bluuebunny/crossref_metadata_2025 huggingface dataset:
Terrace retro-reflector array for poloidal polarimeter on ITER
Authors: Imazawa R. , Kawano Y. , Ono T. , Kusama Y.
Published: February 2011

A new concept of a terrace retro-reflector array (TERRA) as part of the poloidal polarimeter for ITER is proposed in this paper. TERRA reflects a laser light even from a high incident angle in the direction of the incident-light path, while a conventional retro-reflector array cannot. Besides, TERRA can be installed in a smaller space than a corner-cube retro-reflector. In an optical sense, TERRA is equivalent to a Littrow grating, the blaze angle of which varies, depending on the incident angle. The reflected light generates a bright and dark fringe, and the bright fringe is required to travel along the incident-light path to achieve the objects of laser-aided diagnostics. In order to investigate the propagation properties of laser light reflected by TERRA, we have developed a new diffraction formula. Conditions for the propagation of the bright fringe in the direction of the incident light have been obtained using the Littrow grating model and have been confirmed in a simulation applying the new diffraction formula. Finally, we have designed laser transmission optics using TERRA for the ITER poloidal polarimeter and have calculated the light propagation of the system. The optical design obtains a high transmission efficiency, with 88.6% of the incident power returned. These results demonstrate the feasibility of applying TERRA to the ITER poloidal polarimeter.
Efficient radio frequency filters for space constrained cryogenic setups
Authors: Mandal Soumen , Bautze Tobias , Blinder Rémi , Meunier Tristan , Saminadayar Laurent , Bäuerle Christopher
Published: February 2011

Noise filtering is an essential part for measurement of quantum phenomena at extremely low temperatures. Here, we present the design of a filter which can be installed in space constrained cryogenic environment containing a large number of signal carrying lines. Our filters have a –3 db point of 65 kHz and their performance at GHz frequencies is comparable to the best available RF filters.
Coherent features in the sensitivity field of a planar mixing layer
Authors: Zayernouri M. , Metzger M.
Published: February 2011

Coherency in the topology of the instantaneous sensitivity fields of the planar mixing layer was captured using the sensitivity equation method (SEM). In the SEM approach, the partial differential equations governing the evolution of the sensitivity coefficients are derived, discretized, and solved directly, in the present work, using an unsteady finite-volume-based fractional-step algorithm. This allows the investigation of parameter-dependence without performing parametric studies. The present results, from numerical simulations run at Reδ0=200 and Pr=0.71, provide a means to examine how and to what extent perturbations in the Reynolds/Prandtl number locally alter the structure of the flow. Specifically, a two-blade pattern appears as a dominant feature in the sensitivity solution and highlights the physical mechanism leading to vortex thickness growth and enhanced molecular mixing with increasing Reδ0 and Pr. An expression describing the sensitivity of vortex thickness to changes in Reδ0 is also derived and validated using the concept of “nearby” flows.
Intersubband transition energy and linewidth modified by a submonolayer AlAs insertion into GaAs quantum wells
Authors: Unuma Takeya , Takata Soichirou , Sakasegawa Yohei , Hirakawa Kazuhiko , Nakamura Arao
Published: February 2011

We demonstrate a modification of the energy and linewidth of intersubband transitions by the hetero-insertion of a submonolayer into semiconductor quantum wells (QWs). Different changes in the transition energy and absorption linewidth are observed with systematically varied positions of a 0.92-monolayer AlAs insertion into 7.0-nm-wide GaAs QWs. The experimental results are well reproduced by theoretical calculations taking into account energy shifts and scattering processes in electron subbands due to the hetero-insertion. Our findings suggest that the combination of the insertion position and well width can be used to separately tune the transition energy and absorption/emission linewidth for optoelectronic devices.
The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods
Authors: Palmer Michael H. , Hoffmann Søren Vrønning , Jones Nykola C. , Head Ashley R. , Lichtenberger Dennis L.
Published: February 2011

The Rydberg states in the vacuum ultraviolet photoabsorption spectrum of 1,2,3-triazole have been measured and analyzed with the aid of comparison to the UV valence photoelectron ionizations and the results of ab initio configuration interaction (CI) calculations. Calculated electronic ionization and excitation energies for singlet, triplet valence, and Rydberg states were obtained using multireference multiroot CI procedures with an aug-cc-pVTZ [5s3p3d1f] basis set and a set of Rydberg [4s3p3d3f] functions. Adiabatic excitation energies obtained for several electronic states using coupled-cluster (singles, doubles, and triples) and complete active space self-consistent field procedures agree well with experimental values. Variations in bond lengths with the electronic state are discussed. The lowest energy UV band (∼5.5–6.5 eV) is assigned to three electronically excited states and demonstrates the occurrence of a nonplanar upper state on the low energy side. A UV photoelectron spectrum with an improved resolution yielded adiabatic and vertical ionization energies and reorganization energies for several of the lowest cationic states. As well as excitations to the s, p, d-Rydberg states are the excitations consistent with an f-series.
Effect of window reflections on photonic Doppler velocimetry measurements
Authors: Ao T. , Dolan D. H.
Published: February 2011

Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especially for low-velocity transients. Shock experiments of quartz compressed between two sapphire plates demonstrate how optical window reflections cause ringing in the extracted PDV velocity profile. Velocity ringing is significantly reduced by using either a wedge window or an antireflective coating.
Effect of absorption to nanopore on optical properties of conjugated polymers in porous anode alumina
Authors: Kong Fan , Yang Yimin , Zhang Xueqin , Lin Baoping , Qi Zhengjian , Qiu Teng
Published: February 2011

The optical properties of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene] (MEH-PPV) in the nanopores of porous anodic alumina (PAA) are investigated using temperature-dependent photoluminescence (PL) spectra. The PL spectrum of MEH-PPV in PAA becomes wide because the polymer chains absorb to the nanopore walls to restrict excitation energy transfer. Unlike the MEH-PPV film, the PL peak wavelength of MEH-PPV in PAA is independent of temperature in the range of 80 to 290 K. The influence of temperature on the emission bandwidth of MEH-PPV in the nanopores is obviously less than that in the film because temperature-dependent inhomogeneous broadening is suppressed by the absorption effect.
Two-photon ionization of helium studied with the multiconfigurational time-dependent Hartree–Fock method
Authors: Hochstuhl David , Bonitz Michael
Published: February 2011

The multiconfigurational time-dependent Hartree–Fock method (MCTDHF) is applied for simulations of the two-photon ionization of helium. We present results for the single and double ionizations from the ground state for photon energies in the nonsequential regime and compare them to direct solutions of the Schrödinger equation using the time-dependent (full) configuration interaction (TDCI) method. We find that the single ionization is accurately reproduced by MCTDHF, whereas the double ionization results correctly capture the main trends of TDCI.
Masking a CCD camera allows multichord charge exchange spectroscopy measurements at high speed on the DIII-D tokamak
Authors: Meyer O. , Burrell K. H. , Chavez J. A. , Kaplan D. H. , Chrystal C. , Pablant N. A. , Solomon W. M.
Published: February 2011

Charge exchange spectroscopy is one of the standard plasma diagnostic techniques used in tokamak research to determine ion temperature, rotation speed, particle density, and radial electric field. Configuring a charge coupled device (CCD) camera to serve as a detector in such a system requires a trade-off between the competing desires to detect light from as many independent spatial views as possible while still obtaining the best possible time resolution. High time resolution is essential, for example, for studying transient phenomena such as edge localized modes. By installing a mask in front of a camera with a 1024 × 1024 pixel CCD chip, we are able to acquire spectra from eight separate views while still achieving a minimum time resolution of 0.2 ms. The mask separates the light from the eight spectra, preventing spatial and temporal cross talk. A key part of the design was devising a compact translation stage which attaches to the front of the camera and allows adjustment of the position of the mask openings relative to the CCD surface. The stage is thin enough to fit into the restricted space between the CCD camera and the spectrometer endplate.
Spin-dependent tunneling properties of Thue-Morse sequence in ferromagnet/semiconductor/ferromagnet cascade junctions
Authors: Qin Lilan , Liu De , Zhang Hongmei , Kong Xiaojun
Published: February 2011

We investigate the spin-dependent transport in aperiodic cascade junctions of semiconductors, where semiconductors are arranged in the Thue-Morse sequence. We have calculated the spin-dependent transmission and the spin polarization with a transfer matrix method in these cascade junctions. It is shown that a spin-dependent bandgap structure appears by changing the generation and the Rashba spin-orbit wave vector. As a result, around resonant wave vectors, high spin polarization has been observed and the spin polarization has been reversed, and the spin conductance exists the value of zero by tuning the Rashba spin-orbit coupling. Our investigations may provide a way to design spin filters and spin switches.
Directionality control through selective excitation of low-order guided modes in thin-film InGaN photonic crystal light-emitting diodes
Authors: Rangel Elizabeth , Matioli Elison , Choi Yong-Seok , Weisbuch Claude , Speck James S. , Hu Evelyn L.
Published: February 2011

This letter explores the impact of quantum well placement and photonic crystal (PhC) etch depth on the emission directionality of thin-film InGaN PhC light-emitting diodes (LEDs). The far-field pattern of 800-nm-thick PhC LEDs is tuned by varying only the etch depth of a surface-patterned hexagonal PhC from 90 to 440 nm. This dependence on etch depth is shown to arise from the preferential excitation of a subset of the allowed guided modes. Selective excitation of the TE0 and TE1 modes is utilized to achieve a vertically directional emission pattern comprised of only these two modes.
Propagation of attosecond electron bunches along the cone-and-channel target
Authors: Yang X. H. , Xu H. , Ma Y. Y. , Shao F. Q. , Yin Y. , Zhuo H. B. , Yu M. Y. , Tian C. L.
Published: February 2011

Generation and propagation of attosecond electron bunches along a cone-and-channel target are investigated by particle-in-cell simulation. The target electrons are pulled out by the oscillating electric field of an intense laser pulse irradiating a cone target and accelerated forward along the cone walls. It is shown that the energetic electrons can be further guided and confined by a channel attached to the cone tip. The propagation of these electrons along the channel induces a strong quasistatic magnetic field as well as a sheath electric field since a part of the energetic electrons expands into the surrounding vacuum. The electromagnetic field in turn confines the surface currents. With the cone-and-channel target the energetic electrons can be much better collimated and propagate much farther than that from the classical cone target.
The effect of ZnO surface conditions on the electronic structure of the ZnO/CuPc interface
Authors: Park Sang Han , Kim Hyo Jin , Cho Mann-Ho , Yi Yeonjin , Cho Sang Wan , Yang Jaehyun , Kim Hyoungsub
Published: February 2011

The interfacial electronic structures of zinc oxide (ZnO)/copper-phthalocyanine (CuPc) were investigated by in situ x-ray and ultraviolet photoelectron spectroscopy (UPS) to determine the effects of air contamination on the ZnO substrate. UPS spectra showed that the 0.2 eV of the interface dipole is generated at the interface of the air exposed ZnO/CuPc while the interface of the annealed ZnO/CuPc generated −0.2 eV. In both cases, no band bending was observed. On the other hand, band bending at 0.3 eV and an interface dipole of 0.2 eV were observed at the interface of the sputter cleaned ZnO/CuPc. The energy offset between the conduction band maximum of ZnO and the highest occupied molecular orbital of CuPc was determined to be 0.6–0.7 eV for the contaminated ZnO interface while the offset was 1.0 eV for the cleaned ZnO interface. Contaminating moisture has little effect on the offset while the charge transfer was blocked and the offset was decreased in the presence of hydrocarbons.
Strain-induced negative differential resistance in armchair-edge graphene nanoribbons
Authors: Fang Hui , Wang Ru-Zhi , Chen Si-Ying , Yan Mi , Song Xue-Mei , Wang Bo
Published: February 2011

The transport properties of graphene strips under tensile strain have been theoretically investigated. For the armchair-edge graphene nanoribbons (GNRs) with width N=3m−1, the additional negative differential resistance (NDR) undergoes a process from occurring to enhancement and then disappearance with increasing tensile strain. The changes in the additional NDR may be originated from the suppression of strain-mediated channel states for the variations in degenerate energy bands near Fermi level. The strain-induced NDR behaviors of the GNRs present the possibility of the potential applications in electromechanical nanodevices such as stress-controlled Goto pair for digital signal restoration.
Experimental, finite element, and density-functional theory study of inorganic nanotube compression
Authors: Kalfon-Cohen Estelle , Goldbart Ohad , Schreiber Roy , Cohen Sidney R. , Barlam David , Lorenz Tommy , Joswig Jan-Ole , Seifert Gotthard
Published: February 2011

Interactions between the walls in multiwalled nanotubes are key to determining their mechanical properties. Here, we report studies of radial deformation of multiwalled WS2 nanotubes in an atomic force microscope. The experimental results were fitted to a finite element model to determine the radial modulus. These results are compared with density-functional tight-binding calculations of a double-walled tube. Good agreement was obtained between experiment and calculations. The results indicate the importance of the sliding between layers in moderating the radial modulus. A plateau in the deformation curves is seen to have atomistic origins.
Voltage-controlled insertion of single α-hemolysin and Mycobacterium smegmatis nanopores into lipid bilayer membranes
Authors: Renner Stephan , Bessonov Andrey , Simmel Friedrich C.
Published: February 2011

One of the prerequisites for single molecule nanopore translocation experiments is the availability of a single nanopore embedded into a lipid bilayer membrane. Using two alternative experimental setups, microdroplets, and a classical planar lipid bilayer setup, we here show that at near-neutral pH and high salt concentration the incorporation rates of the pore-forming proteins α-hemolysin and porin A from Mycobacterium smegmatis are exponentially enhanced at elevated voltages. This fact can be utilized to establish an experimental procedure by which a voltage-controlled insertion of single pores into lipid membranes can be achieved.
Formation mechanism of shear bands in ultrafine lamellar Ti–Fe eutectics
Authors: Zhu F. , Tian H. N. , Li X. , Cao G. H. , Gerthsen D. , Oertel C.-G. , Skrotzki W.
Published: February 2011

Shear bands with alternating lamellar and serrated structures were observed on the fracture surface of an Ti–Fe ultrafine eutectic. The shear bands are composed of coalesced subgrains. Hence, a subgrain rotational mechanism is proposed to explain their formation. The work is a direct experimental evidence of the hypothetical rotational mechanism.
Engineering the ferromagnetic domain size for optimized imaging of the pinned uncompensated spins in exchange-biased samples by magnetic force microscopy
Authors: Joshi N. R. , Özer S. , Ashworth T. V. , Stickar P. G. , Romer S. , Marioni M. A. , Hug H. J.
Published: February 2011

Magnetic force microscopy (MFM) is able to image and quantify patterns of pinned uncompensated spins (UCS) in exchange-biased samples with high spatial resolution and submonolayer spin sensitivity. However, MFM can only detect magnetic moment distributions with spatial wavelengths within a certain range. Samples with large domains, homogeneous, or divergence-free magnetization fields are not accessible to MFM analysis. In this work we discuss the sample structure constraints placed by the requirement to measure UCS at high spatial resolution, and point out a method to engineer the size of the ferromagnetic domains accordingly.
Communication: Generalizing Rosenfeld's excess-entropy scaling to predict long-time diffusivity in dense fluids of Brownian particles: From hard to ultrasoft interactions
Authors: Pond Mark J. , Errington Jeffrey R. , Truskett Thomas M.
Published: February 2011

Computer simulations are used to test whether a recently introduced generalization of Rosenfeld's excess-entropy scaling method for estimating transport coefficients in systems obeying molecular dynamics can be extended to predict long-time diffusivities in fluids of particles undergoing Brownian dynamics in the absence of interparticle hydrodynamic forces. Model fluids with inverse-power-law, Gaussian-core, and Hertzian pair interactions are considered. Within the generalized Rosenfeld scaling method, long-time diffusivities of ultrasoft Gaussian-core and Hertzian particle fluids, which display anomalous trends with increasing density, are predicted (to within 20%) based on knowledge of interparticle interactions, excess entropy, and scaling behavior of simpler inverse-power-law fluids.
Oriented polaritons in strongly-coupled asymmetric double quantum well microcavities
Authors: Christmann Gabriel , Askitopoulos Alexis , Deligeorgis George , Hatzopoulos Zacharias , Tsintzos Simeon I. , Savvidis Pavlos G. , Baumberg Jeremy J.
Published: February 2011

Replacing independent single quantum wells inside a strongly-coupled semiconductor microcavity with double quantum wells produces a special type of polariton. Using asymmetric double quantum wells in devices processed into mesas allows the alignment of the electron levels to be voltage-tuned. At the resonant electronic tunneling condition, we demonstrate that “oriented polaritons” are formed, which possess greatly enhanced dipole moments. Since the polariton–polariton scattering rate depends on this dipole moment, such devices could reach polariton lasing, condensation, and optical nonlinearities at much lower threshold powers.
Pharmaceutical Benefits Scheme cost sharing, patient cost consciousness and prescription affordability
Authors: Doran Evan , Robertson Jane , Salkeld Glenn
Published: February 2011

Objective.
To assess patients’ prescription medicine cost consciousness and explore the implications of further cost sharing increases for affordability.

Design and participants.
A telephone interview survey of 818 randomly selected prescription medicine users (408 concession card holders, 410 general beneficiaries) resident in the Hunter Valley region of New South Wales, Australia.

Main outcome measures.
Degree of prescription cost consciousness; attitudes towards prescription use and cost sharing; self-rated capacity to manage further co-payment increases and differences between concession card holders and general beneficiaries in these measures.

Results.
The majority of participants were cost conscious medicine users who act responsibly towards medicine use and believe that cost sharing is appropriate. Although there were no differences in cost consciousness scores, card holders appeared more sensitive to prescription costs and increases. Conversely, general beneficiaries were more likely to report difficulties with cost (avoiding seeing a doctor, not collecting prescription medicines, stopping or reducing the dose of a prescribed medicine). Although almost 75% of respondents reported that a co-payment increase would cause financial difficulty, only 28% indicated this would change their medicine use.

Conclusions.
These results suggest that most Australian patients are cost conscious but many are also close to facing difficulties with prescription costs. Further increases in PBS cost sharing could compromise prescription affordability, particularly for general beneficiaries.

What is known about the topic?
Increased PBS cost sharing is intended to minimise unnecessary demand for prescription medicines while maintaining affordability. The key mechanism to achieve this – ‘cost consciousness’ – has not been investigated.

What does this paper add?
The paper provides patient level data on cost consciousness, attitudes to cost sharing and patient capacity to manage future increases in PBS cost sharing.

What are the implications for practitioners?
Australians are cost conscious. Further increases in PBS cost sharing make some patients even more cost conscious but may also erode affordability, particularly for general beneficiaries. A review of cost sharing is important and long overdue.
Niche of harmful alga
Aureococcus anophagefferens
revealed through ecogenomics
Authors: Gobler Christopher J. , Berry Dianna L. , Dyhrman Sonya T. , Wilhelm Steven W. , Salamov Asaf , Lobanov Alexei V. , Zhang Yan , Collier Jackie L. , Wurch Louie L. , Kustka Adam B. , Dill Brian D. , Shah Manesh , VerBerkmoes Nathan C. , Kuo Alan , Terry Astrid , Pangilinan Jasmyn , Lindquist Erika A. , Lucas Susan , Paulsen Ian T. , Hattenrath-Lehmann Theresa K. , Talmage Stephanie C. , Walker Elyse A. , Koch Florian , Burson Amanda M. , Marcoval Maria Alejandra , Tang Ying-Zhong , LeCleir Gary R. , Coyne Kathryn J. , Berg Gry M. , Bertrand Erin M. , Saito Mak A. , Gladyshev Vadim N. , Grigoriev Igor V.
Published: February 2011

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga
Aureococcus anophagefferens
outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of
A. anophagefferens
and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. Using an ecogenomic approach, we specifically focused on gene sets that may facilitate dominance within the environmental conditions present during blooms.
A. anophagefferens
possesses a larger genome (56 Mbp) and has more genes involved in light harvesting, organic carbon and nitrogen use, and encoding selenium- and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species, with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of
A. anophagefferens
and thus, has facilitated the proliferation of this and potentially other HABs.
Development Planning in Iran: A Historical Survey
Authors: Daftary Farhad
Published: February 2011

By the time the Fifth Development Plan was adopted in 1973, Iran had already experienced more than three decades of governmental efforts towards economic development. These efforts first started in the early 1920s and culminated, in the postwar period, in the country's First Development Plan. Before discussing the second and subsequent plans, it will be useful to review the main features of the initial efforts at planning in Iran.

The development policies of the government during the reign of Reza Shah (1925-1941) did not constitute development planning as the term has come to be understood in the postwar economic literature. The prewar policies were restricted to partial investment programs for the public sector only, with little consideration concerning the activities of the private sector. Furthermore, even the public sector programs did not reflect any explicitly defined set of policy objectives.
Characterization of immunostimulatory components of orf virus (parapoxvirus ovis)
Authors: Friebe Astrid , Friederichs Sonja , Scholz Kai , Janssen Uwe , Scholz Corinna , Schlapp Tobias , Mercer Andrew , Siegling Angela , Volk Hans-Dieter , Weber Olaf
Published: February 2011

Inactivated orf virus (ORFV, parapoxvirus ovis) induces antiviral activity in animal models of acute and chronic viral infections and exerts strong effects on human immune cells. ORFV activates antigen presenting cells (APC) via CD14 and, probably, Toll-like receptor signalling, and triggers the release of IFN-γ that has been identified as the key mediator of the antiviral activity. After delineating virus proteins as being the most likely active constituent, we aimed to characterize the ORFV proteins responsible for the therapeutic effect. By using a vaccinia virus/ORFV expression library we identified several multi-gene DNA fragments with strong immunomodulatory activity. Together these fragments contain 27 ORFs. The encoded proteins are related to virion structure and transcription but are otherwise unrelated. Two proteins were separately expressed and purified, and demonstrated immunostimulatory activity. Gene expression profiles induced by ORFV and the identified fragments were investigated by microarray analysis. Interestingly, all active fragments induced a similar gene-expression pattern, differing only in quantitative aspects. Obviously, several proteins of ORFV activate similar cellular pathways, modulating APC to generate a strong T-helper 1-dominated immune response. This was balanced by additional induction of immune dampening mechanisms, suggesting regulatory differences compared to single cytokine therapies. We conclude that ORFV may have the potential to enrich the armamentarium of antiviral therapies.
Insertion of a multibasic cleavage site in the haemagglutinin of human influenza H3N2 virus does not increase pathogenicity in ferrets
Authors: Schrauwen Eefje J. A. , Bestebroer Theo M. , Munster Vincent J. , de Wit Emmie , Herfst Sander , Rimmelzwaan Guus F. , Osterhaus Albert D. M. E. , Fouchier Ron A. M.
Published: February 2011

A multibasic cleavage site (MBCS) in the haemagglutinin (HA) protein of influenza A virus is a key determinant of pathogenicity in chickens, and distinguishes highly pathogenic avian influenza (HPAI) viruses from low pathogenic avian influenza viruses (LPAI). An MBCS has only been detected in viruses of the H5 and H7 subtypes. Here we investigated the phenotype of a human H3N2 virus with an MBCS in HA. Insertion of an MBCS in the H3N2 virus resulted in cleavage of HA and efficient replication in Madin–Darby canine kidney cells in the absence of exogenous trypsin in vitro, similar to HPAI H5N1 virus. However, studies in ferrets demonstrated that insertion of the MBCS into HA did not result in increased virus shedding, cellular host range, systemic replication or pathogenicity, as compared with wild-type virus. This study indicates that acquisition of an MBCS alone is insufficient to increase pathogenicity of a prototypical seasonal human H3N2 virus.
The prevalence of alcohol use disorders among night‐time weekend drivers
Authors: Furr‐Holden C. Debra , Voas Robert B. , Lacey John , Romano Eduardo , Jones Kristina
Published: February 2011

Aims  The objective of this study was to establish the extent of alcohol use disorders (AUDs) among drivers at risk for alcohol‐related crashes. The prevalence of drivers with AUDs on US roads on weekend evenings when alcohol‐related crashes are most frequent is unknown. This study will inform laws and programs designed to reduce alcohol‐involved crashes.

Design  Interviews using a 15‐item AUD questionnaire with a stratified random sample of non‐commercial drivers at 60 primary sampling locations in the 48 contiguous states on Fridays and Saturdays between 10 p.m. and 3 a.m. from July to November 2007.

Setting  Off‐road locations into which a police officer directed a random selection of motorist passing the site.

Participants  A total of 4614 drivers of non‐commercial vehicles.

Measurements  AUDs, including heavy drinking, alcohol abuse, and alcohol dependence.

Findings  Of the participating drivers, 73.7% were current drinkers (reported drinking in the last year). Among those drinkers, 14% were classifiable either as dependent drinkers or as abusive drinkers based on self‐reports of drinking. Another 10% of the drivers were classified as heavy drinkers. Nearly half of the drivers in the survey who had blood alcohol concentrations (BACs) at or higher than the 0.08 g per deciliter legal limit fell into one of those three AUD categories.

Conclusions  Survey data suggest that the majority of high‐blood alcohol concentration drivers on US roads show no clinical signs of an alcohol use disorder, but they are categorized as heavy drinkers. This suggests that environmental programs directed at reducing heavy drinking and brief behavioral interventions aimed at reducing episodes of excessive consumption have promise for reducing alcohol‐related crashes.
Germination and emergence of Ambrosia artemisiifolia L. under changing environmental conditions in China
Authors: SANG WEIGUO , LIU XINYAN , AXMACHER JAN C.
Published: February 2011

Laboratory and greenhouse studies were conducted to determine the effects of key environmental factors on germination and seedling emergence of the invasive weed Ambrosia artemisiifolia L. (common ragweed) collected from Mudanjiang (temperate climate), Nanjing (temperate–subtropical) and Nanchang (subtropical) in China. Germination of seeds occurred at temperatures ranging from 5 to 40°C, under both a 12‐h photoperiod and continuous darkness. Germination success exceeded 48% in solutions with pH values between 4 and 12, with maximum rates occurring in distilled water at pH 5.57. Germination was greatly reduced in solutions with osmotic potentials below −0.8 MPa. Accordingly, the final germination ratio exceeded 69% at <200 mmol/L NaCl, but only reached 8% at 400 mmol/L NaCl. Emergence was greater than 75% at burial seed depths of 1–4 cm; no seedlings emerged from a soil depth of 8 cm. Seeds collected from Mudanjiang, Nanjing and Nanchang had very similar germination traits, with the main differences occurring in relation to temperature. The great germination success of common ragweed over highly variable conditions throughout its Chinese distribution range explains its successful large‐scale invasion.
Assessment of Load Extrapolation Methods for Wind Turbines
Authors: Toft Henrik Stensgaard , Sørensen John Dalsgaard , Veldkamp Dick
Published: February 2011

In the present paper, methods for statistical load extrapolation of wind-turbine response are studied using a stationary Gaussian process model, which has approximately the same spectral properties as the response for the out-of-plane bending moment of a wind-turbine blade. For a Gaussian process, an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper, three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima, and the peak over threshold method with two different threshold values. The comparisons show that the goodness of fit for the local distribution has a significant influence on the results, but the peak over threshold method with a threshold value on the mean plus 1.4 standard deviations generally gives the best results. By considering Gaussian processes for 12 mean wind speeds, the “fitting before aggregation” and “aggregation before fitting” approaches are studied. The results show that the fitting before aggregation approach gives the best results.
Acoustic ship signature measurements by cross-correlation method
Authors: Fillinger Laurent , Sutin Alexander , Sedunov Alexander
Published: February 2011

Cross-correlation methods were applied for the estimation of the power spectral density and modulation spectrum of underwater noise generated by moving vessels. The cross-correlation of the signal from two hydrophones allows the separation of vessel acoustic signatures in a busy estuary. Experimental data recorded in the Hudson River are used for demonstration that cross-correlation method measured the same ship noise and ship noise modulation spectra as conventional methods. The cross-correlation method was then applied for the separation of the acoustic signatures of two ships present simultaneously. Presented methods can be useful for ship traffic monitoring and small ship classification, even in noisy harbor environments.
Long-time trends in ship traffic noise for four sites off the North American West Coast
Authors: Andrew Rex K. , Howe Bruce M. , Mercer James A.
Published: February 2011

Measurements (1994–2007) from four cabled-to-shore hydrophone systems located off the North American west coast permit extensive comparisons between “contemporary” low frequency ship traffic noise (25–50 Hz) collected in the past decade to measurements made over 1963–1965 with the same in-water equipment at the same sites. An increase of roughly 10 dB over the band 25–40 Hz at one site has already been reported [Andrew et al., Acoust. Res. Lett. Online 3(2), 65–70 (2002)]. Newly corrected data from the remaining three systems generally corroborate this increase. Simple linear trend lines of the contemporary traffic noise (duration 6 to 12+ years) show that recent levels are slightly increasing, holding steady, or decreasing. These results confirm the prediction by Ross that the rate of increase in traffic noise would be far less at the end of the 20th century compared to that observed in the 1950s and 1960s.
Estimating fish orientation from broadband, limited-angle, multiview, acoustic reflections
Authors: Jaffe Jules S. , Roberts Paul L. D.
Published: February 2011

This article demonstrates that multiview, broadband (635–935 kHz), nearly monostatic, acoustic reflections recorded from lateral views of juvenile fish can be used to infer animal orientation. Calibrated acoustic data were recorded from live fish in a laboratory, while orientation was measured simultaneously via optical images. Using eight animals, two-dimensional data sets of target strength as a function of frequency and orientation were obtained. Fish length, lateral thickness, and dorsoventral thickness ranged from 24 to 48 mm, 3 to 7 mm and 10 to 20 mm, respectively. Preliminary estimates of orientation were computed from the direction of the gradient of the local autocorrelation function in the target strength image. These local estimates were then median-filtered over the full system bandwidth (but still limited-angle) to improve accuracy. Angular estimates were then corrected for systematic bias via a simple, one-dimensional model that approximated the animals’ reflection by that of a bar target. Taken over all orientations, the average absolute error in orientation estimation is 5.6° to 17°, dependent on the data set. Results indicate, for most sets of views, reasonable estimates of lateral orientation can be obtained from broadband, multiview data over a set of limited angular reflections.
Measuring positive and negative affect in the voiced sounds of African elephants (Loxodonta africana)
Authors: Soltis Joseph , Blowers, Tracy E. , Savage Anne
Published: February 2011

As in other mammals, there is evidence that the African elephant voice reflects affect intensity, but it is less clear if positive and negative affective states are differentially reflected in the voice. An acoustic comparison was made between African elephant “rumble” vocalizations produced in negative social contexts (dominance interactions), neutral social contexts (minimal social activity), and positive social contexts (affiliative interactions) by four adult females housed at Disney’s Animal Kingdom®. Rumbles produced in the negative social context exhibited higher and more variable fundamental frequencies (F0) and amplitudes, longer durations, increased voice roughness, and higher first formant locations (F1), compared to the neutral social context. Rumbles produced in the positive social context exhibited similar shifts in most variables (F0 variation, amplitude, amplitude variation, duration, and F1), but the magnitude of response was generally less than that observed in the negative context. Voice roughness and F0 observed in the positive social context remained similar to that observed in the neutral context. These results are most consistent with the vocal expression of affect intensity, in which the negative social context elicited higher intensity levels than the positive context, but differential vocal expression of positive and negative affect cannot be ruled out.
Nonlinear waves and shocks in a rigid acoustical guide
Authors: Fernando Rasika , Druon Yann , Coulouvrat François , Marchiano Régis
Published: February 2011

A model is developed for the propagation of finite amplitude acoustical waves and weak shocks in a straight duct of arbitrary cross section. It generalizes the linear modal solution, assuming mode amplitudes slowly vary along the guide axis under the influence of nonlinearities. Using orthogonality properties, the model finally reduces to a set of ordinary differential equations for each mode at each of the harmonics of the input frequency. The theory is then applied to a two-dimensional waveguide. Dispersion relations indicate that there can be two types of nonlinear interactions either called “resonant” or “non-resonant.” Resonant interactions occur dominantly for modes propagating at a rather large angle with respect to the axis and involve mostly modes propagating with the same phase velocity. In this case, guided propagation is similar to nonlinear plane wave propagation, with the progressive steepening up to shock formation of the two waves that constitute the mode and reflect onto the guide walls. Non-resonant interactions can be observed as the input modes propagate at a small angle, in which case, nonlinear interactions involve many adjacent modes having close phase velocities. Grazing propagation can also lead to more complex phenomena such as wavefront curvature and irregular reflection.
Irregular array motion and extended integration for the suppression of spatial aliasing in passive sonar
Authors: Chang Enson
Published: February 2011

Conventional synthetic aperture processing uses motion of the sonar to increase aperture size and bearing resolution. Two recent papers discussed a different application in which synthetic elements are used to fill in an otherwise sparse passive array. This paper points out that ambiguities persist, even with synthetic elements, in the ideal case of a straight, uniform, sparse line array with constant velocity in the presence of plane wave signals. It is also shown that irregular motion such as acceleration introduces additional information which can be exploited to suppress the ambiguities. The degree of suppression in such an approach is independent of signal direction. If source stability supports extended coherent integration, then the acceleration and integration time required are both modest to achieve interesting levels of suppression. For a less stable source, a modified conventional beamformer is introduced which leverages acceleration over multiple snapshots to suppress the ambiguities. A post-beamformed processing stage involving a nonlinear deconvolution technique such as the CLEAN algorithm can further improve the result. A semi-coherent adaptation of CLEAN is shown to remove the residual ambiguities effectively in the presence of a moderate level of uncorrelated noise.
Discrimination of temporally asymmetric modulation with triangular envelopes on a broadband-noise carrier (L)
Authors: Byrne Andrew J. , Viemeister Neal F. , Stellmack Mark A.
Published: February 2011

Highly detectable, time-reversed triangular amplitude modulation, with linear increases and decreases in amplitude, was used in an adaptive task to measure just-noticeable differences for changes in the direction of envelope temporal asymmetry for different modulation depths (m = 1.0 and 0.5) and rates (8, 16, and 32 Hz). Thresholds were analyzed using three different measures of the modulator’s shape based on (1) the change in the position of the peak within a cycle, (2) the change in the slope of the modulator’s increasing amplitude portion, and (3) the change in slope measured in units of amplitude per unit cycle rather than amplitude per unit time. The amplitude per unit cycle measure resulted in the best fit to all the data, and predicted additional data that were gathered with roved modulation frequency. The results suggest that a time normalization process may be involved in the perception and discrimination of envelope shape.
Beaked whale (Mesoplodon densirostris) passive acoustic detection in increasing ambient noise
Authors: Ward Jessica , Jarvis Susan , Moretti David , Morrissey Ronald , DiMarzio Nancy , Johnson Mark , Tyack Peter , Thomas Len , Marques Tiago
Published: February 2011

Passive acoustic detection is being increasingly used to monitor visually cryptic cetaceans such as Blainville’s beaked whales (Mesoplodon densirostris) that may be especially sensitive to underwater sound. The efficacy of passive acoustic detection is traditionally characterized by the probability of detecting the animal’s sound emissions as a function of signal-to-noise ratio. The probability of detection can be predicted using accepted, but not necessarily accurate, models of the underwater acoustic environment. Recent field studies combining far-field hydrophone arrays with on-animal acoustic recording tags have yielded the location and time of each sound emission from tagged animals, enabling in-situ measurements of the probability of detection. However, tagging studies can only take place in calm seas and so do not reflect the full range of ambient noise conditions under which passive acoustic detection may be used. Increased surface-generated noise from wind and wave interaction degrades the signal-to-noise ratio of animal sound receptions at a given distance leading to a reduction in probability of detection. This paper presents a case study simulating the effect of increasing ambient noise on detection of M. densirostris foraging clicks recorded from a tagged whale swimming in the vicinity of a deep-water, bottom-mounted hydrophone array.
Rayleigh–Lamb wave propagation on a fractional order viscoelastic plate
Authors: Meral F. Can , Royston Thomas J. , Magin Richard L.
Published: February 2011

A previous study of the authors published in this journal focused on mechanical wave motion in a viscoelastic material representative of biological tissue [Meral et al., J. Acoust. Soc. Am. 126, 3278–3285 (2009)]. Compression, shear and surface wave motion in and on a viscoelastic halfspace excited by surface and sub-surface sources were considered. It was shown that a fractional order Voigt model, where the rate-dependent damping component that is dependent on the first derivative of time is replaced with a component that is dependent on a fractional derivative of time, resulted in closer agreement with experiment as compared with conventional (integer order) models, such as those of Voigt and Zener. In the present study, this analysis is extended to another configuration and wave type: out-of-plane response of a viscoelastic plate to harmonic anti-symmetric Lamb wave excitation. Theoretical solutions are compared with experimental measurements for a polymeric tissue mimicking phantom material. As in the previous configurations the fractional order modeling assumption improves the match between theory and experiment over a wider frequency range. Experimental complexities in the present study and the reliability of the different approaches for quantifying the shear viscoelastic properties of the material are discussed.
Low-frequency sound transmission through a gas–solid interface
Authors: Godin Oleg A.
Published: February 2011

Sound transmission through gas–solid interfaces is usually very weak because of the large contrast in wave impedances at the interface. Here, it is shown that diffraction effects can lead to a dramatic increase in the transparency of gas–solid interfaces at low frequencies, resulting in the bulk of energy emitted by compact sources within a solid being radiated into a gas. The anomalous transparency is made possible by power fluxes in evanescent body waves and by excitation of interface waves. Sound transmission into gas is found to be highly sensitive to absorption of elastic waves within a solid.
Science Starts Early
Authors: Keil Frank C.
Published: February 2011

Infants and children grasp surprisingly sophisticated correlational and causal patterns.
Bringing the Museum into the Classroom
Authors: Gano Steve , Kinzler Ro
Published: February 2011

Digital modules for online resources and good metadata help teachers find the museum's rich, authoritative science content to use in their classrooms.
Synthesis, Structure, and Reactivity of an Iron(V) Nitride
Authors: Scepaniak Jeremiah J. , Vogel Carola S. , Khusniyarov Marat M. , Heinemann Frank W. , Meyer Karsten , Smith Jeremy M.
Published: February 2011

A reactive iron compound bound to nitrogen has been isolated in an unusually high oxidation state.
Development of Transgenic Fungi That Kill Human Malaria Parasites in Mosquitoes
Authors: Fang Weiguo , Vega-Rodríguez Joel , Ghosh Anil K. , Jacobs-Lorena Marcelo , Kang Angray , St. Leger Raymond J.
Published: February 2011

Insect-specific fungi can be used to deliver a range of toxins, antibodies, and other agents to kill vector-born pathogens.
The Developmental Role of Agouti in Color Pattern Evolution
Authors: Manceau Marie , Domingues Vera S. , Mallarino Ricardo , Hoekstra Hopi E.
Published: February 2011

A regulatory mutation affecting expression of the
Agouti
gene shows color-specific selection in beach mice.
Transient Regenerative Potential of the Neonatal Mouse Heart
Authors: Porrello Enzo R. , Mahmoud Ahmed I. , Simpson Emma , Hill Joseph A. , Richardson James A. , Olson Eric N. , Sadek Hesham A.
Published: February 2011

The heart in a newborn mouse can rebuild itself after injury, but this regenerative capacity is lost within a few days.
A Terminal Pleistocene Child Cremation and Residential Structure from Eastern Beringia
Authors: Potter Ben A. , Irish Joel D. , Reuther Joshua D. , Gelvin-Reymiller Carol , Holliday Vance T.
Published: February 2011

Cremated remains and a burial site in central Alaska provide information on early humans in North America.
Socializing Genetic Diseases
Authors: Rabeharisoa Vololona
Published: February 2011

The fact that complete genome sequences are now available has had effects on patient advocacy.
Beyond Human: New Faces, Fields Exploit Genomics
Authors: Pennisi Elizabeth
Published: February 2011

Fast new genomics technology is not just for human geneticists and biomedical researchers anymore.