The Ultimatum Game and Gender Effect: Experimental Evidence from Pakistan

Laboratory experimentation was once considered impossible or irrelevant in economics. Recently, however, economic science has gone through a real ‘laboratory revolution’, and experimental economics is now a most lively subfield of the discipline. This study attempts to examine answers to questions of the changing behaviour of opposite sexes under conditions of both anonymity and knowledge of gender by playing the ultimatum game in Pakistan. It is observed that the behaviour of males and females in Pakistani society is quite different from that found in earlier studies. Insights from the previous experiments have already shown that normative economic theory had failed in its predictions of human behaviour. Currently, the ultimatum game is widely discussed in behavioural economic literature, and this paper will adjust the traditional ultimatum game into a new form wherein it will be tested in the country (Pakistan) with multidimensional behaviour of subjects. With regard to gender effect specifically, all previous studies came up with somewhat mixed results, since results do not always point in the same direction and it is rather early to draw far-reaching conclusions regarding the behavioural differences of men and women. More facts are required in order to move towards the development of a systematic theory. This work is a small attempt to investigate the changing behaviour of opposite sexes under different controlled conditions.Ultimatum Game, Human Sex Difference, Social Behaviour

Gamma Ray Bursts in the Swift-Fermi Era

Gamma-ray bursts (GRBs) are among the most violent occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole birth. They are highly luminous events and provide excellent probes of the distant universe. GRB research has greatly advanced over the past 10 years with the results from Swift, Fermi and an active follow-up community. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.Comment: 16 pages and 15 figures. Invited review article to appear in the special issue of Frontiers of Physics on High Energy Astrophysics, eds. B. Zhang and P. Meszaro

Do Expectations Play Any Role in Determining Pak Rupee Exchange Rates?

This paper presents some evidence on the role of expectations in the determination of Pak rupee exchange rates vis-à-vis the dollar, pound, and yen over the period 1982:1– 1993:7. Results of cointegration and coefficient restriction tests in two out of three cases are supportive of the view of exchange rate determination in postulating that in efficient markets in which uncertainty and expectations about the future are dominant, the equilibrium nominal exchange rate is determined not only by current relative prices but also by the expected real exchange rate. These results are supportive of ex ante purchasing power parity, implying that the real exchange rate follows a random walk. These results also suggest that the anticipated inflation rate is higher in Pakistan than in other countries, which tends to encourage the domestic residents to convert their current balances into foreign currency, so that the terms of trade deteriorate and offset much of gains of the continuous devaluation of Pak rupee by undermining external competitiveness.

The Galactic Center Origin of a Subset of IceCube Neutrino Events

The center of the Milkyway is a host to energetic phenomena across many electromagnetic wave-bands and now possibly of high-energy neutrinos. We show that 5 out of 21 IceCube shower-like events, including a PeV event, likely originated from the Galactic Center region. Hard spectrum and flux inferred from these events are inconsistent with atmospheric neutrinos. The flux of these neutrinos is consistent with an extrapolation of the gamma-ray flux measured by Fermi-LAT from the inner Galactic region. This indicates a common hadronic origin of both, powered by supernovae. Three other shower-like events are spatially correlated with the Fermi bubbles, originating from the Galactic Center activity, within the uncertainty of reconstructing their arrival directions. Origin of the other neutrino events, including 7 track-like events, is still elusive.Comment: 4 pages, 1 figure. Accepted for publication in PRD Rapid Communicatio

A Correct Test of Purchasing Power Parity: The Case of Pak-Rupee Exchange Rates

This paper presents some empirical evidence on long-run purchasing power parity (PPP) for eight Pak-rupee exchange rates over the period 1982:1–1994:4. Results obtained from testing for cointegration and coefficient restrictions using the Johansen (1988, 1991) procedure are supportive of PPP in almost all cases. These results are also supported by those obtained from testing for mean reversion in the real exchange rate using the Sims (1988) Bayesian test. One of the conclusions that emerge from these results is that devaluation of Pak-rupee vis-à-vis major industrial currencies under investigation may be unlikely to improve the country’s external competitiveness and, consequently, the deficit in its trade balance.

Angular correlation of cosmic neutrinos with ultrahigh-energy cosmic rays and implications for their sources

Cosmic neutrino events detected by the IceCube Neutrino Observatory with energy $\gtrsim 30$ TeV have poor angular resolutions to reveal their origin. Ultrahigh-energy cosmic rays (UHECRs), with better angular resolutions at $>60$ EeV energies, can be used to check if the same astrophysical sources are responsible for producing both neutrinos and UHECRs. We test this hypothesis, with statistical methods which emphasize invariant quantities, by using data from the Pierre Auger Observatory, Telescope Array and past cosmic-ray experiments. We find that the arrival directions of the cosmic neutrinos are correlated with $\ge 100$ EeV UHECR arrival directions at confidence level $\approx 93\%$. The strength of the correlation decreases with decreasing UHECR energy and no correlation exists at energy $\sim 60$ EeV. A search in astrophysical databases within $3^\circ$ of the arrival directions of UHECRs with energy $\ge 100$ EeV, that are correlated with the IceCube cosmic neutrinos, resulted in 18 sources from the Swift-BAT X-ray catalog with redshift $z\le 0.06$. We also found 3 objects in the K\"uhr catalog of radio sources using the same criteria. The sources are dominantly Seyfert galaxies with Cygnus A being the most prominent member. We calculate the required neutrino and UHECR fluxes to produce the observed correlated events, and estimate the corresponding neutrino luminosity (25 TeV-2.2 PeV) and cosmic-ray luminosity (500 TeV-180 EeV), assuming the sources are the ones we found in the Swift-BAT and K\"uhr catalogs. We compare these luminosities with the X-ray luminosity of the corresponding sources and discuss possibilities of accelerating protons to $\gtrsim 100$ EeV and produce neutrinos in these sources.Comment: 23 pages, 8 figures and 5 tables. Minor changes, improved presentation, added a new figure (Fig.4). Accepted for publication in JCA

A self-consistent model of cosmic-ray fluxes and positron excess: Roles of nearby pulsars and a sub-dominant source population

The cosmic-ray positron flux calculated using the cosmic-ray nuclei interactions in our Galaxy cannot explain observed data above 10 GeV. An excess in the measured positron flux is therefore open to interpretation. Nearby pulsars, located within sub-kiloparsec range of the Solar system, are often invoked as plausible sources contributing to the excess. We show that an additional, sub-dominant population of sources together with the contributions from a few nearby pulsars can explain the latest positron excess data from the Alpha Magnetic Spectrometer (AMS). We simultaneously model, using the DRAGON code, propagation of cosmic-ray proton, Helium, electron and positron and fit their respective flux data. Our fit to the Boron to Carbon ratio data gives a diffusion spectral index of 0.45, which is close to the Kraichnan turbulent spectrum.Comment: Updated with modified model parameters for nearby pulsar contributions, main results unchanged.Accepted in JCA

Oscillation effects on high-energy neutrino fluxes from astrophysical hidden sources

High-energy neutrinos are expected to be produced in a vareity of astrophysical sources as well as in optically thick hidden sources. We explore the matter-induced oscillation effects on emitted neutrino fluxes of three different flavors from the latter class. We use the ratio of electron and tau induced showers to muon tracks, in upcoming neutrino telescopes, as the principal observable in our analysis. This ratio depends on the neutrino energy, density profile of the sources and on the oscillation parameters. The largely unknown flux normalization drops out of our calculation and only affects the statistics. For the current knowledge of the oscillation parameters we find that the matter-induced effects are non-negligible and the enhancement of the ratio from its vacuum value takes place in an energy range where the neutrino telescopes are the most sensitive. Quantifying the effect would be useful to learn about the astrophysics of the sources as well as the oscillation parameters. If the neutrino telescopes mostly detect diffuse neutrinos without identifying their sources, then any deviation of the measured flux ratios from the vacuum expectation values would be most naturally explained by a large population of hidden sources for which matter-induced neutrino oscillation effects are important.Comment: Phys.Rev.D accepted version. 12 pages, 10 figures. Results unchanged, added references, minor changes and text re-arrangement

Ultrahigh-energy neutrino flux as a probe of large extra-dimensions

A suppression in the spectrum of ultrahigh-energy (UHE, >= 10^{18} eV) neutrinos will be present in extra-dimensional scenarios, due to enhanced neutrino-antineutrino annihilation processes with the supernova relic neutrinos. In the n>4 scenario, being n the number of extra dimensions, neutrinos can not be responsible for the highest energy events observed in the UHE cosmic ray spectrum. A direct implication of these extra-dimensional interactions would be the absence of UHE neutrinos in ongoing and future neutrino telescopes.Comment: JCAP accepted version. Included 5, 6 and 7 extra-dimensional cases, and 2 new figures. The conclusion remains unchanged that UHE neutrino flux would be suppressed in large extra-dimensional model