A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel.

Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.

Use of activated recombinant coagulation factor VII in patients undergoing reconstruction surgery for traumatic fracture of pelvis or pelvis and acetabulum: a double-blind, randomized, placebo-controlled trial.

BACKGROUND: Activated recombinant coagulation factor VII (rFVIIa) effectively prevents and controls bleeding in patients with coagulopathy. Data show that rFVIIa may reduce blood loss and eliminate the need for transfusion in patients with normal haemostasis undergoing major surgery. We assessed the efficacy of rFVIIa in patients with normal haemostasis undergoing repair surgery of major traumatic fracture of the pelvis or the pelvis and acetabulum, who were expected to have a large volume of blood loss. METHODS: We performed a double-blind, randomized, placebo-controlled trial involving 48 patients undergoing major pelvic-acetabular surgery. Patients were randomized to receive an i.v. bolus injection of rFVIIa 90 microg kg(-1) or placebo as add-on therapy at the time of the first skin incision. All patients also received intraoperative salvaged red blood cells (RBC). RESULTS: There was no significant difference in the total volume of perioperative blood loss, the primary outcome variable, between the rFVIIa and placebo groups. In addition, there were no differences between the two groups in the total volume of blood components, including salvaged RBC transfused, number of patients requiring allogeneic blood components, total volume of fluids infused, total operating time, time taken after entry to the intensive care unit to reach normal body temperature and acid-base status, and time spent in hospital. No adverse events, in particular thromboembolic events, were reported in either group. CONCLUSIONS: In patients with normal haemostasis undergoing repair surgery of traumatic pelvic-acetabular fracture, the prophylactic use of rFVIIa does not decrease the volume of perioperative blood loss.

Calibration of three capnographs for use with helium and oxygen gas mixtures.

Capnography is considered essential in the management of mechanically-ventilated patients. Helium, as an adjunct to mechanical ventilation, is the subject of renewed interest and used increasingly. However, helium affects the performance of infrared capnometry. We constructed a simple device to generate variable mixtures of helium, oxygen and carbon dioxide within the normal physiological range, and tested the performance of two side-stream and one in-line capnographs. We found that addition of helium to the gas mixture caused all three capnographs to underestimate the concentration of carbon dioxide. The underestimation increased as the proportion of helium increased. The maximum underestimation (30%) occurred in a 79:21 helium/oxygen mixture.

The strong ion gap does not have prognostic value in critically ill patients in a mixed medical/surgical adult ICU.

OBJECTIVE: To examine whether the strong ion gap (SIG) or standard base excess corrected for abnormalities of serum chloride and albumin (BE(UA)) can predict outcome and to compare the prognostic abilities of these variables with standard base excess (SBE), anion gap (AG), pH, and lactate, the more traditional markers of acid-base disturbance. DESIGN: Prospective, observational study. SETTING: University teaching hospital, general adult ICU. PATIENTS: One hundred consecutive patients on admission to the ICU. MEASUREMENTS AND RESULTS: The anion gap (AG) was calculated and corrected for abnormal serum albumin (AG(corrected)). Serum lactate was measured and SBE, BE(UA), SIG, and APACHE II scores calculated for each patient. 28-day survival was recorded. There was a significant difference between the mean APACHE II (P < 0.001), SBE (P < 0.001), lactate (P = 0.008), AG (P = 0.007), pH (P < 0.001), and BE(UA) (P = 0.009) of survivors and non-survivors. There was no significant difference between the mean SIG (P = 0.088), SIDeff (P = 0.025), and SID app (P = 0.254) between survivors and non-survivors. The pH and SBE demonstrated the best ability of the acid-base variables to predict outcome (AUROC curves 0.72 and 0.71, respectively). Neither of these were as good as the APACHE II score (AUROC 0.76) CONCLUSION: Traditional indices of SBE, BE(UA,) lactate, pH, AG, and APACHE II all discriminated well between survivors and non-survivors. In this group of patients the SIG, SIDeff, and SIGapp appear to offer no advantage in prediction of outcome and their use as prognostic markers can therefore not be advocated.

Adult vaccinations.

Adult vaccination saves lives and is cost-effective. During influenza epidemics, more than 20,000 estimated deaths occur in the United States. Despite the benefits of adult vaccination and the availability of usage guidelines, vaccination rates remain low. In 1999, only 67% and 55% of elderly persons reported receiving influenza and pneumoccal vaccines. Vaccination indications are categorized as age, health, occupation, lifestyle, and environment.

Effect of the Vaccines for Children program on physician referral of children to public vaccine clinics: a pre-post comparison.

OBJECTIVE: Started in late 1994, the Vaccines for Children (VFC) program is a major entitlement program that provides states with free vaccines for disadvantaged children. Some evaluation studies have been conducted, but they do not include individually matched pre-post comparisons of physician responses. This project studied the effect of the VFC on the physician likelihood of referring children to public vaccine clinics for immunizations. DESIGN: In 1999, trained personnel conducted a survey of a cohort of physicians who previously participated in surveys on barriers to childhood vaccination conducted before VFC implementation. Responses were matched, and pre- versus post-VFC comparisons were made. SETTING AND PARTICIPANTS: Minnesota and Pennsylvania primary care physicians selected by stratified random sampling and initially studied in 1990 to 1991 and 1993, respectively. MAIN OUTCOME MEASURES: Likelihood of referral of a child to a public vaccine clinic. RESULTS: On a scale of 0 to 10, physician likelihood of referring an uninsured child decreased by a mean of 1.9 (95% confidence interval: 1.2-2.5) from pre- to post-VFC. Two fifths (45%) of physicians reported that the VFC decreased the number of referrals from their practice to public vaccine clinics and 50% gave intermediate responses. Among physicians who participate in VFC, only 9% were likely to refer a Medicaid-insured child in contrast to 44% of those not participating. CONCLUSIONS: Physicians' reported referral and likelihood of referring Medicaid-insured and uninsured children has decreased because of VFC in Minnesota and Pennsylvania.vaccination/economics, vaccination/legislation and jurisprudence, immunization programs/economics, immunization programs/utilization, vaccines/economics, Medicaid/economics, national health programs United States, child health services.

A comprehensive investigation of barriers to adult immunization: a methods paper.

OBJECTIVE: Immunization rates for influenza and pneumococcal vaccines among the elderly (especially minority elderly) are below desired levels. We sought to answer 4 questions: (1) What factors explain most missed immunizations? (2) How are patient beliefs and practices regarding adult immunization affected by racial or cultural factors? (3) How are immunizations and patient beliefs affected by physician, organizational, and operational factors? and (4) Based on the relationships identified, can typologies be created that foster the tailoring of interventions to improve immunization rates? STUDY DESIGN: A multidisciplinary team chose the PRECEDE-PROCEED framework, the Awareness-to-Adherence model of clinician response to guidelines, and the Triandis model of consumer decision making as the best models to assess barriers to and facilitators of immunization. Our data collection methods included focus groups, face-to-face and telephone interviews, self-administered surveys, site visits, participant observation, and medical record review. POPULATION: To encounter a broad spectrum of patients, facilities, systems, and interventions, we sampled from 4 strata: inner-city neighborhood health centers, clinics in Veterans Administration facilities, rural practices in a network, and urban/suburban practices in a network. In stage 1, a stratified random cluster sample of 60 primary care clinicians was selected, 15 in each of the strata. In stage 2, a random sample of 15 patients was selected from each clinician's list of patients, aiming for 900 total interviews. CONCLUSIONS: This multicomponent approach is well suited to identifying barriers to and facilitators of adult immunizations among a variety of populations, including the disadvantaged.

Prognostic factors in intensive care.

Predicting the outcome of critical illness remains an evolving art despite many recent advances. This review article describes the tools currently employed, appraising each in turn. The subject is viewed from the perspective that physiological reserve and inflammatory response are the essential elements in assessing prognosis in patients with multi-organ dysfunction/failure, the most commonly encountered syndrome in intensive care practice.

Permittivity measurement of thermoplastic composites at elevated temperature.

The material properties of greatest importance in microwave processing of a dielectric are the complex relative permittivity epsilon = epsilon'-jepsilon", and the loss tangent, tan delta = epsilon"/epsilon'. This paper describes two convenient laboratory based methods to obtain epsilon', epsilon" and hence tan delta of fibre-reinforced thermoplastic (FRTP) composites. One method employs a microwave network analyzer in conjunction with a waveguide transmission technique, chosen because it provides the widest possible frequency range with high accuracy. The values of the dielectric constant and dielectric loss of glass fibre reinforced (33%) low density polyethylene, LDPE/GF (33%), polystyrene, PS/GF (33%), and Nylon 66/GF (33%), were obtained. Results are compared with those obtained by another method using a high-temperature dielectric probe.

Systemic Weber-Christian disease complicated by partial transverse myelopathy.

Weber-Christian disease is an inflammatory disorder of fatty tissue which usually presents with raised red tender nodules in the skin. Although there may be additional systemic upset, there are very few reports of neurological features associated with this condition. We report a patient with biopsy-confirmed systemic Weber-Christian disease in whom a transient partial myelopathy, of probable inflammatory origin, was the most prominent feature. Based on recent reports of the effects of immune mediators on neuronal function, a possible pathogenetic explanation for this syndrome is suggested.

Does the Vaccines for Children program influence pediatric nurse practitioner referral of disadvantaged children to public vaccine clinics?

OBJECTIVE: Concerns about financial barriers to vaccination led to the creation of the Vaccines for Children (VFC) program, which provides free vaccines to states for disadvantaged children. Our objective was to understand the effect of free vaccine and insurance on pediatric nurse practitioners' (PNPs) likelihood of referring children to public vaccine clinics. Although referral from the medical home to public vaccine clinics is preferable to not vaccinating, there are disadvantages, including the potential for windows of inadequate protection and fragmentation of care. METHODS: A standardized survey was conducted by trained personnel using computer-assisted telephone interviewing. We interviewed a national random sample of primary care PNPs in 1997. RESULTS: In 1997, 252 of 271 (93%) directly contacted PNPs were interviewed. The percentage of respondents receiving free vaccines was 82%. Among PNPs not receiving free vaccines, the percentages stating that they were likely to refer insured, Medicaid insured, and uninsured children to public vaccine clinics were 7%, 27%, and 67%, respectively. In contrast, among PNPs receiving free vaccines, only 46% would refer an uninsured child and 10% a Medicaid child. CONCLUSIONS: Most respondents received free vaccine supplies in 1997. Based on current PNP data and previous physician data, most clinicians who do not receive free vaccine supplies are likely to refer uninsured children to public vaccine clinics. In contrast, clinicians who receive free vaccine supplies are much more likely to vaccinate uninsured and Medicaid-insured children.

A transmission imaging spectrograph and microfabricated channel system for DNA analysis.

In this paper we present the development of a DNA analysis system using a microfabricated channel device and a novel transmission imaging spectrograph which can be efficiently incorporated into a high throughput genomics facility for both sizing and sequencing of DNA fragments. The device contains 48 channels etched on a glass substrate. The channels are sealed with a flat glass plate which also provides a series of apertures for sample loading and contact with buffer reservoirs. Samples can be easily loaded in volumes up to 640 nL without band broadening because of an efficient electrokinetic stacking at the electrophoresis channel entrance. The system uses a dual laser excitation source and a highly sensitive charge-coupled device (CCD) detector allowing for simultaneous detection of many fluorescent dyes. The sieving matrices for the separation of single-stranded DNA fragments are polymerized in situ in denaturing buffer systems. Examples of separation of single-stranded DNA fragments up to 500 bases in length are shown, including accurate sizing of GeneCalling fragments, and sequencing samples prepared with a reduced amount of dye terminators. An increase in sample throughput has been achieved by color multiplexing.

Crossed waveguide directional couplers for high power applications.

The small aperture coupling theory of the broad wall to broad wall (Moreno) coupler is reviewed and extended. It is shown that a lower limit on the directivity is given by the ratio of magnetic polarizability to electric polarizability for the coupling apertures. Hence directivity may be improved by using very narrow crossed slots for coupling. The results of coupling measurements on a Moreno coupler are presented to demonstrate the accuracy of the small aperture theory. A small aperture design procedure has also been developed for the narrow wall to broad wall coupler, which takes into account the effect of wall proximity on slot coupling. The measured results for the manufactured coupler are in excellent agreement with this theory.

Microwave facilities for welding thermoplastic composites and preliminary results.

The wide range of applications of microwave technology in manufacturing industries has been well documented (NRC, 1994; Thuery, 1992). In this paper, a new way of joining fibre reinforced thermoplastic composites with or without primers is presented. The microwave facility used is also discussed. The effect of power input and cycle time on the heat affected zone (HAZ) is detailed together with the underlying principles of test piece material interactions with the electromagnetic field. The process of autogenous joining of 33% by weight of random glass fibre reinforced Nylon 66, polystyrene (PS) and low density polyethylene (LDPE) as well as 23.3% by weight of carbon fibre reinforced PS thermoplastic composites is discussed together with developments using filler materials, or primers in the heterogenous joining mode. The weldability dependence on the dielectric loss tangent of these materials at elevated temperatures is also described.

Electronic Structure of the Aqueous Vanadyl Ion Probed by 9 and 94 GHz EPR and Pulsed ENDOR Spectroscopies and Density Functional Theory Calculations.

The aqueous vanadyl ion ([VO(H(2)O)(5)](2+)) has been investigated by X-band EPR, 94 GHz W-band EPR, and ESE-ENDOR. These experiments reveal information about the hyperfine (|A(xx)| = 208.5 MHz, |A(yy)| = 208.5 MHz, |A(zz)| = 547.0 MHz), and nuclear quadrupole coupling (|e(2)qQ| = 5.6 MHz) of the (51)V nucleus. The measured nuclear quadrupole coupling parameters are compared to values determined by density functional theory calculations (|e(2)qQ| = 5.2 MHz). These theoretical calculations illustrate that axial ligands and molecular distortions can alter the magnitude of the nuclear quadrupole interaction.

Diclofenac/misoprostol compared with diclofenac in the treatment of osteoarthritis of the knee or hip: a randomized, placebo controlled trial. Arthrotec Osteoarthritis Study Group.

OBJECTIVE: Gastric (GU) and duodenal ulcers (DU) are common adverse effects of nonsteroidal anti-inflammatory drugs (NSAID). Endoscopically diagnosed upper gastrointestinal (GI) ulceration occurs in about 24% of longterm NSAID users. Coadministration of misoprostol with the NSAID reduces the incidence of NSAID induced GU and DU and their complications. However, compliance is limited by the different dosing regimens of misoprostol and NSAID and GI symptoms associated with misoprostol at its recommended q.i.d. dose. We compared the efficacy, safety, and incidence of endoscopic upper GI ulceration associated with the administration of 2 combinations of diclofenac (50 or 75 mg) and misoprostol 200 microg (D50/M200 t.i.d., D75/M200 b.i.d.), diclofenac 75 mg b.i.d., and placebo in a 6 week, randomized, double blind study in patients with osteoarthritis (OA) of the knee or hip. METHODS: A total of 572 patients with symptomatic OA of the knee or hip and history of GU, DU. or 10 or more erosions were randomized to receive D50/M200 t.i.d., D75/M200 b.i.d., diclofenac 75 mg b.i.d., or placebo for 6 weeks. Arthritis assessments were performed at baseline, 2, and 6 weeks, and upper GI endoscopies at baseline and end of treatment. RESULTS: All active treatment groups were significantly better than placebo, at all visits, in improving OA symptoms. There were no significant differences in arthritis efficacy between the diclofenac/ misoprostol combinations and diclofenac. However, endoscopically diagnosed GU and/or DU were significantly less frequent in patients receiving D50/M200 t.i.d. (8%), D75/M200 b.i.d. (7%), and placebo (4%) compared to diclofenac 75 mg b.i.d. (17%). Adverse events were not different between the active treatment groups, except for higher incidences of flatulence with D75/M200 and diarrhea with D50/M200. CONCLUSION: Diclofenac 50 mg/misoprostol 200 microg t.i.d. and diclofenac 75 mg/misoprostol 200 microg b.i.d. are as efficacious as diclofenac 75 mg b.i.d. in the treatment of OA, but are associated with a significantly lower incidence of gastric and/or duodenal ulcers.

Pulmonary manifestations of Goodpasture's syndrome. Antiglomerular basement membrane disease and related disorders.

Goodpasture's syndrome, or antiglomerular basement membrane disease, is a disorder in which lungs and kidneys are affected by the binding of anti-GBM antibodies, leading to pulmonary hemorrhage and glomerulonephritis with rapidly progressive renal insufficiency. Recent advances in the understanding of disease pathogenesis and diagnosis and treatment have significantly improved our ability to recognize the syndrome, distinguish it from other similar disorders, and offer successful treatment. This article focuses on the pathogenetic features, clinical manifestations, diagnostic strategies, and therapeutic principles of anti-GBM disease.