Throughout the trials and tribulations of the 1950s and 1960s, white anti-apartheid activists rose to the call of duty and took a stand against injustice, taking a stance that others refused to take. They threw themselves into the fire, serving jail sentences, going underground, and suffering great hardship as they separated from their families and friends. When imprisoned and exiled by the national government, they soldiered on, more resilient than ever. These activists provided an invaluable service to their country and to their fellow citizens of Africa, and many of their lives were forsaken for the cause. But above all, they achieved their aim: a free and democratic South Africa equal to all.
Factors such as shift work, sleep deprivation, and noise affect job performance in part because they affect individuals' levels of arousal. Recent work on arousal has identified two distinct forms of arousal that affect performance in very different ways. Tense arousal represents a continuum from calmness to anxiety, whereas energetic arousal reflects a continuum from tiredness to energy. The three studies reported here sought to determine the usefulness of breaking down energetic arousal still further, into dimensions of wakefulness and vigor. In the first study, a factor analysis of self-reported psychological state data determined that wakefulness and vigor did form separate factors. The second study found that the circadian rhythms of wakefulness and vigor differed; wakefulness increased over the day, whereas vigor peaked at noon. The third study examined the relationship between the two types of arousal and performance on a reading comprehension task. Although both wakefulness and vigor showed an association with performance, only vigor showed the inverted-U-shaped relationship embodied in the Yerkes-Dodson law. These data suggest that distinguishing between wakefulness and vigor will clarify how changes in arousal levels affect productivity. These results also suggest that the schedule for optimal performance of tasks depends on whether they are facilitated by either wakefulness or vigor.
The Grover-Counter Test (GCT) is evaluated for use with a group that has been neglected in terms of legislative provisions and services, as well as assessment procedures. Non-handicapped black scholars in racially segregated schools underperformed after the age of 7 years, and this finding is examined in detail. A construct validity study was conducted on a sample of mentally handicapped children using the Griffiths Scales of Mental Development (Griffiths) and the Draw-A-Man (DAM) test. Mental age scores and IQ range scores were used in the correlations with the GCT. The GCT was found to correlate most highly with the expected subscales on the Griffiths; other significant correlations also support the construct validity of the GCT. No difference in performance was found between children with and without language deficits on the GCT; the group with language deficits performed significantly lower on all the Griffiths subscales. Significant correlations were found between the GCT and the DAM. A criterion validity study found that the GCT predicted the level of functioning within the school. Inter-rater reliability and test-retest reliability was high. Detailed discussion is provided of the ethical issues raised by this research. Material from the clinical aspects of the research is presented, as very little documentation of clinical work with this group exists.
With the coalition's success at forcing Iraq out of Kuwait, the USA now faces one of its greatest challenges to peace since the end of World War II. Now that the war has ended, it remains unclear how the USA hopes to achieve regional stability in the Middle East. The author examines U.S. policy options in the Middle East with special reference to regional security arrangements in the Middle East, regional arms limitation, monitoring unconventional weapons development in the region, the issue of reviving the Middle East peace process among other topics. (DÜI-Sen)
Population dynamics and movements were investigated in a population of Pseudantechinus macdonnellensis, a dasyurid marsupial occupying rocky habitats in the Australian arid zone. Intra-annual cycling in abundance, activity and numbers of resident and transient individuals was not regular from year to year, although the number of residents was high compared with the number of transients. Juvenile recruitment varied between years and was as low as 18%. Densities were low (0.05–0.2 ha–1 for females and 0.05–0.3 ha–1 for males), and individuals exhibited large stable long-term ranges – mean Minimum Convex Polygon (MCP) area for males was 427 m2 and for females 171 m2. The constraints of the monoestrous, synchronised reproductive strategy of P. macdonnellensis, together with the ameliorating effect of its rocky habitat, which may decrease food limitation and increase survival, seem to have produced a different pattern of population dynamics to that seen in arid-zone dasyurids that are polyoestrous plains-dwellers. The patterns of movement in P. macdonnellensis also differ from plains-dwelling species, in which individuals display high life-time mobility. The existence of large but non-drifting ranges in P. macdonnellensis may be seen as a consequence of a low but relatively predictable food supply, which precludes the necessity for individuals to shift their activity to temporary patches of high food supply, but requires them to occupy a large range to obtain enough food to meet energy requirements.
Food preferences of two species of Australian desert rodents, the spinifex hopping-mouse (Notomys alexis) and the sandy inland mouse (Pseudomys hermannsburgensis), were investigated in cafeteria trials. Both species showed strong preference for invertebrate material (a beetle, Tenebrio molitor) over the seeds and stems of spinifex (Triodia basedowii), and fungus (Tulostoma sp.). This contrasts with previous reports that these rodents are granivores, and suggests instead that they may be omnivorous. Further investigation of the basis for food choice was carried out in a series of seed preference trials, and provided some indication that the water content of food items may underlie diet selection. We suggest that the ability of native rodents to eat a broad range of food types, particularly invertebrates, has promoted survival in arid regions that have been subjected to disturbance since European settlement.
A population of Rattus villosissimus was studied during an 18-month period in a sand-dune habitat in south-western Queensland. The population numbers fluctuated dramatically during this time. Increases in population numbers were due primarily to immigration, with reproduction playing a secondary role. Rain-induced increases in food availability are the most likely stimuli for these increases. The cause of population decline is not clear from this study, but predation and disease may be important factors. Radio-tracking showed that the spatial activity of the animals was concentrated on the sides of the dunes, and around burrows. Temporal activity is influenced by moonlight, with animals remaining in burrows for long periods of time on bright nights.
Small quantities of fluorescent pigments were tattooed into the pinnae of pouch young Dasyurus geoffroii and Isoodon obesulus (Marsupialia), and into the pinnae of 5-day-old Mus rnusculus (Rodentia). The tattoos contrasted sharply with natural skin pigmentation when scanned with a UV light. Of 11 pigments tested, Flare 610 pigments were the most persistent, remaining visible for a minimum of 6 months. The technique facilitates rapid, cheap and reliable marking of marsupial pouch young, and should be generally applicable for determining filial relationships in a wide range of marsupial species.
Context Central Australia has been a graveyard for native mammals, with many small and medium-sized species becoming extinct or persisting in reduced geographical ranges in this region since the advent of European settlement. Species in the critical weight range (35–5500 g) have been affected most dramatically.
Aims We compared the dynamics of two geographically distant populations of a medium-sized surviving desert mammal, the brush-tailed mulgara (Dasycercus blythi, ~100 g), and tested the hypothesis that this species' persistence can be explained by its demographic plasticity.
Methods Paired sampling grids, each 31.5 ha, were set up in the Tanami Desert on the northern edge of the species' geographical range and near Uluru Kata Tjuta National Park (UKTNP) on the southern boundary. Animals were live-trapped every 3 months between 1992 and 1995, and estimates made of population size, residency, reproduction, bodyweight and tail width; the latter was used as an index of condition.
Key results The UKTNP site supported a larger population of D. blythi than did the Tanami Desert site. In both areas, the population fluctuated annually, declining during the breeding season (June to October) and increasing again following the influx of juveniles in spring. Females had one litter per year, with a median and maximum litter size of six; births in the Tanami occurred in July, at least a month earlier than they did at UKTNP. Bodyweights and tail widths peaked before breeding and then declined until spring, with animals retaining better body condition in the Tanami than at UKTNP. In both regions, individuals were resident for 1–2 years; daughters remained near their mother's home range but males moved to other areas.
Conclusions The results provided little support for our initial expectation that populations of D. blythi would behave differently in disparate parts of the species' geographical range, and suggested instead that this mulgara exhibits a predictable life history, with limited demographic flexibility.
Implications The persistence of D. blythi in central Australia is most likely a result of its striking flexibility in use of food resources, its ability to enter torpor and to tolerate large declines in bodyweight and condition, and its propensity to dig deep burrows. We suggest that these attributes buffer mulgaras from the impacts of introduced predators that have contributed to extinctions of other medium-sized marsupials, and from climatic and resource uncertainties that shape the dynamics of many smaller desert mammals.
