3,547 research outputs found
1933 and 1977 - Some Expansion Policy Problems in Cases of Unbalanced Domestic and International Economic Relations
Lecture to the memory of Alfred Nobel, December 8, 1977international trade;
Supernovae feedback propagation: the role of turbulence
Modelling the propagation of supernova (SN) bubbles, in terms of energy,
momentum and spatial extent, is critical for simulations of galaxy evolution
which do not capture these scales. To date, small scale models of SN feedback
predict that the evolution of above-mentioned quantities can be solely
parameterised by average quantities of the surrounding gas, such as density.
However, most of these studies neglect the turbulent motions of this medium. In
this paper, we study the propagation and evolution of SNe in turbulent
environments. We confirm that the time evolution of injected energy and
momentum can be characterised by the average density. However, the details of
the density structure of the interstellar medium play a crucial role in the
spatial extent of the bubble, even at a given average density. We demonstrate
that spherically symmetric models of SN bubbles do not model well their spatial
extent, and therefore cannot not be used to design sub-grid models of SNe
feedback at galactic and cosmological scales.Comment: Accepted by MNRA
Solvent promoted reversible cyclometalation in a tethered NHC iridium complex
Reaction of [Ir(COD)(py–ItBu)]+ (py–ItBu = 3-tert-butyl-1-picolylimidazol-2-ylidene) with acetonitrile results in reversible intramolecular C–H bond activation of the NHC ligand and formation of [Ir(η2:η1-C8H13)(py–ItBu′)(NCMe)]+. Coordinated COD acts as an internal hydride acceptor and acetonitrile coordination offsets the otherwise unfavourable thermodynamics of the process
Promoter methylation in the PTCH gene in cervical epithelial cancer and ovarian cancer tissue as studied by eight novel Pyrosequencing assays
DNA methylation status in the CpG sites of promoter regions in cancer-related genes, such as PTCH, has traditionally been investigated using either dye-terminator sequencing or methylation-specific PCR. We aimed to study the PTCH gene promoter methylation in gynecological cancers, with a method that gives a quantitative measure of the methylation status of the promoter region of the studied gene, and for this purpose, we designed novel Pyrosequencing based assays. Bisulfite-treated genomic DNA (bsDNA)was amplified by standard PCR and applied to novel Pyrosequencing assays, in order to measure the methylated fraction(%) at each CpG site of the PTCH gene promoter. We analyzed 22 squamous cell cervical cancer tissue specimens (11 with good and 11 with poor outcomes after radiotherapy)and 5 ovarian cancer tissue specimens matched with 5 normal ovarian tissue specimens. Six optimized PCR protocols which generated 8 Pyrosequencing assays covering 63 CpG sites in the promoter regions 1 and 2 as well as the previously unanalyzed promoter region 3 in the PTCH gene were developed. The 27 tumor tissue specimens and 5 normal tissues did not show any methylation within any of the 63 CpG sites. Our data suggest that methylation of the PTCH promoter is not a high-prevalence feature of squamous cell cervical cancer or ovarian cancer, but Pyrosequencing assays are a good method for studying promoter methylation
Tunable-angle wedge transducer for improved acoustophoretic control in a microfluidic chip
We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 mu m diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation.</p
Assessing the Control-Theory
As the first cases before the ICC proceed to the Appeals Chamber, the judges ought to critically evaluate the merits and demerits of the control-theory of perpetratorship and its related doctrines. The request for a possible re-characterization of the form of responsibility in the case of Katanga and the recent acquittal of Ngudjolo can be taken as indications that the control-theory, is problematic as a theory of liability. The authors, in a spirit of constructive criticism, invite the ICC Appeals Chamber to take this unique opportunity to reconsider or improve the control-theory as developed by the Pre-Trial Chambers in the Lubanga and Katanga cases
Decavanadate, decaniobate, tungstate and molybdate interactions with sarcoplasmic reticulum Ca2+-ATPase: quercetin prevents cysteine oxidation by vanadate but does not reverse ATPase inhibition
Recently we demonstrated that the decavanadate (V10) ion is a stronger Ca2+-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V10 interaction is not affected by any of the protein conformations that occur during the process of calcium translocation
(i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the present study, we further explore this subject, and we can now show that the decaniobate ion, [Nb10 = Nb10O28]6−, is a useful tool
in deducing the interaction and the non-competitive Ca2+-ATPase inhibition by the decavanadate ion [V10 = V10O28]6−. Moreover, decavanadate and vanadate induce protein cysteine oxidation whereas no effects were detected for the decaniobate, tungstate or molybdate ions. The presence of the antioxidant quercetin prevents cysteine oxidation, but not ATPase inhibition, by vanadate or decavanadate. Definitive
V(IV) EPR spectra were observed for decavanadate in the presence of sarcoplasmic reticulum Ca2+-
ATPase, indicating a vanadate reduction at some stage of the protein interaction. Raman spectroscopy clearly shows that the protein conformation changes that are induced by V10, Nb10 and vanadate are different from the ones induced by molybdate and tungstate monomer ions. Here, Mo and W cause
changes similar to those by phosphate, yielding changes similar to the E1P protein conformation. The putative reduction of vanadium(V) to vanadium(IV) and the non-competitive binding of the V10 and Nb10
decametalates may explain the differences in the Raman spectra compared to those seen in the presence of molybdate or tungstate. Putting it all together, we suggest that the ability of V10 to inhibit the Ca2+-
ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation. These results contribute to the understanding and application of these families of mono- and
polyoxometalates as effective modulators of many biological processes, particularly those associated with calcium homeostasis.MA thanks CCMAR; LAEBC and MPMM thank QFM-UC for
financial support. CAO is grateful for a QEII fellowship and
Discovery Project grant (DP110105530) from the Australian
Research Council. WHC acknowledges support from the U.S.
Department of Energy Office of Basic Energy Science via grant
DE-FG02-05ER15693, the National Science Foundation via
EAR-0814242 and an NSF CCI grant through the Center for
Sustainable Materials Chemistry, number CHE-1102637
Characterization of decavanadate and decaniobate solutions by Raman spectroscopy
The decaniobate ion, (Nb10 = [Nb10O28]6−) being isoelectronic and isostructural with the decavanadate
ion (V10 = [V10O28]6−), but chemically and electrochemically more inert, has been useful in advancing the
understanding of V10 toxicology and pharmacological activities. In the present study, the solution chemistry
of Nb10 and V10 between pH 4 and 12 is studied by Raman spectroscopy. The Raman spectra of V10
show that this vanadate species dominates up to pH 6.45 whereas it remains detectable until pH 8.59,
which is an important range for biochemistry. Similarly, Nb10 is present between pH 5.49 and 9.90 and
this species remains detectable in solution up to pH 10.80. V10 dissociates at most pH values into smaller
tetrahedral vanadate oligomers such as V1 and V2, whereas Nb10 dissociates into Nb6 under mildly (10 >
pH > 7.6) or highly alkaline conditions. Solutions of V10 and Nb10 are both kinetically stable under basic pH
conditions for at least two weeks and at moderate temperature. The Raman method provides a means of
establishing speciation in the difficult niobate system and these findings have important consequences for
toxicology activities and pharmacological applications of vanadate and niobate polyoxometalates
Role of micropillar arrays in cell rolling dynamics
In this study, we present a role of arrayed micropillar structures in cell rolling dynamics. Cell rolling on a ligand coated surface as a means of cell separation was demonstrated using a micropillar-integrated microfluidic channel. This approach allows the separation of cells according to characteristic surface properties, regardless of cell size. In these experiments, different moving trajectories of the cells between a ligand-coated micropost structure and a 1% BSA coated micropost structure were observed using sequential images. Based on the analysis of the angle of travel of cells in the trajectory, the average angles of travel on the ligand-coated microposts were 1.5 degrees and -3.1 degrees on a 1% BSA-coated micropost structure. The overall force equivalent applied to a cell can be analyzed to predict the cell rolling dynamics when a cell is detached. These results show that it will be possible to design chip geometry for delicate operations and to separate target cells. Furthermore, we believe that these control techniques based on a ligand coated micropillar surface can be used for enhancing cell rolling-based separation in a faster and more continuous manner.ope
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