Search for: All records

Engineering is a creative profession where diverse perspectives of both men and women are crucial to the field. The importance of better understanding the pipeline of female students into engineering, and the path to their success in the major is evident. In 2017, women comprised approximately 20% of engineering graduates, up from 18% in 1997, and 15% never entered the engineering workforce. In 2019, women comprised 48% of the workforce, 34% of the STEM workforce, and only 16% of practicing engineers, a 3% increase from 2009. In an effort to better understand these disparities, this mixed methods research investigated the creative self-efficacy (CSE) of women engineering majors and their beliefs about creativity in relation to lived experiences and explores the research question: In what ways do undergraduate women engineering students describe their creativity and how their lived experiences influenced their decision to major in engineering? The researchers investigated the lived experiences of women engineering students before they entered the engineering major in relation to the way they described themselves as creative. A survey of CSE and beliefs about creativity was administered to 121 undergraduate women engineering students who volunteered for this study. Interviews were conducted of 15 participants selected from survey results with different levels of CSE who met the researcher’s criteria for success in the engineering major. The findings of this study lead to several conclusions: (1) students’ descriptions of themselves as creative corresponded more with the arts than to innovation in engineering; (2) students who described themselves as less creative: (a) had a lower level of CSE; (b) had a greater exposure to engineering in high school through engineering-centered courses and clubs; (c) had a family member who worked in the profession; (d) described more negative classroom experiences at all educational levels that involved intimidation, isolation, and gender-bias. 

Virtual professional development increases meaningful and diverse learning opportunities for in-service teachers (Darling-Hammond & McLaughlin, 2011). As part of virtual professional development the participants in this study engaged in doing math collaboratively and began thinking about mathematical and pedagogical decision making within their classrooms. Preliminary results suggest that participants valued the time to think flexibly about their own work and that of others and began to learn to recognize the hidden decisions they were making when solving a problem that it may benefit their students to know. 

Understanding how to design online professional development environments that support mathematics teachers in developing mathematical and pedagogical knowledge is more important than ever. We argue that productive social and sociomathematical (SM) norms have benefits for teachers learning mathematics in online asynchronous collaboration and that particular patterns in interactions can create context for the emergence of such norms. We employed social network analysis to compare the emerging social networks of two iterations of an online asynchronous professional development course focused on functions to understand whether particular scaffolds can support the emergence of specific patterns of interactions. Results suggest that evidence-based noticing and wondering can impact the “small world” properties of a social network and associated potential for the emergence of social and SM norms. 

The EnCoMPASS project (Emerging Communities for Mathematical Practices and Assessment) at Drexel University has produced a web-based software tool for the assessment of student work. This paper discusses research on the impact of this tool on teachers’ attitudes toward engaging with students in the software environment. The tool supports teachers adopting a more dialogic perspective towards learning and teaching through cycles of problem solving, discussion and mathematical development. It is suggested that the tool aids teachers’ transition toward this more interactive approach to teaching mathematics while also acknowledging and addressing concerns about the time it takes to engage in more detailed dialogue and thinking about mathematics with their students. 

Creative self-efficacy (CSE) was studied in connection to beliefs about creativity. CSE is one’s belief in their own creative potential. The belief that creativity can improve was discussed as a “Growth Creativity Mindset” (GCM), and the belief that creativity cannot improve was discussed as a “Fixed Creativity Mindset” (FCM). Creativity within engineering has been described as crucial to the field, and as an aspect that is appealing to women engineers. Undergraduate women engineering students local to the Philadelphia area volunteered to take a survey of CSE and beliefs about creativity. Quantitative data analysis showed that an increase in GCM likely results in an increase in CSE for students with higher than average GPA. A change in CSE had no effect on FCM. Interviews were conducted with 15 survey respondents with different levels of CSE who met criteria for success in the engineering major (2.5 GPA or above and successful completion of calculus II). Synthesis of the quantitative and qualitative data revealed that interview participants had similar lived experiences that lead them to a level of success in the engineering major, but different lived experiences that distinguished them with respect to CSE level. All participants were exposed to project based learning (PBL), had strong personal influences, exhibited perseverance in overcoming struggles, and described their negative perceptions of engineering before entering the major. Participants with all levels of CSE highlighted their own creativity with respect to the performing and visual arts, before reflecting on innovation as creative. Most participants with low CSE described their lack of creativity in the arts. They also discussed being “intimidated” by negative classroom experiences more than their peers with higher levels of CSE. Those with low CSE were also exposed to more engineering centered experiences in high school, and most had a parent who worked in the profession. It is expected that this research will provide a more comprehensive understanding of CSE, perceptions of engineering as a creative field, and the educational reform needed that connects creativity to engineering in an atmosphere that welcomes diversity. 

We present 10 main-sequence ALPINE galaxies (log (M/M⊙) = 9.2−11.1 and ${\rm SFR}=23-190\, {\rm M_{\odot }\, yr^{-1}}$) at z ∼ 4.5 with optical [O ii] measurements from Keck/MOSFIRE spectroscopy and Subaru/MOIRCS narrow-band imaging. This is the largest such multiwavelength sample at these redshifts, combining various measurements in the ultraviolet, optical, and far-infrared including [C ii]158 $\mu$m line emission and dust continuum from ALMA and H α emission from Spitzer photometry. For the first time, this unique sample allows us to analyse the relation between [O ii] and total star-formation rate (SFR) and the interstellar medium (ISM) properties via [O ii]/[C ii] and [O ii]/H α luminosity ratios at z ∼ 4.5. The [O ii]−SFR relation at z ∼ 4.5 cannot be described using standard local descriptions, but is consistent with a metal-dependent relation assuming metallicities around $50{{\ \rm per\ cent}}$ solar. To explain the measured dust-corrected luminosity ratios of $\log (L_{\rm [OII]}/L_{\rm [CII]}) \sim 0.98^{+0.21}_{-0.22}$ and $\log (L_{\rm [OII]}/L_{\rm H\alpha }) \sim -0.22^{+0.13}_{-0.15}$ for our sample, ionization parameters log (U) < −2 and electron densities $\log (\rm n_e / {\rm [cm^{-3}]}) \sim 2.5-3$ are required. The former is consistent with galaxies at z ∼ 2−3, however lower than at z > 6. The latter may be slightly higher than expected given the galaxies’ specific SFR. The analysis of this pilot sample suggests that typical log (M/M⊙) > 9 galaxies at z ∼ 4.5 to have broadly similar ISM properties as their descendants at z ∼ 2 and suggest a strong evolution of ISM properties since the epoch of reionization at z > 6.

 

Aims. The dust content of normal galaxies and the dust mass density (DMD) at high- z ( z  > 4) are unconstrained given the source confusion and the sensitivity limitations of previous observations. The ALMA Large Program to INvestigate [CII] at Early times (ALPINE), which targeted 118 ultra-violet (UV)-selected star-forming galaxies at 4.4 <  z  < 5.9, provides a new opportunity to tackle this issue for the first time with a statistically robust dataset. Methods. We exploited the rest-frame far-infrared (FIR) fluxes of 23 galaxies individually detected in their continuum emission, as well as stacked continuum images, to measure the dust content of the 118 UV-selected ALPINE galaxies. We focused on the dust scaling relations and, by comparison with predictions from chemical evolution models, we probed the evolutionary stage of UV-selected galaxies at high- z . By using the observed correlation between the UV luminosity and the dust mass, we estimated the DMD of UV-selected galaxies at z  ∼ 5, weighting the galaxies by means of the UV luminosity function. The derived DMD is compared with the value we estimated from ten ALPINE galaxies blindly detected in the FIR continuum, at the redshift of the ALPINE targets. Results. Our ALMA survey allows the exploration for the first time of the dust content in normal star-forming galaxies at z  > 4 in a statistically robust sample of sources. The comparison of the observed dust scaling relations with chemical evolution models suggests that ALPINE galaxies are not likely progenitors of disc galaxies, but of intermediate- and low-mass proto-spheroids, resulting in present-day bulges of spiral or elliptical galaxies. Interestingly, this conclusion is in line with the independent morphological analysis that shows that the majority (∼70%) of the dust-continuum detected galaxies have a disturbed morphology. The DMD obtained at z  ∼ 5 from UV-selected sources is ∼30% of the value obtained from blind FIR-selected sources, showing that the UV selection misses the most dust-rich, UV-obscured galaxies. 

Star formation rate (SFR) measurements at z  > 4 have relied mostly on the rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on the IRX- β relation are highly uncertain and are still debated in the literature. Hence, rest-frame far-infrared (FIR) observations are necessary to constrain the dust-obscured component of the SFR. In this paper, we exploit the rest-frame FIR continuum observations collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) to directly constrain the obscured SFR in galaxies at 4.4 <  z  < 5.9. We used stacks of continuum images to measure average infrared luminosities taking both detected and undetected sources into account. Based on these measurements, we measured the position of the main sequence of star-forming galaxies and the specific SFR (sSFR) at z  ∼ 4.5 and z  ∼ 5.5. We find that the main sequence and sSFR do not significantly evolve between z  ∼ 4.5 and z  ∼ 5.5, as opposed to lower redshifts. We developed a method to derive the obscured SFR density (SFRD) using the stellar masses or FUV-magnitudes as a proxy of FIR fluxes measured on the stacks and combining them with the galaxy stellar mass functions and FUV luminosity functions from the literature. We obtain consistent results independent of the chosen proxy. We find that the obscured fraction of SFRD is decreasing with increasing redshift, but even at z  ∼ 5.5 it constitutes around 61% of the total SFRD. 

We present ALMA observations of a merging system at z  ∼ 4.57, observed as a part of the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. Combining ALMA [CII]158  μ m and far-infrared continuum data with multi-wavelength ancillary data, we find that the system is composed of two massive ( M ⋆  ≳ 10 10   M ⊙ ) star-forming galaxies experiencing a major merger (stellar mass ratio r mass  ≳ 0.9) at close spatial (∼13 kpc; projected) and velocity (Δ v  <  300 km s −1 ) separations, and two additional faint narrow [CII]-emitting satellites. The overall system belongs to a larger scale protocluster environment and is coincident to one of its overdensity peaks. Additionally, ALMA reveals the presence of [CII] emission arising from a circumgalactic gas structure, extending up to a diameter-scale of ∼30 kpc. Our morpho-spectral decomposition analysis shows that about 50% of the total flux resides between the individual galaxy components, in a metal-enriched gaseous envelope characterised by a disturbed morphology and complex kinematics. Similarly to observations of shock-excited [CII] emitted from tidal tails in local groups, our results can be interpreted as a possible signature of interstellar gas stripped by strong gravitational interactions, with a possible contribution from material ejected by galactic outflows and emission triggered by star formation in small faint satellites. Our findings suggest that mergers could be an efficient mechanism of gas mixing in the circumgalactic medium around high- z galaxies, and thus play a key role in the galaxy baryon cycle at early epochs. 

Context. The Lyman- α line in the ultraviolet (UV) and the [CII] line in the far-infrared (FIR) are widely used tools to identify galaxies in the early Universe and to obtain insights into interstellar medium (ISM) properties in high-redshift galaxies. By combining data obtained with ALMA in band 7 at ∼320 GHz as part of the ALMA Large Program to INvestigate [CII] at Early Times (ALPINE) with spectroscopic data from DEIMOS at the Keck Observatory, VIMOS and FORS2 at the Very Large Telescope, we assembled a unique sample of 53 main-sequence star-forming galaxies at 4.4 <   z  <  6 in which we detect both the Lyman- α line in the UV and the [CII] line in the FIR. Aims. The goal of this paper is to constrain the properties of the Ly α emission in these galaxies in relation to other properties of the ISM. Methods. We used [CII], observed with ALMA, as a tracer of the systemic velocity of the galaxies, and we exploited the available optical spectroscopy to obtain the Ly α -[CII] and ISM-[CII] velocity offsets. Results. We find that 90% of the selected objects have Ly α -[CII] velocity offsets in the range 0 <  Δ v Ly α  − [CII]  <  400 km s −1 , in line with the few measurements available so far in the early Universe, and significantly smaller than those observed at lower redshifts. At the same time, we observe ISM-[CII] offsets in the range −500 <  Δ v ISM−[CII]  <  0 km s −1 , in line with values at all redshifts, which we interpret as evidence for outflows in these galaxies. We find significant anticorrelations between Δ v Ly α −[CII] and the Ly α rest-frame equivalent width EW 0 (Ly α ) (or equivalently, the Ly α escape fraction f esc (Ly α )): galaxies that show smaller Δ v Ly α −[CII] have larger EW 0 (Ly α ) and f esc (Ly α ). Conclusions. We interpret these results in the framework of available models for the radiative transfer of Ly α photons. According to the models, the escape of Ly α photons would be favored in galaxies with high outflow velocities, producing large EW 0 (Ly α ) and small Δ v Ly α -[CII] , in agreement with our observations. The uniform shell model would also predict that the Ly α escape in galaxies with slow outflows (0 <   v out  <  300 km s −1 ) is mainly determined by the neutral hydrogen column density (NHI) along the line of sight, while the alternative model by Steidel et al. (2010, ApJ, 717, 289) would more highly favor a combination of NHI at the systemic velocity and covering fraction as driver of the Ly α escape. We suggest that the increase in Ly α escape that is observed in the literature between z  ∼ 2 and z  ∼ 6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease in average NHI along the line of sight, or alternatively, a decrease in HI covering fraction.