Constraints on Theories With Large Extra Dimensions

Recently, a number of authors have challenged the conventional assumption that the string scale, Planck mass, and unification scale are roughly comparable. It has been suggested that the string scale could be as low as a TeV. In this note, we explore constraints on these scenarios. We argue that the most plausible cases have a fundamental scale of at least 10 TeV and five dimensions of inverse size 10 MeV. We show that a radial dilaton mass in the range of proposed millimeter scale gravitational arises naturally in these scenarios. Most other scenarios require huge values of flux and may not be realizable in M Theory. Existing precision experiments put a conservative lower bound of 6-10 TeV on the fundamental energy scale. We note that large dimensions with bulk supersymmetry might be a natural framework for quintessence, and make some other tentative remarks about cosmology.Comment: 31 pp. latex. Minor changes, ref. problems fixe

TRIP13PCH-2 promotes Mad2 localization to unattached kinetochores in the spindle checkpoint response.

The spindle checkpoint acts during cell division to prevent aneuploidy, a hallmark of cancer. During checkpoint activation, Mad1 recruits Mad2 to kinetochores to generate a signal that delays anaphase onset. Yet, whether additional factors contribute to Mad2's kinetochore localization remains unclear. Here, we report that the conserved AAA+ ATPase TRIP13(PCH-2) localizes to unattached kinetochores and is required for spindle checkpoint activation in Caenorhabditis elegans. pch-2 mutants effectively localized Mad1 to unattached kinetochores, but Mad2 recruitment was significantly reduced. Furthermore, we show that the C. elegans orthologue of the Mad2 inhibitor p31(comet)(CMT-1) interacts with TRIP13(PCH-2) and is required for its localization to unattached kinetochores. These factors also genetically interact, as loss of p31(comet)(CMT-1) partially suppressed the requirement for TRIP13(PCH-2) in Mad2 localization and spindle checkpoint signaling. These data support a model in which the ability of TRIP13(PCH-2) to disassemble a p31(comet)/Mad2 complex, which has been well characterized in the context of checkpoint silencing, is also critical for spindle checkpoint activation

What is the valence of Mn in Ga1−x_{1-x}Mnx_xN?

We investigate the current debate on the Mn valence in Ga$_{1-x}$Mn$_x$N, a diluted magnetic semiconductor (DMSs) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to $2+$ ($d^5$), but in a mixed spin configuration with average magnetic moments of 4$\mu_B$. By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: 1) an effective $d^4$ picture ideal for local physics, and 2) an effective $d^5$ picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.Comment: 4 figure

In the shadows of the national recovery: an overview of New England's economic performance in 2005

Annual review of the economic performance of the New England states.Economic conditions - New England

The economic performance of the New England states in 2004: an overview

The year 2004 marked the beginning of New England’s economic turnaround. After three consecutive years of job losses — not to mention 86 years of World Series famine — the region emerged victorious. All six New England states added jobs over the course of the year and experienced reductions in unemployment. Job growth in the region, however, was sluggish compared with the nation overall. Recovery was also reflected in strong exports growth, increases in the economic activity index, and improved consumer confidence. Although consumer price inflation in New England was milder than in recent years, home prices continued to escalate at above-average rates.Economic conditions - New England

Growing... but slowing? : an overview of New England's economic performance in 2006

New England’s economic performance was somewhat mixed during 2006. On one hand, all six states added jobs over the course of the year, and the region’s unemployment rate remained steady. The region as a whole picked up jobs in nearly all major industries. Export values and income and wages also increased. One the other hand, much of the economic growth experienced by the region was slower than that seen in the nation as a whole. Although the unemployment rate did not go up for the region, the nation saw joblessness decrease. Moreover, real estate markets, though weak nationwide, were even weaker in the region.Economic conditions - New England ; Economic conditions - Connecticut ; Economic conditions - Maine ; Economic conditions - Massachusetts ; Economic conditions - New Hampshire ; Economic conditions - Rhode Island ; Economic conditions - Vermont

Effects of coastal managed retreat on mercury biogeochemistry

We investigated the impact of managed retreat on mercury (Hg) biogeochemistry at a site subject to diffuse contamination with Hg. We collected sediment cores from an area of land behind a dyke one year before and one year after it was intentionally breached. These sediments were compared to those of an adjacent mudflat and a salt marsh. The concentration of total mercury (THg) in the sediment doubled after the dyke was breached due to the deposition of fresh sediment that had a smaller particle size, and higher pH. The concentration of methylmercury (MeHg) was 27% lower in the sediments after the dyke was breached. We conclude that coastal flooding during managed retreat of coastal flood defences at this site has not increased the risk of Hg methylation or bioavailability during the first year. As the sediment becomes vegetated, increased activity of Hg-methylating bacteria may accelerate Hg-methylation rate