Direct Determination of Fission-Barrier Heights Using Light-Ion Transfer in Inverse Kinematics.

We demonstrate a new technique for obtaining fission data for nuclei away from ß stability. These types of data are pertinent to the astrophysical r process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of ^{239}U has been determined via the ^{238}U(d,pf) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

Quenching of Single-Particle Strength in A=15 Nuclei.

Absolute cross sections for the addition of s- and d-wave neutrons to ^{14}C and ^{14}N have been determined simultaneously via the (d,p) reaction at 10 MeV/u. The difference between the neutron and proton separation energies, ΔS, is around -20 MeV for the ^{14}C+n system and +8 MeV for ^{14}N+n. The population of the 1s_{1/2} and 0d_{5/2} orbitals for both systems is reduced by a factor of approximately 0.5 compared with the independent single-particle model, or about 0.6 when compared with the shell model. This finding strongly contrasts with results deduced from intermediate-energy knockout reactions between similar nuclei on targets of ^{9}Be and ^{12}C. The simultaneous technique used removes many systematic uncertainties.

First Exploration of Neutron Shell Structure below Lead and beyond N=126.

The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r process in producing nuclei heavier than A∼190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in ^{207}Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. The radioactive beam of ^{206}Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of ^{207}Hg marks a first step in improving our understanding of the relevant structural properties of nuclei involved in a key part of the path of the r process.

A multicentre assessment of prostate MRI quality and compliance with UK and international standards.

AIM: To assess prostate magnetic resonance imaging (MRI) image quality and compliance with technical standards between centres in the South West region of the UK. MATERIALS AND METHODS: Fifteen imaging sites in the region submitted seven consecutive anonymised MRI studies. These were assessed by two experienced radiologists in consensus. Overall, subjective image quality for T2-weighted imaging (T2W), diffusion weighted imaging (DWI), and dynamic contrast enhancement (DCE) was scored on a five-point Likert scale. Five additional quality parameters were also assessed visually, including image noise, motion, artefact, and distortion. The degree of compliance by each site with 21 published technical standards was also assessed. RESULTS: Ninety-four MRI examinations were reviewed from across all sites (mean 6.3 scans per site, range 5-7). Mean compliance with technical standards was 63% (range 38-86%). Forty-seven percent of sites did not perform DCE. One site used a 3 T scanner. The percentage of patients with overall quality scores of ≥3 (diagnostically acceptable) were 68% for T2W, 81% for DWI, and 60% for both T2W and DWI. Ninety-three percent of the 45 patients who underwent DCE had diagnostically acceptable studies. By scanner age, the percentage of patients with diagnostically acceptable T2W scores was 53% for scanners ≥7 years and 80% when <7 years (p=0.006). Comparing individual sites, the mean overall quality scores were 2.9 (range 2.2-4.2) for T2W, 3.2 (1.8-4.7) for DWI, and 3.4 (2.5-4.7) for DCE. CONCLUSION: There is wide variation in compliance with recognised technical standards and image quality across sites. If MRI is to replace biopsy in selected low-risk patients, improvements in image quality may be required.

Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

Quenching of cross sections in nucleon transfer reactions.

Cross sections for proton knockout observed in (e,e'p) reactions are apparently quenched by a factor of ∼0.5, an effect attributed to short-range correlations between nucleons. Here we demonstrate that such quenching is not restricted to proton knockout, but a more general phenomenon associated with any nucleon transfer. Measurements of absolute cross sections on a number of targets between 16O and 208Pb were analyzed in a consistent way, with the cross sections reduced to spectroscopic factors through the distorted-wave Born approximation with global optical potentials. Across the 124 cases analyzed here, induced by various proton- and neutron-transfer reactions and with angular momentum transfer ℓ=0-7, the results are consistent with a quenching factor of 0.55. This is an apparently uniform quenching of single-particle motion in the nuclear medium. The effect is seen not only in (d,p) reactions but also in reactions with A=3 and 4 projectiles, when realistic wave functions are used for the projectiles.

Test of sum rules in nucleon transfer reactions.

The quantitative consistency of nucleon transfer reactions as a probe of the occupancy of valence orbits in nuclei is tested. Neutron-adding, neutron-removal, and proton-adding transfer reactions were measured on the four stable even Ni isotopes, with particular attention to the cross section determinations. The data were analyzed consistently in terms of the distorted wave Born approximation to yield spectroscopic factors. Valence-orbit occupancies were extracted, utilizing the Macfarlane-French sum rules. The deduced occupancies are consistent with the changing number of valence neutrons, as are the vacancies for protons, both at the level of <5%. While there has been some debate regarding the true "observability" of spectroscopic factors, the present results indicate that empirically they yield self-consistent results.

First experiment with HELIOS: the structure of 13B.

A first experiment is reported that makes use of a new kind of spectrometer uniquely suited to the study of reactions with radioactive beams in inverse kinematics, the helical orbit spectrometer, HELIOS. The properties of some low-lying states in the neutron-rich N=8 nucleus 13B were studied with good resolution. From the measured angular distributions of the (d,p) reaction and the relative spectroscopic factors, spin and configuration assignments of the first- and third-excited states of this nucleus can be constrained.

MRI appearances of acute idiopathic scrotal oedema in an adult.

Acute idiopathic scrotal oedema is an uncommon cause of acute painless scrotal swelling that is usually seen in children. Traditionally, ultrasound has been used to help establish the diagnosis in the appropriate clinical setting. We report the MRI appearances of acute idiopathic scrotal oedema in a 51-year-old male with associated involvement of the penis.

The integration of transabdominal ultrasound simulators into an ultrasound curriculum.

INTRODUCTION: Simulation is increasingly used throughout medicine. Within ultrasound, simulators are more established for learning transvaginal and interventional procedures. The use of modern high-fidelity transabdominal simulators is increasing, particularly in centres with large trainee numbers. There is no current literature on the value of these simulators in gaining competence in abdominal ultrasound. The aim was to investigate the impact of a new ultrasound curriculum, incorporating transabdominal simulators into the first year of training in a UK radiology academy. METHODS: The simulator group included 13 trainees. The preceding cohort of 15 trainees was the control group. After 10 months, a clinical assessment was performed to assess whether the new curriculum resulted in improved ultrasound skills. Questionnaires were designed to explore the acceptability of simulation training and whether it had any impact on confidence levels. RESULTS: Trainees who had received simulator-enriched training scored higher in an objective clinical ultrasound assessment, which was statistically significant (p = 0.0463). End confidence scores for obtaining diagnostic images and demonstrating pathology were also higher in the simulation group. All trainees stated that transabdominal simulator training was useful in early training. CONCLUSIONS: This initial study shows that embedded into a curriculum, transabdominal ultrasound simulators are an acceptable training method that can result in improved ultrasound skills and higher confidence levels. Using simulators early in training could allow trainees to master the basics, improve their confidence, enabling them to get more educational value from clinical ultrasound experience while reducing the impact of training on service provision.

Equilibrium folding properties of the yeast prion protein determinant Ure2.

The yeast non-Mendelian factor [URE3] propagates by a prion-like mechanism, involving aggregation of the chromosomally encoded protein Ure2. The [URE3] phenotype is equivalent to loss of function of Ure2, a protein involved in regulation of nitrogen metabolism. The prion-like behaviour of Ure2 in vivo is dependent on the first 65 amino acid residues of its N-terminal region which contains a highly repetitive sequence rich in asparagine. This region has been termed the prion-determining domain (PrD). Removal of as little as residues 2-20 of the protein is sufficient to prevent occurrence of the [URE3] phenotype. Removal of the PrD does not affect the regulatory activity of Ure2. The C-terminal portion of the protein has homology to glutathione S -transferases, which are dimeric proteins. We have produced the Ure2 protein to high yield in Escherichia coli from a synthetic gene. The recombinant purified protein is shown to be a dimer. The stability, folding and oligomeric state of Ure2 and a series of N-terminally truncated or deleted variants were studied and compared. The stability of Ure2, DeltaGD-N, H2O, determined by chemical denaturation and monitored by fluorescence, is 12.1(+/-0.4) kcal mol-1at 25 degrees C and pH 8.4. A range of structural probes show a single, coincident unfolding transition, which is invariant over a 550-fold change in protein concentration. The stability is the same within error for Ure2 variants lacking all or part of the prion-determining domain. The data indicate that in the folded protein the PrD is in an unstructured conformation and does not form specific intra- or intermolecular interactions at micromolar protein concentrations. This suggests that the C-terminal domain may stabilise the PrD against prion formation by steric means, and implies that the PrD does not induce prion formation by altering the thermodynamic stability of the folded protein.

Psychiatric aftercare: identified needs versus referral patterns.

Although psychiatric aftercare has received increased attention, little is known about patients' needs for community resources or about predischarge referral patterns. The authors interviewed hospital staff about needs and referrals for each of 747 patients about to be discharged. Nearly all patients had needs in the medical/therapeutic area and most received referrals. In three other nonmedical aftercare areas needs were identified for a much lower percentage of patients, and identified need was two to three times greater than referrals made. The authors discuss the implications of these findings for the provision of aftercare services.

A controlled study of self-help intervention for widows.

The authors conducted a 2-year study of postbereavement adaptation in 162 widows. Sixty-eight were paired with a widow contact who provided emotional support and practical assistance. The differences between the women receiving intervention and the controls at 6, 12, and 24 months after bereavement suggested that those receiving intervention followed the same general course of adaptation as control subjects but that the rate of achieving landmark stages was accelerated for the intervention group. The Goldberg General Health Questionnaire and two indices derived from the study questionnaire confirmed the hypothesized "pathway" of adaptation" through intra- and interpersonal adaptation to resolution of overall distress and the effectiveness of the intervention.

Predictors and correlates of adaptation to conjugal bereavement.

The authors interviewed 162 widows 1, 6, 12, and 24 months after bereavement to determine which sociodemographic, prebereavement, and response variables and circumstances of the husband's death were related to distress level, as measured by the General Health Questionnaire (GHQ). The most important variable associated with high distress at 1 month was the woman's perception that she was seeing old friends less than before her husband's death. At 2 years it was possible to predict distress levels with 86% accuracy by means of a multiple regression analysis using 10 variables, including 1-month GHQ score, short final illness of the husband, and satisfaction with available help.

Marrow versus infection in the Charcot joint: indium-111 leukocyte and technetium-99m sulfur colloid scintigraphy.

UNLABELLED: This study evaluated the role of combined leukocyte/marrow scintigraphy in the assessment of the neuropathic or Charcot joint. METHODS: Seventeen patients with (111)In-labeled leukocyte accumulation in 20 radiographically confirmed Charcot joints underwent 99mTc-sulfur colloid marrow scintigraphy. Studies demonstrating labeled leukocyte accumulation without corresponding activity on marrow images were classified as positive for osteomyelitis. Six of the patients also underwent three-phase bone scintigraphy. Bone scans were interpreted as positive for osteomyelitis when focal hyperperfusion, focal hyperemia and focal bony uptake on delayed images were present. Bone images were also interpreted together with labeled leukocyte images using two different criteria for a positive study. One criterion was the presence of labeled leukocyte activity in a region demonstrating abnormal activity on the bone scan, which was more intense than adjacent marrow activity or marrow activity in the corresponding region of the contralateral foot. The second criterion was either a spatially incongruent distribution of the two tracers or hyperintense activity on the leukocyte study, as compared to the bone scan. RESULTS: Leukocyte/marrow studies were positive for osteomyelitis in 4 of the 20 neuropathic joints. Osteomyelitis was present in three of the four joints, whereas in the fourth, infection was confined to overlying soft tissues. None of the 16 neuropathic joints with negative leukocyte/marrow scans were infected. In one patient who underwent below-the-knee amputation, histological analysis confirmed the presence of hematopoietically active marrow corresponding to areas of congruent activity on the leukocyte and marrow images. Three-phase bone scintigraphy was positive in all six neuropathic joints studied; osteomyelitis was present in two of them. Using the first criterion, leukocyte/bone imaging was also positive in all six. Using the second criterion, leukocyte/bone imaging was positive in the two infected neuropathic joints, as well as in three uninfected ones. Leukocyte/marrow scintigraphy was positive in both infected joints and negative in the four without infection. CONCLUSION: Labeled leukocyte accumulation in the uninfected Charcot joint does occur and is related, at least in part, to hematopoietically active marrow. Leukocyte/marrow scintigraphy is a reliable way to differentiate between marrow and infection as the cause of labeled leukocyte accumulation in the neuropathic joint and, in this series, was superior to both three-phase bone scintigraphy and combined leukocyte/bone scintigraphy.

Differential effect of zinc on teratogen-induced inhibition of pinocytosis by cultured rat yolk sac.

Pinocytosis as measured by the uptake of 125I labelled PVP by the isolated cultured day 12 rat yolk sac was observed to be linear over a 4 h incubation period and to proceed at a rate of approximately 2.5 microliters/mg protein/h. Cadmium, anti-visceral yolk sac antibody (AVYS) and trypan blue all inhibited pinocytosis in a concentration-dependent fashion when added to the culture medium, although at low concentrations trypan blue was slightly stimulatory. The effect of zinc on the inhibition of pinocytosis by these three teratogens was studied. It was observed that zinc ameliorated the inhibitory effects of cadmium and AVYS, but had no effect on inhibition by trypan blue. These results indicate that the previously demonstrated protective action of zinc against cadmium-induced yolk sac dysfunction is not specific to that agent but extends to inhibition of pinocytosis by AVYS, and further suggest that, because of its refractoriness to zinc, trypan blue-induced inhibition of pinocytosis by yolk sac occurs by a mechanism different from that effected by cadmium and AVYS.

Failure of zinc to prevent dysmorphogenesis of cultured rat conceptuses by anti-yolk sac antiserum.

Day 10 rat conceptuses were cultured for 48h in the presence of either cadmium or anti-visceral yolk sac antiserum (AVYS). Cadmium was embryotoxic at concentrations exceeding 0.25 micrograms/ml whilst AVYS caused embryonic dysmorphogenesis, particularly affecting the optic vesicles, at concentrations of 2 microliters/ml and above. The effect of pretreatment with zinc on embryotoxicity caused by cadmium or AVYS was studied. Zinc ameliorated the effects of cadmium but had no effect on AVYS-induced embryonic abnormalities. In a second set of experiments inhibition of 125I-labelled PVP uptake by the yolk sac of cultured whole conceptuses was studied. Cadmium and AVYS both inhibited uptake compared to control cultures. Zinc again ameliorated the effect of cadmium but had no action against AVYS-induced inhibition. These results are in contrast to our previous findings using isolated cultured yolk sacs in which zinc ameliorated the inhibitory effects on 125I-labelled PVP uptake of both cadmium and AVYS. These data show that in experiments using the isolated cultured yolk sac and the intact cultured conceptus, a qualitatively different response in yolk sac behaviour is observed under similar experimental conditions.

Help-seeking behaviour of depressed students.

Depression, the most common form of psychological distress among university students, is often serious enough to warrant professional help but only a minority of depressed students seek formal help. This paper reports on the characteristics which differentiate two groups of depressed students--the help-seekers from the non-help-seekers. A university psychiatric clinic population (N = 183) was compared with a non-clinic sample (N = 55). Data about depressive symptoms, social supports, the use of medical, psychiatric and other helping services, sources of referral and the usual demographic and sociocultural information were obtained. The Beck Depression Inventory was used as the measure of depression. Severity of depression was the single most important predictor of use of the psychiatric service. In addition, being female was also an important predictor. After controlling for severity and sex, the demographic factors which distinguished help-seekers from non-help-seekers were as follows: The help-seekers were more likely to be graduate students, older, living away from family and/or to use a non-psychiatric physician. Contrary to expectation, having a confidant was not related to help-seeking, suggesting that the presence of a confidant may be preventive but does not necessarily decrease the need for professional help once a student has become depressed. A depressed student's decision to seek help may be influenced by four factors: the severity of the problem; the individual's propensity to seek help; the availability of alternate resources; and the accessibility of psychiatric services. The findings are discussed in the light of these factors.

Evidence that suramin and aurothiomalate are teratogenic in rat by disturbing yolk sac-mediated embryonic protein nutrition.

Suramin (250 mg/kg) and sodium aurothiomalate (100 mg/kg) both induced congenital malformations in the offspring following treatment of pregnant rats at either 8.5 or 9.5 days of gestation. Conceptuses from 9.5-day pregnant rats were cultured for 48 h in homologous serum to which either suramin or sodium aurothiomalate was added for the final 6 h. The presence of suramin up to 5 mg/ml had no effect on the protein content of yolk sacs at harvesting, but at 10 mg/ml caused a significant decrease. In contrast sodium aurothiomalate increased the protein content of yolk sacs at harvesting, in a concentration-dependent manner up to 100 micrograms/ml. Neither suramin nor sodium aurothiomalate significantly affected embryo protein content. When 125I-labelled polyvinylpyrrolidone was added to the culture serum for the final 6 h of culture, radioactivity was found in the yolk sac at harvesting, but not in the embryo. When suramin (2-10 mg/ml) was present for the final 6 h of culture, the quantity of radioactivity measured in the yolk sac at harvesting was significantly decreased in a concentration-dependent manner. No radioactivity was detected in the embryos. Sodium aurothiomalate had no effect on the uptake of 125I-labelled polyvinylpyrrolidone. When rat serum whose proteins were labelled with [3H]leucine was used as culture medium, radioactivity was found in the conceptus (both yolk sac and embryo) at harvesting. Suramin (5 mg/ml), present for the final or penultimate 6 h, significantly decreased the uptake of radioactivity into conceptuses and caused a significant increase in the proportion of the captured radiolabel that was associated with the yolk sac. Sodium aurothiomalate (25 or 500 micrograms/ml) had no effect on the total uptake of radio-label but caused a significant increase in the proportion of total radioactivity captured that was associated with the yolk sac. These data indicate that suramin, by interfering with both the uptake and intralysosomal digestion of protein, and sodium aurothiomalate, by inhibiting digestion of captured protein, disturb the normal pathway of yolk sac-mediated protein utilization with a consequent diminution of the supply of amino acids to the conceptus. The effects of suramin are seen only at high concentration, those of sodium aurothiomalate at much lower concentrations. It is likely that the two drugs exert their teratogenic action by their effects on the yolk sac nutritional pathway with resultant amino acid deprivation of the conceptus at a critical stage of development.

Anti-kidney antibody teratogenesis: evidence for a direct action on the rat conceptus by a mechanism involving the yolk sac.

IgG from anti-rat kidney antiserum (anti-K) was added to 48-h cultures of 9.5-day whole rat conceptuses. At concentrations of 25 micrograms/ml and above, dysmorphogenesis of embryos (optic vesicle defects) was observed. Significant embryonic growth retardation was apparent at 75 micrograms/ml and above. Other abnormalities (neural tube defects, deficits in axial rotation, reduced somite numbers) were seen at 100 and 150 micrograms/ml. In separate experiments, anti-K inhibited pinocytosis of 125I-polyvinylpyrrolidone by isolated yolk sacs. All of these effects of anti-K are similar to those produced by anti-visceral yolk sac antiserum suggesting a similar mechanism of teratogenic action, namely interference with yolk-sac-mediated embryotrophic nutrition.