924 research outputs found

    Character Degrees of Normally Monomial Maximal Class 5-Groups

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    This paper will impose limits on the possible sets of irreducible character degrees of a normally monomial 5-group of maximal class

    Remarks on a Paper of Lee and Lim

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    Lee and Lim (2009) state three characterizations of Loamax, exponential and power function distributions, the proofs of which, are based on the solutions of certain second order non-linear differential equations. For these characterizations, they make the following statement : Therefore there exists a unique solution of the differential equation that satisfies the given initial conditions . Although the general solution of their first differential equation is easily obtainable, they do not obtain the general solutions of the other two differential equations to ensure their claim via initial conditions. In this very short report, we present the general solutions of these equations and show that the particular solutions satisfying the initial conditions are uniquely determined to be Lomax, exponential and power function distributions respectively

    Maximal Class \u3cem\u3ep\u3c/em\u3e-Groups with Large Character Degree Gaps

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    In Mann (More on normally monomial p-groups, 2015), he proves some bounds on the size of gaps between character degrees of maximal class p-groups. In this note we construct a family of examples that shows that one of these bounds is sharp

    Exchange of oxygen and hydrogen isotopes between water and water vapor: Experimental results

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    The exchange of {dollar}\delta\sp{18}{dollar}O, {dollar}\delta{dollar}D, and tritium between water and water vapor was quantified using two methods. The first was quiescent equilibration of water samples having widely contrasting isotopic compositions, surface areas, volumes and temperatures, but similar salinities. Rates of exchange (k) depended on surface area and vapor pressure, while the end-point equilibrium was controlled by volume and isotopic composition of the exchanging waters. Values of k ranged from 0.09 to 0.19 cm/day at 22{dollar}\sp\circ{dollar}C and from 0.86 to 0.92 cm/day at 52{dollar}\sp\circ{dollar}C. The second method involved sparging 30 l of tritiated water (5,000 and 630,000 TU) with a constant 15 l/min flux of water-saturated air (TU {dollar}\u3c{dollar} 10). Half of the tritium was exchanged into the vapor effuent over 40 days; k ranged from 0.025/day to 0.030/day. Equilibration with 630,000 TU was observed over a bubble path of 20 cm, suggesting an alternative method of tritium remediation

    Gorgonians Are Foundation Species on Sponge-Dominated Mesophotic Coral Reefs in the Caribbean

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    Foundation species (FS) regulate ecological processes within communities often facilitating biodiversity and habitat complexity. Typically FS are dominant structure-forming taxa; but less dominant taxa having disproportionate ecological impacts to the community can also be FS. Mesophotic coral ecosystems (MCEs) are deep coral reef (∼30–150 m) communities, often dominated by emergent sponges in the Caribbean Basin. Despite the potential competitive advantage of sponges on MCEs, gorgonians are also common constituents of these reefs. Data from the Bahamas demonstrate increased biodiversity and densities of sponges on mesophotic reefs with gorgonians relative to reefs without these species. Drawing upon fifteen years of field surveys at five sites in the Caribbean Basin we assessed in situ interactions between gorgonians and sponges to quantify outcomes consistent with competition (i.e., tissue necrosis and overgrowth). Gorgonians were effective competitors against a variety of sponges, and two allelochemicals produced by Ellisella elongata were mechanistically important in interactions with Agelas clathrodes. We also examined invertebrate recruitment patterns near gorgonians to assess their role in facilitating MCE biodiversity. Our results indicate that live gorgonians, Antillogorgia bipinnata and E. elongata, facilitate biodiverse recruitment into MCEs, indicating that this process is governed by more than passive hydrodynamics. Collectively, these data indicate that these gorgonians exhibit both positive and negative ecological interactions (i.e., facilitation and competition, respectively) with sponges, and other taxa. Thus, these gorgonians are FS of MCE communities within the Caribbean Basin that display several traits contributing to the ecological structure of these understudied communities

    Genetic Structure in the Coral, Montastraea cavernosa: Assessing Genetic Differentiation among and within Mesophotic Reefs

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    Mesophotic coral reefs (30–150 m) have recently received increased attention as a potential source of larvae (e.g., the refugia hypothesis) to repopulate a select subset of the shallow water (,30 m) coral fauna. To test the refugia hypothesis we used highly polymorphic Amplified Fragment Length Polymorphism (AFLP) markers as a means to assess small-scale genetic heterogeneity between geographic locations and across depth clines in the Caribbean coral, Montastraea cavernosa. Zooxanthellae-free DNA extracts of coral samples (N = 105) were analyzed from four depths, shallow (3–10 m), medium (15– 25 m), deep (30–50 m) and very deep (60–90 m) from Little Cayman Island (LCI), Lee Stocking Island (LSI), Bahamas and San Salvador (SS), Bahamas which range in distance from 170 to 1,600 km apart. Using AMOVA analysis there were significant differences in WST values in pair wise comparisons between LCI and LSI. Among depths at LCI, there was significant genetic differentiation between shallow and medium versus deep and very deep depths in contrast there were no significant differences in WST values among depths at LSI. The assignment program AFLPOP, however, correctly assigned 95.7% of the LCI and LSI samples to the depths from which they were collected, differentiating among populations as little as 10 to 20 m in depth from one another. Discriminant function analysis of the data showed significant differentiation among samples when categorized by collection site as well as collection depth. FST outlier analyses identified 2 loci under positive selection and 3 under balancing selection at LCI. At LSI 2 loci were identified, both showing balancing selection. This data shows that adult populations of M. cavernosa separated by depths of tens of meters exhibits significant genetic structure, indicative of low population connectivity among and within sites and are not supplying successful recruits to adjacent coral reefs less than 30 m in depth

    Annual Thermal Stress Increases a Soft Coral’s Susceptibility to Bleaching

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    © 2019 by the authors. Bioassay-guided fractionation of an EtOAc extract of the broth of the endophytic fungus Nemania sp. UM10M (Xylariaceae) isolated from a diseased Torreya taxifolia leaf afforded three known cytochalasins, 19,20-epoxycytochalasins C (1) and D (2), and 18-deoxy-19,20-epoxy-cytochalasin C (3). All three compounds showed potent in vitro antiplasmodial activity and phytotoxicity with no cytotoxicity to Vero cells. These compounds exhibited moderate to weak cytotoxicity to some of the cell lines of a panel of solid tumor (SK-MEL, KB, BT-549, and SK-OV-3) and kidney epithelial cells (LLC-PK11). Evaluation of in vivo antimalarial activity of 19,20-epoxycytochalasin C (1) in a mouse model at 100 mg/kg dose showed that this compound had weak suppressive antiplasmodial activity and was toxic to animals
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