Dynamics of a nonlocal discrete Gross-Pitaevskii equation with defects.

We study the dynamics of dipolar gas in deep lattices described by a nonlocal nonlinear discrete Gross-Pitaevskii equation. The stabilities and the propagation properties of traveling plane waves in the system with defects are discussed in detail. For a clean lattice, both energetic and dynamical stabilities of the traveling plane waves are studied. It is shown that the system with attractive local interaction can preserve the stabilities, i.e., the dipoles can stabilize the gas because of repulsive nonlocal dipole-dipole interactions. For a lattice with defects, within a two-mode approximation, the propagation properties of traveling plane waves in the system map onto a nonrigid pendulum Hamiltonian with quasimomentum-dependent nonlinearity (induced by the nonlocal interactions). Competition between defects, quasimomentum of the gas, and nonlocal interactions determines the propagation properties of the traveling plane waves. Critical conditions for crossing from a superfluid regime with propagation preserved to a normal regime with defect-induced damping are obtained analytically and confirmed numerically. In particular, the critical conditions for supporting the superfluidity strongly depend on the defect type and the quasimomentum of the plane waves. The nonlocal interaction can significantly enhance the superfluidity of the system.

Modulational instability of a modified Gross-Pitaevskii equation with higher-order nonlinearity.

We consider the modulational instability (MI) of Bose-Einstein condensate (BEC) described by a modified Gross-Pitaevskii (GP) equation with higher-order nonlinearity both analytically and numerically. A new explicit time-dependent criterion for exciting the MI is obtained. It is shown that the higher-order term can either suppress or enhance the MI, which is interesting for control of the system instability. Importantly, we predict that with the help of the higher-order nonlinearity, the MI can also take place in a BEC with repulsively contact interactions. The analytical results are confirmed by direct numerical simulations.

[Job satisfaction and its influential factors in oil production workers].

OBJECTIVE: To investigate the job satisfaction and its influential factors in oil production workers. METHODS: 423 oil production workers were investigated using the Occupational Stress Instrument. RESULTS: The job satisfaction, job organization satisfaction, job itself satisfaction in the workers aged < 30 years old (45.69 +/- 10.98, 22.63 +/- 6.16, 23.07 +/- 5.39 respectively) were lower than those in workers aged > or = 30 years old (49.34 +/- 10.12, 24.60 +/- 5.40, 24.74 +/- 5.36 respectively) (P < 0.01). The job satisfaction in the groups of different service length was significantly different. The job satisfaction in the workers of service length 5-10 years was the lowest compared with those of service length < 5 years and > 10 years (P < 0.05). The gender, education, marriage did not show obvious influence on the job satisfaction. The relationship between psychological health, work locus of control, coping strategies, affective balance and social support showed a statistical significance difference (P < 0.01). Regression was analyzed by taking job satisfaction as strain and personal characters, occupational stress factors, coping as independent variables. Five variables entered regression equation. They were work locus of control, affective balance, social support, psychological health and coping strategies. CONCLUSION: The job satisfaction of oil production workers is affected by multiple factors such as the age, work length and social support.

[Effects of occupation on health of traffic policemen in a city].

OBJECTIVE: To investigate the health and work status of traffic policemen in a city, and analyze the effect of the occupation on health of them. METHODS: The prevalent investigation was used to investigate the health status of on-the-job traffic policemen and the effect of the occupation on the health of traffic policemen was studied. RESULTS: Among 4486 traffic policemen, 1604 working outside. The average time of working outside was (12.0 +/- 7.9) years and the average time of standing was (7.0 +/- 1.7) hours/day. The incidence of naso-pharyngitis, arthropathy, photosensitive dermatitis, heat stroke and chilblain, noise-induced deafness in the outside-traffic policemen were higher than that of the policemen working indoors. Eye diseases were higher in those who worked outside for 20-25 years. The varicosis of the lower extremity was higher in those who stood outside over 4 hours every day. The average period of onset of disease was 7-8 years. CONCLUSION: The occupational stress of outside-traffic policemen was bigger in the city. The environmental pollution and the bad condition are the risky factors of 8 kinds of diseases among traffic policemen. The average period of onset of the disease is 7-8 years.

[Relationship between work locus of control and occupational stress in oil workers].

OBJECTIVE: To investigate general states of the work locus of control and explore the relationship between work locus of control and occupational stress in oil workers. METHODS: 582 oil workers were investigated by using the General Questionnaire and Occupational Stress Measure Inventory. RESULTS: There were significant differences in WCLS score between two age groups (= 30 years old group and < 30 years old group) (t = 2.093, P = 0.037). Values of interpersonal relationship, person responsibility, promotion, participation, autonomy, task consistency, challenge, job satisfaction, mental health, self-esteem and coping strategies were higher in the group of internal locus of control; values of role ambiguity, working prospect, depression and social support were higher in the group of external locus of control (P < 0.05). Work locus of control had positive relation with role ambiguity, working prospect, depression, and social support, and negative with interpersonal relationship, promotion, participation, task consistency, challenge, job satisfaction, mental health, self-esteem and coping strategies. In the regression analysis, work locus of control was the major predictive factor of work satisfaction. CONCLUSION: Work locus of control is associated with many occupational stress factors. The group of extrinsic work locus of control experience more stress in oil workers.