Ongoing measurements of the dark current in the WFPC2 detectors indicate that the average level of dark current has been slowly increasing over the instrument's lifetime. We have analyzed more recent dark current data, now covering the period from September 1994 to January 2001. This analysis shows that after late-1998, the dark current is increasing more slowly than expected and could possibly...

We present an algorithm for finding all time-reversible systems within a given family of 2-dim systems of ODE’s whose right-hand sides are polynomials. We also study an interconnection of time-reversibility and invariants of a subgroup of SL(2,C).

Although time is recognized as an important factor relating dialogical selves, space is the primary metaphor used when discussing alternative I-positions in dialogical relations (e.g. Hermans 2001, 2002; Hermans and Kempen 1993; Raggatt 2000). However, more recently, there has been a growing theoretical interest in the temporal dimension of dialogicality (e.g. Bertau and Gonçalves 2007; Bhatia ...

The question of whether the P and NP complexity classes are equivalent is unresolved. It is conjectured that they are inequivalent because of the vast number of NP-Complete languages (including the ever-popular 3-SAT) for which there is no known polynomial time solution. The author of this paper respectfully disagrees and presents a polynomial time solution to a problem closely related to 3-SAT...

We focus on synthesis techniques for transforming existing fault-intolerant real-time programs into fault-tolerant programs that provide phased recovery. A faulttolerant program is one that satisfies its safety and liveness specifications as well as timing constraints in the presence of faults. We argue that in many commonly considered programs (especially in mission-critical systems), when fau...

We consider maximal globally hyperbolic flat (2+1) spacetimes with compact space S of genus g > 1. For any spacetime M of this type, the length of time that the events have been in existence is M defines a global time, called the cosmological time CT of M , which reveals deep intrinsic properties of spacetime. In particular, the past/future asymptotic states of the cosmological time recover and...

The Hiperlan/2 standard [1]-[3] for wireless LAN transmission in the 5 GHz frequency band makes use of OFDM modulation with a TDMA access scheme, in order to efficiently exploit time dispersive channels with frequency selective fading. It is well known that the performance of OFDM schemes is very sensitive to synchronization: symbol timing and carrier frequency errors must be carefully estimate...

An electron neutrino can have the quantum phase of an electron, i.e. share its internal clock, if the neutrino takes a path in space-time that is not in the direction of its energy-momentum. Each flavor neutrino would then have a different internal clock; a muon neutrino would have a muon clock and a tau neutrino would have a tau clock. Perhaps surprisingly, there is some evidence suggesting ne...

In valid-time indeterminacy, it is known that an event stored in a temporal database did in fact occur, but it is not known exactly when the event occurred. We present an extension of the tuple-timestamped temporal data model, called the the possible chronons data model, to support valid-time indeterminacy In the possible chronons data model, each event is represented with a set of possible chr...