Prime Saturations and Rees Algebras of Almost Linearly Presented Ideals

Let I be a height two perfect ideal in the polynomial ring k[x1, ..., xd] satisfying the Gd condition. Suppose I admits a homogeneous presentation matrix composed of linear columns except for one column of degree n. In this setting, we give two descriptions of the ideal A defining the Rees algebra Rees(I) and if in addition I is generated by d+1 elements, we give an explicit generating set for A

Genetics of a de novo origin of undifferentiated multicellularity

The evolution of multicellularity was a major transition in evolution and set the stage for unprecedented increases in complexity, especially in land plants and animals. Here, we explore the genetics underlying a de novo origin of multicellularity in a microbial evolution experiment carried out on the green alga Chlamydomonas reinhardtii. We show that large-scale changes in gene expression underlie the transition to a multicellular life cycle. Among these, changes to genes involved in cell cycle and reproductive processes were overrepresented, as were changes to C. reinhardtii-specific and volvocine-specific genes. These results suggest that the genetic basis for the experimental evolution of multicellularity in C. reinhardtii has both lineage-specific and shared features, and that the shared features have more in common with C. reinhardtii\u27s relatives among the volvocine algae than with other multicellular green algae or land plants

Ultrathin uniform platinum nanowires via a facile route using an inverse hexagonal surfactant phase template

We present an attractive method for the fabrication of long, straight, highly crystalline, ultrathin platinum nanowires. The fabrication is simply achieved using an inverse hexagonal (HII) lyotropic liquid crystal phase of the commercial surfactant phytantriol as a template. A platinum precursor dissolved within the cylindrical aqueous channels of the liquid crystal phase is chemically reduced by galvanic displacement using stainless steel. We demonstrate the production of nanowires using the HII phase in the phytantriol/water system which we obtain either by heating to 55 °C or at room temperature by the addition of a hydrophobic liquid, 9-cis-tricosene, to relieve packing frustration. The two sets of conditions produced high aspect nanowires with diameters of 2.5 and 1.7 nm, respectively, at least hundreds of nanometers in length, matching the size of the aqueous channels in which they grow. This versatile approach can be extended to produce highly uniform nanowires from a range of metals

Early Detection of Response to Experimental Chemotherapeutic Top216 with [18F]FLT and [18F]FDG PET in Human Ovary Cancer Xenografts in Mice

BACKGROUND: 3'-Deoxy-3'-[(18)F]fluorothymidine ((18)F-FLT) is a tracer used to assess cell proliferation in vivo. The aim of the study was to use (18)F-FLT positron emission tomography (PET) to study treatment responses to a new anti-cancer compound. To do so, we studied early anti-proliferative effects of the experimental chemotherapy Top216 non-invasively by PET. METHODOLOGY/PRINCIPAL FINDINGS: In vivo uptake of (18)F-FLT in human ovary cancer xenografts in mice (A2780) was studied at various time points after Top216 treatment (50 mg/kg i.v. at 0 and 48 hours) was initiated. Baseline (18)F-FLT scans were made before either Top216 (n = 7-10) or vehicle (n = 5-7) was injected and repeated after 2 and 6 hours and 1 and 5 days of treatment. A parallel study was made with 2'-deoxy-2'-[(18)F]fluoro-D-glucose ((18)F-FDG) (n = 8). Tracer uptake was quantified using small animal PET/CT. Imaging results were validated by tumor volume changes and gene-expression of Ki67 and TK1. Top216 (50 mg/kg 0 and 48 hours) inhibited the growth of the A2780 tumor compared to the control group (P<0.001). (18)F-FLT uptake decreased significantly at 2 hours (-52%; P<0.001), 6 hours (-49%; P = 0.002) and Day 1 (-47%; P<0.001) after Top216 treatment. At Day 5 (18)F-FLT uptake was comparable to uptake in the control group. Uptake of (18)F-FLT was unchanged in the control group during the experiment. In the treatment group, uptake of (18)F-FDG was significantly decreased at 6 hours (-21%; P = 0.003), Day 1 (-29%; P<0.001) and Day 5 (-19%; P = 0.05) compared to baseline. CONCLUSIONS/SIGNIFICANCE: One injection with Top216 initiated a fast and significant decrease in cell-proliferation assessable by (18)F-FLT after 2 hours. The early reductions in tumor cell proliferation preceded changes in tumor size. Our data indicate that (18)F-FLT PET is promising for the early non-invasive assessment of chemotherapy effects in both drug development and for tailoring therapy in patients

De novo origins of multicellularity in response to predation

The transition from unicellular to multicellular life was one of a few major events in the history of life that created new opportunities for more complex biological systems to evolve. Predation is hypothesized as one selective pressure that may have driven the evolution of multicellularity. Here we show that de novo origins of simple multicellularity can evolve in response to predation. We subjected outcrossed populations of the unicellular green alga Chlamydomonas reinhardtii to selection by the filter-feeding predator Paramecium tetraurelia. Two of five experimental populations evolved multicellular structures not observed in unselected control populations within ~750 asexual generations. Considerable variation exists in the evolved multicellular life cycles, with both cell number and propagule size varying among isolates. Survival assays show that evolved multicellular traits provide effective protection against predation. These results support the hypothesis that selection imposed by predators may have played a role in some origins of multicellularity

Processes associated with ionic current rectification at a 2D-titanate nanosheet deposit on a microhole poly(ethylene terephthalate) substrate

Films of titanate nanosheets (approx. 1.8-nm layer thickness and 200-nm size) having a lamellar structure can form electrolyte-filled semi-permeable channels containing tetrabutylammonium cations. By evaporation of a colloidal solution, persistent deposits are readily formed with approx. 10-μm thickness on a 6-μm-thick poly(ethylene-terephthalate) (PET) substrate with a 20-μm diameter microhole. When immersed in aqueous solution, the titanate nanosheets exhibit a p.z.c. of − 37 mV, consistent with the formation of a cation conducting (semi-permeable) deposit. With a sufficiently low ionic strength in the aqueous electrolyte, ionic current rectification is observed (cationic diode behaviour). Currents can be dissected into (i) electrolyte cation transport, (ii) electrolyte anion transport and (iii) water heterolysis causing additional proton transport. For all types of electrolyte cations, a water heterolysis mechanism is observed. For Ca 2+ and Mg 2+ ions, water heterolysis causes ion current blocking, presumably due to localised hydroxide-induced precipitation processes. Aqueous NBu 4 + is shown to ‘invert’ the diode effect (from cationic to anionic diode). Potential for applications in desalination and/or ion sensing are discussed. [Figure not available: see fulltext.]. </p

Kenneth Lewis Roberts Correspondence

Entries include brief biographical information, a typed biography, typed and handwritten correspondence on personal stationery from Kennebunk Beach, Maine, including a humorous letter in 1933 concerning the Society for Helping Maine Literature, his belief that the author collection was in need of Arnoldiana such as a donated pike head handmade by Arnold\u27s blacksmiths for the attack on Quebec, the manuscript of Arundel sent to be opened after publication and loaned to Leonard for Doubleday Doran and Company and a surprising Western Union telegram requesting permanent loan of the manuscript for MIT, handwritten and typed correspondence from Roberts in Italy including a handwritten artistic postcard from his wife, numerous biographical newspaper review clippings with photographic images, book synopses, and a poem for Theodore Roosevelt who could remember neither the author nor title of the book he was reading, a research question concerning Maine people on cookery, notes through the years concerning his friends, the staff at Doubleday, historians, libraries, and librarians as well as transition at the Maine Development Commission, correspondence with Mary A. Benjamin on Walter R. Benjamin, Autographs, stationery and a postcard concerning the possible sale of a copy of a Maine land grant document, a gift instead from Roberts of his vellum copy of the Trelawny-Goodyear grant of 1631, and the reply of Stubbs from the Maine State Library on receipt of this copy of the Casco Bay land grant