Relating Scattering Amplitudes in Bosonic and Topological String Theories

A formal relationship between scattering amplitudes in critical bosonic string theory and correlation functions of operators in topological string theory is found.Comment: 9 page

Diff(SIGMA) and Metrics from Hamiltonian-TQFT's in 2+1 Dimensions

The constraints of $BF$ topological gauge theories are used to construct Hamiltonians which are anti-commutators of the BRST and anti-BRST operators. Such Hamiltonians are a signature of Topological Quantum Field Theories (TQFT's). By construction, both classes of topological field theories share the same phase spaces and constraints. We find that, for 2+1 and 1+1 dimensional space-times foliated as M=\Sigma\times\IR, a homomorphism exists between the constraint algebras of our TQFT and those of canonical gravity. The metrics on the two-dimensional hypersurfaces are also obtained.Comment: 9 pages, Plain TeX, MIT-CTP#217

Some effects of urea and sulfur additions to corn silage for growing-finishing heifers

A six-year study with growing-finishing beef heifers was conducted to: 1. Compare cottonseed meal (CSM) and urea as protein supplements for corn silage; 2. To evaluate cattle performance when sulfur was added to urea-treated corn silage; 3. Test the value of different levels of urea additions to corn silage if the N:S ratio is held constant; and 4. Compare organic and inorganic sources of sulfur added to urea-treated corn silage. Each year 40 or 48 medium or good grade heifer calves (450-500 pounds) were allotted into eight lots of five or six each. Two lots were randomly assigned to each treatment. The finishing period was divided into a silage phase and a concentrate phase. The heifers were weighed every 28 days and subjectively evaluated at the beginning and end of each feeding phase. When the heifers reached an average con-dition grade of good, they were slaughtered. During the silage phase the CSM-supplemented heifers gained sig-nificantly faster (P \u3c .05) than the urea-supplemented heifers. At the end of the total feeding period the CSM-supplemented heifers had a higher Average Daily Gain (ADG) than the urea-supplemented heifers, but the difference was non-significant (P \u3e .05). There was no significant difference (P \u3e .05) between groups in feed conversion due to source of protein. During 1968 and 1969 sulfur-supplemented heifers required signif-icantly more (P \u3c .05) silage dry matter per pound of gain than heifers fed urea-treated corn silage without added sulfur. However, there was no significant difference (P \u3e .05) in ADG between treatments in any feeding phase. Also, there was no significant difference (P \u3e .05) in ADG or feed efficiency between groups of heifers fed urea-treated corn silage with and without added sulfur in 1970-1973. In 1970 and 1971 when ten pounds and 20 pounds of urea were added per ton of corn silage with the N:S ratio held constant, there was no significant difference (P \u3e .05) in ADG or feed efficiency in any of the groups of heifers due to silage treatment. Sodium sulfate and methionine-hydroxy-analogue (MHA) were com-pared as sulfur sources in 1972 and 1973. There was no significant difference (P \u3e .05) in ADG or feed conversion in any feeding phase due to sulfur source. Grain was not fed during the silage phase in 1968 and 1969 but was fed during the silage phase of the 1970-73 trials. All heifers in all years were fed to the same slaughter weight and grade, but the heifers in 1970-73 averaged 44 fewer days on feed and required less feed per pound of gain than those in 1968 and 1969

The Physics Inside Topological Quantum Field Theories

We show that the equations of motion defined over a specific field space are realizable as operator conditions in the physical sector of a generalized Floer theory defined over that field space. The ghosts associated with such a construction are found not to be dynamical. This construction is applied to gravity on a four dimensional manifold, $M$; whereupon, we obtain Einstein's equations via surgery, along $M$, in a five-dimensional topological quantum field theory.Comment: LaTeX, 7 page

Conceptual modelling and the project process in real simulation projects:a survey of simulation modellers

A survey was used to obtain information on the processes and methods used by simulation experts in real projects. The 102 survey respondents answered questions about their most recent simulation project. This paper presents some of the survey results, focussing mainly on conceptual modelling and the pattern of time allocation to different topics. There are a wide range of findings that include the modellers making changes to the initial conceptual model during subsequent tasks in most of the projects usually by adding complexity, model coding taking on average about twice the time of other topics, and the topics generally occurring in single blocks of time (at the resolution of the survey data collection) but with considerable overlaps. The results give an insight into the way experts approach simulation projects and their problem solving strategies. A potential application is in training novice modellers, particularly in developing ‘craft skills’. The results also provide an empirical basis for further research, especially in conceptual modelling

Experimental evaluation of user performance on two-dimensional and three-dimensional perspective displays in discrete-event simulation

Several experiments were carried out to compare the impacts of using a two dimensional (2D) plan view or a three dimensional (3D) perspective view in discrete event simulation visual displays. The experiments measured the performance of participants in spotting errors, describing the model, and suggesting improvements to the system. The participants using the 3D perspective display performed much better in spotting errors, taking on average about one third of the time of participants observing the 2D display. They also did much better in describing the model. There was no significant difference in suggesting improvements although this may have been because this task was easy. Most participants preferred the 3D perspective view when asked to compare the displays. The experiments indicate that the detailed design of the visual display may have a considerable effect on some of the tasks in a simulation project and hence on whether the overall project is successful

Strategic Decision Making for the North West Air Ambulance Charity Using Discrete Event Simulation

This paper is a preliminary investigation of the provision of enhanced emergency health care at night by North West Air Ambulance (NWAA). A discrete event simulation model of the current NWAA operational system is presented. This model is used to investigate the provision of NWAA services by an air ambulance vs. a rapid response vehicle. More widely, this model will be used within the scope of investigating what NWAA describe to be their ‘optimal service hours’

Agent-based simulation of herding in financial markets

There are several models of financial markets which look at the herding effect. This is a situation where many market traders act as a herd in that they all behave in a similar way with their trading. This type of behaviour may explain certain observed characteristics (or ‘stylised facts’) in real markets. However, the various models have different herding mechanisms and market settings This paper sets out the rationale of our approach and our initial work in trying to get a better understanding of herding in financial markets. Our research, though, is at an early stage. The basic methodology is to reproduce and compare some of the existing models, hopefully leading to a more general understanding and measure of herding and the relationship with market behaviour. One model has been investigated so far and this is described. A more general issue is the research importance of reproducing previous studies