We consider bounds on light quark masses that follow from positivity of the pseudoscalar correlator spectral function plus the assumption that perturbative QCD is valid for the correlator and its derivatives up to order N for momenta t ≥ t̂. We find that the bounds vary a lot depending on the assumed value of t̂ and even, if it is too small (t̂ ≃ 1.5, 1.6, 2.1 GeV for respectively N = 0, 1, 2), th...

The Time Of Arrival (TOA) of a received signal is the most important parameter for position estimation. The accuracy of the estimated TOA is limited by multipath errors. Consequently, multipath mitigation techniques are essential for high accuracy positioning using TOA observations. Narrow Correlator and double delta correlator were introduced to reduce multipath errors in pseudoranges. These c...

Current intrusion detection systems (IDSs) usually focus on detecting low-level attacks and/or anomalies; none of them can capture the logical steps or attack strategies behind these attacks. Consequently, the IDSs usually generate a large amount of alerts. In situations where there are intensive intrusive actions, not only will actual alerts be mixed with false alerts, but the amount of alerts...

The QCD sum rule for the correlator of topological charge densities χ(Q2) and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant fη′ of η -meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the ...

Direct detection optical code-division multipleaccess (CDMA) communication systems involving overlapping pulse-position modulation (OPPM) is considered. Double optical hardlimiters placed before and after the correlator at the receiver side is proposed for this system. The performance (in terms of the bit error probability) of this system is evaluated taking into account the effect of both the ...

The QCD sum rule for the correlator of topological charge densities χ(Q2) and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant fη′ of η -meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the ...

While the Reichardt correlator and its mathematical equivalents do not signal true image velocity, a great deal of experimental evidence establishes them as mechanisms for visual motion detection in insects, humans, and other animals. This study examines the accuracy with which Reichardt correlators can provide velocity estimates in an organism’s natural visual environment. I develop an analyti...