Period-two cycles in a feed-forward layered neural network model with symmetric sequence processing

The effects of dominant sequential interactions are investigated in an exactly solvable feed-forward layered neural network model of binary units and patterns near saturation in which the interaction consists of a Hebbian part and a symmetric sequential term. Phase diagrams of stationary states are obtained and a new phase of cyclic correlated states of period two is found for a weak Hebbian term, independently of the number of condensed patterns $c$.Comment: 8 pages and 5 figure

Symmetric sequence processing in a recurrent neural network model with a synchronous dynamics

The synchronous dynamics and the stationary states of a recurrent attractor neural network model with competing synapses between symmetric sequence processing and Hebbian pattern reconstruction is studied in this work allowing for the presence of a self-interaction for each unit. Phase diagrams of stationary states are obtained exhibiting phases of retrieval, symmetric and period-two cyclic states as well as correlated and frozen-in states, in the absence of noise. The frozen-in states are destabilised by synaptic noise and well separated regions of correlated and cyclic states are obtained. Excitatory or inhibitory self-interactions yield enlarged phases of fixed-point or cyclic behaviour.Comment: Accepted for publication in Journal of Physics A: Mathematical and Theoretica

Trying to make an unwanted facility palatable

Finding suitable accommodations for the temporary storage and permanent disposal of this: nation`s low- and high-level radioactive waste is proving an ever more difficult task in this era of volatile technology and science debate over the merits of the nuclear fuel cycle. Local constituencies become deeply immersed in the complex debate whether the site is chosen through a technical site selection process or is a voluntary entry. Rural communities with candidate sites need to initially shift their focus away from this, often acrimonious, debate; instead, the first discussion priority for such rural communities should be to develop a dynamic vision of their own economic and environmental future. The second discussion priority should be to determine if the array of accompanying incentives and benefits hosting this facility would afford the community the opportunity for vision fulfillment. If so, total focus should, then, be given to understanding and resolving to the satisfaction of the constituents issues related to nuclear technology, isolation of radioactive materials, management of risk, storage and disposal facility need, perceived and actual risk, oversight and power sharing authority, engineered safety barriers, and public trust

A historical application of social amplification of risk model: Economic impacts of risk events at nuclear weapons facilities?

Public perceptions of risk have proven to be a critical barrier to the federal government`s extensive, decade-long, technical and scientific effort to site facilities for the interim storage and permanent disposal of high-level radioactive waste (HLW). The negative imagery, fear, and anxiety that are linked to ``nuclear`` and ``radioactive`` technologies, activities, and facilities by the public originate from the personal realities and experiences of individuals and the information they receive. These perceptions continue to be a perplexing problem for those responsible for making decisions about federal nuclear waste management policies and programs. The problem of understanding and addressing public perceptions is made even more difficult because there are decidedly different opinions about HLW held by the public and nuclear industry and radiation health experts

Isovector EMC effect from global QCD analysis with MARATHON data

We report the results of a Monte Carlo global QCD analysis of unpolarized parton distribution functions (PDFs), including for the first time constraints from ratios of $^3$He to $^3$H structure functions recently obtained by the MARATHON experiment at Jefferson Lab. Our simultaneous analysis of nucleon PDFs and nuclear effects in $A=2$ and $A=3$ nuclei reveals the first indication for an isovector nuclear EMC effect in light nuclei. We find that while the MARATHON data yield relatively weak constraints on the $F_2^n/F_2^p$ neutron to proton structure function ratio and on the $d/u$ PDF ratio, they suggest an enhanced nuclear effect on the $d$-quark PDF in the bound proton, questioning the assumptions commonly made in nuclear PDF analyses.Comment: 6 pages, 3 figure

African Communitarianism and Difference

There has been the recurrent suspicion that community, harmony, cohesion, and similar relational goods as understood in the African ethical tradition threaten to occlude difference. Often, it has been Western defenders of liberty who have raised the concern that these characteristically sub-Saharan values fail to account adequately for individuality, although some contemporary African thinkers have expressed the same concern. In this chapter, I provide a certain understanding of the sub-Saharan value of communal relationship and demonstrate that it entails a substantial allowance for difference. I aim to show that African thinkers need not appeal to, say, characteristically Euro-American values of authenticity or autonomy to make sense of why individuals should not be pressured to conform to a group’s norms regarding sex and gender. A key illustration involves homosexuality

How Climate Impacts the Composition of Wolf-Killed Elk in Northern Yellowstone National Park

While the functional response of predators is commonly measured, recent work has revealed that the age and sex composition of prey killed is often a better predictor of prey population dynamics because the reproductive value of adult females is usually higher than that of males or juveniles. Climate is often an important mediating factor in determining the composition of predator kills, but we currently lack a mechanistic understanding of how the multiple facets of climate interact with prey abundance and demography to influence the composition of predator kills. Over 20 winters, we monitored 17 wolf packs in Yellowstone National Park and recorded the sex, age and nutritional condition of kills of their dominant prey—elk—in both early and late winter periods when elk are in relatively good and relatively poor condition, respectively. Nutritional condition (as indicated by per cent marrow fat) of wolf‐killed elk varied markedly with summer plant productivity, snow water equivalent (SWE) and winter period. Moreover, marrow was poorer for wolf‐killed bulls and especially for calves than it was for cows. Wolf prey composition was influenced by a complex set of climatic and endogenous variables. In early winter, poor plant growth in either year t or t − 1, or relatively low elk abundance, increased the odds of wolves killing bulls relative to cows. Calves were most likely to get killed when elk abundance was high and when the forage productivity they experienced in utero was poor. In late winter, low SWE and a relatively large elk population increased the odds of wolves killing calves relative to cows, whereas low SWE and poor vegetation productivity 1 year prior together increased the likelihood of wolves killing a bull instead of a cow. Since climate has a strong influence on whether wolves prey on cows (who, depending on their age, are the key reproductive components of the population) or lower reproductive value of calves and bulls, our results suggest that climate can drive wolf predation to be more or less additive from year to year

Comparing extractions of Sivers functions

A comparison is given of the various recently published extractions of the Sivers functions from the HERMES and COMPASS data on single-transverse spin asymmetries in semi-inclusive deeply inelastic scattering.Comment: Contribution to the proceedings of "The International Workshop on Transverse Polarisation Phenomena in Hard Processes" (Transversity 2005), Villa Olmo (Como), 7-10th. September 200

Effect of Sociality and Season on Gray Wolf (Canis lupus) Foraging Behavior: Implications for Estimating Summer Kill Rate

BACKGROUND: Understanding how kill rates vary among seasons is required to understand predation by vertebrate species living in temperate climates. Unfortunately, kill rates are only rarely estimated during summer. METHODOLOGY/PRINCIPAL FINDINGS: For several wolf packs in Yellowstone National Park, we used pairs of collared wolves living in the same pack and the double-count method to estimate the probability of attendance (PA) for an individual wolf at a carcass. PA quantifies an important aspect of social foraging behavior (i.e., the cohesiveness of foraging). We used PA to estimate summer kill rates for packs containing GPS-collared wolves between 2004 and 2009. Estimated rates of daily prey acquisition (edible biomass per wolf) decreased from 8.4±0.9 kg (mean ± SE) in May to 4.1±0.4 kg in July. Failure to account for PA would have resulted in underestimating kill rate by 32%. PA was 0.72±0.05 for large ungulate prey and 0.46±0.04 for small ungulate prey. To assess seasonal differences in social foraging behavior, we also evaluated PA during winter for VHF-collared wolves between 1997 and 2009. During winter, PA was 0.95±0.01. PA was not influenced by prey size but was influenced by wolf age and pack size. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that seasonal patterns in the foraging behavior of social carnivores have important implications for understanding their social behavior and estimating kill rates. Synthesizing our findings with previous insights suggests that there is important seasonal variation in how and why social carnivores live in groups. Our findings are also important for applications of GPS collars to estimate kill rates. Specifically, because the factors affecting the PA of social carnivores likely differ between seasons, kill rates estimated through GPS collars should account for seasonal differences in social foraging behavior

Characterizing flows with an instrumented particle measuring Lagrangian accelerations

We present in this article a novel Lagrangian measurement technique: an instrumented particle which continuously transmits the force/acceleration acting on it as it is advected in a flow. We develop signal processing methods to extract information on the flow from the acceleration signal transmitted by the particle. Notably, we are able to characterize the force acting on the particle and to identify the presence of a permanent large-scale vortex structure. Our technique provides a fast, robust and efficient tool to characterize flows, and it is particularly suited to obtain Lagrangian statistics along long trajectories or in cases where optical measurement techniques are not or hardly applicable.Comment: submitted to New Journal of Physic