Chloride Migration Variability in Reinforced Concrete Highway Structures in Pennsylvania

To assess the potential design life for reinforced concrete highway infrastructure in the Northeastern United States, the resistance to corrosion must be known. Reinforced concrete structures in both cold and marine environments are exposed to chloride, an ion with the potential to migrate through concrete and corrode steel. Chloride content can be assessed relative to the chloride migration coefficient determined at an age of 28-days using methods defined in NT Build 492. This approach is a departure from traditional rapid chloride permeability testing methods used for qualification of concrete mix designs by state departments of transportation. To investigate the impact of these methods, a comprehensive experimental study of PennDOT qualified mixes was conducted. Each mix was procured from ongoing construction efforts in the state and subject to both NT Build 492 and ASTM C1202 (Rapid Chloride Permeability Test). The results show that chloride migration coefficient varies considerably throughout the state, from 0.545 x 10-12 m2/sec to 17.24 x 10-12 m2/sec. The variation is in line with the results from Rapid Chloride Permeability Tests (RCPT) conducted on the same mixes. Results for NT Build 492 also correlated strongly with results for the RCPT, despite high coefficients of variability for both tests. Chloride migration was also found to be related to the coarse aggregate used in the mix design as well as the coarse aggregate’s absorption. Due to Pennsylvania’s diverse geologic make-up, 9 different types of coarse aggregate were used in the 20 mix designs tested. Mixes using Diabase and Dolomite as coarse aggregates were the most resistive to chloride migration, while mixes containing Gravel and Limestone experienced poor resistivity to chloride ingress. Coarse aggregate was sourced from 12 different counties in the mix designs tested. Results for NT Build 492 and the RCPT varied considerably in 5 of the counties

Improvements on the Inhaler

Background: Inhalers are a commonplace in American health care and deliver crucial drugs to patients with COPD and asthma. Inhaler use has been shown to be unsatisfactory among patients resulting in ineffective medication delivery. The goal of this project was to improve the inhaler design for increased effectiveness and ease of use. Methods: Our team first interviewed a Pulmonologist regarding patient inhaler use. Dr. Harry Kane demonstrated the proper use of an inhaler as well and described errors in inhaler use are due to patient technique. A variety of inhalers currently available were examined and were compared for ease of use. Results: Interview with attending physician revealed numerous patient errors that impede effectiveness of inhaled medication. Two common mistakes were identified: patients inhaling too rapidly and patients dispensing the medication too late. Inhaling too rapidly decreases the fraction of drug that reaches the lungs, decreasing effectiveness. Dispensing the medication after a patient reaches total lung capacity (TLC) prevents the drug from reaching their lungs, decreasing effectiveness. Conclusions: We conclude that inhalers could be used more effectively by addressing patient education and feedback mechanisms. Possible solutions discuss audible feedback to help coordinate patient breath with optimal dispersal timing. Future work includes prototyping a design and eliciting patient feedback

Unofficial answers to the Uniform certified public accountants examination, May 1948 to November 1950

https://egrove.olemiss.edu/aicpa_exam/1111/thumbnail.jp

Dichotomous development of the gut microbiome in preterm infants.

BackgroundPreterm infants are at risk of developing intestinal dysbiosis with an increased proportion of Gammaproteobacteria. In this study, we sought the clinical determinants of the relative abundance of feces-associated Gammaproteobacteria in very low birth weight (VLBW) infants. Fecal microbiome was characterized at ≤ 2 weeks and during the 3rd and 4th weeks after birth, by 16S rRNA amplicon sequencing. Maternal and infant clinical characteristics were extracted from electronic medical records. Data were analyzed by linear mixed modeling and linear regression.ResultsClinical data and fecal microbiome profiles of 45 VLBW infants (gestational age 27.9 ± 2.2 weeks; birth weight 1126 ± 208 g) were studied. Three stool samples were analyzed for each infant at mean postnatal ages of 9.9 ± 3, 20.7 ± 4.1, and 29.4 ± 4.9 days. The average relative abundance of Gammaproteobacteria was 42.5% (0-90%) at ≤ 2 weeks, 69.7% (29.9-86.9%) in the 3rd, and 75.5% (54.5-86%) in the 4th week (p < 0.001). Hierarchical and K-means clustering identified two distinct subgroups: cluster 1 started with comparatively low abundance that increased with time, whereas cluster 2 began with a greater abundance at ≤ 2 weeks (p < 0.001) that decreased over time. Both groups resembled each other by the 3rd week. Single variants of Klebsiella and Staphylococcus described variance in community structure between clusters and were shared between all infants, suggesting a common, hospital-derived source. Fecal Gammaproteobacteria was positively associated with vaginal delivery and antenatal steroids.ConclusionsWe detected a dichotomy in gut microbiome assembly in preterm infants: some preterm infants started with low relative gammaproteobacterial abundance in stool that increased as a function of postnatal age, whereas others began with and maintained high abundance. Vaginal birth and antenatal steroids were identified as predictors of Gammaproteobacteria abundance in the early (≤ 2 weeks) and later (3rd and 4th weeks) stool samples, respectively. These findings are important in understanding the development of the gut microbiome in premature infants

Alternative Price Indexes for Medical Care: Evidence from the MEPS Survey

Spending on medical care is a large and growing component of GDP. There are wellknown measurement problems that are estimated to overstate inflation and understate real growth for this sector by as much as 1-1/2 percentage points per year. Because of its size, this would translate into an overstatement of inflation for the overall economy of about ¼ percentage point with an equal understatement in real GDP growth. In this paper, we use data from the Medical Expenditure Panel Survey to obtain new, more comprehensive estimates for this bias and to explore a possible adjustment to existing official price indexes. The MEPS data show an upward bias to price growth in this sector of 1 percentage point, which translates into an overstatement of overall inflation of .2 percentage point and an understatement of GDP growth of the same amount. We also find that an adjustment recently used in Bradley et al provides a useful approximation to the indexes advocated by health economists.

Type X Silicon Carbide Presolar Grains: Type Ia Supernova Condensates?

In terms of nucleosynthesis issues alone, we demonstrate that the type X silicon carbide particles have chemical and isotopic compositions resembling those from explosive helium burning in 14N-rich matter. These particles are extracted chemically from meteorites and were once interstellar particles. They have already been identifed by their discoverers as supernova particles on the basis of their isotopic composi-tions, but we argue that they are from supernovae of Type Ia that explode with a cap of helium atop their CO structure. The relative abundances of the isotopes of C and Si and trace N, Mg, and Ca match those in the X particles without need of complicated and arbitrary mixing postulates. Furthermore, both C and Si abundances are enhanced and more abundant than O, which suggests that SiC is in fact the natural condensate of such matter. We also briefly address special issues relevant to the growth of dust within Type Ia interiors during their expansions

Unofficial answers to the uniform certified public accountants examination of the American Institute of Accountants, May 1, 1951 to November 1953

https://egrove.olemiss.edu/aicpa_exam/1152/thumbnail.jp

Choosing a basis that eliminates spurious solutions in k.p theory

A small change of basis in k.p theory yields a Kane-like Hamiltonian for the conduction and valence bands of narrow-gap semiconductors that has no spurious solutions, yet provides an accurate fit to all effective masses. The theory is shown to work in superlattices by direct comparison with first-principles density-functional calculations of the valence subband structure. A reinterpretation of the standard data-fitting procedures used in k.p theory is also proposed.Comment: 15 pages, 2 figures; v3: expanded with much new materia

Improving the Inhaler

Background: Inhalers used to dispense various pharmacological agents play an important role in the care of patients with pulmonary disease. These pharmacological agents can be very effective, however, many patients that use inhalers often deliver these drugs incorrectly or in a sub-optimal manner. Our project aims to improve the design of the inhaler in order to increase the effectiveness of drug delivery and also ease of patient use. Methods: We interviewed a critical care pulmonologist regarding patient inhaler use and compliance. This physician offered information about proper inhaler use and described common errors that patients encounter when attempting to dispense drugs via inhalers. Both steroidal and albuterol inhalers that are currently being prescribed were allocated for our examination and use to help develop a more user friendly model. Results: The pulmonologist illustrated several errors that patients will commonly make which can degrade the efficacy of the inhaled drug delivery. One frequently encountered error was that drug is dispensed by the patient once they had already reached their total lung capacity, or inhaled fully. This sort of error leads to the drug being dispensed into the throat and failure to reach the intended target, the lungs. Additionally, the physician noted that patients often forget to administer their inhaled drugs because the inhaler does not fit comfortably into the patient’s pocket and so it is not optimally portable. Conclusion: Our research suggests that inhaler design could be improved in order to increase the effectiveness of drug delivery and patient compliance. We are considering incorporating audible actuation clues that will alert the patient when to dispense the drug, and also provide electronic feedback to the patient’s mobile device. This would help educate the patient on how to coordinate their breathing with actuation of the device to dispense the medication

Dirac semimetal in three dimensions

In a Dirac semimetal, the conduction and valence bands contact only at discrete (Dirac) points in the Brillouin zone (BZ) and disperse linearly in all directions around these critical points. Including spin, the low energy effective theory around each critical point is a four band Dirac Hamiltonian. In two dimensions (2D), this situation is realized in graphene without spin-orbit coupling. 3D Dirac points are predicted to exist at the phase transition between a topological and a normal insulator in the presence of inversion symmetry. Here we show that 3D Dirac points can also be protected by crystallographic symmetries in particular space-groups and enumerate the criteria necessary to identify these groups. This reveals the possibility of 3D analogs to graphene. We provide a systematic approach for identifying such materials and present ab initio calculations of metastable \beta-cristobalite BiO_2 which exhibits Dirac points at the three symmetry related X points of the BZ.Comment: 6 pages, 4 figure