4,082 research outputs found
The Representation of Immigrants in Federal, State and Local Government Work Forces
Public sector employment of immigrants can increase their economic assimilation and potentially improve their treatment by government. Yet, as we show using Census data from 1990, 2000, and 2009-11, immigrants are substantially under-represented in federal, state, and local governments. To understand why, we use logit analysis for federal and for state and local government employment in each time period to test whether immigrants’ weaker educational attainment and English proficiency, lower probabilities of being citizens and military veterans, and different age, gender, and race/ethnicity distributions can explain that under-representation. Disparities in education and preferential government treatment of veterans are factors, but citizenship requirements appear to be the major obstacle to immigrant employment in the public sector
Quantitative analysis of B-lymphocyte migration directed by CXCL13
B-lymphocyte migration, directed by chemokine gradients, is essential for homing to sites of antigen presentation
Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2
We demonstrate the continuous and reversible tuning of the optical band gap
of suspended monolayer MoS2 membranes by as much as 500 meV by applying very
large biaxial strains. By using chemical vapor deposition (CVD) to grow
crystals that are highly impermeable to gas, we are able to apply a pressure
difference across suspended membranes to induce biaxial strains. We observe the
effect of strain on the energy and intensity of the peaks in the
photoluminescence (PL) spectrum, and find a linear tuning rate of the optical
band gap of 99 meV/%. This method is then used to study the PL spectra of
bilayer and trilayer devices under strain, and to find the shift rates and
Gr\"uneisen parameters of two Raman modes in monolayer MoS2. Finally, we use
this result to show that we can apply biaxial strains as large as 5.6% across
micron sized areas, and report evidence for the strain tuning of higher level
optical transitions.Comment: Nano Lett., Article ASA
Bayesian Nested Neural Networks for Uncertainty Calibration and Adaptive Compression
Nested networks or slimmable networks are neural networks whose architectures
can be adjusted instantly during testing time, e.g., based on computational
constraints. Recent studies have focused on a "nested dropout" layer, which is
able to order the nodes of a layer by importance during training, thus
generating a nested set of sub-networks that are optimal for different
configurations of resources. However, the dropout rate is fixed as a
hyper-parameter over different layers during the whole training process.
Therefore, when nodes are removed, the performance decays in a human-specified
trajectory rather than in a trajectory learned from data. Another drawback is
the generated sub-networks are deterministic networks without well-calibrated
uncertainty. To address these two problems, we develop a Bayesian approach to
nested neural networks. We propose a variational ordering unit that draws
samples for nested dropout at a low cost, from a proposed Downhill
distribution, which provides useful gradients to the parameters of nested
dropout. Based on this approach, we design a Bayesian nested neural network
that learns the order knowledge of the node distributions. In experiments, we
show that the proposed approach outperforms the nested network in terms of
accuracy, calibration, and out-of-domain detection in classification tasks. It
also outperforms the related approach on uncertainty-critical tasks in computer
vision.Comment: 16 pages, 10 figure
Benchmarking a foundation LLM on its ability to re-label structure names in accordance with the AAPM TG-263 report
Purpose: To introduce the concept of using large language models (LLMs) to
re-label structure names in accordance with the American Association of
Physicists in Medicine (AAPM) Task Group (TG)-263 standard, and to establish a
benchmark for future studies to reference.
Methods and Materials: The Generative Pre-trained Transformer (GPT)-4
application programming interface (API) was implemented as a Digital Imaging
and Communications in Medicine (DICOM) storage server, which upon receiving a
structure set DICOM file, prompts GPT-4 to re-label the structure names of both
target volumes and normal tissues according to the AAPM TG-263. Three disease
sites, prostate, head and neck, and thorax were selected for evaluation. For
each disease site category, 150 patients were randomly selected for manually
tuning the instructions prompt (in batches of 50) and 50 patients were randomly
selected for evaluation. Structure names that were considered were those that
were most likely to be relevant for studies utilizing structure contours for
many patients.
Results: The overall re-labeling accuracy of both target volumes and normal
tissues for prostate, head and neck, and thorax cases was 96.0%, 98.5%, and
96.9% respectively. Re-labeling of target volumes was less accurate on average
except for prostate - 100%, 93.1%, and 91.1% respectively.
Conclusions: Given the accuracy of GPT-4 in re-labeling structure names of
both target volumes and normal tissues as presented in this work, LLMs are
poised to be the preferred method for standardizing structure names in
radiation oncology, especially considering the rapid advancements in LLM
capabilities that are likely to continue.Comment: 20 pages, 5 figures, 1 tabl
A single transcription factor is sufficient to induce and maintain secretory cell architecture
We hypothesized that basic helix–loop–helix (bHLH) MIST1 (BHLHA15) is a “scaling factor” that universally establishes secretory morphology in cells that perform regulated secretion. Here, we show that targeted deletion of MIST1 caused dismantling of the secretory apparatus of diverse exocrine cells. Parietal cells (PCs), whose function is to pump acid into the stomach, normally lack MIST1 and do not perform regulated secretion. Forced expression of MIST1 in PCs caused them to expand their apical cytoplasm, rearrange mitochondrial/lysosome trafficking, and generate large secretory granules. Mist1 induced a cohort of genes regulated by MIST1 in multiple organs but did not affect PC function. MIST1 bound CATATG/CAGCTG E boxes in the first intron of genes that regulate autophagosome/lysosomal degradation, mitochondrial trafficking, and amino acid metabolism. Similar alterations in cell architecture and gene expression were also caused by ectopically inducing MIST1 in vivo in hepatocytes. Thus, MIST1 is a scaling factor necessary and sufficient by itself to induce and maintain secretory cell architecture. Our results indicate that, whereas mature cell types in each organ may have unique developmental origins, cells performing similar physiological functions throughout the body share similar transcription factor-mediated architectural “blueprints.
Evaluating Large Language Models on a Highly-specialized Topic, Radiation Oncology Physics
We present the first study to investigate Large Language Models (LLMs) in
answering radiation oncology physics questions. Because popular exams like AP
Physics, LSAT, and GRE have large test-taker populations and ample test
preparation resources in circulation, they may not allow for accurately
assessing the true potential of LLMs. This paper proposes evaluating LLMs on a
highly-specialized topic, radiation oncology physics, which may be more
pertinent to scientific and medical communities in addition to being a valuable
benchmark of LLMs. We developed an exam consisting of 100 radiation oncology
physics questions based on our expertise at Mayo Clinic. Four LLMs, ChatGPT
(GPT-3.5), ChatGPT (GPT-4), Bard (LaMDA), and BLOOMZ, were evaluated against
medical physicists and non-experts. ChatGPT (GPT-4) outperformed all other LLMs
as well as medical physicists, on average. The performance of ChatGPT (GPT-4)
was further improved when prompted to explain first, then answer. ChatGPT
(GPT-3.5 and GPT-4) showed a high level of consistency in its answer choices
across a number of trials, whether correct or incorrect, a characteristic that
was not observed in the human test groups. In evaluating ChatGPTs (GPT-4)
deductive reasoning ability using a novel approach (substituting the correct
answer with "None of the above choices is the correct answer."), ChatGPT
(GPT-4) demonstrated surprising accuracy, suggesting the potential presence of
an emergent ability. Finally, although ChatGPT (GPT-4) performed well overall,
its intrinsic properties did not allow for further improvement when scoring
based on a majority vote across trials. In contrast, a team of medical
physicists were able to greatly outperform ChatGPT (GPT-4) using a majority
vote. This study suggests a great potential for LLMs to work alongside
radiation oncology experts as highly knowledgeable assistants
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