bluuebunny/crossref_metadata_2025 huggingface dataset:
Very low noise AC/DC power supply systems for large detector arrays
Authors: Arnaboldi C. , Baù A. , Carniti P. , Cassina L. , Giachero A. , Gotti C. , Maino M. , Passerini A. , Pessina G.
Published: December 2015

In this work, we present the first part of the power supply system for the CUORE and LUCIFER arrays of bolometric detectors. For CUORE, it consists of AC/DC commercial power supplies (0–60 V output) followed by custom DC/DC modules (48 V input, ±5 V to ±13.5 V outputs). Each module has 3 floating and independently configurable output voltages. In LUCIFER, the AC/DC + DC/DC stages are combined into a commercial medium-power AC/DC source. At the outputs of both setups, we introduced filters with the aim of lowering the noise and to protect the following stages from high voltage spikes that can be generated by the energy stored in the cables after the release of accidental short circuits. Output noise is very low, as required: in the 100 MHz bandwidth the RMS level is about 37 μVRMS (CUORE setup) and 90 μVRMS (LUCIFER setup) at a load of 7 A, with a negligible dependence on the load current. Even more importantly, high frequency switching disturbances are almost completely suppressed. The efficiency of both systems is above 85%. Both systems are completely programmable and monitored via CAN bus (optically coupled).
Hamiltonian purification
Authors: Orsucci Davide , Burgarth Daniel , Facchi Paolo , Nakazato Hiromichi , Pascazio Saverio , Yuasa Kazuya , Giovannetti Vittorio
Published: December 2015

The problem of Hamiltonian purification introduced by Burgarth et al. [Nat. Commun. 5, 5173 (2014)] is formalized and discussed. Specifically, given a set of non-commuting Hamiltonians {h1, …, hm} operating on a d-dimensional quantum system ℋd, the problem consists in identifying a set of commuting Hamiltonians {H1, …, Hm} operating on a larger dE-dimensional system ℋdE which embeds ℋd as a proper subspace, such that hj = PHjP with P being the projection which allows one to recover ℋd from ℋdE. The notions of spanning-set purification and generator purification of an algebra are also introduced and optimal solutions for 𝔲(d) are provided.
Optical bandgap widening and phase transformation of nitrogen doped cupric oxide
Authors: Masudy-Panah Saeid , Radhakrishnan K. , Kumar Avishek , Wong Ten It , Yi Ren , Dalapati Goutam Kumar
Published: December 2015

The structural and optical properties of sputter deposited nitrogen (N) doped CuO (CuO(N)) thin films are systematically investigated. It is found that the incorporation of N into CuO causes an enlargement of optical bandgap and reduction in resistivity of the CuO(N) films. Furthermore, a gradual phase transformation from CuO to Cu2O is observed with the increase in N concentration. The effects of annealing temperature on the structural properties of CuO (N) and its dependence on N concentration are also investigated. It is observed that the phase transformation process from CuO to Cu2O significantly depends on the N concentration and the annealing temperature. Heterojunction solar cells of p-type CuO(N) on n-type silicon (Si) substrate, p-CuO(N)/n-Si, are fabricated to investigate the impact of N doping on its photovoltaic properties.
Coronene molecules in helium clusters: Quantum and classical studies of energies and configurations
Authors: Rodríguez-Cantano Rocío , Pérez de Tudela Ricardo , Bartolomei Massimiliano , Hernández Marta I. , Campos-Martínez José , González-Lezana Tomás , Villarreal Pablo , Hernández-Rojas Javier , Bretón José
Published: December 2015

Coronene-doped helium clusters have been studied by means of classical and quantum mechanical (QM) methods using a recently developed He–C24H12 global potential based on the use of optimized atom-bond improved Lennard-Jones functions. Equilibrium energies and geometries at global and local minima for systems with up to 69 He atoms were calculated by means of an evolutive algorithm and a basin-hopping approach and compared with results from path integral Monte Carlo (PIMC) calculations at 2 K. A detailed analysis performed for the smallest sizes shows that the precise localization of the He atoms forming the first solvation layer over the molecular substrate is affected by differences between relative potential minima. The comparison of the PIMC results with the predictions from the classical approaches and with diffusion Monte Carlo results allows to examine the importance of both the QM and thermal effects.
Polaronic exciton binding energy in iodide and bromide organic-inorganic lead halide perovskites
Authors: Soufiani Arman Mahboubi , Huang Fuzhi , Reece Peter , Sheng Rui , Ho-Baillie Anita , Green Martin A.
Published: December 2015

The last 4 years have seen the rapid emergence of a new solar cell technology based on organic-inorganic lead halide perovskites, primarily CH3NH3PbI3 and related halides involving Cl and Br. Debate continues on the role of excitons and free carriers in these materials. Recent studies report values of exciton binding energy for the iodide ranging from 0.7 meV to 200 meV, with vastly different implications for device operation and design. In the present work, previously neglected polarons are shown likely to have a major impact in determining excitonic properties. Polaronic exciton binding energies calculated using effective longitudinal optical phonon energies, deduced from permittivity measurements, are shown consistent with experimental energies for good quality samples of CH3NH3PbI3 and CH3NH3PbBr3, as determined over a large temperature range from optical absorption data. Bandgaps determined simultaneously show a discontinuity at the orthorhombic to tetragonal phase transition for the iodide, but not for the bromide.
Electronic coupling through natural amino acids
Authors: Berstis Laura , Beckham Gregg T. , Crowley Michael F.
Published: December 2015

Myriad scientific domains concern themselves with biological electron transfer (ET) events that span across vast scales of rate and efficiency through a remarkably fine-tuned integration of amino acid (AA) sequences, electronic structure, dynamics, and environment interactions. Within this intricate scheme, many questions persist as to how proteins modulate electron-tunneling properties. To help elucidate these principles, we develop a model set of peptides representing the common α-helix and β-strand motifs including all natural AAs within implicit protein-environment solvation. Using an effective Hamiltonian strategy with density functional theory, we characterize the electronic coupling through these peptides, furthermore considering side-chain dynamics. For both motifs, predictions consistently show that backbone-mediated electronic coupling is distinctly sensitive to AA type (aliphatic, polar, aromatic, negatively charged and positively charged), and to side-chain orientation. The unique properties of these residues may be employed to design activated, deactivated, or switch-like superexchange pathways. Electronic structure calculations and Green’s function analyses indicate that localized shifts in the electron density along the peptide play a role in modulating these pathways, and further substantiate the experimentally observed behavior of proline residues as superbridges. The distinct sensitivities of tunneling pathways to sequence and conformation revealed in this electronic coupling database help improve our fundamental understanding of the broad diversity of ET reactivity and provide guiding principles for peptide design.
Interplay between crystallinity profiles and the performance of microcrystalline thin-film silicon solar cells studied by in-situ Raman spectroscopy
Authors: Fink T. , Muthmann S. , Mück A. , Gordijn A. , Carius R. , Meier M.
Published: December 2015

The intrinsic microcrystalline absorber layer growth in thin-film silicon solar-cells is investigated by in-situ Raman spectroscopy during plasma enhanced chemical vapor deposition. In-situ Raman spectroscopy enables a detailed study of the correlation between the process settings, the evolution of the Raman crystallinity in growth direction, and the photovoltaic parameters η (solar cell conversion efficiency), JSC (short circuit current density), FF (fill factor), and VOC (open circuit voltage). Raman spectra were taken every 7 nm of the absorber layer growth depending on the process settings. The Raman crystallinity of growing microcrystalline silicon was determined with an absolute error of approximately ±5% for total absorber layer thicknesses >50 nm. Due to this high accuracy, inherent drifts of the Raman crystallinity profiles are resolvable for almost the entire absorber layer deposition. For constant process settings and optimized solar cell device efficiency Raman crystallinity increases during the absorber layer growth. To compensate the inhomogeneous absorber layer growth process settings were adjusted. As a result, absorber layers with a constant Raman crystallinity profile — as observed in-situ — were deposited. Solar cells with those absorber layers show a strongly enhanced conversion efficiency by ∼0.5% absolute. However, the highest FF, VOC, and JSC were detected for solar cells with different Raman crystallinity profiles. In particular, fill factors of 74.5% were observed for solar cells with decreasing Raman crystallinity during the later absorber layer growth. In contrast, intrinsic layers with favorable JSC are obtained for constant and increasing Raman crystallinity profiles. Therefore, monitoring the evolution of the Raman crystallinity in-situ provides sufficient information for an optimization of the photovoltaic parameters with surpassing depth resolution.
Temperature dependence of Soret and diffusion coefficients for toluene–cyclohexane mixture measured in convection-free environment
Authors: Mialdun A. , Shevtsova V.
Published: December 2015

We report on the measurement of diffusion (D), Soret (ST), and thermodiffusion (DT) coefficients in toluene–cyclohexane mixture with mass fraction of toluene 0.40 onboard of the International Space Station. The coefficients were measured in the range of the mean temperatures between 20 °C and 34 °C. The Soret coefficient is negative within the investigated temperature range and its absolute value |ST| decreases with increasing temperature. The diffusion coefficient for this system increases with temperature rising. For comparison, the temperature dependence of diffusion coefficient was measured in ground laboratory using counter-flow cell technique and revealed a good agreement with microgravity results. A non-direct comparison of the measured onboard Soret coefficients with different systems indicated a similar trend for the temperature dependent behavior. Unexpected experimental finding is that for this system the thermodiffusion coefficient DT does not depend on temperature.
Simulation of a runaway electron avalanche developing in an atmospheric pressure air discharge
Authors: Oreshkin E. V. , Barengolts S. A. , Chaikovsky S. A. , Oreshkin V. I.
Published: December 2015

To gain a better understanding of the operation of atmospheric pressure air discharges, the formation of a runaway electron beam at an individual emission site on the cathode has been numerically simulated. The model provides a description of the dynamics of the fast electrons emitted into an air gap from the surface of the emission zone by solving numerically two-dimensional equations for the electrons. It is supposed that the electric field at the surface of the emission zone is enhanced, providing conditions for continuous acceleration of the emitted electrons. It is shown that the formation of a runaway electron beam in a highly overvolted discharge is largely associated with avalanche-type processes and that the number of electrons in the avalanche reaches 50% of the total number of runaway electrons.
MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation
Authors: Ivanov I. A. , Arzhannikov A. V. , Burdakov A. V. , Burmasov V. S. , Gavrilenko D. E. , Kasatov A. A. , Kandaurov I. V. , Kurkuchekov V. V. , Kuznetsov S. A. , Mekler K. I. , Polosatkin S. V. , Popov S. S. , Postupaev V. V. , Rovenskikh A. F. , Sklyarov V. F. , Sorokina N. V. , Trunev Yu. A. , Vyacheslavov L. N.
Published: December 2015

There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70–110 keV for the electron energy, 1–10 MW for the beam power and 30–300 μs for its duration. The spectrum was measured in 75–230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.
Surface characterization of InP trenches embedded in oxide using scanning probe microscopy
Authors: Mannarino Manuel , Chintala Ravi , Moussa Alain , Merckling Clement , Eyben Pierre , Paredis Kristof , Vandervorst Wilfried
Published: December 2015

Metrology for structural and electrical analyses at device level has been identified as one of the major challenges to be resolved for the sub-14 nm technology nodes. In these advanced nodes, new high mobility semiconductors, such as III–V compounds, are grown in narrow trenches on a Si substrate. Probing the nature of the defects, the defect density, and the role of processing steps on the surface of such structures are prime metrology requirements. In order to enable defect analysis on a (III–V) surface, a proper sample preparation for oxide removal is of primary importance. In this work, the effectiveness of different chemical cleanings and thermal annealing procedures is investigated on both blanket InP and oxide embedded InP trenches by means of scanning probe microscopy techniques. It is found that the most effective approach is a combination of an HCl-based chemical cleaning combined with a low-temperature thermal annealing leading to an oxide free surface with atomically flat areas. Scanning tunneling microscopy (STM) has been the preferred method for such investigations on blanket films due to its intrinsic sub-nm spatial resolution. However, its application on oxide embedded structures is non-trivial. To perform STM on the trenches of interest (generally <20 nm wide), we propose a combination of non-contact atomic force microscopy and STM using the same conductive atomic force microscopy tip Our results prove that with these procedures, it is possible to perform STM in narrow InP trenches showing stacking faults and surface reconstruction. Significant differences in terms of roughness and terrace formation are also observed between the blanket and the oxide embedded InP.
Predicting a quaternary tungsten oxide for sustainable photovoltaic application by density functional theory
Authors: Sarker Pranab , Al-Jassim Mowafak M. , Huda Muhammad N.
Published: December 2015

A quaternary oxide, CuSnW2O8 (CTTO), has been predicted by density functional theory (DFT) to be a suitable material for sustainable photovoltaic applications. CTTO possesses band gaps of 1.25 eV (indirect) and 1.37 eV (direct), which were evaluated using the hybrid functional (HSE06) as a post-DFT method. The hole mobility of CTTO was higher than that of silicon. Further, optical absorption calculations demonstrate that CTTO is a better absorber of sunlight than Cu2ZnSnS4 and CuInxGa1−xSe2 (x = 0.5). In addition, CTTO exhibits rigorous thermodynamic stability comparable to WO3, as investigated by different thermodynamic approaches such as bonding cohesion, fragmentation tendency, and chemical potential analysis. Chemical potential analysis further revealed that CTTO can be synthesized at flexible experimental growth conditions, although the co-existence of at least one secondary phase is likely. Finally, like other Cu-based compounds, the formation of Cu vacancies is highly probable, even at Cu-rich growth condition, which could introduce p-type activity in CTTO.
A study on improvement of discharge characteristic by using a transformer in a capacitively coupled plasma
Authors: Kim Young-Cheol , Kim Hyun-Jun , Lee Hyo-Chang , Chung Chin-Wook
Published: December 2015

In a plasma discharge system, the power loss at powered line, matching network, and other transmission line can affect the discharge characteristics such as the power transfer efficiency, voltage and current at powered electrode, and plasma density. In this paper, we propose a method to reduce power loss by using a step down transformer mounted between the matching network and the powered electrode in a capacitively coupled argon plasma. This step down transformer decreases the power loss by reducing the current flowing through the matching network and transmission line. As a result, the power transfer efficiency was increased about 5%–10% by using a step down transformer. However, the plasma density was dramatically increased compared to no transformer. This can be understood by the increase in ohmic heating and the decrease in dc-self bias. By simply mounting a transformer, improvement of discharge efficiency can be achieved in capacitively coupled plasmas.
Probing electronic lifetimes and phonon anharmonicities in high-quality chemical vapor deposited graphene by magneto-Raman spectroscopy
Authors: Neumann Christoph , Halpaap Donatus , Reichardt Sven , Banszerus Luca , Schmitz Michael , Watanabe Kenji , Taniguchi Takashi , Beschoten Bernd , Stampfer Christoph
Published: December 2015

We present a magneto-Raman study on high-quality single-layer graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride by a dry transfer technique. By analyzing the Raman D, G, and 2D peaks, we find that the structural quality of the samples is comparable with state-of-the-art exfoliated graphene flakes. From B-field dependent Raman measurements, we extract the broadening and associated lifetime of the G peak due to anharmonic effects. Furthermore, we determine the decay width and lifetime of Landau level (LL) transitions from magneto-phonon resonances as a function of laser power. At low laser power, we find a minimal decay width of 140 cm−1 highlighting the high electronic quality of the CVD-grown graphene. At higher laser power, we observe an increase of the LL decay width leading to a saturation, with the corresponding lifetime saturating at a minimal value of 18 fs.
Temperature dependence of the electron Landé g-factor in cubic GaN
Authors: Buß J. H. , Schupp T. , As D. J. , Hägele D. , Rudolph J.
Published: December 2015

The temperature dependence of the electron Landé g-factor in bulk cubic GaN is investigated over an extremely broad temperature range from 15 K up to 500 K by time-resolved Kerr-rotation spectroscopy. The g-factor is found to be approximately constant over the full investigated temperature range. Calculations by k·p-theory predict a negligible temperature dependence g(T) in complete agreement with the experiment as a consequence of the large band-gap and small spin orbit splitting in cubic GaN.
Fully magnetic printing by generation of magnetic droplets on demand with a coilgun
Authors: Vekselman Vladislav , Sande Luke , Kornev Konstantin G.
Published: December 2015

In this paper, we exhibit a coilgun-based approach to drop-on-demand printing of liquids laden with magnetic particles. In contrast to other drop-on-demand technologies designed to print droplets only in gaseous environments, this methodology allows one to print magnetic droplets inside any gaseous or liquid media using the same coilgun. Furthermore, we demonstrate the basic principles of magnetic drop-on-demand generation and show the physico-chemical parameters controlling the process.
A crossover in anisotropic nanomechanochemistry of van der Waals crystals
Authors: Shimamura Kohei , Misawa Masaaki , Li Ying , Kalia Rajiv K. , Nakano Aiichiro , Shimojo Fuyuki , Vashishta Priya
Published: December 2015

In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a crossover of anisotropic nanomechanochemistry of vdW crystal. Within 10−13 s from the passage of shock front, lateral collision produces NO2 via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10−12 s, shock normal to multilayers becomes more reactive, producing H2O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies.
Effects of strain on electronic and optic properties of holey two-dimensional C2N crystals
Authors: Guan Shan , Cheng Yingchun , Liu Chang , Han Junfeng , Lu Yunhao , Yang Shengyuan A. , Yao Yugui
Published: December 2015

A two-dimensional (2D) material, the holey 2D C2N (h2D-C2N) crystal, has recently been synthesized. Here, we investigate the strain effects on the properties of this material by first-principles calculations. We show that the material is quite soft with a small stiffness constant and can sustain large strains ≥12%. It remains a direct gap semiconductor under strain, and the bandgap size can be tuned in a wide range as large as 1 eV. Interestingly, for biaxial strain, a band crossing effect occurs at the valence band maximum close to a 8% strain, leading to a dramatic increase of the hole effective mass. Strong optical absorption can be achieved by strain tuning with absorption coefficient ∼106 cm−1 covering a wide spectrum. Our findings suggest the great potential of strain-engineered h2D-C2N in electronic and optoelectronic device applications.
Suppression of low-frequency charge noise in gates-defined GaAs quantum dots
Authors: You Jie , Li Hai-Ou , Wang Ke , Cao Gang , Song Xiang-Xiang , Xiao Ming , Guo Guo-Ping
Published: December 2015

To reduce the charge noise of a modulation-doped GaAs/AlGaAs quantum dot, we have fabricated shallow-etched GaAs/AlGaAs quantum dots using the wet-etching method to study the effects of two-dimensional electron gas (2DEG) underneath the metallic gates. The low-frequency 1/f noise in the Coulomb blockade region of the shallow-etched quantum dot is compared with a non-etched quantum dot on the same wafer. The average values of the gate noise are approximately 0.5 μeV in the shallow-etched quantum dot and 3 μeV in the regular quantum dot. Our results show the quantum dot low-frequency charge noise can be suppressed by the removal of the 2DEG underneath the metallic gates, which provides an architecture for noise reduction.
Fast reconstruction of a bounded ultrasonic beam using acoustically induced piezo-luminescence
Authors: Kersemans Mathias , Smet Philippe F. , Lammens Nicolas , Degrieck Joris , Van Paepegem Wim
Published: December 2015

We report on the conversion of ultrasound into light by the process of piezo-luminescence in epoxy with embedded BaSi2O2N2:Eu as active component. We exploit this acoustically induced piezo-luminescence to visualize several cross-sectional slices of the radiation field of an ultrasonic piston transducer (f = 3.3 MHz) in both the near-field and the far-field. Simply combining multiple slices then leads to a fast representation of the 3D spatial radiation field. We have confronted the luminescent results with both scanning hydrophone experiments and digital acoustic holography results, and obtained a good correlation between the different approaches.
Thin film polycrystalline Si solar cells studied in transient regime by optical pump–terahertz probe spectroscopy
Authors: Pikna P. , Skoromets V. , Becker C. , Fejfar A. , Kužel P.
Published: December 2015

We used time-resolved terahertz spectroscopy to study ultrafast photoconductivity of polycrystalline thin-film silicon solar cells. We selected a series of samples, which exhibited variable conversion efficiencies due to hydrogen plasma passivation under various technological conditions. The decay of the transient terahertz conductivity shows two components: the fast one is related to the charge recombination at interfaces, while the slow nanosecond one is attributed to the trapping of photocarriers by defects localized at grain boundaries or at dislocations in the polycrystalline p− layer of the structure. We observed a clear correlation between the open-circuit voltage and the nanosecond-scale decay time of the transient terahertz conductivity of the solar cells. Thus, the terahertz spectroscopy appears to be a useful contactless tool for inspecting the local photoconductivity of solar cells including, in particular, various nanostructured schemes.
Demonstration of solar-blind AlxGa1−xN-based heterojunction phototransistors
Authors: Zhang Lingxia , Tang Shaoji , Liu Changshan , Li Bin , Wu Hualong , Wang Hailong , Wu Zhisheng , Jiang Hao
Published: December 2015

Al0.4Ga0.6N/Al0.65Ga0.35N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 103 was obtained at 6 V bias.
Evolutionary divergences in root system morphology, allocation, and nitrogen uptake in species from high- versus low-fertility soils
Authors: Bowsher Alan W. , Miller Benjamin J. , Donovan Lisa A.
Published: December 2015

Root morphology and nutrient uptake processes are essential for acquisition of mineral resources from soil. However, our understanding of how root form and function have diverged across environments is limited. In this study, we addressed hypotheses of adaptive differentiation using three pairs of Helianthus species chosen as phylogenetically-independent contrasts with respect to native soil nutrients. Under controlled environmental conditions, root morphology, allocation, and nitrogen (N) uptake (using a 15N tracer) were assessed for seedlings under both high and low N treatments. Species native to low nutrient soils (LNS) had lower total root length than those native to high nutrient soils (HNS), reflecting the slower growth rates of species from less fertile environments. Contrary to expectations, species did not consistently differ in specific root length, root tissue density, or root system plasticity, and species native to LNS had lower root : total mass ratio and higher 15N uptake rates than species native to HNS. Overall, these evolutionary divergences provide support for adaptive differentiation among species, with repeated evolution of slow-growing root systems suited for low resource availability in LNS. However, species native to LNS maintain a high capacity for N uptake, potentially as a means of maximising nutrient acquisition from transient pulses.
Computational complexity of ecological and evolutionary spatial dynamics
Authors: Ibsen-Jensen Rasmus , Chatterjee Krishnendu , Nowak Martin A.
Published: December 2015

Significance

An important question in evolution is: how does population structure affect the outcome of the evolutionary process? The theory of evolution in structured population has provided an impressive range of results, but an understanding of the computational complexity of even simple questions was missing. We prove that some fundamental problems in ecology and evolution can be precisely characterized by well-established computational complexity classes. This implies that the problems cannot be answered by simple equations. For example, there cannot be simple formulas for the fixation probability of a mutant given frequency-dependent selection in a structured population. We also show that, for example, calculating the molecular clock of neutral evolution in structured populations admit efficient algorithmic solutions.
Discovery of a nucleocytoplasmic O-mannose glycoproteome in yeast
Authors: Halim Adnan , Larsen Ida Signe Bohse , Neubert Patrick , Joshi Hiren Jitendra , Petersen Bent Larsen , Vakhrushev Sergey Y. , Strahl Sabine , Clausen Henrik
Published: December 2015

Significance

Nucleocytoplasmic dynamic cycling of
N
-Acetylglucosamine (GlcNAc) on serine and threonine residues (O-GlcNAcylation) and phosphorylation coregulate important cellular processes in all eukaryotic organisms except yeast, including
Saccharomyces cerevisiae
and
Schizosaccharomyces pombe
. The lack of an equivalent nucleocytoplasmic O-glycosylation system in yeast has been difficult to explain given that O-GlcNAcylation is an essential modification in higher organisms. Here, we reveal that yeast use O-linked mannose to modify nucleocytoplasmic proteins on evolutionary-conserved regions and sites normally occupied by O-GlcNAc in higher eukaryotes. The results presented in this study open new avenues for exploration of nutrient sensing and signaling events based on nucleocytoplasmic O-glycosylation in yeast.
Global phosphorus retention by river damming
Authors: Maavara Taylor , Parsons Christopher T. , Ridenour Christine , Stojanovic Severin , Dürr Hans H. , Powley Helen R. , Van Cappellen Philippe
Published: December 2015

Significance

Phosphorus is an essential nutrient for life. Humans have massively altered the global phosphorus cycle by increasing loading to river systems through fertilizer use, soil erosion, and wastewater discharges. River damming interacts with anthropogenic phosphorus enrichment by trapping a fraction of the phosphorus in reservoir sediments. We estimate that in 2000, 12% of the global river phosphorus load was retained in dam reservoirs. This fraction could increase to 17% by 2030, because of the construction of over 3,700 new dams. Although reservoirs represent a huge phosphorus sink, rising anthropogenic phosphorus emissions continue to outpace the addition of new retention capacity by river damming. The resulting growth in riverine phosphorus export likely contributes to the expanding eutrophication of surface waters worldwide.
AMPA receptor inhibition by synaptically released zinc
Authors: Kalappa Bopanna I. , Anderson Charles T. , Goldberg Jacob M. , Lippard Stephen J. , Tzounopoulos Thanos
Published: December 2015

Significance

Ionotropic glutamate AMPA receptors (AMPARs) play a fundamental role in normal function and plasticity of the brain, and they are also involved in many brain disorders. Despite the central role of AMPARs in neurobiology, the modulation of synaptic AMPA responses by endogenous modulators remains not well understood. Here, in three synapses found in two different brain areas, we provide the first evidence, to our knowledge, that endogenous zinc is coreleased with glutamate and modulates the strength of synaptic AMPAR responses. Because in many neocortical areas more than 50% of excitatory presynaptic terminals contain zinc within their glutamatergic vesicles, our findings establish zinc as a general neuromodulator that allows for fine-tuning and plasticity of glutamatergic fast synaptic transmission in the brain.
Inequality, climate impacts on the future poor, and carbon prices
Authors: Dennig Francis , Budolfson Mark B. , Fleurbaey Marc , Siebert Asher , Socolow Robert H.
Published: December 2015

Significance

Hundreds of published papers produce “optimal” trajectories of global emissions of carbon dioxide, and corresponding carbon prices, over this century, taking into account future damages inflicted by climate change. To our knowledge, in all instances the models ignore inequalities in economic variables beyond regional differences. Here, we introduce heterogeneous subregional populations (distributed by income) and explore how the optimal trajectories are affected by whether regional damage afflicts the poor predominantly. We find that when future damage falls especially hard on the poor, considerably greater global mitigation effort is optimal than when damage is proportional to income.
Inositol phosphate kinase 2 is required for imaginal disc development in
Drosophila
Authors: Seeds Andrew M. , Tsui Marco M. , Sunu Christine , Spana Eric P. , York John D.
Published: December 2015

Significance

Inositol phosphate kinase 2 (Ipk2) is a conserved protein that initiates the production of inositol phosphate intracellular messengers that are critical for regulating a variety of cellular processes. Here we explore the developmental roles Ipk2 and its products in
Drosophila
. We report that Ipk2 kinase activity is required to develop adult body structures including eyes, legs, and wings, which are formed by tissue known as imaginal discs. Although Ipk2 mutant discs seem to pattern normally in embryogenesis, during larval development they fail to undergo normal expansion. We find defects in signaling pathways that control both cell death and proliferation. Our work demonstrates a specific role for Ipk2-produced intracellular messengers in regulating developmental pathways involved in tissue growth and stability.
Probing nonlinear rheology layer-by-layer in interfacial hydration water
Authors: Kim Bongsu , Kwon Soyoung , Lee Manhee , Kim QHwan , An Sangmin , Jhe Wonho
Published: December 2015

Significance

The hydration water layer (HWL) is a ubiquitous form of nanoscale water bound to the hydrophilic surfaces and plays a critical role in diverse phenomena in nature. Especially, investigation of its nonlinear fluidic properties is important for better understanding of its rheological contributions at a microscopic level. Using precise control and sensitive detection of HWL, we observe shear thickening at above a critical shear-strain rate of 10
6
s
−1
, resulting from the interplay between relaxation and elasticity-induced fluctuation correlation. Interestingly, the results indicate the occurrence of elasticity turbulence above a universal shear velocity of ∼ 1 mm/s. This work not only furthers our understanding of nonlinear nanorheology but is a stepping-stone toward controlled experiments on the nonlinear fluid dynamics near the interface.
Predicting experimentally stable allotropes: Instability of penta-graphene
Authors: Ewels Christopher P. , Rocquefelte Xavier , Kroto Harold W. , Rayson Mark J. , Briddon Patrick R. , Heggie Malcolm I.
Published: December 2015

Significance

We describe criteria that should be applied when evaluating whether theoretically proposed carbon allotropes may be experimentally isolated. We discuss the importance of energetic isomeric “funnels” centered on a stable allotropic form, the role of defects in catalyzing structural transformations to lower energy isomers, and chemical stability. This is demonstrated with literature examples such as C60 and B80. We apply these criteria to a recently proposed carbon allotrope, penta-graphene, demonstrating with the aid of density functional calculations that it will not be experimentally attainable. A second example, Haeckelites, are unlikely to be experimentally achievable when neutral but may be stabilized through significant charge transfer. The principals discussed here are general and can be applied to any theoretically proposed materials.
MHC-mismatched mixed chimerism augments thymic regulatory T-cell production and prevents relapse of EAE in mice
Authors: Wu Limin , Li Nainong , Zhang Mingfeng , Xue Sheng-Li , Cassady Kaniel , Lin Qing , Riggs Arthur D. , Zeng Defu
Published: December 2015

Significance

Induction of MHC- or HLA-matched mixed chimerism does not cause graft-versus-host disease (GVHD) in animal models or humans, but matched mixed chimerism cannot reverse autoimmunity. MHC-mismatched mixed chimerism is required for reversal of autoimmunity. Here, we report that, using a clinically applicable conditioning regimen consisting of cyclophosphamide, pentostatin, and antithymocyte globulin, MHC-mismatched mixed chimerism is established in experimental autoimmune encephalomyelitis (EAE) mice without any signs of GVHD. The mismatched mixed chimerism reverses autoimmunity, augments myelin sheath regeneration, prevents EAE relapse, and cures the disease. The cure of EAE is associated with thymic deletion of host-type autoreactive T cells and increase of thymic production of host-type Foxp3
+
Treg cells. Thus, induction of HLA-mismatched mixed chimerism can be a curative therapy for progressive MS.
TMEM110 regulates the maintenance and remodeling of mammalian ER–plasma membrane junctions competent for STIM–ORAI signaling
Authors: Quintana Ariel , Rajanikanth Vangipurapu , Farber-Katz Suzette , Gudlur Aparna , Zhang Chen , Jing Ji , Zhou Yubin , Rao Anjana , Hogan Patrick G.
Published: December 2015

Significance

Close appositions between the endoplasmic reticulum (ER) and the plasma membrane in mammalian cells have essential roles in cellular lipid metabolism and in cytoplasmic calcium signaling. Although recent investigations have yielded considerable insight into the structural basis for lipid transfer at ER–plasma membrane junctions, little is known about the proteins that organize junctions for calcium signaling. Our data show that the ER membrane protein transmembrane protein 110 (TMEM110) supports the maintenance of ER–plasma membrane junctions competent for calcium signaling and acts in concert with other proteins in the dynamic remodeling of the junctions during signaling.
Antiinfectives targeting enzymes and the proton motive force
Authors: Feng Xinxin , Zhu Wei , Schurig-Briccio Lici A. , Lindert Steffen , Shoen Carolyn , Hitchings Reese , Li Jikun , Wang Yang , Baig Noman , Zhou Tianhui , Kim Boo Kyung , Crick Dean C. , Cynamon Michael , McCammon J. Andrew , Gennis Robert B. , Oldfield Eric
Published: December 2015

Significance

Uncoupling agents might be expected to be generally cytotoxic, but many US Food and Drug Administration (FDA)-approved drugs do have activity as uncouplers, in addition to targeting enzymes. There is therefore interest in the discovery of antibiotics that have such multitarget activity. Here, we show that some FDA-approved drugs, such as clofazimine, clomiphene, and bedaquiline, with antiinfective activity act as uncouplers. Using molecular dynamics-based in silico screening, we also discovered that the brain cancer drug lead vacquinol is an uncoupler that inhibits an enzyme involved in the formation of tuberculosis (TB) virulence factors, in addition to killing TB bacteria. Our results indicate strong drug–membrane interactions, and that screening for combined enzyme inhibition plus uncoupler activity will lead to new antibiotic leads.
Reconciling divergent estimates of oil and gas methane emissions
Authors: Zavala-Araiza Daniel , Lyon David R. , Alvarez Ramón A. , Davis Kenneth J. , Harriss Robert , Herndon Scott C. , Karion Anna , Kort Eric Adam , Lamb Brian K. , Lan Xin , Marchese Anthony J. , Pacala Stephen W. , Robinson Allen L. , Shepson Paul B. , Sweeney Colm , Talbot Robert , Townsend-Small Amy , Yacovitch Tara I. , Zimmerle Daniel J. , Hamburg Steven P.
Published: December 2015

Significance

Past studies reporting divergent estimates of methane emissions from the natural gas supply chain have generated conflicting claims about the full greenhouse gas footprint of natural gas. Top-down estimates based on large-scale atmospheric sampling often exceed bottom-up estimates based on source-based emission inventories. In this work, we reconcile top-down and bottom-up methane emissions estimates in one of the country’s major natural gas production basins using easily replicable measurement and data integration techniques. These convergent emissions estimates provide greater confidence that we can accurately characterize the sources of emissions, including the large impact that a small proportion of high-emitters have on total emissions and determine the implications for mitigation.
Improved Models for Predicting Walleye Abundance and Setting Safe Harvest Quotas in Northern Wisconsin Lakes
Authors: Hansen Gretchen J. A. , Hennessy Joseph M. , Cichosz Thomas A. , Hewett Steven W.
Published: December 2015

In Wisconsin, the management of Walleyes Sander vitreus relies on a set of log-linear regressions to predict Walleye abundance and to set safe harvest. The regression models predict mean Walleye abundance from lake area, but they ignore variability among years; they also predict equal Walleye populations in lakes with the same size and recruitment source. We evaluated three alternative models in terms of predictive accuracy and the risk of overharvest. We used 899 mark–recapture population estimates (collected between 1953 and 2013) from 219 lakes to develop and evaluate (1) a log-linear mixed-effects model that used all individual observations and estimated adult Walleye abundance from lake area and lake-specific deviations from the overall intercept; (2) a mixed-effects model that builds on model 1 by adding a linear fixed effect of sampling year; and (3) a mixed-effects model that builds on model 1 by adding a random year effect. Walleye abundance was positively correlated with lake area in all models and was negatively correlated with sampling year (when included). Alternative models improved predictive accuracy by 17–22% over the current regression model. Restricting data to those collected during the most recent 20 years improved model responsiveness to new data and reduced the value of including a linear time trend. When all data were used for model construction, the relative risk of overharvest was lowest under the mixed-effects model with a linear time trend; when the most recent 20 years of data were used, the risk was lowest under the mixed-effects model with a random year effect. Accounting for variability among years would allow harvest to track changing Walleye populations and would allow management to be more adaptive. We recommend using the mixed-effects model with a random year effect and restricting the data inputs to the most recent 20 years.

Received May 20, 2015; accepted September 17, 2015
Identifying Aggression in Forensic Inpatients Using the MMPI-2-RF: An Examination of MMPI-2-RF Scale Scores and Estimated Psychopathy Indices
Authors: Grossi Laura M. , Green Debbie , Belfi Brian , McGrath Robert E. , Griswold Hali , Schreiber Jeremy
Published: December 2015

Prior research has examined the relationship between personality characteristics and problematic behaviors, suggesting the utility of self-report personality measures in assessing risk of aggression. This study examined the relationship between select Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF) scales and estimated psychopathy indices derived from MMPI-2-RF scales, and institutional aggression among hospitalized pre-trial defendants. Scores on Thought Dysfunction (THD), Aberrant Experiences, Juvenile Conduct Problems, and Psychoticism-Revised (PSYC-r) were associated with mild-severe aggression. Similarly, THD and PSYC-r were associated with moderate-severe aggression. Regarding psychopathy, impulsive-antisociality, but not fearless-dominance, was associated with both aggressive outcomes. Overall, the relevant MMPI-2-RF scales demonstrated higher classification accuracy than the estimated psychopathy indices.
A National Survey of United States Sexually Violent Person Legislation: Policy, Procedures, and Practice
Authors: DeMatteo David , Murphy Megan , Galloway Meghann , Krauss Daniel A.
Published: December 2015

Sexually Violent Person (SVP) commitment statutes provide for indeterminate civil confinement of certain sex offenders after completion of their criminal sentences. In the United States, SVP laws raise important concerns relating to due process, ex post facto claims, and protection against double jeopardy. However, it is unclear to what extent current legislation addresses or neglects these issues. Without a systematic review of SVP legislation and related case law, it remains unknown to what degree U.S. states have incorporated different strategies to protect individual rights outlined by the U.S. Supreme Court. In this study, SVP statutes from each U.S. state, the federal government, and the District of Columbia, along with related case law, were examined to evaluate (1) the requirements of SVP confinement, (2) the procedures by which SVP hearings occur, and (3) the degree to which the requirements enumerated by the U.S. Supreme Court have been followed. Although nearly half of all states have SVP statutes, findings reveal that statutes differ considerably regarding standards of proof, commitment procedures, appeals standards, definitions of important terms, and procedural safeguards. Moreover, case law provides important information on how SVP laws actually operate. Findings are discussed in light of psychological, legal, and policy implications.
Drug Side Effect Symptoms and Adherence to Antihypertensive
Medication
Authors: Tedla Yacob G. , Bautista Leonelo E.
Published: December 2015

BACKGROUND

Non-adherence to antihypertensive medication increases the risk of uncontrolled hypertension. Antihypertensive drug-related symptoms (side effects) are frequently cited as a main cause of non-adherence, but with little support from prospective studies. We evaluated the association between drug side effects and prospective adherence to treatment.

METHODS

We collected data on the number and dose of antihypertensive drugs at enrollment and at 3, 6, 9, and 12 months of follow-up in a cohort of 175 hypertensive patients starting or restarting antihypertensive treatment (mean age: 50 years; 58% women). During the follow-up visits, we gathered data on 24 side effects during the last month and the pill count adherence ratio (PCAR = pills taken out of number prescribed × 100) since the previous visit. The association between side effects at a visit and adherence through the next visit was estimated using mixed effect models.

RESULTS

Eighty-five percent of the participants experienced side effects, and 34.5% became non-adherent (PCAR <80%). After adjusting for confounders, PCAR was 6.0 percentage points lower ( P = 0.04) among individuals with number of side effects above the median value (4 symptoms). Also, in individuals with genitourinary side effects, PCAR was 7.1 percentage points lower ( P = 0.02) than in those without such side effects. Specifically, PCAR was 6.5 ( P = 0.06) and 7.6 ( P = 0.01) percentage points lower among individuals with excessive urination and decrease in sexual drive, respectively.

CONCLUSION

Antihypertensive drug side effects was associated with drug adherence but only excessive urination and decrease in sexual drive significantly predicted lower adherence. These symptoms could be used as markers to screen out patients at high risk of non-adherence.