Enrico Fermi had to cajole his friend Ettore Majorana into publishing his big idea: a modification of the Dirac equation that would have profound ramifications for particle physics. Shortly afterwards, in 1938, Majorana mysteriously disappeared, and for 70 years his modified equation remained a rather obscure footnote in theoretical physics (Box 1). Now suddenly, it seems, Majorana’s concept is...

A ccording to Apple, “ ... certain celebrity accounts were compromised by a very targeted attack on user names, passwords, and security questions.”1 Didn’t we cover defensive privacy tactics in my January column?2 Color me dazed and confused! Hacking in cyberspace? Nothing like that’s ever happened before. (I’ve got another heads-up for you iPhone users—Siri talks about you behind your back. I’...

Despite the prevalence of mentally ill probationers, and probation officers' (POs') central role in their supervision, this is the first reported study to investigate how POs implement mandates to participate in psychiatric treatment. Five focus groups were conducted in major cities with 32 POs and 20 probationers representing a mix of traditional and "specialty" probation agencies. Three key f...

The happened before model has been widely used to model distributed computations In particular it has been used to model the logical time and the potential causality aspects of a distributed computation Though it is a good model for logical time we argue that it is not a good model for potential causality We introduce a better model for potential causality that extends happened before to allow ...

Most computational accounts of dialogue have assumed that once listeners have interpreted an utterance, they never change this interpretation. However, human interactions routinely violate this assumption. This is because people are necessarily limited in how much information they can make explicit. As a result, misunderstandings might occur--discourse participants might differ in their beliefs...

Clock synchronization is a crucial basic service in typical sensor networks, since the observations of distributed sensors more often than not need to be ordered (“a happened before b”) or otherwise related (“a and b happened within a time window of size x”) in time. Ad-hoc sensor networks exhibit characteristics which make the use of traditional clock-synchronization algorithms infeasible. Mor...

It is widely accepted that aggregate housing prices are predictable, but that excess returns to investors are precluded by the transactions costs of buying and selling property. We examine this issue using a unique data set—all private condominium transactions in Singapore during an eleven-year period. We model directly the price discovery process for individual dwellings. Our empirical results...

In radar systems, tracking targets in low signal-to-noise ratio (SNR) environments is a very important task. There are some algorithms designed for multitarget tracking. Their performances, however, are not satisfactory in low SNR environments. Track-before-detect (TBD) algorithms have been developed as a class of improved methods for tracking in low SNR environments. However, multitarget TBD i...

We develop a model of gradual information diffusion based on word of mouth communication. When news is initially released to a small fraction of investors, the expected diffusion rate (the change in the fraction of investors with the news) is initially increasing in time and only then decreases. Assuming risk-averse investors trade when they receive the news, the serial correlation of stock ret...