October 1st, 2014 by MVH
Mittag, D. M. (2014). A Meno Problem for Evidentialism. Southern Journal of Philosophy, 52(2), 250-266.
Abstract: The original Meno problem is to explain why knowledge is more valuable than mere true belief. In this paper I argue that evidentialists face an additional Meno problem, a Meno problem that, to date, no evidentialist has considered. Specifically, evidentialists must account for the additional epistemic value of a doxastically justified doxastic attitude as compared to a doxastic attitude that is merely propositionally justified. I consider the nature of the problem facing evidentialism and critically discuss two attempts to account for this additional epistemic value. Then, I highlight the remaining options and present the alternative I favor. According to this alternative, while the nature of doxastic justification is analyzed in terms of propositional justification, the value of doxastic justification is not. Holding a doxastic attitude on the basis of propositionally justifying evidence is a fundamental epistemic good. In virtue of this, doxastically justified doxastic attitudes have fundamental epistemic value.
October 1st, 2014 by MVH
Christensen, N. A. (2014). Facing the Weather in James Galvin’s The Meadow and Cormac McCarthy’s The Road. Isle-Interdisciplinary Studies in Literature and Environment, 21(1), 192-204.
This is an essay about the weather and the power of the imagination. What I have to say is as much for people outside of the academy as it is for those of us within it. In the academy, and even within the circles of environmental literary criticism, it might seem romantic or naïve or old fashioned to suggest that the imaginative potency of literature can change values and behavior. But that is precisely what I believe—that reading literature can alter the way we imagine ourselves and our relationship with the weather. And now, more than ever, we find ourselves in need of it.
August 4th, 2014 by MVH
Majure, L. C., Judd, W. S., Ionta, G. M., Skean, J. D., Becquer, E. R., & Neubig, K. M. (2014). Miconia cineana (Melastomataceae: Miconieae), a New Species from the Massif de la Hotte, Haiti, Based on Morphological and Molecular Evidence. Systematic Botany, 39(3), 906-914.
Abstract: We describe a new species, Miconia cineana (Melastomataceae: Miconieae), from the Massif de la Hotte, Haiti. Although this species has been known from sterile collections since the early 1980s, its phylogenetic position was unknown, although it was presumed to be closely related to species of Pachyanthus s. 1. The phylogenetic reconstruction presented here, based on a recent collection of the species, clearly places M. cineana in a clade comprised of Cuban species of the polyphyletic genera Tetrazygia s. I. and Pachyanthus s. 1. Thus, M. cineana represents the sole Hispaniolan member of an otherwise Cuban clade, and an uncommon biogeographic pattern in melastomes. Miconia cineana, although described here from sterile specimens, is easily distinguished from the other species of this clade using vegetative morphology, as well as phylogenetic placement. This study highlights the utility of molecular data when coupled with morphology, allowing for the discovery of an unrecognized species in a region of high diversity and endemism, i.e. the Massif de la Hotte.
July 23rd, 2014 by MVH
Chase, B., Meiggs, D., Ajithprasad, P., & Slater, P. A. (2014). Pastoral land-use of the Indus Civilization in Gujarat: faunal analyses and biogenic isotopes at Bagasra. Journal of Archaeological Science, 50, 1-15.
Abstract: The Indus Civilization (2600–1900 BC) in Gujarat is characterized by a series of small yet monumentally walled settlements located along trade and travel corridors. The manufacture and use of typically Harappan material culture at these settlements demonstrates that many residents of these sites participated in exchange and interaction networks that linked them to distant Indus cities. Less is known, however, regarding the ways in which the residents of these sites were situated into their local landscapes. Here we combine previously published faunal analyses from the small walled settlement of Bagasra in the Indian state of Gujarat, with a preliminary investigation of intra- and inter-individual variation in the ratios of biogenic isotopes of strontium (87Sr/86Sr), carbon (δ13C), and oxygen (δ18O) in the tooth enamel of domestic animals consumed at the site. 87Sr/86Sr ratios in the teeth of sheep and goats exhibit little intra- or inter-individual variation suggesting that most were raised locally while greater inter-individual variation in the teeth of cattle suggesting that nearly half of these animals were either raised further afield or were supplied with fodder raised elsewhere. δ13C values from these same samples in the teeth of sheep and goats exhibit considerable intra-individual variation suggesting of a seasonally variable diet incorporating significant wild forage while uniformly higher values in the teeth of cattle suggest that they consumed mostly agricultural produce throughout the year. δ18O values in the teeth of both sets of domestic livestock exhibit considerable intra-individual variation commensurate with the seasonal variation in temperature and rainfall characteristic of the region while variation between taxa is consistent with observed dietary differences. Taken together, our findings provide new information regarding the ways in which the domestic animals consumed at Bagasra were raised and obtained while establishing an empirical baseline necessary for further exploration of the land-use changes that may have accompanied the emergence and decline of South Asia’s first urban civilization.
July 23rd, 2014 by MVH
Reimann, D. A. (2013). Symmetric interlace patterns on polyhedra using generalized truchet tiles. Symmetry: Culture and Science, 24(1-4), 185-190.
July 23rd, 2014 by MVH
McCauley, A. (Artist). (2014). “Passage 13″. Drawing. Exhibited at: 5th Annual Exhibition of Contemporary Drawing, University of North Carolina, Asheville, January 17-March 17, 2014.
July 23rd, 2014 by MVH
Pifer, M. J., & Baker, V. L. (2014). “It could be just because I’m different”: Otherness and its outcomes in doctoral education. Journal of Diversity in Higher Education, 7(1), 14-30.
Abstract: For students who view themselves as different from the majority and those in positions of influence, doctoral education may present challenges beyond the typical pressures and stresses of the graduate student experience. In this article, we report findings from a qualitative study of otherness as described by 31 full-time doctoral students in two academic departments within one university. We explore identity-based otherness and its related outcomes for students and the academy. Findings from our analysis of interview data indicate that doctoral students experience otherness across a diverse range of characteristics related to professional, relational, and personal components of their identities. Findings also indicate that experiences of otherness may prevent students from viewing themselves as accepted and supported members of departmental, disciplinary, and professional communities. We conclude with implications for research and practice.
July 21st, 2014 by MVH
Chase, B., Ajithprasad, P., Rajesh, S. V., Patel, A., & Sharma, B. (2014). Materializing Harappan identities: Unity and diversity in the borderlands of the Indus Civilization. Journal of Anthropological Archaeology, 35, 63-78.
Abstract: The widespread distribution of Harappan material culture throughout a vast expanse of northwestern South Asia is a defining characteristic of the Indus Civilization (2600–1900 BC). The social dynamics responsible for this material pattern, however, are not fully understood. While top-down perspectives on interregional interaction explain some aspects of the material record in the Indian state of Gujarat, they do not explain the material diversity that we observe at Indus settlements in Gujarat. Here, we undertake a bottom-up exploration of Harappan material culture at two small, recently excavated Indus settlements in Gujarat. Our findings show that although the residents of both sites participated in the interregional economy and publically displayed a common Harappan identity, there is evidence for considerable variation in the domestic practices characteristic of each site. We interpret these to suggest that the residents of these sites were integrated into the wider Indus Civilization by way of inclusionary ideologies that served to unify socially diverse borderland communities. These findings and interpretations regarding the role of material culture in the mediation of local social dynamics in the Indus borderlands contribute to a more complete understanding of South Asia’s first urban society while offering methodological and theoretical perspectives that further the exploration of these issues in early complex societies more generally.
July 15th, 2014 by MVH
Sakulthaew, C., Comfort, S., Chokejaroenrat, C., Harris, C., & Li, X. (2014). A combined chemical and biological approach to transforming and mineralizing PAHs in runoff water. Chemosphere, 117, 1-9.
Abstract: The water quality of lakes, rivers and streams associated with metropolitan areas is declining from increased inputs of urban runoff that contain polycyclic aromatic hydrocarbons (PAHs). Our objective was to transform and mineralize PAHs in runoff using a combined chemical and biological approach. Using 14C-labeled phenanthrene, 14C-benzo(a)pyrene and a mixture of 16 PAHs, we found that ozone transformed all PAHs in a H2O matrix within minutes but complete mineralization to CO2 took several weeks. When urban runoff water (7.6 mg C L−1) replaced H2O as the background matrix, some delays in degradation rates were observed but transforming a mixture of PAHs was still complete within 10 min. Comparing the biodegradability of the ozonated products to the parent structures in unsaturated soil microcosms showed that the 3-ring phenanthrene was more biodegradable (as evidence by 14CO2 released) than its ozonated products but for the 5-ring benzo(a)pyrene, the products produced by ozone were much more biodegradable (22% vs. 3% mineralized). For phenanthrene, we identified diphenaldehyde as the initial degradation product produced from ozonation. By continuing to pump the ozonated products (14C-labeled diphenaldehyde or ozone-treated benzo(a)pyrene) onto glass beads coated with microorganisms, we verified that biological mineralization could be achieved in a flow-through system and mineralization rates improved with acclimation of the microbial population (i.e., time and exposure to the substrate). These results support a combined ozone and biological approach to treating PAHs in urban runoff water.
July 10th, 2014 by MVH
Linich, C., & Parr, C. (2014). Okro mch’edelo (O Goldsmith). In C. Parr (Ed.): Earthsongs.
Description: This piece is an equal-voiced setting, with the narrow ranges of each part typical of many Georgian folk songs. It can be sung in the written key nicely by middle school-age or older mixed groups, or women’s groups with some older women who are comfortable with the occasional G below middle C in the bani (bass) part. For a TTB setting, transpose down a major third or fourth. It could be transposed up a step or so for use with young children, but singing the piece any higher than that will change the desired traditional folk tone quality of the sound. Any kind of octave doubling, either above or below, is not characteristic of the Georgian folk tradition and is not recommended.
May 15th, 2014 by MVH
Harnish, A. (2014). Extractive workload: a mixed-method approach for investigating the socially differentiated effects of land-use/land-cover changes in a southern Zambian frontier. Population and Environment, 35(4), 455-476.
Abstract: In rural regions across the globe, local natural resources (i.e., “bush” resources) are central to meeting daily household needs. Culturally-influenced gender- and age-based divisions of labor guide the harvesting of these resources and, as a result, shifts in resource availability will differentially affect women, men, girls, and boys. This research brief presents results of an innovative pilot project designed to assess the socially differentiated effects of land-use/land-cover changes (LULCC) on Gwembe Tonga migrants living in Kulaale, an agricultural frontier in southern Zambia. Integrating existing analyses of remotely sensed imagery with a seasonal resource survey and mapping exercise (n = 20 homesteads), this study finds the average extractive workloads (mean annual distance traveled for the collection of bush resources) of women, men, girls, and boys to be both unequal and contrary to recent speculations about the distinctive vulnerability of adult women to environmental change. Drawing on qualitative ethnographic methods—including semi-structured interviews (n = 101), a homestead labor survey (n = 38), participant observation, and references to over fifty years of anthropological research—the author identifies additional variables—including the demographic structure of Kulaale homesteads and the flexible division of subsistence labor—that color Gwembe Tonga migrants’ aged and gendered experiences of LULCC. The study adds important nuance to our understanding of natural resource practices and individual-level vulnerability, particularly in the face of contemporary environmental change.
May 13th, 2014 by MVH
Fogle, M., Wulf, D., Morgan, K., McCammon, D., Seely, D. G., Draganić, I. N., et al. (2014). X-ray-emission measurements following charge exchange between C6+ and H2. Physical Review A, 89(4), 042705.
Abstract: Lyman x-ray spectra following charge exchange between C6+ and H2 are presented for collision velocities between 400 and 2300 km/s (1–30 keV/amu). Spectra were measured by a microcalorimeter x-ray detector capable of fully resolving the C vi Lyman series emission lines though Lyman-δ . The ratios of the measured emission lines are sensitive to the angular momentum l states populated during charge exchange and are used to gauge the effectiveness of different l-distribution models in predicting Lyman emission due to charge exchange. At low velocities, we observe that both single-electron-capture and double-electron-capture autoionization contribute to Lyman emission and that a statistical l distribution best describes the measured line ratios. At higher velocities single-electron capture dominates with the l distribution peaked at the maximum l.
May 7th, 2014 by MVH
Myers, P. (2013). The Ambivalence of a Spiritual Quest in India: Waldemar Bonsels’ Indienfahrt. In V. Fuechtner & M. Rhiel (Eds.), Imagining Germany, Imagining Asia : Essays in Asian-German Studies (pp. 131-154). Rochester, N.Y.: Camden House.
May 7th, 2014 by MVH
Shaffer, C. D., Alvarez, C. J., Bednarski, A. E., Dunbar, D., Goodman, A. L., Reinke, C., Saville, K., et al. (2014). A Course-Based Research Experience: How Benefits Change with Increased Investment in Instructional Time. CBE-Life Sciences Education, 13(1), 111-130.
Abstract: There is widespread agreement that science, technology, engineering, and mathematics programs should provide undergraduates with research experience. Practical issues and limited resources, however, make this a challenge. We have developed a bioinformatics project that provides a course-based research experience for students at a diverse group of schools and offers the opportunity to tailor this experience to local curriculum and institution-specific student needs. We assessed both attitude and knowledge gains, looking for insights into how students respond given this wide range of curricular and institutional variables. While different approaches all appear to result in learning gains, we find that a significant investment of course time is required to enable students to show gains commensurate to a summer research experience. An alumni survey revealed that time spent on a research project is also a significant factor in the value former students assign to the experience one or more years later. We conclude: 1) implementation of a bioinformatics project within the biology curriculum provides a mechanism for successfully engaging large numbers of students in undergraduate research; 2) benefits to students are achievable at a wide variety of academic institutions; and 3) successful implementation of course-based research experiences requires significant investment of instructional time for students to gain full benefit.
April 29th, 2014 by MVH
McWhirter, J. (2014). Rejected Prophets: Jesus and His Witnesses in Luke-Acts. Minneapolis, MN: Fortress Press.
Although several scholars have written about how Luke portrays Jesus and the apostles as prophets, no one has yet provided a comprehensive theory as to why Luke’s protagonists resemble the prophets. McWhirter shows that Luke uses these biblical prophets as precedents, seeking to legitimate the apostles’ teachings in the face of events, such as the destruction of Jerusalem and the deaths of Peter and Paul, which seem to contradict those teachings. In order to show that all this was part of God’s plan, Luke compares Jesus and his witnesses to Israel’s prophets who were rejected by their own people. (Publisher’s description).
April 17th, 2014 by MVH
Majure, L. C., Ionta, G. M., Skean, J. D., & Judd, W. S. (2013). New records and notes on species from Parc National Pic Macaya, Massif de la Hotte, Haiti, including a new species of Pilea (Urticaceae). Journal of the Botanical Research Institute of Texas, 7(2), 681-691.
Abstract: Nineteen species new to the flora of the Macaya Biosphere Reserve (including Parc National Pic Macaya) are reported, along with notes on five additional species. The Hispaniolan endemic Cyperus picardae is reported as new to the Massif de la Hotte, and a new species of Pilea, P. vermicularis (Urticaceae), from the Massif de la Hotte, is described and illustrated.
April 4th, 2014 by MVH
Shannon, K. M., Gage, G. J., Jankovic, A., Wilson, W. J., & Marzullo, T. C. (2014). Portable conduction velocity experiments using earthworms for the college and high school neuroscience teaching laboratory. Advances in Physiology Education, 38(1), 62-70.
Abstract: The earthworm is ideal for studying action potential conduction velocity in a classroom setting, as its simple linear anatomy allows easy axon length measurements and the worm’s sparse coding allows single action potentials to be easily identified. The earthworm has two giant fiber systems (lateral and medial) with different conduction velocities that can be easily measured by manipulating electrode placement and the tactile stimulus. Here, we present a portable and robust experimental setup that allows students to perform conduction velocity measurements within a 30-min to 1-h laboratory session. Our improvement over this well-known preparation is the combination of behaviorally relevant tactile stimuli (avoiding electrical stimulation) with the invention of minimal, low-cost, and portable equipment. We tested these experiments during workshops in both a high school and college classroom environment and found positive learning outcomes when we compared pre- and posttests taken by the students.
March 25th, 2014 by MVH
Franzen, T. (2014). Anna Howard Shaw: The Work of Woman Suffrage. Urbana, IL: University of Illinois Press.
Acknowledged by her contemporaries as the most outstanding woman suffrage orator of her time, Anna Howard Shaw (1847-1919) has nonetheless received minimal attention from historians. Trisha Franzen rectifies that oversight with this first scholarly biography of Shaw, a study that illuminates Shaw’s oft-ignored early years and challenges existing scholarship on her time in the suffrage movement.
An immigrant from a poor family, Shaw grew up in an economic reality that encouraged the adoption of non-traditional gender roles. Challenging traditional gender boundaries throughout her life, she put herself through college, worked as an ordained minister and a doctor, and built a tightly-knit family with her secretary and longtime companion Lucy E. Anthony.
Drawing on unprecedented research, Franzen shows how these circumstances and choices both impacted Shaw’s role in the woman suffrage movement and set her apart from her native-born, middle- and upper-class colleagues. Franzen also rehabilitates Shaw’s years as president of the National American Woman Suffrage Association, arguing that Shaw’s much-belittled tenure actually marked a renaissance of both NAWSA and the suffrage movement as a whole. (Publisher’s description)
February 27th, 2014 by MVH
Pifer, M., & Baker, V. (2013). Identity as a Theoretical Construct in Research about Academic Careers. In J. Huisman & M. Tight (Eds.), Theory and Method in Higher Education Research (Vol. 9, pp. 115-132): Emerald Group Publishing Limited.
Abstract: In this chapter, we review the ways in which scholars have conceptualized and relied on the notion of identity to understand the academic career. We explore the use of identity as a theoretical construct in research about the experience of being an academic. We discuss the individual and organizational factors that scholars have focused on when seeking to understand the role of professional and personal identity in academic careers, as well as recent and emerging shifts in the use of identity within this line of scholarship. Research suggests that if we are to understand the future of the academic career, we must understand the identities of its current and prospective members and, more importantly, how those identities shape goals, behaviors, and outcomes. We close with recommendations for future research and theory development.
February 13th, 2014 by MVH
Rabquer, B. J., & Koch, A. E. (2013). NK4 therapy: a new approach to target angiogenesis and inflammation in rheumatoid arthritis. Arthritis Research & Therapy, 15(5).
Abstract: Rheumatoid arthritis (RA) is a progressive autoimmune disease characterized by synovial membrane hyperplasia, inflammation, and angiogenesis. Hepatocyte growth factor (HGF) and its receptor, c-Met, are both overexpressed in the RA synovium. NK4 is an antagonist of HGF which has been shown to inhibit tumor growth, metastasis, and angiogenesis. In an experimental model of RA, NK4 gene therapy inhibited joint damage and inflammation in both preventative and therapeutic models. NK4 treatment therefore represents a possible therapeutic option in combating RA.
February 6th, 2014 by MVH
Neuberg, S. L., Warner, C. M., Mistler, S. A., Berlin, A., Hill, E. D., Johnson, J. D., et al. (2014). Religion and Intergroup Conflict: Findings From the Global Group Relations Project. Psychological Science, 25(1), 198-206.
Abstract: How might religion shape intergroup conflict? We tested whether religious infusion – the extent to which religious rituals and discourse permeate the everyday activities of groups and their members – moderated the effects of two factors known to increase intergroup conflict: competition for limited resources and incompatibility of values held by potentially conflicting groups. We used data from the Global Group Relations Project to investigate 194 groups (e.g., ethnic, religious, national) at 97 sites around the world. When religion was infused in group life, groups were especially prejudiced against those groups that held incompatible values, and they were likely to discriminate against such groups. Moreover, whereas disadvantaged groups with low levels of religious infusion typically avoided directing aggression against their resource-rich and powerful counterparts, disadvantaged groups with high levels of religious infusion directed significant aggression against them-despite the significant tangible costs to the disadvantaged groups potentially posed by enacting such aggression. This research suggests mechanisms through which religion may increase intergroup conflict and introduces an innovative method for performing nuanced, cross-societal research.
January 27th, 2014 by MVH
Liao, Q., & Li, Z. (2014). Portfolio optimization of computer and mobile botnets. International Journal of Information Security, 13(1), 1-14.
Abstract: Botnet, a network of compromised computers controlled by botmasters, can perform various forms of malicious attacks and has emerged as one of the top security problems yet to be solved. Traditionally, botmasters have been focusing on herding computers. As mobile computing devices such as smart phones and tablets are becoming increasingly popular, there are more targets exposed to hacking risks. While technical approaches have so far received limited results, we study the botnet problem from an alternative angle, i.e., economic perspectives of botnet industry. In this paper, we play devil’s advocate and think from the perspective of botmasters, i.e., how botmasters can evolve to maximize their profits in response to changing technologies. We adopt the concept of portfolio management, in which botmasters run their business through maintaining an optimal portfolio of PC and mobile devices to diversify risk and maximize profits of entire botnet industry. On the other hand, users may also maximize their utility function by keeping an optimal portfolio of network activities and data on their computers and mobile devices. The strategic playing by botmasters and users is modeled in a game theoretical framework. Various equilibrium solutions are discussed in terms of their welfare implications to botmasters and users. Understanding the optimal portfolio choice by botmasters provides insight for defenders, especially with evolving and diversified computing environments.
January 23rd, 2014 by MVH
Smellie, J. L., Rocchi, S., Wilch, T. I., Gemelli, M., Di Vincenzo, G., McIntosh, W., et al. (2014). Glaciovolcanic evidence for a polythermal Neogene East Antarctic Ice Sheet. Geology, 42(1), 39-42.
Abstract: A paradigm has existed for more than 30 years that the basal thermal regime of the East Antarctic Ice Sheet in Victoria Land made a fundamental transition from wet-based to cold-based either at ca. 14 Ma or after ca. 2.5 Ma. The basal thermal regime is important because it determines the potential for unstable behavior in an ice sheet. We have studied the environmental characteristics of subglacially erupted volcanic centers scattered along 800 km of the Ross Sea flank of the Transantarctic Mountains. The volcanoes preserve evidence for the coeval paleo-ice thicknesses and contain features diagnostic of both wet-based and cold-based ice conditions. By dating the sequences we are able to demonstrate that the basal thermal regime varied spatially and with time between ca. 12 Ma and present. It was polythermal overall and probably comprised a coarse temperature patchwork of frozen-bed and thawed-bed ice, similar to the East Antarctic Ice Sheet today. Thus, an important shift is required in the prevailing paradigm describing its temporal evolution.
January 16th, 2014 by MVH
Anissi, J., Sendide, K., & Olapade, O. (2014). Seasonal Shifts in the Bacterioplankton Assemblages of High Altitude Middle Atlas Lakes. Journal of Water Resource and Protection, 6(1), 1-7.
Abstract: Compositional changes of the bacterioplankton assemblages in four high altitude middle Atlas lakes were monitored over a complete seasonal cycle using combinations of culture-dependent and molecular approaches. Viable bacterial numbers varied between seasons, with the lowest numbers recorded in the winter and the highest in the summer in all four lakes. Also, bacterial occurrences were found to be strongly correlated with water temperature in all the four sites, i.e., Lake Aoua (0.88), Ifreh (0.59), Hechlef (0.77) and Affourgagh (0.79) during the study period. Standard microbiological characterization of bacteria isolates from the lakes revealed majority (68%) to be Gram positive. Seasonal variations in the microbial assemblages among the lakes were also validated by restriction fragment length polymorphism (RFLP). Shifts in microbial assemblages, especially of the fecal indicator bacteria appeared to also be influenced by differences in the morphometric and watershed characteristics among the lakes. This study further reveals the need to employ combinations of methodological approaches, including taxonomic, physiological and molecular methods to adequately delineate and fully understand the ecology of microbial assemblages in extreme environments.
January 16th, 2014 by MVH
Kish-Gephart, J., Detert, J., Treviño, L., Baker, V., & Martin, S. (2013). Situational Moral Disengagement: Can the Effects of Self-Interest be Mitigated? Journal of Business Ethics, 117(3), 1-19.
Abstract: Self-interest has long been recognized as a powerful human motive. Yet, much remains to be understood about the thinking behind self-interested pursuits. Drawing from multiple literatures, we propose that situations high in opportunity for self-interested gain trigger a type of moral cognition called moral disengagement that allows the individual to more easily disengage internalized moral standards. We also theorize two countervailing forces—situational harm to others and dispositional conscientiousness—that may weaken the effects of personal gain on morally disengaged reasoning. We test our hypotheses in two studies using qualitative and quantitative data and complementary research methods and design. We demonstrate that when personal gain incentives are relatively moderate, reminders of harm to others can reduce the likelihood that employees will morally disengage. Furthermore, when strong personal gain incentives are present in a situation, highly conscientious individuals are less apt than their counterparts to engage in morally disengaged reasoning.
January 13th, 2014 by MVH
Li, H., Mason, D. E., Bieler, T. R., Boehlert, C. J., & Crimp, M. A. (2013). Methodology for estimating the critical resolved shear stress ratios of α-phase Ti using EBSD-based trace analysis. Acta Materialia, 61(20), 7555-7567.
Abstract: A novel method for calculating the critical resolved shear stress (CRSS) ratios of different deformation system types in polycrystalline non-cubic metals has been developed. The mean CRSS ratios between different deformation systems were calculated for both commercially pure (CP) Ti and Ti–5Al–2.5Sn (wt.%) tensile deformed at ambient temperature and 455 °C using an in situ scanning electron microscope-based testing technique combined with electron backscattered diffraction. It was found that the relative activity of the different deformation systems changes as a function of alloying composition and deformation temperature. Prismatic slip was the most active deformation mode for CP Ti. CP Ti exhibited a lower resistance to prismatic slip at both ambient and elevated temperatures compared with Ti–5Al–2.5Sn. For Ti–5Al–2.5Sn, prismatic slip was the most active deformation system at ambient temperature although the basal slip activity significantly increased compared to CP Ti, mostly likely due to an increased c/a ratio resulting in a closer packed basal plane. At 455 °C, basal slip exhibited a lower CRSS than prismatic slip for Ti–5Al–2.5Sn. The relative activity of other deformation systems was also affected by alloying and temperature. The statistical resampling technique of bootstrapping was used to generate multiple equivalent data sets from which mean CRSS ratios between different deformation systems, and associated confidence intervals, could be deduced. It was found that the mean CRSS ratios at low and high strains varied slightly for the same testing conditions. Moreover, lesser activated slip systems resulted in relatively larger confidence intervals for the CRSS means. This variability may be attributed to a number of potential factors, including measurement errors, rotations of grains during deformation, local stress state variations, and work hardening. The analysis further suggests that awareness of the intrinsic statistical variability in CRSS ratios should be considered when formulating crystal plasticity constitutive models.