Deformed Heisenberg algebra and minimal length

A one-dimensional deformed Heisenberg algebra $[X,P]=if(P)$ is studied. We answer the question: For what function of deformation $f(P)$ there exists a nonzero minimal uncertainty in position (minimal length). We also find an explicit expression for the minimal length in the case of arbitrary function of deformation.Comment: to be published in JP

Paper Session I-A - Non-Ohmic Discharge Characteristics of the JSC MARS-1 Martian Regolith Simulant

Studies of the voltage (charge) decay behavior of the JSC Mars-1 Martian Regolith simulant are presented for both moist and dry conditions in a simulated Earth/Mars environment. The results indicate that moisture content is the main driving force behind the form of the decay curve as well as temperature while atmospheric content and pressure play a little role. Dry simulant conditions act as well-behaved ohmic insulators with an expected exponential decay, while moist simulant possesses non-ohmic behavior decaying as 1/time. The decay relationships are derived from the experimental measurements of the current-voltage relationships. Some possible explanations of this behavior are discussed

Paper Session I-C - Comparison of Surface Resistivity and Triboelectric Charge Generation Characteristics of Materials

Electrostatic discharge can be a significant threat to electronic components, equipment and personnel, especially when working around flammable materials. The development of ways to predict the susceptibility of materials to generate significant charge is important for the safety of these personnel and equipment. The classification of materials as conductors or insulators is based on the surface resistivity of the materials. Though surface resistivity is an important piece of information when choosing electrostatically safe materials, this classification system does not provide any information as to the probability of the materials to generate charge when placed in contact with other materials (triboelectric charging). Without that information, the probability for hazardous electrostatic discharge to occur is not known. In this paper we show that there is no significant correlation between surface resistivity and triboelectric charge generation and emphasize the need for a test method to predict the susceptibility of materials for triboelectric charge generation in order to better evaluate a material’s propensity to cause an electrostatic discharge

Representation Theory of Quantized Poincare Algebra. Tensor Operators and Their Application to One-Partical Systems

A representation theory of the quantized Poincar\'e ($\kappa$-Poincar\'e) algebra (QPA) is developed. We show that the representations of this algebra are closely connected with the representations of the non-deformed Poincar\'e algebra. A theory of tensor operators for QPA is considered in detail. Necessary and sufficient conditions are found in order for scalars to be invariants. Covariant components of the four-momenta and the Pauli-Lubanski vector are explicitly constructed.These results are used for the construction of some q-relativistic equations. The Wigner-Eckart theorem for QPA is proven.Comment: 18 page

Hox genes and morphological identity: axial versus lateral patterning in the vertebrate mesoderm

The successful organization of the vertebrate body requires that local information in the embryo be translated into a functional, global pattern. Somite cells form the bulk of the musculoskeletal system. Heterotopic transplants of segmental plate along the axis from quail to chick were performed to test the correlation between autonomous morphological patterning and Hox gene expression in somite subpopulations. The data presented strengthen the correlation of Hox gene expression with axial specification and focus on the significance of Hox genes in specific derivatives of the somites. We have defined two anatomical compartments of the body based on the embryonic origin of the cells making up contributing structures: the dorsal compartment, formed from purely somitic cell populations; and the ventral compartment comprising cells from somites and lateral plate. The boundary between these anatomical compartments is termed the somitic frontier. Somitic tissue transplanted between axial levels retains both original Hox expression and morphological identity in the dorsal compartment. In contrast, migrating lateral somitic cells crossing the somitic frontier do not maintain donor Hox expression but apparently adopt the Hox expression of the lateral plate and participate in the morphology appropriate to the host level. Dorsal and ventral compartments, as defined here, have relevance for experimental manipulations that influence somite cell behavior. The correlation of Hox expression profiles and patterning behavior of cells in these two compartments supports the hypothesis of independent Hox codes in paraxial and lateral plate mesoderm

Paper Session II-A - Results of a Wheel Electrometer for Measuring the Triboelectric Properties of Martian Regolith

The preliminary results of a prototype Wheel Electrometer System (WES) are presented that show that it is indeed possible to use the static electricity generated between polymers and soils after contact (triboelectricity) as a means of detecting property changes. Changes in the triboelectric signals offer information as to the mechanical properties of the soil such as grain size differences, texture, hardness and even moisture content. Initially, four polymers are chosen that span the triboelectric series such as Teflon, Lucite, Fiberglass and Lexan. It is shown that the average charge on Teflon is much higher when rolled over beach sand as compared to Martian simulant and limestone. Lucite was the most susceptible to particle size differences, while Lexan was able to detect underlying materials in the case of a soil lightly covered with a different soil type. All polymers responded differently when rolled over dry soil compared with moist soil. This information can be used as a type of triboelectric spectroscopy when a library of data is used to categorize the unique charging characteristics of individual polymers. This system is of great interest to planetary scientists and such measurements may be included in future Mars rover missions

Is a community still a community? Reviewing definitions of key terms in community ecology

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth etal. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; community, assemblage, guild, and ensemble. We revisit Fauth etal.\u27s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre-1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups