A survey of quality measures for gray-scale image compression

Although a variety of techniques are available today for gray-scale image compression, a complete evaluation of these techniques cannot be made as there is no single reliable objective criterion for measuring the error in compressed images. The traditional subjective criteria are burdensome, and usually inaccurate or inconsistent. On the other hand, being the most common objective criterion, the mean square error (MSE) does not have a good correlation with the viewer's response. It is now understood that in order to have a reliable quality measure, a representative model of the complex human visual system is required. In this paper, we survey and give a classification of the criteria for the evaluation of monochrome image quality

The Bank's balance sheet during the crisis

This article sets out how monetary policy implementation and liquidity provision during the financial crisis have affected the size and composition of the Bank of England’s balance sheet. It extends and updates a recent speech by Paul Fisher, Executive Director Markets, and describes the main components of the Bank’s balance sheet prior to and during the crisis.

Dynamical Disentanglement across a Point Contact in a Non-Abelian Quantum Hall State

We analyze tunneling of non-Abelian quasiparticles between the edges of a quantum Hall droplet at Landau level filling fraction nu=5/2, assuming that the electrons in the first excited Landau level organize themselves in the non-Abelian Moore-Read Pfaffian state. We formulate a bosonized theory of the modes at the two edges of a Hall bar; an effective spin-1/2 degree of freedom emerges in the description of a point contact. We show how the crossover from the high-temperature regime of weak quasiparticle tunneling between the edges of the droplet, with 4-terminal R_{xx} scaling as T^{-3/2}, to the low-temperature limit, with R_{xx} - h/(10 e^2) scaling as -T^4, is closely related to the two-channel Kondo effect. We give a physical interpretation for the entropy of \ln(2\sqrt{2}) which is lost in the flow from the ultraviolet to the infrared.Comment: 4 pages, 1 figur

Grease to the wheel or a spanner in the works? An investigation of office and industrial occupier displacement and property market filtering in Tyne & Wear using the chaining technique

The research uses a chaining technique to study the scale and impact of the displacement of office and industrial occupiers in the Tyne and Wear conurbation. The status and origin of occupiers of 20 office and industrial developments, promoted or assisted by the public sector, have been recorded to determine the distance that they have moved and the number of net new jobs generated. Property chaining reveals the extent to which the filtering effect has resulted in reoccupation of buildings and permits the quantification of the amount of property remaining vacant and its location. Analysis of the recorded chains has revealed that more than half of all occupiers on assisted schemes have relocated within the Tyne and Wear area and one in three occupier chains generated by such relocations result in vacant property elsewhere within the metropolitan area. The displacement of employment and economic activity within the conurbation can be mapped and could be used to inform the action of public agencies to reduce or ameliorate the negative side-effects of their intervention. The chaining technique proves an elegantly simple and robust technique by which to determine the scale and distribution of occupier displacement in property markets

Additives to Control Mechanical Properties and Drug Delivery of Injectable Polymeric Scaffolds

In situ forming implants (ISIs) are popular due to their ease of use and local drug delivery potential, but they suffer from high initial drug burst, and release behavior is tied closely to solvent exchange and polymer properties. Additionally, such systems are traditionally viewed purely as drug delivery devices rather than potential scaffold materials due to their poor mechanical properties and minimal porosity. The aim of this research was to develop an injectable ISI with drug release, mechanical, and microstructural properties controlled by micro- and nanoparticle additives. First, an injectable ISI was developed with appropriate drug release kinetics for orthopedic applications. Poly(β-amino ester) (PBAE) microparticles were loaded with simvastatin or clodronate, and their loading efficiency and drug retention after washing was quantified. Drug-loaded PBAE microparticles and hydroxyapatite (HA) microparticles were added to a poly(lactic-co-glycolic acid) (PLGA)–based ISI. By loading simvastatin into PBAE microparticles, release was extended from 10 days to 30 days, and burst was reduced from 81% to 39%. Clodronate burst was reduced after addition of HA, but was unaffected by PBAE loading. Scaffold mass and porosity fluctuated as the scaffolds swelled and then degraded over 40 days. Next, the mechanical properties of these composite ISIs were quantified. Both micro- and nanoparticulate HA as well as PBAE microparticle content were varied. Increasing HA content generally improved compressive strength and modulus, with a plateau occurring at 30% nano-HA. Injectability remained clinically acceptable for up to 10% w/w PBAE microparticles. Ex vivo injections into trabecular bone improved both strength and modulus. Lastly, HA-free ISIs were investigated for drug delivery into the gingiva to treat periodontitis. Doxycycline and simvastatin were co-delivered, with delivery of doxycycline over 1 week accompanied by simvastatin release over 30 days. PBAE-containing ISIs exhibited higher initial and progressive porosity and accessible volume than PBAE-free ISIs over the course of degradation. Additionally, PBAE-containing ISIs provided superior tissue retention within a simulated periodontal pocket. The ISIs investigated here have a wide range of potential applications due to their flexible material and drug release properties, which can be controlled by both the chemistry and concentration of various particulate additives