Untitled: A Study of Formal and Informal Property Rights in Urban Ecuador

In this paper we explore the substitutability of formal and informal property rights. We analyze new survey data from Ecuador, where households have both formal and informal claims to urban residential property. The latter come from a variety of sources, including the activity of a local boss, or organizer. We first develop a theory of the ability to sell or rent land in which a distinction is drawn between transferable property rights (e.g., title) and non-transferable claims (e.g., length of residence). We use this theory of transactions to show that the increase in price that follows the granting of title may be an overestimate of the households' utility gain. In our empirical work we find that the unconditional effect of granting title is to raise properties' value by 23.5%. However, we also find that informal property rights can substitute effectively for formal property rights, so the marginal effect of titling on the ability to transact and on prices can vary widely among communities and among households within a community. For example, the value of property owned by a newly established household with no adult males can increase by 46% with the acquisition of title. These findings suggest that titling programs should be targeted at young disorganized communities if they are to have much effect.

An ion resonance instability in grossly non-neutral plasmas

Ion resonance instability in grossly non-neutral plasma

Scale invariant correlations and the distribution of prime numbers

Negative correlations in the distribution of prime numbers are found to display a scale invariance. This occurs in conjunction with a nonstationary behavior. We compare the prime number series to a type of fractional Brownian motion which incorporates both the scale invariance and the nonstationary behavior. Interesting discrepancies remain. The scale invariance also appears to imply the Riemann hypothesis and we study the use of the former as a test of the latter.Comment: 13 pages, 8 figures, version to appear in J. Phys.

Electrical manipulation of an electronic two-state system in Ge/Si quantum dots

We calculate that the electron states of strained self-assembled Ge/Si quantum dots provide a convenient two-state system for electrical control. An electronic state localized at the apex of the quantum dot is nearly degenerate with a state localized at the base of the quantum dot. Small electric fields shift the electronic ground state from apex-localized to base-localized, which permits sensitive tuning of the electronic, optical and magnetic properties of the dot. As one example, we describe how spin-spin coupling between two Ge/Si dots can be controlled very sensitively by shifting the individual dot's electronic ground state between apex and base

Novel tools integrating metabolic and gene function to study the impact of the environment on coral symbiosis

© 2014 Pernice and Levy. The symbiotic dinoflagellates (genus Symbiodinium) inhabiting coral endodermal tissues are well known for their role as keystone symbiotic partners, providing corals with enormous amounts of energy acquired via photosynthesis and the absorption of dissolved nutrients. In the past few decades, corals reefs worldwide have been increasingly affected by coral bleaching (i.e., the breakdown of the symbiosis between corals and their dinoflagellate symbionts), which carries important socio-economic implications. Consequently, the number of studies focusing on the molecular and cellular processes underlying this biological phenomenon has grown rapidly, and symbiosis is now widely recognized as a major topic in coral biology. However, obtaining a clear image of the interplay between the environment and this mutualistic symbiosis remains challenging. Here, we review the potential of recent technological advances in molecular biology and approaches using stable isotopes to fill critical knowledge gaps regarding coral symbiotic function. Finally, we emphasize that the largest opportunity to achieve the full potential in this field arises from the integration of these technological advances

Fast Matrix Factorization for Online Recommendation with Implicit Feedback

This paper contributes improvements on both the effectiveness and efficiency of Matrix Factorization (MF) methods for implicit feedback. We highlight two critical issues of existing works. First, due to the large space of unobserved feedback, most existing works resort to assign a uniform weight to the missing data to reduce computational complexity. However, such a uniform assumption is invalid in real-world settings. Second, most methods are also designed in an offline setting and fail to keep up with the dynamic nature of online data. We address the above two issues in learning MF models from implicit feedback. We first propose to weight the missing data based on item popularity, which is more effective and flexible than the uniform-weight assumption. However, such a non-uniform weighting poses efficiency challenge in learning the model. To address this, we specifically design a new learning algorithm based on the element-wise Alternating Least Squares (eALS) technique, for efficiently optimizing a MF model with variably-weighted missing data. We exploit this efficiency to then seamlessly devise an incremental update strategy that instantly refreshes a MF model given new feedback. Through comprehensive experiments on two public datasets in both offline and online protocols, we show that our eALS method consistently outperforms state-of-the-art implicit MF methods. Our implementation is available at https://github.com/hexiangnan/sigir16-eals.Comment: 10 pages, 8 figure

Compressing Word Embeddings

Recent methods for learning vector space representations of words have succeeded in capturing fine-grained semantic and syntactic regularities using vector arithmetic. However, these vector space representations (created through large-scale text analysis) are typically stored verbatim, since their internal structure is opaque. Using word-analogy tests to monitor the level of detail stored in compressed re-representations of the same vector space, the trade-offs between the reduction in memory usage and expressiveness are investigated. A simple scheme is outlined that can reduce the memory footprint of a state-of-the-art embedding by a factor of 10, with only minimal impact on performance. Then, using the same `bit budget', a binary (approximate) factorisation of the same space is also explored, with the aim of creating an equivalent representation with better interpretability.Comment: 10 pages, 0 figures, submitted to ICONIP-2016. Previous experimental results were submitted to ICLR-2016, but the paper has been significantly updated, since a new experimental set-up worked much bette

A comparison of cognitive restructuring and thought listing for excessive acquiring in hoarding disorder

Excessive acquiring is a common symptom of hoarding disorder (HD). Little is known about subjective distress associated with acquiring in HD. The present study examined acquiring- related distress and reactions to cognitive restructuring (CR) in 92 individuals with HD and 66 community control (CC) participants. All participants identified an item of interest at a high-risk acquiring location and then decided whether or not to acquire the item. HD participants completed the acquiring task while receiving a CR-based intervention or a thought-listing (TL) control condition. Results showed that HD participants reported more severe distress and greater urges to acquire the item of interest than did CC participants. Nevertheless, subjective distress decreased in both groups following the acquiring task. There were no differences in acquiring- related distress between the CR and TL conditions. The findings indicate that subjective distress may decrease after relatively short periods of time in individuals with HD, but that a single session of CR may not alleviate acquiring-related distress in HD participants.R01 MH068007 - NIMH NIH HHS; R01 MH068008 - NIMH NIH HHSAccepted manuscrip

A Difficult Question in Deed: A Cost-Benefit Framework for Titling Programs

In this Article we explore the potential benefits and costs of a program to grant title to individuals who are occupying land informally. Only some of these benefits and costs have received careful empirical consideration in the literature. This Article references existing studies and draws on findings from original surveys of urban households in Ecuador. We consider how a titling program might affect the welfare of landowners and occupants, how it could alter the functioning of real estate markets, and whether it could build a community\u27s social capital. Potential benefits must be weighed against a range of costs, including those accruing to the government for implementation of the program, as well as those perceived by individuals in their efforts to obtain title. There also may be dynamic implications of a titling program. For example, these programs can spur further land invasions and render the role of intermediaries more lucrative. The importance of formal property rights and of formal legal systems in governing transactions and land use is of particular interest given that property rights are frequently assigned the prominent role of a prerequisite to economic growth