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 role of proximity in foreclosure externalities: Evidence from condominiums

We explore several different explanations of the effect of foreclosures on neighboring properties using a dataset of transactions in Boston, for which we have rich data on the size and location of condominium associations. There is compelling evidence against a supply effect-nearby condo foreclosures in different associations, and even those within the same association but at different physical addresses, have little impact on condo sale prices. However, condos transact at average discounts of 2.4 percent when a foreclosure shares the same physical address. We view the results as indicating that investment externalities drive foreclosures' impacts on neighboring house prices

Toward a Jurisprudence of Psychiatric Evidence: Examining the Challenges of Reasoning from Group Data in Psychiatry to Individual Decisions in the Law

Psychiatry is an applied science. It thus shares a characteristic of all applied science in that it is ultimately applied at two levels—general and specific. Scientific research inevitably focuses on aggregate data and seeks to generalize findings across persons, places, or things. However, in the courtroom, as is true in other applied settings, the focus is usually on an individual case. Thus, psychiatry presents the challenge inherent in all scientific evidence of reasoning from group data to an individual case, which is termed the “G2i problem.” Psychiatry, unlike many scientific fields that come to court, also confronts the G2i problem in its daily practice since mental health professionals routinely diagnose and treat individuals based on aggregate data. Yet approaches to the G2i problem in clinical psychiatry do not necessarily comport with the ways in which aggregate data is applied to an individual case in the courtroom. In this Article, we employ the G2i lens to examine the admissibility of psychiatric expert testimony in regards to both general research findings, or “framework evidence,” and application of those general findings to specific cases, or “diagnostic evidence.” Although the rules of evidence that apply to “G” and to “i” are the same, the scientific and professional considerations with which each must be evaluated are fundamentally different. G2i inferences provide a useful lens by which the interactions of psychiatry and law can be better understood and managed

Weyl group multiple Dirichlet series constructed from quadratic characters

We construct multiple Dirichlet series in several complex variables whose coefficients involve quadratic residue symbols. The series are shown to have an analytic continuation and satisfy a certain group of functional equations. These are the first examples of an infinite collection of unstable Weyl group multiple Dirichlet series in greater than two variables.Comment: incorporated referee's comment

Asymptotic Expansions for lambda_d of the Dimer and Monomer-Dimer Problems

In the past few years we have derived asymptotic expansions for lambda_d of the dimer problem and lambda_d(p) of the monomer-dimer problem. The many expansions so far computed are collected herein. We shine a light on results in two dimensions inspired by the work of M. E. Fisher. Much of the work reported here was joint with Shmuel Friedland.Comment: 4 page

Anisotropic Hall Effect in Single Crystal Heavy Fermion YbAgGe

Temperature- and field-dependent Hall effect measurements are reported for YbAgGe, a heavy fermion compound exhibiting a field-induced quantum phase transition, and for two other closely related members of the RAgGe series: a non-magnetic analogue, LuAgGe and a representative, ''good local moment'', magnetic material, TmAgGe. Whereas the temperature dependent Hall coefficient of YbAgGe shows behavior similar to what has been observed in a number of heavy fermion compounds, the low temperature, field-dependent measurements reveal well defined, sudden changes with applied field; in specific for $H \perp c$ a clear local maximum that sharpens as temperature is reduced below 2 K and that approaches a value of 45 kOe - a value that has been proposed as the $T = 0$ quantum critical point. Similar behavior was observed for $H \| c$ where a clear minimum in the field-dependent Hall resistivity was observed at low temperatures. Although at our base temperatures it is difficult to distinguish between the field-dependent behavior predicted for (i) diffraction off a critical spin density wave or (ii) breakdown in the composite nature of the heavy electron, for both field directions there is a distinct temperature dependence of a feature that can clearly be associated with a field-induced quantum critical point at $T = 0$ persisting up to at least 2 K.Comment: revised versio

Image quality measures and their performance

A number of quality measures are evaluated for gray scale image compression. They are all bivariate exploiting the differences between corresponding pixels in the original and degraded images. It is shown that although some numerical measures correlate well with the observers' response for a given compression technique, they are not reliable for an evaluation across different techniques. The two graphical measures (histograms and Hosaka plots), however, can be used to appropriately specify not only the amount, but also the type of degradation in reconstructed images

Expansion of epidemic dengue viral infections to Pakistan

Objectives: Antibodies to dengue viruses have occasionally been reported in individuals in Pakistan, but the frequency of occurrence of dengue infection in Pakistan is unclear. The first confirmed dengue hemorrhagic fever outbreak in Pakistan occurred in 1994. In October 1995, the authors investigated an outbreak of a febrile illness among employees of a construction contractor at a power generation plant in Baluchistan, Pakistan, to determine the cause of illness and recommend appropriate preventive measures.Methods: The work site and living arrangements were inspected, a questionnaire was administered, and serum samples were collected from all consenting contractor employees and their families if they lived at the camp. Sera were analyzed for IgM against dengue virus, using an enzyme-linked immunosorbent assay.Results: Interviews were conducted with 76 persons (mean age, 42y); 95% were men. Forty-two persons (55%) reported having experienced fever, headache, or myalgia in the preceding 6 weeks. Fifty-seven subjects (75%) had IgM antibodies against at least one dengue serotype; 45 subjects (59%) had IgM antibodies against dengue serotype 2.CONCLUSION: This was an outbreak of dengue fever due to multiple serotypes of dengue virus. This confirms that epidemic dengue infection was present in southern Pakistan for 2 consecutive years