Generalizing Merton's approach of pricing risky debt: some closed form results

In this work, I generalize Merton's approach of pricing risky debt to the case where the interest rate risk is modeled by the CIR term structure. Closed form result for pricing the debt is given for the case where the firm value has non-zero correlation with the interest rate. This extends previous closed form pricing formular of zero-correlation case to the generic one of non-zero correlation between the firm value and the interest rate.Comment: 7 pages, Revtex styl

Prokaryotic expression, purification and immunogenicity analysis of CpsD protein from Streptococcus iniae

Streptococcus iniae is a major cause of serious bacterial infections in both fish and human beings. Capsular polysaccharide (CPS) of S. iniae is vital to evade phagocytic clearance of the host and serves as an important protective antigen of S. iniae infection in aquatic animals. The CpsD gene was determined to be highly conservative in capsule polysaccharide operon. Prokaryotic expression of the CpsD gene of a clinical isolate of S. iniae from channel catfish and immunogenic examination of the recombinant protein were first described in this essay. The recombinant protein was expressed in the form of inclusion bodies (IBs). Induction conditions in Escherichia coli were optimized with 0.6mM Isopropyl β-D-1-Thiogalactopyranoside at 37°C for 5h after the culture mid-log phase in Luria Bertani (LB) medium. The recombinant protein CpsD was thus expressed and purified by immobilized metal affinity chromatography (IMAC), yielding approximate 582.47 mg the protein per liter culture. Western blot analysis showed that the purified CpsD had reactogenicity. It will possibly reveal more details of capsule synthesis and capsule regulation during various stages of the S. iniae infectious process

Quantum duality and Bethe-ansatz for the Hofstadter problem on hexagonal lattice

The Hofstadter problem is studied on hexagonal lattice. We first establish a relation between the spectra for the hexagonal lattice and for its dual he triangular lattice. Following the idea of Faddeev and Kashaev, we then obtain the Bethe-ansatz equations for this system.Comment: 8 pages, latex, revised version for Phys. Lett.

A remark on interacting anyons in magnetic field

In this remark, we note that the anyons, interacting with each other through pairwise potential in external magnetic field, exhibit a simple quantum group symmetry.Comment: IPT-EPFL preprint, typos fixed, minor corrections, references updated, submitted to Physics Letter A

Spherical collapse with dark energy

I discuss the work of Maor and Lahav [1], in which the inclusion of dark energy into the spherical collapse formalism is reviewed. Adopting a phenomenological approach, I consider the consequences of - a) allowing the dark energy to cluster, and, b) including the dark energy in the virialization process. Both of these issues affect the final state of the system in a fundamental way. The results suggest a potentially differentiating signature between a true cosmological constant and a dynamic form of dark energy. This signature is unique in the sense that it does not depend on a measurement of the value of the equation of state of dark energy.Comment: To appear in the proceedings of the ``Peyresq Physics 10" Workshop, 19 - 24 June 2005, Peyresq, Franc

Gravitational Collapse of Phantom Fluid in (2+1)-Dimensions

This investigation is devoted to the solutions of Einstein's field equations for a circularly symmetric anisotropic fluid, with kinematic self-similarity of the first kind, in $(2+1)$-dimensional spacetimes. In the case where the radial pressure vanishes, we show that there exists a solution of the equations that represents the gravitational collapse of an anisotropic fluid, and this collapse will eventually form a black hole, even when it is constituted by the phantom energy.Comment: 10 page

Effects of Temperature and Moisture on Sheet Molding Compounds

A summary is given on the effects of moisture and temperature on the properties of chopped fiber reinforced sheet molding compounds. The properties surveyed include tensile strength and modulus, compression strength and modulus, shear strength and modulus, flexural strength and modulus, fatigue, creep, vibration damping, moisture absorption characteristics, and thermal expansion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68648/2/10.1177_073168448300200201.pd

On the ultimate convergence rates for isotropic algorithms and the best choices among various forms of isotropy

In this paper, we show universal lower bounds for isotropic algorithms, that hold for any algorithm such that each new point is the sum of one already visited p oint plus one random isotropic direction multiplied by any step size (whenever the step size is chosen by an oracle with arbitrarily high computational power). The bound is 1 − O(1/d) for the constant in the linear convergence (i.e. the constant C such that the distance to the optimum after n steps is upp er b ounded by C n ), as already seen for some families of evolution strategies in [19, 12], in contrast with 1 − O(1) for the reverse case of a random step size and a direction chosen by an oracle with arbitrary high computational power. We then recall that isotropy does not uniquely determine the distribution of a sample on the sphere and show that the convergence rate in isotropic algorithms is improved by using stratified or antithetic isotropy instead of naive isotropy. We show at the end of the pap er that b eyond the mathematical proof, the result holds on exp eriments. We conclude that one should use antithetic-isotropy or stratified-isotropy, and never standard-isotropy

The floor in the interplanetary magnetic field: Estimation on the basis of relative duration of ICME observations in solar wind during 1976-2000

To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use global solar parameters: we identified different large-scale types of solar wind for 1976-2000 interval, obtained a fraction of interplanetary CMEs (ICMEs) and calculated magnitude of interplanetary magnetic field B averaged over 2 Carrington rotations. The floor of magnetic field is estimated as B value at solar cycle minimum when the ICMEs were not observed and it was calculated to be 4,65 \pm 6,0 nT. Obtained value is in a good agreement with previous results.Comment: 10 pages, 2 figures, submitted in GR