Statistical Mechanical Approach to Human Language

We use the formulation of equilibrium statistical mechanics in order to study some important characteristics of language. Using a simple expression for the Hamiltonian of a language system, which is directly implied by the Zipf law, we are able to explain several characteristic features of human language that seem completely unrelated, such as the universality of the Zipf exponent, the vocabulary size of children, the reduced communication abilities of people suffering from schizophrenia, etc. While several explanations are necessarily only qualitative at this stage, we have, nevertheless, been able to derive a formula for the vocabulary size of children as a function of age, which agrees rather well with experimental data.Comment: 20 pages,4 figures, Accepted in Physica

Indigenous livestock husbandry and ethno veterinary practices in Endamohoni District of Tigray Region, Ethiopia

Indigenous knowledge is local knowledge that exists and buildup through experiences of the local community in the day-to-day practice and it is economically inexpensive. Farmers use their indigenous knowledge from time immemorial till today, thus it gives a good solution for their problems. However, this knowledge is not well studied, analyzed and documented to be used as a basis for farming system development. Therefore, this study was conducted with the objectives of identifying and documenting farmers’ indigenous knowledge in livestock husbandry, and ethno veterinary practices in Endamohoni district of southern Tigray. The woreda was purposively selected based on its contrasting agro-ecologies (lowland, midland, and highland) and potential of being the source of traditionally knowledgeable peoples who for generations have been associated with livestock rearing. Six kebeles (two kebeles from each of the three agroecologies) were selected as study sites. A total of 175 households (55 from lowland, 60 each from midland and highland), assumed to have a better indigenous knowledge in livestock production were selected for the study. A structured questionnaire was administered to the selected households to collect data on use of indigenous knowledge on livestock husbandry and ethno veterinary practices. After completing the questionnaires for each division, group discussions have been held and an informal meeting with the key informants for triangulation. Result indicated that 88.3, 76.7 and 92.7 % of the respondents in highland, midland and lowland agroecologies respectively were males. The level of education shows that of all the respondents, 55% in highland, 50% in midland and 72.73% in lowland were illiterate. Sheep and cattle in highlands and midlands and goat and cattle in lowland dominated the livestock populations. Shortage of feed in the study areas was ranked as the first constraints of animal production. Farmers use purchasing of crop residue in the highland and midland, destocking in the midland and movement (urna) in the lowland as mitigation mechanisms. Phenotypic selections of different animal species are employed and also keeping history of pedigree is important instrument in the breeding and selection of animals. Breeding of close related livestock is discouraged in the study sites. Seventeen animal diseases and38 aliments were recorded in the study areas and 65 medicinal plants were accordingly documented to treat those diseases. About 83% of the highland, 75 % of the midland and 92.7% of the lowland farmers acquire ethno veterinary knowledge from their old parents. Of the total medicinal plants, (81 %) were wild. In the preparation of the traditional medicine leaves constitute about 51% and 47 % of the medicine was administered orally. The most common preparation method is by crushing and squeezing (45 %). Farmers are aware of toxicity and provide antioxidants. Farmers used herbals (plants) in dairy utensils cleaning, fumigation, milk processing and preservation. These knowledge and practices of livestock husbandry, animal health and product handling and processing should serve as the basis to develop further interventions to improve livestock productivity in the area. As most of the medicinal plants are grown in wild, it is very important to promote conservation in ex-situ and in-situ. And further biological studies should be conducted on the reported medicinal plant species of the study area so as to utilize them in drug development

Evolution of Vocabulary on Scale-free and Random Networks

We examine the evolution of the vocabulary of a group of individuals (linguistic agents) on a scale-free network, using Monte Carlo simulations and assumptions from evolutionary game theory. It is known that when the agents are arranged in a two-dimensional lattice structure and interact by diffusion and encounter, then their final vocabulary size is the maximum possible. Knowing all available words is essential in order to increase the probability to ``survive'' by effective reproduction. On scale-free networks we find a different result. It is not necessary to learn the entire vocabulary available. Survival chances are increased by using the vocabulary of the ``hubs'' (nodes with high degree). The existence of the ``hubs'' in a scale-free network is the source of an additional important fitness generating mechanism.Comment: 10 pages, 3 Figures, accepted in Physica

Language Time Series Analysis

We use the Detrended Fluctuation Analysis (DFA) and the Grassberger-Proccacia analysis (GP) methods in order to study language characteristics. Despite that we construct our signals using only word lengths or word frequencies, excluding in this way huge amount of information from language, the application of Grassberger- Proccacia (GP) analysis indicates that linguistic signals may be considered as the manifestation of a complex system of high dimensionality, different from random signals or systems of low dimensionality such as the earth climate. The DFA method is additionally able to distinguish a natural language signal from a computer code signal. This last result may be useful in the field of cryptography.Comment: 21 pages, 5 figures, accepted in Physica

Wikipedia Information Flow Analysis Reveals the Scale-Free Architecture of the Semantic Space

In this paper we extract the topology of the semantic space in its encyclopedic acception, measuring the semantic flow between the different entries of the largest modern encyclopedia, Wikipedia, and thus creating a directed complex network of semantic flows. Notably at the percolation threshold the semantic space is characterised by scale-free behaviour at different levels of complexity and this relates the semantic space to a wide range of biological, social and linguistics phenomena. In particular we find that the cluster size distribution, representing the size of different semantic areas, is scale-free. Moreover the topology of the resulting semantic space is scale-free in the connectivity distribution and displays small-world properties. However its statistical properties do not allow a classical interpretation via a generative model based on a simple multiplicative process. After giving a detailed description and interpretation of the topological properties of the semantic space, we introduce a stochastic model of content-based network, based on a copy and mutation algorithm and on the Heaps' law, that is able to capture the main statistical properties of the analysed semantic space, including the Zipf's law for the word frequency distribution

A year-long assessment of wave measurements retrieved from an HF radar network in the Gulf of Naples (Tyrrhenian Sea, Western Mediterranean Sea)

A three-site short-range (25 MHz) CODAR SeaSonde High-Frequency (HF) radar system has been operating in the Gulf of Naples (Tyrrhenian Sea) since 2004. HF radars use first-order echoes to determine surface currents, while second-order ones can be exploited to estimate the main parameters characterising the wave field: significant wave height, direction and period. Waves were studied in the Gulf of Naples at each radar site over a range cell located between 5 and 6 km from the coast. The data acquired in the reference year 2010 were compared with the measurements recorded over the same period by a directional wave buoy installed in the outer part of the basin. This study aims at verifying the agreement between the recordings of the two platforms, in order to test the robustness of the HF radar-derived wave measurements. In addition, the analyses here presented investigate the seasonal patterns of the wave parameters, showing the different responses of the wave field in different sectors of the basin and the responsiveness of HF radars in critical environmental conditions. The two platforms showed consistent results, indicating the reliability of HF radars as wave measurement tools and opening the way to further applications in wave monitoring and analysis in coastal areas

Validation of HF Radar-Derived Currents in the Gulf of Naples with Lagrangian Data

A massive drifter deployment in the Gulf of Naples (Southern Tyrrhenian Sea, Western Mediterranean Sea) over a ten-day multidisciplinary in situ experiment in Summer 2012 provided sea-truth data for validating the performance of a high-frequency (HF) radar network. The buoys were frequently retrieved and relaunched to ensure an optimal coverage of the domain. The total velocity of the drifters, together with the associated zonal and meridional components, was compared with the HF radar surface current estimates. Divergence between virtual and real drifter trajectories, and also the simulated movement of clouds of particles give useful insights for scenarios of search and rescue. All comparisons were performed, considering both ideal and antenna radiation pattern-corrected fields. The results of the investigation testify the high precision of HF radars and confirm the necessity of periodically verifying the antenna pattern to ensure the optimal functionality of these systems

STRING: A new drifter for HF radar validation

International audienc

The stochastic model representing the semantic space.

<p>Results for the simulation of the stochastic model representing the semantic space. This is a simulation of a <i>toy-model</i> for an encyclopedia of pages with size log-normally distributed, with first moment and second moment . The parameter of the model are , and . In the top panels the out-degree distribution (left panel) and the in-degree distribution (right panel) of the semantic network at the percolation threshold are shown. The corresponding cumulative distributions are displayed in the insets. In the bottom left panel we show the cluster size distribution at the percolation threshold, the relative cumulative distribution is displayed in the inset. In the right bottom panel we show the frequency-rank distribution for the words in the model.</p