bluuebunny/crossref_metadata_2025 huggingface dataset:
Anomalous tunneling characteristic of Weyl semimetals with tilted energy dispersion
Authors: Yesilyurt Can , Siu Zhuo Bin , Tan Seng Ghee , Liang Gengchiau , Yang Shengyuan A. , Jalil Mansoor B. A.
Published: August 2017

Weyl semimetals are recently discovered states of quantum matter, which generally possess tilted energy dispersion. Here, we investigate the electron tunneling through a Weyl semimetal p-n-p junction. The angular dependence of electron tunneling exhibits an anomalous profile such that perfect transmission angles are shifted along the direction of the tilt. Coupling of the tilted dispersion and electrical potential within the barrier region gives rise to a transverse momentum shift, which is analogous to the transverse Lorentz displacement induced by magnetic barriers.
An all-perovskite p-n junction based on transparent conducting p-La1−xSrxCrO3 epitaxial layers
Authors: Du Yingge , Li Chen , Zhang Kelvin H. L. , McBriarty Martin E. , Spurgeon Steven R. , Mehta Hardeep S. , Wu Di , Chambers Scott A.
Published: August 2017

Transparent, conducting p-La1−xSrxCrO3 epitaxial layers were deposited on Nb-doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy to form structurally coherent p-n junctions. X-ray photoelectron spectroscopy reveals a type II or “staggered” band alignment, with valence and conduction band offsets of 2.0 eV and 0.9 eV, respectively. Diodes fabricated from these heterojunctions exhibit rectifying behavior, and the I-V characteristics are different from those for traditional semiconductor p-n junctions. A rather large ideality factor is ascribed to the complex nature of the interface.
Hole weak anti-localization in a strained-Ge surface quantum well
Authors: Mizokuchi R. , Torresani P. , Maurand R. , Zeng Z. , Niquet Y.-M. , Myronov M. , De Franceschi S.
Published: August 2017

We report a magneto-transport study of a two-dimensional hole gas confined to a strained Ge quantum well grown on a relaxed Si0.2Ge0.8 virtual substrate. The conductivity of the hole gas measured as a function of a perpendicular magnetic field exhibits a zero-field peak resulting from weak anti-localization. The peak develops and becomes stronger upon increasing the hole density by means of a top gate electrode. This behavior is consistent with a Rashba-type spin-orbit coupling whose strength is proportional to the perpendicular electric field and hence to the carrier density. In the low-density, the single-subband regime, by fitting the weak anti-localization peak to an analytic model, we extract the characteristic transport time scales and a spin splitting energy ΔSO∼ 1 meV. Tight-binding calculations show that ΔSO is dominated by a cubic term in the in-plane wave vector. Finally, we observe a weak anti-localization peak also for magnetic fields parallel to the quantum well and associate this finding to an effect of intersubband scattering induced by interface defects.
Traveling waves for a model of individual clustering with logistic growth rate
Authors: Ibrahim H. , Nasreddine E.
Published: August 2017

We consider a traveling wave problem for a one-dimensional model of individual clustering or aggregation. This model, originally formulated by Grindrod [J. Math. Biol. 26(6), 651–660 (1988)], describes the mechanism of individual dispersion when individuals are able to utilize information about their local environment. Specifically, it assumes that each individual disperses randomly with probability δ and disperses deterministically so as to improve his reproductive rate with probability 1−δ. In this paper, we prove the existence of a traveling wave solution when the probability of random dispersion exceeds a critical value δ* uniquely determined by the biased individual velocity.
Lanthanum-mediated dehydrogenation of 1- and 2-butynes: Spectroscopy and formation of La(C4H4) isomers
Authors: Cao Wenjin , Hewage Dilrukshi , Yang Dong-Sheng
Published: August 2017

La atom reactions with 1-butyne and 2-butyne are carried out in a laser-vaporization molecular beam source. Both reactions yield the same La-hydrocarbon products from the dehydrogenation and carbon-carbon bond cleavage and coupling of the butynes. The dehydrogenated species La(C4H4) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of La(C4H4) produced from the two reactions exhibit two identical transitions, each consisting of a strong origin band and several vibrational intervals. The two transitions are assigned to the ionization of two isomers: La(η4–CH2CCCH2) (Iso A) and La(η4–CH2CHCCH) (Iso B). The ground electronic states are 2A1 (C2v) for Iso A and 2A (C1) for Iso B. The ionization of the doublet state of each isomer removes a La 6s-based electron and results in a 1A1 ion of Iso A and a 1A ion of Iso B. The formation of Iso A from 2-butyne and Iso B from 1-butyne involves the addition of La to the C≡C triple bond, the activation of two C(sp3)–H bonds, and concerted elimination of a H2 molecule. The formation of Iso A from 1-butyne and Iso B from 2-butyne involves the isomerization of the two butynes to 1,2-butadiene in addition to the concerted H2 elimination.
Asymmetric breathing motions of nucleosomal DNA and the role of histone tails
Authors: Chakraborty Kaushik , Loverde Sharon M.
Published: August 2017

The most important packing unit of DNA in the eukaryotic cell is the nucleosome. It undergoes large-scale structural re-arrangements during different cell cycles. For example, the disassembly of the nucleosome is one of the key steps for DNA replication, whereas reassembly occurs after replication. Thus, conformational dynamics of the nucleosome is crucial for different DNA metabolic processes. We perform three different sets of atomistic molecular dynamics simulations of the nucleosome core particle at varying degrees of salt conditions for a total of 0.7 μs simulation time. We find that the conformational dynamics of the nucleosomal DNA tails are oppositely correlated from each other during the initial breathing motions. Furthermore, the strength of the interaction of the nucleosomal DNA tail with the neighboring H2A histone tail modulates the conformational state of the nucleosomal DNA tail. With increasing salt concentration, the degree of asymmetry in the conformation of the nucleosomal DNA tails decreases as both tails tend to unwrap. This direct correlation between the asymmetric breathing motions of the DNA tails and the H2A histone tails, and its decrease at higher salt concentrations, may play a significant role in the molecular pathway of unwrapping.
Optical superimposed vortex beams generated by integrated holographic plates with blazed grating
Authors: Zhang Xue-Dong , Su Ya-Hui , Ni Jin-Cheng , Wang Zhong-Yu , Wang Yu-Long , Wang Chao-Wei , Ren Fei-Fei , Zhang Zhen , Fan Hua , Zhang Wei-Jie , Li Guo-Qiang , Hu Yan-Lei , Li Jia-Wen , Wu Dong , Chu Jia-Ru
Published: August 2017

In this paper, we demonstrate that the superposition of two vortex beams with controlled topological charges can be realized by integrating two holographic plates with blazed grating. First, the holographic plate with blazed grating was designed and fabricated by laser direct writing for generating well-separated vortex beam. Then, the relationship between the periods of blazed grating and the discrete angles of vortex beams was systemically investigated. Finally, through setting the discrete angle and different revolving direction of the holographic plates, the composite fork-shaped field was realized by the superposition of two vortex beams in a particular position. The topological charges of composite fork-shaped field (l = 1, 0, 3, and 4) depend on the topological charges of compositional vortex beams, which are well agreed with the theoretical simulation. The method opens up a wide range of opportunities and possibilities for applying in optical communication, optical manipulations, and photonic integrated circuits.
Fluid modeling of plasma dynamics in pulsed RF capacitive glow discharges in low pressure argon
Authors: Liu Ruiqiang , Liu Yue , Jia Wenzhu , Zhou Yanwen
Published: August 2017

Based on the drift-diffusive approximation, one-dimensional fluid modeling is carried out for the pulsed RF capacitive glow discharges in low pressure argon. Investigated are the effects of various discharge parameters, such as the duty cycle ratio and frequency of the pulsed modulation, and the material properties of the electrode, on the plasma characteristics such as the electron recombination rate, during both the initial and the steady state phases of the discharge. The modeling results show that, after switching off the applied voltage during the pulsed modulation of the RF discharge, the electron density increases first and then decreases. This phenomenon is particularly pronounced before the discharge reaches steady state. Meanwhile, independent of whether the discharge has reached steady state or not, right after the applied voltage is switched on during each modulation period, the electron and ion densities and the metastable argon atom density, as well as their generation rate, experience a time delay (phase lag) with respect to the applied voltage. The results also show that, at the initial phase of the pulsed modulation, during the steady state discharge, the electron temperature in the center of the bulk plasma is almost not affected by the applied voltage, or by the material properties of the electrode such as the secondary electron emission rate. The electron density, however, does increase with these parameters, resulting in increased power density dissipation of the plasma. On the other hand, at fixed applied voltage, the central electron temperature of the bulk plasma is reduced by increasing several parameters, including the modulation duty ratio, the distance between two electrodes, and the modulation frequency, as well as the electron recombination rate due to different choices of the electrode material. This eventually leads to a reduction of the dissipated power density in the plasma. In particular, with the increase of the modulation duty ratio, the distance between electrodes, or the RF modulation frequency, the electron temperature decays slower after switching off the applied voltage within the modulation period. All the above studies are also accompanied by a systematic investigation of the temporal and spatial distributions of the electron energy conversion during the pulsed RF discharge.
Ion hammering eliminated as cause of elongation of embedded nanoparticles
Authors: Bello Mark
Published: August 2017

New research challenges proposed synergy model invoking ion hammering with transient melting.
Demonstrating collisionless fluid models of reconnection in the magnetosphere
Authors: Blaustein Rich
Published: August 2017

Researchers show how high-order moments of kinetic equations allow simulations of critical reconnection events in the magnetosphere.
Feeding wet distillers grains plus solubles contributes to sarcoplasmic reticulum membrane instability
Authors: Chao M. D. , Domenech-Perez K. I. , Senaratne-Lenagala L. S. , Calkins C. R.
Published: August 2017

Feeding wet distillers grains plus solubles (WDGS) increases polyunsaturated fatty acid (PUFA) levels in beef. It was hypothesised that WDGS in feedlot diets increases PUFA concentration in the sarcoplasmic reticulum (SR) membrane, thereby altering membrane integrity, resulting in more rapid intracellular calcium leakage and improved tenderness. The objective of this study was to evaluate this hypothesis. Ninety-six crossbred steers were fed either a corn-based diet with 0% WDGS or 50% WDGS. Fifteen strip loins per treatment were collected, fabricated into steaks, aged and placed under retail display conditions. Steaks were used to measure tenderness, proteolysis, free calcium concentrations, lipid oxidation, sarcomere length and SR membrane fatty acid, phospholipid lipid, neutral lipid and total lipid profiles. Compared with steaks from steers fed 0% WDGS, steaks from steers fed 50% WDGS were more tender (P < 0.05) and had greater (P < 0.05) free calcium concentrations early post-mortem. Feeding 50% WDGS also tended to increase (P < 0.10) total PUFA concentrations, decrease (P < 0.10) total phospholipid concentration and increase (P < 0.10) total neutral lipid concentration for SR membrane. Steaks from steers fed 0% WDGS had greater (P < 0.05) lipid oxidation (TBARS values) than steaks from steers fed 50% WDGS after extended aging. Although differences in tenderness between the two treatments were detected, there were no corresponding differences (P > 0.10) in sarcomere length or proteolysis. This study showed that feeding WDGS may increase tenderness, possibly by increasing free calcium in muscle early post-mortem. However, the true mechanism that contributes to these differences is still unclear.
Different water relations between flowering and leaf periods: a case study in flower-before-leaf-emergence Magnolia species
Authors: Liu Hui , Xu Qiu-Yuan , Lundgren Marjorie R. , Ye Qing
Published: August 2017

The differing water relations between flowers and leaves on a plant reflect the lack of co-ordination between reproductive and vegetative organs during the evolution of angiosperm species. The amount of water that flowers consume has been reported to vary across species, and compared with studies of leaves, accurate measurements of flower water relations at the branch level are lacking. Further, the mechanisms by which flowers regulate their hydraulic function and structure to maintain water balance remain unclear. To explore the ecophysiological basis underpinning the differences between flowers and leaves, we measured hydraulic and morphological traits and monitored sap flow in flowers and leaves from the same branches of two Magnoliaceae species that flower before leaf emergence (Magnolia denudata Desr. and Magnolia soulangeana Soul.-Bod.). Sap flux density (JS) of flowers was 22% and 55% of that predicted for leaves in M. denudata and M. soulangeana respectively. JS of flowers commenced before predawn and ceased early in the afternoon, reflecting their night-time flowering pattern and a dramatic decrease of JS with increasing vapour pressure deficit (D) under the high light of midday. Relative to leaves, tepals were thicker and more hydrated, and had bigger but scarcer stomata, leading to lower stomatal conductance (gs) and transpiration rate (E), less negative water potential (Ψtepal) and lower hydraulic conductance. This study revealed different hydraulic patterns in the flowers and leaves of the two Magnolia species. Although flowers consumed less than half the water that leaves did, they used different strategies to maintain sufficiently high Ψ to sustain hydraulic safety. Magnolia flowers retained more hydrated tepals by exhibiting less water loss than leaves via lower hydraulic conductance. In contrast, Magnolia leaves maintained high transpiration rates through efficient stomatal responses to environmental changes compared with flowers.
Redox variations in Mauna Kea lavas, the oxygen fugacity of the Hawaiian plume, and the role of volcanic gases in Earth’s oxygenation
Authors: Brounce Maryjo , Stolper Edward , Eiler John
Published: August 2017

Significance

Volcanic degassing at Mauna Kea volcanoes decreases the oxidation state of both Fe and S in the magmas, consistent with recent results from Kilauea volcano. The least degassed magmas from Mauna Kea are more oxidized than midocean ridge basalt magmas, possibly due to plate tectonic cycling of material from the oxidized surface to the deep mantle, which is then returned to the surface as a component of buoyant plumes. If the degassing trend observed for Mauna Kea applies to basaltic systems more broadly, decompression does not lead to significant changes in the reducing capacity of the exsolved gases and thus cannot explain the rise of oxygen at the Archean/Proterozoic boundary.
Dual-reporter SERS-based biomolecular assay with reduced false-positive signals
Authors: Chuong Tracy T , Pallaoro Alessia , Chaves Chelsea A. , Li Zhe , Lee Joun , Eisenstein Michael , Stucky Galen D. , Moskovits Martin , Soh H. Tom
Published: August 2017

Significance

Whereas new biomolecular assays are continually being developed to achieve higher detection sensitivities, specificity is often the primary factor limiting an assay’s detection threshold—especially in single-label/signal amplification-based assays. This paper describes a sensitive and quantitative protein detection method that makes use of a dual-reporter approach with enhanced ability to distinguish true positives from false positives. This strategy gives rise to excellent sensitivity and accuracy of measurement, even for low target protein concentrations in complex biological samples.
Flower-specific jasmonate signaling regulates constitutive floral defenses in wild tobacco
Authors: Li Ran , Wang Ming , Wang Yang , Schuman Meredith C. , Weinhold Arne , Schäfer Martin , Jiménez-Alemán Guillermo H. , Barthel Andrea , Baldwin Ian T.
Published: August 2017

Significance

Plants are at the base of most food chains and hence are frequently attacked by herbivores. Leaves are the dominant aboveground tissues of most plants and their defense responses against folivores are well studied and known to be regulated by jasmonate (JA) phytohormone signaling. As the most fitness-valuable and frequently the most nutritious tissues, flowers are also commonly attacked by florivores. However floral defense, compared with leaf defense, is rarely studied, and the signaling systems that regulate these defenses are unknown. Here we show that flowers of the wild tobacco,
Nicotiana attenuata
, constitutively accumulate large amounts of defensive compounds, trypsin proteinase inhibitors, (
E
)-α-bergamotene and defensins, and that a flower-specific sector of JA signaling regulates these constitutively expressed floral defenses.
Large numbers of explanatory variables, a semi-descriptive analysis
Authors: Cox D. R. , Battey H. S.
Published: August 2017

Significance

Data with a small number of study individuals and a large number of potential explanatory features arise particularly in genomics. Existing methods of analysis result in a single model, but other sparse choices of explanatory features may fit virtually equally well. Our primary aim is essentially a set of acceptable simple representations. The method allows the assessment of anomalies, such as nonlinearities and interactions.
Mapping of human brown adipose tissue in lean and obese young men
Authors: Leitner Brooks P. , Huang Shan , Brychta Robert J. , Duckworth Courtney J. , Baskin Alison S. , McGehee Suzanne , Tal Ilan , Dieckmann William , Gupta Garima , Kolodny Gerald M. , Pacak Karel , Herscovitch Peter , Cypess Aaron M. , Chen Kong Y.
Published: August 2017

Significance

Brown adipose tissue (BAT) is currently being explored as a target for the treatment of obesity and diabetes after repeated demonstrations on positron emission tomography-computed tomography (PET/CT) imaging of its ability to metabolize glucose following acute cold exposure. Measurement of whole-body BAT volume, activity, and distribution is difficult because brown adipocytes are structurally commingled among white adipose tissue, muscle, and blood vessels. Thus, BAT’s potential contribution to metabolism remains unclear. To address this, we have identified several refinements to improve current PET/CT analyses and demonstrated their impact in healthy lean vs. obese individuals. Using the refined technique, we defined whole-body BAT distribution and estimated its metabolic capacity and found that it is substantially higher than usually reported.
Early cytoplasmic uncoating is associated with infectivity of HIV-1
Authors: Mamede João I. , Cianci Gianguido C. , Anderson Meegan R. , Hope Thomas J.
Published: August 2017

Significance

After fusion, HIV delivers its capsid formed of CA proteins into the cytoplasm. The regulated disassembly of the capsid (uncoating) is critical to the timely exposure of the viral genome and infection. The timing of this process is controversial. Utilizing an intravirion GFP fluid phase marker with a live-cell imaging approach, where we use less than one virion per cell, we demonstrate that the uncoating of HIV-1 particles is an early cytoplasmic process taking place ∼30 minutes after fusion, and dependent on ongoing reverse transcription. Early uncoating is observed in culture cells, primary T cells, and macrophages with either HIV or pseudotyped envelope. Partial CA retention with the viral complex facilitates late CA functions, including nuclear import and integration site selection.
On the mechanism of long-range orientational order of fibroblasts
Authors: Li Xuefei , Balagam Rajesh , He Ting-Fang , Lee Peter P. , Igoshin Oleg A. , Levine Herbert
Published: August 2017

Significance

Long-range alignment patterns of fibroblasts have been observed both in vivo and in vitro. However, there has not been much understanding of the underlying mechanism. In this work, we show that these patterns cannot be simply explained by their steric interactions with one another during collisions. Instead, we propose that fibroblasts may collectively align through nonlocal interactions arising from their modification of an underlying ECM. The proposed mechanism explains the observed coalignment between fibroblasts and collagen fibers around tumors and can be tested in future experiments that can image the dynamics of this pattern formation in vivo or in vitro.
Organotypic models of type III interferon-mediated protection from Zika virus infections at the maternal–fetal interface
Authors: Corry Jacqueline , Arora Nitin , Good Charles A. , Sadovsky Yoel , Coyne Carolyn B.
Published: August 2017

Significance

Little is known about the specific mechanisms by which viruses associated with congenital disease, such as Zika virus (ZIKV), breach the placental barrier to access the fetal compartment. This is at least in part because of the lack of appropriate systems to model the unique properties of human placental syncytiotrophoblasts, which form a key cellular interface between the maternal and fetal compartments. Here, we describe the development of new organotypic models of human syncytiotrophoblasts that can be used to study the innate defense mechanisms used by these cells to restrict ZIKV infection at various stages of human gestation. These models can be used to study the mechanisms of ZIKV vertical transmission, the development of ZIKV diagnostics, and the testing of anti-ZIKV therapeutics.
BACE inhibition-dependent repair of Alzheimer’s pathophysiology
Authors: Keskin Aylin D. , Kekuš Maja , Adelsberger Helmuth , Neumann Ulf , Shimshek Derya R. , Song Beomjong , Zott Benedikt , Peng Tingying , Förstl Hans , Staufenbiel Matthias , Nelken Israel , Sakmann Bert , Konnerth Arthur , Busche Marc Aurel
Published: August 2017

Significance

The accumulation of amyloid-β (Aβ) proteins in the brain contributes to Alzheimer´s disease (AD). Reducing Aβ by inhibiting its production with a β-secretase (BACE) inhibitor represents a novel mechanism for treating AD; however, whether this therapeutic strategy is capable of repairing impaired brain circuits associated with AD is unknown. Here we demonstrate that BACE inhibition is beneficial to all levels of impairment in an AD mouse model: cellular, long-range circuitry, and memory. We provide evidence that the rescue is dependent on the reduction of soluble forms of Aβ surrounding amyloid plaques. These results have mechanistic and therapeutic implications for AD, including Aβ-related memory defects.
Identification of the Tau phosphorylation pattern that drives its aggregation
Authors: Despres Clément , Byrne Cillian , Qi Haoling , Cantrelle François-Xavier , Huvent Isabelle , Chambraud Béatrice , Baulieu Etienne-Emile , Jacquot Yves , Landrieu Isabelle , Lippens Guy , Smet-Nocca Caroline
Published: August 2017

Significance

In Alzheimer’s disease, the microtubule-associated protein Tau is invariably found in a hyperphosphorylated and aggregated form. Whether (hyper)phosphorylation can drive aggregation is less clear, and no precise phosphorylation pattern leading to aggregation has been described. Combining in vitro phosphorylation assays with purified kinases and a rat brain extract with the analytical power of NMR spectroscopy, we unravel here the phosphorylation pattern of Tau that drives its aggregation. The results point to the importance of this posttranslational modification in Tau's aggregation and suggest orienting therapeutic strategies toward phosphorylated Tau.
Mechanism of DNA alkylation-induced transcriptional stalling, lesion bypass, and mutagenesis
Authors: Xu Liang , Wang Wei , Wu Jiabin , Shin Ji Hyun , Wang Pengcheng , Unarta Ilona Christy , Chong Jenny , Wang Yinsheng , Wang Dong
Published: August 2017

Significance

DNA alkylation represents a major form of DNA damage that is of high clinical and human health relevance; however, the molecular mechanisms of transcriptional lesion recognition, stalling, and bypass remain unknown. Herein, we carried out a comprehensive investigation to compare the effects of three regioisomeric EtdT lesions on transcription. Intriguingly, we found that the location of alkyl group dictates transcriptional stalling profile and lesion bypass routes, and we identified a novel minor-groove–sensing motif, termed Pro-Gate, which plays an important role in detecting the minor-groove lesion. This work provides important mechanistic insights into DNA alkylation-induced transcriptional stalling and mutagenesis. Our study also provides knowledge about cancer etiology and for the future design of effective cancer chemotherapeutic agents.
Electrocatalytic hydrogen evolution reaction activity comparable to platinum exhibited by the Ni/Ni(OH)
2
/graphite electrode
Authors: Chhetri Manjeet , Sultan Salman , Rao C. N. R.
Published: August 2017

Significance

The successful utilization of solar energy to economically produce green fuel should involve facile and inexpensive means for electrolysis of water. To do so, it is necessary to replace the platinum catalyst with an in situ electrode fabrication process involving active catalyst with readily available materials. We have been successful in synthesizing an inexpensive Ni/Ni(OH)
2
/graphite electrode whose performance is as good as Pt. By a suitable choice of the relative proportion of Ni and Ni(OH)
2
, we obtain high current density at low overpotentials. The sequential galvanostatic and potentiostatic pulses used for the electrodeposition of Ni on the graphite rod provide control over the morphology and composition and the improved electrochemical performance.
Arabidopsis
SH3P2 is an ubiquitin-binding protein that functions together with ESCRT-I and the deubiquitylating enzyme AMSH3
Authors: Nagel Marie-Kristin , Kalinowska Kamila , Vogel Karin , Reynolds Gregory D. , Wu Zhixiang , Anzenberger Franziska , Ichikawa Mie , Tsutsumi Chie , Sato Masa H. , Kuster Bernhard , Bednarek Sebastian Y. , Isono Erika
Published: August 2017

Significance

The endosomal sorting of integral proteins is essential for controlling signaling pathways at the plasma membrane. Posttranslational modification by ubiquitin is key to proper degradation of plasma membrane proteins as the ubiquitylated transmembrane proteins are recognized by multiple ubiquitin adaptor proteins and trafficked to the vacuole for degradation. Although plants lack orthologs of the yeast and metazoan endosomal sorting complex required for transport-0 heterodimer that functions as an ubiquitin adaptor, plants appear to have evolved other strategies to recognize and concentrate ubiquitylated proteins that have been endocytosed. Here, we report the SH3P2 protein as a yet-unknown ubiquitin adaptor protein in
Arabidopsis
and its molecular function in regulating the endocytic transport and degradation.
Chaperonin GroEL accelerates protofibril formation and decorates fibrils of the Het-s prion protein
Authors: Wälti Marielle A. , Schmidt Thomas , Murray Dylan T. , Wang Huaibin , Hinshaw Jenny E. , Clore G. Marius
Published: August 2017

Significance

The interaction of amyloids with chaperones, a large group of proteins responsible for proteostasis, is thought to play a significant role in the etiology of amyloidosis. Here, we study the interaction of the model chaperonin GroEL with a model amyloid protein, the prion domain of Het-s, by using NMR and EPR spectroscopies and electron and atomic force microscopies. We show that GroEL accelerates protofibril formation, eventually leading to the formation of fibrils densely decorated by GroEL. This type of chaperone–amyloid interaction may serve to reduce the toxicity of amyloidogenic oligomers and target the fully formed fibrils for rapid elimination by facilitating in vivo clearance.
Seabed Habitat Determines Fish and Macroinvertebrate Community Associations in a Subarctic Marine Coastal Nursery
Authors: Dalley Kate L. , Gregory Robert S. , Morris Corey J. , Cote David
Published: August 2017

Fish exhibit habitat‐specific distributions in heterogeneous landscapes. Many sampling techniques are limited to specific seabed types and have limited utility in comparisons of fish abundance among multiple habitats. We measured the relative abundance and the composition of fish communities in four naturally occurring coastal marine seabed types (sand–pebble, cobble, bedrock, and eelgrass) and one anthropogenic habitat type (wharf) in Newman Sound, Newfoundland, Canada, by using baited video cameras. Fish and macroinvertebrate communities were significantly different among habitat types. Winter Flounder Pseudopleuronectes americanus, Atlantic Cod Gadus morhua, and Shorthorn Sculpin Myoxocephalus scorpius were significantly more abundant over sand–pebble substrate compared with bedrock and wharf sites. Cunners Tautogolabrus adspersus and Greenland Cod Gadus macrocephalus ogac were most abundant at wharf sites. Atlantic rock crabs Cancer irroratus and American lobsters Homarus americanus avoided sand–pebble seabeds, and American lobsters were almost exclusive to bedrock sites. Cunners, Winter Flounder, and Atlantic Cod were more abundant in summer, whereas Greenland Cod and Atlantic rock crabs were more abundant during autumn months. In paired comparisons of eelgrass habitats, the community sampled by two methods was different. Relative abundance estimates from baited video cameras matched beach seine estimates for abundant predatory species (e.g., Cunner, Greenland Cod, and Atlantic rock crab), but other species, including age‐0 Greenland Cod, Shorthorn Sculpin, and White Hake Urophycis tenuis, were better represented in beach seine samples. We demonstrated substrate preferences by common coastal marine fish and crab species, which have proven difficult to enumerate via active sampling techniques in the past. Our findings will facilitate comparative studies for these species among habitat components. For species that are well sampled by using baited video cameras, this technique will advance our ability to plan for their management in the nearshore.
Effectiveness of Dry Cell Microscopic Simulation (DCMS) to Promote Conceptual Understanding about Battery
Authors: Wibowo Firmanul Catur , Suhandi Andi , Rusdiana Dadi , Samsudin Achmad , Darman Dina Rahmi , Faizin M. Noor , Wiyanto  , Supriyatman  , Permanasari Anna , Kaniawati Ida , Setiawan Wawan , Karyanto Yudi , Linuwih Suharto , Fatah Abdul , Subali Bambang , Hasani Aceng , Hidayat Sholeh
Published: August 2017

Electricity is a concept that is abstract and difficult to see by eye directly, one example electric shock, but cannot see the movement of electric current so that students have difficulty by students. A computer simulation designed to improve the understanding of the concept of the workings of the dry cell (battery). This study was conducted to 82 students (aged 18-20 years) in the experimental group by learning to use the Dry Cell Microscopic Simulation (DCMS). The result shows the improving of students’ conceptual understanding scores from post test were statistically significantly of the workings of batteries. The implication using computer simulations designed to overcome the difficulties of conceptual understanding, can effectively help students in facilitating conceptual change.
Multi-scale tracking reveals scale-dependent chromatin dynamics after DNA damage
Authors: Miné-Hattab Judith , Recamier Vincent , Izeddin Ignacio , Rothstein Rodney , Darzacq Xavier
Published: August 2017

The dynamic organization of genes inside the nucleus is an important determinant for their function. Using fast DNA tracking microscopy in Saccharomyces cerevisiae cells and improved analysis of mean-squared displacements, we quantified DNA motion at time scales ranging from 10 ms to minutes and found that following DNA damage, DNA exhibits distinct subdiffusive regimes. In response to double-strand breaks, chromatin is more mobile at large time scales, but, surprisingly, its mobility is reduced at short time scales. This effect is even more pronounced at the site of damage. Such a pattern of dynamics is consistent with a global increase in chromatin persistence length in response to DNA damage. Scale-dependent nuclear exploration is regulated by the Rad51 repair protein, both at the break and throughout of the genome. We propose a model in which stiffening of the damaged ends by the repair complex, combined with global increased stiffness, act like a “needle in a ball of yarn,” enhancing the ability of the break to traverse the chromatin meshwork.
There Are Many More Positive Maps Than Completely Positive Maps
Authors: Klep Igor , McCullough Scott , Šivic Klemen , Zalar Aljaž
Published: August 2017

A $\ast$-linear map $\Phi$ between matrix spaces is positive if it maps positive semidefinite matrices to positive semidefinite ones, and is called completely positive if all its ampliations $I_n\otimes \Phi$ are positive. In this article, quantitative bounds on the fraction of positive maps that are completely positive are proved. A main tool is the real algebraic geometry techniques developed by Blekherman to study the gap between positive polynomials and sums of squares. Finally, an algorithm to produce positive maps that are not completely positive is given.
Successful Treatment of Influenza-Associated Acute Necrotizing Encephalitis in an Adult Using High-Dose Oseltamivir and Methylprednisolone: Case Report and Literature Review
Authors: Alsolami Ahmed , Shiley Kevin
Published: August 2017

A case of influenza-associated acute necrotizing encephalitis (ANE) is described in an otherwise healthy adult. The patient was treated successfully with a combination of high-dose methylprednisolone and high-dose oseltamivir. The patient relapsed after discontinuing 150 mg twice daily oseltamivir but quickly improved and eventually recovered after reinitiation of high-dose oseltamivir for an additional 2 weeks. The clinical presentation, pathogenesis, and treatment of influenza-associated ANE is reviewed. The use of high-dose oseltamivir in combination with methylprednisolone may offer additional therapeutic benefit for this rare and poorly understood complication of influenza infection.
High Relative Parasitic Fitness of G22 Derivatives is Associated with the Epidemic Potential of Wheat Stripe Rust in China
Authors: Bai Bing Bing , Liu Tai Guo , Liu Bo , Gao Li , Chen Wan Quan
Published: August 2017

In total, 13 commercial wheat cultivars around China and four races of Puccinia striiformis f. sp. tritici (namely, CYR32, CYR33, G22-9, and G22-14) were employed for a test of relative parasitic fitness (RPF) using the drop method. The RPF values were measured, including the urediniospore germination rate, the latent period, the uredinial length, the uredinial density, the infection area, the sporulation intensity, the lesion expansion speed, and the sporulation period. The results indicated that the parameters of relative parasitic fitness of the four P. striiformis f. sp. tritici races on the 13 wheat cultivars were significantly different (P = 0.00) in sporulation intensity, lesion expansion speed, uredinial length, sporulation period, uredinial density, and latent period. The urediniospore germination rates of the four P. striiformis f. sp. tritici races for the test were significantly different (P = 0.00), whereas no correlation with the different cultivars was observed (P = 1.00). The infection areas of the tested races on the different cultivars were significantly different (P = 0.00) but there were no obvious manifestations among the various races (P = 0.20). Principal component analysis (PCA) showed that the sporulation intensity represented sporulation capacity and scalability, the latent period indicated infection ability, and the urediniospore germination rate represented urediniospore vigor, all of which fully contributed to the RPF in the interaction of the four races and 13 wheat cultivars, which was calculated by the following formula: RPF = (sporulation intensity × urediniospore germination rate)/latent period. The sporulation and infection of G22-9 on the 13 large-scale cultivated cultivars were the highest, and the RPF of G22-9 was higher than that of the predominant races, CYR32 and CYR33. This result suggested that G22-9 could become a new predominant race and potentially cause epidemics of wheat stripe rust in China. To prevent potential epidemics, susceptible wheat cultivars should be withdrawn from production and breeding programs should reduce the use of Yr10 and Yr26 and use other more effective resistance genes in combination with nonrace-specific resistance for developing wheat cultivars with durable resistance to stripe rust.
The Academy of Master Clinicians: Recognition of Clinical Excellence Within an Academic Medical Center
Authors: Glick John H. , Mulhern Victoria , Olthoff Kim M. , Ende Jack
Published: August 2017

Problem

Academic health centers face increasing challenges in pursuing and maintaining clinical excellence in their tripartite mission. At Penn Medicine, an institution-wide strategic planning process was initiated in 2012. Among the recommendations that arose from that process was to enhance the recognition of Penn Medicine’s most outstanding clinicians. The Academy of Master Clinicians (AoMC) was founded in 2013.

Approach

The ad hoc committee charged with the development and implementation of the AoMC provided a mission statement, eligibility criteria, and a process for nomination and selection of AoMC members. This process was inclusive, extending to all entities of Penn Medicine. Various forms of institutional service were incorporated into the expectations for membership.

Outcomes

To date, 53 clinicians have been selected for membership in the AoMC. Members meet monthly to focus on significant institutional issues. Initiatives are identified for member leadership and participation. Members are engaged in activities and programs for medical students, residents, and faculty, focusing on areas such as career advising, faculty development, physician burnout, and practice operations. The executive vice president (EVP)/dean has commented that the AoMC is “highly visible and impactful.”

Next Steps

A yearly report on outcomes and impact of the AoMC is provided to the EVP and chief executive officer. In addition, at the end of each academic year, the members of the AoMC determine two to three new initiatives on which to work to formulate issues and potential actions.
Synthetic Cannabis Analogues and Suicidal Behavior: Case Report
Authors: Oliveira Pedro Miguel dos Santos , Morais Ana Sofia Félix , Madeira Nuno Gonçalo Gomes Fernandes
Published: August 2017

Introduction:

Despite growing legal control, a wide range of synthetic cannabis analogues is currently used for recreational purposes, notwithstanding their well adverse outcomes, which appear to be more frequent and more serious than those associated with cannabis use. We present the case report of a patient with paranoid schizophrenia, who attempted suicide by serious bodily harm after a single use of “Shiva Ultra Strong,” a compound of several synthetic cannabis analogues.

Case Summary:

A 32-year-old male patient with paranoid schizophrenia was brought to the emergency department presenting with a severe self-inflicted wound to the neck which lacerated the right jugular vein and ipsilateral airway, and narrowly missed the carotid bifurcation. On examination, the patient exhibited psychomotor agitation and anxiety. Laboratory tests, which included routine substance use screening, proved unremarkable. The patient was admitted to the ENT Department for surgical treatment, after which he was transferred to our Psychiatry Department, exhibiting consistent improvement with his usual antipsychotic regimen, to which he had good previous adherence. Later, after discharge, he admitted to having used a smartshop drug, so-called “Shiva Ultra Strong,” shortly before the suicide attempt.

Conclusion:

Although current data on the suicide risk of synthetic cannabis analogues are limited, there is growing evidence of relevant psychiatric effects after their use. Patients with serious mental disorders could prove particularly vulnerable to these drugs, resulting in severe behavioral changes and self-harm.
Human Immunodeficiency Virus Viral Load Rebound Near Delivery in Previously Suppressed, Combination Antiretroviral Therapy–Treated Pregnant Women
Authors: Boucoiran Isabelle , Albert Arianne Y. K. , Tulloch Karen , Wagner Emily C. , Pick Neora , van Schalkwyk Julie , Harrigan P. Richard , Money Deborah
Published: August 2017

OBJECTIVE:

To assess the stability of human immunodeficiency virus (HIV) viral load suppression within 1 month before birth in pregnant women receiving antenatal combination antiretroviral therapy (CART).

METHODS:

This is a retrospective cohort study of a Canadian provincial perinatal HIV database from 1997 to 2015. Inclusion criteria were live birth and CART received for at least 4 weeks. Viral load rebound, defined as viral load greater than 50 copies/mL (or greater than 400 copies/mL for 1997–1998) and measured within 1 month before delivery, was identified in women who had at least one previous undetectable viral load during pregnancy. Logistic regressions were conducted to identify the risk factors for viral load rebound.

RESULTS:

Among the 470 women in the database, 318 met inclusion criteria. Viral load rebound was experienced by 19 women (6.0%, 95% CI 3.7–9.3%) with a mean log10 viral load near delivery of 2.71 copies/mL (=513 copies/mL). Six (32%) had a viral load above 1,000 copies/mL. The rebound was detected within 1 day before delivery in 50% of the women. Aboriginal ethnicity, cocaine use, and hepatitis C virus polymerase chain reaction positivity were significantly associated with viral load rebound. There were no HIV vertical transmissions.

CONCLUSION:

Even women attending for HIV care and achieving viral suppression in pregnancy can experience viral load rebound predelivery.
Association Between Type of Screening for Gestational Diabetes Mellitus and Cesarean Delivery
Authors: Palatnik Anna , Swanson Kate , Churchill Tessa , Bilski Ania , Grobman William A. , Miller Emily S.
Published: August 2017

OBJECTIVE:

To compare maternal and neonatal outcomes using two different testing strategies for gestational diabetes mellitus (GDM) diagnosis: the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) and Carpenter-Coustan approaches. Specifically, we wanted to compare the rates of cesarean delivery between the two epochs.

METHODS:

This was a retrospective cohort study of women with a singleton pregnancy delivering at 37 0/7 weeks of gestation or greater, between 2010 and 2015, in a single tertiary care center. The IADPSG testing was used for GDM diagnosis from December 2010 until July 2013 when institutional guidelines changed to Carpenter-Coustan testing. Maternal and neonatal outcomes were compared between these two different epochs using bivariable and multivariable analyses. The primary outcome was the frequency of cesarean delivery.

RESULTS:

The analysis included a total of 23,509 women: 14,074 (60%) from the IADPSG epoch and 9,435 (40%) from the Carpenter-Coustan epoch. The incidence of GDM diagnosis was higher using the IADPSG compared with Carpenter-Coustan criteria (8.3% compared with 7.5%, P=.042). The total (27.0% compared with 25.5% P=.022) as well as primary cesarean delivery rates (19.1% compared with 18.0%, P=.041) were higher during the IADPSG epoch. The rates of total (39.1% compared with 37.5%, P=.594) and primary (27.3% compared with 27.0%, P=.903) cesarean delivery among women with GDM did not differ between the two epochs. Secondary outcomes of shoulder dystocia (2.5% compared with 2.1%, P=.043) and neonatal intensive care unit admission (3.2% compared with 2.0%, P<.001) also were significantly higher in women screened during the IADPSG epoch, whereas hypertensive disease of pregnancy (6.9% compared with 7.7%, P=.018) was less frequent during the IADPSG epoch. These findings persisted after adjusting for potential confounding factors.

CONCLUSION:

Compared with testing using the Carpenter-Coustan criteria, the IADPSG criteria for diagnosis of GDM were associated with higher rates of GDM, cesarean delivery, shoulder dystocia, and neonatal intensive care unit admission. Obstetric care provider knowledge of GDM diagnosis might have affected decision-making regarding the route of delivery.
MRI scoring methods used in evaluation of muscle involvement in patients with idiopathic inflammatory myopathies
Authors: Kubínová Kateřina , Mann Heřman , Vencovský Jiří
Published: August 2017

Purpose of review

MRI is a promising imaging method commonly used to assess muscle involvement in patients with idiopathic inflammatory myopathies (IIM). MRI enables evaluation of both activity and damage and is therefore an ideal noninvasive diagnostic and monitoring tool. Despite its widespread use, there is no universally accepted method for scoring and reporting of MRI findings. The aim of this review is to provide an overview of systems used in the evaluation of MR images in patients with IIM.

Recent findings

A number of semi-quantitative and quantitative methods have been used to evaluate and record the severity of myopathy on MRI. These scoring systems differ in the number and type of parameters assessed and in their complexity; furthermore, they were evaluated in different patient populations, all of which make comparisons between them difficult.

There is a need to create a standardized and validated protocol for evaluation of pathological changes in muscle MRI in IIM. The most appropriate number and distribution of muscle groups as well as evaluated pathological features need to be determined. Based on this literature search, the future scoring system should include assessment of muscle oedema, fatty infiltration, muscle atrophy and possibly the presence of fascial and subcutaneous inflammation. Whether the quantitative methods provide more reliable information regarding disease activity remains unclear.
New Trends in Ring Fixators
Authors: Iobst Christopher A.
Published: August 2017

Multiple versions of ring fixators are currently available to orthopaedic surgeons. Although the traditional Ilizarov-type ring fixator is still available, many surgeons are now using computer-assisted hexapod frames. There has been a recent surge in the number of different hexapod ring fixators on the market. This article will review some of the new trends in ring fixator hardware and software as well as discuss possible future directions of ring fixator development.