2,651 research outputs found

    Huperzine A for treatment of cognitive impairment in major depressive disorder: A systematic review of randomized controlled trials

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    Background: Acetylcholinesterase (AChE) inhibitors have been shown to be effective in treating cognitive impairment in animal models and in human subjects with major depressive disorder (MDD). Huperzine A (HupA), a Traditional Chinese Medicine derived from a genus of clubmosses known as Huperzineserrata, is a powerful AChE inhibitor that has been used as an adjunctive treatment for MDD, but no meta-analysis on HupA augmentation for MDD has yet been reported. Aim: Conduct a systematic review and meta-analysis of randomized controlled trials (RCTS) about HupA augmentation in the treatment of MDD to evaluate its efficacy and safety. Methods: Two evaluators independently searched nine English-language and Chinese-language databases, selected relevant studies that met pre-determined inclusion criteria, extracted data about outcome and safety, and conducted quality assessments and data synthesis. Results: Three low-quality RCTs (pooled n=238) from China were identified that compared monotherapy antidepressant treatment for depression versus combined treatment with antidepressants and HupA. Participants in the studies ranged from 16 to 60 years of age. The average duration of adjunctive antidepressant and HupA treatment in the studies was only 6.7 weeks. All three studies were open label and non-blinded, so their overall quality was judged as poor. Meta-analysis of the pooled sample found no significant difference in the improvement in depressive symptoms between the two groups (weighted mean difference: -1.90 (95%CI: -4.23, 0.44), p=0.11). However, the adjunctive HupA group did have significantly greater improvement than the antidepressant only group in cognitive functioning (as assessed by the Wisconsin Card Sorting Test and the Wechsler Memory Scale-Revised) and in quality of life. There was no significant difference in the incidence of adverse drug reactions between groups. Conclusions: The data available on the effectiveness and safety of adjunctive treatment using HupA in patients with MDD who are receiving antidepressants is insufficient to arrive at a definitive conclusion about its efficacy and safety. Pooling of the data from three low-quality RCTs from China found no advantage of adjunctive HupA in the treatment of depressive symptoms, but adjunctive treatment with HupA was associated with a faster resolution of the cognitive symptoms that frequently accompany MDD

    Tropical Cyclones Disrupt the Relationship between Tree Height and Species Diversity: Comment

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    In a recent report on the patterns of tree species richness in eastern and western North America, Marks et al. (2016) claimed to have identified an operational indicator of environmental harshness (maximum tree height) and concluded that environmental stressors that limit tree height also act as ecological filters on species richness. Marks et al. (2017) attributed the positive association between species richness and maximum tree height to both the direct effects of environmental harshness on species richness and the indirect effects of environmental harshness on species richness as mediated by maximum tree height. This finding overlooked the fact that many environmental stressors such as cyclonic disturbance affect tree height and tree species diversity in different directions. In a study of elevational patterns in Taiwan, Chi et al. (2015) reported sharply contrasting relationships between tree species diversity and canopy tree height in sites that were subject to tropical cyclone disturbance vs. those that were not. In the mountains of southeastern China beyond the reach of tropical cyclones, both tree species richness and canopy tree height decreased with increasing elevation (Zheng et al. 2004, Chi et al. 2015), supporting the harshness hypothesis (Marks et al. 2016, 2017). In contrast, in Taiwan, where tropical cyclones occur annually, tree species richness decreased but maximum tree height increased with increasing elevation, the opposite of the predictions of the harshness hypothesis (Fig. 1). We attributed the contrasting elevational patterns and associations between tree diversity and canopy tree height in Taiwan to topographic mediation of tropical cyclone disturbance. The shorter tree stature in lower elevations was attributed to more severe tropical cyclone damage (Chi et al. 2015). Although tropical cyclones limit tree height, tree mortality is very low, possibly a result of both evolutional and ecological responses of these forest ecosystems through the long-term interaction between cyclones and the forest ecosystems (Lin et al. 2011). As an example, multiple category three tropical cyclones on the Saffir-Simpson scale (Simpson and Riehl 1981) caused \u3c2% tree mortality in low-elevation evergreen broadleaf forest in northeastern Taiwan in 1994, a record year of tropical cyclone frequency and intensity (Lin et al. 2011). However, taller trees were selectively killed and defoliation was severe, both of which contributed to the low stature of the forest even though the mean annual temperature (18°C) and precipitation (3800) mm are high (Lin et al. 2011). Cyclone disturbance limits vertical development of trees but does not lead to their elimination. Thus, more tropical cyclone disturbance at lower elevations overrides climatic controls on elevational patterns of tree height but does not change the elevational pattern of tree species richness. We suggest that there is an important difference between actual maximum tree height and potential maximum tree height in the presence of disturbance (e.g., tropical cyclone)

    Fluorine: A new element in protein design

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    Fluorocarbons are quintessentially man‐made molecules, fluorine being all but absent from biology. Perfluorinated molecules exhibit novel physicochemical properties that include extreme chemical inertness, thermal stability, and an unusual propensity for phase segregation. The question we and others have sought to answer is to what extent can these properties be engineered into proteins? Here, we review recent studies in which proteins have been designed that incorporate highly fluorinated analogs of hydrophobic amino acids with the aim of creating proteins with novel chemical and biological properties. Fluorination seems to be a general and effective strategy to enhance the stability of proteins, both soluble and membrane bound, against chemical and thermal denaturation, although retaining structure and biological activity. Most studies have focused on small proteins that can be produced by peptide synthesis as synthesis of large proteins containing specifically fluorinated residues remains challenging. However, the development of various biosynthetic methods for introducing noncanonical amino acids into proteins promises to expand the utility of fluorinated amino acids in protein design.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90596/1/2030_ftp.pd

    Even and odd q-deformed charge coherent states and their nonclassical properties

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    Even and odd q-deformed charge coherent states are constructed, their (over)completeness proved and their generation explored. A DD-algebra realization of the SUq_q(1,1) generators is given in terms of them. They are shown to exhibit SUq_q(1,1) squeezing and two-mode qq-antibunching, but neither one-mode, nor two-mode qq-squeezing.Comment: LaTeX, 23 pages, no figure, minor changes, final version to be published in PL

    Dynamics of nascent mRNA folding and RNA–protein interactions: an alternative TAR RNA structure is involved in the control of HIV-1 mRNA transcription

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    HIV-1 Tat protein regulates transcription elongation by binding to the 59 nt TAR RNA stem–loop structure transcribed from the HIV-1 5′ long terminal repeat (5′-LTR). This established Tat–TAR interaction was used to investigate mRNA folding and RNA–protein interactions during early transcription elongation from the HIV-1 5′-LTR. Employing a new site-specific photo-cross-linking strategy to isolate transcription elongation complexes at early steps of elongation, we found that Tat interacts with HIV-1 transcripts before the formation of full-length TAR (TAR59). Analysis of RNA secondary structure by free energy profiling and ribonuclease digestion indicated that nascent transcripts folded into an alternative TAR RNA structure (TAR31), which requires only 31 nt to form and includes an analogous Tat-binding bulge structure. Functionally, TAR31, similar to TAR59, acts as a transcriptional terminator in vitro, and mRNA expression from TAR31-deficient HIV-1 5′-LTR mutant promoters is significantly decreased. Our results support a role for TAR31 in the control of HIV-1 mRNA transcription and we propose that this structure is important to stabilize the short early transcripts before the transcription complex commits for processive elongation. Overall, this study demonstrates that RNA folding during HIV-1 transcription is dynamic and that as the nascent RNA chain grows during transcription, it folds into a number of conformations that function to regulate gene expression. Finally, our results provide a new experimental strategy for studying mRNA conformation changes during transcription that can be applied to investigate the folding and function of nascent RNA structures transcribed from other promoters

    A Survey of Ocean Simulation and Rendering Techniques in Computer Graphics

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    This paper presents a survey of ocean simulation and rendering methods in computer graphics. To model and animate the ocean's surface, these methods mainly rely on two main approaches: on the one hand, those which approximate ocean dynamics with parametric, spectral or hybrid models and use empirical laws from oceanographic research. We will see that this type of methods essentially allows the simulation of ocean scenes in the deep water domain, without breaking waves. On the other hand, physically-based methods use Navier-Stokes Equations (NSE) to represent breaking waves and more generally ocean surface near the shore. We also describe ocean rendering methods in computer graphics, with a special interest in the simulation of phenomena such as foam and spray, and light's interaction with the ocean surface

    Integration, Launch, and First Results from IDEASSat/INSPIRESat-2 - A 3U CubeSat for Ionospheric Physics and Multi-National Capacity Building

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    The Ionospheric Dynamics and Attitude Subsystem Satellite (IDEASSat) is a 3U CubeSat carrying a Compact Ionospheric Probe (CIP) to detect ionospheric irregularities that can impact the usability and accuracy of global satellite navigation systems (GNSS), as well as satellite and terrestrial over the horizon communications. The spacecraft was developed by National Central University (NCU) in Taiwan, with additional development and operational support from partners in the International Satellite Program in Science and Education (INSPIRE) consortium. The spacecraft system needed to accommodate these mission objectives required three axis attitude control, dual band communications capable of supporting both tracking, telemetry and command (TT&C) and science data downlink, as well as flight software and ground systems capable of supporting the autonomous operation and short contact times inherent to a low Earth orbit mission developed on a limited university budget with funding agency-imposed constraints. As the first spacecraft developed at NCU, lessons learned during the development, integration, and operation of IDEASSat have proven to be crucial to the objective of developing a sustainable small satellite program. IDEASSat was launched successfully on January 24, 2021 aboard the SpaceX Falcon 9 Transporter 1 flight. and successfully began operations, demonstrating power, thermal, and structural margins, as well as validation of uplink and downlink communications functionality, and autonomous operation. A serious anomaly occurred after 22 days on orbit when communication with the spacecraft were abruptly lost. Communication was re-established after 1.5 months for sufficient time to downlink stored flight data, which allowed the cause of the blackout to be identified to a high level of confidence and precision. In this paper, we will report on experiences and anomalies encountered during the final flight model integration and delivery, commissioning, and operations. The agile support from the international amateur radio community and INSPIRE partners were extremely helpful in this process, especially during the initial commissioning phase following launch. It is hoped that the lessons learned reported here will be helpful for other university teams working to develop spaceflight capacity

    Aptamer-Functionalized Nano-Biosensors

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    Nanomaterials have become one of the most interesting sensing materials because of their unique size- and shape-dependent optical properties, high surface energy and surface-to-volume ratio, and tunable surface properties. Aptamers are oligonucleotides that can bind their target ligands with high affinity. The use of nanomaterials that are bioconjugated with aptamers for selective and sensitive detection of analytes such as small molecules, metal ions, proteins, and cells has been demonstrated. This review focuses on recent progress in the development of biosensors by integrating functional aptamers with different types of nanomaterials, including quantum dots, magnetic nanoparticles (NPs), metallic NPs, and carbon nanotubes. Colorimetry, fluorescence, electrochemistry, surface plasmon resonance, surface-enhanced Raman scattering, and magnetic resonance imaging are common detection modes for a broad range of analytes with high sensitivity and selectivity when using aptamer bioconjugated nanomaterials (Apt-NMs). We highlight the important roles that the size and concentration of nanomaterials, the secondary structure and density of aptamers, and the multivalent interactions play in determining the specificity and sensitivity of the nanosensors towards analytes. Advantages and disadvantages of the Apt-NMs for bioapplications are focused

    A Smooth-Turn Mobility Model for Airborne Networks

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    In this article, I introduce a novel airborne network mobility model, called the Smooth Turn Mobility Model, that captures the correlation of acceleration for airborne vehicles across time and spatial coordinates. Effective routing in airborne networks (ANs) relies on suitable mobility models that capture the random movement pattern of airborne vehicles. As airborne vehicles cannot make sharp turns as easily as ground vehicles do, the widely used mobility models for Mobile Ad Hoc Networks such as Random Waypoint and Random Direction models fail. Our model is realistic in capturing the tendency of airborne vehicles toward making straight trajectory and smooth turns with large radius, and whereas is simple enough for tractable connectivity analysis and routing design
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