125 research outputs found
A membrane’s blueprint: in silico investigation of fluid flow and molecular transport as a function of membrane design parameters in organ-on-a-chip
Following the rapid growth of Organ-on-a-Chip (OoaC) technology, porous membranes have become essential components for in vitro tissue barrier models. Nonetheless, literature highlights lacking knowledge on their integration and effect on microfluidic devices. Therefore, we conducted finite element modelling (FEM) to characterize the influence of membrane, channel geometry, flow and diffusion parameters, in modelling flow rate, shear stress, transient transport and steady state molecular concentration. This analysis was performed for four different conditions based on single channel (SCP) and parallel perfusion (PP). It was found that membrane and geometry parameters are crucial in determining flow and shear for SCP. However, for PP, flow and shear are predominantly governed by the inlet flow rate. Although the transient behaviour is well-controlled within SCP and PP, only PP allows modelling the steady state concentration distribution. It is highlighted that: (1) the pore radius has great influence on flow and shear; (2) a shallow cell channel and a long membrane are capable of establishing different levels of shear on opposing surfaces of the same channel; (3) the membrane thickness, membrane length, height of the cell and flow channels, and inlet flow rate provide good control over transient transport; (4) the membrane length and inlet flow rate enable changing the concentration from a uniform distribution to a complete heterogeneous state across the device. Experimental assays were performed to support the FEM and evidence its significance for OoaC applications. Ultimately, extensive, and systematic guidelines are provided on designing future OoaC devices with integrated porous membranes
The Critical Care Society of Southern Africa consensus statement on ICU triage and rationing (ConICTri)
BACKGROUND: In South Africa (SA), intensive care is faced with the challenge of resource scarcity as well as an increasing demand for intensive
care unit (ICU) services. ICU services are expensive, and practitioners in low- to middle-income countries experience daily the consequences
of limited resources. Critically limited resources necessitate that rationing and triage (prioritisation) decisions are frequently necessary in SA,
particularly in the publicly funded health sector.
PURPOSE: The purpose of this consensus statement is to examine key questions that arise when considering the status of ICU resources in SA,
and more specifically ICU admission, rationing and triage decisions. The accompanying guideline in this issue is intended to guide frontline
triage policy and ensure the best utilisation of intensive care in SA, while maintaining a fair distribution of available resources. Fair and efficient
triage is important to ensure the ongoing provision of high-quality care to adult patients referred for intensive care.
RECOMMENDATIONS: In response to 14 key questions developed using a modified Delphi technique, 29 recommendations were formulated
and graded using an adapted GRADE score. The 14 key questions addressed the status of the provision of ICU services in SA, the degree of
resource restriction, the efficiency of resource management, the need for triage, and how triage could be most justly implemented. Important
recommendations included the need to formally recognise and accurately quantify the provision of ICU services in SA by national audit;
actively seek additional resources from governmental bodies; consider methods to maximise the efficiency of ICU care; evaluate lower level of
care alternatives; develop a triage guideline to assist policy-makers and frontline practitioners to implement triage decisions in an efficient and
fair way; measure and audit the consequence of triage; and promote research to improve the accuracy and consistency of triage decisions. The
consensus document and guideline should be reviewed and revised appropriately within 5 years.
CONCLUSIONS: In recognition of the absolute need to limit patient access to ICU because of the lack of sufficient intensive care resources in public
hospitals, recommendations and a guideline have been developed to guide policy-making and assist frontline triage decision-making in SA. These
documents are not a complete plan for quality practice but rather the beginning of a long-term initiative to engage clinicians, the public and
administrators in appropriate triage decision-making, and promote systems that will ultimately maximise the efficient and fair use of available
ICU resources.http://www.samj.org.zapm2020SurgeryCritical Car
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.
Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV
We present final searches of the anomalous gammaWW and ZWW trilinear gauge
boson couplings from WW and WZ production using lepton plus dijet final states
and a combination with results from Wgamma, WW, and WZ production with leptonic
final states. The analyzed data correspond to up to 8.6/fb of integrated
luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96
TeV. We set the most stringent limits at a hadron collider to date assuming two
different relations between the anomalous coupling parameters
Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2
TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154,
-0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization,
and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings
parameterization. We also present the most stringent limits of the W boson
magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL
Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV
We present the first measurement of the inclusive three-jet differential
cross section as a function of the invariant mass of the three jets with the
largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96
TeV. The measurement is made in different rapidity regions and for different
jet transverse momentum requirements and is based on a data set corresponding
to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at
the Fermilab Tevatron Collider. The results are used to test the three-jet
matrix elements in perturbative QCD calculations at next-to-leading order in
the strong coupling constant. The data allow discrimination between
parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected
chi2 values for NNPD
Search for pair production of the scalar top quark in muon+tau final states
We present a search for the pair production of scalar top quarks
(), the lightest supersymmetric partners of the top quarks, in
collisions at a center-of-mass energy of 1.96 TeV, using data
corresponding to an integrated luminosity of {7.3 } collected with the
\dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is
assumed to decay into a quark, a charged lepton, and a scalar neutrino
(). We investigate final states arising from and
. With no significant excess of events observed above the
background expected from the standard model, we set exclusion limits on this
production process in the (,) plane.Comment: Submitted to Phys. Lett.
Measurements of inclusive W+jets production rates as a function of jet transverse momentum in ppbar collisions at sqrt{s}=1.96 TeV
This Letter describes measurements of inclusive W (--> e nu) + n jet cross
sections (n = 1-4), presented as total inclusive cross sections and
differentially in the nth jet transverse momentum. The measurements are made
using data corresponding to an integrated luminosity of 4.2 fb-1 collected by
the D0 detector at the Fermilab Tevatron Collider, and achieve considerably
smaller uncertainties on W +jets production cross sections than previous
measurements. The measurements are compared to next-to-leading order
perturbative QCD (pQCD) calculations in the n =1-3 jet multiplicity bins and to
leading order pQCD calculations in the 4-jet bin. The measurements are
generally in agreement with pQCD predictions, although certain regions of phase
space are identified where the calculations could be improved
Measurement of spin correlation in ttbar production using dilepton final states
We measure the correlation between the spin of the top quark and the spin of
the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final
states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96
TeV, where l is an electron or muon. The data correspond to an integrated
luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab
Tevatron collider. The correlation is extracted from the angles of the two
leptons in the t and tbar rest frames, yielding a correlation strength C=
0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction within two
standard deviations, but also in agreement with the no correlation hypothesis.Comment: 10 pages, 3 figures, submitted to PL
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