Effects of photoperiod on growth of larvae and juveniles of the anemonefish Amphiprion melanopus

Rearing of anemonefishes is now relatively routine compared to the culture of cardinalfishes (Apogonidae) or angelfishes (Pomacanthidae). However, it is still a labor intensive, time intensive and expensive procedure. To reduce time and cost of rearing anemonefishes, experiments were undertaken to improve the methods for rearing Amphiprion melanopus. These experiments were conducted to determine the effect of the length of photoperiod on larval duration, growth to metamorphosis and early juvenile phase. Growth of larvae was significantly faster and the duration of the larval phase was significantly shorter, under a photoperiod of 16 hours light/8 hours dark, compared to the photoperiods of 12 hours light/12 hours dark and 24 hours light/0 hours dark

Intrinsic fantasy: motivation and affect in educational games made by children

The concept of intrinsic fantasy has been considered central to the aim of usefully applying the positive affect of computer games to learning. Games with intrinsic fantasy are defined as having “an integral and continuing relationship with the instructional content being presented”, and are claimed as “more interesting and more educational” than extrinsic fantasy games [1]. Studies of children making educational games have shown they usually create extrinsic games for curriculum learning content. In this study, children were encouraged to create non-curriculum games, more easily distanced from the extrinsic preconceptions of formal schooling. Forty, 7-11 year olds took part in this study (17 boys and 23 girls), designing and making their own games at an after-school club. Despite non-curriculum learning content, no more intrinsic games were created than in previous studies. The children failed to create their own pedagogical models for non-curriculum content and did not see the educational value of intrinsic fantasy games. The implications for transfer and learning in intrinsic games are discussed whilst the definition of intrinsic fantasy itself is questioned. It is argued that the integral relationship of fantasy is unlikely to be the most critical means of improving the educational effectiveness of digital games

Emotional and Adrenocortical Responses of Infants to the Strange Situation: The Differential Function of Emotional Expression

The aim of the study was to investigate biobehavioural organisation in infants with different qualities of attachment. Quality of attachment (security and disorganisation), emotional expression, and adrenocortical stress reactivity were investigated in a sample of 106 infants observed during Ainsworth’s Strange Situation at the age of 12 months. In addition, behavioural inhibition was assessed from maternal reports. As expected, securely attached infants did not show an adrenocortical response. Regarding the traditionally defined insecurely attached groups, adrenocortical activation during the strange situation was found for the ambivalent group, but not for the avoidant one. Previous ndings of increased adrenocortical activity in disorganised infants could not be replicated. In line with previous ndings, adrenocortical activation was most prominent in insecure infants with high behavioural inhibition indicating the function of a secure attachment relationship as a social buffer against less adaptive temperamental dispositions. Additional analyses indicated that adrenocortical reactivity and behavioural distress were not based on common activation processes. Biobehavioural associations within the different attachment groups suggest that biobehavioural processes in securely attached infants may be different from those in insecurely attached and disorganised groups. Whereas a coping model may be applied to describe the biobehavioural organisation of secure infants, an arousal model explanation may be more appropriate for the other groups

Viewpoint consistency in Z and LOTOS: A case study

Specification by viewpoints is advocated as a suitable method of specifying complex systems. Each viewpoint describes the envisaged system from a particular perspective, using concepts and specification languages best suited for that perspective. Inherent in any viewpoint approach is the need to check or manage the consistency of viewpoints and to show that the different viewpoints do not impose contradictory requirements. In previous work we have described a range of techniques for consistency checking, refinement, and translation between viewpoint specifications, in particular for the languages LOTOS and Z. These two languages are advocated in a particular viewpoint model, viz. that of the Open Distributed Processing (ODP) reference model. In this paper we present a case study which demonstrates how all these techniques can be combined in order to show consistency between a viewpoint specified in LOTOS and one specified in Z. Keywords: Viewpoints; Consistency; Z; LOTOS; ODP

Experimental active and passive dosimetry systems for the NASA Skylab program

Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis

Late biological effects of heavy charged particles: Cataracts, vascular injury and life shortening in mice

Risks associated with extended habitation in a space environment, particularly hazards to space workers that might result from exposure to high energy heavy ion particles (HZE), were studied. Biological effects of HZE were investigated in mice to assess their potential adverse health hazards. The potential effects of HZE particles on the crystalline lens of the eye and the carcinogenic effects and blood vessel (vascular) damage from radiation were evaluated by a risk assessment. Animal experiments to evaluate dose response relationships for tumor induction/promotion and for vascular injury were introduced. Cataract productions and preliminary results on cacinogenic and vascular effects are presented for perspective

Sub-arcsecond high sensitivity measurements of the DG~Tau jet with e-MERLIN

We present very high spatial resolution deep radio continuum observations at 5 GHz (6 cm) made with e-MERLIN of the young stars DG Tau A and B. Assuming it is launched very close (~=1 au) from the star, our results suggest that the DG Tau A outflow initially starts as a poorly focused wind and undergoes significant collimation further along the jet (~=50 au). We derive jet parameters for DG Tau A and find an initial jet opening angle of 86 degrees within 2 au of the source, a mass-loss rate of 1.5x10^-8 solar masses/yr for the ionised component of the jet, and the total ejection/accretion ratio to range from 0.06-0.3. These results are in line with predictions from MHD jet-launching theories.Comment: Accepted MNRAS Letter

Cataract production in mice by heavy charged particles

The cataractogenic effects of heavy charged particles are evaluated in mice in relation to dose and ionization density. The relative biological effectiveness in relation to linear energy transfer for various particles is considered. Results indicated that low single doses (5 to 20 rad) of Fe 56 or Ar 40 particles are cataractogenic at 11 to 18 months after irradiation; onset and density of the opacification are dose related and cataract density (grade) at 9, 11, 13, and 16 months after irradiation shows partial linear energy transfer dependence. The severity of cataracts is reduced significantly when 417 rad of Co 60 gamma radiation is given in 24 weekly 17 rad fractions compared to giving this radiation as a single dose, but cataract severity is not reduced by fractionation of C12 doses over 24 weeks

Tentative Evidence for Relativistic Electrons Generated by the Jet of the Young Sun-like Star DG Tau

Synchrotron emission has recently been detected in the jet of a massive protostar, providing further evidence that certain jet formation characteristics for young stars are similar to those found for highly relativistic jets from AGN. We present data at 325 and 610 MHz taken with the GMRT of the young, low-mass star DG Tau, an analog of the Sun soon after its birth. This is the first investigation of a low-mass YSO at at such low frequencies. We detect emission with a synchrotron spectral index in the proximity of the DG Tau jet and interpret this emission as a prominent bow shock associated with this outflow. This result provides tentative evidence for the acceleration of particles to relativistic energies due to the shock impact of this otherwise very low-power jet against the ambient medium. We calculate the equipartition magnetic field strength (0.11 mG) and particle energy (4x10^40 erg), which are the minimum requirements to account for the synchrotron emission of the DG Tau bow shock. These results suggest the possibility of low energy cosmic rays being generated by young Sun-like stars.Comment: 19 pages, 2 figures, accepted for publication in ApJ Letter