Antisymmetric Wilson loops in N=4\mathcal{N}=4 SYM beyond the planar limit

We study the $\frac{1}{2}$-BPS circular Wilson loop in the totally antisymmetric representation of the gauge group in $\mathcal N =4$ supersymmetric Yang-Mills. This observable is captured by a Gaussian matrix model with appropriate insertion. We compute the first $1/N$ correction at leading order in 't Hooft coupling by means of the matrix model loop equations. Disagreement with the 1-loop effective action of the holographically dual $D5$-brane suggests the need to account for gravitational backreaction on the string theory side.Comment: 20 pages, 4 figures; typos fixed, references adde

Worldsheet Instantons and the amplitude for string pair production in an external field as a WKB exact functional integral

We revisit the problem of charged string pair creation in a constant external electric field. The string states are massive and creation of pairs from the vacuum is a tunnelling process, analogous to the Schwinger process where charged particle-anti-particle pairs are created by an electric field. We find the instantons in the worldsheet sigma model which are responsible for the tunnelling events. We evaluate the sigma model partition function in the multi-instanton sector in the WKB approximation which keeps the classical action and integrates the quadratic fluctuations about the solution. We find that the summation of the result over all multi-instanton sectors reproduces the known amplitude. This suggests that corrections to the WKB limit must cancel. To show that they indeed cancel, we identify a fermionic symmetry of the sigma model which occurs in the instanton sectors and which is associated with collective coordinates. We demonstrate that the action is symmetric and that the interaction action is an exact form. These conditions are sufficient for localization of the worldsheet functional integral onto its WKB limit.Comment: 40 pages; Expanded discussion section, added reference

What are ‘universalizable interests’?

Many of Habermas's critical commentators agree that Discourse Ethics fails as a theory of the validity of moral norms and only succeeds as a theory of the democratic legitimacy of socio‐political norms. The reason they give is that the moral principle (U) is too restrictive to count as a necessary condition of the validity of norms. Other commentators more sympathetic to his project want to abandon principle (U) and remodel Discourse Ethics without it. Still others want to downplay the role of universalizing moral discourse and to make more of Habermas's less demanding, though still somewhat vague, conception of ethical discourse. Against this chorus of critical voices Habermas maintains that his conception of moral discourse and the moral principle (U) are central to Discourse Ethics in general, and to the normative heart of his political theory in particular. The conflict may have arisen in part because the concept of a ‘universalizable interest’ which is central to Habermas's understanding of moral discourse and of the moral principle (U) remains opaque even after nearly two decades of critical debate. Actually Habermas's concept of interest is pretty obscure too. But the obscurity surrounding the concept of interest is not the source of the confusion. For our present purposes we can simply stipulate that an interest is a reason to want. The notion of reason rests loosely on the notion of a need, and the concepts of need and desire are take left deliberately vague. The source of the current confusion lies in the notion of universalizability that is in play. Once we pay due attention to the conditions of the universalizability of interests contained in Habermas's formulation of the moral principle (U), we can distinguish between a weaker and a stronger version of the principle. I argue that only the weaker version is defensible. But I also want to show that Habermas is tempted into defending the stronger version, and to explain why he does so

Modernity and morality in Habermas's discourse ethics

Discourse ethics is originally conceived as a programme of philosophical justification of morality. This depends on the formal derivation of the moral principle (U) from non-moral principles. The moral theory is supposed to fall out of a pragmatic theory of meaning. The original programme plays a central role in Habermas's social theory: the moral theory, if true, provides good evidence for the more general theory of modernization. But neither Habermas nor his followers have succeeded in providing a formal derivation. This essay shows how and why Habermas's proposed derivation is impossible. As if aware of the lacuna, Habermas has recently suggested that (U) can be derived by 'abduction' rather than deduction. The proposal draws heavily on modernization theory; hence the only justification for (U) now available to him rests on premises drawn from that theory. The original programme of the justification of morality has thus given way to the weaker programme of the philosophical elucidation of morality. Further, since Habermas's moral theory is no longer justified independently of modernization theory, but at least partly by it, the moral theory cannot without circularity provide evidence for the modernization theory

Mechanical strain isolator mount

Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument

Diversification of Wairarapa hill country : the potential for agroforestry : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University

The purpose of this study was to investigate the potential for agroforestry on Wairarapa Hill Country farms. It was set against a background of a marked decline in real farm income on hill country sheep and beef farms in recent years. A broad perspective on project evaluation was taken with a review of the system components presented; covering hill country farming in New Zealand, the Wairarapa, Forestry in New Zealand, and Agroforestry. The results of an intertemporal linear programming model covering a 21 year period, suggest that agroforestry can be both a profitable and feasible investment for Wairarapa Hill Country farmers. Profitability is shown to be strongly influenced by the suitability of planting sites and final timber value. With respect to feasibility, cash-flow considerations are of overriding importance. Together with factors considered outside the model, particularly the management of an integrated livestock and agroforestry property, the need for individual evaluation of each circumstance is stressed. It is recommended that significant development of agroforestry in the Wairarapa will require some form of District Association to co-ordinate planting and marketing, and provide suitable extension and management services. Further development of the model for both agroforestry and land use evaluation is suggested

Equating decomposition numbers for different primes

This paper shows that certain decomposition numbers for the Hecke algebras and q-Schur algebras at different roots of unity in characteristic zero are equal. To prove our results we first establish the corresponding theorem for the canonical basis of the level one Fock space and then apply deep results of Ariki and Varagnolo and Vasserot.Comment: 13 pages. LaTeX2e + pstrick

Symmetric group blocks of small defect

This paper is an attempt to compute the decomposition numbers of the blocks of the symmetric group which have "small defect"; that is, blocks of weight smaller than the characteristic. We present various methods for computing such decomposition numbers and use these as support for a conjecture which relates decomposition numbers in different characteristics. Finally, we apply our techniques to blocks of weight three.Comment: 42 page

The Korean armistice of 1953 and its consequences - part I

Hoare: Both North and South Korea claim victory in the Korean War. Yet neither makes much of the ending of the war in July 1953, and both have had problems coming to terms with the reality of the war. The reality is that both suffered so much in a conflict that achieved little that formal celebrations seem inappropriate. Daniels: The outbreak of the Korean war in 1950 and the ferocious fighting which took place affected Britain, whose army took part in the war. This essay records the different shades of opinion expressed in its various newspapers/journals