“Realism” and “relevance” in gaming simulations

How useful are gaming simulations for the study of problems that interest human ecologists? Anatol Rapoport, a principal contributor to the development of game theory, raised this issue with the editors of Human Ecology,who in turn invited him to express his views in print. In brief, Dr. Rapoport calls into question the real-world applicability of gaming simulations, and explores its limitations. The educational function of simulation, he argues, should not be confused with the research aims of laboratory experimentation. The addition of “realistic” conditions in a gaming simulation merely complicates the experiment and reduces its theoretical significance. It does, however, have some pedagogical utility, whose implications have not yet been adequately taken into account. Dr. Rapoport considers this matter with reference to the problem of “social traps,” such as the “tragedy of the commons,” an issue which concerns many human-ecology researchers.     

“Sicca Complex” in Liver Disease

Sixty-three patients with liver disease were studied for the presence of the components of Sjögren''s syndrome. The “sicca complex” (that is, patients without arthritis) was detected in 42% of patients with active chronic hepatitis, 72% with primary biliary cirrhosis, and 38% with cryptogenic cirrhosis. One patient with active chronic hepatitis and one with primary biliary cirrhosis had rheumatoid arthritis. No evidence of Sjögren''s syndrome was detected in seven patients with alcoholic cirrhosis. It is suggested that the sicca complex and autoimmune liver disease may be part of a systemic disorder in which immunological mechanisms are concerned in the pathogenesis.     

“Costs” of reproduction in reptiles

Summary Many theoretical models of life-history evolution rely on the existence of trade-offs between current fecundity and probable future fecundity and survival. Such costs of reproduction have been demonstrated only rarely. Field and laboratory studies on six species of Australian scincid lizards show that gravid females are more vulnerable to predation than are non-gravid females, primarily because (i) they are physically burdened (running speeds are reduced by 20 to 30%), and (ii) they bask more often (in some species). However, food intake is not reduced in gravid animals. A review of published literature suggests that reproductive trade-offs are widespread among reptiles, but the nature of the reproductive costs may vary widely among related species. Within the range of annual survivorship rates of most lizard species, trade-offs between fecundity and survival are likely to be the main evolutionary determinants of optimal levels of reproductive effort. Trade-offs between fecundity and bodily growth are less likely to be significant.     

Numbers in the Blind's “Eye”

Background

Although lacking visual experience with numerosities, recent evidence shows that the blind perform similarly to sighted persons on numerical comparison or parity judgement tasks. In particular, on tasks presented in the auditory modality, the blind surprisingly show the same effect that appears in sighted persons, demonstrating that numbers are represented through a spatial code, i.e. the Spatial-Numerical Association of Response Codes (SNARC) effect. But, if this is the case, how is this numerical spatial representation processed in the brain of the blind?

Principal Findings

Here we report that, although blind and sighted people have similarly organized numerical representations, the attentional shifts generated by numbers have different electrophysiological correlates (sensorial N100 in the sighted and cognitive P300 in the blind).

Conclusions

These results highlight possible differences in the use of spatial representations acquired through modalities other than vision in the blind population.     

“Theory” in Theory and Practice

A central obstacle to accepting evolution, both among students and the general public, is the idea that evolution is “just a theory,” where “theory” is understood in a pejorative sense as something conjectural or speculative. Although scientists and textbooks constantly explain that the scientific use of “theory” is quite different, the pejorative use continues to cause confusion, in part because of its deep roots in a popular, Baconian, understanding of science. A constructivist approach, whereby students are helped to examine the adequacy of their preconceptions about “theory” for themselves and to revise or replace them appropriately, is recommended.     

“Ischaemic” Colitis in Young Adults

Four cases of transient haemorrhagic colitis seen in young adults resemble 10 others in the literature. The 14 cases are distinguished from the classical transient ischaemic colitis syndrome by their youth, the low incidence of stricture formation, and the prevalence of right-sided lesions.     

“Sensory Switching” in Elbow Reconstruction

In the treatment of the soft tissue defect of the elbow, flap reconstruction is necessitated in many cases because of thinness of soft tissue at this region. In addition, reacquirement of tactile sensation is desirable because of the anatomical and specific functions of the elbow. Of three cases treated for elbow defects, one was reconstructed with a pedicled island forearm flap containing the lateral cutaneous nerve of the forearm, another was reconstructed with a venoneuro-accompanying artery fasciocutaneous flap (VNAF flap) containing the basilic vein, and the third with the VNAF flap containing the cephalic vein. The three cases demonstrated a sudden change of sensory territory 4 to 6 months after surgery, which was confirmed by touching the reconstructed region with patients'' eye-closed: from its original territory to the elbow in a “switching”-like action. Here we describe and discuss the concept of “sensory switching.”     

Examination “Selection Pressures” in Biology

Class Work with Fungi. H. A. DADE and JEAN GUNNELL. Pp. 64. London: Commonwealth Mycological Institute, Kew. 1969. 10s. Review by B. M. Jones

The Insects: Structure and Function. R. F. CHAPMAN. Pp. xiii + 819 + 509 figs. London: The English Universities Press Ltd., 1969. £4.25. Review by T. G. Onions

An Introduction to the Principles of Plant Physiology. WALTER STILES and E. C. COCKING. Pp. 633. London: Methuen &; Co., Ltd. Third edition, 1969. 168s. Review by B. M. Jones

Background Notes to the Study of Human Biology for Nurses. T. ROBERTS. Pp. 80. London: Edward Arnold. Semistiff Back, 10s. (50p.). Review by J. H. Elliott     

“Micronucleoli” in theXenopus germinal vesicle

The germinal vesicle of the Xenopus oocyte contains 1500 or more extrachromosomal nucleoli that are assembled on amplified copies of the rRNA genes. Many of these nucleoli have diameters of 10–15 μm, but some are much smaller, ranging down to 1 μm or less. Morphologically the smaller nucleoli or ”micronucleoli” resemble the similarly sized B snurposomes, but they can be recognized with appropriate antibody probes (e.g., anti-nucleolin and anti-fibrillarin). We describe here a sensitive fluorescent staining technique that uses avidin and propidium iodide to visualize the rDNA in the amplified nucleoli. Many large nucleoli stain about as brightly as haploid yeast nuclei on the same slides. They presumably contain about 12 Mb of DNA, equivalent to 900 rDNA repeats. The smallest micronucleoli display only a tiny dot of stain, which must correspond to relatively few rDNA repeats. Received: 8 January 1997; in revised form: 20 January 1997 / Accepted: 27 January 1997     

Interneurones participating in the “active reaction” in stick insects

The active reaction upon stimulation of the femoral chordotonal organ in stick insects is known to control velocity and endpoint of flexion movements of the femur-tibia joint (Bässler 1988). This article presents evidence that spiking interneurones in the ventral anterior median part of the adjacent ganglion participate in the generation of the active reaction as well as non-spiking interneurones in the dorsal lateral region do. Three different kinds of experiments lead to this conclusion:

Frequency of mutations in “thrombophilic state” genes in Uzbekistan

The frequency of mutations in a number of genetic markers, specifically factor V gene (G1691A), blood coagulation factor II gene (G20210A), and the methylenetetrahydrofolate reductase (MTHFR) gene (C677T), is studied in ethnic Uzbek patients with deep vein thrombosis of the lower extremities and in healthy donors. It is established that the incidence of mutant alleles among patients in Uzbekistan for FV Leiden is 12.9%; for prothrombin, 4%; and for MTHFR, 47.8%. The mutant allele C677T of the MTHFR gene has the highest expressivity in the appearance of MTHFR (47.8%). It is noted that this mutation in the MTHFR gene is encountered significantly more frequently in females with deep vein thrombosis than in males with deep vein thrombosis. The G20210A mutation in the prothrombin gene is encountered more rarely in the Uzbek population. The penetrance is studied and the role of these mutations in the appearance of deep vein thrombosis is estimated.     

The “efferent copy” hypothesis in saccadic programming in cats

Eye movements were investigated in cats while following a visual target. Wire coils implanted into the eyes served as transducers; the animal was placed in a revolving magnetic field (the magnetic search coil technique). The linear nature of amplitude-velocity relationships in saccadic eye movements was demonstrated. With combined head and eye movements, slope of plot was unrelated to maximum velocity of head movement over the entire test range (of up to 250 deg/sec); saccades decelerated when the head was immobile. Duration of gaze shift rose as it increased in amplitude. Amplitude of gaze was found to depend on head velocity. Experimentally obtained data on the interaction between head and eye movements when combined in following a target may be interpreted from the aspect of a mechanism operating to suppress saccadic signals by an efferent copy signal for head movement.M. V. Lomonosov State University, Moscow. Translated from Neirofiziologiya, Vol. 20, No. 5, pp. 631–637, September–October, 1988.     

Thiamine requirement in relation to cytokinin in “normal” and “mutant” strains of tobacco callus

Summary High concentrations of kinetin (400–2,000 g/l) permit continuous growth of tobacco callus cultures (Nicotiana tabacum, var. Wisconsin No. 38) in the absence of exogenous thiamine. On the optimum concentration (1,000 g/l) the tissue has been maintained through 21 bimonthly passages without change in vigor or other growth characteristics.The effect of kinetin is general, not mutagenic, because tissue returned to low-kinetin, thiamine-free medium failed to grow.Kinetin-thiamine interactions in cytokinin mutant strains which were grown without cytokinin in light and darkness suggest that the endogenous content of cytokinins may markedly affect the requirement for thiamine and possibly the tissue content of this vitamin and other growth factors.The viability of tissue on low-kinetin media in enhanced by thiamine, but the addition of this vitamin does not eliminate the requirement for a cytokinin.The great divergence in minimum kinetin concentrations required for growth of the tissue in the presence and absence of thiamine indicates that the growth promoting action of cytokinin must be different in the two cases.     

Continuation of Dabigatran Therapy in “Real-World” Practice in Hong Kong

Background

Dabigatran, an oral direct thrombin inhibitor, possesses several advantages over warfarin that can in principle simplify the management of stroke prevention in atrial fibrillation (AF). Nonetheless it remains unclear whether these advantages can translate to clinical practice and encourage long-term therapy. The objective was to describe long-term dabigatran therapy for stroke prevention in AF and to identify risk factors for discontinuation of therapy.

Methods and Results

We studied 467 consecutive Chinese patients (72±11 years, male: 53.8%) with a mean CHA₂DS₂-VASc score of 3.6 prescribed dabigatran for stroke prevention in AF from March 2010 to September 2013. Over a mean follow-up of 16 months, 101 patients (21.6%) permanently discontinued dabigatran. The mean time-to-discontinuation was 8 months. The most common reason for discontinuation was dyspepsia (30.7%), followed by other adverse events (17.8%) such as minor bleeding (8.9%), major gastrointestinal bleeding (7.9%), and intracranial hemorrhage (1%). Other reasons included dosing frequency (5.9%), fear of side effects (4.0%), lack of laboratory monitoring (1.0%), and cost (1.0%). Multivariable analysis revealed that low baseline estimated glomerular filtration rate (p = 0.02), absence of hypertension (p = 0.01), and prior use of a proton-pump inhibitor (p = 0.02) and H₂-receptor blocker (p = 0.01) were independent predictors of drug discontinuation. In addition, there were altogether 9 ischemic strokes (1.5%/years), 3 intracranial hemorrhages (0.5%/year), and 24 major gastrointestinal bleedings (4.1%/year).

Conclusion

Dabigatran discontinuation is very common amongst Chinese AF patients. This reveals a management gap in the prevention of stroke in AF.     

Variation in the fixation image of “Structured granules” in Anabaena

Summary The varied appearance of so-called structured granules in vegetative cells and akinetes of Anabaena sp. is dependent upon the length of primary glutaraldehyde fixation, the type and duration of secondary fixation, and the temperature during both fixations as well as possible changes under electron bombardment. The image produced may be one of an open hole, an area of low to medium electron opacity or that of a dense structured body and may include all intergradations. These structured granules represent the cyanophycin granules of light microscopy. Various cytochemical tests did not establish their chemical composition.     

Premeiosis and meiosis in Lilium “Enchantment”

Various aspects of premeiosis and meiosis in Lilium Enchantment are described. There was evidence of a premeiotic slow-down but no cells in premeiotic despiralization were observed. A relationship was found between sequence of bud development, or reproductive age of the individual, and degree of preleptotene chromosome contraction. The sequence of development of microsporocytes in the anther differed from the apex-to-base order previously reported in Lilium and, in contrast to observations in L. longiflorum cultivars, the maximum degree of preleptotene contraction was found in basal, last developing microsporocytes. Delayed despiralization of telophase nuclei was observed. There were extremely rare cells in meiotic division in anthers in which all other archesporial cells had not yet reached premeiotic interphase. Extreme variation was observed among anthers in proportions of microsporocytes in mid-stages of meiosis as well as in preleptotene contraction. These observations are discussed in relation to meiosis readiness, meiotic behavior in early and late developing regions of reproductive organs and in aging individuals, synchrony of meiotic development and rates of meiotic division.