bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-energy electro- and photo-emission spectroscopy of GaN materials and devices
Authors: Piccardo Marco , Iveland Justin , Martinelli Lucio , Nakamura Shuji , Choi Joo Won , Speck James S. , Weisbuch Claude , Peretti Jacques
Published: March 2015

In hot-electron semiconductor devices, carrier transport extends over a wide range of conduction states, which often includes multiple satellite valleys. Electrical measurements can hardly give access to the transport processes over such a wide range without resorting to models and simulations. An alternative experimental approach however exists which is based on low-energy electron spectroscopy and provides, in a number of cases, very direct and selective information on hot-electron transport mechanisms. Recent results obtained in GaN crystals and devices by electron emission spectroscopy are discussed. Using near-band-gap photoemission, the energy position of the first satellite valley in wurtzite GaN is directly determined. By electro-emission spectroscopy, we show that the measurement of the electron spectrum emitted from a GaN p-n junction and InGaN/GaN light-emitting diodes (LEDs) under electrical injection of carriers provides a direct observation of transport processes in these devices. In particular, at high injected current density, high-energy features appear in the electro-emission spectrum of the LEDs showing that Auger electrons are being generated in the active region. These measurements allow us identifying the microscopic mechanism responsible for droop which represents a major hurdle for widespread adoption of solid-state lighting.
Robustness of a new molecular dynamics–finite element coupling approach for soft matter systems analyzed by uncertainty quantification
Authors: Liu Shengyuan , Gerisch Alf , Rahimi Mohammad , Lang Jens , Böhm Michael C. , Müller-Plathe Florian
Published: March 2015

Key parameters of a recently developed coarse-grained molecular dynamics-finite element coupling approach have been analyzed in the framework of uncertainty quantification (UQ). We have employed a polystyrene sample for the case study. The new hybrid approach contains several parameters which cannot be determined on the basis of simple physical arguments. Among others, this includes the so-called anchor points as information transmitters between the particle-based molecular dynamics (MD) domain and the surrounding finite element continuum, the force constant between polymer beads and anchor points, the number of anchor points, and the relative sizes of the MD core domain and the surrounding dissipative particle dynamics domain. Polymer properties such as density, radius of gyration, end-to-end distance, and radial distribution functions are calculated as a function of the above model parameters. The influence of these input parameters on the resulting polymer properties is studied by UQ. Our analysis shows that the hybrid method is highly robust. The variation of polymer properties of interest as a function of the input parameters is weak.
Simulated evolution of fluorophores for light emitting diodes
Authors: Shu Yinan , Levine Benjamin G.
Published: March 2015

Organic light emitting diodes based on fluorophores with a propensity for thermally activated delayed fluorescence (TADF) are able to circumvent limitations imposed on device efficiency by spin statistics. Molecules with a propensity for TADF necessarily have two properties: a small gap between the lowest lying singlet and triplet excited states and a large transition dipole moment for fluorescence. In this work, we demonstrate the use of a genetic algorithm to search a region of chemical space for molecules with these properties. This algorithm is based on a flexible and intuitive representation of the molecule as a tree data structure, in which the nodes correspond to molecular fragments. Our implementation takes advantage of hybrid parallel graphics processing unit accelerated computer clusters to allow efficient sampling while retaining a reasonably accurate description of the electronic structure (in this case, CAM-B3LYP/6-31G∗∗). In total, we have identified 3792 promising candidate fluorophores from a chemical space containing 1.26 × 106 molecules. This required performing electronic structure calculations on only 7518 molecules, a small fraction of the full space. Several novel classes of molecules which show promise as fluorophores are presented.
Thermally induced nonlinear optical absorption in metamaterial perfect absorbers
Authors: Guddala Sriram , Kumar Raghwendra , Ramakrishna S. Anantha
Published: March 2015

A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.
Molecular dynamics simulations of shock compressed heterogeneous materials. I. The porous case
Authors: Soulard L. , Pineau N. , Clérouin J. , Colombet L.
Published: March 2015

The propagation of an incident shock and subsequent rarefaction and compression waves in a porous media are analysed from a set of large scale molecular dynamics simulations. The porous material is modelized by a collection of spherical pores, empty or filled with dense gaseous argon, enclosed in a copper matrix. We observe that the pore collapse induces a strong local disorder in the matrix even for shock intensities below the melting point of shocked copper. Various mechanisms are considered and a detailed analysis of the numerical results shows that the melting around an isolated pore is mainly due to the plastic work induced by the collapse: a result that can be extended to more complicated pore shapes. The systematic study of the influence of the shock intensity, the pore size, and the presence of a filling gas shows that the melting is mainly inhibited by the presence of the gas. The final structure strongly depends on the interactions between the waves resulting from the various reflections of the initial shock at the sample boundaries, implying that the evaluation of the incident shock intensity based on post-mortem analyses requires a knowledge of the full history of the sample.
Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons
Authors: Zhang Cheng , Tarasenko Viktor F. , Shao Tao , Beloplotov Dmitry V. , Lomaev Mikhail I. , Wang Ruixue , Sorokin Dmitry A. , Yan Ping
Published: March 2015

Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front.
Superparamagnetic properties of carbon nanotubes filled with NiFe2O4 nanoparticles
Authors: Stojak Repa K. , Israel D. , Alonso J. , Phan M. H. , Palmero E. M. , Vazquez M. , Srikanth H.
Published: March 2015

Multi walled carbon nanotubes (MWCNTs) were successfully synthesized using custom-made 80 nm pore-size alumina templates, and were uniformly filled with nickel ferrite (NFO) nanoparticles of 7.4 ± 1.7 nm diameter using a novel magnetically assisted capillary action method. X-ray diffraction confirmed the inverse spinel phase for the synthesized NFO. Transmission electron microscopy confirms spherical NFO nanoparticles with an average diameter of 7.4 nm inside MWCNTs. Magnetometry indicates that both NFO and NFO-filled MWCNTs present a blocking temperature around 52 K, with similar superparamagnetic-like behavior, and weak dipolar interactions, giving rise to a super-spin-glass-like behavior at low temperatures. These properties along with the uniformity of sub-100 nm structures and the possibility of tunable magnetic response in variable diameter carbon nanotubes make them ideal for advanced biomedical and microwave applications.
Two-dimensional X-ray diffraction and transmission electron microscopy study on the effect of magnetron sputtering atmosphere on GaN/SiC interface and gallium nitride thin film crystal structure
Authors: Shen Huaxiang , Zhu Guo-Zhen , Botton Gianluigi A. , Kitai Adrian
Published: March 2015

The growth mechanisms of high quality GaN thin films on 6H-SiC by sputtering were investigated by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The XRD θ-2θ scans show that high quality (0002) oriented GaN was deposited on 6H-SiC by reactive magnetron sputtering. Pole figures obtained by 2D-XRD clarify that GaN thin films are dominated by (0002) oriented wurtzite GaN and {111} oriented zinc-blende GaN. A thin amorphous silicon oxide layer on SiC surfaces observed by STEM plays a critical role in terms of the orientation information transfer from the substrate to the GaN epilayer. The addition of H2 into Ar and/or N2 during sputtering can reduce the thickness of the amorphous layer. Moreover, adding 5% H2 into Ar can facilitate a phase transformation from amorphous to crystalline in the silicon oxide layer and eliminate the unwanted {33¯02} orientation in the GaN thin film. Fiber texture GaN thin films can be grown by adding 10% H2 into N2 due to the complex reaction between H2 and N2.
Structural and electronic response of U3Fe4Ge4 to high pressure
Authors: Henriques M. S. , Gorbunov D. I. , Andreev A. V. , Prchal J. , Raison P. , Heathman S. , Arnold Z. , Griveau J.-C. , Colineau E. , Havela L. , Gonçalves A. P.
Published: March 2015

Structural, magnetic, and electrical properties have been studied on a U3Fe4Ge4 single crystal under hydrostatic pressure. The orthorhombic crystal structure is found to be stable up to 30 GPa, the highest applied pressure, but the compressibility is strongly anisotropic. Contrary to typical uranium intermetallics for which the softest lattice direction is along the shortest inter-uranium links, in U3Fe4Ge4 the lattice is compressed most in a perpendicular direction for the high pressure range. The elastic properties are modified considerably in the vicinity of 1 GPa when the b axis is transformed from least compressible to most compressible. The bulk modulus is found to be about 150 GPa. The anomalies in the elastic properties are reflected in the electronic properties that consistently indicate a change of the magnetic ground state from ferromagnetic to antiferromagnetic. Both types of order exhibit a gap in the magnon spectrum; however, it is twice as high for the ferromagnetic state. The magnetoresistance reveals field-induced transitions of different origins in the antiferromagnetic state along the easy and hard magnetization directions.
GaSb thermophotovoltaic cells grown on GaAs by molecular beam epitaxy using interfacial misfit arrays
Authors: Juang Bor-Chau , Laghumavarapu Ramesh B. , Foggo Brandon J. , Simmonds Paul J. , Lin Andrew , Liang Baolai , Huffaker Diana L.
Published: March 2015

There exists a long-term need for foreign substrates on which to grow GaSb-based optoelectronic devices. We address this need by using interfacial misfit arrays to grow GaSb-based thermophotovoltaic cells directly on GaAs (001) substrates and demonstrate promising performance. We compare these cells to control devices grown on GaSb substrates to assess device properties and material quality. The room temperature dark current densities show similar characteristics for both cells on GaAs and on GaSb. Under solar simulation the cells on GaAs exhibit an open-circuit voltage of 0.121 V and a short-circuit current density of 15.5 mA/cm2. In addition, the cells on GaAs substrates maintain 10% difference in spectral response to those of the control cells over a large range of wavelengths. While the cells on GaSb substrates in general offer better performance than the cells on GaAs substrates, the cost-savings and scalability offered by GaAs substrates could potentially outweigh the reduction in performance. By further optimizing GaSb buffer growth on GaAs substrates, Sb-based compound semiconductors grown on GaAs substrates with similar performance to devices grown directly on GaSb substrates could be realized.
Alignment engineering in liquid crystalline elastomers: Free-form microstructures with multiple functionalities
Authors: Zeng Hao , Wasylczyk Piotr , Cerretti Giacomo , Martella Daniele , Parmeggiani Camilla , Wiersma Diederik S.
Published: March 2015

We report a method to fabricate polymer microstructures with local control over the molecular orientation. Alignment control is achieved on molecular level in a structure of arbitrary form that can be from 1 to 100 μm in size, by fixing the local boundary conditions with micro-grating patterns. The method makes use of two-photon polymerization (Direct Laser Writing) and is demonstrated specifically in liquid-crystalline elastomers. This concept allows for the realization of free-form polymeric structures with multiple functionalities which are not possible to realize with existing techniques and which can be locally controlled by light in the micrometer scale.
Tunable thermoelectric transport in nanomeshes via elastic strain engineering
Authors: Piccione Brian , Gianola Daniel S.
Published: March 2015

Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermal management.
Thermionic cooling with functionalized carbon nanotube thin films
Authors: Jin Feng , Little Scott
Published: March 2015

A large thermionic cooling effect is reported. Temperature reduction as much as 81 °C has been observed on a functionalized carbon nanotubes (CNTs) cathode surface. This cathode utilizes a thin coating of low work function barium strontium oxide emissive materials on top of the CNTs to lower the surface work function. This, combined with the field effect induced by the CNTs, results in an even lower effective work function, and thus strong thermionic emission. Strong thermionic emission is the underlying reason for the large cooling effect observed, and the largest emission current in this study is around 160 mA on a 0.0727 cm2 emitting surface at around 995 °C. Multiple samples were used in studying thermionic mission at cathode temperature ranging between 750 °C and 1100 °C, and in establishing correlation between the cooling effect and the emission current. Details of the cooling effect measurement are provided, and the measurement results show a clear linear dependence of temperature drop on thermionic emission current. The possible implication of this linear dependence is also discussed.
Electric-field dependent conduction mechanisms in crystalline chromia
Authors: Kwan C.-P. , Chen R. , Singisetti U. , Bird J. P.
Published: March 2015

We investigate mechanisms of electric-field-induced conduction in high-quality chromia crystals. A crossover is observed between space-charge limited conduction and the Frenkel-Poole mechanism with increasing temperature, with the crossover occurring in the vicinity of the Neel temperature of this material. From an analysis of the Frenkel-Poole conduction, we infer the presence of charge traps that lie approximately 0.5 eV below the conduction-band edge. Our experiments confirm the excellent dielectric properties of chromia, a result that is important for attempts to utilize this material as a “gate” dielectric in future spintronic devices.
Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance
Authors: Li Hai-ming , Liu Shao-bin , Liu Si-yuan , Wang Shen-yun , Zhang Hai-feng , Bian Bo-rui , Kong Xiang-kun
Published: March 2015

In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.
A scalable pathway to nanostructured sapphire optical fiber for evanescent-field sensing and beyond
Authors: Chen Hui , Tian Fei , Kanka Jiri , Du Henry
Published: March 2015

We here report an innovative and scalable strategy of transforming a commercial unclad sapphire optical fiber to an all-alumina nanostructured sapphire optical fiber (NSOF). The strategy entails fiber coating with metal aluminum followed by anodization to form alumina cladding of highly organized pore channel structure. Through experiments and numerical simulation, we demonstrate the utility and benefit of NSOF, analogous to all-silica microstructured optical fiber, for evanescent-field surface-enhanced Raman scattering (SERS) measurements. We experimentally reveal the feasibility of Ag nanoparticles (NPs)-enabled NSOF SERS sensing of 10−6 M Rhodamine 6G (R6G) after thermal treatment at 500 °C for 6 h by taking advantage of porous anodic aluminum oxide (AAO) structure to stabilize the Ag NPs. We show, via numerical simulations, that AAO cladding significantly increases the evanescent-field overlap, lower porosity of AAO results in higher evanescent-field overlap, and optimized AAO nanostructure yields greater SERS enhancement.
High efficiency n-type silicon solar cells featuring passivated contact to laser doped regions
Authors: Yang Xinbo , Bullock James , Bi Qunyu , Weber Klaus
Published: March 2015

Minimizing carrier recombination at cell contacts becomes increasingly important for reaching high efficiency. In this work, the passivated contact concept is implemented into n-type silicon solar cells with laser-processed local back surface fields. The passivation and contact characteristics of the SiO2/amorphous silicon (a-Si:H) stack on localized laser doped n+ regions are investigated. We find that the SiO2/a-Si:H stack provides not only good passivation to laser doped n+ regions but also allows a low contact resistivity after thermal annealing. With the implementation of the SiO2/a-Si:H passivated contact, an absolute efficiency gain of up to 1.5% is achieved for n-type solar cells.
Ultraviolet Source Assisted Enhancement of Attosecond Pulse
Authors: Feng Li-qiang , Liu Hang
Published: March 2015

A promising method to improve the attosecond pulse intensity has been theoretically presented by properly adding an ultraviolet pulse into the orthogonal two-color field. The results show that by properly adding a 125 nm ultraviolet pulse to the orthogonal two-color field, not only the harmonic yield is enhanced by 2 orders of magnitude compared with the original orthogonal two-color field case, but also the single short quantum path, which is selected to contribute to the harmonic spectrum, results in an ultrabroad 152 eV bandwidth. Moreover, by optimizing the laser parameters, we find that the harmonic enhancement is not very sensitive to the pulse duration and the polarized angle of the assisted ultraviolet pulse, which is much better for experimental realization. As a result, an isolated pulse with duration of 38 as can be obtained, which is 2 orders of magnitude improvement in comparison with the original two-color orthogonal field case.
A Highly Stable Electrochemical Scanning Tunneling Microscope
Authors: Xia Zhigang , Wang Jihao , Hou Yubin , Lu Qingyou
Published: March 2015

We demonstrate a home-built electrochemical scanning tunneling microscope (ECSTM). The ECSTM exhibits highly stable performance. The drifting rates in XY and Z directions of the ECSTM are about 67 and 55.6 pm/min, respectively. Moreover, a specially designed scanner unit successfully solves the well-known problem of large leakage current in high humidity atmosphere. The mechanical structure of the ECSTM is described in detail. The excellent performances of the system are demonstrated by the measured STM images (in copper sulfate solution), including clean and well-ordered large area morphology of Au(111) and the atomically resolved image of highly oriented pyrolytic graphite.
High Performance of Enhanced Mode Field Effect Transistor and Ultraviolet Sensor Based on ZnO Nanosheet
Authors: Gao Zhi-wei , Wu Yu-kun , Li Jun-wen , Wang Xiao-ping
Published: March 2015

ZnO nanosheets with thickness of a few nanometers are prepared by vapor transport and condensation method, and their structure and optical properties are well characterized. Field effect transistor (FET) and ultraviolet (UV) sensors are fabricated based on the ZnO nanosheets. Due to the peculiar structure of nanosheet, the FET shows n-type enhanced mode behavior and high electrical performance, and its field-effect mobility and on/off current ratio can reach 256 cm2/(V·s) and ∼108, respectively. Moreover, the response of UV sensors can also be remarkably improved to ∼3×108. The results make the ZnO nanosheets be a good material for the applications in nanoelectronic and optoelectronic devices.
Leaf green-white variegation is advantageous under N deprivation in Pelargonium×hortorum
Authors: Abadie Cyril , Lamothe Marlène , Mauve Caroline , Gilard Françoise , Tcherkez Guillaume
Published: March 2015

Variegation (patchy surface area with different colours) is a common trait of plant leaves. In green-white variegated leaves, two tissues with contrasted primary carbon metabolisms (autotrophic in green and heterotrophic in white tissues) are juxtaposed. It is generally believed that variegation is detrimental to growth due to the lower photosynthetic surface area. However, the common occurrence of leaf variegation in nature raises the question of a possible advantage under certain circumstances. Here, we examined growth and metabolism of variegated Pelargonium × hortorum L.H.Bailey using metabolomics techniques under N deprivation. Our results showed that variegated plants tolerate N deficiency much better, i.e. do not stop leaf biomass production after 9 weeks of N deprivation, even though the growth of green plants is eventually arrested and leaf senescence is triggered. Metabolic analysis indicates that white areas are naturally enriched in arginine, which decreases a lot upon N deprivation, probably to feed green areas. This process may compensate for the lower proteolysis enhancement in green areas and thus contribute to maintaining photosynthetic activity. We conclude that under our experimental conditions, leaf variegation was advantageous under prolonged N deprivation.
Fuel flammability and fire responses of juvenile canopy species in a temperate rainforest ecosystem
Authors: Zimmer Heidi C. , Auld Tony D. , Hughes Lesley , Offord Catherine A. , Baker Patrick J.
Published: March 2015

Historically, rainforests have been considered vulnerable to fire. Recent research, however, has shown that many rainforest species can survive fire by resisting burning and by resprouting and seeding post-fire. We investigated the response of a warm temperate rainforest community to fire by burning juveniles of the dominant canopy tree species (Doryphora sassafras, Syzygium smithii and Wollemia nobilis) and examining litter flammability in a controlled environment. The three species resprouted after the experimental burn, predominantly from buds on the stem that were below the soil surface. Higher fire temperatures resulted in reduced overall plant height and resprouting from buds lower on the stem. Increasing proportions of W. nobilis litter generated fires with higher intensities and fuel consumption compared with rainforest angiosperm litter. Moreover, fuel moisture content decreased with increasing W. nobilis litter proportions. Higher litter flammability may result in increased likelihood of fire ignition and fire severity near W. nobilis trees, which would negatively impact the juveniles of all three rainforest species. Alternatively, after lower-temperature fires (e.g. in rainforest angiosperm litter), W. nobilis may have an advantage over the other species because of faster-growing resprouts occurring higher on the stem.
The endoparasites of Liasis fuscus (Serpentes : Boidae) from the Adelaide River floodplain, Northern Territory, Australia
Authors: Mulder E. , Smales L. R.
Published: March 2015

This study documents the parasite assemblage of Liasis fuscus Peters, 1873 from the Adelaide River flood plain, Northern Territory, Australia. In total, nine species of helminth (comprising three cestodes and six nematodes), one pentastome and one protozoan were found in 180 water pythons, with the Nematoda being the dominant and most diverse group, and a cestode, Bothridium ornatum Maplestone & Southwell, 1923, the most prevalent species. In spite of the hosts being present in high numbers the helminth assemblage was depauperate, characterised by low prevalence, intensity, frequency and abundance of species, with neither season nor sex of host affecting abundance. There were, however, significant differences between ages of hosts, juveniles having fewer parasites, and seasonal diversity, with the wet season of 2004 and the dry of 2005 the most similar. Of the Australian python species analysed Morelia spilota (Lacépède, 1804) had the highest species richness. The lower species richness found in L. fuscus was possibly due to its unusual biology. Biogeographic relationships of the parasite fauna of L. fuscus are diverse, connections with Africa, Asia, and South America being noted.
The ghost of essentialism and the trap of binarism: six theses on the Soviet empire
Authors: Annus Epp
Published: March 2015

This article endeavors to open a new critical space for Soviet studies and for nationalities studies more generally. Through analyses of recent trends in Soviet studies, the article dismantles the frequently used opposition between subjective and objective approaches to Soviet empire and suggests instead that truths and categories, whether considered “subjective” or “objective,” are constructed discursively, through legitimizing certain interpretive models over the others. The article also argues against disciplinary avoidance of “what is” questions (e.g. “what is a nation?”) and claims that an excessive concern for (re)producing essentialism should not hinder scholarly inquiry. Several new lines of inquiry for the study of the Soviet empire are suggested and also applicable in nationalities studies more generally: research on the role of symbolic violence in manufacturing consent and research concerning the role of affect in producing linkages between the performative life of a singular human being and the pedagogical discourse of a nation or empire. The article also offers an analysis of the Soviet Union as an empire in becoming and it advocates for postcolonial approaches within Soviet studies. The practical dimensions of Soviet rule are exemplified with data from the Baltic borderlands in the postwar years.
Cost-Effectiveness of Injectable Extended-Release Naltrexone Compared with Methadone Maintenance and Buprenorphine Maintenance Treatment for Opioid Dependence
Authors: Jackson Heide , Mandell Kara , Johnson Kimberly , Chatterjee Debanjana , Vanness David J.
Published: March 2015

Background

The aim of this study was to estimate the cost-effectiveness of injectable extended-release naltrexone (XR-NTX) compared with methadone maintenance and buprenorphine maintenance treatment (MMT and BMT, respectively) for adult males enrolled in treatment for opioid dependence in the United States from the perspective of state-level addiction treatment payers.

Methods

A Markov model with daily time cycles was used to estimate the incremental cost per opioid-free day in a simulated cohort of adult males aged 18–65 over a 6-month period from the state health program perspective.

Results

XR-NTX is predicted to be more effective and more costly than methadone or buprenorphine in our target population, with an incremental cost per opioid-free day gained relative to the next-most effective treatment (MMT) of $72. The cost-effectiveness of XR-NTX relative to MMT was driven by its effectiveness in deterring opioid use while receiving treatment.

Conclusions

XR-NTX is a cost-effective medication for treating opioid dependence if state addiction treatment payers are willing to pay at least $72 per opioid-free day.
A Review of Opioid Overdose Prevention and Naloxone Prescribing: Implications for Translating Community Programming into Clinical Practice
Authors: Mueller Shane R. , Walley Alexander Y. , Calcaterra Susan L. , Glanz Jason M. , Binswanger Ingrid A.
Published: March 2015

Background

As physicians have increased opioid prescribing, overdose deaths from pharmaceutical opioids have substantially increased in the United States. Naloxone hydrochloride (naloxone), an opioid antagonist, is the standard of care for treatment of opioid induced respiratory depression. Since 1996, community-based programs have offered overdose prevention education and distributed naloxone for bystander administration to people who use opioids, particularly heroin. There is growing interest in translating overdose education and naloxone distribution (OEND) into conventional medical settings for patients who are prescribed pharmaceutical opioids. For this review, we summarized and classified existing publications on overdose education and naloxone distribution to identify evidence of effectiveness and opportunities for translation into conventional medical settings.

Methods

For this review, we searched English language PubMed for articles on naloxone based on primary data collection from humans, including feasibility studies, program evaluations, surveys, qualitative studies, and studies comparing the effectiveness of different routes of naloxone administration. We also included cost-effectiveness studies.

Results

We identified 41 articles that represented 5 categories: evaluations of OEND programs, effects of OEND programs on experiences and attitudes of participants, willingness of medical providers to prescribe naloxone, comparisons of different routes of naloxone administration, and the cost-effectiveness of naloxone.

Conclusions

Existing research suggests that people who are at risk for overdose and other bystanders are willing and able to be trained to prevent overdoses and administer naloxone. Counseling patients about the risks of opioid overdose and prescribing naloxone is an emerging clinical practice that may reduce fatalities from overdose while enhancing the safe prescribing of opioids.
Adolescent Substance use Screening in Primary Care: Validity of Computer Self-Administered versus Clinician-Administered Screening
Authors: Harris Sion Kim , Knight John Rogers , Van Hook Shari , Sherritt Lon , Traci L. Brooks , Kulig John W. , Christina A. Nordt , Saitz Richard
Published: March 2015

Background

Computer self-administration may help busy pediatricians’ offices increase adolescent substance use screening rates efficiently and effectively, if proven to yield valid responses. The CRAFFT screening protocol for adolescents has demonstrated validity as an interview, but a computer self-entry approach needs validity testing. The aim of this study was to evaluate the criterion validity and time efficiency of a computerized adolescent substance use screening protocol implemented by self-administration or clinician-administration.

Methods

Twelve- to 17-year-old patients coming for routine care at 3 primary care clinics completed the computerized screen by both self-administration and clinician-administration during their visit. To account for order effects, we randomly assigned participants to self-administer the screen either before or after seeing their clinician. Both were conducted using a tablet computer and included identical items (any past-12-month use of tobacco, alcohol, drugs; past-3-month frequency of each; and 6 CRAFFT items). The criterion measure for substance use was the Timeline Follow-Back, and for alcohol/drug use disorder, the Adolescent Diagnostic Interview, both conducted by confidential research assistant interview after the visit. Tobacco dependence risk was assessed with the self-administered Hooked on Nicotine Checklist (HONC). Analyses accounted for the multisite cluster sampling design.

Results

Among 136 participants, mean age was 15.0 ± 1.5 years, 54% were girls, 53% were black or Hispanic, and 67% had ≥3 prior visits with their clinician. Twenty-seven percent reported any substance use (including tobacco) in the past 12 months, 7% met criteria for an alcohol or cannabis use disorder, and 4% were HONC positive. Sensitivity/specificity of the screener were high for detecting past-12-month use or disorder and did not differ between computer and clinician. Mean completion time was 49 seconds (95% confidence interval [CI]: 44–54) for computer and 74 seconds (95% CI: 68–87) for clinician (paired comparison, P < .001).

Conclusions

Substance use screening by computer self-entry is a valid and time-efficient alternative to clinician-administered screening.
Changes in Psychiatric Symptoms among Persons with Methamphetamine Dependence Predicts Changes in Severity of Drug Problems but Not Frequency of Use
Authors: Polcin Douglas L. , Korcha Rachael , Bond Jason , Galloway Gantt , Nayak Madhabika
Published: March 2015

Background

Few studies have examined how changes in psychiatric symptoms over time are associated with changes in drug use and severity of drug problems. No studies have examined these relationships among methamphetamine (MA)-dependent persons receiving motivational interviewing within the context of standard outpatient treatment.

Methods

Two hundred seventeen individuals with MA dependence were randomly assigned to a standard single session of motivational interviewing (MI) or an intensive 9-session model of MI. Both groups received standard outpatient group treatment. The Addiction Severity Index (ASI) and timeline follow-back (TLFB) for MA use were administered at treatment entry and 2-, 4-, and 6-month follow-ups.

Results

Changes in ASI psychiatric severity between baseline and 2 months predicted changes in ASI drug severity during the same time period, but not changes on measures of MA use. Item analysis of the ASI drug scale showed that psychiatric severity predicted how troubled or bothered participants were by their drug us, how important they felt it was for them to get treatment, and the number of days they experienced drug problems. However, it did not predict the number days they used drugs in the past 30 days. These associations did not differ between study conditions, and they persisted when psychiatric severity and outcomes were compared across 4- and 6-month time periods.

Conclusions

Results are among the first to track how changes in psychiatric severity over time are associated with changes in MA use and severity of drug problems. Treatment efforts targeting reduction of psychiatric symptoms among MA-dependent persons might be helpful in reducing the level of distress and problems associated with MA use but not how often it is used. There is a need for additional research describing the circumstances under which the experiences and perceptions of drug-related problems diverge from frequency of consumption.
Acceptability of Non-Abstinence Goals among Students Enrolled in Addiction Studies Programs across the United States
Authors: Davis Alan K. , Lauritsen Kirstin J.
Published: March 2015

Background

Previous studies of acceptability of non-abstinence recruited older, experienced addiction professionals; it's possible that younger, emerging addiction professionals may be more accepting of non-abstinence, perhaps due to training in harm reduction.

Methods

One hundred seventy graduate and undergraduate students enrolled in college/university-based programs offering training in addiction studies across the United States were recruited to complete a Web-based questionnaire assessing whether acceptability of non-abstinence outcome goals varied depending on the specific substance a client consumes, severity of diagnosis, and finality of outcome goal.

Results

More respondents rated non-abstinence an acceptable Intermediate goal for clients diagnosed with a Moderate cannabis use disorder (57%) or Moderate alcohol use disorder (45%) than for clients diagnosed with any other listed Moderate substance use disorder (32% to 36%). Similarly, larger proportions of respondents rated non-abstinence an acceptable Final goal for clients diagnosed with a Moderate cannabis use disorder (37%) or Moderate alcohol use disorder (31%) than for clients diagnosed with any other listed Moderate substance use disorder (19% to 23%). Only 14% to 26% of respondents rated non-abstinence an acceptable Final goal for clients diagnosed with a Severe substance use disorder, but 28% to 42% rated non-abstinence acceptable for clients diagnosed with a Severe substance use disorder when non-abstinence was an Intermediate goal.

Conclusions

Compared with previous research examining the acceptability of non-abstinence, these results suggest that students enrolled in addiction studies training programs may be more accepting of clients who decide to pursue non-abstinence either as an intermediate step on the way to abstinence or as a final goal.
Teachers’ engagement with published research: addressing the knowledge problema
Authors: Cain Tim
Published: March 2015

Despite the increased interest in research impact, there is very little empirical evidence that educational research can inform practice directly, and furthermore, a body of literature which suggests that this is, in principle, impossible. This paper reports on a study in which secondary school teachers were given research findings about teaching gifted and talented students, and were supported, over a 12‐month period, to incorporate findings into action research projects of their own devising. A theoretical framework from the research literature was used to investigate the process by which knowledge generated from research, was transformed into teachers’ pedagogical knowledge, thereby influencing the curriculum, pedagogy and provision for these students. Evidence suggests that teachers transformed propositional knowledge into practical knowledge by developing their conceptual understandings; they transformed abstract, impersonal knowledge into context‐specific, personal knowledge by using cases from their previous experiences, and they transformed narrowly focused knowledge into broadly focused knowledge by imaginatively diffusing it into areas beyond those in the original research. Implications for research and practice are discussed.
NORE1A is a Ras senescence effector that controls the apoptotic/senescent balance of p53 via HIPK2
Authors: Donninger Howard , Calvisi Diego F. , Barnoud Thibaut , Clark Jennifer , Schmidt M. Lee , Vos Michele D. , Clark Geoffrey J.
Published: March 2015

The Ras oncoprotein is a key driver of cancer. However, Ras also provokes senescence, which serves as a major barrier to Ras-driven transformation. Ras senescence pathways remain poorly characterized. NORE1A is a novel Ras effector that serves as a tumor suppressor. It is frequently inactivated in tumors. We show that NORE1A is a powerful Ras senescence effector and that down-regulation of NORE1A suppresses senescence induction by Ras and enhances Ras transformation. We show that Ras induces the formation of a complex between NORE1A and the kinase HIPK2, enhancing HIPK2 association with p53. HIPK2 is a tumor suppressor that can induce either proapoptotic or prosenescent posttranslational modifications of p53. NORE1A acts to suppress its proapoptotic phosphorylation of p53 but enhance its prosenescent acetylation of p53. Thus, we identify a major new Ras signaling pathway that links Ras to the control of specific protein acetylation and show how NORE1A allows Ras to qualitatively modify p53 function to promote senescence.
Hrr25/CK1δ-directed release of Ltv1 from pre-40S ribosomes is necessary for ribosome assembly and cell growth
Authors: Ghalei Homa , Schaub Franz X. , Doherty Joanne R. , Noguchi Yoshihiko , Roush William R. , Cleveland John L. , Stroupe M. Elizabeth , Karbstein Katrin
Published: March 2015

Casein kinase 1δ/ε (CK1δ/ε) and their yeast homologue Hrr25 are essential for cell growth. Further, CK1δ is overexpressed in several malignancies, and CK1δ inhibitors have shown promise in several preclinical animal studies. However, the substrates of Hrr25 and CK1δ/ε that are necessary for cell growth and survival are unknown. We show that Hrr25 is essential for ribosome assembly, where it phosphorylates the assembly factor Ltv1, which causes its release from nascent 40S subunits and allows subunit maturation. Hrr25 inactivation or expression of a nonphosphorylatable Ltv1 variant blocked Ltv1 release in vitro and in vivo, and prevented entry into the translation-like quality control cycle. Conversely, phosphomimetic Ltv1 variants rescued viability after Hrr25 depletion. Finally, Ltv1 knockdown in human breast cancer cells impaired apoptosis induced by CK1δ/ε inhibitors, establishing that the antiproliferative activity of these inhibitors is due, at least in part, to disruption of ribosome assembly. These findings validate the ribosome assembly pathway as a novel target for the development of anticancer therapeutics.
Adding complexity to the nuclear pore complex
Authors: Short Ben
Published: March 2015

Two studies describe how nucleoporins affect muscle differentiation and budding yeast lifespan.
A new two-component system modelling shallow-water waves
Authors: Ionescu-Kruse Delia
Published: March 2015

For propagation of surface shallow-water waves on irrotational flows, we derive a new two-component system. The system is obtained by a variational approach in the Lagrangian formalism. The system has a noncanonical Hamiltonian formulation. We also find its exact solitary-wave solutions.
Uniqueness of relaxation oscillations: A classical approach
Authors: Hastings S. , McLeod J.
Published: March 2015

In a recent paper (Kosiuk and Szmolyan (2011)), the authors discuss a relaxation oscillator which apparently has not been put in standard Lienard form. They use geometric perturbation theory to analyze this model. Their main result is the existence and uniqueness of a periodic solution for small values of two parameters,

δ
\delta

and

ε
,

\varepsilon ,

and the behavior of this solution as

δ
\delta

and

ε
\varepsilon

tend to zero. We show how standard ode methods can be used to give shorter and more direct proofs of these results. Along the way we give a new proof of a more general result.
Ancient Egypt
Authors: Lloyd Alan B.
Published: March 2015

This book attempts to define, analyse, and evaluate the institutional and ideological systems which empowered and sustained one of the most successful civilizations of the ancient world for a period in excess of three and a half millennia. The book adopts the premise that all societies are the product of a continuous dialogue with their physical context — understood in the broadest sense — and that, in order to achieve a successful symbiosis with this context, they develop an interlocking set of systems, defined by historians, archaeologists, and anthropologists as culture. Culture, therefore, can be described as the sum total of the methods employed by a group of human beings to achieve some measure of control over their environment. Covering the entirety of the civilization, including translations of original Egyptian texts, the book focuses on the main aspects of Egyptian culture which gave the society its particular character, and endeavours to establish what allowed the Egyptians to maintain that character for an extraordinary length of time, despite enduring cultural shock of many different kinds.
Dialogue and Transition
Authors: Lloyd Alan B.
Published: March 2015

The invasion of Egypt by Alexander the Great in 332 BC inaugurated a thousand years of intimate contact between the Egyptian and Classical worlds, both physical and conceptual, which led ultimately to the complete erosion of Pharaonic civilization and the transmutation of native Egyptian culture into something quite new. This process of cultural attrition is copiously documented and provides the clearest possible picture of the gradual, deadly abrasion of a great civilization to the point where nothing but vestigial remains were left. This chapter plots this process through the last two major periods of Egypt's ancient history: the Ptolemaic Period and Roman Egypt.
Introduction
Authors: Downs Jim
Published: March 2015

This book tells the story of hundreds of thousands of African Americans who, following their emancipation from slavery during and after the Civil War, encountered sickness, disease, suffering, and death. Basing its study on evidence from the records of the Medical Division of the Freedmen’s Bureau—a nascent national health system that cared for more than 500,000 freed slaves—the book recounts the plague of lethal diseases, including yellow fever, smallpox, cholera, and dysentery—not to mention malnutrition and poverty—that met former slaves as a result of the collapse of the plantation economy. It examines the deadly consequences of this biological crisis, the largest of the nineteenth century, and the untold misery and suffering it caused to innumerable people in their dash to freedom. It also looks at the Reconstruction policy that was then implemented in the American West and how it affected Native Americans.