Graptolites from Silurian (Llandovery Series) sedimentary deposits attributed to a forearc setting, Co To Formation, Co To archipelago, northeast Vietnam

Newly collected graptolites from the Co To Formation, Co To archipelago, NE Vietnam, comprise assemblages indicative of two biostratigraphical levels within the lower Silurian, Llandovery Series, Telychian Stage: the co-occurrence of Spirograptus turriculatus and Torquigraptus proteus? suggests an interval most likely within the upper part of the Spirograptus turriculatus Biozone or 'Monograptus' crispus Biozone, whilst Oktavites spirally and Monoclimacis cf. suhgeinitzi identify the Oktavites spiralis Biozone. The graptolites provide important biostratigraphical evidence for the age of the upper part of the lower Co To Formation, biostratigraphical ties between the NE Vietnamese succession of the Bac Bo Region and graptolite assemblages of the Long Dai Formation in the Viet-Lao Region of central Vietnam, and include the new species Monograptus hanutlus sp. nov. co-occurring with S. turriculatus, which is perhaps an ancestral form to the later Telychian species Monograptus drepanoformis. We also report the lirst chitinozoans, including Belonechitina, from the Co To Formation

Transcriptional Response of Selenopolypeptide Genes and Selenocysteine Biosynthesis Machinery Genes in Escherichia coli during Selenite Reduction

This work was supported by a United States Department of Agriculture-Cooperative State Research, Education, and Extension Service grant (no. 2009-35318-05032), a Biotechnology Research grant (no. 2007-BRG-1223) from the North Carolina Biotechnology Center, and a startup fund from the Golden LEAF Foundation to the Biomanufacturing Research Institute and Technology Enterprise (BRITE).Bacteria can reduce toxic selenite into less toxic, elemental selenium (Se0), but the mechanism on how bacterial cells reduce selenite at molecular level is still not clear. We used Escherichia coli strain K12, a common bacterial strain, as a model to study its growth response to sodium selenite (Na2SeO3) treatment and then used quantitative real-time PCR (qRT-PCR) to quantify transcript levels of three E. coli selenopolypeptide genes and a set of machinery genes for selenocysteine (SeCys) biosynthesis and incorporation into polypeptides, whose involvements in the selenite reduction are largely unknown. We determined that 5 mM Na2SeO3 treatment inhibited growth by ∼50% while 0.001 to 0.01 mM treatments stimulated cell growth by ∼30%. Under 50% inhibitory or 30% stimulatory Na2SeO3 concentration, selenopolypeptide genes (fdnG, fdoG, and fdhF) whose products require SeCys but not SeCys biosynthesis machinery genes were found to be induced ≥2-fold. In addition, one sulfur (S) metabolic gene iscS and two previously reported selenite-responsive genes sodA and gutS were also induced ≥2-fold under 50% inhibitory concentration. Our findings provide insight about the detoxification of selenite in E. coli via induction of these genes involved in the selenite reduction process.Publisher PDFPeer reviewe

Combinatorial generation via permutation languages

In this work we present a general and versatile algorithmic framework for exhaustively generating a large variety of different combinatorial objects, based on encoding them as permutations. This approach provides a unified view on many known results and allows us to prove many new ones. In particular, we obtain the following four classical Gray codes as special cases: the Steinhaus-Johnson-Trotter algorithm to generate all permutations of an $n$-element set by adjacent transpositions; the binary reflected Gray code to generate all $n$-bit strings by flipping a single bit in each step; the Gray code for generating all $n$-vertex binary trees by rotations due to Lucas, van Baronaigien, and Ruskey; the Gray code for generating all partitions of an $n$-element ground set by element exchanges due to Kaye. We present two distinct applications for our new framework: The first main application is the generation of pattern-avoiding permutations, yielding new Gray codes for different families of permutations that are characterized by the avoidance of certain classical patterns, (bi)vincular patterns, barred patterns, Bruhat-restricted patterns, mesh patterns, monotone and geometric grid classes, and many others. We thus also obtain new Gray code algorithms for the combinatorial objects that are in bijection to these permutations, in particular for five different types of geometric rectangulations, also known as floorplans, which are divisions of a square into $n$ rectangles subject to certain restrictions. The second main application of our framework are lattice congruences of the weak order on the symmetric group~$S_n$. Recently, Pilaud and Santos realized all those lattice congruences as $(n-1)$-dimensional polytopes, called quotientopes, which generalize hypercubes, associahedra, permutahedra etc. Our algorithm generates the equivalence classes of each of those lattice congruences, by producing a Hamilton path on the skeleton of the corresponding quotientope, yielding a constructive proof that each of these highly symmetric graphs is Hamiltonian. We thus also obtain a provable notion of optimality for the Gray codes obtained from our framework: They translate into walks along the edges of a polytope

Dynamic Matching Algorithms Under Vertex Updates

Dynamic graph matching algorithms have been extensively studied, but mostly under edge updates. This paper concerns dynamic matching algorithms under vertex updates, where in each update step a single vertex is either inserted or deleted along with its incident edges. A basic setting arising in online algorithms and studied by Bosek et al. [FOCS\u2714] and Bernstein et al. [SODA\u2718] is that of dynamic approximate maximum cardinality matching (MCM) in bipartite graphs in which one side is fixed and vertices on the other side either arrive or depart via vertex updates. In the BASIC-incremental setting, vertices only arrive, while in the BASIC-decremental setting vertices only depart. When vertices can both arrive and depart, we have the BASIC-dynamic setting. In this paper we also consider the setting in which both sides of the bipartite graph are dynamic. We call this the MEDIUM-dynamic setting, and MEDIUM-decremental is the restriction when vertices can only depart. The GENERAL-dynamic setting is when the graph is not necessarily bipartite and the vertices can both depart and arrive. Denote by K the total number of edges inserted and deleted to and from the graph throughout the entire update sequence. A well-studied measure, the recourse of a dynamic matching algorithm is the number of changes made to the matching per step. We largely focus on Maximal Matching (MM) which is a 2-approximation to the MCM. Our main results are as follows. - In the BASIC-dynamic setting, there is a straightforward algorithm for maintaining a MM, with a total runtime of O(K) and constant worst-case recourse. In fact, this algorithm never removes an edge from the matching; we refer to such an algorithm as irrevocable. - For the MEDIUM-dynamic setting we give a strong conditional lower bound that even holds in the MEDIUM-decremental setting: if for any fixed ? > 0, there is an irrevocable decremental MM algorithm with a total runtime of O(K ? n^{1-?}), this would refute the OMv conjecture; a similar (but weaker) hardness result can be achieved via a reduction from the Triangle Detection conjecture. - Next, we consider the GENERAL-dynamic setting, and design an MM algorithm with a total runtime of O(K) and constant worst-case recourse. We achieve this result via a 1-revocable algorithm, which may remove just one edge per update step. As argued above, an irrevocable algorithm with such a runtime is not likely to exist. - Finally, back to the BASIC-dynamic setting, we present an algorithm with a total runtime of O(K), which provides an (e/(e-1))-approximation to the MCM. To this end, we build on the classic "ranking" online algorithm by Karp et al. [STOC\u2790]. Beyond the results, our work draws connections between the areas of dynamic graph algorithms and online algorithms, and it proposes several open questions that seem to be overlooked thus far

Assessing the Efficacy of MODIS Satellite-derived Start of Growing Season for Jurisdictional Determination of East Texas Bottomland Hardwood Wetlands

Introduction: Crucial to the determination of a jurisdictional wetland is the definition of “growing season”. Satellite imagery is being utilized in other ecological applications, but is lagging in wetland growing season determination. Both cost and temporal limitations historically have restrained use of satellite imagery in assessing the start up of the growing season. Multiple commercial satellites are available that provide high resolution imagery, but the cost are prohibitive for most studies. The National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey (USGS) jointly manage the Landsat and the Moderate-resolution Imaging Spectroradiometer (MODIS) satellite programs. Landsat Enhanced Thematic Mapper Plus images an area every sixteen (16) days. The rapid biological changes indicating the start up of the growing season must be captured more frequently to successfully use satellite imagery for such a time dependent event. In 1999 NASA launched the MODIS program with the Terra satellite and followed with the Aqua satellite in 2000. Terra’s orbit around the Earth is timed so that it passes from north to south across the equator in the morning. Aqua will pass south to north over the equator in the afternoon. This continual, comprehensive coverage allows MODIS to complete an electromagnetic picture of the globe every day. MODIS imagery is available on a daily basis, but the trade-off for the increased speed at which the satellites travel is a lower resolution image when compared to other satellite systems. Research utilizing MODIS for studying vegetation phenology is beginning to emerge, but there is a lack of validation through ground observation for these studies. (Figure 1 and Figure 2

Accuracy Assessment of Land Cover Maps Derived from Multiple Data Sources

Maximum Likelihood (ML) and Artificial Neural Network (ANN) supervised classification methods were used to demarcate land cover types within IKONOS and Landsat ETM+ imagery. Three additional data sources were integrated into the classification process: Canopy Height Model (CHM), Digital Terrain Model (DTM) and Thermal data. Both the CHM and DTM were derived from multiple return small footprint LIDAR. Forty maps were created and assessed for overall map accuracy, user\u27s accuracy, producer\u27s accuracy, kappa statistic and Z statistic using classification schemes from U.S.G.S. 1976 levels 1 and 2 and T.G.l.C. 1999 levels 2 and 4. Results for overall accuracy of land cover maps derived from multiple sources ranged from 13.67 to 57.56 percent for U.S.G.S. level 2 and T.G.l.C. level 4 across ML and ANN classifications. Results for overall map accuracy ranged from 26.00 to 72.33 percent for U.S.G.S. level 1 and T.G.I.C. level 2 across ML and ANN classifications. Land cover maps, derived using ML classification methodology, were consistently more accurate than land cover maps derived using an ANN classification algorithm

Forest Landscape Changes in East Texas from 1974 to 2002

Timber production has been one of the most important industries in east Texas since the mid 19th century. For over 100 years, timber has represented one-third of all agricultural income in this region. In order to review forest landscape changes over time -- resulting from many years of management and investment -- historical satellite remote sensing data from 1974 to 2002 were used to determine landscape patterns and changes in four counties of east Texas : Angelina, Nacogdoches , San Augustine, and Shelby . Land cover was classified either as forest or non-forest and a land cover map was generated for seven unique time stages. Landscape patches were identified on each land cover map and landscape metrics were calculated, including patch size, aggregation of patches, and patch shape complexity. Results showed a decline of total forestland in the 1980s and a recovery in the 1990s. This observation coincided with historical information about large scale clear-cutting during this time. Mean patch size of forest showed a trend of increase, whereas that of non-forest was consistently decreasing over time. This reflected the decrease of forest patch shape complexity, while the patch shape of non-forest became more complex. The forest in east Texas plays an important role (presumably from intensive management) not only in the local economy but also in the environment. Replanting efforts have created buffers between land development such as urban sprawl and ranching. Eventually, the forest maintains the overall landscape contagion while non-forest land-use is becoming more fragmented