A holographic system for subsea recording and analysis of plankton and other marine particles

We report here details of the design, development, initial testing and field-deployment of the HOLOMAR system for in-situ subsea holography and analysis of marine plankton and nonliving particles. HOLOMAR comprises a submersible holographic camera ("HoloCam") able to record in-line and off-axis holograms at depths down to 100 m, together with specialised reconstruction hardware ("HoloScan") linked to custom image processing and classification software. The HoloCam consists of a laser and power supply, holographic recording optics and holographic plate holders, a water-tight housing and a support frame. It utilises two basic holographic geometries, in-line and off-axis such that a wide range of species, sizes and concentrations can be recorded. After holograms have been recorded and processed they are reconstructed in full three-dimensional detail in air in a dedicated replay facility. A computer-controlled microscope, using video cameras to record the image at a given depth, is used to digitise the scene. Specially written software extracts a binarised image of an object in its true focal plane and is classified using a neural network. The HoloCam was deployed on two separate cruises in a Scottish sea loch (Loch Etive) to a depth of 100 m and over 300 holograms were recorded

High-resolution in situ holographic recording and analysis of marine organisms and particles (HOLOMAR)

We report on the development of a fully- unctioning, prototype, underwater holographic camera (holo-camera) for holographic recording of large-volumes of sea water containing marine plankton and seston within the upper water column The overriding benefit of holographic imaging over other measurement techniques is that it allows non-intrusive and non-destructive, in-situ, recording of living organisms and inanimate particles in their natural environment. Because of the inherently high resolution of holography, its threedimensional imaging properties and the ability to perform "optical sectioning" on the image, it allows identification of particular organisms together with the extraction of sue and relative positional information This information, in turn, affords the ability to gain knowledge of the behaviour of marine biological communities, their relationship with each other and with the particles with which they interact

Dépister et analyser les violences subies en milieu scolaire~: le questionnaire de persécution par les camarades (PPC-17)

International audienceRésumé Notre objectif était d'élaborer un questionnaire crayon\textendashpapier d'auto-évaluation des violences subies en milieu scolaire par des enfants ou adolescents de la part d'autres jeunes, applicable dès l'âge de 8 ans et permettant de différencier plusieurs formes de violence physique et psychologique. Nous avons mis au point le questionnaire de persécution par les camarades en 17~items (PPC-17) et nous l'avons testé sur 1564~enfants et adolescents âgés de 8~à 17 ans. Les analyses factorielles ont confirmé une structure en trois facteurs de premier ordre, violence physique, mise à l'écart et insultes\textendashmoqueries, saturant tous trois dans un facteur de deuxième ordre. Cohérence interne et fidélité test\textendashretest sont satisfaisantes. Le score global est indépendant du sexe mais non de l'âge~: il est plus faible chez les adolescents que chez les enfants. Le PPC-17~permet un premier repérage des jeunes susceptibles d'être harcelés en milieu scolaire et l'étude qualitative des violences subies. AbstractAim of the study Although research on school bullying has been developing in France for several years, no handy and sound self-report measure of aggression by peers is available by now in our country. The aim of this study was to design an instrument that would help (1) screen for youths at risk to be victimized, and (2) differentiate the types of aggression suffered by the respondent. We wrote a 17-item self-report paper/pencil questionnaire, the PPC-17 (persécution par les camarades = harassment by peers), consisting in very simple sentences understandable by 8-year old children and usable from ages 8 to 17 years. Method Two samples were successively recruited in primary and secondary schools of the Paris larger area: the first comprised 331 youths (175 girls) 8 to 17 years old; the second comprised 1233 youths (648 girls). They were administered the PPC-17 questionnaire. As principal component analysis conducted on the first sample had suggested a hierarchical model with three first-order factors (physical aggression, exclusion, and insults/mockery) loading on a second-order one, we tested this model using confirmatory factor analyses conducted on the second sample. Gender and age effects on the scores were investigated via analyses of variance. Results These analyses confirmed the good fit of the model, and its configural and parametric (factor loadings) invariance across all four gender and age subgroups (female and male children, female and male adolescents). Internal consistency of all factor scales was satisfactory with Cronbach's α coefficients ranging from .73 to .89 as well as one-week test\textendashretest reliability with correlation coefficients ranging from .77 to .88. There was a main effect of age on all scales except insults/mockery, with adolescents reporting less harassment than children. Effects of gender were more balanced: we did not found significant gender differences on the PPC-17 total score; however, boys scored higher than girls on physical aggression, whilst girls scored higher on exclusion. Interactions indicated that male children scored higher than all other subgroups on physical aggression, and that male adolescents scored lower than all other subgroups on insults/mockery. Discussion and conclusion The PPC-17 is a short and reliable measure of the amount to which a youth feels he/she suffered from aggression by peers. It is not intended to be a measure of bullying, as classically defined. It may help both identify youths who could be victims of bullying, and differentiate three forms of aggressions by peers

Dépister et analyser les violences subies en milieu scolaire~: le questionnaire de persécution par les camarades (PPC-17)

International audienceRésumé Notre objectif était d'élaborer un questionnaire crayon\textendashpapier d'auto-évaluation des violences subies en milieu scolaire par des enfants ou adolescents de la part d'autres jeunes, applicable dès l'âge de 8 ans et permettant de différencier plusieurs formes de violence physique et psychologique. Nous avons mis au point le questionnaire de persécution par les camarades en 17~items (PPC-17) et nous l'avons testé sur 1564~enfants et adolescents âgés de 8~à 17 ans. Les analyses factorielles ont confirmé une structure en trois facteurs de premier ordre, violence physique, mise à l'écart et insultes\textendashmoqueries, saturant tous trois dans un facteur de deuxième ordre. Cohérence interne et fidélité test\textendashretest sont satisfaisantes. Le score global est indépendant du sexe mais non de l'âge~: il est plus faible chez les adolescents que chez les enfants. Le PPC-17~permet un premier repérage des jeunes susceptibles d'être harcelés en milieu scolaire et l'étude qualitative des violences subies. AbstractAim of the study Although research on school bullying has been developing in France for several years, no handy and sound self-report measure of aggression by peers is available by now in our country. The aim of this study was to design an instrument that would help (1) screen for youths at risk to be victimized, and (2) differentiate the types of aggression suffered by the respondent. We wrote a 17-item self-report paper/pencil questionnaire, the PPC-17 (persécution par les camarades = harassment by peers), consisting in very simple sentences understandable by 8-year old children and usable from ages 8 to 17 years. Method Two samples were successively recruited in primary and secondary schools of the Paris larger area: the first comprised 331 youths (175 girls) 8 to 17 years old; the second comprised 1233 youths (648 girls). They were administered the PPC-17 questionnaire. As principal component analysis conducted on the first sample had suggested a hierarchical model with three first-order factors (physical aggression, exclusion, and insults/mockery) loading on a second-order one, we tested this model using confirmatory factor analyses conducted on the second sample. Gender and age effects on the scores were investigated via analyses of variance. Results These analyses confirmed the good fit of the model, and its configural and parametric (factor loadings) invariance across all four gender and age subgroups (female and male children, female and male adolescents). Internal consistency of all factor scales was satisfactory with Cronbach's α coefficients ranging from .73 to .89 as well as one-week test\textendashretest reliability with correlation coefficients ranging from .77 to .88. There was a main effect of age on all scales except insults/mockery, with adolescents reporting less harassment than children. Effects of gender were more balanced: we did not found significant gender differences on the PPC-17 total score; however, boys scored higher than girls on physical aggression, whilst girls scored higher on exclusion. Interactions indicated that male children scored higher than all other subgroups on physical aggression, and that male adolescents scored lower than all other subgroups on insults/mockery. Discussion and conclusion The PPC-17 is a short and reliable measure of the amount to which a youth feels he/she suffered from aggression by peers. It is not intended to be a measure of bullying, as classically defined. It may help both identify youths who could be victims of bullying, and differentiate three forms of aggressions by peers

A holographic system for subsea recording and analysis of plankton and other marine particles (HOLOMAR)

We report here details of the design, development, initial testing and field-deployment of the HOLOMAR system for in-situ subsea holography and analysis of marine plankton and nonliving particles. HOLOMAR comprises a submersible holographic camera ("HoloCam") able to record in-line and off-axis holograms at depths down to 100 m, together with specialised reconstruction hardware ("HoloScan") linked to custom image processing and classification software. The HoloCam consists of a laser and power supply, holographic recording optics and holographic plate holders, a water-tight housing and a support frame. It utilises two basic holographic geometries, in-line and off-axis such that a wide range of species, sizes and concentrations can be recorded. After holograms have been recorded and processed they are reconstructed in full three-dimensional detail in air in a dedicated replay facility. A computer-controlled microscope, using video cameras to record the image at a given depth, is used to digitise the scene. Specially written software extracts a binarised image of an object in its true focal plane and is classified using a neural network. The HoloCam was deployed on two separate cruises in a Scottish sea loch (Loch Etive) to a depth of 100 m and over 300 holograms were recorded