Freeze Thaw Durability of Internally Cured Concrete Made Using Superabsorbent Polymers

The use of superabsorbent polymers (SAPs) to produce internally cured concrete has been shown to be effective in reducing the potential for restrained shrinkage cracking of high performance concrete mixtures. However, not much is known regarding the freeze–thaw durability of concrete mixtures that incorporate SAPs for internal curing (IC). When SAP particles desorb (or partially desorb) the “water” (pore fluid) they contain for the purposes of IC, some believe that the void space created by these particles can provide enough empty voids to accommodate the additional volume caused by water expansion upon freezing. This paper investigates the freeze–thaw durability of internally cured concrete by the use of SAPs. It has been shown that internally cured concretes made using SAP demonstrate good freeze–thaw performance when the concrete is air entrained. When the SAP was used in concrete without air entrainment it did not provide sufficient freeze–thaw durability

Evaluation of Sealers and Waterproofers for Extending the Life Cycle of Concrete

Concrete pavements represent a large portion of the transportation infrastructure. While the vast majority of concrete pavements provide excellent long-term performance, a portion of these pavements have recently shown premature joint deterioration. Substantial interest has developed in understanding why premature joint deterioration is being observed in jointed portland cement concrete pavements (PCCP). While some have attributed this damage to insufficient air void systems, poor mixture design, or chemical reaction between the salt and the paste, it is the hypothesis of this work that a component of this damage can be attributed to fluid absorption at the joints and chemical reactions between the salt and chemistry of the matrix. This paper discusses the role of soy methyl ester - polystyrene blends (SME-PS) as a potential method to extend the service life of concrete pavements by limiting the ingress of salt solutions. The report discusses field application of the SME-PS blends for field investigation in Lafayette and Fishers. Low temperature-differential scanning calorimetry (LT-DSC) techniques identified noticeable differences between plain mortar samples and mortar treated with SME-PS. The report also discusses the development of a test to assess chloride solution ingress during temperature cycling. The aim of this work is to provide background on some aspects that can lead to joint deterioration and provide early documentation showing that sealers may help to reduce the impact of deicers on joint damage, thereby extending the life of the concrete pavement. It should be noted that these sites as well as others are still ongoing and should be monitored for long term performance. Application procedure for SME-PS should follow manufacturer’s recommendation

The Transit Light Curve Project. IV. Five Transits of the Exoplanet OGLE-TR-10b

We present I and B photometry of five distinct transits of the exoplanet OGLE-TR-10b. By modeling the light curves, we find the planetary radius to be R_P = 1.06 +/- 0.08 R_Jup and the stellar radius to be R_S = 1.10 +/- 0.07 R_sun. The uncertainties are dominated by statistical errors in the photometry. Our estimate of the planetary radius is smaller than previous estimates that were based on lower-precision photometry, and hence the planet is not as anomalously large as was previously thought. We provide updated determinations of all the system parameters, including the transit ephemerides.Comment: Accepted in the Astrophysical Journal, 23 October 2006. Includes observations of additional transits to confirm earlier results. [15 pg, 6 figs

Public Willingness to Pay for Continuous and Probabilistic Hazard Information

Investments in new weather forecasting technologies and communication products can be costly and serve the ultimate purpose of protecting life and property. The Forecasting a Continuum of Environmental Threats (FACETs) paradigm attempts to improve technology and communication through the provision of probabilistic hazard information (PHI). The research and technology necessary to produce this information requires a substantial resource investment, but the societal value of the information may outweigh the costs. This study provides an initial estimate of this value by exploring public willingness to pay (WTP) for an app that provides continuously updated, geographically situated PHI that could be utilized during a tornado event. Findings indicate that the mean WTP, in a one-time payment, for this precise hazard information product is $7.53 per person. Aggregated to the US population, the estimated value is between$901 million and $1.56 billion. These findings indicate that federal agencies and private companies are likely to generate a substantial surplus by developing these products and will contribute to improving informed decision-making and protecting lives and property

Linear solvers for power grid optimization problems: a review of GPU-accelerated linear solvers

The linear equations that arise in interior methods for constrained optimization are sparse symmetric indefinite and become extremely ill-conditioned as the interior method converges. These linear systems present a challenge for existing solver frameworks based on sparse LU or LDL^T decompositions. We benchmark five well known direct linear solver packages using matrices extracted from power grid optimization problems. The achieved solution accuracy varies greatly among the packages. None of the tested packages delivers significant GPU acceleration for our test cases

Ultrafast dynamics in light-driven molecular rotary motors probed by femtosecond stimulated raman spectroscopy

Photochemical isomerization in sterically crowded chiral alkenes is the driving force for molecular rotary motors in nanoscale machines. Here the excited state dynamics and structural evolution of the prototypical light driven rotary motor are followed on the ultrafast timescale by femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption (TA). TA reveals a sub 100 fs blue shift and decay of the Franck-Condon bright state arising from relaxation along the reactive potential energy surface. The decay is accompanied by coherently excited vibrational dynamics which survive the excited state structural evolution. The ultrafast Franck-Condon bright state relaxation is to a dark excited state, which FSRS reveals to have a rich spectrum compared to the electronic ground state, with the most intense Raman active modes shifted to significantly lower wavenumber. This is discussed in terms of a reduced bond order of the central bridging bond and overall weakening of bonds in the dark state, which is supported by electronic structure calculations. The observed evolution in the FSRS spectrum is assigned to vibrational cooling accompanied by partitioning of the dark state between the product isomer and the original ground state. Formation of the product isomer is observed in real time by FSRS. It is formed vibrationally hot and cools over several picoseconds, completing the characterization of the light driven half of the photocycle

Diagnosis, Management, and Investigational Therapies for Food Allergies

Food allergies have increased in prevalence over the past 20 years, now becoming an important public health concern. Although there are no therapies currently available for routine clinical care, recent reports have indicated that immunotherapies targeting the mucosal immune system may be effective. Oral immunotherapy is conducted by administering small, increasing amounts of food allergen; it has shown promise for desensitizing individuals with peanut, egg, or milk allergies. Sublingual immunotherapy also desensitizes allergic patients to foods—2 major studies have examined the effects of sublingual immunotherapy in subjects with peanut allergies. We review the complex nature of IgE-mediated food allergies and the therapies being evaluated in clinical trials. We focus on the diagnosis and management of food allergies and investigational therapies

Willingness and Ability of Older Adults in the Emergency Department to Provide Clinical Information Using a Tablet Computer

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134983/1/jgs14366.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134983/2/jgs14366_am.pd

Impact of Allergic Reactions on Food-Specific IgE Concentrations and Skin Test Results

Although there is concern that food allergic reactions may negatively affect the natural history of food allergy, the impact of reactions on food-specific IgE (sIgE) or skin prick tests is unknown