Mach bands change asymmetrically during solar eclipses

Observations made during two partial eclipses of the Sun show that the Mach bands on shadows cast by the Sun disappear and reappear asymmetrically as an eclipse progresses. These changes can be explained as due to changes in the shape of the penumbras of shadows as the visible portion of the Sun forms crescents of different orientation.     

Comparative assessment of handedness for a coordinated bimanual task in chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus)

Hand preferences for a coordinated bimanual task were assessed in a sample of 31 captive gorillas (Gorilla gorilla) and 19 captive orangutans (Pongo pygmaeus) and were compared with chimpanzee (Pan troglodytes) hand preferences in subjects that were matched on the basis of age, sex, and rearing history. The task required that the apes remove food from the inside edges of a symmetrical polyvinyl chloride pipe presented to them in their home cages. The results indicate significant species differences with chimpanzees showing population-level right-handedness and orangutans showing population-level left-handedness. The gorillas showed a nonsignificant trend toward right-handedness. The results are discussed in terms of possible ecological or biomechanical factors that may influence hand preferences in different ape species.     

Should smallpox vaccine be made available to the general public?

In June 2002, the Advisory Committee on Immunization Practices (ACIP) approved draft recommendations concerning preparation for potential biological terror attacks that utilize the smallpox virus. ACIP recommends against both mandatory and voluntary vaccination of the general public. The present paper examines the moral and political considerations both for and against each of the general public vaccination options considered by the ACIP in the context of the state's authority over vaccination for the purposes of protecting public health. Although it is clear that compulsory mass vaccination is not justified at this time, the issues surrounding voluntary vaccination are more complex. Should smallpox vaccination prior to an outbreak be made available to the general public? The paper concludes that the vaccine should not be made available at this time. This conclusion, however, is based upon contingent features of current circumstances, which would change once an outbreak occurred. In the even of a terror-related outbreak of smallpox, the general public's access to voluntary vaccination would become justified, even in areas beyond where the outbreak has occurred.     

Cooling blocks ITM and LTM formation and preserves memory

In Lymnaea aerial respiratory behaviour can be operantly conditioned; snails learn not to perform this behaviour. Depending on the training procedure used, snails are competent to form either intermediate-term (ITM; lasting 1-3 h) or long-term (LTM; >4 h) memory. We found that cooling the snails for 1 h immediately after training was sufficient to block either ITM or LTM. Cooling snails for a similar period 10 or 15 min after cessation of training, failed to block ITM and LTM formation, respectively. Finally, we employed the cooling technique to extend both ITM and LTM. That is, cooling could prevent forgetting. Cooling extended LTM that normally persisted for 2 days to at least 8 days. These data are consistent with the hypothesis that forgetting is due to the learning and remembering of interfering events, and thus is an active process.     

The ethical limits in expanding living donor transplantation

The past decade has witnessed the emergence of novel methods to increase the number of living donors. Although such programs are not likely to yield high volumes of organs, some transplant centers have gone to great lengths to establish one or more of them. I discuss some of the ethical and policy issues raised by five such programs: (1) living-paired and cascade exchanges; (2) unbalanced living-paired exchanges; (3) list-paired exchanges; (4) nondirected donors; and (5) nondirected donors catalyzing cascade exchanges. I argue that living-paired and cascade exchanges are ethically sound, but will lead to only a few additional transplants. Unbalanced exchanges and list-paired exchanges raise ethical issues that should limit their permissibility. Nondirected donations can be ethically sound with adherence to strict eligibility criteria and fair allocation procedures. Nondirected donors catalyzing cascade exchanges can be ethically sound provided that individuals with blood types O and B are not made worse off.     

Reach and posture hand preferences during arboreal feeding in Sifakas (Propithecus sp.): a test of the postural origins theory of behavioral lateralization

Sixteen sifakas (11 Propithecus verreauxi coquereli, 2 Propithecus verreauxi verreauxi form majori, and 3 Propithecus tattersalli) were videotaped as they fed on leaves in an arboreal context. The hand used to feed and the hand used to maintain postural stability was coded. For each subject, the lateral bias of the hand used to feed was opposite the hand used in postural support. Seven sifakas displayed no bias for feeding or posture-related hand use, 7 sifakas displayed significant feeding-related reach preferences for pulling branches to the mouth (5 left- and 2 right-hand preferences), and 9 sifakas exhibited significant hand preferences for postural support (2 left-, 7 right-hand preferent). Although these data do not strongly support the postural origins theory of behavioral lateralization, the modal preference pattern for sifakas that displayed significant hand preferences for posture and feeding involve a left bias for feeding and a right bias for postural support. s reserved).     

The two faces of typicality in category-based induction

Studies of category-based induction using different methods have found somewhat contradictory results for whether typical items are a stronger basis for induction. Typical category items are generally more similar to other category items than are atypical ones, and they are also more likely to be categorized into the category in question. We propose that the first aspect (representativeness) influences induction, but the second (uncertainty about the correct category) does not. Two experiments using artificial categories found support for this prediction. Two further experiments manipulated pictures of objects and also found that representativeness in the category influenced the strength of induction, but uncertainty of classification did not. Thus, the two aspects of typicality have different effects on category-based induction.     

The cultural mind: environmental decision making and cultural modeling within and across populations

This article describes cross-cultural research on the relation between how people conceptualize nature and how they act in it. Mental models of nature differ dramatically among populations living in the same area and engaged in similar activities. This has novel implications for environmental decision making and management, including common problems. The research offers a distinct perspective on cultural modeling and a unified approach to studies of culture and cognition. The authors argue that cultural transmission and formation consist primarily not in shared rules or norms but in complex distributions of causally connected representations across minds interacting with the environment. The cultural stability and diversity of these representations often derive from rich, biologically prepared mental mechanisms that limit variation to readily transmissible psychological forms. This framework addresses several methodological issues, such as limitations on conceiving culture to be a well-defined system, bounded entity, independent variable, or an internalized component of minds.     

Inference and classification learning of abstract coherent categories

Category learning research has primarily focused on how people learn to classify items using simple observable features. However, classification is only 1 way to learn categories. In addition, many concepts have an underlying coherence that explains the featural similarity among exemplars, such as abstract coherent concepts whose instances differ greatly on their observable features. In 3 experiments, the authors investigated how abstract coherent categories are acquired through 2 common means of category learning, classification and inference. Because inference promotes more focus on within-category information than does classification, they hypothesized that inference learning would lead to a better understanding of the underlying coherence of abstract coherent categories. All 3 experiments support this prediction.     

Client perspectives and open-ended questions: a reply to Dean, et al. (2000)

Utilizing an open-ended question may allow subjects to respond in their own words but does not necessarily avoid the problem of narrowing the focus to a specific predetermined topic.