2,224 research outputs found

    Impact of multiscale dynamical processes and mixing on the chemical composition of the upper troposphere and lower stratosphere during the Intercontinental Chemical Transport Experiment–North America

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    We use high-frequency in situ observations made from the DC8 to examine fine-scale tracer structure and correlations observed in the upper troposphere and lower stratosphere during INTEX-NA. Two flights of the NASA DC-8 are compared and contrasted. Chemical data from the DC-8 flight on 18 July show evidence for interleaving and mixing of polluted and stratospheric air masses in the vicinity of the subtropical jet in the upper troposphere, while on 2 August the DC-8 flew through a polluted upper troposphere and a lowermost stratosphere that showed evidence of an intrusion of polluted air. We compare data from both flights with RAQMS 3-D global meteorological and chemical model fields to establish dynamical context and to diagnose processes regulating the degree of mixing on each day. We also use trajectory mapping of the model fields to show that filamentary structure due to upstream strain deformation contributes to tracer variability observed in the upper troposphere. An Eulerian measure of strain versus rotation in the large-scale flow is found useful in predicting filamentary structure in the vicinity of the jet. Higher-frequency (6–24 km) tracer variability is attributed to buoyancy wave oscillations in the vicinity of the jet, whose turbulent dissipation leads to efficient mixing across tracer gradients

    Optical vortex generation from molecular chromophore arrays

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    The generation of light endowed with orbital angular momentum, frequently termed optical vortex light, is commonly achieved by passing a conventional beam through suitably constructed optical elements. This Letter shows that the necessary phase structure for vortex propagation can be directly produced through the creation of twisted light from the vacuum. The mechanism is based on optical emission from a family of chromophore nanoarrays that satisfy specific geometric and symmetry constraints. Each such array can support pairs of electronically delocalized doubly degenerate excitons whose azimuthal phase progression is responsible for the helical wave front of the emitted radiation. The exciton symmetry dictates the maximum magnitude of topological charge; detailed analysis secures the conditions necessary to deliver optical vortices of arbitrary order

    Identifying the development in phase and amplitude of dipole and multipole radiation

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    The spatial variation in phase and the propagating wave-front of plane wave electromagnetic radiation are widely familiar text-book territory. In contrast, the developing amplitude and phase of radiation emitted by a dipole or multipole source generally receive less attention, despite the prevalence of these systems. There is additional complexity in such cases where, in consequence of retardation, the character and features significantly and progressively change as radiation propagates onwards, from the near-field and out towards the wave-zone. Readily developed analytical representations of the electric field, cast as a function of distance from the source, provide illuminating insights into the most prominent and distinctive properties of radiant electromagnetic emission. Graphical implementations and animations of the results prove particularly instructive in revealing the spatial form and temporal evolution of the emergent electromagnetic fields

    The Effect of Salicylic Acid on the Growth and Microtuberization of Potato (Solanum tuberosum L.) cv. Arizona Propagated in Vitro

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    Salicylic acid was employed in this study at levels (0, 50, 100, 150, 200 mg/L) in culture media for shoot development from the culture of single nodal segments, the results showed that the level (100 mg/L) was the best significantly in shoot number, leaf number, leaf area, root length and number, the significant effect of (100 mg/L) was also in total soluble protein (16.78 mg/gm) in shoots, whereas the levels (100,150, 200 mg/l) were the best significantly in chlorophyll content of the shoot leaves, the level (100 mg/L) was also affected significantly in the means of microtuber weight and number(1.094), (7.125) and total soluble protein (5.146 µg /gm) whereas the levels (100 and 150 mg/L) of salicylic acid in starch percentage (12.97, 12.99 %) were better significantly than control treatment (2.55 %). Keywords: Salicylic acid, Potato. Microtuberization, InVitr

    Endometriosis: Terapi Medikamentosa Yang Efisien

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    Endometriosis merupakan penyakit kandungan yang banyak diderita wanita usia reproduksi, ditandai dengan adanya jaringan endometrium baik stroma maupun kelenjar yang implantasi di luar kavum uterus dan memicu terjadinya reaksi inflamasi kronis (ESHRE, 2006). Implantasi abnormal jaringan endometrium ini umumnya terjadi pada permukaan peritoneum, uterus, ovarium, kavum Douglas, namun kemungkinan juga dapat terjadi di beberapa tempat jauh dari organ reproduksi

    Neuroinflammation in post-acute sequelae of COVID-19 (PASC) as assessed by [11C]PBR28 PET correlates with vascular disease measures

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    The COVID-19 pandemic caused by SARS-CoV-2 has triggered a consequential public health crisis of post-acute sequelae of COVID-19 (PASC), sometimes referred to as long COVID. The mechanisms of the heterogeneous persistent symptoms and signs that comprise PASC are under investigation, and several studies have pointed to the central nervous and vascular systems as being potential sites of dysfunction. In the current study, we recruited individuals with PASC with diverse symptoms, and examined the relationship between neuroinflammation and circulating markers of vascular dysfunction. We used [ 11C]PBR28 PET neuroimaging, a marker of neuroinflammation, to compare 12 PASC individuals versus 43 normative healthy controls. We found significantly increased neuroinflammation in PASC versus controls across a wide swath of brain regions including midcingulate and anterior cingulate cortex, corpus callosum, thalamus, basal ganglia, and at the boundaries of ventricles. We also collected and analyzed peripheral blood plasma from the PASC individuals and found significant positive correlations between neuroinflammation and several circulating analytes related to vascular dysfunction. These results suggest that an interaction between neuroinflammation and vascular health may contribute to common symptoms of PASC

    Heterotic String Field Theory

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    We construct the Neveu-Schwarz sector of heterotic string field theory using the large Hilbert space of the superghosts and the multi-string products of bosonic closed string field theory. No picture-changing operators are required as in Wess-Zumino-Witten-like open superstring field theory. The action exhibits a novel kind of nonpolynomiality: in addition to terms necessary to cover missing regions of moduli spaces, new terms arise from the boundary of the missing regions and its subspaces. We determine the action up to quintic order and a subset of terms to all orders.Comment: 15 pages, no figures, LaTeX2e; v2: minor cosmetic change

    Integration and Characterisation of Piezoelectric Macro-Fibre Composite on Carbon Fibre Composite for Vibration Energy Harvesting

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    Carbon fibre composite is a strong and a lightweight structural material with applications in automotive, aerospace, medical and industrial applications. The integration of piezoelectric transducer films onto the composite stack can add vibration energy harvesting capabilities to enable net-zero-power autonomous sensing for an otherwise purely mechanical structure. A PZT macro-fibre composite is co-cured with a carbon/epoxy pre-preg in order to manufacture the multi-functional composite plate. Without noticeably increasing profile, adding weight or compromising mechanical integrity, the resultant mechanical plate can recover power from vibrational excitations. With a volume of 13.5cm3, a peak average power of 9.25mW was recorded at 2.66 ms−2. The normalised power density of 97 μW cm −3 m −2 s 4 is comparable to some of the state-of-the-art PZT generators reported in the literature

    N-String Vertices in String Field Theory

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    We give the general form of the vertex corresponding to the interaction of an arbitrary number of strings. The technique employed relies on the ``comma" representation of String Field Theory where string fields and interactions are represented as matrices and operations between them such as multiplication and trace. The general formulation presented here shows that the interaction vertex of N strings, for any arbitrary N, is given as a function of particular combinations of matrices corresponding to the change of representation between the full string and the half string degrees of freedom.Comment: 22 pages, A4-Latex (latex twice), FTUV IFI
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