Direct measurement of salt–mineral repulsion using atomic force microscopy

The disjoining pressure between a mineral and soluble salt crystal in concentrated aqueous solution has been successfully measured with atomic force microscopy

Wage Differentials in Italy: Market Forces, Institutions, and Inflation

During the 1970s, Italy experienced an extreme compression of wage differentials, similar to the better-known situation in Sweden. Most evidence suggests that this compression came to a stop around 1982-83, coincident with a major institutional change (in the form of the escalator clause in Italian union contracts), a major economic change (the slowdown in inflation), a major technological change (industrial restructuring and the computer revolution), and a major political change (the loss of support for unions and their egalitarian pay policies). While we cannot definitively distinguish among the relative influences of institutions, market forces, technology and politics on the evolution of earnings inequality in Italy, our analysis of skill level wage differentials and our comparisons at the individual level with the more laissez-faire system of the United States suggest that both inflation and egalitarian wage-setting institutions have importantly influenced Italian wage compression in the regular sector of the economy. Yet, this very compression may well have contributed to the flight away from the regular sector of the economy at both ends of the skill distribution, plausibly leading to a greater overall degree of inequality for the whole economy than is apparent from our analysis of wage differentials in the regular sector.

Capacity of Molecular Channels with Imperfect Particle-Intensity Modulation and Detection

This work introduces the particle-intensity channel (PIC) as a model for molecular communication systems and characterizes the properties of the optimal input distribution and the capacity limits for this system. In the PIC, the transmitter encodes information, in symbols of a given duration, based on the number of particles released, and the receiver detects and decodes the message based on the number of particles detected during the symbol interval. In this channel, the transmitter may be unable to control precisely the number of particles released, and the receiver may not detect all the particles that arrive. We demonstrate that the optimal input distribution for this channel always has mass points at zero and the maximum number of particles that can be released. We then consider diffusive particle transport, derive the capacity expression when the input distribution is binary, and show conditions under which the binary input is capacity-achieving. In particular, we demonstrate that when the transmitter cannot generate particles at a high rate, the optimal input distribution is binary.Comment: Accepted at IEEE International Symposium on Information Theory (ISIT

The Small World of Investing: Board Connections and Mutual Fund Returns

This paper uses social networks to identify information transfer in security markets. We focus on connections between mutual fund managers and corporate board members via shared education networks. We find that portfolio managers place larger bets on firms they are connected to through their network, and perform significantly better on these holdings relative to their non-connected holdings. A replicating portfolio of connected stocks outperforms a replicating portfolio of non-connected stocks by up to 8.4% per year. Returns are concentrated around corporate news announcements, consistent with mutual fund managers gaining an informational advantage through the education networks. Our results suggest that social networks may be an important mechanism for information flow into asset prices.

Towards a novel wave-extraction method for numerical relativity. I. Foundations and initial-value formulation

The Teukolsky formalism of black hole perturbation theory describes weak gravitational radiation generated by a mildly dynamical hole near equilibrium. A particular null tetrad of the background Kerr geometry, due to Kinnersley, plays a singularly important role within this formalism. In order to apply the rich physical intuition of Teukolsky's approach to the results of fully non-linear numerical simulations, one must approximate this Kinnersley tetrad using raw numerical data, with no a priori knowledge of a background. This paper addresses this issue by identifying the directions of the tetrad fields in a quasi-Kinnersley frame. This frame provides a unique, analytic extension of Kinnersley's definition for the Kerr geometry to a much broader class of space-times including not only arbitrary perturbations, but also many examples which differ non-perturbatively from Kerr. This paper establishes concrete limits delineating this class and outlines a scheme to calculate the quasi-Kinnersley frame in numerical codes based on the initial-value formulation of geometrodynamics.Comment: 11 pages, 1 figur

Scattering and Blow up for the Two Dimensional Focusing Quintic Nonlinear Schr\"odinger Equation

Using the concentration-compactness method and the localized virial type arguments, we study the behavior of $H^1$ solutions to the focusing quintic NLS in $\R^2$, namely, $$i \partial_t u+\Delta u+|u|^4u=0,\quad\quad (x, t) \in \R^2\times\R.$$ Denoting by $M[u]$ and $E[u]$, the mass and energy of a solution $u,$ respectively, and $Q$ the ground state solution to $-Q+\Delta Q+ |Q|^4Q=0$, and assuming $M[u]E[u] <M[Q]E[Q]$, we characterize the threshold for global versus finite time existence. Moreover, we show scattering for global existing time solutions and finite or "weak" blow up for the complement region. This work is in the spirit of Kenig and Merle and Duyckaerts, Holmer, and Roudenko.Comment: 37 pages, 2 figures and updated reference

Airborne environmental injuries and human health.

The concept that the environment in which we live can have detrimental effects on our health has existed for centuries. Obvious examples of substances that can cause human diseases include infectious agents, poisons, chemicals and other noxious agents, drugs, and physical stimuli such as bright lights and loud sounds. Some less obvious agents can include allergens, nontangible agents such as colorless, odorless gases and aerosolized toxins. In recent decades, humans have developed various new materials and compounds. Additionally, we are now producing known compounds, and even naturally occurring substances, in vastly increased amounts. Many of these substances are generally believed to threaten the health of our environment. However, there is also a considerable amount of hype and exaggeration regarding some of these agents (e.g., mold) that is unsubstantiated. This article extensively reviews the data on a large number of airborne-related illnesses and attempted to place scientific reality in the context of clinical medicine

Discussion of "Predicting water permeability in sedimentary rocks from capillary imbibition and pore structure" by D. Benavente et al., Engineering Geology (2015) [doi: 10.1016/j.enggeo.2015.06.003]

The relation between permeability and sorptivity has not received much attention in the literature of porous materials. Therefore the paper of Benavente et al. (Benavente et al., 2015) is a valuable contribution, both for its theoretical analysis and for providing new data on these properties in a test set of rocks, mostly carbonates. In this Discussion we make some related observations on the topic. We employ the quantities and notation of (Benavente et al., 2015), except that we use the sorptivity S rather than the water absorption coefficient C by capillarity” in describing imbibition. The two are simply related since S = C/ρw where ρw is the density of water