Classifying the tropospheric precursor patterns of sudden stratospheric warmings

Classifying the tropospheric precursor patterns of sudden stratospheric warmings (SSWs) may provide insight into the different physical mechanisms of SSWs. Based on 37 major SSWs during the 1958–2014 winters in the ERA reanalysis data sets, the self-organizing maps method is used to classify the tropospheric precursor patterns of SSWs. The cluster analysis indicates that one of the precursor patterns appears as a mixed pattern consisting of the negative-signed Western Hemisphere circulation pattern and the positive phase of the Pacific-North America pattern. The mixed pattern exhibits higher statistical significance as a precursor pattern of SSWs than other previously identified precursors such as the subpolar North Pacific low, Atlantic blocking, and the western Pacific pattern. Other clusters confirm northern European blocking and Gulf of Alaska blocking as precursors of SSWs. Linear interference with the climatological planetary waves provides a simple interpretation for the precursors. The relationship between the classified precursor patterns of SSWs and ENSO phases as well as the types of SSWs is discussed

The role of synoptic waves in the formation and maintenance of the Western Hemisphere circulation pattern

Previous studies have demonstrated that the NAO, the leading mode of atmospheric low-frequency variability over the North Atlantic, could be linked to Northeast Pacific climate variability via the downstream propagation of synoptic waves. In those studies, the NAO and the Northeast Pacific climate variability are considered as two separate modes that explain the variance over the North Atlantic sector and the East Pacific–North America sector, respectively. A newly identified low-frequency atmospheric regime — the Western Hemisphere (WH) circulation pattern—provides a unique example of a mode of variability that accounts for variance over the whole North Atlantic–North America– North Pacific sector. The role of synoptic waves in the formation and maintenance of the WH pattern is investigated using the ERA reanalysis datasets. Persistent WH events are characterized by the propagation of quasi-stationary Rossby waves across the North Pacific–North America–North Atlantic regions and by associated storm track anomalies. The eddy-induced low-frequency height anomalies maintain the anomalous low-frequency ridge over the Gulf of Alaska, which induces more equatorward propagation of synoptic waves on its downstream side. The eddy forcing favors the strengthening of the mid-latitude jet and the deepening of the mid-high latitude trough over the North Atlantic, whereas the deepening of the trough over eastern North America mostly arises from the quasi-stationary waves propagating from the North Pacific. A case study for the 2013/14 winter is examined to illustrate the downstream development of synoptic waves. The roles of synoptic waves in the formation and maintenance of the WH pattern and in linking the Northeast Pacific ridge anomaly with the NAO are discussed

Insights into biofilm dispersal regulation from the crystal structure of the PAS-GGDEF-EAL region of RbdA from Pseudomonas aeruginosa

© 2018 American Society for Microbiology. RbdA is a positive regulator of biofilm dispersal of Pseudomonas aeruginosa. Its cytoplasmic region (cRbdA) comprises an N-terminal Per-ARNT-Sim (PAS) domain followed by a diguanylate cyclase (GGDEF) domain and an EAL domain, whose phosphodiesterase activity is allosterically stimulated by GTP binding to the GGDEF domain. We report crystal structures of cRbdA and of two binary complexes: one with GTP/Mg 2+ bound to the GGDEF active site and one with the EAL domain bound to the c-di-GMP substrate. These structures unveil a 2-fold symmetric dimer stabilized by a closely packed N-terminal PAS domain and a noncanonical EAL dimer. The autoinhibitory switch is formed by an α-helix (S-helix) immediately N-terminal to the GGDEF domain that interacts with the EAL dimerization helix (α6-E) of the other EAL monomer and maintains the protein in a locked conformation. We propose that local conformational changes in cRbdA upon GTP binding lead to a structure with the PAS domain and S-helix shifted away from the GGDEF-EAL domains, as suggested by small-angle X-ray scattering (SAXS) experiments. Domain reorientation should be facilitated by the presence of an α-helical lever (H-helix) that tethers the GGDEF and EAL regions, allowing the EAL domain to rearrange into an active dimeric conformation

Integrin-mediated traction force enhances paxillin molecular associations and adhesion dynamics that increase the invasiveness of tumor cells into a three-dimensional extracellular matrix.

Metastasis requires tumor cells to navigate through a stiff stroma and squeeze through confined microenvironments. Whether tumors exploit unique biophysical properties to metastasize remains unclear. Data show that invading mammary tumor cells, when cultured in a stiffened three-dimensional extracellular matrix that recapitulates the primary tumor stroma, adopt a basal-like phenotype. Metastatic tumor cells and basal-like tumor cells exert higher integrin-mediated traction forces at the bulk and molecular levels, consistent with a motor-clutch model in which motors and clutches are both increased. Basal-like nonmalignant mammary epithelial cells also display an altered integrin adhesion molecular organization at the nanoscale and recruit a suite of paxillin-associated proteins implicated in invasion and metastasis. Phosphorylation of paxillin by Src family kinases, which regulates adhesion turnover, is similarly enhanced in the metastatic and basal-like tumor cells, fostered by a stiff matrix, and critical for tumor cell invasion in our assays. Bioinformatics reveals an unappreciated relationship between Src kinases, paxillin, and survival of breast cancer patients. Thus adoption of the basal-like adhesion phenotype may favor the recruitment of molecules that facilitate tumor metastasis to integrin-based adhesions. Analysis of the physical properties of tumor cells and integrin adhesion composition in biopsies may be predictive of patient outcome

Inhalation therapy in the next decade : Determinants of adherence to treatment in asthma and COPD

Peer reviewedPublisher PD

Coordination complexes of thiazyl rings: Synthesis, structure and DFT computational analysis of CpCr(CO)x (x = 2,3) complexes of fluorinated and non-fluorinated 1lamda^3-1,2,4,6-thiatriazinyls, with differing Cr—S bond orders.

Sherpa Romeo green journal. Permission to archive accepted author manuscript.Reaction of [3,5-Ph2-C2N3S]2 with [CpCr(CO)3]2 in toluene at RT forms an adduct via a Cr—S bond, formulated as CpCr(CO)3SN3C2Ph2, which has fitting NMR, IR and combustion analysis data. The structure was determined by a single-crystal X-ray structure diffraction study (P21/n, a = 8.4611(17)Å; b = 20.509(4) Å, c = 11.757(2) Å, = 104.453(7)°). The Cr—S bond-length = 2.4908(11) Å corresponds to a bond-order of 1.0 from > 90 values for CpCr(CO)x or Cp*Cr(CO)x moieties (x = 2,3) bonded to S which are used to establish a Pauling-type bond order scale specific to this class of compounds. Similar reactions of fluorinated thiatriazinyls derived from [3-Ph-5-CF3-C2N3S]2 or [4-MeOC6H4-5-CF3-C2N3S]2 are accompanied by the loss of CO to produce CpCr(CO)2SN3C2PhCF3 (P, a = 8.0929(8) Å; b = 10.3160(10) Å, c = 11.2405(11), = 70.032(2)°, = 72.076(2)°, = 82.375(2)° ) and CpCr(CO)2SN3(CCF3)(C6H4OCH3) (P21/c, a = 8.1311(7)Å; b = 24.284(2) Å, c = 9.1025(8) Å, = 97.218(2)°), also fully characterized by spectroscopy and crystallography. Their measured Cr—S bond-lengths, 2.2987(14) Å and 2.2965(11) Å, correspond to bond orders of 1.5. (U/R)B3PW91/6-311+G(2df,2p)//B3PW91/6-31G(2d,p) hybrid DFT calculations show that the tricarbonyl complex has an unusual bond. However, the dicarbonyl complexes of the fluorinated thiatriazinyls are -bonded.Ye