369 research outputs found
On the relation between oral contraceptive use and self-control
In two studies we examined the relation between oral contraceptive (OC) use and self-reported levels of self-control in undergraduate women using OCs (Study 1: OC group N = 399, Study 2: OC group N = 288) and naturally cycling women not using any form of hormonal contraceptives (Study 1: Non-OC group N = 964, Study 2: Non-OC group N = 997). We assessed the self-overriding aspect of self-control using the Brief Self-Control Scale (BSCS) and strategies for self-regulation using the Regulatory Mode Scale (RMS), which separately measures the tendency to assess one’s progress towards a goal (assessment), and the tendency to engage in activities that move one towards an end goal (locomotion). In Study 1, we found no significant differences between OC and non-OC groups in their levels of self-overriding or self-regulatory assessment. However, we found that those in the OC group reported significantly greater levels of self-regulatory locomotion compared to those in the non-OC group, even after controlling for depression symptoms and the semester of data collection. The findings from Study 2 replicated the findings from Study 1 in a different sample of participants, with the exception that OC use was also related to higher levels of assessment in Study 2. These results indicate that OC use is related to increases in self-regulatory actions in service of goal pursuit and perhaps the tendency to evaluate progress towards goals
A New Method to Measure and Map the Gas Scale-Height of Disk Galaxies
We propose a new method to measure and map the gas scale height of nearby
disk galaxies. This method is applied successfully to the Australia Telescope
Compact Array interferometric HI survey of the Large Magellanic Cloud (LMC); it
could also be applied to a significant number of nearby disk galaxies, thanks
to the next generation of interferometric facilities, such as the extended VLA
and CARMA.
The method consists of computing the Spectral Correlation Function (SCF) for
a spectral-line map of a face-on galaxy. The SCF quantifies the correlation
between spectra at different map positions as a function of their separation,
and is sensitive to the properties of both the gas mass distribution and the
gas velocity field. It is likely that spatial correlation properties of the gas
density and velocity fields in a galactic disk are sensitive to the value of
the scale height of the gas disk. A scale-free turbulent cascade is unlikely to
extend to scales much larger than the disk scale height, as the disk dynamics
on those larger scales should be dominated by two dimensional motions.
We find a clear feature in the SCF of the LMC HI disk, on the scale of
approximately 180 pc, which we identify as the disk scale height. We are also
tentatively able to map variations of the scale height over the disk.Comment: 6 pages, submitted to ApJ
Estimation of Short-Term Tag-Induced Mortality in Horseshoe Crabs Limulus Polyphemus
Horseshoe crabs Limulus Polyphemus range along the East Coast of the United States and over 150,000 of them have been marked with U.S. Fish and Wildlife Service disk tags. It has been assumed that the tags do not harm the animals and are similar to common epibionts often found on the shells of the horseshoe crabs. We investigated whether newlv tagged adult female horseshoe crabs would exhibit higher short-term mortality rates than untagged adult females. All crabs were collected from a beach in Connecticut and then were transported to a laboratory for the experiment. Tagging involved drilling a small hole through the carapace in the lower back corner or the prosoma and then inserting the tag into the hole. Overall mortality of the tagged and untagged females held in flow-through raceways for 44 d was minimal (0% mortality among 53 tagged crabs; 4% mortality among 52 untagged crabs). None of the horseshoe crabs lost or shed their disk tags over the course of the experiment. In field mark-recapture studies of horseshoe crabs, typically between 11% and 20% of the initial numbers of tagged crabs are recaptured. Crabs that are recaptured but reported dead are unlikely to have died from the initial tagging process. Our results indicate that newly tagged adult horseshoe crabs have the potential to survive as well as untagged crabs through the Connecticut spawning season (~30-45 d). Recapture data also suggest that these crabs can survive for as long Its 8-10 years with the tags in place
Grainyhead-like 2 inhibits the coactivator p300, suppressing tubulogenesis and the epithelial–mesenchymal transition
Developmental morphogenesis and tumor progression require a transient or stable breakdown of epithelial junctional complexes to permit programmed migration, invasion, and anoikis resistance, characteristics endowed by the epithelial–mesenchymal transition (EMT). The epithelial master-regulatory transcription factor Grainyhead-like 2 (GRHL2) suppresses and reverses EMT, causing a mesenchymal–epithelial transition to the default epithelial phenotype. Here we investigated the role of GRHL2 in tubulogenesis of Madin–Darby canine kidney cells, a process requiring transient, partial EMT. GRHL2 was required for cystogenesis, but it suppressed tubulogenesis in response to hepatocyte growth factor. Surprisingly, GRHL2 suppressed this process by inhibiting the histone acetyltransferase coactivator p300, preventing the induction of matrix metalloproteases and other p300-dependent genes required for tubulogenesis. A 13–amino acid region of GRHL2 was necessary for inhibition of p300, suppression of tubulogenesis, and interference with EMT. The results demonstrate that p300 is required for partial or complete EMT occurring in tubulogenesis or tumor progression and that GRHL2 suppresses EMT in both contexts through inhibition of p300
Bridging the Gap: Generalising State-of-the-Art U-Net Models to Sub-Saharan African Populations
A critical challenge for tumour segmentation models is the ability to adapt
to diverse clinical settings, particularly when applied to poor-quality
neuroimaging data. The uncertainty surrounding this adaptation stems from the
lack of representative datasets, leaving top-performing models without exposure
to common artifacts found in MRI data throughout Sub-Saharan Africa (SSA). We
replicated a framework that secured the 2nd position in the 2022 BraTS
competition to investigate the impact of dataset composition on model
performance and pursued four distinct approaches through training a model with:
1) BraTS-Africa data only (train_SSA, N=60), 2) BraTS-Adult Glioma data only
(train_GLI, N=1251), 3) both datasets together (train_ALL, N=1311), and 4)
through further training the train_GLI model with BraTS-Africa data
(train_ftSSA). Notably, training on a smaller low-quality dataset alone
(train_SSA) yielded subpar results, and training on a larger high-quality
dataset alone (train_GLI) struggled to delineate oedematous tissue in the
low-quality validation set. The most promising approach (train_ftSSA) involved
pre-training a model on high-quality neuroimages and then fine-tuning it on the
smaller, low-quality dataset. This approach outperformed the others, ranking
second in the MICCAI BraTS Africa global challenge external testing phase.
These findings underscore the significance of larger sample sizes and broad
exposure to data in improving segmentation performance. Furthermore, we
demonstrated that there is potential for improving such models by fine-tuning
them with a wider range of data locally.Comment: 14 pages, 5 figures, 3 table
Exome-wide association study of pancreatic cancer risk
We conducted a case-control exome-wide association study to discover germline variants in coding regions that affect risk for pancreatic cancer, combining data from 5 studies. We analyzed exome and genome sequencing data from 437 patients with pancreatic cancer (cases) and 1922 individuals not known to have cancer (controls). In the primary analysis, BRCA2 had the strongest enrichment for rare inactivating variants (17/437 cases vs 3/1922 controls) (P=3.27x10(-6); exome-wide statistical significance threshold P<2.5x10(-6)). Cases had more rare inactivating variants in DNA repair genes than controls, even after excluding 13 genes known to predispose to pancreatic cancer (adjusted odds ratio, 1.35, P=.045). At the suggestive threshold (P<.001), 6 genes were enriched for rare damaging variants (UHMK1, AP1G2, DNTA, CHST6, FGFR3, and EPHA1) and 7 genes had associations with pancreatic cancer risk, based on the sequence-kernel association test. We confirmed variants in BRCA2 as the most common high-penetrant genetic factor associated with pancreatic cancer and we also identified candidate pancreatic cancer genes. Large collaborations and novel approaches are needed to overcome the genetic heterogeneity of pancreatic cancer predisposition
The Mass-Velocity and Position-Velocity Relations in Episodic Outflows
While observational evidence for the episodic nature of young stellar
outflows continues to mount, existing numerical and theoretical models of
molecular outflows assume they are formed by the interaction of a non-episodic
wind from a young stellar object with an ambient cloud. In this Letter we
estimate and discuss the effects of episodicity on the mass-velocity and
position-velocity relations observed in molecular outflows. We explain how many
recent observational results disagree with the predictions of non-episodic
outflow models, and we offer simple explanations for the discrepancies. In
particular, we discuss how an episodic stellar outflow can steepen the
power-law slope of the mass-velocity relation in a molecular outflow. And, we
illustrate how an episodic outflow can produce multiple "Hubble-wedges'' in the
position-velocity distribution of a molecular outflow. With a little more
information than we have now, it may be possible to use the "fossil record"
embedded in a molecular outflow's mass-velocity and position-velocity relations
to reconstruct the history of a young stellar object's mass ejection episodes.Comment: To appear in The Astrophysical Journal Letter
The Episodic, Precessing Giant Molecular Outflow from IRAS 04239+2436 (HH 300)
We present the first set of detailed molecular line maps of the region
associated with the giant Herbig-Haro flow HH 300, from the young star IRAS
04239+2436. Our results indicate that the red lobe of the HH 300 flow is
depositing a fair amount of momentum and kinetic energy over a notable volume
of its host dark cloud. This makes HH 300 a key player in the evolution and
fate of its parent cloud. The redshifted molecular outflow lobe of HH 300 is
1.1 pc long and 0.3 pc wide, and has a very clumpy structure. The density,
velocity, and momentum distributions in the outflow indicate that the observed
clumps arise from the prompt entrainment of ambient gas. Bow shock-shaped
structures are associated with the clumps, and we hypothesize that the shocks
are produced by different mass ejection episodes. Lines drawn from IRAS
04239+2436 to each of these clumps have different orientations on the plane of
the sky, and we conclude that HH 300 is a precessing and episodic outflow. The
observations include a map of the red lobe in the 12CO(2-1) line, with a beam
size of 27'', and more extended maps of the outflow region in the 12CO(1-0) and
13CO(1-0) lines, with 45'' and 47'' beam sizes, respectively. We obtain a steep
power-law mass spectrum for HH 300, which we believe is best explained by the
evolution of the outflow mass kinematics. In addition, our 13CO observations
show that the HH 300 flow has been able to redistribute (in space and velocity)
considerable amounts of its surrounding medium-density gas.Comment: 37 pages, 11 figures Version with embedded full-resolution figures
available at http://www-cfa.harvard.edu/sfgroup/ Accepted by The
Astrophysical Journa
A network approach for managing ecosystem services and improving food and nutrition security on smallholder farms
1. Smallholder farmers are some of the poorest and most food insecure people on Earth. Their high nutritional and economic reliance on home--grown produce makes them particularly vulnerable to environmental stressors such as pollinator loss or climate change which threaten agricultural productivity. Improving smallholder agriculture in a way that is environmentally sustainable and resilient to climate change is a key challenge of the 21st century. 2. Ecological intensification, whereby ecosystem services are managed to increase agricultural productivity, is a promising solution for smallholders. However, smallholder farms are complex socio-ecological systems with a range of social, ecological and environmental factors interacting to influence ecosystem service provisioning. To truly understand the functioning of a smallholder farm and identify the most effective management options to support household food and nutrition security, a holistic, systems-based understanding is required. 3. In this paper, we propose a network approach to understand, visualise and model the complex interactions occurring among wild species, crops and people on smallholder farms. Specifically, we demonstrate how networks may be used to (a) identify wild species with a key role in supporting, delivering or increasing the resilience of an ecosystem service; (b) quantify the value of an ecosystem service in a way that is relevant to the food and nutrition security of smallholders; and (c) understand the social interactions that influence the management of shared ecosystem services. 4. Using a case study based on data from rural Nepal, we demonstrate how this framework can be used to connect wild plants, pollinators and crops to key nutrients consumed by humans. This allows us to quantify the nutritional value of an ecosystem service and identify the wild plants and pollinators involved in its provision, as well as providing a framework to predict the effects of environmental change on human nutrition. 5. Our framework identifies mechanistic links between ecosystem services and the nutrients consumed by smallholder farmers and highlights social factors that may influence the management of these services. Applying this framework to smallholder farms in a range of socio-ecological contexts may provide new, sustainable and equitable solutions to smallholder food and nutrition security.Peer reviewe
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