Simplex s = ±i excitations in 141Xe

Excited levels in ¹⁴¹Xe, populated in spontaneous fission of ²⁴⁸Cm, were studied by means of prompt -ray spectroscopy, using the EUROGAMM2 array. Level scheme of ¹⁴¹Xe obtained in this work shows patterns characteristic of simplex symmetry with s=+i and s=-i bands present but low value of D₀ moment indicates that octupole correlations in Xe isotopes are systematically lower than in Ba nuclei. Received: 9 March 2000 / Accepted: 4 May 2000     

Revealing the Dynamics of Neural Information Processing with Multivariate Information Decomposition

The varied cognitive abilities and rich adaptive behaviors enabled by the animal nervous system are often described in terms of information processing. This framing raises the issue of how biological neural circuits actually process information, and some of the most fundamental outstanding questions in neuroscience center on understanding the mechanisms of neural information processing. Classical information theory has long been understood to be a natural framework within which information processing can be understood, and recent advances in the field of multivariate information theory offer new insights into the structure of computation in complex systems. In this review, we provide an introduction to the conceptual and practical issues associated with using multivariate information theory to analyze information processing in neural circuits, as well as discussing recent empirical work in this vein. Specifically, we provide an accessible introduction to the partial information decomposition (PID) framework. PID reveals redundant, unique, and synergistic modes by which neurons integrate information from multiple sources. We focus particularly on the synergistic mode, which quantifies the “higher-order” information carried in the patterns of multiple inputs and is not reducible to input from any single source. Recent work in a variety of model systems has revealed that synergistic dynamics are ubiquitous in neural circuitry and show reliable structure–function relationships, emerging disproportionately in neuronal rich clubs, downstream of recurrent connectivity, and in the convergence of correlated activity. We draw on the existing literature on higher-order information dynamics in neuronal networks to illustrate the insights that have been gained by taking an information decomposition perspective on neural activity. Finally, we briefly discuss future promising directions for information decomposition approaches to neuroscience, such as work on behaving animals, multi-target generalizations of PID, and time-resolved local analyses.     

Synthesis of tri-aryl ether epoxy resin isomers and their cure with diamino diphenyl sulphone

The synthesis of bi- and tetra-functional tri-aryl ether epoxy resin isomers and their subsequent cure with 44 diamino diphenyl sulphone (DDS) is presented here. The effect of varying aromatic substitution and cross-link density on the structure, property, and processing relationships is explored for 1,3 bis(3-glycidyloxyphenoxy)benzene (133 BGOPB), 1,4 bis(4-glycidyloxyphenoxy)benzene (144 BGOPB), N,N,N,N-tetraglycidyl 1,3-bis (3-aminophenoxy) benzene (133 TGAPB), and N,N,N,N-tetraglycidyl 1,4-bis (4-aminophenoxy) benzene (144 TGAPB). Meta substitution to the aromatic ring reduces the rate of reaction, glass transition temperature, yield strain and crosslink density, coefficient of thermal expansion, and side reactions, while increasing strain softening, compressive modulus and strength, and methyl ethyl ketone ingress. Increasing crosslink density increases the glass transition temperature, promotes side reactions during cure, and increases compressive modulus, strength, and yield strain, while reducing coefficients of thermal expansion, methyl ethyl ketone ingress, and density. The results are discussed in terms of packing efficiency of the meta-substituted epoxy resins and the role of short range molecular mobility caused by the lack of an aromatic axis of rotation.     

A multi point conductivity measurement system for characterisation of protein foams

Protein foams play an important role in both food and biotechnological processes. A sound understanding of foaming properties of proteins relevant to such processes is useful e.g. to allow adequate control of unwanted foams and appropriate choice of protein-physical system when foams of certain characteristics are required. In general, measurements of changes in foam volume (volumetric method) are used for foam characterisation. However, recently there has been increased interest in the use of measurement methods based on conductivity and capacitance. Simple relative techniques based on electrical conductivity measurements provide information on both foamability and foam stability. A multi point conductivity measurement system has been designed and used for characterisation of model protein foams (0.1 and 1.0 mg ml⁻¹ Bovine serum albumin, BSA). The solution of BSA was sparged with nitrogen or carbon dioxide gas at constant flow rate (90 cm³ min⁻¹) via a stainless steel sinter (0.5 or 2.0 μm in pore size). A comparison of foaming properties determined by volumetric and conductimetric techniques is provided. Both methods show that more stable foams are obtained for solutions at higher BSA concentrations. At all BSA concentrations, higher foamability and stability are achieved with a smaller sinter pore size. When nitrogen rather than carbon dioxide is used as a dispersed phase, higher foamability and foam stability are obtained. The conductivity measurements indicate that foamability is dependent on gas type, whereas, volumetric measurements do not show such differences.     

The ν9/2[404] orbital and the deformation in the A ∼ 100 region

A T _1/2 = 16(2)ns isomeric level, populated in the spontaneous fission of ²⁴⁸Cm, has been found in ¹⁰¹Zr at 941.8keV in a measurement of prompt -rays using the EUROGAM2 array. The level is interpreted as a K-isomer corresponding to the 9/2[404] neutron-hole excitation. The quadrupole moment, Q ₀ = 3.6(4)eb, deduced for the new band indicates a large deformation of , which is produced by a specific shape-coexistence mechanism. This is another observation of the 9/2[404] orbital in the mass region, confirming the presence of the effect reported first in our previous work. The 9/2[404] neutron-hole excitation is also confirmed in the ⁹⁷Sr nucleus and the deformation is determined for this configuration. The properties of the 9/2[404] neutron orbital and its influence on the onset of deformation in the region are discussed.PACS: 23.20.Lv transitions and level energies - 21.60.Cs Shell model - 25.85.Ca Spontaneous fission - 27.60. + j      

High-spin structures of 51 121, 123, 125, 127Sb nuclei: Single proton and core-coupled states

The ^{121,123,125,127}Sb nuclei have been produced as fission fragments in three reactions induced by heavy ions: ¹²C + ²³⁸U at 90 MeV bombarding energy, ¹⁸O + ²⁰⁸Pb at 85 MeV, and ³¹P + ¹⁷⁶Yb at 152 MeV. Their level schemes have been built from gamma rays detected using the EUROBALL III and IV arrays. High-spin states of ^123,125,127Sb nuclei have been identified for the first time. Moreover isomeric states lying around 2.3 MeV have been established in ^123,125,127Sb from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. All the observed states can be described by coupling a d_5/2 or g_7/2 proton to an excited Sn core involving either vibrational states or broken neutron pairs.     

Rotational and single-particle structures in83Zr

The band structure of⁸³Zr has been investigated using the Daresbury recoil separator and TESSA array with 20 Compton suppressed Ge detectors and the reaction²⁸Si (⁵⁸Ni, 2pn) at 195 MeV. DCO ratios have been used to make many new spin assignments. The three known rotational bands have been extended up to the onset of the five quasiparticle bands. On the basis of the 21/2⁺, 23/2⁺ and 25/2⁺ yrast and yrare states, a (3qp) structure similar to those found in the isotones⁷⁹Kr and⁸¹Sr has been identified. Additional bands have been observed for the first time, one of which appears to be non-collective. Strong mixing between the various negative parity bands is evident. A multiplet of states feeding the three quasiparticle region of the negative parity yrast band has been found. The data is interpreted in the framework of the cranked shell model.     

A 15 μs isomer in thez=70n=83 nucleus153Yb

Gamma-ray measurements following mass analysis of¹⁰²Pd+245 MeV⁵⁴Fe reaction products have characterized a 15 μs isomeric decay in¹⁵³Yb and elucidated the systematics of proton-rich N=83 nuclei.     

A 35 μs isomer in the exoticN=83 Nucleus154Lu

The⁷⁰Ge(α,nγ)⁷³Se reaction was used to populate medium spin states of the⁷³Se nucleus. Spins and parities up to about I^π=(21/2⁺)? were determined by gamma angular distribution, gamma linear polarization and excitation function measurements.