253 research outputs found
Testing Modality Affects Performance on the Santa Barbara Solids Test
Spatial ability is associated with performance in science, technology, engineering, and mathematics (STEM) disciplines and has been used to predict the likelihood of success in these fields (Wai, Lubinski, & Benbow, 2009). Classically, spatial ability has been assessed by tests that measure general factors of spatial ability. However, these factors may be limited in that they were not developed with individual differences or cognitive theories in mind (Cohen & Hegarty, 2012). Although traditional measures of spatial ability give insight into a person’s general spatial processing, Cohen and Hegarty (2012) point out the need for theoretically motivated spatial ability tests that specifically relate to STEM performance. There are numerous spatial ability measures in use by researchers, yet there is a need for reliable and valid spatial ability measures that are directly applicable to STEM fields.
One new measure of spatial ability developed theoretically with individual differences in mind is the Santa Barbara Solids Test (SBST; Cohen & Hegarty, 2012). In the SBST, participants must imagine what the bisection of three-dimensional forms will be when cut by a two-dimensional plane. This bisection can be horizontal, vertical, or oblique, and the shape can be a simple or complex three-dimensional form. The spatial skills involved in imagining a cross-section of a form have been linked with performance in STEM courses, such as anatomy (Rochford, 1985), biology (Russell-Gebbett, 1985), geology (Kali & Orion, 1996), geometry (Pittalis & Christou, 2010), engineering (Duesbury & O’Neil, 1996), and skills such as reading x-rays and MRIs (Hegarty, Keehner, Cohen, Montello, & Lippa, 2007).
The SBST has been validated with undergraduate students with a range of spatial ability scores (Cohen & Hegarty, 2012), but additional studies of the SBST are needed to replicate and expand on the findings of this promising new measure. For example, it is important to determine the effects of testing modality on performance to highlight a potential confound in future spatial ability studies. Although computerized assessments are common and offer many conveniences (e.g., fast scoring, fewer resources) compared to other testing modalities (e.g., paper-based testing), participants may experience higher perceived workload in computer-based assessments (Mayes, Sims, & Koonce, 2001) or perform differently on the same test in another modality (c.f. Noyes & Garland, 2008). The current study (n = 241) compares the SBST with a traditional measure of spatial ability, the Paper Folding Test (PFT; Ekstrom, French, Harman, & Dermen, 1976), in two testing modalities: 1) computer-based, and 2) paper-based. Results showed there was a correlation between the spatial ability measures, indicating both were tapping the same underlying construct. There was not a difference in performance between testing modalities for the PFT. However, there was a difference in performance based on testing modality for the SBST such that participants in the paper-based condition performed better than those in the computerized condition. The implications of these results are that testing modality should be a consideration for future studies involving the SBST
Global aggregation of newly translated proteins in an Escherichia coli strain deficient of the chaperonin GroEL
A search for transients in the Reionization Lensing Cluster Survey (RELICS): Three new supernovae
The Reionization Cluster Survey (RELICS) imaged 41 galaxy clusters with the
Hubble Space Telescope (HST), in order to detect lensed and high-redshift
galaxies. Each cluster was imaged to about 26.5 AB mag in three optical and
four near-infrared bands, taken in two distinct visits separated by varying
time intervals. We make use of the multiple near-infrared epochs to search for
transient sources in the cluster fields, with the primary motivation of
building statistics for bright caustic crossing events in gravitational arcs.
Over the whole sample, we do not find any significant ()
caustic crossing events, in line with expectations from semi-analytic
calculations but in contrast to what may be naively expected from previous
detections of some bright events, or from deeper transient surveys that do find
high rates of such events. Nevertheless, we find six prominent supernova (SN)
candidates over the 41 fields: three of them were previously reported and three
are new ones reported here for the first time. Out of the six candidates, four
are likely core-collapse (CC) SNe -- three in cluster galaxies, and among which
only one was known before, and one slightly behind the cluster at
. The other two are likely Ia -- both of them previously known,
one probably in a cluster galaxy, and one behind it at . Our study
supplies empirical bounds for the rate of caustic crossing events in galaxy
cluster fields to typical HST magnitudes, and lays the groundwork for a future
SN rate study.Comment: Accepted for publication in MNRAS. 10 pages, 3 figure
Unscrambling the lensed galaxies in JWST images behind SMACS0723
The first deep field images from the James Webb Space Telescope (JWST) of the
galaxy cluster SMACS~J0723.3-7327 reveal a wealth of new lensed images at
uncharted infrared wavelengths, with unprecedented depth and resolution. Here
we securely identify 14 new sets of multiply imaged galaxies totalling 42
images, adding to the five sets of bright and multiply-imaged galaxies already
known from Hubble Space Telescope data. We find examples of arcs crossing
critical curves, allowing detailed community follow-up, such as JWST
spectroscopy for precise redshift determinations, and measurements of the
chemical abundances and of the detailed internal gas dynamics of very distant,
young galaxies. One such arc contains compact knots of magnification
750, and features a microlensed transient. We also detect an Einstein
cross candidate only visible thanks to JWST's superb resolution. Our parametric
lens model is available at
https://www.dropbox.com/sh/gwup2lvks0jsqe5/AAC2RRSKce0aX-lIFCc9vhBXa?dl=0 , and
will be regularly updated using additional spectroscopic redshifts. The model
reproduces the multiple images to better than an rms of ,
and allows for accurate magnification estimates of high-redshift galaxies. The
intracluster light extends beyond the cluster members, exhibiting large-scale
features that suggest a significant past dynamical disturbance. This work
represents a first taste of the enhanced power JWST will have for
lensing-related science.Comment: Submitted to ApJ. 13 pages, 6 figure
N-Glycosylation of ß4 Integrin Controls the Adhesion and Motility of Keratinocytes
α6ß4 integrin is an essential component of hemidesmosomes and modulates cell migration in wound healing and cancer invasion. To elucidate the role of N-glycosylation on ß4 integrin, we investigated keratinocyte adhesion and migration through the re-expression of wild-type or N-glycosylation-defective ß4 integrin (ΔNß4) in ß4 integrin null keratinocytes. N-glycosylation of ß4 integrin was not essential for the heterodimer formation of ß4 integrin with α6 integrin and its expression on a cell surface, but N-glycosylation was required for integrin-mediated cell adhesion and migration. Concomitantly with the reduction of ß4 integrin in the membrane microdomain, the intracellular signals of Akt and ERK activation were decreased in cells expressing ΔNß4 integrin. Forced cross-linking of ß4 integrin rescued the decreased ERK activation in ΔNß4 integrin-expressing cells to a similar extent in wild-type ß4 integrin-expressing cells. Surprisingly, compared with cells expressing wild-type ß4 integrin, an alternation in N-glycan structures expressed on epidermal growth factor receptor (EGFR), and the induction of a stronger association between EGFR and ß4 integrin were observed in ΔNß4 integrin-expressing cells. These results clearly demonstrated that N-glycosylation on ß4 integrin plays an essential role in keratinocyte cellular function by allowing the appropriate complex formation on cell surfaces
JWST's PEARLS: Mothra, a new kaiju star at z=2.091 extremely magnified by MACS0416, and implications for dark matter models
We report the discovery of Mothra, an extremely magnified monster star,
likely a binary system of two supergiant stars, in one of the strongly lensed
galaxies behind the galaxy cluster MACS0416. The star is in a galaxy with
spectroscopic redshift in a portion of the galaxy that is parsecs
away from the cluster caustic. The binary star is observed only on the side of
the critical curve with negative parity but has been detectable for at least
eight years, implying the presence of a small lensing perturber.
Microlenses alone cannot explain the earlier observations of this object made
with the Hubble Space Telescope. A larger perturber with a mass of at least
\,\Msun\ offers a more satisfactory explanation. Based on the lack of
perturbation on other nearby sources in the same arc, the maximum mass of the
perturber is \,\Msun, making it the smallest substructure
constrained by lensing above redshift 0.3. The existence of this millilens is
fully consistent with the expectations from the standard cold dark matter
model. On the other hand, the existence of such small substructure in a cluster
environment has implications for other dark matter models. In particular, warm
dark matter models with particle masses below 8.7\,keV are excluded by our
observations. Similarly, axion dark matter models are consistent with the
observations only if the axion mass is in the range .Comment: 26 pages and 27 figure
Reaching for the stars – JWST/NIRSpec spectroscopy of a lensed star candidate at z = 4.76
We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of zphot ≃ 4.8, previously detected in JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015 (z = 0.591). The spectroscopic observation allows us to precisely measure the redshift of the host arc at zspec = 4.758 ± 0.004, and the star’s spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature K with either a redder F-type companion ( K) or significant dust attenuation (AV ≃ 0.82) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, r ≲ 0.5 pc, could indicate that this scenario is somewhat less likely – albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only ∼1.2 Gyr old showcases the ability of JWST to study early stars through extreme lensing
Reaching for the stars -- JWST/NIRSpec spectroscopy of a lensed star candidate at
We present JWST/NIRSpec observations of a highly magnified star candidate at
a photometric redshift of , previously detected in
JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015
(). The spectroscopic observation allows us to precisely measure the
redshift of the host arc at , and the star's
spectrum displays clear Lyman- and Balmer-breaks commensurate with this
redshift. A fit to the spectrum suggests a B-type super-giant star of surface
temperature K with either a redder F-type
companion (K) or significant dust attenuation
() along the line of sight. We also investigate the possibility
that this object is a magnified young globular cluster rather than a single
star. We show that the spectrum is in principle consistent with a star cluster,
which could also accommodate the lack of flux variability between the two
epochs. However, the lack of a counter image and the strong upper limit on the
size of the object from lensing symmetry, pc, could indicate
that this scenario is somewhat less likely -- albeit not completely ruled out
by the current data. The presented spectrum seen at a time when the Universe
was only Gyr old showcases the ability of JWST to study early stars
through extreme lensing.Comment: Accepted for publication in MNRAS letters. v2 updated to match the
published versio
The DEAD-box RNA Helicase DDX6 is Required for Efficient Encapsidation of a Retroviral Genome
Viruses have to encapsidate their own genomes during the assembly process. For most RNA viruses, there are sequences within the viral RNA and virion proteins needed for high efficiency of genome encapsidation. However, the roles of host proteins in this process are not understood. Here we find that the cellular DEAD-box RNA helicase DDX6 is required for efficient genome packaging of foamy virus, a spumaretrovirus. After infection, a significant amount of DDX6, normally concentrated in P bodies and stress granules, re-localizes to the pericentriolar site where viral RNAs and Gag capsid proteins are concentrated and capsids are assembled. Knockdown of DDX6 by siRNA leads to a decreased level of viral nucleic acids in extracellular particles, although viral protein expression, capsid assembly and release, and accumulation of viral RNA and Gag protein at the assembly site are little affected. DDX6 does not interact stably with Gag proteins nor is it incorporated into particles. However, we find that the ATPase/helicase motif of DDX6 is essential for viral replication. This suggests that the ATP hydrolysis and/or the RNA unwinding activities of DDX6 function in moderating the viral RNA conformation and/or viral RNA-Gag ribonucleoprotein complex in a transient manner to facilitate incorporation of the viral RNA into particles. These results reveal a unique role for a highly conserved cellular protein of RNA metabolism in specifically re-locating to the site of viral assembly for its function as a catalyst in retroviral RNA packaging
Spectroscopy of the Supernova H0pe Host Galaxy at Redshift 1.78
Supernova (SN) H0pe was discovered as a new transient in James Webb Space
Telescope (JWST) NIRCam images of the galaxy cluster PLCK G165.7+67.0 taken as
part of the "Prime Extragalactic Areas for Reionization and Lensing Science"
(PEARLS) JWST GTO program (# 1176) on 2023 March 30 (AstroNote 2023-96; Frye et
al. 2023). The transient is a compact source associated with a background
galaxy that is stretched and triply-imaged by the cluster's strong
gravitational lensing. This paper reports spectra in the 950-1370 nm observer
frame of two of the galaxy's images obtained with Large Binocular Telescope
(LBT) Utility Camera in the Infrared (LUCI) in longslit mode two weeks after
the \JWST\ observations. The individual average spectra show the [OII] doublet
and the Balmer and 4000 Angstrom breaks at redshift z=1.783+/-0.002. The CIGALE
best-fit model of the spectral energy distribution indicates that SN H0pe's
host galaxy is massive (Mstar~6x10^10 Msun after correcting for a magnification
factor ~7) with a predominant intermediate age (~2 Gyr) stellar population,
moderate extinction, and a magnification-corrected star formation rate ~13
Msun/yr, consistent with being below the main sequence of star formation. These
properties suggest that H0pe might be a type Ia SN. Additional observations of
SN H0pe and its host recently carried out with JWST (JWST-DD-4446; PI: B. Frye)
will be able to both determine the SN classification and confirm its
association with the galaxy analyzed in this work.Comment: 6 pages, 4 figures, Letter accepted for publication in Astronomy &
Astrophysic
- …