bluuebunny/crossref_metadata_2025 huggingface dataset:
Proton decoupling and recoupling under double-nutation irradiation in solid-state NMR
Authors: Takeda Kazuyuki , Wakisaka Asato , Takegoshi K.
Published: December 2014

The effect of 1H decoupling in magic-angle spinning solid-state NMR is studied under radiofrequency irradiation causing simultaneous nutations around a pair of orthogonal axes. Double-nutation with an arbitrary pair of nutation frequencies is implemented through modulation of the amplitude, phase, and frequency of the transmitting pulses. Similarity and difference of double-nutation decoupling and two-pulse phase-modulation decoupling schemes [A. E. Bennett, C. M. Rienstra, M. Auger, K. V. Lakshmi, and R. G. Griffin, J. Chem. Phys. 103, 6951–6958 (1995) and I. Scholz, P. Hodgkinson, B. H. Meier, and M. Ernst, J. Chem. Phys. 130, 114510 (2009)] are discussed. The structure of recoupling bands caused by interference of the 1H spin nutation with sample spinning is studied by both experiments and numerical simulations.
Lagrangian approach to the physical degree of freedom count
Authors: Díaz Bogar , Higuita Daniel , Montesinos Merced
Published: December 2014

In this paper, we present a Lagrangian method that allows the physical degree of freedom count for any Lagrangian system without having to perform neither Dirac nor covariant canonical analyses. The essence of our method is to establish a map between the relevant Lagrangian parameters of the current approach and the Hamiltonian parameters that enter in the formula for the counting of the physical degrees of freedom as is given in Dirac’s method. Once the map is obtained, the usual Hamiltonian formula for the counting can be expressed in terms of Lagrangian parameters only, and therefore we can remain in the Lagrangian side without having to go to the Hamiltonian one. Using the map, it is also possible to count the number of first and second-class constraints within the Lagrangian formalism only. For the sake of completeness, the geometric structure underlying the current approach—developed for systems with a finite number of degrees of freedom—is uncovered with the help of the covariant canonical formalism. Finally, the method is illustrated in several examples, including the relativistic free particle.
Narrowing the error in electron correlation calculations by basis set re-hierarchization and use of the unified singlet and triplet electron-pair extrapolation scheme: Application to a test set of 106 systems
Authors: Varandas A. J. C. , Pansini F. N. N.
Published: December 2014

A method previously suggested to calculate the correlation energy at the complete one-electron basis set limit by reassignment of the basis hierarchical numbers and use of the unified singlet- and triplet-pair extrapolation scheme is applied to a test set of 106 systems, some with up to 48 electrons. The approach is utilized to obtain extrapolated correlation energies from raw values calculated with second-order Møller-Plesset perturbation theory and the coupled-cluster singles and doubles excitations method, some of the latter also with the perturbative triples corrections. The calculated correlation energies have also been used to predict atomization energies within an additive scheme. Good agreement is obtained with the best available estimates even when the (d, t) pair of hierarchical numbers is utilized to perform the extrapolations. This conceivably justifies that there is no strong reason to exclude double-zeta energies in extrapolations, especially if the basis is calibrated to comply with the theoretical model.
An improved self-alignment method for strapdown inertial navigation system based on gravitational apparent motion and dual-vector
Authors: Liu Xixiang , Zhao Yu , Liu Xianjun , Yang Yan , Song Qing , Liu Zhipeng
Published: December 2014

Analysis and simulation results indicate that two problems should be solved when the self-alignment method based on gravitational apparent motion and dual-vector can be used for Strapdown Inertial Navigation System. The first one is how to identify the apparent motion from accelerometer measurement containing random noise and the second is how to avoid the collinear problem between two vectors used in alignment solution. In this paper, a parameter identification and reconstruction algorithm is proposed to solve the first problem and simulation results indicate that proposed algorithm can identify apparent motion from accelerometer measurements effectively; and reconstruction algorithm based on current identified parameters for dual-vector is designed in detail to solve the second problem which can make full use of newest identification and avoid collinear problem completely. Simulation and turntable results show that the proposed alignment method can fulfill self-alignment in a swinging condition and the alignment accuracy can reach the theoretical values determined by the sensor precision.
A self-calibrating optomechanical force sensor with femtonewton resolution
Authors: Melcher John , Stirling Julian , Cervantes Felipe Guzmán , Pratt Jon R. , Shaw Gordon A.
Published: December 2014

We report the development of an ultrasensitive optomechanical sensor designed to improve the accuracy and precision of force measurements with atomic force microscopy. The sensors reach quality factors of 4.3 × 106 and force resolution on the femtonewton scale at room temperature. Self-calibration of the sensor is accomplished using radiation pressure to create a reference force. Self-calibration enables in situ calibration of the sensor in extreme environments, such as cryogenic ultra-high vacuum. The senor technology presents a viable route to force measurements at the atomic scale with uncertainties below the percent level.
Laser-written parabolic micro-antennas for efficient photon collection
Authors: Schell Andreas W. , Neumer Tanja , Shi Qiang , Kaschke Johannes , Fischer Joachim , Wegener Martin , Benson Oliver
Published: December 2014

Efficient collection of photons from solid-state single-photon emitters, like quantum dots, molecules, or defect centers in diamond, is a very demanding task. Here, we introduce parabolic micro-antennas fabricated by two-photon direct laser-writing to enhance the collection efficiency by directing emitted light into a small solid angle. The antennas can be fabricated on-site at the position of a pre-selected single-photon emitter.
Ultra-high quality factors in superconducting niobium cavities in ambient magnetic fields up to 190 mG
Authors: Romanenko A. , Grassellino A. , Crawford A. C. , Sergatskov D. A. , Melnychuk O.
Published: December 2014

Ambient magnetic field, if trapped in the penetration depth, leads to the residual resistance and therefore sets the limit for the achievable quality factors in superconducting niobium resonators for particle accelerators. Here, we show that a complete expulsion of the magnetic flux can be performed and leads to: (1) record quality factors Q > 2 × 1011 up to accelerating gradient of 22 MV/m; (2) Q ∼ 3 × 1010 at 2 K and 16 MV/m in up to 190 mG magnetic fields. This is achieved by large thermal gradients at the normal/superconducting phase front during the cooldown. Our findings open up a way to ultra-high quality factors at low temperatures and show an alternative to the sophisticated magnetic shielding implemented in modern superconducting accelerators.
Phase transition modeling of polytetrafluoroethylene during Taylor impact
Authors: Resnyansky A. D. , Bourne N. K. , Brown E. N. , Millett J. C. F. , Rae P. J. , McDonald S. A. , Withers P. J.
Published: December 2014

The complex pressure and temperature dependent phase behavior of the semicrystalline polymer polytetrafluoroethylene (PTFE) has been investigated experimentally. One manifestation of this behavior has been observed as an anomalous abrupt ductile-to-brittle transition in the failure mode of PTFE rods in Taylor cylinder impact tests when impact velocity exceeds a narrow critical threshold. Earlier, hydrocode calculations and Hugoniot estimates have indicated that this critical velocity corresponds to the pressure in PTFE associated with the transition from a crystalline phase of helical structure to the high pressure crystalline phase (phase III) of a planar form. The present work represents PTFE as a material in a simplified phase structure with the transition between the modeled phases regulated by a kinetic description. The constitutive modeling describes the evolution of mechanical characteristics corresponding to the change of mechanical properties due to either an increase of crystallinity or the phase transition of a crystalline low-pressure component into phase III. The modeling results demonstrate that a change in the kinetics of the transition mechanism in PTFE when traversing the critical impact velocity can be used to explain the failure of the polymer in the Taylor cylinder impact tests.
Study of turbulent energy dissipation rate of fluid flow in the vicinity of dispersed phase boundary using spatiotemporal tree model
Authors: Sikiö Päivi , Jalali Payman
Published: December 2014

The hierarchical shell models of turbulence including a spatial dimension, namely, spatiotemporal tree models, reproduce the intermittent behavior of Navier-Stokes equations in both space and time dimensions corresponding to high Reynolds number turbulent flows. This model is used, for the first time in this paper, in a one-dimensional flow zone containing a dispersed-phase particle that can be used in the study of dispersed-phase flows. In this paper, a straightforward method has been used to introduce discrete phase into the spatiotemporal tree model that leads to an increased amount of turbulent energy dissipation rate in the vicinity of the discrete phase. The effects of particle insertion and particle size on the turbulent energy dissipation rate are demonstrated. Moreover, the space-scale behavior of the time-averaged turbulent energy dissipation rate in the presence of dispersed phase is demonstrated by means of continuous wavelet transform.
Optical properties of C-doped bulk GaN wafers grown by halide vapor phase epitaxy
Authors: Khromov S. , Hemmingsson C. , Monemar B. , Hultman L. , Pozina G.
Published: December 2014

Freestanding bulk C-doped GaN wafers grown by halide vapor phase epitaxy are studied by optical spectroscopy and electron microscopy. Significant changes of the near band gap (NBG) emission as well as an enhancement of yellow luminescence have been found with increasing C doping from 5 × 1016 cm−3 to 6 × 1017 cm−3. Cathodoluminescence mapping reveals hexagonal domain structures (pits) with high oxygen concentrations formed during the growth. NBG emission within the pits even at high C concentration is dominated by a rather broad line at ∼3.47 eV typical for n-type GaN. In the area without pits, quenching of the donor bound exciton (DBE) spectrum at moderate C doping levels of 1–2 × 1017 cm−3 is observed along with the appearance of two acceptor bound exciton lines typical for Mg-doped GaN. The DBE ionization due to local electric fields in compensated GaN may explain the transformation of the NBG emission.
Towards a CdS/Cu2ZnSnS4 solar cell efficiency improvement: A theoretical approach
Authors: Courel Maykel , Andrade-Arvizu J. A. , Vigil-Galán O.
Published: December 2014

In this work, a device model for Cu2ZnSnS4 (CZTS) solar cell with certified world record efficiency is presented. A study of the most important loss mechanisms and its effect on solar cell performance was carried out. The trap-assisted tunneling and CdS/CZTS interface recombination are introduced as the most important loss mechanisms. Detailed comparison of the simulation results to the measured device parameters shows that our model is able to reproduce the experimental observations (quantum efficiency, efficiency, Jsc, FF, and Voc) reported under normal operating conditions. Finally, a discussion about a further solar cell efficiency improvement is addressed.
Pressure dependence of the refractive index in wurtzite and rocksalt indium nitride
Authors: Oliva R. , Segura A. , Ibáñez J. , Yamaguchi T. , Nanishi Y. , Artús L.
Published: December 2014

We have performed high-pressure Fourier transform infrared reflectance measurements on a freestanding InN thin film to determine the refractive index of wurtzite InN and its high-pressure rocksalt phase as a function of hydrostatic pressure. From a fit to the experimental refractive-index curves including the effect of the high-energy optical gaps, phonons, free carriers, and the direct (fundamental) band-gap in the case of wurtzite InN, we obtain pressure coefficients for the low-frequency (electronic) dielectric constant ε∞. Negative pressure coefficients of −8.8 × 10−2 GPa−1 and −14.8 × 10−2 GPa−1 are obtained for the wurtzite and rocksalt phases, respectively. The results are discussed in terms of the electronic band structure and the compressibility of both phases.
Atmospheric pressure route to epitaxial nitrogen-doped trilayer graphene on 4H-SiC (0001) substrate
Authors: Boutchich M. , Arezki H. , Alamarguy D. , Ho K.-I. , Sediri H. , Güneş F. , Alvarez J. , Kleider J. P. , Lai C. S. , Ouerghi A.
Published: December 2014

Large-area graphene film doped with nitrogen is of great interest for a wide spectrum of nanoelectronics applications, such as field effect devices, super capacitors, and fuel cells among many others. Here, we report on the structural and electronic properties of nitrogen doped trilayer graphene on 4H-SiC (0001) grown under atmospheric pressure. The trilayer nature of the growth is evidenced by scanning transmission electron microscopy. X-ray photoelectron spectroscopy shows the incorporation of 1.2% of nitrogen distributed in pyrrolic-N, and pyridinic-N configurations as well as a graphitic-N contribution. This incorporation causes an increase in the D band on the Raman signature indicating that the nitrogen is creating defects. Ultraviolet photoelectron spectroscopy shows a decrease of the work function of 0.3 eV due to the N-type doping of the nitrogen atoms in the carbon lattice and the edge defects. A top gate field effect transistor device has been fabricated and exhibits carrier mobilities up to 1300 cm2/V s for holes and 850 cm2/V s for electrons at room temperature.
Scanning tunneling microscopic study of the effects of surface conduction on the electrical transport properties of nanosized Schottky contacts between FeSi2 nanoislands and Si(111)
Authors: Zou Zhi-Qiang , Liu Xiao-Yong , Sun Li-Min , Li Xu
Published: December 2014

Electrical transport properties of Schottky nanocontacts between FeSi2 nanoislands and p(n)-type Si(111) are investigated by a scanning tunneling microscope with tip touching the islands. By comparing the current-voltage curves of the FeSi2 islands with and without a surrounding trench, we extracted the contribution of surface leakage current from the total current and found that the surface conduction dominates the electrical transport of the nanocontacts. The surface leakage current increases linearly with reverse bias but increases exponentially with forward bias, which is explained by the surface-state conduction and surface recombination-generation conduction of minority carriers.
Liquid metal actuation-based reversible frequency tunable monopole antenna
Authors: Kim Daeyoung , Pierce Richard G. , Henderson Rashaunda , Doo Seok Joo , Yoo Koangki , Lee Jeong-Bong
Published: December 2014

We report the fabrication and characterization of a reversible resonant frequency tunable antenna based on liquid metal actuation. The antenna is composed of a coplanar waveguide fed monopole stub printed on a copper-clad substrate, and a tunnel-shaped microfluidic channel linked to the printed metal. The gallium-based liquid metal can be injected and withdrawn from the channel in response to an applied air pressure. The gallium-based liquid metal is treated with hydrochloric acid to eliminate the oxide layer, and associated wetting/sticking problems, that arise from exposure to an ambient air environment. Elimination of the oxide layer allows for reliable actuation and repeatable and reversible tuning. By controlling the liquid metal slug on-demand with air pressure, the liquid metal can be readily controllable to connect/disconnect to the monopole antenna so that the physical length of the antenna reversibly tunes. The corresponding reversible resonant frequency changes from 4.9 GHz to 1.1 GHz. The antenna properties based on the liquid metal actuation were characterized by measuring the reflection coefficient and agreed well with simulation results. Additionally, the corresponding time-lapse images of controlling liquid metal in the channel were studied.
“True” negative thermal expansion in Mn-doped LaCu3Fe4O12 perovskite oxides
Authors: Yamada Ikuya , Marukawa Shohei , Murakami Makoto , Mori Shigeo
Published: December 2014

Negative and zero thermal expansion near room temperature have been achieved in a cubic A-site ordered perovskite oxide LaCu3Fe4−xMnxO12. A discontinuous volume change in the parent material LaCu3Fe4O12, owing to a first-order intermetallic charge transfer transition (3Cu2+ + 4Fe3.75+ ⇄ 3Cu3+ + 4Fe3+), is efficiently relaxed to a second-order-type negative thermal expansion with a linear thermal expansion coefficient (αL) of −2.2(1) × 10−5 K−1 between 300 and 340 K at x = 0.75, followed by an almost zero thermal expansion [αL of −1.1(2) × 10−6 K−1] at x = 1 in a wide temperature range (240–360 K) including room temperature. Magnetic susceptibility measurements display substantial broadenings of the antiferromagnetic transition when x increases, supporting the relaxation of first-order electronic phase transition of the parent material. These findings indicate that the significant adjustability of thermal expansion properties can be achieved in first-order intermetallic charge-transfer transition.
Double in-plane alignment in biaxially textured thin films
Authors: Elofsson V. , Saraiva M. , Boyd R. D. , Sarakinos K.
Published: December 2014

The scientific interest and technological relevance of biaxially textured polycrystalline thin films stem from their microstructure that resembles that of single crystals. To explain the origin and predict the type of biaxial texture in off-normally deposited films, Mahieu et al. have developed an analytical model [S. Mahieu et al., Thin Solid Films 515, 1229 (2006)]. For certain materials, this model predicts the occurrence of a double in-plane alignment, however, experimentally only a single in-plane alignment has been observed and the reason for this discrepancy is still unknown. The model calculates the resulting in-plane alignment by considering the growth of faceted grains with an out-of-plane orientation that corresponds to the predominant film out-of-plane texture. This approach overlooks the fact that in vapor condensation experiments where growth kinetics is limited and only surface diffusion is active, out-of-plane orientation selection is random during grain nucleation and happens only upon grain impingement. Here, we compile and implement an experiment that is consistent with the key assumptions set forth by the in-plane orientation selection model by Mahieu et al.; a Cr film is grown off-normally on a fiber textured Ti epilayer to pre-determine the out-of-plane orientation and only allow for competitive growth with respect to the in-plane alignment. Our results show unambiguously a biaxially textured Cr (110) film that possesses a double in-plane alignment, in agreement with predictions of the in-plane selection model. Thus, a long standing discrepancy in the literature is resolved, paving the way towards more accurate theoretical descriptions and hence knowledge-based control of microstructure evolution in biaxially textured thin films.
Equation of state of bcc-Mo by static volume compression to 410 GPa
Authors: Akahama Yuichi , Hirao Naohisa , Ohishi Yasuo , Singh Anil K.
Published: December 2014

Unit cell volumes of Mo and Pt have been measured simultaneously to ≈400 GPa by x-ray powder diffraction using a diamond anvil cell and synchrotron radiation source. The body-centered cubic (bcc) phase of Mo was found to be stable up to 410 GPa. The equation of state (EOS) of bcc-Mo was determined on the basis of Pt pressure scale. A fit of Vinet EOS to the volume compression data gave K0 = 262.3(4.6) GPa, K0′ = 4.55(16) with one atmosphere atomic volume V0 = 31.155(24) A3. The EOS was in good agreement with the previous ultrasonic data within pressure difference of 2.5%–3.3% in the multimegabar range, though the EOS of Mo proposed from a shock compression experiment gave lower pressure by 7.2%–11.3% than the present EOS. The agreement would suggest that the Pt pressure scale provides an accurate pressure value in an ultra-high pressure range.
Magnetoresistance of Au films
Authors: Zhang D. L. , Song X. H. , Zhang X. , Zhang X.-G.
Published: December 2014

Classical magnetoresistance (MR) in nonmagnetic metals are conventionally understood in terms of the Kohler rule, with violation usually viewed as anomalous electron transport, in particular, as evidence of non-Fermi liquid behavior. Measurement of the MR of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms. Consequently, the Kohler rule should not be used to distinguish normal and anomalous electron transport in solids.
Experimental evidence of high-frequency complete elastic bandgap in pillar-based phononic slabs
Authors: Pourabolghasem Reza , Mohammadi Saeed , Eftekhar Ali A. , Khelif Abdelkrim , Adibi Ali
Published: December 2014

We present strong experimental evidence for the existence of a complete phononic bandgap, for Lamb waves, in the high frequency regime (i.e., 800 MHz) for a pillar-based phononic crystal (PnC) membrane with a triangular lattice of gold pillars on top. The membrane is composed of an aluminum nitride film stacked on thin molybdenum and silicon layers. Experimental characterization shows a large attenuation of at least 20 dB in the three major crystallographic directions of the PnC lattice in the frequency range of 760 MHz–820 MHz, which is in agreement with our finite element simulations of the PnC bandgap. The results of experiments are analyzed and the physics behind the attenuation in different spectral windows is explained methodically by assessing the type of Bloch modes and the in-plane symmetry of the displacement profile.
Multi-state lasing in self-assembled ring-shaped green fluorescent protein microcavities
Authors: Dietrich Christof P. , Höfling Sven , Gather Malte C.
Published: December 2014

We demonstrate highly efficient lasing from multiple photonic states in microcavities filled with self-assembled rings of recombinant enhanced green fluorescent protein (eGFP) in its solid state form. The lasing regime is achieved at very low excitation energies of 13 nJ and occurs from cavity modes dispersed in both energy and momentum. We attribute the momentum distribution to very efficient scattering of incident light at the surface of the eGFP rings. The distribution of lasing states in energy is induced by the large spectral width of the gain spectrum of recombinant eGFP (FWHM ≅ 25 nm).
Electron motion of an annular beam in a low-magnetic-field drift tube
Authors: Wu Ping , Tan Weibing , Sun Jun , Ye Hu , Hu Chengbao
Published: December 2014

Foil-less diodes and annular electron beams are widely adopted in high power microwave systems, and the electron beam is usually constrained by a guiding magnetic field to pass through the downstream drift tube and beam-wave interaction region. The electron beam, however, will present obvious radial motion when a low magnetic field is adopted, which will prominently influence the beam transmission and beam-wave interaction. This paper focuses on the radial motion of the electron beam in a low-magnetic-field drift tube. A spatial period is demonstrated with methods of theoretical analysis, single-particle calculations, particle-in-cell simulations, and experiments. The results obtained with different methods show good coherency, indicating that the real spatial period of the electron beam can be predicted by a simple formula which is based on single-particle motion regardless of space-charge effect.
Controllable growth of metallic nano-helices at room temperature conditions
Authors: Caridad José M. , McCloskey David , Donegan John F. , Krstić Vojislav
Published: December 2014

We report on a method to produce multiple-pitch, regularly shaped, aligned, and freestanding metallic nano-helices at room temperature. This method overcomes the limitations of the standard glancing angle deposition approach through a heat-management technique devoid of active substrate cooling and is even applicable for metals with low melting point, that is, high surface adatom diffusion. The structural quality and optical activity response of these metal nano-helices are comparable to state of the art helices produced by employing substrates cooled down to cryogenic temperatures.
Performance enhancement of thin film silicon solar cells based on distributed Bragg reflector & diffraction grating
Authors: Dubey R. S. , Saravanan S. , Kalainathan S.
Published: December 2014

The influence of various designing parameters were investigated and explored for high performance solar cells. Single layer grating based solar cell of 50 μm thickness gives maximum efficiency up to 24 % whereas same efficiency is achieved with the use of three bilayers grating based solar cell of 30 μm thickness. Remarkably, bilayer grating based solar cell design not only gives broadband absorption but also enhancement in efficiency with reduced cell thickness requirement. This absorption enhancement is attributed to the high reflection and diffraction from DBR and grating respectively. The obtained short-circuit current were 29.6, 32.9, 34.6 and 36.05 mA/cm2 of 5, 10, 20 and 30 μm cell thicknesses respectively. These presented designing efforts would be helpful to design and realize new generation of solar cells.
Electromechanics of graphene spirals
Authors: Korhonen Topi , Koskinen Pekka
Published: December 2014

Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.
A novel response to an outbreak of infectious syphilis in Christchurch, New Zealand
Authors: Coughlan Edward , Young Heather , Parkes Catherine , Coshall Maureen , Dickson Nigel , Psutka Rebecca , Saxton Peter , Pink Ramon , Adams Katharine
Published: December 2014

During 2012, Christchurch experienced a dramatic increase in cases of infectious syphilis among men who have sex with men. This was accompanied by some novel trends; notably, the acquisition of infection in a younger age group, with local sexual contacts, commonly via the use of social media. This study is a report on an approach to case identification and public health communication as a component of a multifaceted outbreak response. Enhanced syphilis surveillance data on public health responses to outbreaks of sexually transmissible infections was collated and reviewed, alongside clinical records and literature. Reported outbreak response methods were adapted for the Christchurch cohort. A Facebook page was created to raise awareness of infectious syphilis, the importance of screening and where to get tested. Twenty-six males were diagnosed with infectious syphilis in 2012, an increase from previous years, of which 22 reported only male sexual contact. High use of social media used to find potential sexual contacts was reported. Enhanced syphilis surveillance characterised in detail an infectious syphilis outbreak in Christchurch. Index cases were identified, contact tracing mapping was used to identify transmission networks and social media was also used to educate the risk group. There was a decrease in infectious syphilis presentations, with no cases in the last 3 months of 2012.
Changes in Relative Abundance of Several Minnesota Fishes from 1970 to 2013
Authors: Bethke Bethany J. , Staples David F.
Published: December 2014

Large‐scale ecological stressors such as climate change, habitat degradation, and invasive species increasingly affect fisheries across watershed or political boundaries within which they are typically managed. Though broad‐scale analyses of trends in fish populations and changes in aquatic communities can be useful for detecting the effects of these stressors, they are rarely possible due to a lack of long‐term data sets. The Minnesota Department of Natural Resources has used gill nets and trap nets to monitor fish communities in lakes since 1940, and the techniques have been standardized since 1970. We applied a random‐coefficient mixed‐effects model to mean CPUE data to describe statewide and local population trends of eight key fish species (Black Crappie Pomoxis nigromaculatus, Bluegill Lepomis macrochirus, Largemouth Bass Micropterus salmoides, Northern Pike Esox lucius, Smallmouth Bass M. dolomieu, Walleye Sander vitreus, White Sucker Catostomus commersonii, and Yellow Perch Perca flavescens) sampled from 1970 to 2013 in 119–1,499 lakes. We found increasing statewide trends in gill‐net CPUE of Black Crappie, Bluegill, Largemouth Bass, Smallmouth Bass, Northern Pike, and Walleye and decreasing trends for Yellow Perch and White Sucker. Statewide trends in average trap‐net CPUE were positive for Bluegill, negative for Black Crappie, Walleye, White Sucker, and Yellow Perch, and stable for Largemouth Bass, Northern Pike, and Smallmouth Bass. We compared the CPUE trends across lake types developed for Minnesota lakes and found some differences, especially in medium and large mesotrophic lakes, suggesting that some species display changes in abundance more in those lakes types than in others. This study quantifies temporal changes in Minnesota's fish community structure and can help managers focus future research and management activities in the state and in similar waters across central North America.

Received May 14, 2014; accepted September 9, 2014
Smoking is Associated with Increased Risk of Binge Drinking in a Young Adult Hispanic Population at the Us-Mexico Border
Authors: Woolard Robert , Liu Jiayang , Parsa Michael , Merriman Garrett , Tarwater Patrick , Alba Israel , Villalobos Susana , Ramos Rebecca , Bernstein Judith , Bernstein Edward , Bond Jason , Cherpitel Cheryl J.
Published: December 2014

Background

This study examines factors related to general health and health behavior, including smoking, that may be associated with binge drinking, drinking “at risk,” and potential for alcohol use disorder among young adults of Mexican ancestry.

Methods

A total of 2191 young adult emergency department (ED) patients (18–30 years) of Mexican ancestry in a public hospital proximate to the US-Mexico border completed health surveys while they were waiting to be treated, including questions on general health, drinking, smoking, and drug use.

Results

Thirty-seven percent of the study participants reported binge drinking, 38% were “at-risk” alcohol users (above National Institute on Alcohol Abuse and Alcoholism guidelines), and 22% were Rapid Alcohol Problem Screen (RAPS) positive (indicating potential for alcohol use disorder). Smoking was reported by 31%, marijuana use by 16%, and other drug use by 9%. Multiple variable models revealed that smoking was the strongest factor associated with binge drinking. Those who smoked were 3.1 ( P < .0001) times more likely to binge drink. Other factors independently associated with binge drinking were age 22–25 years (odds ratio [OR] = 1.5, P = .003), male gender (OR = 1.5, P = .0001), and ED visit for injury (OR = 1.4, P = .007).

Conclusions

There is a strong association of smoking and binge drinking. Study findings suggest that brief interventions designed to reduce preventable health risks for young Hispanics should include discussion of both binge drinking and smoking behaviors.
SPECTRAL CALIBRATION IN THE MID-INFRARED: CHALLENGES AND SOLUTIONS
Authors: Sloan G. C. , Herter T. L. , Charmandaris V. , Sheth K. , Burgdorf M. , Houck J. R.
Published: December 2014

We present spectra obtained with the Infrared Spectrograph on the Spitzer Space Telescope of 33 K giants and 20 A dwarfs to assess their suitability as spectrophotometric standard stars. The K giants confirm previous findings that the strength of the SiO absorption band at 8 μm increases for both later optical spectral classes and redder (B–V)0 colors, but with considerable scatter. For K giants, the synthetic spectra underpredict the strengths of the molecular bands from SiO and OH. For these reasons, the assumed true spectra for K giants should be based on the assumption that molecular band strengths in the infrared can be predicted accurately from neither optical spectral class or color nor synthetric spectra. The OH bands in K giants grow stronger with cooler stellar temperatures, and they are stronger than predicted by synthetic spectra. As a group, A dwarfs are better behaved and more predictable than the K giants, but they are more likely to show red excesses from debris disks. No suitable A dwarfs were located in parts of the sky continuously observable from Spitzer, and with previous means of estimating the true spectra of K giants ruled out, it was necessary to use models of A dwarfs to calibrate spectra of K giants from observed spectral ratios of the two groups and then use the calibrated K giants as standards for the full database of infrared spectra from Spitzer. We also describe a lingering artifact that affects the spectra of faint blue sources at 24 μm.
REVEALING A UNIVERSAL PLANET–METALLICITY CORRELATION FOR PLANETS OF DIFFERENT SIZES AROUND SOLAR-TYPE STARS
Authors: Wang Ji , Fischer Debra A.
Published: December 2014

The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have demonstrated the planet–metallicity correlation for large planets (

); however, a correlation has not been found for smaller planets. With a sample of 406 Kepler objects of interest whose stellar properties are determined spectroscopically, we reveal a universal planet–metallicity correlation: not only gas-giant planets (

) but also gas-dwarf (

) and terrestrial planets (

) occur more frequently in metal-rich stars. The planet occurrence rates of gas-giant planets, gas-dwarf planets, and terrestrial planets are

,

, and

times higher for metal-rich stars than for metal-poor stars, respectively.
Strong convergence to the homogenized limit of parabolic equations with random coefficients
Authors: Conlon Joseph , Fahim Arash
Published: December 2014

This paper is concerned with the study of solutions to discrete parabolic equations in divergence form with random coefficients and their convergence to solutions of a homogenized equation. It has previously been shown that if the random environment is translational invariant and ergodic, then solutions of the random equation converge under diffusive scaling to solutions of a homogenized parabolic PDE. In this paper point-wise estimates are obtained on the difference between the averaged solution to the random equation and the solution to the homogenized equation for certain random environments which are strongly mixing.
Subgroups of 𝑝-divisible groups and centralizers in symmetric groups
Authors: Stapleton Nathaniel
Published: December 2014

We give a formula relating the transfer maps for the cohomology theories

E

n

E_{n}

and

C
t

C_t

to the transchromatic generalized character maps of a previous paper by the author. We then apply this to understand the effect of the transchromatic generalized character maps on Strickland’s isomorphism between the Morava

E
E

-theory of the symmetric group

Σ

p
k

\Sigma _{p^k}

(modulo a transfer ideal) and the global sections of the scheme that classifies subgroups of order

p
k

p^k

in the formal group associated to

E

n

E_{n}

. This provides an algebro-geometric interpretation to the

C
t

C_t

-cohomology of the class of groups arising as centralizers of finite sets of commuting elements in symmetric groups.
Equivalence classes of subquotients of pseudodifferential operator modules
Authors: Conley Charles , Larsen Jeannette
Published: December 2014

Consider the spaces of pseudodifferential operators between tensor density modules over the line as modules of the Lie algebra of vector fields on the line. We compute the equivalence classes of various subquotients of these modules. There is a 2-parameter family of subquotients with any given Jordan-Hölder composition series. In the critical case of subquotients of length 5, the equivalence classes within each non-resonant 2-parameter family are specified by the intersections of a pencil of conics with a pencil of cubics. In the case of resonant subquotients of length 4 with self-dual composition series, as well as in those of lacunary subquotients of lengths 3 and 4, equivalence is specified by a single pencil of conics. Non-resonant subquotients of length exceeding 7 admit no non-obvious equivalences. The cases of lengths 6 and 7 are unresolved.
Interpretation of the X-ray spectral variation of 1H 0707−495 with a variable double partial covering model
Authors: Mizumoto Misaki , Ebisawa Ken , Sameshima Hiroaki
Published: December 2014

The narrow-line Seyfert 1 galaxy 1H 0707−495 is known to exhibit significant X-ray spectral variations. Its X-ray energy spectrum is characterized by a strong soft excess emission, an extremely deep iron K-edge structure at ∼ 7 keV, and a putative iron L-line/edge feature at ∼ 1 keV. We have found that the energy spectrum of 1H 0707−495 in 0.5–10 keV is successfully explained by a “variable double partial covering model” where the original continuum spectrum, which is composed of a soft multi-color disk blackbody component and a hard power-law component, is partially covered by two ionized absorption layers with different ionization states and the same partial covering fraction. The lower-ionized and thicker absorption layer primarily explains the iron K-edge feature, and the higher-ionized and thinner absorption layer explains the L-edge feature. We have discovered that the observed significant intensity/spectral variation within ∼ 1 d is mostly explained by varying only the partial covering fraction. In our model, the intrinsic luminosity and spectral shape are hardly variable within ∼ 1 d, while some intrinsic variability above 3 keV is recognized. This is consistent with the picture that the multi-color disk blackbody spectrum is almost invariable on this timescale, and the hard power-law component is more variable. We propose that the observed spectral variation of 1H 0707−495 is caused by three physically independent variations with different timescales; (1) intrinsic luminosity variation over days, (2) variation of partial covering fraction on a timescale of hours, and (3) small intrinsic hard component variation above 3 keV on a timescale of hours or less.
The Importance of the KR-Rich Region of the Coat Protein of Ourmia melon virus for Host Specificity, Tissue Tropism, and Interference With Antiviral Defense
Authors: Rossi Marika , Vallino Marta , Abbà Simona , Ciuffo Marina , Balestrini Raffaella , Genre Andrea , Turina Massimo
Published: December 2014

The N-terminal region of the Ourmia melon virus (OuMV) coat protein (CP) contains a short lysine/arginine-rich (KR) region. By alanine scanning mutagenesis, we showed that the KR region influences pathogenicity and virulence of OuMV without altering viral particle assembly. A mutant, called OuMV6710, with three basic residue substitutions in the KR region, was impaired in the ability to maintain the initial systemic infection in Nicotiana benthamiana and to infect both cucumber and melon plants systemically. The integrity of this protein region was also crucial for encapsidation of viral genomic RNA; in fact, certain mutations within the KR region partially compromised the RNA encapsidation efficiency of the CP. In Arabidopsis thaliana Col-0, OuMV6710 was impaired in particle accumulation; however, this phenotype was abolished in dcl2/dcl4 and dcl2/dcl3/dcl4 Arabidopsis mutants defective for antiviral silencing. Moreover, in contrast to CPwt, in situ immunolocalization experiments indicated that CP6710 accumulates efficiently in the spongy mesophyll tissue of infected N. benthamiana and A. thaliana leaves but only occasionally infects palisade tissues. These results provided strong evidence of a crucial role for OuMV CP during viral infection and highlighted the relevance of the KR region in determining tissue tropism, host range, pathogenicity, and RNA affinity, which may be all correlated with a possible CP silencing-suppression activity.
Obesity and Gastrointestinal Disorders in Children
Authors: Phatak Uma P. , Pashankar Dinesh S.
Published: December 2014

Obesity in children has become a global pandemic during the last decade. Recent studies have reported an association between obesity and functional gastrointestinal (GI) disorders. In addition, obesity is also becoming increasingly recognized at diagnosis of organic GI diseases such as celiac disease and inflammatory bowel disease. An awareness of all possible complications and associations of obesity by the practicing physician is crucial to provide comprehensive care to obese children. This article reviews the present data on the association between obesity and various common GI disorders. The possible mechanisms and the clinical significance of this association are also discussed.
When maths trumps logic: probabilistic judgements in chimpanzees
Authors: Hanus Daniel , Call Josep
Published: December 2014

When searching for hidden food, do chimpanzees take into account both the number of hidden items and the number of potential hiding locations? We presented chimpanzees with two trays, each of them containing a different food/cup ratio and therefore a different likelihood of finding a baited cup among empty alternatives. Subjects' performance was directly influenced by the relative difference (probability ratio (PR)) between the two given probabilities. Interestingly, however, they did not appreciate the special value of a truly safe option (with
P
= 1.0). Instead, they seemed to ‘blindly’ rely on the PR between the two options, systematically preferring the more likely one once a certain threshold had been reached. A control condition ruled out the possibility of low-level learning explanations for the observed performance.
Constructing predictive models of human running
Authors: Maus Horst-Moritz , Revzen Shai , Guckenheimer John , Ludwig Christian , Reger Johann , Seyfarth Andre
Published: December 2014

Running is an essential mode of human locomotion, during which ballistic aerial phases alternate with phases when a single foot contacts the ground. The spring-loaded inverted pendulum (SLIP) provides a starting point for modelling running, and generates ground reaction forces that resemble those of the centre of mass (CoM) of a human runner. Here, we show that while SLIP reproduces within-step kinematics of the CoM in three dimensions, it fails to reproduce stability and predict future motions. We construct SLIP control models using data-driven Floquet analysis, and show how these models may be used to obtain predictive models of human running with six additional states comprising the position and velocity of the swing-leg ankle. Our methods are general, and may be applied to any rhythmic physical system. We provide an approach for identifying an event-driven linear controller that approximates an observed stabilization strategy, and for producing a reduced-state model which closely recovers the observed dynamics.
Modelling the spatial heterogeneity and molecular correlates of lymphocytic infiltration in triple-negative breast cancer
Authors: Yuan Yinyin
Published: December 2014

Lymphocytic infiltration is associated with a favourable prognosis and predicts response to chemotherapy in many cancer types, including the aggressive triple-negative breast cancer (TNBC). However, it is not well understood owing to the high levels of spatial heterogeneity within tumours, which is difficult to analyse by traditional pathological assessment. This paper describes an unbiased methodology to statistically model the spatial distribution of lymphocytes among tumour cells based on automated analysis of haematoxylin-and-eosin-stained whole-tumour section images, which is applied to two independent TNBC cohorts of 181 patients with matched microarray gene expression data. The novelty of the proposed methodology is the fusion of image analysis and statistical modelling for an integrative understanding of intratumour heterogeneity of lymphocytic infiltration. Using this methodology, a quantitative measure of intratumour lymphocyte ratio is developed and found to be significantly associated with disease-specific survival in both TNBC cohorts independent to standard clinical parameters. The proposed image-based measure compares favourably to a number of gene expression signatures of immune infiltration. In addition, heterogeneous immune infiltration at the morphological level is reflected at the molecular scale and correlated with increased expression ofCTLA4, the target of ipilimumab. Taken together, these results support the fusion of high-throughput image analysis and statistical modelling to offer reproducible and robust biomarkers for the objective identification of patients with poor prognosis and treatment options.
A nanostructural basis for gloss of avian eggshells
Authors: Igic Branislav , Fecheyr-Lippens Daphne , Xiao Ming , Chan Andrew , Hanley Daniel , Brennan Patricia R. L. , Grim Tomas , Waterhouse Geoffrey I. N. , Hauber Mark E. , Shawkey Matthew D.
Published: December 2014

The role of pigments in generating the colour and maculation of birds' eggs is well characterized, whereas the effects of the eggshell's nanostructure on the visual appearance of eggs are little studied. Here, we examined the nanostructural basis of glossiness of tinamou eggs. Tinamou eggs are well known for their glossy appearance, but the underlying mechanism responsible for this optical effect is unclear. Using experimental manipulations in conjunction with angle-resolved spectrophotometry, scanning electron microscopy, atomic force microscopy and chemical analyses, we show that the glossy appearance of tinamou eggshells is produced by an extremely smooth cuticle, composed of calcium carbonate, calcium phosphate and, potentially, organic compounds such as proteins and pigments. Optical calculations corroborate surface smoothness as the main factor producing gloss. Furthermore, we reveal the presence of weak iridescence on eggs of the great tinamou (Tinamus major), an optical effect never previously documented for bird eggs. These data highlight the need for further exploration into the nanostructural mechanisms for the production of colour and other optical effects of avian eggshells.