SWIFT J1749.4-2807: A neutron or quark star?

We investigate an unique accreting millisecond pulsar with X-ray eclipses, SWIFT J1749.4$-$2807 (hereafter J1749), and try to limit the binary system by various methods including that of the Roche lobe, the mass-radius relations of both a main sequence (MS) and a white dwarf (WD) companion stars, as well as the measured mass function of the pulsar. The calculations are based on the assumption that the radius of the companion star has reached its Roche radius (or at 90%), but the pulsar's mass has not been assumed to be a certain value. Our results are as follows. The companion star should be a MS. For the case that the radius equals to its Roche one, we have a companion star with mass $M\simeq 0.51 M_{\odot}$ and radius $R_{\rm c}\simeq 0.52R_{\odot}$, and the inclination angle is $i\simeq 76.5^{\circ}$; for the case that the radius reaches 90% of its Roche one, we have $M\simeq 0.43M_{\odot}$, $R_{\rm c}\simeq 0.44R_{\odot}$ and $i\simeq 75.7^{\circ}$. We also obtain the mass of J1749, $M_{\rm p}\simeq 1M_\odot$, and conclude that the pulsar could be a quark star if the ratio of the critical frequency of rotation-mode instability to the Keplerian one is higher than $\sim 0.3$. The relatively low pulsar mass (about $\sim M_\odot$) may also challenge the conventional recycling scenario for the origin and evolution of millisecond pulsars. The results presented in this paper are expected to be tested by future observations.Comment: RAA accepte

Elvira Roche

Sabem més coses de Darwin que de Caja

The Roche problem: some analytics

Some exact analytical formulas are derived for the potential and mass ratio as a function of Lagrangian points position, in the classical Roche model of the close binary stars.Comment: aastex, 4 pp. ApJ accepte

Book Reviews

Fair Play: The Moral Dilemmas of Spying. By James M. Olson. The Corporate Spy: Industrial Espionage and Counterintelligence inthe Multinational Enterprise with Case Studies (Abridged Version) by Edward M. Roche

Mergers & acquisitions : pharmaceutical and biotechnology sector case study

A glance at the worldwide M&A activity of pharmaceutical companies tells us that consolidation within this sector has not been reached and won’t be soon. The trend of acquiring small biotech start-ups with promising research pipelines is essential for big pharmas to survive their highly competitive sector. Additionally, the global population is rapidly aging and hence, age-related diseases like Alzheimer Disease (AD) will increase and, with them, the need for treatments will rise. Therefore, big pharmaceutical companies need to strengthen their product pipelines with efficient, innovative market-disrupting solutions. For Roche, one of the world’s largest pharmaceuticals, the need to enhance their neuroscience product pipeline has recently increased, due to the failure in passing Phase III of its most promising AD drug in 2014. To “solve” this issue, this work provides a detailed evaluation of a potential M&A deal between Roche and the small German biotech Probiodrug, which, through an innovative approach, created a highly promising AD product, currently in Phase II. With successful approval of this product this deal will provide Roche with an increase in future sales and gives more potential for further research. This work argues that Roche should make an offer with a 41% premium over todays share price, which is equal to EUR 29,78 per share. The total deal value will be EUR 202 mm and paid 100% in cash. Considering the possible synergy creation of the acquisition, in negotiations the total offer price might range from 41% up to 120% over the current share price

Re-nuclearization or Disarmament: A Fateful Choice for Humanity

In light of the real possibility that terrorists could acquire and use nuclear weapons to kill hundreds of thousands of innocent people, never has the need to eliminate the threat posed by nuclear weapons been more urgent. Tragically, this sense of urgency was not shared by many delegates to thethird and final meeting of the Preparatory Committee for the 2005 Review Conference of the NonProliferation Treaty (NPT). The meeting at the U.N. in New York ended May 7, 2004 in disarray, the delegates unable to agree even on an agenda and background documentation for the Review Conference. Acrimony and weak leadership characterized the PrepComm. Issues of substance concerning the future of nuclear weapons were lost in the procedural wrangling that dominated the final two days of the two-week meeting. This is the last of three reports on the meetings in 2002, 2003 and 2004, of the Preparatory Committee for the 2005 Review Conference of the Non-Proliferation Treaty. The first two reports, "The NPT: Crisis and Challenge" (2002) and "Ritualistic Facade" (2003), are available on Senator Roche's website (http://www.sen.parl.gc.ca/droche)