A Narrative Approach to Understanding Career Attrition for Women Engineers

More women exit the engineering profession than enter, leaving a talent void that incurs lost business value from unrealized business revenues. Without new insights about how to address the continued attrition of women engineers, the profession is unlikely to sustain the human capital needed to achieve competitive advantages through innovation, increased productivity, and improved firm reputation. This qualitative narrative inquiry explored the career attrition phenomenon of six former women engineers in the Northern Tier States region of the United States who left engineering within the past 4 years and were either an engineer-in-training or professional engineer. The conceptual framework for this study was based on Bourdieu\u27s concepts of habitus, capital, and field to discover a more nuanced meaning about women engineers\u27 career exit experiences. The research questions focused on understanding the experiences of six former women engineers as told through their narrative stories of consideration for leaving and a final decision to leave the profession. Data were collected in semi-structured interviews; the resulting transcripts were hand coded using initial and pattern coding to ascribe meaning to story segments grouped in cohered themes. Results suggest that women engineers become disillusioned and leave their careers as resilience is surpassed by uncertainty about sustaining professional and life aspirations in response to incongruent hegemonic-male work cultures. These findings can enable engineering stakeholders to develop ways to retain more women. Positive social change could be realized by improving the lives of women engineers and their communities while enhancing the profession\u27s ability to deliver innovative and creative solutions to the most vexing problems facing humanity

A Narrative Approach to Understanding Career Attrition for Women Engineers

More women exit the engineering profession than enter, leaving a talent void that incurs lost business value from unrealized business revenues. Without new insights about how to address the continued attrition of women engineers, the profession is unlikely to sustain the human capital needed to achieve competitive advantages through innovation, increased productivity, and improved firm reputation. This qualitative narrative inquiry explored the career attrition phenomenon of six former women engineers in the Northern Tier States region of the United States who left engineering within the past 4 years and were either an engineer-in-training or professional engineer. The conceptual framework for this study was based on Bourdieu’s concepts of habitus, capital, and field to discover a more nuanced meaning about women engineers’ career exit experiences. The research questions focused on understanding the experiences of six former women engineers as told through their narrative stories of consideration for leaving and a final decision to leave the profession. Data were collected in semi-structured interviews; the resulting transcripts were hand coded using initial and pattern coding to ascribe meaning to story segments grouped in cohered themes. Results suggest that women engineers become disillusioned and leave their careers as resilience is surpassed by uncertainty about sustaining professional and life aspirations in response to incongruent hegemonic-male work cultures. These findings can enable engineering stakeholders to develop ways to retain more women. Positive social change could be realized by improving the lives of women engineers and their communities while enhancing the profession’s ability to deliver innovative and creative solutions to the most vexing problems facing humanity

Synthesis and characterization of vinyl ester based room temperature ionic liquid gels for membrane applications

Fuel cells have the potential for improved efficiency at elevated temperatures, but are restricted to operating at temperatures below 100°C due to the limitations of the proton exchange membrane (PEM). The PEM in fuel cells acts both as a medium for proton conduction and as a barrier between the fuels, requiring high ionic conductivities and mechanical strength. Work has been ongoing to maintain both mechanical integrity and conductivity of PEMs at higher temperatures, through numerous means, including the incorporation of room temperature ionic liquids (RTIL). RTILs offer the unique advantage of having negligible volatility, which potentially allows them to maintain ionic conductivity at high temperatures.A cross-linked polymer network was formed in an RTIL medium. The difunctional monomer, Vinyl Ester of Diglycidyl Ether of Bisphenol A (VE-DGEBA) was reacted with the monofunctional monomer 2-Acrylamido-2-Methyl-1- ropanesulfonic Acid (AMPS) in the presence of an RTIL, 1-Ethyl-3-Methylimidazolium Ethyl Sulfate [EMIM][EtSO4]. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy was used to show the complete conversion of carbon-carbon double bonds in ~13 hours. Dynamic Mechanical Analysis (DMA) frequency sweeps showed the presence of multiple micro-scale phases, which was confirmed through Scanning Electron Microscopy. DMA temperature sweeps showed glass transition temperatures (Tg) ranging from -80°C to 5°C, with second Tgs ranging from -54°C to 64°C. Quasistatic compressive testing showed compressive moduli ranging from 2 MPa to 1127 MPa. Electrochemical impedence spectroscopy showed through-plane ionic conductivities for dry gels ranging from 4.38·10-11 S/cm to 1.54·10-3 S/cm for samples with on exchange capacities (IEC) ranging from 1 mol/L to 5 mol/L. Thermogravimetric analysis showed good thermal stability, with decomposition temperatures at 5% weight loss ranging from 208°C to 274°C, and environmental testing showed irreversible loss of RTIL and property changes when samples were submersed in deionized water.Effort was made to improve the properties of the ILG by preparation of a semiinterpenetrating network (sIPN). This was produced by forming the ILG around Poly-(2- Acrylamido-2-Methyl-1-Propanesulfonic Acid). It was found that this sample showed similar properties to the other ILGs, with a primary Tg of -28.2°C and a second Tg at 17.44°C. The compressive modulus of this sample was found to be 85.89 MPa, the ionic conductivity was 1.41·10-5 S/cm for an IEC of 2.74 mol/L, and the thermal decomposition temperature was found to be 215.2°C. The notable improvement over samples lacking Poly-AMPS was a decrease in brittleness.M.S., Chemical Engineering -- Drexel University, 201

Thermal Signature Identification System (TheSIS)

We characterize both nonlinear and high order linear responses of fiber-optic and optoelectronic components using spread spectrum temperature cycling methods. This Thermal Signature Identification System (TheSIS) provides much more detail than conventional narrowband or quasi-static temperature profiling methods. This detail allows us to match components more thoroughly, detect subtle reversible shifts in performance, and investigate the cause of instabilities or irreversible changes. In particular, we create parameterized models of athermal fiber Bragg gratings (FBGs), delay line interferometers (DLIs), and distributed feedback (DFB) lasers, then subject the alternative models to selection via the Akaike Information Criterion (AIC). Detailed pairing of components, e.g. FBGs, is accomplished by means of weighted distance metrics or norms, rather than on the basis of a single parameter, such as center wavelength

IPC2008-64049 NUMERICAL SIMULATION OF DYNAMIC DUCTILE FRACTURE PROPAGATION USING COHESIVE ZONE MODELING

ABSTRACT This paper presents the development of a dynamic ductile crack growth model to simulate an axially running crack in a pipe by finite element analyses. The model was developed using the finite element (FE) program ABAQUS/Explicit. To simulate the ductile crack propagation, a cohesive zone model was employed. Moreover, the interaction between the gas decompression and the structural deformation was simulated by using an approximate three-dimensional pressure decay relationship from experimental results. The dynamic ductile crack growth model was employed to simulate 152.4 mm (6-inch) diameter pipe tests, where the measured fracture speed was used to calibrate the cohesive model parameters. From the simulation, the CTOA values were calculated during the dynamic ductile crack propagation. In order to validate the calculated CTOA value, drop-weight tear test (DWTT) experiments were conducted for the pipe material, where the CTOA was measured with high-speed video during the impact test. The calculated and measured CTOA values showed reasonable agreement. Finally, the developed model was employed to investigate the effect of pipe diameter on fracture speed for small-diameter pipes

Identification of developmental stage and anatomical fraction contributions to cell wall recalcitrance in switchgrass

Background Heterogeneity within herbaceous biomass can present important challenges for processing feedstocks to cellulosic biofuels. Alterations to cell wall composition and organization during plant growth represent major contributions to heterogeneity within a single species or cultivar. To address this challenge, the focus of this study was to characterize the relationship between composition and properties of the plant cell wall and cell wall response to deconstruction by NaOH pretreatment and enzymatic hydrolysis for anatomical fractions (stem internodes, leaf sheaths, and leaf blades) within switchgrass at various tissue maturities as assessed by differing internode. Results Substantial differences in both cell wall composition and response to deconstruction were observed as a function of anatomical fraction and tissue maturity. Notably, lignin content increased with tissue maturity concurrently with decreasing ferulate content across all three anatomical fractions. Stem internodes exhibited the highest lignin content as well as the lowest hydrolysis yields, which were inversely correlated to lignin content. Confocal microscopy was used to demonstrate that removal of cell wall aromatics (i.e., lignins and hydroxycinnamates) by NaOH pretreatment was non-uniform across diverse cell types. Non-cellulosic polysaccharides were linked to differences in cell wall response to deconstruction in lower lignin fractions. Specifically, leaf sheath and leaf blade were found to have higher contents of substituted glucuronoarabinoxylans and pectic polysaccharides. Glycome profiling demonstrated that xylan and pectic polysaccharide extractability varied with stem internode maturity, with more mature internodes requiring harsher chemical extractions to remove comparable glycan abundances relative to less mature internodes. While enzymatic hydrolysis was performed on extractives-free biomass, extractible sugars (i.e., starch and sucrose) comprised a significant portion of total dry weight particularly in stem internodes, and may provide an opportunity for recovery during processing

Multi-scale environmental filters and niche partitioning govern the distributions of riparian vegetation guilds

Across landscapes, riparian plant communities assemble under varying levels of disturbance, environmental stress, and resource availability, leading to the development of distinct riparian life-history guilds over evolutionary timescales. Identifying the environmental filters that exert selective pressures on specific riparian vegetation guilds is a critical step in setting baseline expectations for how riparian vegetation may respond to environmental conditions anticipated under future global change scenarios. In this study, we ask: (1) What riparian plant guilds exist across the interior Columbia and upper Missouri River basins? (2) What environmental filters shape riparian guild distributions? (3) How does resource partitioning among guilds influence guild distributions and co-occurrence? Woody species composition was measured at 703 stream reaches and each species\u27 morphological and functional attributes were extracted from a database in four categories: (1) life form, (2) persistence and growth, (3) reproduction, and (4) resource use. We clustered species into guilds by morphological characteristics and attributes related to environmental tolerances, modeling these guilds\u27 distributions as a function of environmental filters-regional climate, watershed hydrogeomorphic characteristics, and stream channel form- and guild coexistence. We identified five guilds: (1) a tall, deeply rooted, long-lived, evergreen tree guild, (2) a xeric, disturbance tolerant shrub guild, (3) a hydrophytic, thicket-forming shrub guild, (4) a low-statured, shadetolerant, understory shrub guild, and (5) a flood tolerant, mesoriparian shrub guild. Guilds were most strongly discriminated by species\u27 rooting depth, canopy height and potential to resprout and grow following biomass-removing disturbance (e.g., flooding, fire). Hydro-climatic variables, including precipitation, watershed area, water table depth, and channel form attributes reflective of hydrologic regime, were predictors of guilds whose life history strategies had affinity or aversion to flooding, drought, and fluvial disturbance. Biotic interactions excluded guilds with divergent life history strategies and/or allowed for the co-occurrence of guilds that partition resources differently in the same environment. We conclude that the riparian guild framework provides insight into how disturbance and bioclimatic gradients shape riparian functional plant diversity across heterogeneous landscapes. Multiple environmental filters should be considered when the riparian response guild framework is to be used as a decisionsupport tool framework across large spatial extents. Copyright: © 2015 Hough-Snee et al

Gas phase characterization of the noncovalent quaternary structure of Cholera toxin and the Cholera toxin B subunit pentamer

Cholera toxin (CTx) is an AB5 cytotonic protein that has medical relevance in cholera and as a novel mucosal adjuvant. Here, we report an analysis of the noncovalent homopentameric complex of CTx B chain (CTx B5) using electrospray ionization triple quadrupole mass spectrometry and tandem mass spectrometry and the analysis of the noncovalent hexameric holotoxin usingelectrospray ionization time-of-flight mass spectrometry over a range of pH values that correlate with those encountered by this toxin after cellular uptake. We show that noncovalent interactions within the toxin assemblies were maintained under both acidic and neutral conditions in the gas phase. However, unlike the related Escherichia coli Shiga-like toxin B5 pentamer (SLTx B), the CTx B5 pentamer was stable at low pH, indicating that additional interactions must be present within the latter. Structural comparison of the CTx B monomer interface reveals an additional α-helix that is absent in the SLTx B monomer. In silico energy calculations support interactions between this helix and the adjacent monomer. These data provide insight into the apparent stabilization of CTx B relative to SLTx B

Radio transients from stellar tidal disruption by massive black holes

The tidal disruption of a star by a supermassive black hole provides us with a rare glimpse of these otherwise dormant beasts. It has long been predicted that the disruption will be accompanied by a thermal `flare', powered by the accretion of bound stellar debris. Several candidate disruptions have been discovered in this manner at optical, UV and X-ray wavelengths. Here we explore the observational consequences if a modest fraction of the accretion power is channeled into an ultra-relativistic outflow. We show that a relativistic jet decelerates due to its interaction with the interstellar medium at sub-parsec distances from the black hole. Synchrotron radiation from electrons accelerated by the reverse shock powers a bright radio-infrared transient that peaks on a timescale ~1 yr after disruption. Emission from the forward shock may be detectable for several years after the peak. Deep radio follow-up observations of tidal disruption candidates at late times can test for the presence of relativistic ejecta. Upcoming radio transient surveys may independently discover tens to hundreds of tidal disruptions per year, complimenting searches at other wavelengths. Non-thermal emission from tidal disruption probes the physics of jet formation under relatively clean conditions, in which the flow parameters are independently constrained.Comment: 5 pages, 2 figures, submitted to MNRAS Letter