Experimental and theoretical studies of the Xe-OH(A/X) quenching system

New multi-reference, global ab initio potential energy surfaces (PESs) are reported for the interaction of Xe atoms with OH radicals in their ground X²Π and excited A²Σ⁺ states, together with the non-adiabatic couplings between them. The 2A' excited potential features a very deep well at the collinear Xe-OH configuration whose minimum corresponds to the avoided crossing with the 1A' PES. It is therefore expected that, as with collisions of Kr + OH(A), electronic quenching will play a major role in the dynamics, competing favorably with rotational energy transfer within the 2A' state. The surfaces and couplings are used in full three-state surface-hopping trajectory calculations, including roto-electronic couplings, to calculate integral cross sections for electronic quenching and collisional removal. Experimental cross sections, measured using Zeeman quantum beat spectroscopy, are also presented here for comparison with these calculations. Unlike similar previous work on the collisions of OH(A) with Kr, the surface-hopping calculations are only able to account qualitatively for the experimentally observed electronic quenching cross sections, with those calculated being around a factor of two smaller than the experimental ones. However, the predicted total depopulation of the initial rovibrational state of OH(A) (quenching plus rotational energy transfer) agrees well with the experimental results. Possible reasons for the discrepancies are discussed in detail.

Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces

Objective. Neural interfaces and other implantable micro-devices that use polymer-encapsulated integrated circuits will only be allowed in medical devices when their lifetimes can be estimated from experimental data. An apparatus has been developed and tested that allows hundreds of insulated samples (interdigitated combs) to be aged under accelerated conditions of high temperature and voltage stress. Occasionally, aging is paused while the sample’s impedance is measured; the impedance spectrogram may show degradation as it progresses before failure. Approach. The design was based on practical considerations which are reviewed. A Solartron Modulab provides the frequency response analyser and the femtoammeter. The apparatus can accommodate batches of samples at several temperatures and with different aging voltage waveforms. It is important to understand features of the spectra that are not due to comb–comb leakage, but come from other places (for example substrate-solution leakage); some have been observed and investigated using SPICE. Main results. The design is described in detail and test results show that it is capable of making measurements over long periods, at least up to 67 °C. Despite the size of the apparatus, background capacitance is about 1 pF and comb–comb capacitances of about 30 pF can be measured down to 10 mHz, an impedance of about 100 GΩ. An important discovery was the advantage of grounding the bathing solution, primarily in that it raises the measurement ceiling. Observation and SPICE simulation shows that leakage from the substrate to the bathing solution can give phase lags  >90°, in contrast to comb–comb leakage which reduces phase lag to  <90°. Significance. The value of this paper is that it will facilitate research into the endurance of small implanted devices because, given a description of a proven apparatus, researchers can start building their own apparatus relatively quickly and with confidence.

Improving accuracy of genomic prediction in Brangus cattle by adding animals with imputed low-density SNP genotypes

Reliable genomic prediction of breeding values for quantitative traits requires the availability of sufficient number of animals with genotypes and phenotypes in the training set. As of 31 October 2016, there were 3,797 Brangus animals with genotypes and phenotypes. These Brangus animals were genotyped using different commercial SNP chips. Of them, the largest group consisted of 1,535 animals genotyped by the GGP-LDV4 SNP chip. The remaining 2,262 genotypes were imputed to the SNP content of the GGP-LDV4 chip, so that the number of animals available for training the genomic prediction models was more than doubled. The present study showed that the pooling of animals with both original or imputed 40K SNP genotypes substantially increased genomic prediction accuracies on the ten traits. By supplementing imputed genotypes, the relative gains in genomic prediction accuracies on estimated breeding values (EBV) were from 12.60% to 31.27%, and the relative gain in genomic prediction accuracies on de-regressed EBV was slightly small (i.e. 0.87%-18.75%). The present study also compared the performance of five genomic prediction models and two cross-validation methods. The five genomic models predicted EBV and de-regressed EBV of the ten traits similarly well. Of the two cross-validation methods, leave-one-out cross-validation maximized the number of animals at the stage of training for genomic prediction. Genomic prediction accuracy (GPA) on the ten quantitative traits was validated in 1,106 newly genotyped Brangus animals based on the SNP effects estimated in the previous set of 3,797 Brangus animals, and they were slightly lower than GPA in the original data. The present study was the first to leverage currently available genotype and phenotype resources in order to harness genomic prediction in Brangus beef cattle.

An experimental study of OH(A2Σ+) + H2: Electronic quenching, rotational energy transfer, and collisional depolarization

Zeeman quantum beat spectroscopy has been used to determine the thermal (300 K) rate constants for electronic quenching, rotational energy transfer, and collisional depolarization of OH(A²Σ⁺) by H₂. Cross sections for both the collisional disorientation and collisional disalignment of the angular momentum in the OH(A²Σ⁺) radical are reported. The experimental results for OH(A²Σ⁺) + H₂ are compared to previous work on the OH(A²Σ⁺) + He and Ar systems. Further comparisons are also made to the OH(A²Σ⁺) + Kr system, which has been shown to display significant non-adiabatic dynamics. The OH(A²Σ⁺) + H₂ experimental data reveal that collisions that survive the electronic quenching process are highly depolarizing, reflecting the deep potential energy wells that exist on the excited electronic state surface.

Music-of-light stethoscope: a demonstration of the photoacoustic effect

In this paper we present a system aimed at demonstrating the photoacoustic (PA) effect for educational purposes. PA imaging is a hybrid imaging modality that requires no contrast agent and has a great potential for spine and brain lesion characterisation, breast cancer and blood flow monitoring notably in the context of fetal surgery. It relies on combining light excitation with ultrasound reception. Our brief was to present and explain PA imaging in a public-friendly way suitable for a variety of ages and backgrounds.

We developed a simple, accessible demonstration unit using readily available materials. We used a modulated light emitting diode (LED) torch and an electronic stethoscope. The output of a music player was used for light modulation and the chest piece of the stethoscope covered by a black tape was used as an absorbing target and an enclosed chamber.

This demonstration unit was presented to the public at the Bloomsbury Festival On Light in October 2015. Our stall was visited by over 100 people of varying ages. Twenty families returned in-depth evaluation questionnaires, which show that our explanations of the photoacoustic effect were well understood. Their interest in biomedical engineering was increased.

Renal arteriography using gadolinium enhanced 3D MR angiography--clinical experience with the technique, its limitations and pitfalls

Gadolinium enhanced 3D MR angiography (MRA) is becoming a widely accepted technique for imaging the vascular system. We set out to evaluate its accuracy and reliability in visualization of renal arteries in the clinical setting. Gadolinium enhanced MRA was performed in 15 potential live renal donors and 26 patients suspected of having renal artery stenosis who were referred for digital subtraction angiography (DSA). MRA was performed on a 1.5 T MR scanner in a single breath hold. Images from each study were prospectively analysed for demonstration of number of main and accessory renal arteries and degree of renal artery stenosis in a double blind fashion. All the main and accessory arteries were visualized on MRA in the renal donor group, but in one case a branch was not identified owing to breathing artefact. In one case, an extrarenal vascular anomaly was not demonstrated on MRA. In the renal artery stenosis group, sensitivity, specificity and negative predictive values of 96%, 93% and 96% were obtained for clinically significant stenosis (>50%). Gadolinium enhanced MRA proved to be a useful technique in demonstration of renal arterial anatomy and grading of renal artery stenosis. However, we encountered some pitfalls and limitations of the technique during the process. It is important to be aware of these before accepting it as the sole technique in clinical practice.

Morbidity in reflex sympathetic dystrophy

Reflex sympathetic dystrophy (RSD), an unusual diagnosis in general paediatrics, is well recognised by paediatric rheumatologists. This study reports the presentation and the clinical course of 46 patients (35 female, age range 8-15.2) with RSD. The patients saw professionals from an average of 2.3 specialties (range 1-5). Twenty five (54%) had a history of trauma. Median time to diagnosis was 12 weeks (range 1-130). Many children had multiple investigations and treatments. Once diagnosis was made, treatment followed with physiotherapy and analgesics. Median time to recovery was seven weeks (range 1-140), with 27.5% relapsing. Nine children required assessment by the child and adolescent psychiatry team. This disease, though rare, has significant morbidity and it is therefore important to raise clinicians' awareness of RSD in childhood. Children with the condition may then be recognised and referred for appropriate management earlier, and spared unnecessary investigations and treatments which may exacerbate the condition.

A prospective comparison of brain contrast characteristics and lesion detection using single-shot fast spin-echo and fast spin-echo

MRI is limited by movement artefact, even with current imagers, when examining a restless or claustrophobic patient. We prospectively analysed the images of 92 patients produced by a single-shot fast spin-echo (SSFSE) pulse sequence and compared them with conventional (FSE) and reduced-time fast spin-echo (RT-FSE) techniques, with regard to lesion detection and movement artefact in brain imaging. Images obtained in each case were independently reviewed and scored for overall diagnosis, number of lesions detected, and movement artefact. FSE showed 1217 lesions, RT-FSE 1137, and SSFSE 1044. This discrepancy arose mainly in patients with multiple sclerosis or small-vessel disease, since with SSFSE we were less able to separate small, adjacent low-contrast lesions than with FSE. Arbitrary movement scores were 36, 25 and zero respectively. There were, however, no clinically significant differences in overall diagnosis between the three techniques. SSFSE thus proved a reliable, fast, accurate method for obtaining T2-weighted images, and may be of particular use in the restless, claustrophobic or obtunded patient.

Intracellular metabolism of a 2'-O-methyl-stabilized ribozyme after uptake by DOTAP transfection or asfree ribozyme. A study by capillary electrophoresis

The uptake and cellular metabolism of a fluorescein-labelled synthetic ribozyme stabilized by 2'- O -methyl modification and a 3' inverted thymidine have been studied, employing capillary gel electrophoresis as a novel and efficient analytical method. After internalization by DOTAP transfection, electrophoretic peaks of intact ribozyme and different degradation products were easily resolved and the amount of intracellular intact ribozyme was quantified to >10(7) molecules/cell at the peak value after 4 h transfection. On further incubation the amount of intracellular intact ribozyme decreased due to both degradation and efflux from the cell. However, even after 48 h incubation there were still >10(6) intact ribozyme molecules/cell. Clear differences both in uptake and in metabolism were seen when comparing DOTAP transfection with the uptake of free ribozyme. Fluorescence microscopy studies indicated that the ribozyme was mainly localized in intracellular granules, probably not accessible to target mRNA. This implies that agents able to release the intact ribozyme from intracellular vesicles into the cytosol should have a considerable potential for increasing the biological effects of synthetic ribozymes.

Early intervention for human immunodeficiency virus in Baltimore Sexually Transmitted Diseases Clinics. Impact on gonorrhea incidence in patients infected with HIV

BACKGROUND

High incidences of sexually transmitted diseases (STD) after posttest counseling have been documented in patients diagnosed with human immunodeficiency virus (HIV) in Baltimore STD clinics. In July 1991, the authors instituted an HIV early intervention program providing long-term medical care and social work services. This study compares the incidence of gonorrhea after post-HIV+ test counseling in patients diagnosed with HIV before and after the institution of the early intervention program.

METHODS

Medical records of a cohort composed of all patients newly diagnosed with HIV and those who underwent posttest counseling for HIV in 1991 to 1993 in two Baltimore STD clinics were reviewed. Patients were offered early intervention medical and social work services. Gonorrhea incidence in this cohort was compared to a historical cohort diagnosed and counseled for post-HIV+ testing in 1988 to 1989 who were not offered early intervention services.

RESULTS

The mean follow-up time was 418 days (range, 26 to 703 days). After post-HIV+ test counseling, gonorrhea developed in 39 of 468 (8.3%) men in the 1989 cohort and 13 of 400 (3.3%) men in the 1991 to 1993 cohort. Controlling for variable length of follow-up, the 1991 to 1993 cohort had a relative risk of 0.442 for the development of gonorrhea during the study period (95% confidence interval, 0.225 to 0.790; P = 0.006). Incident gonorrhea after post-HIV+ test counseling also was associated with a prevalent gonorrhea condition at the time of HIV diagnosis (RR = 3.02; 95% CI, 1.75 to 5.23; P = 0.0001) and failure to return for post-HIV+ test counseling as scheduled (RR = 2.27; 95% CI, 1.17-4.43; P = 0.013). After adjustment for gonorrhea at the time of HIV diagnosis and failure to return for scheduled posttest counseling, the difference in gonorrhea incidence between men in the two cohorts remained statistically significant (RR = 0.494; 95% CI, 0.260 to 0.941; P = 0.032). In comparison, overall gonorrhea rates in Baltimore changed little between 1988 and 1993. No significant difference was found in gonorrhea incidence in women, which may have been the result of active gonorrhea screening during the 1991 to 1993 period, which was not performed in 1988 to 1989.

CONCLUSIONS

Providing clinical care to persons with HIV may facilitate the reduction of high-risk behaviors that lead to incident STDs and further HIV transmission.

The effects of the child and adolescent trial for cardiovascular health intervention on psychosocial determinants of cardiovascular disease risk behavior among third-grade students

PURPOSE

The Child and Adolescent Trial for Cardiovascular Health is a multi-site study of a school-based intervention designed to reduce or prevent the development of risk factors for cardiovascular disease. The goal was to change (or prevent) related risk behaviors and the psychosocial variables that theoretically influence those behaviors.

DESIGN

A nested design was used in which schools served as the primary unit of analysis. Twenty-four schools participated at each of four sites (Austin, San Diego, Minneapolis, and New Orleans). Each site had 10 control and 14 intervention schools.

SETTING AND SUBJECT

Ninety-six schools (with more than 6000 students) in the four sites were randomized to three treatment conditions: control, school-based interventions, and school-plus-family interventions. The sample included approximately equal numbers of males and females and was 67.5% white, 13.9% African-American, 13.9% Hispanic, and 4.7% other.

MEASURES

The psychosocial determinants included improvements in dietary knowledge, intentions, self-efficacy, usual behavior, perceived social reinforcement for healthy food choices, and perceived reinforcement and self-efficacy for physical activity.

RESULTS

The findings indicated significant improvements in all the psychosocial determinants measured (p < .0001). The results revealed a greater impact in the school-plus-family intervention schools for two determinants, usual dietary behavior and intentions to eat heart-healthy foods.

CONCLUSIONS

These findings support theory-based interventions for changing selected psychosocial determinants of cardiovascular disease risk behavior among children.

A simple method to incorporate the effects of an RF shield into RF resonator analysis for MRI applications

A simple but effective method is proposed to incorporate the effects of a radio-frequency (RF) shield into the analysis of RF resonators for magnetic resonance imaging (MRI) applications. It is shown that the method can predict the resonant frequencies of RF resonators within 5% of the measured values.

On the field inhomogeneity of a birdcage coil

A mathematical model is developed for the numerical analysis of birdcage coils constructed using capacitors having different capacitance. With the aid of this model, it is shown that the deviation of some capacitance introduced by tune, balance, and drive mechanisms can cause inhomogeneity in the B1 field produced by the coil. Useful curves and formulae are developed to provide a guideline for the design of birdcage coils.

Presentation, diagnosis and treatment of renal abscesses: 1972-1988

We reviewed 61 consecutive patients with renal abscesses who were treated between 1972 and 1988 to determine whether the patient characteristics and mortality differed from those of patients treated during the preceding 2 decades. The results demonstrate that the predisposing conditions, symptomatology, abnormal physical findings, abnormal laboratory results, abnormal radiographic findings and infecting organisms of patients with renal abscesses have not changed during the last 40 years. Ultrasonography and computerized tomography, which became available in the 1970s, identified 35 of 38 (92%) and 23 of 24 (96%) abscesses, respectively. In 57 cases (97%) the abscess was drained and the patients survived. In 4 cases the abscess escaped clinical detection and contributed to patient death. The marked improvement of survival among patients with renal abscesses during the last 2 decades is attributable to improved diagnostic precision and, probably, improved antimicrobial therapy and supportive care.

A regional approach to entry-level critical care education

The education and training of the novice critical care nurse place a constant financial demand on many Puget Sound area hospitals. Critical care educators from this area, committed to cost-effective, high-quality education, enhanced through precepted clinical experience, assessed the need for a collaborative approach among institutions. Jointly we have successfully planned, implemented, and evaluated a cooperative educational program. To date, the program has served to reduce the costs of preparing the RN entering critical care in the Puget Sound area. Application of principles of adult education, timely application of theory to practice, and expansion of the professional role of critical care clinical nurse specialists and educators have also been recognized as outcomes of the CCEC.

Early pregnancy factor: large scale isolation of rosette inhibition test-active polypeptides from ovine placental extracts

Protocols are described for the isolation of substantial (mg) amounts of a rosette inhibition test (RIT)-active polypeptide fraction from ovine placental extracts. The main component of the preparation is a 12K polypeptide which contains a highly reactive thiol group. Oxidation may occur during isolation with the result that the final preparation is a mixture of the 12K polypeptide and a 25K disulphide linked dimer. The highly reactive thiol group was found to be directly involved in activity expression since gentle reduction followed by iodoacetylation resulted in a complete loss of activity. Antisera were prepared and the antibodies removed all the RIT activity from fresh ovine placental extracts, indicating that molecules related to those in the isolated preparation were responsible for all the activity in crude extracts. The antibodies also removed all the RIT activity from ovine and murine pregnancy sera, obtained both before and after implantation. Since EPF is defined as an RIT activity detected in pregnancy serum, these results establish that EPF activity is due to molecules similar to those isolated from the placental extracts. The availability of the preparative protocol and antibodies should hasten the biochemical definition of the EPF phenomenon.

Platelet-activating factor induces the expression of early pregnancy factor activity in female mice

When synthetic platelet-activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) was injected into mature female mice during dioestrus, pro-oestrus or oestrus, it induced the expression of early pregnancy factor (EPF) activity in the sera of these animals within 1 h of injection. The sera of similarly injected males, metoestrous or immature females did not display any EPF activity. The results suggest that embryo-derived PAF may be the ovum factor responsible for triggering the generation of serum EPF activity during the preimplantation stages of pregnancy.