Movements

1. Single motor unit spike trains have been recorded during voluntary isometric contraction of the affected intrinsic hand muscles of patients with unilateral central nervous lesions. These have been compared with similar recordings made from the patients' unaffected hand muscles and with recordings made from the hand muscles of healthy subjects. 2. Cross-correlation analysis was performed between the times of occurrence of the motor unit spike trains. The time course of central cross-correlogram peaks constructed for normal subjects and stroke patients was used to infer properties of the underlying common EPSPs and the impulse-generating properties of the motoneurones. The results of this analysis were compared between the two groups. In addition, the size and time course of cross-correlogram peaks obtained from the patients were related both to the patients' clinical state and to their hand and fine finger function. 3. Central nervous lesions were found to result in either...

Sixty-eight yellowfin tuna, Thunnus albacares, (60-135 cm fork length) were caught and released with implanted archival tags offshore off Baja California, Mexico, during October 2002 and October 2003. Thirty-six fish (53%) were recaptured and the data were downloaded from all 36 recovered tags. Time at liberty ranged from 9 to 1,161 days, and the data were analyzed for the 20 fish that were at liberty for 154 or more days. The accuracy in the position estimates, derived from light-level longitude data and sea-surface temperatures (SSTs) based latitude, is about 0.41° in longitude and 0.82° in latitude, in this region. The movement paths, derived from position estimates, for the 20 yellowfin indicated that 19 (95%) remained within 1,445 km of their release locations. The estimated mean velocity along movement paths was 77 km/day. The southern and northern seasonal movement paths observed for yellowfin off Baja California are influenced by the seasonal movements of the 18°C SST isotherm. Cyclical movements to and from suitable spawning habitat (≥24°C SST) was observed only for mature fish. For the 12 fish that demonstrated site fidelity, the mean 95 and 50% utilization distributions were 258,730 km2 and 41,260 km2, respectively. Evaluations of the timed depth records resulted in discrimination of four distinct behaviors. When exhibiting type-1 diving behavior (78.1% of all days at liberty) the fish remained at depths less than 50 m at night and did not dive to depths greater than about 100 m during the day. Type-2 diving behavior (21.2% of all days at liberty) was characterized by ten or more dives in excess of 150 m during the day. Type-2 diving behavior is apparently a foraging strategy for fish targeting prey organisms of the deep-scattering layer during the day, following nighttime foraging within the mixed layer on the same prey. Yellowfin tuna exhibited occasional deep-diving behavior, and some dives exceeded 1,000 m, where ambient temperatures were less than 5°C. Surface-oriented behavior, defined as the time fish remained at depths less than 10 m for more than 10 min, were evaluated. The mean number and duration of surface-oriented events per day for all fish was 14.3 and 28.5 min, respectively. Habitat utilization of yellowfin, presented as monthly composite horizontal and vertical distributions, indicates confined geographical distributions, apparently resulting from an affinity to an area of high prey availability. The vertical distributions indicate greater daytime depths in relation to a seasonally deeper mixed layer and a greater proportion of daytime at shallower depths in relation to a seasonally shallower mixed layer.

The distribution and diet of the elephants of the Maputo Elephant Reserve were studied using dung counts, satellite tracking and faecal analysis. The results were compared with earlier data from before the civil war in Mozambique. The elephant population decreased during the civil war, but 180 animals still remain. Earlier studies described the elephants as preferring the grass plains. Currently, the elephants prefer the dense forest patches over the high quality forage found in the grass plains. Water salinity affected distribution; elephant dung piles were found closer to fresh water in the dry season. A total of 95 different plant species were identified in the faeces. The percentage of grass was relatively low compared with other studies, increasing at the beginning of the rainy season. At the end of the dry season, elephants concentrated on the few available browse species with young leaves, but generally preferred grass species to browse species. Diet composition was mainly affected by season and less by habitat. The elephants have changed their habitat preference in reaction to poaching, and probably increased the contribution of browse species in the diet. The presence of forest patches has been vital for the survival of the elephants.RésuméOn a étudié la distribution et le régime alimentaire des éléphants de la Réserve áéléphants de Maputo en utilisant le comptages des crottes, le tracking par satellite et l'analyse des excréments. On a comparé les résultats avec des données recueillies avant la guerre civile au Mozambique. La population d'éléphants a baissé pendant la guerre civile mais il reste 180 animaux. Des études antérieures montraient que les éléphants préféraient les plaines herbeuses. Actuellement, ils préfèrent les ı^lots de forêt dense au fourrage de haute qualité qui se trouve dans les plaines herbeuses. La salinité de l'eau modifie la distribution; on trouvait les crottes d’éléphants plus près de l'eau douce en saison sèche. On a identifié un total de 95 espèces végétales différentes dans les excréments. Le pourcentage d'herbes était relativement bas par rapport aux études antérieures, il augmentait au début de la saison des pluies. A la fin de la saison sèche, les éléphants se concentraient sur les quelques espèces de buissons comestibles ayant des jeunes feuilles, mais ils préféraient généralement les espèces herbeuses aux buissons. La composition du régime était surtout affectée par la saison et moins par l'habitat. Les éléphants ont changé leurs préférences en matière d’habitat en réaction au braconnage et ont sans doute ainsi augmenté la contribution des espèces buissonnantes dans le régime alimentaire. La présence des ı^lots forestiers a été vitale pour la survie des éléphants.

Movement patterns of Alaska harbor seal pups were studied using satellite telemetry during 1997–2000. Mean tracking duration was 277.3 d (SD = 105.8) for Tugidak Island pups (n= 26) and 171.2 d (108.3) for Prince William Sound (PWS) pups (n= 27). Movements were similar for males and females and were largely restricted to the continental shelf. Multiple return trips of > 75 km from the natal area and up to ∼3 wk duration were most common, followed by movements restricted to <25 km from the natal area; one way movements from the natal site were rare. Distances moved and home range sizes remained relatively stable or increased gradually from July through winter, then decreased markedly through spring. Monthly movements (maximum distance from tagging location, mean distance from haul-outs to at-sea locations, and home range size) were significantly greater for Tugidak vs. PWS pups. Six of seven pups from each region that traveled farthest and were tracked the longest had returned to their tagging site when their last location was recorded, indicating philopatry or limited dispersal during their first year of life. Seal pups exhibited similar movement patterns in the distinct habitats of the two regions, but differed in the spatial extent of their movements.

The biology of small marsupials is poorly known because most species are nocturnal and arboreal. Using the spool-and-line device, we investigated the use of vertical space by male and female Marmosops incanus in the Serra dos Órgãos National Park. Diameter and slopes of supports also were compared. The species was sexually dimorphic in body size, males weighing on average 72.6 g and females 48.1 g, but males and females did not differ in the frequency of ground movements (GM) and understory movements (UM), or in diameter and slopes of supports used. Males and females also used the forest strata similarly, moving 67% on the ground and 33% in the understory. Both sexes used 0.9–1.7 cm support diameters, and support slopes near the horizontal (more than 50% of cases), but preferred to access a given height by moving on high slope supports (mostly near 90°). Sexual dimorphism in body size does not seem to constrain movements of M. incanus.Die Biologie kleiner Beuteltiere ist wenig bekannt, da die meisten Arten nachtaktiv und arboreal sind. Mittels der Spool-and-Line-Methode wurde die vertikale Raumnutzung von männlichen und weiblichen Tieren der Art Marmosops incanus im Serra-dos-Órgãos-Nationalpark untersucht. Durchmesser und Neigung der genutzten tragenden Strukturen wurden verglichen. Die Art zeigte geschlechtsspezifische Gewichtsunterschiede: Männchen wogen durchschnittlich 72.6 g, Weibchen im Durchschnitt 48.1 g. Die Geschlechter unterschieden sich jedoch nicht hinsichtlich der Aufenthaltsfrequenz am Boden oder im Unterholz und auch nicht bezüglich Durchmesser und Neigung sie tragender Strukturen. Sowohl Männchen als auch Weibchen verbrachten ca. zwei Drittel der Zeit am Boden und ein Drittel im Unterholz. Der Geschlechtsdimorphismus in der Körpergröße bei M. incanus scheint demnach keine Auswirkungen auf die Bewegungen oder Beweglichkeit zu haben.