262 research outputs found
Inhibition of proton-transfer steps in transhydrogenase by transition metal ions
AbstractTranshydrogenase couples proton translocation across a bacterial or mitochondrial membrane to the redox reaction between NAD(H) and NADP(H). Purified intact transhydrogenase from Escherichia coli was prepared, and its His tag removed. The forward and reverse transhydrogenation reactions catalysed by the enzyme were inhibited by certain metal ions but a “cyclic reaction” was stimulated. Of metal ions tested they were effective in the order Pb2+>Cu2+>Zn2+=Cd2+>Ni2+>Co2+. The results suggest that the metal ions affect transhydrogenase by binding to a site in the proton-transfer pathway. Attenuated total-reflectance Fourier-transform infrared difference spectroscopy indicated the involvement of His and Asp/Glu residues in the Zn2+-binding site(s). A mutant in which βHis91 in the membrane-spanning domain of transhydrogenase was replaced by Lys had enzyme activities resembling those of wild-type enzyme treated with Zn2+. Effects of the metal ion on the mutant were much diminished but still evident. Signals in Zn2+-induced FTIR difference spectra of the βHis91Lys mutant were also attributable to changes in His and Asp/Glu residues but were much smaller than those in wild-type spectra. The results support the view that βHis91 and nearby Asp or Glu residues participate in the proton-transfer pathway of transhydrogenase
Взаємозв’язок великих кондратьєвських циклів розвитку економіки і системних світових конфліктів
Однією з найважливіших проблем, що постала перед сучасною наукою у зв’язку із стрімким розгортанням глобальної економічної кризи, загостренням світових конфліктів, є вироблення науково обґрунтованих «метричних» експрес прогнозів розвитку суспільства на ближчу і далеку перспективу
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A new foundational economy academy in Wales: scoping and feasibility study
This report conducted a ‘Scoping and Feasibility Study for a new Foundational Economy Academy’ in Wales, during the first quarter of 2022. We explored how to effectively enhance the Foundational Economy (FE) capability of public service practitioners and learn lessons from the celebrated Preston Model. The report conducted primary research and reviewed academic and practitioner literature. All sectors of the economy operate in a Volatile, Uncertain, Complex, Ambiguous (VUCA) world and exogenous shocks are likely to become more frequent. Public service organisations (PSOs) in Wales have had to deal with multiple challenges including COVID-19, Wellbeing of Future Generations Act obligations, 2030 Net Zero targets, social welfare reforms and Brexit repercussions. These challenges are more acute due to increased financial pressures which manifests into ‘having to do more with less’. Key foundational sectors remain resilient during times of crisis, and the foundational economy offers regional economic stability. The Foundational Economy in Wales is growing and is of vital importance to regional development. FE implementation capability is heterogeneous, and the principles of FE not fully understood. This report outlines the nascent literature and details ‘what works’ in terms of developing FE capability, in Wales. We propose a FE Capability Development framework. We also outline the lessons from the celebrated Preston model. Its success came from engaging multiple stakeholders to coproduce an ecosystem of local government, development agencies, cooperatives and trade unions to implement community wealth building principles with the University of Central Lancashire providing academic insights and facilitation. The report recommends establishing a Foundational Economy Academy in Wales to support PSOs to develop FE capability. The FE Academy could develop a repository of content and interventions and act as a quality assurance function. The FE Academy could also contribute to the development of a regional ecosystem that supports public and private sectors to collaborate with policymakers to generate and retain wealth in Wales. In terms of next steps, we suggest a study that systematically maps and reviews available FE learning content and interventions to develop a robust FE knowledge repository would be valuable. The study could also identify gaps in capability across PSOs to develop interventions, in collaboration with PSOs. A pilot FE programme community of practice would be timely to augment FE activity
Toward an internally consistent astronomical distance scale
Accurate astronomical distance determination is crucial for all fields in
astrophysics, from Galactic to cosmological scales. Despite, or perhaps because
of, significant efforts to determine accurate distances, using a wide range of
methods, tracers, and techniques, an internally consistent astronomical
distance framework has not yet been established. We review current efforts to
homogenize the Local Group's distance framework, with particular emphasis on
the potential of RR Lyrae stars as distance indicators, and attempt to extend
this in an internally consistent manner to cosmological distances. Calibration
based on Type Ia supernovae and distance determinations based on gravitational
lensing represent particularly promising approaches. We provide a positive
outlook to improvements to the status quo expected from future surveys,
missions, and facilities. Astronomical distance determination has clearly
reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press
(chapter 8 of a special collection resulting from the May 2016 ISSI-BJ
workshop on Astronomical Distance Determination in the Space Age
Search for single top quarks in the tau+jets channel using 4.8 fb of collision data
We present the first direct search for single top quark production using tau
leptons. The search is based on 4.8 fb of integrated luminosity
collected in collisions at =1.96 TeV with the D0 detector
at the Fermilab Tevatron Collider. We select events with a final state
including an isolated tau lepton, missing transverse energy, two or three jets,
one or two of them tagged. We use a multivariate technique to discriminate
signal from background. The number of events observed in data in this final
state is consistent with the signal plus background expectation. We set in the
tau+jets channel an upper limit on the single top quark cross section of
\TauLimObs pb at the 95% C.L. This measurement allows a gain of 4% in expected
sensitivity for the observation of single top production when combining it with
electron+jets and muon+jets channels already published by the D0 collaboration
with 2.3 fb of data. We measure a combined cross section of
\SuperCombineXSall pb, which is the most precise measurement to date.Comment: 12 pages, 5 figure
Measurement of Z/gamma*+jet+X angular distributions in ppbar collisions at sqrt{s}=1.96 TeV
We present the first measurements at a hadron collider of differential cross
sections for Z+jet+X production in delta phi(Z, jet), |delta y(Z, jet)| and
|y_boost(Z, jet)|. Vector boson production in association with jets is an
excellent probe of QCD and constitutes the main background to many small cross
section processes, such as associated Higgs production. These measurements are
crucial tests of the predictions of perturbative QCD and current event
generators, which have varied success in describing the data. Using these
measurements as inputs in tuning event generators will increase the
experimental sensitivity to rare signals.Comment: Published in Physics Letters B 682 (2010), pp. 370-380. 15 pages, 6
figure
Search for the standard model Higgs boson in tau final states
We present a search for the standard model Higgs boson using hadronically
decaying tau leptons, in 1 inverse femtobarn of data collected with the D0
detector at the Fermilab Tevatron ppbar collider. We select two final states:
tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These
final states are sensitive to a combination of associated W/Z boson plus Higgs
boson, vector boson fusion and gluon-gluon fusion production processes. The
observed ratio of the combined limit on the Higgs production cross section at
the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of
115 GeV.Comment: publication versio
Search for W' bosons decaying to an electron and a neutrino with the D0 detector
This Letter describes the search for a new heavy charged gauge boson W'
decaying into an electron and a neutrino. The data were collected with the D0
detector at the Fermilab Tevatron proton-antiproton Collider at a
center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity
of about 1 inverse femtobarn. Lacking any significant excess in the data in
comparison with known processes, an upper limit is set on the production cross
section times branching fraction, and a W' boson with mass below 1.00 TeV can
be excluded at the 95% C.L., assuming standard-model-like couplings to
fermions. This result significantly improves upon previous limits, and is the
most stringent to date.Comment: submitted to Phys. Rev. Let
Search for a scalar or vector particle decaying into Zgamma in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for a narrow scalar or vector resonance decaying into
Zgamma with a subsequent Z decay into a pair of electrons or muons. The data
for this search were collected with the D0 detector at the Fermilab Tevatron
ppbar collider at a center of mass energy sqrt(s) = 1.96 TeV. Using 1.1 (1.0)
fb-1 of data, we observe 49 (50) candidate events in the electron (muon)
channel, in good agreement with the standard model prediction. From the
combination of both channels, we derive 95% C.L. upper limits on the cross
section times branching fraction (sigma x B) into Zgamma. These limits range
from 0.19 (0.20) pb for a scalar (vector) resonance mass of 600 GeV/c^2 to 2.5
(3.1) pb for a mass of 140 GeV/c^2.Comment: Published by Phys. Lett.
Search for the associated production of a b quark and a neutral supersymmetric Higgs boson which decays to tau pairs
We report results from a search for production of a neutral Higgs boson in
association with a quark. We search for Higgs decays to pairs with
one subsequently decaying to a muon and the other to hadrons. The data
correspond to 2.7fb of \ppbar collisions recorded by the D0 detector
at TeV. The data are found to be consistent with background
predictions. The result allows us to exclude a significant region of parameter
space of the minimal supersymmetric model.Comment: Submitted to Phys. Rev. Letter
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