts University cosmology preprin

BPS String Solutions in Non-Abelian Yang-Mills Theories and Confinement

Starting from the bosonic part of N=2 Super QCD with a 'Seiberg-Witten' N=2 breaking mass term, we obtain string BPS conditions for arbitrary semi-simple gauge groups. We show that the vacuum structure is compatible with a symmetry breaking scheme which allows the existence of Z_k-strings and which has Spin(10) -> SU(5) x Z_2 as a particular case. We obtain BPS Z_k-string solutions and show that they satisfy the same first order differential equations as the BPS string for the U(1) case. We also show that the string tension is constant, which may cause a confining potential between monopoles increasing linearly with their distance.Comment: 11 pages, Latex. Minor changes to the text. Final version to appear in Phys. Rev.

Scattering off an SO(10) cosmic string

The scattering of fermions from the abelian string arising during the phase transition $SO(10) \rightarrow SU(5) \times Z_2$ induced by the Higgs in the 126 representation is studied. Elastic cross-sections and baryon number violating cross-sections due to the coupling to gauge fields in the core of the string are computed by both a first quantised method and a perturbative second quantised method. The elastic cross-sections are found to be Aharonov-Bohm type. However, there is a marked asymmetry between the scattering cross-sections for left and right handed fields. The catalysis cross-sections are small, depending on the grand unified scale. If cosmic strings were observed our results could help tie down the underlying gauge group.Comment: 20 page

Stochastic inflation on the brane

Chaotic inflation on the brane is considered in the context of stochastic inflation. It is found that there is a regime in which eternal inflation on the brane takes place. The corresponding probability distributions are found in certain cases. The stationary probability distribution over a comoving volume and the creation probability of a de Sitter braneworld yield the same exponential behaviour. Finally, nonperturbative effects are briefly discussed.Comment: 9 page

Learning from implementation of the sanitation and hygiene master plan in Nepal

This briefing paper has been prepared based on the basis of field level experiences. It highlights the emerging decentralized leadership in the WASH sector in light of the Master Plan and ODF movement in Nepal. The Master Plan has introduced innovative institutional arrangement of inclusive WASH Coordination Committees to lead ODF movement. These committees leadership of such committees hashave come up with several innovations in planning, financing, implementation and monitoring, and promoting inclusive and participatory governance process in sanitation development. Nepal's sanitation campaign has visibly scaled up ODF status despite some shortcomings. Mobilization of local resources is possible through local leadership, sustainability requires equal emphasis on behavioural and facility aspects and advocacy for health benefits of the improved sanitation are the prime drivers for changes. Similarly, cross-learning are vital for innovations in the sector and integration of sanitation with other development sector activities enhances synergy. The post-ODF intervention is leading the sanitation sector towards livelihood promotion and social wellbeing aspect too