Is It Rational to Assume that Infants Imitate Rationally? A Theoretical Analysis and Critique

It has been suggested that preverbal infants evaluate the efficiency of others' actions (by applying a principle of rational action) and that they imitate others' actions rationally. The present contribution presents a conceptual analysis of the claim that preverbal infants imitate rationally. It shows that this ability rests on at least three assumptions: that infants are able to perceive others' action capabilities, that infants reason about and conceptually represent their own bodies, and that infants are able to think counterfactually. It is argued that none of these three abilities is in place during infancy. Furthermore, it is shown that the idea of a principle of rational action suffers from two fallacies. As a consequence, is it suggested that it is not rational to assume that infants imitate rationally. Copyright (C) 2012 S. Karger AG, Base

Past and present distribution, densities and movements of blue whales <i>Balaenoptera musculus</i> in the Southern Hemisphere and northern Indian Ocean

1Blue whale locations in the Southern Hemisphere and northern Indian Ocean were obtained from catches (303 239), sightings (4383 records of =8058 whales), strandings (103), Discovery marks (2191) and recoveries (95), and acoustic recordings.2Sighting surveys included 7 480 450 km of effort plus 14 676 days with unmeasured effort. Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggregations of unassociated individuals were only rarely observed. Sighting rates (groups per 1000 km from many platform types) varied by four orders of magnitude and were lowest in the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia; higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile, southern Australia and south of Madagascar.3Blue whales avoid the oligotrophic central gyres of the Indian, Pacific and Atlantic Oceans, but are more common where phytoplankton densities are high, and where there are dynamic oceanographic processes like upwelling and frontal meandering.4Compared with historical catches, the Antarctic (‘true’) subspecies is exceedingly rare and usually concentrated closer to the summer pack ice. In summer they are found throughout the Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare) and to other northerly locations (based on acoustics), although some overwinter in the Antarctic.5Pygmy blue whales are found around the Indian Ocean and from southern Australia to New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand northwards to the equator. Sighting rates are typically much higher than for Antarctic blue whales.6South-east Pacific blue whales have a discrete distribution and high sighting rates compared with the Antarctic. Further work is needed to clarify their subspecific status given their distinctive genetics, acoustics and length frequencies.7Antarctic blue whales numbered 1700 (95% Bayesian interval 860–2900) in 1996 (less than 1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4–11.6%). The status of other populations in the Southern Hemisphere and northern Indian Ocean is unknown because few abundance estimates are available, but higher recent sighting rates suggest that they are less depleted than Antarctic blue whales.</li

Southern right whale (Eubalaena australis), seasonal abundance and distribution at Head of Bight, South Australia

© 2019 John Wiley & Sons, Ltd. Seasonal trends in the distribution and relative abundance of southern right whales (SRWs) Eubalaena australis, were assessed in Australia's largest calving aggregation ground at the Head of the Great Australian Bight, in the Commonwealth Marine Reserve, South Australia. Annual cliff-based surveys were undertaken between June and October from 1992 to 2016. SRWs were primarily distributed in a 15 km by 2 km area within the 10 m depth contour (with 95% of whale sightings made within a 10 km2 area). The distribution of SRWs at Head of Bight varied within an individual season but was consistent among the years. The composition of SRW sightings was 70% female–calf pairs and 30% unaccompanied whales. Peak abundance occurred between mid-July and end-August for female–calf pairs and unaccompanied whales (juveniles or adults not accompanied by a calf), earlier than previously reported. A mean of 16% (range 8–28%, SD = 6.5, 95% CI = 0.15) of calving females were present at the site in mid-June and a mean of 37% (range 13–61%, SD = 15.8, 95% CI = 0.37) remained at the site at the end of September. Based on nearest-neighbour distances of 150 m, the area occupied by 95% of SRWs at Head of Bight could reach carrying capacity at 68 female and calf pairs. Results suggest that the primary aggregation area at Head of Bight may have reached saturation capacity and that habitat expansion can be expected as the population increases. This study provides information on SRW seasonal trends in distribution and abundance, timing of arrival and departure from the site and peak abundance periods relevant to application to conservation and marine park management. As management requirements increase with a growing population, there is a need to complete an Australia-wide assessment of SRW connectivity and habitat expansion

Design, testing and modeling of a high-gain magnetic flux-compression generator

Using a simultaneously initiated cylindrical explosive, a coaxial magnetic flux-compression generator (FCG) was designed to test high-current-gain limitations. A coaxial design with a lossless gain of approx.100:1 was chosen for its efficiency, relative simplicity, and calculability. Theoretical design included modeling as well as 1-D and 2-D hydrodynamic and MHD calculations. A 69.3-cm cylinder of PBX-9501 high explosive, 20.3 cm in diameter, was used to drive the Al armature into a Cu stator. The initial current supplied by a capacitor bank was approx.3 MA which produced a final current approx.75 MA. Details of the experiment and a comparison with calculations are presented

Genetic variation in blue whales in the Eastern Pacific: implication for taxonomy and use of common wintering grounds

Many aspects of blue whale biology are poorly understood. Some of the gaps in our knowledge, such as those regarding their basic taxonomy and seasonal movements, directly affect our ability to monitor and manage blue whale populations. As a step towards filling in some of these gaps, microsatellite and mtDNA sequence analyses were conducted on blue whale samples from the Southern Hemisphere, the eastern tropical Pacific (ETP) and the northeast Pacific. The results indicate that the ETP is differentially used by blue whales from the northern and southern eastern Pacific, with the former showing stronger affinity to the region off Central America known as the Costa Rican Dome, and the latter favouring the waters of Peru and Ecuador. Although the pattern of genetic variation throughout the Southern Hemisphere is compatible with the recently proposed subspecies status of Chilean blue whales, some discrepancies remain between catch lengths and lengths from aerial photography, and not all blue whales in Chilean waters can be assumed to be of this type. Also, the range of the proposed Chilean subspecies, which extends to the Galapagos region of the ETP, at least seasonally, perhaps should include the Costa Rican Dome and the eastern North Pacific as well