bluuebunny/crossref_metadata_2025 huggingface dataset:
Derating of distribution transformers under non‐linear loads using a combined analytical‐finite elements approach
Authors: Ghazizadeh Milad , Faiz Jawad , Oraee Hashem
Published: May 2016

Supplying non‐linear loads causes increased losses in transformers which eventually leads to their reduced life spans. Therefore, transformers are derated in order to protect them against premature loss of life. To do this, load losses including ohmic loss and winding eddy current (WEC) loss need to be estimated. This study suggests an improved analytical approach using finite element method (FEM) which includes all material characteristics and geometrical structures in order to calculate WEC loss under non‐sinusoidal load current in each winding individually. By adopting this procedure, harmonic loss factor as a dominant parameter in transformers derating is estimated. By emphasising the region in which the maximum WEC loss occurs, an additional factor (FMECL) based on the physical phenomena involved is introduced using FEM. On the basis of the aforementioned concepts, a new relationship is presented for transformer derating. Ultimately, the suggested method and the IEEE standard are applied to derate a distribution transformer and the results are discussed. In addition, the proposed method is validated using a thermal model and its advantages over the IEEE derating method is presented.
Inhibitors in Severe Hemophilia A: 25-Year Experience in Slovakia
Authors: Batorova Angelika , Jankovicova Denisa , Morongova Anna , Bubanska Eva , Prigancova Tatiana , Horakova Julia , Machyniakova Marianna , Cervenka Jan , Chandoga Jan , Böhmer Daniel , Mistrik Martin
Published: May 2016

We present 25-year experience with inhibitors in previously untreated patients (PUPs) with severe hemophilia A in Slovakia, where safe factor VIII (FVIII) concentrates have been used since 1990. A prospective study focused on inhibitor incidence in PUPs was established in 1997. Out of a total 61 PUPs born between January 1997 and October 2015, 59 were eligible for evaluation; 50 and 9 were treated with > 20 exposure days (ED) of plasma-derived FVIII (pdFVIII) and recombinant FVIII (rFVIII) products, respectively. In the entire group 13/59 (22%) PUPs developed inhibitors; i.e. 7/50 (14%) and 6/9 (67%) treated with pdFVIII and rFVIII, respectively. Univariate analysis of inhibitor risk factors in patient groups with and without inhibitors showed the rFVIII and serious/recurrent infections within the first 50 EDs to be associated with inhibitor development (OR of 12.3 [95% CI 2.48–60.83; p = 0.002] and 5.0; [95% CI 1.16–21.9; p = 0.03), respectively]). Also, in multivariate Cox regression analysis, peak treatment ≥ 5 EDs reached statistical significance. The hazard ratio (HR) was 7.15 (95% CI 1.65–31.36) p = 0.0086 for rFVIII and 4.38 (95% CI 1.02–18.67) p = 0.046 for intensive treatment. Between 1993 and 2015, 21 immune tolerance inductions (ITIs) in 19 inhibitor patients were performed in the two largest hemophilia centers in Slovakia. In all but one ITI courses pdFVIII containing von Willebrand factor (FVIII/VWF) was used with preferred use of high-dose ITI (HD ITI) in high responders (HRs). Complete or partial success was achieved in 17/19 (89.5%) patients. Evaluating only the patients who already completed ITI, the success rate was even higher (15/16; 94%), including 7/7 low responders and 8/9 HR. Conclusion: Our national prospective study comprising entire group of PUPs with severe hemophilia A showed higher incidence of inhibitors in patients treated with rFVIII and those with intensive therapy within first 50 EDs. However, our experience is limited to small numbers of patients; thus, our results must be interpreted cautiously. High success rate of the ITI in our inhibitor patients has been achieved with FVIII/VWF concentrates and preferred use of HD ITI in HR patients.
Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses
Authors: Kar S. , Ahmed H. , Nersisyan G. , Brauckmann S. , Hanton F. , Giesecke A. L. , Naughton K. , Willi O. , Lewis C. L. S. , Borghesi M.
Published: May 2016

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.
Numerical study of two-dimensional flow around two side-by-side circular cylinders at low Reynolds numbers
Authors: Singha Sintu , Nagarajan Kaushik Kumar , Sinhamahapatra K. P.
Published: May 2016

Incompressible flows at low Reynolds numbers over two identical side-by-side circular cylinders have been investigated numerically using unstructured finite volume method. The gap between the cylinders (g) and Reynolds number (Re) considered in the study lies respectively in the range of 0.2 ≤ g/D ≤ 4.0 (D being the diameter of the cylinder) and 20 ≤ Re ≤ 160. Low Reynolds number steady flows are given considerable importance. Two types of wakes are observed in the steady flow regime; the first type is characterized by attached vortices as in the case of an isolated cylinder and the other type is identified by detached standing vortices in the downstream. Reynolds number at which flow turns unsteady is quantified for each gap width. Five different types of wake patterns are observed in the unsteady flow regime: single bluff body wake, deflected wake, flip-flopping wake, in-phase synchronized, and anti-phase synchronized wakes. Present simulations of the evolution of single bluff-body wake demonstrate presence of vortices in the gap side too. The very long time simulations show that below a limiting Re depending on the gap, there is a transition of fully developed initial anti-phase flow to the in-phase flow at a later time. The limiting Reynolds number for this phase bifurcation phenomenon is evaluated in the (Re, g/D) space. A properly calibrated reduced order model based stability analysis is carried out to investigate the phase transition.
Dynamics of intrinsic axial flows in unsheared, uniform magnetic fields
Authors: Li J. C. , Diamond P. H. , Xu X. Q. , Tynan G. R.
Published: May 2016

A simple model for the generation and amplification of intrinsic axial flow in a linear device, controlled shear decorrelation experiment, is proposed. This model proposes and builds upon a novel dynamical symmetry breaking mechanism, using a simple theory of drift wave turbulence in the presence of axial flow shear. This mechanism does not require complex magnetic field structure, such as shear, and thus is also applicable to intrinsic rotation generation in tokamaks at weak or zero magnetic shear, as well as to linear devices. This mechanism is essentially the self-amplification of the mean axial flow profile, i.e., a modulational instability. Hence, the flow development is a form of negative viscosity phenomenon. Unlike conventional mechanisms where the residual stress produces an intrinsic torque, in this dynamical symmetry breaking scheme, the residual stress induces a negative increment to the ambient turbulent viscosity. The axial flow shear is then amplified by this negative viscosity increment. The resulting mean axial flow profile is calculated and discussed by analogy with the problem of turbulent pipe flow. For tokamaks, the negative viscosity is not needed to generate intrinsic rotation. However, toroidal rotation profile gradient is enhanced by the negative increment in turbulent viscosity.
Design and numerical simulation of a high power capacity relativistic backward wave oscillator with an electron collection cavity
Authors: Li Xiaoze , Ye Hu , Zhang Yuchuan , Song Wei , Su Jiancang , Zhang Ligang , Tan Weibing , Hu Xianggang , Zhu Xiaoxin , Shen Zhiyuan , Zhang Min
Published: May 2016

A high power capacity relativistic backward wave oscillator with an electron collection cavity (ECC) placed at the downstream of the slow wave structure (SWS) is presented. The breakdown threshold is increased, and the density of seed electron is suppressed by preventing the secondary electron, plasma, and powder generated from the bombardment of spent electron beam on the surface of the collector drifting to the extractor and beam-wave interaction region. The maximum longitudinal electric field in the device is reduced through extension of the span between electron beam and slow wave structure and weakening the Cerenkov radiation. The conversion efficiency reaches up to 52% owing to enhanced transit time radiation taking place at the entrance of the ECC. The maximum longitudinal electric field is 1.1 MV/cm on the surface of SWSs when the output power is 7.3 GW and the power capacity improves significantly.
Measurement of electron density using reactance cutoff probe
Authors: You K. H. , You S. J. , Kim D. W. , Na B. K. , Seo B. H. , Kim J. H. , Seong D. J. , Chang H. Y.
Published: May 2016

This paper proposes a new measurement method of electron density using the reactance spectrum of the plasma in the cutoff probe system instead of the transmission spectrum. The highly accurate reactance spectrum of the plasma-cutoff probe system, as expected from previous circuit simulations [Kim et al., Appl. Phys. Lett. 99, 131502 (2011)], was measured using the full two-port error correction and automatic port extension methods of the network analyzer. The electron density can be obtained from the analysis of the measured reactance spectrum, based on circuit modeling. According to the circuit simulation results, the reactance cutoff probe can measure the electron density more precisely than the previous cutoff probe at low densities or at higher pressure. The obtained results for the electron density are presented and discussed for a wide range of experimental conditions, and this method is compared with previous methods (a cutoff probe using the transmission spectrum and a single Langmuir probe).
Dynamic polarizability and electric multipolar transitions in two electron atoms under exponential cosine screened coulomb potential
Authors: Chaudhuri Supriya K. , Modesto-Costa Lucas , Mukherjee Prasanta K.
Published: May 2016

Detailed investigations on the frequency dependent polarizabilities, transition energies, oscillator strengths, and transition probabilities of two electron systems He, Be2+, C4+, and O6+ under electric dipolar (E1) and quadrupolar (E2) excitations have been performed using exponential cosine screened coulomb potential with a view to understand the structural behaviour of such systems due to external confinement produced by plasma environment. Time dependent coupled Hartree–Fock theory within a variational framework has been adopted for studying the first three low lying excited states 1s2:1Se→1snp:1Po (n = 2, 3, 4) and 1snd:1De (n = 3, 4, 5) under such excitations. Quantitatively, the effect of confinement produced by the external plasma has been taken care of by considering the change in atomic potential through plasma screening, directly related to the coupling strength of the plasma with the atomic charge cloud. With increased plasma screening, a gradual destabilisation of the energy levels with subsequent reduction of the ionization potential and number of excited states has been observed. Behavioral pattern of the frequency dependent polarizabilities, excitation energies, oscillator strengths, and transition probabilities under systematic increase of the screening has been investigated. Results have been compared thoroughly with those available for free systems and under confinement by exponential cosine screened and screened Coulomb potential.
Electron heating mode transition induced by mixing radio frequency and ultrahigh frequency dual frequency powers in capacitive discharges
Authors: Sahu B. B. , Han Jeon G.
Published: May 2016

Electron heating mode transitions induced by mixing the low- and high-frequency power in dual-frequency nitrogen discharges at 400 mTorr pressure are presented. As the low-frequency (13.56 MHz) power decreases and high-frequency (320 MHz) power increases for the fixed power of 200 W, there is a transition of electron energy distribution function (EEDF) from Druyvesteyn to bi-Maxwellian type characterized by a distinguished warm electron population. It is shown that this EEDF evolution is attributed to the transition from collisional to collisionless stochastic heating of the low-energy electrons.
Study of electric and magnetic field fluctuations from lower hybrid drift instability waves in the terrestrial magnetotail with the fully kinetic, semi-implicit, adaptive multi level multi domain method
Authors: Innocenti M. E. , Norgren C. , Newman D. , Goldman M. , Markidis S. , Lapenta G.
Published: May 2016

The newly developed fully kinetic, semi-implicit, adaptive multi-level multi-domain (MLMD) method is used to simulate, at realistic mass ratio, the development of the lower hybrid drift instability (LHDI) in the terrestrial magnetotail over a large wavenumber range and at a low computational cost. The power spectra of the perpendicular electric field and of the fluctuations of the parallel magnetic field are studied at wavenumbers and times that allow to appreciate the onset of the electrostatic and electromagnetic LHDI branches and of the kink instability. The coupling between electric and magnetic field fluctuations observed by Norgren et al. [“Lower hybrid drift waves: Space observations,” Phys. Rev. Lett. 109, 055001 (2012)] for high wavenumber LHDI waves in the terrestrial magnetotail is verified. In the MLMD simulations presented, a domain (“coarse grid”) is simulated with low resolution. A small fraction of the entire domain is then simulated with higher resolution also (“refined grid”) to capture smaller scale, higher frequency processes. Initially, the MLMD method is validated for LHDI simulations. MLMD simulations with different levels of grid refinement are validated against the standard semi-implicit particle in cell simulations of domains corresponding to both the coarse and the refined grid. Precious information regarding the applicability of the MLMD method to turbulence simulations is derived. The power spectra of MLMD simulations done with different levels of refinements are then compared. They consistently show a break in the magnetic field spectra at k⊥di∼30, with di the ion skin depth and k⊥ the perpendicular wavenumber. The break is observed at early simulated times, Ωcit<6, with Ωci the ion cyclotron frequency. It is due to the initial decoupling of electric and magnetic field fluctuations at intermediate and low wavenumbers, before the development of the electromagnetic LHDI branch. Evidence of coupling between electric and magnetic field fluctuations in the wavenumber range where the fast and slow LHDI branches develop is then provided for a cluster magnetotail crossing.
Evaluating gyro-viscosity in the Kelvin-Helmholtz instability by kinetic simulations
Authors: Umeda Takayuki , Yamauchi Natsuki , Wada Yasutaka , Ueno Satoshi
Published: May 2016

In the present paper, the finite-Larmor-radius (gyro-viscous) term [K. V. Roberts and J. B. Taylor, Phys. Rev. Lett. 8, 197–198 (1962)] is evaluated by using a full kinetic Vlasov simulation result of the Kelvin-Helmholtz instability (KHI). The velocity field and the pressure tensor are calculated from the high-resolution data of the velocity distribution functions obtained by the Vlasov simulation, which are used to approximate the Finite-Larmor-Radius (FLR) term according to Roberts and Taylor [Phys. Rev. Lett. 8, 197–198 (1962)]. The direct comparison between the pressure tensor and the FLR term shows an agreement. It is also shown that the anisotropic pressure gradient enhanced the linear growth of the KHI when the inner product between the vorticity of the primary velocity shear layer and the magnetic field is negative, which is consistent with the previous FLR-magnetohydrodynamic simulation result. This result suggests that it is not sufficient for reproducing the kinetic simulation result by fluid simulations to include the FLR term (or the pressure tensor) only in the equation of motion for fluid.
Comparison of the secondary electrons produced by proton and electron beams in water
Authors: Kia Mohammad Reza , Noshad Houshyar
Published: May 2016

The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.
A scheme for reducing deceleration-phase Rayleigh–Taylor growth in inertial confinement fusion implosions
Authors: Wang L. F. , Ye W. H. , Wu J. F. , Liu Jie , Zhang W. Y. , He X. T.
Published: May 2016

It is demonstrated that the growth of acceleration-phase instabilities in inertial confinement fusion implosions can be controlled, especially in the high-foot implosions [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility. However, the excessive growth of the deceleration-phase instabilities can still destroy the hot spot ignition. A scheme is proposed to retard the deceleration-phase Rayleigh–Taylor instability growth by shock collision near the waist of the inner shell surface. Two-dimensional radiation hydrodynamic simulations confirm the improved deceleration-phase hot spot stability properties without sacrificing the fuel compression.
The Kelvin-Helmholtz instability of boundary-layer plasmas in the kinetic regime
Authors: Steinbusch Benedikt , Gibbon Paul , Sydora Richard D.
Published: May 2016

The dynamics of the Kelvin-Helmholtz instability are investigated in the kinetic, high-frequency regime with a novel, two-dimensional, mesh-free tree code. In contrast to earlier studies which focused on specially prepared equilibrium configurations in order to compare with fluid theory, a more naturally occurring plasma-vacuum boundary layer is considered here with relevance to both space plasma and linear plasma devices. Quantitative comparisons of the linear phase are made between the fluid and kinetic models. After establishing the validity of this technique via comparison to linear theory and conventional particle-in-cell simulation for classical benchmark problems, a quantitative analysis of the more complex magnetized plasma-vacuum layer is presented and discussed. It is found that in this scenario, the finite Larmor orbits of the ions result in significant departures from the effective shear velocity and width underlying the instability growth, leading to generally slower development and stronger nonlinear coupling between fast growing short-wavelength modes and longer wavelengths.
Ion-acoustic envelope modes in a degenerate relativistic electron-ion plasma
Authors: McKerr M. , Haas F. , Kourakis I.
Published: May 2016

A self-consistent relativistic two-fluid model is proposed for one-dimensional electron-ion plasma dynamics. A multiple scales perturbation technique is employed, leading to an evolution equation for the wave envelope, in the form of a nonlinear Schrödinger type equation (NLSE). The inclusion of relativistic effects is shown to introduce density-dependent factors, not present in the non-relativistic case—in the conditions for modulational instability. The role of relativistic effects on the linear dispersion laws and on envelope soliton solutions of the NLSE is discussed.
Integrating agricultural land-use and management for conservation of a native grassland flora in a variegated landscape
Authors: McIntyre S.
Published: May 2016

Management of variegated landscapes (in which the native vegetation still forms the matrix but has been modified in a variable way) requires strategies to maintain or enhance existing vegetation within the context of human land-uses such as agriculture. Using rangelands in the New England region of New South Wales as an example, spatial patterns of land-use and modification are described. Management principles for conservation of herbaceous communities in areas of pastoral production are suggested, based on the following assumptions: 1) low intensity pasture utilization and management (i.e., limited fertilization, soil disturbance and grazing) is conducive to the maintenance of species richness at a local and regional scale; 2) stratification of management intensity on farms is compatible with viable grazing operations; 3) landscape context is important as effects of management may spread beyond the managed area; 4) spatial arrangement of land-uses could be optimized to maintain or increase diversity. Although our understanding of these issues is incomplete, there is general observational and theoretical support for them. Incorporation of principles derived from these assumptions in the farm planning process is a useful strategy for preserving grassland vegetation in landscapes where opportunities for reserve conservation are limited.
Fragile X Mental Retardation Protein (FMRP) controls diacylglycerol kinase activity in neurons
Authors: Tabet Ricardos , Moutin Enora , Becker Jérôme A. J. , Heintz Dimitri , Fouillen Laetitia , Flatter Eric , Krężel Wojciech , Alunni Violaine , Koebel Pascale , Dembélé Doulaye , Tassone Flora , Bardoni Barbara , Mandel Jean-Louis , Vitale Nicolas , Muller Dominique , Le Merrer Julie , Moine Hervé
Published: May 2016

Significance

Fragile X syndrome (FXS), the most frequent form of inherited intellectual disability, is caused by the absence of the protein Fragile X Mental Retardation Protein (FMRP) in neurons. In the absence of FMRP, the translation of a high number of mRNAs is increased in glutamatergic synapses, leading to abnormal synaptic function. It is unclear whether FMRP individually controls each of these mRNAs and whether some mRNAs are more important for the pathology. This study shows that FMRP mostly associates with and controls one main mRNA target in neurons, diacylglycerol kinase kappa (Dgkκ), a master regulator that controls two key signaling pathways activating protein synthesis. The deregulation of Dgkκ could account for many of the symptoms associated with FXS and could represent a novel therapeutic target.
Free-energy landscape of a hyperstable RNA tetraloop
Authors: Miner Jacob C. , Chen Alan A. , García Angel E.
Published: May 2016

Significance

We report a multistate folding free-energy landscape for a hyperstable RNA tetraloop obtained from high-performance molecular dynamic simulations under multiple temperature and pressure conditions. These studies advance previous successes of de novo folding of RNA tetraloops and our understanding of the folded landscape of basic RNA motifs. In addition to the canonical A-RNA conformation, our analysis describes de novo folding of a left-handed Z-RNA conformation and the formation of a purine Triplet, each showing differential stabilization as a function of temperature and pressure. These results provide important insights into the ability of all-atom RNA force fields to describe the conformational heterogeneity of the most basic RNA secondary structures and represent a significant advancement in the utility of RNA molecular dynamics for describing RNA thermodynamics.
Topological surface states interacting with bulk excitations in the Kondo insulator SmB
6
revealed via planar tunneling spectroscopy
Authors: Park Wan Kyu , Sun Lunan , Noddings Alexander , Kim Dae-Jeong , Fisk Zachary , Greene Laura H.
Published: May 2016

Significance

Topological insulators are an emerging class of quantum matter in which the nontrivial bulk band structure gives rise to topologically protected surface states. Most are weakly correlated band insulators such as Bi
2
Se
3
. Despite numerous investigations on the strongly correlated bulk Kondo insulator samarium hexaboride (SmB
6
), the topological nature of its surface states remained a mystery. Planar tunneling spectroscopy adopted in this work not only reveals spectroscopic signatures for the Dirac fermion surface states, but also reveals that their topological protection is not as robust as in weakly correlated systems due to interaction with collective bulk spin excitations. This finding suggests important implications on generic topological materials whose ground states are governed by strong correlations.
Automated pictographic illustration of discharge instructions with Glyph: impact on patient recall and satisfaction
Authors: Hill Brent , Perri-Moore Seneca , Kuang Jinqiu , Bray Bruce E , Ngo Long , Doig Alexa , Zeng-Treitler Qing
Published: May 2016

Objectives First, to evaluate the effect of standard vs pictograph-enhanced discharge instructions on patients’ immediate and delayed recall of and satisfaction with their discharge instructions. Second, to evaluate the effect of automated pictograph enhancement on patient satisfaction with their discharge instructions.

Materials and Methods Glyph, an automated healthcare informatics system, was used to automatically enhance patient discharge instructions with pictographs. Glyph was developed at the University of Utah by our research team. Patients in a cardiovascular medical unit were randomized to receive pictograph-enhanced or standard discharge instructions. Measures of immediate and delayed recall and satisfaction with discharge instructions were compared between two randomized groups: pictograph (n = 71) and standard (n = 73).

Results Study participants who received pictograph-enhanced discharge instructions recalled 35% more of their instructions at discharge than those who received standard discharge instructions. The ratio of instructions at discharge was: standard = 0.04 ± 0.03 and pictograph-enhanced = 0.06 ± 0.03. The ratio of instructions at 1 week post discharge was: standard = 0.04 ± 0.02 and pictograph-enhanced 0.04 ± 0.02. Additionally, study participants who received pictograph-enhanced discharge instructions were more satisfied with the understandability of their instructions at 1 week post-discharge than those who received standard discharge instructions.

Discussion Pictograph-enhanced discharge instructions have the potential to increase patient understanding of and satisfaction with discharge instructions.

Conclusion It is feasible to automatically illustrate discharge instructions and provide them to patients in a timely manner without interfering with clinical work. Illustrations in discharge instructions were found to improve patients’ short-term recall of discharge instructions and delayed satisfaction (1-week post hospitalization) with the instructions. Therefore, it is likely that patients’ understanding of and interaction with their discharge instructions is improved by the addition of illustrations.
The origin of the α-enhancement of massive galaxies
Authors: Segers Marijke C. , Schaye Joop , Bower Richard G. , Crain Robert A. , Schaller Matthieu , Theuns Tom
Published: May 2016

We study the origin of the stellar α-element-to-iron abundance ratio, [α/Fe]*, of present-day central galaxies, using cosmological, hydrodynamical simulations from the Evolution and Assembly of GaLaxies and their Environments (EAGLE) project. For galaxies with stellar masses of M* > 1010.5 M⊙, [α/Fe]* increases with increasing galaxy stellar mass and age. These trends are in good agreement with observations of early-type galaxies, and are consistent with a ‘downsizing’ galaxy formation scenario: more massive galaxies have formed the bulk of their stars earlier and more rapidly, hence from an interstellar medium that was mostly α-enriched by massive stars. In the absence of feedback from active galactic nuclei (AGNs), however, [α/Fe]* in M* > 1010.5 M⊙ galaxies is roughly constant with stellar mass and decreases with mean stellar age, extending the trends found for lower mass galaxies in both simulations with and without AGN. We conclude that AGN feedback can account for the α-enhancement of massive galaxies, as it suppresses their star formation, quenching more massive galaxies at earlier times, thereby preventing the iron from longer lived intermediate-mass stars (supernova Type Ia) from being incorporated into younger stars.
Reactive School Closure During Increased Influenza-Like Illness (ILI) Activity in Western Kentucky, 2013: A Field Evaluation of Effect on ILI Incidence and Economic and Social Consequences for Families
Authors: Russell Elizabeth S. , Zheteyeva Yenlik , Gao Hongjiang , Shi Jianrong , Rainey Jeanette J. , Thoroughman Douglas , Uzicanin Amra
Published: May 2016

Background.  School closures are an important mitigation strategy during influenza pandemic: if implemented early in a local outbreak, they can slow the disease spread in the surrounding community. During seasonal influenza epidemics, school closures may occur reactively, after the disease is already widespread in the community. Such reactive closures are often too late to reduce influenza transmission. However, they can provide data to determine under which circumstances they might be effective in reducing influenza-like illness (ILI) transmission.

Methods.  We conducted a household survey in a school district in Kentucky. District A closed after high student absenteeism due to influenza-like illness (ILI), whereas adjacent Districts B and C remained open. We collected data on self-reported ILI among household members in these 3 districts 2 weeks before the District A closure, during closure, and 2 weeks after reopening, and we evaluated economic and social consequences of school closure on student households in District A. The difference-in-differences method was applied to compare changes in ILI rates from before to after closure between districts.

Results.  Estimated average daily ILI rate decreased less in District A than in District B or C for the entire sample and when stratified by age groups (0–5 years old, 6–18 years old, and above 18 years old). Twenty-five percent of District A households reported ≥1 closure-related economic or social difficulty.

Conclusions.  Closing schools after a widespread ILI activity in District A did not reduce ILI transmission but caused difficulties for some households.
Objective Metric of Energy Absorbed in Tibial Plateau Fractures Corresponds Well to Clinician Assessment of Fracture Severity
Authors: Kempton Laurence B. , Dibbern Kevin , Anderson Donald D. , Morshed Saam , Higgins Thomas F. , Marsh J. Lawrence , McKinley Todd O.
Published: May 2016

Objectives:

Determine the agreement between subjective assessments of fracture severity and an objective computed tomography (CT)-based metric of fracture energy in tibial plateau fractures.

Methods:

Six fellowship-trained orthopaedic trauma surgeons independently rank-ordered 20 tibial plateau fractures in terms of severity based on anteroposterior and lateral knee radiographs. A CT-based image analysis methodology was used to quantify the fracture energy, and agreement between the surgeons' severity rankings and the fracture energy metric was tested by computing their concordance, a statistical measure that estimates the probability that any 2 cases would be ranked with the same ordering by 2 different raters or methods.

Results:

Concordance between the 6 orthopaedic surgeons ranged from 82% to 93%, and concordance between surgeon severity rankings and the computed fracture energy ranged from 73% to 78%.

Conclusions:

There is a high level of agreement between experienced surgeons in their assessments of tibial plateau fracture severity, and a slightly lower agreement between the surgeon assessments and an objective CT-based metric of fracture energy. Taken together, these results suggest that experienced surgeons share a similar understanding of what makes a tibial plateau fracture more or less severe, and an objective CT-based metric of fracture energy captures much but not all of that information. Further research is ongoing to characterize the relationship between surgeon assessments of severity, fracture energy, and the eventual clinical outcomes for patients with fractures of the tibial plateau.
Alignment After Intramedullary Nailing of Distal Tibia Fractures Without Fibula Fixation
Authors: De Giacomo Anthony F. , Tornetta Paul
Published: May 2016

Objective:

To evaluate the efficacy of intramedullary nailing of distal tibia fractures using modern techniques, without fibula fixation, in obtaining and maintaining alignment.

Design:

Retrospective case review.

Setting:

Level-I academic trauma center.

Patients:

One hundred thirty-two consecutive patients with distal tibia fractures.

Intervention:

Intramedullary nail of distal tibia fracture, without fibula fixation, was performed in consecutive patients using modern reduction techniques.

Main Outcome Measures:

Malalignment and malunion were defined as >5 degrees of varus/valgus angulation or anterior/posterior angulation on the initial postoperative or final anteroposterior and lateral x-rays.

Results:

There were 122 consecutive patients (86 men and 36 women) 16–93 years of age (average, 43 years) with 36 (30%) open and 85 (70%) closed fractures with complete follow-up. Mechanism of injury did not predict the presence or level of fibula fracture. Upon presentation, varus/valgus and procurvatum/recurvatum angulation was greatest when the fibula was fractured at the level of the tibia fracture (P = 0.001 and 0.028). The most common intraoperative reduction aids were nailing in relative extension, transfixion external fixation, and clamps at the fracture site. The OTA fracture type or level/presence of fibula fracture did not influence malalignment (P = 0.86 and 0.66), malunion (P = 0.81 and 0.79), or the change in alignment during union, which averaged 0.9 degrees.

Conclusions:

We found an overall low rate of both malalignment (2%) and malunion (3%) after intramedullary nailing of distal tibial shaft fracture without fibula fixation. We conclude that when modern nailing techniques are used, which allow for confirmation of reduction by visualization in fluoroscopy, from nail placement to distal interlocking, fibula fixation is not necessary to obtain or maintain alignment. Furthermore, standard 2 medial to lateral screws distally afford adequate stability to hold the reduction during union with a 0.9-degree difference in the initial postoperative and final united films.

Level of Evidence:

Therapeutic level IV. See Instructions for Authors for a complete description of levels of evidence.
Rim Plating of Posterolateral Fracture Fragments (PLFs) Through a Modified Anterolateral Approach in Tibial Plateau Fractures
Authors: Cho Jae-Woo , Samal Puspak , Jeon Young-Sik , Oh Chang-Wug , Oh Jong-Keon
Published: May 2016

Posterolateral fracture fragments in tibial plateau fractures have proven to be particularly difficult to reduce and adequately repair internally through anterior or anterolateral approaches, although they are safer. Posterior and posterolateral approaches offer a direct approach for the reduction and fixation of plates, but they have several limitations. Here, we have proposed a modified anterolateral approach, which ensures a safe and effective technique for the reduction and fixation of posterolateral fracture fragments, aided by our innovative rim plate.
Ilizarov bone transport versus fibular graft for reconstruction of tibial bone defects in children
Authors: Abdelkhalek Mostafa , El-Alfy Barakat , Ali Ayman M.
Published: May 2016

The aim of this study was to compare the results of treatment of segmental tibial defects in the pediatric age group using an Ilizarov external fixator versus a nonvascularized fibular bone graft. This study included 24 patients (age range from 5.5 to 15 years) with tibial bone defects: 13 patients were treated with bone transport (BT) and 11 patients were treated with a nonvascularized fibular graft (FG). The outcome parameters were bone results (union, deformity, infection, leg-length discrepancy) and functional results: external fixation index and external fixation time. In group A (BT), one patient developed refracture at the regenerate site, whereas, in group B (FG), after removal of the external fixator, one of the FGs developed a stress fracture. The external fixator time in group A was 10.7 months (range 8–14.5) versus 7.8 months (range 4–11.5 months) in group B (FG). In group A (BT), one patient had a limb-length discrepancy (LLD), whereas, in group B (FG), three patients had LLD. The functional and bone results of the Ilizarov BT technique were excellent in 23.1 and 30.8%, good in 38.5 and 46.2, fair in 30.8 and 15.4, and poor in 7.6 and 7.6%, respectively. The poor functional result was related to the poor bone result because of prolonged external fixator time resulting in significant pain, limited ankle motion, whereas the functional and bone results of fibular grafting were excellent in 9.1 and 18.2%, good in 63.6 and 45.5%, fair in 18.2 and 27.2%, and poor in 9.1 and 9.1%, respectively. Segmental tibial defects can be effectively treated with both methods. The FG method provides satisfactory results, with early removal of the external fixator. However, it had a limitation in patients with severe infection and those with LLD. Also, it requires a long duration of limb bracing until adequate hypertrophy of the graft. The Ilizarov method has the advantages of early weight bearing, treatment of postinfection bone defect in a one-stage surgery, and the possibility to treat the associated LLD. However, it has a long external fixation time.
An unusual case of chondrolysis of the hip: a possible etiology for a rare condition – a case report
Authors: Ruiz Picazo David , Doñate Pérez Francisco , Jiménez Ortega Plácido , Gaspar Aparicio Natalia
Published: May 2016

Idiopathic chondrolysis of the hip (ICH) is a rare condition of unknown etiology, and is characterized by rapid, progressive destruction of the articular cartilage in the coxofemoral joint. This condition has an insidious onset, and is observed more commonly in female preadolescents. Patients report intense pain, motion restriction, and often present with an antalgic gait. Medical imaging techniques are required to make a differential diagnosis and biological markers for inflammation and infection should be evaluated. Avascular necrosis, septic arthritis, and juvenile idiopathic arthritis are the primary alternatives that should be precluded before making a diagnosis. Conservative treatment focuses on pain control and preservation of joint mobility. However, surgical treatment may be an option for these patients. We present a rare case of a 10-year-old boy where imaging tests and physical examination were consistent with conventional idiopathic hip chondrolysis. Following hip joint biopsy and culture, we observed the presence of bacteria originating from the mouth, which could have been responsible for the pathogenesis of ICH. This is the first report of ICH in which common bacteria of the mouth were found upon joint biopsy. In addition, with respect to the pathogenesis of hip chondrolysis, this case emphasizes that numerous factors are involved, many of which remain unknown. Level of Evidence: V.
Surgical Management of Civilian Gunshot-Induced Spinal Cord Injury
Authors: Nwosu Kenneth , Eftekhary Nima , McCoy Eric , Bhalla Amandeep , Fukunaga Dudley , Rolfe Kevin
Published: May 2016

Study Design.

Retrospective chart review.

Objective.

Assess appropriate utilization of surgery for civilian gunshot-induced spinal cord injuries (CGSWSCI) according to literature standards in a large cohort.

Summary of Background Data.

CGSWSCI are mechanically stable injuries that rarely require surgery. Nonetheless, we continue to see high numbers of these patients undergo surgical treatment. This study compares indications for surgeries performed in a large cohort of CGSWSCI patients to established indications for surgical management of such injuries. The rate of over-utilization of surgical management was calculated.

Methods.

Four hundred eighty-nine CGSWSCI patients transferred for rehabilitation to our institution between 2000 and 2014 were identified. Retrospective chart review was performed to identify patients who underwent initial surgical treatment, the specific surgeries performed, and indications given. We assessed appropriateness of surgery according to literature standards. Patients treated surgically were followed to assess for complications and the need for additional intervention and compared to nonsurgical patients. Secondarily, visual analog scale pain scores (0–10) and patient perceived improvement were compared between surgical and nonsurgical patients after telephone survey of both groups.

Results.

Of 489 patients, 91 (18%) underwent initial surgery. Of 91 surgeries, 69 (75%) were not indicated by literature standards. Five of 91 (5.5%) of initially operated patients required a secondary surgery compared with two of 398 (0.5%) of the nonoperative group (P = 0.003). Over-utilization rate of the entire cohort was 14.1%. No difference was seen for pain scores or patient perceived improvement between operative and nonoperative patients.

Conclusion.

We report a high overutilization rate (14%) of surgery for CGSWSCI in our cohort. Surgical management was associated with higher infection and secondary surgery rates compared to nonsurgical management. Surgery done without a clear, demonstrable benefit poses unnecessary risk to patients and accumulates unwarranted healthcare costs.

Level of Evidence: 3
MRI Signal Intensity Classification in Cervical Ossification of the Posterior Longitudinal Ligament
Authors: Ito Kenyu , Imagama Shiro , Ito Keigo , Ito Zenya , Ando Kei , Kobayashi Kazuyoshi , Hida Tetsuro , Tsushima Mikito , Ishikawa Yoshimoto , Matsumoto Akiyuki , Machino Masaaki , Nishida Yoshihiro , Ishiguro Naoki , Kato Fumihiko
Published: May 2016

Study Design.

Prospective cohort study.

Objective.

To investigate whether classification of increased signal intensity (ISI) on magnetic resonance imaging (MRI) of spinal cord in patients with cervical ossification of the posterior longitudinal ligament (C-OPLL) reflects severity of myelopathy and surgical outcome.

Summary of Background Data.

The relationship between classification of ISI on C-OPLL and severity is unknown.

Methods.

The 119 consecutive patients (91 men, 28 women) with C-OPLL who underwent surgery were enrolled. T2-weighted MRI was performed before surgery and ISI was classified into three groups as follows, Grade 0, none; Grade 1, light (obscure); and Grade 2, intense (bright). The severity of myelopathy and surgical outcome were evaluated by the Japanese Orthopedic Association score. To determine factors that influence ISI, the change of the spinal cord cross-sectional area (SCA) during flexion and extension was calculated by computed tomography after myelography.

Results.

The preoperative MRI showed 55 patients in Grade 0, 46 patients in Grade 1, and 18 patients in Grade 2. The preoperative Japanese Orthopedic Association score (Grade 0, 11.2; Grade 1, 10.3; Grade 2, 9.6 points) and surgical outcome got worsened with increasing ISI grade. The patients in Grade 2 had a longer duration of disease, while those in Grade 1 and Grade 2 had a larger change of SCA during flexion and extension (Grade 0, 4.8 mm2; Grade 1, 7.3 mm2; Grade 2, 7.8 mm2). However age, alignment of the cervical spine, range of motion, and occupying ratio of the ossification were not different in the three grades.

Conclusion.

Grade of ISI correlated with preoperative severity of myelopathy and surgical outcome in patients with C-OPLL. Increased signal intensity of the spinal cord on MRI was associated with a larger change in SCA and longer duration of disease.

Level of Evidence: 3
The Lapidus for a Failed Hallux Valgus Surgery
Authors: Hunter Joshua G. , Myerson Mark S. , Ellington J. K.
Published: May 2016

Recurrent hallux valgus (HV) can be a difficult complication for both the patient and the surgeon. There are many options to correct the recurring deformity including osteotomies and proximal or distal arthrodesis. More recently the Lapidus procedure or its modifications has been shown to be an effective method of treating various complications of HV. In this manuscript we present the considerations for treatment of recurrent HV with the Lapidus procedure. We note that the Lapidus procedure and its modifications can reliably correct recurrent HV deformity with or without instability of the first tarsometatarsal joint with no increased risk of complication compared with a primary Lapidus procedure.

Level of Evidence: Diagnostic Level 5. See Instructions for Authors for a complete description of levels of evidence.
Alternative Method to Remove Polyethylene Liner from INBONE Total Ankle Arthroplasty: Operative Technique
Authors: Neumann Julie A. , Schiff Adam P. , Wooster Benjamin M. , Adams Samuel B. , Easley Mark E.
Published: May 2016

Total ankle arthroplasty (TAA) is an evolving treatment indicated in end-stage idiopathic, posttraumatic, or inflammatory ankle arthrosis. Currently, there are 4 Food and Drug Administration approved TAAs systems available in the United States, one of which is the INBONE TAA. The INBONE TAA is a third generation ankle implant that has been approved by the Food and Drug Administration since 2005. It is a modular, fixed-bearing system that utilizes a drill hole through the calcaneus and talus to align the components. Over the past 10 years, there has been a steady increase in the number of TAAs performed in the United States. Undoubtedly, with the increase in the number of INBONE TAA being placed, the number of revision INBONE TAA will increase as well. Revisions may range from a simple polyethylene liner exchange to revision of all 3 components. In most revision scenarios, the polyethylene component will need to be removed. To our knowledge, the only described technique to remove the polyethylene component is in the INBONE TAA operative technique guide, which is technically challenging. Consequently, we developed a more efficient and technically easier method to remove the polyethylene component of the INBONE TAA.

Level of Evidence: Diagnostic Level 5. See Instructions for Authors for a complete description of levels of evidence.