Power-law running of the effective gluon mass

The dynamically generated effective gluon mass is known to depend non-trivially on the momentum, decreasing sufficiently fast in the deep ultraviolet, in order for the renormalizability of QCD to be preserved. General arguments based on the analogy with the constituent quark masses, as well as explicit calculations using the operator-product expansion, suggest that the gluon mass falls off as the inverse square of the momentum, relating it to the gauge-invariant gluon condensate of dimension four. In this article we demonstrate that the power-law running of the effective gluon mass is indeed dynamically realized at the level of the non-perturbative Schwinger-Dyson equation. We study a gauge-invariant non-linear integral equation involving the gluon self-energy, and establish the conditions necessary for the existence of infrared finite solutions, described in terms of a momentum-dependent gluon mass. Assuming a simplified form for the gluon propagator, we derive a secondary integral equation that controls the running of the mass in the deep ultraviolet. Depending on the values chosen for certain parameters entering into the Ansatz for the fully-dressed three-gluon vertex, this latter equation yields either logarithmic solutions, familiar from previous linear studies, or a new type of solutions, displaying power-law running. In addition, it furnishes a non-trivial integral constraint, which restricts significantly (but does not determine fully) the running of the mass in the intermediate and infrared regimes. The numerical analysis presented is in complete agreement with the analytic results obtained, showing clearly the appearance of the two types of momentum-dependence, well-separated in the relevant space of parameters. Open issues and future directions are briefly discussed.Comment: 37 pages, 5 figure

Report of the Task Force on Ecoregional Approaches to Research

Report of the Task Force on Ecoregional Approaches to Research established at ICW94 It was presented at the CGIAR Mid Term Meeting in Nairobi, May 1995 by Task Force Chair Cyrus K. Ndiritu, Director of the Kenya Agricultural Research Institute (KARI). This task force was twinned with the Task Force on Sustainable Agriculture which also reported to MTM95.The report said that the ecoregional approach could focus and integrate commodity and thematic research, and link technological opportunity to the formulation of land use strategies and policies. The complex relationships implicit in the approach required clear assignments of responsibilities and partnerships among the participants. The Task Force proposed a matching fund to attract contributions for NARS and other local participants, and endorsed the TAC recommendations of 39% of CGIAR funding in the near future, and a fifteen year initial time horizon.Annexes include the original and revised terms of reference of the task force, and a list of members. Agenda document at the CGIAR meeting in May 1995

Approaches to the use of sensor data to improve classroom experience

quipping classrooms with inexpensive sensors can enable students and teachers with the opportunity to interact with the classroom in a smart way. In this paper an approach to acquiring contextual data from a classroom environment, using inexpensive sensors, is presented. We present our approach to formalising the usage data. Further we demonstrate how the data was used to model specific room usage situation as cases in a Case-based reasoning (CBR) system. The room usage data was than integrated in a room recommendations system, reasoning on the formalised usage data. We also detail on our on-going work to integrating the systems presented in this paper into our Smart University vision

Approaches to conceptual clustering

Methods for Conceptual Clustering may be explicated in two lights. Conceptual Clustering methods may be viewed as extensions to techniques of numerical taxonomy, a collection of methods developed by social and natural scientists for creating classification schemes over object sets. Alternatively, conceptual clustering may be viewed as a form of learning by observation or concept formation, as opposed to methods of learning from examples or concept identification. In this paper we survey and compare a number of conceptual clustering methods along dimensions suggested by each of these views. The point we most wish to clarify is that conceptual clustering processes can be explicated as being composed of three distinct but inter-dependent subprocesses: the process of deriving a hierarchical classification scheme; the process of aggregating objects into individual classes; and the process of assigning conceptual descriptions to object classes. Each subprocess may be characterized along a number of dimensions related to search, thus facilitating a better understanding of the conceptual clustering process as a whole

Theoretical Approaches to HERA Physics

A review is presented of the different theoretical models proposed to approach consistently the interplay between soft and hard physics, that can now be studied experimentally at HERA for the first time.Comment: 14 page

Approaches to Sensory Landscape Archaeology

As the medium through which humans interact with the physical world, senses are crucial to explore when trying to understand the beings that embody them. Senses are the middlemen through which humans register their surroundings, perform activities crucial for survival, and interact with the world and it’s inhabitants. The phenomenon of senses, although shared among all humans, can be very personal and informative of individual life histories. The scent of cinnamon, for example, can evoke memories of childhood for some, while for others there is no connection. Senses are physically natured but culturally constructed. Colors, tastes, and sounds can hold completely different meanings to different peoples and cultures. Altogether, senses are an undeniably important component of human existence. As such, sensory discourse has led to an interesting accumulation of data, literature, and discoveries. Emerging from this mass of literature is sensory archaeology bringing with it much potential