In this letter we argue that the event-by-event fluctuations of the ratio of the positively charged and the negatively charged pions provides a signal of quark-gluon plasma. The fact that quarks carry fractional charges is ultimately responsible for this distinct signal.It is of great importance that we have a clear signal of the long-sought quark-gluon plasma (QGP) not only for the experiments at RHIC but also for theoretical reasons. At stake is our fundamental understanding of strong interactions as well as understanding of the state of matter in the very early universe [1]. Proposed signals of this new state of matter abound in literature [2] one of the most studied being the J/ψ suppression [3,4].In this paper, we propose the event-by-event h + /h − fluctuations as a distinct signal of QGP formation. We would also like to stress that this observable is something that can be and already has been calculated on a lattice. The idea is very simple and is reminiscent of the original detection of color in e + e − experiment where one measuresHere Q q is the charge of each flavor and N c is the number of colors. Note that if the fundamental degrees of freedom were hadrons, R e + e − would be very different from this simple counting. We would like to establish that the event-by-event h + /h − fluctuations can similarly determine whether the underlying degrees of freedom are quarks and gluons or hadrons.The point is that in the QGP phase, the unit of charge is 1/3 while in the hadronic phase, the unit of charge is 1. The net charge, of course does not depend on such subtleties. However, the fluctuation in the net charge depends on the squares of the charges and hence strongly depend on which phase it originates from. Measuring the charge fluctuation itself, however, is plagued by systematic uncertainties such as volume fluctuations due to the impact parameter variation. In a previous letter [5], we showed that the multiplicity ratio fluctuation is only sensitive to the density fluctuations and not to the volume fluctuations. The task for us is then to find a suitable ratio whose fluctuation is easy to measure and simply related to the net charge fluctuation.The obvious candidate is the ratio F = Q/N ch whereis the net charge andis the charge multiplicity. Here N ± denote the positive and negative multiplicities. Instead of using F , however, in this paper we propose to use the charge ratio R = N + /N − . The advantages of using R over F are that although trivially related, R is more fundamental to experiments and the signal is about 4 times amplified in R as we show below.To relate R with F , we first rewrite the charge ratio asWhen N ch ≫ Q we can safely say |F | ≪ 1. Expanding in terms of F yieldsDefining δx = x − x for any fluctuating quantity x, it is easy to showwhere · · · denotes the average over all events. Let us now consider δF 2 more closely. In a previous letter [5] (see also [6] and the upcoming paper [7]), we showed that a ratio fluctuation can be expressed asWe then showed that when the average ratio i...

The position, surface area and visual field representation of human visual areas V1, V2 and V3 were measured using fMRI in 7 subjects (14 hemispheres). Cortical visual field maps of the central 12 deg were measured using rotating wedge and expanding ring stimuli. The boundaries between areas were identified using an automated procedure to fit an atlas of the expected visual field map to the data. All position and surface area measurements were made along the boundary between white matter and gray matter. The representation of the central 2 deg of visual field in areas V1, V2, V3 and hV4 spans about 2100 mm2 and is centered on the lateral-ventral aspect of the occipital lobes at Talairach coordinates -29, -78, -11 and 25, -80, -9. The mean area between the 2-deg and 12-deg eccentricities for the primary visual areas was: V1: 1470 mm2; V2: 1115 mm2; and V3: 819 mm2. The sizes of areas V1, V2 and V3 varied by about a factor of 2.5 across individuals; the sizes of V1 and V2 are significantly correlated within individuals, but there is a very low correlation between V1 and V3. These in vivo measurements of normal human retinotopic visual areas can be used as a reference for comparison to unusual cases involving developmental plasticity, recovery from injury, identifying homology with animal models, or analyzing the computational resources available within the visual pathways.

The correlation between baryon number and strangeness elucidates the nature of strongly interacting matter, such as that formed transiently in high-energy nuclear collisions. This diagnostic can be extracted theoretically from lattice QCD calculations and experimentally from event-by-event fluctuations. The analysis of present lattice results above the critical temperature severely limits the presence of qq bound states, thus supporting a picture of independent (quasi)quarks.

We review the present status of the search for a phase transition and critical point as well as anomalous transport phenomena in Quantum Chromodynamics (QCD), with an emphasis on the Beam Energy Scan program at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. We present the conceptual framework and discuss the observables deemed most sensitive to a phase transition, QCD critical point, and anomalous transport, focusing on fluctuation and correlation measurements. Selected experimental results for these observables together with those characterizing the global properties of the systems created in heavy ion collisions are presented. We then discuss what can be already learned from the currently available data about the QCD critical point and anomalous transport as well as what additional measurements and theoretical developments are needed in order to discover these phenomena.

a b s t r a c tWe review the progress achieved in extracting the properties of hot and dense matter from relativistic heavy ion collisions at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory and the large hadron collider (LHC) at CERN. We focus on bulk properties of the medium, in particular the evidence for thermalization, aspects of the equation of state, transport properties, as well as fluctuations and correlations. We also discuss the in-medium properties of hadrons with light and heavy quarks, and measurements of dileptons and quarkonia. This review is dedicated to the memory of Gerald E. Brown.