QCD in neutron stars and strange stars

This paper provides an overview of the possible role of Quantum Chromo Dynamics (QDC) for neutron stars and strange stars. The fundamental degrees of freedom of QCD are quarks, which may exist as unconfined (color superconducting) particles in the cores of neutron stars. There is also the theoretical possibility that a significantly large number of up, down, and strange quarks may settle down in a new state of matter known as strange quark matter, which, by hypothesis, could be more stable than atomic nuclei. In the latter case new classes of self-bound, color superconducting objects, ranging from strange quark nuggets to strange quark stars, should exist. The properties of such objects will be reviewed along with the possible existence of deconfined quarks in neutron stars. Implications for observational astrophysics are pointed out.Comment: 7 pages, 2 figures; presented at the T(R)OPICAL QCD Workshop, September 26 - October 2, 2010, Cairns, Australi

Sovereign debt (re)structuring-Where do we stand?

Argentina’s debt default in 2001 moved the international community to launch initiatives to develop procedures for the orderly restructuring of unsustainable sovereign debt. These initiatives come against the backdrop of the increase in public debt in emerging market economies over the last decade, of large-scale fi nancial crises linked to the level or structure of sovereign debt and, a recent development, of several cases of sovereign default on international bonds. These developments pose two challenges. Firstly, the complexity of sovereign debt dynamics makes it necessary to strengthen international institutions’ assessment capacity. The International Monetary Fund (IMF) has thus launched initiatives to improve the assessment of debt sustainability and balance sheet weaknesses. Secondly, the developments have prompted the re-examination of IMF facilities for managing debt crises. The absence of a clear framework in this area could create a moral hazard risk, as the international community could be tempted to avoid necessary restructuring by granting substantial fi nancial assistance. In practice, defining such a framework is complex, given that reforms in the area of restructuring influence the way in which debts are structured. In fact, the features of sovereign debt aim to reconcile two requirements: first, ensuring that the sovereign debtor honours the terms of the debt contract if it has the means to do so (ex ante efficiency); second, making sure that the cost of default is not excessive when the sovereign debtor is effectively unable to pay back (ex post effi ciency). The international community currently favours a market-based approach. Its first pillar is a result of the development and spread of collective action clauses (CAC), following the Quarles Report by the Group of 10. Incorporated into debt contracts, CAC aim to reduce the problems arising in inter-creditor co-ordination, by defi ning, in advance, the decision rules applicable in the event of re-negotiation. The “Principles for Stable Capital Flows and Fair Debt Restructuring in Emerging Markets”, whose defi nition was fostered notably by the Governor of the Banque de France and the Group of 20, form the second pillar. They supply guidelines for the parties involved to steer the exchange of information and facilitate co-ordination between debtors and creditors. The market-based approach is not exclusive of a formal regime, e.g. the IMF’s Sovereign Debt Restructuring Mechanism (SDRM), where such a regime is feasible. In the market-based approach, the IMF acts as an expert via the supply of information and analyses, and also as a “monitor” via the negotiation and monitoring of programmes. The provision of loans, which is in principle limited, aims mainly to facilitate renegotiation by giving credibility to the sovereign’s policy. By contrast, a more formal regime would suppose limiting IMF involvement, so as to guarantee the independence of the mechanism. Whatever the case, the efficiency of the overhauled restructuring framework, which is built on contractual provisions and general principles rather than on a formal regime, will depend on the Fund’s capacity to fully perform its three functions.

DCP-collected absolute target reflectance signatures assist accurate interpretation of ERTS-1 imagery

Data collection platforms (DCP's) are being used at a Black Hills, South Dakota, test site (MMC 226A) to record radiometric measurements needed to determine solar and atmospheric parameters that affect ERTS-1 multispectral scanner radiance measurements. A total of 72 channels of analog data transmitted from an unattended ground truth site via three DCP's at least six times a day. The system has operated with only minor problems since September, sending forth daily measurements of biophysical responses and atmospheric conditions. Comparisons of scene radiance data calculated from ERTS images with that measured on the ground show the image-measured values to be 35 percent higher for the green channel and 20 percent higher for the red channel for the same scene targets. Radiance values for channels 6 and 7 are nearly the same from the ground data and from the imagery

Spin Clustering of Accreting X-ray Neutron Stars as Possible Evidence of Quark Matter

A neutron star in binary orbit with a low-mass non-degenerate companion becomes a source of x-rays with millisecond variability when mass accretion spins it up. Centrifugally driven changes in density profile may initiate a phase transition in a growing region of the core parallel to what may take place in an isolated millisecond pulsar, but in reverse. Such a star will spend a longer time in the spin frequency range over which the transition occurs than elsewhere because the change of phase, paced by the spinup rate, is accompanied by a growth in the moment of inertia. The population of accreters will exhibit a clustering in the critical frequency range. A phase change triggered by changing spin and the accompanying adjustment of moment of inertia has its analogue in rotating nuclei.Comment: 5 pages (AIPproc latex) 6 figures. To be presented at the International Conference on Nuclear Physics, 30 July - 3 August 2001, Berkeley, Californi

The Global Spread of Stock Exchange, 1980-1998

Nations opened local stock exchanges at a rapid pace during the late 1980s and 1990s, creating a channel for investment capital from wealthy industrial nations to "emerging markets" as well as a mechanism for institutional change in local economies. This study examines the local and global processes by which exchanges spread, examining all nations "at risk" during the 1980s and 1990s. We find that local factors influencing the creation of stock exchanges included the size of the economy (overall and relative to population size); the legacy of colonialism; and a recent transition to multi-party democracy. Global factors associated with creating exchanges included levels of prior investment by multinationals; IMF "structural adjustment" aid; centrality in trade flows; and regional "contagion." In contrast to prior work in financial economics, we find no evidence for the influence of legal tradition, and contrary to the implications of dependency theory, we find no sign that foreign capital penetration affects the creation of exchanges. We also find no consistent evidence for the influence of stock exchanges on inequality or human development at the national level, above and beyond their effect on economic and population growth. The results indicate that globalization is usefully construed as a process analogous to institutional diffusion at the organization level.http://deepblue.lib.umich.edu/bitstream/2027.42/39725/3/wp341.pd

Laser Doppler spectrometer method of particle sizing

A spectrometer for the detection of airborne particulate pollution in the submicron size range is described. In this device, airborne particles are accelerated through a supersonic nozzle, with different sizes achieving different velocities in the gas flow. Information about the velocities of the accelerated particles is obtained with a laser-heterodyne optical system through the Doppler shift of light scattered from the particles. Detection is accomplished by means of a photomultiplier. Nozzle design and signal processing techniques are also discussed

Semi-infinite optimization: Structure and stability of the feasible set

The problem of the minimization of a functionf: ℝn→ℝ under finitely many equality constraints and perhaps infinitely many inequality constraints gives rise to a structural analysis of the feasible setM[H, G]={x∈ℝn¦H(x)=0,G(x, y)≥0,y∈Y} with compactY⊂ℝr. An extension of the well-known Mangasarian-Fromovitz constraint qualification (EMFCQ) is introduced. The main result for compactM[H, G] is the equivalence of the topological stability of the feasible setM[H, G] and the validity of EMFCQ. As a byproduct, we obtain under EMFCQ that the feasible set admits local linearizations and also thatM[H, G] depends continuously on the pair (H, G). Moreover, EMFCQ is shown to be satisfied generically