Effects of sugars and aminooxyacetic acid on the longevity of pollinated Dendrobium (Heang Beauty) flowers

The vase life of detached pollinated Dendrobium (Heang Beauty) orchids are affected by loss of energy source and the production of pollination-induced ethylene. The physiological changes that follow these two events are discoloration, thinning of petals and hyponasty. In order to circumvent this problem, individual detached pollinated Dendrobium (Heang Beauty) fl owers were treated with solutions containing different concentrations of sucrose or glucose, Aminooxyacetic acid (AOA) and a combination of sugars and AOA. Discolouration, petal thickness and hyponasty were observed and data was recorded daily. Weight loss of fl owers and pH of all solutions were also measured daily. Results showed that the best treatment solution in extending the longevity of the fl owers were solutions containing 4 sucrose + 0.5mM AOA. Flowers held in this treatment also showed a delay in discoloration, thinning of petals and hyponasty. The inclusion of AOA into solutions resulted in low pH and contributes to better water uptake and delayed turgor loss in flowers

Near-Surface Interface Detection for Coal Mining Applications Using Bispectral Features and GPR

The use of ground penetrating radar (GPR) for detecting the presence of near-surface interfaces is a scenario of special interest to the underground coal mining industry. The problem is difficult to solve in practice because the radar echo from the near-surface interface is often dominated by unwanted components such as antenna crosstalk and ringing, ground-bounce effects, clutter, and severe attenuation. These nuisance components are also highly sensitive to subtle variations in ground conditions, rendering the application of standard signal pre-processing techniques such as background subtraction largely ineffective in the unsupervised case. As a solution to this detection problem, we develop a novel pattern recognition-based algorithm which utilizes a neural network to classify features derived from the bispectrum of 1D early time radar data. The binary classifier is used to decide between two key cases, namely whether an interface is within, for example, 5 cm of the surface or not. This go/no-go detection capability is highly valuable for underground coal mining operations, such as longwall mining, where the need to leave a remnant coal section is essential for geological stability. The classifier was trained and tested using real GPR data with ground truth measurements. The real data was acquired from a testbed with coal-clay, coal-shale and shale-clay interfaces, which represents a test mine site. We show that, unlike traditional second order correlation based methods such as matched filtering which can fail even in known conditions, the new method reliably allows the detection of interfaces using GPR to be applied in the near-surface region. In this work, we are not addressing the problem of depth estimation, rather confining ourselves to detecting an interface within a particular depth range

Mental Health Mediates the Association Between Gender-Based Violence and HIV Treatment Engagement in US Women

Background: Gender-based violence (GBV) is associated with poorer engagement in HIV care and treatment. However, there is a dearth of research on the psychological (eg, mental health) and structural (eg, food insecurity) factors that mediate and moderate this association. GBV could lead to poor mental health, which in turn affects adherence, whereas food insecurity could worsen the effect of GBV on engagement in care. This study uses data from the Women's Interagency HIV Study to address these gaps. Methods: Women completed 6 assessments from 2013 to 2016 on GBV, mental health, food insecurity, adherence to antiretroviral therapy, and missed HIV care appointments in the past 6 months. Multilevel logistic regression models estimated associations between GBV and engagement in care and whether associations were mediated by depression, generalized anxiety disorder (GAD), and posttraumatic stress disorder (PTSD) and moderated by food insecurity. Results: GBV was associated with higher odds of suboptimal adherence (adjusted odds ratio: 1.88; 95% confidence interval: 1.24 to 2.87) and missed appointments (adjusted odds ratio: 1.76; 95% confidence interval: 1.16 to 2.67). The association between GBV and adherence was mediated by depressive symptoms, GAD, and PTSD, accounting for 29.7%, 15.0%, and 16.5%, respectively, of the total association. The association between GBV and missed appointments was mediated by depression and GAD, but not PTSD, with corresponding figures of 25.2% and 19.7%. Associations did not differ by food insecurity. Conclusions: GBV is associated with suboptimal engagement in care, which may be explained by mental health. Interventions should address women's mental health needs, regardless of food insecurity, when improving engagement in HIV care

Mechanisms linking gender-based violence to worse HIV treatment and care outcomes among women in the United States

Objective:To test whether substance use mediates the associations between gender-based violence (GBV) and suboptimal adherence to antiretroviral therapy (ART), and GBV and poor engagement in care, among women living with HIV (WLHIV) in the United States (US).Design:We analyzed longitudinal data collected among 1717 WLHIV in the Women's Interagency HIV Study (WIHS).Methods:From 2013 to 2017, WLHIV completed semi-annual assessments on GBV, substance use, and HIV treatment and care. Adjusted multilevel logistic regression models were built to estimate the impact of GBV on; suboptimal (<95%) adherence and at least one missed HIV care appointment without rescheduling in the past 6 months. Mediation analyses were performed to test whether heavy drinking and illicit drug use mediated the associations between GBV and the two HIV outcomes.Results:The mean age was 47 (standard deviation = 9), 5% reported experiencing GBV, 17% reported suboptimal adherence and 15% reported at least one missed appointment in the past 6 months. Women who experienced GBV had a significantly higher odds of suboptimal adherence [adjusted odds ratio (aOR) = 1.99; 95% confidence interval (CI) = 1.40-2.83] and missed appointments (aOR = 1.92, 95% CI = 1.32-2.33). Heavy drinking and illicit drug use mediated 36 and 73% of the association between GBV and suboptimal adherence and 29 and 65% of the association between GBV and missed appointments, respectively.Conclusions:Substance use is an underlying mechanism through which GBV affects outcomes along the HIV care continuum among WLHIV in the US. To optimize HIV treatment and care among women, interventions should address the combined epidemics of substance use, violence, and HIV

Solar Wind Turbulence and the Role of Ion Instabilities

International audienc

Origins of the Ambient Solar Wind: Implications for Space Weather

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

Large-Eddy Simulations of Magnetohydrodynamic Turbulence in Heliophysics and Astrophysics

We live in an age in which high-performance computing is transforming the way we do science. Previously intractable problems are now becoming accessible by means of increasingly realistic numerical simulations. One of the most enduring and most challenging of these problems is turbulence. Yet, despite these advances, the extreme parameter regimes encountered in space physics and astrophysics (as in atmospheric and oceanic physics) still preclude direct numerical simulation. Numerical models must take a Large Eddy Simulation (LES) approach, explicitly computing only a fraction of the active dynamical scales. The success of such an approach hinges on how well the model can represent the subgrid-scales (SGS) that are not explicitly resolved. In addition to the parameter regime, heliophysical and astrophysical applications must also face an equally daunting challenge: magnetism. The presence of magnetic fields in a turbulent, electrically conducting fluid flow can dramatically alter the coupling between large and small scales, with potentially profound implications for LES/SGS modeling. In this review article, we summarize the state of the art in LES modeling of turbulent magnetohydrodynamic (MHD) ows. After discussing the nature of MHD turbulence and the small-scale processes that give rise to energy dissipation, plasma heating, and magnetic reconnection, we consider how these processes may best be captured within an LES/SGS framework. We then consider several special applications in heliophysics and astrophysics, assessing triumphs, challenges,and future directions

Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

Pigment identification and antioxidant properties of red dragon fruit (Hylocereus polyrhizus)

The aim of this study was to identify pigments present in the red dragon fruit (Hylocereus polyrhizus) and to further investigate the antioxidant properties in this fruit. Pigment was identified using the High Performance Liquid Chromatography (HPLC) and results confirmed the presence of betanin in sample at a retention time of 11.5 min which corresponded to the retention time of the betanin standard used. In the antioxidant properties determination, there were 86.10 mg of total polyphenolic compound in 0.50 g of dried dragon fruit extract using the total polyphenol assay which expresses gallic acid as equivalent. The reducing power assay further confirmed the antioxidant activity present in dragon fruit where the reducing capability increased from 0.18 to 2.37 with the increase of dry weight sample from 0.03 to 0.5 g. The Vanillin-HCl assay which measures the amount of condensed tannin showed that the dried dragon fruit sample had an equivalent of 2.30 mg catechin/g. The DPPH center dot radical scavenging activity determination showed that the effective concentration (EC(50)) for dragon fruit was 2.90 mM vitamin C equivalents/g dried extract

Activity of cell wall degrading enzymes in hylocereus polyrhizus

Changes in the activities of cell wall degrading enzymes such as pectinmethylesterase (PME), polygalacturonase (PG), pectate lyase (PL) and cellulase were studied in red fleshed dragon fruit, Hylocereus polyrhizus harvested at three different harvest maturities. PME activity increased in fruit harvested earlier as opposed to fruit harvested at ripe stage while PG activity increased in all three different stages. Activity of pectate lyase was almost invariable in all three different stages. As for younger fruit, the cellulase activity increased progressively while activity was found to be within the same range in fruit harvested at ripe stage