Determination of far-field stress from localized stress concentrations

The purpose of this work was to develop a method of determining far-field principal stress magnitude and orientation using biaxial stress measurements made in a series of bore holes. Two novel developments were employed: one was a method for relating biaxial measurements from three bore holes to the triaxial principal stress field; the other was a measurement technique that fully defines the biaxial stress field around a bore hole, independent of rock properties. To determine the triaxial principal stress field, a series of simultaneous equations describing biaxial measurements in terms of a random baseline coordinate system was developed. A least squares regression was then utilized to determine the coordinate system\u27s stress field. A Newton-Raphson reduction was subsequently performed to define the orientation and magnitude of the principal stress field. The biaxial stress measurement technique employs two loading mechanisms and ultrasonic crack detection. The biaxial stress field in bore holes with nonhomogeneous and anisotropic rock conditions can be defined. Finally, recommendations are given for the development of a testing apparatus utilizing thin-film piezoelectric substrates to detect ultrasonic shear waves capable of underground biaxial measurements

Resource Allocation for Outdoor-to-Indoor Multicarrier Transmission with Shared UE-side Distributed Antenna Systems

In this paper, we study the resource allocation algorithm design for downlink multicarrier transmission with a shared user equipment (UE)-side distributed antenna system (SUDAS) which utilizes both licensed and unlicensed frequency bands for improving the system throughput. The joint UE selection and transceiver processing matrix design is formulated as a non-convex optimization problem for the maximization of the end-to-end system throughput (bits/s). In order to obtain a tractable resource allocation algorithm, we first show that the optimal transmitter precoding and receiver post-processing matrices jointly diagonalize the end-to-end communication channel. Subsequently, the optimization problem is converted to a scalar optimization problem for multiple parallel channels, which is solved by using an asymptotically optimal iterative algorithm. Simulation results illustrate that the proposed resource allocation algorithm for the SUDAS achieves an excellent system performance and provides a spatial multiplexing gain for single-antenna UEs.Comment: accepted for publication at the IEEE Vehicular Technology Conference (VTC) Spring, Glasgow, Scotland, UK, May 201

Analysis of Competing Data Structures: Does Ontological Clarity Produce Better End-User Query Performance?

End users respond to the information requests of stakeholders by using SQL-based query tools to retrieve information from their organizations’ data stores. The structure of these data stores impacts end users’ performance (e.g., the accuracy of their queries). Traditionally, logical data models with optional properties (referred to hereafter as more-traditional models) are used. Ontologically clearer conceptual models, however, have been shown to facilitate better under- standing of real-world application domains. The question now arises as to whether ontologically clearer (i.e., more precise) implementation representations also improve end-user query performance. This paper reports the results of an experiment that investigates the effect on query performance of more-traditional logical models compared to ontologically clearer logical models. End users of the ontologically clearer implementation made fewer semantic errors and were more confident in the accuracy of their queries. No statistical difference in time was observed between users of the two types of logical models

Rational Bias In Inflation Expectations

Thesis advisor: Robert MurphyWe empirically examine the Biased Expectations Hypothesis, which states that recent price movements in certain sectors play special roles in the formation of in- dividuals inflation expectations. Specifically we analyze whether economists rationally bias their expectations and whether economists and consumers naively bias their ex- pectations with respect to recent inflation in the food and energy sectors. We develop theoretical models for both rationally formed and naively formed inflation expecta- tions. We find that economists do not bias their rationally formed expectations and that consumers and economists do not naively form inflation expectations. Our results do not support the Biased Expectations Hypothesis; rather, they reinforce the use of core measures of inflation in policy making.Thesis (BA) — Boston College, 2013.Submitted to: Boston College. College of Arts and Sciences.Discipline: Economics Honors Program.Discipline: Economics

(Per)chlorate-reducing bacteria can utilize aerobic and anaerobic pathways of aromatic degradation with (per)chlorate as an electron acceptor.

UnlabelledThe pathways involved in aromatic compound oxidation under perchlorate and chlorate [collectively known as (per)chlorate]-reducing conditions are poorly understood. Previous studies suggest that these are oxygenase-dependent pathways involving O2 biogenically produced during (per)chlorate respiration. Recently, we described Sedimenticola selenatireducens CUZ and Dechloromarinus chlorophilus NSS, which oxidized phenylacetate and benzoate, two key intermediates in aromatic compound catabolism, coupled to the reduction of perchlorate or chlorate, respectively, and nitrate. While strain CUZ also oxidized benzoate and phenylacetate with oxygen as an electron acceptor, strain NSS oxidized only the latter, even at a very low oxygen concentration (1%, vol/vol). Strains CUZ and NSS contain similar genes for both the anaerobic and aerobic-hybrid pathways of benzoate and phenylacetate degradation; however, the key genes (paaABCD) encoding the epoxidase of the aerobic-hybrid phenylacetate pathway were not found in either genome. By using transcriptomics and proteomics, as well as by monitoring metabolic intermediates, we investigated the utilization of the anaerobic and aerobic-hybrid pathways on different electron acceptors. For strain CUZ, the results indicated utilization of the anaerobic pathways with perchlorate and nitrate as electron acceptors and of the aerobic-hybrid pathways in the presence of oxygen. In contrast, proteomic results suggest that strain NSS may use a combination of the anaerobic and aerobic-hybrid pathways when growing on phenylacetate with chlorate. Though microbial (per)chlorate reduction produces molecular oxygen through the dismutation of chlorite (ClO2(-)), this study demonstrates that anaerobic pathways for the degradation of aromatics can still be utilized by these novel organisms.ImportanceS. selenatireducens CUZ and D. chlorophilus NSS are (per)chlorate- and chlorate-reducing bacteria, respectively, whose genomes encode both anaerobic and aerobic-hybrid pathways for the degradation of phenylacetate and benzoate. Previous studies have shown that (per)chlorate-reducing bacteria and chlorate-reducing bacteria (CRB) can use aerobic pathways to oxidize aromatic compounds in otherwise anoxic environments by capturing the oxygen produced from chlorite dismutation. In contrast, we demonstrate that S. selenatireducens CUZ is the first perchlorate reducer known to utilize anaerobic aromatic degradation pathways with perchlorate as an electron acceptor and that it does so in preference over the aerobic-hybrid pathways, regardless of any oxygen produced from chlorite dismutation. D. chlorophilus NSS, on the other hand, may be carrying out anaerobic and aerobic-hybrid processes simultaneously. Concurrent use of anaerobic and aerobic pathways has not been previously reported for other CRB or any microorganisms that encode similar pathways of phenylacetate or benzoate degradation and may be advantageous in low-oxygen environments

Single cell analysis applied to antibody fragment production with Bacillus megaterium: development of advanced physiology and bioprocess state estimation tools

<p>Abstract</p> <p>Background</p> <p>Single cell analysis for bioprocess monitoring is an important tool to gain deeper insights into particular cell behavior and population dynamics of production processes and can be very useful for discrimination of the real bottleneck between product biosynthesis and secretion, respectively.</p> <p>Results</p> <p>Here different dyes for viability estimation considering membrane potential (DiOC₂(3), DiBAC₄(3), DiOC₆(3)) and cell integrity (DiBAC₄(3)/PI, Syto9/PI) were successfully evaluated for <it>Bacillus megaterium </it>cell characterization. It was possible to establish an appropriate assay to measure the production intensities of single cells revealing certain product secretion dynamics. Methods were tested regarding their sensitivity by evaluating fluorescence surface density and fluorescent specific concentration in relation to the electronic cell volume. The assays established were applied at different stages of a bioprocess where the antibody fragment D1.3 scFv production and secretion by <it>B. megaterium </it>was studied.</p> <p>Conclusions</p> <p>It was possible to distinguish between live, metabolic active, depolarized, dormant, and dead cells and to discriminate between high and low productive cells. The methods were shown to be suitable tools for process monitoring at single cell level allowing a better process understanding, increasing robustness and forming a firm basis for physiology-based analysis and optimization with the general application for bioprocess development.</p

EVALUATION OF AN EXISTING STEEL POST ALTERNATIVE FOR THE THRIE BEAM BULLNOSE GUARDRAIL SYSTEM

Recently, the Minnesota Department of Transportation (MnDOT) funded a research project through the Midwest States Regional Pooled Fund to evaluate an existing steel post alternative for the thrie beam bullnose barrier system previously developed at the Midwest Roadside Safety Facility (MwRSF). MnDOT had an interest in the replacement of the wooden breakaway posts used in the current bullnose system with proprietary breakaway steel posts. The research project consisted of evaluation of current breakaway steel post designs, investigation and selection of a candidate post design, and full-scale testing of the bullnose system with a steel post alternative. The full-scale testing was to consist of two tests conducted according to the evaluation criteria of NCHRP Report 350: 1) Test 3-38, an impact of a 2000P vehicle on the Critical Impact Point (CIP) of the system at a speed of 100 km/h and an angle of 20 degrees, and 2) Test 3-31, an impact of a 2000P vehicle with the center of the vehicle aligned with the center of the nose of the system at a speed of 100 km/h and an angle of 0 degrees. The evaluation of the steel post alternative for the bullnose system project has been completed. A steel post alternative was selected followed by two full-scale crash tests. Unfortunately, both crash tests failed as the vehicle in each test ramped up the guardrail and vaulted the system. This letter summarizes the work completed

Assessing recent warming using instrumentally homogeneous sea surface temperature records

Sea surface temperature (SST) records are subject to potential biases due to changing instrumentation and measurement practices. Significant differences exist between commonly used composite SST reconstructions from the National Oceanic and Atmospheric Administration’s Extended Reconstruction Sea Surface Temperature (ERSST), the Hadley Centre SST data set (HadSST3), and the Japanese Meteorological Agency’s Centennial Observation-Based Estimates of SSTs (COBE-SST) from 2003 to the present. The update from ERSST version 3b to version 4 resulted in an increase in the operational SST trend estimate during the last 19 years from 0.07° to 0.12°C per decade, indicating a higher rate of warming in recent years. We show that ERSST version 4 trends generally agree with largely independent, near-global, and instrumentally homogeneous SST measurements from floating buoys, Argo floats, and radiometer-based satellite measurements that have been developed and deployed during the past two decades. We find a large cooling bias in ERSST version 3b and smaller but significant cooling biases in HadSST3 and COBE-SST from 2003 to the present, with respect to most series examined. These results suggest that reported rates of SST warming in recent years have been underestimated in these three data sets

Evaluating biases in sea surface temperature records using coastal weather stations

Sea surface temperatures form a vital part of global mean surface temperature records. Historical observation methods have changed substantially over time from buckets to engine room intake sensors, hull sensors and drifting buoys, rendering their use for climatological studies problematic. There are substantial uncertainties in the relative biases of different observations which may impact the global temperature record. Island and coastal weather stations can be compared to coastal sea surface temperature observations to obtain an assessment of changes in bias over time. The process is made more challenging by differences in the rate of warming between air temperatures and sea surface temperatures, and differences across coastal boundaries. A preliminary sea surface temperature reconstruction homogenized using coastal weather station data suggests significant changes to the sea surface temperature record, although there are substantial uncertainties of which only some can be quantified. A large warm excursion in versions 4 and 5 of the NOAA Extended Reconstructed Sea Surface Temperature during World War 2 is rejected, as is a cool excursion around 1910 present in all existing records. The mid-century plateau is cooler than in existing reconstructions