159 research outputs found
High Speed Mid-Wave Infrared Uni-traveling Carrier Photodetector
Mid-wave infrared (MWIR) frequency comb is expected to dramatically improve
the precision and sensitivity of molecular spectroscopy. For high resolution
application, high speed MWIR photodetector is one of the key components,
however, the commercially available high speed MWIR photodetector only has
sub-GHz bandwidth currently. In this paper, we demonstrate, for the first time
to our knowledge, a high speed mid-wave infrared (MWIR) uni-traveling carrier
photodetector based on InAs/GaSb type-II superlattice (T2SL) at room
temperature. The device exhibits a cutoff wavelength of 5.6{\mu}m, and 3dB
bandwidth of 6.58 GHz for a 20{\mu}m diameter device at 300K. These promising
results show the device has potential to be utilized in high speed applications
such as frequency comb spectroscopy, free space communication and others. The
limitations on the high frequency performance of the photodetectors are also
discussed
Toward Controllable and Robust Surface Reconstruction from Spatial Curves
Reconstructing surface from a set of spatial curves is a fundamental problem in computer graphics and computational geometry. It often arises in many applications across various disciplines, such as industrial prototyping, artistic design and biomedical imaging. While the problem has been widely studied for years, challenges remain for handling different type of curve inputs while satisfying various constraints. We study studied three related computational tasks in this thesis. First, we propose an algorithm for reconstructing multi-labeled material interfaces from cross-sectional curves that allows for explicit topology control. Second, we addressed the consistency restoration, a critical but overlooked problem in applying algorithms of surface reconstruction to real-world cross-sections data. Lastly, we propose the Variational Implicit Point Set Surface which allows us to robustly handle noisy, sparse and non-uniform inputs, such as samples from spatial curves
Effects of icariin and quercetin on high glucose-induced neuronal cell apoptosis
Purpose: To study the effects of icariin and quercetin on cell apoptotic changes in neurons induced by elevated glucose condition, and the mechanism involved.
Methods: Neonatal male Sprague Dawley rats (n = 48) weighing 5 – 7 g were used. Neuronal cells were isolated from rat hippocampus and cultured after purification. The cells were randomly assigned to six groups: control, high glucose, icariin, quercetin, serine/threonine-specific protein kinase (Akt) inhibitor, and Akt agonist groups. The Akt inhibitor and agonist used in this study were MK-22062hci and SC79, respectively. The influence of icariin and quercetin on neuronal apoptotic changes were determined flow cytometrically, while their effects on levels of expression of Akt, p-Akt, bax and bcl-2 were determined with Western blotting.
Results: Treatment with icariin or quercetin significantly inhibited apoptosis induced by high glucose. The concentrations of Akt, p-Akt, and bcl-2 proteins were markedly upregulated in high glucose group, relative to control (p < 0.05). The corresponding expression of bax was significantly down-regulated in high glucose group, relative to control (p < 0.05). Treatment with icariin or quercetin, or their agonists reversed high glucose-mediated alterations in these protein levels (p < 0.05).
Conclusion: Icariin and quercetin inhibit neuronal cell apoptosis induced by high glucose through upregulation of bcl-2 expression and down- regulations of bax expression and Akt-induced protein phosphorylation. Thus, Icariin and quercetin possess potential benefits for the treatment of neurological diseases.
Keywords: Apoptosis, High glucose condition, Hippocampal neurons, Icariin, Querceti
The Art of SOCRATIC QUESTIONING: Zero-shot Multimodal Reasoning with Recursive Thinking and Self-Questioning
Chain-of-Thought prompting (CoT) enables large-scale language models to solve
complex reasoning problems by decomposing the problem and tackling it
step-by-step. However, Chain-of-Thought is a greedy thinking process that
requires the language model to come up with a starting point and generate the
next step solely based on previous steps. This thinking process is different
from how humans approach a complex problem e.g., we proactively raise
sub-problems related to the original problem and recursively answer them. In
this work, we propose Socratic Questioning, a divide-and-conquer fashion
algorithm that simulates the self-questioning and recursive thinking process.
Socratic Questioning is driven by a Self-Questioning module that employs a
large-scale language model to propose sub-problems related to the original
problem as intermediate steps and Socratic Questioning recursively backtracks
and answers the sub-problems until reaches the original problem. We apply our
proposed algorithm to the visual question-answering task as a case study and by
evaluating it on three public benchmark datasets, we observe a significant
performance improvement over all baselines on (almost) all datasets. In
addition, the qualitative analysis clearly demonstrates the intermediate
thinking steps elicited by Socratic Questioning are similar to the human's
recursively thinking process of a complex reasoning problem.Comment: 15 pages, 12 figure, 2 algorithm
X-Eval: Generalizable Multi-aspect Text Evaluation via Augmented Instruction Tuning with Auxiliary Evaluation Aspects
Natural Language Generation (NLG) typically involves evaluating the generated
text in various aspects (e.g., consistency and naturalness) to obtain a
comprehensive assessment. However, multi-aspect evaluation remains challenging
as it may require the evaluator to generalize to any given evaluation aspect
even if it's absent during training. In this paper, we introduce X-Eval, a
two-stage instruction tuning framework to evaluate the text in both seen and
unseen aspects customized by end users. X-Eval consists of two learning stages:
the vanilla instruction tuning stage that improves the model's ability to
follow evaluation instructions, and an enhanced instruction tuning stage that
exploits the connections between fine-grained evaluation aspects to better
assess text quality. To support the training of X-Eval, we collect
AspectInstruct, the first instruction tuning dataset tailored for multi-aspect
NLG evaluation spanning 27 diverse evaluation aspects with 65 tasks. To enhance
task diversity, we devise an augmentation strategy that converts human rating
annotations into diverse forms of NLG evaluation tasks, including scoring,
comparison, ranking, and Boolean question answering. Extensive experiments
across three essential categories of NLG tasks: dialogue generation,
summarization, and data-to-text coupled with 21 aspects in meta-evaluation,
demonstrate that our X-Eval enables even a lightweight language model to
achieve a comparable if not higher correlation with human judgments compared to
the state-of-the-art NLG evaluators, such as GPT-4.Comment: 17 pages, 5 figures, 14 table
Microstructure characterization of ion-irradiated nano-grained Ni-Mo-Cr alloy using diffraction line profile analysis
Abstract:
Ni-Mo-Cr alloys were developed for molten-salt reactors and are expected to withstand the
radiation damage above 10 dpa. It is well-known that that having a nano-grained
microstructure could improve the radiation damage tolerance of structural alloys and thus
extend operational lifetime of novel reactor systems. The defect evolution of the nanograined Ni-Mo-Cr alloy was investigated under Au-ion irradiation with a dose of 15 and 30
dpa at room temperature. High-resolution X-ray diffraction patterns were collected at the
33BM beamline of the Advanced Photon Source (APS) and analysed using the Convolutional
Multiple Whole Profile (CMWP) method with the option to interpret the diffuse scattering in
the vicinity of Bragg reflections. Results show that both the average sub-grain size and twin
boundaries spacing significantly increased, whereas the initial high dislocation density
decreased after the irradiation. The interpretation of diffuse scattering indicates that most
irradiation defects are small and vacancy in nature
A retrospective study on the physical growth of twins in the first year after birth
ObjectivesThis study analyzed the physical growth of small for gestational age (SGA) and appropriate for gestational age (AGA) twins up to one year after birth.MethodsWeight, length, and head circumference data of 0–1 year-old twins were collected from the Child Health Care System from 2010 to 2019. Physical data were presented as Z-scores. Five parameters – growth level of weight, body length, head circumference, growth velocity, and body proportion (weight for length) were compared in twins.ResultsA total of 3,909 cases were collected (22.61% SGA, 77.39% AGA). 1. In both groups, WAZ (Weight for age z-score), HCZ (Head circumference for age z-score), and LAZ (Length for age z-score) increased more rapidly in the first 6 months. By one year of age, WAZ, HCZ, and LAZ had reached the normal range, but none had reached the average level of normal singleton children. 2. The mean values of WAZ, HCZ, and LAZ in the AGA group were between −1 and 0, and between −2 and − 1 in the SGA group, in the first year after birth. The SGA group lagged significantly behind the AGA group. The LAZ score of SGA and AGA was lower than the WAZ and HCZ scores. 3. The proportion of preterm AGA was the largest in twins, and the growth rate of preterm AGA was the fastest. Preterm twins had greater growth potential than term twins. However, the growth level of preterm SGA was always low. 4. The WFLZ (Weight for length z-score) in each group was approximately close to 0. The WFLZ of SGA was smaller than that of AGA twins at most time points. After 4 months of age, the WFLZ of twins had a downward trend. The WFLZ of preterm SGA approached −1 at approximately 1 year old.ConclusionThe physical growth of SGA and AGA in twins in the first year can reach the normal range but cannot reach the average level of normal singleton children. More attention should be paid to SGA in twins, especially preterm SGA. We should give proper nutritional guidance after 4 months of age to ensure the appropriate body proportion (weight for length) of SGA in twins.Clinical trial registrationwww.chictr.org.cn, CTR2000034761
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