In this detailed study we have reported on single-crystal and polycrystalline phases of V 1+x S 2 ; 0.10 < x < 0.25, prepared using excess sulfur in a sealed quartz tube and investigated their structural, transport and magnetic properties. The crystal flakes have trigonal symmetry with 2c and incommensurate >2( √ 3)a superlattice ordering in the a-b plane. As-grown flakes showed complex irreversible behaviour in resistivity on cycling to low temperatures, related to the metastability of the structure. The annealing of the crystal flakes and addition of 5-10% Al stabilizes the superstructure. We observe an anomalous contribution to the resistance of these crystal flakes with a maximum around 100-150 K. The contribution is more pronounced for betterordered phases. The magnetic susceptibility and thermopower values of these compounds are large and vary smoothly on cooling around this temperature interval. The polycrystalline phase, obtained at a higher temperature, on the other hand, showed absence of superlattice distortions and gave a smooth behaviour in its resistance, but with a large T 2 -contribution. The structural and electronic properties of different phases are discussed in terms of disorder among the interstitial V atoms and the effect of in-plane vacancies on the chargedensity-wave instability in these and similar compounds.

The proposal that a strong-coupling limit of the five-dimensional type II string theory (M-theory compactified on a 6-torus) in which the Planck length becomes infinite could give a six-dimensional superconformal phase of M-theory is reviewed. This limit exists for the free theory, giving a six-dimensional theory with (4, 0) supersymmetry compactified on a circle whose radius gives the five-dimensional Planck length. The free six-dimensional theory has a fourth rank tensor gauge field with the symmetries of the Riemann tensor instead of a symmetric tensor gauge field, but its dimensional reduction gives conventional linearized gravity in five dimensions. The possibility of an interacting form of this theory existing and the consequences it would have for the geometric picture of gravity are discussed.Gravitational theories are characterized by a length scale l which determines the strength of gravitational coupling and also the scale at which quantum gravity effects are expected to become important; in M-theory this is the D = 11 Planck length. In recent years there has been great success in describing the strong-coupling behaviour of a variety of gauge and string theories in terms of dual theories. Here, a recent proposal [1] (reviewed in [2]) to extend this to gravitational theories will be described. The idea is to consider a suitable limit in which l → ∞ so that masses become zero and a phase of the theory with a vast amount of unbroken gauge symmetry is obtained. The specific model is M-theory compactified on T 6 to D = 5, with a low-energy effective description in terms of D = 5, N = 8 supergravity. The proposal is that the limit l → ∞ is a kind of decompactification limit to a six-dimensional theory. This theory is conformally invariant, with no length scales, and the scale l arises as the compactification scale: compactification from D = 6 on a circle of radius R gives a theory with D = 5 Planck scale l = R. If such a superconformal phase of M-theory exists, then it 0264-

Building Systems Division of Yamatake-Honeywell CO., has developed a new TY4700 Comfort Sensor t h a t revolutionizes indoor comfort control.Thermal comfort depends on many factorsthe new sensor's output temperature signal is a combination of a i r temperature, radiant temperature and air velocity. T h e comfort sensor consists of a sensor unit and a processor unit. T h e sensor unit has a compact, light but accurate compound sensing element which detects air temperature, radiant temperature and air velocity. The processor unit uses the input data to provide an o u t p u t signal r e p r e s e n t i n g t h e r o o m ' s t h e r m a l comfortldiscomfort factor. Building automation (BA) systems can combine this output with humidity data a n d s t o r e d knowledge of tenant's clothing a n d physical activity to calculate the I S 0 7 7 3 0 standard Predicted Mean Vote (PiMV) thermal comfort index, which ensures maximum comfort for tenants a n d minimum energy expenditure for building operators.