Four Generations, Higgs Physics, and the MSSM

We consider the effects of a fourth generation of chiral fermions within the MSSM. Such a model offers the possibility of having the lightest neutral Higgs boson significantly heavier than in the three generation MSSM. The model is highly constrained by precision electroweak data, along with Higgs searches at the Tevatron. In addition, the requirements of perturbative unitarity and direct searches for heavy quarks imply that the four generation MSSM is only consistent for tan beta ~ 1 and highly tuned 4th generation fermion masses.Comment: References added and minor typographical errors correcte

Solar cell radiation flight experiment Quarterly progress report, 2 Dec. 1968 - 14 Mar. 1969

Design and test data of solar cells selected for flight on ATS-E for radiation effect

Past, Present and Future of UHECR Observations

Great advances have been made in the study of ultra-high energy cosmic rays (UHECR) in the past two decades. These include the discovery of the spectral cut-off near 5 x 10^19 eV and complex structure at lower energies, as well as increasingly precise information about the composition of cosmic rays as a function of energy. Important improvements in techniques, including extensive surface detector arrays and high resolution air fluorescence detectors, have been instrumental in facilitating this progress. We discuss the status of the field, including the open questions about the nature of spectral structure, systematic issues related to our understanding of composition, and emerging evidence for anisotropy at the highest energies. We review prospects for upgraded and future observatories including Telescope Array, Pierre Auger and JEM-EUSO and other space-based proposals, and discuss promising new technologies based on radio emission from extensive air showers produced by UHECR.Comment: Review paper accepted by Progress of Experimental and Theoretical Physics. 42 pages, 10 figures. Typo correcte

Exact Solution of a Jamming Transition: Closed Equations for a Bootstrap Percolation Problem

Jamming, or dynamical arrest, is a transition at which many particles stop moving in a collective manner. In nature it is brought about by, for example, increasing the packing density, changing the interactions between particles, or otherwise restricting the local motion of the elements of the system. The onset of collectivity occurs because, when one particle is blocked, it may lead to the blocking of a neighbor. That particle may then block one of its neighbors, these effects propagating across some typical domain of size named the dynamical correlation length. When this length diverges, the system becomes immobile. Even where it is finite but large the dynamics is dramatically slowed. Such phenomena lead to glasses, gels, and other very long-lived nonequilibrium solids. The bootstrap percolation models are the simplest examples describing these spatio-temporal correlations. We have been able to solve one such model in two dimensions exactly, exhibiting the precise evolution of the jamming correlations on approach to arrest. We believe that the nature of these correlations and the method we devise to solve the problem are quite general. Both should be of considerable help in further developing this field.Comment: 17 pages, 4 figure

QCD: Challenges for the Future

Despite many experimental verifications of the correctness of our basic understanding of QCD, there remain numerous open questions in strong interaction physics and we focus on the role of future colliders in addressing these questions. We discuss possible advances in the measurement of $\alpha_s$, in the study of parton distribution functions, and in the understanding of low $x$ physics at present colliders and potential new facilities. We also touch briefly on the role of spin physics in advancing our understanding of QCD.Comment: 12 pages, LATEX2e with snow2e, epsfig and 2 figures. Also available at http://penguin.phy.bnl.gov/~dawson/qcdsnow.ps . QCD working group summary at DPF/DPB Summer Study on New Directions for High Energy Physics, Snowmass, CO, June 25- July 12, 199

Global Hotspots of Conflict Risk between Food Security and Biodiversity Conservation

This work contributes to the Belmont Forum/FACCE-JPI DEVIL project (grant number NE/M021327/1), and AM is supported by a BBSRC EastBio Studentship (http://www.eastscotbiodtp.ac.uk/). The Conservation Biology Institute are acknowledged for provision of data as well as BirdLife International, IUCN, NatureServe, and USGS for their contribution of the species range map data used in producing data available from the Biodiversity Mapping website (http://biodiversitymapping.org).Peer reviewedPublisher PD

A marker suitable for sex-typing birds from degraded samples

A new primer set was developed for sex-typing birds, Z37B. This primer set was designed to amplify alleles of small size to render it suitable for sex-typing degraded samples, including shed feathers. This marker successfully sex-typed 50 % of the species tested, including passerines, shorebirds, rails, seabirds, eagles and the brown kiwi Apteryx australis (allele size range =81–103 bp), and is therefore expected to be suitable for sex-typing a wide range of species. Z37B sex-typed nondegraded samples (blood), degraded tissue (dead unhatched embryos, dead nestlings and museum specimens) and samples of low quantity DNA (plucked feathers and buccal swabs). The small amplicon sizes in birds suggest that this marker will be of utility for sex-typing feathers, swabs and degraded samples from a wide range of avian species