Observation of the critical regime near Anderson localization of light

Diffusive transport is among the most common phenomena in nature [1]. However, as predicted by Anderson [2], diffusion may break down due to interference. This transition from diffusive transport to localization of waves should occur for any type of classical or quantum wave in any media as long as the wavelength becomes comparable to the transport mean free path $\ell^*$ [3]. The signatures of localization and those of absorption, or bound states, can however be similar, such that an unequivocal proof of the existence of wave localization in disordered bulk materials is still lacking. Here we present measurements of time resolved non-classical diffusion of visible light in strongly scattering samples, which cannot be explained by absorption, sample geometry or reduction in transport velocity. Deviations from classical diffusion increase strongly with decreasing $\ell^*$ as expected for a phase transition. This constitutes an experimental realization of the critical regime in the approach to Anderson localization.Comment: 5 pages, 4 figure

Widening mortality disparities by educational attainment among native-born Americans adults over 3 decades of follow up: the mystery deepens

Mortality disparities between high school dropouts and high school graduates may be widening over time. These changes could simply reflect demographic changes among dropouts over time or could represent changes to the cognitive or social benefits of education itself. We used a unique dataset that contains 32 years of survey data, 38 years of mortality follow-up data, and a wide array of psychological, sociological, cognitive, and demographic questions to explore the underlying causes of widening disparities in survival among high school dropouts relative to graduates. We focus on individuals surveyed from 1978 through 1997, and focus on ten-year survival for each respondent. We confirm that mortality disparities between high school dropouts and high school graduates have widened over time. We also find that the racial composition, parental education, racial mix of neighborhoods, income, and verbal IQ of high school dropouts and high school graduates have changed greatly over the past three decades. However, while each of these factors is itself an important determinant of survival, we find that none of these factors (or combinations of them) explain the widening mortality disparities by high school graduation status over the two time periods we study. The widening disparities in survival time by educational attainment we observe are not linked to changes in the socio-demographic characteristics of high school dropouts relative to high school graduates

Deposition And Drying Dynamics Of Liquid Crystal Droplets

Drop drying and deposition phenomena reveal a rich interplay of fundamental science and engineering, give rise to fascinating everyday effects (coffee rings), and influence technologies ranging from printing to genotyping. Here we investigate evaporation dynamics, morphology, and deposition patterns of drying lyotropic chromonic liquid crystal droplets. These drops differ from typical evaporating colloidal drops primarily due to their concentration-dependent isotropic, nematic, and columnar phases. Phase separation occurs during evaporation, and in the process creates surface tension gradients and significant density and viscosity variation within the droplet. As a result, the drying multiphase drops exhibit different convective currents, drop morphologies, and deposition patterns (coffee-rings)

Silicate-analogous borosulfates featuring promising luminescence and frequency-doubling (SHG) properties based on a rich crystal chemistry

Our contribution adresses important features of the emerging compound class of silicate-analogous borosulfates, i.e. their rich crystal chemistry, their exciting optical properties and of course their syntheses – the chemistry behind. Silicate-analogous materials comprise tetrahedral anionic basic building units lacking an inversion centre enhancing the chance of non-centrosymmetric surroundings of metal ions promoting excellent optical properties. Since the very first characterization of crystalline borosulfates in 2012 over sixty members have been found. Therein, the reaction of boric and sulfuric acid yields supertetrahedral BX4 (X=SO4) moieties giving rise to a rich crystal chemistry from non-condensed [B(SO4)4]5– anions via band (see Fig.) and layer structures to anionic frameworks [B(SO4)2]– – which can be understood by principles well known from silicates (see Fig.). The selective synthesis of borosulfates can be challenging but we meanwhile found some basic principles helping to selectively synthesize new compounds as phase-pure samples. Great impact is ascribed to the nature of the boron source, the metal (salt) employed and the amount of oleum added. On one hand, borosulfates feature a low coordination strength which is beneficial for the luminescence and UV-Vis properties of compounds containing lanthanide and transition metal ions, such as Ce3+ (see Fig.), Eu3+, Tb3+ or Co2+ and Ni2+. On the other hand, borosulfates frequently adopt non-centrosysmmetric structures yielding optical properties like SHG (second harmonic generation) which – in combination with large band-gaps – makes them highly promising materials for frequency doubling in the high energy regime. Also ionic conductivity was observed recently

Smart Fan

Modern box fans offer a simple solution to cooling an area. However, the simplicity that makes these fans appealing also limits their potential. A smart box fan that preserves its original simplicity while providing enhanced technological features such as smartphone connectivity and variable speed selection should lead to ease of use, improved performance, and increased customer satisfaction. To this end, a regular box fan will be instrumented and technology-enhanced, thus “smart fan.” The standard AC motor will be replaced with a DC motor for finer speed selection over the allowable range. The smart fan will offer three categories of operation: manual control, scheduled operation, and temperature-sensitive automation. Manual control operates the smart fan similarly to a standard box fan. Scheduled operation specifies the operation of the fan for any time. Temperature-sensitive automation will offer two modes. The first is a single-source mode that operates using a local temperature sensor. The second is a dual-source mode–intended for use in a window–that uses the temperature sensor and a weather API. Both modes operate by mapping speeds to a range of temperatures. The smart fan will allow users to run it when they want, how they want

Schrodinger equation for the one particle density matrix of thermal systems: An alternative formulation of Bose-Einstein condensation

We formulate a linear Schrodinger equation with the temperature-dependent potential for the one-particle density matrix and obtain the condensation temperature of the Bose-Einstein condensate from a bound-state condition for the Schrodinger equation both with and without the confining trap. The results are in very good agreement with those of the full statistical physics treatment. This is an alternative to the Bose-Einstein condensation in the standard ideal Bose gas treatment.Comment: 4 pages, 2 figure

Epigenetic aging signatures in mice livers are slowed by dwarfism, calorie restriction and rapamycin treatment

Background: Global but predictable changes impact the DNA methylome as we age, acting as a type of molecular clock. This clock can be hastened by conditions that decrease lifespan, raising the question of whether it can also be slowed, for example, by conditions that increase lifespan. Mice are particularly appealing organisms for studies of mammalian aging; however, epigenetic clocks have thus far been formulated only in humans. Results: We first examined whether mice and humans experience similar patterns of change in the methylome with age. We found moderate conservation of CpG sites for which methylation is altered with age, with both species showing an increase in methylome disorder during aging. Based on this analysis, we formulated an epigenetic-aging model in mice using the liver methylomes of 107 mice from 0.2 to 26.0 months old. To examine whether epigenetic aging signatures are slowed by longevity-promoting interventions, we analyzed 28 additional methylomes from mice subjected to lifespan-extending conditions, including Prop1df/df dwarfism, calorie restriction or dietary rapamycin. We found that mice treated with these lifespan-extending interventions were significantly younger in epigenetic age than their untreated, wild-type age-matched controls. Conclusions: This study shows that lifespan-extending conditions can slow molecular changes associated with an epigenetic clock in mice livers

Complete High Temperature Expansions for One-Loop Finite Temperature Effects

We develop exact, simple closed form expressions for partition functions associated with relativistic bosons and fermions in odd spatial dimensions. These expressions, valid at high temperature, include the effects of a non-trivial Polyakov loop and generalize well-known high temperature expansions. The key technical point is the proof of a set of Bessel function identities which resum low temperature expansions into high temperature expansions. The complete expressions for these partition functions can be used to obtain one-loop finite temperature contributions to effective potentials, and thus free energies and pressures.Comment: 9 pages, RevTeX, no figures. To be published in Phys. Rev D. v2 has revised introduction and conclusions, plus a few typographical errors are corrected; v3 corrects one typ

Revealing the Competition between Peeled-Ssdna, Melting Bubbles and S-DNA during DNA Overstretching using Fluorescence Microscopy

Understanding the structural changes occurring in double-stranded (ds)DNA during mechanical strain is essential to build a quantitative picture of how proteins interact and modify DNA. However, the elastic response of dsDNA to tension is only well-understood for forces < 65 pN. Above this force, torsionally unconstrained dsDNA gains ∼70% of its contour length, a process known as overstretching. The structure of overstretched DNA has proved elusive, resulting in a rich and controversial debate in recent years. At the centre of the debate is the question of whether overstretching yields a base-paired elongated structure, known as S-DNA, or instead forms single-stranded (ss)DNA via base-pair cleavage. Here, we show clearly, using a combination of fluorescence microscopy and optical tweezers, that both S-DNA and base-pair melted structures can exist, often concurrently, during overstretching. The balance between the two models is affected strongly by temperature and ionic strength. Moreover, we reveal, for the first time, that base-pair melting can proceed via two entirely different processes: progressive strand unpeeling from a free end in the backbone, or by the formation of ‘bubbles' of ssDNA, nucleating initially in AT-rich regions. We demonstrate that the mechanism of base-pair melting is governed by DNA topology: strand unpeeling is favored when there are free ends in the DNA backbone. Our studies settle a long running debate, and unite the contradictory dogmas of DNA overstretching. These findings have important implications for both medical and biological sciences. Force-induced melting transitions (yielding either peeled-ssDNA or melting bubbles) may play active roles in DNA replication and damage repair. Further, the ability to switch easily from DNA containing melting bubbles to S-DNA may be particularly advantageous in the cell, for instance during the formation of RNA within transcription bubbles. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved