Historic Salvage Law Revisited

Litigation involving the R.M.S. Titanic highlights the critical need for a more stable legal regime to protect shipwrecks, their cargo, and other aspects of underwater cultural heritage. The general maritime law, as articulated by admiralty courts in the United States, has begun to qualify salvage awards in terms of compliance with archaeological standards. Salvage law, however, does not provide language and rules readily applicable to historic wreck and related material. We are, therefore, in a period of transition between a heavy reliance on the common law of "treasure" salvage and the development of a truly general, universal regime to govern underwater heritage. At the center of this development is the Draft UNESCO Convention on the Protection of the Underwater Heritage, based upon the Buenos Aires Draft Convention of the International Law Association. The emerging regime of conventional law provides authority, bases of jurisdiction and other forms of international cooperation, to enforce a set of rules for protection and scientific management of heritage. Critical issues await further negotiations, including the definition of protected heritage, an accommodation of commercial salvage interests within the prescribed conservation and management standards, the status of warships, and the terms of coastal state jurisdiction within the permissible limits of the 1982 UNCLOS.     

The U.S.-Led Proliferation Security Initiative and UNCLOS: Legality,Implementation, and an Assessment

This article examines the relationship between the U.S.-led Proliferation Security Initiative (PSI) and the 1982 United Nations Convention on the Law of the Sea (UNCLOS). It attempts to answer the questions of whether the PSI is legal or illegal under UNCLOS and whether U.S. accession to UNCLOS would enhance or create difficulties for the implementation of the PSI. The author concludes that U.S. accession to the Convention would not affect adversely the implementation and effectiveness of the PSI. On the contrary, accession to UNCLOS could help increase U.S. credibility and leadership in dealing with the threat to international peace and security posed by weapons of mass destruction proliferation. It also suggests that all the relevant information needs to be gathered and examined carefully in order to answer the question of whether a PSI interdiction action is legal under UNCLOS or not.     

Dispersion statistics and a sampling plan for Helicoverpa (Lepidoptera: Noctuidae) on fresh-market tomatoes (Lycopersicon esculentum)

Abstract  Helicoverpa spp. is the primary pest in the Australian fresh-market tomato industry. We describe the spatial distribution of Helicoverpa spp. eggs on fresh-market tomato crops in the Goulburn Valley region of Victoria, and present a sequential sampling plan for monitoring population densities. The distribution of Helicoverpa spp. eggs was highly contagious, as indicated by a Taylor's b -value of 1.59. This high level of contagion meant that relatively large sample sizes would need to be collected to obtain an estimate of population density. High-precision sampling plans generally necessitated impractical sample sizes, and thus the plan we present is a relatively low-precision level plan (SE/mean = 0.3). Nonetheless, this level of precision is considered adequate for most agronomic scenarios. The plan was validated using a statistical re-sampling approach. The level of precision achieved was generally close to the nominal level. Likewise, the number of samples collected generally showed little departure from the theoretically calculated minimum sample size.     

On the usability of intramuscular EMG for prosthetic control: A Fitts’ Law approach

Previous studies on intramuscular EMG based control used offline data analysis. The current study investigates the usability of intramuscular EMG in two degree-of-freedom using a Fitts’ Law approach by combining classification and proportional control to perform a task, with real time feedback of user performance. Nine able-bodied subjects participated in the study. Intramuscular and surface EMG signals were recorded concurrently from the right forearm. Five performance metrics (Throughput, Path efficiency, Average Speed, Overshoot and Completion Rate) were used for quantification of usability. Intramuscular EMG based control performed significantly better than surface EMG for Path Efficiency (80.5 ± 2.4% vs. 71.5 ± 3.8%, P = 0.004) and Overshoot (22.0 ± 3.0% vs. 45.1 ± 6.6%, P = 0.01). No difference was found between Throughput and Completion Rate. However the Average Speed was significantly higher for surface (51.8 ± 5.5%) than for intramuscular EMG (35.7 ± 2.7%). The results obtained in this study imply that intramuscular EMG has great potential as control source for advanced myoelectric prosthetic devices.     

Analyzing Taylor’s Scaling Law: qualitative differences of social and territorial behavior on colonization/extinction dynamics

The power law relation between the mean population count and its variance (Taylor’s Power Law, TPL) is among the few general patterns in population ecology. While the TPL has been described to be pervasive across taxa, the causes of variation of the exponent describing this relation is not well understood. We compare the TPL exponents for two species with different social systems and behavior: Piñon jays (Gymnorhinus cyanocephalus) and Western scrub-jays (Aphelocoma californica). We analyze the underlying processes that generate the expected values of population size and its variance. Using a probabilistic model, we identify and estimate important processes involved in the generation of the TPL exponents. While both species show a scaling relationship between their mean and abundance, share a common negative relation between mean abundance and colonization–extinction rates, they differ greatly in the statistical distributions of colonization, extinction, the mean number of colonists, the probability of zero abundance and population sizes. We show how different aspects of the processes that generate abundance affect the TPL exponent, thereby providing empirical guidelines to interpret differences in the scaling relation between mean and variance of population size.     

Clarifying Baker's Law

Background

Baker''s Law states that colonization by self-compatible organisms is more likely to be successful than colonization by self-incompatible organisms because of the ability for self-compatible organisms to produce offspring without pollination agents. This simple model has proved very successful in plant ecology and has been applied to various contexts, including colonizing or ruderal species, islands colonizers, invasive species or mating system variation across distribution ranges. Moreover, it is one of the only models in population biology linking two traits of major importance in ecology, namely dispersal and mating system. Although Baker''s Law has stimulated a large number of empirical studies reporting the association of self-fertilization and colonizing ability in various contexts, the data have not established a general pattern for the association of traits.

Scope

In this paper, a critical position is adopted to discuss and clarify Baker''s Law. From the literature referring to Baker''s Law, an analysis made regarding how mating success is considered in such studies and discrepancies with population genetics theory of mating systems are highlighted. The data reporting the association of self-fertilization and colonizing ability are also briefly reviewed and the potential bias in interpretation is discussed. Lastly, a recent theoretical model analysing the link between colonizing ability and self-fertilization is considered.

Conclusions

Evolutionary predictions are actually more complex than Baker''s intuitive arguments. It appears that Baker''s Law encompasses a variety of ecological scenarios, which cannot be considered a priori as equivalent. Questioning what has been considered as self-evident for more than 50 years seems a reasonable objective to analyse in-depth dispersal and mating system traits.     

Multiple nutrients limit litterfall and decomposition in a tropical forest

To explore the importance of 12 elements in litter production and decomposition, we fertilized 36 1600 m²-plots with combinations of N, P, K, or micronutrients (i.e. B, Ca, Cu, Fe, Mg, Mn, Mo, S, Zn) for 6 years in a lowland Panamanian forest. The 90% of litter falling as leaves and twigs failed to increase with fertilization, but reproductive litter (fruits and flowers) increased by 43% with N. K enhanced cellulose decomposition; one or more micronutrients enhanced leaf-litter decomposition; P enhanced both. Our results suggest tropical forests are a non-Liebig world of multiple nutrient limitations, with at least four elements shaping rates of litterfall and decomposition. Multiple metallomic enzymes and cofactors likely create gradients in the break down of leaf litter. Selection favours individuals that make more propagules, and even in an N-rich forest, N is a non-substitutable resource for reproduction.     

Light responses ofBeggiatoa

Studies on nativeBeggiatoa demonstrated diel vertical migration into, and out of, sediments at the bottom of warm spring pools. Laboratory experiments withBeggiatoa in natural sediments suggested that high light was the cause of the downward movement. The nature of this presumed photomotion was clarified by microscopic observation of individual filaments of nativeBeggiatoa at light/dark boundaries where the light was varied in intensity and quality. Using white light, a negative photo-response was demonstrated, and a dose-response curve was constructed which indicates an increasing response to light over three orders of magnitude of intensity. A coarse action spectrum implicated a pigment with a peak in the blue region as the receptor. Pure culture studies showed the negative response to be a step-up phobic one. The light intensity increase necessary to invoke reversals was a smaller percentage of the initial intensity for higher initial intensities. The light intensity levels and gradient strengths necessary to evoke reversals in single filaments were consistent with the hypothesis that the step-up response accounts for the disappearance in the field. This response has adaptive significance since full sunlight was completely inhibitory toBeggiatoa growth, even when filaments were aggregated in tufts. Dilute suspensions were also inhibited by as little as 5000 lux (fluorescent lamps).     

A stochastic model of tumor response to fractionated radiation: limit theorems and rate of convergence

The iterated birth and death Markov process is defined as an n-fold iteration of a birth and death Markov process describing kinetics of certain population combined with random killing of individuals in the population at moments tau 1,...,tau n with given survival probabilities s1,...,sn. A long-standing problem of computing the distribution of the number of clonogenic tumor cells surviving an arbitrary fractionated radiation schedule is solved within the framework of iterated birth and death Markov process. It is shown that, for any initial population size iota, the distribution of the size N of the population at moment t > or = tau n is generalized negative binomial, and an explicit computationally feasible formula for the latter is found. It is shown that if i --> infinity and sn --> 0 so that the product iota s1...sn tends to a finite positive limit, the distribution of random variable N converges to a probability distribution, which for t = tau n turns out to be Poisson. In the latter case, an estimate of the rate of convergence in the total variation metric similar to the classical Law of Rare Events is obtained.     

THE MAINTENANCE OF GYNODIOECY AND ANDRODIOECY IN A METAPOPULATION

Males and females are at a selective disadvantage relative to hermaphrodites (cosexuals) in species with a colonizing habit, as only cosexuals are able to establish new colonies on their own. The implications of this disadvantage are assessed by means of a computer model of metapopulation dynamics, in which individual colonies are established through different rates of immigration and suffer different rates of local extinction. Results are given for simulations of an island model, a stepping-stone model, and for a partial analysis of the island model with simplifying assumptions. It is shown that: (1) unisexual frequencies in a metapopulation can be reasonably approximated by a linear function of the logarithm of the ratio of the immigration rate to the colony extinction rate; (2) metapopulation dynamics favor the maintenance of females (gynodioecy) over males (androdioecy) with cosexuals when they would otherwise be equally likely in a panmictic situation; (3) the way in which extinction and immigration rates affect unisexual frequencies at metapopulation equilibrium interacts with whether sterility is determined by a dominant or a recessive allele; and (4) unisexual frequencies are affected in a qualitatively similar way by the dynamics of a metapopulation when cosexuals are self-incompatible to when they are self-compatible, although only in the former case are high frequencies of unisexuals maintained when extinction and colonization rates approach the threshold at which the metapopulation goes extinct. These results are discussed with reference to existing data from species with nuclear male or female sterility.