A theory for tunneling between a real surface and a model probe tip, applicable to the "scanning tunneling microscope" is presented. The tunneling current is found to be proportional to the local density of states of the surface, at the position of the tip. It can be shown that the tunneling conductance has exponential dependence on the distance of the nearest approach to the surface

UNLABELLED Vacuum cleaners with a central exhaust may lead to lower airborne dust and allergen concentrations compared with regular vacuum cleaners. In 12 houses, equipped with a central vacuum cleaning system, a standardized vacuum cleaning protocol was performed comparing airborne dust and allergen concentrations between the central system and a regular cleaner. Airborne dust concentrations d...

We analyse symmetry breaking in general gauge theories paying particular attention to the underlying geometry of the theory. In this context we find two natural metrics upon the vacuum manifold: a Euclidean metric associated with the scalar sector, and another generally inequivalent metric associated with the gauge sector. Physically, the interplay between these metrics gives rise to many of th...

The Higgs vacuum – with its constant background field – is not ‘empty’ but is a kind of medium. Any ordinary medium, viewed at sufficiently long length scales, has a hydrodynamic description and can propagate sound waves. The vacuum medium is unusual; the speed of sound is formally infinite and there is no linear sound-wave regime. Instead, long-wavelength disturbances are described by some int...

What can the quantum liquid say on the brane black hole, the entropy of extremal black hole and the vacuum energy? Using quantum liquids one can simulate the behavior of the quantum vacuum in the presence of the event horizon. The condensed matter analogs demonstrate that in most cases the quantum vacuum resists to formation of the horizon, and even if the horizon is formed different types of t...

There appears to be three, perhaps related, ways of approaching the nature of vacuum energy. The first is to say that it is just the lowest energy state of a given, usually quantum, system. The second is to equate vacuum energy with the Casimir energy. The third is to note that an energy difference from a complete vacuum might have some long range effect, typically this energy difference is int...

due to a nearby vacuum cleaner or a passing tramear. You will find that these devices will not help you when you are confronted with disease far from the resources of a modern hospital. The only thing that matters is whether or not you have taken heed to the lesson first taught in the Eastern Mediterranean over two thousand years ago, repeated again by the old Cromwellian captain-"the trooper t...

Abstract Image analysis is used to study the effect of sintering atmosphere and sintering times on the pores morphology of Astaloy CrM. The pores morphology was described by means of some parameters, Circular Diameter (DC)- which shows the diameter of equivalent circle for comparing the pore size, FElongation and FShape- which have different geometrical meanings. The results have been interpret...