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The 12C(16O,12C 12C)α reaction has been measured at Ebeam=75 MeV, for 24Mg emission from 0 to 180 degrees. This energy coincides with an enhancement observed in earlier measurements of the 12C+16O system. The properties of the angular correlations of the reaction products are found to be consistent with a resonance in 28Si at Ex=48.9 MeV, with spin J=17±1. The decay properties of the states in 24Mg, populated following α-decay of the resonance, suggest that the state in 28Si possesses a triaxial structure linked to a (sd)8(fp)4 configuration.

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

A multi-channel data acquisition system has been commissioned for the Charissa “MEGHA” detector array. It is designed to read multiparameter events where there are many potential channels (320) but where only a fraction of these are active in any typical event. Custom-built pre- and main amplifiers process the amplitude (energy) signal from each detector and the system records both amplitude and time of arrival for each signal within an event. The signal amplitude is converted to time using the standard Wilkinson technique and then combined with its time of arrival into a single time trace. These traces are converted by multi-hit TDCs, which only convert the active channels and thus reduce the processing load. Additional custom-built CAMAC modules organise the TDC output into a suitable form for storage and transmission to a network of processor terminals over standard ethernet. This paper presents a description of the data acquisition system from preamplifier through to final storage in a VME-based system and subsequent distribution to a network of Sun terminals over ethernet. The system performance is illustrated with results from heavy-ion elastic scattering recorded with position sensitive strip detectors.

The breakup of 12Be into 6He+6He and 4He+8He has been studied using a 378 MeV 12Be beam inelastically excited by 12C and (CH2)n targets. The measurements indicate that breakup occurs from rotational states in the 10 to 25 MeV excitation energy interval, with spins in the range of 4ħ to 8ħ. The inferred moment of inertia is consistent with the cluster decay of an exotic molecular structure in 12Be, which may be associated with an α-4n-α cluster configuration.

We report on new experimental data which reveal high spin resonances in 12 C+ 12 C scattering. We have measured excitation functions for the 12 C [ 12 C, 12 C(3 1 − ) + 12 C(3 1 − )] reaction over the centre of mass energy range E c.m. =31 to 45 MeV. Resonances have been observed at E c.m. =32.5, 37.5 and 43 MeV. Detailed angular correlation measurements have been performed at the energy corresponding to the peak of each resonance. From an analysis of the angular correlations we suggest a dominant angular momentum of J =22 at the highest energy. We interpret the results in terms of an α cluster model of superdeformed states in 24 Mg.

The reaction has been studied to investigate a possible overlap with the scattering resonances observed in the and channels. Evidence for the break-up of was observed, but the yield was too low to be able to associate it with specific resonances.

A study has been made of the 12C(16O,12C12C) α reaction between the centre of mass energies of 28.3 to 36.8 MeV. A number of resonances in 28Si have been observed for final channels leading to the unbound 10.35, 11.09 and 14.82 MeV states in 16O. At two energies associated with previously observed resonances, the angular correlations of the exit channel particles have been analysed to measure the dominant angular momentum of the 28Si compound nucleus. Additional data were acquired at two off-resonance energies for comparison. Using an essentially model independent analysis, the values obtained were all in the region of 19–21 h , and are comparable with the grazing angular momentum in the entrance channel. The results are relevant to recent theoretical predictions of planar α-cluster structures in 28Si and are discussed in the context of the model predictions.

A study of the $^{12}\mathrm{C}$${(}^{24}$Mg${,}^{16}$O $^{16}\mathrm{O}$${)}^{4}$He reaction has revealed $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ breakup from states in $^{32}\mathrm{S}$ in the excitation region ranging from 32 to 38 MeV. The spins of the states near 33, 35, and 38 MeV of excitation, obtained from angular correlations, are measured to be (${10}^{+}$ or ${12}^{+}$), (${12}^{+}$ or ${14}^{+}$), and (${14}^{+}$ or ${16}^{+}$), respectively. These may be interpreted as arising from a highly deformed band in $^{32}\mathrm{S}$. \textcopyright{} 1996 The American Physical Society.

The reaction {sup 12}C({sup 16}O,7{alpha}) has been studied over the center-of-mass energy range from 37.7 MeV to 51.4 MeV, in a search for evidence for a 7-{alpha} chain state in {sup 28}Si. The yields of the {sup 12}C(0{sub 2}{sup +})-{sup 12}C(0{sub 2}{sup +})-{alpha} and {sup 12}C(0{sub 2}{sup +})-{sup 8}Be-{sup 8}Be final states agree broadly with previous measurements but contain no structure, indicating that a {sup 28}Si chain state is probably not being observed. The yields for the inelastic scattering reaction {sup 12}C+{sup 16}O decaying to other excited states in {sup 12}C and {sup 16}O have also been studied. They also contain no gross structure.

The $^{12}\mathrm{C}$${(}^{16}$O,4\ensuremath{\alpha}${)}^{12}$C reaction has been studied at a beam energy of 99 MeV. The data indicate the existence of sequential decays in the form $^{16}\mathrm{O}^{\mathrm{*}}$\ensuremath{\rightarrow}4\ensuremath{\alpha} in the exit channel. The excitation energy of the $^{16}\mathrm{O}$ nucleus and the nature of the partition process leading to the 4\ensuremath{\alpha} final state, has been reconstructed from the kinematics of the \ensuremath{\alpha} particles. States have been observed at excitation energies of 17.1, 17.5, 18.0, 18.7, 19.3, and 21.4 MeV which decay into $^{8}\mathrm{Be}$${+}^{8}$Be, $^{12}\mathrm{C}$(7.65 MeV, ${0}_{2}^{+}$)+\ensuremath{\alpha} and $^{12}\mathrm{C}$(9.64 MeV, ${3}^{\mathrm{\ensuremath{-}}}$)+\ensuremath{\alpha}. Relative partial decay widths for these three channels have been measured. Angular correlation measurements have been used to deduce the spins of several of the observed states, and indicate spins in the range 2 to 6\ensuremath{\Elzxh}.

A high resoution measurement of the $^{12}\mathrm{C}$${(}^{24}$Mg${,}^{12}$${\mathrm{C}}^{12}$C${)}^{12}$C reaction shows that the $^{24}\mathrm{Mg}$ breakup states have widths in the region of 100 to 250 keV. The energies, widths, and spins of these states are seen to be consistent with those of the $^{12}\mathrm{C}$ ${+}^{12}$C quasimolecular resonances which occur in the same region of excitation in the $^{24}\mathrm{Mg}$ nucleus.

A hybrid detector system has been constructed consisting of a gas filled ionization chamber and a large area silicon semiconductor strip detector within the same gas volume. The construction and operation of these detectors is described, together with a brief description of the electronics and data acquisition system used in cluster breakup studies. The techniques for software correction and gain matching of the detector energy signals are described and results are presented for the resolutions in energy, position and time. In a typical application, elements up to Ca are easily resolved and the positions of individual ions are measured with a resolution of

An analysis of the $^{12}\mathrm{C}$($^{12}\mathrm{C}$,$3\ensuremath{\alpha}$)$^{12}\mathrm{C}$ reaction was made at beam energies between 82 and 106 MeV. Decays to both the ground state and the excited states of $^{8}\mathrm{Be}$ were isolated, allowing states of different characters to be identified. In particular, evidence was found for a previously observed state at 11.16 MeV. An analysis of the angular distributions of the unnatural parity states at 11.83 and 13.35 MeV, previously assigned ${J}^{\ensuremath{\pi}}={2}^{\ensuremath{-}}$, calls into question the validity of these assignments, suggesting that at least one of the states may correspond to ${J}^{\ensuremath{\pi}}={4}^{\ensuremath{-}}$. Evidence is also found for ${1}^{\ensuremath{-}}$ and ${3}^{\ensuremath{-}}$ strengths associated with broad states between 11 and 14 MeV.

The {sup 12}C({sup 12}C,{sup 8}Be+{sup 12}C(0{sub 2}{sup +})){sup 4}He reaction has been studied with beam energies of 82-120 MeV to search for excited states in {sup 20}Ne that decay into {sup 8}Be+{sup 12}C(0{sub 2}{sup +}). The detection of five of the six final-state {alpha} particles in an array of eight, sixteen-element, strip detectors permitted the full reconstruction of the reaction kinematics. Two {sup 20}Ne resonances at 35.2 and 36.5 MeV are observed, particularly at beam energies less than 93 MeV. An analysis of the angular correlations associated with the observed resonances indicates that an angular momentum of 10 ({Dirac_h}/2{pi}) is important in this region, and thus it is possible that at least one of the resonances possesses J{sup {pi}}=10{sup +}.

The $^{12}\mathrm{C}(^{12}\mathrm{C},^{8}\mathrm{Be}+^{8}\mathrm{Be})^{8}\mathrm{Be}$ reaction has been studied with 18 beam energies from $82\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}120\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$. The detection of four of the six final-state $\ensuremath{\alpha}$-particles in an array of eight 16-element strip detectors permitted the full reconstruction of the reaction kinematics. $^{16}\mathrm{O}$ excitation energy spectra spanning $19--40\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ were measured, which provided evidence for $^{16}\mathrm{O}$ excited states up to $35.1\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$. Angular correlation analysis indicates the dominant spins are 6 and $8\phantom{\rule{0.3em}{0ex}}\ensuremath{\hbar}$, possibly extending to $10\phantom{\rule{0.3em}{0ex}}\ensuremath{\hbar}$ at the highest excitation energies. The resulting energy-spin systematics are compared with the predictions of the $\ensuremath{\alpha}$ cluster model and cranked Nilsson-Strutinsky calculations.

An excitation function measurement has been performed over the laboratory range $52--94\phantom{\rule{0.3em}{0ex}}\text{MeV}$ investigating resonance phenomena in the single excitation $^{16}\mathrm{O}$ $(^{16}\mathrm{O},{^{16}\mathrm{O}}^{*}\ensuremath{\rightarrow}^{12}\mathrm{C}_{\mathrm{g.s.}}+\ensuremath{\alpha})^{16}\mathrm{O}_{\mathrm{g.s.}}$ breakup reaction. A number of enhancements are observed in these excitation functions for excitation to the ${4}_{1}^{+}$, $10.35\phantom{\rule{0.3em}{0ex}}\text{MeV}$ and ${4}_{2}^{+}$, $11.09\phantom{\rule{0.3em}{0ex}}\text{MeV}$ excited states in $^{16}\mathrm{O}$. The overlap between these and previously measured enhancements is discussed. Excitation functions for the ${2}_{2}^{+}$, $9.84\phantom{\rule{0.3em}{0ex}}\text{MeV}$ and ${2}_{3}^{+}$, $11.52\phantom{\rule{0.3em}{0ex}}\text{MeV}$ excited states are also presented.

New experimental data for the ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ reaction have been measured in the center-of-mass energy range ${E}_{\mathrm{c}.\mathrm{m}.}=40--59\mathrm{}\mathrm{MeV}.$ Excitation functions for a number of single and mutual ${}^{12}\mathrm{C}$ inelastic channels have been measured which include the ${0}_{\mathrm{g}.\mathrm{s}.}^{+},$ ${2}_{1}^{+},$ ${0}_{2}^{+},$ ${3}_{1}^{\ensuremath{-}},$ and ${4}_{1}^{+}$ ${}^{12}\mathrm{C}$ states. All of the reactions display largely unstructured excitation functions over this energy range. The absence of further resonances in this energy region for the ${}^{12}\mathrm{C}{(}^{12}\mathrm{C}{,}^{12}\mathrm{C}[{3}_{1}^{\ensuremath{-}}]{)}^{12}\mathrm{C}[{3}_{1}^{\ensuremath{-}}]$ reaction confirms theoretical predictions of the termination of the band of resonances found at lower center-of-mass energies in this channel.

10 pages, 2 tables, 13 figures.--PACS nrs.: 21.45.1v, 25.10.1s, 21.10.Gv.--ArXiv pre-print available at: http://arxiv.org/abs/nucl-ex/0111001, A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of intermediate energy (30-50 MeV/nucleon) Li-11, Be-14, and B-15 beams. Some six events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of Be-14, most probably in the channel Be-10+(4)n. The various backgrounds that may mimic such a signal are discussed in detail., This work was funded under the auspices of the IN2P3-CNRS (France) and EPSRC (United Kingdom). Additional support from the ALLIANCE program (Ministère des Affaires Etrangères and British Council) and the Human Capital and Mobility Program of the European Community (Contract No. CHGE-CT94-0056) is also acknowledged.

The breakup of 10,12Be into He clusters has been studied using the p,12C(12Be,6He,6He) and 12C(12Be,4He,6He) inelastic scattering and two neutron transfer reactions with a 378 MeV 12Be beam incident on 12C and (CH2)n targets. Evidence has been found for three new states in 10Be at excitation energies of 13.2, 14.8, and 16.1 MeV, which may be associated with a 4He+6He cluster structure. The evidence for He cluster states in 12Be in the excitation energy range 12 to 25 MeV is also discussed.

In order to search for a proposed α:2n:α:2n:α molecular structure in 16C its break-up into 10Be + 6He, 12Be + α, 8He + 2α and 6He + 6He + α has been studied using a 560 MeV 16C beam inelastically excited on a 12C target. States in 16C appear to be only weakly populated in this reaction.

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

The technique of intensity interferometry is proposed as a probe of the spatial configuration of two-Neutron haloes. After exploring the sensitivity of interferometry to the n-N configuration, it is demonstrated that the application of the standard method for constructing the correlation function is not valid for halo neutrons. A new iterative method is presented and applied to measurements of the dissociation of 6He, 11Li and 14Be. The correlation functions for these systems have thus been extracted for the first time and the corresponding root-Mean-Square n-n separations estimated. The results are in agreement with the predictions of available three-Body models. (C) 2000 Published by Elsevier Science B.V.

The two nuclei 12Be and 14Be have been studied using breakup reactions on p, 12C and 208Pb targets. The decay of 12Be into two helium clusters (6He+6He and 4He+8He) was observed from a series of excited states between 10 and 25 MeV, with spins in the range 4+ to 8+. The single neutron angular distributions for 14Be exhibit the narrow forward peak characteristic of a halo. The widths of these distributions in coincidence with 12Be fragments are ΓL = 78±6 and 80±1 MeV/c for breakup on carbon and lead.

In susceptible species, aluminum induces cytoskeletal changes in which neurofilaments accumulate in neuronal cell bodies and proximal axonal enlargements. To determine if microtubule-associated proteins (MAPs) are altered in this model, we examined the spinal cords of aluminum- and saline-treated control rabbits at several time points after treatment. Transient decreases in tau and MAP2 immunoreactivity in neurons in aluminum-intoxicated rabbits were demonstrated with immunocytochemistry. An antibody directed against Alzheimer's disease paired helical filaments labeled neurons in aluminum-treated rabbits but not controls. MAP5 immunoreactivity in the cell body cytoplasm was displaced by aluminum-induced tangles. The transient decreases in MAP2 and tau immunoreactivity did not reflect alterations in protein levels measured using immunoblotting. The transient antigenic changes in tau and MAP2 may reflect conformational changes in these cytoskeletal proteins. Aluminum-induced pathology provides a model for studying perturbations in MAPs and neurofilament proteins that are characteristic of many human neurodegenerative diseases such as Alzheimer's disease, diffuse Lewy body disease, Parkinson's disease, and amyotrophic lateral sclerosis.

The aim of this study was to understand the intention to use a condom for each instance of sexual intercourse with a new partner in three of Canada's non-dominant ethnocultural communities: Latin American (N = 346), English-speaking Caribbean (N = 358), and South Asian (N = 355). All respondents were recruited from multiple ethnocultural venues using predetermined sampling frames and quotas for each community. Anonymous questionnaires assessing culturally specific theoretical constructs were completed. This paper presents the methodology and the main findings. The high quality of the results of this study demonstrate the advantage of establishing strong partnerships with members of communities being studied.During April-May 1994, in Canada, 346 members of the Latin American community aged 18-49, 358 members of the English-speaking Caribbean community aged 16-49, and 355 members of the South Asian community aged 18-45 completed a questionnaire developed by the Research Group on Psychosocial Aspects of Health Behavior at Laval University in Quebec. This study aimed to identify the variables influencing intention to use a condom for each instance of sexual intercourse with a new partner in three nondominant ethnocultural communities. 81% of Latin Americans, 75% of the Caribbeans, and 71% of the South Asians intended to use a condom for each instance of sexual intercourse with a new partner during the next 3 months. Yet, among people who had had sex with a new partner in the last year, only 30% of Latin Americans, 28% of the Caribbeans, and 47% of South Asians always used a condom. Significant predictors of intent to use a condom in each instance of sexual intercourse with a new partner were personal normative belief (a measure of the personal feelings of moral obligation or responsibility to use or refuse to use a condom), perceived behavioral control, and role beliefs (p .0001). For the Latin American community, these three constructs explained 70.7% of the variance (partial R2 = 51.1% for personal normative belief, 10% for role beliefs, and 4.1% for perceived behavioral control). For the English-speaking Caribbean community, they explained 51% of the variance (partial R2 = 35.7% for personal normative belief, 11.9% for perceived behavioral control, and 3.5% for role beliefs). For the South Asian community, they accounted for 76% of the variance (partial R2 = 63.5% for perceived behavioral control, 9.4% for personal normative belief, and 3.1% for role beliefs). These findings serve as a basis for recommendations for the prevention of HIV transmission among the participating ethnocultural communities.

Canada's population is composed of heterogenous ethnocultural communities. There is a need for information and educational initiatives on HIV and AIDS directed specifically at these communities. For such interventions to be effective we must determine the existing personal and sociocultural factors related to HIV transmission. There has been little such research in Canada. In this supplement we report on various aspects of a study conducted between May 1992 and December 1994 to determine the factors related to HIV transmission in several ethnocultural communities. This paper describes some innovative aspects of the project: the conceptual framework, the community participatory model, the use of a multi-method research design, and the ongoing communication strategy. The combination of these elements makes the study unique. The value of the study lies not only in the information obtained but also in the model it provides for future research in other settings.

This paper presents the results of Phase II of the Ethnocultural Communities Facing AIDS Study, the sociocultural investigation of factors contributing to risk behaviour associated with HIV/AIDS in six ethnocultural communities in Canada in three urban sites. In Vancouver, the South Asian and Chinese communities were studied, the Horn of Africa and English-speaking Caribbean communities in Toronto and the Latin American and Arabic-speaking communities in Montreal. Results demonstrated that there are common elements across these ethnocultural communities that increase the risk for HIV transmission. HIV/AIDS awareness and prevention in ethnocultural communities must address sociocultural differences, particularly sex role differences between men and women in terms of power within relationships to negotiate for safer sexual practices.

This paper describes the survey results reporting demographic profiles, behaviours, opinions, beliefs, attitudes, and intentions related to condom use for three Canadian ethnocultural communities (Latin American, English-speaking Caribbean and South Asian) participating in the Ethnocultural Communities Facing AIDS Study. Specific recommendations are presented for HIV-prevention programming based on the research results.

This article reports on the methodology used to select six ethnocultural communities invited to participate in subsequent phases of the project on HIV/AIDS in the context of culture in Canada. Selection was based on quantitative data on demography, qualitative assessment of ethnocultural cohesion; and quantitative data and qualitative data of exposure to risk for sexually transmitted disease. A principle of partnership insured that the final selection was completed by interaction between the investigators and the National Advisory Committee representing ethnocultural communities in Canada. The six communities asked to participate in Phase II of the study were: in Montreal, the Latin American and the Arabic-speaking communities; in Toronto, the English-speaking Caribbean communities and communities from the Horn of Africa; in Vancouver, the Chinese and the South Asian communities. The results are significant for the future both of research on ethnicity in Canada and of control of HIV and AIDS.

This paper describes the steps taken in generating and implementing a qualitative research design for Phase II of the Ethnocultural Communities Facing AIDS Study. Theoretically framed by the macro-level, sociocultural model of health behaviour developed by Kleinman, the methodological procedures are an adaptation of Scrimshaw's Rapid Assessment Procedures (RAP) and a participatory approach involving stakeholders from each ethnocultural community. Qualitative data-on behaviours conducive to HIV transmission in six ethnocultural communities in Canada-were elicited using a combination of key communicator interviews, focus groups, and participant observation techniques. Data were analyzed using systematic content analysis techniques. Inter-rater reliability checks and procedures of triangulation demonstrated the validity of evidence generated. A commitment to research partnership with community persons, and an accountability loop that provided assurances of how the data would be scientifically represented, were critical elements in the process of design construction.

The immune system of normal individuals represents a dynamic and highly regulated interplay between various types of effector cells programmed to respond to and eliminate invading pathogens, while maintaining a state of tolerance to self molecules. In contrast, an autoimmune disorder reflects a breakdown in the regulatory mechanisms that normally govern a humoral and cellular response so that self molecules are recognized as foreign, thereby triggering an autoimmune attack. For the majority of autoimmune disorders described to date, such as insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis (RA), and multiple sclerosis (MS), the nature of the specific immunoregulatory defect(s) causing the disease is largely unknown. Moreover, the critical factors that predispose an individual to a particular autoimmune disease remain unclear. However, some insight has been gained from numerous genetic studies over the last two decades describing a rather striking association between autoimmunity and molecules encoded within the HLA complex, namely the HLA class I and II antigens.

SummaryAn extensive psychometric test battery was administered to 125 children with a reading disability, to their parents and siblings, and to members of 125 matched control families (N = 1,044). In addition to expected differences in spelling and reading, probands obtained significantly (P ≤ · 01) lower scores than controls on tests of other cognitive abilities. Manifold deficits were also found in siblings and parents of probands, conclusively demonstrating the familial (genetic and/or common-family environmental) nature of the disorder.