1,623 research outputs found
Botanical, Pharmacological, Phytochemical, and Toxicological Aspects of the Antidiabetic PlantBidens pilosaL
Bidens pilosa L. is an easy-to-grow, widespread, and palatable perennial on earth. Hence, it has traditionally been used as foods and medicines without noticeable adverse effects. Despite significant advancement in chemical and biological studies of B. pilosa over the past few years, comprehensive and critical reviews on its anti-diabetic properties are missing. The present review is to summarize up-to-date information on the pharmacology, phytochemistry, and toxicology of B. pilosa, in regard to type 1 diabetes and type 2 diabetes from the literature. In addition to botanical studies and records of the traditional use of B. pilosa in diabetes, scientific studies investigating antidiabetic action of this species and its active phytochemicals are presented and discussed. The structure and biosynthesis of B. pilosa and its polyynes in relation to their anti-diabetic action and mechanism are emphasized. Although some progress has been made, rigorous efforts are further required to unlock the molecular basis and structure-activity relationship of the polyynes isolated from B. pilosa before their clinical applications. The present review provides preliminary information and gives guidance for further anti-diabetic research and development of this plant
Pilotsâ visual scan pattern and situation awareness in flight operations
Introduction: Situation awareness (SA) is considered an essential prerequisite for safe flying. If the impact of visual scanning patterns on a pilotâs situation awareness could be identified in flight operations, then eye-tracking tools could be integrated with flight simulators to improve training efficiency. Method: Participating in this research were 18 qualified, mission-ready fighter pilots. The equipment included high-fidelity and fixed-base type flight simulators and mobile head-mounted eye-tracking devices to record a subjectâs eye movements and SA while performing air-to-surface tasks. Results: There were significant differences in pilotsâ percentage of fixation in three operating phases: preparation (M = 46.09, SD = 14.79), aiming (M = 24.24, SD = 11.03), and release and break-away (M = 33.98, SD = 14.46). Also, there were significant differences in pilotsâ pupil sizes, which were largest in the aiming phase (M = 27,621, SD = 6390.8), followed by release and break-away (M = 27,173, SD = 5830.46), then preparation (M = 25,710, SD = 6078.79), which was the smallest. Furthermore, pilots with better SA performance showed lower perceived workload (M = 30.60, SD = 17.86), and pilots with poor SA performance showed higher perceived workload (M = 60.77, SD = 12.72). Pilotsâ percentage of fixation and average fixation duration among five different areas of interest showed significant differences as well. Discussion: Eye-tracking devices can aid in capturing pilotsâ visual scan patterns and SA performance, unlike traditional flight simulators. Therefore, integrating eye-tracking devices into the simulator may be a useful method for promoting SA training in flight operations, and can provide in-depth understanding of the mechanism of visual scan patterns and information processing to improve training effectiveness in aviation
Pilotsâ visual scan pattern and attention distribution during the pursuit of a dynamic target
Introduction: The current research is investigating pilotsâ visual
scan patterns in order to assess attention distribution during
air-to-air manoeuvers. Method: A total of thirty qualified
mission-ready fighter pilots participated in this research. Eye
movement data were collected by a portable head-mounted eye-tracking
device, combined with a jet fighter simulator. To complete the task,
pilots have to search for, pursue, and lock-on a moving target whilst
performing air-to-air tasks. Results: There were significant
differences in pilotsâ saccade duration (msec) in three operating
phases including searching (M=241, SD=332), pursuing (M=311, SD=392),
and lock-on (M=191, SD=226). Also, there were significant differences
in pilotsâ pupil sizes (pixel2) of which lock-on phase was the largest
(M=27237, SD=6457), followed by pursuing (M=26232, SD=6070), then
searching (M=25858, SD=6137). Furthermore, there were significant
differences between expert and novice pilots on the percentage of
fixation on the HUD, time spent looking outside the cockpit, and the
performance of situational awareness (SA). Discussion: Experienced
pilots have better SA performance and paid more attention to the HUD
but focused less outside the cockpit when compared with novice pilots.
Furthermore, pilots with better SA performance exhibited a smaller
pupil size during the operational phase of lock-on whilst pursuing
a dynamic target. Understanding pilotsâ visual scan patterns and
attention distribution are beneficial to the design of interface
displays in the cockpit and in developing human factors training
syllabi to improve safety of flight operations
Text difficulty in extensive reading: Reading comprehension and reading motivation
This study investigates the effects of the text difficulty of extensive reading materials on the reading comprehension and reading motivation of English as a foreign language (EFL) vocational high school students in Taiwan. Two experimental groups were assigned, on an individual basis, to read graded readers at either one level below (âi-1â) or one level beyond (âi+1â) their current level, while a control group followed their regular curriculum. The results showed that after treatment, the âi-1â group improved their overall comprehension and the subset of literal comprehension. They also outperformed the âi+1â group on the same measures. For reading motivation, the âi+1â groupâs overall motivation was promoted. Both groups enhanced their reading engagement, while only the âi-1â group inhibited reading avoidance. Moreover, the âi+1â group outperformed the âi-1â group in the perception of self-efficacy. Overall, the âi-1â level yielded better effects on reading comprehension; the âi+1â level, on reading motivation
An Empirical Study on Consumption Intention of Virtual Tour Streaming
This study employs the social interaction motivation of the audience to explore the social capital dual-model relationship generated by the audience of âVirtual Tour Streaming,â a term that describes virtual tour streamingâs nascent digital economy. This is situated in a virtual tour streaming platform to ascertain how it influences the intention of the audience and to use âSwift Guanxiâ as the interaction variable to actual intention behavior. This is done to understand the contributions of virtual tour streaming adoption in a direct dial platform of different audience levels and their consumption behavior. The remaining sections discuss the theoretical and practical implications of the study
Thermal instability in spherical liquid shells induced by surface tension
A linear perturbation method is employed to determine the condition for neutral stability in spherical liquid shells induced by surface tension mechanism. Three possible boundary conditions are considered: at least one boundary free or both. The critical Marangoni numbers for the onset of cellular convections are found for two types of steady radial temperature distributions in the spherical shells. Results are compared with those induced by buoyancy mechnism. It is concluded that surface tension forces are much more effective than buoyancy forces in producing thermal instability and a parabolic steady temperature distribution is more susceptible than a linear one to thermal disturbances due to surface tension forces. Heat transfer between a free surface and the ambient promotes thermal stability in liquid shells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23157/1/0000082.pd
Multiple Events of Allopolyploidy in the Evolution of the Racemose Lineages in Prunus (Rosaceae) Based on Integrated Evidence from Nuclear and Plastid Data.
Prunus is an economically important genus well-known for cherries, plums, almonds, and peaches. The genus can be divided into three major groups based on inflorescence structure and ploidy levels: (1) the diploid solitary-flower group (subg. Prunus, Amygdalus and Emplectocladus); (2) the diploid corymbose group (subg. Cerasus); and (3) the polyploid racemose group (subg. Padus, subg. Laurocerasus, and the Maddenia group). The plastid phylogeny suggests three major clades within Prunus: Prunus-Amygdalus-Emplectocladus, Cerasus, and Laurocerasus-Padus-Maddenia, while nuclear ITS trees resolve Laurocerasus-Padus-Maddenia as a paraphyletic group. In this study, we employed sequences of the nuclear loci At103, ITS and s6pdh to explore the origins and evolution of the racemose group. Two copies of the At103 gene were identified in Prunus. One copy is found in Prunus species with solitary and corymbose inflorescences as well as those with racemose inflorescences, while the second copy (II) is present only in taxa with racemose inflorescences. The copy I sequences suggest that all racemose species form a paraphyletic group composed of four clades, each of which is definable by morphology and geography. The tree from the combined At103 and ITS sequences and the tree based on the single gene s6pdh had similar general topologies to the tree based on the copy I sequences of At103, with the combined At103-ITS tree showing stronger support in most clades. The nuclear At103, ITS and s6pdh data in conjunction with the plastid data are consistent with the hypothesis that multiple independent allopolyploidy events contributed to the origins of the racemose group. A widespread species or lineage may have served as the maternal parent for multiple hybridizations involving several paternal lineages. This hypothesis of the complex evolutionary history of the racemose group in Prunus reflects a major step forward in our understanding of diversification of the genus and has important implications for the interpretation of its phylogeny, evolution, and classification
Test-time Defense against Adversarial Attacks: Detection and Reconstruction of Adversarial Examples via Masked Autoencoder
Existing defense methods against adversarial attacks can be categorized into
training time and test time defenses. Training time defense, i.e., adversarial
training, requires a significant amount of extra time for training and is often
not able to be generalized to unseen attacks. On the other hand, test time
defense by test time weight adaptation requires access to perform gradient
descent on (part of) the model weights, which could be infeasible for models
with frozen weights. To address these challenges, we propose DRAM, a novel
defense method to Detect and Reconstruct multiple types of Adversarial attacks
via Masked autoencoder (MAE). We demonstrate how to use MAE losses to build a
KS-test to detect adversarial attacks. Moreover, the MAE losses can be used to
repair adversarial samples from unseen attack types. In this sense, DRAM
neither requires model weight updates in test time nor augments the training
set with more adversarial samples. Evaluating DRAM on the large-scale ImageNet
data, we achieve the best detection rate of 82% on average on eight types of
adversarial attacks compared with other detection baselines. For
reconstruction, DRAM improves the robust accuracy by 6% ~ 41% for Standard
ResNet50 and 3% ~ 8% for Robust ResNet50 compared with other self-supervision
tasks, such as rotation prediction and contrastive learning
Reduction in magnetic coercivity of Co nanomagnets by Fe alloying
We measured the magnetic hysteresis and coercivity of individual Co and CoFe bilayer nano-sized island structures formed on Cu (111) substrate using spin-polarized scanning tunneling microscopy. From the hysteresis taken on various sizes of islands, we found that the alloyed islands are ferromagnetic with out-of-plane magnetic anisotropy, same as the pure islands. Coercivity of the alloy islands, which is dependent on their size, was significantly reduced to â40% of that of the pure islands. Based on the StonerâWohlfarth model, we evaluated the amount of magnetic anisotropic energy and anisotropy constant for both pure and alloy islands. Since tunneling spectra taken on the alloy islands show upward shifts of the valence electronic states as compared to the pure ones, fewer electrons populated in the valence band of the alloy islands are presumably responsible for the reduction in the magnetic anisotropic energy
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