Supersymmetric coupling of a self-dual string to a (2,0) tensor multiplet background

We construct an interaction between a (2,0) tensor multiplet in six dimensions and a self-dual string. The interaction is a sum of a Nambu-Goto term, with the tension of the string given by the modulus of the scalar fields of the tensor multiplet, and a non-local Wess-Zumino term, that encodes the electromagnetic coupling of the string to the two-form gauge field of the tensor multiplet. The interaction is invariant under global (2,0) supersymmetry, modulo the equations of motion of a free tensor multiplet. It is also invariant under a local fermionic kappa-symmetry, as required by the BPS-property of the string.Comment: 12 pages, LaTe

Energy radiated from a fluctuating selfdual string

We compute the energy that is radiated from a fluctuating selfdual string in the large $N$ limit of $A_{N-1}$ theory using the AdS-CFT correspondence. We find that the radiated energy is given by a non-local expression integrated over the string world-sheet. We also make the corresponding computation for a charged string in six-dimensional classical electrodynamics, thereby generalizing the Larmor formula for the radiated energy from an accelerated point particle.Comment: 12 page

Free tensor multiplets and strings in spontaneously broken six-dimensional (2,0) theory

We first review the representations of the six-dimensional (2,0) superalgebra on a free tensor multiplet and on a free string. We then construct a supersymmetric Lagrangian describing a free tensor multiplet. (It also includes a decoupled anti self-dual part of the three-form field strength.) This field theory is then rewritten in variables appropriate for analyzing a situation where the R-symmetry is spontaneously broken by the vacuum expectation values of the scalar moduli fields. Finally, we construct a supersymmetric and kappa-symmetric action for a free string.Comment: 15 pages, LaTe

Thomson scattering of chiral tensors and scalars against a self-dual string

We give a non-technical outline of a program to study the (2,0) theories in six space-time dimensions. Away from the origin of their moduli space, these theories describe the interactions of tensor multiplets and self-dual spinning strings. We argue that if the ratio between the square of the energy of a process and the string tension is taken to be small, it should be possible to study the dynamics of such a system perturbatively in this parameter. As a first step in this direction, we perform a classical computation of the amplitude for scattering chiral tensor and scalar fields (i.e. the bosonic part of a tensor multiplet) against a self-dual spinnless string.Comment: 24 pages, LaTeX, 2 figures. v2: added discussion on supersymmetry in Ch.

Comparison of methods for determining the fatty acid composition of photosynthetic tissues

The fatty acid (FA) composition of photosynthetic tissue differs from that in other plant or animal tissues. In leaves, the lipid fraction constitutes less than 10% of the dry weight and is mostly located in the chloroplasts. An extraction solvent should dissolve polar lipids readily, but should also overcome interactions between the lipids and the tissue matrix. A mixture of chloroform/methanol (C/M) is commonly used. However, less toxic alternative methods such as hexane/isopropanol (H/I) and ethanol (E) have been suggested. In this preliminary study we compared the effectiveness of these three methods which are used as standard extraction protocols for FA analysis of plant material at three different European Universities. C/M extraction gave the highest total FA content and H/I the lowest, suggesting that C/M is indeed the best general-purpose lipid extraction solvent. Significant differences were also observed for FA composition including the ratio of saturated to unsaturated FA indicating selectivity of the various solvents in extracting different individual FA. Further and more detailed investigations are required to confirm this hypothesi

Classical self-dual strings in d=6, (2,0) theory from afar

We show how one can get solitonic strings in a six-dimensional (2,0) supersymmetric theory by incorporating a nonlinear interaction term. We derive a zero force condition between parallel strings, and compute a metric on a moduli space which is $R^4$ when the strings are far apart. When compactifying the strings on a two-torus we show that, in the limit of vanishing two-torus, one regains the moduli space of two widely separated dyons of equal magnetic charges in four dimensions.Comment: 13 pages, clarifications and added reference

Conformal anomaly of Wilson surface observables - a field theoretical computation

We make an exact field theoretical computation of the conformal anomaly for two-dimensional submanifold observables. By including a scalar field in the definition for the Wilson surface, as appropriate for a spontaneously broken A_1 theory, we get a conformal anomaly which is such that N times it is equal to the anomaly that was computed in hep-th/9901021 in the large N limit and which relied on the AdS-CFT correspondence. We also show how the spherical surface observable can be expressed as a conformal anomaly.Comment: 18 pages, V3: an `i' dropped in the Wilson surface, overall normalization and misprints corrected, V4: overall normalization factor corrected, references adde

Near- to mid-infrared picosecond optical parametric oscillator based on periodically poled RbTiOAsO4

We describe a Ti:sapphire-pumped picosecond optical parametric oscillator based on periodically poled RbTiOAsO4 that is broadly tunable in the near to mid infrared. A 4.5-mm single-grating crystal at room temperature in combination with pump wavelength tuning provided access to a continuous-tuning range from 3.35 to 5 mu m, and a pump power threshold of 90 mW was measured. Average mid-infrared output powers in excess of 100 mW and total output powers of 400 mW in similar to 1-ps pulses were obtained at 33% extraction efficiency. (C) 1998 Optical Society of America.</p

Is an ethical economy possible: new forms of value in the information society?

In recent decades managerial discourse and actual business practice has paid increasing attention to ethics. What was chiefly an academic discussion about business ethics has grown into a virtual 'ethics industry' (Hyatt, 2005), and has been supplanted by a growing focus on corporate social responsibility and a booming consumer demand for ethical or 'fair' goods. Critical observers, myself included, have tended to dismiss this focus on ethics as little more than a cynical response to the new demands put forth by a more networked and better informed public opinion. Together with the managerial promotion of ideals like 'creativity' or 'self-actualization', such 'ethics-talk' has been read as part of a New Spirit of Capitalism, in which the critique put forth by the social movements of the Sixties and Seventies has been incorporated and transformed into a new way of legitimizing the same old forms of exploitation and capital accumulation (Boltanski & Chiapello, 1999). In this short piece I would like to try out a different approach. I will suggest, quite provocatively, that the managerial focus on ethics is more than just a cynical move. Nor is it merely a matter of benevolence. Rather, it reflects an important structural transformation within the information society: the growth of a number of strategically central, albeit quantitatively marginal productive practices: all working according to a logic where value is related to the quality of social relations, and not to the quantity of productive time, or as Marxists would say, socially necessary labor time. These diverse practices, which I collectively refer to as 'the ethical economy', are located within the boundaries of the corporate world, as in the case of new forms of knowledge work. But they also transpire outside of, or even in opposition to corporate capitalism, as in the case of more purist forms of Free Software. These processes are generally located at the top end of contemporary value chains and they have all to do with the production or manipulation of information and affect, like experiences, events and brand image. As such they have all been significantly empowered by the spread of networked information and communication technologies. The traversal nature of this ethical economy means that it is likely that its further growth and consolidation will quite radically redraw the boundaries of capitalist economy and redefine the field of conflict and compromise on which it evolves. (This is already visible in intensifying struggles over intellectual property and the 2 emergence of powerful hybrid forms like the social entrepreneurship movement, cf. Boyle, 2008.) The fact that the ethical economy is closely linked to information technology, or, more precisely, that it emerges out of the extended forms of cooperation that these technologies enable, implies that the ethical economy is likely to be central to the emerging economic ecology of the information society. The ethical economy might even become hegemonic to that ecology. Will value in the information society be conceived of as organized around ethics, just as it was conceived of as organized around labor in industrial society? That would amount to nothing less than a mutation in the socially dominant value form, a rare and radical kind of social transformation which has, nevertheless, occurred before (as when 'labor' and 'self-interest' emerged as central forms of value and motivation out of the tumultuous transformations of the European 17th century (Hirschman, 1977, Linebaugh & Rediker, 2000)