571 research outputs found
Flight loads analysis of a maneuvering transport aircraft
The paper provides a method applicable for the determination of flight loads for maneuvering aircraft, in which aerodynamic loads are calculated based on doublet lattice method, which contains three primary steps. Firstly, non-dimensional stability and control derivative coefficients are obtained through solving unsteady aerodynamics in subsonic flow based on a doublet lattice technical. These stability and control derivative coefficients are used in second step. Secondly, the simulation of aircraft dynamic maneuvers is completed utilizing fourth order Runge-Kutta method to solve motion equations in different maneuvers to gain response parameters of aircraft due to the motion of control surfaces. Finally, the response results calculated in the second step are introduced to the calculation of aerodynamic loads. Thus, total loads and loads distribution on different components of aircraft are obtained. According to the above method, abrupt pitching maneuvers, rolling maneuvers and yawing maneuvers are investigated respectively
Stability of Abstract Thermoelastic Systems with Cattaneo's Law and Inertial Term
This paper investigates the polynomial stability of solutions to abstract
thermoelastic systems with Cattaneo's law on Hilbert space. The study includes
two cases: one with an inertial term and the other without it. For the case
with an inertial term, we partition the region of parameters for
non-exponential stability into three sub-regions and obtain distinct polynomial
decay rates for each sub-region. Meanwhile, for the case without an inertial
term, we explore two areas and obtain dissimilar polynomial decay rates in
these areas. Moreover, we demonstrate that all the given polynomial decay rates
are sharp. Finally, we give some examples to explain our conclusion.Comment: typos correcte
(1,10-Phenanthroline-κ2 N,N′)(triphenylÂphosphine-κP)silver(I) trifluoroÂmethaneÂsulfonate
The structure of the title complex, [Ag(C12H8N2)(C18H15P)]CF3SO3, is based on a distorted trigonal–planar N2P coordination of the AgI ion, provided by two N atoms of the bidentate phenanthroline ligand and one P atom of the triphenylÂphosphine ligand. The phenanthroline ligand and one phenyl ring of the triphenylÂphosphine ligand almost lie in one plane (maximum deviation = 0.014 Å from the best planes). The crystal structure may be stabilized by an interÂmolecular C—H⋯O hydrogen bond between the phenanthroline ligand and the O atom of the trifluoroÂmethaneÂsulfonate anion
Hepatic bile acids and bile acid-related gene expression in pregnant and lactating rats
Background. Significant physiological changes occur during pregnancy and lactation. Intrahepatic cholestasis of pregnancy (ICP) is a liver disease closely related to disruption of bile acid homeostasis. The objective of this study was to examine the regulation of bile acid synthesis and transport in normal pregnant and lactating rats.Materials and Methods. Livers from timed pregnant SD rats were collected on gestational days (GD) 10, 14 and 19, and postnatal days (PND) 1, 7, 14 and 21. Total bile acids were determined by the enzymatic method, total RNA was isolated and subjected to real time RT-PCR analysis. Liver protein was extracted for western-blot analysis.Results. Under physiological conditions hepatic bile acids were not elevated during pregnancy but increased during lactation in rats. Bile acid synthesis rate-limiting enzyme Cyp7a1 was unchanged on gestational days, but increased on PND14 and 21 at mRNA and protein levels. Expression of Cyp8b1, Cyp27a1 and Cyp7b1 was also higher during lactation. The mRNA levels of small heterodimer partner (SHP) and protein levels of farnesoid X receptor (FXR) were increased during pregnancy and lactation. Bile acid transporters Ntcp, Bsep, Mrp3 and Mrp4 were lower at gestation, but increased during lactation. Hepatic Oatp transporters were decreased during pregnancy and lactation.Conclusion. Hepatic bile acid homeostasis is maintained during normal pregnancy in rats, probably through the FXR-SHP regulation. The expression of bile acid synthesis genes and liver bile acid accumulation were increased during lactation, together with increased expression of bile acid efflux transporter Bsep, Mrp3 and Mrp4
Critical fates induced by the interaction competition in three-dimensional tilted Dirac semimetals
The interplay among Coulomb interaction, electron-phonon coupling, and
phonon-phonon coupling has a significant impact on the low-energy behavior of
three-dimensional type-I tilted Dirac semimetals. To investigate this
phenomenon, we construct an effective theory, calculate one-loop corrections
arising from all these interactions, and establish the coupled energy-dependent
flows of all associated interaction parameters by adopting the renormalization
group approach. Deciphering such coupled evolutions allows us to determine a
series of low-energy critical properties for these materials. At first, we
present the low-energy tendencies of all interaction parameters. The tilting
parameter exhibits distinct tendencies that depend heavily upon the initial
anisotropy of fermion velocities. In comparison, the latter is mainly dominated
by its initial value but is less sensitive to the former. Variations in these
two quantities drive certain interaction parameters toward the strong
anisotropy in the low energy regime, indicating the screened interaction in
specific directions, and others toward an approximate isotropy. Additionally,
we observe that the tendencies of interaction parameters can be qualitatively
clustered into three distinct types of fixed points, accompanied by the
potential instabilities that induce certain interaction-driven phase
transition. Furthermore, approaching these fixed points leads to the critical
behavior of physical quantities, such as the density of states,
compressibility, and specific heat, which exhibit quite different from their
non-interacting counterparts and even deviate slightly from Fermi-liquid
behavior. Our investigation sheds light on the intricate relationship between
different types of interactions in these semimetals and provides useful
insights into their fundamental properties.Comment: 23 pages, 22 figure
A Survey of Self-supervised Learning from Multiple Perspectives: Algorithms, Applications and Future Trends
Deep supervised learning algorithms generally require large numbers of
labeled examples to achieve satisfactory performance. However, collecting and
labeling too many examples can be costly and time-consuming. As a subset of
unsupervised learning, self-supervised learning (SSL) aims to learn useful
features from unlabeled examples without any human-annotated labels. SSL has
recently attracted much attention and many related algorithms have been
developed. However, there are few comprehensive studies that explain the
connections and evolution of different SSL variants. In this paper, we provide
a review of various SSL methods from the perspectives of algorithms,
applications, three main trends, and open questions. First, the motivations of
most SSL algorithms are introduced in detail, and their commonalities and
differences are compared. Second, typical applications of SSL in domains such
as image processing and computer vision (CV), as well as natural language
processing (NLP), are discussed. Finally, the three main trends of SSL and the
open research questions are discussed. A collection of useful materials is
available at https://github.com/guijiejie/SSL
Different Functions of the Insect Soluble and Membrane-Bound Trehalase Genes in Chitin Biosynthesis Revealed by RNA Interference
BACKGROUND: Trehalase, an enzyme that hydrolyzes trehalose to yield two glucose molecules, plays a pivotal role in various physiological processes. In recent years, trehalase proteins have been purified from several insect species and are divided into soluble (Tre-1) and membrane-bound (Tre-2) trehalases. However, no functions of the two trehalases in chitin biosynthesis in insects have yet been reported. PRINCIPAL FINDINGS: The membrane-bound trehalase of Spodoptera exigua (SeTre-2) was characterized in our laboratory previously. In this study, we cloned the soluble trehalase gene (SeTre-1) and investigated the tissue distribution and developmental expression pattern of the two trehalase genes. SeTre-1 was expressed highly in cuticle and Malpighian tubules, while SeTre-2 was expressed in tracheae and fat body. In the midgut, the two trehalase genes were expressed in different locations. Additionally, the expression profiles of both trehalase mRNAs and their enzyme activities suggest that they may play different roles in chitin biosynthesis. The RNA interference (RNAi) of either SeTre-1 or SeTre-2 was gene-specific and effective, with efficiency rates up to 83% at 72 h post injection. After RNAi of SeTre-1 and SeTre-2, significant higher mortality rates were observed during the larva-pupa stage and pupa-adult stage, and the lethal phenotypes were classified and analyzed. Additionally, the change trends of concentration of trehalose and glucose appeared reciprocally in RNAi-mutants. Moreover, knockdown of SeTre-1 gene largely inhibited the expression of chitin synthase gene A (CHSA) and reduced the chitin content in the cuticle to two-thirds relative to the control insects. The chitin synthase gene B (CHSB) expression, however, was inhibited more by the injection of dsRNA for SeTre-2, and the chitin content in the midgut decreased by about 25%. CONCLUSIONS: SeTre-1 plays a major role in CHSA expression and chitin synthesis in the cuticle, and SeTre-2 has an important role in CHSB expression and chitin synthesis in the midgut
Nanotechnology: a promising method for oral cancer detection and diagnosis
Abstract
Oral cancer is a common and aggressive cancer with high morbidity, mortality, and recurrence rate globally. Early detection is of utmost importance for cancer prevention and disease management. Currently, tissue biopsy remains the gold standard for oral cancer diagnosis, but it is invasive, which may cause patient discomfort. The application of traditional noninvasive methods-such as vital staining, exfoliative cytology, and molecular imaging-is limited by insufficient sensitivity and specificity. Thus, there is an urgent need for exploring noninvasive, highly sensitive, and specific diagnostic techniques. Nano detection systems are known as new emerging noninvasive strategies that bring the detection sensitivity of biomarkers to nano-scale. Moreover, compared to current imaging contrast agents, nanoparticles are more biocompatible, easier to synthesize, and able to target specific surface molecules. Nanoparticles generate localized surface plasmon resonances at near-infrared wavelengths, providing higher image contrast and resolution. Therefore, using nano-based techniques can help clinicians to detect and better monitor diseases during different phases of oral malignancy. Here, we review the progress of nanotechnology-based methods in oral cancer detection and diagnosis
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