Analysis of circuit conditions for optimum intermodulation and gain in bipolar cascomp amplifiers with non-ideal error correction

The cascoded-compensation or ‘Cascomp’ amplifier offers excellent distortion reduction and thermal distortion rejection, but has not seen widespread use because of a limited gain and increased complexity compared with other topologies. The original theory showed that with the addition of an ideal error amplifier the circuit will completely compensate distortion for suitably chosen degeneration and bias values. This research presents a new, rigorous mathematical proof for conditions of compensation. The authors further develop the proof to include the non-idealities of the error amplifier. It is shown that there exists a second bias point, not exposed by the original analysis that offers improved gain while maintaining distortion cancellation. By reducing the error amplifier degeneration resistance, one can increase a Cascomp circuit's overall gain by several dB while maintaining theoretically perfect distortion compensation. A robust bias point is proposed, which takes the advantage of this new theory by optimising circuit values resulting in a comparatively broader and deeper third-order distortion null. The proposed theory is confirmed with simulation and measurement that show agreement within the bounds of process and component error limits

Evolution and Age Relations of Karst Landscapes

Any karst landscape is a work in progress. The observed evolution of the landscape is dictated by competing rate processes of surface denudation, stream downcutting, cave development, and tectonic uplift. Quantitative data on these processes, applied to two physiographic provinces of the Appalachian Mountains of eastern United States gives ages and time scales that are in agreement with previous geomorphic interpretation. The results are anchored, very loosely, by the few dates that have been established for cave sediments. Unfortunately, the measured rates vary over an order of magnitude as a result of local circumstances making regional interpretation a rough approximation at best

Carbon fluxes in Karst aquifers: Sources, sinks, and the effect of storm flow

An effective carbon loading can be calculated from measured alkalinity and pH of karst waters. The carbon loading is independent of the degree of saturation of the water and does not depend on the water being in equilibrium with the carbonate wall rock. A substantial data base of spring water analyses accumulated by students over the past 40 years has been used to probe the CO2 generation, transport, and storage in a variety of drainage basins that feed karst springs. Carbon loading in the water exiting karst drainage basins depends on the rate of CO2 generation in the soils of the catchment areas and on the partitioning between CO2 dissolved in infiltration water and CO2 lost by diffusion upward to the atmosphere. For any given drainage basin there are also influences due to vegetative cover, soil type, and the fraction of the water provided by sinking stream recharge. Losses of CO2 back to the atmosphere occur by speleothem deposition in air-filled caves, by degassing of CO2 in spring runs, and by tufa deposition in spring runs. There are seasonal cycles of CO2 generation that relate growing season and contrasts in winter/summer rates of CO2 generation. Overall, it appears that karst aquifers are a net, but leaky, sink for atmospheric CO2.Keywords: CO2, karst aquifers, springs, carbon loading.DOI: 10.3986/ac.v42i2-3.659

The Unintended Effects of AACSB\u27s 2003 Accreditation Standards

The AACSB recently adopted new accreditation guidelines that are less restrictive regarding what constitutes qualified faculty for accreditation purposes. The new standards are less restrictive, with less emphasis on a terminal degree and more on faculty being fully participating. However, the new standard may have a detrimental effect on the quality of collegiate business education. It may also reduce the standing and prestige of business schools within the university community. Finally, it may reduce the value of AACSB accreditation

Transcriptional repression by ApiAP2 factors is central to chronic toxoplasmosis

Tachyzoite to bradyzoite development in Toxoplasma is marked by major changes in gene expression resulting in a parasite that expresses a new repertoire of surface antigens hidden inside a modified parasitophorous vacuole called the tissue cyst. The factors that control this important life cycle transition are not well understood. Here we describe an important transcriptional repressor mechanism controlling bradyzoite differentiation that operates in the tachyzoite stage. The ApiAP2 factor, AP2IV-4, is a nuclear factor dynamically expressed in late S phase through mitosis/cytokinesis of the tachyzoite cell cycle. Remarkably, deletion of the AP2IV-4 locus resulted in the expression of a subset of bradyzoite-specific proteins in replicating tachyzoites that included tissue cyst wall components BPK1, MCP4, CST1 and the surface antigen SRS9. In the murine animal model, the mis-timing of bradyzoite antigens in tachyzoites lacking AP2IV-4 caused a potent inflammatory monocyte immune response that effectively eliminated this parasite and prevented tissue cyst formation in mouse brain tissue. Altogether, these results indicate that suppression of bradyzoite antigens by AP2IV-4 during acute infection is required for Toxoplasma to successfully establish a chronic infection in the immune-competent host

Evaluation of the angiotensin II receptor blocker azilsartan medoxomil in African-American patients with hypertension

The efficacy and safety of azilsartan medoxomil (AZL-M) were evaluated in African-American patients with hypertension in a 6-week, double-blind, randomized, placebo-controlled trial, for which the primary end point was change from baseline in 24-hour mean systolic blood pressure (BP). There were 413 patients, with a mean age of 52years, 57% women, and baseline 24-hour BP of 146/91mmHg. Treatment differences in 24-hour systolic BP between AZL-M 40mg and placebo (-5.0mmHg; 95% confidence interval, -8.0 to -2.0) and AZL-M 80mg and placebo (-7.8mmHg; 95% confidence interval, -10.7 to -4.9) were significant (P.001 vs placebo for both comparisons). Changes in the clinic BPs were similar to the ambulatory BP results. Incidence rates of adverse events were comparable among the treatment groups, including those of a serious nature. In African-American patients with hypertension, AZL-M significantly reduced ambulatory and clinic BPs in a dose-dependent manner and was well tolerated

Integrated safety studies of the urate reabsorption inhibitor lesinurad in treatment of gout.

ObjectiveLesinurad (LESU) is a selective urate reabsorption inhibitor approved at 200 mg daily for use with a xanthine oxidase inhibitor (XOI) to treat hyperuricaemia in gout patients failing to achieve target serum urate on XOI. The aim of the study was to investigate the long-term safety of LESU + XOI therapy.MethodsSafety data were pooled from three 12-month phase III (core) trials evaluating LESU 200 and 400 mg/day combined with an XOI (LESU200+XOI and LESU400+XOI), and two 12-month extension studies using descriptive statistics. To adjust for treatment duration, treatment-emergent adverse events (TEAEs) were expressed as exposure-adjusted incidence rates (patients with events per 100 person-years).ResultsIn the core studies, exposure-adjusted incidence rates for total and total renal-related TEAEs were comparable for XOI alone and LESU200+XOI but higher with LESU400+XOI. Exposure-adjusted incidence rates for serum creatinine (sCr) elevations ⩾1.5×baseline were 2.9, 7.3 and 18.7, respectively. Resolution (sCr ⩽1.2×baseline) occurred in 75-90% of all events, with 66-75% occurring without any study medication interruption. Major adverse cardiovascular events were 3, 4 and 9 with XOI, LESU200+XOI and LESU400+XOI, respectively. Longer exposure in core+extension studies did not increase rates for any safety signals.ConclusionAt the approved dose of 200 mg once-daily combined with an XOI, LESU did not increase renal, cardiovascular or other adverse events compared with XOI alone, except for sCr elevations. With extended exposure in the core+extension studies, the safety profile was consistent with that observed in the core studies, and no new safety concerns were identified

Impact of NSAIDs on cardiovascular risk and hypertension

Introduction: In recent years, there has been a great deal of evaluation of the cardiovascular (CV) effects of the non-steroidal anti-inflammatory drugs (NSAIDs) and the selective cyclooxygenase- 2 (COX-2) inhibitors. Materials and methods: In this brief review, the focus is on both effects of the NSAIDs and COX-2 inhibitors on blood pressure and CV events. The literature was searched using PubMed for both clinical trials and observational studies reviewing the relations among NSAIDs, blood pressure, and CV events. Results: Clinical trial results for NSAIDs and COX-2 inhibitors have shown varying levels of destabilization of blood pressure control in treated hypertensive patients as well as variable incident rates of the development of arrhythmias, congestive heart failure, myocardial infarction, and stroke. Discussion: The non-selective and COX-2 selective NSAIDs can be used with care in selected arthritis patients with hypertension and stable CV disorders (excluding congestive heart failure and moderate to severe kidney dysfunction) when the individual clinical benefit of antiinflammatory therapy outweighs the CV and gastrointestinal risk