bluuebunny/crossref_metadata_2025 huggingface dataset:
Two dimensional super QCD on a lattice
Authors: Catterall Simon , Veernala Aarti
Published: March 2018

We construct a lattice theory with one exact supersymmetry which consists of fields transforming in both the adjoint and fundamental representations of a U(Nc) gauge group. In addition to gluons and gluinos, the theory contains Nf flavors of fermion in the fundamental representation along with their scalar partners and is invariant under a global U(Nf) flavor symmetry. The lattice action contains an additional Fayet-Iliopoulos term which can be used to generate a scalar potential. We perform numerical simulations that corroborate the theoretical expectation that supersymmetry is spontaneously broken for Nf<Nc.
Spectroscopy of the BSM sextet model
Authors: Fodor Zoltan , Holland Kieran , Kuti Julius , Nogradi Daniel , Wong Chik Him
Published: March 2018

As part of our ongoing lattice study of SU(3) gauge theory with two flavors of fermions in the two-index symmetric representation (the sextet model), we present the current status of the pseudoscalar particle spectrum. We use a mixed action approach based on the gradient flow to control lattice artifacts, allowing a simultaneous extrapolation to the chiral and continuum limits. We find strong evidence that the pseudoscalar is a Goldstone boson state, with spontaneously broken chiral symmetry and a non-zero Goldstone decay constant in the chiral limit. In agreement with our study of the gauge coupling β function, we find the sextet model appears to be a near-conformal gauge theory and serves as a prototype of the composite Higgs BSM template.
A new method for the beta function in the chiral symmetry broken phase
Authors: Fodor Zoltan , Holland Kieran , Kuti Julius , Nogradi Daniel , Him Wong Chik
Published: March 2018

We describe a new method to determine non-perturbatively the beta function of a gauge theory using lattice simulations in the p-regime of the theory. This complements alternative measurements of the beta function working directly at zero fermion mass and bridges the gap between the weak coupling perturbative regime and the strong coupling regime relevant to the mass spectrum of the theory. We apply this method to SU(3) gauge theory with two fermion flavors in the 2-index symmetric (sextet) representation. We find that the beta function is small but non-zero at the renormalized coupling value g2 = 6.7, consistent with our previous independent investigation using simulations directly at zero fermion mass. The model continues to be a very interesting explicit realization of the near-conformal composite Higgs paradigm which could be relevant for Beyond Standard Model phenomenology.
Performance Portability Strategies for Grid C++ Expression Templates
Authors: Boyle Peter A. , Clark M.A. , DeTar Carleton , Lin Meifeng , Rana Verinder , Vaquero Avilés-Casco Alejandro
Published: March 2018

One of the key requirements for the Lattice QCD Application Development as part of the US Exascale Computing Project is performance portability across multiple architectures. Using the Grid C++ expression template as a starting point, we report on the progress made with regards to the Grid GPU offloading strategies. We present both the successes and issues encountered in using CUDA, OpenACC and Just-In-Time compilation. Experimentation and performance on GPUs with a SU(3)×SU(3) streaming test will be reported. We will also report on the challenges of using current OpenMP 4.x for GPU offloading in the same code.
Lattice QCD Application Development within the US DOE Exascale Computing Project
Authors: Brower Richard , Christ Norman , DeTar Carleton , Edwards Robert , Mackenzie Paul
Published: March 2018

In October, 2016, the US Department of Energy launched the Exascale Computing Project, which aims to deploy exascale computing resources for science and engineering in the early 2020’s. The project brings together application teams, software developers, and hardware vendors in order to realize this goal. Lattice QCD is one of the applications. Members of the US lattice gauge theory community with significant collaborators abroad are developing algorithms and software for exascale lattice QCD calculations. We give a short description of the project, our activities, and our plans.
Dirac spectral density and mass anomalous dimension in 2+1 flavor QCD
Authors: Nakayama Katsumasa , Hashimoto Shoji , Fukaya Hidenori
Published: March 2018

We compute the Dirac spectral density of QCD in a wide range of eigenvalues by using a stochastic method. We use 2+1 flavor lattice ensembles generated with Mobius domain-wall fermion at three lattice spacings (a = 0:083; 0:055; 0:044 fm) to estimate the continuum limit. The discretization effect can be minimized by a generalization of the valence domain-wall fermion. The spectral density at relatively high eigenvalues can be matched with perturbation theory. We compare the lattice results with the perturbative expansion available to O(α4s).
Fierz transformations and renormalization schemes for fourquark operators
Authors: Garron Nicolas
Published: March 2018

It has been shown that the choice of renormalization scheme is crucial for four-quark operators, in particular for neutral kaon mixing beyond the Standard Model. In the context of SMOM schemes, the choice of projector is not unique and is part of the definition of the renormalisation scheme. I present the non-diagonal Fierz relations which relate some of these projectors.
Local multiboson factorization of the quark determinant
Authors: Cè Marco , Giusti Leonardo , Schaefer Stefan
Published: March 2018

We discuss the recently proposed multiboson domain-decomposed factorization of the gauge-field dependence of the fermion determinant in lattice QCD. In particular, we focus on the case of a lattice divided in an arbitrary number of thick time slices. As a consequence, multiple space-time regions can be updated independently. This allows to address the exponential degradation of the signal-to-noise ration of correlation functions with multilevel Monte Carlo sampling. We show numerical evidence of the effectiveness of a two-level integration for pseudoscalar propagators with momentum and for vector propagators, in a two active regions setup. These results are relevant to lattice computation of the hadronic contributions to the anomalous magnetic moment of the muon and to heavy meson decay form factors.
Worldlines and worldsheets for non-abelian lattice field theories: Abelian color fluxes and Abelian color cycles
Authors: Gattringer Christof , Göschl Daniel , Marchis Carlotta
Published: March 2018

We discuss recent developments for exact reformulations of lattice field theories in terms of worldlines and worldsheets. In particular we focus on a strategy which is applicable also to non-abelian theories: traces and matrix/vector products are written as explicit sums over color indices and a dual variable is introduced for each individual term. These dual variables correspond to fluxes in both, space-time and color for matter fields (Abelian color fluxes), or to fluxes in color space around space-time plaquettes for gauge fields (Abelian color cycles). Subsequently all original degrees of freedom, i.e., matter fields and gauge links, can be integrated out. Integrating over complex phases of matter fields gives rise to constraints that enforce conservation of matter flux on all sites. Integrating out phases of gauge fields enforces vanishing combined flux of matter-and gauge degrees of freedom. The constraints give rise to a system of worldlines and worldsheets. Integrating over the factors that are not phases (e.g., radial degrees of freedom or contributions from the Haar measure) generates additional weight factors that together with the constraints implement the full symmetry of the conventional formulation, now in the language of worldlines and worldsheets. We discuss the Abelian color flux and Abelian color cycle strategies for three examples: the SU(2) principal chiral model with chemical potential coupled to two of the Noether charges, SU(2) lattice gauge theory coupled to staggered fermions, as well as full lattice QCD with staggered fermions. For the principal chiral model we present some simulation results that illustrate properties of the worldline dynamics at finite chemical potentials.
Atiyah-Patodi-Singer index theorem for domain-wall fermion Dirac operator
Authors: Fukaya Hidenori , Onogi Tetsuya , Yamaguchi Satoshi
Published: March 2018

Recently, the Atiyah-Patodi-Singer(APS) index theorem attracts attention for understanding physics on the surface of materials in topological phases. Although it is widely applied to physics, the mathematical set-up in the original APS index theorem is too abstract and general (allowing non-trivial metric and so on) and also the connection between the APS boundary condition and the physical boundary condition on the surface of topological material is unclear. For this reason, in contrast to the Atiyah-Singer index theorem, derivation of the APS index theorem in physics language is still missing. In this talk, we attempt to reformulate the APS index in a "physicist-friendly" way, similar to the Fujikawa method on closed manifolds, for our familiar domain-wall fermion Dirac operator in a flat Euclidean space. We find that the APS index is naturally embedded in the determinant of domain-wall fermions, representing the so-called anomaly descent equations.
Application of tensor network method to two dimensional lattice N = 1 Wess–Zumino model
Authors: Sakai Ryo , Kadoh Daisuke , Kuramashi Yoshinobu , Nakamura Yoshifumi , Takeda Shinji , Yoshimura Yusuke
Published: March 2018

We study a tensor network formulation of the two dimensional lattice N = 1 Wess–Zumino model with Wilson derivatives for both fermions and bosons. The tensor renormalization group allows us to compute the partition function without the sign problem, and basic ideas to obtain a tensor network for both fermion and scalar boson systems were already given in previous works. In addition to improving the methods, we have constructed a tensor network representation of the model including the Yukawatype interaction of Majorana fermions and real scalar bosons. We present some numerical results.
Duals of U(N) LGT with staggered fermions
Authors: Borisenko Oleg , Chelnokov Volodymyr , Voloshyn Sergey
Published: March 2018

Various approaches to construction of dual formulations of non-abelian lattice gauge theories are reviewed. In the case of U(N) LGT we use a theory of the Weingarten functions to construct a dual formulation. In particular, the dual representations are constructed 1) for pure gauge models in all dimensions, 2) in the strong coupling limit for the models with arbitrary number of flavours and 3) for two-dimensional U(N) QCD with staggered fermions. Applications related to the finite temperature/density QCD are discussed.
Explicit positive representation for complex weights on Rd
Authors: Ruba Błażej , Wyrzykowski Adam
Published: March 2018

It is an old idea to replace averages of observables with respect to a complex weight by expectation values with respect to a genuine probability measure on complexified space. This is precisely what one would like to get from complex Langevin simulations. Unfortunately, these fail in many cases of physical interest. We will describe method of deriving positive representations by matching of moments and show simple examples of successful constructions. It will be seen that the problem is greatly underdetermined.
High-order perturbative expansions in massless gauge theories with NSPT
Authors: Debbio Luigi Del , Renzo Francesco Di , Filaci Gianluca
Published: March 2018

We investigate the possibility of using numerical stochastic perturbation theory (NSPT) to probe high orders in the perturbative expansion of lattice gauge theories with massless Wilson fermions. Twisted boundary conditions are used to regularise the gauge zero-mode; the extension of these boundary conditions to include fermions in the fundamental representation requires to introduce a smell degree of freedom. Moreover, the mass of Wilson fermions is affected by an additive renormalisation: we study how to determine the mass counterterms consistently in finite volume. The knowledge of the critical masses will enable high-order perturbative computations in massless QCD, e.g. (as a first application) for the plaquette.
Influence of magnetic fields on the color screening masses
Authors: Bonati Claudio , D’Elia Massimo , Mesiti Michele , Negro Francesco , Rucci Andrea , Sanfilippo Francesco
Published: March 2018

We present some recent results obtained in the study of the color magnetic and electric screening masses in the QCD plasma. In particular, we discuss how the masses get modified by strong external fields which are expected to be created in physical situations such as heavy-ion collisions.
Lattice study of area law for double-winding Wilson loops
Authors: Shibata Akihiro , Kato Seikou , Kondo Kei-Ichi , Matsudo Ryutaro
Published: March 2018

We study the double-winding Wilson loops in the SU(N) Yang-Mills theory on the lattice. We discuss how the area law falloff of the double-winding Wilson loop average is modified by changing the enclosing contours C1 and C2 for various values of the number of color N. By using the strong coupling expansion, we evaluate the double-winding Wilson loop average in the lattice SU(N) Yang-Mills theory. Moreover, we compute the double-winding Wilson loop average by lattice Monte Carlo simulations for SU(2) and SU(3). We further discuss the results from the viewpoint of the Non-Abelian Stokes theorem in the higher representations.
On theD*sand charmonia leptonic decays
Authors: Bailas Gabriela , Blossier Benoît , Heitger Jochen , Morénas Vincent , Post Matthias
Published: March 2018

Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about theRDsratio, a test of lepton flavour universality equivalent toRD, already measured, but with thesquark as spectator, are awaited in coming years to constrain the corner of an extended Higgs sector with charged doublets. On another side, leptonic widths of pseudoscalar quarkonia are particularly interesting to test an extended Higgs sector with a light CP-odd Higgs boson singlet, through the study of its mixing with quarkonia states. Hadronic parameters entering those processes have to be determined from lattice QCD with enough confidence on the control of systematic errors. We report on the very first step of a long-term program tackled with Nf= 2 Wilson-Clover fermions to put relevant constraints on extensions of the Higgs sector: extraction of decay constants ofD*s,ƞc,ƞc(2S),J/ΨandΨ(2S) with lattice ensembles provided by the CLS effort, considering 2 lattice spacings and a large range of pion masses to estimate cut-off effects and extrapolate results to the chiral limit.
B → D*lv at non-zero recoil
Authors: Avilés-Casco Alejandro Vaquero , DeTar Carleton , Du Daping , El-Khadra Aida , Kronfeld Andreas , Laiho John , Van de Water Ruth S.
Published: March 2018

We present preliminary results from our analysis of the form factors for the B → D*lv decay at non-zero recoil. Our analysis includes 15 MILC asqtad ensembles with Nf = 2 + 1 flavors of sea quarks and lattice spacings ranging from a ≈ 0.15 fm down to 0.045 fm. The valence light quarks employ the asqtad action, whereas the heavy quarks are treated using the Fermilab action. We conclude with a discussion of future plans and phenomenological implications. When combined with experimental measurements of the decay rate, our calculation will enable a determination of the CKM matrix element |Vcb|.
B → πlv with Möbius Domain Wall Fermions
Authors: Colquhoun Brian , Hashimoto Shoji , Kaneko Takashi
Published: March 2018

We report on the status of our calculation of the exclusive semileptonic decay, B → πlv; a key process in the determination of the CKM matrix element |Vub|. The Möbius domain wall action is used for both light and heavy quarks on gauge ensembles that include the effects of 2 + 1 flavours of quarks in the sea at three values of the lattice spacing: a ≈ 0.08 fm, a ≈ 0.055 fm, and a ≈ 0.044 fm. Pion masses go down to 300 MeV while heavy quarks masses are as large as 2.44mc. We present preliminary results of form factors from this process, showing dependence on momentum transfer, lattice spacing, and the heavy quark mass.
Inclusive B decay calculations with analytic continuation
Authors: Hashimoto Shoji , Colquhoun Brian , Izubuchi Taku , Kaneko Takashi , Ohki Hiroshi
Published: March 2018

First-principle lattice calculation of inclusive B meson semileptonic decays is possible for a certain class of moments that is connected to the structure function at unphysical kinematics by analytic continuation. We present an exploratory lattice calculation and a comparison with the heavy quark expansion technique.
Bs → Kℓv form factors with 2+1 flavors
Authors: Liu Yuzhi , Bailey Jon A. , Bazavov A. , Bernard C. , Bouchard C. M. , DeTar C. , Du Daping , El-Khadra A. X. , Freeland E. D. , Gámiz E. , Gelzer Z. , Gottlieb Steven , Heller U. M. , Kronfeld A. S. , Laiho J. , Mackenzie P. B. , Meurice Y. , Neil E. T. , Simone J. N. , Sugar R. , Toussaint D. , Van de Water R. S. , Zhou Ran
Published: March 2018

Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors f0 and f+ for the semileptonic Bs → Kℓv decay. A total of six ensembles with lattice spacing from ≈ 0.12 to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass m’l is one-tenth the strange quark mass m’s. At the intermediate lattice spacing, the ratio m’l/m’s ranges from 0.05 to 0.2. The valence b quark is treated using the Sheikholeslami-Wohlert Wilson-clover action with the Fermilab interpretation. The other valence quarks use the asqtad action. When combined with (future) measurements from the LHCb and Belle II experiments, these calculations will provide an alternate determination of the CKM matrix element |Vub|.
Heavy Domain Wall Fermions: The RBC and UKQCD charm physics program
Authors: Boyle Peter A , Debbio Luigi Del , Jüttner Andreas , Khamseh Ava , Tsang Justus Tobias , Witzel Oliver
Published: March 2018

We review the domain wall charm physics program of the RBC and UKQCD collaborations based on simulations including ensembles with physical pion mass. We summarise our current set-up and present a status update on the decay constants fD, fDs, the charm quark mass, heavy-light and heavy-strange bag parameters and the ratio ξ
Weak hamiltonian Wilson Coefficients from Lattice QCD
Authors: Bruno Mattia
Published: March 2018

n this work we present a calculation of the Wilson Coefficients C1 and C2 of the Effective Weak Hamiltonian to all-orders in αs, using lattice simulations. Given the current availability of lattice spacings we restrict our calculation to unphysically light W bosons around 2 GeV and we study the systematic uncertainties of the two Wilson Coefficients.
Including electromagnetism in K → ππ decay calculations
Authors: Christ Norman , Feng Xu
Published: March 2018

Because of the small size of the ratio A2/A0 of the I = 2 to I = 0 K → ππ decay amplitudes (the ΔI = 1/2 rule) the effects of electromagnetism on A2 may be a factor of 20 larger than given by a naive O(±EM) estimate. Thus, if future calculations of A2 and epsilon’/epsilon are to achieve 10% accuracy, these effects need to be included. Here we present the first steps toward including electromagnetism in a calculation of the standard model K → ππ decay amplitudes using lattice QCD.
Tensor form factor for the D → π(K) transitions with Twisted Mass fermions.
Authors: Lubicz Vittorio , Riggio Lorenzo , Salerno Giorgio , Simula Silvano , Tarantino Cecilia
Published: March 2018

We present a preliminary lattice calculation of the D → π and D → K tensor form factors fT (q2) as a function of the squared 4-momentum transfer q2. ETMC recently computed the vector and scalar form factors f+(q2) and f0(q2) describing D → π(K)lv semileptonic decays analyzing the vector current and the scalar density. The study of the weak tensor current, which is directly related to the tensor form factor, completes the set of hadronic matrix element regulating the transition between these two pseudoscalar mesons within and beyond the Standard Model where a non-zero tensor coupling is possible. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 flavors of dynamical quarks. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV and with the valence heavy quark in the mass range from ≃ 0.7 mc to ≃ 1.2mc. The matrix element of the tensor current are determined for a plethora of kinematical conditions in which parent and child mesons are either moving or at rest. As for the vector and scalar form factors, Lorentz symmetry breaking due to hypercubic effects is clearly observed in the data. We will present preliminary results on the removal of such hypercubic lattice effects.
D → Klv semileptonic decay using lattice QCD with HISQ at physical pion masses
Authors: Chakraborty Bipasha , Davies Christine , Koponen Jonna , Lepage G Peter
Published: March 2018

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.
Improvement of heavy-heavy current for calculation of B̅ → D(*)lv̅ form factors using Oktay-Kronfeld heavy quarks
Authors: Bailey Jon A. , Jang Yong-Chull , Lee Weonjong , Leem Jaehoon
Published: March 2018

The CKM matrix element |Vcb| can be extracted by combining data from experiments with lattice QCD results for the semileptonic form factors for the B̅ → D(*)lv̅ decays. The Oktay-Kronfeld (OK) action was designed to reduce heavy-quark discretization errors to below 1%, or through O(λ3) in HQET power counting. Here we describe recent progress on bottom-to-charm currents improved to the same order in HQET as the OK action, and correct formerly reported results of our matching calculations, in which the operator basis was incomplete.
QCD in a moving frame: an exploratory study
Authors: Brida Mattia Dalla , Giusti Leonardo , Pepe Michele
Published: March 2018

The framework of shifted boundary conditions has proven to be a very powerful tool for the non-perturbative investigation of thermal quantum field theories. For instance, it has been successfully considered for the determination of the equation of state of SU(3) Yang-Mills theory with high accuracy. The set-up can be generalized to QCD and it is expected to lead to a similar breakthrough. We present first results for QCD with three flavours of non-perturbatively O(a)-improved Wilson fermions and shifted boundary conditions.
Towards leading isospin breaking effects in mesonic masses with O(a) improved Wilson fermions
Authors: Risch Andreas , Wittig Hartmut
Published: March 2018

We present an exploratory study of leading isospin breaking effects in mesonic masses using O(a) improved Wilson fermions. Isospin symmetry is explicitly broken by distinct masses and electric charges of the up and down quarks. In order to be able to make use of existing isosymmetric QCD gauge ensembles we apply reweighting techniques. The path integral describing QCD+QED is expanded perturbatively in powers of the light quark’ mass deviations and the electromagnetic coupling. We employ QEDL as a finite volume formulation of QED.
Conformal window in SU(2) with fundamental fermions
Authors: Leino Viljami , Rantaharju Jarno , Rantalaiho Teemu , Rummukainen Kari , Suorsa Joni , Tuominen Kimmo , Tähtinen Sara
Published: March 2018

We present the updated results of the infrared behavior of the SU(2) model with 6 and 8 fundamental representation fermions. We use the gradient flow method with the Schrödinger functional boundary conditions to measure the running of the coupling in these theories and find fixed points on both. We also measure the mass anomalous dimension from these configurations.
Multi-Grid Lanczos
Authors: Clark M. A. , Jung Chulwoo , Lehner Christoph
Published: March 2018

We present a Lanczos algorithm utilizing multiple grids that reduces the memory requirements both on disk and in working memory by one order of magnitude for RBC/UKQCD’s 48I and 64I ensembles at the physical pion mass. The precision of the resulting eigenvectors is on par with exact deflation.
Strategies in Development and Delivery of Nanotechnology Based Cosmetic Products
Authors: Ahmad Usama , Ahmad Zeeshan , Khan Ahmed , Akhtar Juber , Singh Satya , Ahmad Farhan
Published: March 2018

The science of formulation involving cosmetic ingredients has always been a challenge since the release of active components greatly depends upon the carrier system involved and the selectivity of skin barrier. The principle obstacle of the skin resides in the epidermis and it’s hard for many active components to cross it. The formulation related factors like size of particles, viscosity and lipophilicity of the components also play an important role in permeation of the dermal composition. Though widely used; conventional creams and gels still struggle in terms of success. This work focuses on nano based formulation strategies for successful delivery of cosmetic agents. Novel strategies like nanoemulsion, nanogels, liposomes, aquasomes, niosomes, dendrimers and fullerenes have paved way for successful delivery of dermal formulations to desire depths in the skin.
Good Agreement Between Transabdominal and Endoscopic Ultrasound of the Pancreas in Chronic Pancreatitis
Authors: Engjom Trond , Pham Khahn Do-Chong , Erchinger Friedemann , Haldorsen Ingfrid Salvesen , Gilja Odd Helge , Dimcevski Georg , Havre Roald Flesland
Published: March 2018

Purpose We aimed to evaluate the agreement of single criteria and dedicated scores from transabdominal ultrasound of the pancreas (US) compared to standards by endoscopic ultrasound (EUS) and computed tomography (CT).

Materials and Methods In this observational cohort study performed in a tertiary care center, US and EUS were performed in 110 patients referred for suspected CP. Based on the Mayo score, 52 patients were diagnosed with CP. The sonographic findings obtained by both methods were registered. The number of criteria was counted and scored according to the Rosemont score.

Results Agreement between the number of detected US and EUS criteria was substantial (ICC = 0.74 [0.61–0.83]. Adding Rosemont weighting improved the agreement (ICC = 0.88 [0.81–0.92]). Regarding individual criteria, the agreement was substantial for the detection of calcifications (κ = 0.86) and moderate for cysts and irregular or dilated pancreatic duct (κ = 0.42–0.58). Agreement for the other criteria was poorer (κ≤ 0.40). The diagnostic performance indices [95 % CI] of US for diagnosing CP (using Mayo score as reference standard) were for the unweighted score: Sensitivity: 0.65 [0.51–0.78], specificity: 0.97 [0.87–1.00]; and for Rosemont score: Sensitivity: 0.75 [0.61–0.86], specificity: 0.95 [0.83–0.99].

Conclusion The agreement between US and EUS for the unweighted and weighted scores was substantial. For the features calcifications, cysts and main pancreatic duct (MPD) changes, agreement was moderate to substantial. For the other detected US criteria, the agreement with EUS was too poor to be clinically relevant.
Selection of Candidates for Lung Transplantation and Controversial Issues
Authors: Merlo Christian , Orens Jonathan
Published: March 2018

Lung transplantation is a widely accepted treatment to manage the advanced stages of many lung diseases that have failed to respond to all other therapeutic interventions. There have been ever-expanding indications for lung transplantation as a treatment for lung disease. The International Society for Heart and Lung Transplantation (ISHLT) updated guidelines for candidate selection in 2014. This document was published to serve as a guide in selecting appropriate candidates for lung transplantation. Ideal candidates for lung transplantation are those with near-end stage disease, limited life expectancy due to their lung disease, and who experience significant loss in quality of life. At the same time, candidates should be free of significant comorbidities that might negatively impact successful transplantation. Despite well thought out published guidelines for candidate selection, many controversial issues surrounding selection of lung transplant candidates remain. This review will focus on some of the more common controversial issues and explain how most centers approach these issues when choosing candidates for lung transplantation.
Donation after Brain Death versus Donation after Circulatory Death: Lung Donor Management Issues
Authors: Levvey Bronwyn , Levin Kovi , Paraskeva Miranda , Westall Glen , Snell Gregory
Published: March 2018

Lung transplantation (LTx) has traditionally been limited by a lack of suitable donor lungs. With the recognition that lungs are more robust than initially thought, the size of the donor pool of available lungs has increased dramatically in the past decade. Donation after brain death (DBD) and donation after circulatory death (DCD) lungs, both ideal and extended are now routinely utilized. DBD lungs can be damaged. There are important differences in the public's understanding, legal and consent processes, intensive care unit strategies, lung pathophysiology, logistics, and potential-to-actual donor conversion rates between DBD and DCD. Notwithstanding, the short- and long-term outcomes of LTx from any of these DBD versus DCD donor scenarios are now similar, robust, and continue to improve. Large audits suggest there remains a large untapped pool of DCD (but not DBD) lungs that may yet further dramatically increase lung transplant numbers. Donor scoring systems that might predict the donor conversion rates and lung quality, the role of ex vivo lung perfusion as an assessment and lung resuscitation tool, as well as the potential of donor lung quality biomarkers all have immense promise for the clinical field.
The Human Respiratory Microbiome: Implications and Impact
Authors: Mitchell Alicia , Glanville Allan
Published: March 2018

Once considered a sterile site below the larynx, the tracheobronchial tree and parenchyma of the lungs are now known to harbor a rich diversity of microbial species including bacteria, viruses, fungi, and archaea. Many of these organisms, particularly the viruses which comprise the human respiratory virome, have not been identified, so their true role is unknown. It seems logical to conclude that a “healthy” respiratory microbiome exists which may be modified in disease states and perhaps by therapies such as antibiotics, antifungals, and antiviral treatments. It is likely that there is a critical relationship or equilibrium between components of the microbiome until such time as perturbations occur which lead to a state of dysbiosis or an “unhealthy” microbiome. The act of lung transplantation provides an extreme change to an individual's respiratory microbiome as, in effect, the donor respiratory microbiome is transplanted into the recipient. The mandatory ex-vivo period of the donor lungs appears to be associated with blooms of resident viral species in particular. Subsequently, allograft injury, rejection, and immune suppressive therapy all combine to create periods of dysbiosis which when combined with transient infections such as community acquired respiratory viruses may facilitate the development of chronic allograft dysfunction in predisposed individuals. As our understanding of the respiratory microbiome is rapidly expanding, based on the use of new-generation sequencing tools in particular, it is to be hoped that insights gained into the subtle relationship between the microbiome and the lung allograft will facilitate improved outcomes by directing novel therapeutic endeavors.
How Should Lungs Be Allocated for Transplant?
Authors: Egan Thomas
Published: March 2018

As lung transplantation became established therapy for end-stage lung disease, there were not nearly enough suitable lungs from brain-dead organ donors to meet the need, leading to a focus on how lungs are allocated for transplant. Originally lungs were allocated by the United Network for Organ Sharing (UNOS) like hearts—by waiting time, first to listed recipients in the organ procurement organization of the donor, then to potential recipients in concentric 500 nautical mile circles. This resulted in long waiting times and increasing waitlist deaths. In 1999, the Health Resources and Services Administration published a Final Rule, requesting UNOS to review organ allocation algorithms to ensure that they complied with the desire to allocate organs based on urgency, avoiding futile transplants, and minimizing the role of waiting time in organ allocation. This led to development of the lung allocation score (LAS), which allocates lungs based on urgency and transplant benefit, introduced in 2005. The U.S. LAS system was adopted by Eurotransplant to allocate unused lungs between donor countries, and by both Germany and the Netherlands for lung allocation in their countries. This article will review the history of lung allocation, discuss the impact of LAS and its shortcomings, suggest recommendations to increase the number of lungs for transplant, and improve allocation of donated lungs. Ultimately, the goal of organ transplant research is to have so many organs to transplant that allocation systems are unnecessary.
Liberal versus Indicated Maternal Oxygen Supplementation in Labor: A Before-and-After Trial
Authors: Blackwell Sean , Alrais Mesk , Amro Farah , Wiley Rachel , Heale Patricia , Hutchinson Maria , Sibai Baha , Ankumah Nana-Ama
Published: March 2018

Background Although supplemental oxygen (SO2) is routinely administered to laboring gravidas, benefits and harms are not well studied.

Objective This article compares strategies of liberal versus indicated SO2 therapy during labor on cesarean delivery (CD) rate and neonatal outcomes.

Study Design A controlled, before-and-after trial of laboring women with term, singleton pregnancies. During an initial 8-week period, maternal SO2 was administered at the discretion of the provider followed by an 8-week period where SO2 was to be given only for protocol indications.

Results Our study included 844 women. There was no difference in number of women receiving SO2 (53% liberal vs. 50% indicated; p = 0.33). For those receiving SO2, there was no difference in SO2 duration (median, 89 minutes [interquartile range, 42–172] vs. 87 minutes [36–152]; p = 0.42). There were no differences in overall CD rate (20% vs. 17%; p = 0.70), CD for nonreassuring fetal status, or use of intrauterine resuscitative measures. There were more 5-minute APGAR < 7 in the indicated group, but no difference in umbilical artery pH < 7.1 or neonatal intensive care unit (NICU) admission.

Conclusion Approximately half of women receive SO2 intrapartum regardless of a strategy of liberal or indicated oxygen use. There were no clinically significant differences in outcomes between strategies.
A Neurenteric Cyst Presenting as a Brainstem Tumor: Imaging and Clinical Findings
Authors: Subramanian Subramanian , Greene Stephanie , Rajan Deepa , Kofler Julia , Zuccoli Giulio , Ly Juan
Published: March 2018

An 11-year-old girl presented with vomiting, nystagmus, and ataxia. MRI showed a partially enhancing medulla oblongata lesion and an adjacent nonenhancing cystic exophytic lesion. An exophytic brainstem tumor was suspected. Histologically, the lesion was identified as a neurenteric cyst (NC). On retrospective review, the NC was connected to the brainstem by a subtle sinus tract. This led to brainstem inflammation which reversed once the cyst was resected. We describe an unreported case of a patient with a NC at the craniocervical junction connected to the brainstem through a sinus tract and discuss the possible embryological abnormality and imaging features.
A Riccati solution for the ideal MHD plasma response with applications to real-time stability control
Authors: Glasser Alexander S. , Kolemen Egemen , Glasser A. H.
Published: March 2018

Active feedback control of ideal MHD stability in a tokamak requires rapid plasma stability analysis. Toward this end, we reformulate the δW stability method with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the generic tokamak ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD matrix Riccati differential equation. Since Riccati equations are prevalent in the control theory literature, such a shift in perspective brings to bear a range of numerical methods that are well-suited to the robust, fast solution of control problems. We discuss the usefulness of Riccati techniques in solving the stiff ordinary differential equations often encountered in ideal MHD stability analyses—for example, in tokamak edge and stellarator physics. We demonstrate the applicability of such methods to an existing 2D ideal MHD stability code—DCON [A. H. Glasser, Phys. Plasmas 23, 072505 (2016)]—enabling its parallel operation in near real-time, with wall-clock time ≪1s. Such speed may help enable active feedback ideal MHD stability control, especially in tokamak plasmas whose ideal MHD equilibria evolve with inductive timescale τ≳ 1s—as in ITER.
Contributed Review: Camera-limits for wide-field magnetic resonance imaging with a nitrogen-vacancy spin sensor
Authors: Wojciechowski Adam M. , Karadas Mürsel , Huck Alexander , Osterkamp Christian , Jankuhn Steffen , Meijer Jan , Jelezko Fedor , Andersen Ulrik L.
Published: March 2018

Sensitive, real-time optical magnetometry with nitrogen-vacancy centers in diamond relies on accurate imaging of small (≪10−2), fractional fluorescence changes across the diamond sample. We discuss the limitations on magnetic field sensitivity resulting from the limited number of photoelectrons that a camera can record in a given time. Several types of camera sensors are analyzed, and the smallest measurable magnetic field change is estimated for each type. We show that most common sensors are of a limited use in such applications, while certain highly specific cameras allow achieving nanotesla-level sensitivity in 1 s of a combined exposure. Finally, we demonstrate the results obtained with a lock-in camera that paves the way for real-time, wide-field magnetometry at the nanotesla level and with a micrometer resolution.
Non-monotonic behavior of electron temperature in argon inductively coupled plasma and its analysis via novel electron mean energy equation
Authors: Zhao Shu-Xia
Published: March 2018

In this work, the behavior of electron temperature against the power in argon inductively coupled plasma is investigated by a fluid model. The model properly reproduces the non-monotonic variation of temperature with power observed in experiments. By means of a novel electron mean energy equation proposed for the first time in this article, this electron temperature behavior is interpreted. In the overall considered power range, the skin effect of radio frequency electric field results in localized deposited power density, responsible for an increase of electron temperature with power by means of one parameter defined as power density divided by electron density. At low powers, the rate fraction of multistep and Penning ionizations of metastables that consume electron energy two times significantly increases with power, which dominates over the skin effect and consequently leads to the decrease of temperature with power. In the middle power regime, a transition region of temperature is given by the competition between the ionizing effect of metastables and the skin effect of electric field. The power location where the temperature alters its trend moves to the low power end as increasing the pressure due to the lack of metastables. The non-monotonic curve of temperature is asymmetric at the short chamber due to the weak role of skin effect in increasing the temperature and tends symmetric when axially prolonging the chamber. Still, the validity of the fluid model in this prediction is estimated and the role of neutral gas heating is guessed. This finding is helpful for people understanding the different trends of temperature with power in the literature.
Electronic excitation induced defect dynamics in HfO2 based MOS devices investigated by in-situ electrical measurements
Authors: Manikanthababu N. , Vajandar S. , Arun N. , Pathak A. P. , Asokan K. , Osipowicz T. , Basu T. , Nageswara Rao S. V. S.
Published: March 2018

In-situ I-V and C-V characterization studies were carried out to determine the device quality of atomic layer deposited HfO2 (2.7 nm)/SiO2 (0.6 nm)/Si-based metal oxide semiconductor devices during 120 MeV Ag ion irradiation. The influence of various tunneling mechanisms has been investigated by analyzing the I-V characteristics as a function of ion fluence. The nature of the defects created is tentatively identified by the determination of the significant tunneling processes. While the ion induced annealing of defects is observed at lower fluences, ion induced intermixing and radiation damage is found to be significant at higher fluences. The C-V characteristics also reveal significant changes at the interface and oxide trap densities: an increase in the oxide layer thickness occurs through the formation of an HfSiO interlayer. The interlayer is due to the swift heavy ion induced intermixing, which has been confirmed by X-TEM and X-ray photoelectron spectroscopy measurements.
Estimating the cost of high temperature liquid metal based concentrated solar power
Authors: Wilk Gregory , DeAngelis Alfred , Henry Asegun
Published: March 2018

The current levelized cost of electricity from concentrated solar power is too high to directly compete with natural gas under current carbon emissions policies. An approximate 50% cost reduction is needed relative to current power tower technology based on molten nitrate salts, and one pathway to a major cost reduction is to operate the system at higher temperatures, enabling a more efficient heat engine. Here, we consider a future system that can operate at gas turbine inlet temperatures of ∼1300–1500 °C by using liquid metals as heat transfer and storage fluids with a ceramic based piping infrastructure. In general, ceramics are more expensive than the current stainless steels, but they are less expensive than the nickel alloys that are proposed to be used in higher temperature chloride molten salt plants. Considering various tradeoffs, it was not clear a priori whether or not the potential gains in heat engine efficiency would be negated by increased material costs or how much net reduction in levelized cost might be possible. This study answers this question by first detailing a base case molten nitrate salt power tower plant with published cost data. Then, a future liquid metal version of a power tower is modeled using similar specifications as the liquid salt plant to determine if there are any obvious costs that might negate the efficiency gains associated with operating well above 1000 °C. The results of the analysis showed that although the receiver and several other sub-systems become more expensive, there is a net cost reduction in the range of 20%–30%, depending upon the heat engine efficiency.
Thermodynamically stable diatomic dications: The cases of SrO2+ and SrH2+
Authors: Gonçalves dos Santos Levi , Franzreb Klaus , Ornellas Fernando R.
Published: March 2018

A high level theoretical investigation of the low-lying electronic states of the diatomic dications SrO2+ and SrH2+ is presented for the first time along with experimental results of their mass spectra where they were detected. A global and reliable picture of the potential energy curves of the electronic states and the associated spectroscopic parameters provide quantitative results attesting to the thermodynamic stability of both species. Inclusion of spin-orbit interactions does not significantly change the energetic characterization. For SrO2+, the ground (X 3Σ−) and first excited (A 3Π, Te = 3971 cm−1) states are bound (De) by 15.94 kcal mol−1 and 4.71 kcal mol−1, respectively. Transition probabilities (Av′v″) have been evaluated and radiative lifetimes estimated for the vibrational states of A 3Π (v′), and transition probabilities are expected to be diagonally dominant and fall in the far-IR region of the spectrum. For the singlet states a 1Δ, b 1Π, c 1Σ+, and d 1Σ+, transition probabilities have also been calculated for all symmetry allowed transitions and the radiative lifetimes evaluated for selected vibrational states of the upper levels. The transitions associated with the band systems d 1Σ+–b 1Π and d 1Σ+–c 1Σ+, although falling in the yellow region of the spectrum, with overlapping bands, are expected to show quite distinct intensities since the transition moment associated with d 1Σ+–c 1Σ+ is much larger. For singlet transitions, the prediction of relative intensities using the Franck-Condon approximation fails in most of the cases. For SrH2+, only the ground state is bound (De = 6.54 kcal mol−1); with an equilibrium distance of 5.117 a0, the associated spectroscopic parameters (ωe, ωexe, Be) turned out to be (518.9, 32.77, 2.3227) in cm−1. For both species, dipole moment functions illustrate the variation of the molecular polarity with the internuclear distance.
Field-induced phase transitions and enhanced double negative electrocaloric effects in (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric single crystal
Authors: Zhuo Fangping , Li Qiang , Qiao Huimin , Yan Qingfeng , Zhang Yiling , Xi Xiaoqing , Chu Xiangcheng , Long Xifa , Cao Wenwu
Published: March 2018

Field-induced phase transitions and electrocaloric effect have been studied in (Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectric single crystal. Temperature dependent dielectric, Raman spectra, as well as in situ domain evolution demonstrated that the order of phase transitions during heating is in the sequence of orthorhombic antiferroelectric → tetragonal antiferroelectric → cubic paraelectric. Enhanced negative electrocaloric effect value of −3.6 °C and electrocaloric strength of 0.3 K mm/kV at 125 °C have been achieved. Double negative effects (−0.7 °C at 45 °C and −3.6 °C at 125 °C) and a relatively large positive effect (1 °C) near Curie temperature (190 °C) have been found in the PLZST single crystal. Moreover, microscopic dipoles and a phenomenological Landau-type model were employed to understand these unusual electrocaloric effects. Enhanced negative effect and the coexistence of both negative and positive effects in one material are promising for us to develop practical solid-state cooling devices with high efficiency.