Evolution of signalling systems with multiple senders and receivers

Sender–receiver games are simple, tractable models of information transmission. They provide a basic setting for the study the evolution of meaning. It is possible to investigate not only the equilibrium structure of these games but also the dynamics of evolution and learning—with sometimes surprising results. Generalizations of the usual binary game to interactions with multiple senders, multiple receivers or both provide the elements of signalling networks. These can be seen as the loci of information processing, group decisions, and teamwork

Devon Island Programs 1971

From April to October 1971 the Arctic Institute's research base on the northeast coast of Devon Island (75°40'N, 84°40'W) was the seat of operations for over 50 investigators and their field assistants. The major research program was a large integrated tundra ecosystem study sponsored by the Canadian International Biological Program (IBP) .... The Base Camp was also used, though briefly, by groups of researchers from the Canadian Wildlife Survey conducting polar bear studies in northern Devon Island, and from the Polar Continental Shelf Project who were making glaciological studies of the Devon Island Ice Cap. ... The status and condition of the Base Camp, and the logistics services, remain essentially as reported in the 1970 field summary ..., although minor improvements and repairs were made to the 8 huts, and the water and power system and local transportation facilities were improved by the addition of another skidoo, bringing the total to 3. ... In 1971, as in the previous summer, the size and capacity (unfortunately not synonymous) of the Base Camp increased. Those who have visited the Camp in previous years would find little resemblance today. The Camp at present consists of 8 Parcolls and Jamesways (many of which were enlarged in 1971), which together with tents, some lent to the Institute by the Canadian Forces, provided both laboratory and living space. A secondary camp, situated some 5 miles from Base Camp, provided a base of operations for a group of researchers from the University of Manitoba. Remote from the large population of Base Camp it made work on muskoxen and other mammals somewhat easier. One problem that came to the fore in 1971 was how to keep to the minimum the impact of relatively large numbers of people with their equipment on the Truelove Lowland itself. All of those who lived at Base Camp cooperated in efforts to avoid any unsightliness and in fact several visitors noted the general tidiness of the area. Outside the BaseCamp, movement, particularly vehicle movement, was also kept to a minimum. ... [The two AINA-sponsored projects (ecological studies of sedge dominated meadow tundras, comparative ecology of High Arctic species of Saxifraga) are summarized.

TASK XII ANALYTICAL REPORT--SM-1 TRANSIENT ANALYSIS BY ANALOG COMPUTER METHODS

The voltage and frequency response of selected SM-1 plant system parameters to step load changes was analyzed using analog computer measurements. The analog model was that developed for analysis of the SM-2 design. The approach to the analysis, formulation of the model, and analog recordings are presented. The data will be used to prove reliability of the analog model by comparing analog data with test data to be taken at SM-1. (auth

Inference of hot star density stream properties from data on rotationally recurrent DACs

The information content of data on rotationally periodic recurrent discrete absorption components (DACs) in hot star wind emission lines is discussed. The data comprise optical depths tau(w,phi) as a function of dimensionless Doppler velocity w=(Deltalambda/lambda(0))(c/v(infinity)) and of time expressed in terms of stellar rotation angle phi. This is used to study the spatial distributions of density, radial and rotational velocities, and ionisation structures of the corotating wind streams to which recurrent DACs are conventionally attributed. The simplifying assumptions made to reduce the degrees of freedom in such structure distribution functions to match those in the DAC data are discussed and the problem then posed in terms of a bivariate relationship between tau(w, phi) and the radial velocity v(r)(r), transverse rotation rate Omega(r) and density rho(r, phi) structures of the streams. The discussion applies to cases where: the streams are equatorial; the system is seen edge on; the ionisation structure is approximated as uniform; the radial and transverse velocities are taken to be functions only of radial distance but the stream density is allowed to vary with azimuth. The last kinematic assumption essentially ignores the dynamical feedback of density on velocity and the relationship of this to fully dynamical models is discussed. The case of narrow streams is first considered, noting the result of Hamann et al. (2001) that the apparent acceleration of a narrow stream DAC is higher than the acceleration of the matter itself, so that the apparent slow acceleration of DACs cannot be attributed to the slowness of stellar rotation. Thus DACs either involve matter which accelerates slower than the general wind flow, or they are formed by structures which are not advected with the matter flow but propagate upstream (such as Abbott waves). It is then shown how, in the kinematic model approximation, the radial speed of the absorbing matter can be found by inversion of the apparent acceleration of the narrow DAC, for a given rotation law. The case of broad streams is more complex but also more informative. The observed tau(w,phi) is governed not only by v(r)(r) and Omega(r) of the absorbing stream matter but also by the density profile across the stream, determined by the azimuthal (phi(0)) distribution function F-0(phi(0)) of mass loss rate around the stellar equator. When F-0(phi(0)) is fairly wide in phi(0), the acceleration of the DAC peak tau(w, phi) in w is generally slow compared with that of a narrow stream DAC and the information on v(r)(r), Omega(r) and F- 0(phi(0)) is convoluted in the data tau(w, phi). We show that it is possible, in this kinematic model, to recover by inversion, complete information on all three distribution functions v(r)(r), Omega(r) and F-0(phi(0)) from data on tau(w, phi) of sufficiently high precision and resolution since v(r)(r) and Omega(r) occur in combination rather than independently in the equations. This is demonstrated for simulated data, including noise effects, and is discussed in relation to real data and to fully hydrodynamic models

Violation of local realism vs detection efficiency

We put bounds on the minimum detection efficiency necessary to violate local realism in Bell experiments. These bounds depends of simple parameters like the number of measurement settings or the dimensionality of the entangled quantum state. We derive them by constructing explicit local-hidden variable models which reproduce the quantum correlations for sufficiently small detectors efficiency.Comment: 6 pages, revtex. Modifications in the discussion for many parties in section 3, small erros and typos corrected, conclusions unchange

Exponential quantum enhancement for distributed addition with local nonlinearity

We consider classical and entanglement-assisted versions of a distributed computation scheme that computes nonlinear Boolean functions of a set of input bits supplied by separated parties. Communication between the parties is restricted to take place through a specific apparatus which enforces the constraints that all nonlinear, nonlocal classical logic is performed by a single receiver, and that all communication occurs through a limited number of one-bit channels. In the entanglement-assisted version, the number of channels required to compute a Boolean function of fixed nonlinearity can become exponentially smaller than in the classical version. We demonstrate this exponential enhancement for the problem of distributed integer addition.Comment: To appear in Quantum Information Processin

Microparasites and their potential impact on the population dynamics of small cetaceans from South America: a brief review. Document SC/59/DW8, Scientific Committee, International Whaling Commission, Anchorage, Alaska, 4-14 May 2007

We briefly review the pathology, epidemiology and molecular biology of cetacean viruses (including morbilli, papilloma and pox) and Brucella spp. encountered in South America. Antibodies against cetacean morbillivirus were detected (by iELISAs and virus neutralisation tests) in SE Pacific and SW Atlantic delphinids. Morbilliviruses are possibly enzootic in Lagenorhynchus obscurus and offshore Tursiops truncates from Peru and in Lagenodelphis hosei from Brazil and Argentina, but no morbillivirus antibodies were found in inshore small cetaceans. Papillomaviruses cause genital warts in at least three odontocete species in Peru. Two Phocoena spinipinnis papillomaviruses (PsPVs) were found in warts of Burmeister’s porpoises; one (PsPV-1) was cloned and characterized. Half of porpoises had developed genital warts, while in 10% of males the lesions were sufficiently numerous and severe to at least hamper, if not impede, copulation. High titers of cowpox virus neutralising antibodies were detected in Peruvian D. capensis, T. truncatus, L. obscurus and P. spinipinnis in 1993-1995. The high prevalence of orthopoxvirus neutralising antibodies with high titres indicates common infection by poxviruses antigenically related to cowpox virus, the probable causative agents of tattoo skin disease. Cetacean poxviruses may cause significant mortaliy among neonates and calves unprotected by maternal immunity. In Peru, Brucella spp. antibodies were detected (competitive ELISA) in D. capensis, T. truncatus, L. obscurus and P. spinipinnis. Brucellosis is likely enzootic in the latter two species, and may lead to orchitis and bone lesions in L. obscurus and D. capensis. The enzootic circulation of brucellae in L. obscurus and P. spinipinnis may constitute a measurable limiting factor among the environmental variables affecting population dynamics. Also, widespread Brucella spp. infection in several Peruvian odontocetes has public health implications (zoonosis), considering frequent manipulation of carcases and consumption of meat. Extrinsic anthropogenic factors may not only exacerbate the consequences of viral infections on the health of a particular individual, but also operate at the population level

The Grover algorithm with large nuclear spins in semiconductors

We show a possible way to implement the Grover algorithm in large nuclear spins 1/2<I<9/2 in semiconductors. The Grover sequence is performed by means of multiphoton transitions that distribute the spin amplitude between the nuclear spin states. They are distinguishable due to the quadrupolar splitting, which makes the nuclear spin levels non-equidistant. We introduce a generalized rotating frame for an effective Hamiltonian that governs the non-perturbative time evolution of the nuclear spin states for arbitrary spin lengths I. The larger the quadrupolar splitting, the better the agreement between our approximative method using the generalized rotating frame and exact numerical calculations.Comment: 11 pages, 18 EPS figures, REVTe