Downy brome seed bank dynamics in southwestern Saskatchewan

Non-Peer ReviewedIn order to study downy brome seed bank dynamics, a burial experiment was established near Maple Creek in August 1987. Downy brome seed was buried at four depths (2.5 to 20 cm), and placed on the soil surface, in nylon mesh bags. Seed was exhumed at monthly intervals in the fall of 1987 and throughout the 1988 growing season. Seed germination in the field in the fall of 1987 was greatest from the buried seed (almost 50 %) while the surface seed exhibited little germination. This germination occurred in response to fall precipitation. Seed on the soil surface was not in contact with moist soil for a sufficient time to stimulate germination, so 80-90 % of this seed had not germinated by freeze-up in 1987. However the surface collected seed had germination of 34 % when transferred to an incubator in the laboratory, indicating environmentally induced dormancy in the field. There was little recruitment from the seed bank occurred in the spring of 1988 in spite of favorable moisture and temperature conditions. Seed on the soil surface remained viable until the 14th month but the buried seed at all depths had either germinated or deteriorated by the 9th month. This study was repeated in 1988, with similar results to date

Longitudinal evaluation of peritoneal macrophage function and activation during CAPD: Maturity, cytokine synthesis and arachidonic acid metabolism

Longitudinal evaluation of peritoneal macrophage function and activation during CAPD: Maturity, cytokine synthesis and arachidonic acid metabolism. The release of cytokines and prostaglandins (PG) by peritoneal macrophages (PMØ) may influence the cytokine network controlling peritoneal inflammation and in the long-term the function of the peritoneum as a dialysis membrane. In the present study, an evaluation of the long-term effects of peritoneal dialysis on the release of cytokines and prostaglandins, and the expression of surface markers of cellular maturation on blood and mononuclear cells has been performed in patients during their first year on CAPD. Spontaneous release of tumour necrosis factor α (TNFα) and interleukin 6 (IL-6) by PMØ, after 4 or 24 hours in culture, increased significantly with time on CAPD, while there was a small but significant decrease in release of prostaglandin E2 (PGE2). Production of TNFα and IL-6 was enhanced following incubation of the cells with lipopolysaccharide (LPS), but the effect of LPS was proportionally greater on blood monocytes than on PMØ. There was a significant increase in the concentrations of PGE2 and 6-keto-prostaglandin F1α in overnight dwell peritoneal dialysis effluent with time on CAPD. The levels of TNFα and IL-6 in uninfected PDE were below the detection limit of the immunoassay over the whole time period studied. Expression of CD15, which correlates with immaturity, by PMØ and blood monocytes increased with time on CAPD, while expression of CD11c, a marker of maturation, decreased on blood monocytes, but did not change significantly on PMØ. There was also a slight increase in expression of transferrin receptor in both PMØ and monocytes, but this did not reach statistical significance. These findings suggest that peritoneal macrophages and blood monocytes isolated from CAPD patients over a one year period become increasingly immature with time, and this is accompanied by a significant modulation of their ability to secrete inflammatory cytokines. Dysregulation of macrophage function may have important consequences with respect to inflammatory processes and the long-term function of the peritoneal membrane in CAPD patients

ADHM/Nahm Construction of Localized Solitons in Noncommutative Gauge Theories

We study the relationship between ADHM/Nahm construction and ``solution generating technique'' of BPS solitons in noncommutative gauge theories. ADHM/Nahm construction and ``solution generating technique'' are the most strong ways to construct exact BPS solitons. Localized solitons are the solitons which are generated by the ``solution generating technique.'' The shift operators which play crucial roles in ``solution generating technique'' naturally appear in ADHM/Nahm construction and we can construct various exact localized solitons including new solitons: localized periodic instantons (=localized calorons) and localized doubly-periodic instantons. Nahm construction also gives rise to BPS fluxons straightforwardly from the appropriate input Nahm data which is expected from the D-brane picture of BPS fluxons. We also show that the Fourier-transformed soliton of the localized caloron in the zero-period limit exactly coincides with the BPS fluxon.Comment: 30 pages, LaTeX, 3 figures; v3: minor changes, references added; v4: references added, version to appear in PR

A Large-Scale Population-Based Analysis of Common Genetic Variation in the Thyroid Hormone Receptor Alpha Locus and Bone

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Vortices, Instantons and Branes

The purpose of this paper is to describe a relationship between the moduli space of vortices and the moduli space of instantons. We study charge k vortices in U(N) Yang-Mills-Higgs theories and show that the moduli space is isomorphic to a special Lagrangian submanifold of the moduli space of k instantons in non-commutative U(N) Yang-Mills theories. This submanifold is the fixed point set of a U(1) action on the instanton moduli space which rotates the instantons in a plane. To derive this relationship, we present a D-brane construction in which the dynamics of vortices is described by the Higgs branch of a U(k) gauge theory with 4 supercharges which is a truncation of the familiar ADHM gauge theory. We further describe a moduli space construction for semi-local vortices, lumps in the CP(N) and Grassmannian sigma-models, and vortices on the non-commutative plane. We argue that this relationship between vortices and instantons underlies many of the quantitative similarities shared by quantum field theories in two and four dimensions.Comment: 32 Pages, 4 Figure

Categorizing Different Approaches to the Cosmological Constant Problem

We have found that proposals addressing the old cosmological constant problem come in various categories. The aim of this paper is to identify as many different, credible mechanisms as possible and to provide them with a code for future reference. We find that they all can be classified into five different schemes of which we indicate the advantages and drawbacks. Besides, we add a new approach based on a symmetry principle mapping real to imaginary spacetime.Comment: updated version, accepted for publicatio

Genetic sharing with cardiovascular disease risk factors and diabetes reveals novel bone mineral density loci

Bone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR) method to identify single nucleotide polymorphisms (SNPs) associated with BMD by leveraging cardiovascular disease (CVD) associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD) at conditional FDR &lt; 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity.</p

Solitons in a Grassmannian sigma-model Coupled to Chern-Simons Term

We propose an exactly solvable Grassmannian sigma-model coupled to the Chern-Simons theory. In the presence of a novel topological term our model admits exact self-dual vortex solutions which are identical to those of pure Grassmannian model, but the topological charge has a physical meaning as a magnetic flux since the gauge field is no longer auxiliary. We also extend the theory to a noncommutative plane and analyze the BPS solutions.Comment: 10+1 pages, No figure, LaTeX; Reference added, Minor changes, to appear in Phys. Rev.