Ex vivo machine perfusion: current applications and future directions in liver transplantation

Background: Liver transplantation is the only curative treatment option for end-stage liver disease; however, its use remains limited due to a shortage of suitable organs. In recent years, ex vivo liver machine perfusion has been introduced to liver transplantation, as a means to expand the donor organ pool. Purpose: To present a systematic review of prospective clinical studies on ex vivo liver machine perfusion, in order to assess current applications and highlight future directions. Methods: A systematic literature search of both PubMed and ISI web of science databases as well as the ClinicalTrials.gov registry was performed. Results: Twenty-one articles on prospective clinical trials on ex vivo liver machine perfusion were identified. Out of these, eight reported on hypothermic, eleven on normothermic, and two on sequential perfusion. These trials have demonstrated the safety and feasibility of ex vivo liver machine perfusion in both standard and expanded criteria donors. Currently, there are twelve studies enrolled in the clinicaltrials.gov registry, and these focus on use of ex vivo perfusion in extended criteria donors and declined organs. Conclusion: Ex vivo liver machine perfusion seems to be a suitable strategy to expand the donor pool for liver transplantation and holds promise as a platform for reconditioning diseased organs

Search for heavy Majorana neutrinos in mu+/- mu+/- + jets events in proton-proton collisions at sqrt(s) = 8 TeV

A search is performed for heavy Majorana neutrinos (N) using an event signature defined by two muons of the same charge and two jets (mu+/- mu+/- jj). The data correspond to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV, collected with the CMS detector at the CERN LHC. No excess of events is observed beyond the expected standard model background and upper limits are set on abs(V[mu,N])^2 as a function of Majorana neutrino mass m[N] for masses in the range of 40-500 GeV, where V[mu,N] is the mixing element of the heavy neutrino with the standard model muon neutrino. The limits obtained are abs(V[mu,N])^2 < 0.00470 for m[N] = 90 GeV, abs(V[mu,N])^2 < 0.0123 for m[N] = 200 GeV, and abs(V[mu,N])^2 < 0.583 for m[N] = 500 GeV. These results extend considerably the regions excluded by previous direct searches

Measurement of transverse momentum relative to dijet systems in PbPb and pp collisions at sNN=2.76\sqrt{s_{NN}} = 2.76 TeV

An analysis of dijet events in PbPb and pp collisions is performed to explore the properties of energy loss by partons traveling in a quark-gluon plasma. Data are collected at a nucleon-nucleon center-of-mass energy of 2.76 TeV at the LHC. The distribution of transverse momentum (pT) surrounding dijet systems is measured by selecting charged particles in different ranges of pT and at different angular cones of pseudorapidity and azimuth. The measurement is performed as a function of centrality of the PbPb collisions, the pT asymmetry of the jets in the dijet pair, and the distance parameter R used in the anti-kt jet clustering algorithm. In events with unbalanced dijets, PbPb collisions show an enhanced multiplicity in the hemisphere of the subleading jet, with the pT imbalance compensated by an excess of low-pT particles at large angles from the jet axes

Observation of the decay B+→ψ(2S)ϕ(1020)K+B^+ \to \psi(2S) \phi(1020) K^+ in pp collisions at s=\sqrt s = 8 TeV

The decay B+→ψ(2S)ϕ(1020)K$^+$ is observed for the first time using data collected from pp collisions at $\sqrt s =$ 8TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.6 fb$^{−1}$ . The branching fraction of this decay is measured, using the mode B+→ψ(2S)K$^+$ as normalization, to be (4.0±0.4(stat)±0.6(syst)±0.2(B))×10$^{−6}$ , where the third uncertainty is from the measured branching fraction of the normalization channel

Y(nS) polarizations versus particle multiplicity in pp collisions at sqrt(s) = 7 TeV

The polarizations of the Y(1S), Y(2S), and Y(3S) mesons are measured as a function of the charged particle multiplicity in proton-proton collisions at sqrt(s) = 7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The results are extracted from the dimuon decay angular distributions, in two ranges of Y(nS) transverse momentum (10-15 and 15-35 GeV), and in the rapidity interval abs(y)<1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the Y(2S) and Y(3S) cases

Mechanical stability of the CMS strip tracker measured with a laser alignment system

The CMS tracker consists of 206 square meters of silicon strip sensors assembled on carbon fibre composite structures and is designed for operation in the temperature range from -25 to +25 degrees C. The mechanical stability of tracker components during physics operation was monitored with a few micron resolution using a dedicated laser alignment system as well as particle tracks from cosmic rays and hadron-hadron collisions. During the LHC operational period of 2011-2013 at stable temperatures, the components of the tracker were observed to experience relative movements of less than 30 microns. In addition, temperature variations were found to cause displacements of tracker structures of about 2 microns/degree C, which largely revert to their initial positions when the temperature is restored to its original value