Shock Processing of Amino Acids Leading to Complex Structures-Implications to the Origin of Life.

The building blocks of life, amino acids, are believed to have been synthesized in the extreme conditions that prevail in space, starting from simple molecules containing hydrogen, carbon, oxygen and nitrogen. However, the fate and role of amino acids when they are subjected to similar processes largely remain unexplored. Here we report, for the first time, that shock processed amino acids tend to form complex agglomerate structures. Such structures are formed on timescales of about 2 ms due to impact induced shock heating and subsequent cooling. This discovery suggests that the building blocks of life could have self-assembled not just on Earth but on other planetary bodies as a result of impact events. Our study also provides further experimental evidence for the 'threads' observed in meteorites being due to assemblages of (bio)molecules arising from impact-induced shocks.

Did a Complex Carbon Cycle Operate in the Inner Solar System?

Solids in the interstellar medium consist of an intimate mixture of silicate and carbonaceous grains. Because 99% of silicates in meteorites were reprocessed at high temperatures in the inner regions of the Solar Nebula, we propose that similar levels of heating of carbonaceous materials in the oxygen-rich Solar Nebula would have converted nearly all carbon in dust and grain coatings to CO. We discuss catalytic experiments on a variety of grain surfaces that not only produce gas phase species such as CH4, C2H6, C6H6, C6H5OH, or CH3CN, but also produce carbonaceous solids and fibers that would be much more readily incorporated into growing planetesimals. CH4 and other more volatile products of these surface-mediated reactions were likely transported outwards along with chondrule fragments and small Calcium Aluminum-rich Inclusions (CAIs) to enhance the organic content in the outer regions of the nebula where comets formed. Carbonaceous fibers formed on the surfaces of refractory oxides may have significantly improved the aggregation efficiency of chondrules and CAIs. Carbonaceous fibers incorporated into chondritic parent bodies might have served as the carbon source for the generation of more complex organic species during thermal or hydrous metamorphic processes on the evolving asteroid.

Interobserver agreement in the evaluation of B-lines using bedside ultrasound.

PURPOSE: We evaluated agreement among trained emergency physicians assessing the degree of B-line presence on bedside ultrasound in patients presenting to the emergency department (ED) with acute undifferentiated dyspnea. We also determined which thoracic zones offered the highest level of interobserver reliability for sonographic B-line assessment. MATERIALS AND METHODS: We evaluated a prospective convenience sample of adult patients presenting with dyspnea to an academic ED. Two consecutive bedside lung ultrasounds were performed on 91 patients by a pair of physician-sonographers. The lung ultrasounds were structured 10-zone thoracic sonograms, documented as videos. Sonographer pairs were expert/expert (>100 lung ultrasounds performed) or expert/novice pairs (novices performed 5 supervised examinations after structured training) and blinded to clinical data. Sonographers reported B-line concentration with 3 assessment methods: (1) normal (<3 B-lines) or abnormal (≥3 B-lines); (2) ordinal (normal, mild, moderate, or severe), and (3) counting B-lines (0-10; >10) in each zone. All statistical analyses were performed using SPSS version 18.0 (Chicago, IL) and Stata 12.1 (College Station, TX). We evaluated interrater and intrarater agreement using Intraclass correlation coefficients (ICCs). RESULTS: The right and left anterior/superior lung zones showed substantial agreement in all assessment methods and demonstrated best overall agreement (ICC for right: counting, ordinal, and normal/abnormal, 0.811 [0.714-0.875], 0.875 [0.810-0.917], and 0.729 [0.590-0.821], respectively). Furthermore, both expert/expert pairs and expert/novice pairs showed substantial agreement in the right and left anterior/superior thoracic zones (expert/expert, 0.904 and 0.777, respectively; expert/novice, 0.862, and 0.834, respectively). Second best agreement was found for the lateral/superior lung zones (right: counting, ordinal, and normal/abnormal, 0.744 [0.612-0.831], 0.686 [0.524-0.792], and 0.639 [0.453-0.761], respectively; and ICC left: counting, ordinal, and normal/abnormal, 0.671 [0.501-0.782], 0.615 [0.417-0.746], and 0.720 [0.577-0.815], respectively). When comparing agreement to distinguish "normal vs abnormal" B-line findings, our results showed significant agreement in all zones with the exception of the right and left inferior/lateral lung fields and left posterior lung. Reinterpretation by 2 experts of all their own randomized video clips at a later date showed agreement of 0.697 (n=733 zones) and 0.647 (n=266) zones for ordinal assessment of B-line concentration. CONCLUSION: Interrater agreement was best in the anterior/superior thoracic zones followed by the lateral/superior zones for both expert/expert and expert/novice pairs. Agreement in the lateral/inferior lung zones was overall inferior. Intrarater agreement was highest at extreme high or low numbers of B-lines.

Sleep disturbance after mild traumatic brain injury: indicator of injury?

Mild traumatic brain injury (mTBI) is a complex entity with no known objective diagnostic markers. To test the hypothesis that sleep disturbances in the acute mTBI period can serve as an indicator of brain injury, the authors compared sleep polysomnograms (PSG) and sleep EEG power spectra (PS) data in seven mTBI subjects with seven age- and race-matched healthy-control subjects. The two groups differed significantly on PS measures, suggesting that mTBI can result in a disruption of sleep microarchitecture and, in theory, could be of use as a marker for brain injury. These pilot findings need to be replicated on larger samples.

Dermatology's malpractice experience: clinical settings for risk management.

BACKGROUND: Dermatologists need objective information that will help them make rational risk management decisions. OBJECTIVE: We asked, "What can be learned from the limited sources available regarding the clinical situations associated with malpractice litigation against dermatologists?" METHODS: We searched 2 legal databases, one jury verdict and settlement reporter, and reviewed and analyzed a major report from an association of physician insurers. RESULTS: A wide variety of clinical circumstances give rise to malpractice claims. Melanoma is still associated with high risk, and common conditions are associated with relative claim frequency. The clinical details currently available do not encourage optimal responses to reports of malpractice cases. CONCLUSION: Information that clinicians can use in their own risk management efforts can be derived from available sources, but more reliable objective data is needed.

The catalytic potential of cosmic dust: implications for prebiotic chemistry in the solar nebula and other protoplanetary systems.

The synthesis of important prebiotic molecules is fundamentally reliant on basic starting ingredients: water, organic species [e.g., methane (CH(4))], and reduced nitrogen compounds [e.g., ammonia (NH(3)), methyl cyanide (CH(3)CN) etc.]. However, modern studies conclude that the primordial Earth's atmosphere was too rich in CO, CO(2), and water to permit efficient synthesis of such reduced molecules as envisioned by the classic Miller-Urey experiment. Other proposed sources of terrestrial nitrogen reduction, like those within submarine vent systems, also seem to be inadequate sources of chemically reduced C-H-O-N compounds. Here, we demonstrate that nebular dust analogs have impressive catalytic properties for synthesizing prebiotic molecules. Using a catalyst analogous to nebular iron silicate condensate, at temperatures ranging from 500K to 900K, we catalyzed both the Fischer-Tropsch conversion of CO and H(2) to methane and water, and the corresponding Haber-Bosch synthesis of ammonia from N(2) and H(2). Remarkably, when CO, N(2), and H(2) were allowed to react simultaneously, these syntheses also yielded nitrogen-containing organics such as methyl amine (CH(3)NH(2)), acetonitrile (CH(3)CN), and N-methyl methylene imine (H(3)CNCH(2)). A fundamental consequence of this work for astrobiology is the potential for a natural chemical pathway to produce complex chemical building blocks of life throughout our own Solar System and beyond.