Working group report: Collider Physics

This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.     

The effects of gamma irradiation on the microbiological, physical and sensory qualities of diced tomatoes

Diced Roma tomatoes were treated with gamma irradiation and evaluated for changes in microbial, physical, chemical and sensory properties. Dosages for Trial 1 were 0.0, 0.39, 0.56 and 1.82 kGy and in Trial 2, 0.0, 0.50, 1.24 and 3.70 kGy. Irradiation at 3.70 kGy resulted in no aerobic populations through day 12 and significantly fewer colonies through day 15 whereas yeast and mold populations experienced a 2 log reduction through day 12. Color, titratable acidity, and °Brix were not significantly affected by irradiation. Tissue firmness decreased with increasing dose but not with storage time. Treatment with 3.7 kGy decreased firmness by 50% and 20% with 0.5 kGy, however, the reduced firmness induced by 0.50 kGy was undetected by a 9 member trained sensory panel. A significant (p0.05) inverse correlation between changes in texture and water-soluble pectin (WSP) was determined while total pectin remained relatively constant and oxalate soluble pectin content decreased slightly with irradiation dose. The significant inverse correlation between the loss of firmness and WSP indicates that the changes in WSP play an important role in the tissue softening of tomatoes, This study indicates that irradiation at 0.5 kGy can reduce microbial counts substantially to improve microbial shelf life without adverse effects on sensory qualities.     

On the singularity of Green's tensor for a perfectly conducting semi-infinite cone

This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field.     

Photochemistry of aryl tert-butyl ethers in methanol: the effect of substituents on an excited state cleavage reaction

The photolysis of a set of 10 substituted aryl tert-butyl ethers, 8a-j, in methanol gave, as the major product, the corresponding phenol along with tert-butyl-substituted phenols resulting from photo-Fries reaction. The corresponding 4-cyanophenyl 1-adamantyl ether, 9, also gave 1-methoxyadamantane 16 (16%), indicating that, at least for this ether, some of the products were ion-derived. Quenching studies with 2,3-dimethylbutadiene for the tert-butyl ethers indicated that these reactions were occurring from the singlet excited state. Rate constants for the reaction, obtained from quantum yields and singlet lifetimes, were found to correlate reasonably well with sigma(h)()(nu) values, rho = -0.77 (r = 0.975), a result that is unexpected for a reaction where the polarity of the bond breaking in the transition state is expected to be -O(delta-). C(delta+).     

Scattering by small defects in the neighbourhood of a fluid-solid interface

The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions.     

Are Real-Time Displays of Benefit in the Singing Studio? An Exploratory Study

This article reports on an exploratory research project to evaluate the usefulness or otherwise of real-time visual feedback in the singing studio. The primary purpose of the work was not to optimize the technology for this application, but to work alongside teachers and students to study the impact of real-time visual feedback technology use on the students' learning experiences. An action research methodology was used to explore the benefit of real-time displays over an extended period. The experimental phase of the work was guided by a Liaison Panel of teachers and academics in the areas of singing, pedagogy, voice science, speech therapy, and linguistic science. Qualitative data were collected from eight students working with two professional singing teachers. The teachers and students acted as co-researchers under the action research paradigm. Teachers and students alike kept journals of their teaching and learning experiences. Singing lessons were observed regularly by the research team, coded for teacher and student behaviors, and all co-researchers were interviewed at the mid- and endpoint of the project. The use of technology had a positive impact on the learning process, and this is evidenced through case study data.     

Phototransposition reactions of methyl-substituted benzotrifluorides: proof of the role of trifluoromethyl-substituted carbon

Irradiation in acetonitrile of any one of the six isomers of dimethylbenzotrifluoride 8 resulted in efficient photoisomerization to the others. The dominant processes in these phototransposition reactions divides the isomers into two triads. The first consists of 8-2,6 (2,6-dimethylbenzotrifluoride), 8-2,3, and 8-3,4; the second consists of 8-3,5, 8-2,4, and 8-2,5. Moreover, irradiation of 2,6-dideuterio-4-methylbenzotrifluoride 5-d(2) resulted in formation of 5,6-dideuterio-3-methylbenzotrifluoride 6-d(2). These observations demonstrate that it is the trifluoromethyl-substituted carbon that is the migratory one in these reactions.     

B and collider physics: Working group report

This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in Working group on ‘B and collider physics’.