Precession of the Isolated Neutron Star PSR B1828-11

Stairs, Lyne & Shemar have found that arrival time residuals from PSR B1828-11 vary periodically with a period of 500 days. This behavior can be accounted for by precession of the radiopulsar, an interpretation that is reinforced by the detection of variations in its pulse profile on the same timescale. Here, we model the period residuals from PSR B1828-11 in terms of precession of a triaxial rigid body. We include two contributions to the residuals: (i) the geometric effect, which arises because the times at which the pulsar emission beam points toward the observer varies with precession phase; (ii) the spindown contribution, which arises from any dependence of the spindown torque acting on the pulsar on the angle between its spin and magnetic axes. We use the data to probe numerous properties of the pulsar, most notably its shape, and the dependence of its spindown torque on the angle between its spin and magnetic axes, for which we assume a sum of a spin-aligned component (with a weight 1-a) and a dipolar component perpendicular to the magnetic beam axis (weight a), rather than the vacuum dipole torque (a=1). We find that a variety of shapes are consistent with the residuals, with a slight statistical preference for a prolate star. Moreover, a range of torque possibilities fit the data equally well, with no strong preference for the vacuum model. In the case of a prolate star we find evidence for an angle-dependent spindown torque. Our results show that the combination of geometrical and spin-down effects associated with precession can account for the principal features of PSR B1828-11's timing behavior, without fine tuning of the parameters.Comment: 22 pages, 14 figures, submitted to MNRAS; added references, corrected typo

Geometry of Gaussian quantum states

We study the Hilbert-Schmidt measure on the manifold of mixed Gaussian states in multi mode continuous variable quantum systems. An analytical expression for the Hilbert-Schmidt volume element is derived. Its corresponding probability measure can be used to study typical properties of Gaussian states. It turns out that although the manifold of Gaussian states is unbounded, an ensemble of Gaussian states distributed according to this measure still has a normalizable distribution of symplectic eigenvalues, from which unitarily invariant properties can be obtained. By contrast, we find that for an ensemble of one-mode Gaussian states based on the Bures measure the corresponding distribution cannot be normalized. As important applications, we determine the distribution and the mean value of von Neumann entropy and purity for the Hilbert-Schmidt measure

Barriers Inhibiting Industry from Partnering with Universities: Evidence from the Advanced Technology Program

A small sample of 38 Advanced Technology Projects funded between 1993 and 1996 are surveyed to explore the reasons for university non-participation, or, in the cases where they did participate, whether the partnerships encountered any difficulties from their participation. 32 percent report that intellectual property issues were an insurmountable barrier to university participation. Such barriers are more likely when the ATP share of funding is high and when the expected duration of the research is relatively short. They are also somewhat more likely for projects involving chemical technology, and when industrial participants have had previous experience with universities as research partners. These difficulties over IP may arise because the cultures in the two institutional forms differ, or because the original ATP guidelines do not recognize the existence of the Bayh-Dole Act (which grants universities title to inventions made by their employees using outside funding).

Evolution of a fluorinated green fluorescent protein

The fluorescence of bacterial cells expressing a variant (GFPm) of the green fluorescent protein (GFP) was reduced to background levels by global replacement of the leucine residues of GFPm by 5,5,5-trifluoroleucine. Eleven rounds of random mutagenesis and screening via fluorescence-activated cell sorting yielded a GFP mutant containing 20 amino acid substitutions. The mutant protein in fluorinated form showed improved folding efficiency both in vivo and in vitro, and the median fluorescence of cells expressing the fluorinated protein was improved {approx}650-fold in comparison to that of cells expressing fluorinated GFPm. The success of this approach demonstrates the feasibility of engineering functional proteins containing many copies of abiological amino acid constituents

The Rwenzori Mountains, a Paleoproterzoic crustal shear belt crossing the Albertine rift system

This contribution discusses the development of the Paleoproterozoic Buganda-Toro belt in the Rwenzori mountains and its influence on the western part of the East African Rift System in Uganda. The Buganda-Toro belt is composed of several thick-skinned nappes consisting of Archaean Gneisses and Palaeoproterozoic cover units that are thrusted northwards. The high Rwenzori mountains are located in the frontal unit of this belt with retrograde greenschist facies gneisses towards the north, which are unconformably overlain by metasediments and amphibolites. Towards the south the metasediments are overthrust by the next migmatitic gneiss unit that belongs to a crustal scale nappe. The southwards dipping metasedimentary and volcanic sequence in the high Rwenzori mountains shows an inverse metamorphic grade with greenschist facies conditions in the north and amphibolite facies conditions in the south. Early D1 deformation structures are overgrown by cordierite, which in turn grows into D2 deformation, representing the major northwards directed thrusting event. We argue that the inverse metamorphic gradient develops because higher grade rocks are exhumed in the footwall of a crustal scale nappe whereas the exhumation decreases towards the north away from the nappe leading to a decrease in metamorphic grade. The D2 deformation event is followed by a D3 E-W compression, a D4 with the development of steep shear zones with a NNE-SSW and SSE-NNW trend including the large Nyamwamba shear followed by a local D5 retrograde event and D6 brittle inverse faulting. The Paleoproterozoic Buganda-Toro belt is relatively stiff and crosses the NNE-SSW running rift system exactly at the node where the highest peaks of the Rwenzori mountains are situated and where the lake George rift terminates towards the north. Orientation of brittle and ductile fabrics show some similarities indicating that the cross-cutting Buganda-Toro belt influenced rift propagation and brittle fault development within the Rwenzori mountain and that this stiff belt may form part of the reason why the Rwenzori mountains are relatively high within the rift. Keywords: East African Rift, Basement, Buganda Toro, Inverse Metamorphic Gradient, Microtectonics, Rwenzori mountain