[Predictors of osteoarticular problems in a cohort of computer users in Lebanon: about 810 employees]. / Facteurs prédictifs des troubles ostéo-articulaires chez les utilisateurs d'ordinateurs au Liban: a propos d'une cohorte de 810 employés.

OBJECTIVE: The aim of the study is the analysis of osteoarticular problems (OAP) occurring in a group of computer users (CU) in search of correlation between symptoms and different etiological factors. MATERIAL AND METHOD: Questionnaire of 31 items dealing with personal data, the activity of the CU, stress, the occurrence of osteoarticular problems during the last month (Oaplm) and last twelve months (Oaptm) and a checklist of 17 items covering the physical characteristics of the workplace. RESULTS: DESCRIPTIVE ANALYSIS * 810 respondents of mean age 36 +/- 9 years and predominantly female (69%) * FEATURES: seniority at the workplace (12.5 +/- 9 years), pace of work (825 +/- 1.5 hours/day and 5.5 +/- 1 days/ week), number of breaks (13 +/- 1.04/d), duration of breaks (35 min +/- 25/d), 44.5% in sports activities, work stress in 92% of participants * OAP described:--Osteoarticular problems last month (62%), neck pain (68%), shoulder (46%) and lumbar spine (62%) pain. Tingling hands (40%). Headache (55.5%). Temporomandibular disorders (18.5%)--Osteoarticular problems the last twelve months (46%). UNIVARIATE ANALYSIS: Detection of risk factors * RISK FACTORS and Oaplm relationship: female, weight gain, secretary, stress, pain during labor and work stoppages withp < 0.05 * RISK FACTORS and Oaptm relationship: the position of secretary, stress, pain at work, work stop-pages for Oaplm withp < 0.05 * Protection factor: sports more than one time per week. MULTIVARIATE ANALYSIS: Oaplm occurrent factors: weight gain, Oaptm withp < 0.05. Protection factor: well designed workstation * Oaptm occurrent factors: age, stress and Oaplm with p < 0.05. CONCLUSION: Significant prevalence of osteoarticular problems in Lebanese computer users. RISK FACTORS: age, Oaptm, weight gain, stress, work-break cycle not respected and poor layout of the workstation. Ergonomic interventions are necessary and indispensable to reduce the cost of occupational diseases related to the CU, and ensure good mental and physical health.

Structural factors impacting carrier transport and electroluminescence from Si nanocluster-sensitized Er ions.

We present an analysis of factors influencing carrier transport and electroluminescence (EL) at 1.5 µm from erbium-doped silicon-rich silica (SiOx) layers. The effects of both the active layer thickness and the Si-excess content on the electrical excitation of erbium are studied. We demonstrate that when the thickness is decreased from a few hundred to tens of nanometers the conductivity is greatly enhanced. Carrier transport is well described in all cases by a Poole-Frenkel mechanism, while the thickness-dependent current density suggests an evolution of both density and distribution of trapping states induced by Si nanoinclusions. We ascribe this observation to stress-induced effects prevailing in thin films, which inhibit the agglomeration of Si atoms, resulting in a high density of sub-nm Si inclusions that induce traps much shallower than those generated by Si nanoclusters (Si-ncs) formed in thicker films. There is no direct correlation between high conductivity and optimized EL intensity at 1.5 µm. Our results suggest that the main excitation mechanism governing the EL signal is impact excitation, which gradually becomes more efficient as film thickness increases, thanks to the increased segregation of Si-ncs, which in turn allows more efficient injection of hot electrons into the oxide matrix. Optimization of the EL signal is thus found to be a compromise between conductivity and both number and degree of segregation of Si-ncs, all of which are governed by a combination of excess Si content and sample thickness. This material study has strong implications for many electrically-driven devices using Si-ncs or Si-excess mediated EL.

Electrically tailored resistance switching in silicon oxide.

Resistive switching in a metal-free silicon-based material offers a compelling alternative to existing metal oxide-based resistive RAM (ReRAM) devices, both in terms of ease of fabrication and of enhanced device performance. We report a study of resistive switching in devices consisting of non-stoichiometric silicon-rich silicon dioxide thin films. Our devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. We demonstrate different operational modes that make it possible to dynamically adjust device properties, in particular two highly desirable properties: nonlinearity and self-rectification. This can potentially enable high levels of device integration in passive crossbar arrays without causing the problem of leakage currents in common line semi-selected devices. Aspects of conduction and switching mechanisms are discussed, and scanning tunnelling microscopy (STM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments.

Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films.

This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 µm, normalized to the film thickness, was found five times larger for films 1 µm-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices.