bluuebunny/crossref_metadata_2025 huggingface dataset:
Input‐series and output‐series connected modular single‐switch flyback converter operating in the discontinuous conduction mode
Authors: Pagliosa Mauro André , Faust Rafael Gomes , Lazzarin Telles Brunelli , Barbi Ivo
Published: April 2016

This study proposes a modular isolated dc–dc converter, based on the input‐series and output‐series connection of flyback converters operating in discontinuous conduction mode, as an alternative to provide higher voltage capability for medium‐voltage applications (1–10 kV), from low‐voltage semiconductors and passive components. The proposed architecture allows the modular system to operate with a simplified control scheme thanks to an intrinsic voltage‐balancing mechanism. The voltage‐balancing mechanism is investigated by theoretical analysis, both for steady‐state and dynamic operations. A small‐signal ac modelling of the architecture is developed to design the total output‐voltage controller. To experimentally verify the proposed technique, a laboratory prototype system with three single‐switch flyback converters, with 3 kW output power, 600 V dc input and output voltages, and 40 kHz of switching frequency was built.
Extensive Cervicomediastinal Emphysema from Mastoid Injury
Authors: Ahmed Yasmina , Ng Matthew
Published: April 2016

Traumatic cervicomediastinal emphysema resulting from isolated head trauma is a rare occurrence. Herein, we describe a patient who sustained a closed mastoid injury after being struck with a batted baseball, resulting in acute extensive cervicomediastinal emphysema. Upon further assessment, the patient's aerodigestive tract was determined to have remained intact and unaffected by the injury. The source of soft-tissue air originated from the fractured mastoid. This case demonstrates the protective properties of a well-pneumatized mastoid. Furthermore, we elucidate the pathway by which the mastoid air entered and spread into the surrounding soft tissues of the neck and into the chest.
An adaptable dual species effusive source and Zeeman slower design demonstrated with Rb and Li
Authors: Bowden William , Gunton Will , Semczuk Mariusz , Dare Kahan , Madison Kirk W.
Published: April 2016

We present a dual-species effusive source and Zeeman slower designed to produce slow atomic beams of two elements with a large mass difference and with very different oven temperature requirements. We demonstrate this design for the case of 6Li and 85Rb and achieve magneto-optical trap (MOT) loading rates equivalent to that reported in prior work on dual species (Rb+Li) Zeeman slowers operating at the same oven temperatures. Key design choices, including thermally separating the effusive sources and using a segmented coil design to enable computer control of the magnetic field profile, ensure that the apparatus can be easily modified to slow other atomic species. By performing the final slowing using the quadrupole magnetic field of the MOT, we are able to shorten our Zeeman slower length making for a more compact system without compromising performance. We outline the construction and analyze the emission properties of our effusive sources. We also verify the performance of the source and slower, and we observe sequential loading rates of 12 × 108 atoms/s for a Rb oven temperature of 140 °C and 1.1 × 108 atoms/s for a Li reservoir at 460 °C, corresponding to reservoir lifetimes for continuous operation of 10 and 4 years, respectively.
Contact stiffness and damping of liquid films in dynamic atomic force microscope
Authors: Xu Rong-Guang , Leng Yongsheng
Published: April 2016

The mechanical properties and dissipation behaviors of nanometers confined liquid films have been long-standing interests in surface force measurements. The correlation between the contact stiffness and damping of the nanoconfined film is still not well understood. We establish a novel computational framework through molecular dynamics (MD) simulation for the first time to study small-amplitude dynamic atomic force microscopy (dynamic AFM) in a simple nonpolar liquid. Through introducing a tip driven dynamics to mimic the mechanical oscillations of the dynamic AFM tip-cantilever assembly, we find that the contact stiffness and damping of the confined film exhibit distinct oscillations within 6-7 monolayer distances, and they are generally out-of-phase. For the solid-like film with integer monolayer thickness, further compression of the film before layering transition leads to higher stiffness and lower damping, while much lower stiffness and higher damping occur at non-integer monolayer distances. These two alternating mechanisms dominate the mechanical properties and dissipation behaviors of simple liquid films under cyclic elastic compression and inelastic squeeze-out. Our MD simulations provide a direct picture of correlations between the structural property, mechanical stiffness, and dissipation behavior of the nanoconfined film.
Compact high voltage, high peak power, high frequency transformer for converter type modulator applications
Authors: Reghu T. , Mandloi V. , Shrivastava Purushottam
Published: April 2016

The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.
Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study
Authors: Goracci G. , Arbe A. , Alegría A. , Su Y. , Gasser U. , Colmenero J.
Published: April 2016

We have combined X-ray diffraction, neutron diffraction with polarization analysis, small angle neutron scattering, differential scanning calorimetry, and broad band dielectric spectroscopy to investigate the structure and dynamics of binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with either water or tetrahydrofuran (THF) at different concentrations. Aqueous mixtures are characterized by a highly heterogeneous structure where water clusters coexist with an underlying nano-segregation of main chains and side groups of the polymeric matrix. THF molecules are homogeneously distributed among the polymeric nano-domains for concentrations of one THF molecule/monomer or lower. A more heterogeneous situation is found for higher THF amounts, but without evidences for solvent clusters. In THF-mixtures, we observe a remarkable reduction of the glass-transition temperature which is enhanced with increasing amount of solvent but seems to reach saturation at high THF concentrations. Adding THF markedly reduces the activation energy of the polymer β-relaxation. The presence of THF molecules seemingly hinders a slow component of this process which is active in the dry state. The aqueous mixtures present a strikingly broad glass-transition feature, revealing a highly heterogeneous behavior in agreement with the structural study. Regarding the solvent dynamics, deep in the glassy state all data can be described by an Arrhenius temperature dependence with a rather similar activation energy. However, the values of the characteristic times are about three orders of magnitude smaller for THF than for water. Water dynamics display a crossover toward increasingly higher apparent activation energies in the region of the onset of the glass transition, supporting its interpretation as a consequence of the freezing of the structural relaxation of the surrounding matrix. The absence of such a crossover (at least in the wide dynamic window here accessed) in THF is attributed to the lack of cooperativity effects in the relaxation of these molecules within the polymeric matrix.
Bounce harmonic Landau damping of plasma waves
Authors: Anderegg F. , Affolter M. , Kabantsev A. A. , Dubin D. H. E. , Ashourvan A. , Driscoll C. F.
Published: April 2016

We present measurements of bounce harmonic Landau damping due to z-variations in the plasma potential, created by an azimuthally symmetric “squeeze” voltage Vs applied to the cylindrical wall. Traditional Landau damping on spatially uniform plasma is weak in regimes where the wave phase velocity vph≡ω/k is large compared to the thermal velocity. However, z-variations in plasma density and potential create higher spatial harmonics, which enable resonant wave damping by particles with bounce-averaged velocities vph/n, where n is an integer. In our geometry, the applied squeeze predominantly generates a resonance at vph/3. Wave-coherent laser induced fluorescence measurements of particle velocities show a distinctive Landau damping signature at vph/3, with amplitude proportional to the applied Vs. The measured (small amplitude) wave damping is then proportional to Vs2, in quantitative agreement with theory over a range of 20 in temperature. Significant questions remain regarding “background” bounce harmonic damping due to ubiquitous confinement fields and regarding the saturation of this damping at large wave amplitudes.
Current-induced three-dimensional domain wall propagation in cylindrical NiFe nanowires
Authors: Wong D. W. , Purnama I. , Lim G. J. , Gan W. L. , Murapaka C. , Lew W. S.
Published: April 2016

We report on the magnetization configurations in single NiFe cylindrical nanowires grown by template-assisted electrodeposition. Angular anisotropic magnetoresistance measurements reveal that a three-dimensional helical domain wall is formed naturally upon relaxation from a saturated state. Micromagnetic simulations support the helical domain wall properties and its reversal process, which involves a splitting of the clockwise and anticlockwise vortices. When a pulsed current is applied to the nanowire, the helical domain wall propagation is observed with a minimum current density needed to overcome its intrinsic pinning.
Theory of optical transitions in π-conjugated macrocycles
Authors: Marcus Max , Coonjobeeharry Jaymee , Barford William
Published: April 2016

We describe a theoretical and computational investigation of the optical properties of π-conjugated macrocycles. Since the low-energy excitations of these systems are Frenkel excitons that couple to high-frequency dispersionless phonons, we employ the quantized Frenkel-Holstein model and solve it via the density matrix renormalization group (DMRG) method. First we consider optical emission from perfectly circular systems. Owing to optical selection rules, such systems radiate via two mechanisms: (i) within the Condon approximation, by thermally induced emission from the optically allowed j = ± 1 states and (ii) beyond the Condon approximation, by emission from the j = 0 state via coupling with a totally non-symmetric phonon (namely, the Herzberg-Teller effect). Using perturbation theory, we derive an expression for the Herzberg-Teller correction and show via DMRG calculations that this expression soon fails as ħ ω/J and the size of the macrocycle increase. Next, we consider the role of broken symmetry caused by torsional disorder. In this case the quantum number j no longer labels eigenstates of angular momentum, but instead labels localized local exciton groundstates (LEGSs) or quasi-extended states (QEESs). As for linear polymers, LEGSs define chromophores, with the higher energy QEESs being extended over numerous LEGSs. Within the Condon approximation (i.e., neglecting the Herzberg-Teller correction) we show that increased disorder increases the emissive optical intensity, because all the LEGSs are optically active. We next consider the combined role of broken symmetry and curvature, by explicitly evaluating the Herzberg-Teller correction in disordered systems via the DMRG method. The Herzberg-Teller correction is most evident in the emission intensity ratio, I00/I01. In the Condon approximation I00/I01 is a constant function of curvature, whereas in practice it vanishes for closed rings and only approaches a constant in the limit of vanishing curvature. We calculate the optical spectra of a model system, cyclo-poly(para-phenylene ethynylene), for different amounts of torsional disorder within and beyond the Condon approximation. We show how broken symmetry and the Herzberg-Teller effect explain the spectral features. The Herzberg-Teller correction to the 0–1 emission vibronic peak is always significant. Finally, we note the qualitative similarities between the optical properties of conformationally disordered linear polymers and macrocycles in the limit of sufficiently large disorder, because in both cases they are determined by the optical properties of curved chromophores.
Propagation of pore pressure diffusion waves in saturated dual-porosity media (II)
Authors: Yang Duoxing , Li Qi , Zhang Lianzhong
Published: April 2016

A mechanism has been established for pressure diffusion waves in dual-porosity media. Pressure diffusion waves are heavily damped with relatively low velocities and short wavelengths. The characteristic frequency dominates the attenuation behavior of pressure diffusions and separates wave fields into two asymptotic regimes: relaxed and unrelaxed. Characteristic delay times control the pressure diffusion between the matrix and the fractures. The transition zones in wavelength and attenuation peak shift toward high frequencies when the characteristic delay time decreases. In contrast, the transition zones in both phase and group velocity shift toward low frequencies as the characteristic time of the delay increases. In a spatially dependent diffusivity field, the pressure diffusion waves in dual-porosity media obey an accumulation-depletion law.
Metastable honeycomb SrTiO3/SrIrO3 heterostructures
Authors: Anderson T. J. , Ryu S. , Zhou H. , Xie L. , Podkaminer J. P. , Ma Y. , Irwin J. , Pan X. Q. , Rzchowski M. S. , Eom C. B.
Published: April 2016

Recent theory predictions of exotic band topologies in (111) honeycomb perovskite SrIrO3 layers sandwiched between SrTiO3 have garnered much attention in the condensed matter physics and materials communities. However, perovskite SrIrO3 film growth in the (111) direction remains unreported, as efforts to synthesize pure SrIrO3 on (111) perovskite substrates have yielded films with monoclinic symmetry rather than the perovskite structure required by theory predictions. In this study, we report the synthesis of ultra-thin metastable perovskite SrIrO3 films capped with SrTiO3 grown on (111) SrTiO3 substrates by pulsed laser deposition. The atomic structure of the ultra-thin films was examined with scanning transmission electron microscopy (STEM), which suggests a perovskite layering distinct from the bulk SrIrO3 monoclinic phase. In-plane 3-fold symmetry for the entire heterostructure was confirmed using synchrotron surface X-ray diffraction to measure symmetry equivalent crystal truncation rods. Our findings demonstrate the ability to stabilize (111) honeycomb perovskite SrIrO3, which provides an experimental avenue to probe the phenomena predicted for this material system.
Robust and compact entanglement generation from diode-laser-pumped four-wave mixing
Authors: Lawrie B. J. , Yang Y. , Eaton M. , Black A. N. , Pooser R. C.
Published: April 2016

Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein-Podolsky-Rosen entanglement and intensity difference squeezing. Diode-laser-pumped four-wave mixing processes have recently been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generated by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. This robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.
Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying
Authors: Joo Jinmyoung , Defforge Thomas , Loni Armando , Kim Dokyoung , Li Z. Y. , Sailor Michael J. , Gautier Gael , Canham Leigh T.
Published: April 2016

The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO2 solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yield (>32% at room temperature) has been achieved, prompting the need for further detailed studies to establish the dominant causes of such an improvement.
Low absorption loss p-AlGaN superlattice cladding layer for current-injection deep ultraviolet laser diodes
Authors: Martens M. , Kuhn C. , Ziffer E. , Simoneit T. , Kueller V. , Knauer A. , Rass J. , Wernicke T. , Einfeldt S. , Weyers M. , Kneissl M.
Published: April 2016

Current injection into AlGaN-based laser diode structures with high aluminum mole fractions for deep ultraviolet emission is investigated. The electrical characteristics of laser diode structures with different p-AlGaN short period superlattice (SPSL) cladding layers with various aluminum mole fractions are compared. The heterostructures contain all elements that are needed for a current-injection laser diode including cladding and waveguide layers as well as an AlGaN quantum well active region emitting near 270 nm. We found that with increasing aluminum content in the p-AlGaN cladding, the diode turn-on voltage increases, while the series resistance slightly decreases. By introducing an SPSL instead of bulk layers, the operating voltage is significantly reduced. A gain guided broad area laser diode structure with transparent p-Al0.70Ga0.30N waveguide layers and a transparent p-cladding with an average aluminum content of 81% was designed for strong confinement of the transverse optical mode and low optical losses. Using an optimized SPSL, this diode could sustain current densities of more than 4.5 kA/cm2.
Experimental generation of tripartite polarization entangled states of bright optical beams
Authors: Wu Liang , Yan Zhihui , Liu Yanhong , Deng Ruijie , Jia Xiaojun , Xie Changde , Peng Kunchi
Published: April 2016

The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.
Harmonic and reactive behavior of the quasiparticle tunnel current in SIS junctions
Authors: Rashid H. , Desmaris V. , Pavolotsky A. , Belitsky V.
Published: April 2016

In this paper, we show theoretically and experimentally that the reactive quasiparticle tunnel current of the superconductor tunnel junction could be directly measured at specific bias voltages for the higher harmonics of the quasiparticle tunnel current. We used the theory of quasiparticle tunneling to study the higher harmonics of the quasiparticle tunnel current in superconducting tunnel junction in the presence of rf irradiation. The impact of the reactive current on the harmonic behavior of the quasiparticle tunnel current was carefully studied by implementing a practical model with four parameters to model the dc I-V characteristics of the superconducting tunnel junction. The measured reactive current at the specific bias voltage is in good agreement with our theoretically calculated reactive current through the Kramers-Kronig transform. This study also shows that there is an excellent correspondence between the behavior of the predicted higher harmonics using the previously established theory of quasiparticle tunnel current in superconducting tunnel junctions by J.R. Tucker and M.J. Feldman and the measurements presented in this paper.
What do Life Science employers look for in graduates?
Authors: Grando Danilla , Pocknee Catherine , Clarke Bronwyn , Jollands Margaret
Published: April 2016

As part of an Australian Government Office for Learning and Teaching (OLT) grant to develop graduate employability through partnerships with industry and professional associations1, RMIT University invited industry representatives from Life Science (microbiology focused) professions to a focus group to discuss their views on desirable graduate traits and attitudes. Subsequently current Life Science students at RMIT were also invited to focus groups. Using an expanded framework for graduate employability2, their responses were coded and analysed and compared with responses from similar focus groups from other RMIT programs.
Embedding research ethics and integrity into undergraduate practical classes
Authors: Waller Karena L , Barr Daniel P , Taylor Paul M , Wijburg Odilia L
Published: April 2016

The core principles of research ethics and integrity that underpin the responsible conduct of research are critical to the design and performance of high quality research that generates excellent research data and outcomes that can be confidently trusted. Although many senior researchers have gained an in-depth appreciation and understanding of the importance of research ethics and integrity in the responsible conduct of research, many undergraduate students in science and technology disciplines do not obtain a basic, working knowledge of relevant research ethics and integrity principles as part of their degree. Here, we describe the introduction of a research ethics and integrity curriculum component into our third year practical classes, and the beneficial outcomes that we observed.
Ontogenetic and Long‐Term Diet Shifts of a Generalist Juvenile Predatory Fish in an Urban Estuary Undergoing Dramatic Changes in Habitat Availability
Authors: Hall‐Scharf Brittany J. , Switzer Theodore S. , Stallings Christopher D.
Published: April 2016

Vegetated areas such as seagrass beds provide food and essential habitat for many fish and invertebrate species. In particular, many economically important fishes depend on seagrass beds as nursery grounds. In recent decades, there has been a rapid decline in seagrass coverage due to the development of coastal areas worldwide, altering these ecosystems and their community structure. Within Tampa Bay (Florida's largest estuary), seagrass coverage and water quality underwent a decline followed by a recovery over the past three decades; these changes may have altered the community structure of seagrass‐associated fauna. We examined the diets of juvenile Spotted Seatrout Cynoscion nebulosus, a common estuarine predator, to assess whether documented changes in water quality and habitat were reflected in their trophodynamics. Stomach contents of Spotted Seatrout from Tampa Bay were sampled during three different studies conducted in 1981–1982, 1991–1992, and 2005–2013. We analyzed data from these studies to compare the diet across size‐classes and time periods. Using canonical analysis of principal coordinates, we discerned significant differences in diet composition among size‐classes and among time periods. Ontogenetic shifts in diet during all three time periods were consistent with those previously reported, highlighting the plasticity of a generalist piscivore in a recovering seagrass ecosystem. Subtle shifts in diet were detected among the three time periods, suggesting that changes in seagrass coverage contributed to altered trophodynamics in this estuarine system. Our efforts highlight the utility of using a generalist piscivore's diet as a tool for monitoring and quantifying faunal shifts in an ecosystem.

Received July 21, 2015; accepted January 5, 2016 Published online April 18, 2016
A requirement for filopodia extension toward Slit during Robo-mediated axon repulsion
Authors: McConnell Russell E. , Edward van Veen J. , Vidaki Marina , Kwiatkowski Adam V. , Meyer Aaron S. , Gertler Frank B.
Published: April 2016

Axons navigate long distances through complex 3D environments to interconnect the nervous system during development. Although the precise spatiotemporal effects of most axon guidance cues remain poorly characterized, a prevailing model posits that attractive guidance cues stimulate actin polymerization in neuronal growth cones whereas repulsive cues induce actin disassembly. Contrary to this model, we find that the repulsive guidance cue Slit stimulates the formation and elongation of actin-based filopodia from mouse dorsal root ganglion growth cones. Surprisingly, filopodia form and elongate toward sources of Slit, a response that we find is required for subsequent axonal repulsion away from Slit. Mechanistically, Slit evokes changes in filopodium dynamics by increasing direct binding of its receptor, Robo, to members of the actin-regulatory Ena/VASP family. Perturbing filopodium dynamics pharmacologically or genetically disrupts Slit-mediated repulsion and produces severe axon guidance defects in vivo. Thus, Slit locally stimulates directional filopodial extension, a process that is required for subsequent axonal repulsion downstream of the Robo receptor.
Oxidized mitochondrial nucleoids released by neutrophils drive type I interferon production in human lupus
Authors: Caielli Simone , Athale Shruti , Domic Bojana , Murat Elise , Chandra Manjari , Banchereau Romain , Baisch Jeanine , Phelps Kate , Clayton Sandra , Gong Mei , Wright Tracey , Punaro Marilynn , Palucka Karolina , Guiducci Cristiana , Banchereau Jacques , Pascual Virginia
Published: April 2016

Autoantibodies against nucleic acids and excessive type I interferon (IFN) are hallmarks of human systemic lupus erythematosus (SLE). We previously reported that SLE neutrophils exposed to TLR7 agonist autoantibodies release interferogenic DNA, which we now demonstrate to be of mitochondrial origin. We further show that healthy human neutrophils do not complete mitophagy upon induction of mitochondrial damage. Rather, they extrude mitochondrial components, including DNA (mtDNA), devoid of oxidized (Ox) residues. When mtDNA undergoes oxidation, it is directly routed to lysosomes for degradation. This rerouting requires dissociation from the transcription factor A mitochondria (TFAM), a dual high-mobility group (HMG) protein involved in maintenance and compaction of the mitochondrial genome into nucleoids. Exposure of SLE neutrophils, or healthy IFN-primed neutrophils, to antiribonucleotide protein autoantibodies blocks TFAM phosphorylation, a necessary step for nucleoid dissociation. Consequently, Ox nucleoids accumulate within mitochondria and are eventually extruded as potent interferogenic complexes. In support of the in vivo relevance of this phenomenon, mitochondrial retention of Ox nucleoids is a feature of SLE blood neutrophils, and autoantibodies against Ox mtDNA are present in a fraction of patients. This pathway represents a novel therapeutic target in human SLE.
How Do Residents Spend Their Shift Time? A Time and Motion Study With a Particular Focus on the Use of Computers
Authors: Mamykina Lena , Vawdrey David K. , Hripcsak George
Published: April 2016

Purpose

To understand how much time residents spend using computers compared with other activities, and what residents use computers for.

Method

This time and motion study was conducted in June and July 2010 at NewYork-Presbyterian/Columbia University Medical Center with seven residents (first-, second-, and third-year) on the general medicine service. An experienced observer shadowed residents during a single day shift, captured all their activities using an iPad application, and took field notes. The activities were captured using a validated taxonomy of clinical activities, expanded to describe computer-based activities with a greater level of detail.

Results

Residents spent 364.5 minutes (50.6%) of their shift time using computers, compared with 67.8 minutes (9.4%) interacting with patients. In addition, they spent 292.3 minutes (40.6%) talking with others in person, 186.0 minutes (25.8%) handling paper notes, 79.7 minutes (11.1%) in rounds, 80.0 minutes (11.1%) walking or waiting, and 54.0 minutes (7.5%) talking on the phone. Residents spent 685 minutes (59.6%) multitasking. Computer-based documentation activities amounted to 189.9 minutes (52.1%) of all computer-based activities time, with 128.7 minutes (35.3%) spent writing notes and 27.3 minutes (7.5%) reading notes composed by others.

Conclusions

The study showed that residents spent considerably more time interacting with computers (over 50% of their shift time) than in direct contact with patients (less than 10% of their shift time). Some of this may be due to an increasing reliance on computing systems for access to patient data, further exacerbated by inefficiencies in the design of the electronic health record.
Ranking Practice Variability in the Medical Student Performance Evaluation: So Bad, It’s “Good”
Authors: Boysen Osborn Megan , Mattson James , Yanuck Justin , Anderson Craig , Tekian Ara , Fox John Christian , Harris Ilene B.
Published: April 2016

Purpose

To examine the variability among medical schools in ranking systems used in medical student performance evaluations (MSPEs).

Method

The authors reviewed MSPEs from U.S. MD-granting medical schools received by the University of California, Irvine emergency medicine and internal medicine residency programs during 2012–2013 and 2014–2015. They recorded whether the school used a ranking system, the type of ranking system used, the size and description of student categories, the location of the ranking statement and category legend, and whether nonranking schools used language suggestive of rank.

Results

Of the 134 medical schools in the study sample, the majority (n = 101; 75%) provided ranks for students in the MSPE. Most of the ranking schools (n = 63; 62%) placed students into named category groups, but the number and size of groups varied. The most common descriptors used for these 63 schools’ top, second, third, and lowest groups were “outstanding,” “excellent,” “very good,” and “good,” respectively, but each of these terms was used across a broad range of percentile ranks. Student ranks and school category legends were found in various locations. Many of the 33 schools that did not rank students included language suggestive of rank.

Conclusions

There is extensive variation in ranking systems used in MSPEs. Program directors may find it difficult to use MSPEs to compare applicants, which may diminish the MSPE’s value in the residency application process and negatively affect high-achieving students. A consistent approach to ranking students would benefit program directors, students, and student affairs officers.
Enrollment Management in Medical School Admissions: A Novel Evidence-Based Approach at One Institution
Authors: Burkhardt John C. , DesJardins Stephen L. , Teener Carol A. , Gay Steven E. , Santen Sally A.
Published: April 2016

Purpose

In higher education, enrollment management has been developed to accurately predict the likelihood of enrollment of admitted students. This allows evidence to dictate numbers of interviews scheduled, offers of admission, and financial aid package distribution. The applicability of enrollment management techniques for use in medical education was tested through creation of a predictive enrollment model at the University of Michigan Medical School (U-M).

Method

U-M and American Medical College Application Service data (2006–2014) were combined to create a database including applicant demographics, academic application scores, institutional financial aid offer, and choice of school attended. Binomial logistic regression and multinomial logistic regression models were estimated in order to study factors related to enrollment at the local institution versus elsewhere and to groupings of competing peer institutions. A predictive analytic “dashboard” was created for practical use.

Results

Both models were significant at P < .001 and had similar predictive performance. In the binomial model female, underrepresented minority students, grade point average, Medical College Admission Test score, admissions committee desirability score, and most individual financial aid offers were significant (P < .05). The significant covariates were similar in the multinomial model (excluding female) and provided separate likelihoods of students enrolling at different institutional types.

Conclusions

An enrollment-management-based approach would allow medical schools to better manage the number of students they admit and target recruitment efforts to improve their likelihood of success. It also performs a key institutional research function for understanding failed recruitment of highly desirable candidates.
Driving Performance of Residents after Six Consecutive Overnight Work Shifts
Authors: Huffmyer Julie L. , Moncrief Matthew , Tashjian Jessica A. , Kleiman Amanda M. , Scalzo David C. , Cox Daniel J. , Nemergut Edward C.
Published: April 2016

AbstractAbstract

Resident physicians have greater difficulty controlling speed and driving performance in the driving simulator after six consecutive night shifts. Reaction times are also increased with emphasis on increases in minor and major lapses in attention after six consecutive night shifts.

Background

Residency training requires work in clinical settings for extended periods of time, resulting in altered sleep patterns, sleep deprivation, and potentially deleterious effects on safe performance of daily activities, including driving a motor vehicle.

Methods

Twenty-nine anesthesiology resident physicians in postgraduate year 2 to 4 drove for 55 min in the Virginia Driving Safety Laboratory using the Driver Guidance System (MBFARR, LLC, USA). Two driving simulator sessions were conducted, one experimental session immediately after the final shift of six consecutive night shifts and one control session at the beginning of a normal day shift (not after call). Both sessions were conducted at 8:00 am. Psychomotor vigilance task testing was employed to evaluate reaction time and lapses in attention.

Results

After six consecutive night shifts, residents experienced significantly impaired control of all the driving variables including speed, lane position, throttle, and steering. They were also more likely to be involved in collisions. After six consecutive night shifts, residents had a significant increase in reaction times (281.1 vs. 298.5 ms; P = 0.001) and had a significant increase in the number of both minor (0.85 vs. 1.88; P = 0.01) and major lapses (0.00 vs. 0.31; P = 0.008) in attention.

Conclusions

Resident physicians have greater difficulty controlling speed and driving performance in the driving simulator after six consecutive night shifts. Reaction times are also increased with emphasis on increases in minor and major lapses in attention after six consecutive night shifts.
Injury and Liability Associated with Implantable Devices for Chronic Pain
Authors: Fitzgibbon Dermot R. , Stephens Linda S. , Posner Karen L. , Michna Edward , Rathmell James P. , Pollak Kelly A. , Domino Karen B.
Published: April 2016

AbstractAbstract

Claims related to surgical implantation of devices involved infection, inadequate pain relief, trauma to the cord or cauda equina, and retained catheter fragments. Claims related to implanted drug delivery system maintenance tended to involve more serious outcomes associated with medication administration errors and failure to recognize granuloma formation.

Background

Due to an increase in implantable device–related anesthesia pain medicine claims, the authors investigated anesthesia liability associated with these devices.

Methods

After institutional review board approval, the authors identified 148 pain medicine device claims from 1990 or later in the Anesthesia Closed Claims Project Database. Device-related damaging events included medication administration events, infections, hematomas, retained catheter fragments, cerebrospinal fluid leaks, cord or cauda equina trauma, device placed at wrong level, stimulator incorrectly programmed, delay in recognition of granuloma formation, and other issues.

Results

The most common devices were implantable drug delivery systems (IDDS; 64%) and spinal cord stimulators (29%). Device-related care consisted of surgical device procedures (n = 107) and IDDS maintenance (n = 41). Severity of injury was greater in IDDS maintenance claims (56% death or severe permanent injury) than in surgical device procedures (26%, P < 0.001). Death and brain damage in IDDS maintenance claims resulted from medication administration errors (n = 13; 32%); spinal cord injury resulted from delayed recognition of granuloma formation (n = 9; 22%). The most common damaging events for surgical device procedures were infections, inadequate pain relief, cord trauma, retained catheter fragments, and subcutaneous hygroma. Care was more commonly assessed as less than appropriate (78%) and payments more common (63%) in IDDS maintenance than in surgical device procedure claims (P < 0.001).

Conclusions

Half of IDDS maintenance claims were associated with death or permanent severe injury, most commonly from medication errors or failure to recognize progressive neurologic deterioration. Practitioners implanting or managing devices for chronic pain should exercise caution in these areas to minimize patient harm.
Heme Oxygenase-1 Mediates Neuroprotection Conferred by Argon in Combination with Hypothermia in Neonatal Hypoxia–Ischemia Brain Injury
Authors: Zhao Hailin , Mitchell Sian , Koumpa Stefania , Cui Yushi Tracy , Lian Qingquan , Hagberg Henrik , Johnson Mark R. , Takata Masao , Ma Daqing
Published: April 2016

AbstractAbstract

Argon–hypothermia treatment reduced both neuronal death in an in vitro neuronal culture model and brain infarct size in an in vivo rat model of neonatal asphyxia. The protective effects of argon–hypothermia involve both inhibition of apoptosis and neuroinflammation mechanisms and activation of cell survival pathways.

Background

Hypoxic–ischemic encephalopathy is a major cause of mortality and disability in the newborn. The authors investigated the protective effects of argon combined with hypothermia on neonatal rat hypoxic–ischemic brain injury.

Methods

In in vitro studies, rat cortical neuronal cell cultures were challenged by oxygen and glucose deprivation for 90 min and exposed to 70% Ar or N2 with 5% CO2 balanced with O2, at 33°C for 2 h. Neuronal phospho-Akt, heme oxygenase-1 and phospho-glycogen synthase kinase-3β expression, and cell death were assessed. In in vivo studies, neonatal rats were subjected to unilateral common carotid artery ligation followed by hypoxia (8% O2 balanced with N2 and CO2) for 90 min. They were exposed to 70% Ar or N2 balanced with oxygen at 33°, 35°, and 37°C for 2 h. Brain injury was assessed at 24 h or 4 weeks after treatment.

Results

In in vitro studies, argon–hypothermia treatment increased phospho-Akt and heme oxygenase-1 expression and significantly reduced the phospho-glycogen synthase kinase-3β Tyr-216 expression, cytochrome C release, and cell death in oxygen–glucose deprivation–exposed cortical neurons. In in vivo studies, argon–hypothermia treatment decreased hypoxia/ischemia-induced brain infarct size (n = 10) and both caspase-3 and nuclear factor-κB activation in the cortex and hippocampus. It also reduced hippocampal astrocyte activation and proliferation. Inhibition of phosphoinositide-3-kinase (PI3K)/Akt pathway through LY294002 attenuated cerebral protection conferred by argon–hypothermia treatment (n = 8).

Conclusion

Argon combined with hypothermia provides neuroprotection against cerebral hypoxia–ischemia damage in neonatal rats, which could serve as a new therapeutic strategy against hypoxic–ischemic encephalopathy.
Perioperative Diastolic Dysfunction in Patients Undergoing Noncardiac Surgery Is an Independent Risk Factor for Cardiovascular Events
Authors: Fayad Ashraf , Ansari Mohammed T. , Yang Homer , Ruddy Terrence , Wells George A.
Published: April 2016

AbstractAbstract

The authors have performed a random-effects meta-analysis that shows supportive evidence for perioperative diastolic dysfunction as an independent risk factor for adverse cardiovascular events after noncardiac surgery. The work supports the importance of increased awareness of perioperative diastolic dysfunction when considering the cardiac risk factors for noncardiac surgery.

Background

The prognostic value of perioperative diastolic dysfunction (PDD) in patients undergoing noncardiac surgery remains uncertain, and the current guidelines do not recognize PDD as a perioperative risk factor. This systematic review aimed to investigate whether existing evidence supports PDD as an independent predictor of adverse events after noncardiac surgery.

Methods

Ovid MEDLINE, PubMed, EMBASE, the Cochrane Library, and Google search engine were searched for English-language citations in April 2015 investigating PDD as a risk factor for perioperative adverse events in adult patients undergoing noncardiac surgery. Two reviewers independently assessed the study risk of bias. Extracted data were verified. Random-effects model was used for meta-analysis, and reviewers’ certainty was graded.

Results

Seventeen studies met eligibility criteria; however, 13 contributed to evidence synthesis. The entire body of evidence addressing the research question was based on a total of 3,876 patients. PDD was significantly associated with pulmonary edema/congestive heart failure (odds ratio [OR], 3.90; 95% CI, 2.23 to 6.83; 3 studies; 996 patients), myocardial infarction (OR, 1.74; 95% CI, 1.14 to 2.67; 3 studies; 717 patients), and the composite outcome of major adverse cardiovascular events (OR, 2.03; 95% CI, 1.24 to 3.32; 4 studies; 1,814 patients). Evidence addressing other outcomes had low statistical power, but higher long-term cardiovascular mortality was observed in patients undergoing open vascular repair (OR, 3.00; 95% CI, 1.50 to 6.00). Reviewers’ overall certainty of the evidence was moderate.

Conclusion

Evidence of moderate certainty indicates that PDD is an independent risk factor for adverse cardiovascular outcomes after noncardiac surgery.
Hexapod External Fixation of Tibia Fractures in Children
Authors: Iobst Christopher A.
Published: April 2016

Most tibia fractures in children can be treated nonoperatively. For fractures that do require surgery, however, the most common methods of management include plating or flexible nail insertion. Some fracture patterns, such as periphyseal fractures, fractures with bone and/or soft tissue loss, or fractures with delayed presentation, are not easily amenable to these techniques. Hexapod external fixators are especially helpful in these difficult cases. The purpose of this review is to discuss the principles of performing hexapod circular external fixation applied to pediatric tibia fractures. Some of the additional capabilities of the hexapod external fixator will also be highlighted.
Treating Life-Threatening Myocarditis by Blocking Interleukin-1*
Authors: Cavalli Giulio , Pappalardo Federico , Mangieri Antonio , Dinarello Charles A. , Dagna Lorenzo , Tresoldi Moreno
Published: April 2016

Objective:

Treatment of viral fulminant myocarditis relies on life support measures. Based on studies pointing to a role for the proinflammatory cytokine interleukin-1 in myocardial inflammation and contractile dysfunction, we treated a patient with fulminant viral myocarditis with the interleukin-1 receptor blocking agent anakinra. We report the response and discuss the biologic rationale of this novel treatment approach.

Design:

Case report.

Setting:

ICU.

Patient:

A 36-year-old woman who was hospitalized for fulminant myocarditis with biventricular failure and cardiogenic shock, acutely manifested with hypotension and dyspnea.

Interventions:

Following the progressive, life-threatening collapse of the cardiac function in spite of treatment with venous-arterial extracorporeal membrane oxygenation and mechanical circulatory support with a left ventricular assist device, treatment with the interleukin-1 receptor blocking agent anakinra 100 mg/d was started.

Measurements and Main Results:

The severe depression of cardiac function responded promptly to interleukin-1 inhibition. Within 4 days of treatment initiation, progressive clinical improvement allowed weaning from extracorporeal membrane oxygenation and removal of the percutaneous left ventricular assist device. The patient was discharged home and remains in excellent health at 12 months.

Conclusions:

Clinical and experimental evidence suggests that interleukin-1 blockade is effective against myocardial inflammation and contractile dysfunction, thus representing a promising candidate for the treatment of inflammatory heart failure. Although further confirmation is needed, these encouraging results indicate that anakinra may be a suitable treatment for fulminant myocarditis.