Universal properties in ultracold ion-atom interactions

We present some of the universal properties in ion-atom interaction derived from a newly formulated quantum-defect theory for $-1/r^4$ type of long-range interactions. For bound states, we present the universal bound spectrum, namely the equivalent of the Rydberg formula, for ion-atom systems. For scattering, we introduce the concept of universal resonance spectrum to give a systematic understanding of many resonances present in ion-atom scattering. The theory further provides a method for an accurate spectroscopic determination of the atomic polarizability. It also suggests the existence of atom-like molecules, in which multiple atoms orbit around a heavy ion.Comment: 4 pages, 2 figure

The Strong Levinson Theorem for the Dirac Equation

We consider the Dirac equation in one space dimension in the presence of a symmetric potential well. We connect the scattering phase shifts at E=+m and E=-m to the number of states that have left the positive energy continuum or joined the negative energy continuum respectively as the potential is turned on from zero.Comment: Submitted to Physical Review Letter

Semplates: A guide to identification and elicitation

Semplates are a new descriptive and theoretical concept in lexical semantics, borne out of recent L&C work in several domains. A semplate can be defined as a configuration consisting of distinct layers of lexemes, each layer drawn from a different form class, mapped onto the same abstract semantic template. Within such a lexical layer, the sense relations between the lexical items are inherited from the underlying template. Thus, the whole set of lexical layers and the underlying template form a cross-categorial configuration in the lexicon. The goal of this task is to find new kinds of macrostructure in the lexicon, with a view to cross-linguistic comparison

Approximated maximum likelihood estimation in multifractal random walks

We present an approximated maximum likelihood method for the multifractal random walk processes of [E. Bacry et al., Phys. Rev. E 64, 026103 (2001)]. The likelihood is computed using a Laplace approximation and a truncation in the dependency structure for the latent volatility. The procedure is implemented as a package in the R computer language. Its performance is tested on synthetic data and compared to an inference approach based on the generalized method of moments. The method is applied to estimate parameters for various financial stock indices.Comment: 8 pages, 3 figures, 2 table

CAUTION, PRECAUTION & COMMON SENSE: SOME THOUGHTS ON GMOS, ECOSYSTEMS, AND REGULATING THE UNKNOWN

As of 2014, genetically modified crops occupied 448 million acres globally, representing a global market value of 15.7 billion dollars. The United States planted 170 million acres of genetically engineered crops in 2012, including 95% of the nation's sugar beets, 94% of the soybeans, 90% of the cotton and 88% of the feed corn. While many argue that biotechnology is essential to ensuring long-term food security in the climate change era, little is known of its impact on ecosystems.  Potential risks such as changes in adaptive characteristics, gene flow, pest resistance, genotypic or phenotypic instability and adverse effects on non-target organisms must be balanced with the benefits of genetically modified crops. Despite much perseveration about the risks and benefits of GMOs, the United States regulatory regime has remained stagnant, unable to adapt to new innovations in the field. This lack of adequate oversight cannot go on. We propose shifting responsibility to a single agency charged with implementing science-based regulations that embrace the precautionary principle and promote early collaboration among stakeholders, multidisciplinary research, and well-designed monitoring. Part I of this Article provides an overview of biotechnology in modern agriculture.  More specifically, it evaluates potential benefits and risks associated with genetically modified crops. Part II outlines the United States regulatory regime as it applies to genetically modified crops.  Part III analyzes the current regulatory process, focusing specifically on the Department of Agriculture’s ineffective role in the environmental review process. Last, Part IV offers several potential adjustments to improve our ability to identify and mitigate the unforeseeable consequences of implementing this revolutionary technology.

Landscape terms and place names elicitation guide

Landscape terms reflect the relationship between geographic reality and human cognition. Are ‘mountains’, ‘rivers, ‘lakes’ and the like universally recognised in languages as naturally salient objects to be named? The landscape subproject is concerned with the interrelation between language, cognition and geography. Specifically, it investigates issues relating to how landforms are categorised cross-linguistically as well as the characteristics of place naming

Locally-anchored narrative

As for 'Locally-anchored spatial gestures task, version 2', a major goal of this task is to elicit locally-anchored spatial gestures across different cultures. “Locally-anchored spatial gestures” are gestures that are roughly oriented to the actual geographical direction of referents. Rather than set up an interview situation, this task involves recording informal, animated narrative delivered to a native-speaker interlocutor. Locally-anchored gestures produced in such narrative are roughly comparable to those collected in the interview task. The data collected can also be used to investigate a wide range of other topics

Scattering by a contact potential in three and lower dimensions

We consider the scattering of nonrelativistic particles in three dimensions by a contact potential $\Omega\hbar^2\delta(r)/ 2\mu r^\alpha$ which is defined as the $a\to 0$ limit of $\Omega\hbar^2\delta(r-a)/2\mu r^\alpha$. It is surprising that it gives a nonvanishing cross section when $\alpha=1$ and $\Omega=-1$. When the contact potential is approached by a spherical square well potential instead of the above spherical shell one, one obtains basically the same result except that the parameter $\Omega$ that gives a nonvanishing cross section is different. Similar problems in two and one dimensions are studied and results of the same nature are obtained.Comment: REVTeX, 9 pages, no figur