Functional Analytic Continuation Techniques with Applications in Field Theory

Often one has data at points inside the holomorphy domain of a Green’s function, or of an Amplitude or Form—Factor, and wants to obtain information about the spectral function i.e. the discontinuity along the cuts. Data may be experimental or theoretical. In QCD for example the perturbation expansion is valid only for unphysicaL values of the energy: one would like to continue this information to the cuts to find the resonance parameters. However, analytic continuation off open contours is extremely unstable. Also, the straightforward continuation of the truncated perturbation expansion will not do, since this is itself analytic and continuation will thus yield exactly the same result. This problem is solved by functional techniques, first by allowing small imprecisions in the data to remove the uniqueness of the continuation, and then by introducing a stabilizing condition suited to the particular physical problem, which will suppress the functions with incorrect behaviour. The stabilizing condition is expressed in terms of a norm giving a measure of the smoothness of the Discrepancy Function -which is the Amplitude with the resonances removed. The minimal norm computed from the data depends on the trial values of the resonance parameters and enables one to select the best values for these. The corresponding optimal amplitude is also constructed. An explicit solution is obtained for the case of a discrete data set; in the continuous case the problem is expressed in terms of a Fredholm integral equation

Liver transplantation for viral hepatitis - which patients will benefit?

Liver transplantation constitutes a significant part of the hepatologist's armamentarium and has become the treatment of choice for most patients with chronic end-stage liver disease. The results continue to improve and many centres are now able to achieve 1-year survival figures in excess of 90% in selected patients. The surgical techiques involved in liver transplantation and the immunosuppressive protocols used postoperatively have been standardised. In contrast, the indications for and contraindications to liver transplantation continue to be modified. Large numbers of patients have undergone liver transplantation in recent years and analyses of large series of patients have made it possible to determine more accurately the outcome of liver transplantation in specific hepatic disease processes. As a result, subsets of patients who are more likely to survive long term have been identified. This is particularly true of patients with viral hepatitis

Performance Evaluation and Optimization of Math-Similarity Search

Similarity search in math is to find mathematical expressions that are similar to a user's query. We conceptualized the similarity factors between mathematical expressions, and proposed an approach to math similarity search (MSS) by defining metrics based on those similarity factors [11]. Our preliminary implementation indicated the advantage of MSS compared to non-similarity based search. In order to more effectively and efficiently search similar math expressions, MSS is further optimized. This paper focuses on performance evaluation and optimization of MSS. Our results show that the proposed optimization process significantly improved the performance of MSS with respect to both relevance ranking and recall.Comment: 15 pages, 8 figure

The determination of integral closures and geometric applications

We express explicitly the integral closures of some ring extensions; this is done for all Bring-Jerrard extensions of any degree as well as for all general extensions of degree < 6; so far such an explicit expression is known only for degree < 4 extensions. As a geometric application we present explicitly the structure sheaf of every Bring-Jerrard covering space in terms of coefficients of the equation defining the covering; in particular, we show that a degree-3 morphism f : Y --> X is quasi-etale if and only if the first Chern class of the sheaf f_*(O_Y) is trivial (details in Theorem 5.3). We also try to get a geometric Galoisness criterion for an arbitrary degree-n finite morphism; this is successfully done when n = 3 and less satifactorily done when n = 5.Comment: Advances in Mathematics, to appear (no changes, just add this info

A natural history of efavirenz drug-induced liver injury

Background. Efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor, has been a component of first-line antiretroviral therapy (ART) in the South African HIV/AIDS programme since 2004. It is extensively used in ART programmes in other low- and middle-income countries. The natural history of the previously recognised EFV drug-induced liver injury (DILI) is not known.Objectives. To define and establish a causality assessment for EFV DILI and document its natural history by detailing a patient cohort. All relevant features characterising the patterns of clinical and histological injury, the duration of clinical and biochemical recovery and the associated mortality rate were documented. Factors associated with specific histological patterns of liver injury were analysed.Methods. Patients were prospectively included after meeting causality and inclusion criteria for EFV DILI. Clinical, demographic and liver histological features (where possible) were documented from the time of presentation and throughout follow-up. Prednisone at 0.25 - 0.5 mg/kg was initiated at the discretion of the treating hepatologist.Results. Fifty patients were prospectively included in the analysis. The median age was 34 (interquartile range (IQR) 29 - 39) years, males being older than females (p=0.014). Most (92%) were female, and 86% were of black African ethnicity. The median duration of ART at presentation was 6 months, with half of the women having initiated ART during pregnancy, at a median gestation of 24 (IQR 11 - 36) weeks. The median CD4 nadir at ART treatment initiation was 517 cells/µL, with no significant difference in CD4 nadir between those who were pregnant and those who were not (p=0.6). The median RUCAM (Roussel Uclaf Causality Assessment Method) score was 7, and among the 75% of patients who had liver biopsies, three histological patterns were identified: submassive necrosis (60%), nonspecific hepatitis (35%), and mixed cholestatic hepatitis (5%). On multivariate analysis, predictors for the development of submassive necrosis included younger age (&lt;30 years; p=0.045), ART initiation in pregnancy (p=0.02), and a baseline CD4 count &gt;350 cells/µL (p=0.018). For the nonspecific hepatitis group, pregnancy was also an associated factor (p=0.04). The mortality rate was 14%, with a median time from admission to death of 15 days. The median (IQR) time to initial hospital discharge was a lengthy 33 (24 - 52) days. Biochemical recovery was prolonged, necessitating a follow-up period of more than a year at an outpatient specialist clinic, with 86% of patients initiating a protease inhibitor-based ART regimen successfully.Conclusions. EFV DILI is a severe drug complication of ART with appreciable mortality and significant inpatient morbidity, requiring prolonged hospitalisation and follow-up

Syntactic ambiguity resolution in dyslexia: An examination of cognitive factors underlying eye movement differences and comprehension failures

This study examined eye movements and comprehension of temporary syntactic ambiguities in individuals with dyslexia, as few studies have focused on sentence-level comprehension in dyslexia. We tested 50 participants with dyslexia and 50 typically-developing controls, in order to investigate (1) whether dyslexics have difficulty revising temporary syntactic misinterpretations and (2) underlying cognitive factors (i.e. working memory and processing speed) associated with eye movement differences and comprehension failures. In the sentence comprehension task, participants read subordinate-main structures that were either ambiguous or unambiguous, and we also manipulated the type of verb contained in the subordinate clause (i.e. reflexive or optionally transitive). Results showed a main effect of group on comprehension, in which individuals with dyslexia showed poorer comprehension than typically-developing readers. In addition, participants with dyslexia showed longer total reading times on the disambiguating region of syntactically ambiguous sentences. With respect to cognitive factors, working memory was more associated with group differences than was processing speed. Conclusions focus on sentence-level syntactic processing issues in dyslexia (a previously under-researched area) and the relationship between online and offline measures of syntactic ambiguity resolution

Liver transplantation at Red Cross War Memorial Children's Hospital

No Abstract. South African Medical Journal Vol. 96(9) (Part 2) 2006: 960-96

Liver transplantation at Red Cross War Memorial Children's Hospital

The liver transplant programme for infants and children at Red Cross War Memorial Children's Hospital is the only established paediatric service in sub-Saharan Africa. Referrals for liver transplant assessment come from  most provinces within Smith Africa as well as neighbouring countries. Patients and methods. Since 1987, 81 children (range 6 months - 14 years) have had 84liver transplants with biliary atresia being the most frequent diagnosis. The indications for transplantation include biliary atresia (48), metabolic (7), fulminant hepatic failure (10), redo transplants (3) and other (16). Four combined liver/kidney transplants have been performed. Fifty-three were reduced-size transplants with donor/recipient weight ratios  ranging from 2:1 to 11:1 and .32 children weighed less than 10 kg.Results. Sixty patients (74%) survived 3 months -14 years post transplant. Overall cumulative 1- and 5-year patient survival figures are 79% and 70% respectively. However, with the introduction of prophylactic intravenous ganciclovir and the exclusion of hepatitis B virus (HBV) IgG core Ab-positive donors, the 1-year patient survival is 90% and the projected 5-year  paediatric survival is&gt; 80%. Early(&lt; 1 month) postliver- transplantmortality was low. Causes include primary malfunction (1), inferior vena cava   thrombosis (1), bleeding oesophageal ulcer (1), sepsis (1) and cerebral oedema (1). Late morbidity and mortality was mainly due to infections: de novo hepatitis B (5 patients, 2 deaths), Epstein--Barr virus (EBV)related post-transplantation lymphoproliferative disease (12 patients, 7 deaths) and cytomegalovirus (CMV) disease (10 patients, 5 deaths). Tuberculosis (TB) treatment in 3 patients was complicated by chronic rejection (1) and TB-drug-induced subfulminant liver failure (1).Conclusion. Despite limited resources, a successful paediatric programme has been established with good patient and graft survival figures and excellent quality of life. Shortage of donors because of infection with HBV and human immunodeficiency virus (HIV) leads to significant waiting-list mortality and infrequent transplantation