Biomagnetic measurements utilising a superparamagnetic marker: a feasibility study

Summary A preliminary study is here reported on a new potential marker for biomagnetic measurements. The marker consists of superparamagnetic polymer microspheres which were detected in the presence of external steady magnetic fields by means of an r.f.-SQUID magnetometer. The particles were prepared in samples differing in the concentration value and immersed in a homogeneous magnetic field of variable intensity. A simple model was taken into account for the distribution of the microspheres in the samples, so that the theoretical values were compared to the marker field values measured by the biomagnetic sensor. The overall sensitivity of the experimental apparatus and the minimum concentration value of the marker were then estimated.     

Moment problem for effect algebras

We present a solution to the moment problem for effect algebras, concerning mean values of all powers of an observable concentrated on the interval [0, 1] for states from a convex set. We give a solution for particular examples, e.g., for the set of all effect operators. We examine how this problem is related to a socalled E-property. Finally, we give a solution for observables studied in the operational approach to physical theories.     

A mathematical model of the ring-spinning process

This paper develops a mathematical model of the ring-spinning process that takes into account its non-stationary nature. A complex system of differential equations is obtained, which from a mathematical point of view constitutes a ‘free-boundary’ problem. Its solution involves definition of suitable boundary conditions related to the mechanical characteristics of the process and of the spinning machine itself. The boundary conditions which determine the solution are pointed out. A numerical solution of the system of differential equations can be obtained by the Finite-Segments method, as shown in an example.     

Analysis of the crystallization kinetics in poly(ethylene oxide) by calorimetric measurements

Summary Differential scanning calorimetric measurements in the early stage of isothermal crystal growth of polyethylene oxide are analysed in the light of irreversible thermodynamics. An accurate evaluation of the equilibrium melting temperature is done by fitting the thermograms obtained at different undercoolings and referring to the activation energy values already known from the literature. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

Chemically controlled pattern formation in phase-separating materials

Summary The role of chemical reactions in the selection of patterns in phase-separating mixtures is presented. Linearized theory and computer simulation show that the initial long-wavelength instability characteristic of spinodal decomposition is suppressed by chemical reactions, which restrict domain growth to intermediate length scales even in the late stages of phase separation. Our findings suggest that chemical reactions may provide a novel way to stabilize and tune the steady-state morphology of phase-separating materials. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

示差半微分循环伏安法研究琥珀酰胆碱在水/硝基苯界面的传递行为

研究了油/水界面电解的示差半微分循环伏安行为。在0.01mol/L LiCl(w)-0.01mol/L TBATCIPB(nb)体系“电位窗”比TBATPB(nb)向正方向扩展约50mV,残余电流基本消除,使“电位窗”内的平台向左右拓宽约50mV。算得界面电容约为16μF/cm~2。考察了琥珀酰胆碱离子在w/nb界面的传递伏安特性,结果与一般半微分循环伏安法相似。但峰形改善,检测限降低一个数量级(1×10~(-6)mol/L),相对标准偏差在5％以内,可用于定量测定琥珀酰胆碱。     

Normal Vietoris Implies Compactness: A Short Proof

One of the most celebrated results in the theory of hyperspaces says that if the Vietoris topology on the family of all nonempty closed subsets of a given space is normal, then the space is compact (Ivanova-Keesling-Velichko). The known proofs use cardinality arguments and are long. In this paper we present a short proof using known results concerning Hausdorff uniformities.     

On the characterisation of paired monotone metrics

Hasegawa and Petz introduced the notion of paired monotone metrics. They also gave a characterisation theorem showing that Wigner-Yanase-Dyson metrics are the only members of the paired family. In this paper we show that the characterisation theorem holds true under hypotheses that are more general than those used in the above quoted references.