763 research outputs found
Note on group distance magic graphs
A \emph{group distance magic labeling} or a \gr-distance magic labeling of
a graph with is an injection from to an Abelian
group \gr of order such that the weight of
every vertex is equal to the same element \mu \in \gr, called the
magic constant. In this paper we will show that if is a graph of order
for some natural numbers , such that \deg(v)\equiv c
\imod {2^{p+1}} for some constant for any , then there exists
an \gr-distance magic labeling for any Abelian group \gr for the graph
. Moreover we prove that if \gr is an arbitrary Abelian group of
order such that \gr \cong \zet_2 \times\zet_2 \times \gA for some
Abelian group \gA of order , then exists a \gr-distance magic labeling
for any graph
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Networks Underpinning Symbiosis Revealed Through Cross-Species eQTL Mapping.
Organisms engage in extensive cross-species molecular dialog, yet the underlying molecular actors are known for only a few interactions. Many techniques have been designed to uncover genes involved in signaling between organisms. Typically, these focus on only one of the partners. We developed an expression quantitative trait locus (eQTL) mapping-based approach to identify cause-and-effect relationships between genes from two partners engaged in an interspecific interaction. We demonstrated the approach by assaying expression of 98 isogenic plants (Medicago truncatula), each inoculated with a genetically distinct line of the diploid parasitic nematode Meloidogyne hapla With this design, systematic differences in gene expression across host plants could be mapped to genetic polymorphisms of their infecting parasites. The effects of parasite genotypes on plant gene expression were often substantial, with up to 90-fold (P = 3.2 × 10-52) changes in expression levels caused by individual parasite loci. Mapped loci included a number of pleiotropic sites, including one 87-kb parasite locus that modulated expression of >60 host genes. The 213 host genes identified were substantially enriched for transcription factors. We distilled higher-order connections between polymorphisms and genes from both species via network inference. To replicate our results and test whether effects were conserved across a broader host range, we performed a confirmatory experiment using M. hapla-infected tomato. This revealed that homologous genes were similarly affected. Finally, to validate the broader utility of cross-species eQTL mapping, we applied the strategy to data from a Salmonella infection study, successfully identifying polymorphisms in the human genome affecting bacterial expression
Bax/Bak promote sumoylation of DRP1 and its stable association with mitochondria during apoptotic cell death
Dynamin-related protein 1 (DRP1) plays an important role in mitochondrial fission at steady state and during apoptosis. Using fluorescence recovery after photobleaching, we demonstrate that in healthy cells, yellow fluorescent protein (YFP)–DRP1 recycles between the cytoplasm and mitochondria with a half-time of 50 s. Strikingly, during apoptotic cell death, YFP-DRP1 undergoes a transition from rapid recycling to stable membrane association. The rapid cycling phase that characterizes the early stages of apoptosis is independent of Bax/Bak. However, after Bax recruitment to the mitochondrial membranes but before the loss of mitochondrial membrane potential, YFP-DRP1 becomes locked on the membrane, resulting in undetectable fluorescence recovery. This second phase in DRP1 cycling is dependent on the presence of Bax/Bak but independent of hFis1 and mitochondrial fragmentation. Coincident with Bax activation, we detect a Bax/Bak-dependent stimulation of small ubiquitin-like modifier-1 conjugation to DRP1, a modification that correlates with the stable association of DRP1 with mitochondrial membranes. Altogether, these data demonstrate that the apoptotic machinery regulates the biochemical properties of DRP1 during cell death
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Landsat-Derived Estimates of Mangrove Extents in the Sierra Leone Coastal Landscape Complex during 1990–2016
This study provides the first assessment of decadal changes in mangrove extents in Sierra Leone. While significant advances have been made in mangrove mapping using remote sensing, no study has documented long-term changes in mangrove extents in Sierra Leone—one of the most vulnerable countries in West Africa. Such understanding is critical for devising regional management strategies that can support local livelihoods. We utilize multi-date Landsat data and cloud computational techniques to quantify spatiotemporal changes in land cover, with focus on mangrove ecosystems, for 1990–2016 along the coast of Sierra Leone. We specifically focus on four estuaries—Scarcies, Sierra Leone, Yawri Bay, and Sherbro. We relied on the k-means approach for an unsupervised classification, and validated the classified map from 2016 using ground truth data collected from Sentinel-2 and high-resolution images and during field research (accuracy: 95%). Our findings indicate that the Scarcies river estuary witnessed the greatest mangrove loss since 1990 (45%), while the Sierra Leone river estuary experienced mangrove gain over the last 26 years (22%). Overall, the Sierra Leone coast lost 25% of its mangroves between 1990 and 2016, with the lowest coverage in 2000, during the period of civil war (1991–2002). However, natural mangrove dynamics, as supported by field observations, indicate the potential for regeneration and sustainability under carefully constructed management strategies
Spectroscopic properties of halite from KÅ‚odawa salt mine, central Poland
The dynamics of colour centre transformation was investigated in blue halite single crystals from KÅ‚odawa Salt Mine, Central Poland, using UV-vis spectroscopy. The following colour centres were considered: F, R_{1}, R_{2}, as well as plasmons and M centres. The R_{2} centres predominated in navy blue (A) and pale blue (B) halites. Other relatively large populations were plasmons found in all examined samples. In purple (C) halite samples the plasmon population is the highest one among others and R_{1} centres appeared to be equally significant, whereas M centres were almost absent. For A and C samples unidentified bands were observed at 26,500 to 26,200 cm^{-1}, respectively. The bleaching process of the blue halites was investigated using temperature dependent UV-vis and micro-Raman spectroscopies. In micro-Raman 300-100 cm^{-1} region three very intense sharp bands were attributed to the colour centres and colloidal Na precipitation in A and B halites. The one broad band in the range 3,500 to 500 cm^{-1}, which was characteristic even for the colourless sample D but absent in the spectra of colourless NaCl obtained after recrystallization of sample A, requires further study
Towards retrieving dispersion profiles using quantum-mimic Optical Coherence Tomography and Machine Learnin
Artefacts in quantum-mimic Optical Coherence Tomography are considered
detrimental because they scramble the images even for the simplest objects.
They are a side effect of autocorrelation which is used in the quantum
entanglement mimicking algorithm behind this method. Interestingly, the
autocorrelation imprints certain characteristics onto an artefact - it makes
its shape and characteristics depend on the amount of dispersion exhibited by
the layer that artefact corresponds to. This unique relationship between the
artefact and the layer's dispersion can be used to determine Group Velocity
Dispersion (GVD) values of object layers and, based on them, build a
dispersion-contrasted depth profile. The retrieval of GVD profiles is achieved
via Machine Learning. During training, a neural network learns the relationship
between GVD and the artefacts' shape and characteristics, and consequently, it
is able to provide a good qualitative representation of object's dispersion
profile for never-seen-before data: computer-generated single dispersive layers
and experimental pieces of glass.Comment: 11 pages, 5 figure
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