The effect of temporally variable environmental stimuli and group size on emergence behavior

How animals trade-off food availability and predation threats is a strong determinant of animal activity and behavior; however, the majority of work on this topic has been on individual animals, despite the modulating effect the presence of conspecifics can have on both foraging and predation risk. Although these environmental factors (food and predation threat) vary spatially within habitats, they also vary temporally, and in marine habitats, this can be determined by not only the diel cycle but also the tidal cycle. Humbug damselfish, Dascyllus aruanus, live in small groups of unrelated individuals within and around branching coral heads, which they collectively withdraw into to escape a predation threat. In this study, we measured the proportion of individuals in the colony that were outside the coral head before and after they were scared by a fright stimulus and compared the responses at high tide (HT) and low tide (LT). We found that a greater proportion of the shoal emerged after the fright stimulus at HT and in larger groups than at LT or in smaller groups. We also quantified the pattern of emergence over time and discovered the rate of emergence was faster in larger shoals as time progressed. We show that shoals of fish change their behavioral response to a predation threat in accordance with the tide, exemplifying how temporally variable environmental factors can shape group movement decisions

Protocols for Store-and-Forward Message Switching via Microsatellites

The authors have developed a suite of protocols specifically optimized for use on store-and-forward microsatellite communications missions. The protocols support networks in which user terminals directly access the store-and-forward satellite to transfer electronic mail. The authors\u27 PACSAT Protocol Suite includes a message format standard, a virtual-circuit directory and file transfer service, and a datagram based point-to-multipoint broadcast protocol. An implementation of this suite has been operating on the UoSAT-3 PACSAT Communications Experiment (PCE) for twelve months and on the AMSAT Microsats for seven months. During this period, hundreds of small and medium-sized ground terminals in all parts of the world have accessed the satellites. On-board software monitors network activity closely, and usage statistics for UoSAT-3 are gathered regularly at the UoSAT Command Station. Based on this data and the reported experiences of regular system users, we compare the effectiveness of the various protocols. From these comparisons we make some recommendations which are generally applicable to store-and-forward microsatellite missions. This paper describes the design of the PACSAT Protocol Suite and the UoSAT-3 and Microsat implementations. It summarizes the in-orbit performance results, and concludes with recommendations for future store-and-forward microsatellite missions

Single Event Upset Error Protection for Solid State Data Memory on Microsatellites

Many microsatellite missions rely upon large arrays of CMOS static RAM for data storage. Even a satellite with strict power and volume limitations can carry several Mbytes of SRAM. Experience has shown that these memory arrays are useful for scientific data collection image storage, store and- forward message switching and spacecraft telemetry monitoring. This paper describes the authors\u27 design and implementation of error protection codes which protect large CMOS RAM arrays from radiation-induced single event upsets

The UoSAT-C,D & E Technology Demonstration Satellites

The University of Surrey (UK) planned a small, inexpensive spacecraft (UoSAT-C) to be launched by NASA on a DELTA launch vehicle as a secondary payload into low-Earth orbit in 1989. This launch has been postponed, but the University has obtained two launch slots on ARIANE. Two spacecraft, UoSATs D & E are currently under construction at The UoSAT Spacecraft Engineering Research Unit at Surrey and they involve collaboration with international experimenters. The spacecraft will carry the majority of the payloads from the postponed UoSAT-C mission. UoSAT-D & E will established by the spacecraft launched NASA, develop further the objectives preceding UoSAT-1 and UoSAT-2 into low Earth, polar orbit by The paper describes the architecture and experiments of the satellite including: Satellite Communications using digital store-&-forward techniques serving remote and under-developed areas and the amateur radio community. Space Technology providing an in-orbit demonstration and operational evaluation of novel technologies and techniques such as transputers and solar cell evaluation. Space Science supporting sophisticated, yet inexpensive space science objectives studying the radiation environment in low Earth orbit such as Cosmic Particle Detection and Radiation Total Dose Measurement

Triply Threaded [4]Rotaxanes

[4]Rotaxanes featuring three axles threaded through a single ring have been prepared through active metal template synthesis. Nickel-catalyzed sp3-sp3 homocouplings of alkyl bromide ‘half threads’ through 37- and 38-membered 2,2':6',2"-terpyridyl macrocycles generates triply-threaded [4]rotaxanes in up to 11 % yield. An analogous 39-membered macrocycle produced no rotaxane products under similar conditions. The constitutions of the [4]rotaxanes were determined by NMR spectroscopy and mass spectrometry. Doubly-threaded [3]rotaxanes were also obtained from the reactions but no [2]rotaxanes were isolated, suggesting that upon demetallation the axle of a singly-threaded rotaxane can slip through a macrocycle that is sufficiently large to accommodate three threads

Characterisation of Kenana cattle at Um Banein, Sudan

Results of a study carried on the reproductive performance, herd management, weight & growth, milk production & mortality of Kenana cattle at Um Banein Livestock Research Station (Sudan)

Space Science and Microsatellites - A Case Study Observations of the Near-Earth Radiation Environment using the Cosmic-Ray Effects and Dosimetry (CREDO) Payload On-Board UoSAT-3

The University of Surrey\u27s technology demonstration microsatellite: UoSAT-3 launched in January 1990. carries on-board a Cosmic-Ray Effects and Dosimetry (CREDO) payload for characterizing the low-Earth orbit (LEO) radiation environment. Measurements made with this payload are correlated with radiation effects observed in the spacecraft\u27s microelectronics, in particular, the occurrence of single event upsets (SEUs) in solid-state memory devices. The CREDO payload consists of two Sub-systems, the Cosmic Particle Experiment (CPE) and the Total-Dose Experiment (TDE). The CPE houses an array of large-area PIN diode detectors, connected to a pulse-height analysis network. Particles incident on the detector are counted and logged according to their linear-energy transfer (LET). Results are integrated over five minute intervals and the data are stored in the PACSAT Communications Experiment (PCE) memory. The TDE consists of specially manufactured p-channel MOSFETs which are monitored for changes in threshold voltage due to accumulated radiation dose. During the first year\u27s operation, CREDO has provided measurements of the cosmic-ray background, the trapped particle population of the South Atlantic Anomaly (SAA), and has observed a number of large solar proton events - most recently, the major events of June 1991. This paper reviews the results obtained so far and comments on the suitability of microsatellites for this kind of small-scale space science mission

Branching Fractions and Transition Probabilities for UV Transitions in the Spectrum of Cr ii

We present transition probabilities for 268 spectral lines of singly ionized chromium (Cr ii) in the wavelength region 208-414 nm. Branching fractions were measured in archival Fourier transform spectra of chromium-argon and chromium-neon hollow cathode lamps and a Penning discharge source. The branching fractions were combined with previously published experimental lifetimes of 14 levels, and with lifetimes from semiempirical calculations for 14 levels to give transition probabilities. The estimated uncertainties of the transition probabilities range from 10% to 26%. A comparison with previously published experimental transition probabilities shows discrepancies of up to a factor of 2.5 for lines around 213 nm

The value of character-based judgement in the professional domain

Dimensions of character are often overlooked in professional practice at the expense of the development of technical competence and operational efficiency. Drawing on philosophical accounts of virtue ethics and positive psychology, the present work attempts to elevate the role of ‘good’ character in the professional domain. A ‘good’ professional is ideally one that exemplifies dimensions of character informed by sound judgement. A total of 2340 professionals, from five discrete professions, were profiled based on their valuation of qualities pertaining to character and judgement. Profile differences were subsequently examined in the self-reported experience of professional purpose towards a wider societal ‘good’. Analysis of covariance, controlling for stage of career, revealed that professionals valuing character reported higher professional purpose than those overweighting the importance of judgement or valuing neither character nor judgement, F(3, 2054) = 7.92, p < .001. No differences were found between the two groups valuing character, irrespective of whether judgement was valued simultaneously. This profiling analysis of entry-level and in-service professionals, based on their holistic character composition, paves the way for fresh philosophical discussion regarding what constitutes a ‘good’ professional and the interplay between character and judgement. The empirical findings may be of substantive value in helping to recognise how the dimensions of character and judgement may impact upon practitioners’ professional purpose