Achieving satisfactory contractual terms for the engineer's role

An international survey of clients, consultants and contractors produced wide-ranging data on the views of users of the FIDIC form of contract. The purpose of the survey was to elicit views on a range of issues, prior to revising the model form, to ensure that the contract drafters produce a form that is satisfactory for its users. Those questions that focus upon the role of the engineer have been subjected to detailed statistical analysis. The analysis shows that, contrary to popular belief, the views of contract users from common law jurisdictions do not differ from those in civil code jurisdictions. The engineer’s role is not generally perceived as neutral in the contractual relationships between clients and contractors. Contractors would prefer someone other than the engineer to be the first-line settler of disputes in contracts

Differential effects of anti-CD20 therapy on CD4 and CD8 T cells and implication of CD20-expressing CD8 T cells in MS disease activity

A small proportion of multiple sclerosis (MS) patients develop new disease activity soon after starting anti-CD20 therapy. This activity does not recur with further dosing, possibly reflecting deeper depletion of CD20-expressing cells with repeat infusions. We assessed cellular immune profiles and their association with transient disease activity following anti-CD20 initiation as a window into relapsing disease biology. Peripheral blood mononuclear cells from independent discovery and validation cohorts of MS patients initiating ocrelizumab were assessed for phenotypic and functional profiles using multiparametric flow cytometry. Pretreatment CD20-expressing T cells, especially CD2

Surface MIMO: Using Conductive Surfaces For MIMO Between Small Devices

As connected devices continue to decrease in size, we explore the idea of leveraging everyday surfaces such as tabletops and walls to augment the wireless capabilities of devices. Specifically, we introduce Surface MIMO, a technique that enables MIMO communication between small devices via surfaces coated with conductive paint or covered with conductive cloth. These surfaces act as an additional spatial path that enables MIMO capabilities without increasing the physical size of the devices themselves. We provide an extensive characterization of these surfaces that reveal their effect on the propagation of EM waves. Our evaluation shows that we can enable additional spatial streams using the conductive surface and achieve average throughput gains of 2.6-3x for small devices. Finally, we also leverage the wideband characteristics of these conductive surfaces to demonstrate the first Gbps surface communication system that can directly transfer bits through the surface at up to 1.3 Gbps.Comment: MobiCom '1

Irreducible characters of GSp(4, q) and dimensions of spaces of fixed vectors

In this paper, we compute the conjugacy classes and the list of irreducible characters of GSp(4,q), where q is odd. We also determine precisely which irreducible characters are non-cuspidal and which are generic. These characters are then used to compute dimensions of certain subspaces of fixed vectors of smooth admissible non-supercuspidal representations of GSp(4,F), where F is a non-archimedean local field of characteristic zero with residue field of order q.Comment: 48 pages, 21 tables. Corrected an error in Table 16 for type V* representations (theta_11 and theta_12 were switched

Recent X-ray measurements of the accretion-powered pulsar 4U 1907+09

X-ray observations of the accreting X-ray pulsar 4U~1907+09, obtained during February 1996 with the Proportional Counter Array on the Rossi X-ray Timing Experiment (RXTE), have enabled the first measurement of the intrinsic pulse period Ppulse since 1984: Ppulse=440.341[+0.012,-0.017] s. 4U 1907+09 is in a binary system with a blue supergiant. The orbital parameters were solved and this enabled the correction for orbital delay effects of a measurement of Ppulse obtained in 1990 with Ginga. Thus, three spin down rates could be extracted from four pulse periods obtained in 1983, 1984, 1990, and 1996. These are within 8% equal to a value of dPpulse/dt=+0.225 s/yr. This suggest that the pulsar is perhaps in a monotonous spin down mode since its discovery in 1983. Furthermore, the RXTE observations show transient ~18 s oscillations during a flare that lasted about 1 hour. The oscillations may be interpreted as Keplerian motion of an accretion disk near the magnetospheric radius. This, and the notion that the co-rotation radius is much larger than any conceivable value for the magnetospheric radius (because of the long spin period), renders it unlikely that this pulsar spins near equilibrium like is suspected for other slowing accreting X-ray pulsars. We suggest as an alternative that perhaps the frequent occurrence of a retrograde transient accretion disk may be consistently slowing the pulsar down. Further observations of flares can provide more evidence of this.Comment: 26 pages, 11 figures, to be published in Astrophysical Journal part I on March 20, 199

Sonic-Point Model of Kilohertz Quasi-Periodic Brightness Oscillations in Low-Mass X-ray Binaries

Strong, coherent, quasi-periodic brightness oscillations (QPOs) with frequencies ranging from about 300 Hz to 1200 Hz have been discovered with the Rossi X-ray Timing Explorer in the X-ray emission from some fifteen neutron stars in low-mass binary systems. Two simultaneous kilohertz QPOs differing in frequency by 250 to 350 Hertz have been detected in twelve of the fifteen sources. Here we propose a model for these QPOs. In this model the X-ray source is a neutron star with a surface magnetic field of 10^7 to 10^10 G and a spin frequency of a few hundred Hertz, accreting gas via a Keplerian disk. The frequency of the higher-frequency QPO in a kilohertz QPO pair is the Keplerian frequency at a radius near the sonic point at the inner edge of the Keplerian flow whereas the frequency of the lower-frequency QPO is approximately the difference between the Keplerian frequency at a radius near the sonic point and the stellar spin frequency. This model explains naturally many properties of the kilohertz QPOs, including their frequencies, amplitudes, and coherence. We show that if the frequency of the higher-frequency QPO in a pair is an orbital frequency, as in the sonic-point model, the frequencies of these QPOs place interesting upper bounds on the masses and radii of the neutron stars in the kilohertz QPO sources and provide new constraints on the equation of state of matter at high densities. Further observations of these QPOs may provide compelling evidence for the existence of a marginally stable orbit, confirming a key prediction of general relativity in the strong-field regime.Comment: 67 pages, including 15 figures and 5 tables; uses aas2pp4; final version to appear in the Astrophysical Journal on 1 December 199

Sidebands Due to Quasi-periodic Oscillations in 4U 1626-67

The low-mass X-ray binary pulsar 4U 1626-67 shows 0.048 Hz quasi-periodic oscillations (QPOs) and red noise variability as well as coherent pulsations at the 0.130 Hz neutron star spin frequency. Power density spectra of observations made with the Rossi X-ray Timing Explorer show significant sidebands separated from the pulsar spin frequency (and its harmonics) by the QPO frequency. These show that the instantaneous amplitude of the coherent pulsations is modulated by the amplitude of the QPOs. This phenomenon is expected in models such as the magnetospheric beat frequency model where the QPOs originate near the polar caps of the neutron star. In the 4--8 keV energy range, however, the lower-frequency sidebands are significantly stronger than their higher-frequency complements; this is inconsistent with the magnetospheric beat frequency model. We suggest that the 0.048 Hz QPOs are instead produced by a structure orbiting the neutron star at the QPO frequency. This structure crosses the line of sight once per orbit and attenuates the pulsar beam, producing the symmetric (amplitude modulation) sidebands. It also reprocesses the pulsar beam at the beat frequencies between the neutron star spin frequency and the QPOs, producing the excess variability observed in the lower-frequency sidebands. Quite independently, we find no evidence that the red noise variability modulates the amplitude of the coherent pulsations. This is also in contrast to the expectations of the magnetospheric beat frequency model and differs from the behavior in some high-mass X-ray binary pulsars.Comment: 8 pages, 3 figures, AAS macros v4.0. To appear in ApJ Letter