bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular structural property and potential energy dependence on nonequilibrium-thermodynamic state point of liquid n-hexadecane under shear
Authors: Tseng Huan-Chang , Chang Rong-Yeu , Wu Jiann-Shing
Published: January 2011

Extensive computer experiments have been conducted in order to shed light on the macroscopic shear flow behavior of liquid n-hexadecane fluid under isobaric–isothermal conditions through the nonequilibrium molecular dynamic methodology. With respect to shear rates, the accompanying variations in structural properties of the fluid span the microscopic range of understanding from the intrinsic to extrinsic characteristics. As drawn from the average value of bond length and bond angle, the distribution of dihedral angle, and the radius distribution function of intramolecular and intermolecular van der Waals distances, these intrinsic structures change with hardness, except in the situation of extreme shear rates. The shear-induced variation of thermodynamic state curve along with the shear rate studied is shown to consist of both the quasiequilibrium state plateau and the nonequilibrium-thermodynamic state slope. Significantly, the occurrence of nonequilibrium-thermodynamic state behavior is attributed to variations in molecular potential energies, which include bond stretching, bond bending, bond torsion, and intra- and intermolecular van der Waals interactions. To unfold the physical representation of extrinsic structural deformation, under the aggressive influence of a shear flow field, the molecular dimension and appearance can be directly described via the squared radius of gyration and the sphericity angle, Rg2 and φ, respectively. In addition, a specific orientational order Sx defines the alignment of the molecules with the flow direction of the x-axis. As a result, at low shear rates, the overall molecules are slightly stretched and shaped in a manner that is increasingly ellipsoidal. Simultaneously, there is an obvious enhancement in the order. In contrast to high shear rates, the molecules spontaneously shrink themselves with a decreased value of Rg2, while their shape and order barely vary with an infinite value of φ and Sx. It is important to note that under different temperatures and pressures, these three parameters are integrated within a molecular description in response to thermodynamic state variable of density and rheological material function of shear viscosity.
A numerical study of compressible turbulent boundary layers
Authors: Lagha M. , Kim J. , Eldredge J. D. , Zhong X.
Published: January 2011

Compressible turbulent boundary layers with free-stream Mach number ranging from 2.5 up to 20 are analyzed by means of direct numerical simulation of the Navier–Stokes equations. The fluid is assumed to be an ideal gas with constant specific heats. The simulation generates its inflow condition using the rescaling-recycling method. The main objective is to study the effect of Mach number on turbulence statistics and near-wall turbulence structures. The present study shows that supersonic/hypersonic boundary layers at zero pressure gradient exhibit close similarities to incompressible boundary layers and that the main turbulence statistics can be correctly described as variable-density extensions of incompressible results. The study also shows that the spanwise streak’s spacing of 100 wall units in the inner region (y+≈15) still holds for the considered high Mach numbers. The probability density function of the velocity dilatation shows significant variations as the Mach number is increased, but it can also be normalized by accounting for the variable-density effect. The compressible boundary layer also shows an additional similarity to the incompressible boundary layer in the sense that without the linear coupling term, near-wall turbulence cannot be sustained.
Defect dynamics and spectral observation of twinning in single crystalline LaAlO3 under subbandgap excitation
Authors: Chen J. Q. , Wang X. , Lu Y. H. , Roy Barman A. , You G. J. , Xing G. C. , Sum T. C. , Dhar S. , Feng Y. P. , Ariando  , Xu Q.-H. , Venkatesan T.
Published: January 2011

We have investigated the photoluminescence and ultrafast dynamics of LaAlO3 crystal. The photoluminescence consists of a broad spectrum and two sharp peaks, which arise from various defect levels within the bandgap. A doublet splitting of roughly 6 nm is seen in these two sharp peaks. An Al displacement of 0.09 Å in a sublattice, which is possible because of twinning, is adequate to explain the spectral splitting. Femtosecond pump probe experiments reveal further that many of these defect levels have a few picosecond decay times while the lowest defect states have decay times longer than nanosecond to the valence band.
Kinetic depinning of a magnetic domain wall above the Walker field
Authors: Lewis E. R. , Petit D. , O’Brien L. , Jausovec A.-V. , Zeng H. T. , Read D. E. , Cowburn R. P.
Published: January 2011

The dynamical interaction between a transverse domain wall and a T-shaped trap is investigated, for domain wall motion in the oscillatory regime above the Walker field. We demonstrate experimentally the existence of distinct static and kinetic depinning fields in this regime, and show that the oscillatory motion of the domain wall leads to a distribution of kinetic depinning fields. Micromagnetic simulations are in good qualitative agreement with our experimental results.
Top-down fabrication of AlGaN/GaN nanoribbons
Authors: Azize M. , Palacios T.
Published: January 2011

Lateral AlGaN/GaN nanoribbons (NRs) have been fabricated through a top-down technology on planar AlGaN/GaN samples grown on a silicon substrate. Electron-beam lithography and Cl2-based dry etching were used to define the NRs with widths in the 70–145 nm range. The electrical and structural properties of the AlGaN/GaN NRs have been measured and compared to standard planar structures fabricated on the same chip. External mechanical stress and adequate surface passivation have an important effect on the NR’s performance. A 50% improvement in the current density of SixNy passivated AlGaN/GaN NRs was obtained with respect to planar samples.
Single-crystalline (100) Ge networks on insulators by rapid-melting growth along hexagonal mesh-pattern
Authors: Toko Kaoru , Ohta Yasuharu , Sakane Takashi , Sadoh Taizoh , Mizushima Ichiro , Miyao Masanobu
Published: January 2011

Single-crystalline-Ge (c-Ge) networks on insulator films formed on Si substrates are essential for integrating high-speed and multifunctional devices onto the Si-platform. Rapid-melting-growth of mesh-patterned amorphous-Ge is examined over large areas (500×250 μm2). For squared-mesh-pattern, polycrystalline-Ge forms throughout most of the mesh, though c-Ge is obtained near (<100 μm) Si-seed. Based on the consideration of geometric-effects, mesh-patterns are changed to hexagonal. This realizes c-Ge networks over the entire insulator area. These results indicate that Ge growth initiated from Si-seed propagates laterally over the hexagonal-mesh-pattern though bending and branching. These unique c-Ge-networks on insulators facilitate Ge-based advanced-devices on the Si-platform.
Excited electron-bubble states in superfluid 4He: A time-dependent density functional approach
Authors: Mateo David , Jin Dafei , Barranco Manuel , Pi Martí
Published: January 2011

We present a systematic study on the excited electron-bubble states in superfluid \documentclass[12pt]{minimal}\begin{document}$^4$\end{document}4He using a time-dependent density functional approach. For the evolution of the 1P bubble state, two different functionals accompanied with two different time-development schemes are used, namely an accurate finite-range functional for helium with an adiabatic approximation for electron versus an efficient zero-range functional for helium with a real-time evolution for electron. We make a detailed comparison between the quantitative results obtained from the two methods, which allow us to employ with confidence the optimal method for suitable problems. Based on this knowledge, we use the finite-range functional to calculate the time-resolved absorption spectrum of the 1P bubble, which in principle can be experimentally determined, and we use the zero-range functional to real-time evolve the 2P bubble for several hundreds of picoseconds, which is theoretically interesting due to the break down of adiabaticity for this state. Our results discard the physical realization of relaxed, metastable configurations above the 1P state.
Magnetic microstructure and magnetotransport in Co2FeAl Heusler compound thin films
Authors: Weiler Mathias , Czeschka Franz D. , Brandlmaier Andreas , Imort Inga-Mareen , Reiss Günter , Thomas Andy , Woltersdorf Georg , Gross Rudolf , Goennenwein Sebastian T. B.
Published: January 2011

We correlate simultaneously recorded magnetotransport and spatially resolved magneto-optical Kerr effect (MOKE) data in Co2FeAl Heusler compound thin films micropatterned into Hall bars. Room temperature MOKE images reveal the nucleation and propagation of domains in an externally applied magnetic field and are used to extract a macrospin corresponding to the mean magnetization direction in the Hall bar. The anisotropic magnetoresistance calculated using this macrospin is in excellent agreement with magnetoresistance measurements. This suggests that the magnetotransport in Heusler compounds can be adequately simulated using simple macrospin models, while the magnetoresistance contribution due to domain walls is of negligible importance.
Toward making the mean spherical approximation of primitive model electrolytes analytic: An analytic approximation of the MSA screening parameter
Authors: Gillespie Dirk
Published: January 2011

The mean spherical approximation (MSA) for the primitive model of electrolytes provides reasonable estimates of thermodynamic quantities such as the excess chemical potential and screening length. It is especially widely used because of its explicit formulas so that numerically solving equations is minimized. As originally formulated, the MSA screening parameter Γ (akin to the reciprocal of the Debye screening length) does not have an explicit analytic formula; an equation for Γ must be solved numerically. Here, an analytic approximation for Γ is presented whose relative error is generally \documentclass[12pt]{minimal}\begin{document}$\lesssim 10^{-5}$\end{document}≲10−5. If more accuracy is desired, one step of an iterative procedure (which also produces an explicit formula for Γ) is shown to give relative errors within machine precision in many cases. Even when ion diameter ratios are ∼10 and ion valences are ∼10, the relative error for the analytic approximation is still \documentclass[12pt]{minimal}\begin{document}$\lesssim 10^{-3}$\end{document}≲10−3 and for the single iterative substitution it is \documentclass[12pt]{minimal}\begin{document}$\lesssim 10^{-9}$\end{document}≲10−9.
Unpolarized H1 photonic crystal nanocavities fabricated by stretched lattice design
Authors: Luxmoore I. J. , Ahmadi E. D. , Fox A. M. , Hugues M. , Skolnick M. S.
Published: January 2011

We investigate the factors that affect the mode splitting in H1 planar photonic crystal cavities and hence demonstrate unpolarized emission with a high quality factor. Finite difference time domain simulations show that systematic errors in the fabrication process such as hole shape and period lift the degeneracy of the orthogonally polarized fundamental modes. By intentionally stretching the photonic crystal lattice in one direction, we show that the wavelength and mode splitting can be tuned to compensate for such fabrication errors. By using this technique, we demonstrate unpolarized emission at 951 nm with a quality factor of ∼4500.
Li+ alumino-silicate ion source development for the neutralized drift compression experiment
Authors: Roy Prabir K. , Greenway Wayne G. , Kwan Joe W. , Seidl Peter A. , Waldron William L. , Wu James K.
Published: January 2011

We report results on lithium alumino-silicate ion source development in preparation for warm dense matter heating experiments on the new neutralized drift compression experiment II. The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ≈1275 °C, a space-charge limited Li+ beam current density of J ≈1 mA/cm2 was obtained. The lifetime of the ion source was ≈50 h while pulsing at a rate of 0.033 Hz with a pulse duration of 5–6 μs.
Benchmarking the multipole shielding polarizability/reaction field approach to solvation against QM/MM: Applications to the shielding constants of N-methylacetamide
Authors: Kjær Hanna , Sauer Stephan P. A. , Kongsted Jacob
Published: January 2011

We present a benchmark study of a combined multipole shielding polarizability/reaction field (MSP/RF) approach to the calculation of both specific and bulk solvation effects on nuclear magnetic shielding constants of solvated molecules. The MSP/RF scheme is defined by an expansion of the shielding constants of the solvated molecule in terms of electric field and field gradient property derivatives derived from single molecule ab initio calculations. The solvent electric field and electric field gradient are calculated based on data derived from molecular dynamics simulations, thereby accounting for solute–solvent dynamical effects. The MSP/RF method is benchmarked against polarizable quantum mechanics/molecular mechanics (QM/MM) calculations. The best agreement between the MSP/RF and QM/MM approaches is found by truncating the electric field expansion in the MSP/RF approach at the linear electric field level which is due to the cancelation of errors. In addition, we investigate the sensitivity of the results due to the choice of one-electron basis set in the ab initio calculations of the property derivatives and find that these derivatives are affected by the basis set in a way similar to the shielding constants themselves.
Elastic granular flows of ellipsoidal particles
Authors: Campbell Charles S.
Published: January 2011

Granular flow rheology can be divided into two global regimes: the elastic, which is dominated by force chains, and the inertial, which is nearly free of force chains. As the propensity of a material to form force chains should be strongly influenced by particle shape, this paper is an attempt to assess the effects of shape on flow regime transitions through computer simulations of shear flow of ellipsoidal particles. On one hand, the results show that at a given concentration, ellipsoidal particles generate smaller quasistatic stress than spheres, likely a result of their ability to form denser packings. But at the same time, large aspect ratio ellipsoids more readily form force chains and demonstrate elastic behavior at smaller concentrations than spheres. This is shown to be due to a tradeoff between a shear-induced particle alignment that tends to minimize the interference of the particles and the shear flow, and the particle surface friction, which works to rotate the particles into the flow.
Beyond the Nernst-limit with dual-gate ZnO ion-sensitive field-effect transistors
Authors: Spijkman M. , Smits E. C. P. , Cillessen J. F. M. , Biscarini F. , Blom P. W. M. , de Leeuw D. M.
Published: January 2011

The sensitivity of conventional ion-sensitive field-effect transistors (ISFETs) is limited to 59 mV/pH, which is the maximum detectable change in electrochemical potential according to the Nernst equation. Here we demonstrate a transducer based on a ZnO dual-gate field-effect transistor that breaches this boundary. To enhance the response to the pH of the electrolyte, a self-assembled monolayer has been used as a top gate dielectric. The sensitivity scales linearly with the ratio between the top and bottom gate capacitances. The sensitivity of our ZnO ISFET of 22 mV/pH is enhanced by more than two orders of magnitude up to 2.25 V/pH.
Semitransparent organic solar cells with organic wavelength dependent reflectors
Authors: Galagan Yulia , Debije Michael G. , Blom Paul W. M.
Published: January 2011

Semitransparent organic solar cells employing solution-processable organic wavelength dependent reflectors of chiral nematic (cholesteric) liquid crystals are demonstrated. The cholesteric liquid crystal (CLC) reflects only in a narrow band of the solar spectrum and remains transparent for the remaining wavelengths. The reflective band is matched to the absorption spectrum of the organic solar cell such that only unabsorbed photons that can contribute to the photocurrent are reflected to pass through the active layer a second time. In this way, the efficiency of semitransparent organic solar cells can be enhanced without significant transparency losses. An efficiency increase of 6% was observed when a CLC reflector with a reflection band of 540–620 nm was used, whereas the transparency of the organic solar cells is only suppressed in the 80 nm narrow bandwidth.
Hole-channel conductivity in epitaxial graphene determined by terahertz optical-Hall effect and midinfrared ellipsometry
Authors: Hofmann T. , Boosalis A. , Kühne P. , Herzinger C. M. , Woollam J. A. , Gaskill D. K. , Tedesco J. L. , Schubert M.
Published: January 2011

We report noncontact, optical determination of free-charge carrier mobility, sheet density, and resistivity parameters in epitaxial graphene at room temperature using terahertz and midinfrared ellipsometry and optical-Hall effect measurements. The graphene layers are grown on Si- and C-terminated semi-insulating 6H silicon carbide polar surfaces. Data analysis using classical Drude functions and multilayer modeling render the existence of a p-type channel with different sheet densities and effective mass parameters for the two polar surfaces. The optically obtained parameters are in excellent agreement with results from electrical Hall effect measurements.
Effect of vacancy-type oxygen deficiency on electronic structure in amorphous alumina
Authors: Momida Hiroyoshi , Nigo Seisuke , Kido Giyuu , Ohno Takahisa
Published: January 2011

Electronic and atomic structures associated with a vacancy-type oxygen deficiency in an amorphous alumina model are studied by first-principles calculations. The energy levels of the oxygen defects significantly shift depending on their charge states because of remarkable changes of local atomic structures. That is different in character from the α crystal case. We discuss a possibility of the oxygen defects as a conductive path and present an atomistic mechanism of the resistive switching effects in the memory devices.
Limiting performance analysis of cascaded interband/intersubband thermophotovoltaic devices
Authors: Yin Jian , Paiella Roberto
Published: January 2011

This work addresses the question of how much electrical power can in principle be extracted from heat radiation via the combined use of interband and intersubband photodetection as a way to overcome the fundamental limitations of existing thermophotovoltaic devices using mature InP-based technology. Very efficient coverage of the incident radiation spectrum and optimal current matching can be achieved using multiple quantum-cascade structures monolithically integrated with a p-n junction by taking advantage of their intrinsic cascading scheme, spectral agility, and design flexibility. Numerical simulations indicate that this approach can effectively double the present state-of-the-art in thermophotovoltaic output electrical power.
Optofluidic Fabry–Pérot cavity biosensor with integrated flow-through micro-/nanochannels
Authors: Guo Yunbo , Li Hao , Reddy Karthik , Shelar Hrishikesh S. , Nittoor Vasuki R. , Fan Xudong
Published: January 2011

An optofluidic Fabry–Pérot cavity label-free biosensor with integrated flow-through micro-/nanochannels is proposed and demonstrated, which takes advantages of the large surface-to-volume ratio for analyte concentration and high detection sensitivity and built-in fluidic channels for rapid analyte delivery. The operating principle is first discussed, followed by assembly of a robust sensing system. Real-time measurements are performed to test its sensing feasibility and capability including bulk solvent change and removal/binding of molecules from/onto the internal surface of fluidic channels. The results show that this sensor provides a very promising platform for rapid, sensitive, and high-throughput biological and chemical sensing.
Influence of ultrathin amorphous silicon layers on the nucleation of microcrystalline silicon films under hydrogen plasma treatment
Authors: Zuo Z. W. , Guan W. T. , Wang Y. , Lu J. , Wang J. Z. , Pu L. , Shi Y. , Zheng Y. D. , Luo X. Y. , Wang H. H.
Published: January 2011

Microstructures of phosphorus-doped hydrogenated microcrystalline silicon (μc-Si:H) thin films deposited by plasma-enhanced chemical vapor deposition are certainly dependent on the thickness of the H2 plasma-treated amorphous silicon (a-Si:H) layers. An ultrathin H-treated a-Si:H layer is beneficial in obtaining a very thin μc-Si:H film with high conductivity. Experimental results indicate that H2 plasma treatment induces the occurrence of high-pressure H2 in microvoids and causes compressive stress inside the ultrathin a-Si:H layers, thereby enhancing the generation of strained Si–Si bonds and nucleation sites and consequently accelerating the nucleation of μc-Si:H films.
Phase diagram of spherical particles interacted with harmonic repulsions
Authors: Zhu You-Liang , Lu Zhong-Yuan
Published: January 2011

We construct the phase diagram of spherical particles interacted with harmonic repulsions, which are ultrasoft and bounded at fully overlapping. This simple potential form can be used for describing the thermodynamic properties and dynamic behavior of interpenetrable globular micelles, microgels, starlike polymer solutions, and so on. Using dissipative particle dynamics simulations combined with thermodynamic integration, we compute chemical potentials of fluid phase and a number of crystal structures. In addition to the face-centered cubic and body-centered cubic structures, we also find the tetragonal, hexagonal, orthorhombic, and diamond crystal structures stable for this system. In the phase diagram, we identify multiple re-entrant melting regions and polymorphic transitions between the crystals.
Misfit relaxation of La0.7Sr0.3MnO3 thin films by a nanodot segregation mechanism
Authors: Abellán P. , Moreno C. , Sandiumenge F. , Obradors X. , Casanove M.-J.
Published: January 2011

Partially segregated La0.7Sr0.3MnO3 (LSMO) nanocomposite films are shown to exhibit a thickness dependent self-assembled structure. The morphological evolution of the nanocomposite and the misfit strain of the LSMO phase are linked through the topological distribution of La–Sr oxide nanodots within the film. Misfit relaxation occurs above a critical thickness, hc, coinciding with the nucleation of La–Sr oxide nanodots at the film-substrate interface. Below hc, the same dots outcrop the film surface, forming islands. As a consequence of this misfit relaxation mechanism, an enhancement in the magnetoresistance with increasing thickness is measured.
Can a Mediterranean diet reduce the effects of lipodystrophy syndrome in people living with HIV? A pilot randomised controlled trial
Authors: Ng Geraldine Wai Bik , Chan Una Man Shu , Li Patrick Chung Ki , Wong William C. W.
Published: January 2011

Background: HIV and highly active antiretroviral therapies have been associated with changes in individuals’ lipid profiles and fat distribution (lipodystrophy). A pilot study was conducted for a randomised controlled trial to evaluate whether lipodystrophy in HIV patients can be controlled by adopting the low-fat and low-cholesterol diet or the modified Mediterranean diet. Methods: Forty-eight HIV patients were randomised into two diet groups. Thirty-six (75%) completed the 1-year pilot study with regular dietetic consultations, during which time lipid levels, weight, body mass index and fat distribution were recorded. Differences between and within groups were determined. Results: Undesirable body fat changes in the low-fat diet group included decreases in tricep skinfold (from 19.9 mm to 15.4 mm (P = 0.03)), hip circumference (from 93.6 cm to 91.7 cm (P = 0.01)) but a significant increase in waist-to-hip ratio (from 0.87 to 0.89 (P = 0.003)). Serum cholesterol increased significantly in the Mediterranean diet group at 9 and 12 months (from 4.6 to 5.06 mmol L−1 (P = 0.03) and 5.12 mmol L−1 (P = 0.01)) with no obvious change in the low-fat diet group. Serum triglyceride levels remained the same in the Mediterranean diet group, whereas it increased from 1.9 to 3.22 mmol L−1 (P = 0.07) in the low-fat diet group. Conclusions: A Mediterranean diet seems to have an advantage over the low-fat diet in maintaining serum triglyceride levels and avoiding lipodystrophy, but this advantage was offset by a rise in cholesterol level. Several procedural and methodological issues were identified which must be rectified before a similar large-scale trial taking place.
Low yield of anogenital examination among asymptomatic clients of an urban sexual health clinic
Authors: Yong Ma Jun , Ryder Nathan , Wray Lynne , McNulty Anna
Published: January 2011

Background: The use of self-collected specimens to test for sexually transmissible infections (STI) has reduced the opportunity for physical examination. Physical examination has been found to be of limited value in asymptomatic heterosexual women and men; however, prior studies have excluded higher risk populations. We performed a retrospective cross-sectional study to determine the diagnostic yield of physical examination among all clients attending our sexual health service. Methods: The Sydney Sexual Health Centre database was used to identify asymptomatic clients attending for the first time between January and June 2009. Demographic and behavioural data were extracted from the database for all clients. Medical records were then manually reviewed to determine the number and nature of diagnoses related to the examination and whether this varied by sex and sex of sexual partners. Results: Of the 590 clients included, 450 (76%) received anogenital examinations. Ten (2.2%; 95% confidence interval 1.1–4.1%) STI were found, including four cases of cervicitis, four of anogenital warts and two of molluscum. Nineteen (4.2%) other non-STI conditions were detected, mostly in heterosexual women and men who have sex with men (MSM). Conclusion: Physical examination of asymptomatic clients attending our sexual health clinic was of limited value, even among higher risk individuals such as MSM. Sexual health clinics should direct resources currently used to examine clients towards increasing the STI testing rate.
‘If your husband calls, you have to go’: understanding sexual agency among young married women in urban South India
Authors: Pande Rohini Prabha , Falle Tina Y. , Rathod Sujit , Edmeades Jeffrey , Krishnan Suneeta
Published: January 2011

Background: Early marriage is common in many developing countries, including India. Women who marry early have little power within their marriage, particularly in the sexual domain. Research is limited on women’s ability to control their marital sexual experiences.
Methods: We identified factors affecting sexual communication among married women aged 16–25, in Bangalore, India, and how factors associated with sexual communication differed from those influencing non-sexual agency. We ran ordered logit regression models for one outcome of sexual agency (sexual communication, n = 735) and two outcomes of non-sexual agency (fertility control, n = 735, and financial decision-making, n = 728).
Results: Sexual communication was more restricted (83 women (11.3%) with high sexual communication) than financial decision-making (183 women (25.1%) with high financial decision-making agency) and fertility control (238 women (32.4%) with high fertility control). Feeling prepared before the first sexual experience was significantly associated with sexual communication (odds ratio (OR) = 1.8; 95% confidence interval (CI) = 1.13–2.89). Longer marriage duration (OR 2.13; 95% CI = 1.42–3.20) and having worked pre-marriage (OR 1.38; 95% CI = 1.02–1.86) were also significant. Few other measures of women’s resources increased their odds of sexual communication. Education, having children, pre-marital vocational training and marital intimacy were significant for non-sexual outcomes but not sexual communication.
Conclusions: Policy-makers seeking to enhance young married women’s sexual communication need to consider providing sex education to young women before they marry. More broadly, interventions designed to increase women’s agency need to be tailored to the type of agency being examined.
Time to clearance of Chlamydia trachomatis ribosomal RNA in women treated for chlamydial infection
Authors: Renault Cybèle A. , Israelski Dennis M. , Levy Vivian , Fujikawa Bruce K. , Kellogg Timothy A. , Klausner Jeffrey D.
Published: January 2011

Background: The dynamics of chlamydia clearance after treatment administration for chlamydial urogenital infection are unknown. We estimated the time to clearance of Chlamydia trachomatis (CT) ribosomal RNA (rRNA) after administration of azithromycin for cervical chlamydial infection using APTIMA Combo 2 (Gen-Probe, Inc., San Diego, CA, USA). Methods: A total of 115 women diagnosed with urogenital chlamydial infection, defined as a positive APTIMA urine or endocervical specimen, were enrolled in the present study. Vaginal swabs on the day of treatment (Day 0) and on Days 3, 7, 10 and 14 after treatment with 1 g of azithromycin were self-obtained by participants. Specimens were tested in a single laboratory. Our analysis was limited to women who were CT-confirmed by vaginal swab at baseline, who returned all follow-up swabs, and who reported sexual abstinence during the follow-up period (n = 61). Results: Among 61 participants, 48 (79%) had a negative APTIMA at Day 14. Subjects with a negative APTIMA at each time-point were as follows: 0/61 (0%) on Day 0, 7/61 (12%) on Day 3, 28/61 (46%) on Day 7, 40/61 (66%) on Day 10, and 48/61 (79%) on Day 14. Multiple linear regression analysis predicted time to clearance at 17 days (95% confidence interval, 16–18 days) after administration of azithromycin. Seventeen of the 94 participants (18.1%) who screened positive for chlamydia had a negative vaginal swab on Day 0, indicating possible spontaneous clearance of CT. Conclusions: After treatment, CT rRNA declined with time. As rRNA was still detectable in 21% of the women 14 days after treatment, APTIMA should not be used as a test-of-cure in the 14-day period following azithromycin administration.
Is Accelerated Partner Therapy partner notification for sexually transmissible infections acceptable and feasible in general practice?
Authors: Shackleton Thomas , Sutcliffe Lorna , Estcourt Claudia
Published: January 2011

Background: Partner notification in primary care is problematic and of limited effectiveness despite enthusiasm from primary care providers to engage with sexually transmissible infection (STI) management. Innovative partner notification strategies must be relevant to the primary care context. The aim of the present study was to explore the opinions of general practitioners (GP) and practice nurses on the acceptability and feasibility of a new form of partner notification developed in the specialist setting known as Accelerated Partner Therapy (APT), for sex partners of those diagnosed with a bacterial STI in general practice. APT is defined as partner notification strategies that reduce time for sex partners to be treated, and include partner assessment by appropriately qualified health care professionals and here involve telephone and community pharmacy assessment. Methods: Semi-structured qualitative interviews were conducted with a purposive sample of GP and practice nurses in East London, UK. Results: All participants appreciated the importance of partner notification in STI management and felt that APT would improve their practice. They supported prioritising antibiotic provision for the sex partners with provision for future comprehensive STI screening. Although both models were acceptable and feasible, the majority preferred the sexual health clinic telephone assessment over the pharmacy model. Conclusions: GP and practice nurses welcome new strategies for partner notification and believe APT could provide rapid and convenient treatment of sex partners in general practice. This supports further evaluation of APT models as a partner notification strategy in primary care.
The importance of striving for greater efficiency
Authors: Fairley Christopher K. , Vodstrcil Lenka A. , Read Tim
Published: January 2011

Health care costs are rising faster than inflation in almost all developed countries. Improving the efficiency of health care will go some way to address this issue. There has been a significant improvement in the delivery of sexual health care with a particular focus on innovation. In this issue, Baraitser et al. evaluate their services, that uses computer-assisted interviewing combined with self-collected samples in London. This editorial discusses this service in the context of the control of sexually transmissible infections and other recent health care innovations.
2D luminescence imaging of pH in vivo
Authors: Schreml Stephan , Meier Robert J. , Wolfbeis Otto S. , Landthaler Michael , Szeimies Rolf-Markus , Babilas Philipp
Published: January 2011

Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields.
Fast and accurate decisions through collective vigilance in fish shoals
Authors: Ward Ashley J. W. , Herbert-Read James E. , Sumpter David J. T. , Krause Jens
Published: January 2011

Although it has been suggested that large animal groups should make better decisions than smaller groups, there are few empirical demonstrations of this phenomenon and still fewer explanations of the how these improvements may be made. Here we show that both speed and accuracy of decision making increase with group size in fish shoals under predation threat. We examined two plausible mechanisms for this improvement: first, that groups are guided by a small proportion of high-quality decision makers and, second, that group members use self-organized division of vigilance. Repeated testing of individuals showed no evidence of different decision-making abilities between individual fish. Instead, we suggest that shoals achieve greater decision-making efficiencies through division of labor combined with social information transfer. Our results should prompt reconsideration of how we view cooperation in animal groups with fluid membership.
Impacts of climate change on the world's most exceptional ecoregions
Authors: Beaumont Linda J. , Pitman Andrew , Perkins Sarah , Zimmermann Niklaus E. , Yoccoz Nigel G. , Thuiller Wilfried
Published: January 2011

The current rate of warming due to increases in greenhouse gas (GHG) emissions is very likely unprecedented over the last 10,000 y. Although the majority of countries have adopted the view that global warming must be limited to <2 °C, current GHG emission rates and nonagreement at Copenhagen in December 2009 increase the likelihood of this limit being exceeded by 2100. Extensive evidence has linked major changes in biological systems to 20th century warming. The “Global 200” comprises 238 ecoregions of exceptional biodiversity [Olson DM, Dinerstein E (2002)
Ann Mo Bot Gard
89:199–224]. We assess the likelihood that, by 2070, these iconic ecoregions will regularly experience monthly climatic conditions that were extreme in 1961–1990. Using >600 realizations from climate model ensembles, we show that up to 86% of terrestrial and 83% of freshwater ecoregions will be exposed to average monthly temperature patterns >2 SDs (2σ) of the 1961–1990 baseline, including 82% of critically endangered ecoregions. The entire range of 89 ecoregions will experience extreme monthly temperatures with a local warming of <2 °C. Tropical and subtropical ecoregions, and mangroves, face extreme conditions earliest, some with <1 °C warming. In contrast, few ecoregions within Boreal Forests and Tundra biomes will experience such extremes this century. On average, precipitation regimes do not exceed 2σ of the baseline period, although considerable variability exists across the climate realizations. Further, the strength of the correlation between seasonal temperature and precipitation changes over numerous ecoregions. These results suggest many Global 200 ecoregions may be under substantial climatic stress by 2100.
Interleukin-2 inhibits FMS-like tyrosine kinase 3 receptor ligand (flt3L)-dependent development and function of conventional and plasmacytoid dendritic cells
Authors: Lau-Kilby Annie W. , Kretz Cosima C. , Pechhold Susanne , Price Jeffrey D. , Dorta Stephanie , Ramos Haydee , Trinchieri Giorgio , Tarbell Kristin V.
Published: January 2011

Steady-state development of plasmacytoid dendritic cells (pDCs) and conventional dendritic cells (cDCs) requires the ligand for FMS-like tyrosine kinase 3 receptor (flt3L), but little is known about how other cytokines may also control this process. In this study, we show that IL-2 inhibits the development of both pDCs and cDCs from bone marrow cells under flt3L stimulation, by acting on lineage
−
flt3
+
precursors. This inhibition of DC development by IL-2 requires IL-2Rα and IL2Rβ. IL-2Rα is specifically expressed in one stage of the DC precursor: the monocyte and DC progenitors (MDPs). Furthermore, more MDPs are found in flt3L-stimulated bone marrow cultures when IL-2 is present, suggesting that IL-2 may be inhibiting DC development at the MDP stage. Consistent with our in vitro findings, we observe that nonobese diabetic (NOD) mice, which express less IL-2 compared with diabetes-resistant NOD.
Idd3/5
mice, have more splenic pDCs. Additionally, DCs developed in vitro in the presence of flt3L and IL-2 display reduced ability to stimulate T-cell proliferation compared with DCs developed in the presence of flt3L alone. Although the addition of IL-2 does not increase the apoptosis of DCs during their development, DCs developed in the presence of IL-2 are more prone to apoptosis upon interaction with T cells. Together our data show that IL-2 can inhibit both the development and the function of DCs. This pathway may have implications for the loss of immune tolerance: Reduced IL-2 signaling may lead to increased DC number and T-cell stimulatory capacity.
A gradient of childhood self-control predicts health, wealth, and public safety
Authors: Moffitt Terrie E. , Arseneault Louise , Belsky Daniel , Dickson Nigel , Hancox Robert J. , Harrington HonaLee , Houts Renate , Poulton Richie , Roberts Brent W. , Ross Stephen , Sears Malcolm R. , Thomson W. Murray , Caspi Avshalom
Published: January 2011

Policy-makers are considering large-scale programs aimed at self-control to improve citizens’ health and wealth and reduce crime. Experimental and economic studies suggest such programs could reap benefits. Yet, is self-control important for the health, wealth, and public safety of the population? Following a cohort of 1,000 children from birth to the age of 32 y, we show that childhood self-control predicts physical health, substance dependence, personal finances, and criminal offending outcomes, following a gradient of self-control. Effects of children's self-control could be disentangled from their intelligence and social class as well as from mistakes they made as adolescents. In another cohort of 500 sibling-pairs, the sibling with lower self-control had poorer outcomes, despite shared family background. Interventions addressing self-control might reduce a panoply of societal costs, save taxpayers money, and promote prosperity.
Land inheritance establishes sibling competition for marriage and reproduction in rural Ethiopia
Authors: Gibson Mhairi A. , Gurmu Eshetu
Published: January 2011

Intergenerational transfer of wealth has been proposed as playing a pivotal role in the evolution of human sibling relationships. Sibling rivalry is assumed to be more marked when offspring compete for limited heritable resources, which are crucial for reproductive success (e.g., land and livestock); whereas in the absence of heritable wealth, related siblings may cooperate. To date, comparative studies undertaken to support this evolutionary assumption have been confounded by other socioecological factors, which vary across populations, e.g., food sharing and intergroup conflict. In this article we explore effects of sibling competition and cooperation for agricultural resources, marriage, and reproduction in one contemporary Ethiopian agropastoralist society. Here recent changes in land tenure policy, altering transfers of land from parents to offspring, present a unique framework to test the importance of intergenerational transfers of wealth in driving sibling competition, while controlling for socioeconomic biases. In households where land is inherited, the number of elder brothers reduces a man's agricultural productivity, marriage, and reproductive success, as resources diminish and competition increases with each additional sibling. Where land is not inherited (for males receiving land directly from the government and all females) older siblings do not have a competitive effect and in some instances may be beneficial. This study has wider implications for the evolution of human family sizes. Recent changes in wealth transfers, which have driven sibling competition, may be contributing to an increased desire for smaller family sizes.
Experimental selection of hypoxia-tolerant
Drosophila melanogaster
Authors: Zhou Dan , Udpa Nitin , Gersten Merril , Visk DeeAnn W. , Bashir Ali , Xue Jin , Frazer Kelly A. , Posakony James W. , Subramaniam Shankar , Bafna Vineet , Haddad Gabriel G.
Published: January 2011

Through long-term laboratory selection (over 200 generations), we have generated
Drosophila melanogaster
populations that tolerate severe, normally lethal, levels of hypoxia. Because of initial experiments suspecting genetic mechanisms underlying this adaptation, we compared the genomes of the hypoxia-selected flies with those of controls using deep resequencing. By applying unique computing and analytical methods we identified a number of DNA regions under selection, mostly on the X chromosome. Several of the hypoxia-selected regions contained genes encoding or regulating the Notch pathway. In addition, previous expression profiling revealed an activation of the Notch pathway in the hypoxia-selected flies. We confirmed the contribution of Notch activation to hypoxia tolerance using a specific γ-secretase inhibitor, N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), which significantly reduced adult survival and life span in the hypoxia-selected flies. We also demonstrated that flies with loss-of-function Notch mutations or RNAi-mediated Notch knockdown had a significant reduction in hypoxia tolerance, but those with a gain-of-function had a dramatic opposite effect. Using the UAS-Gal4 system, we also showed that specific overexpression of the Notch intracellular domain in glial cells was critical for conferring hypoxia tolerance. Unique analytical tools and genetic and bioinformatic strategies allowed us to discover that Notch activation plays a major role in this hypoxia tolerance in
Drosophila melanogaster
.
Genome and transcriptome analyses of the mountain pine beetle-fungal symbiont
Grosmannia clavigera
, a lodgepole pine pathogen
Authors: DiGuistini Scott , Wang Ye , Liao Nancy Y. , Taylor Greg , Tanguay Philippe , Feau Nicolas , Henrissat Bernard , Chan Simon K. , Hesse-Orce Uljana , Alamouti Sepideh Massoumi , Tsui Clement K. M. , Docking Roderick T. , Levasseur Anthony , Haridas Sajeet , Robertson Gordon , Birol Inanc , Holt Robert A. , Marra Marco A. , Hamelin Richard C. , Hirst Martin , Jones Steven J. M. , Bohlmann Jörg , Breuil Colette
Published: January 2011

In western North America, the current outbreak of the mountain pine beetle (MPB) and its microbial associates has destroyed wide areas of lodgepole pine forest, including more than 16 million hectares in British Columbia.
Grosmannia clavigera
(
Gc
), a critical component of the outbreak, is a symbiont of the MPB and a pathogen of pine trees. To better understand the interactions between
Gc
, MPB, and lodgepole pine hosts, we sequenced the ∼30-Mb
Gc
genome and assembled it into 18 supercontigs. We predict 8,314 protein-coding genes, and support the gene models with proteome, expressed sequence tag, and RNA-seq data. We establish that
Gc
is heterothallic, and report evidence for repeat-induced point mutation. We report insights, from genome and transcriptome analyses, into how
Gc
tolerates conifer-defense chemicals, including oleoresin terpenoids, as they colonize a host tree. RNA-seq data indicate that terpenoids induce a substantial antimicrobial stress in
Gc
, and suggest that the fungus may detoxify these chemicals by using them as a carbon source. Terpenoid treatment strongly activated a ∼100-kb region of the
Gc
genome that contains a set of genes that may be important for detoxification of these host-defense chemicals. This work is a major step toward understanding the biological interactions between the tripartite MPB/fungus/forest system.
Rack1 is required for Vangl2 membrane localization and planar cell polarity signaling while attenuating canonical Wnt activity
Authors: Li Shuangding , Esterberg Robert , Lachance Veronik , Ren Dongdong , Radde-Gallwitz Kristen , Chi Fanglu , Parent Jean-Luc , Fritz Andreas , Chen Ping
Published: January 2011

The vertebrate planar cell polarity (PCP) pathway shares molecular components with the β-catenin–mediated canonical Wnt pathway but acts through membrane complexes containing Vang or Frizzled to orient neighboring cells coordinately. The molecular interactions underlying the action of Vang in PCP signaling and specification, however, are yet to be delineated. Here, we report the identification of Rack1 as an interacting protein of a vertebrate Vang protein, Vangl2. We demonstrate that Rack1 is required in zebrafish for PCP-regulated processes, including oriented cell division, cellular polarization, and convergent extension during gastrulation. We further show that the knockdown of Rack1 affects membrane localization of Vangl2 and that the Vangl2-interacting domain of Rack1 has a dominant-negative effect on Vangl2 localization and gastrulation. Moreover, Rack1 antagonizes canonical Wnt signaling. Together, our data suggest that Rack1 regulates the localization of an essential PCP protein and acts as a molecular switch to promote PCP signaling.