How a quark-gluon plasma phase modifies the bounds on extra dimensions from SN 1987a

The shape of the neutrino pulse from the supernova SN1987a provides one of the most stringent constraints on the size of large, compact, "gravity-only" extra dimensions. Previously, calculations have been carried out for a newly-born proto-neutron star with a temperature of about 50 MeV at nuclear matter density. It is arguable that, due to the extreme conditions in the interior of the star, matter might be a quark-gluon plasma, where the relevant degrees of freedom are quarks and gluons rather than nucleons. We consider an energy-loss scenario where seconds after rebounce the core of the star consists of a hot and dense quark-gluon plasma. Adopting a simplified model of the plasma we derive the necessary energy-loss formulae in the soft-radiation limit. The emissivity is found to be comparable to the one for nuclear matter and bounds on the radius of extra dimensions are similar to those found previously from nuclear matter calculations.Comment: 20 pages, 4 eps figures, revtex; typos corrected, revised treatment of the quark-gluon plasma, conclusions essentially unaltered; to appear in Nuclear Physics

Subset-lex: did we miss an order?

We generalize a well-known algorithm for the generation of all subsets of a set in lexicographic order with respect to the sets as lists of elements (subset-lex order). We obtain algorithms for various combinatorial objects such as the subsets of a multiset, compositions and partitions represented as lists of parts, and for certain restricted growth strings. The algorithms are often loopless and require at most one extra variable for the computation of the next object. The performance of the algorithms is very competitive even when not loopless. A Gray code corresponding to the subset-lex order and a Gray code for compositions that was found during this work are described.Comment: Two obvious errors corrected (indicated by "Correction:" in the LaTeX source

RF noise suppression using the photodielectric effect in semiconductors

Technique using photodielectric effect of semiconductor in high-Q superconductive cavity gives initial improvement of 2-4 db in signal-to-noise enhancement of conventional RF communication systems. Wide band signal plus noise can be transmitted through a narrow-band cavity due to parametric perturbation of the cavity frequency or phase

Re-thinking pedagogies: New immigrants in Aotearoa New Zealand early childhood settings

This chapter examines the importance of teacher orientations towards immigrant children, families, and teachers in early childhood education settings in Aotearoa New Zealand. Informed by a critical literature review and analysis,I highlight the complexity of cultural “otherness”and some tensions, risks, and dangers of superficial, simple interpretations of curriculum aspirations and guidelines. I argue that an orientation towards committed, sensitive, and accepting engagements is required to promote ethical and just practices. Following this, I argue that critical attention must be paid to interpretations of policy documents and guidelines for practice, and that ongoing questioning of possibilities for socially just professional practices are crucial to support diverse immigrants in early childhood settings

Do Credit Constraints Matter more for College Dropout Entrepreneurs?

Start-ups and their respective market partners are faced with severe problems of asymmetric information due to their lack of prior production history and reputation. Given this situation, it is most likely that outside financiers will not be informed about the potential gains, losses, and risks of the new venture. In our paper, we study how banks screen the abilities of the entrepreneurs. We argue that specific characteristics of the educational history of individuals signal their quality as founders. Namely, we expect banks to also use “college dropout” as an indicator when deciding to extend credit to a founder. We empirically test our hypotheses using a dataset of 189 German start-ups collected in 1998/99. Our hypothesis is borne out by the data. Applying ordered probit techniques we find that college dropouts have more difficulties to obtain the credit they need in the beginning of their start-up than those without college dropout experience.adverse selection, financial constraints, entrepreneurship, education

HIV/AIDS, human capital, and economic prospects for Mozambique

As in other countries in the southern Africa region, a human development catastrophe is unfolding in Mozambique. Recently released data estimate HIV prevalence rates amongst the adult population in the year 2000 at around 12% with substantial regional variation..... This paper is structured as follows. Section two discusses the implications of recently released HIV prevalence rates and provides more detail on the expected demographic impacts of the pandemic using available demographic projections. Section three reviews literature focusing on macroeconomic impacts. Section four formally analyzes implications for human capital accumulation. Section five presents the economy-wide modeling approach including critical assumptions and model scenarios. Section six discusses the major results. Section seven summarizes and section eight considers both reactive and preventive policy implications.....[The paper concludes that] the economic analysis and related policy implications provide strong support for adoption of both reactive and preventive policies. While the pandemic cannot be avoided, much can be done to reduce its harshness and duration. Some relatively broad policy options were also presented; however, as usual, the devils are in the details. Moving beyond these general policy ideas (both reactive and preventive) to real policy initiatives will require careful thought particularly with respect to issues of implementation.Human capital ,

The "more economic approach" in EU merger control: A critical assessment

With the "more economic approach" the EU is taking a new tack on merger control policy. This is visible not only in the new SIEC prohibition criterion and the criteria for appraising horizontal mergers but also in more recent decision-making practice. Greater legal certainty, on the one hand, and improved decision-making, on the other, have been cited as the aims of the (increased) use of industrial economics models and quantitative analysis. The objective of a (better) economic foundation in EU merger control is expressly welcomed. However, on closer analysis it is found that in point of fact the more economic approach in its present form creates less legal certainty, while the upshot in terms of the quality of the decision-making is at least unclear. At the same time, the (administrative) burden is likely to rise. Moreover, certain problems emerge for instance from the increasing involvement of economic experts or the possibilities for (industrial policy-related) political intervention. In conclusion, a broader perception of an economics-based approach which takes account especially of the institutional implications is called for. Specific recommendations are the establishment of an independent competition authority and the stronger orientation of merger control to (more) general rules. --Competition policy,EU merger control,economic analysis