The associative algebras of conformal field theory

Modulo the ideal generated by the derivative fields, the normal ordered product of holomorphic fields in two-dimensional conformal field theory yields a commutative and associative algebra. The zero mode algebra can be regarded as a deformation of the latter. Alternatively, it can be described as an associative quotient of the algebra given by a modified normal ordered product. We clarify the relation of these structures to Zhu's product and Zhu's algebra of the mathematical literature.Comment: LaTeX (BibTeX), 6 pages, no figure

Warranted Diagnosis

A diagnostic process is an investigative process that takes a clinical picture as input and outputs a diagnosis. We propose a method for distinguishing diagnoses that are warranted from those that are not, based on the cognitive processes of which they are the outputs. Processes designed and vetted to reliably produce correct diagnoses will output what we shall call ‘warranted diagnoses’. The latter are diagnoses that should be trusted even if they later turn out to have been wrong. Our work is based on the recently developed Cognitive Process Ontology and further develops the Ontology of General Medical Science. It also has applications in fields such as intelligence, forensics, and predictive maintenance, all of which rely on vetted processes designed to secure the reliability of their outputs

Municipal Infrastructure Delivery in Ethiopia: A bottomless pit or an option to reach the Millennium Development Goals?

The following paper examines the different options to finance local public infrastructure in Ethiopia based on the assumption that the federal government of Ethiopia will not provide any guarantees for local borrowing. Besides a detailed description of the local public finance system and the capital market in Ethiopia, the paper also sets out some international successful practices in municipal infrastructure financing. Based on the observation of the Ethiopian case and the consideration of the international experiences, the paper has two major pillars that very specifically identify actions required for implementation. On the one hand, the paper recommends a number of feasible arrangements to generate a revenue enhancement of the local authorities in the existing intergovernmental framework. On the other hand, the paper suggests a solution - for creditworthy as well as for potentially creditworthy urban local governments (ULG) - to finance their future demand of public infrastructure together with the national finance institutions as well as the international donors.Fiscal Federalism, Grants, Ethiopia, Urban and Rural Economies

Inference without randomization or ignorability: A stability­ controlled quasi-experiment on the prevention of tuberculosis

When determining the effectiveness of a new treatment, randomized trials are not always possible or desirable. The stability-controlled quasi-experiment (SCQE) (Hazlett, 2019) is an observational approach that replaces the usual “no-unobserved confounding” assumption with one on the change in non-treatment outcome between successive cohorts, or the “baseline trend.” We extend this method to allow variance estimation and inference, and apply it for the first time by examining whether isoniazid preventive therapy (IPT) reduced tuberculosis (TB) incidence among 26,715 HIV patients in Tanzania. After IPT became available in the clinics we studied, a non-random 25% of patients received it. Within a year, fewer than 1% of patients on IPT developed TB, compared to 16% of the untreated. Regression adjustment using available covari-ates produces an equally large and highly significant estimate of -15 percentage point (pp) [95%CI: -16.6, -13.7]. While those estimates may generate confidence in IPT’s effectiveness, they cannot eliminate confounding. By contrast, SCQE reveals that the average treatment effect on the treated must be small and indistinguishable from zero, if we assume the baseline trend was flat over the study period. Rather, to argue that IPT was beneficial requires claiming that the (non-treatment) incidence rate rose by at least 0.5 pp per year. This is plausible, but far from certain. The SCQE approach has broad applicability and will sometimes lead to definitive claims of effectiveness. In this case, it usefully aids in protecting against over-confidence in claims that IPT was effective

The Comparison of the Swift Gamma-Ray Bursts With and Without Measured Redshifts

Gamma-ray bursts, detected by the Swift satellite, are separated into two samples: the bursts with and without determined redshifts. These two samples are compared by the standard Student t-test and F-test. We have compared the dispersions and the mean values of the durations, peak fluxes and fluences in order to find any differences among these two samples. No essential differences were found.Comment: Published in the Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, 200