Dear Wife : the Civil War letters of Chester K. Leach

Occasional paper (University of Vermont. Center for Research on Vermont) ; no. 20

Appropriate timing of the 14 C-urea breath test to establish eradication of Helicobacter pylori infection

The aim of this study was to determine the performance characteristics of the 14 C-urea breath test (UBT) performed 2 wk after the completion of therapy for Helicobacter pylori using a 4 to 6 wk study as the gold standard. METHODS : Patients with active Helicobacter pylori infection at four medical centers received proton pump inhibitor-based triple or quadruple therapy for 10–14 days. Patients underwent the 14 C-UBT 2 and 4–6 wk after the completion of therapy. A positive test was defined as 14 CO 2 excretion of >200 dpm, a negative test as 50 but <200 dpm. Performance characteristics of the 2-wk UBT were calculated using the 4 to 6-wk result as a gold standard. RESULTS : Eighty-five patients were enrolled and 82 patients (mean ± SD age, 62 ± 15 yr; 15 women) completed the protocol. Four patients had equivocal UBT results and were excluded from the analysis. Of the 78 patients, 68 (87%) had a negative 4 to 6-wk UBT. The 2-week UBT yielded a sensitivity of 90% (95% confidence interval 72–100%), specificity of 99% (97–100%), and accuracy of 97% (93–100%). In patients with a persistently positive UBT, 14 CO 2 excretion at 2 wk was significantly lower than at 4–6 wk after therapy ( p = 0.03 ). CONCLUSIONS : A UBT performed 2 wk after therapy yielded results comparable to 4 to 6 wk testing. Further studies to evaluate the optimal time of confirmatory testing in the age of more effective proton pump inhibitor-based triple therapies are warranted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73434/1/j.1572-0241.2000.02005.x.pd

Safety, the Preface Paradox and Possible Worlds Semantics

This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

Classical and Quantum-like approaches to Charged-Particle Fluids in a Quadrupole

A classical description of the dynamics of a dissipative charged-particle fluid in a quadrupole-like device is developed. It is shown that the set of the classical fluid equations contains the same information as a complex function satisfying a Schrodinger-like equation in which Planck's constant is replaced by the time-varying emittance, which is related to the time-varying temperature of the fluid. The squared modulus and the gradient of the phase of this complex function are proportional to the fluid density and to the current velocity, respectively. Within this framework, the dynamics of an electron bunch in a storage ring in the presence of radiation damping and quantum-excitation is recovered. Furthermore, both standard and generalized (including dissipation) coherent states that may be associated with the classical particle fluids are fully described in terms of the above formalism.Comment: LaTex, to appear in Physica Script

A comparison of three fingerstick, whole blood antibody tests for Helicobacter pylori infection: a United States, multicenter trial

We compared three whole blood antibody tests for Helicobacter pylori ( H. pylori ) in a United States, multicenter trial. Methods Patients referred for EGD at three medical centers were recruited. During EGD, biopsies were taken for histology and rapid urease testing (RUT). Immediately after endoscopy, patients underwent the antibody tests (FlexPack HP, Abbott Diagnostics; QuikVue, Quidel Corporation; AccuMeter, ChemTrak) using whole blood obtained by two to three fingersticks. Performance characteristics were calculated for each antibody test using the biopsy-based methods as a gold standard. Results A total of 131 patients participated; 50 (38%) patients had histological evidence of H. pylori infection. Using histology as a gold standard, the sensitivities of FlexPack HP, QuikVue, and Accumeter were 76%, 78%, and 84%, respectively. Specificity was 79% with FlexPack HP and 90% with QuikVue and Accumeter. There were no significant differences in the performance of the three antibody tests though there was a trend toward superior performance for AccuMeter compared to FlexPack HP ( p = 0.019 ). However, RUT proved superior to FlexPack HP using histology as a gold standard ( p = 0.008 ). Using either concordant histology and RUT results or a positive histology or RUT to define active H. pylori infection, there was no statistically significant difference between the antibody tests. Conclusions There were no statistically significant differences in the performance of the three antibody tests. These tests proved only marginally sensitive in detecting patients infected with H. pylori . Clinicians should be aware of the limitations of these tests, particularly when using them as a sole means of testing for H. pylori .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72148/1/j.1572-0241.1999.1135_x.x.pd

GeoTextMESS: result fusion with fuzzy Borda ranking in geographical information retrieval

In this paper we discuss the integration of different GIR systems by means of a fuzzy Borda method for result fusion. Two of the systems, the one by the Universidad Politécnica de Valencia and the one of the Universidad of Jaén participated to the GeoCLEF task under the name TextMess. The proposed result fusion method takes as input the document lists returned by the different systems and returns a document list where the documents are ranked according to the fuzzy Borda voting scheme. The obtained results show that the fusion method allows to improve the results of the component systems, although the fusion is not optimal, because it is effective only if the components return a similar set of relevant documents.Peer ReviewedPostprint (author’s final draft

Vegetation responses to the first 20 years of cattle grazing in an Australian desert

Existing theoretical frameworks suggest three predictions relevant to grazing effects in Australian aridlands: grazing has a negative but moderate effect on plant species richness; a separate "state" resulting from degradation caused by extreme grazing will be evident; some plant species will have a strong association with grazing relief refuges that have only ever been subject to light grazing. These predictions were examined in the dune swales of an Australian desert, with data on herbaceous species collected along transects up to 14 km from artificial water points between four and 33 years old. A cumulative grazing index was constructed utilizing both the spatial occupation patterns of cattle and the length of exposure. Despite restricting sampling to a narrow habitat, silt/clay content and soil pH influence floristic patterns independent of grazing. The analysis of quadrat data in relation to grazing revealed almost no patterns in plant cover, species richness (at two different scales), or abundance across plant life-form groups. Five species had an increasing response, and seven a decreasing response, while the only species restricted to areas of extremely low grazing pressure was sufficiently rare that it could have occurred there by chance. The dominant annual grass, the most common shrub, and a perennial tussock-forming sedge all decrease with high levels of grazing. Most species exhibit an ephemeral life strategy in response to unreliable rainfall, and this boom and bust strategy effectively doubles as an adaptation to grazing. After 20 years of exposure to managed grazing with domestic stock in Australian dune swales, patterns in species richness have not emerged in response to grazing pressure, the ecosystem has not been transformed to another degradation "state," and there is no evidence that grazing relief refuges provide havens for species highly sensitive to grazing

Rich Situated Attitudes

We outline a novel theory of natural language meaning, Rich Situated Semantics [RSS], on which the content of sentential utterances is semantically rich and informationally situated. In virtue of its situatedness, an utterance’s rich situated content varies with the informational situation of the cognitive agent interpreting the utterance. In virtue of its richness, this content contains information beyond the utterance’s lexically encoded information. The agent-dependence of rich situated content solves a number of problems in semantics and the philosophy of language (cf. [14, 20, 25]). In particular, since RSS varies the granularity of utterance contents with the interpreting agent’s informational situation, it solves the problem of finding suitably fine- or coarse-grained objects for the content of propositional attitudes. In virtue of this variation, a layman will reason with more propositions than an expert

Quasiperiodic spin-orbit motion and spin tunes in storage rings

We present an in-depth analysis of the concept of spin precession frequency for integrable orbital motion in storage rings. Spin motion on the periodic closed orbit of a storage ring can be analyzed in terms of the Floquet theorem for equations of motion with periodic parameters and a spin precession frequency emerges in a Floquet exponent as an additional frequency of the system. To define a spin precession frequency on nonperiodic synchro-betatron orbits we exploit the important concept of quasiperiodicity. This allows a generalization of the Floquet theorem so that a spin precession frequency can be defined in this case too. This frequency appears in a Floquet-like exponent as an additional frequency in the system in analogy with the case of motion on the closed orbit. These circumstances lead naturally to the definition of the uniform precession rate and a definition of spin tune. A spin tune is a uniform precession rate obtained when certain conditions are fulfilled. Having defined spin tune we define spin-orbit resonance on synchro--betatron orbits and examine its consequences. We give conditions for the existence of uniform precession rates and spin tunes (e.g. where small divisors are controlled by applying a Diophantine condition) and illustrate the various aspects of our description with several examples. The formalism also suggests the use of spectral analysis to ``measure'' spin tune during computer simulations of spin motion on synchro-betatron orbits.Comment: 62 pages, 1 figure. A slight extension of the published versio