Finanças comportamentais e a formação de bolhas especulativas

Economic crises caused by speculative bubbles are recurring in economic history but there is still no consensus on how it begins, grows and overflows. Economists and regulators seem to be inefficient in predicting and preventing this process, which is so detrimental to economic functioning. This failure proved to be obvious with the American subprime crises, which had great impact on various sectors of the U.S. economy. In this paper, we perform a literature review of the traditional theory of finance, mainly represented by the Efficient Market Hypothesis. According to this theory, asset prices always reflect their intrinsic value, assumption that doesn’t match the price boom followed by a crash, observed in the crisis generated by speculative bubbles. Finally, we present a new way to analyze this phenomenon, in the light of the investors’ behavioral aspects and the flaws inherent to the financial markets

Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent F-statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3 x 10(-24) and 8 x 10(-25) are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof-of-principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of similar to 1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.