An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe.

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.

Altered bone development in a mouse model of peripheral sensory nerve inactivation.

OBJECTIVES: The present study sought to determine the effects of decreased peripheral sensory nerve function on skeletal development and bone metabolism in mice. METHODS: C57BL/6 neonatal mice were treated with capsaicin to induce peripheral sensory nerve degeneration, and compared to vehicle-treated controls at 4, 8 and 12 weeks of age. Changes in bone structure were assessed using micro-computed tomography, mechanical properties and fracture resistance were assessed using three-point bending of radii, and bone turnover was assessed using dynamic histomorphometry and serum biomarkers. RESULTS: Capsaicin treatment resulted in small but significant decreases in bone structure, particularly affecting trabecular bone. Capsaicin-treated mice exhibited lower trabecular thickness at the femoral metaphysis and L5 vertebral body compared with vehicle-treated mice. However, capsaicin- and vehicle-treated mice had similar mechanical properties and bone turnover rates. CONCLUSION: Neonatal capsaicin treatment affected trabecular bone during development; however these small changes may not be meaningful with respect to bone strength under normal loading conditions. It is possible that capsaicin-sensitive neurons may be more important for bone under stress conditions such as increased mechanical loading or injury. Future studies will investigate this potential role of peripheral sensory nerves in bone adaptation.

Near-threshold production of the multistrange Xi- hyperon.

The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.

Comparison of source images for protons, pi-'s, and lambda's in 6A GeV Au+Au collisions.

Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.

Longitudinal flow of protons from (2-8)A GeV central Au+Au collisions.

Rapidity distributions of protons from central 197Au+197Au collisions measured by the E895 Collaboration in the energy range from (2-8)A GeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, (L), as a function of the logarithm of beam energy.

Model-independent source imaging using two-pion correlations in (2 to 8)a GeV Au+Au collisions.

We report a particle source imaging analysis based on two-pion correlations in high multiplicity Au+Au collisions at beam energies between 2A and 8A GeV. We apply the imaging technique introduced by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. The extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional Hanburg-Brown-Twiss analysis.

Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions.

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.

Bombarding energy dependence of pi(-) interferometry at the brookhaven AGS

We present the first excitation function of pi(-) intensity interferometry at Alternating Gradient Synchrotron (AGS) energies (2-8 A GeV). The sensitivity of the multidimensional correlation functions to the geometry and dynamics of the pion-emitting system provides a stringent test of transport models of heavy ion collisions. Detailed comparisons with a realistic transport model, both with and without an explicit nuclear mean field, suggest that the beam energy evolution in the reaction dynamics is different in the model than in the data. A significantly increased pi(-) emission time scale, which has been suggested as a signal of the onset of the transition to quark-gluon plasma, is not observed.

Antiflow of K(0)(s) mesons in 6A GeV Au + Au collisions

We have measured the sideward flow of neutral strange ( K(0)(s)) mesons in 6A GeV Au+Au collisions. A prominent antiflow signal is observed for an impact parameter range ( b less, similar7 fm) which spans central and midcentral events. Since the K(0)(s) scattering cross section is relatively small in nuclear matter, this observation suggests that the in-medium kaon vector potential plays an important role in high density nuclear matter.

Sideward flow in Au+Au collisions between 2A and 8A GeV

Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au+Au collisions at beam energies of 2A, 4A, 6A, and 8A GeV are presented in the form of in-plane transverse momentum and the first Fourier coefficient of azimuthal anisotropy v(1). These measurements indicate a smooth variation of sideward flow as a function of beam energy. The data are compared with four nuclear transport models which have an orientation towards this energy range. All four exhibit some qualitative trends similar to those found in the data, although none show a consistent pattern of agreement within experimental uncertainties.

Analysis of health-related quality of life and muscle impairment in individuals with amyotrophic lateral sclerosis using the medical outcome survey and the Tufts Quantitative Neuromuscular Exam.

OBJECTIVE: The Tufts Quantitative Neuromuscular Exam (TQNE) is commonly used to assess the rate of disease progression in individuals with amyotrophic lateral sclerosis (ALS). The Medical Outcome Study Short Form (SF-36) is a general method to assess health-related quality of life (HRQL). This study examined the relationship between the TQNE and SF-36, established the reliability and responsiveness of each, and contrasted the HRQL between individuals with ALS and the general population. DESIGN: Subjects (31) completed the SF-36 and TQNE within 1 week to determine reliability. Subjects (17) also completed both the TQNE and SF-36 each month for 1 year after diagnosis of ALS to establish the relationship between the two assessment tools. SETTING: A primary care university teaching hospital. PATIENTS: Thirty-one subjects with an age range of 27 to 76 years (mean 59.1, SD 10.32), recently diagnosed with ALS. RESULTS: Each test was highly reliable and responsive. The intraclass correlations (2, 1) were consistently higher for the TQNE (.93 to .98) than for the SF-36 (.57 to .90). Changes in physical function were correlated to changes in lower extremity force megascores (.48). CONCLUSION: Both the TQNE and the SF-36 are reliable and responsive and appear important in characterization of patient status after ALS is diagnosed.

Ischemic stroke in young adults. Experience in 329 patients enrolled in the Iowa Registry of stroke in young adults.

OBJECTIVES: To describe the likely causes of ischemic stroke in a population of young adults and to report the influence of strict algorithms on the diagnosis of the likely cause of stroke in this cohort. DESIGN: Between July 1, 1977, and January 1, 1993, we registered 329 young adults with ischemic stroke in our registry. Diagnostic studies were selected on a case-by-case basis. Presumed causes of stroke were determined using clinical information and the results of diagnostic tests. In each case, a second causative diagnosis was made using the criteria developed for a large clinical trial. SETTING: Patients referred to the Division of Cerebrovascular Diseases in the Department of Neurology at the University of Iowa Hospitals and Clinics, Iowa City, by physicians in Iowa and adjacent states. PATIENTS: Three hundred twenty-nine young adults (182 men and 147 women) aged 15 to 45 years with ischemic stroke; 102 persons, 48 men and 54 women, were aged 30 years or younger. RESULTS: Cerebral arteriography was performed in 227 cases, and the findings were abnormal in 146. Transthoracic echocardiography revealed abnormalities in 82 of 221 patients examined. We identified approximately 60 different disorders that were presumed to be the cause of stroke. There were no major changes in the frequency of subtype diagnoses between the first 144 patients and the subsequent 185. Use of strict diagnostic criteria increased the number of cases of stroke of undetermined etiology (from 45 to 113), and the number attributed to large artery atherosclerosis declined from 71 to 32. CONCLUSIONS: The causes of ischemic stroke in young adults are numerous. Because treatment options in this group are influenced by a presumed cause, an evaluation on a case-by-case basis is warranted. Our experience suggests that a likely cause will be detected in most cases and that a regimented battery of tests may not be required. If strict diagnostic criteria are used, the diagnosis of stroke of undetermined etiology considerably increases. While such strict criteria are important in clinical trials that test new interventions, the value of the application of such methodologies to an unusual population, such as stroke in young adults, needs clarification. In particular, the usefulness of categorizing a stroke as undetermined when two or more possible causes are identified needs to be explored.

Prognosis of young adults with ischemic stroke. A long-term follow-up study assessing recurrent vascular events and functional outcome in the Iowa Registry of Stroke in Young Adults.

BACKGROUND AND PURPOSE: Information about the long-term prognosis of young adults with ischemic stroke is limited. Therefore, we performed a follow-up assessment of 296 patients with ischemic stroke who are enrolled in the Iowa Registry of Stroke in Young Adults. We studied young adults (age, 15 to 45 years) who were referred to a tertiary medical center for management of ischemic stroke between July 1, 1977, and January 1, 1992. METHODS: Follow-up assessments were performed by means of questionnaires, examinations, telephone interviews, review of medical records, and reports from personal physicians. Data about risk factors, coincident medical diseases, etiology of stroke, treatment, recurrent stroke, other vascular events, and deaths were collected. Outcomes were rated with the Glasgow Outcome Scale, Barthel Index, National Institutes of Health stroke scale, and the Mini-Mental State Examination. Quality of life was assessed with the SF-36 Health Status questionnaire. RESULTS: Follow-up information about the status of 10 patients was limited except that they were alive. Twenty-one patients (7%) died as the result of their initial stroke, and another 40 patients (14%) died during a mean follow-up of 6.0 years. None of the patients aged 25 years or younger at the time of stroke died during follow-up. Mortality was significantly higher among patients who had a stroke secondary to large-vessel stroke and it was significantly lower in patients with stroke of unknown etiology than in patients with stroke of other causes (relative risk [RR], 1.7; 95% confidence limits [CL], 1.0 to 2.7; and RR, 0.1; CL, 0 to 0.6; respectively). Recurrent strokes occurred in 23 patients (9%) and were fatal in 9. Another 37 patients were treated by a cardiologist during follow-up; 3 had had a myocardial infarct. Fourteen additional patients needed major vascular surgery. Outcomes with the Glasgow Outcome Scale and Barthel Index were generally favorable. Still, only 49% of patients were still alive, were not disabled, had not suffered from recurrent vascular events, or had not undergone major vascular surgery. Only 42% of survivors had returned to work. A majority of survivors reported emotional, social, or physical residuals that lessened the quality of life. CONCLUSIONS: The risks of recurrent vascular events in young adults who have had ischemic stroke are considerable. In addition, a majority of survivors will have residual emotional, social, or physical impairments that hamper employment or lower the quality of life. Further research on the quality of life for young adults who survive stroke is needed.