An approximation theory for the identification of nonlinear distributed parameter systems

An abstract approximation framework for the identification of nonlinear distributed parameter systems is developed. Inverse problems for nonlinear systems governed by strongly maximal monotone operators (satisfying a mild continuous dependence condition with respect to the unknown parameters to be identified) are treated. Convergence of Galerkin approximations and the corresponding solutions of finite dimensional approximating identification problems to a solution of the original finite dimensional identification problem is demonstrated using the theory of nonlinear evolution systems and a nonlinear analog of the Trotter-Kato approximation result for semigroups of bounded linear operators. The nonlinear theory developed here is shown to subsume an existing linear theory as a special case. It is also shown to be applicable to a broad class of nonlinear elliptic operators and the corresponding nonlinear parabolic partial differential equations to which they lead. An application of the theory to a quasilinear model for heat conduction or mass transfer is discussed

On the number of particles which a curved quantum waveguide can bind

We discuss the discrete spectrum of N particles in a curved planar waveguide. If they are neutral fermions, the maximum number of particles which the waveguide can bind is given by a one-particle Birman-Schwinger bound in combination with the Pauli principle. On the other hand, if they are charged, e.g., electrons in a bent quantum wire, the Coulomb repulsion plays a crucial role. We prove a sufficient condition under which the discrete spectrum of such a system is empty.Comment: a LateX file, 12 page

Numerical studies of identification in nonlinear distributed parameter systems

An abstract approximation framework and convergence theory for the identification of first and second order nonlinear distributed parameter systems developed previously by the authors and reported on in detail elsewhere are summarized and discussed. The theory is based upon results for systems whose dynamics can be described by monotone operators in Hilbert space and an abstract approximation theorem for the resulting nonlinear evolution system. The application of the theory together with numerical evidence demonstrating the feasibility of the general approach are discussed in the context of the identification of a first order quasi-linear parabolic model for one dimensional heat conduction/mass transport and the identification of a nonlinear dissipation mechanism (i.e., damping) in a second order one dimensional wave equation. Computational and implementational considerations, in particular, with regard to supercomputing, are addressed

Micro-Savings and Poverty Reduction in Nigeria: Some Field Observations from Gokana Local Government Area of Rivers State

This study had the objective of investigating issues relating to micro-saving and how it can be employed to reduce poverty in Gokana Local Government Area of Rivers State, Nigeria.  A field survey was conducted in which primary data were collected using a structured questionnaire.  A total of 102 micro-saving cooperative members were interviewed.  Based on descriptive statistics tools of percentages and simple averages, the study reveals that micro-saving is a veritable source of raising funds for investment. Also, lack of access to formal financial institution makes people to patronize micro-savings in Gokana LGA. Again, respondents engaged in micro-savings for emergencies and unexpected investment purposes while cultural obligations induce respondents to engage in micro-saving and more. It is therefore suggested that an enabling macroeconomic environment be given to informal financial sector of Nigeria. This can be achieved by encouraging members of the micro-saving cooperatives to register at least at the local government council to promote assistants from the government on their operations. Keywords: Gokana, Micro-Savings and Poverty Reductio

Oriented polaritons in strongly-coupled asymmetric double quantum well microcavities

Replacing independent single quantum wells inside a strongly-coupled semiconductor microcavity with double quantum wells produces a special type of polariton. Using asymmetric double quantum wells in devices processed into mesas allows the alignment of the electron levels to be voltage-tuned. At the resonant electronic tunnelling condition, we demonstrate that `oriented polaritons' are formed, which possess greatly enhanced dipole moments. Since the polariton-polariton scattering rate depends on this dipole moment, such devices could reach polariton lasing, condensation and optical nonlinearities at much lower threshold powers.Comment: 3 figure

I lie? We lie! Why? Experimental evidence on a dishonesty shift in groups

Unethical behavior such as dishonesty, cheating and corruption occurs frequently in organizations or groups. Recent experimental evidence suggests that there is a stronger inclination to behave immorally in groups than individually. We ask if this is the case, and if so, why. Using a parsimonious laboratory setup, we study how individual behavior changes when deciding as a group member. We observe a strong dishonesty shift. This shift is mainly driven by communication within groups and turns out to be independent of whether group members face payoff commonality or not (i.e. whether other group members benefit from one’s lie). Group members come up with and exchange more arguments for being dishonest than for complying with the norm of honesty. Thereby, group membership shifts the perception of the validity of the honesty norm and of its distribution in the population

I lie? We lie! Why? Experimental evidence on a dishonesty shift in groups

Unethical behavior such as dishonesty, cheating and corruption occurs frequently in organizations or groups. Recent experimental evidence suggests that there is a stronger inclination to behave immorally in groups than individually. We ask if this is the case, and if so, why. Using a parsimonious laboratory setup, we study how individual behavior changes when deciding as a group member. We observe a strong dishonesty shift. This shift is mainly driven by communication within groups and turns out to be independent of whether group members face payoff commonality or not (i.e. whether other group members benefit from one’s lie). Group members come up with and exchange more arguments for being dishonest than for complying with the norm of honesty. Thereby, group membership shifts the perception of the validity of the honesty norm and of its distribution in the population

A pilot investigation of load-carrying on the head and bone mineral density in premenopausal, black African women

Although the influence of weight bearing activity on bone mass has been widely investigated in white women, few studies have been conducted in black, African populations. We investigated bone mineral density (BMD) in black South African women, with and without a history of load-carrying on the head. We also investigated whether load carrying may offer protection against low BMD in users of injectable progestin contraception (IPC). Participants were 32 black, South African women (22.4±3.2 yrs). Load carrying history was determined by questionnaire and interview and participants were grouped as load carriers (LC; n=18) or non load carriers (NLC; n=14). Ten women were using IPC and 6 were load-carriers. Total body (TB), lumbar spine (LS) and total hip (H) BMD were measured by dual energy X-ray absorptiometry. There were no differences in BMD between LC and NLC, and after controlling for age and BMI using two-tailed partial correlations. IPC users had lower BMD at all sites compared to non IPC users (p<0.05) and there were no associations between load carrying and BMD in this group. When IPC users were excluded from analysis, LC had higher LS BMD than NLC (p<0.005). Correlations were found between the weight of load carried and LS BMD (r=0.743, p<0.005), and between years of load carrying and LS and TB BMD (r=0.563, r=0.538 respectively; both p<0.05). Load carrying on the head may offer osteogenic benefits to the spine but these benefits did not appear in women using IPC