bluuebunny/crossref_metadata_2025 huggingface dataset:
Wissenswertes aus aktuellen Studien
Authors: Schikora Stephanie
Published: April 2018

Eine transiente Abnahme der Herzfunktion – dies war das unerwartete Ergebnis einer Studie, in der sich adipöse Patienten einer 8-wöchigen Crash-Diät unterzogen hatten. Hielten sie diese strenge Kalorienrestriktion ein, nahmen sie zwar erfolgreich ab, zu Beginn der Diät stieg der Fettgehalt im Herzen jedoch drastisch und die Herzfunktion verschlechtere sich. Patienten mit Herzproblemen sollten daher eine radikale Diät nicht ohne Wissen ihres Arztes starten.
An Aniline-Mediated Regioselective Synthesis of Quinoxalin-2-ones via the Condensation of α-Ketimine Esters with 2-Aminoanilines
Authors: Huynh Huy , Çalimsiz Selçuk , Wangun Hilaire , Rainey Trevor , McGinitie Teague , Liao Xiaoming , Yu Lizhi
Published: April 2018

A highly regioselective method for the condensation of α-ketimine esters with 2-aminoanilines for the construction of quinoxalin-2-one derivatives is described. The substrate scope with 2-aminoaniline derivatives and different α-keto esters is explored with yields ranging from 44 to 90% and typical isolated regioselectivities between 6.4 to >25:1.
Rund um die Rheumatologie
Authors: Grübler Beate
Published: April 2018

Der erstmals in Stuttgart verortete gemeinsame Jahreskongress der Deutschen Gesellschaft für Rheumatologie (DGRh), der Deutschen Gesellschaft für Orthopädische Rheumatologie (DGORh) und der Gesellschaft für Kinderund Jugendrheumatologie (GKJR) im September 2017 zählte 2 600 Teilnehmer und informierte in 54 wissenschaftlichen Sitzungen zu neuen Entwicklungen auf dem Gebiet der Rheumatologie. Über 300 Originalbeiträge zu neuen Studienergebnissen wurden im Rahmen der Abstract-Sessions und der Posterpräsentationen präsentiert. Inhaltlich wurden Themen beleuchtet, die einen hohen Grad an interdisziplinärem Arbeiten erfordern, wie z. B. die systemischen Vaskulitiden, Autoinflammationserkrankungen und Infektionen.
Status Quo und Zukunft der Therapie von Kuhmilchallergie
Authors: Niggemann Bodo
Published: April 2018

Kuhmilch ist ein wichtiger Nährstofflieferant, der zur gesunden und normalen Entwicklung beiträgt. Doch was, wenn Kinder allergisch auf Milchproteine reagieren? Ein Gespräch mit Prof. Bodo Niggemann, ehem. Komm. Direktor der Klinik für Pädiatrie m. S. Pneumologie und Immunologie der Universitätsklinik Charité in Berlin, über Diagnose, Therapie und aktuelle Forschungen.
Patientenorientierte Behandlung mit Lisdexamfetamin
Authors: Ameri Abdol A.
Published: April 2018

Im Jugendund besonders im Übergang in das Erwachsenenalter ändern sich die Bedürfnisse der ADHS-Patienten und ihre Erwartungen an die Therapie. Damit steigen auch die Anforderungen an eine effektive, bedarfsorientierte Behandlung. Das Prodrug-Stimulans Lisdexamfetamin (LDX; Elvanse®) verbessert die Kernsymptome der ADHS sowie die Funktionalität im Alltag und dies bei täglicher Einmalgabe über den ganzen Tag. Bei einer ins Erwachsenenalter persistierenden ADHS kann LDX weiterverordnet und die Therapiestabilität erhalten werden.
Lessons on electronic decoherence in molecules from exact modeling
Authors: Hu Wenxiang , Gu Bing , Franco Ignacio
Published: April 2018

Electronic decoherence processes in molecules and materials are usually thought and modeled via schemes for the system-bath evolution in which the bath is treated either implicitly or approximately. Here we present computations of the electronic decoherence dynamics of a model many-body molecular system described by the Su-Schrieffer-Heeger Hamiltonian with Hubbard electron-electron interactions using an exact method in which both electronic and nuclear degrees of freedom are taken into account explicitly and fully quantum mechanically. To represent the electron-nuclear Hamiltonian in matrix form and propagate the dynamics, the computations employ the Jordan-Wigner transformation for the fermionic creation/annihilation operators and the discrete variable representation for the nuclear operators. The simulations offer a standard for electronic decoherence that can be used to test approximations. They also provide a useful platform to answer fundamental questions about electronic decoherence that cannot be addressed through approximate or implicit schemes. Specifically, through simulations, we isolate basic mechanisms for electronic coherence loss and demonstrate that electronic decoherence is possible even for one-dimensional nuclear bath. Furthermore, we show that (i) decreasing the mass of the bath generally leads to faster electronic decoherence; (ii) electron-electron interactions strongly affect the electronic decoherence when the electron-nuclear dynamics is not pure-dephasing; (iii) classical bath models with initial conditions sampled from the Wigner distribution accurately capture the short-time electronic decoherence dynamics; (iv) model separable initial superpositions often used to understand decoherence after photoexcitation are only relevant in experiments that employ delta-like laser pulses to initiate the dynamics. These insights can be employed to interpret and properly model coherence phenomena in molecules.
What is measured by hyper-Rayleigh scattering from a liquid?
Authors: Rodriquez Micheal B. , Shelton David P.
Published: April 2018

Polarization and angle dependence of hyper-Rayleigh scattering (HRS) measured for liquid acetonitrile and dimethyl sulfoxide (DMSO) is analyzed in terms of contributions from randomly oriented molecules and additional contributions produced during intermolecular collisions and induced by the electric field of dissolved ions. All three contributions show the effect of long-range correlation, and the correlation functions are determined using the HRS observations combined with the results of molecular dynamics simulations. HRS from acetonitrile is polarized transverse to the scattering vector. This is due to long-range molecular orientation correlation produced by the dipole-dipole interaction, and correlation at distances r > 100 nm must be included to account for the HRS observations. Analysis of the HRS measurements for acetonitrile determines the length scale a = 0.185 nm for the long-range longitudinal and transverse orientation correlation functions BL=−2BT=a3/r3. Transverse polarized collision-induced HRS is also observed for acetonitrile, indicating long-range correlation of intermolecular modes. Strong longitudinal HRS is induced by the radial electric field of dissolved ions in acetonitrile. For DMSO, the angle between the molecular dipole and the vector part of the first hyperpolarizability tensor is about 100°. As a result, HRS from the randomly oriented molecules in DMSO is nearly unaffected by dipole correlation, and ion-induced HRS is weak. The strong longitudinal polarized HRS observed for DMSO is due to the collision-induced contribution, indicating long-range correlation of intermolecular modes. The HRS observations require correlation that has r−3 long-range asymptotic form, for molecular orientation and for intermolecular vibration and libration, for both acetonitrile and DMSO.
Transient dynamics of a quantum-dot: From Kondo regime to mixed valence and to empty orbital regimes
Authors: Cheng YongXi , Li ZhenHua , Wei JianHua , Nie YiHang , Yan YiJing
Published: April 2018

Based on the hierarchical equations of motion approach, we study the time-dependent transport properties of a strongly correlated quantum dot system in the Kondo regime (KR), mixed valence regime (MVR), and empty orbital regime (EOR). We find that the transient current in KR shows the strongest nonlinear response and the most distinct oscillation behaviors. Both behaviors become weaker in MVR and diminish in EOR. To understand the physical insight, we examine also the corresponding dot occupancies and the spectral functions, with their dependence on the Coulomb interaction, temperature, and applied step bias voltage. The above nonlinear and oscillation behaviors could be understood as the interplay between dynamical Kondo resonance and single electron resonant-tunneling.
Overheating instability of a thin conductor with respect to stratification
Authors: Garanin S. F. , Kuznetsov S. D.
Published: April 2018

We consider an overheating instability of a thin (compared to the skin depth) conductor with respect to stratification at the stage when its resistivity rises up to an electrical explosion. Temperature perturbations under such conditions are shown to grow in proportion to resistivity. In the model, when resistivity is proportional to temperature, perturbations grow in proportion to temperature and hence exhibit no relative growth. For a conductor with initial thickness perturbations, temperature perturbations grow in proportion to resistivity and current action integral, i.e., somewhat faster than perturbations in the problem of constant thickness conductors. Comparison of our results with simulations of the growth of stratification during electrical heating of foils in warm dense matter generation systems demonstrates their close agreement.
Intermolecular dissociation energies of dispersively bound complexes of aromatics with noble gases and nitrogen
Authors: Knochenmuss Richard , Sinha Rajeev K. , Leutwyler Samuel
Published: April 2018

We measured accurate intermolecular dissociation energies D0 of the supersonic jet-cooled complexes of 1-naphthol (1NpOH) with the noble gases Ne, Ar, Kr, and Xe and with N2, using the stimulated-emission pumping resonant two-photon ionization method. The ground-state values D0(S0) for the 1NpOH⋅S complexes with S= Ar, Kr, Xe, and N2 were bracketed to be within ±3.5%; they are 5.67 ± 0.05 kJ/mol for S = Ar, 7.34 ± 0.07 kJ/mol for S = Kr, 10.8 ± 0.28 kJ/mol for S = Xe, 6.67 ± 0.08 kJ/mol for isomer 1 of the 1NpOH⋅N2 complex, and 6.62 ± 0.22 kJ/mol for the corresponding isomer 2. For S = Ne, the upper limit is D0 < 3.36 kJ/mol. The dissociation energies increase by 1%-5% upon S0 → S1 excitation of the complexes. Three dispersion-corrected density functional theory (DFT-D) methods (B97-D3, B3LYP-D3, and ωB97X-D) predict that the most stable form of these complexes involves dispersive binding to the naphthalene “face.” A more weakly bound edge isomer is predicted in which the S moiety is H-bonded to the OH group of 1NpOH; however, no edge isomers were observed experimentally. The B97-D3 calculated dissociation energies D0(S0) of the face complexes with Ar, Kr, and N2 agree with the experimental values within <5%, but the D0(S0) for Xe is 12% too low. The B3LYP-D3 and ωB97X-D calculated D0(S0) values exhibit larger deviations to both larger and smaller dissociation energies. For comparison to 1-naphthol, we calculated the D0(S0) of the carbazole complexes with S = Ne, Ar, Kr, Xe, and N2 using the same DFT-D methods. The respective experimental values have been previously determined to be within <2%. Again, the B97-D3 results are in the best overall agreement with experiment.
High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors
Authors: Liu Zhen , Ren Weijun , Peng Ping , Guo Shaobo , Lu Teng , Liu Yun , Dong Xianlin , Wang Genshui
Published: April 2018

Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ∼ 3.7 × 10−8 C cm−2 K−1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10−10 m/V, 2.89 × 10−2 m2/C, and 1.15 × 10−5 Pa−1/2 at 1 kHz and 1.32 × 10−10 m/V, 2.70 × 10−2 m2/C, and 1.09 × 10−5 Pa−1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ∼400 × 10−8 C cm−2 K−1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.
Auger-generated hot carrier current in photo-excited forward biased single quantum well blue light emitting diodes
Authors: Espenlaub Andrew C. , Alhassan Abdullah I. , Nakamura Shuji , Weisbuch Claude , Speck James S.
Published: April 2018

We report on measurements of the photo-modulated current-voltage and electroluminescence characteristics of forward biased single quantum well, blue InGaN/GaN light emitting diodes with and without electron blocking layers. Low intensity resonant optical excitation of the quantum well was observed to induce an additional forward current at constant forward diode bias, in contrast to the usual sense of the photocurrent in photodiodes and solar cells, as well as an increased electroluminescence intensity. The presence of an electron blocking layer only slightly decreased the magnitude of the photo-induced current at constant forward bias. Photo-modulation at constant forward diode current resulted in a reduced diode bias under optical excitation. We argue that this decrease in diode bias at constant current and the increase in forward diode current at constant applied bias can only be due to additional hot carriers being ejected from the quantum well as a result of an increased Auger recombination rate within the quantum well.
Alkyl hydrogen atom abstraction reactions of the CN radical with ethanol
Authors: Athokpam Bijyalaxmi , Ramesh Sai G.
Published: April 2018

We present a study of the abstraction of alkyl hydrogen atoms from the β and α positions of ethanol by the CN radical in solution using the Empirical Valence Bond (EVB) method. We have built separate 2 × 2 EVB models for the Hβ and Hα reactions, where the atom transfer is parameterized using ab initio calculations. The intra- and intermolecular potentials of the reactant and product molecules were modelled with the General AMBER Force Field, with some modifications. We have carried out the dynamics in water and chloroform, which are solvents of contrasting polarity. We have computed the potential of mean force for both abstractions in each of the solvents. They are found to have a small and early barrier along the reaction coordinate with a large energy release. Analyzing the solvent structure around the reaction system, we have found two solvents to have little effect on either reaction. Simulating the dynamics from the transition state, we also study the fate of the energies in the HCN vibrational modes. The HCN molecule is born vibrationally hot in the CH stretch in both reactions and additionally in the HCN bends for the Hα abstraction reaction. In the early stage of the dynamics, we find that the CN stretch mode gains energy at the expense of the energy in CH stretch mode.
The critical 1-arm exponent for the ferromagnetic Ising model on the Bethe lattice
Authors: Heydenreich Markus , Kolesnikov Leonid
Published: April 2018

We consider the ferromagnetic nearest-neighbor Ising model on regular trees (Bethe lattice), which is well-known to undergo a phase transition in the absence of an external magnetic field. The behavior of the model at critical temperature can be described in terms of various critical exponents; one of them is the critical 1-arm exponent ρ which characterizes the rate of decay of the (root) magnetization as a function of the distance to the boundary. The crucial quantity we analyze in this work is the thermal expectation of the root spin on a finite subtree, where the expected value is taken with respect to a probability measure related to the corresponding finite-volume Hamiltonian with a fixed boundary condition. The spontaneous magnetization, which is the limit of this thermal expectation in the distance between the root and the boundary (i.e., in the height of the subtree), is known to vanish at criticality. We are interested in a quantitative analysis of the rate of this convergence in terms of the critical 1-arm exponent ρ. Therefore, we rigorously prove that ⟨σ0⟩n+, the thermal expectation of the root spin at the critical temperature and in the presence of the positive boundary condition, decays as ⟨σ0⟩n+≈n−12 (in a rather sharp sense), where n is the height of the tree. This establishes the 1-arm critical exponent for the Ising model on regular trees (ρ=12).
Lipid-protein interaction induced domains: Kinetics and conformational changes in multicomponent vesicles
Authors: Sreeja K. K. , Sunil Kumar P. B.
Published: April 2018

The spatio-temporal organization of proteins and the associated morphological changes in membranes are of importance in cell signaling. Several mechanisms that promote the aggregation of proteins at low cell surface concentrations have been investigated in the past. We show, using Monte Carlo simulations, that the affinity of proteins for specific lipids can hasten their aggregation kinetics. The lipid membrane is modeled as a dynamically triangulated surface with the proteins defined as in-plane fields at the vertices. We show that, even at low protein concentrations, strong lipid-protein interactions can result in large protein clusters indicating a route to lipid mediated signal amplification. At high protein concentrations, the domains form buds similar to that seen in lipid-lipid interaction induced phase separation. Protein interaction induced domain budding is suppressed when proteins act as anisotropic inclusions and exhibit nematic orientational order. The kinetics of protein clustering and resulting conformational changes are shown to be significantly different for the isotropic and anisotropic curvature inducing proteins.
Effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of t-C8B2N2
Authors: Zhu Haiyan , Shi Liwei , Li Shuaiqi , Duan Yifeng , Zhang Shaobo , Xia Wangsuo
Published: April 2018

The effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of a superhard material t-C8B2N2 have been studied using first-principles calculations. The structure is proven to be mechanically and dynamically stable under the applied external forces. All the elastic constants (except C66) and elastic modulus increase (decrease) with increasing pressure and compressive (tensile) biaxial strain εxx. A microscopic model is used to calculate the Vicker's hardness of every single bond as well as the crystal. The hardness of t-C8B2N2 (64.7 GPa) exceeds that of c-BN (62 GPa) and increases obviously by employing pressure and compressive εxx. Furthermore, the Debye temperature and anisotropy of sound velocities for t-C8B2N2 have been discussed. t-C8B2N2 undergoes an indirect to direct bandgap transition when εxx > 2%; however, the indirect bandgap character of the material remains under pressure.
Low temperature thermoelectric properties of p-type doped single-crystalline SnSe
Authors: Wang Si , Hui Si , Peng Kunling , Bailey Trevor P. , Liu Wei , Yan Yonggao , Zhou Xiaoyuan , Tang Xinfeng , Uher Ctirad
Published: April 2018

SnSe single crystals have been widely studied lately as a result of their record high ZT and controversial low thermal conductivity. Much research has focused on the high-temperature properties of single crystals and polycrystalline SnSe, but few studies were carried out on the low-temperature properties of doped single-crystalline SnSe. To study the mechanism of the charge carrier and phonon scattering, and to eliminate the ambiguity of the high temperature thermal conductivity measurement, we performed low temperature transport characterization of Na-doped and Ag-doped single-crystalline SnSe by a longitudinal steady-state technique. The electronic transport property measurements suggest that Na is a more efficient p-type dopant in SnSe than Ag. In the thermal conductivity data, we observe pronounced dielectric peak around 10 K with magnitude dependent on the doping level. In the p-type doped samples, we found that our room temperature lattice thermal conductivities (>1.74 W m−1 K−1) are in general higher than those previously reported. Based on these findings, our study implies that the lattice thermal conductivity values of doped and pure single-crystalline SnSe were underestimated.
Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet
Authors: Vennemann T. , Jeong M. , Yoon D. , Magrez A. , Berger H. , Yang L. , Živković I. , Babkevich P. , Rønnow H. M.
Published: April 2018

We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO4 with S = 1/2 (Mo5+) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.
Electrically tunable dynamic nuclear spin polarization in GaAs quantum dots at zero magnetic field
Authors: Manca M. , Wang G. , Kuroda T. , Shree S. , Balocchi A. , Renucci P. , Marie X. , Durnev M. V. , Glazov M. M. , Sakoda K. , Mano T. , Amand T. , Urbaszek B.
Published: April 2018

In III–V semiconductor nano-structures, the electron and nuclear spin dynamics are strongly coupled. Both spin systems can be controlled optically. The nuclear spin dynamics are widely studied, but little is known about the initialization mechanisms. Here, we investigate optical pumping of carrier and nuclear spins in charge tunable GaAs dots grown on 111A substrates. We demonstrate dynamic nuclear polarization (DNP) at zero magnetic field in a single quantum dot for the positively charged exciton X+ state transition. We tune the DNP in both amplitude and sign by variation of an applied bias voltage Vg. Variation of ΔVg on the order of 100 mV changes the Overhauser splitting (nuclear spin polarization) from −30 μeV (−22%) to +10 μeV (+7%) although the X+ photoluminescence polarization does not change sign over this voltage range. This indicates that absorption in the structure and energy relaxation towards the X+ ground state might provide favourable scenarios for efficient electron-nuclear spin flip-flops, generating DNP during the first tens of ps of the X+ lifetime which is on the order of hundreds of ps. Voltage control of DNP is further confirmed in Hanle experiments.
Low index contrast heterostructure photonic crystal cavities with high quality factors and vertical radiation coupling
Authors: Ge Xiaochen , Minkov Momchil , Fan Shanhui , Li Xiuling , Zhou Weidong
Published: April 2018

We report here design and experimental demonstration of heterostructure photonic crystal cavities resonating near the Γ point with simultaneous strong lateral confinement and highly directional vertical radiation patterns. The lateral confinement is provided by a mode gap originating from a gradual modulation of the hole radii. High quality factor resonance is realized with a low index contrast between silicon nitride and quartz. The near surface-normal directional emission is preserved when the size of the core region is scaled down. The influence of the cavity size parameters on the resonant modes is also investigated theoretically and experimentally.
A green and facile method to fabricate superhydrophobic coatings
Authors: Huang Yanfen , Lv Zaosheng , Cao Zhe , Huang Chi
Published: April 2018

In this work, we reported a green and facile method to fabricate superhydrophobic coatings via blending TiO2 nanoparticles and fluorinated acrylate copolymers. The fluorinated acrylate copolymers were synthesised with the method of solution polymerisation using ethanol as solvent. The integration of TiO2 nanoparticles and the fluorinated acrylate copolymers satisfied two necessary conditions of multi-scale nano/microstructures and low surface energy for fabricating superhydrophobic coatings. It was found that the water contact angle and contact angle hysteresis of the as-prepared coatings were respectively 156.3° and 3.7°, and it indicated that the coatings had excellent superhydrophobicity and self-cleaning ability. In particular, these coatings showed good thermal stabilities. Owing to its flexibility, simplicity and non-toxicity, the method is not only a facile and inexpensive way to achieve the lotus effect but could also create coatings with high values in practical application.
Thrombopoietin protects hematopoietic stem cells from retrotransposon-mediated damage by promoting an antiviral response
Authors: Barbieri Daniela , Elvira-Matelot Emilie , Pelinski Yanis , Genève Laetitia , de Laval Bérengère , Yogarajah Gayathri , Pecquet Christian , Constantinescu Stefan N. , Porteu Françoise
Published: April 2018

Maintenance of genomic integrity is crucial for the preservation of hematopoietic stem cell (HSC) potential. Retrotransposons, spreading in the genome through an RNA intermediate, have been associated with loss of self-renewal, aging, and DNA damage. However, their role in HSCs has not been addressed. Here, we show that mouse HSCs express various retroelements (REs), including long interspersed element-1 (L1) recent family members that further increase upon irradiation. Using mice expressing an engineered human L1 retrotransposition reporter cassette and reverse transcription inhibitors, we demonstrate that L1 retransposition occurs in vivo and is involved in irradiation-induced persistent γH2AX foci and HSC loss of function. Thus, RE represents an important intrinsic HSC threat. Furthermore, we show that RE activity is restrained by thrombopoietin, a critical HSC maintenance factor, through its ability to promote a potent interferon-like, antiviral gene response in HSCs. This uncovers a novel mechanism allowing HSCs to minimize irradiation-induced injury and reinforces the links between DNA damage, REs, and antiviral immunity.
Anti–Ebola Virus Antibody Levels in Convalescent Plasma and Viral Load After Plasma Infusion in Patients With Ebola Virus Disease
Authors: Brown Jerry F , Dye John M , Tozay Sam , Jeh-Mulbah Gertrude , Wohl David A , Fischer William A , Cunningham Coleen K , Rowe Kathleen , Zacharias Peter , van Hasselt James , Norwood David A , Thielman Nathan M , Zak Samantha E , Hoover David L
Published: April 2018

Enzyme-linked immunosorbent and microneutralization assays of 180 Ebola convalescent plasma specimens were highly concordant and predictive for detection of antibody by 50% plaque reduction neutralization test. Viral load decreased following infusion of antibody-containing plasma in 2 Ebola virus disease patients.
Machine learning approach for early detection of autism by combining questionnaire and home video screening
Authors: Abbas Halim , Garberson Ford , Glover Eric , Wall Dennis P
Published: April 2018

Background

Existing screening tools for early detection of autism are expensive, cumbersome, time- intensive, and sometimes fall short in predictive value. In this work, we sought to apply Machine Learning (ML) to gold standard clinical data obtained across thousands of children at-risk for autism spectrum disorder to create a low-cost, quick, and easy to apply autism screening tool.

Methods

Two algorithms are trained to identify autism, one based on short, structured parent-reported questionnaires and the other on tagging key behaviors from short, semi-structured home videos of children. A combination algorithm is then used to combine the results into a single assessment of higher accuracy. To overcome the scarcity, sparsity, and imbalance of training data, we apply novel feature selection, feature engineering, and feature encoding techniques. We allow for inconclusive determination where appropriate in order to boost screening accuracy when conclusive. The performance is then validated in a controlled clinical study.

Results

A multi-center clinical study of n = 162 children is performed to ascertain the performance of these algorithms and their combination. We demonstrate a significant accuracy improvement over standard screening tools in measurements of AUC, sensitivity, and specificity.

Conclusion

These findings suggest that a mobile, machine learning process is a reliable method for detection of autism outside of clinical settings. A variety of confounding factors in the clinical analysis are discussed along with the solutions engineered into the algorithms. Final results are statistically limited and will benefit from future clinical studies to extend the sample size.
Using statistical anomaly detection models to find clinical decision support malfunctions
Authors: Ray Soumi , McEvoy Dustin S , Aaron Skye , Hickman Thu-Trang , Wright Adam
Published: April 2018

Objective

Malfunctions in Clinical Decision Support (CDS) systems occur due to a multitude of reasons, and often go unnoticed, leading to potentially poor outcomes. Our goal was to identify malfunctions within CDS systems.

Methods

We evaluated 6 anomaly detection models: (1) Poisson Changepoint Model, (2) Autoregressive Integrated Moving Average (ARIMA) Model, (3) Hierarchical Divisive Changepoint (HDC) Model, (4) Bayesian Changepoint Model, (5) Seasonal Hybrid Extreme Studentized Deviate (SHESD) Model, and (6) E-Divisive with Median (EDM) Model and characterized their ability to find known anomalies. We analyzed 4 CDS alerts with known malfunctions from the Longitudinal Medical Record (LMR) and Epic® (Epic Systems Corporation, Madison, WI, USA) at Brigham and Women’s Hospital, Boston, MA. The 4 rules recommend lead testing in children, aspirin therapy in patients with coronary artery disease, pneumococcal vaccination in immunocompromised adults and thyroid testing in patients taking amiodarone.

Results

Poisson changepoint, ARIMA, HDC, Bayesian changepoint and the SHESD model were able to detect anomalies in an alert for lead screening in children and in an alert for pneumococcal conjugate vaccine in immunocompromised adults. EDM was able to detect anomalies in an alert for monitoring thyroid function in patients on amiodarone.

Conclusions

Malfunctions/anomalies occur frequently in CDS alert systems. It is important to be able to detect such anomalies promptly. Anomaly detection models are useful tools to aid such detections.
Addressing Dual Patient and Staff Safety Through A Team-Based Standardized Patient Simulation for Agitation Management in the Emergency Department
Authors: Wong Ambrose H. , Auerbach Marc A. , Ruppel Halley , Crispino Lauren J. , Rosenberg Alana , Iennaco Joanne D. , Vaca Federico E.
Published: April 2018

Introduction

Emergency departments (EDs) have seen harm rise for both patients and health workers from an increasing rate of agitation events. Team effectiveness during care of this population is particularly challenging because fear of physical harm leads to competing interests. Simulation is frequently employed to improve teamwork in medical resuscitations but has not yet been reported to address team-based behavioral emergency care. As part of a larger investigation of agitated patient care, we designed this secondary study to examine the impact of an interprofessional standardized patient simulation for ED agitation management.

Methods

We used a mixed-methods approach with emergency medicine resident and attending physicians, Physician Assistants (PAs) and Advanced Practice Registered Nurses (APRNs), ED nurses, technicians, and security officers at two hospital sites. After a simulated agitated patient encounter, we conducted uniprofessional and interprofessional focus groups. We undertook structured thematic analysis using a grounded theory approach. Quantitative data consisted of responses to the KidSIM Questionnaire addressing teamwork and simulation-based learning attitudes before and after each session.

Results

We reached data saturation with 57 participants. KidSIM scores revealed significant improvements in attitudes toward relevance of simulation, opportunities for interprofessional education, and situation awareness, as well as four of six questions for roles/responsibilities. Two broad themes emerged from the focus groups: (1) a team-based agitated patient simulation addressed dual safety of staff and patients simultaneously and (2) the experience fostered interprofessional discovery and cooperation in agitation management.

Conclusions

A team-based simulated agitated patient encounter highlighted the need to consider the dual safety of staff and patients while facilitating interprofessional dialog and learning. Our findings suggest that simulation may be effective to enhance teamwork in behavioral emergency care.
Single-particle tracking of Nucleotide Excision Repair proteins inside living bacteria
Authors: Piotrowska Alicja , Stracy Mathew , Zawadzki Pawel
Published: April 2018

Single-particle tracking (SPT) combined with Photoactivated Localization Microscopy (sptPALM) provides an opportunity to perform complex molecular biology experiments inside living cells. By tracking the motion of DNA repair proteins in vivo, information can be extracted not only about their diffusion, but also about the kinetics and spatial distribution of DNA binding1–3. From a methodological point of view, a Total Internal Reflection Microscope equipped with a sensitive detector (usually an EM-CCD camera4) is commonly used, allowing detection of individual fluorophores. The signal from individual emitters can be analysed and the position of a given fluorophore established with high accuracy (up to a single nm) by Gaussian fitting. To determine the mobility of each fluorophore, the positions of individual molecules are linked into trajectories over multiple frames using a tracking algorithm5.
Haplotype-aware genotyping from noisy long reads
Authors: Ebler Jana , Haukness Marina , Pesout Trevor , Marschall Tobias , Paten Benedict
Published: April 2018

Motivation

Current genotyping approaches for single nucleotide variations (SNVs) rely on short, relatively accurate reads from second generation sequencing devices. Presently, third generation sequencing platforms able to generate much longer reads are becoming more widespread. These platforms come with the significant drawback of higher sequencing error rates, which makes them ill-suited to current genotyping algorithms. However, the longer reads make more of the genome unambiguously mappable and typically provide linkage information between neighboring variants.

Results

In this paper we introduce a novel approach for haplotype-aware genotyping from noisy long reads. We do this by considering bipartitions of the sequencing reads, corresponding to the two haplotypes. We formalize the computational problem in terms of a Hidden Markov Model and compute posterior genotype probabilities using the forward-backward algorithm. Genotype predictions can then be made by picking the most likely genotype at each site. Our experiments indicate that longer reads allow significantly more of the genome to potentially be accurately genotyped. Further, we are able to use both Oxford Nanopore and Pacific Biosciences sequencing data to independently validate millions of variants previously identified by short-read technologies in the reference NA12878 sample, including hundreds of thousands of variants that were not previously included in the high-confidence reference set.
An accurate and robust algorithm for solvent-excluded surface computation
Authors: Wang Lincong
Published: April 2018

The solvent-excluded surface (SES1) of a molecule is an important geometrical property relevant to its solvation in aqueous solution and its interactions with other molecules. In this paper we present an accurate and robust analytic algorithm suitable for a large-scale SES analysis. The accuracy and robustness of our algorithm are made possible by an iterative strategy for the treatments of probe-probe intersections, probe-probe overlaps and limited numerical precision. The accuracy and robustness of our algorithm in turn make it possible to analyze on a large-scale the SESs for different types of proteins and various sets of ligand-protein interaction interfaces. The results illustrate the usefulness of SES and SES-defined physical and geometrical properties for the characterization of protein-solvent interaction and ligand-protein interaction where ligand could be either small molecule compound, or membrane lipid, or DNA or protein.
Coarse-Grained Model of the SNARE Complex Shows that Quick Zippering Requires Partial Assembly
Authors: Fortoul N. , Bykhovskaia M. , Jagota A.
Published: April 2018

Neuronal transmitters are released from nerve terminals via the fusion of synaptic vesicles with the presynaptic membrane. Vesicles become attached to the membrane via the SNARE complex. The SNARE complex comprises the vesicle associate protein Synaptobrevin (Syb), the membrane associated protein syntaxin (Syx), and the cytosolic protein SNAP25, which together form a four-helical bundle. The full assembly of Syb onto the core SNARE bundle promotes vesicle fusion. We investigated SNARE assembly using a coarse-grained model of the SNARE complex. The model retains chemical specificity, and was calibrated using single molecule experiments and all-atom molecular dynamics simulations. Steered force-control simulations of SNARE unzippering by peeling off Syb were used to set up initial disassembled states of the SNARE complex. From these states, the assembly process was simulated. We found that if Syb is in helical form, then the SNARE complex assembles rapidly, on a sub-microsecond time-scale. We found that assembly times grow exponentially with separation distance between Syb and Syx C-termni. The formation of helical turns is likely to substantially decelerate the assembly, consistent with single molecule force experiments that show SNARE assembly duration on the time-scale of hundreds of ms. Since synaptic vesicle fusion occurs at a sub-millisecond time-scale, our results indicate that for biologically relevant rapid assembly the SNARE complex needs to be partially zippered and its constituent helices brought into proximity, possibly by means of molecular chaperones.
User conceptualizations of derivative relationships in the bibliographic universe
Authors: Tallerås Kim , Dahl Jørn Helge B. , Pharo Nils
Published: April 2018

Purpose

Considerable effort is devoted to developing new models for organizing bibliographic metadata. However, such models have been repeatedly criticized for their lack of proper user testing. The purpose of this paper is to present a study on how non-experts in bibliographic systems map the bibliographic universe and, in particular, how they conceptualize relationships between independent but strongly related entities.

Design/methodology/approach

The study is based on an open concept-mapping task performed to externalize the conceptualizations of 98 novice students. The conceptualizations of the resulting concept maps are identified and analyzed statistically.

Findings

The study shows that the participants’ conceptualizations have great variety, differing in detail and granularity. These conceptualizations can be categorized into two main groups according to derivative relationships: those that apply a single-entity model directly relating document entities and those (the majority) that apply a multi-entity model relating documents through a high-level collocating node. These high-level nodes seem to be most adequately interpreted either as superwork devices collocating documents belonging to the same bibliographic family or as devices collocating documents belonging to a shared fictional world.

Originality/value

The findings can guide the work to develop bibliographic standards. Based on the diversity of the conceptualizations, the findings also emphasize the need for more user testing of both conceptual models and the bibliographic end-user systems implementing those models.
Lifeworld as “unit of analysis”
Authors: Gorichanaz Tim , Latham Kiersten F. , Wood Elizabeth
Published: April 2018

Purpose

The authors discuss the lifeworld as a research concept for the field of information behaviour, which serves to problematise the concept of unit of analysis. In so doing, the authors demonstrate how the lifeworld can be adopted as a unit of analysis in information behaviour research, that is, how research can be based in the lifeworld rather than merely looking at the lifeworld. The paper aims to discuss these issues.

Design/methodology/approach

The authors first situate our discussion in the current of information behaviour scholarship. The authors then introduce the concepts of lifeworld and unit of analysis and consider how they intersect. Next, to show the importance of the lifeworld, the authors present two recent studies in which the lifeworld emerged. Finally, the authors discuss how lifeworld-based research can be conducted more conscientiously.

Findings

Though many research approaches deal with lived experience in one way or another, they tend not to fully grasp these experiences. As opposed to units of analysis such as individual, social group, person-in-situation, etc., using lifeworld as a unit of analysis allows phenomena to be researched holistically and without reductionism.

Research limitations/implications

The authors limit the discussion to the concept of the lifeworld as developed by Husserl, the concept’s originator. The lifeworld has been discussed and extended by other authors since, but this work is not considered here. The viewpoint is offered as a supplementary perspective, meant to be enriching to our field of study, rather than divisive.

Originality/value

This is the first time the concept of the lifeworld has been fully explicated in information science. As the authors discuss, two recent information behaviour studies that “discovered” the lifeworld through their analysis. Future studies that attend to the lifeworld from the start have the capacity to build on this work and extend the horizons of information science.
Delays in new product introduction
Authors: Adaku Ebenezer , Amoatey Charles Teye , Nornyibey Israel , Famiyeh Samuel , Asante-Darko Disraeli
Published: April 2018

Purpose

Speed to the market is becoming a key competitive priority in developing countries’ environments even though lack of technology, poor skilled labour and under-developed infrastructure remain daunting challenges. The purpose of this paper is to examine the causes and relative importance of delay factors in the introduction of food products to the market in the era of time-based competition.

Design/methodology/approach

The study employed a case study approach in understanding the phenomenon in its natural settings and making sense of it through process and participants observations. Again, a two-stage approach (first, interviews and second, questionnaire) was used in collecting data from the respondents who work in a project team for a large food processing firm. The data was analysed using the relative importance index technique.

Findings

The results show that the most important causes of delays in new products introduction, especially in the food processing industry, are: high number of projects running concurrently; lack of project management process; lack of consistent project management structure; high workload on project team and delays caused by external laboratory.

Originality/value

This study sought to identify detailed delay factors in the introduction of new products with respect to the food processing industry and more importantly established the relative importance of these delay factors as a decision support system for managers in the food processing industry.
A planktonic diatom displays genetic structure over small spatial scales
Authors: Sefbom Josefin , Kremp Anke , Rengefors Karin , Jonsson Per R. , Sjöqvist Conny , Godhe Anna
Published: April 2018

Marine planktonic microalgae have potentially global dispersal, yet reduced gene flow has been confirmed repeatedly for several species. Over larger distances (>200 km) geographic isolation and restricted oceanographic connectivity have been recognized as instrumental in driving population divergence. Here we investigated whether similar patterns, that is, structured populations governed by geographic isolation and/or oceanographic connectivity, can be observed at smaller (6–152 km) geographic scales. To test this we established 425 clonal cultures of the planktonic diatom Skeletonema marinoi collected from 11 locations in the Archipelago Sea (northern Baltic Sea). The region is characterized by a complex topography, entailing several mixing regions of which four were included in the sampling area. Using eight microsatellite markers and conventional F‐statistics, significant genetic differentiation was observed between several sites. Moreover, Bayesian cluster analysis revealed the co‐occurrence of two genetic groups spread throughout the area. However, geographic isolation and oceanographic connectivity could not explain the genetic patterns observed. Our data reveal hierarchical genetic structuring whereby despite high dispersal potential, significantly diverged populations have developed over small spatial scales. Our results suggest that biological characteristics and historical events may be more important in generating barriers to gene flow than physical barriers at small spatial scales.
Evidence for selective bacterial community structuring on microplastics
Authors: Ogonowski Martin , Motiei Asa , Ininbergs Karolina , Hell Eva , Gerdes Zandra , Udekwu Klas I. , Bacsik Zoltan , Gorokhova Elena
Published: April 2018

In aquatic ecosystems, microplastics are a relatively new anthropogenic substrate that can readily be colonized by biofilm‐forming organisms. To examine the effects of substrate type on microbial community assembly, we exposed ambient Baltic bacterioplankton to plastic substrates commonly found in marine environments (polyethylene, polypropylene and polystyrene) as well as native (cellulose) and inert (glass beads) particles for 2 weeks under controlled conditions. The source microbial communities and those of the biofilms were analyzed by Illumina sequencing of the 16S rRNA gene libraries. All biofilm communities displayed lower diversity and evenness compared with the source community, suggesting substrate‐driven selection. Moreover, the plastics‐associated communities were distinctly different from those on the non‐plastic substrates. Whereas plastics hosted greater than twofold higher abundance of Burkholderiales, the non‐plastic substrates had a significantly higher proportion of Actinobacteria and Cytophagia. Variation in the community structure, but not the cell abundance, across the treatments was strongly linked to the substrate hydrophobicity. Thus, microplastics host distinct bacterial communities, at least during early successional stages.