Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry

We report the first measurement of the low-energy neutron-$^3$He incoherent scattering length using neutron interferometry: $b_i' = (-2.512\pm 0.012{statistical}\pm0.014{systematic})$ fm. This is in good agreement with a recent calculation using the AV18+3N potential. The neutron-$^3$He scattering lengths are important for testing and developing nuclear potential models that include three nucleon forces, effective field theories for few-body nuclear systems, and neutron scattering measurements of quantum excitations in liquid helium. This work demonstrates the first use of a polarized nuclear target in a neutron interferometer.Comment: 4 figure

On surfaces with pg = 2, q = 1 and K2 = 5

We consider minimal surfaces of general type with pg = 2, q = 1 and K2 = 5. We provide a stratification of the corresponding moduli space M and we give some bounds for the number and the dimensions of its irreducible components. © Springer-Verlag 2011

High rate production of polarized 3He with meta-stability exchange method

Keywords: polarized 3He, meta-stability exchange, infrared laserComment: 4 figures, submitted to J. Phys. Soc. Jpn

HERschel Observations of Edge-on Spirals (HEROES). II: Tilted-ring modelling of the atomic gas disks

Context. Edge-on galaxies can offer important insights in galaxy evolution as they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. Aims. In this second HEROES paper we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to constrain the surface density distribution, the rotation curve and the geometry of the gas disks in a homogeneous way. In addition we identify peculiar features and signs of recent interactions. Methods. We construct detailed tilted-ring models of the atomic gas disks based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced archival HI data of NGC 5907, NGC 5529, IC 2531 and NGC 4217. Potential degeneracies between different models are resolved by requiring a good agreement with the data in various representations of the data cubes. Results. From our modelling we find that all but one galaxy are warped along the major axis. In addition, we identify warps along the line of sight in three galaxies. A flaring gas layer is required to reproduce the data only for one galaxy, but (moderate) flares cannot be ruled for the other galaxies either. A coplanar ring-like structure is detected outside the main disk of NGC 4217, which we suggest could be the remnant of a recent minor merger event. We also find evidence for a radial inflow of 15 +- 5 km/s in the disk of NGC 5529, which might be related to the ongoing interaction with two nearby companions. (Abridged)Comment: 39 pages, 38 figures, Accepted for publication in Astronomy & Astrophysic

Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n-3^3He

We report a determination of the n-$^3$He scattering length difference $\Delta b^{\prime} = b_{1}^{\prime}-b_{0}^{\prime} =$ ($-5.411$ $\pm$ $0.031$ (statistical) $\pm$ $0.039$ (systematic)) fm between the triplet and singlet states using a neutron interferometer. This revises our previous result $\Delta b^{\prime} =$ (-5.610 $\pm$ $0.027$ (statistical) $\pm$ $0.032$ (systematic) fm obtained using the same technique in 2008. This revision is due to a re-analysis of the 2008 experiment that includes a more robust treatment of the phase shift caused by magnetic field gradients near the $^3$He cell. Furthermore, we more than doubled our original data set from 2008 by acquiring six months of additional data in 2013. Both the new data set and a re-analysis of the older data are in good agreement. Scattering lengths of low Z isotopes are valued for use in few-body nuclear effective field theories, provide important tests of modern nuclear potential models and in the case of $^3$He aid in the interpretation of neutron scattering from quantum liquids. The difference $\Delta b^{\prime}$ was determined by measuring the relative phase shift between two incident neutron polarizations caused by the spin-dependent interaction with a polarized $^3$He target. The target $^3$He gas was sealed inside a small, flat windowed glass cell that was placed in one beam path of the interferometer. The relaxation of $^3$He polarization was monitored continuously with neutron transmission measurements. The neutron polarization and spin flipper efficiency were determined separately using $^3$He analyzers and two different polarimetry analysis methods. A summary of the measured scattering lengths for n-$^3$He with a comparison to nucleon interaction models is given

Antiphospholipid antibodies and renal transplant: a systematic review and meta-analysis

Objective: To evaluate the effect of antiphospholipid antibodies (aPL) on renal allograft outcome after kidney transplantation. Methods: A systematic search of EMBASE and PubMed databases from inception to July 2018 was run according to PRISMA guidelines; Peto's odds ratio (OR) for rare events was used for the meta-analysis. Results: Our inclusion/exclusion criteria were met by 22 cohort studies having different outcomes: allograft thrombosis (n = 9) and thromboprophylaxis (n = 3), allograft loss from any cause (n = 9), allograft malfunction (n = 3), duration (n = 2), glomerular filtration rate at 1 year (n = 3) and allograft rejection (n = 5). The pooled prevalence of allograft thrombosis and of thrombotic microangiopathy was greater in aPL+ve than negative recipients (10.4% vs 1.7%, p < 0.0001 and 10.2% vs 0%, p = 0.005, respectively). The pooled prevalence of allograft thrombosis was 75% in patients not taking anticoagulation whereas none of the anticoagulated recipients developed thrombosis (p < 0.0001). The pooled prevalence of allograft loss was greater in aPL+ve recipients (28% vs 18% respectively, p < 0.0001); the pooled prevalence of aPL was greater in allograft loss recipients compared to those who did not lose it (51% vs 33%, p < 0.0001). The pooled prevalence of allograft malfunction and rejection was similar in aPL−ve and aPL+ve recipients (32.2% vs 40.3% and 14.9% vs 14.4%, respectively) but graft duration was shorter in aPL+ve than aPL−ve recipients (p = 0.001) and glomerular filtration rate at 1 year was lower in aPL + ve than aPL−ve recipients (p < 0.0001). Conclusion: APL relate strongly to allograft thrombosis, loss and duration but not to allograft malfunction and rejection. Oral antivitamin K anticoagulants effectively prevent allograft thrombosis in aPL recipients. The debate on the role of aPL in renal transplant is limited by the expression of data as percentage of recipients positive for aPL rather than aPL titres in many studies

Incommensurate Charge Density Waves in the adiabatic Hubbard-Holstein model

The adiabatic, Holstein-Hubbard model describes electrons on a chain with step $a$ interacting with themselves (with coupling $U$) and with a classical phonon field \f_x (with coupling \l). There is Peierls instability if the electronic ground state energy F(\f) as a functional of \f_x has a minimum which corresponds to a periodic function with period ${\pi\over p_F}$, where $p_F$ is the Fermi momentum. We consider ${p_F\over\pi a}$ irrational so that the CDW is {\it incommensurate} with the chain. We prove in a rigorous way in the spinless case, when \l,U are small and {U\over\l} large, that a)when the electronic interaction is attractive $U<0$ there is no Peierls instability b)when the interaction is repulsive $U>0$ there is Peierls instability in the sense that our convergent expansion for F(\f), truncated at the second order, has a minimum which corresponds to an analytical and ${\pi\over p_F}$ periodic \f_x. Such a minimum is found solving an infinite set of coupled self-consistent equations, one for each of the infinite Fourier modes of \f_x.Comment: 16 pages, 1 picture. To appear Phys. Rev.

Neutron Beam Effects on Spin Exchange Polarized He-3

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal-spin-exchange polarized He-3 cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable He-3 polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as the square root of the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the recombination-limited ion concentration, but is much larger than expected from earlier work.Comment: submitted to Physical Review Letter