Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations of evaporable water within the fine structure of pastes, each having unique properties, and we present applied physics models that capture the hysteresis by dividing drying and rewetting into two related regimes based on relative humidity (RH). We show that a continuum model, incorporating a pore-blocking mechanism for desorption and equilibrium thermodynamics for adsorption, explains well the sorption hysteresis for a paste that remains above approximately 20% RH. In addition, we show with molecular models and experiments that water in spaces of ≲1  nm width evaporates below approximately 20% RH but reenters throughout the entire RH range. This water is responsible for a drying shrinkage hysteresis similar to that of clays but opposite in direction to typical mesoporous glass. Combining the models of these two regimes allows the entire drying and rewetting hysteresis to be reproduced accurately and provides parameters to predict the corresponding dimensional changes. The resulting model can improve the engineering predictions of long-term drying shrinkage accounting also for the history dependence of strain induced by hysteresis. Alternative strategies for quantitative analyses of the microstructure of cement paste based on this mesoscale physical model of water content within porous spaces are discussed.Portland Cement AssociationNational Ready Mixed Concrete Association (Research and Education Foundation)Schlumberger Foundatio

Is automatic imitation a specialized form of stimulus–response compatibility? Dissociating imitative and spatial compatibilities

In recent years research on automatic imitation has received considerable attention because it represents an experimental platform for investigating a number of inter-related theories suggesting that the perception of action automatically activates corresponding motor programs. A key debate within this research centers on whether automatic imitation is any different than other long-term S-R associations, such as spatial stimulus-response compatibility. One approach to resolving this issue is to examine whether automatic imitation shows similar response characteristics as other classes of stimulus-response compatibility. This hypothesis was tested by comparing imitative and spatial compatibility effects with a two alternative forced-choice stimulus-response compatibility paradigm and two tasks: one that involved selecting a response to the stimulus (S-R) and one that involved selecting a response to the opposite stimulus (OS-R), i.e., the one not presented. The stimulus for both tasks was a left or right hand with either the index or middle finger tapping down. Speeded responses were performed with the index or middle finger of the right hand in response to the finger identity or the left-right spatial position of the fingers. Based on previous research and a connectionist model, we predicted standard compatibility effects for both spatial and imitative compatibility in the S-R task, and a reverse compatibility effect for spatial compatibility but not for imitative compatibility in the OS-R task. The results from the mean response times, mean percentage of errors, and response time distributions all converged to support these predictions. A second noteworthy result was that the recoding of the finger identity in the OS-R task required significantly more time than the recoding of the left-right spatial position, but the encoding time for the two stimuli in the S-R task was equivalent. In sum, this evidence suggests that the processing of spatial and imitative compatibility is dissociable with regard to two different processes in dual processing models of stimulus-response compatibility

What do we mean by wet? Geoarchaeology and the reconstruction of water availability

Geoarchaeology has a key role to play in the human-climate-environment debate, including research into the controls and variability of water availability. However its interdisciplinarity can cause complications as well as advantages and leads to confusion as to what researchers should be investigating and how they should be reporting their findings. In this paper I investigate Geoarchaeology, and its place in 21st century science, as well as investigating its role in reconstructing past water availability and some of the challenges involved in ensuring these investigations are undertaken in a robust manner that will enhance academic knowledge and debate

First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional "sum-of-Gaussians" instrumental profile: 1.8 m s$^{-1}$ over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte

Positron-emission tomography–based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma

Background: Previous studies reported that early progression of disease (POD) after initial therapy predicted poor overall survival (OS) in patients with follicular lymphoma (FL). Here, we investigated whether pre-treatment imaging modality had an impact on prognostic significance of POD. Methods: In this retrospective study, we identified 1088 patients with grade I–IIIA FL; of whom, 238 patients with stage II–IV disease were initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and 346 patients were treated with rituximab-based chemotherapy. Patients (N = 484) from the FOLL05 study served as an independent validation cohort. We risk-stratified patients based on pre-treatment radiographic imaging (positron-emission tomography [PET] versus computed tomography [CT]) and early POD status using event-defining and landmark analyses. A competing risk analysis evaluated the association between early POD and histologic transformation. Results: In the discovery cohort, patients with POD within 24 months (PFS24) of initiating R-CHOP therapy had a 5-year OS of 57.6% for CT-staged patients compared with 70.6% for PET-staged patients. In the validation cohort, the 5-year OS for patients with early POD was 53.9% and 100% in CT- and PET-staged patients, respectively. The risk of histologic transformation in patients whose disease progressed within one year of initiating therapy was higher in CT-staged patients than in PET-staged patients (16.7% versus 6.3%, respectively), which was associated with a 9.7-fold higher risk of death. Conclusion: In FL, pre-treatment PET staging reduced the prognostic impact of early POD compared with CT staging. Patients with early POD and no histologic transformation have an extended OS with standard therapy

Reflections on a crisis: political disenchantment, moral desolation, and political integrity

Declining levels of political trust and voter turnout, the shift towards populist politics marked by appeals to ‘the people’ and a rejection of ‘politics-as-usual’, are just some of the commonly cited manifestations of our culture of political disaffection. Democratic politics, it is argued, is in crisis. Whilst considerable energy has been expended on the task of lamenting the status of our politics and pondering over recommendations to tackle this perceived crisis, amid this raft of complaints and solutions lurks confusion. This paper seeks to explore the neglected question of what the precise nature of the crisis with which we are confronted involves, and, in so doing, to go some way towards untangling our confusion. Taking my cue from Machiavelli and his value-pluralist heirs, I argue that there is a rift between a morally admirable and a virtuous political life. Failure to appreciate this possibility causes narrations of crisis to misconstrue the moral messiness of politics in ways that lead us to misunderstand how we should respond to disenchantment. Specifically, I suggest that: (i) we think that there is a moral crisis in politics because we have an unsatisfactorily idealistic understanding of political integrity in the first place; and (ii) it is a mistake to imagine that the moral purification of politics is possible or desirable. Put simply, our crisis is not moral per se but primarily philosophical in nature: it relates to the very concepts we employ—the qualities of character and context we presuppose whilst pondering over political integrity

Comparing Team Evaluation Software (Team+ and CATME)

The first-year program at Michigan Technological University emphasizes an active, collaborative learning environment. Students are grouped into teams of 3-5 students to work on class activities and projects. The success of this program relies on the students learning to work together and numerous activities in the class are designed to help build these teamwork skills. For example, teams are expected to build a team contract at the beginning of the semester and provide formative and summative feedback to each team member in the form of peer evaluations.In the Fall of 2021, four faculty members at Michigan Technological University evaluated two different teaming systems designed to help enhance these teamwork skills: CATME and Team+. A total of 402 students, in 19 sections of our first-year engineering course participated in this study. Sections were randomly assigned to using either the CATME or Team+ tool. Eight sections (170 students) used the CATME tool and eleven sections (232 students) used Team+. We have historically used the CATME team tool in our courses for peer evaluation. Comparing peer evaluation results with Team+ is one metric we used to measure how our first-year engineering populations responded to this new teaming software. Additionally, we evaluated the impact both of these tools had on team connectedness and satisfaction as well as participation levels in team development activities throughout the semester. This paper will summarize these overall quantitative metrics as well as the reflections from students and faculty on both teaming systems

Interpretation of Full Sorption-Desorption Isotherms as a Tool for Understanding Concrete Pore Structure

Sorption isotherms are frequently used to characterize the structure of porous materials such as cement. Their interpretation has been somewhat hindered by the large hysteresis observed between the adsorption and desorption processes. Here, we model the hysteresis due to pore blocking, whereby water condensed in small pores prevents propagation of a vapour interface into the pore structure, trapping water condensed in larger pores in a metastable state. The model identifies the adsorption isotherm as more useful in determining the pore size distribution. Additionally, and of particular interest, it provides a way of calculating an additional structural parameter, quantifying the exposure of mesopores (gel pores) to the surrounding atmosphere. This exposure is higher for samples with higher water-to-cement ratio, suggesting that it is mediated by capillary pores. The model also allows calculation of the connectivity of the pore structure, although the intertwined influences of exposure and connectivity make the latter difficult to interpret