Effect of carbonation on the hydro-mechanical properties of Portland cements

We evaluate experimentally the effect of carbonation on the hydro-mechanical properties of Portland cement. Samples were carbonated at 90 °C and 28 MPa under wet supercritical CO₂. Two types of carbonation features were achieved, either the samples were homogeneously carbonated or they displayed sharp carbonation fronts. Using a tri-axial apparatus, the static elastic moduli and the mechanical strength were measured at in-situ pressure conditions (28 MPa) and showed a degradation of the mechanical properties of the samples where a carbonation front prevailed. Water and gas permeabilities were measured and showed that the samples with a carbonation front exhibit a stress sensitive permeability. P and S elastic wave velocities were measured to evaluate dynamic (ultrasonic range, 1 MHz) elastic moduli. The use of an effective medium theory approach enabled us to characterize the density and distribution of cracks within the samples. This approach outlines that the samples which developed a carbonation front were damaged.     

Evaluation of seeing-induced cross talk in tip-tilt-corrected solar polarimetry

We reanalyze the effects of atmosphere-induced image motions on the measurement of solar polarized light using a formalism developed by Lites. Our reanalysis is prompted by the advent of adaptive optics (AO) systems that reduce image motion and higher-order aberrations, by the availability of liquid crystals as modulation devices, and by the need to understand how best to design polarimeters for future telescopes such as the Advanced Technology Solar Telescope. In this first attempt to understand the major issues, we analyze the influence of residual image motion (tip-tilt) corrections of operational AO systems on the cross talk between Stokes parameters and present results for several polarization analysis schemes. Higher-order wave-front corrections are left for future research. We also restrict our discussion to the solar photosphere, which limits several important parameters of interest, using some recent magnetoconvection simulations.     

Emotion enhances the subjective feeling of remembering, despite lower accuracy for contextual details.

Emotion strengthens the subjective experience of recollection. However, these vivid and confidently remembered emotional memories may not necessarily be more accurate. We investigated whether the subjective sense of recollection for negative stimuli is coupled with enhanced memory accuracy for contextual details using the remember/know paradigm. Our results indicate a double-dissociation between the subjective feeling of remembering, and the objective memory accuracy for details of negative and neutral scenes. “Remember” judgments were boosted for negative relative to neutral scenes. In contrast, memory for contextual details and associative binding was worse for negative compared to neutral scenes given a “remember” response. These findings show that the enhanced subjective recollective experience for negative stimuli does not reliably indicate greater objective recollection, at least of the details tested, and thus may be driven by a different mechanism than the subjective recollective experience for neutral stimuli. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Does preinjury alcohol use or blood alcohol level influence cognitive functioning after traumatic brain injury?

Objective: To examine the relations among preinjury alcohol use patterns and admission blood alcohol level (BAL) and postinjury cognitive functioning among individuals with recent TBI. Design: Cohort survey with chart review and follow-up cognitive assessment. Setting: Acute inpatient rehabilitation program in a Level I trauma center. Participants: 124 consecutive initial admissions meeting inclusion criteria. Measures: Admission BAL, preinjury alcohol consumption, consequences, and symptoms of dependence, as well as initial injury severity and subsequent cognitive functioning. Results: Higher BAL at hospital admission was related to greater initial injury severity (lower Glasgow Coma Scale score). Preinjury alcohol consumption and admission BAL were not consistently related to any postinjury assessment of cognition. Conclusion: Alcohol use at the time of injury may exacerbate the initial severity of TBI. Cognitive functioning soon after injury does not appear to be related to any preinjury drinking behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Target discrimination by RNA-binding proteins: role of the ancillary protein U2A' and a critical leucine residue in differentiating the RNA-binding specificity of spliceosomal proteins U1A and U2B"

The spliceosomal proteins U1A and U2B" each use a homologous RRM domain to bind specifically to their respective snRNA targets, U1hpll and U2hpIV, two stem-loops that are similar yet distinct in sequence. Previous studies have shown that binding of U2B" to U2hpIV is facilitated by the ancillary protein U2A', whereas specific binding of U1A to U1hpll requires no cofactor. Here we report that U2A' enables U2B" to distinguish the loop sequence of U2hpIV from that of U1hpll but plays no role in stem sequence discrimination. Although U2A' can also promote heterospecific binding of U1A to U2hpIV, a much higher concentration of the ancillary protein is required due to the approximately 500-fold greater affinity of U2A' for U2B". Additional experiments have identified a single leucine residue in U1A(Leu-44) that is critical for the intrinsic specificity of this protein for the loop sequence of U1 hpll in preference to that of U2hpIV. Our data suggest that most of the difference in RNA-binding specificity between U1A and U2B" can be accounted for by this leucine residue and by the contribution of the ancillary protein U2A' to the specificity of U2B".     

Motivational interviewing to prevent alcohol abuse after traumatic brain injury: A case series.

Objective: Our goal was to test motivational interviewing as a means of preventing return to alcohol abuse after traumatic brain injury. Participants: Twelve of 15 inpatients (80%) who screened positive for alcoholism were approached about the study. Historical controls were 20 similar but untreated patients with follow-up data. Results: One-year outcome data were obtained on 9 participants (75%). Seventy-six percent were male and an average of 35 years old. Eighty-nine percent of participants and 55% of controls reported drinking no alcohol during a typical week at 1 year after discharge. Conclusion: Motivational interviewing is feasible during inpatient rehabilitation and may reduce drinking after traumatic brain injury. Controlled studies are needed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nucleic acid aptamers as tools and drugs: recent developments

Nucleic acid aptamers are molecules that bind to their ligands with high affinity and specificity. Unlike other functional nucleic acids such as antisense oligonucleotides, ribozymes, or siRNAs, aptamers almost never exert their effects on the genetic level. They manipulate their target molecules such as gene products or epitopes directly and site specifically, leaving nontargeted protein functions intact. In a similar way to antibodies, aptamers bind to many different kinds of target molecules with high specificity and can be made to order, but as a result of their different biochemical nature and size they can also be used complementary to antibodies. In some cases, aptamers might be more suitable or more specific than antibody approaches or small molecules, both as scientific and biotechnological tools and as therapeutic agents. Recent examples of characterization of aptamers as tools for scientific research to study regulatory circuits, as tools in diagnostic or biosensor development, and as therapeutic agents are discussed.