3,507 research outputs found
Ballistic Missile Warhead Recognition based on Micro-Doppler Frequency
To elucidate the spinning-precession signatures of ballistic warhead, the model of spinning precessionfor ballistic missile warhead is established and the mathematics of micro-Doppler signatures caused by spinning-precession is derived. Then the micro-Doppler features are analysed using high-resolution time-frequencytransform, and the model predictions match the experimental data well. Based on different mass of warheadsand decoys, the feature, which can reflect the mass of the targets, is extracted from the time-frequency plane,proving a new method for recognising warheads and discriminating these from decoys. Finally the validityof the feature extracted in this study is verified by computer simulations even with low signal-to-noise ratio.Defence Science Journal, 2008, 58(6), pp.705-709, DOI:http://dx.doi.org/10.14429/dsj.58.169
End-point Modification of Recombinant Thrombomodulin with Enhanced Stability and Anticoagulant Activity
Thrombomodulin (TM) is an endothelial cell membrane protein that plays essential roles in controlling vascular haemostatic balance. The 4, 5, 6 EGF-like domain of TM (TM456) has cofactor activity for thrombin binding and subsequently protein C activation. Therefore, recombinant TM456 is a promising anticoagulant candidate but has a very short half-life. Ligation of poly (ethylene glycol) to a bioactive protein (PEGylation) is a practical choice to improve stability, extend circulating life, and reduce immunogenicity of the protein. Site-specific PEGylation is preferred as it could avoid the loss of protein activity resulting from nonspecific modification. We report herein two site-specific PEGylation strategies, enzymatic ligation and copper-free click chemistry (CFCC), for rTM456 modification. Recombinant TM456 with a C-terminal LPETG tag (rTM456-LPETG) was expressed in Escherichia coli for its end-point modification with NH2-diglycine-PEG5000-OMe via Sortase A-mediated ligation (SML). Similarly, an azide functionality was easily introduced at the C-terminus of rTM456-LPETG via SML with NH2-diglycine-PEG3-azide, which facilitates a site-specific PEGylation of rTM456 via CFCC. Both PEGylated rTM456 conjugates retained protein C activation activity as that of rTM456. Also, they were more stable than rTM456 in Trypsin digestion assay. Further, both PEGylated rTM456 conjugates showed a concentration-dependent prolongation of thrombin clotting time (TCT) compared to non-modified protein, which confirms the effectiveness of these two site-specific PEGylation schemes
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Transversus abdominis plane block reduces remifentanil and propofol consumption, evaluated by closed-loop titration guided by bispectral index.
The present prospective, randomized, double-blind study aimed to determine the impact of transversus abdominis plane (TAP) block on propofol and remifentanil consumption, when administered by closed-loop titration guided by processed electroencephalography, i.e., bispectral index (BIS) values. Following institutional review board approval, 60 patients were scheduled for laparoscopic colectomy under general anesthesia. Patients were randomly assigned to receive bilateral TAP block with 20 ml 0.375% ropivacaine (TAP group) or 20 ml 0.9% saline [control (CON) group]. General anesthesia was maintained with propofol and remifentanil administration using closed-loop titration guided by BIS values. The primary outcome was perioperative propofol and remifentanil consumption. The secondary outcomes were hypertensive or hypotensive events requiring treatment, recovery time in PACU and time to first rescue analgesia following surgery. A total of 58 patients participated in the present study. At similar depths of anesthesia, as measured by BIS during the maintenance phase (45-55), patients who received TAP blocks required less propofol (4.2±1.3 vs. 5.5±1.6 mg/kg/h; P<0.001) and remifentanil (0.16±0.05 vs. 0.21±0.05 µg/kg/min; P<0.001). Time to extubation was significantly shorter in the TAP group (9.8±3.2 min) than in the CON group (14.2±4.9 min) (P<0.05). The requirement to treat hemodynamic change was also significantly lower (P<0.05). Pain score at 2 h after surgery was also significantly reduced in the TAP group compared with the CON group (P<0.05), whereas the time to first rescue analgesia was delayed in patients who received TAP block (P<0.05). Postoperative nausea and vomiting occurred at comparable rates in each group (P>0.05). In conclusion, TAP block combined with general anesthesia reduced propofol and remifentanil consumption, shortened time to tracheal extubation and promoted hemodynamic stability in laparoscopic colectomy
Topological triply-degenerate point with double Fermi arcs
Unconventional chiral particles have recently been predicted to appear in
certain three dimensional (3D) crystal structures containing three- or
more-fold linear band degeneracy points (BDPs). These BDPs carry topological
charges, but are distinct from the standard twofold Weyl points or fourfold
Dirac points, and cannot be described in terms of an emergent relativistic
field theory. Here, we report on the experimental observation of a topological
threefold BDP in a 3D phononic crystal. Using direct acoustic field mapping, we
demonstrate the existence of the threefold BDP in the bulk bandstructure, as
well as doubled Fermi arcs of surface states consistent with a topological
charge of 2. Another novel BDP, similar to a Dirac point but carrying nonzero
topological charge, is connected to the threefold BDP via the doubled Fermi
arcs. These findings pave the way to using these unconventional particles for
exploring new emergent physical phenomena
Exercise intervention to reduce mobile phone addiction in adolescents: a systematic review and meta-analysis of randomized controlled trials
BackgroundThe growing problem of adolescent mobile phone addiction has attracted significant attention, underscoring the importance of identifying approaches to address it. Exercise has been found to reduce adolescent mobile phone addiction; however, its mechanism remains unclear. This review aims to elucidate the potential moderating factors between exercise and mobile phone addiction based on previous studies to provide a reference for adolescents to effectively participate in exercise to reduce mobile phone addiction.MethodsArticles were searched in the CNKI, Web of Science, Scopus, Cochrane, PsycINFO, and PubMed databases according to the inclusion criteria and followed the Preferred Reporting Items for Systematic Assessment and Meta-analysis (PRISMA). The quality of the literature was assessed by two independent reviewers using the Cochrane Collaboration Risk of Bias tool for methodological quality assessment. Meta-analysis was performed using Stata 15.1 software for Meta-analysis, standardized mean difference (SMD) was combined using a random effects model, and subgroup analysis was used to explore heterogeneity.ResultsA total of 12 studies, 17 samples, and 861 subjects were included in the meta-analysis, and all studies were randomized controlled trials. The findings revealed that the exercise intervention significantly reduced mobile phone addiction in adolescents (SMD = −3.11; 95% CI: −3.91, −2.30; p < 0.001). The intervention effect was moderated by multiple variables, such as the measurement tools, exercise intervention types, cycles, frequency, and duration of a single exercise intervention.ConclusionOur findings suggest that exercise could serve as an effective strategy for preventing or ameliorating mobile phone addiction in adolescents. Based on the results of this study, we encourage mobile phone-addicted adolescents to engage in a single exercise using a mix of skills for 30–60 min three or more times weekly for more than eight consecutive weeks
Crossover between Weak Antilocalization and Weak Localization of Bulk States in Ultrathin Bi2Se3 Films
We report transport studies on the 5 nm thick Bi2Se3 topological insulator
films which are grown via molecular beam epitaxy technique. The angle-resolved
photoemission spectroscopy data show that the Fermi level of the system lies in
the bulk conduction band above the Dirac point, suggesting important
contribution of bulk states to the transport results. In particular, the
crossover from weak antilocalization to weak localization in the bulk states is
observed in the parallel magnetic field measurements up to 50 Tesla. The
measured magneto-resistance exhibits interesting anisotropy with respect to the
orientation of B// and I, signifying intrinsic spin-orbit coupling in the
Bi2Se3 films. Our work directly shows the crossover of quantum interference
effect in the bulk states from weak antilocalization to weak localization. It
presents an important step toward a better understanding of the existing
three-dimensional topological insulators and the potential applications of
nano-scale topological insulator devices
Retentive Network: A Successor to Transformer for Large Language Models
In this work, we propose Retentive Network (RetNet) as a foundation
architecture for large language models, simultaneously achieving training
parallelism, low-cost inference, and good performance. We theoretically derive
the connection between recurrence and attention. Then we propose the retention
mechanism for sequence modeling, which supports three computation paradigms,
i.e., parallel, recurrent, and chunkwise recurrent. Specifically, the parallel
representation allows for training parallelism. The recurrent representation
enables low-cost inference, which improves decoding throughput, latency,
and GPU memory without sacrificing performance. The chunkwise recurrent
representation facilitates efficient long-sequence modeling with linear
complexity, where each chunk is encoded parallelly while recurrently
summarizing the chunks. Experimental results on language modeling show that
RetNet achieves favorable scaling results, parallel training, low-cost
deployment, and efficient inference. The intriguing properties make RetNet a
strong successor to Transformer for large language models. Code will be
available at https://aka.ms/retnet
Effect of Lycii fructus polysaccharides on ovulation failure in rats
Purpose: To investigate the effect of Lycii Fructus polysaccharides (LFPS) on ovulation failure.Methods: A rat model of ovulation failure was established by intragastric administration of hydroxyurea (300 mg/kg). Rats with ovulation failure then received LFPS via oral administration at doses of 100, 200, or 400 mg/kg. The body, uterus and ovary of each rat were weighed using electronic scales. The hypothalamic-pituitary-ovarian (HPO) axis hormones, including estradiol (E2) level, follicle-stimulating hormone (FSH) activity, and luteinizing hormone (LH) activity in the serum of each rat were determined by enzyme-linked immunosorbent assay (ELISA). The levels of pro-apoptotic proteins (Fas, FasL, FADD, c-caspase-8, c-caspase-10, c-caspase-3, c-caspase-6, and c-caspase-7) in the ovarian tissue of each rat were detected by western blot.Results: Hydroxyurea reduced significantly (p < 0.01) uterus and ovary indices (uterus or ovary weight/body weight) (0.119 and 0.026 %), E2 level (3.42 pmol/L), and FSH and LH activities (2.28 and 2.76 U/L), compared with those in the normal group (0.169 and 0.039 %; 6.72 pmol/L; 2.76 and 3.75 U/L). Hydroxyurea increased significantly (p < 0.01) the levels of the above-mentioned pro-apoptotic proteins relative to those in the normal group. LFPS (100, 200, or 400 mg/kg) reversed significantly (p < 0.05 or 0.01) the effect of hydroxyurea on all of the above indices.Conclusion: LFPS exhibits a protective effect on hydroxyurea-induced ovulation failure by regulating the HPO axis hormones and death receptor-mediated apoptotic pathway.Keywords: Lycii Fructus polysaccharides, Ovulation failure, Hypothalamic-pituitary-ovarian axis, Death receptor-mediated apoptotic pathwa
Transcriptional regulation of PEN-2, a key component of the γ-secretase complex, by CREB
Gamma-secretase, which is responsible for the intramembranous cleavage of Alzheimer's P-amyloid precursor protein (APP), the signaling receptor Notch, and many other substrates, is a multiprotein complex consisting of at least four components: presenilin (PS), nicastrin, APH-1, and PEN-2. Despite the fact that PEN-2 is known to mediate endoproteolytic cleavage of full-length PS and APH-1 and nicastrin are required for maintaining the stability of the complex, the detailed physiological function of each component remain elusive. Unlike that of PS, the transcriptional regulation of PEN-2, APH-1, and nicastrin has not been investigated. Here, we characterized the upstream regions of the human PEN-2 gene and identified a 238-bp fragment located 353 bp upstream of the translational start codon as the key region necessary for the promoter activity. Further analysis revealed a CREB binding site located in the 238-bp region that is essential for the transcriptional activity of the PEN-2 promoter. Mutation of the CREB site abolished the transcriptional activity of the PEN-2 promoter. Electrophoretic mobility shift assays and chromatin immunoprecipitation analysis showed the binding of CREB to the PEN-2 promoter region both in vitro and in vivo. Activation of the CREB transcriptional factor by forskolin dramatically promoted the expression of PEN-2 mRNA and protein, whereas the other components of the gamma-secretase complex remained unaffected. Forskolin treatment slightly increases the secretion of soluble APP alpha and A beta without affecting Notch cleavage. These results demonstrate that expression of PEN-2 is regulated by CREB and suggest that the specific control of PEN-2 expression may imply additional physiological functions uniquely assigned to PEN-2
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