Boundary Limitation of Wavenumbers in Taylor-Vortex Flow

We report experimental results for a boundary-mediated wavenumber-adjustment mechanism and for a boundary-limited wavenumber-band of Taylor-vortex flow (TVF). The system consists of fluid contained between two concentric cylinders with the inner one rotating at an angular frequency $\Omega$. As observed previously, the Eckhaus instability (a bulk instability) is observed and limits the stable wavenumber band when the system is terminated axially by two rigid, non-rotating plates. The band width is then of order $\epsilon^{1/2}$ at small $\epsilon$ ($\epsilon \equiv \Omega/\Omega_c - 1$) and agrees well with calculations based on the equations of motion over a wide $\epsilon$-range. When the cylinder axis is vertical and the upper liquid surface is free (i.e. an air-liquid interface), vortices can be generated or expelled at the free surface because there the phase of the structure is only weakly pinned. The band of wavenumbers over which Taylor-vortex flow exists is then more narrow than the stable band limited by the Eckhaus instability. At small $\epsilon$ the boundary-mediated band-width is linear in $\epsilon$. These results are qualitatively consistent with theoretical predictions, but to our knowledge a quantitative calculation for TVF with a free surface does not exist.Comment: 8 pages incl. 9 eps figures bitmap version of Fig

A Mutation in the SUV39H2 Gene in Labrador Retrievers with Hereditary Nasal Parakeratosis (HNPK) Provides Insights into the Epigenetics of Keratinocyte Differentiation.

Peer reviewe

Mapping of HNPK in Labrador Retrievers.

<p>(A) A genome-wide association study using 13 cases and 23 controls indicates a strong signal with multiple associated SNPs on CFA 2. (B) The detailed view of CFA 2 delineates an associated interval of ∼4 Mb. (C) Homozygosity mapping. Each horizontal bar corresponds to one of the 13 analyzed cases. Homozygous regions with shared alleles are shown in black. A shared homozygous interval of ∼1.6 Mb delineates the exact boundaries of the critical interval from 20,818,258–22,414,948 bp (CanFam 3.1 assembly). (D) Gene content of the corresponding human interval on HSA 10 (NCBI annotation, genome build 37.5).</p

Variants detected by whole genome re-sequencing of an affected Labrador Retriever.

a<p>The sequences were compared to the reference genome (CanFam 3.1) from a Boxer. Only variants that were homozygous in the affected Labrador Retriever are reported.</p

Four non-synonymous variants in the critical interval of an HNPK affected Labrador Retriever with respect to the Boxer reference genome (CanFam 3.1).

a<p>Subsequent analyses of the original Sanger reads from the dog genome project revealed that this is not a true variant, but rather an error in the reference genome assembly (data not shown).</p

Evolutionary conservation of the asparagine residue at position 324 in the SUV39H2 protein.

<p>Position 324 within the catalytically active SET domain is perfectly conserved across vertebrates in all known SUV39H2 orthologs. In the lower part of the alignment the sequences of closely related paralogous histone methyltransferases with similar substrate specificity also demonstrate conservation of the asparagine at this position. The sequences were derived from the following database accessions: <i>C. lupus</i> SUV39H2 XP_535179.2, <i>H. sapiens</i> SUV39H2 NP_001180353.1, <i>B. taurus</i> SUV39H2 NP_001032556.1, <i>M. musculus</i> Suv39h2 NP_073561.2, <i>G. gallus</i> SUV39H2 NP_001026541.1, <i>X. laevis</i> suv39h2 NP_001091337.1, <i>H. sapiens</i> SUV39H1 NP_003164.1, <i>H. sapiens</i> EHMT1 NP_079033.4, <i>H. sapiens</i> EHMT2 NP_006700.3, <i>H. sapiens</i> SETDB1 NP_001138887.1, <i>H. sapiens</i> SETDB2 NP_114121.2.</p

Nasal planum tissue of an HNPK affected and a non-affected Labrador Retriever.

<p>(A) Hematoxylin and eosin (HE) staining of an HNPK affected dog shows diffuse parakeratotic hyperkeratosis, hydropic keratinocytes in upper epidermal layers (black arrows), epidermal lymphocytic exocytosis, and a perivascular dermal lymphocytic infiltrate. The formation of elongated and sometimes fused slim rete pegs in the affected dog contributes to the thickening of the epidermis (the boundary of one rete peg is indicated by a white dashed line, one fusion is indicated by the white arrow). (B) HE staining of a control dog. (C–F) Immunodetection of desmoglein 1 (DSG1, green) in two different magnifications. Nuclei are counterstained with Hoechst 33258 (blue). No visible differences in the DSG1 staining patterns are present between HNPK affected and control dog. Scale bar = 100 µm for HE/DSG1 100× and 25 µm for DSG1 400×.</p