State and output feedback design for robust tracking of linear systems with rate limited actuators

A design technique (Control of Uncertain Systems with Bounded Inputs, Tarbouriech S, Garcia G, (Eds), Lecture Notes in Control and Information Sciences, vol. 227 , Springer: Berlin, 1997; 173–186) recently proposed for stabilization of a linear system with rate‐limited actuators is utilized to design feedback laws that cause the system output to track a desired command signal. This design technique combines two design techniques recently developed for linear systems with position limited actuators, piecewise‐linear LQ control (Automatica, 1994; 30 : 403–416) and low‐and‐high gain feedback (IEEE Trans. Automat. Control, 1996; 41 : 368–378), and hence takes advantage of both design techniques, while avoiding their disadvantages. In the case that only the output is available for feedback, the performance of the state feedback law is preserved by the use of a fast observer. An open‐loop exponentially unstable fighter aircraft is used to demonstrate the effectiveness of the proposed control design method. Copyright © 2002 John Wiley & Sons, Ltd.     

The use of N-acetylcysteine long after an acetaminophen overdose in mice

N-Acetylcysteine (NAC), given to mice 5 h after an LD50 dose of acetaminophen, decreased 24-h survival to 33%. The reduction in survival observed for late NAC is significantly lower than the survival observed for the LD50 dose alone (53%), and is in sharp contrast to the 100% survival reported for the early use of NAC.     

GC-MS Determination of Targeted Pesticides in Environmental Samples from the Kafue Flats of Zambia

Results of a GC-MS analysis for targeted pesticides i.e. dieldrin, endosulfan, pp-DDT, endrin, HCB, heptachlor, mirex and aldrin in the Kafue Flats of Zambia are presented. Analysis was done in soils, sediments, water and vegetation samples from the Lochinvar and Blue Lagoon National Parks along the Kafue River. A validated analytical method that was used gave recoveries in a spiked soil sample ranging between 60 % and 100 % with limits of detection (LODs) ranging from 0.94 to 8.0 ng/g. The targeted pesticides were not detected in all the samples i.e. were below LODs. Screening using the Automated Mass Spectral Deconvolution and Identification System (AMDIS) simplified the analysis due to its power of deconvolution and identification of analytes of interest.     

Propylthiouracil-induced autoimmune disease

Hyperthyroidism is a condition characterized by excessive production of thyroid hormones. Propylthiouracil (PTU) is commonly used as first line drug in the management of hyperthyroidism. This is a case report of 24-year-old female, a known case of hyperthyroidism since 4 years, who came with a history of fever and myalgia since 3 days and dyspnea with coughing out of blood since 1 day. Patient was taking PTU (100 mg per day) since 4 years for hyperthyroidism. Patient was immediately intubated for type-II respiratory failure. Diagnosed to be having PTU-induced autoimmune disease. PTU was stopped and treated with methylprednisolone and cyclophosphamide. Clinical features improved over a period of 8 days and discharged home successfully. Having a high suspicion for the onset of autoimmune disease in hyperthyroidism patients who are on PTU therapy and timely treatment with immunosuppressants and supportive care along with the withdrawal of the drug can make a difference in morbidity and mortality.     

Human complement receptor 2 (CR2/CD21) as a receptor for DNA: Implications for its roles in the immune response and the pathogenesis of systemic lupus erythematosus (SLE)

Human CR2 is a B cell membrane glycoprotein that plays a central role in autoimmunity. Systemic lupus erythematosus (SLE) patients show reduced CR2 levels, and complete deficiency of CR2 and CR1 promotes the development of anti-DNA antibodies in mouse models of SLE. Here we show that multiple forms of DNA, including bacterial, viral and mammalian DNA, bind to human CR2 with moderately high affinity. Surface plasmon resonance studies showed that methylated DNA bound with high affinity with CR2 at a maximal K(D) of 6nM. DNA was bound to the first two domains of CR2 and this binding was blocked by using a specific inhibitory anti-CR2 mAb. DNA immunization in Cr2(-/-) mice revealed a specific defect in immune responses to bacterial DNA. CR2 can act as a receptor for DNA in the absence of complement C3 fixation to this ligand. These results suggest that CR2 plays a role in the recognition of foreign DNA during host-immune responses. This recognition function of CR2 may be a mechanism that influences the development of autoimmunity to DNA in SLE.     

Isolation of a nonmitogenic angiogenesis factor from wound fluid.

Angiogenesis, or new capillary growth, is essential to normal growth and wound healing. It is also active in several pathologic states, including the growth of malignant tumors. An extracellular, nonneoplastic angiogenesis factor has been isolated from cell-free rabbit wound fluid by pore-limit dialysis and chromatography on a size-exclusion HPLC column. The isolated angiogenesis factor was purified 9,600-fold with a yield of 81% and has a molecular weight between 2,000 and 14,000. Wound fluid angiogenesis factor was completely separated from the mitogenic activity of wound fluid; it did not increase the number of capillary endothelial cells in vitro or stimulate [3H]thymidine uptake by these cells. The isolated angiogenesis factor stimulated endothelial cell migration in vitro, and less than 200 ng of the factor stimulated angiogenesis in vivo in the corneal implant assay.     

Improved identification and enrolment into care of HIV-exposed and -infected infants and children following a community health worker intervention in Lilongwe,Malawi

Background

Early identification and entry into care is critical to reducing morbidity and mortality in children with HIV. The objective of this report is to describe the impact of the Tingathe programme, which utilizes community health workers (CHWs) to improve identification and enrolment into care of HIV-exposed and -infected infants and children.

Methods

Three programme phases are described. During the first phase, Mentorship Only (MO) (March 2007–February 2008) on-site clinical mentorship on paediatric HIV care was provided. In the second phase, Tingathe-Basic (March 2008–February 2009), CHWs provided HIV testing and counselling to improve case finding of HIV-exposed and -infected children. In the final phase, Tingathe-PMTCT (prevention of mother-to-child transmission) (March 2009–February 2011), CHWs were also assigned to HIV-positive pregnant women to improve mother-infant retention in care. We reviewed routinely collected programme data from HIV testing registers, patient mastercards and clinic attendance registers from March 2005 to March 2011.

Results

During MO, 42 children (38 HIV-infected and 4 HIV-exposed) were active in care. During Tingathe-Basic, 238 HIV-infected children (HIC) were newly enrolled, a six-fold increase in rate of enrolment from 3.2 to 19.8 per month. The number of HIV-exposed infants (HEI) increased from 4 to 118. During Tingathe-PMTCT, 526 HIC were newly enrolled over 24 months, at a rate of 21.9 patients per month. There was also a seven-fold increase in the average number of exposed infants enrolled per month (9.5–70 patients per month), resulting in 1667 enrolled with a younger median age at enrolment (5.2 vs. 2.5 months; p<0.001).During the Tingathe-Basic and Tingathe-PMTCT periods, CHWs conducted 44,388 rapid HIV tests, 7658 (17.3%) in children aged 18 months to 15 years; 351 (4.6%) tested HIV-positive. Over this time, 1781 HEI were enrolled, with 102 (5.7%) found HIV-infected by positive PCR. Additional HIC entered care through various mechanisms (including positive linkage by CHWs and transfer-ins) such that by February 2011, a total of 866 HIC were receiving care, a 23-fold increase from 2008.

Conclusions

A multipronged approach utilizing CHWs to conduct HIV testing, link HIC into care and provide support to PMTCT mothers can dramatically improve the identification and enrolment into care of HIV-exposed and -infected children.