(M-theory-)Killing spinors on symmetric spaces

We show how the theory of invariant principal bundle connections for reductive homogeneous spaces can be applied to determine the holonomy of generalised Killing spinor covariant derivatives of the form $D= \nabla + \Omega$ in a purely algebraic and algorithmic way, where $\Omega : TM \rightarrow \Lambda^*(TM)$ is a left-invariant homomorphism. Specialising this to the case of symmetric M-theory backgrounds (i.e. $(M,g,F)$ with $(M,g)$ a symmetric space and $F$ an invariant closed 4-form), we derive several criteria for such a background to preserve some supersymmetry and consequently find all supersymmetric symmetric M-theory backgrounds.Comment: Updated abstract for clarity. Added missing geometries to section 6. Main result stand

Studies of ''soft tooling'' for a semi- toroidal test tank Final report

Unfeasibility of soft tooling for semi-toroidal test tan

Attosecond electron pulses for 4D diffraction and microscopy

In this contribution, we consider the advancement of ultrafast electron diffraction and microscopy to cover the attosecond time domain. The concept is centered on the compression of femtosecond electron packets to trains of 15-attosecond pulses by the use of the ponderomotive force in synthesized gratings of optical fields. Such attosecond electron pulses are significantly shorter than those achievable with extreme UV light sources near 25 nm ({approx}50 eV) and have the potential for applications in the visualization of ultrafast electron dynamics, especially of atomic structures, clusters of atoms, and some materials

Deflation at Turnaround for Oscillatory Cosmology

It is suggested that dark energy in a brane world can help reconcile an infinitely cyclic cosmology with the second law of thermodynamics. A cyclic cosmology is described, in which dark energy with constant equation of state leads to a turnaround at finite future time, when entropy is decreased by a huge factor equal to the inverse of its enhancement during the initial inflation. Thermodynamic consistency of cyclicity requires the arrow of time to reverse during contraction. Entropy reduction in the contracting phase is infinitesimally smaller than entropy increase during expansion.Comment: 11 pages late

Looking for Intermediate-Mass Black Holes

A discussion of the entropy of the universe leads to the suggestion of very many intermediate-mass black holes between thirty and three hundred thousand solar masses in the halo. It is consistent with observations on wide binaries as well as microlensing and considerations of disk stability that such IMBHs constitute all cold dark matterComment: 4pp latex. Plenary talk at BSM-LHC conference, Northeastern University, June 200

Entropy of Contracting Universe in Cyclic Cosmology

Following up a recent proposal \cite{BF} for a cyclic model based on phantom dark energy, we examine the content of the contracting universe (cu) and its entropy $S_{cu}$. We find that beyond dark energy the universe contains on average zero or at most a single photon which if present immediately after turnaround has infinitesimally energy which subsequently blue shifts to produce $e^+e^-$ pairs. These statements are independent of the equation of state $\omega = p/\rho$ of dark energy provided $\omega < -1$. Thus $S_{cu} = 0$ and if observations confirm $\omega < -1$ the entropy problem is solved. We discuss the absence of a theoretical lower bound on $\phi = |\omega + 1|$, then describe an anthropic fine tuning argument that renders unlikely extremely small $\phi$. The present bound $\phi \lesssim 0.1$ already implies a time until turnaround of $(t_T - t_0) \gtrsim 100$ Gy.Comment: 5 pages late

CHARTS FOR EQUILIBRIUM FLOW PROPERTIES OF AIR IN HYPERVELOCITY NOZZLES

Charts for equilibrium flow properties of air in hypervelocity nozzle

Changes in the Balance Sheet of the U.S. Manufacturing Sector, 1926-1977

This is a report on the results of a research project, sponsored by the NBER's Program on Financial Markets and Monetary Economics, which involves the collection and organization of income account and balance sheet data, at the firm level, for the years 1926-77. The primary data source for the study is Moody's Industrial Manual. Working at the firm level, it is possible to obtain accurate information on the market values of traded securities.This paper presents and discusses some of the aggregate characteristics of the dataset and also reports the results of estimating a simple portfolio model which attempts to explain changes in firm balance sheet flows for the periods 1927-35 and 1965-77.The data collected for the study, as well as software necessary to manage them efficiently, are available from the authors. An NBER Technical Paper will shortly be available to describe the dataset and software in detail.